Dynamical evolution of high velocity clouds in the intergalactic medium

HI observations of high-velocity clouds (HVCs) indicate, that they are interacting with their ambient medium. Even clouds located in the very outer Galactic halo or the intergalactic space seem to interact with their ambient medium. In this paper, we investigate the dynamical evolution of high velocity neutral gas clouds moving through a hot magnetized ambient plasma by means of two-dimensional magnetohydrodynamic plasma-neutral gas simulations. This situation is representative for the fast moving dense neutral gas cloudlets in the Magellanic Stream as well as for high velocity clouds in general. The question on the dynamical and thermal stabilization of a cold dense neutral cloud in a hot thin ambient halo plasma is numerically investigated. The simulations show the formation of a comet-like head-tail structure combined with a magnetic barrier of increased field strength which exerts a stabilizing pressure on the cloud and hinders hot plasma from diffusing into the cloud. The simulations can explain both the survival times in the intergalactic medium and the existence of head-tail high velocity clouds.Comment: 11 pages, 19 figure

EFFECTS OF WEIGHT LOSS ON VISCERAL ADIPOSITY AND METABOLIC ADAPTATIONS IN DIABETIC VERSUS NON-DIABETIC WOMEN

Obesity increases the risk for the development of cardiovascular disease, type 2 diabetes and other co-morbid conditions. Type 2 diabetes also is often associated with excessive visceral abdominal fat. Weight loss in obese individuals decreases the risk for developing the co-morbid conditions. Individuals with type 2 diabetes often have a greater difficulty in controlling these complications compared to individuals without type 2 diabetes. The purpose of this study was to evaluate adherence to a medically-supervised low-energy diet (LED) weight loss program and changes in body composition and metabolic parameters after weight loss in women with and without type 2 diabetes. Subjects consisted of Caucasian women, between the ages of 40 to 65 years, with BMIs between 30 and 45 kg/m2. There was no significant difference in BMI between the groups at study initiation (38.1 kg/m2, diabetics (DM) and 36.0 kg/m2, non-diabetics (NDM), p=0.2314). All subjects participated in the HMR Program for 16 weeks. Twenty-nine subjects completed the weight loss phase (18 diabetics, 11 non-diabetics) and were evaluated for change in weight, body composition, and blood parameters. Data were analyzed by repeated-measures ANCOVA and students t-tests using SAS version 8.02. DM and NDM lost 11.7% and 16% of body weight, respectively (p=0.6474). Results indicate DM has more total lean tissue (p=0.004), more total body fat (p=0.04), more total abdominal tissue (p=0.001), more visceral adipose tissue (p=0.001) and lost less percent body fat (p=0.04) than NDM after 16 weeks of weight loss. After weight loss there was no significant difference in leptin, ghrelin or adiponectin levels. DM had greater insulin (p=0.05), HOMA-IR (pandlt;0.0001), glucose (pandlt;0.0001), HbA1c (pandlt;0.0001), resistin (p=0.04) and PAI-1 (p=0.02). There were no differences after weight loss in lipid levels, blood pressure, diet compliance or exercise. The data show that medically-supervised LEDs are safe and effective for treating obesity in individuals with type 2 diabetes. Cardiovascular risk factors improved in both NDM and DM subjects with weight loss. The findings also suggest that insulin and metabolically dysfunctional lean tissue may play a critical role in the complex axes affecting changes in body composition and inflammation in individuals with type 2 diabetes

Feasibility Study of Economics and Performance of Solar Photovoltaics at the Crazy Horse Landfill Site in Salinas, California. A Study Prepared in Partnership with the Environmental Protection Agency for the RE-Powering America's Land Initiative: Siting Renewable Energy on Potentially Contaminated Land and Mine Sites

The U.S. Environmental Protection Agency (EPA), in accordance with the RE-Powering America's Land initiative, selected the Crazy Horse Landfill site in Salinas, California, for a feasibility study of renewable energy production. The National Renewable Energy Laboratory (NREL) was contacted to provide technical assistance for this project. The purpose of this report is to assess the site for a possible photovoltaic (PV) system installation and estimate the cost, performance, operation and maintenance requirements, and site impacts of different PV options. In addition, the report recommends financing options that could assist in the implementation of a PV system at the site

Comparison of light transmission and reflection techniques to determine concentrations in flow tank experiments

Transmissive and reflective intensity measurements for visual concentration determinations in 2D flow tank experiments were compared and evaluated for their applicability in the study of flow and transport phenomena. A density-dependent heterogeneous flow experiment was conducted and transmission and reflection images of the dyed saltwater plume were analyzed. A single light source and dark curtains forced the light to pass through the porous media only, thus facilitating the transmission measurements. The reflection images delivered a more homogeneous spatial illumination than the transmission images. Major perturbations of the transmission images were lens flare effects and light dispersion within the bead-water-Plexiglas system which smear the front of the plume. Based on the conducted evaluation of transmissive and reflective intensity measurements, the reflection data delivered more reliable intensity values to derive solute concentrations in intermediate scale flow tank experiment

Robust Chauvenet Outlier Rejection

Sigma clipping is commonly used in astronomy for outlier rejection, but the number of standard deviations beyond which one should clip data from a sample ultimately depends on the size of the sample. Chauvenet rejection is one of the oldest, and simplest, ways to account for this, but, like sigma clipping, depends on the sample's mean and standard deviation, neither of which are robust quantities: Both are easily contaminated by the very outliers they are being used to reject. Many, more robust measures of central tendency, and of sample deviation, exist, but each has a tradeoff with precision. Here, we demonstrate that outlier rejection can be both very robust and very precise if decreasingly robust but increasingly precise techniques are applied in sequence. To this end, we present a variation on Chauvenet rejection that we call "robust" Chauvenet rejection (RCR), which uses three decreasingly robust/increasingly precise measures of central tendency, and four decreasingly robust/increasingly precise measures of sample deviation. We show this sequential approach to be very effective for a wide variety of contaminant types, even when a significant -- even dominant -- fraction of the sample is contaminated, and especially when the contaminants are strong. Furthermore, we have developed a bulk-rejection variant, to significantly decrease computing times, and RCR can be applied both to weighted data, and when fitting parameterized models to data. We present aperture photometry in a contaminated, crowded field as an example. RCR may be used by anyone at https://skynet.unc.edu/rcr, and source code is available there as well.Comment: 62 pages, 48 figures, 7 tables, accepted for publication in ApJ

Theology, Mission and Child: Global Perspectives

In our view there are three primary and equally constituent parts to the volume we have been commissioned to edit and collate, and these are therefore indicated in the title.https://scholar.csl.edu/edinburghcentenary/1023/thumbnail.jp

Shear-Flow Driven Current Filamentation: Two-Dimensional Magnetohydrodynamic Simulations

The process of current filamentation in permanently externally driven, initially globally ideal plasmas is investigated by means of two-dimensional Magnetohydrodynamic (MHD)-simulations. This situation is typical for astrophysical systems like jets, the interstellar and intergalactic medium where the dynamics is dominated by external forces. Two different cases are studied. In one case, the system is ideal permanently and dissipative processes are excluded. In the second case, a system with a current density dependent resistivity is considered. This resistivity is switched on self-consistently in current filaments and allows for local dissipation due to magnetic reconnection. Thus one finds tearing of current filaments and, besides, merging of filaments due to coalescence instabilities. Energy input and dissipation finally balance each other and the system reaches a state of constant magnetic energy in time.Comment: 32 Pages, 13 Figures. accepted, to appear in Physics of Plasmas (049012