Acceleration of phenological advance and warming with latitude over the past century.

In the Northern Hemisphere, springtime events are frequently reported as advancing more rapidly at higher latitudes, presumably due to an acceleration of warming with latitude. However, this assumption has not been investigated in an analytical framework that simultaneously examines acceleration of warming with latitude while accounting for variation in phenological time series characteristics that might also co-vary with latitude. We analyzed 743 phenological trend estimates spanning 86 years and 42.6 degrees of latitude in the Northern Hemisphere, as well as rates of Northern Hemisphere warming over the same period and latitudinal range. We detected significant patterns of co-variation in phenological time series characteristics that may confound estimates of the magnitude of variation in trends with latitude. Notably, shorter and more recent time series tended to produce the strongest phenological trends, and these also tended to be from higher latitude studies. However, accounting for such variation only slightly modified the relationship between rates of phenological advance and latitude, which was highly significant. Furthermore, warming has increased non-linearly with latitude over the past several decades, most strongly since 1998 and northward of 59°N latitude. The acceleration of warming with latitude has likely contributed to an acceleration of phenological advance along the same gradient

Seniority, External Labor Markets, and Faculty Pay

We estimate the returns to seniority (the wage-tenure profile) for university faculty, and the degree to which these returns respond to entry-level salaries (or opportunity wages) a relationship unexplored in work to date. Using data on faculty at a Big Ten university (ours), we estimate elasticities of senior-faculty salaries with respect to entry-level salaries, and find that these elasticities decline with seniority. The evidence both provides an explanation of faculty salary compression and suggests the importance of controlling for entry-level salaries in obtaining estimates of the returns to seniority.faculty, wages, college, labor, markets, Brown, Woodbury

Gender Differences in Faculty Turnover

Over the last 15 to 20 years, colleges and universities have paid increasing attention to attracting and retaining faculty women. The rate of progress of women in academe has nevertheless been painfully slow. For example, statistics on economists collected and published by the American Economic Association (Committee on the Status of Women in the Economics Profession 1994) suggest that in recent years, about 20 percent of Economics assistant professors in graduate Ph.D.-granting departments were women, about 10 percent of associate professors were women, and under 5 percent of full professors were women. The percentage of new assistant professors who are women has lagged behind the percentage of new Ph.D.s who are women by 10 to 15 percentage points. And the percentage of promotions to associate (and full) professor that are accounted for by women has lagged behind the percentage of assistant (and associate) professors who were women and "promotable." One of the explanations (or perhaps excuses) offered for the slow progress of women in academe is that faculty women have higher rates of voluntary turnover than do faculty men. This explanation accords with the general finding that women have higher rates of labor market turnover than do men (Blau and Kahn 1981; Light and Ureta 1992), and may provide a psychic calm both for those frustrated by the slow progress of women in academe and for those who might frustrate that progress. Studies to date of faculty turnover have used grouped (or university-level) data, which usually preclude examination of gender differences in faculty turnover (Ehrenberg, Kasper, and Rees 1991; Rees and Smith 1991). In this paper we offer evidence on faculty turnover using micro data from a single large public university Michigan State University (MSU) during the decade of the 1980s. Our findings suggest strongly that the higher separation rates that are observed for faculty women are accounted for by differences between men and women in appointment status that is, faculty women have higher turnover rates than faculty men because a higher percentage of women than of men hold temporary appointments.faculty, college, gender, turnover, Brown, Woodbury

Pleistocene molluscan faunas and physiographic history of Pecos Valley in Texas

Bibliography: p. 29.UT Librarie

Reactive self-heating model of aluminum spherical nanoparticles

Aluminum-oxygen reaction is important in many highly energetic, high pressure generating systems. Recent experiments with nanostructured thermites suggest that oxidation of aluminum nanoparticles occurs in a few microseconds. Such rapid reaction cannot be explained by a conventional diffusion-based mechanism. We present a rapid oxidation model of a spherical aluminum nanoparticle, using Cabrera-Mott moving boundary mechanism, and taking self-heating into account. In our model, electric potential solves the nonlinear Poisson equation. In contrast with the Coulomb potential, a "double-layer" type solution for the potential and self-heating leads to enhanced oxidation rates. At maximal reaction temperature of 2000 C, our model predicts overall oxidation time scale in microseconds range, in agreement with experimental evidence.Comment: submitte