Fine Grid Asteroseismology Of G117-B15A And R548

We now have a good measurement of the cooling rate of G117-B15A. In the near future, we will have equally well determined cooling rates for other pulsating white dwarfs, including R548. The ability to measure their cooling rates offers us a unique way to study weakly interacting particles that would contribute to their cooling. Working toward that goal, we perform a careful asteroseismological analysis of G117-B15A and R548. We study them side by side because they have similar observed properties. We carry out a systematic, fine grid search for best-fit models to the observed period spectra of those stars. We freely vary four parameters: the effective temperature, the stellar mass, the helium layer mass, and the hydrogen layer mass. We identify and quantify a number of uncertainties associated with our models. Based on the results of that analysis and fits to the periods observed in R548 and G117-B15A, we clearly define the regions of the four-dimensional parameter space occupied by the best-fit models.NSF AST 05-07639Astronom

How to select the doses of vitamin D in the management of osteoporosis

The dose of vitamin D in the management of osteoporosis should be no less than 700-800IU per day. An optimal dose of vitamin D should raise serum concentrations of 25(OH)D to the desirable range of at least 75nmol/l. Higher intermittent oral doses of vitamin D may overcome low adherence. Vitamin D supplementation in the management of osteoporosis holds a significant public health potential because of its low cost, excellent tolerability, and combined musculo-skeletal benefits. Fall and fracture prevention with vitamin D is especially appealing in the treatment of older individuals at risk for fall-related fractures. However, bone density, strength, and function benefits with vitamin D include active and inactive subgroups of community-dwelling older men and women. Based on a recent expert panel and supportive evidence presented in this review, serum concentrations of at least 75nmol/l 25(OH)D will be referred to as desirable. Today, desirable serum 25(OH)D levels of at least 75nmol/l may only be reached in about one third of US older individuals and even fewer European older individuals. Two main factors discussed in this review may help public health efforts to ensure desirable vitamin D levels for fall and fracture prevention, including (1) a sufficient dose of vitamin D and (2) improved adherence to supplementatio

Validated treatments and therapeutic perspectives regarding nutritherapy

Nutritherapy seeks to prevent or correct disease by the use of nutritional supplements including vitamins, trace elements, or macronutrients. This chapter of the "Les Entretiens du Carla” reviews the potential of nutritherapy for the prevention or improvement of sarcopenia, which is the progressive reduction in muscle mass and muscle strength prevalent in late-life. It is critical that we review nutrients and their potential to maintain muscle mass and strength which ultimately will help minimize falls and fractures among the older population. Evidence from randomized-controlled trials will be reviewed for muscle mass as well as important sarcopenia-related endpoints including lower extremity strength and function, as well as falls and fallrelated fractures. This chapter will focus on vitamin D as a compelling strategy with evidence for strength gain, fall and fracture prevention from double-blind randomized controlled trials. The other strategy discussed is increased protein intake although longer-term trials and evidence for clinically important endpoints are limited. Today, there is no consistent data on other micronutrients or macronutrients with an established potential to combat sarcopeni

Optimum Irrigation Loading Rates of Highly Saline Wastewater on a Montmorillonitic Soil

Annual applications of 125, 90, and 50 cm of secondary-treated municipal effluent were applied to a 0.76 cm/hr glaciated soil growing alfalfa for 3 years. All treatments had weekly applications with the depth of application varying from 1.5-3.2 cm for the low rate plot to 3.8-8 cm for the high plot. The amounts applied paralleled the evapotranspiration curve of the crop with weekly applications lowest in the spring and fall and highest during the summer. Water quality varied from 1500-3000 Siemens /cm for the electrolyte concentration, from 5-11 for the sodium adsorption ratio, and from 0.1-12. 4 ppm for nitrate nitrogen. A water table developed within 1.2 meters of the surface for the 90 cm plot (treatment 35G) and within 1.1 meters of the surface on the 125 cm plot (treatment 50) at the end of the second irrigation season. Treatment 50 had lost 1-2% of the plant population at the end of the second year and 15-20% by the end of the third year of irrigating. Leaching fractions of 0.08-0.10 for total moisture should not be exceeded to prevent water table problems from developing near the surface. Annual soil applications of gypsum were added to the 90 cm plot (treatment 35G) to determine the efficiency in removing exchangeable sodium from the soil colloid exchange sites. After two annual applications of powdered gypsum, no significant difference between the gypsum plot (treatment 35G) and the non-gypsum plot (treatment 35) was detected in the top 1.2 meters. However, the sodium level for 35G in observation wells at the center of the plot were 2-5 times higher than the non-gypsum plot with the same annual rate of effluent. Sulphate levels were 4-8 times higher on 35G versus 35 and magnesium was 4 times higher. Calcium was replacing magnesium and sodium on the exchange complex at depths below 1.2 meters. Nitrate levels in the soil varied according to the nitrate levels in the effluent. In situ soil water extracts were monitored with depth and time across treatments. There was no difference in the nitrate levels in the soil according to treatment. Nitrate nitrogen levels were the highest in the ground waters beneath the plot with the thickest sand layer in the subsoil. Soil dispersion caused by sodic irrigation water for the top 3 cm of soil was evident at the end of the three-year project on the 50 cm annual application plot (treatment 20). Concentrating effects of ET and low leaching caused high sodium adsorption ratios of the soil solution during the irrigation season on treatment 20. Treatments 50, 35, and 35G did not show signs of soil dispersion on the top 3 cm

Neural Networks for Impact Parameter Determination

An accurate impact parameter determination in a heavy ion collision is crucial for almost all further analysis. The capabilities of an artificial neural network are investigated to that respect. A novel input generation for the network is proposed, namely the transverse and longitudinal momentum distribution of all outgoing (or actually detectable) particles. The neural network approach yields an improvement in performance of a factor of two as compared to classical techniques. To achieve this improvement simple network architectures and a 5 by 5 input grid in (p_t,p_z) space are sufficient.Comment: Phys. Rev. C in print. Postscript-file also available at http://www.th.physik.uni-frankfurt.de/~bass/pub.htm

A New Timescale for Period Change in the Pulsating DA White Dwarf WD 0111+0018

We report the most rapid rate of period change measured to date for a pulsating DA (hydrogen atmosphere) white dwarf (WD), observed in the 292.9 s mode of WD 0111+0018. The observed period change, faster than 10^{-12} s/s, exceeds by more than two orders of magnitude the expected rate from cooling alone for this class of slow and simply evolving pulsating WDs. This result indicates the presence of an additional timescale for period evolution in these pulsating objects. We also measure the rates of period change of nonlinear combination frequencies and show that they share the evolutionary characteristics of their parent modes, confirming that these combination frequencies are not independent modes but rather artifacts of some nonlinear distortion in the outer layers of the star.Comment: 10 pages, 6 figures, accepted for publication in The Astrophysical Journa