2,354 research outputs found

    Discovery of the yellow fever virus

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    Cultural Resources Remote-Sensing Survey Of Areas Adjacent To Shamrock Island, Corpus Christi Bay, Nueces County, Texas

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    Coastal Environments Inc. (CEI) conducted a cultural resources remote-sensing survey of two areas adjacent to Shamrock Island, Nueces County, Texas. The northern-most of these covers 56.38 hectares (139.31 acres), while the southern-most survey area encompasses 44.8 hectares (110.69 acres). These are proposed locations of sand borrow areas to be used by the Nature Conservancy, Texas Coast Office for the Shamrock Island Restoration Project. Data were collected by Naismith Marine of Houston, Texas on December 15th and 17th, 2014 and supervised by the principal investigator and the remotesensing specialist from CEI. Remote-sensing equipment used in the project include a Geometrics 882 cesium magnetometer, an Edgetech 4125 dual frequency side-scan sonar system, and a digital recording fathometer. Positioning was performed with a differential global positioning system (DGPS) with corrections provided by a Virtual Reference Station (VRS). Upon delivery to CEI, additional processing and analysis was performed on the data and relevant archival work performed in order to determine the cultural significance of remote-sensing anomalies. While the remote-sensing data delineate an array of modern oil targets, two targets of possible cultural significance (designated anomalies M11 and M16) were identified. It is recommended that these targets either be avoided or that further investigations are carried out to determine their cultural significance

    The Ethics of Infection Control: Philosophical Frameworks

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    Recent developments that are relevant to the ethics of infection control include the patient safety movement, the appearance of new diseases (notably, severe acute respiratory syndrome) that pose threats to healthcare workers, data confirming the suspicion that infection control measures such as isolation may compromise patient care, and, in philosophy, renewed interest in virtue ethics and communitarianism. We review general ethical frameworks and relevant vocabulary for infection control practitioners and hospital epidemiologists. Frameworks for the ethics of infection control resemble those of public health more than those of clinical medicine but embrace elements of both. The optimum framework, we suggest, takes into account a virtue-based communitarianism. The virtue ethics movement stresses the need to consider not only rules and outcomes but also the character of the individual(s) involved. Communitarianism emphasizes the well-being and values of local communities, best determined by shared, democratic decision making among stakeholders. Brief discussions of 15 consecutive cases illustrate the extent to which the daily practice of infection control poses problems heavily freighted with ethical overtones

    Preventing Deep Wound Infection After Coronary Artery Bypass Grafting: a Review

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    The consequences of deep wound infections before, during, and after coronary artery bypass grafting have prompted research to clarify risk factors and explore preventive measures to keep infection rates at an irreducible minimum. An analysis of 42 studies in which investigators used multivariate logistic regression analysis revealed that diabetes mellitus and obesity are by far the chief preoperative risk factors. A 4-point preoperative scoring system based on a patient\u27s body mass index and the presence or absence of diabetes is one practical way to determine the risk of mediastinitis, and other risk-estimate methods are being refined. Intraoperative risk factors include prolonged perfusion time, the use of one or more internal mammary arteries as grafts, blood transfusion, and mechanical circulatory assistance. The chief postoperative risk factor is reoperation, usually for bleeding. Unresolved issues include the optimal approach to Staphylococcus aureus nasal colonization and the choice of a prophylactic antibiotic regimen. We recommend that cardiac surgery programs supplement their audit processes and ongoing vigilance for infections with periodic, multidisciplinary reviews of best-practice standards for preoperative, intraoperative, and postoperative patient care

    Uncertainty Assessment of the SeaWiFS On-Orbit Calibration

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    Ocean color climate data records require water-leaving radiances with 5% absolute and 1% relative accuracies as input. Because of the amplification of any sensor calibration errors by the atmospheric correction, the 1% relative accuracy requirement translates into a 0.1% long-term radiometric stability requirement for top-of-the atmosphere radiances. The rigorous on-orbit calibration program developed and implemented for SeaWiFS by the NASA Ocean Biology Processing Group (OBPG) Calibration and Validation Team (CVT) has allowed the CVT to maintain the stability of the radiometric calibration of SeaWiFS at 0.13% or better over the mission. The uncertainties in the resulting calibrated top-of-the-atmosphere (TOA) radiances can be addressed in terms of accuracy (biases in the measurements), precision (scatter in the measurements), and stability (repeatability of the measurements). The calibration biases of lunar observations relative to the USGS RObotic Lunar Observatory (ROLO) photometric model of the Moon are 2-3%. The biases from the vicarious calibration against the Marine Optical Buoy (MOBY) are 1-2%. The precision of the calibration derived from the solar calibration signal-tonoise ratios are 0.16%, from the lunar residuals are 0.13%, and from the vicarious gains are 0.10%. The long-term stability of the TOA radiances, derived from the lunar time series, is 0.13%. The stability of the vicariouslycalibrated TOA radiances, incorporating the uncertainties in the MOBY measurements and the atmospheric correction, is 0.30%. These results allow the OBPG to produce climate data records from the SeaWiFS ocean color data

    Maintaining Structural Stability of Poly(lactic acid): Effects of Multifunctional Epoxy based Reactive Oligomers

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    In order to reduce the effects of hydrolytic degradation and to maintain sufficient viscosity during processing of biomass based poly(l-lactic acid) (PLLA), various epoxy functional reactive oligomers have been characterized and incorporated into the degraded fragments as chain extenders. The molecular weight of PLLA increased with the increase in functionality of the reactive oligomers. No further increase in molecular weight was observed for oligomers with functionality of greater than five. Under our experimental conditions, no gelation was found even when the highest functionality reactive oligomers were used. This is attributed to the preferential reaction of the carboxylic acid versus the negligible reactivity of the hydroxyl groups, present at the two ends of the degraded PLLA chains, with the epoxy groups. The study provides a clear understanding of the degradation and chain extension reaction of poly(lactic acid) (PLA) with epoxy functional reactive oligomers. It is also shown that a higher functionality and concentration of the reactive oligomers is needed, to bring about a sufficient increase in the molecular weight and hence the hydrolytic stability in circumstances when PLA chains suffer significant degradation during processing

    Impact of operative indication and surgical complexity on outcomes after thoracic endovascular aortic repair at National Surgical Quality Improvement Program Centers

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    IntroductionThoracic endovascular aortic repair (TEVAR) devices are increasingly being utilized to treat aortic pathologies outside of the original Food & Drug Administration (FDA) approval for nonruptured descending thoracic aorta aneurysms (DTAs). The objective of this study was to evaluate the outcomes of patients undergoing TEVAR, elucidating the role of surgical and pathologic variables on morbidity and mortality.MethodsNational Surgical Quality Improvement Program (NSQIP) data were reviewed for all patients undergoing endovascular thoracic aorta repair from 2005 to 2007. The patients' operative indication and surgical complexity were used to divide them into study and control populations. Comorbid profiles were assessed utilizing a modified Charlson Comorbidity Index (CCI). Thirty-day occurrences of mortality and serious adverse events (SAEs) were used as study endpoints. Univariate and multivariate models were created using demographic and clinical variables to assess for significant differences in endpoints (P ≤ .05).ResultsA total of 440 patients undergoing TEVAR were identified. When evaluating patients based on operative indication, the ruptured population had increased mortality and SAE rates compared to the nonruptured DTA population (22.6% vs 6.2%;P < .01 and 35.5% vs 9.1%;P < .01, respectively). Further analysis by surgical complexity revealed increased mortality and SAE rates when comparing the brachiocephalic aortic debranching population to the noncovered left subclavian artery population (23.1% vs 6.5%; P = .02 and 30.8% vs 9.1%; P < .01, respectively). Multivariate analysis demonstrated that operative indication was not a correlate of mortality or SAEs (odds ratio [OR], 0.95; P = .92 and OR, 1.42; P = .39, respectively); however, brachiocephalic aortic debranching exhibited a deleterious effect on mortality (OR, 8.75; P < .01) and SAE rate (OR, 6.67; P = .01).ConclusionThe operative indication for a TEVAR procedure was not found to be a predictor of poor patient outcome. Surgical complexity, specifically the need for brachiocephalic aortic debranching and aortoiliac conduit, was shown to influence the occurrence of SAEs in a multivariate model. Comparative data, such as these, illustrate real-world outcomes of patients undergoing TEVAR outside of the original FDA-approved indications. This information is of paramount importance to various stakeholders, including third-party payers, the device industry, regulatory agencies, surgeons, and their patients

    Impact of Transfused Citrate on Pathophysiology in Massive Transfusion

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    UNLABELLED: This narrative review article seeks to highlight the effects of citrate on physiology during massive transfusion of the bleeding patient. DATA SOURCES: A limited library of curated articles was created using search terms including citrate intoxication, citrate massive transfusion, citrate pharmacokinetics, hypocalcemia of trauma, citrate phosphate dextrose, and hypocalcemia in massive transfusion. Review articles, as well as prospective and retrospective studies were selected based on their relevance for inclusion in this review. STUDY SELECTION: Given the limited number of relevant studies, studies were reviewed and included if they were written in English. This is not a systematic review nor a meta-analysis. DATA EXTRACTION AND SYNTHESIS: As this is not a meta-analysis, new statistical analyses were not performed. Relevant data were summarized in the body of the text. CONCLUSIONS: The physiologic effects of citrate independent of hypocalcemia are poorly understood. While a healthy individual can rapidly clear the citrate in a unit of blood (either through the citric acid cycle or direct excretion in urine), the physiology of hemorrhagic shock can lead to decreased clearance and prolonged circulation of citrate. The so-called Diamond of Death of bleeding-coagulopathy, acidemia, hypothermia, and hypocalcemia-has a dynamic interaction with citrate that can lead to a death spiral. Hypothermia and acidemia both decrease citrate clearance while circulating citrate decreases thrombin generation and platelet function, leading to ionized hypocalcemia, coagulopathy, and need for further transfusion resulting in a new citrate load. Whole blood transfusion typically requires lower volumes of transfused product than component therapy alone, resulting in a lower citrate burden. Efforts should be made to limit the amount of citrate infused into a patient in hemorrhagic shock while simultaneously addressing the induced hypocalcemia

    Orbital Advection by Interpolation: A Fast and Accurate Numerical Scheme for Super-Fast MHD Flows

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    In numerical models of thin astrophysical disks that use an Eulerian scheme, gas orbits supersonically through a fixed grid. As a result the time step is sharply limited by the Courant condition. Also, because the mean flow speed with respect to the grid varies with position, the truncation error varies systematically with position. For hydrodynamic (unmagnetized) disks an algorithm called FARGO has been developed that advects the gas along its mean orbit using a separate interpolation substep. This relaxes the constraint imposed by the Courant condition, which now depends only on the peculiar velocity of the gas, and results in a truncation error that is more nearly independent of position. This paper describes a FARGO-like algorithm suitable for evolving magnetized disks. Our method is second order accurate on a smooth flow and preserves the divergence-free constraint to machine precision. The main restriction is that the magnetic field must be discretized on a staggered mesh. We give a detailed description of an implementation of the code and demonstrate that it produces the expected results on linear and nonlinear problems. We also point out how the scheme might be generalized to make the integration of other supersonic/super-fast flows more efficient. Although our scheme reduces the variation of truncation error with position, it does not eliminate it. We show that the residual position dependence leads to characteristic radial variations in the density over long integrations.Comment: 32 pages, 18 figures, accepted for publication in The Astrophysical Journal. Contains an additional appendix providing more details for some of the test problems (to be published as an addendum in the ApJS December 2008, v179n2 issue
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