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Abstract: High-fidelity computational simulation can be an invaluable tool in planning strategies for hazard risk mitigation. The accuracy and reliability of the predictions are crucial elements of these tools being successful. We present here a new simulation tool for dry granular avalanches using several new techniques for enhancing numerical solution accuracy. Highlights of our new methodology are the use of a depth-averaged model of the conservation laws and an adaptive grid Godunov solver to solve the resulting equations. The software is designed to run on distributed memory supercomputers and makes use of digital elevation data dynamically, i.e., refine the grid and input data to finer resolutions to better capture flow features as the flow evolves. Our simulations are validated using quantitative and qualitative comparisons to tabletop experiments and data from field observations. Our software is freely available and uses only publicly available libraries and hence can be used on a wide range of hardware and software platforms. [Copyright &y& Elsevier]

Abstract: This paper describes the development of highly accurate adaptive discontinuous Galerkin schemes for the solution of the equations arising from a thin layer type model of debris flows. Such flows have wide applicability in the analysis of avalanches induced by many natural calamities, e.g. volcanoes, earthquakes, etc. These schemes are coupled with special parallel solution methodologies to produce a simulation tool capable of very high-order numerical accuracy. The methodology successfully replicates cold rock avalanches at Mount Rainier, Washington and hot volcanic particulate flows at Colima Volcano, Mexico. [Copyright &y& Elsevier]

Abstract: Islet culture has emerged as a standard practice prior to clinical transplantation. However, culturing large numbers of islets requires low islet density (number of islets per unit surface area) and, consequently, 20 to 30 flasks per pancreas in order to avoid hypoxia-induced death (HID). There is a need for a simple, practical, small-footprint culture vessel that will accommodate aseptic maintenance of entire human islet isolations while avoiding HID. In this communication, we examine the hypothesis that by improving oxygen transfer through culture of islets on silicone rubber membranes (SRM), we may increase islet surface coverage and reduce the number of flasks required while avoiding HID. Our results demonstrate that islets cultured for up to 48 hours in vessels with SRM bottoms at 2000 to 4000 islet equivalents (IE)/cm2, a surface coverage 10- to 20-fold higher than the standard culture protocol, displayed no significant loss of viability. In contrast, islets cultured for 48 hours at 4000 IE/cm2 in flasks with gas-impermeable bottoms suffered a 60% to 70% reduction in viability. The data suggest that it is possible to culture all islets isolated from a human pancreas on SRM in a single, standard-sized vessel while maintaining the same viability as with the current, standard culture protocols that require 20 to 30 flasks. This approach may lead to substantial improvements in islet culture for research and clinical transplantation. [Copyright &y& Elsevier]