15,984 research outputs found

    Triple cascade behaviour in QG and drift turbulence and generation of zonal jets

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    We study quasigeostrophic (QG) and plasma drift turbulence within the Charney-Hasegawa-Mima (CHM) model. We focus on the zonostrophy, an extra invariant in the CHM model, and on its role in the formation of zonal jets. We use a generalized Fjørtoft argument for the energy, enstrophy, and zonostrophy and show that they cascade anisotropically into nonintersecting sectors in k space with the energy cascading towards large zonal scales. Using direct numerical simulations of the CHM equation, we show that zonostrophy is well conserved, and the three invariants cascade as predicted by the Fjørtoft argument

    Preliminary Results of Aerodynamic Heating Studies on the X-15 Airplane

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    Aerodynamic heating analysis of X-15 aircraft in fligh

    Beyond a Call to Action

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    This paper is intended as a critique and development of morality in literature, seeking to prove that literature can have deep effects on a reader\u27s moral character. The stakes for such research are rather high: especially during the pandemic, our culture is heavily informed by social and mass media, and it is hard to imagine a good future for the world if these mediums cannot shake the status quo. Though this paper takes a narrower scope of investigation than moral progress itself, the reader should keep in mind that all of our practices of communication can and should be informed by literary tradition, among other practices. For art is our name for the most refined and deliberate artifacts of human expression, capable of great scale, subtlety, and mass dissemination. Morality in communication is explored here through literature, but I hope the reader will make an attempt to apply any knowledge gleaned to as diverse a range of their practices as is possible. The basic issue of my research is that conventional calls to action, for example Sarah McLachlan\u27s famous SPCA commercials, are not terribly effective. This is obvious insofar as there is a saturation of these calls to action, and a shocking lack of action or concern from many, but I will also seek to justify this in the theories of Immanuel Levinas, then develop a solution from a more philosophical framing of the problem, with Louis Althusser\u27s writings on ideology, as well as case studies from literature. Eventually, this all leads to the question: how do we address ideology in art? Which will hopefully be somewhat answered by the development of the question, and further addressed by the case studies comprising the latter half of this writing

    Overview of the Main Propulsion System for the NASA Ares I Upper Stage

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    A functional overview of the Main Propulsion System (MPS) of the NASA Ares I Upper Stage is provided. In addition to a simple overview of the key MPS functions and design philosophies, major lessons learned are discussed. The intent is to provide a technical overview with enough detail to allow engineers outside of the MPS Integrated Product Team (IPT) to develop a rough understanding of MPS operations, components, design philosophy, and lessons learned

    Effects of magnesium with or without boron on headshaking behavior in horses with trigeminal-mediated headshaking.

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    BackgroundOral administration of magnesium and boron might have a beneficial effect on headshaking behavior in horses.ObjectiveEvaluate the effects of oral magnesium alone or in combination with boron on headshaking behavior in affected horses.AnimalsTwelve geldings (6 healthy controls and 6 affected).MethodsProspective randomized controlled dietary trial over 42 days in 12 horses (6 horses diagnosed with trigeminal-mediated headshaking and 6 unaffected healthy controls). All horses received a hay diet and were randomized into 3 treatment groups: pelleted feed combination (PF), pelleted feed combination with magnesium (M), and pelleted feed combination with magnesium-boron (MB) with a week washout of hay only between treatments. Headshaking behavior and biochemical blood variables were assessed at baseline (hay only) and then after each week of supplementation.ResultsAll 3 diet interventions increased blood ionized and total magnesium. Groups M and MB further increased Mg2+ when compared to PF. Horses receiving treatments had a significant reduction in headshaking behavior, as measured by incidence rate ratio (IRR), when compared to unsupplemented hay diet (44% for PF, IRR, 0.558; CI, 0.44, 0.72; P < .001; 52% for M, IRR, 0.476; CI, 0.37, 0.62; P < .001; and 64% for MB, IRR, 0.358; CI, 0.27, 0.48; P < .001).Conclusions and clinical importanceMagnesium in combination with boron had the greatest decrease in headshaking. Oral supplementation with magnesium or magnesium in combination with boron should be considered in horses affected with headshaking

    Axiomatic approach to radiation reaction of scalar point particles in curved spacetime

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    Several different methods have recently been proposed for calculating the motion of a point particle coupled to a linearized gravitational field on a curved background. These proposals are motivated by the hope that the point particle system will accurately model certain astrophysical systems which are promising candidates for observation by the new generation of gravitational wave detectors. Because of its mathematical simplicity, the analogous system consisting of a point particle coupled to a scalar field provides a useful context in which to investigate these proposed methods. In this paper, we generalize the axiomatic approach of Quinn and Wald in order to produce a general expression for the self force on a point particle coupled to a scalar field following an arbitrary trajectory on a curved background. Our equation includes the leading order effects of the particle's own fields, commonly referred to as ``self force'' or ``radiation reaction'' effects. We then explore the equations of motion which follow from this expression in the absence of non-scalar forces.Comment: 17 pages, 1 figur

    The Economic Recession: Early Impacts on Health Care Safety Net Providers

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    Examines how the recession and state and local budget cuts affected safety-net clinics' capacity to meet demand in five communities, the extent to which federal stimulus funds mitigated the impact, strategies for sustainability, and implications

    The Expected Mass Function for Low Mass Galaxies in a CDM Cosmology: Is There a Problem?

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    It is well known that the mass function for_halos_ in CDM cosmology is a relatively steep power law for low masses, possibly too steep to be consistent with observations. But how steep is the_galaxy_ mass function? We have analyzed the stellar and gas mass functions of the first massive luminous objects formed in a \Lambda CDM universe, as calculated in the numerical simulation described in Gnedin (2000ab). We found that while the dark matter mass function is steep, the stellar and gas mass functions are flatter for low mass objects. The stellar mass function is consistently flat at the low mass end. Moreover, while the gas mass function follows the dark matter mass function until reionization at z~7, between z=7 and z=4, the gas mass function also flattens considerably at the low mass end. At z=4, the gas and stellar mass functions are fit by a Schechter function with \alpha ~ -1.2 +/- 0.1, significantly shallower than the dark matter halo mass function and consistent with some recent observations. The baryonic mass functions are shallower because (a) the dark matter halo mass function is consistent with the Press-Schechter formulation at low masses n(M) M^-2 and (b) heating/cooling and ionization processes appear to cause baryons to collect in halos with the relationship M_b M_d^4 at low masses. Combining (a) and (b) gives n(M_b) M_b^-5/4, comparable to the simulation results. Thus, the well known observational fact that low mass galaxies are underabundant as compared to expectations from numerical dark matter simulations or Press-Schechter modeling of CDM universes emerges naturally from these results, implying that perhaps no ``new physics'' beyond the standard model is needed.Comment: Submitted to ApJ, 17 pages including 6 figure
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