3,401 research outputs found
Examination of the validity of the Social Support Survey using confirmatory factor analysis.
types: Journal Article; Validation StudiesCopyright © 2000 Taylor & Francis. This is an Author's Accepted Manuscript of an article published in Research Quarterly for Exercise and Sport available online at: http://www.tandfonline.com/doi/abs/10.1080/02701367.2000.10608915?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed#.VN3Q1p1FDcsThe Social Support Survey (SSS), validated by Richman, Rosenfeld, and Hardy (1993), is a multidimensional self-report measure of social support tested with student athletes. The SSS contains eight dimensions of support. For each dimension of support the same four questions are posed. The SSS could, therefore, be scored in two ways: (a) to derive a score for the support dimensions; (b) to derive a score for the questions posed across all eight support dimensions. Confirmatory factor analyses of the SSS on 416 university athletes revealed poor fits to models for both the eight support dimensions and the four questions across all eight dimensions. This problem was clarified by using a multitrait-multimethod model, which led to improved model fit but revealed that most of the SSS items were two-dimensional. Caution should, therefore, be exercised in using the SSS as a measure of multidimensional social support
Across the great divide: genetic forensics reveals misidentification of endangered cutthroat trout populations
Accurate assessment of species identity is fundamental for conservation biology. Using molecular markers from the mitochondrial and nuclear genomes, we discovered that many putatively native populations of greenback cutthroat trout (Oncorhynchus clarkii stomias) comprised another subspecies of cutthroat trout, Colorado River cutthroat trout (Oncorhynchus clarkii pleuriticus). The error can be explained by the introduction of Colorado River cutthroat trout throughout the native range of greenback cutthroat trout in the late 19th and early 20th centuries by fish stocking activities. Our results suggest greenback cutthroat trout within its native range is at a higher risk of extinction than ever before despite conservation activities spanning more than two decades
Volumetric, relaxometric and diffusometric correlates of psychotic experiences in a non-clinical sample of young adults
BACKGROUND: Grey matter (GM) abnormalities are robust features of schizophrenia and of people at ultra high-risk for psychosis. However the extent to which neuroanatomical alterations are evident in non-clinical subjects with isolated psychotic experiences is less clear. METHODS: Individuals (mean age 20 years) with (n = 123) or without (n = 125) psychotic experiences (PEs) were identified from a population-based cohort. All underwent T1-weighted structural, diffusion and quantitative T1 relaxometry MRI, to characterise GM macrostructure, microstructure and myelination respectively. Differences in quantitative GM structure were assessed using voxel-based morphometry (VBM). Binary and ordinal models of PEs were tested. Correlations between socioeconomic and other risk factors for psychosis with cortical GM measures were also computed. RESULTS: GM volume in the left supra-marginal gyrus was reduced in individuals with PEs relative to those with no PEs. The greater the severity of PEs, the greater the reduction in T1 relaxation rate (R1) across left temporoparietal and right pre-frontal cortices. In these regions, R1 was positively correlated with maternal education and inversely correlated with general psychopathology. CONCLUSIONS: PEs in non-clinical subjects were associated with regional reductions in grey-matter volume reduction and T1 relaxation rate. The alterations in T1 relaxation rate were also linked to the level of general psychopathology. Follow up of these subjects should clarify whether these alterations predict the later development of an ultra high-risk state or a psychotic disorder
D3/D7 Quark-Gluon Plasma with Magnetically Induced Anisotropy
We study the effects of the temperature and of a magnetic field in the setup
of an intersection of D3/D7 branes, where a large number of D7 branes is
smeared in the transverse directions to allow for a perturbative solution in a
backreaction parameter. The magnetic field sources an anisotropy in the plasma,
and we investigate its physical consequences for the thermodynamics and energy
loss of particles probing the system. In particular we comment on the
stress-energy tensor of the plasma, the propagation of sound in the directions
parallel and orthogonal to the magnetic field, the drag force of a quark moving
through the medium and jet quenching.Comment: 29 pages + appendices, 5 figures. v2 Version to appear in JHEP, with
minor revisions, references added and typos correcte
Task analysis for error identification: Theory, method and validation
This paper presents the underlying theory of Task Analysis for Error Identification. The aim is to illustrate the development of a method that has been proposed for the evaluation of prototypical designs from the perspective of predicting human error. The paper presents the method applied to representative examples. The methodology is considered in terms of the various validation studies that have been conducted, and is discussed in the light of a specific case study
A combined transmission spectrum of the Earth-sized exoplanets TRAPPIST-1 b and c
Three Earth-sized exoplanets were recently discovered close to the habitable
zone of the nearby ultracool dwarf star TRAPPIST-1. The nature of these planets
has yet to be determined, since their masses remain unmeasured and no
observational constraint is available for the planetary population surrounding
ultracool dwarfs, of which the TRAPPIST-1 planets are the first transiting
example. Theoretical predictions span the entire atmospheric range from
depleted to extended hydrogen-dominated atmospheres. Here, we report a
space-based measurement of the combined transmission spectrum of the two inner
planets made possible by a favorable alignment resulting in their simultaneous
transits on 04 May 2016. The lack of features in the combined spectrum rules
out cloud-free hydrogen-dominated atmospheres for each planet at 10-
levels; TRAPPIST-1 b and c are hence unlikely to harbor an extended gas
envelope as they lie in a region of parameter space where high-altitude
cloud/haze formation is not expected to be significant for hydrogen-dominated
atmospheres. Many denser atmospheres remain consistent with the featureless
transmission spectrum---from a cloud-free water vapour atmosphere to a
Venus-like atmosphere.Comment: Early release to inform further the upcoming review of HST's Cycle 24
proposal
VLT/FORS2 comparative transmission spectroscopy II: confirmation of a cloud-deck and Rayleigh scattering in WASP-31b, but no potassium?
This is the author accepted manuscript. The final version is available from OUP via the DOI in this record.We present transmission spectroscopy of the hot-Jupiter WASP-31b using FORS2
on the VLT during two primary transits. The observations cover a wavelength range
of â400â840 nm. The light curves are corrupted by significant systematics, but these
were to first order invariant with wavelength and could be removed using a commonmode
correction derived from the white light curves. We reach a precision in the
transit depth of â140 ppm in 15 nm bins, although the precision varies significantly
over the wavelength range. Our FORS2 observations confirm the cloud-deck previously
inferred using HST/STIS. We also re-analyse the HST/STIS data using a Gaussian
process model, finding excellent agreement with earlier measurements. We reproduce
the Rayleigh scattering signature at short wavelengths (. 5300 ËA) and the
cloud-deck at longer wavelengths. However, our FORS2 observations appear to rule
out the large potassium feature previously detected using STIS, yet it is recovered from
the HST/STIS data, although with reduced amplitude and significance (â 2.5Ï). The
discrepancy between our results and the earlier STIS detection of potassium (â 4.3Ï) is
either a result of telluric contamination of the ground-based observations, or an underestimate
of the uncertainties for narrow-band features in HST/STIS when using linear
basis models to account for the systematics. Our results further demonstrate the use
of ground-based multi-object spectrographs for the study of exoplanet atmospheres,
and highlight the need for caution in our interpretation of narrow-band features in
low-resolution spectra of hot-Jupiters.This work is based on observations collected at the European
Organisation for Astronomical Research in the Southern
Hemisphere under ESO programme 096.C-0765. N. P.
G. gratefully acknowledges support from the Royal Society
in the form of a University Research Fellowship. N. N, D. K.
S, and T. M. E. acknowledge funding from the European Research
Council under the European Unions Seventh Framework
Programme (FP7/2007-2013) / ERC grant agreement
no. 336792. J. K. B. is supported by a Royal Astronomical
Society Research Fellowship. P.A.W. acknowledges the
support of the French Agence Nationale de la Recherche
(ANR), under program ANR-12-BS05-0012 âExo-Atmosâ.
We are grateful to the developers of the NumPy, SciPy,
Matplotlib, iPython and Astropy packages, which were
used extensively in this work (Jones et al. 01 ; Hunter 2007;
PÂŽerez & Granger 2007; Astropy Collaboration et al. 2013)
VLT/FORS2 comparative transmission spectroscopy II: Confirmation of a cloud deck and Rayleigh scattering in WASP-31b, but no potassium?
We present transmission spectroscopy of the hot-Jupiter WASP-31b using the FOcal Reducer and low dispersion Spectrograph 2 (FORS2) on the Very Large Telescope during two primary transits. The observations cover a wavelength range of â400â840 nm. The light curves are corrupted by significant systematics, but these were to first-order invariant with wavelength and could be removed using a common-mode correction derived from the white light curves. We reach a precision in the transit depth of â140 ppm in 15 nm bins, although the precision varies significantly over the wavelength range. Our FORS2 observations confirm the cloud deck previously inferred using Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph (STIS). We also re-analyse the HST/STIS data using a Gaussian process model, finding excellent agreement with earlier measurements. We reproduce the Rayleigh scattering signature at short wavelengths (5300 Ă
) and the cloud deck at longer wavelengths. However, our FORS2 observations appear to rule out the large potassium feature previously detected using STIS, yet it is recovered from the HST/STIS data, although with reduced amplitude and significance (â2.5Ï ). The discrepancy between our results and the earlier STIS detection of potassium (â4.3Ï ) is either a result of telluric contamination of the ground-based observations, or an underestimate of the uncertainties for narrow-band features in HST/STIS when using linear basis models to account for the systematics. Our results further demonstrate the use of ground-based multi-object spectrographs for the study of exoplanet atmospheres, and highlight the need for caution in our interpretation of narrow-band features in low-resolution spectra of hot Jupiters
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