Faculty Productivity in Supervising Doctoral Students’ Dissertations at Cornell University

Excerpt] Economists and academic administrators have long been concerned with issues of faculty productivity. For example, sets of studies have addressed whether faculty research productivity is related to faculty salaries, whether gender differences in faculty salaries remain after one controls for research productivity, and whether a negative association between faculty salary and seniority at an institution is due to universities having monopsony power or due to declining faculty research productivity with seniority. To take another example, concern that the ending of mandatory retirement, which became effective for tenured faculty in January 1994, would lead to an aging nonproductive faculty has led other researchers to examine how faculty research and teaching productivity, the latter measured by undergraduate student evaluations, have varied over the life cycle. More recently, researchers studied whether declining research productivity is related to the acceptance of an offer for an early retirement incentive. Finally, other researchers have looked at how faculty research productivity varies across cohorts, finding that when a scientist enters the labor market has a substantial effect on his or her productivity over the life cycle and that more recently educated cohorts are not necessarily more productive than earlier cohorts. While some studies have looked at the implicit role that PhD student production has on the quality rankings of PhD programs, to our knowledge no studies have focused on how the distribution of PhD student supervisory responsibilities varies across faculty members at a university. Our study uses data on all PhDs produced during a 7-year period at Cornell University to illustrate how researchers can study whether the degree of inequality in PhD student supervision across faculty members within a broad field of study, varies across fields, as well as what the determinants are of differences in PhD student supervision responsibilities across individual faculty members within each broad field. Of particular concern to us, given the elimination of mandatory retirement, is how faculty members’ productivity in the supervision of PhD students varies over their life cycles

Tracing a relativistic Milky Way within the RAMOD measurement protocol

Advancement in astronomical observations and technical instrumentation implies taking into account the general relativistic effects due the gravitational fields encountered by the light while propagating from the star to the observer. Therefore, data exploitation for Gaia-like space astrometric mission (ESA, launch 2013) requires a fully relativistic interpretation of the inverse ray-tracing problem, namely the development of a highly accurate astrometric models in accordance with the geometrical environment affecting light propagation itself and the precepts of the theory of measurement. This could open a new rendition of the stellar distances and proper motions, or even an alternative detection perspective of many subtle relativistic effects suffered by light while it is propagating and subsequently recorded in the physical measurements.Comment: Proceeding for "Relativity and Gravitation, 100 Years after Einstein in Prague" to be published by Edition Open Access, revised versio

Bistability and instability of dark-antidark solitons in the cubic-quintic nonlinear Schroedinger equation

We characterize the full family of soliton solutions sitting over a background plane wave and ruled by the cubic-quintic nonlinear Schroedinger equation in the regime where a quintic focusing term represents a saturation of the cubic defocusing nonlinearity. We discuss existence and properties of solitons in terms of catastrophe theory and fully characterize bistability and instabilities of the dark-antidark pairs, revealing new mechanisms of decay of antidark solitons.Comment: 8 pages, 10 figures, accepted in PR

The hydrogeological role of an aquitard in preventing drinkable water well contamination: a case study.

Groundwater pollution has become a worrisome phenomenon, mainly for aquifers underlying industrialized areas. In order to evaluate the risk of pollution, a model of the aquifer is needed. Herewith, we describe a quasi-tridimensional model, which we applied to a multilayered aquifer where a phreatic aquifer was coupled to a confined one by means of an aquitard. This hydrogeological scheme is often met in practice and, therefore, models a number of situations. Moreover, aquitards play and important role in the management of natural resources of this kind. The model we adopted contains some approximations: the flow within the aquifers is assumed to be horizontal, whereas leakage is assumed vertical. The effect of some wells drilled in these aquifers is also taken into account. In order to evaluate the leakage fluxes that correspond to different exploitation conditions, we numerically solve a system of quasilinear and time-dependent partial differential equations. This model has been calibrated by the hydrogeological data from a water supply station of the Milan Water Works, where water is polluted by some halocarbons. Our simulations account for several experimental facts, both from the hydrogeological and hydrogeochemical viewpoints. Maxima of computed downward leakage rates are found to correspond with measured pollutant concentration maxima. Other results show how the aquitard can help in minimizing the contamination of drinkable water

A general relativistic model for the light propagation in the gravitational field of the Solar System: the dynamical case

Modern astrometry is based on angular measurements at the micro-arcsecond level. At this accuracy a fully general relativistic treatment of the data reduction is required. This paper concludes a series of articles dedicated to the problem of relativistic light propagation, presenting the final microarcsecond version of a relativistic astrometric model which enable us to trace back the light path to its emitting source throughout the non-stationary gravity field of the moving bodies in the Solar System. The previous model is used as test-bed for numerical comparisons to the present one. Here we also test different versions of the computer code implementing the model at different levels of complexity to start exploring the best trade-off between numerical efficiency and the micro-arcsecond accuracy needed to be reached.Comment: 40 pages, 5 figures. Accepted for publication on The Astrophysical Journal. Manuscript prepared with AASLaTeX macros v.5.

Crossover dynamics of dispersive shocks in Bose-Einstein condensates characterized by two and three-body interactions

We show that the perturbative nonlinearity associated with three-atom interactions, competing with standard two-body repulsive interactions, can change dramatically the evolution of 1D dispersive shock waves in a Bose-Einstein condensate. In particular, we prove the existence of a rich crossover dynamics, ranging from the formation of multiple shocks regularized by coexisting trains of dark and antidark matter waves, to 1D soliton collapse. For a given scattering length, all these different regimes can be accessed by varying the number of atoms in the condensate.Comment: 4 pages, 5 figure

Testing general relativity by micro-arcsecond global astrometry

The global astrometric observations of a GAIA-like satellite were modeled within the PPN formulation of Post-Newtonian gravitation. An extensive experimental campaign based on realistic end-to-end simulations was conducted to establish the sensitivity of global astrometry to the PPN parameter \gamma, which measures the amount of space curvature produced by unit rest mass. The results show that, with just a few thousands of relatively bright, photometrically stable, and astrometrically well behaved single stars, among the ~10^9 objects that will be observed by GAIA, \gamma can be estimated after 1 year of continuous observations with an accuracy of ~10^{-5} at the 3\sigma level. Extrapolation to the full 5-year mission of these results based on the scaling properties of the adjustment procedure utilized suggests that the accuracy of \simeq 2x10^{-7}, at the same 3\sigma level, can be reached with \~10^6 single stars, again chosen as the most astrometrically stable among the millions available in the magnitude range V=12-13. These accuracies compare quite favorably with recent findings of scalar-tensor cosmological models, which predict for \gamma a present-time deviation, |1-\gamma|, from the General Relativity value between 10^{-5} and 10^{-7}.Comment: 7 pages, 2 figures, to be published in A&

Landscapes of Northern Lombardy: from the glacial scenery of Upper Valtellina to the prealpine lacustrine environment of Lake Como

In the region between Valtellina and Lake Como in the Central Italian Alps, one can visit, in a relatively small area, some of the best examples of mountain geomorphological landscapes of Italy. Eight specific sites-showing peculiar glacial, periglacial, structural, gravity-induced and erosional landforms-have been selected to illustrate how different landscapes may originate from geomorphological modelling of different lithotypes in different morphogenetic systems. These eight sites are exemplary cases in which significant evidence of past and current climatic and structural conditions characterising this region is exhibited