5,191 research outputs found
Learning physics in context: a study of student learning about electricity and magnetism
This paper re-centres the discussion of student learning in physics to focus
on context. In order to do so, a theoretically-motivated understanding of
context is developed. Given a well-defined notion of context, data from a novel
university class in electricity and magnetism are analyzed to demonstrate the
central and inextricable role of context in student learning. This work sits
within a broader effort to create and analyze environments which support
student learning in the sciencesComment: 36 pages, 4 Figure
Effects of Age and Gender on Physical Performance
Our purpose was to examine the effects of age and gender on physical performance. We assessed a one-hour swimming performance and participation of 4,271 presumably healthy men and women, aged 19–91 years, from the 2001–2003 United States Masters Swimming long-distance (1 h) national competition. The decline in performance with increasing age was found to be quadratic rather than linear. The equation which best fit variation in 1 h swimming distance in meters (m) according to variations in age in years (y) in men was: distance (m) = 4058 + 2.18 age−0.29 age (http://www.acsmmsse.org/pt/re/msse/positionstandards.htm;jsessionid=DiRVACC7YS3mq27s5kV3vwpEVSokmmD1ZJLC7pdnol3KcfoSu0t!1096311956!-949856145!9001!-1), with the same equation for women except that 380 m needed to be subtracted from the calculated value at all ages (about a 10% difference). There was a large overlap in performance between men and women. The overall mean decline in performance with age was about 50% and was parallel in men and women. The mean difference in distance for a 1-year increment in age was −9.7 m at 21 y of age, −21.3 m at 40 y, and −44.5 m at 80 y. Far greater declines of about 96% in numbers participating with advanced age (80 y and over, 4% of peak numbers) were observed than in the 40–49 y age group. In conclusion, the declines in performance were parallel in men and women at all ages, and the 1-year age-related declines in performance were about twice as great at 40 y and more than four-times as great at 80 y than at 20 y of age, with even greater age-related declines in participation being noted for both men and women
Validation of gyrokinetic modelling of light impurity transport including rotation in ASDEX Upgrade
Upgraded spectroscopic hardware and an improved impurity concentration
calculation allow accurate determination of boron density in the ASDEX Upgrade
tokamak. A database of boron measurements is compared to quasilinear and
nonlinear gyrokinetic simulations including Coriolis and centrifugal rotational
effects over a range of H-mode plasma regimes. The peaking of the measured
boron profiles shows a strong anti-correlation with the plasma rotation
gradient, via a relationship explained and reproduced by the theory. It is
demonstrated that the rotodiffusive impurity flux driven by the rotation
gradient is required for the modelling to reproduce the hollow boron profiles
at higher rotation gradients. The nonlinear simulations validate the
quasilinear approach, and, with the addition of perpendicular flow shear,
demonstrate that each symmetry breaking mechanism that causes momentum
transport also couples to rotodiffusion. At lower rotation gradients, the
parallel compressive convection is required to match the most peaked boron
profiles. The sensitivities of both datasets to possible errors is
investigated, and quantitative agreement is found within the estimated
uncertainties. The approach used can be considered a template for mitigating
uncertainty in quantitative comparisons between simulation and experiment.Comment: 19 pages, 11 figures, accepted in Nuclear Fusio
Rural-to-Urban Migration: Socioeconomic Status But Not Acculturation was Associated with Overweight/Obesity Risk.
To investigate whether socioeconomic status (SES) and acculturation predict overweight/obesity risk as well as the mediating effect of physical activity (PA) in the context of internal migration. Cross-sectional study of 587 rural-to-urban migrants participating in the PERU MIGRANT study. Analyses were conducted using logistic regression and structured equation modeling. Interaction effects of SES and acculturation were tested. Models were controlled for age, gender and education. Only SES was a significant predictor of overweight/obesity risk. Lower SES decreased the odds of being overweight/obese by 51.4 %. This association did not vary by gender nor was it explained by PA. Mechanisms underlying the relationship between SES and overweight/obesity may differ depending on the geographic location and sociocultural context of the population studied. Research on internal migration and health would benefit from the development of tailored acculturation measures and the evaluation of exploratory models that include diet
Quaiselastic scattering from relativistic bound nucleons: Transverse-Longitudinal response
Predictions for electron induced proton knockout from the and
shells in O are presented using various approximations for the
relativistic nucleonic current. Results for the differential cross section,
transverse-longitudinal response () and left-right asymmetry
are compared at (GeV/c) corresponding to TJNAF experiment
89-003. We show that there are important dynamical and kinematical relativistic
effects which can be tested by experiment.Comment: 10 pages, including 2 figures. Removed preliminary experimental data
from the figure
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