2,528 research outputs found

    Global Security, Climate Change, and the Arctic

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    This issue of Swords and Ploughshares examines the complex set of global security challenges that are emerging as a result of warmer temperatures and melting ice in the Arctic region. For policymakers and analysts alike, the contemporary Arctic presents a particularly acute convergence of compelling problems and opportunities related to global security, foreign affairs, climate change, environmentalism, international law, energy economics, and the rights of indigenous populations. The goals of this publication are two-fold: to provide thoughtful analysis of recent developments in the Arctic both from scientific and geopolitical perspectives; and to offer careful and informed assessments of how evolving conditions in the Arctic might impact the broader global security framework and relations between the international actors involved, not to mention the region’s inhabitants and ecosystem. The articles in this issue were contributed by each of four panelists invited by the Program in Arms Control, Disarmament, and International Security (ACDIS), the European Union Center, and the Russian, East European, and Eurasian Center at the University of Illinois to participate in a November 2009 symposium entitled “Global Security, Climate Change, and the Arctic: Implications of an Open Northwest Passage.” The symposium and this publication were supported through grants to the host centers from the European Commission, the US Department of Education (Title VI international education program), and the John D. and Catherine T. MacArthur Foundation.published or submitted for publicationnot peer reviewe

    A Candidate for Exact Continuum Dual Theory for Scalar QED3_3

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    We discuss a possible exact equivalence of the Abelian Higgs model and a scalar theory of a magnetic vortex field in 2+1 dimensions. The vortex model has a current - current interaction and can be viewed as a strong coupling limit of a massive vector theory. The fixed point structure of the theory is discussed and mapped into fixed points of the Higgs model.Comment: 17 pages, 1 figure available on request, LA-UR-93-83

    Signature of Schwinger's pair creation rate via radiation generated in graphene by strong electric current

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    Electron - hole pairs are copuously created by an applied electric field near the Dirac point in graphene or similar 2D electronic systems. It was shown recently that for sufficiently large electric fields and ballistic times the I-V characteristics become strongly nonlinear due to Schwinger's pair creation. Since there is no energy gap the radiation from the pairs' annihilation is enhanced. The spectrum of radiation is calculated. The angular and polarization dependence of the emitted photons with respect to the graphene sheet is quite distinctive. For very large currents the recombination rate becomes so large that it leads to the second Ohmic regime due to radiation friction.Comment: 9 pages, 7 figure

    Can NATO Survive Afghanistan?

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    Since 2003, the North Atlantic Treaty Organization has led the operation of the International Security Assistance Force (ISAF) to “establish conditions in which Afghanistan can enjoy a representative government and self-sustaining peace and security.” However, ISAF has struggled to bring stability to Afghanistan, prompting concerns about its chances for meeting those objectives. Moreover, senior U.S. officials referred in spring 2008 to a possible “existential crisis” for NATO, as a result of tensions within the alliance over member countries’ troop-level and mission task commitments to ISAF. This collection of articles examines the significant challenges facing NATO as it conducts its first mission outside the Euro-Atlantic arena in its nearly sixty-year history.published or submitted for publicationnot peer reviewe

    VASCOMP 2. The V/STOL aircraft sizing and performance computer program. Volume 6: User's manual, revision 3

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    This report describes the use of the V/STOL Aircraft Sizing and Performance Computer Program (VASCOMP II). The program is useful in performing aircraft parametric studies in a quick and cost efficient manner. Problem formulation and data development were performed by the Boeing Vertol Company and reflects the present preliminary design technology. The computer program, written in FORTRAN IV, has a broad range of input parameters, to enable investigation of a wide variety of aircraft. User oriented features of the program include minimized input requirements, diagnostic capabilities, and various options for program flexibility

    Alumina Size Distributions from High-Pressure Composite Solid-Propellant Combustion

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    Alumina size distributions were obtained for both a coarse and a fine oxidizer composite propellant burning in a nitrogen atmosphere over the pressure range from atmospheric to 500 pounds per square inch. The amount of additive agglomeration was found to be significantly higher for the coarse oxidizer propellant and decreased with increasing pressure to the 0.3 power over the range from atmospheric pressure to 250 pounds per square inch. High-speed photographs of the burning propellant surface revealed that the additives moved on the surface with the average particle velocity decreasing with pressure to approximately the 0.3 power over the pressure range from atmospheric to 50 pounds per square inch. The empirical relation between particle velocity and pressure was used to modify an agglomeration criterion presented previously. Evaluation of the critical aluminum diameter required for agglomeration indicated that both propellant types used in this study should experience some agglomeration over the pressure range studied. The aluminum size required for agglomeration was found to increase with increasing pressure. The experimental findings of the critical aluminum diameter required for agglomeration were in reasonable agreement with the calculated data. The volume mean diameter of the alumina was found to decrease with increasing pressure
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