Trial-by-trial analysis or averaging: implications for electromyographic models of rapid limb control

The control of human limb movement has been the focus of research for more than a century. A major issue to emerge from this work is the manner in which the central nervous system regulates electromyographic (EMG) activity to produce movements that differ in distance, velocity, and movement time. However the different methods of analysis often used to analyze EMG data could result in different kinematic-EMG relationships. In this study, participants performed an elbow flexion task to one of five distance goals (between 5 degrees and 50 degrees) using three movement speeds. EMG data from the right elbow flexors were compared using a trial-by-trial analysis and one based on averaged data. Averaging across trials underestimated biceps EMG amplitude at all movement distances and speeds compared to a trial-by-trial analysis. Averaging overestimated EMG burst duration compared to the trial-by-trial analysis. Peak agonist EMG amplitude was positively related to distance and inversely related to movement time. Agonist EMG duration was constant for movement distances less than 30 degrees but increased in the 50 degrees condition. The results support the view that peak EMG amplitude and duration can be controlled independently, but EMG duration changes only for longer distance movements when additional force is required.     

Computerized Agility Training Improves Change-of-Direction and Balance Performance Independently of Footwear in Young Adults

Understanding the effects of training in different footwear on sporting performance would be useful to coaches and athletes. Purpose: This study compared the effects of computerized agility training using 3 types of footwear on change-of-direction and balance performance in young adults. Method: Thirty recreationally active young adults (M_age = 22.8 ± 3.1 years; M_height = 1.71 ± 0.7 m; M_bodymass = 73.4 ± 10.3 kg) were randomly assigned to a 6-week computerized agility training intervention in 1 of 3 footwear groups (n = 10/group): barefoot, minimal footwear, or traditional shoes. Participants had no previous barefoot or minimal-footwear training experience. Dependent variables included change-of-direction test time to completion, Star Excursion Balance Test, and single-leg stability evaluation. Testing was performed at the start of the training program, after 2 weeks, after 4 weeks, and at the end of the training program. Results: No group or time interactions were found for any of the dependent variables. Time main effects were observed for the performance measures of change of direction, Star Excursion, and single-leg-with-eyes-open stability evaluation. Participants improved in all 3 tests as early as 2 weeks into the intervention, with improvements continuing through the entire 6-week intervention. Conclusions: The lack of interaction and footwear effects suggests that agility and balance improvements during foot agility training are independent of footwear in a recreationally active young-adult population. Computerized agility training improves change-of-direction and balance performance within 2 weeks of training implementation. Future studies should consider footwear training effects in different populations, including frail older adults and athletes.     

Microbial dark matter coming to light: challenges and opportunities

Microbes are the most abundant and diverse cellular life forms on Earth and colonize a wide range of environmental niches.However,more than 99％of bac-terial and...     

Employing teachers' ratings in selection of achievement tests in reading and mathematics with a behaviorally disturbed population

The usefulness of a particular standardized achievement test with a specific population may be determined largely on the basis of experience. Sixty-six behaviourally disturbed students were administered portions of a test battery including the Reading Recognition subtest of the Peabody Individual Achievement Test (PIAT), PIAT Reading Comprehension, the Reading subtest of the Wide Range Achievement Test (WRAT), and Stanford Diagnostic Reading Test (SDRT); PIAT Mathematics, WRAT Arithmetic, Stanford Diagnostic Mathematics Test (SDMT), and KeyMath Diagnostic Arithmetic Test. Toward the end of the academic year, teachers estimated students' grade levels in reading and mathematics. Results indicated that, in mathematics, the SDMT and the PIAT predicted teachers' ratings equally well and better than the other tests; in reading, all tests predicted teachers' ratings equally well except for the PIAT Reading Comprehension, which performed less well than others. Explanations for these results are offered, together with suggestions for identifying achievement tests suitable to specific populations.     

The Choice of Response Probability in Bookmark Standard Setting: An Experimental Study

Evidence of the internal consistency of standard-setting judgments is a critical part of the validity argument for tests used to make classification decisions. The bookmark standard-setting procedure is a popular approach to establishing performance standards, but there is relatively little research that reflects on the internal consistency of the resulting judgments. This article presents the results of an experiment in which content experts were randomly assigned to one of two response probability conditions: .67 and .80. If the standard-setting judgments collected with the bookmark procedure are internally consistent, both conditions should produce highly similar cut scores. The results showed substantially different cut scores for the two conditions; this calls into question whether content experts can produce the type of internally consistent judgments that are required using the bookmark procedure.     

Automatic detection of collisions in elite level rugby union using a wearable sensing device

Elite rugby union teams currently employ the latest technology to monitor and evaluate the physical demands of training and games on their players. Tackling has been shown to be the most common cause of injury in rugby union, yet current player monitoring technology does not effectively evaluate player tackling measurements. Currently, to evaluate measurements specific to player tackles, a time-consuming manual analysis of player sensor data and video footage is required. The purpose of this work is to investigate tackle modeling techniques which can be utilised to automatically detect player tackles and collisions using sensing technology already being used by elite international and club level rugby union teams. This paper discusses issues relevant to automatic tackle analysis, describes a technique to detect tackles using sensing data and validates the technique by comparing automatically detected collisions to manually labeled collisions using data from elite club and international level players. The results of the validation show that the system is able to consistently identify collisions with very few false positives and false negatives, achieving a recall and precision rating of 0.933 and 0.958, respectively. The aim is that the automatically detected tackles can provide coaching, medical and strength and conditioning staff with objective tackle-specific measurements, in real time, which can be used in injury prevention and rehabilitation strategies.     

Reception Studies in the Rhetoric of Science

This article encourages the increased attention to issues of reception in rhetoric of science, according with the sentiment but not the argument of Paul, Charney, and Kendall's “Moving beyond the Moment.” In particular, it offers two works as exemplary of the disciplinary maturity that has occasioned this focus on reception, Ceccarelli's monograph, Shaping Science with Rhetoric, and Harris's collection, Rhetoric and Incommensurability.