6,706 research outputs found

    Relentless Assimilationist Indigenous Policy: From Invasion of Group Rights to Genocide in Mercy’s Clothing

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    Despite the United Nations Declaration of the Rights of Indigenous Peoples, assimilationist policies continue, whether official or effective. Such policies affect more than the right to group choice. The concern is whether indeed genocide or “only” ethnocide (or culturecide)—the elimination of a traditional culture—is at work. Discussions of the distinction between the two terms have been inconsistent enough that at least one commentator has declared that they cannot be used in analytical contexts. While these terms, I contend, have distinct senses, yet in cases of governmental and other institutional assimilationist policy for indigenous peoples, such ethnocide effectively entails genocide. Insofar as any people’s cultural practices and beliefs are essential for life and health, individuals in groups value, if tacitly, their culture as highly as their language or any artifact: Thus, attempts to eradicate a culture through assimilation in fact eradicate individuals’ lives and health and so are effectively murderous. Acknowledgement by worldwide organizations that assimilationist ethnocide is effectively genocide should affect policy concerning indigenous peoples and thus has significance for international law

    Data assimilation in the low noise regime with application to the Kuroshio

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    On-line data assimilation techniques such as ensemble Kalman filters and particle filters lose accuracy dramatically when presented with an unlikely observation. Such an observation may be caused by an unusually large measurement error or reflect a rare fluctuation in the dynamics of the system. Over a long enough span of time it becomes likely that one or several of these events will occur. Often they are signatures of the most interesting features of the underlying system and their prediction becomes the primary focus of the data assimilation procedure. The Kuroshio or Black Current that runs along the eastern coast of Japan is an example of such a system. It undergoes infrequent but dramatic changes of state between a small meander during which the current remains close to the coast of Japan, and a large meander during which it bulges away from the coast. Because of the important role that the Kuroshio plays in distributing heat and salinity in the surrounding region, prediction of these transitions is of acute interest. Here we focus on a regime in which both the stochastic forcing on the system and the observational noise are small. In this setting large deviation theory can be used to understand why standard filtering methods fail and guide the design of the more effective data assimilation techniques. Motivated by our analysis we propose several data assimilation strategies capable of efficiently handling rare events such as the transitions of the Kuroshio. These techniques are tested on a model of the Kuroshio and shown to perform much better than standard filtering methods.Comment: 43 pages, 12 figure

    The global structure of thin, stratified "alpha"-discs and the reliability of the one layer approximation

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    We report the results of a systematic comparison between the vertically averaged model and the vertically explicit model of steady state, Keplerian, optically thick "alpha"-discs. The simulations have concerned discs currently found in three different systems: dwarf novae, young stellar objects and active galactic nuclei. In each case, we have explored four decades of accretion rates and almost the whole disc area (except the narrow region where the vertically averaged model has degenerate solutions). We find that the one layer approach gives a remarkably good estimate of the main physical quantities in the disc, and specially the temperature at the equatorial plane which is accurate to within 30% for cases considered. The major deviations (by a factor < 4) are observed on the disc half-thickness. The sensitivity of the results to the "alpha"-parameter value has been tested for 0.001 < alpha < 0.1 and appears to be weak. This study suggests that the ``precision'' of the vertically averaged model which is easy to implement should be sufficient in practice for many astrophysical applications.Comment: 4 pages, PostScript. Accepted in Astronomy & Astrophysic

    Resistivity-driven State Changes in Vertically Stratified Accretion Disks

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    We investigate the effect of shear viscosity and Ohmic resistivity on the magnetorotational instability (MRI) in vertically stratified accretion disks through a series of local simulations with the Athena code. First, we use a series of unstratified simulations to calibrate physical dissipation as a function of resolution and background field strength; the effect of the magnetic Prandtl number, Pm = viscosity/resistivity, on the turbulence is captured by ~32 grid zones per disk scale height, H. In agreement with previous results, our stratified disk calculations are characterized by a subthermal, predominately toroidal magnetic field that produces MRI-driven turbulence for |z| < 2 H. Above |z| = 2 H, magnetic pressure dominates and the field is buoyantly unstable. Large scale radial and toroidal fields are also generated near the mid-plane and subsequently rise through the disk. The polarity of this mean field switches on a roughly 10 orbit period in a process that is well-modeled by an alpha-omega dynamo. Turbulent stress increases with Pm but with a shallower dependence compared to unstratified simulations. For sufficiently large resistivity, on the order of cs H/1000, where cs is the sound speed, MRI turbulence within 2 H of the mid-plane undergoes periods of resistive decay followed by regrowth. This regrowth is caused by amplification of toroidal field via the dynamo. This process results in large amplitude variability in the stress on 10 to 100 orbital timescales, which may have relevance for partially ionized disks that are observed to have high and low accretion states.Comment: very minor changes, accepted to Ap

    Examination of the Role of Religious and Psychosocial Factors in HIV Medication Adherence Rates

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    Optimal adherence to antiretroviral therapy (ART) is associated with favorable HIV outcomes, including higher CD4 cell counts, HIV virus suppression and a lower risk of HIV transmission. However, only 25% of people living with HIV/AIDS (PLWH) in the USA are virally suppressed. Sub-optimal adherence (p\u3c 0.05). Social support satisfaction was also significantly associated with ART adherence (OR = 1.52, 95% CI [1.11–2.08], p \u3c 0.05) and energy/fatigue/vitality (OR = 1.03, 95% CI [1.00–1.05], p \u3c 0.05)

    Differential sensitivity of basal and acetylcholine-induced activity of nitric oxide to blockade by asymmetric dimethylarginine (ADMA) in the rat aorta

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    &lt;b&gt;Background and purpose&lt;/b&gt;: Previous work has shown that NG-monomethyl-l-arginine (l-NMMA) paradoxically inhibits basal, but not ACh-stimulated activity of nitric oxide in rat aorta. The aim of this study was to determine if the endogenously produced agent, asymmetric NG, NG-dimethyl-l-arginine (ADMA), also exhibits this unusual selective blocking action. &lt;b&gt;Experimental approach&lt;/b&gt;: The effect of ADMA on basal nitric oxide activity was assessed by examining its ability to enhance phenylephrine (PE)-induced tone in endothelium-containing rings. Its effect on ACh-induced relaxation was assessed both in conditions where ADMA greatly enhanced PE tone and where tone was carefully matched with control tissues at a range of different levels. &lt;b&gt;Key results&lt;/b&gt;: ADMA (100 µM) potentiated PE-induced contraction, consistent with inhibition of basal nitric oxide activity. Higher concentrations (300–1000 µM) had no greater effect. Although ADMA (100 µM) also appeared to block ACh-induced relaxation when it enhanced PE tone to maximal levels, virtually no block was seen at intermediate levels of tone in the presence of ADMA. Even ADMA at 1000 µM had no effect on the maximal relaxation to ACh, although it produced a small (two- to threefold) reduction in sensitivity. ADMA and l-NMMA, like l-arginine (all at 1000 µM), protected ACh-induced relaxation against blockade by l-NAME (30 µM). &lt;b&gt;Conclusions and implications&lt;/b&gt;: In the rat aorta, ADMA, like l-NMMA, blocks basal activity of nitric oxide, but has little effect on that stimulated by ACh. Further studies are required to explain these seemingly anomalous actions of ADMA and l-NMMA

    Dead Zone Accretion Flows in Protostellar Disks

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    Planets form inside protostellar disks in a dead zone where the electrical resistivity of the gas is too high for magnetic forces to drive turbulence. We show that much of the dead zone nevertheless is active and flows toward the star while smooth, large-scale magnetic fields transfer the orbital angular momentum radially outward. Stellar X-ray and radionuclide ionization sustain a weak coupling of the dead zone gas to the magnetic fields, despite the rapid recombination of free charges on dust grains. Net radial magnetic fields are generated in the magneto-rotational turbulence in the electrically conducting top and bottom surface layers of the disk, and reach the midplane by Ohmic diffusion. A toroidal component to the fields is produced near the midplane by the orbital shear. The process is similar to the magnetization of the Solar tachocline. The result is a laminar, magnetically-driven accretion flow in the region where the planets form.Comment: 12 pages, 4 figure

    Turbulence and Steady Flows in 3D Global Stratified MHD Simulations of Accretion Disks

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    We present full 2 Pi global 3-D stratified MHD simulations of accretion disks. We interpret our results in the context of proto-planetary disks. We investigate the turbulence driven by the magneto-rotational instability (MRI) using the PLUTO Godunov code in spherical coordinates with the accurate and robust HLLD Riemann solver. We follow the turbulence for more than 1500 orbits at the innermost radius of the domain to measure the overall strength of turbulent motions and the detailed accretion flow pattern. We find that regions within two scale heights of the midplane have a turbulent Mach number of about 0.1 and a magnetic pressure two to three orders of magnitude less than the gas pressure, while outside three scale heights the magnetic pressure equals or exceeds the gas pressure and the turbulence is transonic, leading to large density fluctuations. The strongest large-scale density disturbances are spiral density waves, and the strongest of these waves has m=5. No clear meridional circulation appears in the calculations because fluctuating radial pressure gradients lead to changes in the orbital frequency, comparable in importance to the stress gradients that drive the meridional flows in viscous models. The net mass flow rate is well-reproduced by a viscous model using the mean stress distribution taken from the MHD calculation. The strength of the mean turbulent magnetic field is inversely proportional to the radius, so the fields are approximately force-free on the largest scales. Consequently the accretion stress falls off as the inverse square of the radius.Comment: Accepted for publication in Ap

    Morphology and Ultrastructure of the Amazon River Dolphin (<i>Inia geoffrensis</i>) Spermatozoa

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    The spermatozoa from seven adult Amazon river dolphins (Inia geoffrensis, CETACEA: INIIDAE) were analyzed by light and electron microscopy. The spermatozoa showed an elongated ellipsoid shaped head and a long tail with a well distinguishable midpiece. The head spermatozoa have a smooth surface like other odontocetes examined, with the exception of the Delphinidae family. The mean dimensions of the spermatozoa were within the range already reported for other cetaceans. The spermatozoa midpiece, as in other cetaceans, showed a random pattern of mitochondria, different from that described for other mammals. Further studies of sperm morphology of a wider spectrum of cetacean families could help to better understand the reproductive biology of these animals and the intergeneric and intrageneric relationships among them, as well as, among other mammals. Anat Rec, 300:1519–1523, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc
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