3,927 research outputs found

    Radiative, actively cooled panel tests results

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    The radiative, actively cooled panel designed to withstand a uniform incident heat flux of 136 kW/sq m to a 444 K surface temperature was evaluated. The test program consisted of preliminary static thermal mechanical loading and aerothermal flow tests. Test results are briefly discussed

    Dark-State Polaritons for multi-component and stationary light fields

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    We present a general scheme to determine the loss-free adiabatic eigensolutions (dark-state polaritons) of the interaction of multiple probe laser beams with a coherently driven atomic ensemble under conditions of electromagnetically induced transparency. To this end we generalize the Morris-Shore transformation to linearized Heisenberg-Langevin equations describing the coupled light-matter system in the weak excitation limit. For the simple lambda-type coupling scheme the generalized Morris-Shore transformation reproduces the dark-state polariton solutions of slow light. Here we treat a closed-loop dual-V scheme wherein two counter-propagating control fields generate a quasi stationary pattern of two counter-propagating probe fields -- so-called stationary light. We show that contrary to previous predictions,there exists a single unique dark-state polariton; it obeys a simple propagation equation.Comment: 6 pages, 2 figure

    A Dynamical Study of the Non-Star Forming Translucent Molecular Cloud MBM16: Evidence for Shear Driven Turbulence in the Interstellar Medium

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    We present the results of a velocity correlation study of the high latitude cloud MBM16 using a fully sampled 12^{12}CO map, supplemented by new 13^{13}CO data. We find a correlation length of 0.4 pc. This is similar in size to the formaldehyde clumps described in our previous study. We associate this correlated motion with coherent structures within the turbulent flow. Such structures are generated by free shear flows. Their presence in this non-star forming cloud indicates that kinetic energy is being supplied to the internal turbulence by an external shear flow. Such large scale driving over long times is a possible solution to the dissipation problem for molecular cloud turbulence.Comment: Uses AAS aasms4.sty macros. Accepted for publication in Ap

    Bilingual episodic memory: an introduction

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    Our current models of bilingual memory are essentially accounts of semantic memory whose goal is to explain bilingual lexical access to underlying imagistic and conceptual referents. While this research has included episodic memory, it has focused largely on recall for words, phrases, and sentences in the service of understanding the structure of semantic memory. Building on the four papers in this special issue, this article focuses on larger units of episodic memory(from quotidian events with simple narrative form to complex autobiographical memories) in service of developing a model of bilingual episodic memory. This requires integrating theory and research on how culture-specific narrative traditions inform encoding and retrieval with theory and research on the relation between(monolingual) semantic and episodic memory(Schank, 1982; Schank & Abelson, 1995; Tulving, 2002). Then, taking a cue from memory-based text processing studies in psycholinguistics(McKoon & Ratcliff, 1998), we suggest that as language forms surface in the progressive retrieval of features of an event, they trigger further forms within the same language serving to guide a within-language/ within-culture retrieval

    Anticoagulation Management and Heparin Resistance During Cardiopulmonary Bypass: A Survey of Society of Cardiovascular Anesthesiologists Members

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    We surveyed Society of Cardiovascular Anesthesiologists members regarding anticoagulation practices for cardiopulmonary bypass and attitudes on heparin resistance. Of 550 respondents (18.5% response rate), 74.9% (95% CI, 71.3%-78.5%) used empiric weight-based dosing of heparin, and 70.7% (95% CI, 66.9%-74.5%) targeted an activated clotting time of either 400 or 480 seconds to initiate cardiopulmonary bypass. Of note, 17.1% (95% CI, 13.9%-20.2%) of respondents reported activated clotting time targets lower than those recommended by recent 2018 Society of Thoracic Surgeons/Society of Cardiovascular Anesthesiologists/American Society of Extracorporeal Technology guidelines or failed to monitor heparin effects at all. When heparin resistance was encountered, 54.2% of respondents (95% CI, 50.0%-58.4%) administered antithrombin concentrates as a first-line therapy

    Rigid invariance as derived from BRS invariance: The abelian Higgs model

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    Consequences of a symmetry, e.g.\ relations amongst Green functions, are renormalization scheme independently expressed in terms of a rigid Ward identity. The corresponding local version yields information on the respective current. In the case of spontaneous breakdown one has to define the theory via the BRS invariance and thus to construct rigid and current Ward identity non-trivially in accordance with it. We performed this construction to all orders of perturbation theory in the abelian Higgs model as a prelude to the standard model. A technical tool of interest in itself is the use of a doublet of external scalar ``background'' fields. The Callan-Symanzik equation has an interesting form and follows easily once the rigid invariance is established.Comment: 33 pages, Plain Te

    Phosphine generator trial using external air dilution

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    A commercial phosphine (PH3) generator manufactured by Beijing Liangmao Technology Development Company Limited, China was used in a fumigation trial on 5000 tonne bunker storage. The generator’s production of PH3 is controlled by the rate of dosing conventional aluminum phosphide (AlP) tablets into 100 kg water in the reaction chamber.Because PH3 is flammable and explosive if certain a concentration is reached in air, it is usually mixed with carbon dioxide (CO2) in the weight ratio of 50:1. This trial’s objective was to minimise the amount of CO2 and dilute the generated PH3 with air. The PH3 generated is purged from the reaction chamber by a continuous low flow of regulated CO2 gas. The PH3-rich CO2 purge stream was fed into the suction inlet of an external venturi. A high pressure fan was used to produce the air flow through the venturi to create the vacuum to suck in and dilute the PH3 rich stream from the generator. The PH3 was diluted in the air-flow to ensure a non-flammable concentration of less than 1% (10.000 ppm) and thence fed directly into the bunker storage. The trial successfully demonstrated the viability of generating phosphine in this manner, and excellent results in PH3 concentration and distribution was achieved in very short time periods. The capacity of the generator was limited to 8 kg of AlP tablets, equivalent to 2.667 kg of PH3, or sufficient to fumigate 2667 m3 of grain at a dosage rate of 1 g/m3. A much larger version of the machine would be required to fumigate medium size bunker storages in the 10.000 to 15.000 tonne range. Notwithstanding, the generator offers an attractive package combining the speed and convenience associated with the use of gaseous PH3 with the low cost of AlP formulations. Keywords: Phosphine fumigant, On-site generator, Metallic phosphide, Non-flammabl
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