Analysis of data on retention of high school band students

Includes bibliographical references

TeV radiation from the Crab nebula and other matters

The detection of the Crab Nebula via the Cherenkov imaging technique places TeV astronomy on a secure observational footing. The motivation for TeV observations, a discussion of the atmospheric Cherenkov technique, the experimental details of the Crab Nebula detection, and its scientific implications are presented. The present dilemma of VHE/UHE astronomy is that the Crab appears to be the only source whose showers match theoretical expectations. The situation will be clarified as improved ground-based detectors come on-line with sensitivities matching those of the GRO (Gamma Ray Observatory) instruments

Computing Vertex Centrality Measures in Massive Real Networks with a Neural Learning Model

Vertex centrality measures are a multi-purpose analysis tool, commonly used in many application environments to retrieve information and unveil knowledge from the graphs and network structural properties. However, the algorithms of such metrics are expensive in terms of computational resources when running real-time applications or massive real world networks. Thus, approximation techniques have been developed and used to compute the measures in such scenarios. In this paper, we demonstrate and analyze the use of neural network learning algorithms to tackle such task and compare their performance in terms of solution quality and computation time with other techniques from the literature. Our work offers several contributions. We highlight both the pros and cons of approximating centralities though neural learning. By empirical means and statistics, we then show that the regression model generated with a feedforward neural networks trained by the Levenberg-Marquardt algorithm is not only the best option considering computational resources, but also achieves the best solution quality for relevant applications and large-scale networks. Keywords: Vertex Centrality Measures, Neural Networks, Complex Network Models, Machine Learning, Regression ModelComment: 8 pages, 5 tables, 2 figures, version accepted at IJCNN 2018. arXiv admin note: text overlap with arXiv:1810.1176

GeV Gamma-Ray Sources

We report on the preliminary extension of our work on cataloging the GeV sky to approximately 7 years of CGRO/EGRET observations with special emphasis on a search for transient sources. The search method and significance levels are presented. Our initial results on 13 possible transients indicate that 3 may be new gamma-ray sources. Sixteen new steady GeV sources are also detected, 3 of which have never been reported as gamma-ray sources

Imaging diagnosis-computed tomography of traction bronchiectasis secondary to pulmonary fibrosis in a Patterdale Terrier

An 8-year-old, Patterdale terrier was referred for evaluation of tachypnoea, exercise intolerance, and weight loss. Computed tomographic images showed pneumomediastinum, diffuse pulmonary ground glass opacity, and marked dilatation of peripheral bronchi, but no evidence of thickened bronchial walls. The histopathologic diagnosis was diffuse pulmonary interstitial fibrosis, type II pneumocyte hyperplasia, and bronchiectasis. The lack of evidence of primary bronchitis supported a diagnosis of traction bronchiectasis. Traction bronchiectasis can occur as a sequela to pulmonary fibrosis in dogs. (C) 2016 American College of Veterinary Radiology

A Unified Jet Model of X-Ray Flashes, X-Ray-Rich Gamma-Ray Bursts, and Gamma-Ray Bursts: I. Power-Law-Shaped Universal and Top-Hat-Shaped Variable Opening-Angle Jet Models

HETE-2 has provided strong evidence that the properties of X-Ray Flashes (XRFs), X-ray-rich GRBs, and GRBs form a continuum, and therefore that these three kinds of bursts are the same phenomenon. A key feature found by HETE-2 is that the density of bursts is roughly constant per logarithmic interval in burst fluence S_E and observed spectral peak energy Ep_obs, and in isotropic-equivalent energy Eiso and rest frame spectral peak energy Epeak. In this paper, we explore a unified jet model of all three kinds of bursts, using population synthesis simulations of the bursts and detailed modeling of the instruments that detect them. We show that both a variable jet opening-angle model in which the emissivity is a constant independent of the angle relative to the jet axis and a universal jet model in which the emissivity is a power-law function of the angle relative to the jet axis can explain the observed properties of GRBs reasonably well. However, if one tries to account for the properties of all three kinds of bursts in a unified picture, the extra degree of freedom available in the variable jet opening-angle model enables it to explain the observations reasonably well while the power-law universal jet model cannot. The variable jet opening-angle model of XRFs, X-ray-rich GRBs, and GRBs implies that the energy Egamma radiated in gamma rays is ~ 100 times less than has been thought, and that most GRBs have very small jet opening angles (~ half a degree). It also implies that there are ~ 10^4 - 10^5 more bursts with very small jet opening angles for every burst that is observable. If this is the case, the rate of GRBs could be comparable to the rate of Type Ic core collapse supernovae.Comment: 51 pages, 19 figures, accepted by ApJ; revised; condensed abstrac

Search for an X-ray identification of a strong gamma-ray source

X-rays from Cygnus X-3 were observed during early 1978 with the detectors of the SAS-3 satellite. These observations in conjunction with earlier UHURU and ANS data indicate that the 4.8 hr period of Cygnus X-3 is increasing at the rate of P/P = (5/1 plus or minus 1.3) x 10 to the minus 6 power/1 yr. The sign and magnitude for this change are incompatible with a rotation model for the period and are in reasonable agreement with model predictions for orbital changes associated with mass loss and transfer in a binary system