Concurrent Visual Feedback, Practice Organization, and Spatial Aiming Accuracy in Rapid Movement Sequences

Int J Exerc Sci 3(2) : 78-91, 2010. While the availability of visual feedback is a well-known factor influencing the accuracy of rapid aiming movements, little is known about how vision might interact with a contextual variable like practice organization. In the current study, the interaction of concurrent visual feedback (CVF) and practice organization on aiming movement accuracy was investigated in the dominant limb of 40 college-aged participants. Participants performed “triplets” of rapid aiming movements with a lightweight lever in the sagittal plane involving short (20°), medium (40°), long (60°) distances and were randomly assigned to one of four groups (n=10) in a 2 (Group: Blocked Practice, Random Practice) x 2 (Vision: CVF, no CVF) factorial design. Participants performed 24 triplets in acquisition and 10 triplets of a novel pattern (15°- 45°-15°) on transfer. Movement time was controlled by a metronome set at 1.43 cycles per second resulting in a cycle time of approximately 700 ms per movement. The constant error and overall error in distance were calculated for each distance and analyzed with separate 2 (Group) x 2 (Vision) x 3 (Movement) ANOVAs with repeated measures on the last factor. When CVF was available, contextual interference effects were shown by better accuracy for the blocked practice groups during acquisition compared to the random practice group. Without CVF, participants tended to overshoot the targets and contextual interference effects were minimized during acquisition and on the first transfer trial. Random practice resulted in better transfer performance compared to blocked practice for both vision conditions when all transfer trials were included in the analysis. The findings contributed to the current literature by demonstrating the importance of practice context and visual feedback to aiming accuracy

Do the Principles of Motor Program Editing Apply to Longer Sequences of Rapid Aiming Movements? Part I

Prior work had shown that performing a shorter distance aiming movement prior to a longer distance aiming movement resulted in overshooting of the short movement and undershooting of the longer movement compared to repetition of the same movement. The main question was whether the same interference effects would be found in a three-movement sequence. Right-handed (N = 24) participants (aged 18-22) produced a sequence of two or three bimanual rapid lever reversals combining short (20°) and long (60°) movements with an intermovement interval of 2.5 s beginning with either the dominant or nondominant hand. Participants overshot the short target and undershot the long target when short and long movements alternated compared to same distance control conditions, but the effects were greater for the nondominant hand. Overall, the experiment demonstrated that parameter value switching was a major source of spatial inaccuracy in sequential aiming movements

Defining the Focus of Attention: Effects of Attention on Perceived Exertion and Fatigue

This manuscript presents two experiments designed to explore the effects of attention on perceived exertion and time to failure in a fatiguing athletic task. There were two major motivating factors for these experiments. First, there are few studies evaluating attentional focus effects in endurance tasks and, second, there is a lack of integration between studies of attentional focus as external/internal (e.g., Wulf, 2007a) compared to associative/dissociative (e.g., Stevinson and Biddle, 1998). In Experiment 1, we used a fatiguing wall-sit posture (essentially a complex, isometric task) to compare two different types of external attention with an internal focus on the position of the legs. An external focus (regardless of type) increased the time taken to failure and reduced perceived exertion. In Experiment 2, we manipulated subjects’ expectancy of fatigue to test the interaction of attention and expectancy (both top-down factors) in this highly fatiguing task. Previous theories of attention during endurance tasks have suggested that as fatigue/pain increase, bottom-up factors begin to dominate subjects’ attention. While this may be true, Experiment 2 showed that even in a highly fatiguing task, attentional strategies, and expectancies affected the time to failure and perceived exertion

Individual Differences in the Programming of Rapid Bimanual Movements: Are Two Modes Better Than One?

International Journal of Exercise Science 9(3): 347-358, 2016. One of the challenges in performing simultaneous bimanual movements is to prevent interference from one limb to the other, thereby maintaining spatial accuracy in both limbs. Prior research has shown that when a longer distance movement is performed with a shorter movement, the shorter movement overshoots its target and the longer movement undershoots its target relative to control conditions where two shorter or two longer movements are made. The current experiment investigated the motor control strategies used by participants when performing simultaneous aiming movements combining both different and same distances. Participants (N = 20) made rapid lever-positioning movements (goal time to reversal was 350 ms) in the sagittal plane to 2 different spatial targets (20° and 60°) or the same targets (either 20° or 60°). Feedback about spatial accuracy was provided immediately after each trial. Constant error (CE) was measured for each distance based on 20 practice trials per condition. The CE from the same- and different-distance conditions were compared with separate one-way ANOVAs with repeated measures. Overshooting was shown of the 20° target and undershooting of the 60° target when the two distances were performed together. However, the movement amplitudes were positively correlated over trials in both the same- and different-distance conditions. A trial-by-trial analysis of the CE scores revealed both compensatory and non-compensatory strategies. The results suggest individual differences in how amplitude parameters are chosen for use with the generalized motor program in the control of bimanual aiming movements

Carbonyl sulfide and carbon disulfide: Large-scale distributions over the western Pacific and emissions from Asia during TRACE-P

An extensive set of carbonyl sulfide (OCS) and carbon disulfide (CS2) observations were made as part of the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) project, which took place in the early spring 2001. TRACE-P sampling focused on the western Pacific region but in total included the geographic region 110°E to 290°E longitude, 5°N to 50°N latitude, and 0–12 km altitude. Substantial OCS and CS2 enhancements were observed for a great many air masses of Chinese and Japanese origin during TRACE-P. Over the western Pacific, mean mixing ratios of long-lived OCS and shorter-lived CS2 showed a gradual decrease by about 10% and a factor of 5–10, respectively, from the surface to 8–10 km altitude, presumably because land-based sources dominated their distribution during February through April 2001. The highest mean OCS and CS2levels (580 and 20 pptv, respectively, based on 2.5° × 2.5° latitude bins) were observed below 2 km near the coast of Asia, at latitudes between 25°N and 35°N, where urban Asian outflow was strongest. Ratios of OCS versus CO for continental SE Asia were much lower compared to Chinese and Japanese signatures and were strongly associated with biomass burning/biofuel emissions. We present a new inventory of anthropogenic Asian emissions (including biomass burning) for OCS and CS2 and compare it to emission estimates based on regional relationships of OCS and CS2 to CO and CO2. The OCS and CS2 results for the two methods compare well for continental SE Asia and Japan plus Korea and also for Chinese CS2 emissions. However, it appears that the inventory underestimates Chinese emissions of OCS by about 30–100%. This difference may be related to the fact that we did not include natural sources such as wetland emissions in our inventory, although the contributions from such sources are believed to be at a seasonal low during the study period. Uncertainties in OCS emissions from Chinese coal burning, which are poorly characterized, likely contribute to the discrepancy

Functional Allocation with Airborne Self-Separation Evaluated in a Piloted Simulation

A human-in-the-loop simulation experiment was designed and conducted to evaluate an airborne self-separation concept. The activity supports the National Aeronautics and Space Administration s (NASA) research focus on function allocation for separation assurance. The objectives of the experiment were twofold: (1) use experiment design features in common with a companion study of ground-based automated separation assurance to promote comparability, and (2) assess agility of self-separation operations in managing trajectory-changing events in high traffic density, en-route operations with arrival time constraints. This paper describes the experiment and presents initial results associated with subjective workload ratings and group discussion feedback obtained from the experiment s commercial transport pilot participants

Prospective isolation and global gene expression analysis of definitive and visceral endoderm

AbstractIn spite of the therapeutic importance of endoderm derivatives such as the pancreas, liver, lung, and intestine, there are few molecular markers specific for early endoderm. In order to identify endoderm-specific genes as well as to define transcriptional differences between definitive and visceral endoderm, we performed microarray analysis on E8.25 definitive and visceral endoderm. We have developed an early endoderm gene expression signature, and clarified the transcriptional similarities and differences between definitive and visceral endoderm. Additionally, we have developed methods for flow cytometric isolation of definitive and visceral endoderm. These results shed light on the mechanism of endoderm formation and should facilitate investigation of endoderm formation from embryonic stem cells

Multilevel Interventions Targeting Obesity: Research Recommendations for Vulnerable Populations

The origins of obesity are complex and multifaceted. To be successful, an intervention aiming to prevent or treat obesity may need to address multiple layers of biological, social, and environmental influences

Research and Analysis of Fisheries in Illinois

Reports on progress and results for the following project objectives: sport fish population and sport fishing metrics; enhanced field sampling of sport fish populations; determination of factors affecting fishing quality; coordination with ongoing fisheries research projects; support for and enhance of web interface; fishes of Champaign County; recovery of urban stream sport fisheries.Illinois Department of Natural Resources, Division of Fisheries, Federal Aid Project F-69-R Segment 28unpublishednot peer reviewedOpe

Should patients with abnormal liver function tests in primary care be tested for chronic viral hepatitis: cost minimisation analysis based on a comprehensively tested cohort

Background Liver function tests (LFTs) are ordered in large numbers in primary care, and the Birmingham and Lambeth Liver Evaluation Testing Strategies (BALLETS) study was set up to assess their usefulness in patients with no pre-existing or self-evident liver disease. All patients were tested for chronic viral hepatitis thereby providing an opportunity to compare various strategies for detection of this serious treatable disease. Methods This study uses data from the BALLETS cohort to compare various testing strategies for viral hepatitis in patients who had received an abnormal LFT result. The aim was to inform a strategy for identification of patients with chronic viral hepatitis. We used a cost-minimisation analysis to define a base case and then calculated the incremental cost per case detected to inform a strategy that could guide testing for chronic viral hepatitis. Results Of the 1,236 study patients with an abnormal LFT, 13 had chronic viral hepatitis (nine hepatitis B and four hepatitis C). The strategy advocated by the current guidelines (repeating the LFT with a view to testing for specific disease if it remained abnormal) was less efficient (more expensive per case detected) than a simple policy of testing all patients for viral hepatitis without repeating LFTs. A more selective strategy of viral testing all patients for viral hepatitis if they were born in countries where viral hepatitis was prevalent provided high efficiency with little loss of sensitivity. A notably high alanine aminotransferase (ALT) level (greater than twice the upper limit of normal) on the initial ALT test had high predictive value, but was insensitive, missing half the cases of viral infection. Conclusions Based on this analysis and on widely accepted clinical principles, a "fast and frugal" heuristic was produced to guide general practitioners with respect to diagnosing cases of viral hepatitis in asymptomatic patients with abnormal LFTs. It recommends testing all patients where a clear clinical indication of infection is present (e.g. evidence of intravenous drug use), followed by testing all patients who originated from countries where viral hepatitis is prevalent, and finally testing those who have a notably raised ALT level (more than twice the upper limit of normal). Patients not picked up by this efficient algorithm had a risk of chronic viral hepatitis that is lower than the general population