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  • Management Approach of Penetrating Vertebral Artery Injury With Concomitant Cervical Nerve Root Injury in Regional Hospital: Report of Two Cases
    16 janvier 2018
    Publication date: December 2018
    Source:Journal of Orthopaedics, Trauma and Rehabilitation, Volume 25

    Author(s): Yuk-Yu Lam, Hon-For Tsui, Hok-Leung Wong, Yuk-Yin Chow

    Penetrating vertebral artery injury is uncommon yet potentially fatal. We present two cases of penetrating vertebral artery injury with concomitant cervical nerve root injury managed in our centre. The first case was a young gentleman who suffered from neck injury by broken metal fragment. Cervical nerve root injury was suspected preoperatively. Massive bleeding from vertebral artery was encountered during wound exploration. It was managed by ligation, followed by retrograde endovascular embolisation. The second case was a young lady being assaulted with knife and fork over the neck. She was also suspected to have cervical nerve root injury preoperatively. Vascular control of vertebral artery was achieved with endovascular intervention. Subsequent operation for foreign body removal and nerve root repair was performed with minimal bleeding intraoperatively. Management approach of penetrating vertebral artery injury with concomitant cervical nerve root injury and the role of endovascular intervention were discussed.





  • Reverse-engineering organogenesis through feedback loops between model systems
    16 janvier 2018
    Publication date: August 2018
    Source:Current Opinion in Biotechnology, Volume 52

    Author(s): Cody Narciso, Jeremiah Zartman

    Biological complexity and ethical limitations necessitate models of human development. Traditionally, genetic model systems have provided inexpensive routes to define mechanisms governing organ development. Recent progress has led to 3D human organoid models of development and disease. However, robust methods to control the size and morphology of organoids for high throughput studies need to be developed. Additionally, insights from multiple developmental contexts are required to reveal conserved genes and processes regulating organ growth and development. Positive feedback between quantitative studies using mammalian organoids and insect micro-organs enable identification of underlying principles for organ size and shape control. Advances in the field of multicellular systems engineering are enabling unprecedented high-content studies in developmental biology and disease modeling. These will lead to fundamental advances in regenerative medicine and tissue-engineered soft robotics.





  • Environmental xenobiotic exposure and autoimmunity
    16 janvier 2018
    Publication date: August 2018
    Source:Current Opinion in Toxicology, Volume 10

    Author(s): K. Michael Pollard, Joseph M. Christy, David M. Cauvi, Dwight H. Kono

    Susceptibility to autoimmune diseases is dependent on multigenic inheritance, environmental factors, and stochastic events. Although there has been substantial progress in identifying predisposing genetic variants, a significant challenge facing autoimmune disease research is the identification of the specific events that trigger loss of tolerance, autoreactivity and ultimately autoimmune disease. Accordingly, studies have indicated that a wide range of extrinsic factors including drugs, chemicals, microbes, and other environmental factors can induce autoimmunity, particularly systemic autoimmune diseases such as lupus. This review describes a class of environmental factors, namely xenobiotics, epidemiologically linked to human autoimmunity. Mechanisms of xenobiotic autoimmune disease induction are discussed in terms of human and animal model studies with a focus on the role of inflammation and the innate immune response. We argue that localized tissue damage and chronic inflammation elicited by xenobiotic exposure leads to the release of self-antigens and damage-associated molecular patterns as well as the appearance of ectopic lymphoid structures and secondary lymphoid hypertrophy, which provide a milieu for the production of autoreactive B and T cells that contribute to the development and persistence of autoimmunity in predisposed individuals.





  • Comparative diagnostic accuracy of dual-energy CT myocardial perfusion imaging by monochromatic energy versus material decomposition methods
    16 janvier 2018
    Publication date: July–August 2018
    Source:Clinical Imaging, Volume 50

    Author(s): Ibrahim Danad, Iksung Cho, Kimberly Elmore, Joshua Schulman-Marcus, Bríain ó Hartaigh, Wijnand J. Stuijfzand, Patricia Carrascosa, James K. Min

    Purpose To compare the diagnostic value of monochromatic and material decomposition (MD) dual- energy computed tomography (DECT) imaging for the evaluation of ischemia. Methods Patients with suspected coronary artery disease underwent rest-stress DECT and SPECT perfusion imaging. DECT images were reconstructed between 40 and 140keV and through MD of iodine/muscle. Results MD and monochromatic imaging had a sensitivity, specificity, negative predictive, positive predictive value, and accuracy of 89%, 40%, 67%, 73% and 71%; and 91%, 67%, 67%, 91% and 86%, respectively (p =0.05). Conclusion DECT using monochromatic energy displayed a non-significantly higher diagnostic accuracy for myocardial ischemia as compared with DECT MD.





  • The short esophagus: Review of a neglected entity
    16 janvier 2018
    Publication date: July–August 2018
    Source:Clinical Imaging, Volume 50

    Author(s): Arwa A. Alzaghal, Rida Salman, Ghina Berjawi, Maurice Haddad, Lena Naffaa

    In this pictorial essay, the authors discuss etiologies, imaging findings with focus on fluoroscopy and management of the short esophagus in children and adults.





  • Vaginal delivery-related changes in the pelvic organ position and vaginal cross-sectional area in the general population
    16 janvier 2018
    Publication date: July–August 2018
    Source:Clinical Imaging, Volume 50

    Author(s): Shotaro Naganawa, Eriko Maeda, Akifumi Hagiwara, Shiori Amemiya, Wataru Gonoi, Shouhei Hanaoka, Takeharu Yoshikawa, Kuni Ohtomo

    Purpose Evaluate the effect of vaginal delivery on pelvic organ positions and vaginal cross-sectional areas. Methods MRI of 119 premenopausal women were grouped according to the number of deliveries. The distances from the three 3-reference points (bladder, uterus, and rectum) to two 2-lines (pubococcygeal-line (PCL) and midpubic-line (MPL)), length of H- and M-lines and vaginal cross-sectional area were compared between the groups. Results With increasing parity, distance from the rectum to PCL tended to increase (nullipara vs. bipara; p <0.01). Vaginal cross-sectional area was larger in bipara and tripara than in nullipara (p <0.01). Conclusions Rectal position is more caudally located and vaginal cross-sectional area is larger in bipara than in nullipara.





  • Cystic mediastinal masses and the role of MRI
    16 janvier 2018
    Publication date: July–August 2018
    Source:Clinical Imaging, Volume 50

    Author(s): Rachna Madan, Lisa Ratanaprasatporn, Linda Ratanaprasatporn, Brett W. Carter, Jeanne B. Ackman

    While some cystic masses can be definitively diagnosed on CT, others remain indeterminate. Because of its intrinsic superior soft tissue resolution, MR is an important tool in the evaluation of select mediastinal masses that are incompletely characterized on CT. This review describes how non-vascular MR provides greater diagnostic precision in the evaluation of indeterminate cystic mediastinal masses on CT. It also emphasizes key MR pulse sequences for optimal evaluation of problematic mediastinal masses.





  • Long-term outcomes after percutaneous renal cryoablation performed with adjunctive techniques
    16 janvier 2018
    Publication date: July–August 2018
    Source:Clinical Imaging, Volume 50

    Author(s): Faraz Khan, Andrew M. Ho, Joseph E. Jamal, Meyer D. Gershbaum, Aaron E. Katz, Jason C. Hoffmann

    Objective To review the technical success of image-guided percutaneous cryoablation of renal masses in difficult anatomic locations using adjunctive techniques to displace critical structures away from the ablation zone, while also reporting longer-term outcomes within this patient population. Methods An IRB approved, retrospective analysis of 92 renal masses treated with percutaneous cryoablation revealed 15 cases utilizing adjunctive techniques. Tumor size and distance to adjacent organ before and after adjunctive technique and long-term outcomes were evaluated. Results The adjunctive techniques used were hydrodissection (n =15) and angioplasty balloon interposition (n=1). Before and after adjunctive technique, median tumor proximity to closest organ was 4mm and 26mm, respectively. All cases had appropriate ablation zones and protection of adjacent critical structures. There is no evidence of recurrence or complication on follow-up (median 51months). Conclusions Adjunctive techniques to ablate renal masses in difficult locations provide technical success, safety, and favorable long-term outcomes.





  • Collision of the glass shards with the eye: A computational fluid-structure interaction model
    16 janvier 2018
    Publication date: July 2018
    Source:Journal of Chemical Neuroanatomy, Volume 90

    Author(s): Alireza Karimi, Reza Razaghi, Hasan Biglari, Toshihiro Sera, Susumu Kudo

    The main stream of blunt trauma injuries has been reported to be related to the automobile crashes, sporting activities, and military operations. Glass shards, which can be induced due to car accident, earthquake, gunshot, etc., might collide with the eye and trigger substantial scarring and, consequently, permanently affect the vision. The complications as a result of the collision with the eye and its following injuries on each component of the eye are difficult to be diagnosed. The objective of this study was to employ a Three-Dimensional (3D) computational Fluid-Structure Interaction (FSI) model of the human eye to assess the results of the glass shards collision with the eye. To do this, a rigid steel-based object hit a Smoothed-Particle Hydrodynamics (SPH) glass wall at the velocities of 100, 150, and 200 m/s and, subsequently, the resultant glass shards moved toward the eye. The amount of injury, then, quantified in terms of the stresses and strains. The results revealed the highest amount of stress in the cornea while the lowest one was observed in the vitreous body. It was also found that increasing the speed of the glass shards amplifies the amount of the stress in the components which are located in the central anterior zone of the eye, such as the cornea, aqueous body, and iris. However, regarding those components located in the peripheral/posterior side of the eye, especially the optic nerve, by increasing the amount of velocity a reduction in the stresses was observed and the optic nerve is hardly damaged. These findings have associations not only for understanding the amount of stresses/strains in the eye components at three different velocities, but also for providing preliminary information for the ophthalmologists to have a better diagnosis after glass shards (small objects impact) injuries to the eye.





  • Differential proteomic analysis to identify proteins associated with quality traits of frozen mud shrimp (Solenocera melantho) using an iTRAQ-based strategy
    16 janvier 2018
    Publication date: 15 June 2018
    Source:Food Chemistry, Volume 251

    Author(s): Jing Shi, Longteng Zhang, Yutian Lei, Huixing Shen, Xunpei Yu, Yongkang Luo

    An iTRAQ-based strategy was applied to investigate proteome changes in mud shrimp during long-term frozen storage under different conditions. A total of 226 proteins was identified as differential abundance proteins (DAPs) in mud shrimp from two frozen treatment groups (−20 °C and −40 °C) compared with the fresh control group. The proteome changes in mud shrimp muscle stored under −20 °C was much greater than that under −40 °C. Correlation analysis between DAPs and quality traits of mud shrimp muscle showed that 12 proteins were correlated closely with color (L , a , and b value) and texture (hardness, elasticity, and chewiness). Bioinformatic analysis revealed that most of these proteins were involved in protein structure, metabolic enzymes, and protein turnover. Among them, several proteins might be potential protein markers for color, and some proteins are good candidate predictors for textural properties of mud shrimp muscle.





  • Improved collagen extraction from jellyfish (Acromitus hardenbergi) with increased physical-induced solubilization processes
    16 janvier 2018
    Publication date: 15 June 2018
    Source:Food Chemistry, Volume 251

    Author(s): Nicholas M.H. Khong, Fatimah Md. Yusoff, B. Jamilah, Mahiran Basri, I. Maznah, Kim Wei Chan, Nurdin Armania, Jun Nishikawa

    Efficiency and effectiveness of collagen extraction process contribute to huge impacts to the quality, supply and cost of the collagen produced. Jellyfish is a potential sustainable source of collagen where their applications are not limited by religious constraints and threats of transmittable diseases. The present study compared the extraction yield, physico-chemical properties and toxicology in vitro of collagens obtained by the conventional acid-assisted and pepsin-assisted extraction to an improved physical-aided extraction process. By increasing physical intervention, the production yield increased significantly compared to the conventional extraction processes (p < .05). Collagen extracted using the improved process was found to possess similar proximate and amino acids composition to those extracted using pepsin (p > .05) while retaining high molecular weight distributions and polypeptide profiles similar to those extracted using only acid. Moreover, they exhibited better appearance, instrumental colour and were found to be non-toxic in vitro and free of heavy metal contamination.

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  • Universal Method for the Purification of Recombinant AAV Vectors of Differing Serotypes
    16 janvier 2018
    Publication date: 15 June 2018
    Source:Molecular Therapy - Methods & Clinical Development, Volume 9

    Author(s): Shelley A. Nass, Maryellen A. Mattingly, Denise A. Woodcock, Brenda L. Burnham, Jeffrey A. Ardinger, Shayla E. Osmond, Amy M. Frederick, Abraham Scaria, Seng H. Cheng, Catherine R. O’Riordan

    The generation of clinical good manufacturing practices (GMP)-grade adeno-associated virus (AAV) vectors requires purification strategies that support the generation of vectors of high purity, and that exhibit a good safety and efficacy profile. To date, most reported purification schemas are serotype dependent, requiring method development for each AAV gene therapy product. Here, we describe a platform purification process that is compatible with the purification of multiple AAV serotypes. The method generates vector preparations of high purity that are enriched for capsids with full vector genomes, and that minimizes the fractional content of empty capsids. The two-column purification method, a combination of affinity and ion exchange chromatographies, is compatible with a range of AAV serotypes generated by either the transient triple transfection method or the more scalable producer cell line platform. In summary, the adaptable purification method described can be used for the production of a variety of high-quality AAV vectors suitable for preclinical testing in animal models of diseases.





  • Review with novel markers facilitates precise categorization of 41 cases of diagnostically challenging, “undifferentiated small round cell tumors”. A clinicopathologic, immunophenotypic and molecular analysis
    16 janvier 2018
    Publication date: June 2018
    Source:Annals of Diagnostic Pathology, Volume 34

    Author(s): Isidro Machado, Akihiko Yoshida, María Gema Nieto Morales, Lucas Faria Abrahão-Machado, Samuel Navarro, Julia Cruz, Javier Lavernia, Antonina Parafioriti, Piero Picci, Antonio Llombart-Bosch

    Background Despite extensive immunohistochemical (IHC) and molecular studies combined with morphologic findings, a group of round/ovoid cell tumors histologically similar to Ewing sarcomas (ES) but lacking EWSR1-rearrangements may remain unclassifiable. Design We retrospectively analyzed 41 Ewing-like tumors (formalin-fixed, paraffin-embedded) previously determined as negative or non-informative for EWSR1-rearrangements by FISH and/or RT-PCR. A new histopathology revision and additional IHC and molecular analyses were carried out in order to investigate whether additional IHC and/or molecular testing in combination with the morphological findings may help in reaching a definitive diagnosis. Results Almost all the tumors (n =40) involved soft tissue and/or bone and half the patients died of disease. In the archival cases all diagnoses were Ewing sarcoma (ES), Ewing-like sarcoma (ELS), myoepithelial tumor and undifferentiated sarcoma (US). In the new review all the tumors were re-classified as, ES (n =16), Ewing-like tumor with EWSR1 rearrangement and amplification and possible EWSR1-NFATC2 gene fusion (n=1), CIC-rearranged sarcomas or undifferentiated sarcoma, most consistent with CIC-rearranged sarcoma (n =7), sarcoma with BCOR-alteration or undifferentiated sarcoma, consistent with BCOR-associated sarcoma (n =3), neuroblastoma (n =2), unclassifiable neoplasm with neuroblastic differentiation (n =1), malignant rhabdoid tumor (n=2), lymphoblastic lymphoma (n =1), clear cell sarcoma of the gastrointestinal tract (n =1), small cell carcinoma (n=1), sclerosing rhabdomyosarcoma (n =1), desmoplastic small round cell tumor (n=1), malignant peripheral sheath nerve tumor (n =1), poorly-differentiated synovial sarcoma (n =1), Possible gastrointestinal stromal tumor/GIST with predominant round cells (n=1) and possible SMARCA4-deficient-sarcoma (n=1). NKX2.2, ETV4 and BCOR immunoreactivity was observed in all ES, CIC-rearranged sarcomas and sarcomas with BCOR alteration, respectively. CIC-rearrangement by FISH was observed in many of the CIC-rearranged sarcomas. Conclusion Our analysis of 41 Ewing-like tumors confirms that there may be a significant pathological and IHC overlap among Ewing-like tumors, with prognostic and therapeutic impacts. Additional IHC (NKX2.2, ETV4 and BCOR) and molecular studies including FUS, CIC or BCOR analysis may support the final diagnosis when FISH or RT-PCR fail to detect EWSR1-rearrangements. Any molecular findings should always be interpreted in relation to the specific clinical and pathological context.





  • Isoprostanes as markers for muscle aging in older athletes
    16 janvier 2018
    Publication date: June 2018
    Source:Biochimie Open, Volume 6

    Author(s): Claire Vinel, Ophélie Pereira, Aude Dupuy, Justine Bertrand-Michel, Dalila Laoudj-Chenivesse, Yves Rolland, Daniel Rivière, Philippe Valet, Cédric Dray, Fabien Pillard

    Introduction Production of isoprostanes (IsoPs) is enhanced after acute, intense, and prolonged exercise, in untrained subjects. This effect is greater in older subjects. The present study aims to delineate the profile of acute-exercise-induced IsoPs levels in young and older endurance-trained subjects. Methods All included subjects were male, young (n = 6; 29 yrs ± 5.7) or older (n = 6; 63.7 yrs ± 2.3), and competitors. The kinetics of F2-IsoPs in blood-sera was assessed at rest, for the maximal aerobic exercise power (MAP) corresponding to the cardio-respiratory fitness index and after a 30-min recovery period. Results No significant time effect on F2-IsoPs kinetics was identified in young subjects. However, in older athletes, F2-IsoPs blood-concentrations at the MAP were higher than at rest, whereas these blood-concentrations did not differ between rest and after the 30-min recovery period. Conclusion Because plasma glutathione (GSH) promotes the formation of some F2-IsoPs, we suggest that the surprising decrease in F2-IsoPs levels in older subjects would be caused by decreased GSH under major ROS production in older subjects. We argue that the assessment F2-IsoPs in plasma as biomarkers of the aging process should be challenged by exercise to improve the assessment of the functional response against reactive oxygen species in older subjects.





  • Decisive differences in the bone repair processes of the metaphysis and diaphysis in young mice
    16 janvier 2018
    Publication date: June 2018
    Source:Bone Reports, Volume 8

    Author(s): Satoshi Inoue, Hirotada Otsuka, Jiro Takito, Masanori Nakamura

    Fractures are common traumatic injuries that mainly occur in the metaphyses of long bones such as the proximal humerus, distal radius, and proximal femur. However, most studies of fracture repair processes have focused on the diaphyseal region. In this study, we compared the bone repair processes of the metaphysis and the diaphysis of the mouse tibia. Bone apertures were formed in the tibial metaphysis and diaphysis. At indicated times after surgery, samples were collected, and the healing process was investigated using micro-computed tomography, as well as histological, immunohistochemical, and mRNA expression analyses. In the metaphysis, cartilage formation was not detected on the periosteal side. The bone aperture was filled with newly formed bone produced from bone marrow at day 7. In the case of the diaphysis, cartilage was formed around the aperture at day 4 and sequentially replaced by bone on the periosteal side. The bone aperture was filled with newly formed bone at day 14. In the bone marrow, expression of the osteogenic markers such as alkaline phosphatase, osteocalcin, and type I collagen, appeared earlier with metaphyseal injury than with diaphyseal injury. The mRNA expression of chondrogenesis markers was markedly upregulated in the diaphysis compared with that in the metaphysis on the periosteal side. These results indicate differences in the bone repair processes of the two regions, suggesting functional heterogeneity of the periosteum and bone marrow mesenchymal cells in response to bone fractures.





  • The effect of oral dabigatran etexilate on bone density, strength, and microstructure in healthy mice
    16 janvier 2018
    Publication date: June 2018
    Source:Bone Reports, Volume 8

    Author(s): Mikkel Bo Brent, Jesper Skovhus Thomsen, Annemarie Brüel

    Thrombin is a key component in the coagulation cascade where it converts factor V, VIII, XI, and fibrinogen. In addition to the abundant production of thrombin in the liver, osteoclasts synthesize and secrete thrombin as well. Osteoblasts express thrombin receptors, and it has been reported that thrombin stimulates the expression of RANKL relatively to OPG, resulting in greater osteoclast activation and bone degradation. Pradaxa (dabigatran etexilate, DE) is a new anticoagulant, which has recently been approved for clinical use. DE is a direct thrombin inhibitor with potential to modulate the RANKL/OPG ratio and thereby limit osteoclast activation and bone degradation. The purpose of the study was to investigate whether DE can increase bone density, bone strength, and bone microstructure in healthy male and female mice and to investigate whether the effect of DE is sex-dependent. Twenty-eight 14-week-old male C57BL/6 mice were stratified by weight into 4 groups: 1. Control 3weeks; 2. DE 3weeks; 3. Control 6weeks; 4. DE 6weeks. An identical study design was applied to twenty-four 14-week-old female C57BL/6 mice. Chow mixed with DE was offered ad libitum, resulting in a dose of 1.70mgDE/g body weight and 1.52mgDE/g body weight, to female and male mice, respectively. The animals were euthanized after 3 or 6weeks. Bone mineral density (aBMD) and bone mineral content (BMC) were evaluated with DEXA, 3D microstructural properties were determined with μCT, bone strength was determined with mechanical testing, and bone formation and resorption was evaluated with bone histomorphometry. In female mice, DE resulted in significant higher tibial aBMD values after 6weeks of intervention. Furthermore, DE significantly increased tibial diaphyseal cortical bone area and tissue area, which was accompanied by significantly increased strength of the tibial shaft. DE had no effect on femoral cortical bone or on femoral and vertebral trabecular 3D microstructure. Finally, bone histomorphometry showed that DE had no effect on MS/BS or Oc.S/BS. In male mice, no bone positive effects of DE were found in any of the parameters investigated. In conclusion, intervention with DE may result in a weak positive site specific effect at tibial cortical bone in female mice, and importantly, no major deleterious effects of DE on bone tissue were seen in either female or male mice despite the relatively high dose of DE used.





  • Constraints and flexibility during vocal development: insights from marmoset monkeys
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Behavioral Sciences, Volume 21

    Author(s): Asif A Ghazanfar, Diana A Liao

    Human vocal development is typically conceived as a sequence of two processesan early maturation phase where vocal sounds change as a function of body growth (‘constraints’) followed by a period during which social experience can influence vocal sound production (‘flexibility’). However, studies of other behaviors (e.g., locomotion) reveal that growth and experience are interactive throughout development. As it turns out, vocal development is not exceptional; it is also the on-going result of the interplay between an infant's growing biological system of production (the body and the nervous system) and experience with caregivers. Here, we review work on developing marmoset monkeysa species that exhibits strikingly similar vocal developmental processes to those of prelinguistic human infantsthat demonstrates how constraints and flexibility are parallel and interactive processes.





  • Connectivity and the search for specializations in the language-capable brain
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Behavioral Sciences, Volume 21

    Author(s): Rogier B Mars, Nicole Eichert, Saad Jbabdi, Lennart Verhagen, Matthew F.S. Rushworth

    The search for the anatomical basis of language has traditionally been a search for specializations. More recently such research has focused both on aspects of brain organization that are unique to humans and aspects shared with other primates. This work has mostly concentrated on the architecture of connections between brain areas. However, as specializations can take many guises, comparison of anatomical organization across species is often complicated. We demonstrate how viewing different types of specializations within a common framework allows one to better appreciate both shared and unique aspects of brain organization. We illustrate this point by discussing recent insights into the anatomy of the dorsal language pathway to the frontal cortex and areas for laryngeal control in the motor cortex.





  • Regeneration mechanism for skin and peripheral nerves clarified at the organ and molecular scales
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Biomedical Engineering, Volume 6

    Author(s): Ioannis V. Yannas, Dimitrios S. Tzeranis, Peter T.C. So

    This article is a review of current research on the mechanism of regeneration of skin and peripheral nerves based on use of collagen scaffolds, particularly the dermis regeneration template (DRT), which is widely used clinically. DRT modifies the normal wound healing process, converting it from wound closure by contraction and scar formation to closure by regeneration. DRT achieves this modification by blocking wound contraction, which spontaneously leads to cancellation of scar formation, a process secondary to contraction. Contraction blocking by DRT is the result of a dramatic phenotype change in contractile cells (myofibroblasts, MFB) which follows specific binding of integrins α1β1 and α2β1 onto hexapeptide ligands, probably GFOGER and GLOGER, that are naturally present on the surface of collagen fibers in DRT. The methodology of organ regeneration based on use of DRT has been recently extended from traumatized skin to diseased skin. Successful extension of the method to other organs in which wounds heal by contraction is highly likely though not yet attempted. This regenerative paradigm is much more advanced both in basic mechanistic understanding and clinical use than methods based on tissue culture or stem cells. It is also largely free of risk and has shown decisively lower morbidity and lower cost than organ transplantation.





  • Re-engineering of protein motors to understand mechanisms biasing random motion and generating collective dynamics
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Biotechnology, Volume 51

    Author(s): Ken’ya Furuta, Akane Furuta

    A considerable amount of insight into the mechanisms of protein-based biomolecular motors has been accumulated over decades of research. However, our knowledge about the design principles of these motors is still limited. Even less is known about the design of multi-motor systems that perform various functions within the cell. Here we focus on constructive (or synthetic) approaches to biomolecular motors that could make a breakthrough in our understanding. Recent achievements include studies at different hierarchical levels of complexity: re-engineering of individual motors, construction of multi-motor systems, and generation of large-scale complex behaviour. We then propose a strategy where the collective behaviour can be repeatedly tested upon modifying individual motors, which may provide important clues about how biomolecular motors and their systems are designed.

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  • Messages from the voices within: regulation of signaling by proteins of the nuclear lamina
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Cell Biology, Volume 52

    Author(s): Larry Gerace, Olga Tapia

    The nuclear lamina (NL) is a protein scaffold lining the nuclear envelope that consists of nuclear lamins and associated transmembrane proteins. It helps to organize the nuclear envelope, chromosomes, and the cytoplasmic cytoskeleton. The NL also has an important role in regulation of signaling, as highlighted by the wide range of human diseases caused by mutations in the genes for NL proteins with associated signaling defects. This review will consider diverse mechanisms for signaling regulation by the NL that have been uncovered recently, including interaction with signaling effectors, modulation of actin assembly and compositional alteration of the NL. Cells with discrete NL mutations often show disruption of multiple signaling pathways, however, and for the most part the mechanistic basis for these complex phenotypes remains to be elucidated.





  • Sphingolipids in host–microbial interactions
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Microbiology, Volume 43

    Author(s): Stacey L Heaver, Elizabeth L Johnson, Ruth E Ley

    Sphingolipids, a lipid class characterized by a long-chain amino alcohol backbone, serve vital structural and signaling roles in eukaryotes. Though eukaryotes produce sphingolipids, this capacity is phylogenetically highly restricted in Bacteria. Intriguingly, bacterial species commonly associated in high abundance with eukaryotic hosts include sphingolipid producers, such as the Bacteroidetes in the mammalian gut. To date, a role for bacterial sphingolipids in immune system maturation has been described, but their fate and impact in host physiology and metabolism remain to be elucidated. The structural conservation of bacterial sphingolipids with those produced by their mammalian hosts offer clues about which aspects of mammalian biology may be modulated by these intriguing lipids.





  • Proximity labeling: spatially resolved proteomic mapping for neurobiology
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Neurobiology, Volume 50

    Author(s): Shuo Han, Jiefu Li, Alice Y Ting

    Understanding signaling pathways in neuroscience requires high-resolution maps of the underlying protein networks. Proximity-dependent biotinylation with engineered enzymes, in combination with mass spectrometry-based quantitative proteomics, has emerged as a powerful method to dissect molecular interactions and the localizations of endogenous proteins. Recent applications to neuroscience have provided insights into the composition of sub-synaptic structures, including the synaptic cleft and inhibitory post-synaptic density. Here we compare the different enzymes and small-molecule probes for proximity labeling in the context of cultured neurons and tissue, review existing studies, and provide technical suggestions for the in vivo application of proximity labeling.





  • Implantable, wireless device platforms for neuroscience research
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Neurobiology, Volume 50

    Author(s): Philipp Gutruf, John A Rogers

    Recently developed classes of ultraminiaturized wireless devices provide powerful capabilities in neuroscience research, as implantable light sources for simulation/inhibition via optogenetics, as integrated microfluidic systems for programmed pharmacological delivery and as multimodal sensors for physiological measurements. These platforms leverage basic advances in biocompatible materials, semiconductor device designs and systems engineering concepts to afford modes of operation that are qualitatively distinct from those of conventional approaches that tether animals to external hardware by means of optical fibers, electrical cables and/or fluidic tubing. Neuroscience studies that exploit the unique features of these technologies enable insights into neural function through targeted stimulation, inhibition and recording, with spatially and genetically precise manipulation of neural circuit activity. Experimental possibilities include studies in naturalistic, three dimensional environments, investigations of pair-wise or group related social interactions and many other scenarios of interest that cannot be addressed using traditional hardware.





  • Recent advances in neural dust: towards a neural interface platform
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Neurobiology, Volume 50

    Author(s): Ryan M Neely, David K Piech, Samantha R Santacruz, Michel M Maharbiz, Jose M Carmena

    The neural dust platform uses ultrasonic power and communication to enable a scalable, wireless, and batteryless system for interfacing with the nervous system. Ultrasound offers several advantages over alternative wireless approaches, including a safe method for powering and communicating with sub mm-sized devices implanted deep in tissue. Early studies demonstrated that neural dust motes could wirelessly transmit high-fidelity electrophysiological data in vivo, and that theoretically, this system could be miniaturized well below the mm-scale. Future developments are focused on further minimization of the platform, better encapsulation methods as a path towards truly chronic neural interfaces, improved delivery mechanisms, stimulation capabilities, and finally refinements to enable deployment of neural dust in the central nervous system.





  • Targeting oxidant-dependent mechanisms for the treatment of respiratory diseases and their comorbidities
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Pharmacology, Volume 40

    Author(s): Neil C Thomson

    Oxidative stress is implicated in the pathogenesis of respiratory diseases, such as COPD and its comorbidities, asthma, idiopathic pulmonary fibrosis and radiation pneumonitis. Antioxidants drugs, such as small molecule thiols, nuclear erythroid-2 related factor 2 activators and catalytic enzyme mimetics have been developed to target oxidant-dependent mechanisms. The therapeutic effects of antioxidants have been generally disappointing. A small number of antioxidants are approved for clinical use, such as the small molecule thiol N-acetyl-l-cysteine for chronic obstructive pulmonary disease, and in the United States, the superoxide dismutase mimetic AEOL 10150 for severe radiation pneumonitis. The future use of antioxidants for the treatment of chronic respiratory diseases may require a precision medicine approach to identify responsive patients.





  • Targeting the renin–angiotensin system as novel therapeutic strategy for pulmonary diseases
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Pharmacology, Volume 40

    Author(s): Wan Shun Daniel Tan, Wupeng Liao, Shuo Zhou, Dan Mei, Wai-Shiu Fred Wong

    The renin–angiotensin system (RAS) plays a major role in regulating electrolyte balance and blood pressure. RAS has also been implicated in the regulation of inflammation, proliferation and fibrosis in pulmonary diseases such as asthma, acute lung injury (ALI), chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF) and pulmonary arterial hypertension (PAH). Current therapeutics suffer from some drawbacks like steroid resistance, limited efficacies and side effects. Novel intervention is definitely needed to offer optimal therapeutic strategy and clinical outcome. This review compiles and analyses recent investigations targeting RAS for the treatment of inflammatory lung diseases. Inhibition of the upstream angiotensin (Ang) I/Ang II/angiotensin receptor type 1 (AT1R) pathway and activation of the downstream angiotensin-converting enzyme 2 (ACE2)/Ang (1–7)/Mas receptor pathway are two feasible strategies demonstrating efficacies in various pulmonary disease models. More recent studies favor the development of targeting the downstream ACE2/Ang (1–7)/Mas receptor pathway, in which diminazene aceturate, an ACE2 activator, GSK2586881, a recombinant ACE2, and AV0991, a Mas receptor agonist, showed much potential for further development. As the pathogenesis of pulmonary diseases is so complex that RAS modulation may be used alone or in combination with existing drugs like corticosteroids, pirfenidone/nintedanib or endothelin receptor antagonists for different pulmonary diseases. Personalized medicine through genetic screening and phenotyping for angiotensinogen or ACE would aid treatment especially for non-responsive patients. This review serves to provide an update on the latest development in the field of RAS targeting for pulmonary diseases, and offer some insights into future direction.





  • The cholinergic anti-inflammatory pathway: an innovative treatment strategy for respiratory diseases and their comorbidities
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Pharmacology, Volume 40

    Author(s): Mitsuhiro Yamada, Masakazu Ichinose

    Over the past few decades, it has been clarified that the nervous system and immune system have overlapping distributions and their interactions are critical in the regulation of immunological and inflammatory responses. The cholinergic anti-inflammatory pathway, including the parasympathetic nerve systems and humoral factors orchestrate the immune responses to protect the body during infection and tissue injury. Recent investigations have attempted to clarify how the parasympathetic nerve systems attenuate the systemic inflammatory responses and identified the α7 nicotinic acetylcholine receptor (α7nAChR) as a crucial target for attenuating the release of inflammatory cytokines from inflammatory cells including macrophages and dendritic cells. This modulatory circuit pathway possibly exists in the lungs and might be involved in regulating inflammation and immunity during infection and other inflammatory lung diseases including asthma and COPD, which means that modulation of the cholinergic anti-inflammatory pathway is a possible therapeutic target for lung diseases.





  • Statins in the treatment of COPD and asthma—where do we stand?
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Pharmacology, Volume 40

    Author(s): Jennifer Y So, Santosh Dhungana, Joanna J Beros, Gerard J Criner

    Asthma and chronic obstructive pulmonary disease (COPD) are the two most prevalent obstructive lung diseases that account for tremendous morbidity and mortality throughout the world. These diseases have strong inflammatory components, with multiple prior studies showing elevated levels of various inflammatory markers and cells in those with COPD and asthma. Therefore, efforts to target inflammation in management of these diseases are of great interest. Statins, which define a class of drugs that are HMG-CoA inhibitors, are used to decrease cholesterol levels and have also been described to have many pleotropic effects that include anti-inflammatory and anti-oxidative properties. These properties have led to multiple studies looking at the potential use of statins in decreasing inflammation in many diseases, including COPD and asthma. This review aims to address the current evidence behind the potential use of statins in the treatment of asthma and COPD.





  • Post-transcriptional regulation of mitochondrial function
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Physiology, Volume 3

    Author(s): Désirée Schatton, Elena I Rugarli

    RNA-binding proteins (RBPs) can control each step of the mRNA life cycle, such as splicing, nuclear export, stability, degradation, localization, and translation efficiency. Thus, RBPs can modulate the final amount of protein level and play an important role in fine-tuning many cellular processes. Surprisingly, the role of specific RBPs to allow the dynamic and coordinated expression of functionally related mitochondrial proteins has begun to emerge only recently. These RBPs define specific post-transcriptional RNA regulons that fine-tune mitochondrial gene expression, thus tailoring the effects of broad transcriptional responses to specific demands or affecting mitochondrial biogenesis independently from de novo transcription. Moreover, a handful of RBPs promote translation of mitochondrial proteins in close proximity to the organelle. Here, we review the molecular components that play a role in these elaborate and flexible mechanisms, and discuss the physiological implications of post-transcriptional regulation for mitochondrial function.





  • Sucrose capped gold nanoparticles as a plasmonic chemical sensor based on non-covalent interactions: Application for selective detection of vitamins B1 and B6 in brown and white rice food samples
    16 janvier 2018
    Publication date: 1 June 2018
    Source:Food Chemistry, Volume 250

    Author(s): Kamlesh Shrivas, Nidhi Nirmalkar, Santosh Singh Thakur, Manas Kanti Deb, Sandip S. Shinde, Ravi Shankar

    We report simple and selective method for detection of vitamins B1 and B6 in brown and white rice samples using localized surface plasmon resonance (LSPR) of sucrose capped gold nanoparticles (AuNPs) as a chemical sensor colorimetrically. Here, detection is based on the color change of AuNPs from pink to blue followed by a red shift of LSPR absorption band in UV–vis region with the addition of vitamins B1 and B6 into the NPs solution. A good linear range was observed in the range of 25–1000 ngmL−1 with detection limit of 8 ngmL−1 for B1 and 50–1000 ngmL−1 with detection limit of 15 ngmL−1 for vitamins B6. The employment of AuNPs for detection of B1 and B6 vitamins in rice food samples showed remarkable abilities in terms of the simplicity, low cost, stability, reproducibility and sensitivity.





  • Sample preparation combined with electroanalysis to improve simultaneous determination of antibiotics in animal derived food samples
    16 janvier 2018
    Publication date: 1 June 2018
    Source:Food Chemistry, Volume 250

    Author(s): Wesley Pereira da Silva, Luiz Henrique de Oliveira, André Luiz dos Santos, Valdir Souza Ferreira, Magno Aparecido Gonçalves Trindade

    A procedure based on liquid–liquid extraction (LLE) and phase separation using magnetically stirred salt-induced high-temperature liquid-liquid extraction (PS-MSSI-HT-LLE) was developed to extract and pre-concentrate ciprofloxacin (CIPRO) and enrofloxacin (ENRO) from animal food samples before electroanalysis. Firstly, simple LLE was used to extract the fluoroquinolones (FQs) from animal food samples, in which dilution was performed to reduce interference effects to below a tolerable threshold. Then, adapted PS-MSSI-HT-LLE protocols allowed re-extraction and further pre-concentration of target analytes in the diluted acid samples for simultaneous electrochemical quantification at low concentration levels. To improve the peak separation, in simultaneous detection, a baseline-corrected second-order derivative approach was processed. These approaches allowed quantification of target FQs from animal food samples spiked at levels of 0.80 to 2.00 µmol L−1 in chicken meat, with recovery values always higher than 80.5%, as well as in milk samples spiked at 4.00 µmol L−1, with recovery values close to 70.0%.





  • Dissociation mechanisms-based UHPLC Q-Orbitrap strategy for screening of cephalosporins and metabolites in shrimp
    16 janvier 2018
    Publication date: 1 June 2018
    Source:Food Chemistry, Volume 250

    Author(s): Wei Jia, Lin Shi, Xiaogang Chu

    A screening method was explored for simultaneous analysis of 43 cephalosporins residues and their metabolites from four generations in shrimp utilizing a novel fully untargeted data acquisition method. Four generations of cephalosporins residues and their metabolites are extracted with online extraction simultaneously. Ultrahigh-performance liquid chromatography coupled to quadrupole-orbitrap high resolution mass spectrometry was used for to determine cephalosporins and their metabolites in ten shrimp species. Precision in terms of relative standard deviation (RSD) was under 6.3% for all compounds, and the extraction recoveries ranged from 85% to 108%. The detection capabilities ranged from 0.011 to 0.223 mg kg−1. The fully untargeted vDIA acquisition way improves both selectivity and sensitivity for the compounds at trace levels, which is beneficial for screening performance.





  • Determination of virginiamycin M1 residue in tissues of swine and chicken by ultra-performance liquid chromatography tandem mass spectrometry
    16 janvier 2018
    Publication date: 1 June 2018
    Source:Food Chemistry, Volume 250

    Author(s): Xiaoyang Wang, Mi Wang, Keyu Zhang, Ting Hou, Lifang Zhang, Chenzong Fei, Feiqun Xue, Taijun Hang

    A reliable UPLC–MS/MS method with high sensitivity was developed and validated for the determination of virginiamycin M1 in muscle, fat, liver, and kidney samples of chicken and swine. Analytes were extracted using acetonitrile and extracts were defatted by N-hexane. Chromatographic separation was performed on a BEH C18 liquid chromatography column. The analytes were then detected using triplequadrupole mass spectrometry in positive electrospray ionization and multiple reaction monitoring mode. Calibration plots were constructed using standard working solutions and showed good linearity. Limits of quantification ranged from 2 to 60 ng mL−1.





  • Peptidomic analysis of antioxidant and ACE-inhibitory peptides obtained from tomato waste proteins fermented using Bacillus subtilis
    16 janvier 2018
    Publication date: 1 June 2018
    Source:Food Chemistry, Volume 250

    Author(s): Ali Moayedi, Leticia Mora, Maria Concepción Aristoy, Mohammad Safari, Maryam Hashemi, Fidel Toldrá

    In this study, tomato seeds were obtained as by-products and submitted to fermentation with the proteolytic strain Bacillus subtilis A14h. The resulting peptide mixture was fractionated and purified through different chromatographic steps. Fractions were assayed for antioxidant and angiotensin converting enzyme (ACE)-inhibitory activities and peptides were identified by using nano-liquid chromatography coupled to mass spectrometry in tandem (nLC-MS/MS). Most of the identified peptides were smaller than 1000 Da and had different aromatic and hydrophobic amino acid residues. Their sequences were novel but some of them showed active domains previously reported in other bioactive peptides. The hexapeptide DGVVYY showed an IC50 value of 2 µM in angiotensin-I converting enzyme (ACE-I) inhibitory activity, whereas the pentapeptide GQVPP displayed a 97% of DPPH activity at 0.4 mM. The results revealed that B. subtilis fermentation of tomato by-products could be a good strategy for obtaining added-value peptides that might be used as an ingredient in functional foods and nutraceuticals.





  • Mimicking new receptors based on molecular imprinting and their application to potentiometric assessment of 2,4-dichlorophenol as a food taint
    16 janvier 2018
    Publication date: 1 June 2018
    Source:Food Chemistry, Volume 250

    Author(s): A.M. El-Kosasy, Ayman H. Kamel, L.A. Hussin, Miriam F. Ayad, N.V. Fares

    Innovative host-tailored polymers were prepared, characterized and used as recognition elements in potentiometric transducers for the selective quantification of 2,4-dichlorophenol (DCP).The polymer beads were synthesized using DCP as a template molecule, acrylamide (AM),methacrylic acid (MAA) and ethyl methacrylate (EMA) as functional monomers and divinylbenzene (DVB) and ethylene glycol dimethacrylate (EGDMA) as cross-linkers. The sensors were fabricated by the inclusion of MIPs in plasticized polyvinyl chloride (PVC) matrix. Response characteristics of the proposed sensors revealed anionic slopes of −59.2, −49.7 and −80.6 mV/decade with detection limits of 5.6 × 10−5,5.9 × 10−5 and 13.2 × 10−5 mol/L for MIP/AM/DVB, MIP/MAA/DVB and MIP/EMA/EGDMA membrane based sensors, respectively. Good selectivity was observed over common inorganic/organic anions. Validation of the assay method according to IUPAC recommendations was justified ensuring the synthesis of good reliable novel sensors for DCP determination. The method was successfully applied for routine analysis of food taint in fish and fish farms water samples.





  • Monoclonal antibody-based ELISA for the quantification of porcine hemoglobin in meat products
    16 janvier 2018
    Publication date: 1 June 2018
    Source:Food Chemistry, Volume 250

    Author(s): Xingyi Jiang, Danielle Fuller, Yun-Hwa Peggy Hsieh, Qinchun Rao

    Misusage of porcine blood proteins, such as misbranding and substitution, can cause religious objections, law violation, and food quality concerns. These issues highlight the need for detecting unlabeled or overuse of porcine blood in foods. Compared with acidic and neutral pHs, porcine hemoglobin (PHb) at alkaline pH retained the best solubility, molecular integrity, and immunoreactivity after heat treatment. PHb at acidic and alkaline pHs remained stable during storage at 4 °C for 29 days. A monoclonal antibody (mAb) specific to mammalian hemoglobin, 13F7, was developed. A mAb13F7-based indirect competitive ELISA (icELISA) was optimized for the quantification of PHb in meat products. This assay had a wide working range from 0.5 ppm to 1000 ppm. It was sensitive (limit of detection: 0.5 ppm), precise and reproducible with low inter- and intra-coefficient of variances (<20%). This assay is suitable for government, food industry, and third-party authority to surveillance food quality.





  • Sensory characteristics of liquids thickened with commercial thickeners to levels specified in the International Dysphagia Diet Standardization Initiative (IDDSI) framework
    16 janvier 2018
    Publication date: June 2018
    Source:Food Hydrocolloids, Volume 79

    Author(s): Jane Jun-Xin Ong, Catriona M. Steele, Lisa M. Duizer

    Sensory characteristics are important for the acceptance of thickened liquids, but those of liquids thickened to the new standards put forth by the International Dysphagia Diet Standardization Initiative (IDDSI) are unknown. This research sought to identify and rate the perception of important sensory properties of liquids thickened to levels specified in the IDDSI framework. Samples were made with water, with and without added barium sulfate, and were thickened with a cornstarch or xanthan gum based thickener. Samples were characterized using projective mapping/ultra-flash profiling to identify important sample attributes, and then with trained descriptive analysis panels to characterize those attributes in non-barium and barium thickened liquids. Three main groups of attributes were observed. Taste and flavor attributes decreased in intensity with increasing thickener. Thickener specific attributes included graininess and chalkiness for the cornstarch thickened samples, and slipperiness for the xanthan gum samples. Within the same type of thickener, ratings of thickness-related attributes (perceived viscosity, adhesiveness, manipulation, and swallowing) at different IDDSI levels were significantly different from each other. However, in non-barium samples, cornstarch samples were perceived as thicker than xanthan gum samples even though they had similar apparent viscosities at 50 s−1. On the other hand, the two thickeners had similar perceived thickness in the barium samples even though the apparent viscosities of cornstarch samples were higher than those of the xanthan gum samples. In conclusion, IDDSI levels can be distinguished based on sensory properties, but these properties may be affected by the type of thickener and medium being thickened.

    Graphical abstract

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  • Polysaccharide food matrices for controlling the release, retention and perception of flavours
    16 janvier 2018
    Publication date: June 2018
    Source:Food Hydrocolloids, Volume 79

    Author(s): Sarah L. Cook, Lisa Methven, Jane K. Parker, Vitaliy V. Khutoryanskiy

    Polysaccharides have many roles across both the food and pharmaceutics industries. They are commonly used to enhance viscosity, stabilise emulsions and to add bulk to food products. In the pharmaceutics industry, they are also utilised for their mucoadhesive nature. Mucoadhesive polysaccharides can facilitate retention of active ingredients at mucosal sites for a prolonged time and formulations can be designed to control their release and bioavailability. This study investigates how polysaccharides, with differing physicochemical properties (e.g. functional groups and molecular weight), affect the release and perception of flavour compounds from films. Polysaccharide films were prepared using either high or low viscosity carboxymethyl cellulose, pullulan or hydroxypropyl methylcellulose. Glucose, vanillin or a combination of both was also added to the films to assess the effect of flavour release and perception over time. The films were assessed for glucose release in vitro, swelling and disintegration times, and mucoadhesive ability. Results show that flavour release and perception depend on the polysaccharide matrix properties; this includes how quickly the films dissolve, the rate of release of tastant compounds, and the mucoadhesive strength of the polysaccharide. A higher viscosity and slower disintegration time resulted in slower release of glucose in vitro and flavour perception in vivo.

    Graphical abstract

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  • Expanding horizons of active packaging: Design of consumer-controlled release systems helps risk management of susceptible individuals
    16 janvier 2018
    Publication date: June 2018
    Source:Food Hydrocolloids, Volume 79

    Author(s): Derya Boyacı, Ahmet Yemenicioğlu

    The objective of this study was the development of zein based antilisterial films that contain a consumer-controlled and pH-triggered release mechanism for lysozyme (LYS). For this purpose, composite films were formed by mixing hydrophobic zein with hydrophilic soy protein isolate (SPI) or lentil protein isolate (LPI). Active property of films was formed by maintaining 30 to 50% of total LYS in free form (LYSfree). On the other hand, the pH-triggered release mechanism was formed by exploiting attractive charge-charge interactions between LYS (pI: 11.4) and SPI or LPI (pI values ≈ 4.5), and binding remaining LYS (LYSbound) in film matrix. The pH-triggered release mechanism of composite films worked in buffers that had pHs varying between 4.3 and 7.3. The composite films bound majority of LYS between pH 5.3 and 7.3, but they released LYS at pH ≤ 4.5. The pH-triggered release of LYS was achieved with zein-LPI films activated by acidification in packed cold-stored beef, lamb and smoked salmon. The zein-SPI films performed pH-triggered LYS release in packed food with the exception of packed smoked salmon. The LYSfree and LYSbound released from pH-triggered films showed antimicrobial activity on Listeria innocua. Consumer-controlled release mechanisms enable increasing antimicrobial stress over pathogens during transfer from market to home and cold storage at home. Thus, such films could initiate personalized packaged food to help risk management of susceptible individuals.

    Graphical abstract

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  • Influence of heat processing on the volatile organic compounds and microbial diversity of salted and vacuum-packaged silver carp (Hypophthalmichthys molitrix) fillets during storage
    16 janvier 2018
    Publication date: June 2018
    Source:Food Microbiology, Volume 72

    Author(s): Dongping Li, Jingbin Zhang, Sijia Song, Ligeng Feng, Yongkang Luo

    Ready-to-eat products have become popular with most of the busy people in modern cities. Heat processing combined with vacuum-packaging is one of the most common methods to make ready-to-eat products with an extended shelf-life. In this study, the influence of heat processing [80 °C (LT) and 98 °C (HT) in water bath] on the quality of salted and vacuum-packaged silver carp (Hypophthalmichthys molitrix) fillets, stored at 20 ± 1 °C, was investigated by sensory analysis, biochemical analysis, and microbial diversity. SPME-GC/MS indicated the presence of 27 volatile organic compounds (VOCs) in fillets, and major VOCs were aldehydes and alcohols. Acids tended to increase during storage and caused a fetid odor at the end of storage. Culture-dependent method indicated that Bacillus dominated the spoiled LT and HT samples. In addition, Bacillus was identified as the main spoiler of deteriorated heated fillets by high-throughput sequencing. Sphingomonas and Brevibacillus dominated the indigenous bacteria of fresh raw fillets. After heat processing, LT samples exhibited higher organoleptic quality than HT samples on day 0. HT samples showed extended shelf-life at 20 °C storage compared to LT samples.





  • Effect of several packaging conditions on the microbiological, physicochemical and sensory properties of ostrich steaks during refrigerated storage
    16 janvier 2018
    Publication date: June 2018
    Source:Food Microbiology, Volume 72

    Author(s): Rosa Capita, Tania Álvarez-González, Carlos Alonso-Calleja

    A total of 365 ostrich steaks were packaged in air (AIR), vacuum (VAC), MAP1 (70% O2 + 30% CO2), MAP2 (30% O2 + 30% N2 + 40% CO2), MAP3 (20% O2 + 30% N2 + 50% CO2), MAP4 (50% N2 + 50% CO2), MAP5 (20% N2 + 80% CO2) or MAP6 (100% CO2). Microbial counts (10 groups), pH, Aw and sensory properties (nine-point hedonic scale) were determined on days 0, 1, 3, 7 and 15 of storage (4 °C). On day 0, microbial counts (log10 cfu/g) ranged from undetectable levels (Brochothrix thermosphacta, enterococci) to 3.21 ± 0.63 (total aerobic counts -TAC-). The highest and the lowest microbial loads throughout storage were observed in AIR and MAP6, respectively. On day 15 TAC as high as 9.96 ± 0.20 log10 cfu/g were found in AIR. The shelf-life (time until overall acceptability score fell below 5) was 3 days (MAP1, MAP2), 7 days (MAP3, AIR) or 15 days (MAP4, MAP5, MAP6). Only for VAC the shelf-life limit extended beyond 15 days.





  • Effects of microbial diversity on nitrite concentration in pao cai, a naturally fermented cabbage product from China
    16 janvier 2018
    Publication date: June 2018
    Source:Food Microbiology, Volume 72

    Author(s): Zhaoxia Wang, Yuyu Shao

    Pao cai is a spontaneously fermented cabbage where native bacteria may have an important influence on nitrite content during fermentation. In this research, we used metagenomic-based 16S rRNA gene amplicon sequencing to analyze differences in bacterial composition of pao cai from Hohhot City (northern China) and Guiyang City (southern China). Alongside this, metagenome functional features from the 16S rRNA genes of the microbiome were predicted and correlated with the nitrite content of pao cai. Nitrite-reducing bacterial genera were identified including Lactobacillus (73.37%), Pediococcus (0.93%), Acinetobacter (0.74%), Leuconostoc (0.31%), Weissella (0.14%), Streptococcus (0.09%), Megamonas (0.08%), Enterococcus (0.07%), and Alistipes (0.06%). Lactobacillus was the predominant genus in both the northern and the southern pao cai samples and was significantly negatively correlated with nitrite content; it was more abundant in southern samples than northern samples. Based on determination of alpha and beta diversities of the microbiome in samples, differences in the microbiome of northern and southern pao cai were demonstrated that may influence nitrogen metabolism. This research suggests that 16S rRNA gene amplicon sequencing is an effective way to comprehensively study the microbes with potential nitrite formation or decomposition ability instead of investigating the individual bacterial genera.





  • Superficial acral fibromyxoma: A rare and distinct clinicopathological entity: A case report and review of literature
    16 janvier 2018
    Publication date: June 2018
    Source:Human Pathology: Case Reports, Volume 12

    Author(s): Ravi Gupta, Anubhav Malhotra, Sonam Arora, Vinisha Bansal

    Superficial acral fibromyxoma (SAF) is a rare, slow growing soft tissue tumor which was first described as a separate entity in 2001 by Fetsch et al. The tumor involves periungual and subungual regions of fingers and toes in middle aged adults with slight male predominance. Not many cases have been reported worldwide. To the best of our knowledge, only a couple of such cases have been reported earlier in Indian population. Superficial acral fibromyxoma has a recurrence rate of 25%. Local recurrence is almost always associated with positive margins. Malignant or metastatic behaviour has not been reported as yet. Since the tumor has a tendency to recur, it is beneficial to make a pre-operative provisional diagnosis and do wide surgical excision with tumor free margins and keep the patient on regular follow up.





  • Jejunal lymphangioma and recurrent intussusception in an adult patient; a case report and review of literature
    16 janvier 2018
    Publication date: June 2018
    Source:Human Pathology: Case Reports, Volume 12

    Author(s): Suzanne Iwaz, Nathan Aardsma, Rajyasree Emmadi







  • Neonatal spinal injury induces de novo projections of primary afferents to the lumbosacral intermediolateral nucleus in rats
    16 janvier 2018
    Publication date: June 2018
    Source:IBRO Reports, Volume 4

    Author(s): Masahito Takiguchi, Mai Fujioka, Kengo Funakoshi

    Complete spinal transection in adult rats results in poor recovery of hind limb function and severe urinary bladder dysfunction. Neonatal rats with spinal cord transection, however, exhibit spontaneous and significant recovery of micturition control. A previous study in which biotinylated-dextran amine (BDA) was used as an anterograde tracer demonstrated that primary afferent fibers from the fifth lumbar dorsal root ganglion (DRG) project more strongly and make more terminals in the ventral horn after neonatal spinal cord transection at the mid-thoracic level. In the present study, we injected BDA into the sixth lumbar (L6) DRG of neonatally spinalized rats to label primary afferent fibers that include visceral afferents. The labeled fibers projected to the intermediolateral nucleus (IML) in the intermediate zone on ipsilateral side of the L6 spinal segment, whereas no projections to the IML were observed in sham-operated or intact rats. The BDA-labeled fibers of neonatally spinalized rats formed varicose terminals on parasympathetic preganglionic neurons in the IML. These findings suggest that some primary afferent projections from the L6 DRG to the IML appear after neonatal spinal cord transection, and these de novo projections might contribute to the recovery of autonomic function such as micturition following spinal cord injury in the neonatal stage.





  • Acute epidural hematoma due to spinal venous angioma: A case report
    16 janvier 2018
    Publication date: June 2018
    Source:Interdisciplinary Neurosurgery, Volume 12

    Author(s): Shiro Chitoku, Iwao Nishiura, Miyuki Fukuda, Shigeru Amano

    Background Spinal epidural cavernous angioma was reported about 4% of all spinal epidural tumors, mostly generating as a primary lesion in the vertebral bone. Spinal epidural hematoma (SEDH) due to angioma without primary origin was very rare, which reported in the English literatures was only 10 cases including our case. The main symptoms were numbness and pains and motor weakness owing to the acute compression signs of cord and roots. Emergency surgical treatment was required for the good surgical results. We present a rare case of cervical acute epidural hematoma due to ruptured venous angioma. Case presentation A 78-year-old man, who suffered from sudden severe right suboccipitalgia., and sent to our hospital. He also noticed progressive numbness and motor weakness over his bilateral upper and lower extremities after the onset. Cervical CT and MRI showed acute intracanal hematoma over the right side of the cervical spine at C2 to C6. Emergency operation was performed 13h after the onset. His sensory and motor symptoms were disappeared quickly after the operation. Pathological examination revealed spinal epidural hematoma due to venous angioma. Conclusion This case presented with acute progressive deterioration of paresis and sensory disturbance, and required emergency operation. Early diagnosis and emergency surgical treatment are essential for the therapy of acute spinal epidural hematoma due to venous angioma.





  • Self-thrombosing anterior cerebral artery aneurysm leading to a caudate infarct
    16 janvier 2018
    Publication date: June 2018
    Source:Interdisciplinary Neurosurgery, Volume 12

    Author(s): Peter N. Hadar, John Burke, Jared Pisapia, Aaron Bress, Bryan Pukenas, David Kung

    Self-thrombosing intracranial aneurysms are relatively uncommon and the conditions that lead to their formation are unknown, although they can be seen following subarachnoid hemorrhage and in autopsy specimens. We seek to raise awareness of the unintended iatrogenic thrombosis of intracranial aneurysms, its ischemic consequences, and the use of mechanical thrombectomy in its treatment. A 50-year-old hypertensive woman presented with a sudden onset of severe headache concerning for a ruptured cerebral aneurysm (Hunt-Hess 2). HCT showed diffuse subarachnoid hemorrhage (modified Fisher grade 3), and CTA showed two aneurysms arising from an anterior communicating (ACOM) complex fenestration and one aneurysm arising from the proximal left anterior cerebral artery (ACA) A1 segment. Successful coil embolization of the distal ACOM aneurysm was followed by an attempted balloon-assisted coil embolization of a left ACA A1 aneurysm that led to self-thrombosis and partial occlusion of the A1 segment. After mechanical thrombectomy, there was significant reduction in left A1 thrombus burden. The patient developed an asymptomatic small infarct of the left caudate, likely by occlusion of an anatomic variant of the recurrent artery of Heubner arising from the A1 segment. To our knowledge, this is the first reported case of a self-thrombosing aneurysm during attempted balloon-assisted embolization. Propagation of the thrombus can lead to parent vessel occlusion and ischemia, and, in this case, an anatomic variant of the recurrent artery of Heubner from A1 made this more likely. Intra-arterial mechanical thrombectomy may be used in the treatment of an iatrogenic vessel thrombosis.





  • Spinal kirschner wire migration after surgical treatment of clavicular fracture or acromioclavicular joint dislocation: Report of a case and meta-analysis
    16 janvier 2018
    Publication date: June 2018
    Source:Interdisciplinary Neurosurgery, Volume 12

    Author(s): Hermann Adonis N'da, Kporou Landry Drogba, Landry Meleine Konan, Aderehime Haidara, Guy Varlet

    Kirschner wire is the most used device for clavicular and acromioclavicular joint dislocation fixation. Although wire migrations have been extensively reported, spinal migrations remain rare. Moreover, the mechanism of migration is still elusive. The aim of the present paper is to describe a single case of cervical spine migration of a K-wire followed by meta-analysis. Twelve cases of spinal K-wire have been reported in the last 20years, with less than 2 cases per year. Clavicular fixation was the main initial procedure with 66.67% of cases. The average time between surgery and migration was 25.5months. C7-T1 and T2-T3 were the prominent level of migration with each 33.33% of cases, where the migration was transversal in 72.73% of cases. The neural foramen was the most penetrating site of the K-wire in the spine (75% of cases). In all cases the wire was removed via direct access surgery by gentle pulling out along its axis under view control. The greater range of motion in the shoulder seems to be the main mechanism of all kinds of migrations.





  • Long-term clinical outcomes following surgical management of cervical spine fractures in elderly patients
    16 janvier 2018
    Publication date: June 2018
    Source:Interdisciplinary Neurosurgery, Volume 12

    Author(s): James Zhou, Nitin Agarwal, Gurpreet S. Gandhoke, Mike T. Koltz, Adam S. Kanter, David O. Okonkwo, D. Kojo Hamilton

    Background To date, no studies have compared the outcomes of surgical management of cervical fractures in patients<75 to those of patients75. Given the possibility of increased frailty in “older” elderly patients, it is important to consider how the outcomes of surgery compare in these two patient groups. Objective In this study, we aim to determine if the outcomes of surgical management of cervical fractures differ when comparing patients<75 to patients75. Methods A retrospective review was conducted of a prospectively maintained database of 107 elderly patients who experienced cervical spine trauma between 2007 and 2014. Chi-square analysis and Fisher exact tests were performed to compare two groups on a number clinical outcome measures. Results There are no statistically significant differences when patients<75 with patients75 on a number of clinical outcome measures. Selected outcomes include length of stay, likelihood of death during admission, likelihood of death following discharge, likelihood of developing mental status decline following discharge, post-operative neurologic improvements, and long-term functional status. Conclusions Patients75 have statistically similar outcomes following surgical management of cervical spine fractures when compared to patients<75. This may be due to ongoing improvements in both surgical and medical methodologies in spine trauma care. These results indicate that surgical management of cervical fractures in elderly patients is beneficial without regard to age, and should not be withheld for fear of poor outcomes in “older” elderly patients.






 

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  • Reverse-engineering organogenesis through feedback loops between model systems
    16 janvier 2018
    Publication date: August 2018
    Source:Current Opinion in Biotechnology, Volume 52

    Author(s): Cody Narciso, Jeremiah Zartman

    Biological complexity and ethical limitations necessitate models of human development. Traditionally, genetic model systems have provided inexpensive routes to define mechanisms governing organ development. Recent progress has led to 3D human organoid models of development and disease. However, robust methods to control the size and morphology of organoids for high throughput studies need to be developed. Additionally, insights from multiple developmental contexts are required to reveal conserved genes and processes regulating organ growth and development. Positive feedback between quantitative studies using mammalian organoids and insect micro-organs enable identification of underlying principles for organ size and shape control. Advances in the field of multicellular systems engineering are enabling unprecedented high-content studies in developmental biology and disease modeling. These will lead to fundamental advances in regenerative medicine and tissue-engineered soft robotics.





  • Damage characterization of aluminum 2024 thin sheet for different stress triaxialities
    16 janvier 2018
    Publication date: July 2018
    Source:Archives of Civil and Mechanical Engineering, Volume 18, Issue 3

    Author(s): G.H. Majzoobi, M. Kashfi, N. Bonora, G. Iannitti, A. Ruggiero, E. Khademi

    Due to its attractive mechanical properties, aluminum 2024 is widely used in aircraft manufacturing industries, especially as fiber metal laminates, such as GLARE. In the present work, a series of experiments for different stress triaxialities are used to study the ductile damage of Al 2024 considering continuum damage mechanics (CDM). Stress triaxiality is produced using notched specimens. The main objective of the present study is to predict the local equivalent plastic strain to fracture and introducing a relation which describes the effect of stress triaxiality factor (TF) on it in the medium range of stress triaxiality. Hence, a nonlinear damage model is utilized for Al 2024 and its parameters are determined by an experimental/numerical/optimization procedure using tensile test on plain specimens. The experiments showed that for large notch specimens (Al-NL) and medium notch samples (Al-NM) fracture started from the center of the notch root of the specimens, whereas for small notched specimens (Al-NS) the failure initiated from the notch root surface. Finite element simulations are performed using the presented nonlinear damage model and are compared with the experimental data. Results show that the proposed damage model can predict the damage evolution for different stress triaxialities.





  • Numerical modelling of innovative DST steel joint under cyclic loading
    16 janvier 2018
    Publication date: July 2018
    Source:Archives of Civil and Mechanical Engineering, Volume 18, Issue 3

    Author(s): Angela Lemos, Luis Simões da Silva, Massimo Latour, Gianvittorio Rizzano

    This paper addresses the numerical simulation of an innovative double split Tee beam-to-column joint fitted with a dissipative friction damper, recently proposed at the University of Salerno. The innovative connection prevents damage to all other structural components with the exception of one component of the connection that is specially designed to dissipate the input energy of a seismic hazard by means of the slippage of a friction material. The main topics herein presented are the development of a strategy for the numerical modelling of complex friction problems and a detailed numerical model of the overall beam-to-column joint equipped with the friction device. The joint is subjected to both monotonic and cyclic loading conditions. The numerical modelling was developed using the Finite Elements Method (FEM) with Abaqus Software. Sliding force–displacement curves are obtained for two damper materials and an estimation of their wearing is presented. To evaluate the accuracy of the numerical model, moment–rotation curves of the joint are compared with the experimental curves. The FE results show good correlations and confirm the potential interest of this novel joint typology to achieve easily replaceable details in case of a seismic event.





  • On spectral representation method and Karhunen–Loève expansion in modelling construction material properties
    16 janvier 2018
    Publication date: July 2018
    Source:Archives of Civil and Mechanical Engineering, Volume 18, Issue 3

    Author(s): Elton J. Chen, Lieyun Ding, Yong Liu, Xianfeng Ma, Miroslaw J. Skibniewski

    Randomness in construction material properties (e.g. Young's modulus) can be simulated by stationary random processes or random fields. To check the stationarity of commonly used techniques, three random process generation methods were considered: X n (t), Y n (t), and Z n (t). Methods X n (t) and Y n (t) are based on a truncation of the spectral representation method with the first n terms. X n (t) has random amplitudes while Y n (t) has random harmonics phases. Method Z n (t) is based on the Karhunen–Loève expansion with the first n terms as well. The effects of the truncation technique on the mean-square error, covariance function, and scale of fluctuation were examined in this study; these three methods were shown to have biased estimations of variance with finite n. Modified forms for those methods were proposed to ensure the truncated processes were still zero-mean, unit-variance, and had a controllable scale of fluctuation; in particular, the modified form of Karhunen–Loève expansion was shown to be stationary in variance. As a result, the modified forms for those three methods are advantageous in simulating statistically homogenous material properties. The effectiveness of the modified forms was demonstrated by a numerical example.





  • Failure characteristics of jointed rock-like material containing multi-joints under a compressive-shear test: Experimental and numerical analyses
    16 janvier 2018
    Publication date: July 2018
    Source:Archives of Civil and Mechanical Engineering, Volume 18, Issue 3

    Author(s): R.H. Cao, P. Cao, H. Lin, G.W. Ma, C.Y. Zhang, C. Jiang

    Extensive efforts have been made to gain a better understanding of the failure behaviour of rocks and rock-like materials, but crack propagation and failure processes under compressive-shear loading have not yet been comprehensively investigated. To address this area of research, the peak shear strengths (τ) and failure processes of specimens with multiple joints are studied by lab testing and particle flow code (PFC2D). Four types of failure modes are observed: (a) shear failure through a plane (Mode-I), (b) intact shear failure (Mode-II), (c) oblique shear crack connection failure (Mode-III), and (d) stepped path failure (Mode-IV). The failure mode gradually transformed to Mode-III as α (joint inclination angle) increases from 0° to 90° in the specimens. In addition, with increasing joint distance (d) in the specimens, the failure mode changes to Mode-II. As the non-overlapping length between joints (c) in the specimens increases, the failure mode changes to Mode-IV. The joint geometry has a major influence on the shear strength of the jointed specimens. The peak shear strength of specimens with different joint inclination angles is obtained when α =45°. Additionally, the peak shear strength increases as the joint distance (d) and non-overlapping length (c) increase.





  • Machining parameter optimization for EDM machining of Mg–RE–Zn–Zr alloy using multi-objective Passing Vehicle Search algorithm
    16 janvier 2018
    Publication date: July 2018
    Source:Archives of Civil and Mechanical Engineering, Volume 18, Issue 3

    Author(s): Sohil Parsana, Nishil Radadia, Mohak Sheth, Nisarg Sheth, Vimal Savsani, N. Eswara Prasad, T. Ramprabhu

    Mg alloys are known for their specific strength, stiffness, damping capacity, EMI shielding. Particularly, Rare earths added Mg alloys find applications in the gear box casing, transmission housing, engine mount, ribs, frames, instrument panels due to their improved corrosion resistance, pressure tightness, specific strength and creep strength. Reemergence of Mg alloys in the aircraft structural applications demands for advanced machining processes such as EDM to fabricate complex geometry parts. In this study, parametric multi-objective optimization of EDM on Mg–RE–Zn–Zr alloy is carried out using the novel meta-heuristic algorithm – Passing Vehicle Search (PVS). The input parameters considered are pulse-on (T on ), pulse-off (T off ) and peak current (A). Response surface method (RSM) is implemented through the Box–Behnken design to formulate a mathematical model for Material Removal Rate (MRR), Tool Wear Rate (TWR) and Roundness of holes. The accuracy of theoretical model has been established using the confirmation runs. Using the weighted sum method, the multi-objective PVS calculated optimal solutions for different weights to generate 2-D and surface pareto fronts. These pareto fronts were evaluated for performance determination of PVS using novel and established metrics such as spacing, spreading, hypervolume and pure diversity. The values of performance metrics indicate acceptable nature of the graphs and such analysis would facilitate better comparisons of solutions to select algorithms for optimization. Finally, decision making is illustrated with the help of level diagrams to draw up practical inferences for designing production plans and providing the best choice of machining parameters according to their preferences.





  • A new Hysteretic Nonlinear Energy Sink (HNES)
    16 janvier 2018
    Publication date: July 2018
    Source:Communications in Nonlinear Science and Numerical Simulation, Volume 60

    Author(s): George C. Tsiatas, Aristotelis E. Charalampakis

    The behavior of a new Hysteretic Nonlinear Energy Sink (HNES) coupled to a linear primary oscillator is investigated in shock mitigation. Apart from a small mass and a nonlinear elastic spring of the Duffing oscillator, the HNES is also comprised of a purely hysteretic and a linear elastic spring of potentially negative stiffness, connected in parallel. The Bouc-Wen model is used to describe the force produced by both the purely hysteretic and linear elastic springs. Coupling the primary oscillator with the HNES, three nonlinear equations of motion are derived in terms of the two displacements and the dimensionless hysteretic variable, which are integrated numerically using the analog equation method. The performance of the HNES is examined by quantifying the percentage of the initially induced energy in the primary system that is passively transferred and dissipated by the HNES. Remarkable results are achieved for a wide range of initial input energies. The great performance of the HNES is mostly evidenced when the linear spring stiffness takes on negative values.





  • Static and dynamic wetting of soft substrates
    16 janvier 2018
    Publication date: July 2018
    Source:Current Opinion in Colloid & Interface Science, Volume 36

    Author(s): Longquan Chen, Elmar Bonaccurso, Tatiana Gambaryan-Roisman, Victor Starov, Nektaria Koursari, Yapu Zhao

    A survey of recent literature on wetting phenomena reveals that there is a fast-growing interest in wetting of soft or deformable substrates, due to its potential applications in many industrial, technical and biological processes. Unlike rigid substrates, a droplet deposited on a soft substrate deforms the substrate via a combination of the normal component of surface tension and the Laplace pressure, i.e. by capillary force and the action of disjoining pressure. In turn, the capillary and disjoining pressure-induced substrate deformation affects the wetting phenomena on the substrate. In this review, we summarize recent achievements on static and dynamic wetting of soft substrates and provide an outlook to future progress. In static wetting, theoretical, numerical and experimental investigations of capillary and disjoining pressure-induced substrate deformation are introduced, and corresponding effects on contact angle and contact angle hysteresis are discussed. In dynamic wetting, the influence of substrate stiffness on spontaneous wetting, droplet impact dynamics, and other types of forced wetting and dewetting is considered. Finally, other interesting capillarity-controlled phenomena occurring on soft and soft-like substrates are briefly introduced.

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  • Two‐dimensional boron as an impressive lithium‐sulphur battery cathode material
    16 janvier 2018
    Publication date: July 2018
    Source:Energy Storage Materials, Volume 13

    Author(s): Sean Grixti, Sankha Mukherjee, Chandra Veer Singh

    β12-borophene is a recently fabricated two-dimensional (2D) allotrope of boron that has many unique electrical, mechanical and chemical properties that make it an excellent candidate as a cathode material in lithium sulphur (Li-S) batteries. Ab initio calculations were performed to determine β12-borophene's applicability as a Li-S battery cathode material. Binding energies of sulphur (S8) and various lithium polysulphides (Li2Sx, x=2,3,4,6,8) on the β12-borophene surface were calculated, along with the diffusion barriers for Li2S6 and Li2S4. Our calculations suggest a moderate adsorption of sulphur and a strong adsorption of all lithium polysulphides, implying β12-borophene would sufficiently inhibit the dissolution of lithium polysulphides into the electrolyte, preventing the “shuttle effect”. Through an exhaustive adsorption site sampling the binding energies were determined to be −1.19eV for S8, −2.98eV for Li2S8, −2.77eV for Li2S6, −3.08eV for Li2S4, −3.48eV for Li2S3, −3.79eV for Li2S2, and −4.57eV for Li2S. The diffusion barriers for Li2S6 and Li2S4 were determined to be moderate, ensuring efficient diffusion, with the lowest diffusion energy barriers being 0.61eV and 0.99eV for Li2S6 and Li2S4, respectively. The strong binding energies and moderate diffusion barriers suggest β12-borophene would be an excellent lithium polysulphide immobilizer in Li-S cathodes.

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  • Highly sensitive force sensor based on balloon-like interferometer
    16 janvier 2018
    Publication date: July 2018
    Source:Optics & Laser Technology, Volume 103

    Author(s): Yue Wu, Shiying Xiao, Yao Xu, Ya Shen, Youchao Jiang, Wenxing Jin, Yuguang Yang, Shuisheng Jian

    An all-fiber highly sensitive force sensor based on modal interferometer has been presented and demonstrated. The single-mode fiber (SMF) with coating stripped is designed into a balloon-like shape to form a modal interferometer. Due to the bent SMF, the interference occurs between the core mode and cladding modes. With variation of the force applied to the balloon-like interferometer, the bending diameter changes, which caused the wavelength shift of the modal interference. Thus the measurement of the force variation can be achieved by monitoring the wavelength shift. The performances of the interferometer with different bending diameter are experimentally investigated, and the maximum force sensitivity of 24.9 pm/ μ N can be achieved with the bending diameter 14 mm ranging from 0  μ N to 1464.12  μ N. Furthermore, the proposed fiber sensor exhibits the advantages of easy fabrication and low cost, making it a suitable candidate in the optical fiber sensing field.





  • Experimental behavior of full-scale exterior beam-column space joints retrofitted by ferrocement layers under cyclic loading
    16 janvier 2018
    Publication date: June 2018
    Source:Case Studies in Construction Materials, Volume 8

    Author(s): Ibrahim G. Shaaban, Osama A. Seoud

    A majority of the traditional reinforced concrete frame buildings, existing across the Middle East, lack adequate confinement in beam-column joints, or in other words, are shear deficient because they were constructed before the introduction of seismic codes for construction. This research studies the experimental behavior of full-scale beam-column space (three-dimensional) joints under displacement-controlled cyclic loading. Eleven joint specimens, included a traditionally reinforced one (without adequate shear reinforcement), a reference one with sufficient shear reinforcement according to ACI 318, and nine specimens retrofitted by ferrocement layers, were experimentally tested to evaluate a retrofit technique for strengthening shear deficient beam column joints. The studied variables were the number of layers, orientation angle of expanded wire mesh per layer, and presence of steel angles in the corners of joint specimen prior to wrapping with ferrocement layers. The experimental results showed that proper shear reinforcement for the test joints, according to ACI 318, enhanced the behavior of the specimen over that of the traditionally reinforced specimens without adequate shear reinforcement. The joints retrofitted by ferrocement layers showed higher ultimate capacity, higher ultimate displacement prior to failure (better ductility), and they did not suffer heavily damage as observed for the traditionally reinforced one. Increasing the number of ferrocement layers for retrofitted specimens led to improving performance for such specimens compared to the traditionally reinforced ones in terms of enhancing the ultimate capacity and ultimate displacement. Specimens retrofitted by ferrocement layers reinforced by expanded wire mesh of 60° orientation angle showed slightly better performance than those of 45° orientation angles. Retrofitting using steel angles in addition to ferrocement layers improves the seismic performance of the specimens, achieves better stability for stiffness degradation, attains higher capacity of the dissipated energy, and reduces the vulnerability of joints to excessive damage. Based on the experimental work in this study, it is recommended to retrofit beam-column joint specimens by two ferrocement layers in addition to steel angles as stiffeners taking the orientation angle of expanded wire mesh into consideration.





  • Event structure as a basis of semantic processing of familiar metaphors
    16 janvier 2018
    Publication date: June 2018
    Source:Cognitive Systems Research, Volume 49

    Author(s): Andrew P.L. Tobing

    In this paper I propose a model of metaphor interpretation that would account for the possibility that semantic processing of familiar metaphors no longer go through the sequential steps of alignment and projection, but may rather be established upon schematic semantic units allowing faster processing. The proposition is grounded on the notion that metaphors are formed based on peoples’ perception of what is typically associated with entities. It is suggested that in its most abstract form, these associations are essentially events, analyzed in terms of event structure.





  • CFD-DEM based numerical simulation of liquid-gas-particle mixture flow in dam break
    16 janvier 2018
    Publication date: June 2018
    Source:Communications in Nonlinear Science and Numerical Simulation, Volume 59

    Author(s): Kyung Min Park, Hyun Sik Yoon, Min Il Kim

    This study investigates the multiphase flow of a liquid-gas-particle mixture in dam break. The open source codes, OpenFOAM and CFDEMproject, were used to reproduce the multiphase flow. The results of the present study are compared with those of previous results obtained by numerical and experimental methods, which guarantees validity of present numerical method to handle the multiphase flow. The particle density ranging from 1100 to 2500 kg/m3 is considered to investigate the effect of the particle density on the behavior of the free-surface and the particles. The particle density has no effect on the liquid front, but it makes the particle front move with different velocity. The time when the liquid front reach at the opposite wall is independent of particle density. However, such time for particle front decrease as particle density increases, which turned out to be proportional to particle density. Based on these results, we classified characteristics of the movement by the front positions of the liquid and the particles. Eventually, the response of the free-surface and particles to particle density is identified by three motion regimes of the advancing, overlapping and delaying motions.





  • A Huygens immersed-finite-element particle-in-cell method for modeling plasma-surface interactions with moving interface
    16 janvier 2018
    Publication date: June 2018
    Source:Communications in Nonlinear Science and Numerical Simulation, Volume 59

    Author(s): Huijun Cao, Yong Cao, Yuchuan Chu, Xiaoming He, Tao Lin

    Surface evolution is an unavoidable issue in engineering plasma applications. In this article an iterative method for modeling plasma-surface interactions with moving interface is proposed and validated. In this method, the plasma dynamics is simulated by an immersed finite element particle-in-cell (IFE-PIC) method, and the surface evolution is modeled by the Huygens wavelet method which is coupled with the iteration of the IFE-PIC method. Numerical experiments, including prototypical engineering applications, such as the erosion of Hall thruster channel wall, are presented to demonstrate features of this Huygens IFE-PIC method for simulating the dynamic plasma-surface interactions.





  • The effect of gas and fluid flows on nonlinear lateral vibrations of rotating drill strings
    16 janvier 2018
    Publication date: June 2018
    Source:Communications in Nonlinear Science and Numerical Simulation, Volume 59

    Author(s): Lelya Khajiyeva, Askar Kudaibergenov, Askat Kudaibergenov

    In this work we develop nonlinear mathematical models describing coupled lateral vibrations of a rotating drill string under the effect of external supersonic gas and internal fluid flows. An axial compressive load and a torque also affect the drill string. The mathematical models are derived by the use of Novozhilov's nonlinear theory of elasticity with implementation of Hamilton's variation principle. Expressions for the gas flow pressure are determined according to the piston theory. The fluid flow is considered as added mass inside the curved tube of the drill string. Using an algorithm developed in the Mathematica computation program on the basis of the Galerkin approach and the stiffness switching method the numerical solution of the obtained approximate differential equations is found. Influences of the external loads, drill string angular speed of rotation, parameters of the gas and fluid flows on the drill string vibrations are shown.





  • Supercritical nonlinear parametric dynamics of Timoshenko microbeams
    16 janvier 2018
    Publication date: June 2018
    Source:Communications in Nonlinear Science and Numerical Simulation, Volume 59

    Author(s): Hamed Farokhi, Mergen H. Ghayesh

    The nonlinear supercritical parametric dynamics of a Timoshenko microbeam subject to an axial harmonic excitation force is examined theoretically, by means of different numerical techniques, and employing a high-dimensional analysis. The time-variant axial load is assumed to consist of a mean value along with harmonic fluctuations. In terms of modelling, a continuous expression for the elastic potential energy of the system is developed based on the modified couple stress theory, taking into account small-size effects; the kinetic energy of the system is also modelled as a continuous function of the displacement field. Hamilton's principle is employed to balance the energies and to obtain the continuous model of the system. Employing the Galerkin scheme along with an assumed-mode technique, the energy terms are reduced, yielding a second-order reduced-order model with finite number of degrees of freedom. A transformation is carried out to convert the second-order reduced-order model into a double-dimensional first order one. A bifurcation analysis is performed for the system in the absence of the axial load fluctuations. Moreover, a mean value for the axial load is selected in the supercritical range, and the principal parametric resonant response, due to the time-variant component of the axial load, is obtained – as opposed to transversely excited systems, for parametrically excited system (such as our problem here), the nonlinear resonance occurs in the vicinity of twice any natural frequency of the linear system; this is accomplished via use of the pseudo-arclength continuation technique, a direct time integration, an eigenvalue analysis, and the Floquet theory for stability. The natural frequencies of the system prior to and beyond buckling are also determined. Moreover, the effect of different system parameters on the nonlinear supercritical parametric dynamics of the system is analysed, with special consideration to the effect of the length-scale parameter.





  • Nonlinear dynamics of a circular piezoelectric plate for vibratory energy harvesting
    16 janvier 2018
    Publication date: June 2018
    Source:Communications in Nonlinear Science and Numerical Simulation, Volume 59

    Author(s): Tian-Chen Yuan, Jian Yang, Li-Qun Chen

    Nonlinear behaviors are investigated for a vibration-based energy harvester. The harvester consists of a circular composite plate with the clamped boundary, a proof mass and two steel rings. The lumped parameter model of the harvester is established and the parameters are identified from the experiment. The measured nonlinear behaviors can be approximately described by the lumped model. Both the experimental and the numerical results demonstrate that the circular plate harvester has soft characteristics under low excitation and both hard characteristics and soft characteristics under high excitation. The experimental results show that the output voltage can achieve over 35 V (about 50 mW) and more than 14 Hz of bandwidth with 25 kΩ load resistance.





  • Regeneration mechanism for skin and peripheral nerves clarified at the organ and molecular scales
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Biomedical Engineering, Volume 6

    Author(s): Ioannis V. Yannas, Dimitrios S. Tzeranis, Peter T.C. So

    This article is a review of current research on the mechanism of regeneration of skin and peripheral nerves based on use of collagen scaffolds, particularly the dermis regeneration template (DRT), which is widely used clinically. DRT modifies the normal wound healing process, converting it from wound closure by contraction and scar formation to closure by regeneration. DRT achieves this modification by blocking wound contraction, which spontaneously leads to cancellation of scar formation, a process secondary to contraction. Contraction blocking by DRT is the result of a dramatic phenotype change in contractile cells (myofibroblasts, MFB) which follows specific binding of integrins α1β1 and α2β1 onto hexapeptide ligands, probably GFOGER and GLOGER, that are naturally present on the surface of collagen fibers in DRT. The methodology of organ regeneration based on use of DRT has been recently extended from traumatized skin to diseased skin. Successful extension of the method to other organs in which wounds heal by contraction is highly likely though not yet attempted. This regenerative paradigm is much more advanced both in basic mechanistic understanding and clinical use than methods based on tissue culture or stem cells. It is also largely free of risk and has shown decisively lower morbidity and lower cost than organ transplantation.





  • Messages from the voices within: regulation of signaling by proteins of the nuclear lamina
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Cell Biology, Volume 52

    Author(s): Larry Gerace, Olga Tapia

    The nuclear lamina (NL) is a protein scaffold lining the nuclear envelope that consists of nuclear lamins and associated transmembrane proteins. It helps to organize the nuclear envelope, chromosomes, and the cytoplasmic cytoskeleton. The NL also has an important role in regulation of signaling, as highlighted by the wide range of human diseases caused by mutations in the genes for NL proteins with associated signaling defects. This review will consider diverse mechanisms for signaling regulation by the NL that have been uncovered recently, including interaction with signaling effectors, modulation of actin assembly and compositional alteration of the NL. Cells with discrete NL mutations often show disruption of multiple signaling pathways, however, and for the most part the mechanistic basis for these complex phenotypes remains to be elucidated.





  • Mesh electronics: a new paradigm for tissue-like brain probes
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Neurobiology, Volume 50

    Author(s): Guosong Hong, Xiao Yang, Tao Zhou, Charles M Lieber

    Existing implantable neurotechnologies for understanding the brain and treating neurological diseases have intrinsic properties that have limited their capability to achieve chronically-stable brain interfaces with single-neuron spatiotemporal resolution. These limitations reflect what has been dichotomy between the structure and mechanical properties of living brain tissue and non-living neural probes. To bridge the gap between neural and electronic networks, we have introduced the new concept of mesh electronics probes designed with structural and mechanical properties such that the implant begins to ‘look and behave’ like neural tissue. Syringe-implanted mesh electronics have led to the realization of probes that are neuro-attractive and free of the chronic immune response, as well as capable of stable long-term mapping and modulation of brain activity at the single-neuron level. This review provides a historical overview of a 10-year development of mesh electronics by highlighting the tissue-like design, syringe-assisted delivery, seamless neural tissue integration, and single-neuron level chronic recording stability of mesh electronics. We also offer insights on unique near-term opportunities and future directions for neuroscience and neurology that now are available or expected for mesh electronics neurotechnologies.





  • Implantable, wireless device platforms for neuroscience research
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Neurobiology, Volume 50

    Author(s): Philipp Gutruf, John A Rogers

    Recently developed classes of ultraminiaturized wireless devices provide powerful capabilities in neuroscience research, as implantable light sources for simulation/inhibition via optogenetics, as integrated microfluidic systems for programmed pharmacological delivery and as multimodal sensors for physiological measurements. These platforms leverage basic advances in biocompatible materials, semiconductor device designs and systems engineering concepts to afford modes of operation that are qualitatively distinct from those of conventional approaches that tether animals to external hardware by means of optical fibers, electrical cables and/or fluidic tubing. Neuroscience studies that exploit the unique features of these technologies enable insights into neural function through targeted stimulation, inhibition and recording, with spatially and genetically precise manipulation of neural circuit activity. Experimental possibilities include studies in naturalistic, three dimensional environments, investigations of pair-wise or group related social interactions and many other scenarios of interest that cannot be addressed using traditional hardware.





  • Nanomaterials at the neural interface
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Neurobiology, Volume 50

    Author(s): Denis Scaini, Laura Ballerini

    Interfacing the nervous system with devices able to efficiently record or modulate the electrical activity of neuronal cells represents the underlying foundation of future theranostic applications in neurology and of current openings in neuroscience research. These devices, usually sensing cell activity via microelectrodes, should be characterized by safe working conditions in the biological milieu together with a well-controlled operation-life. The stable device/neuronal electrical coupling at the interface requires tight interactions between the electrode surface and the cell membrane. This neuro-electrode hybrid represents the hyphen between the soft nature of neural tissue, generating electrical signals via ion motions, and the rigid realm of microelectronics and medical devices, dealing with electrons in motion. Efficient integration of these entities is essential for monitoring, analyzing and controlling neuronal signaling but poses significant technological challenges. Improving the cell/electrode interaction and thus the interface performance requires novel engineering of (nano)materials: tuning at the nanoscale electrode's properties may lead to engineer interfacing probes that better camouflaged with their biological target. In this brief review, we highlight the most recent concepts in nanotechnologies and nanomaterials that might help reducing the mismatch between tissue and electrode, focusing on the device's mechanical properties and its biological integration with the tissue.





  • Effect of temperature, ion type and ionic strength on dynamic viscoelastic, steady-state and dilute-solution properties of Descurainia sophia seed gum
    16 janvier 2018
    Publication date: June 2018
    Source:Food Hydrocolloids, Volume 79

    Author(s): Mousa Hamidabadi Sherahi, Maral Shadaei, Elnaz Ghobadi, Fatemeh Zhandari, Zohre Rastgou, Seyed Mohammad Bagher Hashemi

    In this study, dilute solution, steady state and dynamic rheological properties of Descurainia sophia seed gum (DSSG) were investigated. With increasing the solution temperature, the intrinsic viscosity and coil dimension of DSSG decreased. The intrinsic viscosity of DSSG was essentially constant over a very extensive range of ion concentrations. Activation energy and chain flexibility of DSSG were found to be 1.1 × 107 (J/kg) and 1353 (1/K), respectively. DSSG can be introduced as good encapsulator in food and pharmaceutical systems due to low degree of chain flexibility. Steady shear measurements showed shear thinning behavior at all tested temperatures, regardless of ion type and ionic strength. Addition of NaCl and increasing temperature caused a decrease in consistency coefficient and an increase in the flow behavior index. On the other hand, at high CaCl2 concentration, the consistency coefficient of DSSG increased. The values of tan δ in all tested conditions were lower than one, but more than 0.1, revealing weak gel-like behavior. The frequency sweep results revealed that DSSG solution had weak gel behavior at different ions types and ionic strengths: as dynamic moduli increased with increasing frequency and G′ was always superior to G″. The data obtained in the present study and the results thereof can be useful when considering the impact of salts, and/or processing parameter such as temperature on food systems.

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  • Calcium-induced gelation of whey protein aggregates: Kinetics, structure and rheological properties
    16 janvier 2018
    Publication date: June 2018
    Source:Food Hydrocolloids, Volume 79

    Author(s): Anna Kharlamova, Taco Nicolai, Christophe Chassenieux

    Cold gelation of preformed whey protein aggregates was induced by adding CaCl2. The gels were investigated using rheology and confocal laser scanning microscopy in order to study the evolution with time of the elasticity and the microstructure as a function of the protein and calcium concentrations, the size and shape of the aggregates and the temperature. The net charge density of the proteins was fixed, but the effect of adding CaCl2 on the pH was investigated and was related to specific binding of Ca2+ to the proteins. The gelation process was correlated with the effective charge density of the proteins that was reduced by specific binding of Ca2+ to the proteins. Increasing the temperature or the CaCl2 concentration ([CaCl2]) strongly increased the rate of gelation, but did not influence the stiffness or the structure of the gels. The temperature dependence of the gelation time was characterized by an activation energy of 210 kJ/mol independent of the CaCl2 ([CaCl2] = 2–50 mM) and protein concentrations (C = 5–60 g/L). Increasing the protein concentration not only sped up gelation, but also increased the gel stiffness and rendered the gels more homogeneous. The size of fractal aggregates did not influence the gel structure, the gel stiffness and very little the gelation rate. Gelation of fractal aggregates was compared with that of microgels, which formed weaker and more heterogeneous gels at the same protein concentration. It is shown how syneresis can be avoided by a proper choice of [CaCl2], temperature and aggregate size.

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  • Release kinetics and antimicrobial properties of carvacrol encapsulated in electrospun poly-(ε-caprolactone) nanofibres. Application in starch multilayer films
    16 janvier 2018
    Publication date: June 2018
    Source:Food Hydrocolloids, Volume 79

    Author(s): Alina Tampau, Chelo González-Martínez, Amparo Chiralt

    Electrospun poly-(ε-caprolactone) (PCL) fibre mats encapsulating Carvacrol (CA) were obtained with good encapsulation efficiency (85%) and CA load (11% in the fibre). These mats were effective at controlling the growth of Escherichia coli, when the surface density of CA loaded fibres was 1.2 or 1.8 mg/cm2, in line with the CA released into the culture medium that exceeded the MIC of the bacteria. However, they were not effective at controlling the growth of Listeria innocua, since a greater release of CA was necessary to achieve the MIC of this bacterium. It was not only the CA load in the fibres, but also its release capacity in the media that determined the antimicrobial effect. The fibre showed higher release rate and ratio in less polar simulants, D1 (50% ethanol) and D2 (isooctane) (representing fatty foodstuff), where practically the total amount of CA was released; whereas in more polar systems (simulants A (10% ethanol) and B (3% acetic acid)) a more limited CA delivery (60–75%) occurred, at a slower rate. The antimicrobial action of the active PCL mats was reproduced in multilayer starch films containing the CA-loaded electrospun PCL fibres between two starch sheets, with a slightly delayed response. In the multilayer films, a great reduction in the water vapour permeability was also observed with respect to that of starch films, without relevant changes in other functional properties of the films for packaging purposes.

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  • Efficient extraction of pectin from sisal waste by combined enzymatic and ultrasonic process
    16 janvier 2018
    Publication date: June 2018
    Source:Food Hydrocolloids, Volume 79

    Author(s): Yishuo Yang, Zhaomei Wang, Die Hu, Kaijun Xiao, Jian-Yong Wu

    Combined enzymatic and ultrasonic treatment was evaluated for efficient extraction of pectin from sisal waste in comparison with other extraction methods. The sequential treatment with enzyme (Celluclast 1.5 L) followed by ultrasound of sisal waste attained a much higher pectin yield of 31.1% than the ultrasound followed by enzyme, 14.6%. The pectin yield attained with the combined enzymatic/ultrasonic extraction was also higher than enzymatic extraction (9.4%), ultrasonic extraction (11.9%) and acidic extraction (5.8%). The pectin attained using the combined enzymatic/ultrasonic extraction (PEU) exhibited a higher galacturonic acid content (62.88%) and a higher degree of esterification (49.64%), indicating a better preserved polymer chain than that using acidic extraction (PA). PEU had a higher molar mass (7.65 × 105 g/mol) and a lower Mw/Mn than PA. Meanwhile, all sisal pectins showed the similar sugar composition regardless of the extraction methods according to FT-IR analysis. The results of rheological test showed that PEU in water turned from gel to liquid with increasing angle-frequency, while PA remained in a gel state. Compared with PA, the viscoelastic properties of PEU were more sensitive to temperature changes. SEM observation of the sisal residues after pectin extraction revealed a synergistic effect of the enzymatic and ultrasonic treatment on the solid structure, which may be contributable to the improved pectin extraction efficiency. The results from the present study suggest that the combination of enzymatic and ultrasonic extraction is an efficient process strategy for production of high quality pectins.

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  • Centrifuge model tests on the use of geosynthetic layer as an internal drain in levees
    16 janvier 2018
    Publication date: June 2018
    Source:Geotextiles and Geomembranes, Volume 46, Issue 3

    Author(s): R.K. Saran, B.V.S. Viswanadham

    The objective of the paper is to examine the use of a geosynthetic layer as an internal drain in a levee subjected to flooding through centrifuge model tests. Three levee sections, having an upstream slope of 1V:1H and downstream slope of 1.5V:1H, were modelled at 30 gravities in a 4.5 m radius large beam centrifuge available at IIT Bombay. Out of the three levee sections modelled, one levee section was without any drainage layer (or clogged drain), while the other two had different types of horizontal drainage layers, namely, sand and nonwoven geotextile layer. The flood was induced with the help of a custom developed and calibrated in-flight flood simulator. At the onset of flood and subsequent seepage, pore water pressures within levee section, and surface settlements were measured using pore water transducers (PPTs) and linear variable differential transformer (LVDTs) respectively. Digital image analysis was employed to trace surface settlements, and downstream slope face movements at the onset of flooding during centrifuge tests. Levee section without any horizontal drain or clogged drain experienced a catastrophic failure. In comparison, the levee sections with an internal drain (sand/geotextile) remained stable at the onset of flooding. In the case of a levee with a sand drainage layer, the phreatic surface was observed to confine within the levee section itself, whereas it was found to migrate towards toe gradually in the levee section with a nonwoven geotextile layer. It is attributed to either due to suppression of drainage capacity of nonwoven geotextile layer or due to washing of fine particles into pores of nonwoven geotextile layer. Further, seepage and stability analyses were carried out numerically and compared with centrifuge test results. In order to address blocking of pores of nonwoven geotextile layer, a concept of sandwiching nonwoven geotextile layer with sand was explored. By sandwiching nonwoven geotextile layer with sand on either side, the thickness of drainage layer can be of the order of 0.05H.





  • Numerical analysis of geocell-reinforced retaining wall failure modes
    16 janvier 2018
    Publication date: June 2018
    Source:Geotextiles and Geomembranes, Volume 46, Issue 3

    Author(s): Fei Song, Huabei Liu, Liqiu Ma, Hongbing Hu

    Numerical analyses on the failure mode of geocell-reinforced retaining walls by the finite element strength reduction technique are reported. The effectiveness of the numerical model was validated by the centrifuge model test results. Parametric studies were conducted using the calibrated finite element procedure to investigate the effects of the apparent cohesion of geocell-reinforced soil, the friction between the wall base and the footing, the weak interlayer in the wall, and the layout of the two-tiered geocell-reinforced retaining wall on the failure surface and the factor of safety. The study results indicated that when the apparent cohesion was very large, or the friction between the wall and the footing was small, or there existed a weak interlayer in the wall, sliding failure was found to occur in geocell-reinforced retaining walls, similar to the failure mode of rigid retaining walls. Coulomb's wedge theory was suitable for the stability analysis of geocell-reinforced retaining wall in these conditions. However, in other conditions, which are more relevant in engineering applications, the failure mode of geocell-reinforced retaining walls was similar to that of slopes and the strength reduction technique for the stability analysis of slope may be suitable to analyze the stability of geocell-reinforced retaining walls.





  • Full-scale mechanically stabilized earth (MSE) walls under strip footing load
    16 janvier 2018
    Publication date: June 2018
    Source:Geotextiles and Geomembranes, Volume 46, Issue 3

    Author(s): Hamzeh Ahmadi, Adam Bezuijen

    This study analyses two full-scale model tests on mechanically stabilized earth (MSE) walls. One test was conducted with a rigid and one with a flexible wall face. Other parameters were the same in these two tests, like the number and type of geogrid layers, the vertical distance between the layers and the soil type. The loads and strains on the reinforcement are measured as function of the horizontal and vertical earth pressure and compared with analytical models. Specifics regarding the behavior of the geogrids under the compaction load during the construction of the model and under strip footing load are included in the study. Results are compared with AASHTO and the empirical K-stiffness method. In this study, an analytical method is developed for the MSE walls taking into account the facing panel rigidity both after backfill construction and after strip footing load. There is good agreement between the proposed analytical method and the experimental results considering the facing panel rigidity. The results indicate that the tensile force on reinforcement layers for rigid facing is less than the flexible facing. The maximum strains in the reinforcement layers occurred in the upper layers right below the strip footing load. The maximum wall deflection for the flexible facing is more than for the rigid facing. The maximum deflection was at the top of the wall for the rigid facing and occurred at z/H = 0.81 from top of the wall for the flexible facing.





  • Uniaxial compression behavior of geotextile encased stone columns
    16 janvier 2018
    Publication date: June 2018
    Source:Geotextiles and Geomembranes, Volume 46, Issue 3

    Author(s): Jian-Feng Chen, Xing-Tao Wang, Jian-Feng Xue, Yue Zeng, Shou-Zhong Feng

    The bearing capacity and failure mechanism of encased stone columns are affected by many factors such as encasement length, relative density, strength and stiffness of the encasement material. In soft soils where surrounding soil pressure is low, especially in the top section, the stone columns may be close to a uniaxial compression state, where the uniaxial compression strength controls the bearing capacity of the stone columns. A series of large-scale triaxial tests on ordinary stone columns and uniaxial tests on geotextile encased stone columns have been performed. The stone columns were 300 mm in diameter and 600 mm in height. Samples of four different relative densities, and five types of geotextiles were used in the tests to study the effect of initial void ratio and encasing materials on the uniaxial compression behavior of the stone columns. The results show the uniaxial compressive strength of the encased stone columns is not affected by the initial void ratio but mainly by the tensile strength of the encasing geotextiles. The stress strain curves of the encased stone columns under uniaxial loading condition are nearly liner before failure, which is similar to the tensile behavior of the geotextiles.





  • A latencies tolerant model predictive control approach to damp Inter-area oscillations in delayed power systems
    16 janvier 2018
    Publication date: June 2018
    Source:International Journal of Electrical Power & Energy Systems, Volume 98

    Author(s): Alexander Molina-Cabrera, Mario A. Ríos, Yvon Besanger, Nouredine HadjSaid

    Automatic voltage regulators and power system stabilizers have been employed successfully to deal with fast dynamics associated to local oscillations phenomena. Whereas, inter-area oscillations damping in large power systems requires remote feedback controllers fed by Wide Area Monitoring Systems (WAMS). Although these improvements in the inter-area oscillations behavior have been effective, a new challenge emerges: reaching stability with a closed loop control despite latencies due to measurements taken far away from the control centre. The research was motivated by the need for modernization of power systems capable of dealing with control difficulties in centralised WAMS for damping inter-area oscillations in power systems caused by delays in the communication system. Herein, time delay and control problems are addressed separately. The time delay problem is solved by a database based time compensation solution relying on the most updated available state of the system. The control problem is solved by a Model Predictive Control (MPC) with terminal cost and constraint set to handle complexities due to nonlinearities of the power system, the large scale of the problem and the parametric variations. Both solutions work in a coordinated way with local controllers to implement a decentralised coordinated strategy that manages slow global dynamics and fast local dynamics as well. The integrated proposed approach is called Time-Delay-Tolerant Model Predictive Control (TDT-MPC). Coordinated and coherent performance of the two TDT-MPC components (Kalman compensator and MPC) is achieved thanks to unifying power system reference models for both strategies. The approach has been tested on the IEEE 39 system and validated with time domain nonlinear simulations, obtaining post-fault damped oscillations and a good tracking of new power references when tripping tie lines.





  • The influence of damping resistance on first swing stability of turbine generator considering stator transient
    16 janvier 2018
    Publication date: June 2018
    Source:International Journal of Electrical Power & Energy Systems, Volume 98

    Author(s): Guorui Xu, Yang Zhan, Haisen Zhao, Xiaofang Liu

    Generally, the ignored stator transient of turbine generator result in the unidirectional electromagnetic torque caused by damping resistance is neglected. While, the unidirectional electromagnetic torque has a braking effect which can reduce the rotor acceleration following the disturbance and improve the stability of power system. With a 300 MW turbine generator as an example, the large disturbance characteristic and First Swing Stability (FSS) limit are calculated by Time-Step Finite Element Model (T-S FEM) and three practical models of turbine generator in this paper. The unidirectional electromagnetic torque caused by stator transient is investigated and its important role in FSS is analyzed. Since there are several material options for damping windings, the influence of damping resistance on the large disturbance characteristic and FSS limit are calculated and compared under different damping resistance. The result shows that the FSS limits calculated by the practical model with stator transient are increased than that without stator transient; the FSS limits of turbine generator with damping windings made from stainless steel are larger than that made from aluminum and beryllium bronze by the four kinds of generator models. The result provides theoretic basis of generator modeling for precise simulation of power systems.





  • H∞ current damping control of DFIG based wind farm for sub-synchronous control interaction mitigation
    16 janvier 2018
    Publication date: June 2018
    Source:International Journal of Electrical Power & Energy Systems, Volume 98

    Author(s): Yun Wang, Qiuwei Wu, Rong Yang, Guoqing Tao, Zhaoxi Liu

    This paper proposes an H damping controller for the doubly-fed induction generator (DFIG) based wind farm (WF) to mitigate sub-synchronous control interactions (SSCI) with series capacitor compensated lines. A multi-input multi-output (MIMO) uncertain state-space model is developed to reflect the main SSCI characteristics considering the uncertainties of wind speed, series compensation (SC) levels and system parameters. The SSCI is analyzed using the eigenvalue analysis of the uncertain system model. In order to damp the SSCI between the WF and series capacitor compensated lines under uncertainties, an H damping controller is designed for the rotor side converter (RSC). The weighting functions are designed to meet the mitigation requirements of sub-synchronous oscillation currents and output power. The robust stability (RS) and robust performance (RP) of the system are validated by the µ analysis. The performance of the H damping controller is demonstrated by time domain simulations of a 90 MW wind farm model with different wind speed, and SC levels. The case study with 6 m/s wind speed and 70% SC level shows superior performance of the H damping controller.





  • Optimizing fin design for a PCM-based thermal storage device using dynamic Kriging
    16 janvier 2018
    Publication date: June 2018
    Source:International Journal of Heat and Mass Transfer, Volume 121

    Author(s): Mike Augspurger, K.K. Choi, H.S. Udaykumar

    A key challenge in the development of a practical thermal storage device (TSD) is the low thermal conductivity of common phase change materials (PCM). This low conductivity impedes both heat input and extraction. The most common solution is to use conductive metal fins to spread heat through the device. However, optimizing the effectiveness of the container and the fin arrangement is difficult due to the large number of potential design parameters. This paper develops a strategy to make simulation-based optimization process affordable and accurate. First, numerical techniques are designed to accurately and efficiently compute heat and mass transport in a variety of geometries without generating grids to conform to each geometry. This facilitates rapid prototyping and mitigates the expense of individual simulations. Second, a pre-screening process identifies the independent variables with the largest and most nonlinear effect on the objective function in the optimization process, thus narrowing the parameter space. Finally, a dynamic Kriging-based optimization approach constructs a multidimensional response surface using sparse input datasets; the response surface is then used to identify an optimal design. The combination of the above three strategies is shown to result in an approach that can aid in the design of optimal thermal storage devices that rely on a mixture of PCM and metal fins.





  • A fractal method to calculate the permeability for compressible gas flow through a porous restrictor in aerostatic bearings
    16 janvier 2018
    Publication date: June 2018
    Source:International Journal of Heat and Mass Transfer, Volume 121

    Author(s): Hailong Cui, Yang Wang, Min Zhang, Wei Wang, Chunjiang Zhao

    In this study, a fractal method was applied to calculate the permeability for compressible gas flow through a porous restrictor in aerostatic bearings. A mathematical permeability model without any empirical parameters was established according to the fractal theory, gas conservation equations and Darcy's Law. The box-counting method was applied to determine the pore area fractal dimension and tortuosity fractal dimension. The effects of the scanning magnification and image size on the calculation results of the fractal dimension were also investigated. The porosity characteristics of the scanning images have obvious self-similarity, and the diameters of the maximum pore and minimum pore satisfy the fundamental condition of fractal analysis. Magnification ranges of 50–100 × and 1–2k × were appropriate for calculating the permeability of ceramic and graphite porous restrictors, respectively. Image pixels of 512 × 512 were sufficient to ensure the accuracy of permeability calculation. In addition, an experimental platform was constructed to measure the permeability of ceramic and graphite porous restrictors. The differences between the calculation results and the experimental data for both ceramic and graphite porous restrictors were less than 10%, which demonstrated that the permeability for compressible gas flow through a porous restrictor in aerostatic bearings can be accurately predicted by the fractal calculation method.





  • Conditioning and error analysis of nonlocal operators with local boundary conditions
    16 janvier 2018
    Publication date: June 2018
    Source:Journal of Computational and Applied Mathematics, Volume 335

    Author(s): Burak Aksoylu, Adem Kaya

    We study the conditioning and error analysis of novel nonlocal operators in 1D with local boundary conditions. These operators are used, for instance, in peridynamics (PD) and nonlocal diffusion. The original PD operator uses nonlocal boundary conditions (BC). The novel operators agree with the original PD operator in the bulk of the domain and simultaneously enforce local periodic, antiperiodic, Neumann, or Dirichlet BC. We prove sharp bounds for their condition numbers in the parameter δ only, the size of nonlocality. We accomplish sharpness both rigorously and numerically. We also present an error analysis in which we use the Nyström method with the trapezoidal rule for discretization. Using the sharp bounds, we prove that the error bound scales like O ( h 2 δ 2 ) and verify the bound numerically. The conditioning analysis of the original PD operator was studied by Aksoylu and Unlu (2014). For that operator, we had to resort to a discretized form because we did not have access to the eigenvalues of the analytic operator. Due to analytical construction, we now have direct access to the explicit expression of the eigenvalues of the novel operators in terms of δ . This gives us a big advantage in finding sharp bounds for the condition number without going to a discretized form and makes our analysis easily accessible. We prove that the novel operators have ill-conditioning indicated by δ 2 sharp bounds. For the original PD operator, we had proved the similar δ 2 ill-conditioning when the mesh size approaches 0. From the conditioning perspective, we conclude that the modification made to the original PD operator to obtain the novel operators that accommodate local BC is minor. Furthermore, the sharp δ 2 bounds shed light on the role of δ in nonlocal problems.





  • Dimension and basis construction for C2-smooth isogeometric spline spaces over bilinear-like G2 two-patch parameterizations
    16 janvier 2018
    Publication date: June 2018
    Source:Journal of Computational and Applied Mathematics, Volume 335

    Author(s): Mario Kapl, Vito Vitrih

    A particular class of planar two-patch geometries, called bilinear-like G 2 two-patch geometries, is introduced. This class includes the subclass of all bilinear two-patch parameterizations and possesses similar connectivity functions along the patch interface. It is demonstrated that the class of bilinear-like G 2 two-patch parameterizations is much wider than the class of bilinear parameterizations and can approximate with good quality given generic two-patch parameterizations. We investigate the space of C 2 -smooth isogeometric functions over this specific class of two-patch geometries. The study is based on the equivalence of the C 2 -smoothness of an isogeometric function and the G 2 -smoothness of its graph surface (cf. Groisser and Peters (2015) and Kapl et al. (2015). The dimension of the space is computed and an explicit basis construction is presented. The resulting basis functions possess simple closed form representations, have small local supports, and are well-conditioned. In addition, we introduce a subspace whose basis functions can be generated uniformly for all possible configurations of bilinear-like G 2 two-patch parameterizations. Numerical results obtained by performing L 2 -approximation and solving Poisson’s equation indicate that already the subspace possesses optimal approximation properties.





  • Does Conservative Rehabilitation Program Lead to Long-Term Stiffness after Arthroscopic Rotator Cuff Repair?
    16 janvier 2018
    Publication date: June 2018
    Source:Journal of Orthopaedics, Trauma and Rehabilitation, Volume 24

    Author(s): Chun Ming Chan, Pang Hei Li

    Background Evidence on the ideal rehabilitation program for arthroscopic rotator cuff repair is lacking. Most data and results are conflicting with no consensus made. This study aims to compare between an early aggressive program with immediate postoperative range-of-motion (ROM) exercises and a more conservative program with early restriction of motion in Hong Kong Chinese population. Materials and methods We retrospectively evaluated 37 arthroscopic rotator cuff repair cases who underwent a standardized delayed rehabilitation protocol of immobilization for 4 weeks to 6 weeks before formal passive ROM exercises. Patients were evaluated at 3 months, 6 months, and 12 months after the surgery, for which they would be tested on passive forward flexion (FF). They were categorized as “stiff” if FF was less than 100°. Constant score, Disability of Arm, Shoulder and Hand (DASH) score, Visual Analog Scale (VAS) score, and isometric abduction power deficit percentage were parameters to assess the functional outcome, and they were obtained in all of the patients' last follow-up assessments. Results Two cases (5.4%) are considered “stiff” 6 months after the surgery. At 1 year, the stiffness in both cases resolved, resulting in 0% rate of stiffness. The mean FF at 1 year was 153.33 ± 20.15, which is comparable to the literature. Two cases (5.4%) of clinical retear occurred. Mean Constant score at the latest follow-up was 62.4 ± 13.2. Mean VAS score was 1.1 ± 1.8 at rest and 2.8 ± 2.0 on exertion. Mean DASH score was 25.3 ± 21.9. Mean isometric abduction power deficit was 42.7% ± 0.2%. Discussion Historically, due to concerns on long-term stiffness, an early aggressive postoperative rehabilitation protocol was used. We found that an early restriction of ROM with 4 weeks to 6 weeks of immobilization did not lead to long-term stiffness and functional disadvantage. This includes patients with stiffness even before the operations. Conclusions Immobilization for 4 weeks to 6 weeks after arthroscopic rotator cuff repair does not result in long-term stiffness and may even be beneficial to cuff tendon healing.





  • On developing an optimal design procedure for a bimorph piezoelectric cantilever energy harvester under a predefined volume
    16 janvier 2018
    Publication date: June 2018
    Source:Mechanical Systems and Signal Processing, Volume 106

    Author(s): Noha Aboulfotoh, Jens Twiefel

    A typical vibration harvester is tuned to operate at resonance in order to maximize the power output. There are many design parameter sets for tuning the harvester to a specific frequency, even for simple geometries. This work studies the impact of the geometrical parameters on the harvested power while keeping the resonance frequency constant in order to find the combination of the parameters that optimizes the power under a predefined volume. A bimorph piezoelectric cantilever is considered for the study. It consists of two piezoelectric layers and a middle non-piezoelectric layer and holds a tip mass. A theoretical model was derived to obtain the system parameters and the power as functions of the design parameters. Formulas for the optimal load resistance that provide maximum power capability at resonance and anti-resonance frequency were derived. The influence of the width on the power is studied, considering a constant mass ratio (between the tip mass and the mass of the beam). This keeps the resonance frequency constant while changing the width. The influence of the ratio between the thickness of the middle layer and that of the piezoelectric layer is also studied. It is assumed that the total thickness of the cantilever is constant and the middle layer has the same mechanical properties (elasticity and density) as the piezoelectric layer. This keeps the resonance frequency constant while changing the ratio between the thicknesses. Finally, the influence of increasing the free length as well as of increasing the mass ratio on the power is investigated. This is done by first, increasing each of them individually and secondly, by increasing each of them simultaneously while increasing the total thickness under the condition of maintaining a constant resonance frequency. Based on the analysis of these influences, recommendations as to how to maximize the geometrical parameters within the available volume and mass are presented.





  • Vehicle yaw stability control via H∞ gain scheduling
    16 janvier 2018
    Publication date: June 2018
    Source:Mechanical Systems and Signal Processing, Volume 106

    Author(s): Jinhua Zhang, Weichao Sun, Zhiguang Feng

    Yaw stability control (YSC) is rather significant in a vehicle lateral motion, since it can considerably reduce casualties caused by vehicle instability. Nevertheless with the vehicle running, the parameters, such as vehicle mass and moment of inertial, can be perturbed because of variation of capacity, loadage and consumption of fuel, hence some of nominal controllers cannot always work satisfactorily. To overcome the aforementioned deficiency, a gain scheduled H YSC controller is developed in this paper, taking the vehicle mass and moment of inertial as the scheduled variables, now that the gain scheduled H controller can guarantee both the robustness against parameter perturbation and the adjustability of tracking accuracy. Then the constructed controller is verified via numerical simulation and MATLAB-CarSim coalition simulation. The simulation results indicate that the designed controller can indeed improve the vehicle handing performance under circumstance of lateral stability.





  • Displacement and force coupling control design for automotive active front steering system
    16 janvier 2018
    Publication date: June 2018
    Source:Mechanical Systems and Signal Processing, Volume 106

    Author(s): Wanzhong Zhao, Han Zhang, Yijun Li

    A displacement and force coupling control design for active front steering (AFS) system of vehicle is proposed in this paper. In order to investigate the displacement and force characteristics of the AFS system of the vehicle, the models of AFS system, vehicle, tire as well as the driver model are introduced. Then, considering the nonlinear characteristics of the tire force and external disturbance, a robust yaw rate control method is designed by applying a steering motor to generate an active steering angle to adjust the yaw stability of the vehicle. Based on mixed H2/H control, the system robustness and yaw rate tracking performance are enforced by H norm constraint and the control effort is captured through H2 norm. In addition, based on the AFS system, a planetary gear set and an assist motor are both added to realize the road feeling control in this paper to dismiss the influence of extra steering angle through a compensating method. Evaluation of the overall system is accomplished by simulations and experiments under various driving condition. The simulation and experiment results show the proposed control system has excellent tracking performance and road feeling performance, which can improve the cornering stability and maneuverability of vehicle.





  • Vibration control of an energy regenerative seat suspension with variable external resistance
    16 janvier 2018
    Publication date: June 2018
    Source:Mechanical Systems and Signal Processing, Volume 106

    Author(s): Donghong Ning, Shuaishuai Sun, Haiping Du, Weihua Li, Nong Zhang

    In this paper, an energy regenerative seat suspension with a variable external resistance is proposed and built, and a semi-active controller for its vibration control is also designed and validated. The energy regenerative seat suspension is built with a three-phase generator and a gear reducer, which are installed in the scissors structure centre of the seat suspension, and the vibration energy is directly harvested from the rotary movement of suspension’s scissors structure. The electromagnetic torque of the semi-active seat suspension actuator is controlled by an external variable resistor. An integrated model including the seat suspension’s kinematics and the generator is built and proven to match the test result very well. A simplified experimental phenomenon model is also built based on the test results for the controller design. A state feedback H controller is proposed for the regenerative seat suspension’s semi-active vibration control. The proposed regenerative seat suspension and its controller are validated with both simulations and experiments. A well-tuned passive seat suspension is applied to evaluate the regenerative seat’s performance. Based on ISO 2631-1, the frequency-weighted root mean square (FW-RMS) acceleration of the proposed seat suspension has a 22.84% reduction when compared with the passive one, which indicates the improvement of ride comfort. At the same time, the generated RMS power is 1.21 W. The proposed regenerative seat suspension can greatly improve the driver’s ride comfort and has the potential to be developed to a self-powered semi-active system.





  • Dynamic modeling and vibration characteristics analysis of the aero-engine dual-rotor system with Fan blade out
    16 janvier 2018
    Publication date: June 2018
    Source:Mechanical Systems and Signal Processing, Volume 106

    Author(s): Pingchao Yu, Dayi Zhang, Yanhong Ma, Jie Hong

    Fan Blade Out (FBO) from a running rotor of the turbofan engine will not only introduce the sudden unbalance and inertia asymmetry into the rotor, but also apply large impact load and induce rotor-to-stator rubbing on the rotor, which makes the mass, gyroscopic and stiffness matrixes of the dynamic equation become time-varying and highly nonlinear, consequently leads to the system’s complicated vibration. The dynamic analysis of the aero-engine rotor system is one essential requirement of the authorities and is vital to the aero-engine’s safety. The paper aims at studying the dynamic responses of the complicated dual-rotor systems at instantaneous and windmilling statuses when FBO event occurs. The physical process and mechanical characteristics of the FBO event are described qualitatively, based on which the dynamic modeling for an aero-engine dual-rotor system is carried out considering several excitations caused by FBO. Meanwhile the transient response during the instantaneous status and steady-state response at the windmilling status are obtained. The results reveal that the sudden unbalance can induce impact load to the rotor, and lead to the sharp increase of the vibration amplitude and reaction force. The rub-impact will apply constraint effects on the rotor and restrict the transient vibration amplitude, while the inertia asymmetry has little influence on the transient response. When the rotor with huge unbalance operates at windmilling status, the rub-impact turns to be the main factor determining the rotor’s dynamic behavior, and several potential motion states, such as instable dry whip, intermittent rubbing and synchronous full annular rubbing would happen on certain conditions.





  • Integrated modeling and analysis of the multiple electromechanical couplings for the direct driven feed system in machine tools
    16 janvier 2018
    Publication date: June 2018
    Source:Mechanical Systems and Signal Processing, Volume 106

    Author(s): Xiaojun Yang, Dun Lu, Hui Liu, Wanhua Zhao

    The complicated electromechanical coupling phenomena due to different kinds of causes have significant influences on the dynamic precision of the direct driven feed system in machine tools. In this paper, a novel integrated modeling and analysis method of the multiple electromechanical couplings for the direct driven feed system in machine tools is presented. At first, four different kinds of electromechanical coupling phenomena in the direct driven feed system are analyzed systematically. Then a novel integrated modeling and analysis method of the electromechanical coupling which is influenced by multiple factors is put forward. In addition, the effects of multiple electromechanical couplings on the dynamic precision of the feed system and their main influencing factors are compared and discussed, respectively. Finally, the results of modeling and analysis are verified by the experiments. It finds out that multiple electromechanical coupling loops, which are overlapped and influenced by each other, are the main reasons of the displacement fluctuations in the direct driven feed system.





  • Decoupling control of vehicle chassis system based on neural network inverse system
    16 janvier 2018
    Publication date: June 2018
    Source:Mechanical Systems and Signal Processing, Volume 106

    Author(s): Chunyan Wang, Wanzhong Zhao, Zhongkai Luan, Qi Gao, Ke Deng

    Steering and suspension are two important subsystems affecting the handling stability and riding comfort of the chassis system. In order to avoid the interference and coupling of the control channels between active front steering (AFS) and active suspension subsystems (ASS), this paper presents a composite decoupling control method, which consists of a neural network inverse system and a robust controller. The neural network inverse system is composed of a static neural network with several integrators and state feedback of the original chassis system to approach the inverse system of the nonlinear systems. The existence of the inverse system for the chassis system is proved by the reversibility derivation of Interactor algorithm. The robust controller is based on the internal model control (IMC), which is designed to improve the robustness and anti-interference of the decoupled system by adding a pre-compensation controller to the pseudo linear system. The results of the simulation and vehicle test show that the proposed decoupling controller has excellent decoupling performance, which can transform the multivariable system into a number of single input and single output systems, and eliminate the mutual influence and interference. Furthermore, it has satisfactory tracking capability and robust performance, which can improve the comprehensive performance of the chassis system.





  • Assessment of energy harvesting and vibration mitigation of a pendulum dynamic absorber
    16 janvier 2018
    Publication date: June 2018
    Source:Mechanical Systems and Signal Processing, Volume 106

    Author(s): Krzysztof Kecik

    The paper presents a novel system for simultaneous energy harvesting and vibration mitigation. The system consists of two main parts: an autoparametric pendulum vibration absorber and an energy harvester device. The recovered energy is from oscillation of a levitating magnet in a coil. The energy harvesting system is mounted in a pendulum structure. The system allows energy recovery from a semi-trivial solution (pendulum in rest) or/and swinging of a pendulum. The influence of harvester parameters on the system response and energy harvesting in a parametric resonance is studied in detail. The harvester device does not decrease vibration reduction effectiveness.





  • State and force observers based on multibody models and the indirect Kalman filter
    16 janvier 2018
    Publication date: June 2018
    Source:Mechanical Systems and Signal Processing, Volume 106

    Author(s): Emilio Sanjurjo, Daniel Dopico, Alberto Luaces, Miguel Ángel Naya

    The aim of this work is to present two new methods to provide state observers by combining multibody simulations with indirect extended Kalman filters. One of the methods presented provides also input force estimation. The observers have been applied to two mechanism with four different sensor configurations, and compared to other multibody-based observers found in the literature to evaluate their behavior, namely, the unscented Kalman filter (UKF), and the indirect extended Kalman filter with simplified Jacobians (errorEKF). The new methods have some more computational cost than the errorEKF, but still much less than the UKF. Regarding their accuracy, both are better than the errorEKF. The method with input force estimation outperforms also the UKF, while the method without force estimation achieves results almost identical to those of the UKF. All the methods have been implemented as a reusable MATLAB® toolkit which has been released as Open Source in https://github.com/MBDS/mbde-matlab.





  • Modal resonant dynamics of cables with a flexible support: A modulated diffraction problem
    16 janvier 2018
    Publication date: June 2018
    Source:Mechanical Systems and Signal Processing, Volume 106

    Author(s): Tieding Guo, Houjun Kang, Lianhua Wang, Qijian Liu, Yueyu Zhao

    Modal resonant dynamics of cables with a flexible support is defined as a modulated (wave) diffraction problem, and investigated by asymptotic expansions of the cable-support coupled system. The support-cable mass ratio, which is usually very large, turns out to be the key parameter for characterizing cable-support dynamic interactions. By treating the mass ratio’s inverse as a small perturbation parameter and scaling the cable tension properly, both cable’s modal resonant dynamics and the flexible support dynamics are asymptotically reduced by using multiple scale expansions, leading finally to a reduced cable-support coupled model (i.e., on a slow time scale). After numerical validations of the reduced coupled model, cable-support coupled responses and the flexible support induced coupling effects on the cable, are both fully investigated, based upon the reduced model. More explicitly, the dynamic effects on the cable’s nonlinear frequency and force responses, caused by the support-cable mass ratio, the resonant detuning parameter and the support damping, are carefully evaluated.





  • Clutch pressure estimation for a power-split hybrid transmission using nonlinear robust observer
    16 janvier 2018
    Publication date: June 2018
    Source:Mechanical Systems and Signal Processing, Volume 106

    Author(s): Bin Zhou, Jianwu Zhang, Ji Gao, Haisheng Yu, Dong Liu

    For a power-split hybrid transmission, using the brake clutch to realize the transition from electric drive mode to hybrid drive mode is an available strategy. Since the pressure information of the brake clutch is essential for the mode transition control, this research designs a nonlinear robust reduced-order observer to estimate the brake clutch pressure. Model uncertainties or disturbances are considered as additional inputs, thus the observer is designed in order that the error dynamics is input-to-state stable. The nonlinear characteristics of the system are expressed as the lookup tables in the observer. Moreover, the gain matrix of the observer is solved by two optimization procedures under the constraints of the linear matrix inequalities. The proposed observer is validated by offline simulation and online test, the results have shown that the observer achieves significant performance during the mode transition, as the estimation error is within a reasonable range, more importantly, it is asymptotically stable.





  • Vibration energy harvesting based monitoring of an operational bridge undergoing forced vibration and train passage
    16 janvier 2018
    Publication date: June 2018
    Source:Mechanical Systems and Signal Processing, Volume 106

    Author(s): Paul Cahill, Budhaditya Hazra, Raid Karoumi, Alan Mathewson, Vikram Pakrashi

    The application of energy harvesting technology for monitoring civil infrastructure is a bourgeoning topic of interest. The ability of kinetic energy harvesters to scavenge ambient vibration energy can be useful for large civil infrastructure under operational conditions, particularly for bridge structures. The experimental integration of such harvesters with full scale structures and the subsequent use of the harvested energy directly for the purposes of structural health monitoring shows promise. This paper presents the first experimental deployment of piezoelectric vibration energy harvesting devices for monitoring a full-scale bridge undergoing forced dynamic vibrations under operational conditions using energy harvesting signatures against time. The calibration of the harvesters is presented, along with details of the host bridge structure and the dynamic assessment procedures. The measured responses of the harvesters from the tests are presented and the use the harvesters for the purposes of structural health monitoring (SHM) is investigated using empirical mode decomposition analysis, following a bespoke data cleaning approach. Finally, the use of sequential Karhunen Loeve transforms to detect train passages during the dynamic assessment is presented. This study is expected to further develop interest in energy-harvesting based monitoring of large infrastructure for both research and commercial purposes.








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  • Mode tracking using multiple data streams
    16 janvier 2018
    Publication date: September 2018
    Source:Information Fusion, Volume 43

    Author(s): Mohamed-Rafik Bouguelia, Alexander Karlsson, Sepideh Pashami, Sławomir Nowaczyk, Anders Holst

    Most existing work in information fusion focuses on combining information with well-defined meaning towards a concrete, pre-specified goal. In contradistinction, we instead aim for autonomous discovery of high-level knowledge from ubiquitous data streams. This paper introduces a method for recognition and tracking of hidden conceptual modes, which are essential to fully understand the operation of complex environments, and an important step towards building truly intelligent aware systems. We consider a scenario of analyzing usage of a fleet of city buses, where the objective is to automatically discover and track modes such as highway route, heavy traffic, or aggressive driver, based on available on-board signals. The method we propose is based on aggregating the data over time, since the high-level modes are only apparent in the longer perspective. We search through different features and subsets of the data, and identify those that lead to good clusterings, interpreting those clusters as initial, rough models of the prospective modes. We utilize Bayesian tracking in order to continuously improve the parameters of those models, based on the new data, while at the same time following how the modes evolve over time. Experiments with artificial data of varying degrees of complexity, as well as on real-world datasets, prove the effectiveness of the proposed method in accurately discovering the modes and in identifying which one best explains the current observations from multiple data streams.





  • A sensor fusion approach for drowsiness detection in wearable ultra-low-power systems
    16 janvier 2018
    Publication date: September 2018
    Source:Information Fusion, Volume 43

    Author(s): Victor Javier Kartsch, Simone Benatti, Pasquale Davide Schiavone, Davide Rossi, Luca Benini

    Drowsiness detection mechanisms have been extensively studied in the last years since they are one of the prevalent causes of accidents within the mining, driving and industrial activities. Many research efforts were done to quantify the drowsiness levels using behavioral analyses based on camera eye tracking systems as well as by analyzing physiological features contained in EEG signals. Detection systems typically use specific drowsiness indicators from only one of these methods, leaving a risk of missed detection since not all the population presents same symptoms of drowsiness. Thus, multi-feature systems are preferable even though most of the current State-of-the-Art (SoA) solutions are based on power-hungry platforms and they have meager chance to be used in embedded wearable applications with long battery lifetime. This work presents a drowsiness detection scheme fusing behavioral information coming from user motion through an IMU sensor and physiological information coming from brain activity through a single EEG electrode. The solution is implemented and tested on a low power programmable platform based on an ARM Cortex-M4 microcontroller, resulting in a wearable device capable to detect 5 different levels of drowsiness with an average accuracy of 95.2% and a battery life of 6 hours, using a 200 mAh battery. We also study the energy optimization achievable by accelerating the sensor fusion-based drowsiness detector on a parallel ultra-low power (PULP) platform. Results show that the use of PULP as efficient processing platform provides an energy improvement of 63x with respect to a solution based on a commercial microcontroller. This may extend the battery life of the complete system up to 46 h with a 7x improvement, paving the way for a completely wearable, always-on system.





  • Recent advances in neural dust: towards a neural interface platform
    16 janvier 2018
    Publication date: June 2018
    Source:Current Opinion in Neurobiology, Volume 50

    Author(s): Ryan M Neely, David K Piech, Samantha R Santacruz, Michel M Maharbiz, Jose M Carmena

    The neural dust platform uses ultrasonic power and communication to enable a scalable, wireless, and batteryless system for interfacing with the nervous system. Ultrasound offers several advantages over alternative wireless approaches, including a safe method for powering and communicating with sub mm-sized devices implanted deep in tissue. Early studies demonstrated that neural dust motes could wirelessly transmit high-fidelity electrophysiological data in vivo, and that theoretically, this system could be miniaturized well below the mm-scale. Future developments are focused on further minimization of the platform, better encapsulation methods as a path towards truly chronic neural interfaces, improved delivery mechanisms, stimulation capabilities, and finally refinements to enable deployment of neural dust in the central nervous system.





  • Tablet form factors and swipe gesture designs affect thumb biomechanics and performance during two-handed use
    16 janvier 2018
    Publication date: May 2018
    Source:Applied Ergonomics, Volume 69

    Author(s): Sarah M. Coppola, Michael Y.C. Lin, John Schilkowsky, Pedro M. Arezes, Jack T. Dennerlein

    Tablet computers’ hardware and software designs may affect upper extremity muscle activity and postures. This study investigated the hypothesis that forearm muscle activity as well as wrist and thumb postures differ during simple gestures across different tablet form factors and touchscreen locations. Sixteen adult (8 female, 8 male) participants completed 320 tablet gestures across four swipe locations, with various tablet sizes (8″ and 10”), tablet orientations (portrait and landscape), swipe orientations (vertical and horizontal), and swipe directions (medial and radial). Three-dimensional motion analysis and surface electromyography measured wrist and thumb postures and forearm muscle activity, respectively. Postures and muscle activity varied significantly across the four swipe locations (p < .0001). Overall, swipe location closest to the palm allowed users to swipe with a more neutral thumb and wrist posture and required less forearm muscle activity. Greater thumb extension and abduction along with greater wrist extension and ulnar deviation was required to reach the target as the target moved farther from the palm. Extensor Carpi Radialis, Extensor Carpi Ulnaris, Flexor Carpi Ulnaris, Extensor Policis Brevis, and Abductor Pollicis Longus muscle activity also increased significantly with greater thumb reach (p < 001). Larger tablet size induced greater Extensor Carpi Radialis, Extensor Carpi Ulnaris, Flexor Carpi Ulnaris, Flexor Carpi Radialis, and Abductor Pollicis Longus muscle activity (p < .0001). The study results demonstrate the importance of swipe locations and suggest that the tablet interface design can be improved to induce more neutral thumb and wrist posture along with lower forearm muscle load.





  • Dynamic classifier selection: Recent advances and perspectives
    16 janvier 2018
    Publication date: May 2018
    Source:Information Fusion, Volume 41

    Author(s): Rafael M.O. Cruz, Robert Sabourin, George D.C. Cavalcanti

    Multiple Classifier Systems (MCS) have been widely studied as an alternative for increasing accuracy in pattern recognition. One of the most promising MCS approaches is Dynamic Selection (DS), in which the base classifiers are selected on the fly, according to each new sample to be classified. This paper provides a review of the DS techniques proposed in the literature from a theoretical and empirical point of view. We propose an updated taxonomy based on the main characteristics found in a dynamic selection system: (1) The methodology used to define a local region for the estimation of the local competence of the base classifiers; (2) The source of information used to estimate the level of competence of the base classifiers, such as local accuracy, oracle, ranking and probabilistic models, and (3) The selection approach, which determines whether a single or an ensemble of classifiers is selected. We categorize the main dynamic selection techniques in the DS literature based on the proposed taxonomy. We also conduct an extensive experimental analysis, considering a total of 18 state-of-the-art dynamic selection techniques, as well as static ensemble combination and single classification models. To date, this is the first analysis comparing all the key DS techniques under the same experimental protocol. Furthermore, we also present several perspectives and open research questions that can be used as a guide for future works in this domain.





  • Robust EMG pattern recognition in the presence of confounding factors: features, classifiers and adaptive learning
    16 janvier 2018
    Publication date: 15 April 2018
    Source:Expert Systems with Applications, Volume 96

    Author(s): Yikun Gu, Dapeng Yang, Qi Huang, Wei Yang, Hong Liu

    Traditional electromyogram (EMG) pattern recognition does not take into account the effect of confounding factors, preventing its effective clinical application. In this paper, we investigated EMG pattern recognition of compound confounding factors including electrode shift, force variation, limb posture and temporary drift. We started with feature extraction, to identify suitable representations to resolve classification degradation caused by electrode doffing. Then, we proceeded to examine a variety of classifiers, to achieve a favorable classification accuracy (CA) when switching the control arms (dominant and nondominant) without additional calibration. Lastly, we investigated adaptive learning strategies, to mitigate the decline in CA over a relatively long duration (one day) of use. Two data-collection protocols (electrode doffing and donning, and one-day-long collection) were applied, and EMG datasets collected in these two protocols were arranged into three scenarios for progressive validation of the features, classifiers, and adaptive learning methods. Our results showed that the features extracted from the frequency domain improved the CA by 30% in comparison with their original time-domain representations (14 motions, 67.5 ± 9.8%, p < .001). When alternating the control arms, the performance achieved by the classifiers all declined and no method appeared to be more reliable than the others (14 motions, the best 45.5 ± 8.4%, probabilistic neural network; 7 motions, the best 70.4 ± 10.6%, linear discriminant analysis). At last, the new adaptive learning method utilizing representative samples could effectively mitigate classification degradation by updating the classifier's training samples in real-time.





  • Psychological stress level detection based on electrodermal activity
    16 janvier 2018
    Publication date: 2 April 2018
    Source:Behavioural Brain Research, Volume 341

    Author(s): Yun Liu, Siqing Du

    This paper presents a method for detecting psychological stress levels. It aims to explore the feasibility of using a single physiological signal to create a more practical alternative for detecting stress in people than current multiple physiological signals approaches involve. In particular, the approach explored uses linear discriminant analysis (LDA) based on the electrodermal activity (EDA) signal which aims at discriminating between three stress levels: low, medium and high. We used the MIT Media lab 'stress database' from which we selected eleven ‘foot’ based EDA data sets for our experiments. Using this eighteen EDA features were extracted from (sixty-six) five-minutes data segments equating to three driving conditions: at rest, on the open road (highway) and city driving. After that, Fisher projection and Linear discriminant analysis (LDA) were used to classify the stress levels with feature vectors, that included both leaving one out and test cross-validation strategy. The results showed that these methods achieved recognition rate of 81.82% which we argue, while less that multiple signal systems, may be a better balance between recognition performance and computational load, that could be a promising line of research for the development of practical personal stress monitors.





  • Enhanced wakefulness following lesions of a mesopontine locus essential for the induction of general anesthesia
    16 janvier 2018
    Publication date: 2 April 2018
    Source:Behavioural Brain Research, Volume 341

    Author(s): Sa’ar Lanir-Azaria, Guy Meiri, Tamir Avigdor, Anne Minert, Marshall Devor

    The induction of general anesthesia shares many features with the transition from wakefulness to non-rapid eye movement (NREM) sleep, suggesting that the two types of brain-state transition are orchestrated by a common neuronal mechanism. Previous studies revealed a brainstem locus, the mesopontine tegmental anesthesia area (MPTA), that is of singular importance for anesthetic induction. Microinjection of GABAergic anesthetics there induces rapid loss-of-consciousness and lesions render the animal relatively insensitive to anesthetics administered systemically. Here we show that MPTA lesions also alter the natural sleep-wake rhythm by increasing overall wake time at the expense of time asleep (NREM and REM sleep equally), with nearly all of the change occurring during the dark hours of the light-dark cycle. The effect was proportional to the extent of the lesion and was not seen after lesions just outside of the MPTA, or following sham lesions. Thus, MPTA neurons appear to play a role in natural bistable brain-state switching (sleep-wake) as well as in loss and recovery of consciousness induced pharmacologically.





  • Extended Fitts’ model of pointing time in eye-gaze input system - Incorporating effects of target shape and movement direction into modeling
    16 janvier 2018
    Publication date: April 2018
    Source:Applied Ergonomics, Volume 68

    Author(s): Atsuo Murata, Daichi Fukunaga

    This study attempted to investigate the effects of the target shape and the movement direction on the pointing time using an eye-gaze input system and extend Fitts' model so that these factors are incorporated into the model and the predictive power of Fitts' model is enhanced. The target shape, the target size, the movement distance, and the direction of target presentation were set as within-subject experimental variables. The target shape included: a circle, and rectangles with an aspect ratio of 1:1, 1:2, 1:3, and 1:4. The movement direction included eight directions: upper, lower, left, right, upper left, upper right, lower left, and lower right. On the basis of the data for identifying the effects of the target shape and the movement direction on the pointing time, an attempt was made to develop a generalized and extended Fitts’ model that took into account the movement direction and the target shape. As a result, the generalized and extended model was found to fit better to the experimental data, and be more effective for predicting the pointing time for a variety of human-computer interaction (HCI) task using an eye-gaze input system.





  • The effect of a multi-axis suspension on whole body vibration exposures and physical stress in the neck and low back in agricultural tractor applications
    16 janvier 2018
    Publication date: April 2018
    Source:Applied Ergonomics, Volume 68

    Author(s): Jeong Ho Kim, Jack T. Dennerlein, Peter W. Johnson

    Whole body vibration (WBV) exposures are often predominant in the fore-aft (x) or lateral (y) axis among off-road agricultural vehicles. However, as the current industry standard seats are designed to reduce mainly vertical (z) axis WBV exposures, they may be less effective in reducing drivers' exposure to multi-axial WBV. Therefore, this laboratory-based study aimed to determine the differences between a single-axial (vertical) and multi-axial (vertical + lateral) suspension seat in reducing WBV exposures, head acceleration, self-reported discomfort, and muscle activity (electromyography) of the major muscle of the low back, neck and shoulders. The results showed that the multi-axial suspension seat had significantly lower WBV exposures compared to the single-axial suspension seats (p' < 0.04). Similarly, the multi-axial suspension seat had lower head acceleration and muscle activity of the neck, shoulder, and low back compared to the single-axial suspension seat; some but not all of the differences were statistically significant. These results indicate that the multi-axial suspension seat may reduce the lateral WBV exposures and associated muscular loading in the neck and low back in agricultural vehicle operators.





  • Biomechanical evaluation of exoskeleton use on loading of the lumbar spine
    16 janvier 2018
    Publication date: April 2018
    Source:Applied Ergonomics, Volume 68

    Author(s): Eric B. Weston, Mina Alizadeh, Gregory G. Knapik, Xueke Wang, William S. Marras

    The objective of this study was to investigate biomechanical loading to the low back as a result of wearing an exoskeletal intervention designed to assist in occupational work. Twelve subjects simulated the use of two powered hand tools with and without the use of a Steadicam vest with an articulation tool support arm in a laboratory environment. Dependent measures of peak and mean muscle forces in ten trunk muscles and peak and mean spinal loads were examined utilizing a dynamic electromyography-assisted spine model. The exoskeletal device increased both peak and mean muscle forces in the torso extensor muscles (p < 0.001). Peak and mean compressive spinal loads were also increased up to 52.5% and 56.8%, respectively, for the exoskeleton condition relative to the control condition (p < 0.001). The results of this study highlight the need to design exoskeletal interventions while anticipating how mechanical loads might be shifted or transferred with their use.





  • Assessment of an active industrial exoskeleton to aid dynamic lifting and lowering manual handling tasks
    16 janvier 2018
    Publication date: April 2018
    Source:Applied Ergonomics, Volume 68

    Author(s): Kirsten Huysamen, Michiel de Looze, Tim Bosch, Jesus Ortiz, Stefano Toxiri, Leonard W. O'Sullivan

    The aim of this study was to evaluate the effect of an industrial exoskeleton on muscle activity, perceived musculoskeletal effort, measured and perceived contact pressure at the trunk, thighs and shoulders, and subjective usability for simple sagittal plane lifting and lowering conditions. Twelve male participants lifted and lowered a box of 7.5 kg and 15 kg, respectively, from mid-shin height to waist height, five times, both with and without the exoskeleton. The device significantly reduced muscle activity of the Erector Spinae (12%-15%) and Biceps Femoris (5%). Ratings of perceived musculoskeletal effort in the trunk region were significantly less with the device (9.5%-11.4%). The measured contact pressure was highest on the trunk (91.7 kPa-93.8 kPa) and least on shoulders (47.6 kPa-51.7 kPa), whereas pressure was perceived highest on the thighs (35-44% of Max LPP). Six of the users rated the device usability as acceptable. The exoskeleton reduced musculoskeletal loading on the lower back and assisted with hip extensor torque during lifting and lowering. Contact pressures fell below the Pain Pressure Threshold. Perceived pressure was not exceptionally high, but sufficiently high to cause discomfort if used for long durations.





  • Predictors of disability and absenteeism in workers with non-specific low back pain: A longitudinal 15-month study
    16 janvier 2018
    Publication date: April 2018
    Source:Applied Ergonomics, Volume 68

    Author(s): Arnaud Lardon, Jean-Daniel Dubois, Vincent Cantin, Mathieu Piché, Martin Descarreaux

    Objectives The objective of this study was to identify baseline predictors of disability and absenteeism in workers with a history of non-specific low back pain (LBP). Methods One hundred workers with a history of non-specific LBP participated in three evaluations (baseline, 7 and 15 months follow-up). Current and past history of LBP, clinical pain intensity, disability, absenteeism, fear-avoidance beliefs, pain catastrophizing, pain hypervigilance, work satisfaction and patient stratification based on “risk of poor clinical outcome assessment” (RPCO) were evaluated using questionnaires and interviews. In addition, cutaneous heat pain thresholds, cutaneous heat pain tolerance thresholds, conditioned pain modulation (CPM), trunk kinematics and muscle activity were measured during each evaluation. Logistic regression models were used to determine predictors of LBP disability and absenteeism at 15-months. Results Sixty-eight workers returned for the 15-month follow-up and among this sample, 49% reported disability and 16% reported absenteeism at follow-up. Baseline clinical pain intensity predicted disability (OR = 1.08, 95%CI: 1.03–1.13) at 15-month while work satisfaction (OR = 0.93, 95%CI: 0.87–0.99) and RPCO (OR = 1.51, 95%CI: 1.05–2.16) predicted absenteeism. These results remained significant after adjustments for age, gender as well as type of work and intervention. Conclusion This study highlights the importance of clinical pain and psychological factors in the prediction and potentially the prevention of future disability. Screening tools assessing these risk factors can be useful to evaluate workers with past history of low back pain.





  • Evaluation of physical workload affected by mass and center of mass of head-mounted display
    16 janvier 2018
    Publication date: April 2018
    Source:Applied Ergonomics, Volume 68

    Author(s): Takanori Chihara, Akihiko Seo

    A head-mounted display (HMD) with inappropriate mass and center of mass (COM) increases the physical workload of HMD users. The aim of this study was to investigate the effects of mass and COM of HMD on physical workload. Twelve subjects participated in this study. The mass and posteroanterior COM position were 0.8, 1.2, or 1.6 kg and −7.0, 0.0, or 7.0 cm, respectively. The subjects gazed at the target objects in four test postures: the neutral, look-up, body-bending, and look-down postures. The normalized joint torques for the neck and the lumbar region were calculated based on the measured segment angles. The results showed that the neck joint torque was significantly affected by mass and COM and it increased as the HMD mass increased for all test postures. The COM position that minimized the neck joint torque varied depending on the test postures, and the recommended ranges of COM were identified.





  • Design-validation of a hand exoskeleton using musculoskeletal modeling
    16 janvier 2018
    Publication date: April 2018
    Source:Applied Ergonomics, Volume 68

    Author(s): Clint Hansen, Florian Gosselin, Khalil Ben Mansour, Pierre Devos, Frederic Marin

    Exoskeletons are progressively reaching homes and workplaces, allowing interaction with virtual environments, remote control of robots, or assisting human operators in carrying heavy loads. Their design is however still a challenge as these robots, being mechanically linked to the operators who wear them, have to meet ergonomic constraints besides usual robotic requirements in terms of workspace, speed, or efforts. They have in particular to fit the anthropometry and mobility of their users. This traditionally results in numerous prototypes which are progressively fitted to each individual person. In this paper, we propose instead to validate the design of a hand exoskeleton in a fully digital environment, without the need for a physical prototype. The purpose of this study is thus to examine whether finger kinematics are altered when using a given hand exoskeleton. Therefore, user specific musculoskeletal models were created and driven by a motion capture system to evaluate the fingers' joint kinematics when performing two industrial related tasks. The kinematic chain of the exoskeleton was added to the musculoskeletal models and its compliance with the hand movements was evaluated. Our results show that the proposed exoskeleton design does not influence fingers’ joints angles, the coefficient of determination between the model with and without exoskeleton being consistently high ( R 2 ¯ =0.93) and the nRMSE consistently low ( n R M S E ¯ = 5.42°). These results are promising and this approach combining musculoskeletal and robotic modeling driven by motion capture data could be a key factor in the ergonomics validation of the design of orthotic devices and exoskeletons prior to manufacturing.





  • Exploring the effect of using different levels of emotional design features in multimedia science learning
    16 janvier 2018
    Publication date: April 2018
    Source:Computers & Education, Volume 119

    Author(s): Ahmet Murat Uzun, Zahide Yıldırım

    The current study aims to examine the influence of incorporating different emotional design approaches into multimedia on 7th grade middle school students’ positive emotions, mental effort investments and learning achievements (recall and transfer). To this end, four different instructional materials were created. Each material was identical, with only the extent of emotional design differing. For the Neutral Design (ND) group, none of the emotional design principles were used (monochromatic grayscale). For the Colorful Design (CD) group, attention-grabbing, bright and saturated colors were added to the material. For the Anthropomorphic Design (AD) group, expressive facial expressions (anthropomorphism of lifeless objects and expressive facial expressions of human characters) were incorporated into the material. Finally, for the Anthropomorphic Design and Sound Effects (ADSE) group, interesting sound effects were also used. The study was conducted at a middle school with a group of 106 students. Positive emotions were measured using an emWave emotion detection device. Results revealed that positive emotions generally increased as the amount of emotional design features increased. However, while students who used the Colorful Design invested more mental effort compared to students who used the Neutral Design, students who used the Anthropomorphic Design and Sound Effects (ADSE) invested less mental effort compared to students who used the Colorful Design. In addition, students who used the Colorful Design outperformed students who used the Neutral Design in terms of their recall scores. No significant difference in terms of transfer of learning scores was observed across the groups. Results were discussed with respect to different views in the literature regarding the use of emotional design in multimedia.





  • The involvement of the pathway connecting the substantia nigra, the periaqueductal gray matter and the retrotrapezoid nucleus in breathing control in a rat model of Parkinson's disease
    16 janvier 2018
    Publication date: April 2018
    Source:Experimental Neurology, Volume 302

    Author(s): Juliana C. Lima, Luiz M. Oliveira, Marina T. Botelho, Thiago S. Moreira, Ana C. Takakura

    Parkinson's disease (PD) is characterized by a reduction in the number of dopaminergic neurons of the substantia nigra (SNpc), accompanied by motor and non-motor deficiencies such as respiratory failure. Here, our aim was to investigate possible neuronal communications between the SNpc and chemoreceptor neurons within the retrotrapezoid nucleus (RTN), in order to explain neurodegeneration and the loss of breathing function in the 6-OHDA PD animal model. Male Wistar rats received tracer injections in the SNpc, RTN and periaqueductal gray (PAG) regions to investigate the projections between those regions. The results showed that neurons of the SNpc project to the RTN by an indirect pathway that goes through the PAG region. In different groups of rats, reductions in the density of neuronal markers (NeuN) and the number of catecholaminergic varicosities in PAG, as well as reductions in the number of CO2-activated PAG neurons with RTN projections, were observed in a 6-OHDA model of PD. Physiological experiments showed that inhibition of the PAG by bilateral injection of muscimol did not produce resting breathing disturbances but instead reduced genioglossus (GGEMG) and abdominal (AbdEMG) muscle activity amplitude induced by hypercapnia in control rats that were urethane-anesthetized, vagotomized, and artificially ventilated. However, in a model of PD, we found reductions in resting diaphragm muscle activity (DiaEMG) and GGEMG frequencies, as well as in hypercapnia-induced DiaEMG, GGEMG and AbdEMG frequencies and GGEMG and AbdEMG amplitudes. Therefore, we can conclude that there is an indirect pathway between neurons of the SNpc and RTN that goes through the PAG and that there is a defect of this pathway in an animal model of PD.





  • A multi-class EEG-based BCI classification using multivariate empirical mode decomposition based filtering and Riemannian geometry
    16 janvier 2018
    Publication date: 1 April 2018
    Source:Expert Systems with Applications, Volume 95

    Author(s): Pramod Gaur, Ram Bilas Pachori, Hui Wang, Girijesh Prasad

    A brain-computer interface (BCI) facilitates a medium to translate the human motion intentions using electrical brain activity signals such as electroencephalogram (EEG) into control signals. EEG signals are non-stationary and subject specific. A major challenge in BCI research is to classify human motion intentions from non-stationary EEG signals. We propose a novel subject specific multivariate empirical mode decomposition (MEMD) based filtering method, namely, SS-MEMDBF to classify the motor imagery (MI) based EEG signals into multiple classes. The MEMD method simultaneously decomposes the multichannel EEG signals into a group of multivariate intrinsic mode functions (MIMFs). This decomposition enables us to extract the cross-channel information and also localize the specific frequency information. The MIMFs are considered as narrow-band, amplitude and frequency modulated (AFM) signals. The statistical measure, mean frequency has been used to automatically filter the MIMFs to obtain enhanced EEG signals which better represent motor imagery related brainwave modulations over μ and β rhythms. The sample covariance matrix has been computed and used as a feature set. The feature set has been classified into multiple MI tasks using Riemannian geometry. The proposed method has helped achieve mean Kappa value of 0.60 across nine subjects of the BCI competition IV dataset 2A which is superior to all the reported methods.





  • Delivering home healthcare through a Cloud-based Smart Home Environment (CoSHE)
    16 janvier 2018
    Publication date: April 2018
    Source:Future Generation Computer Systems, Volume 81

    Author(s): Minh Pham, Yehenew Mengistu, Ha Do, Weihua Sheng

    The dramatic increase of senior population worldwide is challenging the existing healthcare and support systems. Recently, smart home environments are utilized for ubiquitous health monitoring, allowing patients to stay at the comfort of their homes. In this paper we presented a Cloud-Based Smart Home Environment (CoSHE) for home healthcare. CoSHE collects physiological, motion and audio signals through non-invasive wearable sensors and provides contextual information in terms of the resident’s daily activity and location in the home. This enables healthcare professionals to study daily activities, behavioral changes and monitor rehabilitation and recovery processes. A smart home environment is set up with environmental sensors to provide contextual information. The sensor data are processed in a smart home gateway and sent to a private cloud, which provides real time data access for remote caregivers. Our case study shows that we can successfully integrate contextual information to health data and this comprehensive information can help better understand caretaker’s health status.





  • The effect of bismuth on the structure, magnetic and electric properties of Co2MnO4 spinel multiferroic
    16 janvier 2018
    Publication date: 1 April 2018
    Source:Journal of Magnetism and Magnetic Materials, Volume 451

    Author(s): H. Chouaya, M. Smari, I. Walha, E. Dhahri, M.P.F. Graça, M.A. Valente

    Mixed Co2Mn1−xBixO4 (x = 0, x = 0.05 and x = 0.1) samples were prepared by the sol–gel method using the citric acid route and characterized by various techniques. The X-ray diffraction (XRD) and Raman spectroscopic analyses confirmed the formation of inverse spinel cubic structure with Fd 3 m space group. The introduction of Bismuth (Bi) into Co2MnO4 did not modify the ferrimagnetic character of the parent compound Co2MnO4, whereas the field-cooled magnetizations MFC and the Curie temperature Tc decreased when increasing the Bi content. The electrical properties showed an activation energy (Ea) increase caused by the decrease of the double-exchange interaction following the substitution of Mn3+ by Bi3+. Eventually, the temperature coefficient of resistance (TCR) shows significant values for all samples can be investigated also as good candidates for bolometer applications.





  • Association between lumbopelvic pain and pelvic floor dysfunction in women: A cross sectional study
    16 janvier 2018
    Publication date: April 2018
    Source:Musculoskeletal Science and Practice, Volume 34

    Author(s): Sinéad Dufour, Brittany Vandyken, Marie-Jose Forget, Carolyn Vandyken

    Background The prevalence, cost and disability associated with lumbopelvic pain continues to rise despite the range of available therapeutic interventions, indicating a deficiency in current approaches. A literature base highlighting a correlation between lumbopelvic pain and pelvic floor function is developing; however, the features that characterize this correlation have yet to be fully established. Purpose The purpose of this study was to determine the prevalence and characteristics of pelvic floor muscle function among women with lumbopelvic pain. Methods A cross−sectional study was conducted on non-pregnant women presenting with lumbopelvic pain to one of seven outpatient orthopaedic clinics in Canada. Potential participants underwent a screening process to assess for pelvic floor muscle dysfunction. Results A total of 182 women were recruited and 97 were excluded, leaving 85 participants (n = 85). Of these, 95.3% were determined to have some form of pelvic floor dysfunction. Specifically, 71% of the participants had pelvic floor muscle tenderness, 66% had pelvic floor weakness and 41% were found to have a pelvic organ prolapse. Participants with combined low back pain and pelvic girdle pain presented with higher levels of disability and increased characteristics of pelvic floor dysfunction. Conclusions Our findings corroborate and extend recent research supporting the hypothesis that a high proportion of pelvic floor muscle dysfunction is present among women with lumbopelvic pain. Specifically, increased pelvic floor muscle pressure-pain sensitivity represented the most frequent characteristic, the clinical implications of which require further study.





  • Normal values of abdominal muscles thickness in healthy children using ultrasonography
    16 janvier 2018
    Publication date: April 2018
    Source:Musculoskeletal Science and Practice, Volume 34

    Author(s): Nahid Rahmani, Mohammad Ali Mohseni-Bandpei, Mahyar Salavati, Roshanak Vameghi, Iraj Abdollahi

    Abdominal muscles are one of the important elements to support the lumbar spine. Evaluation of muscle thickness using ultrasonography (US) is considered to be a source of information from muscles characteristics. The purpose of this study was to demonstrate normal reference data of abdominal muscles thickness and subcutaneous fat in adolescents using US. A random sample of 160 healthy adolescents (80 boys and 80 girls) at the age range of 15–18 years was recruited. Three abdominal muscles including Transversus Abdominis (TA), Internal Oblique (IO), External Oblique (EO) and subcutaneous fat (SF) were bilaterally measured using US. The range of normal values for TA muscle thickness was between 2.31 and 2.57 mm, for IO muscle thickness was between 4.02 and 5.15 mm and for EO muscle thickness was between 2.81 and 3.17 mm. The normal patterns of abdominal muscles were found as IO > EO > TA at both sides. Boys were taller, heavier with greater body mass index (BMI) and had larger abdominal muscles thickness than girls. A weak negative correlation was found between age and muscles size [r = (−0.06) – (−0.23), p < .05], but a significant positive correlation was found between BMI and muscle size (r = 0.21–0.68, p < .05). It seems that abdominal muscles thickness in adolescents followed the same pattern of muscle size in adults. BMI appeared to be the best predictor of muscle thickness. However, further studies are recommended to support the findings of the present study.





  • High-density EEG characterization of brain responses to auditory rhythmic stimuli during wakefulness and NREM sleep
    16 janvier 2018
    Publication date: 1 April 2018
    Source:NeuroImage, Volume 169

    Author(s): Caroline Lustenberger, Yogi A. Patel, Sankaraleengam Alagapan, Jessica M. Page, Betsy Price, Michael R. Boyle, Flavio Fröhlich

    Auditory rhythmic sensory stimulation modulates brain oscillations by increasing phase-locking to the temporal structure of the stimuli and by increasing the power of specific frequency bands, resulting in Auditory Steady State Responses (ASSR). The ASSR is altered in different diseases of the central nervous system such as schizophrenia. However, in order to use the ASSR as biological markers for disease states, it needs to be understood how different vigilance states and underlying brain activity affect the ASSR. Here, we compared the effects of auditory rhythmic stimuli on EEG brain activity during wake and NREM sleep, investigated the influence of the presence of dominant sleep rhythms on the ASSR, and delineated the topographical distribution of these modulations. Participants (14 healthy males, 20-33 years) completed on the same day a 60 min nap session and two 30 min wakefulness sessions (before and after the nap). During these sessions, amplitude modulated (AM) white noise auditory stimuli at different frequencies were applied. High-density EEG was continuously recorded and time-frequency analyses were performed to assess ASSR during wakefulness and NREM periods. Our analysis revealed that depending on the electrode location, stimulation frequency applied and window/frequencies analysed the ASSR was significantly modulated by sleep pressure (before and after sleep), vigilance state (wake vs. NREM sleep), and the presence of slow wave activity and sleep spindles. Furthermore, AM stimuli increased spindle activity during NREM sleep but not during wakefulness. Thus, (1) electrode location, sleep history, vigilance state and ongoing brain activity needs to be carefully considered when investigating ASSR and (2) auditory rhythmic stimuli during sleep might represent a powerful tool to boost sleep spindles.





  • Intracranial high-γ connectivity distinguishes wakefulness from sleep
    16 janvier 2018
    Publication date: 1 April 2018
    Source:NeuroImage, Volume 169

    Author(s): Ezequiel Mikulan, Eugenia Hesse, Lucas Sedeño, Tristán Bekinschtein, Mariano Sigman, María del Carmen García, Walter Silva, Carlos Ciraolo, Adolfo M. García, Agustín Ibáñez

    Neural synchrony in the γ-band is considered a fundamental process in cortical computation and communication and it has also been proposed as a crucial correlate of consciousness. However, the latter claim remains inconclusive, mainly due to methodological limitations, such as the spectral constraints of scalp-level electroencephalographic recordings or volume-conduction confounds. Here, we circumvented these caveats by comparing γ-band connectivity between two global states of consciousness via intracranial electroencephalography (iEEG), which provides the most reliable measurements of high-frequency activity in the human brain. Non-REM Sleep recordings were compared to passive-wakefulness recordings of the same duration in three subjects with surgically implanted electrodes. Signals were analyzed through the weighted Phase Lag Index connectivity measure and relevant graph theory metrics. We found that connectivity in the high-γ range (90–120 Hz), as well as relevant graph theory properties, were higher during wakefulness than during sleep and discriminated between conditions better than any other canonical frequency band. Our results constitute the first report of iEEG differences between wakefulness and sleep in the high-γ range at both local and distant sites, highlighting the utility of this technique in the search for the neural correlates of global states of consciousness.





  • Measurement of mass stopping power of chitosan polymer loaded with TiO2 for relativistic electron interaction
    16 janvier 2018
    Publication date: April 2018
    Source:Radiation Physics and Chemistry, Volume 145

    Author(s): S. Ramesh Babu, N.M. Badiger, M.Y. Karidurgannavar, Jolly.G. Varghese

    The Mass Stopping Power (MSP) of relativistic electrons in chitosan loaded with TiO2 of different proportions has been measured by recording the spectrum of internal conversion electrons. The internal conversion electrons of energies 614keV from Cs137, 942keV and 1016keV from Bi207 source are allowed to pass through chitosan-TiO2 alloy and transmitted electrons are detected with a Si (Li) detector coupled to an 8K multichannel analyzer. By knowing the energies of incident electrons and transmitted electrons, the energy loss and the MSP are determined. Thus measured MSP values of the alloys are compared with the values calculated using Braggs additivity rule. The disagreement between theory and experiment is found to increases with increasing TiO2 concentration in chitosan, indicating the influence of chemical environment in the properties of such polymeric membrane.





  • Longitudinal training dams mitigate effects of shipping on environmental conditions and fish density in the littoral zones of the river Rhine
    16 janvier 2018
    Publication date: 1 April 2018
    Source:Science of The Total Environment, Volumes 619–620

    Author(s): F.P.L. Collas, A.D. Buijse, L. van den Heuvel, N. van Kessel, M.M. Schoor, H. Eerden, R.S.E.W. Leuven

    The stability of habitat conditions in littoral zones of navigated rivers is strongly affected by shipping induced waves and water displacements. In particular, the increase of variability in flow conditions diminishes the suitability of these habitats for juvenile fishes. Recently, a novel ecosystem based river management strategy has resulted in the replacement of traditional river training structures (i.e., groynes) by longitudinal training dams (LTDs), and the creation of shore channels in the river Waal, the main, free-flowing and intensively navigated distributary of the river Rhine in the Netherlands. It was hypothesized that these innovative LTDs mitigated the effects of shipping on fishes by maintaining the natural variability of habitat conditions in the littoral zones during ship passages whereby shore channels served as refugia for juvenile fishes. Measurements of abiotic conditions showed a significantly lower water level fluctuation and significantly higher flow stability in shore channels compared to groyne fields. Flow velocity did not differ, nor did the variation in flow velocity fluctuation during ship passage between these habitats. Densities of fish were found to be significantly higher in the littoral zones of shore channels compared to nearby groyne fields. Moreover, electrofishing along the inner side of the newly constructed LTD showed a significant linear relationship between fish density and distance from highly dynamic in- and outflow sections and to lowered inflow sections in the LTD. Results of our field sampling clearly indicate successful ecological rehabilitation of littoral zones that coincides with a facilitation of navigation in the main river channel and increased flood safety.

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  • Reduced P3b brain response during sustained visual attention is associated with remote blast mTBI and current PTSD in U.S. military veterans
    16 janvier 2018
    Publication date: 15 March 2018
    Source:Behavioural Brain Research, Volume 340

    Author(s): Casey S. Gilmore, Craig A. Marquardt, Seung Suk Kang, Scott R. Sponheim

    Approximately 275,000 American service members deployed to Iraq or Afghanistan have sustained a mild traumatic brain injury (mTBI), with 75% of these incidents involving an explosive blast. Combat-related mTBI is frequently associated with comorbid mental health disorders, especially posttraumatic stress disorder (PTSD). Attention problems, including sustained attention, are common cognitive complaints of veterans with TBI and PTSD. The present study sought to examine neural correlates of sustained attention in veterans with blast mTBI and/or current PTSD. In 124 veterans of Operations Enduring and Iraqi Freedom (OEF/OIF), we examined event-related potentials (ERPs) elicited by targets and non-targets during performance of a degraded-stimulus continuous performance task (DS-CPT). Four groups, consisting of veterans with blast-related mTBI only, current PTSD only, both blast mTBI and PTSD, and a control group, were studied. Compared to all other groups, blast mTBI only participants were more likely to respond regardless of stimulus type during the DS-CPT. During target detection, the three mTBI/PTSD groups showed reduced amplitude of the P3b (i.e., P300) ERP at Pz compared to the control group. P3b of the three affected groups did not differ from each other. These results suggest that parietal P3b amplitude reduction during target detection in the DS-CPT task may be an index of brain pathology after combat trauma, yet the diminished brain response fails to differentiate independent effects of blast-related mTBI or severity of PTSD symptomatology.





  • Discordant manifestations in Italian brothers with GNE myopathy
    16 janvier 2018
    Publication date: 15 March 2018
    Source:Journal of the Neurological Sciences, Volume 386

    Author(s): Maria-Teresa Dotti, Alessandro Malandrini, Xavière Lornage, Andrea Mignarri, Teresa Anna Cantisani, Johann Bohm, Jocelyn Laporte, Edoardo Malfatti







  • New Cav2 calcium channel gating modifiers with agonist activity and therapeutic potential to treat neuromuscular disease
    16 janvier 2018
    Publication date: 15 March 2018
    Source:Neuropharmacology, Volume 131

    Author(s): Man Wu, Hayley V. White, Blake A. Boehm, Christopher J. Meriney, Kaylan Kerrigan, Michael Frasso, Mary Liang, Erika M. Gotway, Madeleine R. Wilcox, Jon W. Johnson, Peter Wipf, Stephen D. Meriney

    Voltage-gated calcium channels (VGCCs) are critical regulators of many cellular functions, including the activity-dependent release of chemical neurotransmitter from nerve terminals. At nerve terminals, the Cav2 family of VGCCs are closely positioned with neurotransmitter-containing synaptic vesicles. The relationship between calcium ions and transmitter release is such that even subtle changes in calcium flux through VGCCs have a strong influence on the magnitude of transmitter released. Therefore, modulators of the calcium influx at nerve terminals have the potential to strongly affect transmitter release at synapses. We have previously developed novel Cav2-selective VGCC gating modifiers (notably GV-58) that slow the deactivation of VGCC current, increasing total calcium ion flux. Here, we describe ten new gating modifiers based on the GV-58 structure that extend our understanding of the structure-activity relationship for this class of molecules and extend the range of modulation of channel activities. In particular, we show that one of these new compounds (MF-06) was more efficacious than GV-58, another (KK-75) acts more quickly on VGCCs than GV-58, and a third (KK-20) has a mix of increased speed and efficacy. A subset of these new VGCC agonist gating modifiers can increase transmitter release during action potentials at neuromuscular synapses, and as such, show potential as therapeutics for diseases with a presynaptic deficit that results in neuromuscular weakness. Further, several of these new compounds can be useful tool compounds for the study of VGCC gating and function.

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  • “High risk non-initiating insider” identification based on EEG analysis for enhancing nuclear security
    16 janvier 2018
    Publication date: March 2018
    Source:Annals of Nuclear Energy, Volume 113

    Author(s): Young A. Suh, Man-Sung Yim

    The objective of this research is to describe the possibility of identifying a non-initiating insider (insider who has not yet committed an action) using an electroencephalography (EEG) signals analysis for application in nuclear facilities. To support the study, a quantitative EEG analysis (qEEG) was performed by using a wearable device on 11 healthy subjects. Possible indicators from the qEEG records were examined to identify a non-initiating insider. Such indicators included the relative power of different frequency bands of brain waves (i.e., alpha, beta, theta, gamma and the sum of alpha and theta) and the band-to-band power ratio of beta to alpha and gamma to alpha waves. Results showed that the thinking process of the subjects toward a good (e.g., following the moral compass) versus a bad decision (e.g., cooperation with outsiders) evoked significantly different responses in the relative powers of different frequency band brain waves as well as in the β/α and γ/α band-to-band power ratios. Similar differences were also found for all but the theta band EEG indicators when the subjects committed to a decision related to becoming an insider. The variations in the β/α and γ/α band-to-band power ratios were also found to identify the differences in the level of difficulties involved in the tasks related to becoming an insider. The results indicated that it may be possible to identify a high risk insider based on EEG monitoring using a wearable device.





  • Individual variation in working memory is associated with fear extinction performance
    16 janvier 2018
    Publication date: March 2018
    Source:Behaviour Research and Therapy, Volume 102

    Author(s): Daniel M. Stout, Dean T. Acheson, Tyler M. Moore, Ruben C. Gur, Dewleen G. Baker, Mark A. Geyer, Victoria B. Risbrough

    PTSD has been associated consistently with abnormalities in fear acquisition and extinction learning and retention. Fear acquisition refers to learning to discriminate between threat and safety cues. Extinction learning reflects the formation of a new inhibitory-memory that competes with a previously learned threat-related memory. Adjudicating the competition between threat memory and the new inhibitory memory during extinction may rely, in part, on cognitive processes such as working memory (WM). Despite significant shared neural circuits and signaling pathways the relationship between WM, fear acquisition, and extinction is poorly understood. Here, we analyzed data from a large sample of healthy Marines who underwent an assessment battery including tests of fear acquisition, extinction learning, and WM (N-back). Fear potentiated startle (FPS), fear expectancy ratings, and self-reported anxiety served as the primary dependent variables. High WM ability (N = 192) was associated with greater CS + fear inhibition during the late block of extinction and greater US expectancy change during extinction learning compared to individuals with low WM ability (N = 204). WM ability was not associated with magnitude of fear conditioning/expression. Attention ability was unrelated to fear acquisition or extinction supporting specificity of WM associations with extinction. These results support the conclusion that individual differences in WM may contribute to regulating fear responses.





  • New features for scanned bioelectrical activity of motor unit in health and disease
    16 janvier 2018
    Publication date: March 2018
    Source:Biomedical Signal Processing and Control, Volume 41

    Author(s): N. Tuğrul Artuğ, Imran Goker, Bülent Bolat, Onur Osman, Elif Kocasoy Orhan, M. Baris Baslo

    The present study aims to find new features that support the differential diagnosis of neuromuscular diseases. Scanning EMG is an experimental method developed for understanding the motor unit organization and for observing temporal and spatial characteristics of motor unit’s electrical activity. A motor unit consists of a motor neuron and muscle fibers that are innervated by its motor neuron. Both simulation and biological data on neuromuscular diseases are considered in this study. Biological data were acquired from 3 patients with neurogenic involvement (2 with poliomyelitis sequela and 1 with spinal muscular atrophy), 2 patients with myopathy (1 with inflammatory myopathy and 1 with muscular dystrophy) and 4 healthy participants. Seven features are extracted by specifications of neuromuscular diseases and characteristics of EMG signals. These features are maximum amplitude, spike duration, the number of peaks, maximum amplitude x spike duration, number of peaks x spike duration, the ratio of the power outside the activity corridor to the power inside the activity corridor and the number of peaks outside of the activity corridor. The autocorrelation function of the sum of scanning EMG signals is effective in determining the activity corridor of these signals and the spike duration can be determined more easily by using the activity corridor. Wavelet transform based noise reduction and the windowing method are proposed for calculating the features correctly. By this method, spike duration and the number of peaks should be able to be calculated more precisely. It is confirmed that if the signals are filtered by a high pass filter with a cut off frequency of 2KHz, the calculation of the number of peaks should be easier. While maximum amplitude and maximum amplitude times spike duration are found to be significant for diagnosing neurogenic diseases, other features are found to be significant for all groups by ANOVA test. It is determined that which features are more effective for differential diagnosis and the dataset that contains normal people and patients is classified using multi-layer perceptron (MLP), radial basis function network (RBF), support vector machines (SVM) and k nearest neighbor algorithm (k-NN). The best accuracy is obtained as 85% with MLP network.

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  • An analysis of fear of crime using multimodal measurement
    16 janvier 2018
    Publication date: March 2018
    Source:Biomedical Signal Processing and Control, Volume 41

    Author(s): Seul-Kee Kim, Hang-Bong Kang

    Fear of crime, which may be present without experiencing an actual crime, can restrict one’s daily physical and mental activities and reduce quality of life. In previous research, fear of crime was measured by regional surveys. Though useful for confirming group characteristics, regional surveys cannot measure in real-time, assess individual characteristics, or provide an objective measure of anxiety. Since the causes and effects of fear of crime are highly individualized, we have developed a protocol to measure physiological signals in concert with existing surveys; this system can verify an individual’s fear of crime characteristics in real time. Subjects were shown 6 clips of actual pedestrian environments (day/night of a commercial street scene, day/night of a residential street scene, day/night of a natural street scene). To ease immersion of the subjects into the scenes, clips were produced from the subjects’ first-person point of view. Subjects were divided into two groups (Group1: N=14, age, 22±1.66years; Group2: N=13, age 21±1.35years) based on their fear intensity as reported on our pre-recording survey; electroencephalographic (EEG), electrocardiographic (ECG), and galvanic skin response (GSR) signals were compared between groups. They were then assessed via video for comparative purposes. Our results demonstrated that the physiological signals were dependent on how conscious an individual was of his or her own fear of crime. We found significant differences between the two groups for all video clips except for daytime commercial street and nighttime natural street; these data suggest that individual characteristics are important in measuring fear of crime.





  • An efficient approach for EEG sleep spindles detection based on fractal dimension coupled with time frequency image
    16 janvier 2018
    Publication date: March 2018
    Source:Biomedical Signal Processing and Control, Volume 41

    Author(s): Wessam Al-salman, Yan Li, Peng Wen, Mohammed Diykh

    Detection of the characteristics of the sleep stages, such as sleep spindles and K-complexes in EEG signals, is a challenging task in sleep research as visually detecting them requires high skills and efforts from sleep experts. In this paper, we propose a robust method based on time frequency image (TFI) and fractal dimension (FD) to detect sleep spindles in EEG signals. The EEG signals are divided into segments using a sliding window technique. The window size is set to 0.5 s with an overlapping of 0.4 s. A short time Fourier transform (STFT) is applied to obtain a TFI from each EEG segment. Each TFI is converted into an 8-bit binary image. Then, a box counting method is applied to estimate and discover the FDs of EEG signals. Different sets of features are extracted from each TFI after applying a statistical model to the FD of each TFI. The extracted statistical features are fed to a least square support vector machine (LS_SVM) to figure out the best combination of the features. As a result, the proposed method is found to have a high classification rate with the eight features sets. To verify the effectiveness of the proposed method, different classifiers, including a K-means, Naive Bayes and a neural network, are also employed. In this paper, the proposed method is evaluated using two publically available datasets: Dream sleep spindles and Montreal archive of sleep studies. The proposed method is compared with the current existing methods, and the results revealed that the proposed method outperformed the others. An average accuracy of 98.6% and 97.1% is obtained by the proposed method for the two datasets, respectively.





  • A self-adaptive frequency selection common spatial pattern and least squares twin support vector machine for motor imagery electroencephalography recognition
    16 janvier 2018
    Publication date: March 2018
    Source:Biomedical Signal Processing and Control, Volume 41

    Author(s): Duan Li, Hongxin Zhang, Muhammad Saad Khan, Fang Mi

    Motor imagery brain-computer interface (BCI) systems require accurate and fast recognition of brain activity patterns for reliable communication and interaction. Achieving this accuracy is still a challenge because of the low signal-to-noise ratio in electroencephalography signals and high variability of sensorimotor rhythms. To address this need, we proposed a novel scheme that combined a frequency band selection common spatial pattern algorithm and a particle swarm optimization least squares twin support vector machine classifier for recognition of motor imagery patterns. We used self-adaptive artifact removal and the common spatial pattern method to obtain the most distinguishable features. To improve the classification results, we investigated linear, polynomial, sigmoid, wavelet and gaussian kernel functions for the nonlinear least squares twin support vector machine classifier. Particle swarm optimization, chaotic particle swarm optimization, a genetic algorithm and a quantum genetic algorithm were compared and used to tune the hyper-parameters for the classifier. To evaluate our proposed method, we used BCI Competition IV data sets 2A and 2B. Experimental results showed that for our method, the average recognition accuracy of data set 2A is increased by 6.10%, 6.71%, 3.87%, 4.01%, 2.55% and 4.86% compared with the results obtained by regularization projection twin support vector machine, twin support vector machine, support vector machine, linear discriminant analysis, back propagation and probabilistic neural network, respectively. Using data set 2B, the average recognition accuracy achieved by our method was greater by 4.73%, 5.46%, 4.45%, 4.10%, 8.62% and 4.27%, respectively. The standard deviation of the accuracy values of the two data sets decreased. Furthermore, compared with the traditional support vector machines, our proposed method achieved a faster central processing unit running time for training classifiers.





  • Sleep deprivation decreases neuronal excitability and responsiveness in rats both in vivo and ex vivo
    16 janvier 2018
    Publication date: March 2018
    Source:Brain Research Bulletin, Volume 137

    Author(s): Sándor Borbély, Ildikó Világi, Zsófia Haraszti, Örs Szalontai, Tünde Hajnik, Attila Tóth, László Détári

    Sleep deprivation has severe consequences for higher nervous functions. Its effects on neuronal excitability may be one of the most important factors underlying functional deterioration caused by sleep loss. In the present work, excitability changes were studied using two complementary in vivo and ex vivo models. Auditory evoked potentials were recorded from freely-moving animals in vivo. Amplitude of evoked responses showed a near-continuous decrease during deprivation. Prevention of sleep also reduced synaptic efficacy ex vivo, measured from brain slices derived from rats that underwent sleep deprivation. While seizure susceptibility was not affected significantly by sleep deprivation in these preparations, the pattern of spontaneous seizure activity was altered. If seizures developed, they lasted longer and tended to contain more spikes in slices obtained from sleep-deprived than from control rats. Current-source density analysis revealed that location and sequence of activation of local cortical networks recruited by seizures did not change by sleep deprivation. Moderate differences seen in the amplitude of individual sinks and sources might be explained by smaller net transmembrane currents as a consequence of decreased excitability. These findings contradict the widely accepted conception of synaptic homeostasis suggesting gradual increase of excitability during wakefulness. Our results also indicate that decreased neuronal excitability caused by sleep deprivation is preserved in slices prepared from rats immediately after deprivation. This observation might mean new opportunities to explore the effects of sleep deprivation in ex vivo preparations that allow a wider range of experimental manipulations and more sophisticated methods of analysis than in vivo preparations.

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  • High-performance miniature CSTR for biphasic C–C bond-forming reactions
    16 janvier 2018
    Publication date: 1 March 2018
    Source:Chemical Engineering Journal, Volume 335

    Author(s): Yiming Mo, Hongkun Lin, Klavs F. Jensen

    Chemical transformations used in fine chemical manufacturing often involve two-phase interaction for which mass transfer limitations can lead to prolonged reaction time and reduced productivity. We present a high-performance miniature continuous stirred-tank reactor (CSTR), with non-contact magnetic coupling providing intensive agitation inside the sealed miniaturized chamber. High-speed imaging of the biphasic hydrodynamics gives an estimated mass transfer coefficient (kLa) on the order of 10 s−1, comparable to commercial passive mixing flow reactors. Case studies with two important biphasic C–C bond-forming reactions: (i) asymmetric alkylation catalyzed by cinchonidine-derived phase-transfer catalyst, and (ii) biphasic Suzuki-Miyaura C–C coupling reactions, demonstrate the versatility of the CSTR unit. Moreover, a detailed kinetic model proposed for phase-transfer reaction systems controlled by the Makosza interfacial mechanism further cross-validates the mass transfer coefficient estimates.

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  • Perturbation of muscle metabolism in patients with muscular dystrophy in early or acute phase of disease: In vitro, high resolution NMR spectroscopy based analysis
    16 janvier 2018
    Publication date: March 2018
    Source:Clinica Chimica Acta, Volume 478

    Author(s): Niraj Kumar Srivastava, Ramakant Yadav, Somnath Mukherjee, Neeraj Sinha

    Background Muscular dystrophy is an inherited muscle disease, characterized by progressive muscle wasting and weakness of variable distribution and severity. Methods In vitro, high-resolution proton nuclear magnetic resonance (NMR) spectroscopy based analysis was performed on perchloric acid (PCA) extract of muscle specimens of patients suffering from various types of muscular dystrophies to identify alteration in hydrophilic low-molecular weight substances (aqueous metabolites) as compared to muscle of control subjects as well as in between the types of muscular dystrophy. Muscle tissue specimens were obtained from Duchenne muscular dystrophy (DMD) [n=11], Becker muscular dystrophy (BMD) [n=12], facioscapulohumeral dystrophy (FSHD) [n=9] and limb girdle muscular dystrophy (LGMD)-2B [n=22]. Control muscle specimens [n=40] were also taken. Results Concentration of branched chain amino acids (BCA), glutamine/glutamate (Gln/Glu), acetate (Ace) and fumarate (Fum) was decreased and His was increased in muscle tissue of DMD, BMD, FSHD and LGMD-2B patients as compared to control subjects. Alanine (Ala) was significantly reduced in BMD, FSHD and LGMD-2B patients as compared to control subjects. Tyrosine (Tyr) was present only in the muscle tissue of control subjects. Propionate (Prop) was present in muscle tissue of DMD, BMD, FSHD and LGMD-2B patients and was absent in muscle tissue of control subjects. Concentration of BCA and Prop is significantly reduced in patients with DMD as compared to BMD, but Glucose is significantly higher in patients with DMD as compared to BMD. Quantity of Glucose, His and Gln/glu are significantly higher in patients with DMD as compared to FSHD, but Prop is significantly reduced in patients with DMD as compared to FSHD. Concentration of Ala and His is significantly higher in patients with DMD as compared to LGMD-2B, but BCA, Glucose and Prop are significantly reduced in patients with DMD as compared to LGMD-2B. Concentration of His is significantly higher in patients with BMD as compared to FSHD. Concentration of His is significantly reduced and Glucose is higher in patients with LGMD-2B as compared to BMD. Glucose concentration is significantly reduced in patients with FSHD as compared to LGMD-2B. ROC curves supported the noticeable discrimination in between the patients with DMD and FSHD for the quantity of Gln/Glu, and patients with LGMD-2B and DMD for the quantity of Ala. Collectively, these findings showed the perturbation of muscle metabolism in muscular dystrophy. Conclusions The data of presented study may be used as supporting information for existing methods of the diagnosis for patients with muscular dystrophy.





  • Wakefulness evaluation during sleep for healthy subjects and OSA patients using a patch-type device
    16 janvier 2018
    Publication date: March 2018
    Source:Computer Methods and Programs in Biomedicine, Volume 155

    Author(s): Heenam Yoon, Su Hwan Hwang, Sang Ho Choi, Jae-Won Choi, Yu Jin Lee, Do-Un Jeong, Kwang Suk Park

    Objectives Obstructive sleep apnea (OSA) is a major sleep disorder that causes insufficient sleep, which is linked with daytime fatigue and accidents. Long-term sleep monitoring can provide meaningful information for patients with OSA to prevent and manage their symptoms. Even though various methods have been proposed to objectively measure sleep in ambulatory environments, less reliable information was provided in comparison with standard polysomnography (PSG). Therefore, this paper proposes an algorithm for distinguishing wakefulness from sleep using a patch-type device, which is applicable for both healthy individuals and patients with OSA. Methods Electrocardiogram (ECG) and 3-axis accelerometer signals were gathered from the single device. Wakefulness was determined with six parallel methods based on information about movement and autonomic nervous activity. The performance evaluation was conducted with five-fold cross validation using the data from 15 subjects with a low respiratory disturbance index (RDI) and 10 subjects with high RDI. In addition, wakefulness information, including total sleep time (TST), sleep efficiency (SE), sleep onset latency (SOL), and wake after sleep onset (WASO), were extracted from the proposed algorithm and compared with those from PSG. Results According to epoch-by-epoch (30 s) analysis, the performance results of detecting wakefulness were an average Cohen's kappa of 0.60, accuracy of 91.24%, sensitivity of 64.12%, and specificity of 95.73%. Moreover, significant correlations were observed in TST, SE, SOL, and WASO between the proposed algorithm and PSG (p < 0.001). Conclusions Wakefulness-related information was successfully provided using data from the patch-type device. In addition, the performance results of the proposed algorithm for wakefulness detection were competitive with those from previous studies. Therefore, the proposed system could be an appropriate solution for long-term objective sleep monitoring in both healthy individuals and patients with OSA.





  • Mice overexpressing lamin B1 in oligodendrocytes recapitulate the age-dependent motor signs, but not the early autonomic cardiovascular dysfunction of autosomal-dominant leukodystrophy (ADLD)
    16 janvier 2018
    Publication date: March 2018
    Source:Experimental Neurology, Volume 301, Part A

    Author(s): Viviana Lo Martire, Sara Alvente, Stefano Bastianini, Chiara Berteotti, Cristiano Bombardi, Giovanna Calandra-Buonaura, Sabina Capellari, Gary Cohen, Pietro Cortelli, Laura Gasparini, Quasar Padiath, Alice Valli, Giovanna Zoccoli, Alessandro Silvani

    Autosomal dominant leukodystrophy (ADLD) is a rare adult-onset demyelinating disease caused by overexpression of lamin B1, a nuclear lamina filament. Early autonomic dysfunction involving the cardiovascular system before progressive somatic motor dysfunction is a striking feature of most cases of ADLD. In the Plp-FLAG-LMNB1 transgenic mouse model, lamin B1 overexpression in oligodendrocytes elicits somatic motor dysfunction and neuropathology akin to ADLD. Here, we investigate whether Plp-FLAG-LMNB1 mice also develop autonomic cardiovascular dysfunction before or after somatic motor dysfunction. We find that Plp-FLAG-LMNB1 mice have preserved cardiovascular responses to changes in wake-sleep state and ambient temperature and normal indexes of autonomic modulation at 37–42weeks of age despite a progressive somatic motor dysfunction, which includes impairments of walking ability (the ability to walk on a narrow path was impaired in 80% of mice at 34–38weeks of age) and subtle breathing derangements. Only late in the development of the disease phenotype did Plp-FLAG-LMNB1 mice develop a structural deficit of sympathetic noradrenergic fibers, with a 38% decrease in fiber profiles in the kidneys at 44–47weeks of age. We demonstrate that while the Plp-FLAG-LMNB1 mouse model recapitulates the age-dependent motor dysfunction of ADLD, it does not show signs of early autonomic cardiovascular dysfunction, raising the possibility that oligodendrocyte dysfunction may not be sufficient to cause the full spectrum of clinical features present in ADLD.





  • A robust structure identification method for evolving fuzzy system
    16 janvier 2018
    Publication date: 1 March 2018
    Source:Expert Systems with Applications, Volume 93

    Author(s): Hisham Haider Yusef Sa'ad, Nor Ashidi Mat Isa, Md. Manjur Ahmed, Adnan Haider Yusef Sa'd

    This paper proposes a robust structure identification method (RSIM) based on incremental partitioning learning. RSIM starts with an open region (initial domain) that covers all input samples. The initial region starts with one fuzzy rule without fuzzy terms and then evolves through incremental partitioning learning, which creates many subregions for system error minimization. The three major contributions of the proposed RSIM are as follows: It locates sufficient splitting points provided through a robust partitioning technique, determines the optimum trade-off between accuracy and complexity through a novel partition-selection technique, minimizes global error through global least square optimization. These contributions offer many remarkable advantages. First, RSIM provides a solution for the curse of dimensionality. Second, RSIM can also be applied to low-dimensional problems. Third, RSIM seeks to produce few rules with low number of conditions to improve system readability. Fourth, RSIM minimizes the number of fired rules. Therefore, RSIM can achieve low-level complexity systems. Three low-dimension and six high-dimension and real-life benchmarks are used to evaluate the performance of RSIM with state-of-the art methods. Although RSIM has high interpretability, the results prove that RSIM exhibits greater accuracy than other existing methods.





  • Wheat lines exhibiting variation in tolerance of Septoria tritici blotch differentiated by grain source limitation
    16 janvier 2018
    Publication date: March 2018
    Source:Field Crops Research, Volume 217

    Author(s): F. Collin, P. Bancal, J. Spink, P. Kock Appelgren, J. Smith, N.D. Paveley, M-O. Bancal, M.J. Foulkes

    Septoria tritici blotch (STB) is the most damaging disease of wheat crops in Europe. Because of the partial nature of genotypic resistance or the increasing resistance against fungicides, the tolerance, i.e. maintaining yield in the presence of expressed disease, is a relevant alternative. Tolerance is generally estimated through the yield loss per unit of source reduction, contrasts of tolerance between genotypes have been observed previously suggesting that either increasing the source availability or improving the use of stored assimilate could improve tolerance. This paper aims at developing a source/sink approach to understand the tolerance mechanism and identifying potential traits to increase tolerance of STB. A field experiment was designed to explore the relation between tolerance of STB and source/sink balance. Based on six wheat genotypes contrasting for tolerance exposed to natural STB epidemics, late nitrogen fertilization and a 50% spikelet removal were applied to change the source/sink balance. The tolerance of genotypes was quantitatively estimated over three additional field experiments. We found that STB tolerance was correlated with traits of healthy crops (high individual grain weight and high proportion of green leaf lamina area as leaf 3; flag leaf=leaf 1). The spikelet removal revealed a highly variable degree of source limitation for grain filling amongst the six genotypes. Thus, we proposed an easily calculated index that highly correlated positively with the labor intensive estimation of STB tolerance. Finally, potential yield and tolerance were not correlated, which suggests that breeding for yield performance and tolerance could be possible.





  • Physicochemical characteristics of complexes between amylose and garlic bioactive components generated by milling activating method
    16 janvier 2018
    Publication date: March 2018
    Source:Food Research International, Volume 105

    Author(s): Liming Zhang, Ping Guan, Zhihan Zhang, Yujie Dai, Limin Hao

    Complexes of amylose (Am) with garlic bioactive components (GBCs) were prepared by milling activating treatment of Am and garlic paste (GP) together. The complex, produced by milling for 2.5h with the garlic (dry basis)/Am ratio of 1:5 (w/w) and water content of 25% (w/w) exhibited significantly higher allicin content (0.49mg/g of complex) than others. The scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transforms infrared (FT-IR), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), high performance liquid chromatography (HPLC), and gas chromatography–mass spectrometry (GC–MS) techniques were used complex characterization. XRD results indicated that the Am and garlic bioactive components formed the V-type structure. FT-IR and DSC analysis further confirmed the formation of the Am-GBCs complex, and its thermal stability was improved in comparison with garlic powder. According to GC–MS results, all organosulfur compounds (OSCs) in fresh garlic were better retained to Am-GBCs complex. Therefore, the Am-GBCs complexes can have important applications as stable natural flavor compound systems.

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  • Walking measures to evaluate assistive technology for foot drop in multiple sclerosis: A systematic review of psychometric properties
    16 janvier 2018
    Publication date: March 2018
    Source:Gait & Posture, Volume 61

    Author(s): Georgia Andreopoulou, Thomas H. Mercer, Marietta L. van der Linden

    Background Foot drop in people with multiple sclerosis (pwMS) often managed with assistive technologies, such as functional electrical stimulation and ankle foot orthoses. No evidence synthesis exists for the psychometric properties of outcomes used to evaluate the efficacy of these interventions. Objective This systematic review aimed to identify the outcome measures reported to assess the benefits of assistive technology for pwMS and then synthesize the psychometric evidence in pwMS for a subset of these measures. Methods Two searches in eight databases were conducted up to May 2017. Methodological quality was rated using the COSMIN guidelines. Overall level of evidence was scored according to the Cochrane criteria. Results The first search identified 27 measures, with the 10 m walk test, gait kinematics and Physiological Cost Index (PCI) most frequently used. The second search resulted in 41 studies evaluating 10 measures related to walking performance. Strong levels of evidence were found for the internal consistency and test-retest reliability of the Multiple Sclerosis Walking Scale-12 and for the construct validity for Timed 25 Foot Walk. No psychometric studies were identified for gait kinematics and PCI in pwMS. There was a lack of evidence for measurement error and responsiveness. Conclusion Although a strong level of evidence exists for some measures included in this review, there was an absence of psychometric studies on commonly used measures such as gait kinematics. Future psychometric studies should evaluate a wider range of walking related measures used to assess the efficacy of interventions to treat foot drop in pwMS.





  • Surface EMG patterns for quantification of thigh muscle co-contraction in school-age children: Normative data during walking
    16 janvier 2018
    Publication date: March 2018
    Source:Gait & Posture, Volume 61

    Author(s): Francesco Di Nardo, Annachiara Strazza, Alessandro Mengarelli, Serena Ercolani, Nicole Morgoni, Laura Burattini, Valentina Agostini, Marco Knaflitz, Sandro Fioretti

    Muscle co-contractions are particularly relevant in analyzing children pathologies. To interpret surface electromyography (sEMG) in pathological conditions, reliable normative data in non-pathological children are required for direct comparison. Aim of the study was the quantification of co-contraction activity between quadriceps femoris (QF) and hamstring muscles during walking in healthy children. To this aim, Statistical gait analysis was performed on sEMG signals from rectus femoris (RF), vastus medialis (VM), and lateral hamstrings (LH), in 16401 strides walked by 100 healthy school-age children. Co-contractions were assessed as overlapping period between activation intervals of considered muscles. Results showed full superimpositions of LH with both RF and VL activity from terminal swing, 80–100% of gait cycle, to successive loading response (0–15% of gait cycle), in around 90% of strides, as reported in adults. This indicates that children regularly use a cocontraction activity between QF and hamstring muscles in weight acceptance during walking, supporting the hypothesis of a regulatory role of co-contraction in providing knee joint stability. Concomitant activity of QF and hamstring muscles was detected also during push-off phase (30–50% of gait cycle), showing a large variability intra and inter subjects and a lower occurrence frequency (around 25% of strides). This could be intended for controlling rapid knee flexion and/or stabilizing pelvis during body progression. Present findings represent the first attempt to provide normative sEMG dataset on variability of QF and hamstring muscles co-contractions during child walking, useful for discriminating physiological and pathological behavior and for designing future studies on maturation of gait.





  • Effect of foot progression angle adjustment on the knee adduction moment and knee joint contact force in runners with and without knee osteoarthritis
    16 janvier 2018
    Publication date: March 2018
    Source:Gait & Posture, Volume 61

    Author(s): I.C.D. Fong, W.S.C. Li, W.K.J. Tai, T.W.R. Tsang, J.H. Zhang, T.L.W. Chen, H. Baur, P. Eichelberger, R.T.H. Cheung

    Background Knee adduction moment (KAM) is often used as a surrogate marker of knee contact force (KCF) during walking. Previous studies have reported potential benefits to reduce KAM in patients with knee osteoarthritis (OA) by foot progression angle adjustment. However, KAM is an external moment and it does not consider any muscle contribution to the joint loading, which should pose a greater influence in running than walking. Research question This study used a computational model to compare KAM and KCF between runners with and without knee OA during running. In addition, we evaluated the KAM and KCF when runners adjusted to an out-toe running style. Methods Kinematic, kinetic, and lower limb EMG data were collected from 9 runners with knee OA and 10 healthy counterparts. They were asked to run at their usual speed with standard shoes on an instrumented treadmill. Results We found no significant difference in the KAM during running between OA and the healthy group (p > 0.376). However, runners with knee OA exhibited a greater total KCF than the healthy counterparts (p < 0.041). We did not observe any reduction in KAM after foot progression angle adjustment (p > 0.346). Surprisingly, an increase in the longitudinal KCF and total KCF were found with adjustment of foot progression angle (p < 0.046). Significance Unlike the findings reported by the previous walking trials, our findings do not support the notion that foot progression angle adjustment would lead to a lower joint loading during running.





  • Temporal-spatial gait parameter models of very slow walking
    16 janvier 2018
    Publication date: March 2018
    Source:Gait & Posture, Volume 61

    Author(s): Andrew J.J. Smith, Edward D. Lemaire

    This study assessed the relationship between walking speed and common temporal-spatial stride-parameters to determine if a change in gait strategy occurs at extremely slow walking speeds. Stride-parameter models that represent slow walking can act as a reference for lower extremity exoskeleton and powered orthosis controls since these devices typically operate at walking speeds less than 0.4 m/s. Full-body motion capture data were collected from 30 health adults while walking on a self-paced treadmill, within a CAREN-Extended virtual reality environment. Kinematic data were collected for 0.2–0.8 m/s, and self-selected walking speed. Eight temporal stride-parameters were determined and their relationship to walking speed was assessed using linear and quadratic regression. Stride-length, step-length, and step-frequency were linearly related to walking speed, even at speeds below 0.4 m/s. An inflection point at 0.5 m/s was found for stride-time, step-time, stance-time, and double support time. Equations were defined for each stride-parameter, with equation outputs producing correlations greater than 0.91 with the test data. This inflection point suggests a change in gait strategy at very slow walking speeds favouring greater ground contact time.





  • Towards unravelling the relationship between on-body, environmental and emotion data using sensor information fusion approach
    16 janvier 2018
    Publication date: March 2018
    Source:Information Fusion, Volume 40

    Author(s): Eiman Kanjo, Eman M.G. Younis, Nasser Sherkat

    Over the past few years, there has been a noticeable advancement in environmental models and information fusion systems taking advantage of the recent developments in sensor and mobile technologies. However, little attention has been paid so far to quantifying the relationship between environment changes and their impact on our bodies in real-life settings. In this paper, we identify a data driven approach based on direct and continuous sensor data to assess the impact of the surrounding environment and physiological changes and emotion. We aim at investigating the potential of fusing on-body physiological signals, environmental sensory data and on-line self-report emotion measures in order to achieve the following objectives: (1) model the short term impact of the ambient environment on human body, (2) predict emotions based on-body sensors and environmental data. To achieve this, we have conducted a real-world study ‘in the wild’ with on-body and mobile sensors. Data was collected from participants walking around Nottingham city centre, in order to develop analytical and predictive models. Multiple regression, after allowing for possible confounders, showed a noticeable correlation between noise exposure and heart rate. Similarly, UV and environmental noise have been shown to have a noticeable effect on changes in ElectroDermal Activity (EDA). Air pressure demonstrated the greatest contribution towards the detected changes in body temperature and motion. Also, significant correlation was found between air pressure and heart rate. Finally, decision fusion of the classification results from different modalities is performed. To the best of our knowledge this work presents the first attempt at fusing and modelling data from environmental and physiological sources collected from sensors in a real-world setting.





  • The effects of valve-handwheel height and angle on neck, shoulder, and back muscle loading
    16 janvier 2018
    Publication date: March 2018
    Source:International Journal of Industrial Ergonomics, Volume 64

    Author(s): Saif Al-Qaisi, Fereydoun Aghazadeh

    The objectives of this research were to: (1) investigate the effects of handwheel height and angle of a valve on the muscle loading of shoulder, neck, and back muscles; and (2) identify a handwheel height and angle that best distributes the load of torque exertions to different muscles. Fifteen healthy male participants were recruited for this study. The handwheel heights included knee, elbow, shoulder, and overhead levels. The handwheel angles included 0°, 45°, and 90°. At each height-angle combination, participants performed an isometric torque exertion on a handwheel. During each trial, the maximum electromyography (EMG) activities were measured from the right and left anterior deltoids, trapezii, latissimi dorsi, and erector spinae muscles. EMG data were normalized and reported as percentages of reference contractions (RC). A two factor split-plot analysis of variance (ANOVA) and Tukey multiple pairwise comparison tests were performed to determine the significant effects. Results show that a handwheel at overhead 45°, which allows the greatest torque production, is associated with a concentrated load on the right anterior deltoid (94.1 %RC). At elbow level, participants were exposed to low loads on the shoulder and neck muscles, but that was compensated with higher loads on the back muscles. Based on the EMG results, the best handwheel height and angle appeared to be at shoulder 0°. At this height and angle, seven of the eight muscles were working at or close to their lowest EMG activities, while also allowing the production of relatively large torques (65.2 Nm).





  • Correlations between pediatric obstructive sleep apnea and longitudinal growth
    16 janvier 2018
    Publication date: March 2018
    Source:International Journal of Pediatric Otorhinolaryngology, Volume 106

    Author(s): Do-Yang Park, Ji Ho Choi, So Young Kang, Jinjoo Han, Hun Yi Park, Jin Soon Hwang, Jae Ho Cho, Min Hyuk Cho, Hyun Jun Kim

    Objectives Pediatric obstructive sleep apnea has a relatively high prevalence and has various negative health and behavioral consequences. Among the various complications of pediatric obstructive sleep apnea, growth disturbance is still controversial. Method 745 pediatric subjects with obstructive sleep apnea diagnosed by in-lab polysomnography were enrolled, after excluding ineligible subjects with abnormal growth related factors. Height, weight, and BMI of enrolled patients were measured and statistically converted to z-scores, and the converted data were analyzed statistically with the polysomnographic results. Multiple linear regression were used to analyze the relationships between age, gender, z-score for weight, polysomnography results, and z-score for height. Results Patients with higher respiratory related index or lower mean/lowest oxygen saturation of PSG showed smaller z-score for height. Mean apnea hypopnea index and standard deviation of enrolled patients was 7.46 ± 12.92, with moderate severity. And mean z-score for height and standard deviation was 0.21 ± 1.15. Apnea hypopnea index, respiratory disturbance index, obstructive apnea index, and hypopnea index, respiratory related results of polysomnography, were statistically negative correlated with a z-score for height. And mean oxygen saturation and lowest oxygen saturation, oxygen saturation results of polysomnography, were statistically positive correlated with a z-score for height. Conclusions Respiratory related results and oxygen saturation results of polysomnography show negative and positive correlation with z-score for height. Therefore, pediatric obstructive sleep apnea have a negative effect on longitudinal growth.





 

Mis à jour le 03 avril 2013