Supertubes in Field Theories

To a domain wall or string object, Noether charge and topological spatial objects can be attracted, forming a composite BPS (Bogomolny-Prasad-Sommerfield) object. We consider two field theories and derive a new BPS bound on composite linear solitons involving multiple charges. Among the BPS objects `supertubes' appear when the wall or string tension is canceled by the bound energy, and could take an arbitrary closed curve. In our theories, supertubes manifest as Chern-Simons solitons, dyonic instantons, charged semi-local vortices, and dyonic instantons on vortex flux sheet.Comment: latex, 10 page

Multivariate Decomposition for Hazard Rate Models

We develop a regression decomposition technique for hazard rate models, where the difference in observed rates is decomposed into components attributable to group differences in characteristics and group differences in effects. The baseline hazard is specified using a piecewise constant exponential model, which leads to convenient estimation based on a Poisson regression model fit to person-period, or split-episode data. This specification allows for a flexible representation of the baseline hazard and provides a straightforward way to introduce time-varying covariates and time-varying effects. We provide computational details underlying the method and apply the technique to the decomposition of the black-white difference in first premarital birth rates into components reflecting characteristics and effect contributions of several predictors, as well as the effect contribution attributable to race differences in the baseline hazard.Poisson regression, hazard rates, decomposition, piecewise constant exponential model

The In-Hospital Mortality Rates of Slaves and Freemen: Evidence from Touro Infirmary, New Orleans, Louisiana, 1855–1860

Using a rich sample of admission records from New Orleans Touro Infirmary, we examine the in-hospital mortality risk of free and enslaved patients. Despite a higher mortality rate in the general population, slaves were significantly less likely to die in the hospital than the whites. We analyze the determinants of in-hospital mortality at Touro using Oaxaca-type decomposition to aggregate our regression results. After controlling for differences in characteristics and maladies, we find that much of the mortality gap remains unexplained. In conclusion, we propose an alternative explanation for the mortality gap based on the selective hospital admission of slaves.hospital, slavery, Oaxaca-type decomposition, New Orleans, Touro

Racial and Ethnic Disparities in the Use of Drug Therapy

The purpose of this research is to explain the variation in the utilization of drug therapy for the medical conditions of depression, high cholesterol, and hypertension between Hispanics, non-Hispanic blacks, and non-Hispanics whites using Oaxaca-type decomposition analysis based on logit estimates. We find that almost the entire share of the utilization differences in drug therapy between blacks and whites can be explained by the differences in the coefficients of observable characteristics, while the sources of the utilization difference between the whites and Hispanics are split between the differences in the observable characteristics and the coefficient estimates. This result implies that strategies to improve racial and ethnic disparities need to be tailored to each group by focusing on the specific factors that are attributed to causing the disparity.high cholesterol, depression, drug therapy, racial and ethnic disparities, hypertension, Oaxaca decomposition

Changes in Korean Wage Inequality, 1980−2005

Korea is known not only for rapid economic growth but also relatively low wage inequality. It is one of the few countries in which wage inequality decreased during the 1980s, though in recent years wage inequality has increased. This paper studies what factors contributed to the changes in wage inequality during the last two decades. This paper implements a recently developed Oaxaca-type inequality decomposition method to decompose "U" shaped changes in inequality into characteristics (quantity), coefficients (price) and residuals effects at both overall and detailed levels. The results of decomposition analysis show that changes in the wage structure significantly contribute to the changes in wage inequality in Korea. The coefficients effect of human capital factors has played a major role not only in increasing wage inequality from mid-1990s, but also decreasing wage inequality in 1980s and early 1990s.decomposition analysis of inequality, earnings equation, coefficients (price) effect, characteristics (quantity) effect, residuals effect

The Relationship of the value of the Dollar, and the Prices of Gold and Oil: A Tale of Asset Risk

This paper investigates the relationship between the value of the dollar and the prices of two commodities, gold and oil. Granger causality is used on monthly data from January of 1970 through July of 2008. The empirical results show that the hypothesis that there is no causal relation between the value of the dollar and the prices of gold and oil is not supported by the evidence. There are causal relations between each of the prices, and there is a negative relation between the value of the dollar and the price of each of the commodities, as predicted by standard economic theory. Also consistent with the predictions of classical economic theory is that there is a positive statistical association between the prices of gold and oil. The implication is that gold and oil represent safe havens from fluctuations in the value of the dollar.Dollar, Gold, Oil, Exchange Rates, Commodity Prices, Granger Causality

Did the price control achieve its goal?

As a result of the 1973 oil embargo and the subsequent increase of world oil prices, the oil price control program took place in order to reduce the impact of sharply higher external oil prices. In this regard, since the domestic price for oil was below that of the world market, the price control effort seemed to be regarded as successful. Did the oil price control achieve its goal? Maybe not. This study shows that the price control for the domestically produced crude oil was ineffective and enhanced the ability of external suppliers to manipulate prices.Oil Price Price Control

Chaos in the segments from Korean traditional singing and western singing

We investigate the time series of the segments from a Korean traditional song ``Gwansanyungma'' and a western song ``La Mamma Morta'' using chaotic analysis techniques. It is found that the phase portrait in the reconstructed state space of the time series of the segment from the Korean traditional song has a more complex structure in comparison with the segment from the western songs. The segment from the Korean traditional song has the correlation dimension 4.4 and two positive Lyapunov exponents which show that the dynamic related to the Korean traditional song is a high dimensional hyperchaotic process. On the other hand, the segment from the western song with only one positive Lyapunov exponent and the correlation dimension 2.5 exhibits low dimensional chaotic behavior.Comment: 23 pages including 10 eps figures, latex, to appear in J. Acoust. Soc. A