992 research outputs found

    Error, bias, and long-branch attraction in data for two chloroplast photosystem genes in seed plants

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    Sequences of two chloroplast photosystem genes, psaA and psbB, together comprising about 3,500 bp, were obtained for all five major groups of extant seed plants and several outgroups among other vascular plants. Strongly supported, but significantly conflicting, phylogenetic signals were obtained in parsimony analyses from partitions of the data into first and second codon positions versus third positions. In the former, both genes agreed on a monophyletic gymnosperms, with Gnetales closely related to certain conifers. In the latter, Gnetales are inferred to be the sister group of all other seed plants, with gymnosperms paraphyletic. None of the data supported the modern ‘‘anthophyte hypothesis,’’ which places Gnetales as the sister group of flowering plants. A series of simulation studies were undertaken to examine the error rate for parsimony inference. Three kinds of errors were examined: random error, systematic bias (both properties of finite data sets), and statistical inconsistency owing to long-branch attraction (an asymptotic property). Parsimony reconstructions were extremely biased for third-position data for psbB. Regardless of the true underlying tree, a tree in which Gnetales are sister to all other seed plants was likely to be reconstructed for these data. None of the combinations of genes or partitions permits the anthophyte tree to be reconstructed with high probability. Simulations of progressively larger data sets indicate the existence of long-branch attraction (statistical inconsistency) for third-position psbB data if either the anthophyte tree or the gymnosperm tree is correct. This is also true for the anthophyte tree using either psaA third positions or psbB first and second positions. A factor contributing to bias and inconsistency is extremely short branches at the base of the seed plant radiation, coupled with extremely high rates in Gnetales and nonseed plant outgroups. M. J. Sanderson,* M. F. Wojciechowski,*† J.-M. Hu,* T. Sher Khan,* and S. G. Brad

    Social Network Intelligence Analysis to Combat Street Gang Violence

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    In this paper we introduce the Organization, Relationship, and Contact Analyzer (ORCA) that is designed to aide intelligence analysis for law enforcement operations against violent street gangs. ORCA is designed to address several police analytical needs concerning street gangs using new techniques in social network analysis. Specifically, it can determine "degree of membership" for individuals who do not admit to membership in a street gang, quickly identify sets of influential individuals (under the tipping model), and identify criminal ecosystems by decomposing gangs into sub-groups. We describe this software and the design decisions considered in building an intelligence analysis tool created specifically for countering violent street gangs as well as provide results based on conducting analysis on real-world police data provided by a major American metropolitan police department who is partnering with us and currently deploying this system for real-world use

    Translation, adaptation, and content validation of a French version of the Nurse Competence Scale in Canada.

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    Background: While everyone agrees that it is important for nurses to be competent practitioners, no validated French questionnaire measuring nurse competence is available to date. Internationally, one of the most frequently used questionnaires used to measure the competence level of nurses working in a clinical setting is the Nurse Competence Scale (NCS). Objective: The objective of this study was to translate and culturally adapt a French version of the NCS (NCS-Fr) with nurses working in the province of Quebec (Canada). Methods: It had a multi-method design, inspired by guidelines for translation, adaptation, and validation of scales in health research. The scale instructions and items were translated from English to French by two translators knowledgeable in nursing/healthcare and then back-translated to English by two other translators. Versions were compared; ambiguities and discrepancies were resolved during a synthesis discussion. A convenience sample of registered nurses (n=8) and experts in nursing education (n=10) assessed instructions and items for comprehensibility. Results: Content validity index (CVI) for items (I-CVI) of the preliminary version ranged from 0.56 to 1, with most items (n=64) meeting the threshold of 0.78. The scale CVI (S-CVI) was 0.89. Conclusion: This study used a rigorous method to translate and adapt a French version of the NCS. The next step will be to evaluate the psychometric properties and items performance of the NCSFr

    PAssive Thermal Coating Observatory Operating in Low Earth Orbit (PATCOOL)

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    The PATCOOL is a NASA sponsored, University of Florida developed 3U CubeSat meant to investigate the feasibility of using a cryogenic selective surface coating as a new, more efficient way of passively cooling components in space. Initial tests on the ground demonstrate that this coating should provide a much higher reflectance of the Sun's irradiant power than any existing coating, while still providing far-infrared power emission. The ultimate validation of this technology requires on-orbit testing. PATCOOL hosts a 4-sample housing, with the samples shaped as thin cylinders (coin-like). Two samples are coated with state-of-the-art material, while the other pair uses the new coating to be evaluated. The temperatures of all samples during the mission (minimum 72 hours of data collection) are measured via thermistors. The samples are connected via thin Kevlar strings to the housing, to minimize heat transfer. The housing is designed to shield the samples from Earth's thermal radiation, and the CubeSat is attitude stabilized and controlled via a gravity gradient boom, magnetorquers and a reaction wheel set. Thermal Desktop simulations show PATCOOL's ability to thermally isolate the samples from heat exchanges other than with Sun and deep space, thanks to its thermal design and the chosen attitude profil

    Passive Thermal Coating Observatory Operating in Low-Earth Orbit (PATCOOL) Cubesat Design to Test Passive Thermal Coatings in Space

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    The PATCOOL is a NASA sponsored, University of Florida developed 3U Cu-beSat meant to investigate the feasibility of using a cryogenic selective surface coating as a new, more efficient way of passively cooling components in space. Initial tests on the ground demonstrate that this coating should provide a much higher reflectance of the Suns irradiant power than any existing coating, while still providing far-infrared power emission. The ultimate validation of this tech-nology requires on-orbit testing. PATCOOL hosts a 4-sample housing, with the samples shaped as thin cylinders (coin-like). Two samples are coated with state-of-the-art material, while the other pair uses the new coating to be evaluated. The temperatures of all samples during the mission (minimum 72 hours of data col-lection) are measured via thermistors. The samples are connected via thin Kevlar strings to the housing, to minimize heat transfer. The housing is designed to shield the samples from Earths thermal radiation, and the CubeSat is attitude stabilized and controlled via a gravity gradient boom, magnetorquers and a reaction wheel set. Thermal Desktop simulations show PATCOOLs ability to thermally isolate the samples from heat exchanges other than with Sun and deep space, thanks to its thermal design and the chosen attitude profile

    Molecular mechanisms linking wound inflammation and fibrosis: knockdown of osteopontin leads to rapid repair and reduced scarring

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    Previous studies of tissue repair have revealed osteopontin (OPN) to be up-regulated in association with the wound inflammatory response. We hypothesize that OPN may contribute to inflammation-associated fibrosis. In a series of in vitro and in vivo studies, we analyze the effects of blocking OPN expression at the wound, and determine which inflammatory cells, and which paracrine factors from these cells, may be responsible for triggering OPN expression in wound fibroblasts. Delivery of OPN antisense oligodeoxynucleotides into mouse skin wounds by release from Pluronic gel decreases OPN protein levels at the wound and results in accelerated healing and reduced granulation tissue formation and scarring. To identify which leukocytic lineages may be responsible for OPN expression, we cultured fibroblasts in macrophage-, neutrophil-, or mast cell–conditioned media (CM), and found that macrophage- and mast cell–secreted factors, specifically platelet-derived growth factor (PDGF), induced fibroblast OPN expression. Correspondingly, Gleevec, which blocks PDGF receptor signaling, and PDGF-Rβ–neutralizing antibodies, inhibited OPN induction by macrophage-CM. These studies indicate that inflammation-triggered expression of OPN both hinders the rate of repair and contributes to wound fibrosis. Thus, OPN and PDGF are potential targets for therapeutic modulation of skin repair to improve healing rate and quality

    A low-cost, precise piezoelectric droplet-on-demand generator

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    We present the design of a piezoelectric droplet-on-demand generator capable of producing droplets of highly repeatable size ranging from 0.5 to 1.4 mm in diameter. The generator is low cost and simple to fabricate. We demonstrate the manner in which droplet diameter can be controlled through variation of the piezoelectric driving waveform parameters, outlet pressure, and nozzle diameter.National Science Foundation (U.S.) (Grants CBET-0966452 and CMMI-1333242)National Science Foundation (U.S.) (Fellowship
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