Worker Training in a Restructuring Economy: Evidence from the Russian Transition

We use 1994-1998 data from the Russian Longitudinal Monitoring Survey (RLMS) to measure the incidence and determinants of several types of worker training and to estimate the effects of training on workers' interindustry, interfirm, and occupational mobility, their labor force transitions, and their wage growth in Russia compared to the U.S. We hypothesize that the shock of economic liberalization in Russia may raise the benefits of training, particularly retraining for new jobs, but uncertainty concerning the revaluation of skills may raise the costs, with an overall ambiguous effect on the amount of training undertaken. The RLMS indicates a lower rate of formal training than studies have found for the U.S., suggesting that the second effect dominates. Previous schooling is estimated to affect the probability of training positively, but the relationship is much stronger for additional training in the same field than for retraining for new fields, consistent with the hypothesis that schooling and training are complementary but become more substitutable in a restructuring environment. Foreign ownership of the firm also positively affects the probability of undertaking training, providing evidence of active restructuring by foreigner investors. Additional training in workers' current fields is estimated to reduce mobility and earnings, suggesting inertial programs from the pre-transition era. Retraining in new fields increases all types of worker mobility and has higher returns than those typically observed for training in the U.S., but it also raises the variance of earnings and the probability of employment, consistent with a search view of such retraining. Given the large returns to retraining, the efforts of Russian workers to learn new skills may increase as uncertainty is resolved and restructuring proceeds.http://deepblue.lib.umich.edu/bitstream/2027.42/39715/3/wp331.pd

Temperature dependence of exciton recombination in semiconducting single-wall carbon nanotubes

We study the excitonic recombination dynamics in an ensemble of (9,4) semiconducting single-wall carbon nanotubes by high sensitivity time-resolved photo-luminescence experiments. Measurements from cryogenic to room temperature allow us to identify two main contributions to the recombination dynamics. The initial fast decay is temperature independent and is attributed to the presence of small residual bundles that create external non-radiative relaxation channels. The slow component shows a strong temperature dependence and is dominated by non-radiative processes down to 40 K. We propose a quantitative phenomenological modeling of the variations of the integrated photoluminescence intensity over the whole temperature range. We show that the luminescence properties of carbon nanotubes at room temperature are not affected by the dark/bright excitonic state coupling

A New Constraint on the Escape Fraction in Distant Galaxies Using Gamma-ray Burst Afterglow Spectroscopy

We describe a new method to measure the escape fraction fesc of ionizing radiation from distant star-forming galaxies using the afterglow spectra of long-duration gamma-ray bursts (GRBs). Optical spectra of GRB afterglows allow us to evaluate the optical depth of the host ISM, according to the neutral hydrogen column density N(HI) observed along the sightlines toward the star-forming regions where the GRBs are found. Different from previous effort in searching for faint, transmitted Lyman continuum photons, our method is not subject to background subtraction uncertainties and does not require prior knowledge of either the spectral shape of the host galaxy population or the IGM Lya forest absorption along these GRB sightlines. Because most GRBs occur in sub-L_* galaxies, our study also offers the first constraint on fesc for distant low-mass galaxies that dominate the cosmic luminosity density. We have compiled a sample of 27 GRBs at redshift z>2 for which the underlying N(HI) in the host ISM are known. These GRBs together offer a statistical sampling of the integrated optical depth to ionizing photons along random sightlines from star-forming regions in the host galaxies, and allow us to estimate the mean escape fraction averaged over different viewing angles. We find =0.02\pm 0.02 and place a 95% c.l. upper limit <= 0.075 for these hosts. We discuss possible biases of our approach and implications of the result. Finally, we propose to extend this technique for measuring at z~0.2 using spectra of core-collapse supernovae.Comment: Five journal pages, including one figure; ApJL in pres

Worker Training in a Restructuring Economy: Evidence from the Russian Transition

We use 1994-1998 data from the Russian Longitudinal Monitoring Survey (RLMS) to measure the incidence and determinants of several types of worker training and to estimate the effects of training on workers' interindustry, interfirm, and occupational mobility, their labor force transitions, and their wage growth in Russia compared to the U.S. We hypothesize that the shock of economic liberalization in Russia may raise the benefits of training, particularly retraining for new jobs, but uncertainty concerning the revaluation of skills may raise the costs, with an overall ambiguous effect on the amount of training undertaken. The RLMS indicates a lower rate of formal training than studies have found for the U.S., suggesting that the second effect dominates. Previous schooling is estimated to affect the probability of training positively, but the relationship is much stronger for additional training in the same field than for retraining for new fields, consistent with the hypothesis that schooling and training are complementary but become more substitutable in a restructuring environment. Foreign ownership of the firm also positively affects the probability of undertaking training, providing evidence of active restructuring by foreigner investors. Additional training in workers' current fields is estimated to reduce mobility and earnings, suggesting inertial programs from the pre-transition era. Retraining in new fields increases all types of worker mobility and has higher returns than those typically observed for training in the U.S., but it also raises the variance of earnings and the probability of employment, consistent with a search view of such retraining. Given the large returns to retraining, the efforts of Russian workers to learn new skills may increase as uncertainty is resolved and restructuring proceeds.training, retraining, on-the-job training, mobility, labor market, transition

Harmonic coordinate method for simulating generic singularities

This paper presents both a numerical method for general relativity and an application of that method. The method involves the use of harmonic coordinates in a 3+1 code to evolve the Einstein equations with scalar field matter. In such coordinates, the terms in Einstein's equations with the highest number of derivatives take a form similar to that of the wave equation. The application is an exploration of the generic approach to the singularity for this type of matter. The preliminary results indicate that the dynamics as one approaches the singularity is locally the dynamics of the Kasner spacetimes.Comment: 5 pages, 4 figures, Revtex, discussion expanded, references adde

Snowmass 2001: Jet Energy Flow Project

Conventional cone jet algorithms arose from heuristic considerations of LO hard scattering coupled to independent showering. These algorithms implicitly assume that the final states of individual events can be mapped onto a unique set of jets that are in turn associated with a unique set of underlying hard scattering partons. Thus each final state hadron is assigned to a unique underlying parton. The Jet Energy Flow (JEF) analysis described here does not make such assumptions. The final states of individual events are instead described in terms of flow distributions of hadronic energy. Quantities of physical interest are constructed from the energy flow distribution summed over all events. The resulting analysis is less sensitive to higher order perturbative corrections and the impact of showering and hadronization than the standard cone algorithms.Comment: REVTeX4, 13 pages, 6 figures; Contribution to the P5 Working Group on QCD and Strong Interactions at Snowmass 200

Finding the way forward for forensic science in the US:a commentary on the PCAST report

A recent report by the US President’s Council of Advisors on Science and Technology (PCAST) [1] has made a number of recommendations for the future development of forensic science. Whereas we all agree that there is much need for change, we find that the PCAST report recommendations are founded on serious misunderstandings. We explain the traditional forensic paradigms of match and identification and the more recent foundation of the logical approach to evidence evaluation. This forms the groundwork for exposing many sources of confusion in the PCAST report. We explain how the notion of treating the scientist as a black box and the assignment of evidential weight through error rates is overly restrictive and misconceived. Our own view sees inferential logic, the development of calibrated knowledge and understanding of scientists as the core of the advance of the profession

Cities in fiction: Perambulations with John Berger

This paper explores selected novels by John Berger in which cities play a central role. These cities are places, partially real and partially imagined, where memory, hope, and despair intersect. My reading of the novels enables me to trace important themes in recent discourses on the nature of contemporary capitalism, including notions of resistance and universality. I also show how Berger?s work points to a writing that can break free from the curious capacity of capitalism to absorb and feed of its critique

Berry phase in graphene: a semiclassical perspective

We derive a semiclassical expression for the Green's function in graphene, in which the presence of a semiclassical phase is made apparent. The relationship between this semiclassical phase and the adiabatic Berry phase, usually referred to in this context, is discussed. These phases coincide for the perfectly linear Dirac dispersion relation. They differ however when a gap is opened at the Dirac point. We furthermore present several applications of our semiclassical formalism. In particular we provide, for various configurations, a semiclassical derivation of the electron's Landau levels, illustrating the role of the semiclassical ``Berry-like'' phas

Analysis Of Measured Transport Properties Of Domain Walls In Magnetic Nanowires And Films

Existing data for soft magnetic materials of critical current for domain-wall motion, wall speed driven by a magnetic field, and wall electrical resistance, show that all three observable properties are related through a single parameter: the wall mobility $\mu$. The reciprocal of $\mu$ represents the strength of viscous friction between domain wall and conduction-electron gas. And $\mu$ is a function of the wall width, which depends in turn on the aspect ratio t/w, where t and w are the thickness and width of the sample. Over four orders of magnitude of $\mu$, the data for nanowires show $\mu\propto (t/w)^{-2.2}$. This dependence is in approximate agreement with the prediction of the 1984 Berger theory based on s-d exchange. On the other hand, it is inconsistent with the prediction of the 2004 Tatara and Kohno theory, and of the 2004 Zhang and Li theory.Comment: 7 pages, 1 figure; submitted to Phys. Rev.