20,760 research outputs found

    Geographic body size variation in ectotherms: effects of seasonality on an anuran from the southern temperate forest

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    Indexación: Web of Science; Scopus.Background: Body size variation has played a central role in biogeographical research, however, most studies have aimed to describe trends rather than search for underlying mechanisms. In order to provide a more comprehensive understanding of the causes of intra-specific body size variation in ectotherms, we evaluated eight hypotheses proposed in the literature to account for geographical body size variation using the Darwin's frog (Rhinoderma darwinii), an anuran species widely distributed in the temperate forests of South America. Each of the evaluated hypotheses predicted a specific relationship between body size and environmental variables. The level of support for each of these hypotheses was assessed using an information-theoretic approach and based on data from 1015 adult frogs obtained from 14 sites across the entire distributional range of the species. Results: There was strong evidence favouring a single model comprising temperature seasonality as the predictor variable. Larger body sizes were found in areas of greater seasonality, giving support to the "starvation resistance" hypothesis. Considering the known role of temperature on ectothermic metabolism, however, we formulated a new, non-exclusive hypothesis, termed "hibernation hypothesis": greater seasonality is expected to drive larger body size, since metabolic rate is reduced further and longer during colder, longer winters, leading to decreased energy depletion during hibernation, improved survival and increased longevity (and hence growth). Supporting this, a higher post-hibernation body condition in animals from areas of greater seasonality was found. Conclusions: Despite largely recognized effects of temperature on metabolic rate in ectotherms, its importance in determining body size in a gradient of seasonality has been largely overlooked so far. Based on our results, we present and discuss an alternative mechanism, the "hibernation hypothesis", underlying geographical body size variation, which can be helpful to improve our understanding of biogeographical patterns in ectotherms.https://frontiersinzoology.biomedcentral.com/articles/10.1186/s12983-015-0132-

    Applying black hole perturbation theory to numerically generated spacetimes

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    Nonspherical perturbation theory has been necessary to understand the meaning of radiation in spacetimes generated through fully nonlinear numerical relativity. Recently, perturbation techniques have been found to be successful for the time evolution of initial data found by nonlinear methods. Anticipating that such an approach will prove useful in a variety of problems, we give here both the practical steps, and a discussion of the underlying theory, for taking numerically generated data on an initial hypersurface as initial value data and extracting data that can be considered to be nonspherical perturbations.Comment: 14 pages, revtex3.0, 5 figure

    Restoration of eucalypt grassy woodland: effects of experimental interventions on ground-layer vegetation

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    We report on the effects of broad-scale restoration treatments on the ground layer of eucalypt grassy woodland in south-eastern Australia. The experiment was conducted in two conservation reserves from which livestock grazing had previously been removed. Changes in biomass, species diversity, ground-cover attributes and life-form were analysed over a 4-year period in relation to the following experimental interventions: (1) reduced kangaroo density, (2) addition of coarse woody debris and (3) fire (a single burn). Reducing kangaroo density doubled total biomass in one reserve, but no effects on exotic biomass, species counts or ground cover attributes were observed. Coarse woody debris also promoted biomass, particularly exotic annual forbs, as well as plant diversity in one of the reserves. The single burn reduced biomass, but changed little else. Overall, we found the main driver of change to be the favourable growth seasons that had followed a period of drought. This resulted in biomass increasing by 67%, (mostly owing to the growth of perennial native grasses), whereas overall native species counts increased by 18%, and exotic species declined by 20% over the 4-year observation period. Strategic management of grazing pressure, use of fire where biomass has accumulated and placement of coarse woody debris in areas of persistent erosion will contribute to improvements in soil and vegetation condition, and gains in biodiversity, in the future.Funding and in-kind logistic support for this project was provided by the ACT Government as part of an Australian Research Council Linkage Grant (LP0561817; LP110100126). Drafts of the manuscript were read by Saul Cunningham and Ben Macdonald

    Family visits to libraries and bookshops: observations and implications for digital libraries

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    This paper explores how families select books for leisure reading. We recruited 17 families (adults and children) for this study, and spent time with each in both bookshops and public libraries. Our research aims to add to understanding of how families interact with books and bookshelves in these places, and how digital libraries might best support the shared needs of these inter-generational users. Much of our understanding of how an eBook should look and feel comes from generalizations about books and assumptions about the needs of those individuals who read them. We explore how children and adults search and browse for books together, with specific focus on the type of information seeking tasks that families undertake and on the families’ shared search and browsing strategies. We further explore the implications of this study for the development of digital libraries for children and families

    Perspectives: nursing education - from vision to action in changing world

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    There is consensus that there are shared contemporary issues within nursing and nurse education that require collective consideration and, on occasion, shared solutions. Nonetheless, in the complex world in which we live, taking time to reflect on our work can become lost in the need to meet many competing demands. A conference can be expensive and time consuming, and as time pressures and deadlines loom risk becoming a short trip to present a paper rather than fuller engagement. With this in mind, we offer perspectives on our learning from The Federation of European Nurse Educators (FINE) 11th International FINE Conference in Malta (21–23 February 2018) and some opportunities and challenges facing nursing education today. FINE is a membership organisation, which, since its inception in 1994, has facilitated knowledge exchange and discussion around contemporary challenges in nursing education. Attendees came from 22 nations and five continents to share best practice and educational research innovation. This paper offers insight into key themes that emerged from the conference and the opportunities, innovations and challenges facing nursing education today. We include examples of papers debating these themes. In conclusion, we reflect on our experiences and offer benefits of global networking nursing education

    A virtual world of paleontology

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    Computer-aided visualization and analysis of fossils has revolutionized the study of extinct organisms. Novel techniques allow fossils to be characterized in three dimensions and in unprecedented detail. This has enabled paleontologists to gain important insights into their anatomy, development, and preservation. New protocols allow more objective reconstructions of fossil organisms, including soft tissues, from incomplete remains. The resulting digital reconstructions can be used in functional analyses, rigorously testing long-standing hypotheses regarding the paleobiology of extinct organisms. These approaches are transforming our understanding of long-studied fossil groups, and of the narratives of organismal and ecological evolution that have been built upon them

    A view of Large Magellanic Cloud HII regions N159, N132, and N166 through the 345 GHz window

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    We present results obtained towards the HII regions N159, N166, and N132 from the emission of several molecular lines in the 345 GHz window. Using ASTE we mapped a 2.4' ×\times 2.4' region towards the molecular cloud N159-W in the 13^{13}CO J=3-2 line and observed several molecular lines at an IR peak very close to a massive young stellar object. 12^{12}CO and 13^{13}CO J=3-2 were observed towards two positions in N166 and one position in N132. The 13^{13}CO J=3-2 map of the N159-W cloud shows that the molecular peak is shifted southwest compared to the peak of the IR emission. Towards the IR peak we detected emission from HCN, HNC, HCO+^{+}, C2_{2}H J=4-3, CS J=7-6, and tentatively C18^{18}O J=3-2. This is the first reported detection of these molecular lines in N159-W. The analysis of the C2_{2}H line yields more evidence supporting that the chemistry involving this molecular species in compact and/or UCHII regions in the LMC should be similar to that in Galactic ones. A non-LTE study of the CO emission suggests the presence of both cool and warm gas in the analysed region. The same analysis for the CS, HCO+^{+}, HCN, and HNC shows that it is very likely that their emissions arise mainly from warm gas with a density between 5×1055 \times 10^5 to some 10610^6 cm3^{-3}. The obtained HCN/HNC abundance ratio greater than 1 is compatible with warm gas and with an star-forming scenario. From the analysis of the molecular lines observed towards N132 and N166 we propose that both regions should have similar physical conditions, with densities of about 103^3 cm3^{-3}.Comment: accepted in MNRAS (October 5, 2015

    Colliding Black Holes: The Close Limit

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    The problem of the mutual attraction and joining of two black holes is of importance as both a source of gravitational waves and as a testbed of numerical relativity. If the holes start out close enough that they are initially surrounded by a common horizon, the problem can be viewed as a perturbation of a single black hole. We take initial data due to Misner for close black holes, apply perturbation theory and evolve the data with the Zerilli equation. The computed gravitational radiation agrees with and extends the results of full numerical computations.Comment: 4 pages, Revtex, 3 postscript figures included, CGPG-94/2-

    Health Research Participants' Preferences for Receiving Research Results

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    BACKGROUND: Participants in health research studies typically express interest in receiving results from the studies in which they participate. However, participants’ preferences and experiences related to receiving results are not well understood. In general, existing studies have had relatively small sample sizes and typically address specific and often sensitive issues within targeted populations. METHODS: The present study used an online survey to explore attitudes and experiences of registrants in ResearchMatch, a large database of past, present, and potential health research participants. Survey respondents provided information related to whether or not they received research results from studies in which they participated, the methods used to communicate results, their satisfaction with results, and when and how they would like to receive research results from future studies. 70,699 ResearchMatch registrants were notified of the study’s topic. Of the 5,207 registrants who requested full information about the study, 3,381 respondents completed the survey. RESULTS: Approximately 33% of respondents with previous health research participation reported receiving results. Approximately half of respondents with previous research participation reported no opportunity to request results. However, almost all respondents said researchers should always or sometimes offer results to participants. Respondents expressed particular interest in results related to their (or a loved one's) health, as well as information about studies’ purposes and any medical advances based on the results. In general, respondents’ most preferred dissemination methods for results were email and website postings. The least desirable dissemination methods for results included Twitter, conference calls, and text messages. Across all results, we compare the responses of respondents with and without previous research participation experience, and those who have worked in research organizations vs. those who have not. Compared to respondents who have previous participation experience, a greater proportion of respondents with no participation experience indicated that results should always be shared with participants. Likewise, respondents with no participation experience placed higher importance on the receipt of each type of results information included in the survey. CONCLUSIONS: We present findings from a survey assessing attitudes and experiences of a broad sample of respondents that addresses gaps in knowledge related to participants’ preferences for receiving results. The study’s findings highlight the potential for inconsistency between respondents’ expressed preferences to receive specific types of results via specific methods and researchers’ unwillingness or inability to provide them. We present specific recommendations to shift the approach of new studies to investigate participants’ preferences for receiving research results
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