989 research outputs found
Halo-model Analysis of the Clustering of Photometrically Selected Galaxies from SDSS
We measure the angular 2-point correlation functions of galaxies in a volume
limited, photometrically selected galaxy sample from the fifth data release of
the Sloan Digital Sky Survey. We split the sample both by luminosity and galaxy
type and use a halo-model analysis to find halo-occupation distributions that
can simultaneously model the clustering of all, early-, and late-type galaxies
in a given sample. Our results for the full galaxy sample are generally
consistent with previous results using the SDSS spectroscopic sample, taking
the differences between the median redshifts of the photometric and
spectroscopic samples into account. We find that our early- and late- type
measurements cannot be fit by a model that allows early- and late-type galaxies
to be well-mixed within halos. Instead, we introduce a new model that
segregates early- and late-type galaxies into separate halos to the maximum
allowed extent. We determine that, in all cases, it provides a good fit to our
data and thus provides a new statistical description of the manner in which
early- and late-type galaxies occupy halos.Comment: Accepted to MNRAS 11 pages, 6 figure
Most vital segment barriers
We study continuous analogues of "vitality" for discrete network flows/paths,
and consider problems related to placing segment barriers that have highest
impact on a flow/path in a polygonal domain. This extends the graph-theoretic
notion of "most vital arcs" for flows/paths to geometric environments. We give
hardness results and efficient algorithms for various versions of the problem,
(almost) completely separating hard and polynomially-solvable cases
Health comorbidities and cognitive abilities across the lifespan in Down syndrome.
BACKGROUND: Down syndrome (DS) is associated with variable intellectual disability and multiple health and psychiatric comorbidities. The impact of such comorbidities on cognitive outcomes is unknown. We aimed to describe patterns of physical health and psychiatric comorbidity prevalence, and receptive language ability, in DS across the lifespan, and determine relationships with cognitive outcomes. METHODS: Detailed medical histories were collected and cognitive abilities measured using standardised tests for 602 individuals with DS from England and Wales (age range 3 months to 73 years). Differences in prevalence rates between age groups and between males and females were determined using chi-squared or Fisher's exact tests. In adults, rates for psychiatric comorbidities were compared to expected population rates using standardised morbidity ratios (SMRs). Adapted ANCOVA functions were constructed to explore age and sex associations with receptive language ability across the lifespan, and regression analyses were performed to determine whether the presence of health comorbidities or physical phenotypes predicted cognitive abilities. RESULTS: Multiple comorbidities showed prevalence differences across the lifespan, though there were few sex differences. In adults, SMRs were increased in males and decreased in females with DS for schizophrenia, bipolar disorder, and anxiety. Further, SMRs were increased in both males and females with DS for dementia, autism, ADHD, and depression, with differences more pronounced in females for dementia and autism, and in males for depression. Across the lifespan, receptive language abilities increasingly deviated from age-typical levels, and males scored poorer than females. Only autism and epilepsy were associated with poorer cognitive ability in those aged 16-35 years, with no relationships for physical health comorbidities, including congenital heart defects. CONCLUSIONS: Our results indicate the prevalence of multiple comorbidities varies across the lifespan in DS, and in adults, rates for psychiatric comorbidities show different patterns for males and females relative to expected population rates. Further, most health comorbidities are not associated with poorer cognitive outcomes in DS, apart from autism and epilepsy. It is essential for clinicians to consider such differences to provide appropriate care and treatment for those with DS and to provide prognostic information relating to cognitive outcomes in those with comorbidities
O(\alpha^2 L) Radiative Corrections to Deep Inelastic ep Scattering
The leptonic QED radiative corrections are calculated in the next-to-leading
log approximation for unpolarized deeply
inelastic --scattering in the case of mixed variables. The corrections are
determined using mass factorization in the OMS--scheme for the
double--differential scattering cross sections.Comment: 10 pages LATEX, 1 style file
Traction forces generated during studded boot‐surface interactions on third‐generation artificial turf: A novel mechanistic perspective
The traction forces generated during studded boot–surface
interactions affect player performance and injury risk. Over
20 years of empirical research into traction on third
generation (3G) artificial turf has met with only limited
success in supporting the development of safer surfaces and
boots. Thus, the purpose of this perspective article is to
present a conceptual framework for generating scientific
understanding on 3G turf traction through a novel
mechanistic approach. A three-stage framework is
proposed. Firstly, the hypothesized traction mechanisms
and related analytical equations are identified, namely:
friction between the boot outsole and surface; shear
resistance of the performance infill layer to the outsole; and
compressive resistance of the performance infill layer to
horizontal stud displacement. Secondly, a Concept Map is
generated to visually represent the contribution of the thirtynine variables identified as directly affecting the traction
response. Finally, a Research Roadmap is constructed to
guide the direction of future traction studies towards the
development of safer surfaces and boots as well as improved
mechanical tests to assess surface safety. The proposed
framework represents the first attempt to deconstruct bootsurface interactions and hypothesize the science behind the
mobilization of traction forces
Galaxy Zoo: the dependence of morphology and colour on environment
We analyse the relationships between galaxy morphology, colour, environment
and stellar mass using data for over 100,000 objects from Galaxy Zoo, the
largest sample of visually classified morphologies yet compiled. We
conclusively show that colour and morphology fractions are very different
functions of environment. Both are sensitive to stellar mass; however, at fixed
stellar mass, while colour is also highly sensitive to environment, morphology
displays much weaker environmental trends. Only a small part of both relations
can be attributed to variation in the stellar mass function with environment.
Galaxies with high stellar masses are mostly red, in all environments and
irrespective of their morphology. Low stellar-mass galaxies are mostly blue in
low-density environments, but mostly red in high-density environments, again
irrespective of their morphology. The colour-density relation is primarily
driven by variations in colour fractions at fixed morphology, in particular the
fraction of spiral galaxies that have red colours, and especially at low
stellar masses. We demonstrate that our red spirals primarily include galaxies
with true spiral morphology. We clearly show there is an environmental
dependence for colour beyond that for morphology. Before using the Galaxy Zoo
morphologies to produce the above results, we first quantify a luminosity-,
size- and redshift-dependent classification bias that affects this dataset, and
probably most other studies of galaxy population morphology. A correction for
this bias is derived and applied to produce a sample of galaxies with reliable
morphological type likelihoods, on which we base our analysis.Comment: 25 pages, 20 figures (+ 6 pages, 11 figures in appendices);
moderately revised following referee's comments; accepted by MNRA
Distortions of Subjective Time Perception Within and Across Senses
Background: The ability to estimate the passage of time is of fundamental importance for perceptual and cognitive processes. One experience of time is the perception of duration, which is not isomorphic to physical duration and can be distorted by a number of factors. Yet, the critical features generating these perceptual shifts in subjective duration are not understood.
Methodology/Findings: We used prospective duration judgments within and across sensory modalities to examine the effect of stimulus predictability and feature change on the perception of duration. First, we found robust distortions of perceived duration in auditory, visual and auditory-visual presentations despite the predictability of the feature changes in the stimuli. For example, a looming disc embedded in a series of steady discs led to time dilation, whereas a steady disc embedded in a series of looming discs led to time compression. Second, we addressed whether visual (auditory) inputs could alter the perception of duration of auditory (visual) inputs. When participants were presented with incongruent audio-visual stimuli, the perceived duration of auditory events could be shortened or lengthened by the presence of conflicting visual information; however, the perceived duration of visual events was seldom distorted by the presence of auditory information and was never perceived shorter than their actual durations.
Conclusions/Significance: These results support the existence of multisensory interactions in the perception of duration and, importantly, suggest that vision can modify auditory temporal perception in a pure timing task. Insofar as distortions in subjective duration can neither be accounted for by the unpredictability of an auditory, visual or auditory-visual event, we propose that it is the intrinsic features of the stimulus that critically affect subjective time distortions
HAGE (DDX43) is a biomarker for poor prognosis and a predictor of chemotherapy response in breast cancer
Background: HAGE protein is a known immunogenic cancer-specific antigen. Methods: The biological, prognostic and predictive values of HAGE expression was studied using immunohistochemistry in three cohorts of patients with BC (n=2147): early primary (EP-BC; n=1676); primary oestrogen receptor-negative (PER-BC; n=275) treated with adjuvant anthracycline-combination therapies (Adjuvant-ACT); and primary locally advanced disease (PLA-BC) who received neo-adjuvant anthracycline-combination therapies (Neo-adjuvant-ACT; n=196). The relationship between HAGE expression and the tumour-infiltrating lymphocytes (TILs) in matched prechemotherapy and postchemotherapy samples were investigated. Results: Eight percent of patients with EP-BC exhibited high HAGE expression (HAGEþ) and was associated with aggressive clinico-pathological features (Ps<0.01). Furthermore, HAGEþexpression was associated with poor prognosis in both univariate and multivariate analysis (Ps<0.001). Patients with HAGE+ did not benefit from hormonal therapy in high-risk ER-positive disease. HAGE+ and TILs were found to be independent predictors for pathological complete response to neoadjuvant-ACT; P<0.001. A statistically significant loss of HAGE expression following neoadjuvant-ACT was found (P=0.000001), and progression-free survival was worse in those patients who had HAGE+ residual disease (P=0.0003). Conclusions: This is the first report to show HAGE to be a potential prognostic marker and a predictor of response to ACT in patients with BC
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