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The author examines the effect of rapid population growth due to migration on the parish of Tenango del Valle, Mexico, during the eighteenth century. She gives special consideration to the impact on quality of life in indigenous villages, especially for widows and female heads of households who were impoverished as a result of discriminatory land transactions. Data are mainly from the parish register for 1770.  相似文献   
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This study concerns the relationship between knowledge of drug culture and substance use. Results from a sample of 2,635 middle and high school students indicate that (1) knowledge of drug culture is positively correlated with substance use; (2) drug knowledge is more reliable and coherent in older youth; (3) drug knowledge is unrelated to other kinds of knowledge acquired in school; (4) youth exposed to peers' substance use in school have more drug knowledge; and (5) the earlier young people begin using drugs and alcohol, the more they know about the drug culture. Results suggest that knowledge of the drug culture may be an unobtrusive indicator of substance use problems.This project was made possible by a grant from the Tulsa Psychiatric Center, Tulsa, Oklahoma.Received Ph.D. from University of California at Berkeley in personality psychology. Research interests include school dropouts, substance use, delinquency, identity, narcissism, and health. To whom correspondence should be addressed.Received Ph.D. from University of California at Berkeley in personality psychology. Research interests include school dropouts, substance use, delinquency, personal commitments, identity, narcissism, and health.Received Ph.D. from University of California at Berkeley in personality psychology. Research interests include moral development and personality.  相似文献   
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Danger: implants     
The superheated debate over breast implants awakened a sleeping giant of an issue clouding "medical devices"--the government's clumsy nomenclature for any medical product that is not a drug, from breast implants and artificial hips to X-ray machines and surgical thread. Some 130 categories of high-risk devices are in use with little or no proof of safety, reliability or effectiveness. All appeared before 1976, the year that the Food and Drug Administration got the authority to regulate such products. Under activist chief David Kessler and with added clout from a 1990 law, the FDA plans to scrutinize the entire 130-item list. Five will get special attention starting early next year: saline-filled breast implants, inflatable penile implants, testicular implants, heart-bypass pumps and cranial stimulators. U.S. News has looked at all five devices, using FDA data obtained through the Freedom of Information Act. In-depth computer analysis suggested that penile implants deserve closer examination. Why is clear from the following report.  相似文献   
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