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The MSL Curiosity rover investigated dark, Mn-P-enriched nodules in shallow lacustrine/fluvial sediments at the Groken site in Glen Torridon, Gale Crater, Mars. Applying all relevant information from the rover, the nodules are interpreted as pseudomorphs after original crystals of vivianite, (Fe2+,Mn2+)3(PO4)2·8H2O, that cemented the sediment soon after deposition. The nodules appear to have flat faces and linear boundaries and stand above the surrounding siltstone. ChemCam LIBS (laser-induced breakdown spectrometry) shows that the nodules have MnO abundances approximately twenty times those of the surrounding siltstone matrix, contain little CaO, and have SiO2 and Al2O3 abundances similar to those of the siltstone. A deconvolution of APXS analyses of nodule-bearing targets, interpreted here as representing the nodules’ non-silicate components, shows high concentrations of MnO, P2O5, and FeO and a molar ratio P/Mn = 2. Visible to near-infrared reflectance of the nodules (by ChemCam passive and Mastcam multispectral) is dark and relatively flat, consistent with a mixture of host siltstone, hematite, and a dark spectrally bland material (like pyrolusite, MnO2). A drill sample at the site is shown to contain minimal nodule material, implying that analyses by the CheMin and SAM instruments do not constrain the nodules’ mineralogy or composition. The fact that the nodules contain P and Mn in a small molar integer ratio, P/Mn = 2, suggests that the nodules contained a stoichiometric Mn-phosphate mineral, in which Fe did (i.e., could) not substitute for Mn. The most likely such minerals are laueite and strunzite, Mn2+Fe3+2(PO4)2(OH)2·8H2O and –6H2O, respectively, which occur on Earth as alteration products of other Mn-bearing phosphates including vivianite. Vivianite is a common primary and diagenetic precipitate from low-oxygen, P-enriched waters. Calculated phase equilibria show Mn-bearing vivianite could be replaced by laueite or strunzite and then by hematite plus pyrolusite as the system became more oxidizing and acidic. These data suggest that the nodules originated as vivianite, forming as euhedral crystals in the sediment, enclosing sediment grains as they grew. After formation, the nodules were oxidized—first to laueite/strunzite yielding the diagnostic P/Mn ratio, and then to hematite plus an undefined Mn oxy-hydroxide (like pyrolusite). The limited occurrence of these Mn-Fe-P nodules, both in space and time (i.e., stratigraphic position), suggests a local control on their origin. By terrestrial analogies, it is possible that the nodules precipitated near a spring or seep of Mn-rich water, generated during alteration of olivine in the underlying sediments.

Purpose: To evaluate satisfaction with work-life balance (WLB) and career plans of US oncologists., Methods: The American Society of Clinical Oncology conducted a survey of US oncologists evaluating satisfaction with WLB and career plans between October 2012 and March 2013. The sample included equal numbers of men and women from all career stages., Results: Of 2,998 oncologists contacted, 1,490 (49.7%) returned surveys. From 1,117 oncologists (37.3% of overall sample) completing full-length surveys, we evaluated satisfaction with WLB and career plans among the 1,058 who were not yet retired. The proportion of oncologists satisfied with WLB (n = 345; 33.4%) ranked lower than that reported for all other medical specialties in a recent national study. Regarding career plans, 270 oncologists (26.5%) reported a moderate or higher likelihood of reducing their clinical work hours in the next 12 months, 351 (34.3%) indicated a moderate or higher likelihood of leaving their current position within 24 months, and 273 (28.5%) planned to retire before 65 years of age. Multivariable analyses found women oncologists (odds ratio [OR], 0.458; P < .001) and those who devoted greater time to patient care (OR for each additional hour, 0.977; P < .001) were less likely to be satisfied with WLB. Satisfaction with WLB and burnout were the strongest predictors of intent to reduce clinical work hours and leave current position on multivariable analysis., Conclusion: Satisfaction with WLB among US oncologists seems lower than for other medical specialties. Dissatisfaction with WLB shows a strong relationship with plans to reduce hours and leave current practice. Given the pending US oncologist shortage, additional studies exploring interactions among WLB, burnout, and career satisfaction and their impact on career and retirement plans are warranted.