291 research outputs found

    The Cosmic MeV Neutrino Background as a Laboratory for Black Hole Formation

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    Calculations of the cosmic rate of core collapses, and the associated neutrino flux, commonly assume that a fixed fraction of massive stars collapse to black holes. We argue that recent results suggest that this fraction instead increases with redshift. With relatively more stars vanishing as "unnovae" in the distant universe, the detectability of the cosmic MeV neutrino background is improved due to their hotter neutrino spectrum, and expectations for supernova surveys are reduced. We conclude that neutrino detectors, after the flux from normal SNe is isolated via either improved modeling or the next Galactic SN, can probe the conditions and history of black hole formation.Comment: 5 pages, 4 figures; Matches version published in Physics Letters

    Networking Behavior in Thin Film and Nanostructure Growth Dynamics

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    Thin film coatings have been essential in development of several micro and nano-scale devices. To realize thin film coatings various deposition techniques are employed, each yielding surface morphologies with different characteristics of interest. Therefore, understanding and control of the surface growth is of great interest. In this paper, we devise a novel network-based modeling of the growth dynamics of such thin films and nano-structures. We specifically map dynamic steps taking place during the growth to components (e.g., nodes, links) of a corresponding network. We present initial results showing that this network-based modeling approach to the growth dynamics can simplify our understanding of the fundamental physical dynamics such as shadowing and re-emission effects

    Protective effect of leukotriene receptor antagonist montelukast on smoking-induced lung injury in Wistar rats.

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    Increased activation of alveolar macrophage, neutrophil and mast cell has been proven in cigarette smoking (CS)-related lung disorders (CSLD). An increased production of cysteinyl-leukotrienes (LTs), which are mediators secreted from the mentioned cells, in response to CS has been shown in humans. The protective effect of LT1 receptor-1 antagonist (LTR-1AT) on CSLD is, however, not known. In this study we aimed to determine whether there is any protective effect of a LTR-1AT, montelukast (MK), on CSLD in Wistar rats. Nine controls and twenty-three smoke-exposed rats were enrolled into this study. Controls were exposed to non-filtered air, and the smoke-exposed rats were exposed to CS for 6 h/day, 6 days/week for three weeks. The CS-exposed rats were also treated with 0.1 mg/kg/day of MK or saline. Morphometric criteria for lung injury were determined as the mean linear intercept of alveolar septa (Lm), the volume density of alveolar septa (Vvspt) and the density of the alveolar surface area per unit volume of lung parenchyma (Sva.pa). Lung mast cells (LMC), which are a major source of LTs, were also counted. Results showed that Lm of the control group was significantly lower and Vvspt, Sva.pa of the controls were significantly higher compared to those of the CS-exposed groups. Animals treated with MK had significant protection against CSLD. Lm was significantly higher and Vvspt, Sva.pa were lower in the saline group than in the MK-treated group. The number of LMC in the CS-exposed groups was also significantly higher than that in the control group. Based on these results, one can suggest that some part of the pathogenesis of CSLD may be related to an enhanced LTs synthesis and LTR-1AT. Therefore, montelukast may protect against active or passive smoking-induced lung injury and related disorders.</p
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