6,653 research outputs found

    Phylogenetics, Biogeography, and Patterns of Diversification of GeckosAcross the Sunda Shelf with an Emphasis on the GenusCnemaspis (Strauch, 1887)

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    In my dissertation I investigate two genera of geckos (Cyrtodactylus and Cnemaspis) that are distributed across Southeast Asia with an emphasis on Cnemaspis. In Chapter 1 I use a multilocus dataset, ancestral area analyses, and molecular clock dating to generate a species level time calibrated phylogeny to test the monophyly of Cyrtodactylus and to identify major biogeographical patterns. I identified that Cyrtodactylus is monophyletic only if the the Sri Lankan genus often recognized as Geckoella is included. The results of the Biogeographical analyses reveal a west to east pattern of diversification. Chapter 2 I use a traditional morphological dataset to describe a new species of Cnemaspis from Peninsular Malaysia. In Chapter 3 my colleagues and I use a multilocus dataset and morphological characters to revise the taxonomy of all Cnemaspis species and put this in a phylogenetic context. This resulted in the description of eight new species and allowed us to generate hypotheses relating to parallel evolution, diversity, and biogeography. In Chapter 4 I use additional taxon sampling of Cnemaspis from Thailand to generate a more complete phylogeny and use an integrative taxonomic approach to describe three new species. In Chapter 5 I used high throughput sequencing of sequence capture and Ultra Conserved Elements to test for a rapid radiation in Cnemaspis and to investigate biogeographic hypotheses relating to the diversification and evolution of Cnemaspis. I determined that there was a temporal rapid radiation of Cnemaspis that coincides with the temporal diversification of other terrestrial vertebrates across Sundaland. The results of these studies indicate that the species diversity of Cnemaspis is underestimated and that both genera have experienced similar temporal and spatial diversification coinciding with major vicariant events during the Eocene and the Oligocene-Miocene transition

    Brain-derived neurotrophic factor prevents dendritic retraction of adult mouse retinal ganglion cells

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    We used cultured adult mouse retinae as a model system to follow and quantify the retraction of dendrites using diolistic labelling of retinal ganglion cells (RGCs) following explantation. Cell death was monitored in parallel by nuclear staining as ‘labelling’ with RGC and apoptotic markers was inconsistent and exceedingly difficult to quantify reliably. Nuclear staining allowed us to delineate a lengthy time window during which dendrite retraction can be monitored in the absence of RGC death. The addition of brain-derived neurotrophic factor (BDNF) produced a marked reduction in dendritic degeneration, even when application was delayed for 3 days after retinal explantation. These results suggest that the delayed addition of trophic factors may be functionally beneficial before the loss of cell bodies in the course of conditions such as glaucoma

    LSST Science Book, Version 2.0

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    A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at http://www.lsst.org/lsst/sciboo

    Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

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    Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

    Constitutivism

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    A brief explanation and overview of constitutivism

    Azimuthally anisotropic emission of low-momentum direct photons in Au++Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV

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    The PHENIX experiment at the Relativistic Heavy Ion Collider has measured 2nd and 3rd order Fourier coefficients of the azimuthal distributions of direct photons emitted at midrapidity in Au++Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV for various collision centralities. Combining two different analysis techniques, results were obtained in the transverse momentum range of 0.4<pT<4.00.4<p_{T}<4.0 GeV/cc. At low pTp_T the second-order coefficients, v2v_2, are similar to the ones observed in hadrons. Third order coefficients, v3v_3, are nonzero and almost independent of centrality. These new results on v2v_2 and v3v_3, combined with previously published results on yields, are compared to model calculations that provide yields and asymmetries in the same framework. Those models are challenged to explain simultaneously the observed large yield and large azimuthal anisotropies.Comment: 552 authors, 15 pages, 9 figures, 3 tables, 2007 and 2010 data. v2 is version accepted for publication by Phys. Rev. C. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm
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