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

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

Infinite index extensions of local nets and defects

Subfactor theory provides a tool to analyze and construct extensions of Quantum Field Theories, once the latter are formulated as local nets of von Neumann algebras. We generalize some of the results of [LR95] to the case of extensions with infinite Jones index. This case naturally arises in physics, the canonical examples are given by global gauge theories with respect to a compact (non-finite) group of internal symmetries. Building on the works of Izumi, Longo, Popa [ILP98] and Fidaleo, Isola [FI99], we consider generalized Q-systems (of intertwiners) for a semidiscrete inclusion of properly infinite von Neumann algebras, which generalize ordinary Q-systems introduced by Longo [Lon94] to the infinite index case. We characterize inclusions which admit generalized Q-systems of intertwiners and define a braided product among the latter, hence we construct examples of QFTs with defects (phase boundaries) of infinite index, extending the family of boundaries in the grasp of [BKLR16].Comment: 50 page

Relaciones foréticas entre ácaros (Acaridae y Chaetodactylidae) e himenópteros (Anthophoridae, Xylocopinae)

Fil: Abrahamovich, Alberto H.. División Entomología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Bischoff de Alzuet, Alcira D.. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin

Deutoninfas (Hypopi) de los géneros Sennertia Oudemans, 1905 y Horstia Oudemans, 1905 (Acari: Astigmata) sobre Xylocopa (S.) splendidula splendidula Lepeletier, 1841 (Hymenoptera: Apoidea)

Fil: Bischoff de Alzuet, Alcira D.. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Abrahamovich, Alberto H.. División Entomología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin