20,388 research outputs found

    Computer program for calculating water and steam properties

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    Computer subprogram, WASP, accepts any two of pressure, temperature, and density as input conditions. Pressure and either entropy or enthalpy are also allowable input variables. This flexibility is especially useful in cycle analysis. Metastable calculations can also be made using WASP

    Gamma ray angular correlations following inelastic scattering of 42-MeV alpha particles from magnesium 24

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    Angular correlation between inelastically scattered alpha particles and gamma rays emitted in subsequent nuclear decay of magnesium 2

    Glutathione treatment protects the rat liver against injury after warm ischemia and Kupffer cell activation

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    Background/Aim: The generation of reactive oxygen species by activated Kupffer cells (KC) may contribute to reperfusion injury of the liver during liver transplantation or resection. The aim of our present studies was to investigate (1) prevention of hepatic reperfusion injury after warm ischemia by administration of the antioxidant glutathione (GSH) and (2) whether GSH confers protection through influences on KC toxicity. Methods: Isolated perfused rat livers were subjected to 1 h of warm ischemia followed by 90 min of reperfusion without (n = 5) or with GSH or catalase (n = 4-5 each). Selective KC activation by zymosan (150 mug/ml) in continuously perfused rat livers was used to investigate KC-related liver injury. Results: Postischemic infusion of 0.1, 0.5, 1.0 and 2.0 mM GSH, but not 0.05 mM GSH prevented reperfusion injury after warm ischemia as indicated by a marked reduction of sinusoidal LDH efflux by up to 83 +/- 13% (mean +/- SD; p < 0.05) and a concomitant significant improvement of postischemic bile flow by 58 +/- 27% (p < 0.05). A similar protection was conveyed by KC blockade with gadolinium chloride indicating prevention of KC-related reperfusion injury by postischemic GSH treatment. Postischemic treatment with catalase (150 U/ml) resulted in a reduction of LDH efflux by 40 +/- 9% (p < 0.05). Accordingly, catalase as well as GSH (0.1-2.0 mM) nearly completely prevented the increase in LDH efflux following selective :KC activation by zymosan in continously perfused rat livers. Conclusion: Postischemic administration of GSH protects the liver against reperfusion injury after warm ischemia. Detoxification of KC-derived hydrogen peroxide seem to be an important feature of the protective mechanisms. Copyright (C) 2002 S. Karger AG, Basel

    Spectral Consequences of Deviation from Spherical Composition Symmetry in Type Ia Supernovae

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    We investigate the prospects for constraining the maximum scale of clumping in composition that is consistent with observed Type Ia supernova flux spectra. Synthetic spectra generated without purely spherical composition symmetry indicate that gross asymmetries make prominent changes to absorption features. Motivated by this, we consider the case of a single unblended line forming in an atmosphere with perturbations of different scales and spatial distributions. Perturbations of about 1% of the area of the photodisk simply weaken the absorption feature by the same amount independent of the line of sight. Conversely, perturbations of about 10% of the area of the photodisk introduce variation in the absorption depth which does depend on the line of sight. Thus, 1% photodisk area perturbations may be consistent with observed profile homogeneity but 10% photodisk area perturbations can not. Based on this, we suggest that the absence of significant variation in the depths of Si II 6355 absorption features in normal Type Ia spectra near maximum light indicates that any composition perturbations in these events are quite small. This also constrains future three-dimensional explosion models to produce ejecta profiles with only small scale inhomogeneities.Comment: 11 pages, 6 figure

    Supernova Resonance--scattering Line Profiles in the Absence of a Photosphere

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    In supernova spectroscopy relatively little attention has been given to the properties of optically thick spectral lines in epochs following the photosphere's recession. Most treatments and analyses of post-photospheric optical spectra of supernovae assume that forbidden-line emission comprises most if not all spectral features. However, evidence exists which suggests that some spectra exhibit line profiles formed via optically thick resonance-scattering even months or years after the supernova explosion. To explore this possibility we present a geometrical approach to supernova spectrum formation based on the "Elementary Supernova" model, wherein we investigate the characteristics of resonance-scattering in optically thick lines while replacing the photosphere with a transparent central core emitting non-blackbody continuum radiation, akin to the optical continuum provided by decaying 56Co formed during the explosion. We develop the mathematical framework necessary for solving the radiative transfer equation under these conditions, and calculate spectra for both isolated and blended lines. Our comparisons with analogous results from the Elementary Supernova code SYNOW reveal several marked differences in line formation. Most notably, resonance lines in these conditions form P Cygni-like profiles, but the emission peaks and absorption troughs shift redward and blueward, respectively, from the line's rest wavelength by a significant amount, despite the spherically symmetric distribution of the line optical depth in the ejecta. These properties and others that we find in this work could lead to misidentification of lines or misattribution of properties of line-forming material at post-photospheric times in supernova optical spectra.Comment: 37 pages, 24 figures; accepted for publication in ApJ Supplement Serie

    MP731: New England Killing Frost Records by Zone

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    This publication provides a deeper look at the killing frost data that is analyzed and summarized in Maine Agricultural and Forest Experiment Station Bulletin 846. The presentation in Bulletin 846 is designed to help planners and analysts. Individual readers, historians, botanists, agronomists, ecologists, and others may find a deeper look at the materials useful. Miscellaneous Publication 731 provides those data by climate zone on a yearly basis.https://digitalcommons.library.umaine.edu/aes_miscpubs/1026/thumbnail.jp

    B846: Growing Season Parameter Reconstructions for New England Using Killing Frost Records, 1697-1947

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    In New England, killing frosts in the late spring and early fall mark the limits of the region\u27s growing seasons. Over the years, farmers have tried to anticipate when to plant and when to harvest to safely prevent their crops from experiencing the harmful effects of freezing. As a hedge against failing memory, some farmers kept notes on when killing frosts occurred so that they could more readily calculate in the years to come when to sow and when to reap. Some of these notes have survived and are now preserved in archives and libraries across the region, or remain the proud possessions of later generations of the same families. The growing season records reconstructed for this bulletin are based on data taken from these diaries, farm journals, notebooks, and scraps of paper and represent the observations of several generations of New England farmers.https://digitalcommons.library.umaine.edu/aes_bulletin/1039/thumbnail.jp

    {\eta} and {\eta}' mesons from Nf=2+1+1 twisted mass lattice QCD

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    We determine mass and mixing angles of eta and eta' states using Nf=2+1+1 Wilson twisted mass lattice QCD. We describe how those flavour singlet states need to be treated in this lattice formulation. Results are presented for three values of the lattice spacing, a=0.061 fm, a=0.078 fm and a=0.086 fm, with light quark masses corresponding to values of the charged pion mass in a range of 230 to 500 MeV and fixed bare strange and charm quark mass values. We obtain 557(15)(45) MeV for the eta mass (first error statistical, second systematic) and 44(5) degrees for the mixing angle in the quark flavour basis, corresponding to -10(5) degrees in the octet-singlet basis.Comment: 28 pages, 9 figures, version to appear in JHEP, extended discussion of autocorrelation times and comparison to results available in the literature, added a comment for FS-effects and clarified the description of our blocking procedur

    High frequency dynamics in a monatomic glass

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    The high frequency dynamics of glassy Selenium has been studied by Inelastic X-ray Scattering at beamline BL35XU (SPring-8). The high quality of the data allows one to pinpoint the existence of a dispersing acoustic mode for wavevectors (QQ) of 1.5<Q<12.51.5<Q<12.5 nm1^{-1}, helping to clarify a previous contradiction between experimental and numerical results. The sound velocity shows a positive dispersion, exceeding the hydrodynamic value by \approx 10% at Q<3.5Q<3.5 nm1^{-1}. The Q2Q^2 dependence of the sound attenuation Γ(Q)\Gamma(Q), reported for other glasses, is found to be the low-QQ limit of a more general Γ(Q)Ω(Q)2\Gamma(Q) \propto \Omega(Q)^2 law which applies also to the higher QQ region, where Ω(Q)Q\Omega(Q)\propto Q no longer holds.Comment: Phys. Rev. Lett. (Accepted

    Near-infrared line identification in type Ia supernovae during the transitional phase

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    We present near-infrared synthetic spectra of a delayed-detonation hydrodynamical model and compare them to observed spectra of four normal type Ia supernovae ranging from day +56.5 to day +85. This is the epoch during which supernovae are believed to be undergoing the transition from the photospheric phase, where spectra are characterized by line scattering above an optically thick photosphere, to the nebular phase, where spectra consist of optically thin emission from forbidden lines. We find that most spectral features in the near-infrared can be accounted for by permitted lines of Fe II and Co II. In addition, we find that [Ni II] fits the emission feature near 1.98 {\mu}m, suggesting that a substantial mass of 58Ni exists near the center of the ejecta in these objects, arising from nuclear burning at high density. A tentative identification of Mn II at 1.15 {\mu}m may support this conclusion as well.Comment: accepted to Ap
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