DOES AFFIRMATIVE ACTION AFFECT PRODUCTIVITY IN THE INDIAN RAILWAYS?

Our objective in this paper is to shed some empirical light on a claim often made by critics of affirmative action policies: that increasing the representation of members of marginalized communities in jobs – and especially in relatively skilled positions – comes at a cost of reduced efficiency. We undertake a systematic empirical analysis of productivity in the Indian Railways in order to determine whether increasing proportions of Scheduled Castes and Scheduled Tribes in railway employment – largely a consequence of India's affirmative action policies – have actually reduced productive efficiency in the railway system. We find no evidence that higher percentages of Scheduled Castes and Scheduled Tribes in the railway labour force have reduced productivity. Indeed, some of our results suggest that the opposite is true, providing tentative support for the claim that greater labour force diversity boosts productivity.affirmative action; labour force; productivity; Indian railways

Heart and Minds: A Social Model of U.S. Productivity Growth

macroeconomics, product growth

"Economics in Context: The Need for a New Textbook"

economics education, textbooks, economic theory

New X-ray observations of the Geminga pulsar wind nebula

Previous observations of the middle-aged pulsar Geminga with XMM-Newton and Chandra have shown an unusual pulsar wind nebula (PWN), with a 20" long central (axial) tail directed opposite to the pulsar's proper motion and two 2' long, bent lateral (outer) tails. Here we report on a deeper (78 ks) Chandra observation and a few additional XMM-Newton observations of the Geminga PWN. The new Chandra observation has shown that the axial tail, which includes up to three brighter blobs, extends at least 50" (i.e., 0.06 d_{250} pc) from the pulsar. It also allowed us to image the patchy outer tails and the emission in the immediate vicinity of the pulsar with high resolution. The PWN luminosity, L_{0.3-8 keV} ~ 3\times 10^{29} d_{250}^2 erg/s, is lower than the pulsar's magnetospheric luminosity by a factor of 10. The spectra of the PWN elements are rather hard (photon index ~ 1). Comparing the two Chandra images, we found evidence of PWN variability, including possible motion of the blobs along the axial tail. The X-ray PWN is the synchrotron radiation from relativistic particles of the pulsar wind; its morphology is connected with the supersonic motion of Geminga. We speculate that the outer tails are either (1) a sky projection of the limb-brightened boundary of a shell formed in the region of contact discontinuity, where the wind bulk flow is decelerated by shear instability, or (2) polar outflows from the pulsar bent by the ram pressure from the ISM. In the former case, the axial tail may be a jet emanating along the pulsar's spin axis, perhaps aligned with the direction of motion. In the latter case, the axial tail may be the shocked pulsar wind collimated by the ram pressure.Comment: 16 pages, including 6 figures; minor changes in the text; typos corrected; published in Ap

Chandra Phase-Resolved X-ray Spectroscopy of the Crab Pulsar II

We present a new study of the X-ray spectral properties of the Crab Pulsar. The superb angular resolution of the Chandra X-ray Observatory enables distinguishing the pulsar from the surrounding nebulosity. Analysis of the spectrum as a function of pulse phase allows the least-biased measure of interstellar X-ray extinction due primarily to photoelectric absorption and secondarily to scattering by dust grains in the direction of the Crab Nebula. We modify previous findings that the line-of-sight to the Crab is under-abundant in oxygen and provide measurements with improved accuracy and less bias. Using the abundances and cross sections from Wilms, Allen & McCray (2000) we find [O/H] = $(5.28 \pm 0.28)\times10^{-4}$ ($4.9 \times10^{-4}$ is solar abundance). We also measure for the first time the impact of scattering of flux out of the image by interstellar grains. We find $\tau_{\rm scat} = 0.147 \pm 0.043$. Analysis of the spectrum as a function of pulse phase also measures the X-ray spectral index even at pulse minimum --- albeit with increasing statistical uncertainty. The spectral variations are, by and large, consistent with a sinusoidal variation. The only significant variation from the sinusoid occurs over the same phase range as some rather abrupt behavior in the optical polarization magnitude and position angle. We compare these spectral variations to those observed in Gamma-rays and conclude that our measurements are both a challenge and a guide to future modeling and will thus eventually help us understand pair cascade processes in pulsar magnetospheres. The data were also used to set new, and less biased, upper limits to the surface temperature of the neutron star for different models of the neutron star atmosphere.Comment: 32 pages, 6 figures submitted to the Astrophysical journa

Coulombic Energy Transfer and Triple Ionization in Clusters

Using neon and its dimer as a specific example, it is shown that excited Auger decay channels that are electronically stable in the isolated monomer can relax in a cluster by electron emission. The decay mechanism, leading to the formation of a tricationic cluster, is based on an efficient energy-transfer process from the excited, dicationic monomer to a neighbor. The decay is ultrafast and expected to be relevant to numerous physical phenomena involving core holes in clusters and other forms of spatially extended atomic and molecular matter.Comment: 5 pages, 1 figure, to be published in PR

The relevance of the Chinese experience for third world economic development

If the ten elements of Chinese development strategy discussed earlier are to provide object lessons relevant for other third world nations, they must be potentially transferable to other societies. The extent to which each element of the strategy is transferable depends on the conditions under which it can be successfully implemented, and on the degree to which these conditions are satisfied in other third world nations. I had also sought to determine what political-economic, geographical, and historical conditions are required for the successful implementation of each of the ten elements of strategy. The results of this analysis are summarized in the form of a matrix in Table 1. Each of the ten elements of strategy under discussion requires at least one - and often many more - of the major features of China's political-economic system. In all cases an effective and extensive system of public administration and/or a massoriented class structure are required, and in most cases a considerable degree of public ownership of the means of production and administrative control of resource allocation is either necessary or helpful. Less often required, but crucial in a few cases, are a central government with the power to mobilize resources on a large scale, a political leadership capable of influencing and involving people on a wide scale, and a ruraloriented class structure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43659/1/11186_2004_Article_BF00207280.pd

Effective action for Dirac fields in a constant electromagnetic background

We obtain, through zeta function methods, the one-loop effective action for massive Dirac fields in the presence of a uniform, but otherwise general, electromagnetic background. We show the agreement of our result with previous ones, concerning particular limit cases