Ion-beam doping during molecular beam epitaxy

Compositional modifications on the atomic scale, made possible through molecular beam epitaxy, have opened up a new range of semiconductor devices. Some recent work has investigated the addition of ion dopants during molecular beam epitaxy, with the goal of improving electrical and optical properties.     

Effects of veratridine on the action potentials and contractility of right and left ventricles from normo- and hypertensive rats

Induction of nitric oxide synthase and generation of nitric oxide in pancreatic islet beta-cells may mediate cytokine-induced dysfunction leading to insulin-dependent diabetes mellitus. Nitric oxide generation can be regulated by availability of arginine substrate which, in turn, may be affected by substrate utilization in competing pathways such as the arginase-catalysed formation of ornithine and urea. In this study we have investigated the activity of arginase in the rat insulinoma-derived cell line RINm5F and the effect on this of interleukin 1beta, the nitric oxide synthase reaction intermediate NG-hydroxy-l-arginine and the nitric oxide-generating compounds 3-morpholinosydnonimine and S-nitrosoglutathione. Cytosols from RINm5F cells treated with or without interleukin 1beta (0.1nM, 18h) were incubated (45min, 37 degrees C) with [U-14C]arginine. Radiolabelled products ([14C]citrulline from nitric oxide synthase, [14C]ornithine and [14C]urea from arginase) were separated by high-performance liquid chromatography or ion-exchange chromatography. Interleukin 1beta increased citrulline production (from 0.01+/-0.002 to 0.58+/-0.03 pmol/microg cell protein), indicating induction of nitric oxide synthase, and significantly decreased production of both ornithine (from 4.60+/-0.20 to 3.40+/-0.20 pmol/microg) and urea (0.93+/-0.05 to 0.69+/-0.04 pmol/microg) (P<0.001), indicating decreased activity of arginase. Arginase was significantly inhibited by NG-hydroxy-l-arginine (IC50=50 microM), S-nitrosoglutathione (500 microM: 69+/-7% of control) and 3-morpholinosydnonimine (1 mM: 57+/-7% of control) (P<0.05). We conclude that during cytokine-directed beta-cell assault nitric oxide synthase-catalysed production of NG-hydroxy-l-arginine and nitric oxide may inhibit arginase thereby increasing the availability of arginine for nitric oxide production.     

pH and Acid Anion Time Trends in Different Elevation Ranges in the Great Smoky Mountains National Park

Quarterly base flow water quality data collected from October, 1993 to November, 2002 at 90 stream sites in the Great Smoky Mountains National Park were used in step-wise multiple linear regression models to analyze pH, acid neutralizing capacity (ANC), and sulfate and nitrate long-term time trends. The potential predictor variables included cumulative Julian day, seasonality, elevation, basin slope, stream order, precipitation, surrogate streamflows, geology, and acid depositional fluxes. Modeling revealed statistically significant decreasing trends in pH and sulfate with time at lower elevations, but generally no long-term time trends in stream nitrate or ANC. The best forecasting models were chosen based on maximizing the r2 of a holdout data set. If conditions remain the same and past trends continue, the forecasting models suggest that 30.0% of the sampling sites will reach pH values less than 6.0 in less than 10?years, 63.3% in less than 25?years, and 96.7% in less than 50?years. The pH forecasting models explain 65% of the variability in the holdout data.     

The originality of Kandinsky's compositions

Vasily Kandinsky (1866–1944) is one of the most original artists and thinkers of our century. His work presents radically new ways of visually expressing images and meanings. Through analysis of major works of art and citations from the artist's writings, this paper introduces Kandinsky's practice and theory of composition to a general audience. His most distinctive compositional devices — the use of multiple foci, the articulation or blunting of corners, the placement and coloring of weighty forms, the disassociation of color from line and the scattering of compositional elements — are illustrated in each of the main phases of his career.     

Women and gender in research on work and family stress.

Research on work-related stress has tended to focus on males and to neglect gender as a variable; often, findings from studies of men are incorrectly generalized to women. The failure to "build women in" to conceptual models has impaired our understanding of both work and family role stressors. This article focuses on assumptions, gaps, and biases in the literature; the home, for example, has been viewed as a stress-free sanctuary, whereas workplace stress has been overemphasized and seen as particularly dangerous for women. To better understand the costs and benefits of employment and of multiple roles for women, and the stressfulness of family roles, more attention to the qualitative aspects of roles is needed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)