4,743 research outputs found

    Computer-aided space shuttle orbiter wing design study

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    An analytical and experimental investigation has been made to provide a space shuttle orbiter wing design that met the guideline requirements of landing performance, stability, and hypersonic trim for a specified center-of-gravity envelope. The analytical study was facilitated by the use of the Optimal Design Integration system (ODIN) and the experimental part of the investigation was conducted in the Langley low-turbulence pressure tunnel and the Langley continuous-flow hypersonic tunnel

    A mathematical model of a single main rotor helicopter for piloted simulation

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    A mathematical model, suitable for piloted simulation of the flying qualities of helicopters, is a nonlinear, total force and moment model of a single main rotor helicopter. The model has ten degrees of freedom: six rigid body, three rotor flapping, and the rotor rotational degrees of freedom. The rotor model assumes rigid blades with rotor forces and moments radially integrated and summed about the azimuth. The fuselage aerodynamic model uses a detailed representation over a nominal angle of attack and sideslip range of + or - 15 deg., as well as a simplified curve fit at large angles of attack or sideslip. Stabilizing surface aerodynamics are modeled with a lift curve slope between stall limits and a general curve fit for large angles of attack. A generalized stability and control augmentation system is described. Additional computer subroutines provide options for a simplified engine/governor model, atmospheric turbulence, and a linearized six degree of freedom dynamic model for stability and control analysis

    Hadron structure in tau -> KKpi nu_tau decays

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    We analyse the hadronization structure of both vector and axial-vector currents leading to tau -> KKpi nu_tau decays. At leading order in the 1/Nc expansion, and considering only the contribution of the lightest resonances, we work out, within the framework of the resonance chiral Lagrangian, the structure of the local vertices involved in those processes. The couplings in the resonance theory are constrained by imposing the asymptotic behaviour of vector and axial-vector spectral functions ruled by QCD. In this way we predict the hadron spectra and conclude that, contrarily to previous assertions, the vector contribution dominates by far over the axial-vector one in all KKpi charge channels.Comment: 32 pages, 7 figure

    Answers that Have Integrity

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    [EN] Answers to queries in possibly inconsistent databases may not have integrity. We formalize ‘has integrity’ on the basis of a definition of ‘causes’. A cause of an answer is a minimal excerpt of the database that explains why the answer has been given. An answer has integrity if one of its causes does not overlap with any cause of integrity violation.Supported by FEDER and the Spanish grants TIN2009-14460-C03, TIN2010-17139.Decker, H. (2011). Answers that Have Integrity. Lecture Notes in Computer Science. 6834:54-72. https://doi.org/10.1007/978-3-642-23441-5S5472683

    Ground-simulation investigations of VTOL airworthiness criteria for terminal-area operations

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    Several ground-based simulation experiments undertaken to investigate concerns related to tilt-rotor aircraft airworthiness were conducted. The experiments were conducted on the National Aeronautics and Space Administration (NASA) Ames Research Center's Vertical Motion Simulator, which permits simulation of a wide variety of aircraft with a high degree of fidelity of motion cueing. Variations in conversion/deceleration profile, type of augmentation or automation, level of display assistance, and meteorological conditions were considered in the course of the experiments. Certification pilots from the Federal Aviation Administration (FAA) and the Civil Aviation Authority (CAA) participated, in addition to NASA research pilots. The setup of these experiments on the simulator is summarized, and some of the results highlighted

    Effects of Dietary Sodium Intake on Blood Flow Regulation During Exercise in Salt Resistant Individuals

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    PURPOSE: Dietary sodium intake guidelines is ≤2,300 mg/day, yet is exceeded by 90% of Americans. This study examined the impact of a high sodium diet on blood flow regulation during exercise. METHODS: Six males (25 ± 2 years) consumed dietary sodium intake guidelines for two weeks, with one week salt-capsule supplemented (HS: 6,900 mg/day of sodium) and the other week placebo-capsule supplemented (LS: 2,300 mg/day of sodium). At the end of each week, peripheral hemodynamic measurements [blood flow (BF), shear rate (SR), and flow mediated dilation (FMD)/SR)] of the brachial and superficial femoral artery were taken during handgrip (HG) and plantar flexion (PF) exercise, respectively. Each exercise workload was 3 minutes and progressed by 8 kilograms until exhaustion. RESULTS: There were no differences between LS and HS in blood pressure (82 ± 4 v 80 ± 5 mmHg; p = 0.3) or heart rate (56 ± 6 v 59 ± 10 bpm; p = 0.4). HG and PF exercise increased BF, SR, and FMD/SR across workload (p \u3c 0.03 for all), but no difference between diets (p \u3e 0.05 for all). CONCLUSION: Despite previous reports that HS impairs resting vascular function, this study revealed that peripheral vascular function and blood flow regulation during exercise is not impacted by a HS diet.https://scholarscompass.vcu.edu/gradposters/1082/thumbnail.jp

    Telaprevir-based triple-therapy in patients with chronic hepatitis C in Germany: a 12-week interim analysis of real-life data

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    Telaprevir (TVR)-based triple therapy in patients (pts) with chronic hepatitis C (HCV) in daily practice in Germany is investigated in this non-interventional study. Aims are the evaluation of the implementation of futility rules, as well as safety and efficacy of TVR-based therapy. This prospective, multi-center study investigates TVR-based therapy in therapy-naïve and pretreated pts with genotype 1 chronic HCV in Germany, including pts with HIV co-infection. Patients are treated with a combination of TVR, ribavirin and peg-interferon. This interim analysis includes data from the first 100 pts (12.5% of the planned total) at 32 sites completing 12 weeks (W) of treatment. 66% of pts were pretreated for HCV. 36.4% of pts with pre-treatment were prior relapsers and 30.3% null or partial responders. Cirrhosis was present in 11% of all pts at baseline. HCV RNA levels below 800.000 IU/ml at baseline were present in 50% of pts. 67% of pts showed rapid virological response (RVR, undetectable HCV RNA at W4). Adherence to the futility rule (treatment stop if HCV-RNA>1000 IU/ml at W4) was 100% (N=9). At W12, 91.4% of pts had undetectable HCV RNA. 57.7% of therapy-naïve pts and 86.4% of previous relapsers were HCV-RNA negative at both W4 and 12 (70.8% in total). Only one patient achieving RVR at W4 suffered a virologic breakthrough. Nearly all pts (99%) had adverse events (AE) during the first 12W, 6% reported serious adverse events (SAE). AEs were mostly mild (63.9%) or moderate (34.6%) and frequently mentioned dry skin/pruritus (54%), gastrointestinal disorders (48%), anorectal discomfort (30%), rash (29%) and anemia (23%). Rash was mostly rated as mild or moderate (97.1%). An Hb decrease<12 g/dl (female) or<13 g/dl (male) was reported in 87% of pts. Mean Hb levels decreased from 14.8 g/dl at baseline to 10.6 g/dl at W12; Hb levels<8.5 g/dl at any time within the first 12W of treatment were present in 11% of anemia cases and 6.6% required transfusion. Only one patient received erythropoietin treatment. 2 cases each of anemia and rash were considered as SAE. These interim results suggest that TVR-based triple-therapy is efficient against GT1 chronic hepatitis C in a real life setting. Adherence to futility rules was confirmed in all patients. As observed in clinical trials, adverse events were reported frequently, including anemia and rash. As more data become available, results will be updated
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