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971.
Understanding mechanisms of fatigue of the trunk extensors is important because fatigue is a major factor in predicting incidence of low back pain, but few studies have examined trunk extensor fatigue muscles using differing load types and measured the amplitude and frequency domain of the electromyographic signal to explain these differences. Sixteen healthy participants performed position- and force-matching fatigue tasks in a modified Sørensen test position. Time to task failure was significantly longer during the position-matching task compared to force-matching task (58.3 ± 6.6 min vs. 36.1 ± 5.4 min). This finding is the opposite of that commonly reported for the appendicular muscle, but the mean power frequency shifts and muscle activation patterns of the trunk and hip extensors did not explain this difference. The mean power frequency shifts and muscle activation patterns of the trunk and hip extensors did not explain this difference. The greater time to task failure during the position-matching task may reflect adaptation of the trunk extensor muscles to optimize maintaining specific joint angles more so than specific loads. 相似文献
972.
《The International journal of psycho-analysis》2017,98(2):323-341
This paper focuses on the study of temporality used as a clinical pointer to processes of affect regulation in patients who express their suffering through a discourse driven by bodily allusions. Differences between symptoms revealed by body language that conveys an experience of conflict (psychoneurotic symptoms) and somatizations are reviewed. Somatization is examined as a benchmark for the failure to resolve states of tension. The body in the session is conceptualized as a speech event. The body is considered as a psychical construction organized in the exchanges with a fellow human‐being. It is thus established as a support for subjectivity. Two discourse registers are described: the discourse of the evoked body and the discourse of the perceived body. The study of Greek mythology allows us to distinguish two different types of temporality : Chronos and Kairos. Chronos represents chronological whereas Kairos subjective time. Both are present in the subject; but if greater mental disorganization supervenes, Chronos predominates as it paves the way for a defence against suffering, designed to avoid the unbearable meaning of ceasing to be. Adherence to one or other mode of temporality signals different conceptions of analytic work. The topics addressed are illustrated by various clinical vignettes . 相似文献
973.
Matthew C. Bell William M. Baum 《Journal of the experimental analysis of behavior》2017,108(3):367-397
Most studies of operant choice have focused on presenting subjects with a fixed pair of schedules across many experimental sessions. Using these methods, studies of concurrent variable‐ interval variable‐ratio schedules helped to evaluate theories of choice. More recently, a growing literature has focused on dynamic choice behavior. Those dynamic choice studies have analyzed behavior on a number of different time scales using concurrent variable‐interval schedules. Following the dynamic choice approach, the present experiment examined performance on concurrent variable‐interval variable‐ratio schedules in a rapidly changing environment. Our objectives were to compare performance on concurrent variable‐interval variable‐ratio schedules with extant data on concurrent variable‐interval variable‐interval schedules using a dynamic choice procedure and to extend earlier work on concurrent variable‐interval variable‐ratio schedules. We analyzed performances at different time scales, finding strong similarities between concurrent variable‐interval variable‐interval and concurrent variable‐interval variable‐ ratio performance within dynamic choice procedures. Time‐based measures revealed almost identical performance in the two procedures compared with response‐based measures, supporting the view that choice is best understood as time allocation. Performance at the smaller time scale of visits accorded with the tendency seen in earlier research toward developing a pattern of strong preference for and long visits to the richer alternative paired with brief “samples” at the leaner alternative (“fix and sample”). 相似文献
974.
Michael Perone Dean C. Williams Mark Galizio 《Journal of the experimental analysis of behavior》2017,107(1):1-8
Primates take longer to choose between alternatives with smaller differences in value. This effect—a particular instance of the distance effect in symbolic comparisons—has not been replicated in birds. Instead, birds appear to respond independently to each alternative, such that the latency to choose depends primarily on the alternative of highest value. Three experiments tested for the distance effect in pigeons under conditions not previously considered. Experiment 1 presented pigeons with forced‐ and binary free‐choice trials, where each alternative was one of three possible delays to reinforcement (4, 8, and 16 s). Pigeons were exposed to the choice stimuli for different amounts of time and with different sample response requirements prior to the choice response. Experiment 2 added a fourth (0‐s delay) alternative. Experiment 3 substituted the 16‐s delay with a second 4‐s delay. In all experiments, pigeons systematically chose the shortest delay to reinforcement. Latency to choose the 4‐s delay did not vary when choosing against the 8‐s or 16‐s delay, regardless of whether choice stimuli were exposed for the duration of nine pecks (Experiment 1), or whether a 0‐s delay alternative was sometimes present (Experiment 2). Latency to choose the preferred of two identical alternatives (4‐s vs. 4‐s) was shorter than the latency to choose between different alternatives (4‐s vs. 8‐s; Experiment 3); this is the opposite of a distance effect. These results show no evidence of a distance effect in pigeon choice, consistent with the hypothesis that pigeons respond independently to each choice alternative. 相似文献
975.
The total variance of a first-order autoregressive AR(1) time series is well known in time series literature. However, despite the increased use and interest in two-level AR(1) models, an equation for the total variance of these models does not exist. This paper presents an approximation of this total variance. It will be used to compute the unexplained and explained variance at each level of the model, the proportion of explained variance, and the intraclass correlation (ICC). The use of these variances and the ICC will be illustrated using an example concerning structured diary data about the positive affect of 96 married women. 相似文献
976.
Performer autonomy (or self-control) has consistently been shown to enhance motor learning, and it can also provide immediate benefits for motor performance. Autonomy is also a key variable in the OPTIMAL theory of motor learning (Wulf & Lewthwaite, 2016). It is assumed to contribute to enhanced expectancies and goal-action coupling, affecting performance effectiveness and efficiency. The purpose of the present study was to examine whether providing autonomy support by giving performers choices would enhance their ability to maintain maximum force levels. Participants were asked to repeatedly produce maximum forces using a hand dynamometer. After 2 initial trials with the dominant and non-dominant hand, stratified randomization was used to assign participants with the same average maximum force to one of two groups, choice or yoked control groups. Choice group participants were able to choose the order of hands (dominant, non-dominant) on the remaining trials (3 per hand). For control group participants, hand order was determined by choice-group counterparts. Maximum forces decreased significantly across trials in the control group, whereas choice group participants were able to maintain the maximum forces produced on the first trial. We interpret these findings as evidence that performer autonomy promotes movement efficiency. The results are in line with the view that autonomy facilitates the coupling of goals and actions (Wulf & Lewthwaite, 2016). 相似文献
977.
Skilled movement is mediated by motor commands executed with extremely fine temporal precision. The question of how the brain incorporates temporal information to perform motor actions has remained unanswered. This study investigated the effect of stimulus temporal predictability on response timing of speech and hand movement. Subjects performed a randomized vowel vocalization or button press task in two counterbalanced blocks in response to temporally-predictable and unpredictable visual cues. Results indicated that speech and hand reaction time was decreased for predictable compared with unpredictable stimuli. This finding suggests that a temporal predictive code is established to capture temporal dynamics of sensory cues in order to produce faster movements in responses to predictable stimuli. In addition, results revealed a main effect of modality, indicating faster hand movement compared with speech. We suggest that this effect is accounted for by the inherent complexity of speech production compared with hand movement. Lastly, we found that movement inhibition was faster than initiation for both hand and speech, suggesting that movement initiation requires a longer processing time to coordinate activities across multiple regions in the brain. These findings provide new insights into the mechanisms of temporal information processing during initiation and inhibition of speech and hand movement. 相似文献
978.
Andriy Gusak Tetiana Zaporozhets Jolanta Janczak-Rusch 《Philosophical Magazine Letters》2017,97(1):1-10
Two mechanisms of the Kirkendall voids pinning at the moving interface are discussed. Besides common Zener pinning, voids can be additionally, kinetically pinned to the interface by the additional vacancy concentration gradient, existing due to unideal vacancy sinks/sources at the interface and at the both sides of it. Kinetic pinning may explain the influence of copper substrate defect prehistory on the pinning behaviour. Capillary pinning is difficult to apply for the cases of voids enveloping by the growing phase. 相似文献
979.
By assessing the association strength with TRUE and FALSE, the autobiographical Implicit Association Test (aIAT) [Sartori, G., Agosta, S., Zogmaister, C., Ferrara, S. D., &; Castiello, U. (2008). How to accurately detect autobiographical events. Psychological Science, 19, 772–780. doi:10.1111/j.1467-9280.2008.02156.x] aims to determine which of two contrasting statements is true. To efficiently run well-powered aIAT experiments, we propose a web-based aIAT (web-aIAT). Experiment 1 (n?=?522) is a web-based replication study of the first published aIAT study [Sartori, G., Agosta, S., Zogmaister, C., Ferrara, S. D., &; Castiello, U. (2008). How to accurately detect autobiographical events. Psychological Science, 19, 772–780. doi:10.1111/j.1467-9280.2008.02156.x; Experiment 1]. We conclude that the replication was successful as the web-based aIAT could accurately detect which of two playing cards participants chose (AUC?=?.88; Hit rate?=?81%). In Experiment 2 (n?=?424), we investigated whether the use of affirmative versus negative sentences may partly explain the variability in aIAT accuracy findings. The aIAT could detect the chosen card when using affirmative (AUC?=?.90; Hit rate?=?81%), but not when using negative sentences (AUC?=?.60; Hit rate?=?53%). The web-based aIAT seems to be a valuable tool to facilitate aIAT research and may help to further identify moderators of the test’s accuracy. 相似文献
980.