8,634 research outputs found
Developing and Teaching IS97.2: Personal Productivity with Information Technology
It is common for university students either to have introductory skills in the basic desktop software packages or to obtain these skills by self-study modules or short courses. What students lack is an understanding of how to use desktop packages effectively to improve their productivity. This is the missing link in the curriculum. This tutorial describes one solution: the IS\u2797.2 course on Personal Productivity with Information Technology. An appendix presents a sample lesson used with this course
The Dual Formulation of Cosmic Strings and Vortices
We study four dimensional systems of global, axionic and local strings. By
using the path integral formalism, we derive the dual formulation of these
systems, where Goldstone bosons, axions and missive vector bosons are described
by antisymmetric tensor fields, and strings appear as a source for these tensor
fields. We show also how magnetic monopoles attached to local strings are
described in the dual formulation. We conclude with some remarks.Comment: 18 pages, CU-TP-588 and CERN-TH.6780/9
A relativistic study of Bessel beams
We present a fully relativistic analysis of Bessel beams revealing some
noteworthy features that are not explicit in the standard description. It is
shown that there is a reference frame in which the field takes a particularly
simple form, the wave appearing to rotate in circles. The concepts of
polarization and angular momentum for Bessel beams is also reanalyzed.Comment: 11 pages, 2 fig
Winter Wheat Response to Nitrogen, Phosphorus, Potassium and Limestone on a Burleson Clay Loam
Last updated: 6/9/200
Scanning and Transmission Electron Microscopic Study of Recovered Porcine Aortic Valved Conduits
Four explanted porcine aortic valved conduits were examined using scanning and transmission electron microscopy. Sources of obstruction such as neointima or peel and calcification were observed. In one sample the neointima was found to possess an unusually large expanse of squamous cells partially lining the luminal surface. This lining much resembled a normal endothelium, which is not an expected feature of neointima. Cells, presumably of host origin, were noted upon the leaflet surfaces. They did not seem as well organized as those found on the neointima. Calcification did not seem greatly advanced but was clearly apparent. Certain treatments proposed by others to curtail calcification are discussed and amended herein.
SEM examination of three of these conduits provided good evidence of lining cells on only the inflow surface of the leaflet. The fourth conduit, however, showed cells on both inflow and outflow surfaces. These cells possessed certain characteristics of cells from leaflets of the other three conduits, but questions remain as to the precise identification of all of these lining cells. TEM examination provided cytological evidence of macrophage-like cells lining the inflow surface of a leaflet
Spectral Line Imaging Observations of 1E0102.2-7219
E0102-72 is the second brightest X-ray source in the Small Magellanic Cloud
and the brightest supernova remnant in the SMC. We observed this SNR for ~140
ksec with the High Energy Transmission Gratings (HETG) aboard the Chandra X-ray
Observatory. The small angular size and high surface brightness make this an
excellent target for HETG and we resolve the remnant into individual lines. We
observe fluxes from several lines which include O VIII Ly, Ly,
and O VII along with several lines from Ne X, Ne IX and Mg XII. These line
ratios provide powerful constraints on the electron temperature and the
ionization age of the remnant.Comment: To appear in "Young Supernova Remnants" (11th Annual Astrophysics
Conference in Maryland), S. S. Holt & U. Hwang (eds), AIP, New York (2001
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