The observable light deflection angle

The physical deflection angle of a light ray propagating in a space-time supplied with an asymptotically flat metric has to be expressed in terms of the impact parameter.Comment: 11 pages, 1 figur

Markets for Reputation: Evidence on Quality and Quantity in Academe

We develop a theory of the market for individual reputation, an indicator of regard by one’s peers and others. The central questions are: 1) Does the quantity of exposures raise reputation independent of their quality? and 2) Assuming that overall quality matters for reputation, does the quality of an individual’s most important exposure have an extra effect on reputation? Using evidence for academic economists, we find that, conditional on its impact, the quantity of output has no or even a negative effect on each of a number of proxies for reputation, and very little evidence that a scholar's most influential work provides any extra enhancement of reputation. Quality ranking matters more than absolute quality. Data on mobility and salaries show, on the contrary, substantial positive effects of quantity, independent of quality. We test various explanations for the differences between the determinants of reputation and salary.mobility, quality/quantity trade-off, salary determination

Two-Sided Learning, Labor Turnover and Displacement

We construct a general dynamic structural model of two-sided learning between a firm and its workers. We estimate an empirical version of the model using personnel data from Fokker Aircraft that cover the path of layoffs and quits through its bankruptcy. We find that the firm learns about its workers' loyalty (demonstrating the role of information in repeated cooperative principal-agent relationships). There is no evidence that workers learn (consistent with earlier empirical results on American workers). The type of data that we use also generates information on the value of learning and on whether and how the characteristics of workers who remain until the firm's death differ from those of all affected workers. It thus allows us to measure the increases in the firm's value from learning about its workers' behavior and to infer the extent of biases in estimated losses from displacement from samples restricted to displaced workers.

Evidence for Helical Edge Modes in Inverted InAs/GaSb Quantum Wells

We present an experimental study of low temperature electronic transport in the hybridization gap of inverted InAs/GaSb composite quantum wells. Electrostatic gate is used to push the Fermi level into the gap regime, where the conductance as a function of sample length and width is measured. Our analysis shows strong evidence for the existence of helical edge modes proposed by Liu et al [Phys. Rev. Lett., 100, 236601 (2008)]. Edge modes persist inspite of sizable bulk conduction and show only a weak magnetic field dependence - a direct consequence of gap opening away from zone center.Comment: 4 pages, 4 figure

Simulating quantum effects of cosmological expansion using a static ion trap

We propose a new experimental testbed that uses ions in the collective ground state of a static trap for studying the analog of quantum-field effects in cosmological spacetimes, including the Gibbons-Hawking effect for a single detector in de Sitter spacetime, as well as the possibility of modeling inflationary structure formation and the entanglement signature of de Sitter spacetime. To date, proposals for using trapped ions in analog gravity experiments have simulated the effect of gravity on the field modes by directly manipulating the ions' motion. In contrast, by associating laboratory time with conformal time in the simulated universe, we can encode the full effect of curvature in the modulation of the laser used to couple the ions' vibrational motion and electronic states. This model simplifies the experimental requirements for modeling the analog of an expanding universe using trapped ions and enlarges the validity of the ion-trap analogy to a wide range of interesting cases.Comment: (v2) revisions based on referee comments, figure added for clarity; (v1) 17 pages, no figure

Finite Conductivity in Mesoscopic Hall Bars of Inverted InAs/GaSb Quantum Wells

We have studied experimentally the low temperature conductivity of mesoscopic size InAs/GaSb quantum well Hall bar devices in the inverted regime. Using a pair of electrostatic gates we were able to move the Fermi level into the electron-hole hybridization state, and observe a mini gap. Temperature dependence of the conductivity in the gap shows residual conductivity, which can be consistently explained by the contributions from the free as well as the hybridized carriers in the presence of impurity scattering, as proposed by Naveh and Laikhtman [Euro. Phys. Lett., 55, 545-551 (2001)]. Experimental implications for the stability of proposed helical edge states will be discussed.Comment: 5 pages, 4 figure

Has foreign bank entry led to sounder banks in Latin America?

Policymakers continue to debate the merits of opening emerging market financial sectors to foreign ownership. A comparison of the 1995-2000 performance of foreign and domestic banks in select Latin American countries reveals that while foreign banks differed little from their domestic counterparts in overall financial condition, they showed more robust loan growth, a more aggressive response to asset quality deterioration, and a greater ability to absorb losses_characteristics that could help to strengthen the financial systems of their host countries.Banks and banking - Latin America ; Banks and banking, Foreign ; Economic development - Latin America