2,103 research outputs found
Measuring Redshift-Space Distortions using Photometric Surveys
We outline how redshift-space distortions (RSD) can be measured from the
angular correlation function w({\theta}), of galaxies selected from photometric
surveys. The natural degeneracy between RSD and galaxy bias can be minimized by
comparing results from bins with top-hat galaxy selection in redshift, and bins
based on the radial position of galaxy pair centres. This comparison can also
be used to test the accuracy of the photometric redshifts. The presence of RSD
will be clearly detectable with the next generation of photometric redshift
surveys. We show that the Dark Energy Survey (DES) will be able to measure
f(z){\sigma}_8(z) to a 1{\sigma} accuracy of (17 {\times} b)%, using galaxies
drawn from a single narrow redshift slice centered at z = 1. Here b is the
linear bias, and f is the logarithmic rate of change of the linear growth rate
with respect to the scale factor. Extending to measurements of w({\theta}) for
a series of bins of width 0.02(1 + z) over 0.5 < z < 1.4 will measure {\gamma}
to a 1{\sigma} accuracy of 25%, given the model f = {\Omega}_m(z)^{\gamma}, and
assuming a linear bias model that evolves such that b = 0.5 + z (and fixing
other cosmological parameters). The accuracy of our analytic predictions is
confirmed using mock catalogs drawn from simulations conducted by the MICE
collaboration.Comment: Accepted by MNRAS, revisions include fixing of typos and
clarification of the tex
Obesity in individuals with schizophrenia:a case controlled study in Scotland
We would like to thank Dr Moira Connolly, Professor Steve Lawrie and Dr Carol Robertson who, along with the authors, were part of a protocol development group funded by the NHS Research Scotland Mental Health Network (NRS MHN) formerly known as the Scottish Mental Health Research Network (SMHRN). We are grateful to the NRS MHN for funding the data acquisition and to the PCCIU for providing the data. We also thank Professor Gordon Murray for statistical advice.Peer reviewedPublisher PD
Use of the TIDier checklist to describe an online structured education programme for type 2 diabetes
Objectives:
The aim of structured education for type 2 diabetes is to improve knowledge, skills and confidence in self-management. It is recommended in the UK for everyone who is newly diagnosed with type 2 diabetes. We developed an on-line programme called HeLP-Diabetes: Starting Out to address poor uptake of face-to-face structured education. The aim of this paper is to describe the intervention in line with the Template for Intervention Description and Replication guide, which calls for better reporting of interventions.
Methods:
The Template for Intervention Description and Replication guide provided the item headings for the description. These included the theoretical underpinning, materials, procedures, providers, and mode of delivery.
Results:
The programme was developed to meet NICE requirements for structured education and therefore followed a structured curriculum with four sessions covering content such as what diabetes is and how it is treated, possible complications, and how lifestyle changes can improve health. Content was delivered in text, images and video, and behaviour change techniques, self-assessment and feedback were used to help people target key health behaviours. The programme was delivered entirely online, but the team were available for support via telephone. Email feedback and reminders were sent.
Conclusions:
The TIDieR checklist allowed us to provide a clear structure for the description of the intervention. However, it could not capture the full complexity of the programme, and intervention developers considering using it in the future may find that it needs to be adapted to make it more specific to their intervention
Properties of planetary fluids at high pressure and temperature
In order to derive models of the interiors of Uranus, Neptune, Jupiter and Saturn, researchers studied equations of state and electrical conductivities of molecules at high dynamic pressures and temperatures. Results are given for shock temperature measurements of N2 and CH4. Temperature data allowed demonstration of shock induced cooling in the the transition region and the existence of crossing isotherms in P-V space
Road-Edge Effects on Herpetofauna in a Lowland Amazonian Rainforest
The impact of roads on the flora and fauna of Neotropical rainforest is perhaps the single biggest driver of habitat modification and population declines in these ecosystems. We investigated the road-edge effect of a low-use dirt road on amphibian and reptile abundance, diversity, and composition within adjacent lowland Amazonian rainforest at San José de Payamino, Ecuador. The road has been closed to vehicle traffic since its construction in 2010. Thus, effects from vehicle mortality, vehicle-related pollution, and road noise were not confounding factors. Herpetofauna were surveyed using both visual encounter surveys and drift fences with pitfall and funnel traps at varying distances from the road. Structural and microclimate features of the forest were measured at each sampling distance. Several habitat variables were found to differ at intermediate and interior sampling distances from the road compared to forest edge conditions, suggesting the road-edge effect began to attenuate by the intermediate sampling distance. However, the edge effect on amphibians and reptiles appeared to extend 100 m from the road edge, as abundance and diversity were significantly greater at the interior forest compared to the forest edge. Additionally, assemblage composition as well as the hierarchical position of species shifted between sampling distances. Habitat predictor models indicate that amphibian abundance was best predicted by vine abundance, while both vine and mature tree abundance were the best predictors for species richness and diversity. Overall, and contrary to what might otherwise be expected, our results demonstrate that small, little-used road disturbances can nonetheless have profound impacts on wildlife
Understanding the faint red galaxy population using large-scale clustering measurements from SDSS DR7
We use data from the SDSS to investigate the evolution of the large-scale
galaxy bias as a function of luminosity for red galaxies. We carefully consider
correlation functions of galaxies selected from both photometric and
spectroscopic data, and cross-correlations between them, to obtain multiple
measurements of the large-scale bias. We find, for our most robust analyses, a
strong increase in bias with luminosity for the most luminous galaxies, an
intermediate regime where bias does not evolve strongly over a range of two
magnitudes in galaxy luminosity, and no evidence for an upturn in bias for
fainter red galaxies. Previous work has found an increase in bias to low
luminosities that has been widely interpreted as being caused by a strong
preference for red dwarf galaxies to be satellites in the most massive halos.
We can recover such an upturn in bias to faint luminosities if we push our
measurements to small scales, and include galaxy clustering measurements along
the line-of-sight, where we expect non-linear effects to be the strongest. The
results that we expect to be most robust suggest that the low luminosity
population of red galaxies is not dominated by satellite galaxies occupying the
most massive haloes.Comment: Matches version accepted by MNRA
Dislocation Emission around Nanoindentations on a (001) fcc Metal Surface Studied by STM and Atomistic Simulations
We present a combined study by Scanning Tunneling Microscopy and atomistic
simulations of the emission of dissociated dislocation loops by nanoindentation
on a (001) fcc surface. The latter consist of two stacking-fault ribbons
bounded by Shockley partials and a stair-rod dislocation. These dissociated
loops, which intersect the surface, are shown to originate from loops of
interstitial character emitted along the directions and are usually
located at hundreds of angstroms away from the indentation point. Simulations
reproduce the nucleation and glide of these dislocation loops.Comment: 10 pages, 4 figure
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