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Microeconometrics researchers have increasingly realized the essential need to account for any within-group dependence in estimating standard errors of regression parameter estimates. The typical preferred solution is to calculate cluster-robust or sandwich standard errors that permit quite general heteroskedasticity and within-cluster error correlation,(More)
Any opinions expressed here are those of the author(s) and not those of the institute. Research disseminated by IZA may include views on policy, but the institute itself takes no institutional policy positions. The Institute for the Study of Labor (IZA) in Bonn is a local and virtual international research center and a place of communication between(More)
A silicon-based device, dubbed a microphysiometer, can be used to detect and monitor the response of cells to a variety of chemical substances, especially ligands for specific plasma membrane receptors. The microphysiometer measures the rate of proton excretion from 10(4) to 10(6) cells. This article gives an overview of experiments currently being carried(More)
A series of influential papers by Christopher J. Ruhm (2000, 2003, 2005, 2008) documents that recessions are “good for your health”—or, more specifically, that state-level mortality rates are strongly procyclical. The magnitude of the correlation is economically meaningful: a typical estimate from the literature suggests that a 1 percentage point increase(More)
The causal links between health and economic resources have long concerned social scientists. We use four waves of data from the Panel Study of Income Dynamics (PSID) to analyze the impact of wealth upon an individual's health status. The difficulty in approaching this task that has bedeviled previous studies is that wealth may be endogenous; a priori, it(More)
This study considers sibling differences in child labor in Nepal. The data are consistent with a model where parents care equally for all children but siblings differ in comparative advantage in household production, although parental preferences and credit constraints could also be important. Girls, especially older girls, tend to work more than their(More)
This selective review of the biological effects of ultrasound presents a synopsis of our current understanding of how cells insonated in vitro are affected by inertial cavitation from the standpoint of physical and chemical mechanisms. The focus of this review is on the physical and chemical mechanisms of action of inertial cavitation which appear to be(More)
OBJECTIVE The purpose of this report is to analyze factors affecting morbidity and mortality after pneumonectomy for malignant disease. METHODS We retrospectively reviewed the cases of all patients who underwent pneumonectomy for malignancy at the Mayo Clinic. Between January 1, 1985, and September 30, 1998, 639 patients (469 men and 170 women) were(More)
A study was carried out to determine possible effects of 60-Hz electromagnetic-field exposure on pineal gland function in humans. Overnight excretion of urinary 6-hydroxymelatonin sulfate (6-OHMS), a stable urinary metabolite of the pineal hormone melatonin, was used to assess pineal gland function in 42 volunteers who used standard (conventional) or(More)