Dynamic changes in connexin expression correlate with key events in the wound healing process.

Wound healing is a complex process requiring communication for the precise co-ordination of different cell types. The role of extracellular communication through growth factors in the wound healing process has been extensively documented, but the role of direct intercellular communication via gap junctions has scarcely been investigated. We have examined the dynamics of gap junction protein (Connexins 26, 30, 31.1 and 43) expression in the murine epidermis and dermis during wound healing, and we show that connexin expression is extremely plastic between 6 hours and 12 days post-wounding. The immediate response (6 h) to wounding is to downregulate all connexins in the epidermis, but thereafter the expression profile of each connexin changes dramatically. Here, we correlate the changing patterns of connexin expression with key events in the wound healing process

Farm Program Flexibility Options and Sustainable Agriculture

The phrase planting f1exibility was influential in the formation of The Food, Agriculture, Conservation, and Trade Act of 1990 (the 1990 Farm Bill).Several planting flexibility proposals were introduced during the congressional debates leading up to the 1990 Farm Bl11. Each proposal differed in the amount of planting flexibility given to farmers and which acres to use in the calculation of farm program benefits. In this report, we will look at three of those proposals --the Normal Crop Acreage program, the Triple Base program, and the Integrated Farm Management Program Option. For purposes of our analyses, we have selected 10 case farms (sustainable, and conventional). The case farms\u27 used in this report are the same as those used in other recent research reported by the Economics Department at South Dakota State University (Dobbs, et a1., 1990; Becker and Dobbs, 1990; Cole and Dobbs, 1990). Each sustainable and conventional farm represents one of five different agro-c1imatic areas within South Dakota: south-central, east-central, northeast, northwest, and southwest (Figure 1). In this report, we will first describe the details of each flexibility option. Then, we will show the results of applying the various flexibility options to each sustainable and conventional case farm

Implications of a Mandatory Supply Control Program for Sustainable Agriculture in South Dakota

This is one of a series of reports by the authors on implications for conventional and sustainable farming systems of various public policy options. Previously released was a report by Dobbs, Becker, and Taylor (1990) which provided an overview of the implications of several policy options. The present report focuses specifically on mandatory supply controls. A future report will deal with the implications of flexibility and triple base policy options

Detecting Stellar Spots by Gravitational Microlensing

During microlensing events with a small impact parameter, the amplification of the source flux is sensitive to the surface brightness distribution of the source star. Such events provide a means for studying the surface structure of target stars in the ongoing microlensing surveys, most efficiently for giants in the Galactic bulge. In this work we demonstrate the sensitivity of point-mass microlensing to small spots with radii $r_s\lesssim0.2$ source radii. We compute the amplification deviation from the light curve of a spotless source and explore its dependence on lensing and spot parameters. During source-transit events spots can cause deviations larger than 2%, and thus be in principle detectable. Maximum relative deviation usually occurs when the lens directly crosses the spot. Its numerical value for a dark spot with sufficient contrast is found to be roughly equal to the fractional radius of the spot, i.e., up to 20% in this study. Spots can also be efficiently detected by the changes in sensitive spectral lines during the event. Notably, the presence of a spot can mimic the effect of a low-mass companion of the lens in some events.Comment: 18 pages with 7 Postscript figures, to appear in ApJ, January 2000; discussion expanded, references added, minor revisions in tex

The FIRST-2MASS Red Quasar Survey

Combining radio observations with optical and infrared color selection -- demonstrated in our pilot study to be an efficient selection algorithm for finding red quasars -- we have obtained optical and infrared spectroscopy for 120 objects in a complete sample of 156 candidates from a sky area of 2716 square degrees. Consistent with our initial results, we find our selection criteria -- J-K>1.7, R-K>4.0 -- yield a ~50% success rate for discovering quasars substantially redder than those found in optical surveys. Comparison with UVX- and optical color-selected samples shows that >~ 10% of the quasars are missed in a magnitude-limited survey. Simultaneous two-frequency radio observations for part of the sample indicate that a synchrotron continuum component is ruled out as a significant contributor to reddening the quasars' spectra. We go on to estimate extinctions for our objects assuming their red colors are caused by dust. Continuum fits and Balmer decrements suggest E(B-V) values ranging from near zero to 2.5 magnitudes. Correcting the K-band magnitudes for these extinctions, we find that for K <= 14.0, red quasars make up between 25% and 60% of the underlying quasar population; owing to the incompleteness of the 2MASS survey at fainter K-band magnitudes, we can only set a lower limit to the radio-detected red quasar population of >20-30%.Comment: 80 pages (single-column, preprint format) 20 figures, Accepted for publicated in Ap