4,071 research outputs found

    Master of Science

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    thesisUntethered magnetic devices such as magnetic capsule endoscopes, magnetic swimming microrobots, and magnetic screws, as well as tethered magnetic devices such as magnet-tipped catheters and magnet-tipped cochlear-implant electrode arrays, can be actuate

    Alien Registration- Wright, Samuel E. (Houlton, Aroostook County)

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    https://digitalmaine.com/alien_docs/34921/thumbnail.jp

    Multiscale sequentially-coupled fsi computation in parachute modeling

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    We describe how the spatially multiscale Sequentially-Coupled Fluid–Structure Interaction (SCFSI) techniques we have developed, specifically the “SCFSI M2C”, which is spatially multiscale for the structural mechanics part, can be used for increasing the accuracy of the membrane and cable structural mechanics solution in parachute FSI computations. The SCFSI M2C technique is used here in conjunction with the Stabilized Space–Time FSI (SSTFSI) technique, which was developed and improved over the years by the Team for Advanced Flow Simulation and Modeling (T AFSM) and serves as the core numerical technology, and a number of special parachute FSI techniques developed by the T AFSM in conjunction with the SSTFSI technique

    Advanced fluid-structure interaction techniques for modeling ringsail parachutes

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    The Team for Advanced Flow Simulation and Modeling (T☆FSM) at Rice University specializes in developing fluid-structure interaction (FSI) modeling techniques for several classes of challenging problems including geometrically complex parachutes. Current modeling technologies are expanded upon with emphasis placed on more realistic FSI modeling of the Orion spacecraft ringsail parachutes. A method for generating a starting condition that matches NASA drop test data and allows for a fair comparison of design variations is introduced. The effect of the geometric porosity distribution on parachute performance and stability is analyzed for three parachute configurations. Rotationally periodic computations that model flow past the complex canopy geometry are presented. Fabric and geometric porosity coefficients are calculated for an improved FSI porosity model. A spatially multiscale technique is used to compare fabric stresses with and without a vent hoop

    Gompertz-Laird model prediction of optimum utilization of crude protein and metabolizable energy by French guinea fowl broilers

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    This study was conducted to assess the influence of dietary CP and ME on growth parameters of the French guinea fowl, a meat-type variety. In a 2 × 3 × 3 factorial arrangement, 297 one-day-old French guinea keets (162 females and 135 males) were randomly assigned to experimental diets comprising 3,050, 3,100, and 3,150 kcal of ME/kg, each containing 21, 23, and 25% CP from hatch to 4 wk of age (WOA), and 3,100, 3150, and 3,200 kcal of ME/kg, each containing 19, 21, and 23% CP at 5 to 8 WOA. Using BW and G:F data from hatch to 8 WOA, the Gompertz-Laird growth model was employed to estimate growth patterns of the French guinea fowl. Mean differences in exponential growth rate, age of maximum growth, and asymptotic BW among dietary CP and ME levels were not significant. However, instantaneous growth rate and weight at inflection point were significantly higher (P \u3c 0.05) in birds on the 25% CP diet than those on the 21% CP diet at hatch to 4 WOA (1.12 kg/wk and 0.79 kg vs. 1.04 kg/wk and 0.74 kg, respectively). The exponential growth rate was also higher (P \u3c 0.05) in birds fed the 3,050 kcal of ME/kg diet with either 23 or 25% CP than those fed diets containing 3,050 kcal of ME/kg and 21% CP. Mean G:F was higher (P \u3c 0.05) in birds fed diets containing 3,050 kcal of ME/kg and either 21 or 23% CP than those in other dietary treatments. Therefore, based on the Gompertz-Laird growth model estimates, feeding 21 and 23% CP and 3,100 kcal of ME/kg at hatch to 4 WOA and 19 and 21% CP with 3,150 kcal of ME/kg at 5 to 8 WOA can be recommended as adequate for growth for the French guinea fowl broilers

    The effect of floor density on growth performance and carcass characteristics of French guinea broilers

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    The floor density required for optimal growth performance of different avian species and varieties is highly variable. Little is known of the required floor density for optimum performance of the French guinea fowl (Numida meleagris) broiler. The objective of this study was to assess the effect of varying floor densities on growth performance and carcass characteristics of the French guinea broiler. In 3 replicates, 687 one-day-old French guinea keets were weighed individually and randomly assigned to floor pens covered with pine wood shavings at 69, 60, 53, and 47 birds/pen, equivalent to densities of 15.6, 13.6, 12, and 10.7 birds/m2, respectively. Birds in these floor densities were allowed feeder space of 2.7, 3.1, 3.5, and 4 cm/bird, respectively, and water space of 1.4, 1.6, 1.8, and 2.0 cm/bird, respectively. All birds received a 23-h lighting regimen and were fed the same diet comprising 3,100 kcal of ME/kg of diet and 23% CP from 1 d old to 4 wk of age (WOA) and 3,150 kcal of ME/kg of diet and 21% CP at 5 to 8 WOA. Feed and water were provided for ad libitum consumption. Body weight and feed consumption were measured weekly, whereas carcass characteristics were evaluated at 8 WOA. Overall, feed consumption was significantly higher (P \u3c 0.05) in birds raised in 10.7 birds/m2 than other treatment groups. Birds in floor densities of 12 and 15.6 birds/m2 also consumed 6% more feed than those raised at 13.6 birds/m2. Mean BW gain of birds in floor density of 15.6 birds/m2 was significantly lower (P \u3c 0.05) than that of birds in other floor densities. In general, significantly lower feed conversion ratios and higher carcass yields were observed in birds raised in floor densities of 13.6 and 12 birds/m2 than those raised in floor densities of 15.6 and 10.7 birds/m2. Therefore, French guinea broilers exhibited superior performance when raised at floor densities of 13.6 and 12 birds/m2 than those reared at floor densities of 15.6 and 10.7 birds/m2

    Update to the Vitamin C, Thiamine and Steroids in Sepsis (VICTAS) protocol: statistical analysis plan for a prospective, multicenter, double-blind, adaptive sample size, randomized, placebo-controlled, clinical trial.

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    BACKGROUND: Observational research suggests that combined therapy with Vitamin C, thiamine and hydrocortisone may reduce mortality in patients with septic shock. METHODS AND DESIGN: The Vitamin C, Thiamine and Steroids in Sepsis (VICTAS) trial is a multicenter, double-blind, adaptive sample size, randomized, placebo-controlled trial designed to test the efficacy of combination therapy with vitamin C (1.5 g), thiamine (100 mg), and hydrocortisone (50 mg) given every 6 h for up to 16 doses in patients with respiratory or circulatory dysfunction (or both) resulting from sepsis. The primary outcome is ventilator- and vasopressor-free days with mortality as the key secondary outcome. Recruitment began in August 2018 and is ongoing; 501 participants have been enrolled to date, with a planned maximum sample size of 2000. The Data and Safety Monitoring Board reviewed interim results at N = 200, 300, 400 and 500, and has recommended continuing recruitment. The next interim analysis will occur when N = 1000. This update presents the statistical analysis plan. Specifically, we provide definitions for key treatment and outcome variables, and for intent-to-treat, per-protocol, and safety analysis datasets. We describe the planned descriptive analyses, the main analysis of the primary end point, our approach to secondary and exploratory analyses, and handling of missing data. Our goal is to provide enough detail that our approach could be replicated by an independent study group, thereby enhancing the transparency of the study. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03509350. Registered on 26 April 2018

    Rationale, design, and protocol for the prevention of low back pain in the military (POLM) trial (NCT00373009)

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    <p>Abstract</p> <p>Background</p> <p>There are few effective strategies reported for the primary prevention of low back pain (LBP). Core stabilization exercises targeting the deep abdominal and trunk musculature and psychosocial education programs addressing patient beliefs and coping styles represent the current best evidence for secondary prevention of low back pain. However, these programs have not been widely tested to determine if they are effective at preventing the primary onset and/or severity of LBP. The purpose of this cluster randomized clinical trial is to determine if a combined core stabilization exercise and education program is effective in preventing the onset and/or severity of LBP. The effect of the combined program will be compared to three other standard programs.</p> <p>Methods/Design</p> <p>Consecutive Soldiers participating in advanced individual training (AIT) will be screened for eligibility requirements and consented to study participation, as appropriate. Companies of Soldiers will be randomly assigned to receive the following standard prevention programs; a core stabilization exercise program (CSEP) alone, a CSEP with a psychosocial education (PSEP), a traditional exercise (TEP), or a TEP with a PSEP. Proximal outcome measures will be assessed at the conclusion of AIT (a 12 week training period) and include imaging of deep lumbar musculature using real-time ultrasound imaging and beliefs about LBP by self-report questionnaire. We are hypothesizing that Soldiers receiving the CSEP will have improved thickness of selected deep lumbar musculature (transversus abdominus, multifidi, and erector spinae muscles). We are also hypothesizing that Soldiers receiving the PSEP will have improved beliefs about the management of LBP. After AIT, Soldiers will be followed monthly to measure the distal outcomes of LBP occurrence and severity. This information will be collected during the subsequent 2 years following completion of AIT using a web-based data entry system. Soldiers will receive a monthly email that queries whether any LBP was experienced in the previous calendar month. Soldiers reporting LBP will enter episode-specific data related to pain intensity, pain-related disability, fear-avoidance beliefs, and pain catastrophizing. We are hypothesizing that Soldiers receiving the CSEP and PSEP will report the longest duration to first episode of LBP, the lowest frequency of LBP, and the lowest severity of LBP episodes. Statistical comparisons will be made between each of the randomly assigned prevention programs to test our hypotheses related to determining which of the 4 programs is most effective.</p> <p>Discussion</p> <p>We have presented the design and protocol for the POLM trial. Completion of this trial will provide important information on how to effectively train Soldiers for the prevention of LBP.</p> <p>Trial registration</p> <p>NCT00373009</p

    Solar Contamination in Extreme-precision Radial-velocity Measurements: Deleterious Effects and Prospects for Mitigation

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    Solar contamination, due to moonlight and atmospheric scattering of sunlight, can cause systematic errors in stellar radial velocity (RV) measurements that significantly detract from the ~10 cm s−1 sensitivity required for the detection and characterization of terrestrial exoplanets in or near habitable zones of Sun-like stars. The addition of low-level spectral contamination at variable effective velocity offsets introduces systematic noise when measuring velocities using classical mask-based or template-based cross-correlation techniques. Here we present simulations estimating the range of RV measurement error induced by uncorrected scattered sunlight contamination. We explore potential correction techniques, using both simultaneous spectrometer sky fibers and broadband imaging via coherent fiber imaging bundles, that could reliably reduce this source of error to below the photon-noise limit of typical stellar observations. We discuss the limitations of these simulations, the underlying assumptions, and mitigation mechanisms. We also present and discuss the components designed and built into the NEID (NN-EXPLORE Exoplanet Investigations with Doppler spectroscopy) precision RV instrument for the WIYN 3.5 m telescope, to serve as an ongoing resource for the community to explore and evaluate correction techniques. We emphasize that while "bright time" has been traditionally adequate for RV science, the goal of 10 cm s−1 precision on the most interesting exoplanetary systems may necessitate access to darker skies for these next-generation instruments
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