11,945 research outputs found

    Twilight Intensity Variation of the Infrared Hydroxyl Airglow

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    The vibration rotation bands of the hydroxyl radical are the strongest features in the night airglow and are exceeded in intensity in the dayglow only by the infrared atmospheric bands of oxygen. The variation of intensity during evening twilight is discussed. Using a ground-based Fourier Transform Spectrometer (FTS), hydroxyl intensity measurements as early as 3 deg solar depression were made. Models of the twilight behavior show that this should be sufficient to provide measurement of the main portion of the twilight intensity change. The instrument was equipped with a liquid nitrogen-cooled germanium detector whose high sensitivity combined with the efficiency of the FTS technique permits spectra of the region 1.1 to 1.6 microns at high signal-to-noise to be obtained in two minutes. The use of a polarizer at the entrance aperture of the instrument reduces the intensity of scattered sunlight by a factor of at least ten for zenith observations

    Solar cell radiation response near the interface of different atomic number materials

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    The response of cobalt 60 irradiated N/P silicon solar cells was measured as a function of the atomic number of the medium adjacent to the cell and the direction of the gamma ray beam. The interpositioning of various thicknesses of aluminum between the adjacent material and the cell had the effect of moving the cell to various locations in an approximate monatomic numbered medium. Using this technique the solar cell response was determined at various distances from the interface for gold and beryllium. The results were compared with predictions based upon ionization chamber measurements of dose perturbations in aluminum and found to agree within five percent. Ionization chamber data was then used to estimate the influence of various base contact materials

    New Analysis Indicates No Thermal Inversion in the Atmosphere of HD 209458b

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    An important focus of exoplanet research is the determination of the atmospheric temperature structure of strongly irradiated gas giant planets, or hot Jupiters. HD 209458b is the prototypical exoplanet for atmospheric thermal inversions, but this assertion does not take into account recently obtained data or newer data reduction techniques. We re-examine this claim by investigating all publicly available Spitzer Space Telescope secondary-eclipse photometric data of HD 209458b and performing a self-consistent analysis. We employ data reduction techniques that minimize stellar centroid variations, apply sophisticated models to known Spitzer systematics, and account for time-correlated noise in the data. We derive new secondary-eclipse depths of 0.119 +/- 0.007%, 0.123 +/- 0.006%, 0.134 +/- 0.035%, and 0.215 +/- 0.008% in the 3.6, 4.5, 5.8, and 8.0 micron bandpasses, respectively. We feed these results into a Bayesian atmospheric retrieval analysis and determine that it is unnecessary to invoke a thermal inversion to explain our secondary-eclipse depths. The data are well-fitted by a temperature model that decreases monotonically between pressure levels of 1 and 0.01 bars. We conclude that there is no evidence for a thermal inversion in the atmosphere of HD 209458b.Comment: 8 pages, 5 figures; accepted for publication in Ap

    Instrumentation for hydrogen slush storage containers

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    Hydrogen liquid and slush tank continuous inventory during ground storag

    Deduction with XOR Constraints in Security API Modelling

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    We introduce XOR constraints, and show how they enable a theorem prover to reason effectively about security critical subsystems which employ bitwise XOR. Our primary case study is the API of the IBM 4758 hardware security module. We also show how our technique can be applied to standard security protocols

    Mopra CO Observations of the Bubble HII Region RCW120

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    We use the Mopra radio telescope to test for expansion of the molecular gas associated with the bubble HII region RCW120. A ring, or bubble, morphology is common for Galactic HII regions, but the three-dimensional geometry of such objects is still unclear. Detected near- and far-side expansion of the associated molecular material would be consistent with a three-dimensional spherical object. We map the J=10J = 1\rightarrow 0 transitions of 12^{12}CO, 13^{13}CO, C18^{18}O, and C17^{17}O, and detect emission from all isotopologues. We do not detect the 0011E0_0\rightarrow 1_{-1} E masing lines of CH3_3OH at 108.8939 GHz. The strongest CO emission is from the photodissociation region (PDR), and there is a deficit of emission toward the bubble interior. We find no evidence for expansion of the molecular material associated with RCW120 and therefore can make no claims about its geometry. The lack of detected expansion is roughly in agreement with models for the time-evolution of an HII region like RCW120, and is consistent with an expansion speed of <1.5kms1< 1.5\, {\rm km\, s^{-1}}. Single-position CO spectra show signatures of expansion, which underscores the importance of mapped spectra for such work. Dust temperature enhancements outside the PDR of RCW120 coincide with a deficit of emission in CO, confirming that these temperature enhancements are due to holes in the RCW120 PDR. Hα\alpha emission shows that RCW120 is leaking 5%\sim5\% of the ionizing photons into the interstellar medium (ISM) through PDR holes at the locations of the temperature enhancements. H-alpha emission also shows a diffuse "halo" from leaked photons not associated with discrete holes in the PDR. Overall 25±10%25\pm10\% of all ionizing photons are leaking into the nearby ISM.Comment: 35 pages, 14 figures. Accepted to Ap

    Diabetes educators: Perceived experiences, supports and barriers to use of common diabetes-related technologies

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    © 2016 Diabetes Technology Society. Background: Various technologies are commonly used to support type 1 diabetes management (continuous subcutaneous insulin infusion therapy, continuous glucose monitoring systems, smartphone and tablet applications, and video conferencing) and may foster self-care, communication, and engagement with health care services. Diabetes educators are key professional supporters of this patient group, and ideally positioned to promote and support technology use. The aim of this study was to examine diabetes educators' perceived experiences, supports, and barriers to use of common diabetes-related technologies for people with type 1 diabetes. Methods: This qualitative ethnographic study recruited across metropolitan, regional and rural areas of Australia using purposive sampling of Australian Diabetes Educators Association members. Data were collected by semistructured telephone interviews and analyzed using thematic analysis. Results: Participants (n = 31) overwhelmingly indicated that overall the use of technology in the care of patients with type 1 diabetes was burdensome for them. They identified 3 themes involving common diabetes-related technologies: access to technology, available support, and technological advances. Overall, these themes demonstrated that while care was usually well intentioned it was more often fragmented and inconsistent. Most often care was provided by a small number of diabetes educators who had technology expertise. Conclusions: To realize the potential benefits of these relatively new but common diabetes technologies, many diabetes educators need to attain and retain the skills required to deliver this essential component of care. Furthermore, policy and strategy review is required, with reconfiguration of services to better support care delivery

    Magnetic Fields and Passive Scalars in Polyakov's Conformal Turbulence

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    Polyakov has suggested that two dimensional turbulence might be described by a minimal model of conformal field theory. However, there are many minimal models satisfying the same physical inputs as Polyakov's solution (p,q)=(2,21). Dynamical magnetic fields and passive scalars pose different physical requirements. For large magnetic Reynolds number other minimal models arise. The simplest one, (p,q)=(2,13) makes reasonable predictions that may be tested in the astrophysical context. In particular, the equipartition theorem between magnetic and kinetic energies does not hold: the magnetic one dominates at larger distances.Comment: 12 pages, UR-1296, ER-745-4068
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