21,015 research outputs found

    Accuracy Assessment of the 2006 National Land Cover Database Percent Impervious Dataset

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    An impervious surface is any surface that prevents water from infiltrating the ground. As impervious surface area increases within watersheds, stream networks and water quality are negatively impacted. The Multi-Resolution Land Characteristic Consortium developed a percent impervious dataset using Landsat imagery as part of the 2006 National Land Cover Database. This percent impervious dataset estimates imperviousness for each 30-meter cell in the land cover database. The percent impervious dataset permits study of impervious surfaces, can be used to identify impacted or critical areas, and allows for development of impact mitigation plans; however, the accuracy of this dataset is unknown. To determine the accuracy of the 2006 percent impervious dataset, reference data were digitized from one-foot digital aerial imagery for three study areas in Arkansas, USA. Digitized reference data were compared to percent impervious dataset estimates of imperviousness at multiple 900m2 , 8,100m2 , and 22,500m2 sample grids to determine if accuracy varied by ground area. Analyses showed percent impervious estimates and digitized reference data differ modestly; however, as ground area increases, percent impervious estimates and reference data match more closely. These findings suggest that the percent impervious dataset is useful for planning purposes for ground areas of at least 2.25ha

    Recruitment of Activation Receptors at Inhibitory NK Cell Immune Synapses

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    Natural killer (NK) cell activation receptors accumulate by an actin-dependent process at cytotoxic immune synapses where they provide synergistic signals that trigger NK cell effector functions. In contrast, NK cell inhibitory receptors, including members of the MHC class I-specific killer cell Ig-like receptor (KIR) family, accumulate at inhibitory immune synapses, block actin dynamics, and prevent actin-dependent phosphorylation of activation receptors. Therefore, one would predict inhibition of actin-dependent accumulation of activation receptors when inhibitory receptors are engaged. By confocal imaging of primary human NK cells in contact with target cells expressing physiological ligands of NK cell receptors, we show here that this prediction is incorrect. Target cells included a human cell line and transfected Drosophila insect cells that expressed ligands of NK cell activation receptors in combination with an MHC class I ligand of inhibitory KIR. The two NK cell activation receptors CD2 and 2B4 accumulated and co-localized with KIR at inhibitory immune synapses. In fact, KIR promoted CD2 and 2B4 clustering, as CD2 and 2B4 accumulated more efficiently at inhibitory synapses. In contrast, accumulation of KIR and of activation receptors at inhibitory synapses correlated with reduced density of the integrin LFA-1. These results imply that inhibitory KIR does not prevent CD2 and 2B4 signaling by blocking their accumulation at NK cell immune synapses, but by blocking their ability to signal within inhibitory synapses

    Tuning electronic structures via epitaxial strain in Sr2IrO4 thin films

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    We have synthesized epitaxial Sr2IrO4 thin-films on various substrates and studied their electronic structures as a function of lattice-strains. Under tensile (compressive) strains, increased (decreased) Ir-O-Ir bond-angles are expected to result in increased (decreased) electronic bandwidths. However, we have observed that the two optical absorption peaks near 0.5 eV and 1.0 eV are shifted to higher (lower) energies under tensile (compressive) strains, indicating that the electronic-correlation energy is also affected by in-plane lattice-strains. The effective tuning of electronic structures under lattice-modification provides an important insight into the physics driven by the coexisting strong spin-orbit coupling and electronic correlation.Comment: 9 pages, 5 figures, 1 tabl

    Protecting participant privacy while maintaining content and context: Challenges in qualitative data De‐identification and sharing

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    The Library Assessment for Research and Scholarship Lab investigates qualitative research support across disciplines. In 2018–2019, the lab conducted 29 interviews with faculty, librarians, and doctoral students who engaged in qualitative research to understand their needs during the research lifecycle. At the conclusion of this project, the qualitative data will be deposited in a repository where it can be made available for future secondary use. The deposited data will include de‐identified versions of the complete interview transcripts. This poster supplements existing de‐identification standards, details drafting and revising protocol for de‐identification of our data, and discusses the de‐identification process we used for the qualitative data. Existing de‐identification literature and standards are limited and not widely uniform in qualitative research. In developing de‐identification protocol, our lab recognized several potential challenges in the process and created procedures to ensure future data usability. There is inherent tension between keeping privacy intact and sharing undistorted qualitative data. We aim to address some of the hazards with de‐identification best practices, demonstrating methodology for producing high quality de‐identified qualitative data. In offering up a test case with suggested methods to better protect participants’ identities, this work will lend itself to sustainable qualitative data sharing and reuse.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163391/2/pra2415_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163391/1/pra2415.pd

    Factor demand linkages, technology shocks, and the business cycle

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    This paper argues that factor demand linkages can be important for the transmission of both sectoral and aggregate shocks. We show this using a panel of highly disaggregated manufacturing sectors together with sectoral structural VARs. When sectoral interactions are explicitly accounted for, a contemporaneous technology shock to all manufacturing sectors implies a positive response in both output and hours at the aggregate level. Otherwise there is a negative correlation, as in much of the existing literature. Furthermore, we find that technology shocks are important drivers of the business cycle

    On Forward J/\psi Production at Fermilab Tevatron

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    The D0 Collaboration has recently reported the measurement of J/\psi production at low angle. We show here that the inclusion of color octet contributions in any framework is able to reproduce this data.Comment: 1 page, Revtex, uses epsfig.sty, 2 postscript figure

    Soft Color Enhancement of the Production of J/psi's by Neutrinos

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    We calculate the production of J/psi mesons by neutrino-nucleon collisions in fixed target experiments. Soft color, often referred to as color evaporation effects, enhance production cross sections due to the contribution of color octet states. Though still small, J/\psi production may be observable in present and future experiments like NuTeV and muon colliders.Comment: 7 pages, Revtex, 4 postscript figures, uses epsfig.st
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