5,303 research outputs found
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
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
Transitional Lu and Spherical Ta Ground-State Proton Emitters in the Relativistic Hartree-Bogoliubov model
Properties of transitional Lu and spherical Ta ground-state proton emitters
are calculated with the Relativistic Hartree Bogoliubov (RHB) model. The NL3
effective interaction is used in the mean-field Lagrangian, and pairing
correlations are described by the pairing part of the finite range Gogny
interaction D1S. Proton separation energies, ground-state quadrupole
deformations, single-particle orbitals occupied by the odd valence proton, and
the corresponding spectroscopic factors are compared with recent experimental
data, and with results of the macroscopic-microscopic mass model.Comment: 11 pages RevTex, 3 p.s figures, Submitted to Phys. Rev.
Accuracy of BCS-based approximations for pairing in small Fermi systems
We analyze the accuracy of BCS-based approximations for calculating
correlation energies and odd-even energy differences in 2-component fermionic
systems with a small number of pairs. The analysis is focused on comparing BCS
and projected BCS treatments with the exact solution of the pairing
Hamiltonian, considering parameter ranges appropriate for nuclear pairing
energies. We find that the projected BCS is quite accurate over the entire
range of coupling strengths in spaces of up to about 20 doubly degenerate
orbitals. It is also quite accurate for two cases we considered with a more
realistic Hamiltonian, representing the nuclei around 117Sn and 207Pb. However,
the projected BCS significantly underestimates the energies for much larger
spaces when the pairing is weak.Comment: 10 pages; 14 figure
Application of the gradient method to Hartree-Fock-Bogoliubov theory
A computer code is presented for solving the equations of
Hartree-Fock-Bogoliubov (HFB) theory by the gradient method, motivated by the
need for efficient and robust codes to calculate the configurations required by
extensions of HFB such as the generator coordinate method. The code is
organized with a separation between the parts that are specific to the details
of the Hamiltonian and the parts that are generic to the gradient method. This
permits total flexibility in choosing the symmetries to be imposed on the HFB
solutions. The code solves for both even and odd particle number ground states,
the choice determined by the input data stream. Application is made to the
nuclei in the -shell using the USDB shell-model Hamiltonian.Comment: 20 pages, 5 figures, 3 table
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