314 research outputs found

    Evidence for a Ru4+^{4+} Kondo Lattice in LaCu3_3Ru4_4O12_{12}

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    Rare dd-electron derived heavy-fermion properties of the solid-solution series LaCu3_3Rux_xTi4x_{4-x}O12_{12} were studied for 1x41 \leq x \leq 4 by resistivity, susceptibility, specific-heat measurements, and magnetic-resonance techniques. The pure ruthenate (x=4x = 4) is a heavy-fermion metal characterized by a resistivity proportional to T2T^2 at low temperatures TT. The coherent Kondo lattice formed by the localized Ru 4dd electrons is screened by the conduction electrons leading to strongly enhanced effective electron masses. By increasing titanium substitution the Kondo lattice becomes diluted resulting in single-ion Kondo properties like in the paradigm 4f4f-based heavy-fermion compound Cex_xLa1x_{1-x}Cu2.05_{2.05}Si2_2 [M. Ocko {\em et al.}, Phys. Rev. B \textbf{64}, 195106 (2001)]. In LaCu3_3Rux_xTi4x_{4-x}O12_{12} the heavy-fermion behavior finally breaks down on crossing the metal-to-insulator transition close to x=2x = 2.Comment: 9 pages, 8 figure

    Tax revenue performance and vulnerability in developing countries

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    This paper addresses vulnerability of revenue to external shocks using export composition to capture economic structure and differentiating countries according to income levels, resource endowments and political regimes. This gives a richer characterization than previous studies. Lower income countries are vulnerable to shocks, especially in terms of trade (associated with the greatest revenue loss): democratic regimes seem to be less vulnerable to revenue losses due to shocks than non-democracies whereas revenue in resource rich is more vulnerable to shocks (except natural disasters) than non-resource rich countries. We find a negative relationship between manufacturing exports and revenue in lower income countries

    Educational Migration into Secondary Vocational Institutions in the Context of Society's Well-being

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    In this article education and educational migration into secondary vocational institutions is considered as one of the most important factors of improving the well-being of the society. Actualization of such concepts as “knowledge economics” and “smart educations” and also the emergence of new tendencies on the world educational services market (internalization of education, commercialization of education; geographical changes in educational migration) contribute to it. In the context of such changes Russian education is capable of improving its competitiveness at the expense of reconsideration of the concept of vocational education. This article presents opportunities in stimulating educational migration into Russian secondary vocational institutions under current demographic situation and deficiency of qualified workers, and also specifies some system limitations and difficulties, which can be faced when realizing the strategy of educational services export. Some of them: bad potential students’ knowledge of Russian language, poor material and technical base, old-fashioned educational facilities and persisting differences in educational systems with the other leading countries of the world, inadequate legislation, etc. Listed in the article problems call for a better managed migration policy by using modern organizational and economic solutions, providing incentives and opportunities for the population influx

    A Comprehensive Investigation of Gamma-Ray Burst Afterglows Detected by TESS

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    Gamma-ray bursts produce afterglows that can be observed across the electromagnetic spectrum and can provide insight into the nature of their progenitors. While most telescopes that observe afterglows are designed to rapidly react to trigger information, the Transiting Exoplanet Survey Satellite (TESS) continuously monitors sections of the sky at cadences between 30 minutes and 200 seconds. This provides TESS with the capability of serendipitously observing the optical afterglow of GRBs. We conduct the first extensive search for afterglows of known GRBs in archival TESS data reduced with the TESSreduce package, and detect 11 candidate signals that are temporally coincident with reported burst times. We classify 3 of these as high-likelihood GRB afterglows previously unknown to have been detected by TESS, one of which has no other afterglow detection reported on the Gamma-ray Coordinates Network. We classify 5 candidates as tentative and the remainder as unlikely. Using the afterglowpy package, we model each of the candidate light curves with a Gaussian and a top hat model to estimate burst parameters; we find that a mean time delay of 740±690740\pm690\,s between the explosion and afterglow onset is required to perform these fits. The high cadence and large field of view make TESS a powerful instrument for localising GRBs, with the potential to observe afterglows in cases when no other backup photometry is possible.Comment: 17 pages, 7 figures, 5 table

    The price of tumor control: an analysis of rare side effects of anti-CTLA-4 therapy in metastatic melanoma from the ipilimumab network

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    Background: Ipilimumab, a cytotoxic T-lymphocyte antigen-4 (CTLA-4) blocking antibody, has been approved for the treatment of metastatic melanoma and induces adverse events (AE) in up to 64% of patients. Treatment algorithms for the management of common ipilimumab-induced AEs have lead to a reduction of morbidity, e.g. due to bowel perforations. However, the spectrum of less common AEs is expanding as ipilimumab is increasingly applied. Stringent recognition and management of AEs will reduce drug-induced morbidity and costs, and thus, positively impact the cost-benefit ratio of the drug. To facilitate timely identification and adequate management data on rare AEs were analyzed at 19 skin cancer centers. Methods and Findings: Patient files (n = 752) were screened for rare ipilimumab-associated AEs. A total of 120 AEs, some of which were life-threatening or even fatal, were reported and summarized by organ system describing the most instructive cases in detail. Previously unreported AEs like drug rash with eosinophilia and systemic symptoms (DRESS), granulomatous inflammation of the central nervous system, and aseptic meningitis, were documented. Obstacles included patientś delay in reporting symptoms and the differentiation of steroid-induced from ipilimumab-induced AEs under steroid treatment. Importantly, response rate was high in this patient population with tumor regression in 30.9% and a tumor control rate of 61.8% in stage IV melanoma patients despite the fact that some patients received only two of four recommended ipilimumab infusions. This suggests that ipilimumab-induced antitumor responses can have an early onset and that severe autoimmune reactions may reflect overtreatment. Conclusion: The wide spectrum of ipilimumab-induced AEs demands doctor and patient awareness to reduce morbidity and treatment costs and true ipilimumab success is dictated by both objective tumor responses and controlling severe side effects

    Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV

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    A search for pair-production of supersymmetric particles under the assumption that R-parity is violated via a dominant LQDbar coupling has been performed using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV. The observed candidate events in the data are in agreement with the Standard Model expectation. This result is translated into lower limits on the masses of charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81 GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the 95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure
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