5,652 research outputs found

    Environments and Morphologies of Red Sequence Galaxies with Residual Star Formation in Massive Clusters

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    We present a photometric investigation into recent star formation in galaxy clusters at z ~ 0.1. We use spectral energy distribution templates to quantify recent star formation in large X-ray selected clusters from the LARCS survey using matched GALEX NUV photometry. These clusters all have signs of red sequence galaxy recent star formation (as indicated by blue NUV-R colour), regardless of cluster morphology and size. A trend in environment is found for these galaxies, such that they prefer to occupy low density, high cluster radius environments. The morphology of these UV bright galaxies suggests that they are in fact red spirals, which we confirm with light curves and Galaxy Zoo voting percentages as morphological proxies. These UV bright galaxies are therefore seen to be either truncated spiral galaxies, caught by ram pressure in falling into the cluster, or high mass spirals, with the photometry dominated by the older stellar population.Comment: Accepted for publication in MNRAS, 11 pages, 11 figure

    Effect of sintering atmosphere on the pore-structure stability of cerium-doped nanostructured alumina

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    Pore-structure stability of pure and Ce-doped alumina in air and argon atmospheres was studied using DTA, TGA, N2 ads./des. and XRD with a view to understand the importance of the ionic size of the dopant cation on the pore-structure stability of alumina. The ionic size effect was studied by heat treating the Ce-alumina system in both oxidizing and reducing atmospheres to have Ce4+ (87 pm) and Ce3+ (106 pm) respectively. No compound formation between Ce and alumina was observed. In the case of pure alumina there is a drastic reduction in porosity during the transformation to α-alumina. Ce-doped alumina has a higher DSC transformation temperature corresponding to the α-alumina transformation compared to pure alumina. Ce-doped alumina showed higher pore-structure stability compared with pure alumina and the stability was relatively higher in reducing atmosphere (higher Ce3+/Ce4+ ratio, higher effective ionic size) compared with oxidizing conditions (lower Ce3+/Ce4+ ratio, lower effective ionic size)

    Herpes encephalitis in an elderly immunocompetent lady – A case report

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    Herpes zoster encephalitis is a rare complication of varicella zoster virus infection. As its clinical presentation is usually non-specific, it often goes unrecognized. Advent of polymerase chain reaction test for detecting viral particles in the cerebrospinal fluid has enabled rapid and accurate diagnosis

    Ignition criteria for x-ray fast ignition inertial confinement fusion

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    The derivation of the ignition energy for fast ignition inertial confinement fusion is reviewed and one-dimensional simulations are used to produce a revised formula for the ignition energy of an isochoric central hot-spot, which accounts for variation in the radius of the hot-spot r_h as well as the density rho. The required energy may be as low as 1 kJ when rho*r_h ~ 0:36 g cm^-2; T ~ 20 keV, and rho greater or equal to 700 g cm^-2. Although there are many physical challenges to creating these conditions, a possible route to producing such a hot-spot is via a bright source of nonthermal soft x-rays. Further one-dimensional simulations are used to study the non-thermal soft x-ray heating of dense DT and it is found to offer the potential to significantly reduce hydrodynamic losses as compared to particle driven fast ignition due to the hotspot being heated supersonically in a layer-by-layer fashion. A sufficiently powerful soft x-ray source would be difficult to produce, but line emission from laser-produced-plasma is the most promising option

    Should I Stay or Should I Go? The Emergence of Partitioned Land Use Among Human Foragers

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    Taking inspiration from the archaeology of the Texas Coastal Plain (TCP), we develop an ecological theory of population distribution among mobile hunter-gatherers. This theory proposes that, due to the heterogeneity of resources in space and time, foragers create networks of habitats that they access through residential cycling and shared knowledge. The degree of cycling that individuals exhibit in creating networks of habitats, encoded through social relationships, depends on the relative scarcity of resources and fluctuations in those resources. Using a dynamic model of hunter-gatherer population distribution, we illustrate that increases in population density, coupled with shocks to a biophysical or social system, creates a selective environment that favors habitat partitioning and investments in social mechanisms that control the residential cycling of foragers on a landscape. Our work adds a layer of realism to Ideal Distribution Models by adding a time allocation decision process in a variable environment and illustrates a general variance reduction, safe-operating space tradeoff among mobile human foragers that drives social change
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