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https://www.readbyqxmd.com/read/28813876/design-control-and-validation-of-the-variable-stiffness-exoskeleton-flexo
#1
Sariah Mghames, Marco Laghi, Cosimo Della Santina, Manolo Garabini, Manuel Catalano, Giorgio Grioli, Antonio Bicchi
In this paper we present the design of a one degree of freedom assistive platform to augment the strength of upper limbs. The core element is a variable stiffness actuator, closely reproducing the behavior of a pair of antagonistic muscles. The novelty introduced by this device is the analogy of its control parameters with those of the human muscle system, the threshold lengths. The analogy can be obtained from a proper tuning of the mechanical system parameters. Based on this, the idea is to control inputs by directly mapping the estimation of the muscle activations, e...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28813796/feedforward-model-based-arm-weight-compensation-with-the-rehabilitation-robot-armin
#2
Fabian Just, Ozhan Ozen, Stefano Tortora, Robert Riener, Georg Rauter
Highly impaired stroke patients at early stages of recovery are unable to generate enough muscle force to lift the weight of their own arm. Accordingly, task-related training is strongly limited or even impossible. However, as soon as partial or full arm weight support is provided, patients are enabled to perform arm rehabilitation training again throughout an increased workspace. In the literature, the current solutions for providing arm weight support are mostly mechanical. These systems have components that restrict the freedom of movement or entail additional disturbances...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28808338/a-dynamical-framework-for-complex-fractional-killing
#3
Richard Ballweg, Andrew L Paek, Tongli Zhang
When chemotherapy drugs are applied to tumor cells with the same or similar genotypes, some cells are killed, while others survive. This fractional killing contributes to drug resistance in cancer. Through an incoherent feedforward loop, chemotherapy drugs not only activate p53 to induce cell death, but also promote the expression of apoptosis inhibitors which inhibit cell death. Consequently, cells in which p53 is activated early undergo apoptosis while cells in which p53 is activated late survive. The incoherent feedforward loop and the essential role of p53 activation timing makes fractional killing a complex dynamical challenge, which is hard to understand with intuition alone...
August 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28796509/predicting-thermal-behavior-of-secondary-organic-aerosols
#4
John H Offenberg, Michael Lewandowski, Tadeusz E Kleindienst, Kenneth S Docherty, Mohammed Jaoui, Jonathan Krug, Theran P Riedel, David A Olson
Volume concentrations of secondary organic aerosol (SOA) are measured in 139 steady-state, single precursor hydrocarbon oxidation experiments after passing through a temperature controlled inlet. The response to change in temperature is well predicted through a feedforward Artificial Neural Network. The most parsimonious model, as indicated by Akaike's Information Criterion, Corrected (AIC,C), utilizes 11 input variables, a single hidden layer of 4 tanh activation function nodes, and a single linear output function...
August 10, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28783639/supervised-learning-based-on-temporal-coding-in-spiking-neural-networks
#5
Hesham Mostafa
Gradient descent training techniques are remarkably successful in training analog-valued artificial neural networks (ANNs). Such training techniques, however, do not transfer easily to spiking networks due to the spike generation hard nonlinearity and the discrete nature of spike communication. We show that in a feedforward spiking network that uses a temporal coding scheme where information is encoded in spike times instead of spike rates, the network input-output relation is differentiable almost everywhere...
August 1, 2017: IEEE Transactions on Neural Networks and Learning Systems
https://www.readbyqxmd.com/read/28767379/composite-backstepping-consensus-algorithms-of-leader-follower-higher-order-nonlinear-multiagent-systems-subject-to-mismatched-disturbances
#6
Xiangyu Wang, Shihua Li, Michael Z Q Chen
This paper is devoted to solving the output consensus problem of leader-follower higher-order nonlinear multiagent systems subject to mismatched disturbances. The disturbances are allowed to be in higher-order forms. First, by constructing a generalized proportional-integral observer for each follower, estimates of the disturbances and their derivatives are obtained. At the same time, a distributed observer is also developed for the followers to estimate the leader state information. Second, based on the estimates of the disturbances and the leader state, together with the backstepping technique, a feedforward-feedback composite consensus control scheme is proposed...
July 27, 2017: IEEE Transactions on Cybernetics
https://www.readbyqxmd.com/read/28763761/feedforward-neural-network-methodology-to-characterize-thin-films-by-electrostatic-force-microscopy
#7
M Konomi, G M Sacha
The contribution of the present paper is in introducing a numerical method to improve the automatic characterization of thin films by increasing the effectiveness of numerical methods that take into account the macroscopic shape of the tip. To achieve this objective, we propose the combination of different feedforward neural networks architectures adapted to the specific requirements of the physical system under study. First, an Adaline architecture is redefined as a linear combination of Green functions obtained from the Laplace equation...
July 26, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/28756947/two-element-transcriptional-regulation-in-the-canonical-wnt-pathway
#8
Kibeom Kim, Jaehyoung Cho, Thomas S Hilzinger, Harry Nunns, Andrew Liu, Bryan E Ryba, Lea Goentoro
The canonical Wnt pathway regulates numerous fundamental processes throughout development and adult physiology and is often disrupted in diseases [1-4]. Signal in the pathway is transduced by β-catenin, which in complex with Tcf/Lef regulates transcription. Despite the many processes that the Wnt pathway governs, β-catenin acts primarily on a single cis element in the DNA, the Wnt-responsive element (WRE), at times potentiated by a nearby Helper site. In this study, working with Xenopus, mouse, and human systems, we identified a cis element, distinct from WRE, upon which β-catenin and Tcf act...
August 7, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28754776/the-hlf-il-6-stat3-feedforward-circuit-drives-hepatic-stellate-cell-activation-to-promote-liver-fibrosis
#9
Dai-Min Xiang, Wen Sun, Bei-Fang Ning, Teng-Fei Zhou, Xiao-Feng Li, Wei Zhong, Zhuo Cheng, Ming-Yang Xia, Xue Wang, Xing Deng, Wei Wang, Heng-Yu Li, Xiu-Liang Cui, Shi-Chao Li, Bin Wu, Wei-Fen Xie, Hong-Yang Wang, Jin Ding
BACKGROUND AND AIMS: Liver fibrosis is a wound-healing response that disrupts the liver architecture and function by replacing functional parenchyma with scar tissue. Recent progress has advanced our knowledge of this scarring process, but the detailed mechanism of liver fibrosis is far from clear. METHODS: The fibrotic specimens of patients and HLF (hepatic leukemia factor)(PB/PB) mice were used to assess the expression and role of HLF in liver fibrosis. Primary murine hepatic stellate cells (HSCs) and human HSC line Lx2 were used to investigate the impact of HLF on HSC activation and the underlying mechanism...
July 28, 2017: Gut
https://www.readbyqxmd.com/read/28751279/the-extracellular-role-of-dna-damage-repair-protein-ape1-in-regulation-of-il-6-expression
#10
Somsubhra Nath, Shrabasti Roychoudhury, Matthew J Kling, Heyu Song, Pranjal Biswas, Ashima Shukla, Hamid Band, Shantaram Joshi, Kishor K Bhakat
The human apurinic/apyrimidinic endonuclease 1 (APE1) is a pleiotropic nuclear protein with roles in DNA base excision repair pathway as well as in regulation of transcription. Recently, the presence of extracellular plasma APE1 was reported in endotoxemic rats. However, the biological significance and the extracellular function of APE1 remain unclear. In this study, we found that monocytes secrete APE1 upon inflammatory challenges. Challenging the monocytic cells with extracellular APE1 resulted in the increased expression and secretion of the pro-inflammatory cytokine IL-6...
July 25, 2017: Cellular Signalling
https://www.readbyqxmd.com/read/28750005/from-grid-cells-to-place-cells-with-realistic-field-sizes
#11
Torsten Neher, Amir Hossein Azizi, Sen Cheng
While grid cells in the medial entorhinal cortex (MEC) of rodents have multiple, regularly arranged firing fields, place cells in the cornu ammonis (CA) regions of the hippocampus mostly have single spatial firing fields. Since there are extensive projections from MEC to the CA regions, many models have suggested that a feedforward network can transform grid cell firing into robust place cell firing. However, these models generate place fields that are consistently too small compared to those recorded in experiments...
2017: PloS One
https://www.readbyqxmd.com/read/28747874/the-functioning-of-a-cortex-without-layers
#12
REVIEW
Julien Guy, Jochen F Staiger
A major hallmark of cortical organization is the existence of a variable number of layers, i.e., sheets of neurons stacked on top of each other, in which neurons have certain commonalities. However, even for the neocortex, variable numbers of layers have been described and it is just a convention to distinguish six layers from each other. Whether cortical layers are a structural epiphenomenon caused by developmental dynamics or represent a functionally important modularization of cortical computation is still unknown...
2017: Frontiers in Neuroanatomy
https://www.readbyqxmd.com/read/28745372/systems-level-organization-of-non-alcoholic-fatty-liver-disease-progression-network
#13
K Shubham, L Vinay, P K Vinod
Non-Alcoholic Fatty Liver Disease (NAFLD) is a complex spectrum of diseases ranging from simple steatosis to Non-Alcoholic Steatohepatitis (NASH) with fibrosis, which can progress to cirrhosis and hepatocellular carcinoma. The pathogenesis of NAFLD is complex, involving crosstalk between multiple organs, cell-types, and environmental and genetic factors. Dysfunction of the adipose tissue plays a central role in NAFLD progression. Here, we analysed transcriptomics data obtained from the Visceral Adipose Tissue (VAT) of NAFLD patients to understand how the VAT metabolism is altered at the genome scale and co-regulated with other cellular processes during the progression from obesity to NASH with fibrosis...
July 26, 2017: Molecular BioSystems
https://www.readbyqxmd.com/read/28738310/postural-response-to-predictable-and-nonpredictable-visual-flow-in-children-and-adults
#14
Mark A Schmuckler
Children's (3-5years) and adults' postural reactions to different conditions of visual flow information varying in its frequency content was examined using a moving room apparatus. Both groups experienced four conditions of visual input: low-frequency (0.20Hz) visual oscillations, high-frequency (0.60Hz) oscillations, multifrequency nonpredictable visual input, and no imposed visual information. Analyses of the frequency content of anterior-posterior (AP) sway revealed that postural reactions to the single-frequency conditions replicated previous findings; children were responsive to low- and high-frequency oscillations, whereas adults were responsive to low-frequency information...
November 2017: Journal of Experimental Child Psychology
https://www.readbyqxmd.com/read/28736520/combined-effects-of-feedforward-inhibition-and-excitation-in-thalamocortical-circuit-on-the-transitions-of-epileptic-seizures
#15
Denggui Fan, Lixia Duan, Qian Wang, Guoming Luan
The mechanisms underlying electrophysiologically observed two-way transitions between absence and tonic-clonic epileptic seizures in cerebral cortex remain unknown. The interplay within thalamocortical network is believed to give rise to these epileptic multiple modes of activity and transitions between them. In particular, it is thought that in some areas of cortex there exists feedforward inhibition from specific relay nucleus of thalamus (TC) to inhibitory neuronal population (IN) which has even more stronger functions on cortical activities than the known feedforward excitation from TC to excitatory neuronal population (EX)...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28736308/laminar-fmri-what-can-the-time-domain-tell-us
#16
REVIEW
Natalia Petridou, Jeroen C W Siero
The rapid developments in functional MRI (fMRI) acquisition methods and hardware technologies in recent years, particularly at high field (≥7 T), have enabled unparalleled visualization of functional detail at a laminar or columnar level, bringing fMRI close to the intrinsic resolution of brain function. These advances highlight the potential of high resolution fMRI to be a valuable tool to study the fundamental processing performed in cortical micro-circuits, and their interactions such as feedforward and feedback processes...
July 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28729159/what-do-we-know-about-laminar-connectivity
#17
REVIEW
Kathleen S Rockland
In this brief review, I attempt an overview of the main components of anatomical laminar-level connectivity. These are: extrinsic outputs, excitatory and inhibitory intrinsic connectivity, and intrinsic inputs. Supporting data are biased from the visual system of nonhuman primates (NHPs), but I have drawn as much as possible from a broader span in order to treat the important issue of area-specific variability. In a second part, I briefly discuss laminar connectivity in the context of network organization (feedforward/feedback cortical connections, and the major types of corticothalamic connections)...
July 17, 2017: NeuroImage
https://www.readbyqxmd.com/read/28722113/specialised-stomatal-humidity-responses-underpin-ecological-diversity-in-c3-bromeliads
#18
Jamie Males, Howard Griffiths
The Neotropical Bromeliaceae display an extraordinary level of ecological variety, with species differing widely in habit, photosynthetic pathway, and growth form. Divergences in stomatal structure and function, hitherto understudied in treatments of bromeliad evolutionary physiology, could have been critical to the generation of variety in ecophysiological strategies among the bromeliads. Since humidity is a key factor in bromeliad niches, we focussed on stomatal responses to vapour pressure deficit (VPD)...
July 19, 2017: Plant, Cell & Environment
https://www.readbyqxmd.com/read/28716400/direct-identification-of-generalized-prandtl-ishlinskii-model-inversion-for-asymmetric-hysteresis-compensation
#19
Young-Rae Ko, Yoonkyu Hwang, Minji Chae, Tae-Hyoung Kim
In this study, we present an identification-based direct construction of the inverse generalized Prandtl-Ishlinskii (P-I) model to facilitate inverse model-based feedforward compensation of asymmetric hysteresis nonlinearities. Compared with the derivation of the inverse model analytically from a generalized P-I model, this direct modeling approach has the following advantages. First, direct inverse model identification is formulated as a nonlinear optimization problem, which is not subject to the constraint condition on the generalized P-I model's threshold and density functions, where this is indispensable for the analytical model inversion procedure...
July 14, 2017: ISA Transactions
https://www.readbyqxmd.com/read/28709746/the-most-promising-advances-in-our-understanding-and-treatment-of-functional-psychogenic-movement-disorders
#20
Mark Hallett
The name functional rather than psychogenic is getting to be more widely used for terminology of this condition. It is better accepted by patients and keeps an open mind in searching for greater understanding of the pathophysiology. Advances in the pathophysiology show an overactive limbic system with connections to the motor system. Moreover, there is a disruption of the self-agency network, possibly due to a failure of feedforward signaling. There has recently been more success in treating patients. The strongest evidence is for intensive physical therapy coupled with at least some psychological support...
July 8, 2017: Parkinsonism & related Disorders
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