The Role of Pre-Market Factors in Black-White Wage Differences

Many attempts to measure the wage effects of current labor market discrimination against minorities include controls for worker productivity that (1) could themselves be affected by market discrimination and (2) are very imprecise measures of worker skill. The resulting estimates of residual wage gaps may be biased. Our approach is a parsimoniously specified wage equation which controls for skill with the score of a test administered as teenagers prepared to leave high school and embark on work careers or post-secondary education. Independent evidence shows that this test score is a racially unbiased measure of the skills and abilities these teenagers were about to bring to the labor market. We find that this one test score explains all of the black-white wage gap for young women and much of the gap for young men. For today's young adults, the black-white wage gap primarily reflects a skill gap, which in turn can be traced, at least in part, to observable differences in the family backgrounds and school environments of black and white children. While our results do provide some evidence of current labor market discrimination, skill gaps play such a large role that we believe future research should focus on the obstacles black children face in acquiring productive skills.

Two Metals Are Better Than One in the Gold Catalyzed Oxidative Heteroarylation of Alkenes

We present a detailed study of the mechanism for oxidative heteroarylation, based on DFT calculations and experimental observations. We propose binuclear Au(II)–Au(II) complexes to be key intermediates in the mechanism for gold catalyzed oxidative heteroarylation. The reaction is thought to proceed via a gold redox cycle involving initial oxidation of Au(I) to binuclear Au(II)–Au(II) complexes by Selectfluor, followed by heteroauration and reductive elimination. While it is tempting to invoke a transmetalation/reductive elimination mechanism similar to that proposed for other transition metal complexes, experimental and DFT studies suggest that the key C–C bond forming reaction occurs via a bimolecular reductive elimination process (devoid of transmetalation). In addition, the stereochemistry of the elimination step was determined experimentally to proceed with complete retention. Ligand and halide effects played an important role in the development and optimization of the catalyst; our data provides an explanation for the ligand effects observed experimentally, useful for future catalyst development. Cyclic voltammetry data is presented that supports redox synergy of the Au···Au aurophilic interaction. The monometallic reductive elimination from mononuclear Au(III) complexes is also studied from which we can predict a ~ 15 kcal/mol advantage for bimetallic reductive elimination

Abell 2111: An Optical and Radio Study of the Richest Butcher-Oemler Cluster

We present an in-depth analysis of the Butcher-Oemler cluster A2111, including new optical spectroscopy plus a deep Very Large Array (VLA) radio continuum observation. These are combined with optical imaging from the Sloan Digital Sky Survey (SDSS) to assess the activity and properties of member galaxies. Prior X-ray studies have suggested A2111 is a head-on cluster merger, a dynamical state which might be connected to the high level of activity inferred from its blue fraction. We are able to directly assess this claim, using our spectroscopic data to identify 95 cluster members among 196 total galaxy spectra. These galaxy velocities do not themselves provide significant evidence for the merger interpretation, however they are consistent with it provided the system is viewed near the time of core passage and at a viewing angle >~30 degrees different from the merger axis. The SDSS data allow us to confirm the high blue fraction for A2111, f_b = 0.15 +/- 0.03 based on photometry alone and f_b = 0.23 +/- 0.03 using spectroscopic data to remove background galaxies. We are able to detect 175 optical sources from the SDSS in our VLA radio data, of which 35 have redshift information. We use the SDSS photometry to determine photometric redshifts for the remaining 140 radio-optical sources. In total we identify up to 26 cluster radio galaxies, 14 of which have spectroscopic redshifts. The optical spectroscopy and radio data reveal a substantial population of dusty starbursts within the cluster. The high blue fraction and prevalence of star formation is consistent with the hypothesis that dynamically-active clusters are associated with more active member galaxies than relaxed clusters.Comment: To appear in AJ; 53 pages including 10 figures and several long table

The Dynamics of Abell 2125

We present 371 galaxy velocities in the field of the very rich cluster Abell 2125 (z~0.25). These were determined using optical spectroscopy collected over several years from both the WIYN 3.5m telescope and NOAO Mayall 4m telescope. Prior studies at a variety of wavelengths (radio, optical, and X-ray) have indicated that A2125 is a likely cluster-cluster merger, a scenario which we are able to test using our large velocity database. We identified 224 cluster galaxies, which were subjected to a broad range of statistical tests using both positional and velocity information to evaluate the cluster dynamics and substructure. The tests confirmed the presence of substructures within the Abell 2125 system at high significance, demonstrating that A2125 is a complex dynamical system. Comparison of the test results with existing simulations strengthens the merger hypothesis, and provides clues about the merger geometry and stage. The merger model for the system can reconcile A2125's low X-ray temperature and luminosity with its apparently high richness, and might also explain A2125's high fraction of active galaxies identified in prior radio and optical studies.Comment: 34 pages, including tables and 3 color figures; to appear in Ap

A New Moderately Repetitive DNA Sequence Family of Novel Organization

In cloning adenovirus homologous sequences, from a human cosmid library, we identified a moderately repetitive DNA sequence family consisting of tandem arrays of 2.5 kb members. A member was sequenced and several non-adjacent, 15–20 bp G-C rich segments with homology to the left side of adenovirus were discovered. The copy number of 400 members is highly conserved among humans. Southern blots of partial digests of human DNA have verified the tandem array of the sequence family. The chromosomal location was defined by somatic cell genetics and in situ hybridization. Tandem arrays are found only on chromosomes 4 (4q31) and 19 (ql3.l-ql3.3). Homologous repetitive sequences are found in DNA of other primates but not in cat or mouse. Thus we have identified a new family of moderately repetitive DNA sequences, unique because of its organization in clustered tandem arrays, its length, its chromosomal location, and its lack of homology to other moderately repetitive sequence families

Development of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Blades

This paper will describe the results from a proof of concept test to examine the feasibility of using Pressure Sensitive Paint (PSP) to measure global surface pressures on rotorcraft blades in hover. The test was performed using the U.S. Army 2-meter Rotor Test Stand (2MRTS) and 15% scale swept rotor blades. Data were collected from five blades using both the intensity- and lifetime-based approaches. This paper will also outline several modifications and improvements that are underway to develop a system capable of measuring pressure distributions on up to four blades simultaneously at hover and forward flight conditions