1,791 research outputs found

    Hub and blade structural loads measurements of an SA349/2 helicopter

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    Data from 23 flight conditions, including level flights ranging from advance ratio mu = 0.14 to 0.37 and steady turning flights from advance ratio mu = 0.26 to 0.35, are presented for an Aerospatiale SA349/2 Gazelle helicopter. The data include hub loads data (for 6 of the 23 conditions), blade structural data at eleven different blade radial stations, and fuselage structural data. All dynamic data are presented as harmonic analysis coefficients (ten harmonics per rotor revolution). The data acquisition and reduction procedures are also documented. Blade structural and inertial properties are provided in addition to control system geometry and properties

    Menstrual Phase and the Vascular Response to Acute Resistance Exercise in Women

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    Does the World Need U.S. Farmers Even if Americans Donā€™t?

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    We consider the implications of trends in the number of U.S. farmers and food imports on the question of what role U.S. farmers have in an increasingly global agrifood system. Our discussion stems from the argument some scholars have made that American consumers can import their food more cheaply from other countries than it can produce it. We consider the distinction between U.S. farmers and agriculture and the effect of the U.S. food footprint on developing nations to argue there might be an important role for U.S. farmers, even if it appears Americans donā€™t need them. For instance, we may need to protect U.S. farmland and, by implication, U.S. farmers, for future food security needs both domestic and international. We also explore the role of U.S. farmers by considering the question of whether food is a privilege or a right. Although Americans seem to accept that food is a privilege, many scholars and commentators argue that, at least on a global scale, food is a right, particularly for the worldā€™s poor and hungry. If this is the case, then U.S. farmers might have a role in meeting the associated obligation to ensure that the poor of the world have enough food to eat. We look at the consequences of determining that food is a right versus a privilege and the implications of that decision for agricultural subsidies as well as U.S. agriculture and nutrition policies.Food Security and Poverty,

    Hub loads analysis of the SA349/2 helicopter

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    The forces and moments at the rotor hub of an Aerospatiale SA349/2 helicopter were investigated. The study included three main topics. First, measured hub forces and moments for a range of level flight conditions (mu = 0.14 to 0.37) were compared with predictions from a comprehensive rotorcraft analysis to examine the influence of the wake model on the correlations. Second, the effect of changing the blade mass distribution and blade chordwise center of gravity location on the 3/rev nonrotating frame hub loads was studied for a high-speed flight condition (mu = 0.37). Third, the use of higher harmonic control to reduce nonrotating frame 3/rev hub shear forces was investigated. The last two topics were theoretical studies only

    Effects of Acute Nitrate Intake on Exhaled Nitric Oxide and Vascular Endothelial Function in Hypoxia

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    Acute Effects of High-Intensity Exercise on Peripheral Conduit Artery Blood Flow

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    Resistance Exercise, Carotid Artery Stiffness, and Cerebral Blood Flow Pulsatility

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    Lefferts, W., Augustine, J., Heffernan, K., Department of Exercise Science, Syracuse University, Syracuse, NY Cross-sectional studies have identified arterial stiffness as an important correlate of cerebral blood flow (CBF) pulsatility, an important predictor of cerebrovascular damage. Central artery stiffness increases acutely following a bout of resistance exercise (RE). It has yet to be elucidated whether RE-induced increases in arterial stiffness affect CBF pulsatility. Purpose: To investigate the effects of acute RE on carotid artery stiffness and CBF pulsatility. Methods: 18 healthy men (age 22 Ā± 1 yr; BMI 23.7 Ā± 0.5 kgāˆ™m-2) underwent a) acute RE (5 sets, 5-RM bench press, 5 sets 10-RM bicep curls with 90 s rest intervals), and b) a time control condition (seated rest) in a randomized order. CBF pulsatility index (PI) was measured with transcranial Doppler at the middle cerebral artery (MCA). Common carotid artery (CCA) beta stiffness (Ī²) and blood flow velocity PI were assessed using Doppler ultrasound. CCA pulse pressure was measured using applanation tonometry. Wave intensity analysis (WIA) was used to derive measures of forward (W1) and backward (Negative Area (NA)) travelling pressure waves to gain insight into origins of CBF pulsatility. Results: CCA Ī², and pulse pressure significantly increased post-RE (p \u3c 0.05). There was a significant increase in post-RE forward wave pressure (W1, p \u3c 0.05) with no changes in measures of backward/reflected wave pressure (lnNA, p \u3e 0.05). There were no changes in CCA PI or MCA PI following acute RE (p \u3e 0.05). Conclusions: Acute RE increases CCA stiffness and pressure pulsatility without affecting CCA or MCA flow pulsatility. Increases in pressure pulsatility are due to increases in forward wave pressure and not pressure from wave reflections

    The Effects of Acute Resistance Exercise on Vascular and Cognitive Function

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    Central Vascular Reactivity to Mental Stress in Emergency Responders

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    Beetroot Juice and Cerebrovascular Hemodynamics in Young Adults with a History of Concussion: Preliminary Findings

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