2,879 research outputs found

    Nanostructured Vanadium Oxide Uncooled Bolometers and Method of Fabrication

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    The present invention relates to uncooled microbolometers which can be integrated in future thermal instruments engaged in land imaging on future observatories. The present invention includes: (1) developing and characterizing a microstructured VOx thin film, and, (2) fabricating an uncooled microbolometer array over the 8-14 micron spectral band

    When trees grow too long: Investigating the causes of highly inaccurate bayesian branch-length estimates

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    A surprising number of recent Bayesian phylogenetic analyses contain branch-length estimates that are several orders of magnitude longer than corresponding maximum-likelihood estimates. The levels of divergence implied by such branch lengths are unreasonable for studies using biological data and are known to be false for studies using simulated data. We conducted additional Bayesian analyses and studied approximate-posterior surfaces to investigate the causes underlying these large errors. We manipulated the starting parameter values of the Markov chain Monte Carlo (MCMC) analyses, the moves used by the MCMC analyses, and the prior-probability distribution on branch lengths. We demonstrate that inaccurate branch-length estimates result from either 1) poor mixing of MCMC chains or 2) posterior distributions with excessive weight at long tree lengths. Both effects are caused by a rapid increase in the volume of branch-length space as branches become longer. In the former case, both an MCMC move that scales all branch lengths in the tree simultaneously and the use of overdispersed starting branch lengths allow the chain to accurately sample the posterior distribution and should be used in Bayesian analyses of phylogeny. In the latter case, branch-length priors can have strong effects on resulting inferences and should be carefully chosen to reflect biological expectations. We provide a formula to calculate an exponential rate parameter for the branch-length prior that should eliminate inference of biased branch lengths in many cases. In any phylogenetic analysis, the biological plausibility of branch-length output must be carefully considered

    Leukocytoclastic Vasculitis in a 66-Year-Old Woman After Fusion of the Second Right Metatarsocuneiform Joint Using Titanium Plate and Screws: A Case Report

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    Metallic orthopaedic implants are known to instigate cutaneous reactions; however, the mechanism by which this occurs is not fully understood. Contact dermatitis after implantation of stainless steel fracture plates was first described in 1966, and similar reactions to various implants have been documented subsequently. Leukocytoclastic vasculitis (LCV) is an inflammatory condition of small dermal blood vessels resulting from neutrophil invasion, degranulation, and cell death caused by a type III hypersensitivity reaction. No studies have reported use of titanium orthopaedic implants resulting in LCV. We describe a 66-year-old woman who developed LCV after the fusion of her second right metatarsocuneiform joint with a titanium plate and screws. At 4 months after removal of the titanium plate and screws, the LCV symptoms had resolved without further intervention. Although this rash might be a rare complication associated with orthopaedic implants, it is an important differential diagnosis for orthopaedic surgeons to consider when assessing and treating postoperative rashes

    Microscopic crystallographic analysis of dislocations in molecular crystals

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    Organic molecular crystals encompass a vast range of materials from pharmaceuticals to organic optoelectronics and proteins to waxes in biological and industrial settings. Crystal defects from grain boundaries to dislocations are known to play key roles in mechanisms of growth and also in the functional properties of molecular crystals. In contrast to the precise analysis of individual defects in metals, ceramics, and inorganic semiconductors enabled by electron microscopy, significantly greater ambiguity remains in the experimental determination of individual dislocation character and slip systems in molecular materials. In large part, nanoscale dislocation analysis in molecular crystals has been hindered by the severely constrained electron exposures required to avoid irreversibly degrading these crystals. Here, we present a low-dose, single-exposure approach enabling nanometre-resolved analysis of individual extended dislocations in molecular crystals. We demonstrate the approach for a range of crystal types to reveal dislocation character and operative slip systems unambiguously.Comment: Manuscript (14 pages, 4 figures) and Supplementary Material (32 pages, 19 figures) in a single PDF fil

    Verbal Compliments As a Differential Source of Mate Poaching Threat For Men and Women

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    Two studies tested whether people feel threatened by another individual verbally complimenting their romantic partner. Such compliments may indicate that the other person is a potential rival who will try to poach their mate. Across two studies, women were more threatened than men when imagining another person complimenting their partner\u27s physical appearance. There were no sex differences in response to imagining another person complimenting their partner\u27s sense of humor. When another person compliments one\u27s partner\u27s physical appearance, this indicates that they may be sexually attracted to the partner. Mediation analyses revealed that the sex difference occurs because women believe men are more open to casual sex, and therefore more vulnerable to mate poaching when another person expresses sexual interest in them

    Multicentury Fire and Forest Histories at 19 Sites in Utah and Eastern Nevada

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    Our objective is to provide site-specific fire and forest histories from Utah and eastern Nevada that can be used for land management or additional research. We systematically sampled fire scars and tree-recruitment dates across broad gradients in elevation and forest type at 13 sites in Utah and 1 in eastern Nevada to characterize spatial and temporal variation in historical fire regimes as well as forest structure and composition. We collected similar data non-systematically at five additional sites in Utah. These 19 sites include a broad range of forest types (from pinyon-juniper woodlands to spruce-fir forests) and fire regime types. In this report, we summarize local-scale spatial and temporal variation with site-specific details of historical fire regimes and forests that will be useful for local natural resource and fire management of the individual sites. For each site, we report topography, chronologies of fire and tree recruitment, and properties derived from those chronologies such as time-averaged fire regime parameters (mean fire interval and fire severity) and changes in forest composition and structure that have occurred since the late 1800s

    NMR elastometry of fluid membranes in the mesoscopic regime

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    In solid-state 2H NMR of fluid lipid bilayers, quasielastic deformations at MHz frequencies are detected as a square-law dependence of the nuclear spin-lattice (R1Z) relaxation rates and order parameters (SCD). The signature square-law slope is found to decrease progressively with the mole fraction of cholesterol and with the acyl chain length, due to a stiffening of the membrane. The correspondence to thermal vesicle fluctuations and molecular dynamics simulations implies that a broad distribution of modes is present, ranging from the membrane size down to the molecular dimensions
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