Spitzer Observations of Molecular Hydrogen in Interacting Supernova Remnants

With Spitzer IRS we have obtained sensitive low-resolution spectroscopy from 5 to 35 microns for six supernova remnants (SNRs) that show evidence of shocked molecular gas: Kes 69, 3C 396, Kes 17, G346.6-0.2, G348.5-0.0 and G349.7+0.2. Bright, pure-rotational lines of molecular hydrogen are detected at the shock front in all remnants, indicative of radiative cooling from shocks interacting with dense clouds. We find the excitation of H2 S(0)-S(7) lines in these SNRs requires two non-dissociative shock components: a slow, 10 km/s C- shock through clumps of density 10^6 cm^-3, and a faster, 40-70 km/s C- shock through a medium of density 10^4 cm^-3. The ortho-to-para ratio for molecular hydrogen in the warm shocked gas is typically found to be much less than the LTE value, suggesting that these SNRs are propagating into cold quiescent clouds. Additionally a total of thirteen atomic fine-structure transitions of Ar+, Ar++, Fe+, Ne+, Ne++, S++, and Si+ are detected. The ionic emitting regions are spatially segregated from the molecular emitting regions within the IRS slits. The presence of ionic lines with high appearance potential requires the presence of much faster, dissociative shocks through a lower density medium. The IRS slits are sufficiently wide to include regions outside the SNR which permits emission from diffuse gas around the remnants to be separated from the shocked emission. We find the diffuse molecular hydrogen gas projected outside the SNR is excited to a temperature of 100 to 300 K with a warm gas fraction of 0.5 to 15 percent along the line of sight.Comment: Accepted to Ap J and scheduled for 2009 April 1 v694 issue. LaTeX, 27 pages with 11 figure

A Spitzer Space Telescope Infrared Survey of Supernova Remnants in the Inner Galaxy

Using Infrared Array Camera (IRAC) images at 3.6, 4.5, 5.8, and 8 microns from the GLIMPSE Legacy science program on the Spitzer Space Telescope, we searched for infrared counterparts to the 95 known supernova remnants that are located within galactic longitudes 65>|l|>10 degrees and latitudes |b|<1 degree. Eighteen infrared counterparts were detected. Many other supernova remnants could have significant infrared emission but are in portions of the Milky Way too confused to allow separation from bright HII regions and pervasive mid-infrared emission from atomic and molecular clouds along the line of sight. Infrared emission from supernova remnants originates from synchrotron emission, shock-heated dust, atomic fine-structure lines, and molecular lines. The detected remnants are G11.2-0.3, Kes 69, G22.7-0.2, 3C 391, W 44, 3C 396, 3C 397, W 49B, G54.4-0.3, Kes 17, Kes 20A, RCW 103, G344.7-0.1, G346.6-0.2, CTB 37A, G348.5-0.0, and G349.7+0.2. The infrared colors suggest emission from molecular lines (9 remnants), fine-structure lines (3), and PAH (4), or a combination; some remnants feature multiple colors in different regions. None of the remnants are dominated by synchrotron radiation at mid-infrared wavelengths. The IRAC-detected sample emphasizes remnants interacting with relatively dense gas, for which most of the shock cooling occurs through molecular or ionic lines in the mid-infrared.Comment: Accepted 10/18/2005 for publication in "The Astronomical Journal". The figures in this astro-ph submission are drastically reduced in quality in order to fit within its limit

Atherosclerotic risk factor reduction in peripheral arterial diseasea: results of a national physician survey

OBJECTIVE: Individuals with peripheral arterial disease (PAD) have a 3- to 6-fold increased risk of coronary heart disease and stroke compared to those without PAD. We documented physician-reported practice behavior, knowledge, and attitudes regarding atherosclerotic risk factor reduction in patients with PAD. DESIGN: National physician survey. PATIENTS/PARTICIPANTS: General internists (N = 406), family practitioners (N = 435), cardiologists (N = 473), and vascular surgeons (N = 264) randomly identified using the American Medical Association\u27s physician database. MEASUREMENTS AND MAIN RESULTS: Physicians were randomized to 1 of 3 questionnaires describing a) a 55- to 65-year-old patient with PAD; b) a 55- to 65-year-old patient with coronary artery disease (CAD), or c) a 55- to 65-year-old patient without clinically evident atherosclerosis (no disease). A mailed questionnaire was used to compare physician behavior, knowledge, and attitude regarding risk factor reduction for each patient. Rates of prescribed antiplatelet therapy were significantly lower for the patient with PAD than for the patient with CAD. Average low-density lipoprotein levels at which physicians almost always initiated lipid-lowering drugs were 121.6 +/- 23.5 mg/dL, 136.3 +/- 28.9 mg/dL, and 149.7 +/- 24.4 mg/dL for the CAD, PAD, and no-disease patients, respectively (PCONCLUSIONS: Deficiencies in physician knowledge and attitudes contribute to lower rates of atherosclerotic risk factor reduction for patients with PAD. Reversing these deficiencies may reduce the high rates of cardiovascular morbidity and mortality associated with PAD