Labor market transitions of young women over the early life course: A multistate life table analysis

Using detailed panel data on school, work, and family formation history of youth (i.e., NLSY 1979-1991), we examine the dynamic process of labor market transitions women make during young adulthood. Transitions between the states of the labor force (i.e., employment, unemployment, and out of the labor force) are analyzed using multistate life tables, in which labor market and family transitions are estimated simultaneously. The age-pattern, life-cycle variation, and racial differences in employment and nonemployment transitions are the main interests of this study. We find that black women in the aggregate are less likely to be employed (or in the labor force) and more likely to be nonemployed than white women during early adulthood (i.e., at ages 16-34). With first childbirth controlled, a higher proportion of black women than white women are in the labor force during the same period, as past studies have shown. But, we find that the proportion employed is actually lower among blacks than among whites because a higher proportion of blacks are unemployed. Even though the racial differential in employment decreases with age among women with more than a high school education, it persists among women with a high school education or less. By estimating the conditional probabilities of transitions between states of the labor force, this study shows that the major component of the racial differential in employment (or in nonemployment) is in the process of entering employment either from the unemployment or the out-of-the-labor-force state: black women, if in the labor force, are less likely to be employed and more likely to withdraw from the labor force, if unemployed, than their white counterparts. As a summary measure, our life table analysis shows that black women spend considerably more time nonemployed and less time employed than white women over the early life course.

Error Voltage Components in Quantitative Voltage Contrast Measurement Systems

This paper presents the results of computer simulation studies into the respective contributions of the potential barrier, the off-normal incidence injection of secondary electrons (SEs) into the retarding field and analyser geometry on Types I and II local field error voltages for a practical 20 mm wide planar retarding field energy analyser. Results show that the error voltage component due to the off-normal incidence injection effect of SEs into the retarding field dominates the Type I local field error. For type II LFE, the error voltage component due to analyser geometry effect is the higher contributing factor. The presence of a neighbouring electrode voltage tends to draw SEs away from the central axis of the energy analyser, thus causing the electron trajectories to be more sensitive to the influence of the analyser geometry

Dark Matter in Gauge Mediation from Emergent Supersymmetry

We investigated the viability of neutralino dark matter in the gauge mediation from emergent supersymmetry proposal. In this proposal, supersymmetry is broken at Planck scale and consequently, the gravitino is superheavy and completely decouples from the low energy theory. Squarks and sleptons obtain their soft masses dominantly through gauge mediation with other mechanisms highly suppressed. The lightest supersymmetric partner, in contrast to traditional gauge mediation, is a neutralino which is also a dark matter candidate. By explicit calculation of the low energy spectra, the parameter space was constrained using the WMAP observed relic density of dark matter, LEP2 Higgs mass bounds, collider bounds on supersymmetric partners and exotic B-meson decays. We found that the model has intriguing hybrid features such as a nearly gauge-mediated spectrum (the exception being the superheavy gravitino) but with a dominant mSUGRA-like bino-stau coannihilation channel and at large $\tan \beta$, A-resonance-like annihilation.Comment: 14 pages, 4 figure

Carrier de-smearing of photoluminescence images on silicon wafers using the continuity equation

Photoluminescence images of silicon wafers with non-uniform lifetime distribution are often smeared by lateral carrier diffusion. We propose a simple method to de-smear the photoluminescence images by applying the two-dimensional continuity equation. We demonstrate the method on simulated silicon wafers and measured photoluminescence-based lifetime image of multicrystalline silicon wafer. The de-smearing is very effective in recovering the actual lifetime for wafers with gradual changes in lifetime but is less effective around localised recombination centres with high contrast such as grain boundaries and dislocations. The method is sensitive to measurement noise; therefore, the implementation of suitable noise filtering is often critical.This work was supported by the Australian Research Council and the Australian Renewable Energy Agency

A Simulation Model for Electron Irradiation Induced Specimen Charging in a Scanning Electron Microscope

A numerical model has been formulated to simulate the dynamics of specimen charging in a scanning electron microscope. In this model, the electric field due to imposed boundary conditions and fixed charges is solved by the finite element method. The empirical electron yield data are stored in Universal Yield Curves (UYC) . These UYCs control the generation of secondary and backscattered electrons from various materials. The electrons emitted from electron-solid interactions are tracked using a leapfrog integration scheme. Excess charges generated on the surface of electrically floating solids are assigned to numerical grids using a linear charge redistribution scheme. The validity of the simulation model was verified by measurements in a special setup which consisted of several isolated electrodes in the SEM chamber. Excess currents generated inside each electrode due to electron irradiation were measured simultaneously. Measurements and simulation results are in broad agreement and show that electrically floating electrodes, not directly irradiated by the primary beam, can charge-up if they are irradiated by secondary electrons and backscattered electrons emitted from a nearby electrode. The polarity of charge generation on the electrically floating solid depends on its own material property, and also strongly on the potential distribution in the space surrounding the floating electrode

Underpriced Default Spread Exacerbates Market Crashes

In this paper, we develop a specific observable symptom of a banking system that underprices the default spread in non-recourse asset-backed lending. Using three different data sets for 18 countries and property types, we find that, following a negative demand shock, the “underpricing” economies experience far deeper asset market crashes than economies in which the put option is correctly priced. Furthermore, only one of the countries in our sample continues to exhibit the underpricing symptom following a market crash. This indicates that market crashes have a cleansing effect and eliminate underpricing at least for a period of time. This makes investing in such markets safer following a negative demand shock.real estate bubble, lender optimism, disaster myopia, Asian financial crisis

Underpriced Default Spread Exacerbates Market Crashes

In this paper, we develop a specific observable symptom of a banking system that underprices the default spread in non-recourse asset-backed lending. Using three different data sets for 18 countries and property types, we find that, following a negative demand shock, the underpricing economies experience far deeper asset market crashes than economies in which the put option is correctly priced. Furthermore, only one of the countries in our sample continues to exhibit the underpricing symptom following a market crash. This indicates that market crashes have a cleansing effect and eliminate underpricing at least for a period of time. This makes investing in such markets safer following a negative demand shock.real estate bubble, lender optimism, disaster myopia, Asian financial crisis

Minimal SUSY SO(10), b-τ\tau unification and large neutrino mixings

We show that the assumption of type II seesaw mechanism for small neutrino masses coupled with $b-\tau$ mass unification in a minimal SUSY SO(10) model leads not only to a natural understanding of large atmospheric mixing angle ($\theta_{23}$) among neutrinos, as recently pointed out, but also to large solar angle ($\theta_{12}$) and a small $\theta_{13}\equiv U_{e3}$ as required to fit observations. This is therefore a minimal, completely realistic grand unified model for all low energy observations that naturally explains the diverse mixing patterns between the quark and leptons without any additional inputs such as extra global symmetries. The proposed long baseline neutrino experiments will provide a crucial test of this model since it predicts $U_{e3}\simeq 0.16$ for the allowed range of parameters.Comment: 15 pages, latex, 3 figures, UMD-PP-03-03

Investigation of Dislocations in GaAs Using Cathodoluminescence in the Scanning Electron Microscope

Electrically active dislocations in Si-doped {100} GaAs substrates were observed using the cathodoluminescence (CL) technique in the scanning electron microscope (SEM). CL contrast profiles were experimentally obtained from the dislocations at different beam energies. Based on the CL model for localized defects in semiconductors developed earlier by Pey, the depths of the dislocations were found by locating the beam energy at which maximum CL contrast occurred. A preferential etching technique for {100} GaAs was employed to reveal the dislocations and to measure their depths. The etched depths obtained were compared to the predicted results from the theoretical model developed. The discrepancies in the results were attributed to a Cottrell atmosphere of point defects around the dislocation core

Cathodoluminescence Contrast of Localized Defects Part II. Defect Investigation

Cathodoluminescence contrast from defects with different geometrical and electronic properties have been studied using the numerical model developed in Part I. The contrast of a localized subsurface defect exhibits a maxima at a specific beam energy Emax which corresponds to the depth of the defect. The contrast of a dis-location which intersects the top surface perpendicularly is a decreasing function of beam energy. The differences in the image profiles of the two different kinds of defects allow the two types of imperfections to be distinguished. In addition, the resolution of a subsurface defect at beam energies lower than Emax is only a function of defect size and is insensitive to the defect strength. The defect depth, size and strength can therefore be extracted sequentially. The extension of the model to the investigation of complex or multiple defects such as dot and halo contrast is also illustrated