909 research outputs found

    The executive toolbox:building legislative support in a multiparty presidential regime

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    How do presidents win legislative support under conditions of extreme multipartism?Comparative presidential research has offered two parallel answers, one relying on distributivepolitics and the other claiming that legislative success is a function of coalition formation. Wemerge these insights in an integrated approach to executive-legislative relations, also addingcontextual factors related to dynamism and bargaining conditions. We find that the twopresidential “tools” – pork and coalition goods – are substitutable resources, with porkfunctioning as a fine-tuning instrument that interacts reciprocally with legislative support. Porkexpenditures also depend upon a president’s bargaining leverage and the distribution oflegislative seats.

    Scaling Symmetries of Scatterers of Classical Zero-Point Radiation

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    Classical radiation equilibrium (the blackbody problem) is investigated by the use of an analogy. Scaling symmetries are noted for systems of classical charged particles moving in circular orbits in central potentials V(r)=-k/r^n when the particles are held in uniform circular motion against radiative collapse by a circularly polarized incident plane wave. Only in the case of a Coulomb potential n=1 with fixed charge e is there a unique scale-invariant spectrum of radiation versus frequency (analogous to zero-point radiation) obtained from the stable scattering arrangement. These results suggest that non-electromagnetic potentials are not appropriate for discussions of classical radiation equilibrium.Comment: 13 page

    Plasma spray nozzle with low overspray and collimated flow

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    An improved nozzle for reducing overspray in high temperature supersonic plasma spray devices comprises a body defining an internal passageway having an upstream end and a downstream end through which a selected plasma gas is directed. The nozzle passageway has a generally converging/diverging Laval shape with its upstream end converging to a throat section and its downstream end diverging from the throat section. The upstream end of the passageway is configured to accommodate a high current cathode for producing an electrical arc in the passageway to heat and ionize the gas flow to plasma form as it moves along the passageway. The downstream end of the nozzle is uniquely configured through the methodology of this invention to have a contoured bell-shape that diverges from the throat to the exit of the nozzle. Coating material in powder form is injected into the plasma flow in the region of the bell-shaped downstream end of the nozzle and the powder particles become entrained in the flow. The unique bell shape of the nozzle downstream end produces a plasma spray that is ideally expanded at the nozzle exit and thus virtually free of shock phenomena, and that is highly collimated so as to exhibit significantly reduced fanning and diffusion between the nozzle and the target. The overall result is a significant reduction in the amount of material escaping from the plasma stream in the form of overspray and a corresponding improvement in the cost of the coating operation and in the quality and integrity of the coating itself

    High-Temperature Crystal-Growth Cartridge Tubes Made by VPS

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    Cartridge tubes for use in a crystal growth furnace at temperatures as high as 1,600 deg. C have been fabricated by vacuum plasma spraying (VPS). These cartridges consist mainly of an alloy of 60 weight percent molybdenum with 40 weight percent rhenium, made from molybdenum powder coated with rhenium. This alloy was selected because of its high melting temperature (approximately equal.2,550 C) and because of its excellent ductility at room temperature. These cartridges are intended to supplant tungsten/nickel-alloy cartridges, which cannot be used at temperatures above approximately equal 1,300 C

    Derivation of the Planck Spectrum for Relativistic Classical Scalar Radiation from Thermal Equilibrium in an Accelerating Frame

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    The Planck spectrum of thermal scalar radiation is derived suggestively within classical physics by the use of an accelerating coordinate frame. The derivation has an analogue in Boltzmann's derivation of the Maxwell velocity distribution for thermal particle velocities by considering the thermal equilibrium of noninteracting particles in a uniform gravitational field. For the case of radiation, the gravitational field is provided by the acceleration of a Rindler frame through Minkowski spacetime. Classical zero-point radiation and relativistic physics enter in an essential way in the derivation which is based upon the behavior of free radiation fields and the assumption that the field correlation functions contain but a single correlation time in thermal equilibrium. The work has connections with the thermal effects of acceleration found in relativistic quantum field theory.Comment: 23 page

    Nano powders, components and coatings by plasma technique

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    Ultra fine and nanometer powders and a method of producing same are provided, preferably refractory metal and ceramic nanopowders. When certain precursors are injected into the plasma flame in a reactor chamber, the materials are heated, melted and vaporized and the chemical reaction is induced in the vapor phase. The vapor phase is quenched rapidly to solid phase to yield the ultra pure, ultra fine and nano product. With this technique, powders have been made 20 nanometers in size in a system capable of a bulk production rate of more than 10 lbs/hr. The process is particularly applicable to tungsten, molybdenum, rhenium, tungsten carbide, molybdenum carbide and other related materials

    Evaluation of denoising strategies to address motion-correlated artifacts in resting-state functional magnetic resonance imaging data from the human connectome roject

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    Like all resting-state functional connectivity data, the data from the Human Connectome Project (HCP) are adversely affected by structured noise artifacts arising from head motion and physiological processes. Functional connectivity estimates (Pearson's correlation coefficients) were inflated for high-motion time points and for high-motion participants. This inflation occurred across the brain, suggesting the presence of globally distributed artifacts. The degree of inflation was further increased for connections between nearby regions compared with distant regions, suggesting the presence of distance-dependent spatially specific artifacts. We evaluated several denoising methods: censoring high-motion time points, motion regression, the FMRIB independent component analysis-based X-noiseifier (FIX), and mean grayordinate time series regression (MGTR; as a proxy for global signal regression). The results suggest that FIX denoising reduced both types of artifacts, but left substantial global artifacts behind. MGTR significantly reduced global artifacts, but left substantial spatially specific artifacts behind. Censoring high-motion time points resulted in a small reduction of distance-dependent and global artifacts, eliminating neither type. All denoising strategies left differences between high- and low-motion participants, but only MGTR substantially reduced those differences. Ultimately, functional connectivity estimates from HCP data showed spatially specific and globally distributed artifacts, and the most effective approach to address both types of motion-correlated artifacts was a combination of FIX and MGTR

    A first ceramic chronology for the Late Islamic Arabian Gulf

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    © Equinox Publishing Ltd. Islamic archaeology in the Arabian Gulf has grown tremendously in recent years. However, a ceramic chronology for the Late Islamic Arabian Gulf has not yet been put forward. The present paper constitutes a first attempt at a refined periodization based on the occupational sequence of al-Ain, UAE. The study is based on the typological quantification of sherds from stratified excavations undertaken by the Historic Buildings and Landscapes Section of the Tourism and Culture Authority Abu Dhabi. It is broadly based on the methodology developed by Derek Kennet in his much-cited Sasanian and Islamic Pottery from Ras al-Khaimah (2004). The c. 13,500-sherd assemblage has been divided into six periods of thirty to seventy years spanning the later seventeenth to mid-twentieth centuries. The al-Ain assemblage is compared to published ceramics from contemporary sites in the Gulf region and further compared to relevant historical sources to draw out the wider implications of the findings. The present study constitutes an interim report and full publication of ceramics from al-Ain will appear in a multi-authored pottery handbook currently in preparation

    Electropermanent magnetic anchoring for surgery and endoscopy

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    The use of magnets for anchoring of instrumentation in minimally invasive surgery and endoscopy has become of increased interest in recent years. Permanent magnets have significant advantages over electromagnets for these applications; larger anchoring and retraction force for comparable size and volume without the need for any external power supply. However, permanent magnets represent a potential hazard in the operating field where inadvertent attraction to surgical instrumentation is often undesirable. The current work proposes an interesting hybrid approach which marries the high forces of permanent magnets with the control of electromagnetic technology including the ability to turn the magnet OFF when necessary. This is achieved through the use of an electropermanent magnet, which is designed for surgical retraction across the abdominal and gastric walls. Our electropermanent magnet, which is hand-held and does not require continuous power, is designed with a center lumen which may be used for trocar or needle insertion. The device in this application has been demonstrated successfully in the porcine model where coupling between an intraluminal ring magnet and our electropermanent magnet facilitated guided insertion of an 18 Fr Tuohy needle for guidewire placement. Subsequent investigations have demonstrated the ability to control the coupling distance of the system alleviating shortcomings with current methods of magnetic coupling due to variation in transabdominal wall thicknesses. With further refinement, the magnet may find application in the anchoring of endoscopic and surgical instrumentation for minimally invasive interventions in the gastrointestinal tract

    A Comparison of Soviet and American Maritime Arbitration

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    Maritime arbitration has a long history both in the United States, where it dates from the late 19th century, and in the Soviet Union, where the permanent arbitration body known as the Maritime Arbitration Commission (MAC or Commission) has existed since 1930. Although both countries have similar procedures for maritime arbitration, the history, ideology, and commercial goals of each country have created systems that differ markedly in approach and style. The American experience has fostered an ad hoc system where the parties establish arbitration panels as disputes arise and where the parties have almost unlimited discretion in choosing arbitrators and rules. By contrast, the Soviet system has established a permanent arbitration body with a limited choice of arbitrators and rules. The contrast between two such differing systems can shed considerable light on each of them. This Note will discuss the major aspects of Soviet maritime arbitration with reference to the relevant portions of the MAC\u27s statute and Rules of Procedure. It will then consider American maritime arbitration with particular emphasis on arbitration in New York under the rules and procedures of the Society of Maritime Arbitrators (SMA or Society). Finally, this Note will compare and contrast the two systems of arbitration
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