Gender differences in compensation in academic medicine: the results from four neurological specialties within the University of California Healthcare System

This study demonstrates the continued existence of gender disparity with respect to salary in four neurologic specialties in the largest public healthcare system of the Western United States without the bias of self-report. We extracted physician salary information from the publicly available UC pay system database and obtained Scopus (http://www.scopus.com/home.url) and Web of Science publication counts and h-indices via searching individual faculty by name and specialty. Faculty gender, institution, specialty, ranking, chairmanship, degrees, and salary data were collected through review of departmental websites and individual faculty profiles. All faculty members (n = 433) from the departments of ophthalmology, otolaryngology, neurosurgery and neurology in the UC pay system database in 2008 were selected for analysis. We found that female faculty members in the 2008 UC healthcare system were significantly underrepresented from the highest salary brackets, representing only 12.5 and 2.6 % of those earning $300,001–$400,000 and over $400,000, respectively (p < 0.01). The female-to-male salary ratio in 2008 for all UC physicians earning over $100,000 was 0.698 (p < 0.00001). Multivariate regression modeling demonstrated a 12 % salary deficit (95 % CI 2–21 %, p = 0.02) for women in the UC healthcare system after controlling for institution, professorial rank, chairmanship, specialty, Scopus publication count, and Scopus h-index. Despite recent efforts at educational equality in the training of physicians, gender disparities still persist within academic medicine.     

Abiotic degradation of hexahydro-l,3,5-trinitro-1,3,5-triazine in the presence of hydrogen sulfide and black carbon.

We report that hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) was rapidly destroyed by sulfides in the presence of black carbon, forming nitrite and formaldehyde, rather than toxic nitrosated reduction products. Although traditionally viewed as inactive sorbents, black carbons have been noted to participate in the destruction of certain contaminants, such as azo dyes, via quinonoid groups. However, in our experiments sulfide modification of quinones did not seem to be involved. Although at least 1.2 mM sulfides were needed for the reaction to proceed, abiotic natural attenuation of RDX in marine sediments may occur, because these concentrations are found in certain marine sediments, together with black carbon. In the absence of natural black carbons, synthetic black carbons, such as activated carbon, may be added to sediments. As compared with other in situ techniques, such as bioremediation and zero-valent iron cutoff trenches, which often generate nitrosated byproducts, this in situ, abiotic technique may be an attractive alternative.     

Concentration and particle size of airborne toxic algae (brevetoxin) derived from ocean red tide events

Red tides in the Gulf of Mexico are formed by blooms of the dinoflagellate Karenia brevis, which produces brevetoxins (PbTx). Brevetoxins can be transferred from water to air in the wind-powered whitecapped waves during red tide episodes. Inhalation exposure to marine aerosol containing PbTx causes respiratory problems. A liquid chromatograph/ tandem mass spectrometric method was developed for the detection and quantitation of several PbTxs in ambient samples collected during red tide events. This method was complemented by a previously developed antibody assay that analyzes the entire class of PbTx compounds. The method showed good linearity, accuracy, and reproducibility, allowing quantitation of PbTx compounds in the 10 pg/m3 range. Air concentrations of PbTxs and brevenal for individual samples ranged from 0.01 to 80 ng/m3. The particle size showed a single mode with a mass median diameter between 6 and 10 microm, which was consistent for all of the PbTx species that were measured. Our results imply that individual PbTxs were from the same marine aerosol or from marine aerosol that was produced from the same process. The particle size indicated the likelihood of high deposition efficiency in the respiratory tract with the majority of aerosol deposited in the upper airways and small but not insignificant deposition in the lower airways.     

Production of 11C in Fullerene Cages: Short Half-Life Tracers

¹¹C “raditfullerenes” C_n1¹¹C (n = 60, 70, 76 to 84) have been produced, purified by high performance liquid chromatography, and characterized using optical absorption spectroscopy and an ultrasensitive coincidence counting technique for radioactivity measurement. The first successful direct labelling of the higher fullerenes C_n-1¹¹C (n = 76 to 84), in addition to C₅₉¹¹C and C₆₉¹¹C, suggests that well characterized ¹¹C radiofullerenes of various sizes could find possible applications as tracers in fluid flow systems (both biological and physical) and in porosity characterization of nanoscale membranes.     

Degradation of tertiary alkylamines during chlorination/chloramination: implications for formation of aldehydes, nitriles, halonitroalkanes, and nitrosamines

Drinking water utilities are exploring the use of waters impacted by wastewater effluents and agricultural runoff to meet the demands of growing populations. Due to the elevated organic nitrogen concentrations in these waters, the pathways responsible for transformation of organic nitrogen into toxic nitrogenous disinfection byproducts during chlorine and chloramine disinfection are of current concern. Tertiary alkylamines are important functional groups in human waste products and various consumer products that can be released to drinking water supplies via wastewater effluents. We investigated degradation pathways for model tertiary alkylamines during chlorination and chloramination. Our results indicate that tertiary alkylamines degrade nearly instantaneously during chlorination to form aldehydes and secondary alkylamines quantitatively, with no significant regioselectivity. Similar results were observed during chloramination, but the observed degradation rates were much slower, with lower yields of aldehydes. As these major products were fairly stable, these results explain why tertiary amines are significant precursors of secondary nitrosamines during chloramination. Trichloronitromethane formed at very low yields during chlorination, but was not observed during chloramination; monochloronitromethane and dichloronitromethane were never detected. Despite the significant yields of aldehydes during chloramination, our results indicated low nitrile yields bythe reaction between chloramines and aldehydes.     

Nitrosamine formation pathway revisited: the importance of chloramine speciation and dissolved oxygen

Nitrosamine formation during chloramination previously has been linked to a reaction between monochloramine and organic nitrogen precursors via unsymmetrical dialkylhydrazine intermediates. Our results demonstrate the critical importance of dichloramine and dissolved oxygen. We propose a new nitrosamine formation pathway in which dichloramine reacts with secondary amine precursors to form chlorinated unsymmetrical dialkylhydrazine intermediates. Oxidation of these intermediates by dissolved oxygen to form nitrosamines competes with their oxidation by chloramines. Even when preformed monochloramine was applied, our model explained nearly all N-nitrosodimethylamine formation from the traces of dichloramine formed via monochloramine disproportionation. We suggest that, in contrast to unsymmetrical dialkylhydrazines, the weak, nonpolar nature of the N-Cl linkage in chlorinated unsymmetrical dialkylhydrazine intermediates enables incorporation of dissolved oxygen to form nitrosamines. With the improved understanding of the nitrosamine formation pathway, strategies are suggested that could significantly reduce nitrosamine formation during chloramination.     

Brominated flame retardants in polar bears (Ursus maritimus) from Alaska, the Canadian Arctic, East Greenland, and Svalbard

Polybrominated diphenyl ethers (PBDEs) were determined in adipose tissue of adult and subadult female polar bears sampled between 1999 and 2002 from sub-populations in Arctic Canada, eastern Greenland, and Svalbard, and in males and females collected from 1994 to 2002 in northwestern Alaska. Only 4 congeners (BDE47, 99, 100, and 153) were consistently identified in all samples. BDE47 was the major PBDE congener representing from 65% to 82% of the sum (sigma) PBDEs. Age was not a significant covariate for individual PBDEs or sigmaPBDE. Higher proportions of BDE 99, 100, and 153 were generally found in samples from the Canadian Arctic than from Svalbard or the Bering-Chukchi Sea area of Alaska. Geometric mean sigmaPBDE concentrations were highest for female polar bear fat samples collected from Svalbard (50 ng/g lipid weight (lw)) and East Greenland (70 ng/g lw). Significantly lower sigmaPBDE concentrations were found in fat of bears from Canada and Alaska (means ranging from 7.6 to 22 ng/g lw).