The key physical parameters governing frictional dissipation in a precipitating atmosphere

Precipitation generates small-scale turbulent air flows the energy of which ultimately dissipates to heat. The power of this process has previously been estimated to be around 2-4 W m-2 in the tropics: a value comparable in magnitude to the dynamic power of the global circulation. Here we suggest that this previous power estimate is approximately double the true figure. Our result reflects a revised evaluation of the mean precipitation path length Hp. We investigate the dependence of Hp on surface temperature,relative humidity,temperature lapse rate and degree of condensation in the ascending air. We find that the degree of condensation,defined as the relative change of the saturated water vapor mixing ratio in the region of condensation, is a major factor determining Hp. We estimate from theory that the mean large-scale rate of frictional dissipation associated with total precipitation in the tropics lies between 1 and 2 W m-2 and show that our estimate is supported by empirical evidence. We show that under terrestrial conditions frictional dissipation constitutes a minor fraction of the dynamic power of condensation-induced atmospheric circulation,which is estimated to be at least 2.5 times larger. However,because Hp increases with surface temperature Ts, the rate of frictional dissipation would exceed that of condensation-induced dynamics, and thus block major circulation, at Ts >~320 K in a moist adiabatic atmosphere.Comment: 12 pp, 2 figure

Genetic analysis of a major international collection of cultivated apple varieties reveals previously unknown historic heteroploid and inbred relationships

Domesticated apple (Malus x domestica Borkh.) is a major global crop and the genetic diversity held within the pool of cultivated varieties is important for the development of future cultivars. The aim of this study was to investigate the diversity held within the domesticated form, through the analysis of a major international germplasm collection of cultivated varieties, the UK National Fruit Collection, consisting of over 2,000 selections of named cultivars and seedling varieties. We utilised Diversity Array Technology (DArT) markers to assess the genetic diversity within the collection. Clustering attempts, using the software STRUCTURE revealed that the accessions formed a complex and historically admixed group for which clear clustering was challenging. Comparison of accessions using the Jaccard similarity coefficient allowed us to identify clonal and duplicate material as well as revealing pairs and groups that appeared more closely related than a standard parent-offspring or full-sibling relations. From further investigation, we were able to propose a number of new pedigrees, which revealed that some historically important cultivars were more closely related than previously documented and that some of them were partially inbred. We were also able to elucidate a number of parent-offspring relationships that had resulted in a number of important polyploid cultivars. This included reuniting polyploid cultivars that in some cases dated as far back as the 18th century, with diploid parents that potentially date back as far as the 13th century

Biological Notes On Drosophila Guttifera (Diptera, Drosophilidae), A Consumer Of Mushrooms

Volume: 101Start Page: 161End Page: 16

Acalyptrate Diptera Reared From Higher Fungi In Northeastern Ohio

Volume: 101Start Page: 117End Page: 12

Physiological Predictors of Increasing Total and Central Adiposity in Aging Men and Women

BACKGROUND: Increasing levels of total and central body fat with advancing age contribute to the development of cardiovascular and metabolic disease. We examined gender-related differences and physiological predictors of the rate of increase in total and central body fat in men and women. METHODS: We studied 427 healthy men (age range, 17 to 90 years) and 293 women (age range, 18 to 88 years). We measured body fatness by hydrostatic weighing, central adiposity from the waist circumference, peak volume of oxygen utilization (V̇O2) from a treadmill test, leisure time physical activity (LTA) from a questionnaire, resting metabolic rate and respiratory quotient from indirect calorimetry, and energy intake from 3-day food diaries. RESULTS: Fat mass increased with age, and the rate was greater in women (r=.61; slope=0.25 kg/y; P<.01) than in men (r=.43; slope=0.16 kg/y; P<.01). Increasing fat mass in men and women was most strongly associated with declines in peak V̇O2 and LTA. Controlling for these variables reduced the increase in fat mass from 17% to 3% per decade in men and from 26% to 5% per decade in women. The increase in waist circumference with age was also greater in women (r=.53; slope=0.28 cm/y) than in men (r=.39; slope=0.18 cm/y; P<.01). Increasing waist circumference with age in men and women was most strongly associated with declines in LTA and peak V̇O2, respectively. Control for these variables reduced the age-related increase in waist circumference from 2% to 1% per decade in men and from 4% to 1% per decade in women. We observed no independent contribution of resting metabolic rate, respiratory quotient, menopause status, energy, or macronutrient intake to the age-related increase in fat mass and waist circumference. CONCLUSIONS: Our findings suggest that (1) the age-related increase in fat mass and waist circumference is greater in women than in men and (2) the physiological characteristics that reflect a decline in physical activity—related energy expenditure, rather than resting energy expenditure, are important predictors of the increases in total and central fatness. Lifestyle changes that increase the level of physical activity may be advantageous in blunting age-related increases in total and central body fatness.(Arch Intern Med. 1995;155:2443-2448