Durango apatite fission-track dating using length-based age corrections and neutron fluence measurements by natural thorium thin films and natural U-doped glasses calibrated through natural uranium thin films

In this work, we present an approach for neutron fluence measurements based on natural thorium thin films and natural uranium-doped glasses calibrated through natural uranium thin films to be used for dating with the Fission-Track Method (FTM). This neutron dosimetry approach allows the employment of FTM even when dating is carried out using low neutron themalization facilities. Besides, it makes possible the determination of the Th/U ratio of the mineral to be dated. Durango apatite which is often employed in FTM as an age standard was analyzed. This apatite presented a fairly high Th/U ratio, 29.9 +/- 1.7. Th fissions were 18%, 12% and 10% of the total for irradiations where thermal to fast neutron flux ratios were 2.4, 4.4 and 5,2, respectively. These results show that Th fission must be considered for this apatite, when not well-thermalized irradiation facilities are used. The ratio between spontaneous and induced track length, L(S)/L(1), close to 0.89, indicates a certain amount of rejuvenation of the age of Durango apatite. Therefore, its apparent age should be corrected, the application of a technique based on track-length measurements produced a corrected age of 29.7 +/- 1.1 Ma, consistent with the independent reference age of this apatite (31.4 +/- 0.5 Ma). This result represents a support for viability of the neutron dosimetry approach studied in this work for FTM.(C) 2002 Elsevier B.V. B.V. All rights reserved.

Uptake of regular chlamydia testing by U.S. women: a longitudinal study

Background Routine chlamydia screening is a recommended preventive intervention for sexually active women aged ≤25 years in the U.S. but rates of regular uptake are not known. Purpose This study aimed to examine rates of annual chlamydia testing and factors associated with repeat testing in a population of U.S. women. Methods Women aged 15–25 years at any time from January 1, 2002, to December 31, 2006 who were enrolled in 130 commercial health plans were included. Data relating to chlamydia tests were analyzed in 2009. Chlamydia testing rates (per 100 woman-years) by age and rates of repeated annual testing were estimated. Poisson regression was used to examine the effects of age and previous testing on further chlamydia testing within the observation period. Results In total, 2,632,365 women were included. The chlamydia testing rate over the whole study period was 13.6 per 100 woman years after adjusting for age-specific sexual activity; 8.5 (95% CI=6.0, 12.3) per 100 woman-years in those aged 15 years; and 17.7 (95% CI=17.1, 18.9) in those aged 25 years. Among women enrolled for the entire 5-year study period, 25.9% had at least one test but only 0.1% had a chlamydia test every year. Women tested more than once and older women were more likely to be tested again in the observation period. Conclusions The low rates of regular annual chlamydia testing do not comply with national recommendations and would not be expected to have a major impact on the control of chlamydia infection at the population level.

Intendedness of pregnancy among active duty women in the U.S. Army

Objective. The objective of this study was to determine the prevalence of unintended pregnancy and the association between social and demographic factors among a population of active duty women in the U.S. Army giving birth to viable infants at a U.S. Army hospital at Fort Hood, Texas. Prevalence of unintended pregnancy in this group was 50.9% (95% CI 44.0 to 57.9) with 36.3% being mistimed (95% CI 29.8 to 33.2) and 14.6% being unwanted (95% CI 10.2 to 20.1). A further 14.2% of the women experienced ambivalence (95% CI 9.8 to 19.6). ^ The study population was a cross-sectional group of active duty pregnant women who represent the target population of all female soldiers that deliver viable infants in the Army. Using a survey based on previous studies, intendedness of pregnancy at conception was retrospectively determined. Unintended births are further characterized as mistimed or unwanted. Demographic and other exposures were described bivariately. Associations were evaluated using measures of relative risk and chi-square analysis. ^ The results of the research indicate that in the study population, race/ethnicity is not associated with unintended pregnancy and non-commissioned officers had a lower rate of unintended pregnancy than other rank groupings. ^

Disparities in medical expenditure and utilization among hypertensive men and women in the U.S.: Cross-section and lifetime analysis

Objectives. To investigate procedural gender equity by assessing predisposing, enabling and need predictors of gender differences in annual medical expenditures and utilization among hypertensive individuals in the U.S. Also, to estimate and compare lifetime medical expenditures among hypertensive men and women in the U.S. ^ Data source. 2001-2004 the Medical Expenditure Panel Survey (MEPS);1986-2000 National Health Interview Survey (NHIS) and National Health Interview Survey linked to mortality in the National Death Index through 2002 (2002 NHIS-NDI). ^ Study design. We estimated total medical expenditure using four equations regression model, specific medical expenditures using two equations regression model and utilization using negative binomial regression model. Procedural equity was assessed by applying the Aday et al. theoretical framework. Expenditures were estimated in 2004 dollars. We estimated hypertension-attributable medical expenditure and utilization among men and women. ^ To estimate lifetime expenditures from ages 20 to 85+, we estimated medical expenditures with cross-sectional data and survival with prospective data. The four equations regression model were used to estimate average annual medical expenditures defined as sum of inpatient stay, emergency room visits, outpatient visits, office based visits, and prescription drugs expenditures. Life tables were used to estimate the distribution of life time medical expenditures for hypertensive men and women at different age and factors such as disease incidence, medical technology and health care cost were assumed to be fixed. Both total and hypertension attributable expenditures among men and women were estimated. ^ Data collection. We used the 2001-2004 MEPS household component and medical condition files; the NHIS person and condition files from 1986-1996 and 1997-2000 sample adult files were used; and the 1986-2000 NHIS that were linked to mortality in the 2002 NHIS-NDI. ^ Principal findings. Hypertensive men had significantly less utilization for most measures after controlling predisposing, enabling and need factors than hypertensive women. Similarly, hypertensive men had less prescription drug (-9.3%), office based (-7.2%) and total medical (-4.5%) expenditures than hypertensive women. However, men had more hypertension-attributable medical expenditures and utilization than women. ^ Expected total lifetime expenditure for average life table individuals at age 20, was $188,300 for hypertensive men and $254,910 for hypertensive women. But the lifetime expenditure that could be attributed to hypertension was $88,033 for men and $40,960 for women. ^ Conclusion. Hypertensive women had more utilization and expenditure for most measures than hypertensive men, possibly indicating procedural inequity. However, relatively higher hypertension-attributable health care of men shows more utilization of resources to treat hypertension related diseases among men than women. Similar results were reported in lifetime analyses.^ Key words: gender, medical expenditures, utilization, hypertension-attributable, lifetime expenditure ^

Use of contraception and contraceptive services among U.S. Hispanic women: 2006--2008

This study investigates the association between race/ethnicity and acculturation variables (language preference and nativity) with use of contraception and contraceptive services among Mexican/Mexican American and “other” Hispanic women aged 15-44 when compared to non- Hispanic white women.^ Data was analyzed from the 2006-2008 National Survey of Family Growth. The sample contained 3357 women aged 15-44. Multivariate logistic regression analysis was used to examine the association between race/ethnicity and acculturation variables and contraceptive-related behaviors adjusted for other known covariates. ^ After multivariate analysis, neither nativity nor language preference were significantly associated with contraception use or contraceptive services. Mexican/Mexican American women did not differ in their contraception-related behaviors when compared to non-Hispanic whites. Other Hispanic women, however, were less likely to obtain contraceptive services than non-Hispanic whites (OR=0.67, 95% CI=0.45-1.00). Women aged 30-39 and 40-44 were less likely to obtain contraception and contraceptive services than those aged 15-19. Single women were less likely to use contraception (OR=0.72, 95% CI=0.56-0.92) and contraceptive services (OR=0.69, 95% CI=0.53-0.89) than married/co-habiting women. Women with healthcare coverage were more likely to use contraception and contraceptive services than uninsured women.^ Among Hispanic women of different origin groups, age, marital status, and healthcare coverage were stronger indicators of contraception-related behavior than race/ethnicity, language preference, and nativity. Reproductive health programs that target increased use of contraception and contraceptive services among Hispanic origin groups should specifically target women who are over 30, single, and uninsured.^

Amy Bucholz (?) UUM Women's Track, 1993

{At Len Paddock Invitational]