506 research outputs found

    Oxygen transfer during aerobic exercise in a varanid lizard Varanus mertensi is limited by the circulation

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    Oxygen transfer during sustained maximal exercise while locomoting on a treadmill at 0.33 m s(-1) was examined in a varanid lizard Varanus mertensi at 35degreesC. The rate of oxygen consumption ((V)over dot (O 2)) increased with locomotion from 3.49+/-0.75 (mean+/-S.D.) to 14.0+/-4.0 ml O-2 kg(-1) min(-1). Ventilation (V-E) increased, aided by increases in both tidal volume and frequency, in direct proportion to (V)over dot(O 2). The air convection requirement ((V)over dot(E)/(V)over dot(O 2)=27) was therefore maintained, together with arterial Pa-CO 2 and Pa-O 2. The alveolar-arterial P-O 2 difference (PA(O 2)-Pa-O 2) also remained unchanged during exercise from its value at rest, which was approximately 20 mmHg. Pulmonary diffusion for carbon monoxide (0.116+/-0.027 ml kg(-1) min(-1) mmHg(-1)) was double the value previously reported in V. exanthematicus and remained unchanged with exercise. Furthermore, exercise was associated with an increase in the arterial-venous O-2 content difference (Ca-O2-Cv(O 2)), which was assisted by a marked Bohr shift in the hemoglobin saturation curve and further unloading of venous O-2. During exercise the increase in cardiac output ((Q)over dot(tot)) did not match the increase in (V)over dot(O2) such that the blood convection requirement ((Q)over dot(tot)/(V)over dot (O 2)) decreased from the pre-exercise value of approximately 35 to 16 during exercise. Together, the results suggest that ventilation and O-2 transfer across the lung are adequate to meet the aerobic needs of V. mertensi during exercise, but the decrease in the blood convection requirement in the presence of a large arterial-venous O-2 content difference suggests that a limit in the transport of O-2 is imposed by the circulation

    Utilizing ISS Camera Systems for Scientific Analysis of Lightning Characteristics and Comparison with ISS-LIS and GLM

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    Video and still frame images from cameras aboard the International Space Station (ISS) are used to inspire, educate, and provide a unique vantage point from low-Earth orbit that is second to none; however, these cameras have overlooked capabilities for contributing to scientific analysis of the Earth and near-space environment. The goal of this project is to study how geo referenced video/images from available ISS camera systems can be useful for scientific analysis, using lightning properties as a demonstration

    Characteristics of Lightning Within Electrified Snowfall Events Using Lightning Mapping Arrays

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    This study examined 34 lightning flashes within four separate thundersnow events derived from lightning mapping arrays (LMAs) in northern Alabama, central Oklahoma, and Washington, DC. The goals were to characterize the in-cloud component of each lightning flash, as well as the correspondence between the LMA observations and lightning data taken from national lightning networks like the National Lightning Detection Network (NLDN). Individual flashes were examined in detail to highlight several observations within the dataset. The study results demonstrated that the structures of these flashes were primarily normal polarity. The mean area encompassed by this set of flashes is 375 square kilometers, with a maximum flash extent of 2300 square kilometers, a minimum of 3 square kilometers, and a median of 128 square kilometers. An average of 2.29 NLDN flashes were recorded per LMA-derived lightning flash. A maximum of 11 NLDN flashes were recorded in association with a single LMA-derived flash on 10 January 2011. Additionally, seven of the 34 flashes in the study contain zero NLDN identified flashes. Eleven of the 34 flashes initiated from tall human-made objects (e.g., communication towers). In at least six lightning flashes, the NLDN detected a return stroke from the cloud back to the tower and not the initial upward leader. This study also discusses lightning's interaction with the human built environment and provides an example of lightning within heavy snowfall observed by GOES-16's Geostationary Lightning Mapper

    Severe Acute Respiratory Syndrome Coronavirus nsp9 Dimerization Is Essential for Efficient Viral Growth

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    The severe acute respiratory syndrome coronavirus (SARS-CoV) devotes a significant portion of its genome to producing nonstructural proteins required for viral replication. SARS-CoV nonstructural protein 9 (nsp9) was identified as an essential protein with RNA/DNA-binding activity, and yet its biological function within the replication complex remains unknown. Nsp9 forms a dimer through the interaction of parallel α-helices containing the protein-protein interaction motif GXXXG. In order to study the role of the nsp9 dimer in viral reproduction, residues G100 and G104 at the helix interface were targeted for mutation. Multi-angle light scattering measurements indicated that G100E, G104E, and G104V mutants are monomeric in solution, thereby disrupting the dimer. However, electrophoretic mobility assays revealed that the mutants bound RNA with similar affinity. Further experiments using fluorescence anisotropy showed a 10-fold reduction in RNA binding in the G100E and G104E mutants, whereas the G104V mutant had only a 4-fold reduction. The structure of G104E nsp9 was determined to 2.6-Å resolution, revealing significant changes at the dimer interface. The nsp9 mutations were introduced into SARS-CoV using a reverse genetics approach, and the G100E and G104E mutations were found to be lethal to the virus. The G104V mutant produced highly debilitated virus and eventually reverted back to the wild-type protein sequence through a codon transversion. Together, these data indicate that dimerization of SARS-CoV nsp9 at the GXXXG motif is not critical for RNA binding but is necessary for viral replication

    Hospital nurse-staffing models and patient- and staff-related outcomes

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    Background: Nurses comprise the largest component of the health workforce worldwide and numerous models of workforce allocation and profile have been implemented. These include changes in skill mix, grade mix or qualification mix, staff‐allocation models, staffing levels, nursing shifts, or nurses’ work patterns. This is the first update of our review published in 2011. Objectives: The purpose of this review was to explore the effect of hospital nurse‐staffing models on patient and staff‐related outcomes in the hospital setting, specifically to identify which staffing model(s) are associated with: 1) better outcomes for patients, 2) better staff‐related outcomes, and, 3) the impact of staffing model(s) on cost outcomes. Search methods: CENTRAL, MEDLINE, Embase, two other databases and two trials registers were searched on 22 March 2018 together with reference checking, citation searching and contact with study authors to identify additional studies. Selection criteria: We included randomised trials, non‐randomised trials, controlled before‐after studies and interrupted‐time‐series or repeated‐measures studies of interventions relating to hospital nurse‐staffing models. Participants were patients and nursing staff working in hospital settings. We included any objective reported measure of patient‐, staff‐related, or economic outcome. The most important outcomes included in this review were: nursing‐staff turnover, patient mortality, patient readmissions, patient attendances at the emergency department (ED), length of stay, patients with pressure ulcers, and costs. Data collection and analysis: We worked independently in pairs to extract data from each potentially relevant study and to assess risk of bias and the certainty of the evidence. Main results: We included 19 studies, 17 of which were included in the analysis and eight of which we identified for this update. We identified four types of interventions relating to hospital nurse‐staffing models: introduction of advanced or specialist nurses to the nursing workforce; introduction of nursing assistive personnel to the hospital workforce; primary nursing; and staffing models. The studies were conducted in the USA, the Netherlands, UK, Australia, and Canada and included patients with cancer, asthma, diabetes and chronic illness, on medical, acute care, intensive care and long‐stay psychiatric units. The risk of bias across studies was high, with limitations mainly related to blinding of patients and personnel, allocation concealment, sequence generation, and blinding of outcome assessment. The addition of advanced or specialist nurses to hospital nurse staffing may lead to little or no difference in patient mortality (3 studies, 1358 participants). It is uncertain whether this intervention reduces patient readmissions (7 studies, 2995 participants), patient attendances at the ED (6 studies, 2274 participants), length of stay (3 studies, 907 participants), number of patients with pressure ulcers (1 study, 753 participants), or costs (3 studies, 617 participants), as we assessed the evidence for these outcomes as being of very low certainty. It is uncertain whether adding nursing assistive personnel to the hospital workforce reduces costs (1 study, 6769 participants), as we assessed the evidence for this outcome to be of very low certainty. It is uncertain whether primary nursing (3 studies, > 464 participants) or staffing models (1 study, 647 participants) reduces nursing‐staff turnover, or if primary nursing (2 studies, > 138 participants) reduces costs, as we assessed the evidence for these outcomes to be of very low certainty. Authors' conclusions: The findings of this review should be treated with caution due to the limited amount and quality of the published research that was included. We have most confidence in our finding that the introduction of advanced or specialist nurses may lead to little or no difference in one patient outcome (i.e. mortality) with greater uncertainty about other patient outcomes (i.e. readmissions, ED attendance, length of stay and pressure ulcer rates). The evidence is of insufficient certainty to draw conclusions about the effectiveness of other types of interventions, including new nurse‐staffing models and introduction of nursing assistive personnel, on patient, staff and cost outcomes. Although it has been seven years since the original review was published, the certainty of the evidence about hospital nurse staffing still remains very low

    Comparing rates of adverse events detected in incident reporting and the Global Trigger Tool: a systematic review

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    Many hospitals continue to use incident reporting systems (IRSs) as their primary patient safety data source. The information IRSs collect on the frequency of harm to patients [adverse events (AEs)] is generally of poor quality, and some incident types (e.g. diagnostic errors) are under-reported. Other methods of collecting patient safety information using medical record review, such as the Global Trigger Tool (GTT), have been developed. The aim of this study was to undertake a systematic review to empirically quantify the gap between the percentage of AEs detected using the GTT to those that are also detected via IRSs. The review was conducted in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Studies published in English, which collected AE data using the GTT and IRSs, were included. In total, 14 studies met the inclusion criteria. All studies were undertaken in hospitals and were published between 2006 and 2022. The studies were conducted in six countries, mainly in the USA (nine studies). Studies reviewed 22 589 medical records using the GTT across 107 institutions finding 7166 AEs. The percentage of AEs detected using the GTT that were also detected in corresponding IRSs ranged from 0% to 37.4% with an average of 7.0% (SD 9.1; median 3.9 and IQR 5.2). Twelve of the fourteen studies found 10-fold gap between the detection rates of the GTT and IRSs is strong evidence that the rate of AEs collected in IRSs in hospitals should not be used to measure or as a proxy for the level of safety of a hospital. IRSs should be recognized for their strengths which are to detect rare, serious, and new incident types and to enable analysis of contributing and contextual factors to develop preventive and corrective strategies. Health systems should use multiple patient safety data sources to prioritize interventions and promote a cycle of action and improvement based on data rather than merely just collecting and analysing information

    Preliminary Results on HAT-P-4, TrES-3, XO-2, and GJ 436 from the NASA EPOXI Mission

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    EPOXI (EPOCh + DIXI) is a NASA Discovery Program Mission of Opportunity using the Deep Impact flyby spacecraft. The EPOCh (Extrasolar Planet Observation and Characterization) Science Investigation will gather photometric time series of known transiting exoplanet systems from January through August 2008. Here we describe the steps in the photometric extraction of the time series and present preliminary results of the first four EPOCh targets.Comment: 4 pages, 2 figures. To appear in the Proceedings of the 253rd IAU Symposium: "Transiting Planets", May 2008, Cambridge, M
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