Practice makes efficient: Effects of golf practice on brain activity

This study employed a test-retest design to examine changes in brain activity associated with practice of a motor skill. We recorded EEG activity from twelve right-handed recreational golfers (mean handicap: 23) as they putted 50 balls to a 2.4m distant hole, before and after a 3-day practice. We measured changes in putting performance, conscious processing, and regional EEG alpha activity. Putting performance improved and conscious processing decreased after practice. Mediation analyses revealed that performance improvements were associated with changes in EEG alpha, whereby activity in task-irrelevant cortical regions (temporal regions) was inhibited and functionally isolated from activity in task-relevant regions (central regions). These findings provide evidence for the development of greater neurophysiological efficiency with practice of a motor skill

Characterization of the Noise in Secondary Ion Mass Spectrometry Depth Profiles

The noise in the depth profiles of secondary ion mass spectrometry (SIMS) is studied using different samples under various experimental conditions. Despite the noise contributions from various parts of the dynamic SIMS process, its overall character agrees very well with the Poissonian rather than the Gaussian distribution in all circumstances. The Poissonian relation between the measured mean-square error (MSE) and mean can be used to describe our data in the range of four orders. The departure from this relation at high counts is analyzed and found to be due to the saturation of the channeltron used. Once saturated, the detector was found to exhibit hysteresis between rising and falling input flux and output counts.Comment: 14 pages, 4 postscript figures, to appear on J. Appl. Phy

Eye quietness and quiet eye in expert and novice golf performance: an electrooculographic analysis

Quiet eye (QE) is the final ocular fixation on the target of an action (e.g., the ball in golf putting). Camerabased eye-tracking studies have consistently found longer QE durations in experts than novices; however, mechanisms underlying QE are not known. To offer a new perspective we examined the feasibility of measuring the QE using electrooculography (EOG) and developed an index to assess ocular activity across time: eye quietness (EQ). Ten expert and ten novice golfers putted 60 balls to a 2.4 m distant hole. Horizontal EOG (2ms resolution) was recorded from two electrodes placed on the outer sides of the eyes. QE duration was measured using a EOG voltage threshold and comprised the sum of the pre-movement and post-movement initiation components. EQ was computed as the standard deviation of the EOG in 0.5 s bins from –4 to +2 s, relative to backswing initiation: lower values indicate less movement of the eyes, hence greater quietness. Finally, we measured club-ball address and swing durations. T-tests showed that total QE did not differ between groups (p = .31); however, experts had marginally shorter pre-movement QE (p = .08) and longer post-movement QE (p < .001) than novices. A group × time ANOVA revealed that experts had less EQ before backswing initiation and greater EQ after backswing initiation (p = .002). QE durations were inversely correlated with EQ from –1.5 to 1 s (rs = –.48 - –.90, ps = .03 - .001). Experts had longer swing durations than novices (p = .01) and, importantly, swing durations correlated positively with post-movement QE (r = .52, p = .02) and negatively with EQ from 0.5 to 1s (r = –.63, p = .003). This study demonstrates the feasibility of measuring ocular activity using EOG and validates EQ as an index of ocular activity. Its findings challenge the dominant perspective on QE and provide new evidence that expert-novice differences in ocular activity may reflect differences in the kinematics of how experts and novices execute skills

The Assuan Papyri

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Spacecraft-plasma interaction codes: NASCAP/GEO, NASCAP/LEO, POLAR, DynaPAC, and EPSAT

Development of a computer code to simulate interactions between the surfaces of a geometrically complex spacecraft and the space plasma environment involves: (1) defining the relevant physical phenomena and formulating them in appropriate levels of approximation; (2) defining a representation for the 3-D space external to the spacecraft and a means for defining the spacecraft surface geometry and embedding it in the surrounding space; (3) packaging the code so that it is easy and practical to use, interpret, and present the results; and (4) validating the code by continual comparison with theoretical models, ground test data, and spaceflight experiments. The physical content, geometrical capabilities, and application of five S-CUBED developed spacecraft plasma interaction codes are discussed. The NASA Charging Analyzer Program/geosynchronous earth orbit (NASCAP/GEO) is used to illustrate the role of electrostatic barrier formation in daylight spacecraft charging. NASCAP/low Earth orbit (LEO) applications to the CHARGE-2 and Space Power Experiment Aboard Rockets (SPEAR)-1 rocket payloads are shown. DynaPAC application to the SPEAR-2 rocket payloads is described. Environment Power System Analysis Tool (EPSAT) is illustrated by application to Tethered Satellite System 1 (TSS-1), SPEAR-3, and Sundance. A detailed description and application of the Potentials of Large Objects in the Auroral Region (POLAR) Code are presented

On classification of Poisson vertex algebras

We describe a conjectural classification of Poisson vertex algebras of CFT type and of Poisson vertex algebras in one differential variable (= scalar Hamiltonian operators)

Quiet eye and eye quietness: Electrooculographic methods to study ocular activity during motor skills

Camera-based eye tracking research has revealed that experts make longer fixations on the target of an action (e.g., the ball in golf putting) prior to and following movement onset, compared to novices. Yet it is not clear how ocular activity affects motor performance. It is possible that the limited temporal resolution of camera systems has held back progress on this issue. We analysed horizontal EOG (512 Hz, 0.1-30 Hz filtered) from ten expert and ten novice golfers as they putted 60 balls to a 2.4 m distant hole. We used multiple voltage thresholds to measure the duration of the final fixation (quiet eye; QE) with its pre- and post-movement onset components. We also measured ocular activity across time as the standard deviation of the EOG in 0.5 s bins, –4 to +2 s from movement onset (eye quietness; EQ): lower values correspond with greater quietness. Finally, we measured ball address and club swing durations using infrared and sound sensors. Total QE duration did not differ between groups. However, experts had shorter pre-movement QE and longer post-movement QE than novices. Experts had less EQ before movement onset and greater EQ after movement onset. EQ was inversely correlated with QE duration, concurrently validating EQ as an index of ocular activity. Experts had longer swing durations than novices. Swing duration correlated positively with post-movement QE and negatively with post-movement EQ. Our findings provide new evidence that expert-novice differences in ocular activity may reflect differences in the kinematics of how experts and novices execute motor skills

Conscious processing and cortico-cortical functional connectivity in golf putting

The Theory of Reinvestment argues that automated motor processes are disrupted when task-related declarative knowledge is used to control movement execution. Electroencephalographic (EEG) based high-alpha band (10-12 Hz) connectivity between the left temporal (verbal/analytic processing) area and the frontal (motor planning) area has been endorsed as a neurophysiological marker of the propensity for conscious processing of declarative knowledge during movement preparation. Our study investigated the utility of left temporal to frontal connectivity in characterizing optimal golf putting performance. Ten expert and ten novice right-handed male golfers putted 120 golf balls on a flat mat to a 2.4 m distant hole while the EEG was continuously recorded. Conscious processing was assessed by a putting-specific reinvestment scale. Functional connectivity in preparation to golf putts was computed as high-alpha inter site phase clustering (ISPC), and analyzed as a function of expertise (expert, novice), performance outcome (holed, missed) and psychological pressure (low, high). We found that left (but not right) temporal-frontal ISPC was lower in experts compared to novices (M experts = .39; M novices = .48). The experts also reported lower conscious processing compared to the novices (M experts = 2.80; M novices = 3.50). Furthermore, left temporal-frontal ISPC was higher in missed versus holed putts for experts (M holed= .37; M misses = .41) and novices (M holed = .44; M misses = .51). No pressure effect was revealed (M low = .42; M high = .45). Our findings suggest that experts engage in less conscious processing compared to novices, and, in line with the Theory of Reinvestment, suggest that errors in motor performance can be prompted by excessive conscious verbal/analytic interference with movement preparation and execution. Our study findings suggest that diminished communication between the left temporal (verbal/analytic) and the frontal (pre-motor) cortical areas during movement preparation and execution is a feature of skilled motor performance. This knowledge can now be used to design connectivity-based neurofeedback training protocols to expedite motor learning and improve motor skills

Suppression of left temporal cortical activity mediates improvements in golf putting: A neural signature of expertise in precision sports?

Background and Purpose. The study of electroencephalographic (EEG) activity in precision sports has revealed that oscillatory activity within the upper-alpha frequency (10-12 Hz) recorded in the last seconds preceding skill execution can distinguish experts from novices. The power of these oscillations provides an index of neuronal suppression by a thalamic mechanism that gates resources to task-related and away from task-unrelated cortical areas. Our study employed a test-retest training paradigm to examine changes in cortical alpha activity and performance. Method. Twelve right-handed experienced golfers (age: M = 21) underwent three 1-hour putting training sessions, sandwiched between a test and retest session, during which they putted 50 balls to a standard hole at a distance of 2.4 m. Outcome (number of holed putts) and performance (radial, angle, and length errors) measures were recorded in both sessions. EEG upper-alpha power was measured from 32 scalp electrodes before (-3 s) and after (+1 s) initiation of the backswing. Results. The change in outcome and performance measures indicated that participants improved across sessions (e.g., holed putts: 12.17 during test, 16.25 during retest, P = .05). Among the performance measures, angle error was the best correlate of putting outcome during both test (r = -0.92, P < .001) and retest (r = -0.89, P < .001). The improvement in performance across sessions was fully mediated by the reduction of angle (P = .008) and radial (P = .06), but not length error. A topographical analysis of the EEG revealed that upper-alpha power was lowest in central areas and highest in temporal-occipital areas (P < .001). The improvements in putting outcome (P = .02) and angle error (P = .03) across sessions were partially mediated by higher power in the left temporal area in the last second preceding backswing initiation. Conclusion. The present findings confirm that improvements in putting outcome are largely attributable to decreases in putter head angle at impact. The topographical pattern displayed by preparatory upper-alpha power is consistent with the gating of resources to central sensorimotor areas and away from temporal and occipital areas. Importantly, increased inhibition of cognitive (e.g., language) processes performed in the left temporal cortex partially accounted for improved putting outcome and performance. Finally, data on self-reported measures (e.g., conscious processing) as well as limitations and further directions will be presented and discussed in relation to alpha gating