59,381 research outputs found
"Employment Effects of the 2009 Minimum Wage Increase: Evidence from State Comparisons of At-Risk Workers"
In July, 2009, the U.S. Federal minimum wage was increased from 7.25. Individuals in some states were unaffected by this increase, since the state minimum wage already exceeded $7.25 and the state minimum was not increased further. We use this variation, as well as variation in the actual amount of the increase, to make comparisons of the employment of “at-risk” workers across states with their peers and within states with workers arguably unaffected by the increase. Our data come from the 2009 CPS, four and five months before and after the increase. We find some evidence that the employment of some at-risk demographic groups declined as a result of the minimum wage increase, but the impacts are not statistically significant. We also find that the employment changes were not responsive to the actual amount of the increase.minimum wage
"Employment Effects of the 2009 Minimum Wage Increase: Evidence from State Comparisons of At-Risk Workers (Revised Version)"
In July, 2009, the U.S. Federal minimum wage was increased from 7.25. Individuals in some states were unaffected by this increase, since the state minimum wage already exceeded $7.25. We use this variation to make comparisons of the employment of “at-risk” workers with their peers across states and with workers within states who were arguably unaffected by the increase. Our data come from the 2009 CPS, four and five months before and after the increase. We find little evidence of negative employment effects for teens or less- educated adults, but some stronger evidence of a negative effect for young adults with a high school degree or less. Control for demographic characteristics reduces the size and significance of the estimated effects.Minimum Wage
Micromagnetic Simulations of Ferromagnetic Rings
Thin nanomagnetic rings have generated interest for fundamental studies of
magnetization reversal and also for their potential in various applications,
particularly as magnetic memories. They are a rare example of a geometry in
which an analytical solution for the rate of thermally induced magnetic
reversal has been determined, in an approximation whose errors can be estimated
and bounded. In this work, numerical simulations of soft ferromagnetic rings
are used to explore aspects of the analytical solution. The evolution of the
energy near the transition states confirms that, consistent with analytical
predictions, thermally induced magnetization reversal can have one of two
intermediate states: either constant or soliton-like saddle configurations,
depending on ring size and externally applied magnetic field. The results
confirm analytical predictions of a transition in thermally activated reversal
behavior as magnetic field is varied at constant ring size. Simulations also
show that the analytic one dimensional model continues to hold even for wide
rings
Participation in college sports and protection from sexual victimization
Some sociologists have argued that sport is a male-dominated institution and sexist culture in which female athletes experience various forms of discrimination, including sexual harassment from coaches and male athletes. Some research does indicate that female athletes suffer higher rates of sexual victimization from authority figures in sport than their nonathletic counterparts in education and the workplace. In contrast, researchers have also speculated that athletic participation can protect female athletes from sexual victimization through a variety of social-psychological mechanisms such as team membership, physical strength, and self-confidence. This paper reports on the first descriptive analysis to test the “sport protection hypothesis” among both female and male athletes, using cross-tabulation secondary analyses of data from the National College Health Risk Behavior Survey, conducted in 1995 by the U.S. Centers for Disease Control and Prevention (N=4814). USA college students of traditional undergraduate age (aged 18-24) were included in the sample (N=2903). Some limited support for the protection hypothesis was found, and student athletes were significantly less likely to report sexual victimization during their late high school and early college years than their nonathletic counterparts. A gender gap in the pattern of sexual victimization also appeared between males and females across all student age groups, with females experiencing more sexual victimization than males. However, no significant gender gap was found among athletes. The results are discussed in relation to previous studies of campus athletes and to college prevention policy
Coupled-resonator-induced transparency with a squeezed vacuum
We present the first experimental observation of quantum fluctuation spectra
in two coupled optical cavities with an injected squeezed vacuum light. The
quadrature components of the reflected squeezed vacuum spectra are measured by
phase sensitive homodyne detector. The experimental results demonstrate
coupled-resonator-induced transparency in the quantum regime, in which
electromagnetically-induced-transparency-like characteristic of the absorption
and dispersion properties of the coupled optical cavities determines the
line-shape of the reflected quantum noise spectra.Comment: 4 pages, 4 figures, appear in Phys. Rev. Let
Assessing the critical material constraints on low carbon infrastructure transitions
We present an assessment method to analyze whether the disruption in supply of a group of materials endangers the transition to low-carbon infrastructure. We define criticality as the combination of the potential for supply disruption and the exposure of the system of interest to that disruption. Low-carbon energy depends on multiple technologies comprised of a multitude of materials of varying criticality. Our methodology allows us to assess the simultaneous potential for supply disruption of a range of materials. Generating a specific target level of low-carbon energy implies a dynamic roll-out of technology at a specific scale. Our approach is correspondingly dynamic, and monitors the change in criticality during the transition towards a low-carbon energy goal. It is thus not limited to the quantification of criticality of a particular material at a particular point in time. We apply our method to criticality in the proposed UK energy transition as a demonstration, with a focus on neodymium use in electric vehicles. Although we anticipate that the supply disruption of neodymium will decrease, our results show the criticality of low carbon energy generation increases, as a result of increasing exposure to neodymium-reliant technologies. We present a number of potential responses to reduce the criticality through a reduction in supply disruption potential of the exposure of the UK to that disruption
Dynamics of coherence, localization and excitation transfer in disordered nanorings
Self-assembled supramolecular aggregates are excellent candidates for the
design of efficient excitation transport devices. Both artificially prepared
and natural photosynthetic aggregates in plants and bacteria present an
important degree of disorder that is supposed to hinder excitation transport.
Besides, molecular excitations couple to nuclear motion affecting excitation
transport in a variety of ways. We present an exhaustive study of exciton
dynamics in disordered nanorings with long-range interactions under the
influence of a phonon bath and take the LH2 system of purple bacteria as a
model. Nuclear motion is explicitly taken into account by employing the Davydov
ansatz description of the polaron and quantum dynamics are obtained using a
time-dependent variational method. We reveal an optimal exciton-phonon coupling
that suppresses disorder-induced localization and facilitate excitation
de-trapping. This excitation transfer enhancement, mediated by environmental
phonons, is attributed to energy relaxation toward extended, low-energy
excitons provided by the precise LH2 geometry with anti-parallel dipoles and
long-range interactions. An analysis of localization and spectral statistics is
followed by dynamical measures of coherence and localization, transfer
efficiency and superradiance. Linear absorption, 2D photon-echo spectra and
diffusion measures of the exciton are examined to monitor the diffusive
behavior as a function of the strengths of disorder and exciton-phonon
coupling.Comment: 18 pages, 13 figure
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