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We present new evidence on the evolution of black–white earnings differences among all men, including both workers and nonworkers. We study two measures: (i) the level earnings gap—the racial earnings difference at a given quantile; and (ii) the earnings rank gap—the difference between a black man’s percentile in the black earnings distribution and the position he would hold in the white earnings distribution. After narrowing from 1940 to the mid-1970s, the median black–white level earnings gap has since grown as large as it was in 1950. At the same time, the median black man’s relative position in the earnings distribution has remained essentially constant since 1940, so that the improvement then worsening of median relative earnings have come mainly from the stretching and narrowing of the overall earnings distribution. Black men at higher percentiles have experienced significant advances in relative earnings since 1940, due mainly to strong positional gains among those with college educations. Large relative schooling gains by blacks at the median and below have been more than counteracted by rising return to skill in the labor market, which has increasingly penalized remaining racial differences in schooling at the bottom of the distribution.

Engineering broadband light absorbers is crucial to many applications, including energy-harvesting devices and optical interconnects. The performances of an ideal absorber are that of a black body, a dark material that absorbs radiation at all angles and polarizations. Despite advances in micrometre-thick films, the absorbers available to date are still far from an ideal black body. Here, we describe a disordered nanostructured material that shows an almost ideal black-body absorption of 98–99% between 400 and 1,400 nm that is insensitive to the angle and polarization of the incident light. The material comprises nanoparticles composed of a nanorod with a nanosphere of 30 nm diameter attached. When diluted into liquids, a small concentration of nanoparticles absorbs on average 26% more than carbon nanotubes, the darkest material available to date. By pumping a dye optical amplifier with nanosecond pulses of ∼100 mW power, we harness the structural darkness of the material and create a new type of light source, which generates monochromatic emission (∼5 nm wide) without the need for any resonance. This is achieved through the dynamics of light condensation in which all absorbed electromagnetic energy spontaneously generates single-colour energy pulses. Nanoparticles can absorb most of the incoming light irrespective of incidence angle and polarization and condense it into a monochromatic emission in the presence of a dye.

Using IPUMS data for five decennial years between 1970 and 2010, we delineate and compare the trends and sources of the racial pay gap among men and women in the U.S. labor force. Decomposition of the pay gap into components underscores the significance of the intersection between gender and race; we find meaningful gender differences in the composition of the gap and in the gross and the net earnings gaps—both are much larger among men than among women. Despite these differences, the over-time trend is strikingly similar for both genders. Racial gaps sharply declined between 1970 and 1980 and continued to decline, but at a slower rate, until 2000. However, at the turn of the millennium, the trend reversed for both gender groups. The growth of the racial pay gap at the turn of the millennium is attributable to the increase in overall income inequality, stagnation in occupational segregation, and an increase in the unexplained portion of the gap, a portion we attribute to economic discrimination.

Phase-transition materials provide exciting opportunities for controlling optical properties of photonic devices dynamically. Here, we systematically investigate the infrared emission from a thin film of vanadium dioxide (VO 2 ). We experimentally demonstrate that such thin films are promising candidates to tune and control the thermal radiation of an underlying hot body with different emissivity features. In particular, we studied two different heat sources with completely different emissivity features, i.e. a black body-like and a mirror-like heated body. The infrared emission characteristics were investigated in the 3.5–5.1 μm spectral range using the infrared thermography technique which included heating the sample, and then cooling back. Experimental results were theoretically analyzed by modelling the VO 2 film as a metamaterial for a temperature range close to its critical temperature. Our systematic study reveals that VO 2 thin films with just one layer 80 nm thick has the potential to develop completely different dynamic tuning of infrared radiation, enabling both black-body emission suppression and as well as mirror emissivity boosting, in the same single layer device. Understanding the dynamics and effects of thermal tuning on infrared emission will benefit wide range of infrared technologies including thermal emitters, sensors, active IR filters and detectors.

In this work, we have considered a n -dimensional Schwarzschild–Tangherlini black hole spacetime with massless minimally coupled free scalar fields in its bulk and 3-brane. The bulk scalar field equation is separable using the higher dimensional spherical harmonics on ( n - 2 ) -sphere. First, using the Hamiltonian formulation with the help of the recently introduced near-null coordinates we have obtained the expected temperature of the Hawking effect, identical for both bulk and brane localized scalar fields. Second, it is known that the spectrum of the Hawking effect as seen at asymptotic future does not correspond to a perfect black body and it is properly represented by a greybody distribution. We have calculated the bounds on this greybody factor for the scalar field in both bulk and 3-brane. Furthermore, we have reaffirmed that these bounds predict a decrease in the greybody factor as the spacetime dimensionality n increases and also reaffirmed that for a large number of extra dimensions the Hawking quanta is mostly emitted in the brane.

The aim of this paper is to study the quantum tunneling process for charged vector particles through the horizons of more generalized black holes by using the Proca equation. For this purpose, we consider a pair of charged accelerating and rotating black holes with Newman–Unti–Tamburino parameter and a black hole in 5D gauged super-gravity theory, respectively. Further, we study the tunneling probability and corresponding Hawking temperature for both black holes by using the WKB approximation. We find that our analysis is independent of the particles species whether or not the background black hole geometries are more generalized.

Decades of racial progress have led some researchers and policymakers to doubt that discrimination remains an important cause of economic inequality. To study contemporary discrimination, we conducted a field experiment in the low-wage labor market of New York City, recruiting white, black, and Latino job applicants who were matched on demographic characteristics and interpersonal skills. These applicants were given equivalent résumés and sent to apply in tandem for hundreds of entry-level jobs. Our results show that black applicants were half as likely as equally qualified whites to receive a callback or job offer. In fact, black and Latino applicants with clean backgrounds fared no better than white applicants just released from prison. Additional qualitative evidence from our applicants' experiences further illustrates the multiple points at which employment trajectories can be deflected by various forms of racial bias. These results point to the subtle yet systematic forms of discrimination that continue to shape employment opportunities for low-wage workers.

Here, we demonstrate that the power spectral density of thermal radiation at a specific wavelength produced by a body of finite dimensions set up in free space under a fixed temperature could be made theoretically arbitrary high, if one could realize double negative metamaterials with arbitrary small loss and arbitrary high absolute values of permittivity and permeability (at a given frequency). This result refutes the widespread belief that Planck's law itself sets a hard upper limit on the spectral density of power emitted by a finite macroscopic body whose size is much greater than the wavelength. Here we propose a physical realization of a metamaterial emitter whose spectral emissivity can be greater than that of the ideal black body under the same conditions. Due to the reciprocity between the heat emission and absorption processes such cooled down superemitter also acts as an optimal sink for the thermal radiation-the 'thermal black hole'-which outperforms Kirchhoff-Planck's black body which can absorb only the rays directly incident on its surface. The results may open a possibility to realize narrowband super-Planckian thermal radiators and absorbers for future thermo-photovoltaic systems and other devices.

By allowing for an extensive margin in the standard quantity-quality model, we generate new insights into fertility transitions. We test the model on Southern black women affected by a large-scale school construction program. Consistent with our model, women facing improved schooling opportunities for their children were more likely to have at least one child but chose to have smaller families overall. By contrast, women who themselves obtained more schooling due to the program delayed childbearing along both the extensive and intensive margins and entered higher quality occupations, consistent with education raising opportunity costs of child rearing.