175 research outputs found
Impact of a Brief Workshop on Stages of Change Profiles in Athletes
This report examines the impact of a psychoeducational workshop on athletes’ stages of change for use of mental skills training. Fourteen teams participated in a sport psychology workshop including seven women’s teams (n = 124) and seven men’s teams (n = 96). Teams were assessed on decisional balance (pros and cons) and stages of change variables before and after the workshop. As hypothesized, athletes reported significantly higher pros and contemplation scores after the workshop, with corresponding decreases in cons and precontemplation scores. Moderate effect sizes (.35 - .68) supported a positive impact of the workshop on athletes’ perceptions of mental training, but data were not collected on how long these effects may last. The results also suggest that research should explore more efficient methods for stage assignment for athletes to maximize intervention effectiveness
Desarrollo de una práctica de laboratorio OPC
OPC es un protocolo que le permite a las empresas y a las personas que manejan
procesos de automatización poder trabajar con equipos y sistemas de diferentes
fabricantes, haciendo que estos trabajen como una única red de automatización.
Las empresas y personas que adquieren este protocolo se benefician al poder
integrar características importantes de uno y otro fabricante lo cual ofrece como
resultado un proceso de óptima calidad.
Además gracias a este protocolo las empresas desarrolladoras de equipos
industriales están en condiciones de proveer instrumentos de mejor calidad, por
que le dedican mas tiempo y esfuerzo a las características del hardware y
software propios del equipo y no pierden el tiempo en desarrollar un driver
diferente para cada equipo.Incluye bibliografí
X-ray flares, neutrino cooled disks, and the dynamics of late accretion in GRB engines
We compute the average luminosity of X-ray flares as a function of time, for
a sample of 10 long-duration gamma-ray burst afterglows. The mean luminosity,
averaged over a timescale longer than the duration of the individual flares,
declines as a power-law in time with index ~-1.5. We elaborate on the
properties of the central engine that can produce such a decline. Assuming that
the engine is an accreting compact object, and for a standard conversion factor
between accretion rate and jet luminosity, the switch between a neutrino-cooled
thin disk and a non-cooled thick disk takes place at the transition from the
prompt to the flaring phase. We discuss the implications of this coincidence
under different scenarios for the powering of the GRB outflow. We also show
that the interaction of the outflow with the envelope of the progenitor star
cannot produce flares out of a continuous relativistic flow, and conclude that
it is the dynamics of the disk or the jet-launching mechanism that generates an
intrinsically unsteady outflow on timescales much longer than the dynamical
timescale of the system. This is consistent with the fact that X-ray flares are
observed in short-duration GRBs as well as in long-duration ones.Comment: 5 pages, MNRAS in pres
On the evolution of anomalous X-ray pulsars and soft gamma ray repeaters with fallback disks
We show that the period clustering of anomalous X-ray pulsars (AXPs) and soft
gamma-ray repeaters (SGRs), their X-ray luminosities, ages and statistics can
be explained with fallback disks with large initial specific angular momentum.
The disk evolution models are developed by comparison to self-similar
analytical models. The initial disk mass and angular momentum set the viscous
timescale. An efficient torque, with (1 - w^2) dependence on the fastness
parameter w leads to period clustering in the observed AXP-SGR period range
under a wide range of initial conditions. The timescale t_0 for the early
evolution of the fallback disk, and the final stages of fallback disk
evolution, when the disk becomes passive, are the crucial determinants of the
evolution. The disk becomes passive at temperatures around 100 K, which
provides a natural cutoff for the X-ray luminosity and defines the end of
evolution in the observable AXP and SGR phase. This low value for the minimum
temperature for active disk turbulence indicates that the fallback disks are
active up to a large radius greater than ~10^{12} cm. We find that transient
AXPs and SGRs are likely to be older than their persistent cousins. A fallback
disk with mass transfer rates corresponding to the low quiescent X-ray
luminosities of the transient sources in early evolutionary phases would have a
relatively lower initial mass, such that the mass-flow rate in the disk is not
sufficient for the inner disk to penetrate into the light cylinder of the young
neutron star, making mass accretion onto the neutron star impossible. The
transient AXP phase therefore must start later. The model results imply that
the transient AXP/SGRs, although older, are likely to be similar in number to
persistent sources (abridged).Comment: 42 pages, 22 figures. Accepted for publication in the Astrophysical
Journa
Cross-sectional examination of physical and social contexts of episodes of eating and drinking in a national sample of US adults
OBJECTIVE: The current study characterizes associations between physical and social contexts of self-reported primary episodes of eating/drinking and sociodemographic and obesity-related variables in US adults.
DESIGN: Multinomial logistic regression was used to analyse a nationally representative sample of adults from the 2006-2008 American Time Use Survey. Models identifying physical (where) and social (whom) contexts of primary eating/drinking episodes at the population level, controlling for demographic characteristics, weight status and time of eating, were conducted.
SETTING USA SUBJECTS: A nationally representative sample of US adults (n 21 315).
RESULTS: Eating/drinking with immediate family was positively associated with age (OR = 1·15 (95 % CI 1·04, 1·27) to 1·23 (95 % CI 1·09, 1·39)), education level (OR = 1·16 (95 % CI 1·03, 1·30) to 1·36 (95 % CI 1·21, 1·54)), obesity (OR = 1·13 (95 % CI 1·04, 1·22)), children in the household (OR = 3·39 (95 % CI 3·14, 3·66)) and time of day (OR = 1·70 (95 % CI 1·39, 2·07) to 5·73 (95 % CI 4·70, 6·99)). Eating in the workplace was negatively associated with female gender (OR = 0·65 (95 % CI 0·60, 0·70)) and children in the household (OR = 0·90 (95 % CI 0·83, 0·98)), while positively associated with non-white status (OR = 1·14 (95 % CI 1·01, 1·29) to 1·47 (95 % CI 1·32, 1·65)) and time of day (OR = 0·25 (95 % CI 0·28, 0·30) to 5·65 (95 % CI 4·66, 6·85)). Women (OR = 0·80 (95 % CI 0·74, 0·86)), those aged >34 years (OR = 0·48 (95 % CI 0·43, 0·54) to 0·83 (95 % CI 0·74, 0·93)) and respondents with children (OR = 0·69 (95 % CI 0·63, 0·75)) were less likely to eat in a restaurant/bar/retail than at home. Overweight and obese respondents had a greater odds of reporting an episode of eating in social situations v. alone (e.g. immediate family and extended family; OR = 1·13 (95 % CI 1·04, 1·22)) and episodes occurring in restaurant/bar/retail locations (OR = 1·12 (95 % CI 1·03, 1·23) to 1·14 (95 % CI 1·05, 1·24)).
CONCLUSIONS: Findings underscore the multidimensional nature of describing eating/drinking episodes. Social and physical contexts for eating/drinking and their demographic correlates suggest opportunities for tailoring interventions related to diet and may inform intervention targeting and scope
No Confirmed New Isolated Neutron Stars In The SDSS Data Release 4
We report on follow-up observations of candidate X-ray bright, radio-quiet
isolated neutron stars (INSs) identified from correlations of the ROSAT All-Sky
Survey (RASS) and the Sloan Digital Sky Survey (SDSS) Data Release 4 in
Ag\"ueros et al. (2006). We obtained Chandra X-ray Telescope exposures for 13
candidates in order to pinpoint the source of X-ray emission in optically blank
RASS error circles. These observations eliminated 12 targets as good INS
candidates. We discuss subsequent observations of the remaining candidate with
the XMM-Newton X-ray Observatory, the Gemini North Observatory, and the Apache
Point Observatory. We identify this object as a likely extragalactic source
with an unusually high log(fX/fopt) ~ 2.4. We also use an updated version of
the population synthesis models of Popov et al. (2010) to estimate the number
of RASS-detected INSs in the SDSS Data Release 7 footprint. We find that these
models predict ~3-4 INSs in the 11,000 square deg imaged by SDSS, which is
consistent with the number of known INSs that fall within the survey footprint.
In addition, our analysis of the four new INS candidates identified by Turner
et al. (2010) in the SDSS footprint implies that they are unlikely to be
confirmed as INSs; together, these results suggest that new INSs are not likely
to be found from further correlations of the RASS and SDSS.Comment: 11 pages, 2 figures, 3 tables; accepted for publication in A
Hyperaccreting Neutron-Star Disks and Neutrino Annihilation
Newborn neutron stars surrounded by hyperaccreting and neutrino-cooled disks
may exist in some gamma-ray bursts (GRBs) and/or supernovae (SNe). In this
paper we further study the structure of such a neutron-star disk based on the
two-region (i.e., inner & outer) disk scenario following our previous work, and
calculate the neutrino annihilation luminosity from the disk in various cases.
We investigate the effects of the viscosity parameter, energy parameter
(measuring the neutrino cooling efficiency of the inner disk) and outflow
strength on the structure of the entire disk as well as the effect of emission
from the neutron star surface boundary emission on the total neutrino
annihilation rate. The inner disk satisfies the entropy-conservation or the
advection-dominated self-similar structure depending on the energy parameter.
An outflow from the disk decreases the density and pressure but increases the
thickness of the disk. Moreover, compared with the black-hole disk, the
neutrino annihilation luminosity above the neutron-star disk is higher, and the
neutrino emission from the boundary layer could increase the neutrino
annihilation luminosity by about one order of magnitude higher than the disk
without boundary emission. The neutron-star disk with the advection-dominated
inner disk could produce the highest neutrino luminosity while the disk with an
outflow has the lowest. Although a heavily mass-loaded outflow from the neutron
star surface at early times of neutron star formation prevents the outflow
material from being accelerated to a high bulk Lorentz factor, an energetic
ultrarelativistic jet via neutrino annihilation can be produced above the
stellar polar region at late times if the disk accretion rate and the neutrino
emission luminosity from the surface boundary layer are sufficiently high.Comment: 46 pages, 11 figures, 4 tables, improved version following the
referee's comments, accepted for publication in Ap
Socioeconomic Differences in the Association Between Competitive Food Laws and the School Food Environment
Schools of low socioeconomic status (SES) tend to sell fewer healthy competitive foods/beverages. This study examined whether state competitive food laws may reduce such disparities
Interdisciplinary Perspectives on Sun Safety and Skin Cancer Risk: achieving consensus
Overexposure to the sun is associated with an increased risk of melanoma and nonmelanoma skin cancer, but indications of improvements in sun protection behavior are poor. Attempts to identify emerging themes in skin cancer control have largely been driven by groups of experts from a single field. In December 2016, 19 experts from various disciplines convened for Interdisciplinary Perspectives on Skin Cancer, a 2-day meeting hosted by the National Academy of Sciences. The group discussed knowledge gaps, perspectives on sun exposure, implications for skin cancer risk and other health outcomes, and new directions. Five themes emerged from the discussion: (1) The definition of risk must be expanded, and categories for skin physiology must be refined to incorporate population diversities. (2) Risky sun exposure often co-occurs with other health-related behaviors. (3) Messages must be nuanced to target at-risk populations. (4) Persons at risk for tanning disorder must be recognized and treated. (5) Sun safety interventions must be scalable. Efficient use of technologies will be required to sharpen messages to specific populations and to integrate them within multilevel interventions. Further interdisciplinary research should address these emerging themes to build effective and sustainable approaches to large-scale behavior change
Novae from isolated white dwarfs as a source of helium for second generation stars in globular clusters
We explore the possible contribution of classical and recurrent novae from
isolated white dwarfs accreting from the intracluster medium to the abundances
of "second generation" globular cluster stellar populations. We show that under
reasonable assumptions the helium abundances of clusters can be enhanced
substantially by these novae and argue that novae should be considered as an
important, and perhaps even dominant channel in the evolution of the
intracluster medium. We also discuss a possible test for whether helium
enhancement really is the cause of the multiple main sequences in globular
clusters that is independent of the positions of stars in the color-magnitude
diagram.Comment: 6 pages, accepted to MNRA
- …