Insights into magma ocean dynamics from the transport properties of basaltic melt.

The viscosity of magma plays a crucial role in the dynamics of the Earth: from the crystallization of a magma ocean during its initial stages to modern-day volcanic processes. However, the pressure-dependence behavior of viscosity at high pressure remains controversial. In this study, we report the results of first-principles molecular dynamics simulations of basaltic melt to show that the melt viscosity increases upon compression along each isotherm for the entire lower mantle after showing minima at ~6 GPa. However, elevated temperatures of the magma ocean translate to a narrow range of viscosity, i.e., 0.01-0.03 Pa.s. This low viscosity implies that the crystallization of the magma ocean could be complete within a few million years. These results also suggest that the crystallization of the magma ocean is likely to be fractional, thus supporting the hypothesis that present-day mantle heterogeneities could have been generated during the early crystallization of the primitive mantle.

Complex dietary protein improves growth through a complex mechanism of intestinal peptide absorption and protein digestion.

BACKGROUND: The small intestinal epithelium has an impressive ability to adapt to changes resulting from loss of length or alteration in dietary load. We sought to determine the potential influence of dietary protein absorption on growth and development. We hypothesized that a complex protein diet would improve growth over that of an elemental diet. METHODS: Using the nematode Caenorhabditis elegans, a transparent worm with a rudimentary intestinal tube lined by enterocytes that function remarkably similar to humans, we measured daily growth, intestinal peptide, and amino acid transporter expression and intestinal proteolysis to compare the effects of a complex protein diet to a diet containing only amino acids. RESULTS: Nematodes raised on a complex protein diet grew to adulthood faster than those raised solely on amino acids, which did not require an overall change in intestinal peptide or amino acid transporter expression. Despite no overall change in transporter expression, a shift in location of peptide transporter expression was noted between diets that corresponded to decreased rate of intestinal proteolysis seen in the complex protein-fed group. CONCLUSIONS: A complex protein diet stimulates in an altered pattern of intestinal peptide transporter expression and intestinal proteolytic activity that results in improved growth compared with a diet of elemental amino acids. This improved growth appears to be the result of increased efficiency of a smaller number of enterocytes. These data might be useful in targeting intestinal rehabilitation therapies for short bowel syndrome and other risk factors for intestinal failure.

Pilot study of a web-based intervention for adolescents with type 1 diabetes.

We evaluated the feasibility and effectiveness of a website designed to improve compliance to treatment protocols in adolescents with type-1 diabetes. Fifty-nine adolescents, 13-18 years of age, were randomly assigned to a control or experimental group. The control group received standard medical care as usual. The experimental group participated in an interactive, 7-week web-based intervention, taking part in problem-solving through discussion forums, chat rooms and blogs. Fifty of the 59 participants (85%) completed measures assessing diabetes-related quality of life, self-efficacy and outcome expectations. These variables were expected to be interrelated and their combined effects were considered as mediators of compliance. There was a marginally significant difference between the two groups on these combined measures (P = 0.052), with the control group scoring significantly higher on Positive Outcome Expectations (P = 0.03) both pre- and post-treatment. Attrition in the period between recruitment and the beginning of the intervention reduced power. Self-Efficacy was significantly correlated with Positive Outcome Expectations (r = 0.30, P = 0.037) and Diabetes Self-Management and Diabetes Quality of Life for Youths (r = 0.43, P = 0.002). In an exit survey, 90% of participants indicated that they were more willing to comply with their treatment protocol after participating in the intervention. An online website is a promising tool to bring adolescents with a chronic disease together, providing problem solving activities and social support.