10,515 research outputs found

    A spin-recovery parachute system for light general-aviation airplanes

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    A tail mounted spin recovery parachute system was designed and developed by the NASA Langley Research Center for use on light general aviation airplanes. The system was designed for use on typical airplane configurations, including low wing, single engine, and twin-engine design. A mechanically triggered pyrotechnic slug gun is used to forcibly deploy a pilot parachute which extracts a bag that deploys a ring slot spin recovery parachute. The total system weighs 8.2 kg (18 lb). System design factors included airplane wake effects on parachute deployment, prevention of premature parachute deployment, positive parachute jettison, compact size, low weight, system reliability, and pilot and ground crew safety. Extensive ground tests were conducted to qualify the system. The recovery parachute was used successfully in flight 17 times

    Role of noncoding RNA in vascular remodelling

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    Purpose of review: Noncoding RNAs (ncRNAs), such as microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) are becoming fundamentally important in the pathophysiology relating to injury-induced vascular remodelling. We highlight recent studies that demonstrate the involvement of ncRNAs in vein graft disease, in in-stent restenosis and in pulmonary arterial hypertension, with a particular focus on endothelial cell and vascular smooth muscle cell function. We also briefly discuss the emerging role of exosomal-derived ncRNAs and how this mechanism impacts on vascular function. Recent findings: ncRNAs have been described as novel regulators in the pathophysiology of vascular injury, inflammation, and vessel wall remodelling. In particular, several studies have demonstrated that manipulation of miRNAs can reduce the burden of pathological vascular remodelling. Such studies have also shown that exosomal miRNA-mediated, cell-to-cell communication between endothelial cells and vascular smooth muscle cells is critical in the disease process. In addition to miRNAs, lncRNAs are emerging as regulators of vascular function in health and disease. Although lncRNAs are complex in both their sheer numbers and mechanisms of action, identifying their contribution to vascular disease is essential. Summary: Given the important roles of ncRNAs in vascular injury and remodelling together will their capacity for cell-to-cell communication, manipulating ncRNA might provide novel therapeutic interventions

    Emergence of Kinetic Behavior in Streaming Ultracold Neutral Plasmas

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    We create streaming ultracold neutral plasmas by tailoring the photoionizing laser beam that creates the plasma. By varying the electron temperature, we control the relative velocity of the streaming populations, and, in conjunction with variation of the plasma density, this controls the ion collisionality of the colliding streams. Laser-induced fluorescence is used to map the spatially resolved density and velocity distribution function for the ions. We identify the lack of local thermal equilibrium and distinct populations of interpenetrating, counter-streaming ions as signatures of kinetic behavior. Experimental data is compared with results from a one-dimensional, two-fluid numerical simulation.Comment: 8 pages, 6 figure

    B-field Determination from Magnetoacoustic Oscillations in kHz QPO Neutron Star Binaries: Theory and Observations

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    We present a method for determining the B-field around neutron stars based on observed kHz and viscous QPO frequencies used in combination with the best-fit optical depth and temperature of a Comptonization model. In the framework of the transition layer QPO model, we analyze magnetoacoustic wave formation in the layer between a neutron star surface and the inner edge of a Keplerian disk. We derive formulas for the magnetoacoustic wave frequencies for different regimes of radial transition layer oscillations. We demonstrate that our model can use the QPO as a new kind of probe to determine the magnetic field strengths for 4U 1728-42, GX 340+0, and Sco X-1 in the zone where the QPOs occur. Observations indicate that the dependence of the viscous frequency on the Keplerian frequency is closely related to the inferred dependence of the magnetoacoustic wave frequency on the Keplerian frequency for a dipole magnetic field. The magnetoacoustic wave dependence is based on a single parameter, the magnetic moment of the star as estimated from the field strength in the transition layer. The best-fit magnetic moment parameter is about (0.5-1)x 10^{25} G cm^3 for all studied sources. From observational data, the magnetic fields within distances less 20 km from neutron star for all three sources are strongly constrained to be dipole fields with the strengths 10^{7-8} G on the neutron star surface.Comment: 10 pages, 1 figure, accepted for the Astrophysical Journal Letter

    England's fresh approach to food waste: problem frames in the Resources and Waste Strategy

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    Coexisting and eye-watering levels of food abundance, waste, overconsumption and hunger are symptomatic of a broken food system punctuated by vested interests in systematic overproduction. Against that backdrop, this paper evaluates England's ‘new’ approach to food waste in light of concerns that policy-makers have framed food waste as a consumer behaviour problem, rather than a structural challenge. The Resources and Waste Strategy's acknowledgement of normalised overproduction is thus remarkable, but unexpected. However, frame critical analysis reveals how an apparent departure from preoccupations with economic growth, combined with promises of government action, obscure an ongoing reluctance to intervene against powerful interests and the causes (not symptoms) of food waste. Legislative proposals, rather than reducing surplus, shift the burden of redistributing food away from the state and retailers, on to charities and farmers. With England, perhaps wrongly, seen as a world-leader on food waste, this has implications for other jurisdictions, as well as forthcoming consultations

    Giovanni Luca Conforti and Vocal Embellishment: From Formula to Artful Improvisation

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    Considers Conforti\u27s treatise Breve et facile maniera d\u27essercitarsi... (1593) and his Salmi passaggiati (1601-03), revealing the vast gulf between the etude-like exercises in the treatise and the actual embellished music--a difference similar to that between the exercises of Hanon and the piano etudes of Chopin. The embellishments of this period were far more than mere displays of virtuosity; they sprang from a desire to express the deepest meanings of the text
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