1,224 research outputs found

    Neuroendocrine and Behavioral Responses and Brain Pattern of c- fos Induction Associated with Audiogenic Stress

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72579/1/j.1365-2826.1997.00593.x.pd

    Modeling of physical human–robot interaction : admittance controllers applied to intelligent assist devices with large payload

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    Enhancement of human performance using an intelligent assist device is becoming more common. In order to achieve effective augmentation of human capacity, cooperation between human and robot must be safe and very intuitive. Ensuring such collaboration remains a challenge, especially when admittance control is used. This paper addresses the issues of transparency and human perception coming from vibration in admittance control schemes. Simulation results obtained with our suggested improved model using an admittance controller are presented, then four models using transfer functions are discussed in detail and evaluated as a means of simulating physical human–robot interaction using admittance control. The simulation and experimental results are then compared in order to assess the validity and limitations of the proposed models in the case of a four-degree-of-freedom intelligent assist device designed for large payload

    Active stability observer using artificial neural network for intuitive physical human–robot interaction

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    Physical human-robot interaction may present an obstacle to transparency and operations’ intuitiveness. This barrier could occur due to the vibrations caused by a stiff environment interacting with the robotic mechanisms. In this regard, this paper aims to deal with the aforementioned issues while using an observer and an adaptive gain controller. The adaptation of the gain loop should be performed in all circumstances in order to maintain operators’ safety and operations’ intuitiveness. Hence, two approaches for detecting and then reducing vibrations will be introduced in this study as follows: 1) a statistical analysis of a sensor signal (force and velocity) and 2) a multilayer perceptron artificial neural network capable of compensating the first approach for ensuring vibrations identification in real time. Simulations and experimental results are then conducted and compared in order to evaluate the validity of the suggested approaches in minimizing vibrations

    The Impact of Experimental Pain on Shoulder Movement During an Arm Elevated Reaching Task in a Virtual Reality Environment

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    Background: People with chronic shoulder pain have been shown to present with motor adaptations during arm movements. These adaptations may create abnormal physical stress on shoulder tendons and muscles. However, how and why these adaptations develop from the acute stage of pain is still not well-understood. Objective: To investigate motor adaptations following acute experimental shoulder pain during upper limb reaching. Methods: Forty participants were assigned to the Control or Pain group. They completed a task consisting of reaching targets in a virtual reality environment at three time points: (1) baseline (both groups pain-free), (2) experimental phase (Pain group experiencing acute shoulder pain induced by injecting hypertonic saline into subacromial space), and (3) Post experimental phase (both groups pain-free). Electromyographic (EMG) activity, kinematics, and performance data were collected. Results: The Pain group showed altered movement planning and execution as shown by a significant increased delay to reach muscles EMG peak and a loss of accuracy, compared to controls that have decreased their mean delay to reach muscles peak and improved their movement speed through the phases. The Pain group also showed protective kinematic adaptations using less shoulder elevation and elbow flexion, which persisted when they no longer felt the experimental pain. Conclusion: Acute experimental pain altered movement planning and execution, which affected task performance. Kinematic data also suggest that such adaptations may persist over time, which could explain those observed in chronic pain populations

    A separable domain of the p150 subunit of human Chromatin Assembly Factor-1 promotes protein and chromosome associations with nucleoli

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    Chromatin Assembly Factor-1 (CAF-1) is a three-subunit protein complex conserved throughout eukaryotes that deposits histones during DNA synthesis. Here, we present a novel role for the human p150 subunit in regulating nucleolar macromolecular interactions. Acute depletion of p150 causes redistribution of multiple nucleolar proteins and reduces nucleolar association with several repetitive element-containing loci. Notably, a point mutation in a SUMO-interacting motif (SIM) within p150 abolishes nucleolar associations, whereas PCNA or HP1 interaction sites within p150 are not required for these interactions. Additionally, acute depletion of SUMO-2 or the SUMO E2 ligase Ubc9 reduces alpha-satellite DNA association with nucleoli. The nucleolar functions of p150 are separable from its interactions with the other subunits of the CAF-1 complex, because an N-terminal fragment of p150 (p150N) that cannot interact with other CAF-1 subunits is sufficient for maintaining nucleolar chromosome and protein associations. Therefore, these data define novel functions for a separable domain of the p150 protein, regulating protein and DNA interactions at the nucleolus

    MYOD1 involvement in myopathy

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    [Excerpt] Introduction Myogenic Differentiation 1 (MYOD1) encodes a transcription factor that plays an important role in myogenic determination into mature skeletal muscle [1]. The first loss-of-function mutation of MYOD1 in humans was described in three siblings with perinatal lethal fetal akinesia [2].[...]We thank the individual and family. Funding was provided by The Fonds de recherche du Québec - Santé (FRQS) and Canadian Institutes of Health Research (CIHR) to P.M.C., Fundação para a Ciência e Tecnologia (FCT) with the fellowship SFRH/BD/84650/2010 to F.L. and Groupe Pasteur Mutualité Foundation (GPM Foundation) to M.M.info:eu-repo/semantics/publishedVersio

    994-99 Can Late Saphenous Vein Graft Closure Be Predicted by Quantitative Angiographic Analysis Before the Clinical Event?

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    Angiographic parameters predicting the likelihood of late occlusion of saphenous vein grafts (SVG) have been infrequently described. The Post-CABG Study, a 5-year trial aimed at reducing SVG closure in minimally symptomatic patients 1–11 years Post-CABG, offers a unique view into this event since this study requires an angiogram to document baseline graft patency. In this preliminary study we performed quantitative angiographic analysis (QAA Reiber) comparing the baseline Post-CABG study angiogram to an unscheduled “clinically driven” angiogram. Of 1253 enrolled patients with at least one patent SVG, 35 developed MI or unstable angina associated angiographically with a changed SVG lesion and either total or subtotal occlusion. Average patient age was 58±2 (SEM)years; 97% were male. Years since SVG placement to baseline angiogram averaged 6.5±0.4 (range 2–14). Time from the baseline to the unscheduled angiogram was 22±2 mo (range 3–47). In 28 patients the involved graft was single and in 7 sequential. The SVG insertion segments involved the LCX in 17, RCA in 15 and LAD in 10.ResultsThe initial lesion diameter at the site of the subsequent inciting lesion for all 35 patients averaged 2.58±0.17 mm, or 29.5±3.6% diam. stenosis. (This was defined as the most severe stenosis in any part of the graft in patients with subsequent total graft occlusion, and the exactly matched graft site in those with subtotal occlusion.) In 8 patients the baseline SVG was entirely normal. The initial lesion was >50% stenosis in only 4 patients. At the time of the clinical event, the lesion had progressed to 87±2.6% diam stenosis (N=35). In 16 patients the causal lesion was subtotal, while in 19 the SVG was totally occluded. The mean native vessel — responsible graft anastomotic diameter was 2.33±0.12mm.ConclusionQAA of SVG in asymptomatic patients may not predict subsequent graft closure associated with acute coronary syndromes. The initial site of the lesion is typically of mild-moderate severity, and only later exhibits rapid progression to occlusion
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