1,745 research outputs found

    Artin t-Motifs

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    We show that analytically trivial t-motifs satisfy a Tannakian duality, without restrictions on the base field, save for that it be of generic characteristic. We show that the group of components of the t-motivic Galois group coincides with the absolute Galois group of the base field.Comment: To appear in Journal of Number Theor

    Open access to novel dual flow chamber technology for in vitro cell mechanotransduction, toxicity and pharamacokinetic studies

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    <p>Abstract</p> <p>Background</p> <p>A major stumbling block for researchers developing experimental models of mechanotransduction is the control of experimental variables, in particular the transmission of the mechanical forces at the cellular level. A previous evaluation of state of the art commercial perfusion chambers showed that flow regimes, applied to impart a defined mechanical stimulus to cells, are poorly controlled and that data from studies in which different chambers are utilized can not be compared, even if the target stress regimes are comparable.</p> <p>Methods</p> <p>This study provides a novel chamber design to provide both physiologically-based flow regimes, improvements in control of experimental variables, as well as ease of use compared to commercial chambers. This novel design achieves controlled stresses through five gasket designs and both single- and dual-flow regimes.</p> <p>Results</p> <p>The imparted shear stress within the gasket geometry is well controlled. Fifty percent of the entire area of the 10 × 21 mm universal gasket (Gasket I, designed to impart constant magnitude shear stresses in the center of the chamber where outcome measures are taken), is exposed to target stresses. In the 8 mm diameter circular area at the center of the chamber (where outcome measures are made), over 92% of the area is exposed to the target stress (± 2.5%). In addition, other gasket geometries provide specific gradients of stress that vary with distance from the chamber inlet. Bench-top testing of the novel chamber prototype shows improvements, in the ease of use as well as in performance, compared to the other commercial chambers. The design of the chamber eliminates flow deviations due to leakage and bubbles and allows actual flow profiles to better conform with those predicted in computational models.</p> <p>Conclusion</p> <p>The novel flow chamber design provides predictable and well defined mechanical forces at the surface of a cell monolayer, showing improvement over previously tested commercial chambers. The predictability of the imparted stress improves both experiment repeatability as well as the accuracy of inter-study comparisons. Carefully controlling the stresses on cells is critical in effectively mimicking <it>in vivo </it>situations. Overall, the improved perfusion flow chamber provides the needed resolution, standardization and <it>in vitro </it>model analogous to <it>in vivo </it>conditions to make the step towards greater use in research and the opportunity to enter the diagnostic and therapeutic market.</p

    Pure Anderson Motives and Abelian \tau-Sheaves

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    Pure t-motives were introduced by G. Anderson as higher dimensional generalizations of Drinfeld modules, and as the appropriate analogs of abelian varieties in the arithmetic of function fields. In order to construct moduli spaces for pure t-motives the second author has previously introduced the concept of abelian \tau-sheaf. In this article we clarify the relation between pure t-motives and abelian \tau-sheaves. We obtain an equivalence of the respective quasi-isogeny categories. Furthermore, we develop the elementary theory of both structures regarding morphisms, isogenies, Tate modules, and local shtukas. The later are the analogs of p-divisible groups.Comment: final version as it appears in Mathematische Zeitschrif

    Pure Anderson Motives over Finite Fields

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    In the arithmetic of function fields Drinfeld modules play the role that elliptic curves take on in the arithmetic of number fields. As higher dimensional generalizations of Drinfeld modules, and as the appropriate analogues of abelian varieties, G. Anderson introduced pure t-motives. In this article we study the arithmetic of the later. We investigate which pure t-motives are semisimple, that is, isogenous to direct sums of simple ones. We give examples for pure t-motives which are not semisimple. Over finite fields the semisimplicity is equivalent to the semisimplicity of the endomorphism algebra, but also this fails over infinite fields. Still over finite fields we study the endomorphism rings of pure t-motives and criteria for the existence of isogenies. We obtain answers which are similar to Tate's famous results for abelian varieties.Comment: v2: final version to appear in Journal of Number Theory. Note, this is the second part of the two-in-one article arXiv:math.NT/060973

    Rotating Superconductors and the London Moment: Thermodynamics versus Microscopics

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    Comparing various microscopic theories of rotating superconductors to the conclusions of thermodynamic considerations, we traced their marked difference to the question of how some thermodynamic quantities (the electrostatic and chemical potentials) are related to more microscopic ones: The electron's the work function, mean-field potential and Fermi energy -- certainly a question of general import. After the correct identification is established, the relativistic correction for the London Moment is shown to vanish, with the obvious contribution from the Fermi velocity being compensated by other contributions such as electrostatics and interactions.Comment: 23 pages 4 fi

    Study Protocol for a Cluster-Randomized Trial of a Bundle of Implementation Support Strategies to Improve the Fidelity of Implementation of Schoolwide Positive Behavioral Interventions and Supports in Rural Schools

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    Background: Improving the implementation of evidence-based interventions is important for population-level impacts. Positive Behavioral Interventions and Supports (PBIS) is effective for improving school climate and students’ behavioral outcomes, but rural schools often lag behind urban and suburban schools in implementing such initiatives. Methods/Design: This paper describes a Type 3 hybrid implementation-effectiveness trial of Rural School Support Strategies (RS3), a bundle of implementation support strategies selected to improve implementation outcomes in rural schools. In this two-arm parallel group trial, 40 rural public schools are randomized to receive: 1) a series of trainings about PBIS; or 2) an enhanced condition with training plus RS3. The trial was planned for two years, but due to the pandemic has been extended another year. RS3 draws from the Interactive Systems Framework, with a university-based team (support system) that works with a team at each school (school-based delivery system), increasing engagement through strategies such as: providing technical assistance, facilitating school team functioning, and educating implementers. The primary organizational-level outcome is fidelity of implementation, with additional implementation outcomes of feasibility, acceptability, appropriateness, and cost. Staff-level outcomes include perceived climate and self-reported adoption of PBIS core components. Student-level outcomes include disciplinary referrals, academic achievement, and perceived climate. Mediators being evaluated include organizational readiness, school team functioning, and psychological safety. Discussion: The study tests implementation strategies, with strengths including a theory-based design, mixed methods data collection, and consideration of mediational mechanisms. Results will yield knowledge about how to improve implementation of universal prevention initiatives in rural schools

    A Phase 1 Randomized, Placebo-controlled, Observer-blinded Trial to Evaluate the Safety and Immunogenicity of Inactivated Streptococcus pneumoniae Whole-cell Vaccine in Adults

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    BACKGROUND: Broadly protective pneumococcal vaccines that are affordable for low-resource countries are needed. Streptococcus pneumoniae whole cell vaccine (wSp) is an investigational vaccine that contains killed cells from a nonencapsulated strain of S. pneumoniae (SPn) with aluminum hydroxide adjuvant. Studies in mice demonstrated protection against nasopharyngeal carriage (T-cell-mediated) and invasive pneumococcal disease (antibody-mediated). The aim of this randomized, double-blind, placebo-controlled Phase 1 study was to assess safety, tolerability and immunogenicity of wSp in healthy adults. METHODS: Forty-two participants were randomized into 3 dose cohorts to receive 0.1, 0.3, or 0.6 mg of wSp or saline intramuscularly. Participants received a 3-dose vaccination schedule spaced by 4-week intervals. Postvaccination assessments included solicited reactogenicity events through day 7, blood chemistry and hematology assessments at day 7, and adverse events (AEs) through day 84. Participants were monitored for serum antibody and peripheral blood mononuclear cell cytokine responses to pneumococcal antigens. A 6-month telephone follow-up was completed to assess for any additional AEs. RESULTS: wSp was safe and well tolerated. Reactogenicity was acceptable and no untoward safety signals were observed. wSp elicited potentially clinically significant rises (defined arbitrarily as at least a 2-fold rise) in immunoglobulin G responses to multiple pneumococcal antigens, including pneumococcal surface protein A and pneumolysin. Functional antibody responses were observed with the highest dose of wSp (0.6 mg). Increases in T-cell cytokine responses, including interleukin 17A, were also seen among wSp vaccines. CONCLUSIONS: wSp was safe and well tolerated in healthy US adults, eliciting pneumococcal antigen-specific antibody and T-cell cytokine responses

    Voices About Choices: The Role of Female Networks in Affirming Life Choices in the Academy

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    This essay addresses the topic of women\u27s professional development in the academy, noting the critical roles fulfilled by support networks. Research and personal narratives explore the diverse choices women make, the resistance they sometimes face, and the need to find validation for those choices. Recognizing the importance of women\u27s achievement of tenure and publication, the authors also challenge the notion that those traditional measures of academic success are the only, or the best, way to assess women\u27s professional development
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