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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

The development of new radiation protocols for insect sterilization using long wavelength x-rays

Control of insect species for the protection of crops, livestock, and prevention of disease such as dengue fever and malaria is a high priority in today’s global economy. Traditional methods such as pesticides have fallen out of favor because its effects are indiscriminate as well as adverse and unpredictable impacts on the environment. Modern novel techniques such as genetic modification have had trouble gaining traction due to ethics concerns and the potential for unforeseen side effects. One approach that has gained traction and has proven its efficacy is the use of ionizing radiation to affect sterility in insect species in order to scale back their population. Known as Sterile Insect Technique (SIT), it has proven very effective in eradicating certain dipteran insect populations. However, when standard sterilization methods developed for dipertans are applied to mosquito populations significant complications arise, such as an inability to compete with non-irradiated males and high mortality rates. We have investigated the effect of treatment with x-rays of different wavelengths on x-ray sterilized mosquito males. Our results have demonstrated that longer wavelength x-rays have a significant effect on the outcome of the sterile males’ longevity as well as an increase on the efficacy of sterilization while employing a substantially lower dose.

60 APPLIED LIFE SCIENCES↗
NASA NTRS2000

Inducing jet-lag in older people: directional asymmetry

Twenty healthy elderly subjects (12 female, 8 male; mean age 81 years, range 67-87 years) each experienced a 15-day time isolation protocol in which they lived individually in a special laboratory apartment in which sleep and circadian rhythm measures could be taken. There were two experiments: one (6 females, 4 males) involved a 6-h phase advance of the sleep/wake cycle, and the other (6 females, 4 males) a 6-h phase delay. Each started with 5 baseline days, immediately followed by the phase shift. The subject was then held to the phase shifted routine for the remainder of the study. Rectal temperatures were recorded minute-by-minute throughout the entire experiment and each night of sleep was recorded using polysomnography. A directional asymmetry in phase-shift effects was apparent, with significantly more sleep disruption and circadian rhythm amplitude disruption after the phase advance than after the phase delay. Sleep disruption was reflected in reduced time spent asleep, and in changed REM latency, which increased in the phase advance direction but decreased in the phase delay direction. Although the phase advance led to a significant increase in wakefulness in the first half of the night, the phase delay did not lead to an equivalent increase in wakefulness during the second half of the night. Examination of both raw and 'demasked' circadian rectal temperature rhythms confirmed that phase adjustment was slow in both directions, but was less slow (and more monotonic) after the phase delay than after the phase advance. Subjective alertness suffered more disruption after the phase advance than after the phase delay.

NASA Discipline Regulatory Physiology↗
DOE OSTI2023

Obesity is associated with biliary tract cancer mortality and incidence: A pooled analysis of 21 cohort studies in the Asia Cohort Consortium

Abstract Body fatness is considered a probable risk factor for biliary tract cancer (BTC), whereas cholelithiasis is an established factor. Nevertheless, although obesity is an established risk factor for cholelithiasis, previous studies of the association of body mass index (BMI) and BTC did not take the effect of cholelithiasis fully into account. To better understand the effect of BMI on BTC, we conducted a pooled analysis using population‐based cohort studies in Asians. In total, 905 530 subjects from 21 cohort studies participating in the Asia Cohort Consortium were included. BMI was categorized into four groups: underweight (<18.5 kg/m 2 ); normal (18.5‐22.9 kg/m 2 ); overweight (23‐24.9 kg/m 2 ); and obese (25+ kg/m 2 ). The association between BMI and BTC incidence and mortality was assessed using hazard ratios (HR) and 95% confidence intervals (CIs) by Cox regression models with shared frailty. Mediation analysis was used to decompose the association into a direct and an indirect (mediated) effect. Compared to normal BMI, high BMI was associated with BTC mortality (HR 1.19 [CI 1.02‐1.38] for males, HR 1.30 [1.14‐1.49] for females). Cholelithiasis had significant interaction with BMI on BTC risk. BMI was associated with BTC risk directly and through cholelithiasis in females, whereas the association was unclear in males. When cholelithiasis was present, BMI was not associated with BTC death in either males or females. BMI was associated with BTC death among females without cholelithiasis. This study suggests BMI is associated with BTC mortality in Asians. Cholelithiasis appears to contribute to the association; and moreover, obesity appears to increase BTC risk without cholelithiasis.

Oze, Isao↗
DOE OSTI2023

Demographic and genetic consequences of a steelhead supplementation program

Abstract Objective Supplementation of naturally spawning populations by the addition of hatchery-spawned individuals is commonly conducted for recovery of threatened and endangered populations and to support harvest opportunities. Our objective was to evaluate whether the use of a juvenile captive broodstock and an integrated paradigm could increase returns of steelhead, the anadromous form of Rainbow Trout Oncorhynchus mykiss, while avoiding negative genetic impacts commonly associated with hatchery propagation. Methods We analyzed 291 genetic markers in adult steelhead returning to an integrated population in southwest Washington over the course of 15 years. Reproductive success (RS) of fish spawning in the natural environment was evaluated by origin (hatchery versus natural) and return year. Data were then pooled over years to maximize sample sizes for comparing RS estimates among groups (i.e., estimation of relative reproductive success [RRS]). Result We observed a weak relationship between RS and origin (male p = 0.347; female p = 0.066), but a significant relationship between RS and return year (male p < 0.001, η2 = 0.896; female p ⟨ 0.001, η2 = 0.867) (i.e., hatchery- and natural-origin fish did well or poorly together each year). Estimates of RRS for fish spawned in the hatchery ranged from 2.4 to 6.4, indicating that fish spawned in the hatchery produced more returning adult progeny than did fish allowed to spawn in the natural environment. Estimates of RRS were ⟨1.0 for hatchery-origin fish spawning in the natural environment, but the difference was nonsignificant for males and marginally significant for females. Hatchery-origin fish exhibited reduced genetic diversity as well as evidence of increased temporal population structure. Conclusion We conclude that the program was successful in achieving an increase in adult returns but not in avoiding negative genetic effects on the population and that any lasting impacts of supplementation remain to be determined.

Smith, Christian T. (ORCID:0000000240522669)↗
DOE OSTI2024

Inferring precocial Chinook Salmon production through single‐parentage assignments

Abstract Objective Parentage analysis is a routine methodology in fisheries research, but study systems exist where it is impractical to sample both parents. The ability to reliably assign offspring to a single parent is beneficial in these situations. We applied single‐parentage assignments to a naturally spawning population of Chinook Salmon Oncorhynchus tshawytscha to quantify production of anadromous returns by unsampled precocial males. Methods We used an approach that focused on two important aspects of parentage analyses: (1) addressing the presence of family structure within the set of sampled parents and (2) controlling for false‐positive and false‐negative assignments. Result Results indicated that 30% of reproductively successful males were precocial males, which produced 20% of the returning anadromous offspring. Conclusion This study provides a framework for applying single‐parent assignments in a salmonid study system while explicitly addressing sources of assignment errors.

Steele, Craig A.↗
DOE OSTI2016

Factors Associated with Advanced Inferior Vena Cava Filter Removals: A Single-Center Retrospective Study of 203 Patients Over 7 Years

PurposeTo identify factors associated with advanced inferior vena cava filter (IVCF) retrieval to raise awareness on technical considerations, retrieval efficiency, and patient safety.Materials and MethodsA single-center retrospective review was performed of 203 consecutive retrievable IVC filters placed between 2007 and 2014. Attempted retrievals were classified as advanced if the routine “snare and sheath” technique was initially unsuccessful after multiple attempts, or an alternate endovascular maneuver or access site was utilized. Patient and filter characteristics were recorded.Results203 attempted retrievals were reviewed (48.7 % male, 51.2 % female, mean age 52.7 years, mean dwell time 109 days). Advanced retrievals were observed in 20 patients (9.8 %) (15 females, 5 males). Fluoroscopy time (p ≤ 0.01, 34.3 ± 21.1 and 5.3 ± 4.5 min for advanced retrievals and routine retrievals respectively, same below), gender (p = 0.031), and retrieval tilt angle (p ≤ 0.01, 5.7 ± 5.10° vs. 11.9 ± 11.03°) were associated with advanced retrievals. Females were 3.16 times more likely to have an advanced retrieval performed than males with a significantly higher tilt angle in those with advanced retrieval. History of cancer (p = 0.502), dwell time (p = 0.916), retrieval caval diameter (p = 0.053), placement caval diameter (p = 0.365), filter type (p = 0.710), strut perforation (p = 0.506), placement tilt angle (p = 0.311), and age (p = 0.558) were not found significantly associated with advanced retrievals.ConclusionsWomen are at increased risk for advanced filter retrieval secondary to a significant change in filter tilt over time compared to men, independent of filter type or competing demographic or filter risks, likely placing them at increased risk for higher procedural fluoroscopy times.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2020

Cell fusing agent virus (Flavivirus) infection in Aedes aegypti in Texas: seasonality, comparison by trap type, and individual viral loads

Abstract South Texas has experienced local transmission of Zika virus and of other mosquito-borne viruses such as chikungunya virus and dengue virus in the last decades. Using a mosquito surveillance program in the Lower Rio Grande Valley (LRGV) and San Antonio, TX, from 2016 to 2018, we detected the presence of an insect-specific virus, cell fusing agent virus (CFAV), in the Aedes aegypti mosquito population. We tested 6,326 females and 1,249 males from the LRGV and 659 females from San Antonio for CFAV by RT-PCR using specific primers. Infection rates varied from 0 to 261 per 1,000 mosquitoes in the LRGV and 115 to 208 per 1,000 in San Antonio depending on the month of collection. Infection rates per 1,000 individuals appeared higher in females collected from BG Sentinel 2 traps compared to Autocidal Gravid Ovitraps, but the ratio of the percentage of infected pools did not differ by trap type. The natural viral load in individual males ranged from 1.25 x 10 2 to 5.50 x 10 6 RNA copies and in unfed females from 5.42 x 10 3 to 8.70 x 10 6 RNA copies. Gravid females were found to harbor fewer viral particles than males and unfed females.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Home range and resource selection of Virginia opossums in the rural southeastern United States

The Virginia opossum (Didelphis virginiana) has a rapidly expanding distribution in North America, but many aspects of its ecology remain relatively understudied, particularly in rural areas of its core range. We collected GPS telemetry data from 93 opossums in a rural, non-agricultural landscape in South Carolina, USA (2018–2019) to examine factors influencing space use and resource selection. Estimated male home ranges (99% utilization distributions) were on average 50% larger than those of females (mean home range 115.9 ± 103.7 ha vs 76.7 ± 75.0 ha). The home range size decreased on average by 20% with each 20% increase in deciduous land cover but was not affected by season or other landscape factors. Core area sizes (65% utilization distributions) were not influenced by sex (mean core area size 29.1 ± 23.7 ha and 22.4 ha ± 13.8 for males and females, respectively) or season, but the core area size decreased by 14% with each 400 m increase in distance from a permanent water source. Resource selection by opossums primarily occurred at the landscape level. Both males and females generally selected for wetlands while avoiding pine forests and developed/open areas, likely the result of differences in resource availability and predation risk between habitats. Opossums also tended to select for linear features such as unpaved roads and edge habitat, which may facilitate movement across the landscape. Finally, the home ranges we documented are among the largest recorded for opossums in the USA, likely the result of the relatively low resource abundance throughout our study area due to comparatively minimal anthropogenic influence.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Nutrient canals and porosity of the bony palate: A basis for the biological plausibility of the anterior middle superior alveolar nerve block

Background. The authors investigated morphologic parameters of the palatal cortex that affect the diffusion of local anesthetic solution in the region of the anterior middle superior alveolar (AMSA) nerve block injection site. Methods. The authors used computed tomographic (CT) and micro-CT imaging to assess 20 human skulls from an anatomic collection. Analysis of the C1 images included frequency, distribution, and width of the nutrient canals in the bony palate, according to to the person's sex and age. Micro-CT analysis involved measuring the thickness and porosity of palatal cortical bone in the area of the AMSA injection site in relation to the thickness and porosity of the opposite buccal cortical bone. Results. There was a statistically significant difference (P = .042) in the location of the nutrient canals between male specimens (> 50% in the border region) and female specimens (> 50% in the palatal process). Furthermore, the female skulls had significantly wider nutrient canal foramina (P = .042) than did the male skulls. Despite greater thickness, the palatal cortex in the area of the AMSA injection site had slightly greater porosity than did the buccal cortex. A significantly greater number of microcanals penetrated the whole cortical thickness in palatal than in buccal cortical bone (P = .001). Conclusions. The distribution and width of nutrient canals differed between male and female skulls. At the microscopic level, structural characteristics of the palatal cortex provide a good anatomic basis for the potential of a satisfactory AMSA injection success rate. Practical Implications. The AMSA technique success rate might be increased if the clinician adjusts the injection site to the distribution of nutrient canals, depending on the sex of the patient.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

STAT5A and STAT5B have opposite correlations with drug response gene expression

Introduction: STAT5A and STAT5B are important transcription factors that play a key role in regulation of several important physiological processes including proliferation, survival, mediation of responses to cytokines and in regulating gender differences in drug response genes such as the hepatic cytochrome P450s (CYPs) that are responsible for a large majority of drug metabolism reactions in the human body. STAT5A and STAT5b have a high degree of sequence homology and have been reported to have largely similar functions. Recent studies have, however, indicated that they can also often have distinct and unique roles in regulating gene expression. Objective: In this study, we evaluated the association of STAT5A and STAT5B mRNA expression levels with those of several key hepatic cytochrome P450s (CYPs) and hepatic transcription factors (TFs) and evaluated the potential roles of STAT5A and 5b in mediating gender differences in these CYPs and TFs. Methods: Expression profiling for major hepatic CYP isoforms and transcription factors was performed using RNA sequencing (RNA-seq) in 102 human liver samples (57 female, 45 male). Real time PCR gene expression data for selected CYPs and TFs was available on a subset of 50 human liver samples (25 female, 25 male) and was used to validate the RNA-seq findings. Results: While STAT5A demonstrated significant negative correlation with expression levels of multiple hepatic transcription factors (including NR1I2 and HNF4A) and DMEs such as CYP3A4 and CYP2C19, STAT5B expression was observed to demonstrate positive associations with several CYPs and TFs analyzed. As STAT5A and STAT5B have been shown to be important in regulation of gender differences in CYPs, we also analyzed STAT5A and 5b associations with CYPs and TFs separately in males and females and observed gender dependent differential associations of STATs with several CYPs and TFs. Results from the real time PCR validation largely supported our RNA-seq findings. Conclusions: Using both RNA sequencing and real time PCR, we examined the association of STAT5A and STAT5B mRNA expression with CYP and TF gene expression. While STAT5A demonstrated significant negative correlations with expression levels of multiple hepatic TFs (including NR1I2 and HNF4α) and CYPs (eg. CYP3A4, CYP2C19), STAT5B expression was observed to demonstrate positive association with most of the CYPs/TFs analyzed suggesting that STAT5A and STAT5b have potentially different and distinct roles in regulating expression of hepatic drug response genes. Further studies are needed to elucidate the potential roles of STAT5A and 5b in regulation of CYPs/TFs and the potential implications of these findings.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

β-cell serotonin production is associated with female sex, old age, and diabetes-free condition

Serotonin is known to be present in pancreatic β-cells and to play several physiological roles, including insulin secretion, β-cell proliferation, and paracrine inhibition of α-cells. However, the serotonin production of different cell lines and islets has not been compared based on age, sex, and diabetes related conditions. Here, we directly compared the serotonin concentrations in βTC and MIN6 cell lines, as well as in islets from mice using ultra-performance liquid chromatography tandem mass spectrometry. The average serotonin concentration was 5–10 ng/mg protein in the islets of male and non-pregnant female mice. The serotonin level was higher in females than males at 8 weeks, although there was no difference at 1 year. Furthermore, we observed serotonin by immunofluorescence staining in the pancreatic tissues of mice and human. Serotonin was detected by immunofluorescence staining in a portion of β-cells from islets of old female mice, but not of male or young female mice. A similar pattern was observed in human pancreas as well. In humans, serotonin production in β-cells was associated with a diabetes-free condition. Thus, serotonin production in β-cells was associated with old age, female sex, and diabetes-free condition. - Highlights: • Actual serotonin concentrations in cell lines and islets are compared. • Serotonin over-production in mouse β-cell is aged and female specific. • Ovariectomy lowers serotonin concentrations in islets. • Serotonin over-production in human β-cell is aged, female, and non-diabetes specific.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Novel localization of Aurora A kinase in mouse testis suggests multiple roles in spermatogenesis

Highlights: • Aurora A kinase is a previously identified mitotic kinase. • Developing male germ cells express Aurora A including spermatogonia, spermatocytes, and spermatids. • Aurora A kinase and its activated form are localized to the flagella of sperm. • Activated Aurora A kinase is enriched in motile sperm of the epididymis suggesting a role in sperm motility. Male germ cells are transformed from undifferentiated stem cells into spermatozoa through a series of highly regulated steps together termed spermatogenesis. Spermatogonial stem cells undergo mitosis and differentiation followed by two rounds of meiotic division and then proceed through a series of dramatic cell shape changes to form highly differentiated spermatozoa. Using indirect immunofluorescence, we investigated a role for the mitotic kinase, Aurora A (AURKA), in these events through localization of this protein in mouse testis and spermatozoa. AURKA is expressed in several cell types in the testis. Spermatogonia and spermatocytes express AURKA as expected based on the known role of this kinase in cell division. Surprisingly, we also found AURKA localized to spermatids and the flagellum of spermatozoa. Total AURKA and activated AURKA are expressed in different compartments of the sperm flagellum with total AURKA found in the principal piece and its phosphorylated and activated form found in the sperm midpiece. In addition, active AURKA is enriched in the flagellum of motile sperm isolated from cauda epididymis. These results provide evidence for a unique role for AURKA in spermatogenesis and sperm motility. Defining the signaling mechanisms that govern spermatogenesis and sperm cell function is crucial to understanding and treating male infertility as well as for development of new contraceptive strategies.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

In vivo masculinizing function of the Ostrinia furnacalis Masculinizer gene

Highlights: • We established a system for monitoring the sex of a single O. furnacalis embryo. • Of Masc is a masculinizing factor of O. furnacalis. • Masc is a masculinizing factor in an insect species distant from Bombycidae. The Masculinizer gene (Masc) encodes a CCCH tandem zinc finger protein essential for masculinization and dosage compensation in the silkworm Bombyx mori. Previously we identified a Masc orthologue from the crambid Ostrinia furnacalis (OfMasc) and observed its masculinizing activity in the B. mori cultured cell line BmN-4. However, the role of OfMasc in masculinization of O. furnacalis has not been assessed. In this study, we unexpectedly discovered that all of the male larvae that escaped from Wolbachia-induced embryonic male-killing by OfMasc cRNA injection expressed the female-type splicing variants of O. furnacalis doublesex (Ofdsx). To clarify the role of OfMasc in the masculinization process in vivo, we established a system to monitor both sex chromosome- and dsx splicing-based sexes from a single O. furnacalis embryo. Using this system, we investigated the effects of OfMasc knockdown in early embryos on Ofdsx splicing and found that depletion of OfMasc mRNA in male embryos induced the production of the female-type splicing variants of Ofdsx. This result indicates that OfMasc is required for masculinization in O. furnacalis, and that the Masc protein possesses masculinizing activity in an insect species that is phylogenetically distant from Bombycidae.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2026

Temporal multi-omic analysis uncovers sex-biased molecular programs underlying skeletal muscle adaptation to endurance training

Background. Exercise training is known to benefit health and reduce disease risk. While adaptations in skeletal muscles are fundamental to many of the health benefits of exercise training, the common and sex-specific molecular regulators that mediate these adaptations remain to be fully elucidated. Methods. To this end, we leveraged skeletal muscle multi-omics data generated by the Molecular Transducers of Physical Activity Consortium (MoTrPAC), where 6 month-old male and female rats endurance trained for 1, 2, 4, or 8 weeks. Our objective was to identify shared and sex-specific multi-omic molecular responses to endurance training in skeletal muscle, and relate them to phenotypic adaptations. Results. We identified largely sexually-conserved transcriptomic and proteomic enrichments in the gastrocnemius, which correlated with skeletal muscle responses from a published exercise study in humans. We uncovered sex-consistent post-translational modifications, including decreased oxidation of MYH2 and deacetylation of the ß-oxidation enzyme HADHA. Pathway enrichment analyses revealed sex-specific remodeling across the acetylome, redox proteome, and phosphoproteome; females decreased mitochondrial protein oxidation and increased mitochondrial cristae proteins, indicative of enhanced redox buffering and mitochondrial efficiency. Despite observed decreases in the oxidation of key mitochondrial proteins, females displayed increases in the oxidation of proteins involved in glucose catabolism relative to males after 8 weeks of training, suggestive of sex-biased subcellular reactive oxygen species generation. Conclusions. This work shows a large portion of the adaptive response to endurance training in skeletal muscle is shared between females and males, while there are distinct and nuanced sex-specific adaptations that are evident, particularly at the level of post-translational regulation.

Many, Gina M.↗
DOE OSTI2016

High feather mercury concentrations in the wandering albatross are related to sex, breeding status and trophic ecology with no demographic consequences

Hg can affect physiology of seabirds and ultimately their demography, particularly if they are top consumers. In the present study, body feathers of >200 wandering albatrosses from Possession Island in the Crozet archipelago were used to explore the potential demographic effects of the long-term exposure to Hg on an apex predator. Variations of Hg with sex, age class, foraging habitat (inferred from δ{sup 13}C values), and feeding habits (inferred from δ{sup 15}N values) were examined as well as the influence of Hg on current breeding output, long-term fecundity and survival. Wandering albatrosses displayed among the highest Hg feather concentrations reported for seabirds, ranging from 5.9 to 95 µg g{sup −1}, as a consequence of their high trophic position (δ{sup 15}N values). These concentrations fall within the same range of those of other wandering albatross populations from subantarctic sites, suggesting that this species has similar exposure to Hg all around the Southern Ocean. In both immature and adult albatrosses, females had higher Hg concentrations than males (28 vs. 20 µg g{sup −1} dw on average, respectively), probably as a consequence of females foraging at lower latitudes than males (δ{sup 13}C values). Hg concentrations were higher in immature than in adult birds, and they remained fairly constant across a wide range of ages in adults. Such high levels in immature individuals question (i) the frequency of moult in young birds, (ii) the efficiency of Hg detoxification processes in immatures compared to adults, and (iii) importantly the potential detrimental effects of Hg in early life. Despite very high Hg concentrations in their feathers, neither effects on adults' breeding probability, hatching failure and fledgling failure, nor on adults' survival rate were detected, suggesting that long-term bioaccumulated Hg was not under a chemical form leading to deleterious effects on reproductive parameters in adult individuals. - Highlights: • Immature albatrosses had higher feather Hg concentrations than adults. • Foraging habitat influenced Hg bioaccumulation as a result of male and female segregation. • No carry-over effects were detected on reproductive parameters.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Urinary phthalate metabolites and environmental phenols in university students in South China

Highlights: • University students in South China might be exposed to higher levels of phthalates than parabens or bisphenol analogues. • Concentrations of target EEDs were relatively low in university students, with higher levels in female than male students. • The usage of PCPs is an important source other than diet to affect the profiles of phthalates and parabens in students. In China, university students have unique lifestyles compared with the rest of the youth population, as they are almost entirely isolated in campuses. The number of university students is large, and since students represent the future of human reproduction, exposure to environmental endocrine disruptors (EEDs) may have a large impact on society. In this study, levels of several EEDs, including phthalate metabolites, parabens, bisphenol A (BPA) and its analogues, triclosan (TCS), and benzophenone-3, were determined in 169 urine samples collected from university students in Guangzhou, South China. In addition, to further understand the potential sources of EEDs in their daily lives, a survey of students’ lifestyles was conducted. Based on the urinary concentrations of EEDs and the survey results, daily exposure doses of target EEDs and their potential sources were investigated. Our results indicated that nine phthalate metabolites, three parabens, and BPA were ubiquitous (detection frequency > 60%) in the urine of university students. The concentrations of total phthalates (median: 99.4 µg L{sup −1}) were orders of magnitude higher than those of total parabens (7.30 µg L{sup −1}) and of other environmental phenols (0.40 µg L{sup −1}). Significantly higher concentrations of phthalates, parabens, and TCS were found in female versus male students, partly due to the higher usage of personal care products (PCPs) by female students (p < 0.05). The estimated daily intakes (EDIs) of phthalates, parabens, BPA, and TCS were 0.46–1.35, 3.29–10.3, 0.007, and 0.67 µg/kg-bw/day, respectively. The EDIs of phthalates and BPA were much lower than those suggested by the European Food Safety guidelines (10, 50, and 50 µg/kg-bw/day for dibutyl phthalate, diethylhexyl phthalate, and BPA, respectively). Our results indicated that university students were widely exposed to EEDs, but at relatively low doses. PCP usage was the main reason for differences in levels of phthalates (especially diethyl phthalate) and parabens between male and female students in South Chinese universities.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Variations in Medicare Reimbursement in Radiation Oncology: An Analysis of the Medicare Provider Utilization and Payment Data Set

Purpose: The purposes of this study were to summarize recently published data on Medicare reimbursement to individual radiation oncologists and to identify the causes of variation in Medicare reimbursement in radiation oncology. Methods and Materials: The Medicare Provider Utilization and Payment Data: Physician and Other Supplier Public Use File (POSPUF), which details nearly all services provided by radiation oncologists in 2012, was used for this study. The data were filtered and analyzed by physician and by billing code. Statistical analysis was performed to identify differences in reimbursements based on sex, rurality, billing of technical services, or location in a certificate of need (CON) state. Results: There were 4135 radiation oncologists who received a total of $1,499,625,803 in payments from Medicare in 2012. Seventy-five percent of radiation oncologists were male. The median reimbursement was $146,453. The code with the highest total reimbursement was 77418 (radiation treatment delivery intensity modulated radiation therapy [IMRT]). The most commonly billed evaluation and management (E/M) code for new visits was 99205 (49%). The most commonly billed E/M code for established visits was 99213 (54%). Forty percent of providers billed none of their new office visits using 99205 (the highest E/M billing code), whereas 34% of providers billed all of their new office visits using 99205. For the 1510 radiation oncologists (37%) who billed technical services, median Medicare reimbursement was $606,008, compared with $93,921 for all other radiation oncologists (P<.001). On multivariate analysis, technical services billing (P<.001), male sex (P<.001), and rural location (P=.007) were predictive of higher Medicare reimbursement. Conclusions: The billing of technical services, with their high capital and labor overhead requirements, limits any comparison in reimbursement between individual radiation oncologists or between radiation oncologists and other specialists. Male sex and rural practice location are independent predictors of higher total Medicare reimbursements.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Factors Affecting Gender-based Experiences for Residents in Radiation Oncology

Purpose: Although women constitute approximately half of medical school graduates, an uneven gender distribution exists among many specialties, including radiation oncology, where women fill only one third of residency positions. Although multiple social and societal factors have been theorized, a structured review of radiation oncology resident experiences has yet to be performed. Methods and Materials: An anonymous and voluntary survey was sent to 611 radiation oncology residents practicing in the United States. Residents were asked about their gender-based experiences in terms of mentorship, their professional and learning environment, and their partnerships and personal life. Results: A total of 203 participants submitted completed survey responses. Fifty-seven percent of respondents were men, and 43% were women, with a mean age of 31 years (standard deviation=3.7 years). Although residents in general value having a mentor, female residents prefer mentors of the same gender (P<.001), and noted having more difficulty finding a mentor (P=.042). Women were more likely to say that they have observed preferential treatment based on gender (P≤.001), and they were more likely to perceive gender-specific biases or obstacles in their professional and learning environment (P<.001). Women selected residency programs based on gender ratios (P<.001), and female residents preferred to see equal numbers of male and female faculty (P<.001). Women were also more likely to perceive work-related strain than their male counterparts (P<.001). Conclusions: Differences in experiences for male and female radiation oncology residents exist with regard to mentorship and in their professional and learning environment.

62 RADIOLOGY AND NUCLEAR MEDICINE↗