7,914 research outputs found

    Word-level Symbolic Trajectory Evaluation

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    Symbolic trajectory evaluation (STE) is a model checking technique that has been successfully used to verify industrial designs. Existing implementations of STE, however, reason at the level of bits, allowing signals to take values in {0, 1, X}. This limits the amount of abstraction that can be achieved, and presents inherent limitations to scaling. The main contribution of this paper is to show how much more abstract lattices can be derived automatically from RTL descriptions, and how a model checker for the general theory of STE instantiated with such abstract lattices can be implemented in practice. This gives us the first practical word-level STE engine, called STEWord. Experiments on a set of designs similar to those used in industry show that STEWord scales better than word-level BMC and also bit-level STE.Comment: 19 pages, 3 figures, 2 tables, full version of paper in International Conference on Computer-Aided Verification (CAV) 201

    Presence of Spotters Improves Bench Press Performance: A Deception Study.

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    Sheridan, A, Marchant, DC, Williams, EL, Jones, HS, Hewitt, PA, and Sparks, SA. Presence of spotters improves bench press performance: a deception study. J Strength Cond Res XX(X): 000-000, 2017-Resistance exercise is a widely used method of physical training in both recreational exercise and athletic populations. The use of training partners and spotters during resistance exercise is widespread, but little is known about the effect of the presence of these individuals on exercise performance. The purpose of the current study was to investigate the effect of spotter presence on bench press performance. Twelve recreationally trained participants (age, 21.3 ± 0.8 years, height, 1.82 ± 0.1 m, and weight, 84.8 ± 11.1 kg) performed 2 trials of 3 sets to failure at 60% of 1 repetition maximum on separate occasions. The 2 trials consisted of spotters being explicitly present or hidden from view (deception). During the trials, total repetitions (reps), total weight lifted, ratings of perceived exertion (RPE), and self-efficacy were measured. Total reps and weight lifted were significantly greater with spotters (difference = 4.5 reps, t = 5.68, p < 0.001 and difference = 209.6 kg, t = 5.65, p < 0.001, respectively). Although RPE and local RPE were significantly elevated in the deception trials (difference = 0.78, f = 6.16, p = 0.030 and difference = 0.81, f = 5.89, p = 0.034, respectively), self-efficacy was significantly reduced (difference = 1.58, f = 26.90, p < 0.001). This study demonstrates that resistance exercise is improved by the presence of spotters, which is facilitated by reduced RPE and increased self-efficacy. This has important implications for athletes and clients, who should perform resistance exercise in the proximity of others, to maximize total work performed

    Competitor presence reduces internal attentional focus and improves 16.1km cycling time trial performance.

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    Objectives: Whilst the presence of a competitor has been found to improve performance, the mechanisms influencing the change in selected work rates during direct competition have been suggested but not specifically assessed. The aim was to investigate the physiological and psychological influences of a visual avatar competitor during a 16.1-km cycling time trial performance, using trained, competitive cyclists. Design: Randomised cross-over design. Methods: Fifteen male cyclists completed four 16.1 km cycling time trials on a cycle ergometer, performing two with a visual display of themselves as a simulated avatar (FAM and SELF), one with no visual display(DO), and one with themselves and an opponent as simulated avatars (COMP). Participants were informed the competitive avatar was a similar ability cyclist but it was actually a representation of their fastest previous performance. Results: Increased performance times were evident during COMP (27.8 ± 2.0 min) compared to SELF(28.7 ± 1.9 min) and DO (28.4 ± 2.3 min). Greater power output, speed and heart rate were apparent during COMP trial than SELF (p < 0.05) and DO (p ≤ 0.06). There were no differences between SELF and DO.Ratings of perceived exertion were unchanged across all conditions. Internal attentional focus was significantly reduced during COMP trial (p < 0.05), suggesting reduced focused on internal sensations during an increase in performance. Conclusions: Competitive cyclists performed significantly faster during a 16.1-km competitive trial than when performing maximally, without a competitor. The improvement in performance was elicited due to a greater external distraction, deterring perceived exertion

    Improvements in Cycling Time Trial Performance Are Not Sustained Following the Acute Provision of Challenging and Deceptive Feedback

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    The provision of performance-related feedback during exercise is acknowledged as an influential external cue used to inform pacing decisions. The provision of this feedback in a challenging or deceptive context allows research to explore how feedback can be used to improve performance and influence perceptual responses. However, the effects of deception on both acute and residual responses have yet to be explored, despite potential application for performance enhancement. Therefore, this study investigated the effects of challenging and deceptive feedback on perceptual responses and performance in self-paced cycling time trials (TT) and explored whether changes in performance are sustained in a subsequent TT following the disclosure of the deception. Seventeen trained male cyclists were assigned to either an accurate or deceptive feedback group and performed four 16.1 km cycling TTs; 1 and 2) ride-alone baseline TTs where a fastest baseline (FBL) performance was identified, 3) a TT against a virtual avatar representing 102% of their FBL performance (PACER), and 4) a subsequent ride-alone TT (SUB). The deception group, however, were initially informed that the avatar accurately represented their FBL, but prior to SUB were correctly informed of the nature of the avatar. Affect, self-efficacy and RPE were measured every quartile. Both groups performed PACER faster than FBL and SUB (p < 0.05) and experienced lower affect (p = 0.016), lower self-efficacy (p = 0.011), and higher RPE (p < 0.001) in PACER than FBL. No significant differences were found between FBL and SUB for any variable. The presence of the pacer rather than the manipulation of performance beliefs acutely facilitates TT performance and perceptual responses. Revealing that athletes’ performance beliefs were falsely negative due to deceptive feedback provision has no effect on subsequent perceptions or performance. A single experiential exposure may not be sufficient to produce meaningful changes in the performance beliefs of trained individuals beyond the acute setting

    Negative and positive selection of antigen-specific cytotoxic T lymphocytes affected by the α3 domain of MHC I molecules

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    THE α1 and α2 domains of major histocompatibility complex (MHC) class I molecules function in the binding and presentation of foreign peptides to the T-cell antigen receptor and control both negative and positive selection of the T-cell repertoire. Although the α3 domain of class I is not involved in peptide binding, it does interact with the T-cell accessory molecule, CDS. CDS is important in the selection of T cells as anti-CDS antibody injected into perinatal mice interfers with this process. We previously used a hybrid class I molecule with the α1/α2 domains from L^d and the α3 domain from Q7^b and showed that this molecule binds an L^d-restricted peptide but does not interact with CD8-dependent cytotoxic T lymphocytes. Expression of this molecule in transgenic mice fails to negatively select a subpopulation of anti-L^d cytotoxic T lymphocytes. In addition, positive selection of virus-specific L^d-restricted cytotoxic T lymphocytes does not occur. We conclude that besides the α1/α2 domains of class I, the α3 domain plays an important part in both positive and negative selection of antigen-specific cells

    Current Control Methods for an Asymmetrical Six-Phase Induction Motor Drive

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    Using the vector space decomposition approach, the currents in a multiphase machine with distributed winding can be decoupled into the flux and torque producing α-β components, and the loss-producing x-y and zero-sequence components. While the control of α-β currents is crucial for flux and torque regulation, control of x-y currents is important for machine/converter asymmetry and dead-time effect compensation. In this paper, an attempt is made to provide a physically meaningful insight into current control of a six-phase machine, by showing that the fictitious x-y currents can be physically interpreted as the circulating currents between the two three-phase windings. Using this interpretation, the characteristics of x-y currents due to the machine/converter asymmetry can be analyzed. The use of different types of x-y current controllers for asymmetry compensation and suppression of dead-time-induced harmonics is then discussed. Experimental results are provided throughout the paper, to underpin the theoretical considerations, using tests on a prototype asymmetrical six-phase induction machine. © 1986-2012 IEEE

    Postfault operation of an asymmetrical six-phase induction machine with single and two isolated neutral points

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    The paper presents a study of postfault control for an asymmetrical six-phase induction machine with single and two isolated neutral points, during single open-phase fault. Postfault control is based on the normal decoupling (Clarke) transformation, so that reconfiguration of the controller is minimized. Effect of the single open-phase fault on the machine equations under this control structure is discussed. Different modes of postfault operation are analyzed and are further compared in terms of the achievable torque and stator winding losses. Validity of the analysis is verified using experimental results obtained from a six-phase induction motor drive prototype. © 1986-2012 IEEE

    Knowledge sharing in infection prevention in routine and outbreak situations: a survey of the Society for Healthcare Epidemiology of America Research Network

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    Abstract In this cross-sectional Society for Healthcare Epidemiology of America Research Network survey on knowledge sharing in infection prevention we identified a rudimentary understanding of how to communicate and share knowledge within healthcare institutions. Our data support the need of further research in this important field
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