The natural space environment: Effects on spacecraft

The effects of the natural space environments on spacecraft design, development, and operation are the topic of a series of NASA Reference Publications currently being developed by the Electromagnetics and Environments Branch, Systems Analysis and Integration Laboratory, Marshall Space Flight Center. This primer provides an overview of the natural space environments and their effect on spacecraft design, development, and operations, and also highlights some of the new developments in science and technology for each space environment. It is hoped that a better understanding of the space environment and its effect on spacecraft will enable program management to more effectively minimize program risks and costs, optimize design quality, and successfully achieve mission objectives

Fast Simulation of Mass-Spring Systems

We describe a scheme for time integration of mass-spring systems that makes use of a solver based on block coordinate descent. This scheme provides a fast solution for classical linear (Hookean) springs. We express the widely used implicit Euler method as an energy minimization problem and introduce spring directions as auxiliary unknown variables. The system is globally linear in the node positions, and the non-linear terms involving the directions are strictly local. Because the global linear system does not depend on run-time state, the matrix can be pre-factored, allowing for very fast iterations. Our method converges to the same final result as would be obtained by solving the standard form of implicit Euler using Newton’s method. Although the asymptotic convergence of Newton’s method is faster than ours, the initial ratio of work to error reduction with our method is much faster than Newton’s. For real-time visual applications, where speed and stability are more important than precision, we obtain visually acceptable results at a total cost per timestep that is only a fraction of that required for a single Newton iteration. When higher accuracy is required, our algorithm can be used to compute a good starting point for subsequent Newton’s iteration

Long-Term Effects of Land Application of Domestic Wastwater: Tooele, Utah, Slow-Rate Site, Volume 1: Field Investigation

Application of wastewater to the land has been designated a viable alternative for wastewater treatment by the Water Pollution Act Amendments of 1972 (PL 92-500). However, very little information is available concerning the long-term effects of applying wastewater to the land. The general objective of this study was to determine the long-term effects of employing secondary treated municipal wastewater as irrigation water. The study compared the quality of soils, crops, groundwater, and applied water to a site receiving normal irrigation water (control site) to a site (treated site) which had utilized seondary treated municipal effluent for irrigation water during a 20-year period. Similar management practices were employed at both sites

Evaluation of the Long Term Effects of Irrigation with Wastewater

Introduction: Background: The application of municipal wastewater to the land or using the soil mantle as a wastewater treatment system has been practiced for many years. The history of land application dates back to ancient Athens. Sewage farming or the transportation of wastewater to rural areas for irrigation and disposal was practiced in Eurpose as early as 1559. The practice became fairly widespread in England, France, Germany, Poland, Austria, and the United States during the late 1800\u27s

Pharmacological Inhibition of mTOR and ERK1/2 Resulted in Attenuated Protein Synthesis Rates in Differentiated C2C12 Myoblasts in a Similar Fashion to in vivo Rodent Studies.

Fractional protein synthesis rates have long been used as in indicator of acute alterations in the anabolic state of various tissues. Through the use of a number of stable and isotopic tracer methodologies, the measurement of fractional synthesis rates (FSR) in vivo has become a staple of skeletal muscle physiology. Through the application of a deuterium oxide tracer, this project sought to measure pharmacological perturbations in fractional synthesis rates in culture in differentiated C2C12 murine myotubes. PURPOSE: To assess myofibrillar protein FSR in differentiated C2C12 murine myotubes following pharmacological inhibition of rapamycin-sensitive (mTOR) or -insensitive (ERK1/2) pathways, and how signal transduction through these pathways impact FSR as compared to previous in vivo studies of pharmacological inhibition studies in skeletal muscle. METHODS: C2C12 murine myoblasts were cultured in collagen coated 6 well culture dishes, and grown to 60-70% confluency using a high glucose DMEM growth media (GM). Cultures were transitioned to a differentiation media (DM) upon reaching target confluency. DM was changed daily for 4 days to allow for complete differentiation to myotubes. Cultures were randomly assigned treatment conditions of cell control (CC), rapamycin inhibition (RAPA), ERK1/2 inhibition (ERK), and electrical stimulation (ESTIM). Cultures underwent treatment conditions for 24 hours with a 4% deuterium oxide GM supplement. Analysis was carried out using a gas chromatography mass spectrometer. RESULTS: Fractional rates of protein synthesis were significantly lower in the RAPA (p=0.028) and ERK (p=0.029) groups as compared to CC, with no differences between RAPA and ERK groups (p\u3e0.05). Although statistics were not applied to the ESTIM group due to low sample size, electrical pulse stimulation shows promise for the stimulation of FSR in cultured myotubes. CONCLUSION: Diminished FSR in both RAPA and ERK groups are consistent with previous findings from in vivo rodent studies. These results may indicate comparable alterations in skeletal muscle anabolic signaling in cell culture as well as in vivo rodent models. Further investigations into anabolic signaling mechanisms related to the control of protein synthesis are needed