1,197 research outputs found
School physical activity intervention effect on adolescents' performance in mathematics
Purpose: The primary aim of this study was to test the effect of a school-based physical activity intervention on adolescentsâ performance in mathematics. A secondary aim was to explore potential mechanisms that might explain the intervention effect.
Methods: The Activity and Motivation in Physical EDucation intervention was evaluated using a two-arm cluster randomized controlled trial in 14 secondary schools located in low socioeconomic areas of Western Sydney, Australia. Study participants (n = 1173) were grade 8 students (mean age = 12.94 yr, SD = 0.54). The multicomponent intervention was designed to help teachers maximize studentsâ opportunities for moderate-to-vigorous physical activity (MVPA) during physical education (PE) and enhance studentsâ motivation toward PE. Mathematics performance was assessed as part of national testing in grade 7, which was the year before the trial began and then again in grade 9. Potential mediators were: (i) proportion of PE lesson time that students spent in MVPA and leisure time MVPA (%), measured using Actigraph GT3X+ accelerometers, and (ii) studentsâ self-reported engagement (behavioral, emotional, and cognitive) during mathematics lessons. Mediators were assessed at baseline (grade 8) and follow-up (grade 9, 14â15 months after baseline).
Results: The effect of the intervention on mathematics performance was small-to-medium (ÎČ = 0.16, P < 0.001). An intervention effect was observed for MVPA% in PE (ÎČ = 0.59, P < 0.001), but not for leisure time MVPA or any of the engagement mediators. There were no significant associations between changes in potential mediators and mathematics performance.
Conclusions: The Activity and Motivation in Physical EDucation intervention had a significant positive effect on mathematics performance in adolescents. However, findings should be interpreted with caution as the effect was small and not associated with changes in hypothesized mediators
Magnetic properties of submicron Co islands and their use as artificial pinning centers
We report on the magnetic properties of elongated submicron magnetic islands
and their influence on a superconducting film. The magnetic properties were
studied by magnetization hysteresis loop measurements and scanning-force
microscopy. In the as-grown state, the islands have a magnetic structure
consisting of two antiparallel domains. This stable domain configuration has
been directly visualized as a 2x2-checkerboard pattern by magnetic-force
microscopy. In the remanent state, after magnetic saturation along the easy
axis, all islands have a single-domain structure with the magnetic moment
oriented along the magnetizing field direction. Periodic lattices of these Co
islands act as efficient artificial pinning arrays for the flux lines in a
superconducting Pb film deposited on top of the Co islands. The influence of
the magnetic state of the dots on their pinning efficiency is investigated in
these films, before and after the Co dots are magnetized.Comment: 6 pages including figure
Investigating human audio-visual object perception with a combination of hypothesis-generating and hypothesis-testing fMRI analysis tools
Primate multisensory object perception involves distributed brain regions. To investigate the network character of these regions of the human brain, we applied data-driven group spatial independent component analysis (ICA) to a functional magnetic resonance imaging (fMRI) data set acquired during a passive audio-visual (AV) experiment with common object stimuli. We labeled three group-level independent component (IC) maps as auditory (A), visual (V), and AV, based on their spatial layouts and activation time courses. The overlap between these IC maps served as definition of a distributed network of multisensory candidate regions including superior temporal, ventral occipito-temporal, posterior parietal and prefrontal regions. During an independent second fMRI experiment, we explicitly tested their involvement in AV integration. Activations in nine out of these twelve regions met the max-criterion (A < AV > V) for multisensory integration. Comparison of this approach with a general linear model-based region-of-interest definition revealed its complementary value for multisensory neuroimaging. In conclusion, we estimated functional networks of uni- and multisensory functional connectivity from one dataset and validated their functional roles in an independent dataset. These findings demonstrate the particular value of ICA for multisensory neuroimaging research and using independent datasets to test hypotheses generated from a data-driven analysis
New Pulsating DB White Dwarf Stars from the Sloan Digital Sky Survey
We are searching for new He atmosphere white dwarf pulsators (DBVs) based on
the newly found white dwarf stars from the spectra obtained by the Sloan
Digital Sky Survey. DBVs pulsate at hotter temperature ranges than their better
known cousins, the H atmosphere white dwarf pulsators (DAVs or ZZ Ceti stars).
Since the evolution of white dwarf stars is characterized by cooling,
asteroseismological studies of DBVs give us opportunities to study white dwarf
structure at a different evolutionary stage than the DAVs. The hottest DBVs are
thought to have neutrino luminosities exceeding their photon luminosities
(Winget et al. 2004), a quantity measurable through asteroseismology.
Therefore, they can also be used to study neutrino physics in the stellar
interior. So far we have discovered nine new DBVs, doubling the number of
previously known DBVs. Here we report the new pulsators' lightcurves and power
spectra.Comment: 15 pages, 2 figures, 3 tables, ApJ accepte
Spatio-temporal dynamics and plastic flow of vortices in superconductors with periodic arrays of pinning sites
We present simulations of flux-gradient-driven superconducting rigid vortices
interacting with square and triangular arrays of columnar pinning sites in an
increasing external magnetic field. These simulations allow us to
quantitatively relate spatio-temporal microscopic information of the vortex
lattice with typically measured macroscopic quantities, such as the
magnetization . The flux lattice does not become completely commensurate
with the pinning sites throughout the sample at the magnetization matching
peaks, but forms a commensurate lattice in a region close to the edge of the
sample. Matching fields related to unstable vortex configurations do not
produce peaks in . We observe a variety of evolving complex flux
profiles, including flat terraces or plateaus separated by winding
current-carrying strings and, near the peaks in , plateaus only in
certain regions, which move through the sample as the field increases
Continental weathering and recovery from ocean nutrient stress during the Early Triassic Biotic Crisis
Following the latest Permian extinction âŒ252 million years ago, normal marine and terrestrial
ecosystems did not recover for another 5-9 million years. The driver(s) for the Early Triassic
biotic crisis, marked by high atmospheric CO2 concentration, extreme ocean warming, and
marine anoxia, remains unclear. Here we constrain the timing of authigenic K-bearing mineral
formation extracted from supergene weathering profiles of NW-Pangea by Argon geochronology,
to demonstrate that an accelerated hydrological cycle causing intense chemical
alteration of the continents occurred between âŒ254 and 248 Ma, and continued throughout
the Triassic period. We show that enhanced ocean nutrient supply from this intense continental
weathering did not trigger increased ocean productivity during the Early Triassic
biotic crisis, due to strong thermal ocean stratification off NW Pangea. Nitrogen isotope
constraints suggest, instead, that full recovery from ocean nutrient stress, despite some brief
amelioration âŒ1.5 million years after the latest Permian extinction, did not commence until
climate cooling revitalized the global upwelling systems and ocean mixing âŒ10 million years
after the mass extinction
Discriminatory Attitudes and Practices by Health Workers toward Patients with HIV/AIDS in Nigeria
BACKGROUND: Nigeria has an estimated 3.6 million people with HIV/AIDS and is home to one out of every 11 people with HIV/AIDS worldwide. This study is the first population-based assessment of discrimination against people living with HIV/AIDS in the health sector of a country. The purpose of this study was to characterize the nature and extent of discriminatory practices and attitudes in the health sector and indicate possible contributing factors and intervention strategies. The study involved a cross-sectional survey of 1,021 Nigerian health-care professionals (including 324 physicians, 541 nurses, and 133 midwives identified by profession) in 111 health-care facilities in four Nigerian states. METHODS AND FINDINGS: Fifty-four percent of the health-care professionals (550/1,021) were sampled from public tertiary care facilities. Nine percent of professionals reported refusing to care for an HIV/AIDS patient, and 9% indicated that they had refused an HIV/AIDS patient admission to a hospital. Fifty-nine percent agreed that people with HIV/AIDS should be on a separate ward, and 40% believed a person's HIV status could be determined by his or her appearance. Ninety-one percent agreed that staff and health-care professionals should be informed when a patient is HIV-positive so they can protect themselves. Forty percent believed that health-care professionals with HIV/AIDS should not be allowed to work in any area of health-care that requires patient contact. Twenty percent agreed that many with HIV/AIDS behaved immorally and deserve the disease. Basic materials needed for treatment and prevention of HIV were not adequately available. Twelve percent agreed that treatment of opportunistic infections in HIV/AIDS patients wastes resources, and 8% indicated that treating someone with HIV/AIDS is a waste of precious resources. Providers who reported working in facilities that did not always practice universal precautions were more likely to favor restrictive policies toward people with HIV/AIDS. Providers who reported less adequate training in HIV treatment and ethics were also more likely to report negative attitudes toward patients with HIV/AIDS. There was no consistent pattern of differences in negative attitudes and practices across the different health specialties surveyed. CONCLUSION: While most health-care professionals surveyed reported being in compliance with their ethical obligations despite the lack of resources, discriminatory behavior and attitudes toward patients with HIV/AIDS exist among a significant proportion of health-care professionals in the surveyed states. Inadequate education about HIV/AIDS and a lack of protective and treatment materials appear to contribute to these practices and attitudes
Social Interactions vs Revisions, What is important for Promotion in Wikipedia?
In epistemic community, people are said to be selected on their knowledge
contribution to the project (articles, codes, etc.) However, the socialization
process is an important factor for inclusion, sustainability as a contributor,
and promotion. Finally, what does matter to be promoted? being a good
contributor? being a good animator? knowing the boss? We explore this question
looking at the process of election for administrator in the English Wikipedia
community. We modeled the candidates according to their revisions and/or social
attributes. These attributes are used to construct a predictive model of
promotion success, based on the candidates's past behavior, computed thanks to
a random forest algorithm.
Our model combining knowledge contribution variables and social networking
variables successfully explain 78% of the results which is better than the
former models. It also helps to refine the criterion for election. If the
number of knowledge contributions is the most important element, social
interactions come close second to explain the election. But being connected
with the future peers (the admins) can make the difference between success and
failure, making this epistemic community a very social community too
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