2,753 research outputs found
Change in active travel and changes in recreational and total physical activity in adults: longitudinal findings from the iConnect study.
BACKGROUND: To better understand the health benefits of promoting active travel, it is important to understand the relationship between a change in active travel and changes in recreational and total physical activity. METHODS: These analyses, carried out in April 2012, use longitudinal data from 1628 adult respondents (mean age 54 years; 47% male) in the UK-based iConnect study. Travel and recreational physical activity were measured using detailed seven-day recall instruments. Adjusted linear regression models were fitted with change in active travel defined as 'decreased' (15 min/week) as the primary exposure variable and changes in (a) recreational and (b) total physical activity (min/week) as the primary outcome variables. RESULTS: Active travel increased in 32% (n=529), was maintained in 33% (n=534) and decreased in 35% (n=565) of respondents. Recreational physical activity decreased in all groups but this decrease was not greater in those whose active travel increased. Conversely, changes in active travel were associated with commensurate changes in total physical activity. Compared with those whose active travel remained unchanged, total physical activity decreased by 176.9 min/week in those whose active travel had decreased (adjusted regression coefficient -154.9, 95% CI -195.3 to -114.5) and was 112.2 min/week greater among those whose active travel had increased (adjusted regression coefficient 135.1, 95% CI 94.3 to 175.9). CONCLUSION: An increase in active travel was associated with a commensurate increase in total physical activity and not a decrease in recreational physical activity
Circulation and Dissipation on Hot Jupiters
Many global circulation models predict supersonic zonal winds and large
vertical shears in the atmospheres of short-period jovian exoplanets. Using
linear analysis and nonlinear local simulations, we investigate hydrodynamic
dissipation mechanisms to balance the thermal acceleration of these winds. The
adiabatic Richardson criterion remains a good guide to linear stability,
although thermal diffusion allows some modes to violate it at very long
wavelengths and very low growth rates. Nonlinearly, wind speeds saturate at
Mach numbers and Richardson numbers for a broad
range of plausible diffusivities and forcing strengths. Turbulence and vertical
mixing, though accompanied by weak shocks, dominate the dissipation, which
appears to be the outcome of a recurrent Kelvin-Helmholtz instability. An
explicit shear viscosity, as well as thermal diffusivity, is added to ZEUS to
capture dissipation outside of shocks. The wind speed is not monotonic nor
single valued for shear viscosities larger than about of the sound
speed times the pressure scale height. Coarsening the numerical resolution can
also increase the speed. Hence global simulations that are incapable of
representing vertical turbulence and shocks, either because of reduced physics
or because of limited resolution, may overestimate wind speeds. We recommend
that such simulations include artificial dissipation terms to control the Mach
and Richardson numbers and to capture mechanical dissipation as heat.Comment: 34 pages, 10 figure
Recommended from our members
Trajectories of maternal depression and offspring psychopathology at 6 years: 2004 Pelotas cohort study
BACKGROUND: Few studies have addressed the course and severity of maternal depression and its effects on child psychiatric disorders from a longitudinal perspective. This study aimed to identify longitudinal patterns of maternal depression and to evaluate whether distinct depression trajectories predict particular psychiatric disorders in offspring. METHODS: Cohort of 4231 births followed-up in the city of Pelotas, Brazil. Maternal depressive symptoms were assessed with the Edinburgh Postnatal Depression Scale (EPDS) at 3, 12, 24 and 48 months and 6 years after delivery. Psychiatric disorders in 6-year-old children were evaluated through the development and well-being assessment (DAWBA) instrument. Trajectories of maternal depression were calculated using a group-based modelling approach. RESULTS: We identified five trajectories of maternal depressive symptoms: a "low" trajectory (34.8%), a "moderate low" (40.9%), a "increasing" (9.0%), a "decreasing" (9.9%), and a "high-chronic" trajectory (5.4%). The probability of children having any psychiatric disorder, as well as both internalizing and externalizing problems, increased as we moved from the "low" to the "high-chronic" trajectory. These differences were not explained by maternal and child characteristics examined in multivariate analyses. LIMITATIONS: Data on maternal depression at 3-months was available on only a sub-sample. In addition, we had to rely on maternal report of child's behavior alone. CONCLUSIONS: The study revealed an additive effect on child outcome of maternal depression over time. We identified a group of mothers with chronic and severe symptoms of depression throughout the first six years of the child life and for this group child psychiatric outcome was particularly compromised
Three Dimensional Modeling of Hot Jupiter Atmospheric Flows
We present a three dimensional hot Jupiter model, extending from 200 bar to 1
mbar, using the Intermediate General Circulation Model from the University of
Reading. Our horizontal spectral resolution is T31 (equivalent to a grid of
48x96), with 33 logarithmically spaced vertical levels. A simplified
(Newtonian) scheme is employed for the radiative forcing. We adopt a physical
set up nearly identical to the model of HD 209458b by Cooper & Showman
(2005,2006) to facilitate a direct model inter-comparison. Our results are
broadly consistent with theirs but significant differences also emerge. The
atmospheric flow is characterized by a super-rotating equatorial jet, transonic
wind speeds, and eastward advection of heat away from the dayside. We identify
a dynamically-induced temperature inversion ("stratosphere") on the planetary
dayside and find that temperatures at the planetary limb differ systematically
from local radiative equilibrium values, a potential source of bias for transit
spectroscopic interpretations. While our model atmosphere is quasi-identical to
that of Cooper & Showman (2005,2006) and we solve the same meteorological
equations, we use different algorithmic methods, spectral-implicit vs.
grid-explicit, which are known to yield fully consistent results in the Earth
modeling context. The model discrepancies identified here indicate that one or
both numerical methods do not faithfully capture all of the atmospheric
dynamics at work in the hot Jupiter context. We highlight the emergence of a
shock-like feature in our model, much like that reported recently by Showman et
al. (2009), and suggest that improved representations of energy conservation
may be needed in hot Jupiter atmospheric models, as emphasized by Goodman
(2009).Comment: 25 pages, 6 figures, minor revisions, ApJ accepted, version with
hi-res figures:
http://www.astro.columbia.edu/~kristen/Hires/hotjup.3d.deep.ps.g
A Systematic Review of Online Sex Addiction and Clinical Treatments Using CONSORT Evaluation
Researchers have suggested that the advances of the Internet over the past two decades have gradually eliminated traditional offline methods of obtaining sexual material. Additionally, research on cybersex and/or online sex addictions has increased alongside the development of online technology. The present study extended the findings from Griffiths’ (2012) systematic empirical review of online sex addiction by additionally investigating empirical studies that implemented and/or documented clinical treatments for online sex addiction in adults. A total of nine studies were identified and then each underwent a CONSORT evaluation. The main findings of the present review provide some evidence to suggest that some treatments (both psychological and/or pharmacological) provide positive outcomes among those experiencing difficulties with online sex addiction. Similar to Griffiths’ original review, this study recommends that further research is warranted to establish the efficacy of empirically driven treatments for online sex addiction
The influence of mothers' and fathers' parenting stress and depressive symptoms on own and partner's parent-child communication
This study examines how parenting stress and depressive symptoms experienced by mothers and fathers influence their own (actor effects) and the partner's (partner effects) parent–child communication. Based on the Actor-Partner Interdependence Model, data from 196 families were analyzed, with both parents rating their parenting stress and depressive feelings, and parents as well as children rating the open parent–child communication. Actor effects were found between parenting stress and open parent–child communication, whereas partner effects were prominent between depressive symptoms and open parent–child communication. The results provide no evidence for gender differences in the strength of the pathways to open parent–child communication. Our findings demonstrate the need to include both parents in studies on parent–child communication to enhance our understanding of the mutual influence among family members
Acceptability, reliability, referential distributions and sensitivity to change in the Young Person's Clinical Outcomes in Routine Evaluation (YP-CORE) outcome measure: Replication and refinement
Background: Many outcome measures for young people exist, but the choices for services are limited when seeking measures that (a) are free to use in both paper and electronic format, and (b) have evidence of good psychometric properties. Method: Data on the Young Person's Clinical Outcomes in Routine Evaluation (YP-CORE), completed by young people aged 11-16, are reported for a clinical sample (N = 1269) drawn from seven services and a nonclinical sample (N = 380). Analyses report item omission, reliability, referential distributions and sensitivity to change. Results: The YP-CORE had a very low rate of missing items, with 95.6% of forms at preintervention fully completed. The overall alpha was .80, with the values for all four subsamples (11-13 and 14-16 by gender) exceeding .70. There were significant differences in mean YP-CORE scores by gender and age band, as well as distinct reliable change indices and clinically significant change cut-off points. Conclusions: These findings suggest that the YP-CORE satisfies standard psychometric requirements for use as a routine outcome measure for young people. Its status as a free to use measure and the availability of an increasing number of translations makes the YP-CORE a candidate outcome measure to be considered for routine services
Atmospheric Circulation of Hot Jupiters: A Shallow Three-Dimensional Model
Remote observing of exoplanetary atmospheres is now possible, offering us
access to circulation regimes unlike any of the familiar Solar System cases.
Atmospheric circulation models are being developed to study these new regimes
but model validations and intercomparisons are needed to establish their
consistency and accuracy. To this end, we present a simple Earth-like
validation of the pseudo-spectral solver of meteorological equations called
IGCM (Intermediate General Circulation Model), based on Newtonian relaxation to
a prescribed latitudinal profile of equilibrium temperatures. We then describe
a straightforward and idealized model extension to the atmospheric flow on a
hot Jupiter with the same IGCM solver. This shallow, three-dimensional hot
Jupiter model is based on Newtonian relaxation to a permanent day-night pattern
of equilibrium temperatures and the absence of surface drag. The baroclinic
regime of the Earth's lower atmosphere is contrasted with the more barotropic
regime of the simulated hot Jupiter flow. For plausible conditions at the 0.1-1
bar pressure level on HD 209458b, the simulated flow is characterized by
unsteadiness, subsonic wind speeds, a zonally-perturbed superrotating
equatorial jet and large scale polar vortices. Violation of the Rayleigh-Kuo
inflexion point criterion on the flanks of the accelerating equatorial jet
indicates that barotropic (horizontal shear) instabilities may be important
dynamical features of the simulated flow. Similarities and differences with
previously published simulated hot Jupiter flows are briefly noted.Comment: 31 pages, 9 figures, accepted for publication in ApJ. Version with
hi-res figures:
http://www.astro.columbia.edu/~kristen/Hires/hotjup.3d.shallow.ps.g
Daylight saving time as a potential public health intervention: an observational study of evening daylight and objectively-measured physical activity among 23,000 children from 9 countries.
BACKGROUND: It has been proposed that introducing daylight saving measures could increase children's physical activity, but there exists little research on this issue. This study therefore examined associations between time of sunset and activity levels, including using the bi-annual 'changing of the clocks' as a natural experiment. METHODS: 23,188 children aged 5-16 years from 15 studies in nine countries were brought together in the International Children's Accelerometry Database. 439 of these children were of particular interest for our analyses as they contributed data both immediately before and after the clocks changed. All children provided objectively-measured physical activity data from Actigraph accelerometers, and we used their average physical activity level (accelerometer counts per minute) as our primary outcome. Date of accelerometer data collection was matched to time of sunset, and to weather characteristics including daily precipitation, humidity, wind speed and temperature. RESULTS: Adjusting for child and weather covariates, we found that longer evening daylight was independently associated with a small increase in daily physical activity. Consistent with a causal interpretation, the magnitude of these associations was largest in the late afternoon and early evening and these associations were also evident when comparing the same child just before and just after the clocks changed. These associations were, however, only consistently observed in the five mainland European, four English and two Australian samples (adjusted, pooled effect sizes 0.03-0.07 standard deviations per hour of additional evening daylight). In some settings there was some evidence of larger associations between daylength and physical activity in boys. There was no evidence of interactions with weight status or maternal education, and inconsistent findings for interactions with age. CONCLUSIONS: In Europe and Australia, evening daylight seems to play a causal role in increasing children's activity in a relatively equitable manner. Although the average increase in activity is small in absolute terms, these increases apply across all children in a population. Moreover, these small effect sizes actually compare relatively favourably with the typical effect of intensive, individual-level interventions. We therefore conclude that, by shifting the physical activity mean of the entire population, the introduction of additional daylight saving measures could yield worthwhile public health benefits
Atmospheric circulation of tidally locked exoplanets: a suite of benchmark tests for dynamical solvers
The complexity of atmospheric modelling and its inherent non-linearity,
together with the limited amount of data of exoplanets available, motivate
model intercomparisons and benchmark tests. In the geophysical community, the
Held-Suarez test is a standard benchmark for comparing dynamical core
simulations of the Earth's atmosphere with different solvers, based on
statistically-averaged flow quantities. In the present study, we perform
analogues of the Held-Suarez test for tidally-locked exoplanets with the
GFDL-Princeton Flexible Modeling System (FMS) by subjecting both the spectral
and finite difference dynamical cores to a suite of tests, including the
standard benchmark for Earth, a hypothetical tidally-locked Earth, a "shallow"
hot Jupiter model and a "deep" model of HD 209458b. We find qualitative and
quantitative agreement between the solvers for the Earth, tidally-locked Earth
and shallow hot Jupiter benchmarks, but the agreement is less than satisfactory
for the deep model of HD 209458b. Further investigation reveals that closer
agreement may be attained by arbitrarily adjusting the values of the horizontal
dissipation parameters in the two solvers, but it remains the case that the
magnitude of the horizontal dissipation is not easily specified from first
principles. Irrespective of radiative transfer or chemical composition
considerations, our study points to limitations in our ability to accurately
model hot Jupiter atmospheres with meteorological solvers at the level of ten
percent for the temperature field and several tens of percent for the velocity
field. Direct wind measurements should thus be particularly constraining for
the models. Our suite of benchmark tests also provides a reference point for
researchers wishing to adapt their codes to study the atmospheric circulation
regimes of tidally-locked Earths/Neptunes/Jupiters.Comment: Accepted by MNRAS, 23 pages, 17 figures, 2 tables. No changes from
previous version, except MNRAS wants no hyphen in the title. Sample movies of
simulations are available at http://www.phys.ethz.ch/~kheng/fms
- …