3,927 research outputs found
Radiative, actively cooled panel tests results
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
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
We present the results of a velocity correlation study of the high latitude
cloud MBM16 using a fully sampled CO map, supplemented by new 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
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
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
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
Chaos synchronization in time-delayed systems with parameter mismatches and variable delay times
Phosphine generator trial using external air dilution
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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