Ionization chambers often exhibit a stem effect, caused by interactions of radiation with air near the chamber end, or with dielectric in the chamber stem or cable. These interactions contribute to the apparent measured exposure. To determine the stem efffect for several common ionization chamber systems, exposures were measured with TLD capsules placed at the center of 60Co fields of various sizes. These exposure measurements then were repeated with various ionization chamber systems, including two Victoreen R meters (25- and 100-R chambers), a Capintec 192 dosimeter with a Farmer 0.6-cm3 probe, a PTW transit dose probe, and an EG and G IC-18 probe with a Keithley 610-B electrometer. From a comparison of TLD and ionization chamber measurements of the variation in exposure rate with field size, stem corrections for the different systems were determined within 1%.

Cobalt Radioisotopes↗

PubMedDate not supplied

The Vietnam Era Twin Registry: a resource for medical research.

The Vietnam Era Twin Registry consists of 4,774 male-male twin pairs born between 1939 and 1957 with both brothers having served in the United States military during the Vietnam War. The registry was originally developed to provide the best control group for Vietnam-exposed servicemen to study the long-term health consequences of service in Vietnam. Recognizing the potential value of the registry for other areas of medical research, the Department of Veterans Affairs in 1988 opened the registry for use by both VA and non-VA investigators. The existence of centralized VA data bases for deaths and VA hospitalizations will strengthen future followup of the twins. This article describes the characteristics of the registry population and the process for accessing the registry.

Adult↗

PubMedDate not supplied

Voice therapy for vocal nodules and vocal polyps.

Explore the source record for details and available documents.

Adult↗

PubMedDate not supplied

Breastfeeders versus bottlefeeders: differences in femininity perceptions.

Fifty-eight primiparous women were studied to explore perceived differences in femininity between women who chose to breastfeed and women who chose to bottlefeed. A demographic questionnaire and a sex role inventory were administered to the sample. Although breast and bottlefeeders did not differ significantly in their perceived levels of femininity, analysis of the data revealed that women who had no clear cut sense of identity were more likely to bottlefeed.

Adult↗