Race and ethnicity in housing: turnover in New York City, 1978-1987.

This study examines the patterns and predictors of housing turnovers among non-Hispanic whites, non-Hispanic blacks, Puerto Ricans, and other Hispanics in New York City during 1978-1987 to assess whether access to housing is distributed differentially by race and ethnicity. The data are taken from the triennial New York City Housing and Vacancy Survey. After controlling for household preferences, purchasing power, and quality characteristics of the housing unit, multinomial logistic regression results show the most consistent and significant predictors of turnover to be geographic and market-sector attributes. The findings suggest the presence of structural constraints in the housing market which effectively channel racial/ethnic groups to separate neighborhoods. The overall results are reminiscent of early studies of neighborhood transition by Duncan and Duncan (1957) and Taeuber and Taeuber (1965), and show that little progress has been made toward achieving equality in housing or informal social contact between racial/ethnic groups.

Effect of malathion on Bufo arenarum Hensel development--I. Esterase inhibition and recovery.

Newly fertilized Bufo arenarum Hensel embryos were exposed continuously or for a brief period (72-120 hr) to malathion (44 ppm) and then resuspended in amphibian Ringer's solution. Continuous exposure depressed acetylcholinesterase (EC 3.1.1.7), butyrylcholinesterase (EC 3.1.1.8) and carboxylesterase (EC 3.1.1.1) activities. The activities of the three enzymes in embryos treated for 72 hr recovered after a delay of 24 hr, but these enzymes showed different rates of recovery in embryos treated for 120 hr. Acrylamide disc electrophoresis showed several bands of esterase activity in control embryos. Continuous exposure to malathion abolished all esterase activity within 48 hr, but if the exposure continued new bands of esterase activity appeared at 120 hr of exposure. The zymograms of embryos exposed for 72 or 120 hr to malathion and then transferred to uncontaminated medium for 120 hr were similar to that of control embryos.