2,191 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

    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

    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

    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

    Fludarabine as a cost-effective adjuvant to enhance engraftment of human normal and malignant hematopoiesis in immunodeficient mice

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    There is still an unmet need for xenotransplantation models that efficiently recapitulate normal and malignant human hematopoiesis. Indeed, there are a number of strategies to generate humanized mice and specific protocols, including techniques to optimize the cytokine environment of recipient mice and drug alternatives or complementary to the standard conditioning regimens, that can be significantly modulated. Unfortunately, the high costs related to the use of sophisticated mouse models may limit the application of these models to studies that require an extensive experimental design. Here, using an affordable and convenient method, we demonstrate that the administration of fludarabine (FludaraTM) promotes the extensive and rapid engraftment of human normal hematopoiesis in immunodeficient mice. Quantification of human CD45+ cells in bone marrow revealed approximately a 102-fold increase in mice conditioned with irradiation plus fludarabine. Engrafted cells in the bone marrow included hematopoietic stem cells, as well as myeloid and lymphoid cells. Moreover, this model proved to be sufficient for robust reconstitution of malignant myeloid hematopoiesis, permitting primary acute myeloid leukemia cells to engraft as early as 8 weeks after the transplant. Overall, these results present a novel and affordable model for engraftment of human normal and malignant hematopoiesis in immunodeficient mice

    Coronagraphic Wavefront Control for the ATLAST-9.2m Telescope

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    The Advanced Technology for Large Aperture Space Telescope (ATLAST) concept was assessed as one of the NASA Astrophysics Strategic Mission Concepts (ASMC) studies. Herein we discuss the 9.2-meter diameter segmented aperture version and its wavefront sensing and control (WFSC) with regards to coronagraphic detection and spectroscopic characterization of exoplanets. The WFSC would consist of at least two levels of sensing and control: (i) an outer coarser level of sensing and control to phase and control the segments and secondary mirror in a manner similar to the James Webb Space Telescope but operating at higher temporal bandwidth, and (ii) an inner, coronagraphic instrument based, fine level of sensing and control for both amplitude and wavefront errors operating at higher temporal bandwidths. The outer loop would control rigid-body actuators on the primary and secondary mirrors while the inner loop would control one or more segmented deformable mirror to suppress the starlight within the coronagraphic field-of view. Herein we discuss the visible nulling coronagraph (VNC) and the requirements it levies on wavefront sensing and control and show the results of closed-loop simulations to assess performance and evaluate the trade space of system level stability versus control bandwidth

    Topically Applied Recombinant Chemokine Analogues Fully Protect Macaques from Vaginal Simian-Human Immunodeficiency Virus Challenge

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    Effective strategies for preventing human immunodeficiency virus infection are urgently needed, but recent failures in key clinical trials of vaccines and microbicides highlight the need for new approaches validated in relevant animal models. Here, we show that 2 new chemokine (C-C motif) receptor 5 inhibitors, 5P12-RANTES (regulated on activation, normal T cell expressed and secreted) and 6P4-RANTES, fully protect against infection in the rhesus vaginal challenge model. These highly potent molecules, which are amenable to low-cost production, represent promising new additions to the microbicides pipelin

    Nitrate stable isotopes and major ions in snow and ice samples from four Svalbard sites

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    Increasing reactive nitrogen (N-r) deposition in the Arctic may adversely impact N-limited ecosystems. To investigate atmospheric transport of N-r to Svalbard, Norwegian Arctic, snow and firn samples were collected from glaciers and analysed to define spatial and temporal variations (1 10 years) in major ion concentrations and the stable isotope composition (delta N-15 and delta O-18) of nitrate (NO3-) across the archipelago. The delta N-15(NO3-) and delta O-18(NO3-) averaged -4 parts per thousand and 67 parts per thousand in seasonal snow (2010-11) and -9 parts per thousand and 74 parts per thousand in firn accumulated over the decade 2001-2011. East-west zonal gradients were observed across the archipelago for some major ions (non-sea salt sulphate and magnesium) and also for delta N-15(NO3-) and delta O-18(NO3-) in snow, which suggests a different origin for air masses arriving in different sectors of Svalbard. We propose that snowfall associated with long-distance air mass transport over the Arctic Ocean inherits relatively low delta N-15(NO3-) due to in-transport N isotope fractionation. In contrast, faster air mass transport from the north-west Atlantic or northern Europe results in snowfall with higher delta N-15(NO3-) because in-transport fractionation of N is then time-limited

    A Future Large-Aperture UVOIR Space Observatory: Key Technologies and Capabilities

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    We present the key technologies and capabilities that will enable a future, large-aperture ultravioletopticalinfrared (UVOIR) space observatory. These include starlight suppression systems, vibration isolation and control systems, lightweight mirror segments, detector systems, and mirror coatings. These capabilities will provide major advances over current and near-future observatories for sensitivity, angular resolution, and starlight suppression. The goals adopted in our study for the starlight suppression system are 10-10 contrast with an inner working angle of 20 milliarcsec and broad bandpass. We estimate that a vibration and isolation control system that achieves a total system vibration isolation of 140 dB for a vibration-isolated mass of 5000 kg is required to achieve the high wavefront error stability needed for exoplanet coronagraphy. Technology challenges for lightweight mirror segments include diffraction-limited optical quality and high wavefront error stability as well as low cost, low mass, and rapid fabrication. Key challenges for the detector systems include visible-blind, high quantum efficiency UV arrays, photon counting visible and NIR arrays for coronagraphic spectroscopy and starlight wavefront sensing and control, and detectors with deep full wells with low persistence and radiation tolerance to enable transit imaging and spectroscopy at all wavelengths. Finally, mirror coatings with high reflectivity ( 90), high uniformity ( 1) and low polarization ( 1) that are scalable to large diameter mirror substrates will be essential for ensuring that both high throughput UV observations and high contrast observations can be performed by the same observatory
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