881 research outputs found
Predictors of Depressive Symptoms and Unemployed Black Adults
Using data from a probability based survey of unemployed Black adults residing in an urban area, this study explores factors related to the presence of depressive symptoms. Findings indicate that depressive symptoms are less among unemployed persons with higher levels of income, education, religiosity, age and satisfactory social support. Age, however, is the single best predictor of depressive symptoms among unemployed Blacks. There were no significant differences by gender
Verification of TG-61 dose for synchrotron-produced monochromatic x-ray beams using fluence-normalized MCNP5 calculations
Ion chamber dosimetry is being used to calibrate dose for cell irradiations
designed to investigate photoactivated Auger electron therapy at the Louisiana
State University CAMD synchrotron facility. This study performed a dosimetry
intercomparison for synchrotron-produced monochromatic x-ray beams at 25 and 35
keV. Ion chamber depth-dose measurements in a PMMA phantom were compared with
the product of MCNP5 Monte Carlo calculations of dose per fluence and measured
incident fluence. Monochromatic beams of 25 and 35 keV were generated on the
tomography beamline at CAMD. A cylindrical, air-equivalent ion chamber was used
to measure the ionization created in a 10x10x10-cm3 PMMA phantom for depths
from 0.6 to 7.7 cm. The American Association of Physicists in Medicine TG-61
protocol was applied to convert measured ionization into dose. Photon fluence
was determined using a NaI detector to make scattering measurements of the beam
from a thin polyethylene target at angles 30 degrees to 60 degrees.
Differential Compton and Rayleigh scattering cross sections obtained from
xraylib, an ANSI C library for x-ray-matter interactions, were applied to
derive the incident fluence. MCNP5 simulations of the irradiation geometry
provided the dose deposition per photon fluence as a function of depth in the
phantom. At 25 keV the fluence-normalized MCNP5 dose overestimated the
ion-chamber measured dose by an average of 7.2+/-3.0% to 2.1+/-3.0% for PMMA
depths from 0.6 to 7.7 cm, respectively. At 35 keV the fluence-normalized MCNP5
dose underestimated the ion-chamber measured dose by an average of 1.0+/-3.4%
to 2.5+/-3.4%, respectively. These results showed that TG-61 ion chamber
dosimetry, used to calibrate dose output for cell irradiations, agreed with
fluence-normalized MCNP5 calculations to within approximately 7% and 3% at 25
and 35 keV, respectively.Comment: 22 pages, 5 figure
Protocol of a cluster randomized trial of an educational intervention to increase knowledge of living donor kidney transplant among potential transplant candidates
BackgroundThe best treatment option for end-stage renal disease is usually a transplant, preferably a live donor kidney transplant (LDKT). The most effective ways to educate kidney transplant candidates about the risks, benefits, and process of LDKT remain unknown.Methods/designWe report the protocol of the Enhancing Living Donor Kidney Transplant Education (ELITE) Study, a cluster randomized trial of an educational intervention to be implemented during initial transplant evaluation at a large, suburban U.S. transplant center. Five hundred potential transplant candidates are cluster randomized (by date of visit) to receive either: (1) standard-of-care ("usual") transplant education, or (2) intensive education that is based upon the Explore Transplant series of educational materials. Intensive transplant education includes viewing an educational video about LDKT, receiving print education, and meeting with a transplant educator. The primary outcome consists of knowledge of the benefits, risks, and process of LDKT, assessed one week after the transplant evaluation. As a secondary outcome, knowledge and understanding of LDKT are assessed 3 months after the evaluation. Additional secondary outcomes, assessed one week and 3 months after the evaluation, include readiness, self-efficacy, and decisional balance regarding transplant and LDKT, with differences assessed by race. Although the unit of randomization is the date of the transplant evaluation visit, the unit of analysis will be the individual potential transplant candidate.DiscussionThe ELITE Study will help to determine how education in a transplant center can best be designed to help Black and non-Black patients learn about the option of LDKT.Trial registrationClinicaltrials.gov number NCT01261910
Dose-response curve of EBT, EBT2, and EBT3 radiochromic films to synchrotron-produced monochromatic x-ray beams
Purpose: This work investigates the dose-response curves of GAFCHROMIC ® EBT, EBT2, and EBT3 radiochromic films using synchrotron-produced monochromatic x-ray beams. EBT2 film is being utilized for dose verification in photoactivated Auger electron therapy at the Louisiana State University Center for Advanced Microstructures and Devices (CAMD) synchrotron facility. Methods: Monochromatic beams of 25, 30, and 35 keV were generated on the tomography beamline at CAMD. Ion chamber depth-dose measurements were used to determine the dose delivered to films irradiated at depths from 0.7 to 8.5 cm in a 10 × 10 × 10-cm3 polymethylmethacrylate phantom. AAPM TG-61 protocol was applied to convert measured ionization into dose. Films were digitized using an Epson 1680 Professional flatbed scanner and analyzed using the net optical density (NOD) derived from the red channel. A dose-response curve was obtained at 35 keV for EBT film, and at 25, 30, and 35 keV for EBT2 and EBT3 films. Calibrations of films for 4 MV x-rays were obtained for comparison using a radiotherapy accelerator at Mary Bird Perkins Cancer Center. Results: The sensitivity (NOD per unit dose) of EBT film at 35 keV relative to that for 4-MV x-rays was 0.73 and 0.76 for doses 50 and 100 cGy, respectively. The sensitivity of EBT2 film at 25, 30, and 35 keV relative to that for 4-MV x-rays varied from 1.09-1.07, 1.23-1.17, and 1.27-1.19 for doses 50-200 cGy, respectively. For EBT3 film the relative sensitivity was within 3 of unity for all three monochromatic x-ray beams. Conclusions: EBT and EBT2 film sensitivity showed strong energy dependence over an energy range of 25 keV-4 MV, although this dependence becomes weaker for larger doses. EBT3 film shows weak energy dependence, indicating that it would be a better dosimeter for kV x-ray beams where beam hardening effects can result in large changes in the effective energy. © 2012 American Association of Physicists in Medicine
Factors predictive of successful retention in care among HIV-infected men in a universal test-and-treat setting in Uganda and Kenya: A mixed methods analysis.
BackgroundPrevious research indicates clinical outcomes among HIV-infected men in sub-Saharan Africa are sub-optimal. The SEARCH test and treat trial (NCT01864603) intervention included antiretroviral care delivery designed to address known barriers to HIV-care among men by decreasing clinic visit frequency and providing flexible, patient-centered care with retention support. We sought to understand facilitators and barriers to retention in care in this universal treatment setting through quantitative and qualitative data analysis.MethodsWe used a convergent mixed methods study design to evaluate retention in HIV care among adults (age > = 15) during the first year of the SEARCH (NCT01864603) test and treat trial. Cox proportional hazards regression was used to evaluate predictors of retention in care. Longitudinal qualitative data from n = 190 in-depth interviews with HIV-positive individuals and health care providers were analyzed to identify facilitators and barriers to HIV care engagement.ResultsThere were 1,863 men and 3,820 women who linked to care following baseline testing. Retention in care was 89.7% (95% CI 87.0-91.8%) among men and 89.0% (86.8-90.9%) among women at one year. In both men and women older age was associated with higher rates of retention in care at one year. Additionally, among men higher CD4+ at ART initiation and decreased time between testing and ART initiation was associated with higher rates of retention. Maintaining physical health, a patient-centered treatment environment, supportive partnerships, few negative consequences to disclosure, and the ability to seek care in facilities outside of their community of residence were found to promote retention in care.ConclusionsFeatures of the ART delivery system in the SEARCH intervention and social and structural advantages emerged as facilitators to retention in HIV care among men. Messaging around the health benefits of early ART start, decreasing logistical barriers to HIV care, support of flexible treatment environments, and accelerated linkage to care, are important to men's success in ART treatment programs. Men already benefit from increased social support following disclosure of their HIV-status. Future efforts to shift gender norms towards greater equity are a potential strategy to support high levels of engagement in care for both men and women
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Economic Energy Savings Potential in Federal Buildings
The primary objective of this study was to estimate the current life-cycle cost-effective (i.e., economic) energy savings potential in Federal buildings and the corresponding capital investment required to achieve these savings, with Federal financing. Estimates were developed for major categories of energy efficiency measures such as building envelope, heating system, cooling system, and lighting. The analysis was based on conditions (building stock and characteristics, retrofit technologies, interest rates, energy prices, etc.) existing in the late 1990s. The potential impact of changes to any of these factors in the future was not considered
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