5,520 research outputs found

    Wall Model Large Eddy Simulation of a Diffusing Serpentine Inlet Duct

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    The modeling focus on serpentine inlet ducts (S-duct), as with any inlet, is to quantify the total pressure recovery and ow distortion after the inlet, which directly impacts the performance of a turbine engine fed by the inlet. Accurate prediction of S-duct ow has yet to be achieved amongst the computational fluid dynamics (CFD) community to improve the reliance on modeling reducing costly testing. While direct numerical simulation of the turbulent ow in an S-duct is too cost prohibitive due to grid scaling with Reynolds number, wall-modeled large eddy simulation (WM-LES) serves as a tractable alternative. US3D, a hypersonic research CFD code developed by University of Minnesota was used with inviscid fluxes calculated using 4th order kinetic-energy consistent schemes by Subbareddy and Candler with a flux limiter by Ducro. The WM-LES model by Komives was applied with a constant Vreman sub grid scale model. The use of higher order numerical models on a fully structured grid were assessed with delayed detached eddy simulation (DDES) and WM-LES turbulence models to obtain increased prediction accuracy of the S-duct ow when compared to previous studies and test data. Further, a first of its kind dynamic Vreman model was derived, implemented, and validated in US3D using a flat plate model

    Emergence of a Dynamic Super-Structural Order Integrating Antiferroelectric and Antiferrodistortive Competing Instabilities in EuTiO3

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    Microscopic structural instabilities of EuTiO3 single crystal were investigated by synchrotron x-ray diffraction. Antiferrodistortive (AFD) oxygen octahedral rotational order was observed alongside Ti derived antiferroelectric (AFE) distortions. The competition between the two instabilities is reconciled through a cooperatively modulated structure allowing both to coexist. The electric and magnetic field effect on the modulated AFD order shows that the origin of large magnetoelectric coupling is based upon the dynamic equilibrium between the AFD - antiferromagnetic interactions versus the electric polarization - ferromagnetic interactions

    Consensus mutagenesis reveals that non-helical regions influence thermal stability of horseradish peroxidase

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    The enzyme horseradish peroxidase has many uses in biotechnology but a stabilized derivative would have even wider applicability. To enhance thermal stability, we applied consensus mutagenesis (used successfully with other proteins) to recombinant horseradish peroxidase and generated five single-site mutants. Unexpectedly, these mutations had greater effects on steady-state kinetics than on thermal stability. Only two mutants (T102A, T110V) marginally exceeded the wild type's thermal stability (4% and 10% gain in half-life at 50 °C respectively); the others (Q106R, Q107D, I180F) were less stable than wild type. Stability of a five-fold combination mutant matched that of Q106R, the least-stable single mutant. These results were perplexing: the Class III plant peroxidases display wide differences in thermal stability, yet the consensus mutations failed to reflect these natural variations. We examined the sequence content of Class III peroxidases to determine if there are identifiable molecular reasons for the stability differences observed. Bioinformatic analysis validated our choice of sites and mutations and generated an archetypal peroxidase sequence for comparison with extant sequences. It seems that both genetic variation and differences in protein stability are confined to non-helical regions due to the presence of a highly conserved alpha-helical structural scaffold in these enzymes

    Shining new light on mammalian diving physiology using wearable near-infrared spectroscopy

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    Investigation of marine mammal dive-by-dive blood distribution and oxygenation has been limited by a lack of non-invasive technology for use in freely diving animals. Here, we developed a non-invasive near-infrared spectroscopy (NIRS) device to measure relative changes in blood volume and haemoglobin oxygenation continuously in the blubber and brain of voluntarily diving harbour seals. Our results show that seals routinely exhibit preparatory peripheral vasoconstriction accompanied by increased cerebral blood volume approximately 15 s before submersion. These anticipatory adjustments confirm that blood redistribution in seals is under some degree of cognitive control that precedes the mammalian dive response. Seals also routinely increase cerebral oxygenation at a consistent time during each dive, despite a lack of access to ambient air. We suggest that this frequent and reproducible reoxygenation pattern, without access to ambient air, is underpinned by previously unrecognised changes in cerebral drainage. The ability to track blood volume and oxygenation in different tissues using NIRS will facilitate a more accurate understanding of physiological plasticity in diving animals in an increasingly disturbed and exploited environment

    Incidental Findings on CT Scans in the Emergency Department

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    Objectives. Incidental findings on computed tomography (CT) scans are common. We sought to examine rates of findings and disclosure among discharged patients who received a CT scan in the ED. Methods. Retrospective chart review (Aug-Oct 2009) of 600 patients age 18 and older discharged home from an urban Level 1 trauma center. CT reports were used to identify incidental findings and discharge paperwork was used to determine whether the patient was informed of these findings. Results. There were 682 CT scans among 600 patients: 199 Abdomen & Pelvis, 405 Head, and 78 Thorax. A total of 348 incidental findings were documented in 228/682 (33.4%) of the scans, of which 34 (9.8%) were reported to patients in discharge paperwork. Patients with 1 incidental finding were less likely to receive disclosure than patients with 2 or more (P = .010). Patients age <60 were less likely to have incidental findings (P < .001). There was no significant disclosure or incidental finding difference by gender. Conclusions. While previous research suggests that CT incidental findings are often benign, reporting to patients is recommended but this is rarely happening

    Data and code associated with “Supporting Adaptive Management with Ecological Forecasting: Chronic Wasting Disease in the Jackson Elk Herd”

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    Final_Data.zip contains several spreadsheets representing data collected by both the Wyoming Game and Fish Department and the US Fish and Wildlife Service for elk management: Jackson feedground census, 1998-2016; Harvest data, 1997-2015; Hunt area census, 1998-2016; Chronic wasting disease test results, 1998-2015. Final_Code.zip contains several Program R scripts written for data analysis and model fitting as described in the full associated article.Adaptive management has emerged as the prevailing approach for combining environmental research and management to advance science and policy. Adaptive management, as originally formulated by Carl Walters in 1986, depends on the use of Bayesian models to provide a framework to accumulate knowledge. The emergence of ecological forecasting using the Bayesian framework has provided robust tools and supports a new approach to informing adaptive management, which can be particularly useful in developing policy for managing infectious disease in wildlife. We used the potential infection of elk populations with chronic wasting disease in the Jackson Valley of Wyoming and the National Elk Refuge as a model system to show how Bayesian forecasting can support adaptive management in anticipation of management challenges. The core of our approach resembles the sex- and age-structured, discrete time models used to support management decisions on elk harvest throughout western North America. Our model differs by including stages for CWD infected and unaffected animals. We used data on population counts, sex and age classification, and CWD testing, as well as results from prior research, in a Bayesian statistical framework to predict model parameters and the number of animals in each age, sex, and disease stage over time. Initial forecasts suggested CWD may reach a mean prevalence in the population of 12%, but uncertainty in this forecast is large and we cannot rule out a mean forecasted prevalence as high as 20%. Using recruitment rates observed during the last two decades, the model predicted that a CWD prevalence of 7% in females would cause the population growth rate (l) to drop below 1, resulting in population declines even when female harvest was zero. The primary value of this ecological forecasting approach is to provide a framework to assimilate data with understanding of disease processes to enable continuous improvement in understanding the ecology of CWD and its management.Data collection was funded as part of management efforts by the Wyoming Game and Fish Department and the US Fish and Wildlife Service. Data analysis and work for publication was funded by the US Fish and Wildlife Service and the National Park Service

    Dietary protein intake is associated with maximal and explosive strength of the leg flexors in young and older blue collar workers

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    The aim of this study was to investigate the association between dietary PRO intake and maximal and rapid strength of the leg flexors in blue collar (BC) working men. Twenty-four young (age=23.2±2.1 yrs), and nineteen older aged (age=52.8±5.2 yrs) men employed in BC occupations completed a three day dietary record and isometric strength testing of the leg flexors. Food logs were analyzed for total protein (TPRO) and essential amino acid (EAA) intake. Rapid and maximal strength capacities were examined from the rate of torque development at 50ms (RTD50) and peak torque (PT) of the torque-time curves, respectively. Pearson correlations and partial correlations were used to examine the relationships between TPRO and EAA intake on strength variables. PT was positively correlated to TPRO and EAA intake in the young (r=0.439 and 0.431;P0.05) between TPRO and strength variables when controlling for EAA intake. TPRO intake explained 20–44% of the variance in rapid and maximal strength for both age groups. EAA intake was largely responsible for the positive relationship between PRO intake and strength. Across young and older aged blue collar working male populations, protein consumption was associated with both maximal and explosive strength capacities of the leg flexors muscle group

    Cyclotron modeling phase-resolved infrared spectroscopy of polars I: EF Eridani

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    We present phase-resolved low resolution infrared spectra of the polar EF Eridani obtained over a period of 2 years with SPEX on the IRTF. The spectra, covering the wavelength range 0.8 to 2.4 microns, are dominated by cyclotron emission at all phases. We use a ``Constant Lambda'' prescription to attempt to model the changing cyclotron features seen in the spectra. A single cyclotron emission component with B = 12.6 MG, and a plasma temperature of kT = 5.0 keV, does a reasonable job in matching the features seen in the H and K bands, but fails to completely reproduce the morphology shortward of 1.6 microns. We find that a two component model, where both components have similar properties, but whose contributions differ with viewing geometry, provides an excellent fit to the data. We discuss the implications of our models and compare them with previously published results. In addition, we show that a cyclotron model with similar properties to those used for modeling the infrared spectra, but with a field strength of B = 115 MG, can explain the GALEX observations of EF Eri.Comment: 25 pages, 5 figures, to appear in Ap
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