The Three-Dimensional Structure Of The Infrared Cirrus

This project was carried out over a period of four years, beginning 6/15/89 and continuing through 9/15/93. Intermediate results have been reported as poster papers at several meetings of the American Astronomical Society. A brief summary was presented in April 1993 at a symposium on the infrared cirrus. The final results were published in late 1993. The measurements have been deposited in NASA\u27s Astronomical Data Center. Briefly, the results are as follows: Using the IRAS data base, we surveyed the 1808 06-B9.5 stars in the Bright Star Catalog for extended excess emission at 60 micrometers, indicating the presence of heated dust (cirrus hotspots) at the location of the star. Measurements of the angular size and infrared flux at 12, 25, 60 and 100 micrometers were obtained for 302 objects. From these basic data we calculated the radius, absorption, optical depth, color temperature, and dust density for each object. Arguing that the stars are randomly distributed point probes of the ISM, we showed that the filling factor of the dust-bearing component of the ISM is 14.6 + 2.4 percent within 400 pc of the sun for clouds with an equivalent hydrogen density greater than 0.5 cm(exp -3). Above a density of 1.0 cm(exp -3) the density distribution function appears to follow a power law of index -1.25. Further, we showed that the dust is distributed more sparsely in a region near the sun about 60 pc wide and extending several hundred parsecs in the direction of longitudes 80-260 deg. The distances to the dust clouds were determined from the spectroscopic parallaxes of the embedded stars; when the HIPPARCOS parallaxes become available, we will be able to produce a more accurate three-dimensional view of the local ISM

A Robotic Wide-Angle H-Alpha Survey of the Southern Sky

We have completed a robotic wide-angle imaging survey of the southern sky (declination less than +15 degrees) at 656.3 nm wavelength, the H-alpha emission line of hydrogen. Each image of the resulting Southern H-Alpha Sky Survey Atlas (SHASSA) covers an area of the sky 13 degrees square at an angular resolution of approximately 0.8 arcminute, and reaches a sensitivity level of 2 rayleigh (1.2 x 10^-17 erg cm^-2 s^-1 arcsec^-2) per pixel, corresponding to an emission measure of 4 cm^-6 pc, and to a brightness temperature for microwave free-free emission of 12 microkelvins at 30 GHz. Smoothing over several pixels allows features as faint as 0.5 rayleigh to be detected.Comment: LATEX, 33 pages, 15 figures. Accepted for publication in PASP, 113, November 2001. Further information at http://amundsen.swarthmore.edu/SHASSA

Mycoplasma Contamination Revisited: Mesenchymal Stromal Cells Harboring Mycoplasma hyorhinis Potently Inhibit Lymphocyte Proliferation In Vitro

Mesenchymal stromal cells (MSC) have important immunomodulatory effects that can be exploited in the clinical setting, e.g. in patients suffering from graft-versus-host disease after allogeneic stem cell transplantation. In an experimental animal model, cultures of rat T lymphocytes were stimulated in vitro either with the mitogen Concanavalin A or with irradiated allogeneic cells in mixed lymphocyte reactions, the latter to simulate allo-immunogenic activation of transplanted T cells in vivo. This study investigated the inhibitory effects of rat bone marrow-derived MSC subsequently found to be infected with a common mycoplasma species (Mycoplasma hyorhinis) on T cell activation in vitro and experimental graft-versus-host disease in vivo.We found that M. hyorhinis infection increased the anti-proliferative effect of MSC dramatically, as measured by both radiometric and fluorimetric methods. Inhibition could not be explained solely by the well-known ability of mycoplasmas to degrade tritiated thymidine, but likely was the result of rapid dissemination of M. hyorhinis in the lymphocyte culture.This study demonstrates the potent inhibitory effect exerted by M. hyorhinis in standard lymphocyte proliferation assays in vitro. MSC are efficient vectors of mycoplasma infection, emphasizing the importance of monitoring cell cultures for contamination

Temperature And Brightness Variations On Betelgeuse

Changes in TiO band strengths correlate well with the brightness changes of α Orionis, thus supporting the hypothesis of Schwarzschild that the irregular luminosity variations of red giants are due to temperature changes in a few extremely large convective elements on their surface

The Distribution Of Interstellar Dust In The Solar Neighborhood

We surveyed the IRAS data base at the positions of the 1808 O6-B9.5 stars in The Bright Star Catalog for extended objects with excess emission at 60 mum, indicating the presence of interstellar dust at the location of the star. Within 400 pc the filling factor of the interstellar medium for dust clouds with a density \u3e0.5 cm-3 is 14.6 +/- 2.4%. Above a density of 1.0 cm-3, the density distribution function appears to follow a power law of index -1.25. When the dust clouds are mapped onto the galactic plane, the sun appears to be located in a low-density region of the interstellar medium of width about 60 pc extending at least 500 pc in the direction of longitudes 80-degrees-260-degrees, a feature we call the \u27\u27local trough.\u27\u2

An Upper Limit On The Contribution Of Galactic Free-Free Emission To The Cosmic Microwave Background Near The North Celestial Pole

We have observed the region of the sky north of 81 degrees declination with a wide-angle CCD camera and narrow-band (1 nn) H alpha filter. After subtracting the stellar background using off-band images and smoothing to 0.1 degrees resolution, we set an upper limit on the anisotropy in the H alpha emission at this angular scale of 1.3 Rayleigh. At degree angular scales, the upper limit is 0.5 R, which corresponds to an anisotropy in the brightness temperature of the free-free emission at 32 GHz of 3 mu K. Thus no more than 7% of the 44 mu K anisotropy observed by Netterfield et al. (ApJ, 331, 341, 1995) can be due to free-free emission by Galactic hydrogen