1,886 research outputs found

    Performance of Cold-Formed Steel Shear Walls with Frame Blocking and Double-Sheathing

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    This paper summarizes a laboratory based research program on blocked and double-sheathed cold-formed steel framed shear walls. The intent was to develop walls whose in-plane shear resistance exceeds that of configurations currently listed in the AISI S400 Standard. The results showed that the frame blocking can be used in the construction of walls whose resistance is at the limit of that found in AISI S400; however, the blocking will not adequately restrain the framing members if thicker sheathing is used. An approach was needed to minimize the effect of the eccentric loading caused by the sheathing and to account for the combination of axial compression and bending on the chord studs. Shear walls with steel sheathing placed on both sides of the framing demonstrated resistances up to twice those listed in AISI S400, without damage to the framing members, and similar ductility characteristics to previously tested CFS shear walls

    Isolation of Fungi from Lake Vostok Accretion Ice

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    Here we report the characterization of fungi from 10 accretion ice sections (3300-5100 y old) as well as two deep glacial ice sections that are close to the bottom of the glacier (1 000 000-2 000 000 y old) from the Vostok, Antarctica, 5G ice core. Fungi were characterized by fluorescence microscopy culturing and sequence analyses of ribosomal DNA internal transcribed spacers. A total of 270 fungal colonies were cultured from the accretion ice of subglacial Lake Vostok and an additional 14 from the glacial ice immediately above the accretion ice. Mean concentrations were 0-4.42 cells mL-1 ice meltwater of which 0-100% exhibited viability (as determined by fluorescence microscopy). Thirty-one unique fungal ribosomal DNA sequences (28 from accretion ice and three from glacial ice) were determined and compared to recent taxa. The results, plus tests for growth at low temperatures, indicated that Lake Vostok contains a mixture of heterotrophic psychrotolerant fungal species. This indicates that the lake is not sterile but contains a unique ecosystem

    Development of a Genetic Algorithm to Automate Clustering of a Dependency Structure Matrix

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    Much technology assessment and organization design data exists in Microsoft Excel spreadsheets. Tools are needed to put this data into a form that can be used by design managers to make design decisions. One need is to cluster data that is highly coupled. Tools such as the Dependency Structure Matrix (DSM) and a Genetic Algorithm (GA) can be of great benefit. However, no tool currently combines the DSM and a GA to solve the clustering problem. This paper describes a new software tool that interfaces a GA written as an Excel macro with a DSM in spreadsheet format. The results of several test cases are included to demonstrate how well this new tool works

    DETECTING CHANGING POLARIZATION STRUCTURES IN SAGITTARIUS A* WITH HIGH FREQUENCY VLBI

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    Sagittarius A* is the source of near infrared, X-ray, radio, and (sub)millimeter emission associated with the supermassive black hole at the Galactic Center. In the submillimeter regime, Sgr A* exhibits time-variable linear polarization on timescales corresponding to <10 Schwarzschild radii of the presumed 4 × 10[superscript 6] M[subscript ☉] black hole. In previous work, we demonstrated the potential for total-intensity (sub)millimeter-wavelength very long baseline interferometry (VLBI) to detect time-variable—and periodic—source structure changes in the Sgr A* black hole system using nonimaging analyses. Here, we extend this work to include full polarimetric VLBI observations. We simulate full-polarization (sub)millimeter VLBI data of Sgr A* using a hot spot model that is embedded within an accretion disk, with emphasis on nonimaging polarimetric data products that are robust against calibration errors. Although the source-integrated linear polarization fraction in the models is typically only a few percent, the linear polarization fraction on small angular scales can be much higher, enabling the detection of changes in the polarimetric structure of Sgr A* on a wide variety of baselines. The shortest baselines track the source-integrated linear polarization fraction, while longer baselines are sensitive to polarization substructures that are beam-diluted by connected-element interferometry. The detection of periodic variability in source polarization should not be significantly affected even if instrumental polarization terms cannot be calibrated out. As more antennas are included in the (sub)millimeter-VLBI array, observations with full polarization will provide important new diagnostics to help disentangle intrinsic source polarization from Faraday rotation effects in the accretion and outflow region close to the black hole event horizon.National Science Foundation (U.S.

    Analysis of an Energetic Electron Injection at GEO Using FalconSEED: A Low SWaP-C, CubeSat-Compatible Instrument for Space Environments

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    We present a detailed analysis of an energetic electron injection (10s - 100s keV) observed at geostationary Earth orbit (GEO) on March 5, 2022 in order to highlight the capabilities of the Falcon Solid-state Energetic Electron Detector (SEED). The high time- and energy-resolution of SEED are used to quantify the dispersion of the injection front and to explore the morphology of the energy distribution throughout the injection encounter. Observations of the same event from nearby platforms are included for context. The SEED is a CubeSat compatible, single element particle telescope, designed to measure 14 to 145keV electrons in GEO. The flight payload has a volume of 10 cm x 10 cm x 20 cm, in a 4.3-kg, 3.4-W package. The SEED was manifested on the Department of Defense (DoD) Space Test Program Satellite—6 (STPSat-6) which was launched in December of 2021 to GEO at 112 W longitude. During the first year of mission operations, the SEED has demonstrated the ability, evidenced in this paper, or a low-resource particle detector comprised of predominantly commercial-off-the-shelf components to provide relevant science observations of the space plasma environment

    Ranking metabolite sets by their activity levels

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    Related metabolites can be grouped into sets in many ways, e.g., by their participation in series of chemical reactions (forming metabolic pathways), or based on fragmentation spectral similarities or shared chemical substructures. Understanding how such metabolite sets change in relation to experimental factors can be incredibly useful in the interpretation and understanding of complex metabolomics data sets. However, many of the available tools that are used to perform this analysis are not entirely suitable for the analysis of untargeted metabolomics measurements. Here, we present PALS (Pathway Activity Level Scoring), a Python library, command line tool, and Web application that performs the ranking of significantly changing metabolite sets over different experimental conditions. The main algorithm in PALS is based on the pathway level analysis of gene expression (PLAGE) factorisation method and is denoted as mPLAGE (PLAGE for metabolomics). As an example of an application, PALS is used to analyse metabolites grouped as metabolic pathways and by shared tandem mass spectrometry fragmentation patterns. A comparison of mPLAGE with two other commonly used methods (overrepresentation analysis (ORA) and gene set enrichment analysis (GSEA)) is also given and reveals that mPLAGE is more robust to missing features and noisy data than the alternatives. As further examples, PALS is also applied to human African trypanosomiasis, Rhamnaceae, and American Gut Project data. In addition, normalisation can have a significant impact on pathway analysis results, and PALS offers a framework to further investigate this. PALS is freely available from our project Web site
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