12,826 research outputs found

    3D Spectrophotometry of Planetary Nebulae in the Bulge of M31

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    We introduce crowded field integral field (3D) spectrophotometry as a useful technique for the study of resolved stellar populations in nearby galaxies. As a methodological test, we present a pilot study with selected extragalactic planetary nebulae (XPN) in the bulge of M31, demonstrating how 3D spectroscopy is able to improve the limited accuracy of background subtraction which one would normally obtain with classical slit spectroscopy. It is shown that due to the absence of slit effects, 3D is a most suitable technique for spectrophometry. We present spectra and line intensities for 5 XPN in M31, obtained with the MPFS instrument at the Russian 6m BTA, INTEGRAL at the WHT, and with PMAS at the Calar Alto 3.5m Telescope. Using 3D spectra of bright standard stars, we demonstrate that the PSF is sampled with high accuracy, providing a centroiding precision at the milli-arcsec level. Crowded field 3D spectrophotometry and the use of PSF fitting techniques is suggested as the method of choice for a number of similar observational problems, including luminous stars in nearby galaxies, supernovae, QSO host galaxies, gravitationally lensed QSOs, and others.Comment: (1) Astrophysikalisches Institut Potsdam, (2) University of Durham. 18 pages, 11 figures, accepted for publication in Ap

    Cholecystogastric fistula: a brief report and review of the literature.

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    Cholecystogastric fistula is a rare, life-threatening complication of cholelithiasis that presents a difficult challenge to the surgeon when it occurs in elderly and co-morbid patients. Following a case of a 68-year-old female who presented with a short history of epigastric pain and vomiting, and in whom a cholecystogastric fistula was identified on abdominal computed tomography and confirmed on upper gastrointestinal endoscopy, we performed a systematic review of the literature on the management of cholecystogastric fistula. Our patient underwent laparotomy without excision of the fistula nor cholecystectomy and had an uncomplicated post-operative course. Surgical management using an open approach remains the mainstay of treatment of cholecystogastric fistula although laparoscopic techniques are used with increasing success. Surgical closure of the fistula is not always necessary. Improved surgical techniques including the use of laparoscopic surgery have led to improved outcomes in the management of cholecystogastric fistula

    A Preliminary Study of the Preparation of Slurry Fuels from Vaporized Magnesium

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    Slurry fuels containing extremely small particles of magnesium were prepared by concentrating the dilute slurry product resulting from the shock-cooling of magnesium metal vapors with a liquid hydrocarbon spray. A complete description of the equipment and procedure used in preparing the fuel is given. Ninety-five percent by weight of the solid particles formed by this process passed through a 100-mesh screen. The particle-size distribution of the screened fraction of one run, as determined by sedimentation analysis, indicated that 73 percent by weight of the metal particles were finer than 2 microns in equivalent spherical diameter. The purity of the solid particles ranged as high as 98.9 percent by weight of free magnesium. The screened product was concentrated by means of a bowl-type centrifuge from 0.5 to more than 50 percent by weight solids content to form an extremely viscous, clay-like mass. By addition of a surface active agent, this viscous material was converted into a pumpable slurry fuel

    SNAPPI-DB: a database and API of Structures, iNterfaces and Alignments for Proteinā€“Protein Interactions

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    SNAPPI-DB, a high performance database of Structures, iNterfaces and Alignments of Proteinā€“Protein Interactions, and its associated Java Application Programming Interface (API) is described. SNAPPI-DB contains structural data, down to the level of atom co-ordinates, for each structure in the Protein Data Bank (PDB) together with associated data including SCOP, CATH, Pfam, SWISSPROT, InterPro, GO terms, Protein Quaternary Structures (PQS) and secondary structure information. Domainā€“domain interactions are stored for multiple domain definitions and are classified by their Superfamily/Family pair and interaction interface. Each set of classified domainā€“domain interactions has an associated multiple structure alignment for each partner. The API facilitates data access via PDB entries, domains and domainā€“domain interactions. Rapid development, fast database access and the ability to perform advanced queries without the requirement for complex SQL statements are provided via an object oriented database and the Java Data Objects (JDO) API. SNAPPI-DB contains many features which are not available in other databases of structural proteinā€“protein interactions. It has been applied in three studies on the properties of proteinā€“protein interactions and is currently being employed to train a proteinā€“protein interaction predictor and a functional residue predictor. The database, API and manual are available for download at:

    Composing Efficient, Robust Tests for Policy Selection

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    Modern reinforcement learning systems produce many high-quality policies throughout the learning process. However, to choose which policy to actually deploy in the real world, they must be tested under an intractable number of environmental conditions. We introduce RPOSST, an algorithm to select a small set of test cases from a larger pool based on a relatively small number of sample evaluations. RPOSST treats the test case selection problem as a two-player game and optimizes a solution with provable kk-of-NN robustness, bounding the error relative to a test that used all the test cases in the pool. Empirical results demonstrate that RPOSST finds a small set of test cases that identify high quality policies in a toy one-shot game, poker datasets, and a high-fidelity racing simulator.Comment: 26 pages, 13 figures. To appear in Proceedings of the Thirty-Ninth Conference on Uncertainty in Artificial Intelligence (UAI 2023

    Purine nucleoside phosphorylase: A new marker for free oxygen radical injury to the endothelial cell

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    The effect of ischemia and reperfusion on purine nucleoside phosphorylase was studied in an isolated perfused rat liver model. This enzyme is localized primarily in the cytoplasm of the endothelial and Kupffer cells; some activity is associated with the parenchymal cells. Levels of this enzyme accurately predicted the extent of ischemia and reperfusion damage to the microvascular endothelial cell of the liver. Livers from Lewis rats were subjected to 30, 45 and 60 min of warm (37Ā° C) no flow ischemia that was followed by a standard reperfusion period lasting 45 min. Purine nucleoside phosphorylase was measured at the end of the no flow ischemia and reperfusion periods as was superoxide generation (O2ā€). Bile production was monitored throughout the no flow ischemia and reperfusion periods. Control perfusions were carried out for 120 min. A significant rise in purine nucleoside phosphorylase levels as compared with controls was observed at the end of ischemia in all the three groups. The highest level, 203.5 Ā± 29.2 mU/ml, was observed after 60 min of ischemia. After the reperfusion period, levels of purine nucleoside phosphorylase decreased in the 30ā€ and 45ā€min groups 58.17 Ā± 9.66 mU/ml and 67.5 Ā± 17.1 mU/ml, respectively. These levels were equal to control perfusions. In contrast, after 60 min of ischemia, levels of purine nucleoside phosphorylase decreased early in the reperfusion period and then rose to 127.8 Ā± 14.8 mU/ml by the end of reperfusion (p < 0.0001). Superoxide generation at the beginning of reperfusion was higher than in controls with similar values observed at the end of 30, 45 and 60 min of ischemia. During reperfusion, production of superoxide continued. Bile production was significantly lower at the end of 30 min (0.044 Ā± 0.026 Ī¼l/min/gm), 45 min (0.029 Ā± 0.0022 Ī¼/min/gm) and 60 min of ischemia (0.022 Ā± 0.008 Ī¼/min/gm) when compared with bile production by control livers during the corresponding time (0.680 Ā± 0.195, 0.562 Ā± 0.133 and 0.480 Ā± 0.100 Ī¼/min/gm respectively; p < 0.001). During reperfusion, rates of bile production were normal after 30 and 45 min of ischemia. In contrast, significantly lower rates of bile production, 0.046 Ā± 0.36 Ī¼/min/gm (p < 0.001) occurred during reperfusion after 60 min of ischemia. Control livers during the same period produced 0.330 Ā± 0.056 Ī¼l/min/gm of bile. The results indicate that purine nucleoside phosphorylase levels may be a good index of oxidative injury to the liver in ischemia reperfusion and reliably predict the functional state of the organ after reperfusion. Copyright Ā© 1990 American Association for the Study of Liver Disease

    Fourteen Draft Genome Sequences for the First Reported Cases of Azithromycin-Resistant Neisseria gonorrhoeae in Ireland

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    Here, we report the draft genome assemblies of 14 azithromycin-resistantNeisseria gonorrhoeaeclinical isolates, representing the first such strains identified in Ireland. Among these isolates are the first reported highly resistant strains (MIC >256mg/liter), which both belonged to the ST1580 sequence type
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