1,783 research outputs found

    Theory of the Injun 5 VLF Poynting flux measurements

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    VLF Poynting flux measurement technique used on Injun 5 satellit

    Crystal Structures of Influenza A Virus Matrix Protein M1: Variations on a Theme

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    Matrix protein 1 (M1) of the influenza A virus plays multiple roles in virion assembly and infection. Interest in the pH dependence of M1\u27s multiple functions led us to study the effect of subtle pH changes on M1 structure, resulting in the elucidation of a unique low-pH crystal structure of the N1-165-domain of A/WSN/33 (H1N1) M1 that has never been reported. Although the 2.2 Å crystal structure of M1 N-terminus shows a dimer with the two monomers interacting in a face-to-face fashion at low pH as observed earlier, a 44° rotation of the second monomer has led to a significantly different dimer interface that possibly affects dimer stability. More importantly, while one of the monomers is fully defined, the N-terminal half of the second monomer shows considerable disorder that appears inherent in the protein and is potentially physiologically relevant. Such disorder has not been observed in any other previously reported structure at either low or high pH conditions, despite similar crystallization pH conditions. By comparing our novel N1-165-domain structure with other low-pH or neutral-pH M1 structures, it appears that M1 can energetically access different monomer and dimer conformations, as well as oligomeric states, with varying degree of similarities. The study reported here provides further insights into M1 oligomerization that may be essential for viral propagation and infectivity

    In-office diagnostic arthroscopy for knee and shoulder intra-articular injuries its potential impact on cost savings in the United States

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    BACKGROUND: The purpose of this analysis was to determine whether in office diagnostic needle arthroscopy (Visionscope Imaging System [VSI]) can provide for improved diagnostic assessment and; more cost effective care. METHODS: Data on arthroscopy procedures in the US for deep seated pathology in the knee and shoulder were used (Calendar Year 2012). These procedures represent approximately 25-30% of all arthroscopic procedures performed annually. Sensitivities, specificities, positive predictive, and negative predictive values for MRI analysis of this deep seated pathology from systematic reviews and meta-analyses were used in assessing for false positive and false negative MRI findings. The costs of performing diagnostic and surgical arthroscopy procedures (using 2013 Medicare reimbursement amounts); costs associated with false negative findings; and the costs for treating associated complications arising from diagnostic and therapeutic arthroscopy procedures were then assessed. RESULTS: In patients presenting with medial meniscal pathology (ICD9CM diagnosis 836.0 over 540,000 procedures in CY 2012); use of the VSI system in place of MRI assessment (standard of care) resulted in a net cost savings to the system of 151million.Inpatientspresentingwithrotatorcuffpathology(ICD9CM840.4over165,000proceduresinCY2012);useofVSIinplaceofMRIsimilarlysaved151 million. In patients presenting with rotator cuff pathology (ICD9CM 840.4 over 165,000 procedures in CY2012); use of VSI in place of MRI similarly saved 59 million. These savings were realized along with more appropriate care as; fewer patients were exposed to higher risk surgical arthroscopic procedures. CONCLUSIONS: The use of an in-office arthroscopy system can: possibly save the US healthcare system money; shorten the diagnostic odyssey for patients; potentially better prepare clinicians for arthroscopic surgery (when needed) and; eliminate unnecessary outpatient arthroscopy procedures, which commonly result in surgical intervention

    VLF electric and magnetic fields observed in the auroral zone with the Javelin 8.46 sounding rocket

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    VLF electric and magnetic fields observed in auroral zone with Javelin 8.46 sounding rocke

    Paradigm of Factors That Affect the Use Of.The Computer as an Instructional Medium

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    In tryihg to find a base for analyzing the lack of acceptance of the computer as an instructional medium, the writer found no adequate research or theory.base available. Therefore, this research set out to create a basis for finding the reason or reasons for the lack of acceptance of the computer. In the process of developing the questionnaire, a paradigm to describe the factors affecting computer use as an instructional medium was produced. This paradigm provides a basis for developing a theory of inhibitions in its most general sense. In a more limited sense, it can serve to detect whether teachers in a school system are likely to use the computer or not. This dissertation presents a rough outline and start on the paradigm in Chapter I. Chapter II presents the.literature from which the paradigm is developed. The third chapter summarizes the literature and presents the interview schedule. Chapter IV reports the case studies that were developed from the interviews. Chapter V contains a summary of the interview results and a presentation of the improved paradigm. Chapter VI presents the development of the questionnaire including its relation to the interviews and the paradigm. The last chapter includes a summary of the dissertation, implications of the research, and recommendations that resulted from this research.Educational Administratio

    On the Specificity of Heparin/Heparan Sulfate Binding to Proteins. Anion-Binding Sites on Antithrombin and Thrombin Are Fundamentally Different

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    Background The antithrombin–heparin/heparan sulfate (H/HS) and thrombin–H/HS interactions are recognized as prototypic specific and non-specific glycosaminoglycan (GAG)–protein interactions, respectively. The fundamental structural basis for the origin of specificity, or lack thereof, in these interactions remains unclear. The availability of multiple co-crystal structures facilitates a structural analysis that challenges the long-held belief that the GAG binding sites in antithrombin and thrombin are essentially similar with high solvent exposure and shallow surface characteristics. Methodology Analyses of solvent accessibility and exposed surface areas, gyrational mobility, symmetry, cavity shape/size, conserved water molecules and crystallographic parameters were performed for 12 X-ray structures, which include 12 thrombin and 16 antithrombin chains. Novel calculations are described for gyrational mobility and prediction of water loci and conservation. Results The solvent accessibilities and gyrational mobilities of arginines and lysines in the binding sites of the two proteins reveal sharp contrasts. The distribution of positive charges shows considerable asymmetry in antithrombin, but substantial symmetry for thrombin. Cavity analyses suggest the presence of a reasonably sized bifurcated cavity in antithrombin that facilitates a firm ‘hand-shake’ with H/HS, but with thrombin, a weaker ‘high-five’. Tightly bound water molecules were predicted to be localized in the pentasaccharide binding pocket of antithrombin, but absent in thrombin. Together, these differences in the binding sites explain the major H/HS recognition characteristics of the two prototypic proteins, thus affording an explanation of the specificity of binding. This provides a foundation for understanding specificity of interaction at an atomic level, which will greatly aid the design of natural or synthetic H/HS sequences that target proteins in a specific manner

    Elevated CO\u3csub\u3e2\u3c/sub\u3e Enhances Productivity and the C/N Ratio of Grasses in the Colorado Shortgrass Steppe

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    Atmospheric CO2 concentrations have been increasing since the industrial revolution, and are projected to double within this century over today\u27s concentration of 360 µmol mol-1 . This study used six open-top chambers in the Colorado, USA shortgrass steppe to investigate how increasing CO2 will affect productivity and C and N status of indigenous perennial grasses and forbs. From March until October, chambers were placed on two plots in each of the three blocks. In each block, one chamber was assigned an ambient CO2 treatment (~360 µmol mol-1), the other an elevated CO2 treatment (~720 µmol mol-1). Each block also had an unchambered control plot. Growth under elevated CO2 increased above-ground phytomass an average 31% in 1997 and 47% in 1998, with no differences in relative growth responses of C3 and C4 grasses and forbs. Growth in chambers was greater than non-chambered control plots, presumably due to warmer temperatures in chambers and a longer growing season. Shoot N concentrations were reduced 21% and C/N ratios increased 23% in elevated compared to ambient chambers. Variation in aboveground phytomass due to year, CO2 and chamber effects correlated well to % shoot N and C/N ratios, although for both traits different regression lines were required for green plant material (harvested in July) and senescent plant material (harvested in October). Results suggest increased growth and reduced N concentrations in this mixed C3/C4 grassland in an elevated CO2 environment

    CELLULAR REQUIREMENTS FOR THE PRIMARY IN VITRO ANTIBODY RESPONSE TO DNP-FICOLL

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    The cellular requirements for the primary in vitro IgM and IgG response to dinitrophenyl-substituted Ficoll were examined. Neither thymus-derived lymphocytes nor macrophage-rich splenic adherent cells were required for anti-DNP antibody synthesis. DNP-Ficoll is therefore tentatively classified as a "thymic-independent" antigen

    Initial observations of VLF electric and magnetic fields with the Injun 5 satellite

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    Very low frequency electric and magnetic field observations by Injun 5 satellit
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