7,781 research outputs found

    Sacred Hoop Dreams: Basketball in the Work of Sherman Alexie

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    The game of basketball serves as a fitting metaphor for the conflicts and tensions of life. It involves both cooperation and competition, selflessness and ego. In the hands of a gifted writer like Sherman Alexie, those paradoxes become even deeper and more revealing. In his short story collections, The Lone Ranger and Tonto Fistfight in Heaven and The Toughest Indian in the World, his debut novel, Reservation Blues, and his recent young adult novel, The Absolutely True Diary of a Part-Time Indian, Alexie uses basketball to explore the ironies of American Indian reservation life and the tensions between traditional lifeways and contemporary social realities. So central is basketball to the Lone Ranger and Tonto short story collection, in fact, that the paperback edition\u27s cover depicts a salmon - the Coeur d\u27Alene Indians are fishermen - flying over a basketball hoop

    Holistic Learning-Centeredness: De-Centering the University for Social Justice

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    Many colleges and universities have begun to shift their orientation from teaching-centered (privileging the teacher and the content) to student-centered (designing courses and curricula based on students’ perspectives, needs, and desires). Higher education needs to take the next step by acknowledging that the campus as only one locus of student learning out of many. Students learn from all aspects of their lives, and higher education institutions should—by implementing ePortfolios and other tools for integration and reflection—focus on helping students connect and reflect upon what they learn not only in the curriculum and co-curriculum, but also in their families, workplaces, friendships, and elsewhere. Building upon the scholarly literature on learner-centered teaching in diverse settings, I argue that de-centering the college campus in favor of a more fully learner-centered perspective will further social justice by honoring the multiple communities—especially those with less socioeconomic privilege—in which our students live and learn, and transform and energize ourselves as teachers

    Liver Transplantation to Provide Low-Density-Lipoprotein Receptors and Lower Plasma Cholesterol in a Child with Homozygous Familial Hypercholesterolemia

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    A six-year-old girl with severe hypercholesterolemia and atherosclerosis had two defective genes at the low-density-lipoprotein (LDL) receptor locus, as determined by biochemical studies of cultured fibroblasts. One gene, inherited from the mother, produced no LDL receptors; the other gene, inherited from the father, produced a receptor precursor that was not transported to the cell surface and was unable to bind LDL. The patient degraded intravenously administered 125I-LDL at an extremely low rate, indicating that her high plasma LDL-cholesterol level was caused by defective receptor-mediated removal of LDL from plasma. After transplantation of a liver and a heart from a normal donor, the patient's plasma LDL-cholesterol level declined by 81 per cent, from 988 to 184 mg per deciliter. The fractional catabolic rate for intravenously administered 125I-LDL, a measure of functional LDL receptors in vivo, increased by 2.5-fold. Thus, the transplanted liver, with its normal complement of LDL receptors, was able to remove LDL cholesterol from plasma at a nearly normal rate. We conclude that a genetically determined deficiency of LDL receptors can be largely reversed by liver transplantation. These data underscore the importance of hepatic LDL receptors in controlling the plasma level of LDL cholesterol in human beings. (N Engl J Med 1984; 311: 1658–64.). © 1984, Massachusetts Medical Society. All rights reserved

    Axonal stress kinase activation and tau misbehavior induced by kinesin-1 transport defects

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    Many neurodegenerative diseases exhibit axonal pathology, transport defects, and aberrant phosphorylation and aggregation of the microtubule binding protein tau. While mutant tau protein in frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP17) causes aberrant microtubule binding and assembly of tau into filaments, the pathways leading to tau-mediated neurotoxicity in Alzheimer's disease and other neurodegenerative disorders in which tau protein is not genetically modified remain unknown. To test the hypothesis that axonal transport defects alone can cause pathological abnormalities in tau protein and neurodegeneration in the absence of mutant tau or amyloid β deposits, we induced transport defects by deletion of the kinesin light chain 1 (KLC1) subunit of the anterograde motor kinesin-1. We found that upon aging, early selective axonal transport defects in mice lacking the KLC1 protein (KLC1-/-) led to axonopathies with cytoskeletal disorganization and abnormal cargo accumulation. In addition, increased c-jun N-terminal stress kinase activation colocalized with aberrant tau in dystrophic axons. Surprisingly, swollen dystrophic axons exhibited abnormal tau hyperphosphorylation and accumulation. Thus, directly interfering with axonal transport is sufficient to activate stress kinase pathways initiating a biochemical cascade that drives normal tau protein into a pathological state found in a variety of neurodegenerative disorders including Alzheimer's disease.Fil: Falzone, Tomas Luis. Howard Hughes Medical Institute; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Stokin, Gorazd B.. University Psychiatric Hospital; EsloveniaFil: Lillo, Concepción. University of California at San Diego; Estados UnidosFil: Rodrigues, Elizabeth M.. Howard Hughes Medical Institute; Estados UnidosFil: Westerman, Eileen L.. Howard Hughes Medical Institute; Estados UnidosFil: Williams, David S.. University of California at San Diego; Estados UnidosFil: Goldstein, Lawrence S. B.. Howard Hughes Medical Institute; Estados Unido

    The NAD(P)H oxidase homolog Nox4 modulates insulin-stimulated generation of H\u3csub\u3e2\u3c/sub\u3e0\u3csub\u3e2\u3c/sub\u3e and plays an integral role in insulin signal transduction

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    Insulin stimulation of target cells elicits a burst of H2O2 that enhances tyrosine phosphorylation of the insulin receptor and its cellular substrate proteins as well as distal signaling events in the insulin action cascade. The molecular mechanism coupling the insulin receptor with the cellular oxidant-generating apparatus has not been elucidated. Using reverse transcription-PCR and Northern blot analyses, we found that Nox4, a homolog of gp91phox, the phagocytic NAD(P)H oxidase catalytic subunit, is prominently expressed in insulin-sensitive adipose cells. Adenovirus-mediated expression of Nox4 deletion constructs lacking NAD(P)H or FAD/NAD(P)H cofactor binding domains acted in a dominant-negative fashion in differentiated 3T3-L1 adipocytes and attenuated insulin-stimulated H2O2 generation, insulin receptor (IR) and IRS-1 tyrosine phosphorylation, activation of downstream serine kinases, and glucose uptake. Transfection of specific small interfering RNA oligonucleotides reduced Nox4 protein abundance and also inhibited the insulin signaling cascade. Overexpression of Nox4 also significantly reversed the inhibition of insulin-stimulated IR tyrosine phosphorylation induced by coexpression of PTP1B by inhibiting PTP1B catalytic activity. These data suggest that Nox4 provides a novel link between the IR and the generation of cellular reactive oxygen species that enhance insulin signal transduction, at least in part via the oxidative inhibition of cellular protein-tyrosine phosphatases (PTPases), including PTP1B, a PTPase that has been previously implicated in the regulation of insulin action

    Stellar Dynamics of Extreme-Mass-Ratio Inspirals

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    Inspiral of compact stellar remnants into massive black holes (MBHs) is accompanied by the emission of gravitational waves at frequencies that are potentially detectable by space-based interferometers. Event rates computed from statistical (Fokker-Planck, Monte-Carlo) approaches span a wide range due to uncertaintities about the rate coefficients. Here we present results from direct integration of the post-Newtonian N-body equations of motion descrbing dense clusters of compact stars around Schwarzschild MBHs. These simulations embody an essentially exact (at the post-Newtonian level) treatment of the interplay between stellar dynamical relaxation, relativistic precession, and gravitational-wave energy loss. The rate of capture of stars by the MBH is found to be greatly reduced by relativistic precession, which limits the ability of torques from the stellar potential to change orbital angular momenta. Penetration of this "Schwarzschild barrier" does occasionally occur, resulting in capture of stars onto orbits that gradually inspiral due to gravitational wave emission; we discuss two mechanisms for barrier penetration and find evidence for both in the simulations. We derive an approximate formula for the capture rate, which predicts that captures would be strongly disfavored from orbits with semi-major axes below a certain value; this prediction, as well as the predicted rate, are verified in the N-body integrations. We discuss the implications of our results for the detection of extreme-mass-ratio inspirals from galactic nuclei with a range of physical properties.Comment: 28 pages, 16 figures. Version 2 is significantly revised to reflect new insights into J and Q effects, to be published late

    Variation in Emission and Absorption Lines and Continuum Flux by Orbital Phase in Vela X-1

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    High resolution spectral studies were undertaken at orbital phases 0, 0.25 and 0.5 on the high-mass X-ray binary (HMXB) Vela X-1 using archival Chandra data. We present (a) the first detailed analysis of the multiple strong narrow emission lines present in phase 0.5 (b) an analysis of the absorption of the continuum in phase 0.5, and (c) the first detection of narrow emission and absorption lines in phase 0.25. Multiple fluorescent and H-and He-like emission lines in the band 1.6 - 20 Angstrom in eclipse are partially obscured at phase 0.25 by the X-ray continuum. The phase 0.25 spectrum displays 3 triplets, 2 with a blue-shifted resonance (r) line in absorption and the intercombination (i) and forbidden (f) lines in emission, and shows in absorption other blue-shifted lines seen in emission in eclipse. At phase 0.5 the soft X-ray continuum diminishes revealing an "eclipse-like" spectrum, however line flux values are around 13-fold those in eclipse. We conclude the narrow emission lines in Vela X-1 become apparent when the continuum is blocked from line of sight, either by eclipse or by scattering and/or absorption from a wake or cloud. The H-and He-like lines arise in warm photoionised regions in the stellar wind, while the fluorescent lines (including a Ni K alpha line) are produced in cooler clumps of gas outside these regions. Absorption of the 5-13 Angstrom continuum at phase 0.5 may be caused by an accretion wake comprised of dense stagnant photoionized plasma inside a Stromgren zone. Multiple fluorescent emission lines may be a common feature of the supergiant category of HMXBs.Comment: 29 pages, 7 figures, accepted for publication in the Astronomical Journa

    Mandated Leave Policies in the Context of Student Mental Health Challenges at Canadian Universities: A Framework Analysis

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    Although there is increased attention to the mental health needs of university students, far less attention has been given to mental health-related university policies. Many Canadian public universities have mandated leave policies that specify the conditions under which a student may be required to take a leave of absence from university. The purpose of the current study was to conduct an in-depth analysis of current mandated leave policies in public Canadian English-speaking universities. Applied framework analysis methodology was used to examine the approaches to balancing the needs of students experiencing mental health challenges and providing a safe environment on campus. Three primary themes regarding mandated leave policies were identified, including (a) approaches for addressing mental health concerns, (b) balancing the needs of the student with the needs of the institution, and (c) guidelines, standards, and quality assurance. Implications for mandated leave policies and approaches to students experiencing mental health challenges are discussed.Bien que l’on s’intéresse de plus en plus aux besoins des étudiants universitaires en matière de santé mentale, on a accordé moins d’attention aux politiques universitaires relatives à la santé mentale. De nombreuses universités publiques canadiennes ont des politiques de congé obligatoire qui précisent les conditions dans lesquelles un étudiant doit prendre un congé de l’université. L’ob-jectif de la présente étude est d’analyser les politiques actuelles de congé obligatoire dans les universités publiques canadiennes anglophones. Une méthodologie d’analyse de cadre appliquée a été utilisée pour examiner les approches visant à trouver un équilibre entre les besoins des étudiants ayant des problèmes de santé mentale et la nécessité de fournir un environnement sûr sur le campus. Trois thèmes principaux ressortent concernant les politiques en matière de congés obligatoires, soit (a) les approches pour répondre aux problèmes de santé mentale, (b) l’équilibre entre les besoins de l’étudiant et les besoins de l’université, et (c) les lignes directrices, les normes et l’assurance de la qualité. Les implications pour les politiques de congé obligatoire et les approches auprès des étudiants ayant des problèmes de santé mentale sont discutées

    Non-equilibrium phase transitions in biomolecular signal transduction

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    We study a mechanism for reliable switching in biomolecular signal-transduction cascades. Steady bistable states are created by system-size cooperative effects in populations of proteins, in spite of the fact that the phosphorylation-state transitions of any molecule, by means of which the switch is implemented, are highly stochastic. The emergence of switching is a nonequilibrium phase transition in an energetically driven, dissipative system described by a master equation. We use operator and functional integral methods from reaction-diffusion theory to solve for the phase structure, noise spectrum, and escape trajectories and first-passage times of a class of minimal models of switches, showing how all critical properties for switch behavior can be computed within a unified framework

    Effect of Free Stream Turbulence and Other Vortical Disturbances on a Laminar Boundary Layer

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    This paper is concerned with the effect of free-stream turbulence on the pretransitional flat-plate boundary layer. It is assumed that either the turbulence Reynolds number or the downstream distance (or both) is small enough so that the flow can be linearized. The dominant disturbances in the boundary layer, which are of the Klebanoff type, are governed by the linearized unsteady boundary-region equations, i.e., the Navier Stokes equations with the streamwise derivatives neglected in the viscous and pressure-gradient terms. The turbulence is represented as a superposition of vortical free-stream Fourier modes, and the corresponding individual Fourier component solutions to the boundary-region equations are obtained numerically. The results are then superposed to compute the root mean square of the fluctuating streamwise velocity in the boundary layer produced by the actual free-stream turbulence. The calculated boundary-layer disturbances are in good quantitative agreement with the experimentally observed Klebanoff modes when strong low-frequency anisotropic effects are included in the free-stream turbulence spectrum. We discuss some additional effects that may need to be accounted for in order to obtain a complete description of the Klebanoff modes
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