Ortho-to-para ratio of interstellar heavy water

Despite the low elemental deuterium abundance in the Galaxy, enhanced molecular D/H ratios have been found in the environments of low-mass star forming regions, and in particular the Class 0 protostar IRAS 16293-2422. The CHESS (Chemical HErschel Surveys of Star forming regions) Key Program aims at studying the molecular complexity of the interstellar medium. The high sensitivity and spectral resolution of the HIFI instrument provide a unique opportunity to observe the fundamental 1,1,1 - 0,0,0 transition of the ortho-D2O molecule, inaccessible from the ground, and to determine the ortho-to-para D2O ratio. We have detected the fundamental transition of the ortho-D2O molecule at 607.35 GHz towards IRAS 16293-2422. The line is seen in absorption with a line opacity of 0.62 +/- 0.11 (1 sigma). From the previous ground-based observations of the fundamental 1,1,0 - 1,0,1 transition of para-D2O seen in absorption at 316.80 GHz we estimate a line opacity of 0.26 +/- 0.05 (1 sigma). We show that the observed absorption is caused by the cold gas in the envelope of the protostar. Using these new observations, we estimate for the first time the ortho to para D2O ratio to be lower than 2.6 at a 3 sigma level of uncertainty, to be compared with the thermal equilibrium value of 2:1.Comment: 5 pages, 5 figures, accepted the A&A HIFI Special Issue as a lette

Greater short-term weight loss in women 20-45 versus 55-65 years of age following bariatric surgery

BACKGROUND: Whether and how sex and age affect bariatric-surgery outcome is poorly understood. Estrogens regulate body composition in women and animals, and increase weight loss in a rodent model of gastric bypass, suggesting that premenopausal women may lose more weight following bariatric surgery. METHODS: One thousand three hundred fifty-six female gastric-bypass or gastric-banding patients were retrospectively grouped as 20-45 years old (presumptively premenopausal; n = 1,199) and 55-65 years old (presumptively postmenopausal; n = 157). Mixed-model ANCOVA followed by Bonferroni-corrected t tests were used to categorically test the effect of age on percent excess body weight loss (%EBWL) at 1 and 2 years post-surgery, controlling for preoperative EBW and surgery type. Age effects were also tested dimensionally in all women and in 289 male patients. RESULTS: Twenty- to forty-five-year-old women showed greater %EBWL 1 and 2 years post-surgery than 55-65-year-old women (p's  0.2) This age effect was detected only after gastric banding, with 20-45-year-old women losing ∼7 kg more than 55-65-year-old women after 2 years. Dimensional analysis confirmed a significant inverse effect of age on bariatric surgery outcome in women, but did not detect any effect in men. CONCLUSIONS: Results indicate that 55-65-year-old women lose less weight than 20-45-year-old women in the initial 2 years after bariatric surgery, especially gastric banding; this may be mediated by age- or menopause-associated changes in physical activity, energy expenditure, or energy intake