2,718 research outputs found

    Very Large Array Detection of the 36 GHz Zeeman Effect in DR21W Revisited

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    We report on the observation of the 36 GHz methanol maser line in the star forming region DR21W to accurately measure the Zeeman effect. The reported Zeeman signature by Fish et al. (2011) became suspicious after an instrumental effect was discovered in the early days of the Very Large Array Wide-band Digital Architecture (WIDAR) correlator commissioning. We conclude that the previously reported magnetic field strength of 58 mG ((1.7 Hz/mG)/z) is instrumental in nature and thus incorrect. With the improved performance of the array, we now deduce a 3 sigma limit of -4.7 to +0.4 mG ((1.7 Hz/mG)/z) for the line-of-sight component of the magnetic field strength in DR21W.Comment: 6 pages, 1 figure, accepted for publication in Ap

    The Effect of Oral and Intraperitoneal Administration of Alcohol upon the Concentration of Alcohol in the Blood of the Rat

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    A number of experiments were made in this laboratory to determine the rate of absorption of alcohol into the blood of rats after the administration of alcohol both orally and by intraperitoneal injection. Both fasted and unfasted rats were used in these experiments

    A Micro Method for the Determination of Ethyl Alcohol in Blood

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    In connection with some work on the physiological effects of ethyl alcohol on rats being done in this laboratory, it was essential to have a rapid and accurate method for the determination of ethyl alcohol in small samples of bloo

    Control surfaces of aquatic vertebrates: active and passive design and function

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    Aquatic vertebrates display a variety of control surfaces that are used for propulsion, stabilization, trim and maneuvering. Control surfaces include paired and median fins in fishes, and flippers and flukes in secondarily aquatic tetrapods. These structures initially evolved from embryonic fin folds in fishes and have been modified into complex control surfaces in derived aquatic tetrapods. Control surfaces function both actively and passively to produce torque about the center of mass by the generation of either lift or drag, or both, and thus produce vector forces to effect rectilinear locomotion, trim control and maneuvers. In addition to fins and flippers, there are other structures that act as control surfaces and enhance functionality. The entire body can act as a control surface and generate lift for stability in destabilizing flow regimes. Furthermore, control surfaces can undergo active shape change to enhance their performance, and a number of features act as secondary control structures: leading edge tubercles, wing-like canards, multiple fins in series, finlets, keels and trailing edge structures. These modifications to control surface design can alter flow to increase lift, reduce drag and enhance thrust in the case of propulsive fin-based systems in fishes and marine mammals, and are particularly interesting subjects for future research and application to engineered systems. Here, we review how modifications to control surfaces can alter flow and increase hydrodynamic performance

    Biomarkers for Radiation Pneumonitis Using Noninvasive Molecular Imaging

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    Our goal is to develop minimally invasive biomarkers for predicting radiation-induced lung injury before symptoms develop. Currently, there are no biomarkers that can predict radiation pneumonitis. Radiation damage to the whole lung is a serious risk in nuclear accidents or in radiologic terrorism. Our previous studies have shown that a single dose of 15 Gy of x-rays to the thorax causes severe pneumonitis in rats by 6–8 wk. We have also developed a mitigator for radiation pneumonitis and fibrosis that can be started as late as 5 wk after radiation. Methods: We used 2 functional SPECT probes in vivo in irradiated rat lungs. Regional pulmonary perfusion was measured by injection of 99mTc-macroaggregated albumin. Perfused volume was determined by comparing the volume of distribution of 99mTc-macroaggregated albumin to the anatomic lung volume obtained by small-animal CT. A second probe, 99mTc-labeled Duramycin, which binds to apoptotic cells, was used to measure pulmonary cell death in the same rat model. Results: The perfused volume of lung was decreased by about 25% at 1, 2, and 3 wk after receipt of 15 Gy, and 99mTc-Duramycin uptake was more than doubled at 2 and 3 wk. There was no change in body weight, breathing rate, or lung histology between irradiated and nonirradiated rats at these times. Pulmonary vascular resistance and vascular permeability measured in isolated perfused lungs ex vivo increased at 2 wk after 15 Gy of irradiation. Conclusion: Our results suggest that SPECT biomarkers have the potential to predict radiation injury to the lungs before substantial functional or histologic damage is observed. Early prediction of radiation pneumonitis in time to initiate mitigation will benefit those exposed to radiation in the context of therapy, accidents, or terrorism

    The Distribution of Alcohol in the Tissues of the Rat

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    In order to determine the distribution of alcohol in the tissues, we have devised a method which is quite simple and accurate. The animal is killed and the tissues removed as rapidly as possible. The tissues are placed in weighed 150 ml. extraction flasks immersed in solid carbon dioxide. The flasks and tissues are weighed and the tissues covered with a solution of picric and tartaric acids. The samples are then placed in a refrigerator until the analysis can be made
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