187 research outputs found

    Spectral mapping of brain functional connectivity from diffusion imaging.

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    Understanding the relationship between the dynamics of neural processes and the anatomical substrate of the brain is a central question in neuroscience. On the one hand, modern neuroimaging technologies, such as diffusion tensor imaging, can be used to construct structural graphs representing the architecture of white matter streamlines linking cortical and subcortical structures. On the other hand, temporal patterns of neural activity can be used to construct functional graphs representing temporal correlations between brain regions. Although some studies provide evidence that whole-brain functional connectivity is shaped by the underlying anatomy, the observed relationship between function and structure is weak, and the rules by which anatomy constrains brain dynamics remain elusive. In this article, we introduce a methodology to map the functional connectivity of a subject at rest from his or her structural graph. Using our methodology, we are able to systematically account for the role of structural walks in the formation of functional correlations. Furthermore, in our empirical evaluations, we observe that the eigenmodes of the mapped functional connectivity are associated with activity patterns associated with different cognitive systems

    Burbot Early Life History Strategies in the Great Lakes

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    Burbot Lota lota exhibit four previously known reproductive strategies in the Great Lakes region. In this paper we review those strategies and provide evidence for a fifth one—delayed deepwater spawning. The four known, shallow‐water strategies are as follows: (1) spawning by self‐sustaining, landlocked populations, (2) spawning in tributaries in winter and the exit of larvae to a Great Lake, (3) spawning by residents in a spawning stream with access to a Great Lake, and (4) spawning on unconsolidated and rocky areas in shallow water in winter in the lake proper. Resident, landlocked populations exist in some Michigan and Wisconsin rivers (e.g., the Muskegon River in Michigan). The evidence for winter tributary spawning is the appearance of newly hatched Burbot in the St. Marys and Bark rivers during April–June. Evidence for Burbot juveniles leaving spawning streams is U.S. Fish and Wildlife Service tributory mouth trap data. The evidence for winter nearshore spawning comes from power plant monthly entrainment studies (Mansfield et al. 1983). Our proposed fifth strategy is spring and summer spawning at deep reefs, where there is probably cobble or boulder habitat. Our evidence comes from midlake reefs in Lake Michigan and offshore areas of Lake Huron: (1) we collected adult Burbot at midlake reefs in Lake Michigan, (2) we collected many Burbot larvae (many of which were newly hatched) from Lakes Michigan and Huron in June–August, and (3) we collected a Burbot egg in a PONAR grab in mid‐July from 73 m in southern Lake Huron. An important question remains, namely, which life history strategy provides the highest recruitment success for this species. It may be that adaptability ensures the survival of this important, top‐predator fish during periods of crisis (e.g., encounters with dams, Sea Lamprey Petromyzon marinus predation).Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141895/1/tafs1733.pd

    Starting the conversation: land issues and critical conservation studies in post-colonial Africa

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    This thematic issue brings together the scholarly fields of critical conservation studies and African land issues, a relationship largely unexplored to date. The alienation of land for conservation purposes, introduced to Africa under colonial rule and still taking place today, has fundamental impacts on the politics of land and land use, and is contested in contemporary nation-states - including those that are attempting to implement land restitution and reform. The contributors explore these issues in a range of African contexts. Three key themes are identified: the problematic constructions of ‘community’ by outside agencies; spatial exclusion and the silencing of local voices; and the neoliberalisation of conservation spaces. In contributing to new perspectives on these themes, this thematic issue shows how discourses and practices of conservation, increasingly shaped by neoliberalism, currently impact on land ownership, access and use. It further highlights some important historical continuities. These trends can be observed in transfrontier conservation areas, on state-owned land used for conservation and ‘green’ initiatives, but also on private land where conservation is increasingly turned to commercial purposes.International Bibliography of Social Science

    The Seventh Data Release of the Sloan Digital Sky Survey

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    This paper describes the Seventh Data Release of the Sloan Digital Sky Survey (SDSS), marking the completion of the original goals of the SDSS and the end of the phase known as SDSS-II. It includes 11663 deg^2 of imaging data, with most of the roughly 2000 deg^2 increment over the previous data release lying in regions of low Galactic latitude. The catalog contains five-band photometry for 357 million distinct objects. The survey also includes repeat photometry over 250 deg^2 along the Celestial Equator in the Southern Galactic Cap. A coaddition of these data goes roughly two magnitudes fainter than the main survey. The spectroscopy is now complete over a contiguous area of 7500 deg^2 in the Northern Galactic Cap, closing the gap that was present in previous data releases. There are over 1.6 million spectra in total, including 930,000 galaxies, 120,000 quasars, and 460,000 stars. The data release includes improved stellar photometry at low Galactic latitude. The astrometry has all been recalibrated with the second version of the USNO CCD Astrograph Catalog (UCAC-2), reducing the rms statistical errors at the bright end to 45 milli-arcseconds per coordinate. A systematic error in bright galaxy photometr is less severe than previously reported for the majority of galaxies. Finally, we describe a series of improvements to the spectroscopic reductions, including better flat-fielding and improved wavelength calibration at the blue end, better processing of objects with extremely strong narrow emission lines, and an improved determination of stellar metallicities. (Abridged)Comment: 20 pages, 10 embedded figures. Accepted to ApJS after minor correction

    A Single-Blind randomized controlled trial to evaluate the effect of extended counseling on uptake of pre-antiretroviral care in eastern uganda

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    <p>Abstract</p> <p>Background</p> <p>Many newly screened people living with HIV (PLHIV) in Sub-Saharan Africa do not understand the importance of regular pre-antiretroviral (ARV) care because most of them have been counseled by staff who lack basic counseling skills. This results in low uptake of pre-ARV care and late treatment initiation in resource-poor settings. The effect of providing post-test counseling by staff equipped with basic counseling skills, combined with home visits by community support agents on uptake of pre-ARV care for newly diagnosed PLHIV was evaluated through a randomized intervention trial in Uganda.</p> <p>Methods</p> <p>An intervention trial was performed consisting of post-test counseling by trained counselors, combined with monthly home visits by community support agents for continued counseling to newly screened PLHIV in Iganga district, Uganda between July 2009 and June 2010, Participants (N = 400) from three public recruitment centres were randomized to receive either the intervention, or the standard care (the existing post-test counseling by ARV clinic staff who lack basic training in counseling skills), the control arm. The outcome measure was the proportion of newly screened and counseled PLHIV in either arm who had been to their nearest health center for clinical check-up in the subsequent three months +2 months. Treatment was randomly assigned using computer-generated random numbers. The statistical significance of differences between the two study arms was assessed using chi-square and t-tests for categorical and quantitative data respectively. Risk ratios and 95% confidence intervals were used to assess the effect of the intervention.</p> <p>Results</p> <p>Participants in the intervention arm were 80% more likely to accept (take up) pre-ARV care compared to those in the control arm (RR 1.8, 95% CI 1.4-2.1). No adverse events were reported.</p> <p>Conclusions</p> <p>Provision of post-test counseling by staff trained in basic counseling skills, combined with home visits by community support agents had a significant effect on uptake of pre-ARV care and appears to be a cost-effective way to increase the prerequisites for timely ARV initiation.</p> <p>Trial registration</p> <p>The trial was registered by Current Controlled Trials Ltd C/OBioMed Central Ltd as <a href="http://www.controlled-trials.com/ISRCTN94133652">ISRCTN94133652</a> and received financial support from Sida and logistical support from the European Commission.</p
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