Secondary prevention following coronary artery bypass surgery: a pilot study for improved patient education

This is an Open Access article distributed under the terms of the Open Access Policy

Mirror Images of String Cosmologies

A discrete symmetry of the four-dimensional string effective action is employed to derive spatially homogeneous and inhomogeneous string cosmologies from vacuum solutions of general relativity that admit two commuting spacelike Killing vectors. In particular, a tilted Bianchi type V cosmology is generated from a vacuum type VI_h solution and a plane wave solution with a bounded and oscillating dilaton field is found from a type ${\rm VII}_h$ model. Further applications are briefly discussed.Comment: 10 pages plain late

The Ursinus Weekly, February 12, 1976

Students and Board meet • U.S.G.A. to be elected: Pres. qualifications amended • English Dept. upholds quality • ETS changes • Attorney named bequest chairman • Two Ursinus grads look back from Penn • Editorial: Schedule change - aid to program? • Civil Service testing set • Letter to the editor: A different opinion • Rich Swartz discusses his U.C. career • Movie review: One flew over the cuckoo\u27s nest • Shakespeare trip offered in June • Reflections on France • Forum review: Duo pianists • Lorelei news • Good: Badminton! • Our Bears do wrestle! • We have a winner! • NBA stars • How Vermeil got the Eagles job! • Bernie! • Intramurals! • Bears basketball • Notes from sports editor\u27s deskhttps://digitalcommons.ursinus.edu/weekly/1050/thumbnail.jp

WISE/NEOWISE Preliminary Analysis and Highlights of the 67P/Churyumov-Gerasimenko Near Nucleus Environs

On January 18-19 and June 28-29 of 2010, the Wide-field Infrared Survey Explorer (WISE) spacecraft imaged the Rosetta mission target, comet 67P/Churyumov-Gerasimenko. We present a preliminary analysis of the images, which provide a characterization of the dust environment at heliocentric distances similar to those planned for the initial spacecraft encounter, but on the outbound leg of its orbit rather than the inbound. Broad-band photometry yields low levels of CO2 production at a comet heliocentric distance of 3.32 AU and no detectable production at 4.18 AU. We find that at these heliocentric distances, large dust grains with mean grain diameters on the order of a millimeter or greater dominate the coma and evolve to populate the tail. This is further supported by broad-band photometry centered on the nucleus, which yield an estimated differential dust particle size distribution with a power law relation that is considerably shallower than average. We set a 3-sigma upper limit constraint on the albedo of the large-grain dust at <= 0.12. Our best estimate of the nucleus radius (1.82 +/- 0.20 km) and albedo (0.04 +/- 0.01) are in agreement with measurements previously reported in the literature

WISE/NEOWISE observations of Active Bodies in the Main Belt

We report results based on mid-infrared photometry of 5 active main belt objects (AMBOs) detected by the Wide-field Infrared Survey Explorer (WISE) spacecraft. Four of these bodies, P/2010 R2 (La Sagra), 133P/Elst-Pizarro, (596) Scheila, and 176P/LINEAR, showed no signs of activity at the time of the observations, allowing the WISE detections to place firm constraints on their diameters and albedos. Geometric albedos were in the range of a few percent, and on the order of other measured comet nuclei. P/2010 A2 was observed on April 2-3, 2010, three months after its peak activity. Photometry of the coma at 12 and 22 {\mu}m combined with ground-based visible-wavelength measurements provides constraints on the dust particle mass distribution (PMD), dlogn/dlogm, yielding power-law slope values of {\alpha} = -0.5 +/- 0.1. This PMD is considerably more shallow than that found for other comets, in particular inbound particle fluence during the Stardust encounter of comet 81P/Wild 2. It is similar to the PMD seen for 9P/Tempel 1 in the immediate aftermath of the Deep Impact experiment. Upper limits for CO2 & CO production are also provided for each AMBO and compared with revised production numbers for WISE observations of 103P/Hartley 2.Comment: 32 Pages, including 5 Figure

Finding Radio Pulsars in and Beyond the Galactic Center

Radio-wave scattering is enhanced dramatically for Galactic center sources in a region with radius >~ 15 arc min. Using scattering from Sgr A* and other sources, we show that pulse broadening for pulsars in the Galactic center is {\em at least} 6.3 \nu^{-4} seconds (\nu = radio frequency in GHz) and is most likely 50--200 times larger because the relevant scattering screen appears to be within the Galactic center region itself. Pulsars beyond---but viewed through---the Galactic center suffer even greater pulse broadening and are angularly broadened by <~ 2 {\em arc min}. Periodicity searches at radio frequencies are likely to find only long period pulsars and, then, only if optimized by using frequencies >~ 7 GHz and by testing for small numbers of harmonics in the power spectrum. The optimal frequency is $\nu ~ 7.3 GHz (\Delta_{0.1}P\sqrt{\alpha})^{-1/4}$ where \Delta_{0.1} is the distance of the scattering region from Sgr A* in units of 0.1 kpc, P is the period (seconds), and \alpha is the spectral index. A search for compact sources using aperture synthesis may be far more successful than searches for periodicities because the angular broadening is not so large as to desensitize the survey. We estimate that the number of {\em detectable} pulsars in the Galactic center may range from <= 1 to 100, with the larger values resulting from recent, vigorous starbursts. Such pulsars provide unique opportunities for probing the ionized gas, gravitational potential, and stellar population near Sgr A*.Comment: 13 pages, 4 PS figures, LaTeX and requires AASTeX macro aas2pp4, accepted by ApJ, also available as http://astrosun.tn.cornell.edu/SPIGOT/papers/pulsar/gc_psr.web

Bostonia: The Boston University Alumni Magazine. Volume 9

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Debiasing the NEOWISE Cryogenic Mission Comet Populations

We use NEOWISE data from the four-band and three-band cryogenic phases of the Wide-field Infrared Survey Explorer mission to constrain size distributions of the comet populations and debias measurements of the short- and long-period comet (LPC) populations. We find that the fit to the debiased LPC population yields a cumulative size−frequency distribution (SFD) power-law slope (β) of −1.0 ± 0.1, while the debiased Jupiter-family comet (JFC) SFD has a steeper slope with β = −2.3 ± 0.2. The JFCs in our debiased sample yielded a mean nucleus size of 1.3 km in diameter, while the LPCs' mean size is roughly twice as large, 2.1 km, yielding mean size ratios (〈D_(LPC)〉/〈D_(JFC)〉) that differ by a factor of 1.6. Over the course of the 8 months of the survey, our results indicate that the number of LPCs passing within 1.5 au are a factor of several higher than previous estimates, while JFCs are within the previous range of estimates of a few thousand down to sizes near 1.3 km in diameter. Finally, we also observe evidence for structure in the orbital distribution of LPCs, with an overdensity of comets clustered near 110° inclination and perihelion near 2.9 au that is not attributable to observational bias

The NEOWISE-Discovered Comet Population and the CO+CO_2 production rates

The 163 comets observed during the WISE/NEOWISE prime mission represent the largest infrared survey to date of comets, providing constraints on dust, nucleus size, and CO + CO_2 production. We present detailed analyses of the WISE/NEOWISE comet discoveries, and discuss observations of the active comets showing 4.6 μm band excess. We find a possible relation between dust and CO + CO_2 production, as well as possible differences in the sizes of long and short period comet nuclei