Lunary Dust Grain Charging by Electron Impact: Complex Role of Secondary Electron Emissions in Space Environments

Dust grains in various astrophysical environments are generally charged electrostatically by photoelectric emissions with radiation from nearby sources, or by electron/ion collisions by sticking or secondary electron emissions (SEES). The high vacuum environment on the lunar surface leads to some unusual physical and dynamical phenomena involving dust grains with high adhesive characteristics, and levitation and transportation over long distances. Knowledge of the dust grain charges and equilibrium potentials is important for understanding a variety of physical and dynamical processes in the interstellar medium, and heliospheric, interplanetary/ planetary, and lunar environments. It has been well recognized that the charging properties of individual micron-/submicron-size dust grains are expected to be substantially different from the corresponding values for bulk materials. In this paper, we present experimental results on the charging of individual 0.2-13 m size dust grains selected from Apollo 11 and 17 dust samples, and spherical silica particles by exposing them to mono-energetic electron beams in the 10-200 eV energy range. The dust charging process by electron impact involving the SEES discussed is found to be a complex charging phenomenon with strong particle size dependence. The measurements indicate substantial differences between the polarity and magnitude of the dust charging rates of individual small-size dust grains, and the measurements and model properties of corresponding bulk materials. A more comprehensive plan of measurements of the charging properties of individual dust grains for developing a database for realistic models of dust charging in astrophysical and lunar environments is in progress

Sex hormone-binding globulin (SHBG), insulin and insulin-like growth factor-I (IGF-I) in anorexia nervosa: effect of refeeding

International audienc

Temporal variability and annual budget of inorganic dissolved matter in Andean Pacific Rivers located along a climate gradient from northern Ecuador to southern Peru

In Ecuador and Peru, geochemical information from Pacific coastal rivers is limited and scarce. Here, we present an unedited database of major element concentrations from five HYBAM observatory stations monitored monthly between 4 and 10 years, and the discrete sampling of 23 Andean rivers distributed along the climate gradient of the Ecuadorian and Peruvian Pacific coasts. Concentration (C) vs. discharge (Q) relationships of the five monitored basins exhibit a clear dilution behavior for evaporites and/or pyrite solutes, while the solute concentrations delivered by other endmembers are less variable. Spatially, the annual specific fluxes for total dissolved solids (TDS), Ca2+, HCO3 −, K+, Mg2+, and SiO2 are controlled on the first order by runoff variability, while Cl−, Na+ and SO4 2− are controlled by the occurrence of evaporites and/or pyrite. The entire Pacific basin in Ecuador and Peru exported 30 Mt TDS·yr−1, according to a specific flux of ∼70 t·km−2·yr−1. This show that, even under low rainfall conditions, this orogenic context is more active, in terms of solute production, than the global average

Temporal variability and annual budget of inorganic dissolved matter in Andean Pacific Rivers located along a climate gradient from northern Ecuador to southern Peru

In Ecuador and Peru, geochemical information from Pacific coastal rivers is limited and scarce. Here, we present an unedited database of major element concentrations from five HYBAM observatory stations monitored monthly between 4 and 10 years, and the discrete sampling of 23 Andean rivers distributed along the climate gradient of the Ecuadorian and Peruvian Pacific coasts. Concentration (C) vs. discharge (Q) relationships of the five monitored basins exhibit a clear dilution behavior for evaporites and/or pyrite solutes, while the solute concentrations delivered by other endmembers are less variable. Spatially, the annual specific fluxes for total dissolved solids (TDS), Ca2+, HCO3 −, K+, Mg2+, and SiO2 are controlled on the first order by runoff variability, while Cl−, Na+ and SO4 2− are controlled by the occurrence of evaporites and/or pyrite. The entire Pacific basin in Ecuador and Peru exported 30 Mt TDS·yr−1, according to a specific flux of ∼70 t·km−2·yr−1. This show that, even under low rainfall conditions, this orogenic context is more active, in terms of solute production, than the global average

Obesity management in women with polycystic ovary syndrome

Copyright © 2007 Future MedicineObesity and insulin resistance play an important role in initiating or maintaining ill health in polycystic ovary syndrome (PCOS). This implies that treatment that reduces body weight and insulin resistance would alleviate the symptoms of PCOS. Lifestyle modification has been found to be effective in restoring reproductive function in up to 80% of individuals who achieve at least 5% weight loss. However, long-term weight maintenance is a challenge. This article provides a review of reduced glycemic load diets, including low glycemic index, very low carbohydrate, high-protein and high monounsaturated fat diets, on metabolic and reproductive health in PCOS and non-PCOS populations. Dietary trials in non-PCOS women suggest that higher-protein, reduced glycemic load diets were probably more beneficial than the conventional low-fat, high-carbohydrate diet but further studies are required to confirm this in PCOS women. Similarly, the optimal exercise regime for PCOS women remains to be investigated.Siew S Lim, Peter M Clifton, Manny Noakes & Robert J Norma