Scaling Laws for Dark Matter Halos in Late-Type and Dwarf Spheroidal Galaxies

Maximum disk mass models fitted to galaxy rotation curves are used to show that dark matter (DM) halos in late-type and dwarf spheroidal (dSph) galaxies satisfy well defined scaling laws. Halos in less luminous galaxies have smaller core radii, higher central densities, and smaller central velocity dispersions. Implications: (1) A single, continuous physical sequence of increasing mass extends from the tiniest dSphs to the most luminous spirals. (2) The high DM densities in dSph galaxies are normal for such dwarf galaxies. Since virialized density depends on collapse redshift z, the smallest dwarfs formed about delta z = 7 earlier than the biggest spirals. (3) The high DM densities of dSphs implies that they are real galaxies formed from primordial density fluctuations. They are not tidal fragments. (4) Because dwarf galaxies become more numerous and more nearly dominated by DM as luminosity decreases, there may be a large population of objects that are completely dark. Such objects are a canonical prediction of cold DM theory. (5) The slopes of the DM parameter correlations provide a measure on galactic mass scales of the slope n of the power spectrum of primordial density fluctuations. Our results not yet corrected for baryonic compression of DM give n = -1.9 +- 0.2. This is consistent with cold DM theory.Comment: 19 pages, 5 Postscript figures; requires IAUS215.sty; to appear in "IAU Symposium 220, Dark Matter in Galaxies", ed. Ryder, Pisano, Walker, and Freeman, San Francisco: ASP, in pres

What if Congress Doubled R&D Spending on the Physical Sciences?

Many business, academic, and scientific groups have recommended that the Congress substantially increase R&D spending in the near future. President Bush's American Competitiveness Initiative calls for a doubling of spending over the next decade in selected agencies that deal with the physical sciences, including the National Science Foundation. We consider the rationale for government R&D spending in the context of globalization and as an investment in human capital and knowledge creation with gestation times far longer than Federal funding cycles. To assess the impact of a large increase in R&D spending on the science job market, we examine the impact of the 1998- 2003 doubling of the NIH budget on the bio-medical sciences. We find that the rapid increase in NIH spending and ensuing deceleration created substantial adjustment problems in the market for research and failed to address long-standing problems with scientific careers that are likely to deter many young people from choosing a scientific career. We argue that because research simultaneously produces knowledge and add to the human capital of researchers, which has greater value for young scientists because of their longer future career life span than to older scientists, there is reason for funding agencies to tilt their awards to younger researchers.Basic Science, R&D, labor markets for scientists, globalization

What Went Wrong? The Erosion of Relative Earnings and Employment Among Young Black Men in the 1980s

This paper shows a widening in black-white earnings and employment gaps among young men from the mid-l970s through the 1980s that differs among subgroups. Earnings gaps increased most among college graduates and in the midwest while gaps in employment-population rates grew most among high school dropouts. We attribute the differential widening to distinct shifts in demand for subgroups due to changes in industry and regional employment, the falling real minimum wage and deunionisation, the growth of the relative supply of black to white workers that was marked among college graduates, and to increased crime, that was marked among high school dropouts. The differential factors affecting the groups highlights the economic diversity of black Americans.

Screening Program on Superalloys for Trisonic Transport. Report No. 2. Results for Cold-Worked N155 Alloy

N155 alloy sheet cold reduced 40 and 65 percent was subjected to a screening program in the as-rolled condition designed to rate materials for possible usefulness for the airframe of a trisonic transport plane, Cold reductions of 40 to 65 percent produced the following properties at room temperature in the as-rolled N155 sheet investigated