1,100 research outputs found

    Cosmic String Spacetime in Dilaton Gravity and Flat Rotation Curves

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    In dilaton gravity theories, we consider a string-like topological defect formed during U(1) gauge symmetry-breaking phase transition in the early Universe, and far from the cosmic string we have vacuum solutions of the generalized Einstein equation. We discuss how they can be related to the flatness of galactic rotation curves.Comment: 9 pages, RevTeX4 fil

    Antimicrobial stewardship practices in Virginia

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    The Society of Healthcare Epidemiology of America, the Centers for Disease Control and Prevention, and the President\u27s Council of Advisors on Science and Technology recognize the need to combat antimicrobial resistance through the promotion of antimicrobial stewardship programs. Health care facilities in Virginia were surveyed using a 23-item survey focused on facility characteristics and antimicrobial stewardship strategies. Antimicrobial stewardship activities were highly variable and many are missing key personnel and resources

    Structural Forecasting for Short-term Tropical Cyclone Intensity Guidance

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    Because geostationary satellite (Geo) imagery provides a high temporal resolution window into tropical cyclone (TC) behavior, we investigate the viability of its application to short-term probabilistic forecasts of TC convective structure to subsequently predict TC intensity. Here, we present a prototype model which is trained solely on two inputs: Geo infrared imagery leading up to the synoptic time of interest and intensity estimates up to 6 hours prior to that time. To estimate future TC structure, we compute cloud-top temperature radial profiles from infrared imagery and then simulate the evolution of an ensemble of those profiles over the subsequent 12 hours by applying a Deep Autoregressive Generative Model (PixelSNAIL). To forecast TC intensities at hours 6 and 12, we input operational intensity estimates up to the current time (0 h) and simulated future radial profiles up to +12 h into a ``nowcasting'' convolutional neural network. We limit our inputs to demonstrate the viability of our approach and to enable quantification of value added by the observed and simulated future radial profiles beyond operational intensity estimates alone. Our prototype model achieves a marginally higher error than the National Hurricane Center's official forecasts despite excluding environmental factors, such as vertical wind shear and sea surface temperature. We also demonstrate that it is possible to reasonably predict short-term evolution of TC convective structure via radial profiles from Geo infrared imagery, resulting in interpretable structural forecasts that may be valuable for TC operational guidance

    The virtual peripheral nerve academy: education for the identification and treatment of peripheral nerve disorders

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    Millions of people around the globe suffer peripheral nerve injuries caused by trauma and medical disorders. However, medical school curricula are profoundly deficient in peripheral nerve education. This lack of knowledge within the healthcare profession may cause inadequate patient care. We developed the Virtual Peripheral Nerve Academy (VPNA) as a reusable virtual learning environment to provide medical students with detailed education on the peripheral nervous system (PNS). Students are introduced to the PNS through virtual 3D rendering of the human body, wherein they visualize individual nerves through dissection and observe normal motor and sensory function associated with each nerve. PNS structures that are absent from traditional texts are included in this visualization, ranging from the innervation of joints to the normal anatomic variation required for differential diagnosis of pain after an injury. Detailed modules on peripheral nerve disorders allow students to observe pathophysiological mechanisms, associated symptomatology, and appropriate treatments. Students are briefed on a patient clinical case, then interact with a patient avatar to learn the appropriate diagnostics, including physical exam maneuvers and electrodiagnostic testing. Interactive modules on peripheral nerve surgeries detail surgical techniques. The VPNA data and analytics dashboards allow medical students and course instructors to assess skill improvement and identify specific learning needs. The built-in learner management system and availability on both computer-based and virtual reality platforms facilitate integration into any existing medical school curricula. Ultimately, this immersive technology enables every medical student to learn about the peripheral nervous system and gain competency in treating real-life nerve pathologies

    Phytoplankton blooms weakly influence the cloud forming ability of sea spray aerosol

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    After many field studies, the establishment of connections between marine microbiological processes, sea spray aerosol (SSA) composition, and cloud condensation nuclei (CCN) has remained an elusive challenge. In this study, we induced algae blooms to probe how complex changes in seawater composition impact the ability of nascent SSA to act as CCN, quantified by using the apparent hygroscopicity parameter (Îșapp). Throughout all blooms, Îșapp ranged between 0.7 and 1.4 (average 0.95 ± 0.15), consistent with laboratory investigations using algae‐produced organic matter, but differing from climate model parameterizations and in situ SSA generation studies. The size distribution of nascent SSA dictates that changes in Îșapp associated with biological processing induce less than 3% change in expected CCN concentrations for typical marine cloud supersaturations. The insignificant effect of hygroscopicity on CCN concentrations suggests that the SSA production flux and/or secondary aerosol chemistry may be more important factors linking ocean biogeochemistry and marine clouds.Key PointsChanges in seawater and sea spray composition did not strongly affect expected CCN concentrationsBlooms may impact clouds more strongly through changes in aerosol flux or secondary chemistryModel parameterizations likely overestimate changes in cloud nuclei due to primary marine organicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/1/grl54978_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/2/grl54978-sup-0001-supinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/3/grl54978.pd

    Multiple Phosphorylation of Rhodopsin and the In Vivo Chemistry Underlying Rod Photoreceptor Dark Adaptation

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    AbstractDark adaptation requires timely deactivation of phototransduction and efficient regeneration of visual pigment. No previous study has directly compared the kinetics of dark adaptation with rates of the various chemical reactions that influence it. To accomplish this, we developed a novel rapid-quench/mass spectrometry-based method to establish the initial kinetics and site specificity of light-stimulated rhodopsin phosphorylation in mouse retinas. We also measured phosphorylation and dephosphorylation, regeneration of rhodopsin, and reduction of all-trans retinal all under identical in vivo conditions. Dark adaptation was monitored by electroretinography. We found that rhodopsin is multiply phosphorylated and then dephosphorylated in an ordered fashion following exposure to light. Initially during dark adaptation, transduction activity wanes as multiple phosphates accumulate. Thereafter, full recovery of photosensitivity coincides with regeneration and dephosphorylation of rhodopsin

    Novel Interventions for HIV Self-Management in African American Women: A Systematic Review of mHealth Interventions

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    The purpose of this systematic review was to assess the quality of interventions using mobile health (mHealth) technology being developed for and trialed with HIV-infected African American (AA) women. We aimed to assess rigor and to ascertain if these interventions have been expanded to include the broad domain of self-management. After an extensive search using the PRISMA approach and reviewing 450 records (411 published studies and 39 ongoing trials atclinicaltrials.gov), we found little completed research that tested mHealth HIV self-management interventions for AA women. Atclinicaltrials.gov, we found several mHealth HIV intervention studies designed for women in general, forecasting a promising future. However, most studies were exploratory in nature and focused on a single narrow outcome, such as medication adherence. Given that cultural adaptation is the key to successfully implementing any effective self-management intervention, culturally relevant, gender-specific mHealth interventions focusing on HIV-infected AA women are warranted for the future
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