329 research outputs found

    The fractal dimension of star-forming regions at different spatial scales in M33

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    We study the distribution of stars, HII regions, molecular gas, and individual giant molecular clouds in M33 over a wide range of spatial scales. The clustering strength of these components is systematically estimated through the fractal dimension. We find scale-free behavior at small spatial scales and a transition to a larger correlation dimension (consistent with a nearly uniform distribution) at larger scales. The transition region lies in the range 500-1000 pc. This transition defines a characteristic size that separates the regime of small-scale turbulent motion from that of large-scale galactic dynamics. At small spatial scales, bright young stars and molecular gas are distributed with nearly the same three-dimensional fractal dimension (Df <= 1.9), whereas fainter stars and HII regions exhibit higher values (Df = 2.2-2.5). Our results indicate that the interstellar medium in M33 is on average more fragmented and irregular than in the Milky Way.Comment: 18 pages including 4 figures. Accepted for publication in Ap

    Audience effects on the neural correlates of relational reasoning in adolescence

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    Adolescents are particularly sensitive to peer influence. This may partly be due to an increased salience of peers during adolescence. We investigated the effect of being observed by a peer on a cognitively challenging task, relational reasoning, which requires the evaluation and integration of multiple mental representations. Relational reasoning tasks engage a fronto-parietal network including the inferior parietal cortex, pre-supplementary motor area, dorsolateral and rostrolateral prefrontal cortices. Using functional magnetic resonance imaging (fMRI), peer audience effects on activation in this fronto-parietal network were compared in a group of 19 female mid-adolescents (aged 14-16 years) and 14 female adults (aged 23-28 years). Adolescent and adult relational reasoning accuracy was influenced by a peer audience as a function of task difficulty: the presence of a peer audience led to decreased accuracy in the complex, relational integration condition in both groups of participants. The fMRI results demonstrated that a peer audience differentially modulated activation in regions of the fronto-parietal network in adolescents and adults. Activation was increased in adolescents in the presence of a peer audience, while this was not the case in adults

    Quantitative estimation of tissue blood flow rate

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    The rate of blood flow through a tissue (F) is a critical parameter for assessing the functional efficiency of a blood vessel network following angiogenesis. This chapter aims to provide the principles behind the estimation of F, how F relates to other commonly used measures of tissue perfusion, and a practical approach for estimating F in laboratory animals, using small readily diffusible and metabolically inert radio-tracers. The methods described require relatively nonspecialized equipment. However, the analytical descriptions apply equally to complementary techniques involving more sophisticated noninvasive imaging. Two techniques are described for the quantitative estimation of F based on measuring the rate of tissue uptake following intravenous administration of radioactive iodo-antipyrine (or other suitable tracer). The Tissue Equilibration Technique is the classical approach and the Indicator Fractionation Technique, which is simpler to perform, is a practical alternative in many cases. The experimental procedures and analytical methods for both techniques are given, as well as guidelines for choosing the most appropriate method

    Response of Coastal Fishes to the Gulf of Mexico Oil Disaster

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    The ecosystem-level impacts of the Deepwater Horizon disaster have been largely unpredictable due to the unique setting and magnitude of this spill. We used a five-year (2006–2010) data set within the oil-affected region to explore acute consequences for early-stage survival of fish species inhabiting seagrass nursery habitat. Although many of these species spawned during spring-summer, and produced larvae vulnerable to oil-polluted water, overall and species-by-species catch rates were high in 2010 after the spill (1,989±220 fishes km-towed−1 [μ ± 1SE]) relative to the previous four years (1,080±43 fishes km-towed−1). Also, several exploited species were characterized by notably higher juvenile catch rates during 2010 following large-scale fisheries closures in the northern Gulf, although overall statistical results for the effects of fishery closures on assemblage-wide CPUE data were ambiguous. We conclude that immediate, catastrophic losses of 2010 cohorts were largely avoided, and that no shifts in species composition occurred following the spill. The potential long-term impacts facing fishes as a result of chronic exposure and delayed, indirect effects now require attention

    A scoping study of interventions to increase the uptake of physical activity (PA) amongst individuals with mild-to-moderate depression (MMD)

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    Background - Depression is the largest contributor to disease burden globally. The evidence favouring physical activity as a treatment for mild-to-moderate depression is extensive and relatively uncontested. It is unclear, however, how to increase an uptake of physical activity amongst individuals experiencing mild-to-moderate depression. This leaves professionals with no guidance on how to help people experiencing mild-to-moderate depression to take up physical activity. The purpose of this study was to scope the evidence on interventions to increase the uptake of physical activity amongst individuals experiencing mild-to-moderate depression, and to develop a model of the mechanisms by which they are hypothesised to work. Methods - A scoping study was designed to include a review of primary studies, grey literature and six consultation exercises; two with individuals with experience of depression, two pre-project consultations with physical activity, mental health and literature review experts, one with public health experts, and one with community engagement experts. Results - Ten papers met the inclusion criteria and were included in the review. Consultation exercises provided insights into the mechanisms of an uptake of physical activity amongst individuals experiencing mild-to-moderate depression; evidence concerning those mechanisms is (a) fragmented in terms of design and purpose; (b) of varied quality; (c) rarely explicit about the mechanisms through which the interventions are thought to work. Physical, environmental and social factors that may represent mediating variables in the uptake of physical activity amongst people experiencing mild-to-moderate depression are largely absent from studies. Conclusions - An explanatory model was developed. This represents mild-to-moderate depression as interfering with (a) the motivation to take part in physical activity and (b) the volition that it is required to take part in physical activity. Therefore, both motivational and volitional elements are important in any intervention to increase physical activity in people with mild-to-moderate depression. Furthermore, mild-to-moderate depression-specific factors need to be tackled in any physical activity initiative, via psychological treatments such as Cognitive Behavioural Therapy. We argu

    Sports graduate capabilities and competencies: a comparison of graduate and employer perceptions in six EU countries

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    The graduate employment market faces ever-increasing socio-economic and political pressures. Higher Education Institutions and the sport sector in the EU have an important role in contributing to graduate employment. The aims of the study were: (1) to assess general perceptions of employability, and (2) to assess sports graduates’ and employers’ perceptions of specific capabilities and competencies in order to identify possible improvements for sports graduate employability programmes. A cross-sectional survey of sports graduates and employers was administered in six EU countries including the UK, France, Germany, Spain, Greece and the Czech Republic to assess graduate and employer perceptions. A graduate capabilities and competencies framework was devised to assess personal, interpersonal, cognitive, role-specific and generic skills. Responses were elicited from 1132 sports graduates and 327 employers. There was generally a wide difference of opinion between employers and sports graduates in terms of the importance and possession of a number of capabilities and competencies. There is a need for the Higher Education sector and employers to take responsibility in ensuring that work experience, work placement and volunteering opportunities are embedded in curricula and to ensure the fitness of purpose of what and how graduate capabilities and competencies are assessed

    Repeatability of Corticospinal and Spinal Measures during Lengthening and Shortening Contractions in the Human Tibialis Anterior Muscle

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    Elements of the human central nervous system (CNS) constantly oscillate. In addition, there are also methodological factors and changes in muscle mechanics during dynamic muscle contractions that threaten the stability and consistency of transcranial magnetic stimulation (TMS) and perpherial nerve stimulation (PNS) measures

    A consensus-based transparency checklist

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    We present a consensus-based checklist to improve and document the transparency of research reports in social and behavioural research. An accompanying online application allows users to complete the form and generate a report that they can submit with their manuscript or post to a public repository
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