2,889 research outputs found

    Sudden Flight and True Sudden Stops

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    We extend the sudden stops literature by allowing crisis episodes to be caused by either the retreat of global investors, as is assumed but not shown in the extant literature, or the sudden flight of local investors. We find that almost half of the previously defined sudden stops are actually episodes of sudden flight. Compared to sudden flight, true sudden stops are bunched and are associated with greater slowdowns in economic activity and sharper currency depreciations. We show that the empirical regularities of sudden flight and true sudden stops are consistent with theoretical models that incorporate gross capital flows and information asymmetries.international capital flows, capital flight, emerging market crises

    A specific biosynthetic marker for immature thymic lymphoblasts. Active synthesis of thymus-leukemia antigen restricted to proliferating cells

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    Large cortical thymocytes from C57BL/6-Tla(a) mice have been prepared rapidly and in high yield by a combination of centrifugal elutriation and differential binding to peanut agglutinin (PNA)-coated plates. The cells in these lymphoblast-rich fractions were clearly distinct from the majority of thymocytes, with up to 70 percent in the S or G(2) + M phases of the cell cycle and an average rate of [(35)S]methionine incorporation per cell up to 20 times higher than that of the majority population. The populations of cells resolved in this fractionation were characterized by monitoring their rates of synthesis of specific glycoproteins, thymus- leukemia antigen (TL) and the Lyt-2, Lyt-3 complex (Lyt-2/3), relative to their total protein synthesis. Cells that bound to PNA synthesized high levels of Lyt-2/3, consistent with their identification as cortical thymocytes. Those that failed to bind made little or no Lyt-2/3, as expected for medullary cells, The fraction of dividing lymphoblasts that bound to PNA was enriched in cortical thymocyte precursors, including all the large cells detectably active in synthesizing Lyt-2. It differed sharply from the small cortical cells, however, in the synthesis of TL. Although both populations displayed abundant surface TL, the TL glycoprotein was produced actively in fractions containing dividing cells but made at a drastically reduced rate by the nondividing majority of cortical thymocytes. Thus, TL seems to be made at a narrowly circumscribed stage of early thymocyte development that is correlated with rapid proliferation. In most of the descendants of such blast cells, the TL glycoprotein is presumably retained on the cell surface as long as no substantial membrane turnover takes place. Ongoing TL synthesis may therefore serve as a marker for a unique developmental state which terminates rapidly in normal differentiation but may be extended by agents that give rise to TL(+) thymic lymphomas

    GRBs from unstable Poynting dominated outflows

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    Poynting flux driven outflows from magnetized rotators are a plausible explanation for gamma-ray burst engines. We suggest a new possibility for how such outflows might transfer energy into radiating particles. We argue that the Poynting flux drives non-linearly unstable large amplitude electromagnetic waves (LAEMW) which ``break'' at radii rt∌1014r_t \sim 10^{14} cm where the MHD approximation becomes inapplicable. In the ``foaming'' (relativisticly reconnecting) regions formed during the wave breaks the random electric fields stochastically accelerate particles to ultrarelativistic energies which then radiate in turbulent electromagnetic fields. The typical energy of the emitted photons is a fraction of the fundamental Compton energy ϔ∌fℏc/re \epsilon \sim f \hbar c/r_e with f∌10−3f \sim 10^{-3} plus additional boosting due to the bulk motion of the medium. The emission properties are similar to synchrotron radiation, with a typical cooling time ∌10−4\sim 10^{-4} sec. During the wave break, the plasma is also bulk accelerated in the outward radial direction and at larger radii can produce afterglows due to the interactions with external medium. The near equipartition fields required by afterglow models maybe due to magnetic field regeneration in the outflowing plasma (similarly to the field generation by LAEMW of laser-plasma interactions) and mixing with the upstream plasma.Comment: 15 pages, 1 figur

    By and For Jewish Women Only: The Musical Film The Heart That Sings

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    The musical film, “The Heart that Sings” (2011), written and directed by Robin Saex Garbose, is part of a genre of films created by and for Orthodox Jewish women. Heart provides a case study that illustrates the depth and breadth of Lubavitch Rebbe Menachem Mendel Schneerson’s (1902-1994) influence on Jews and Jewish life well beyond his own community members. Schneerson’s outreach work via his shlichim, or emissaries, to unobservant Jews is well-recognized. The extent and nuance of his influence on a broad cross-section of Jews, however, has yet to be fully traced. Heart tells its viewers that Jewish women from all backgrounds can create an empowered, unified community, if religiously observant, Orthodox practices are in place, perpetuating Schneerson’s message with a feminist bent and musical twist

    Lyt-2 glycoprotein is synthesized as a single molecular species

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    We investigated the possibility that the Lyt-2 molecules made by uncloned mouse T lymphocytes would show variable primary structures like those of immunoglobulins. Newly synthesized Lyt-2/3 complexes were found to include only two major components, both discrete glycoproteins with apparent molecular weights of 31,000 (31 K) and 35,000 (35 K). When products of Lyt-2.1 and Lyt-2.2 thymocytes were compared by two-dimensional nonequilibrium pH gradient electrophoresis and sodium dodecyl sulfate polyacrylamide gel electrophoresis, the isoelectric points of the 35 K molecules were different; thus, the 35 K component was likely to be encoded by the Lyt-2 locus itself. However, the 35 K molecules made by any one genotype were homogeneous in charge as well as in size. The homogeneity was obscured rapidly by post-translational modification. Most strikingly, within 30 min of initial synthesis, these processing events generated the conspicuous array of microheterogeneous products that form the "38 K" component of cell-surface Lyt-2/3

    Large-scale educational telecommunications systems for the US: An analysis of educational needs and technological opportunities

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    The needs to be served, the subsectors in which the system might be used, the technology employed, and the prospects for future utilization of an educational telecommunications delivery system are described and analyzed. Educational subsectors are analyzed with emphasis on the current status and trends within each subsector. Issues which affect future development, and prospects for future use of media, technology, and large-scale electronic delivery within each subsector are included. Information on technology utilization is presented. Educational telecommunications services are identified and grouped into categories: public television and radio, instructional television, computer aided instruction, computer resource sharing, and information resource sharing. Technology based services, their current utilization, and factors which affect future development are stressed. The role of communications satellites in providing these services is discussed. Efforts to analyze and estimate future utilization of large-scale educational telecommunications are summarized. Factors which affect future utilization are identified. Conclusions are presented

    Introduction

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