28 research outputs found

    Magnon-drag thermopower and Nernst coefficient in Fe, Co, and Ni

    Full text link
    Magnon-drag is shown to dominate the thermopower of elemental Fe from 2 to 80 K and of elemental Co from 150 to 600 K; it is also shown to contribute to the thermopower of elemental Ni from 50 to 500 K. Two theoretical models are presented for magnon-drag thermopower. One is a hydrodynamic theory based purely on non-relativistic, Galilean, spin-preserving electron-magnon scattering. The second is based on spin-motive forces, where the thermopower results from the electric current pumped by the dynamic magnetization associated with a magnon heat flux. In spite of their very different microscopic origins, the two give similar predictions for pure metals at low temperature, allowing us to semi-quantitatively explain the observed thermopower of elemental Fe and Co without adjustable parameters. We also find that magnon-drag may contribute to the thermopower of Ni. A spin-mixing model is presented that describes the magnon-drag contribution to the Anomalous Nernst Effect in Fe, again enabling a semi-quantitative match to the experimental data without fitting parameters. Our work suggests that particle non-conserving processes may play an important role in other types of drag phenomena, and also gives a predicative theory for improving metals as thermoelectric materials.Comment: main text plus 7 figures; accepted in PRB September 201

    Immunologic and Hematopoietic Effects of CD40 Stimulation after Syngeneic Bone Marrow Transplantation in Mice

    Get PDF
    CD40 is a molecule present on multiple cell types including B lymphocyte lineage cells. CD40 has been shown to play an important role in B cell differentiation and activation in vitro, although little is known concerning the effects of CD40 stimulation in vivo. We therefore examined the effects of CD40 stimulation in mice using a syngeneic bone marrow transplantation (BMT) model in an effort to augment B cell recovery after high dose therapy with hematopoietic reconstitution. After the BMT, mice were treated with or without 2-6 ÎĽg of a soluble recombinant murine CD40 ligand (srmCD40L) given intraperitoneally twice a week. A significant increase in B cell progenitors (B220 +/surface IgM -) was observed in the bone marrow of mice receiving the srmCD40L. The treated recipients also demonstrated improved B-cell function with increases in total serum immunoglobulin and increased splenic mitogen responsiveness to LPS being noted. Additionally, srmCD40L treatment promoted secondary lymphoid organ repopulation, accelerating germinal center formation in the lymph nodes. Total B cell numbers in the periphery were not significantly affected even with continuous srmCD40L administration. Lymphocytes obtained from mice treated with the ligand also had increases in T cell mitogen and anti-CD3 mAb responsiveness and acquired the capability to produce IL-4. Surprisingly, treatment with srmCD40L also produced hematopoietic effects in mice, resulting in an increase of BM and splenic hematopoietic progenitor cells in the mice after BMT. Treatment with srmCD40L significantly increased granulocyte and platelet recovery in the peripheral blood. Incubation of BMC with srmCD40L in vitro also resulted in increased progenitor proliferation, demonstrating that the hematopoietic effects of the ligand may be direct. Thus, stimulation of CD40 by its ligand may he beneficial in accelerating both immune and hematopoietic recovery in the setting of bone marrow transplantation

    Documenting the agriculture based indigenous traditional knowledge in Manipur State of North Eastern India

    Get PDF
    The North East Indian Himalayan Region (NEIHR) is bestowed with unique ethnicity and highly diversified biodiversity (flora and fauna) that are inherent to this region and inquisitive traditional practices. The region is a conservatory of indigenous knowledge and practices.  NE agriculture has its own merit, demerit, diversity and complex system which distinguishes it from the mainland agriculture of the country. Indigenous knowledge used in agriculture in various parts of Manipur is still less explored. Keeping this as the foremost point, survey was undertaken for collecting information on traditional knowledge in 8 districts of 15 villages of Manipur for identifying the different indigenous traditional knowledge (ITK) used in agriculture. Each district was surveyed and from each selected locality and interviewed through questionnaires for collecting relevant information on ITKs used in agriculture. Initially the detail information was collected from respondent farmers and further validated by triangulation method. 15 number of ITK has been documented and validated by triangulation method. There is a strong requisite to document and validate ITK before it gets lost with time. So, indigenous and modern approach may be combined as the so called “technology blending” for the evolution of new technology

    The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

    Get PDF
    The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure

    The Virtual Sociality of Rights: The Case of Women\u27s Rights are Human Rights

    Get PDF
    This essay traces the relationship between activists and academics involved in the campaign for women\u27s rights as human rights as a case study of the relationship between different classes of what I call knowledge professionals self-consciously acting in a transnational domain. The puzzle that animates this essay is the following: how was it that at the very moment at which a critique of rights and a reimagination of rights as rights talk proved to be such fertile ground for academic scholarship did the same rights prove to be an equally fertile ground for activist networking and lobbying activities? The paper answers this question with respect to the work of self-reflexivity in creating a virtual sociality of rights