Group feeding and predatory behavior of the flatworm Dugesia tigrina on the isopod Caecidota sp.

Includes bibliographical references.The purpose of this project was to evaluate the effect of predator group size on per capita ingestion rates of the flatworm Dugesia tigrina, and to determine whether an optimum group size exists. In previous experiements performes by Cash et al. (1993,1995), it was determined that when Dugesia was fed Daphnia and mosquito larvae, per capita ingestion rates were higher in predator groups of four and eight. My project was designed to determine if the same pattern would be found if the flatworms were given isopods (Caecidotea sp.,) to prey upon, which are benthic organisms. To accomplish this, flatworms were maintained in groups of one, two , four, eight, ten, and sixteen, and were fed a constant ratio of three isopods per predator. Each experiment was run for five days, counting and replacing eaten prey daily. A total of six experiments were performed, three of which included a mesh screening in the bottom of the dishes. Per capita ingestion rates were determined and analyzed. The results showed no significant difference in per capita ingestion rates between group sizes. However, there was a significant overall decrease in per capita rates among the flatworms in the dishes containing screen compared to those without the screen. It is hypothesized that the screen enabled the isopods to more easily escape predation by the flatworms. It is thought that, in addition to a food source, this may be one reason that isopods in natural environments are found on the undersides of dead leaves and vegetation.B.S. (Bachelor of Science

Breaking the Rocket Equation: How Refuellable Spacecraft Change the Dynamics of Space Transportation

One of the chief tenets of space transportation has been the immutability of the Tsiolkovsky rocket equation, placing great emphasis on the specific impulse of a thruster to determine the propellant mass. For applications where all propellant must be carried from the start, this drives most vehicle designs to the highest possible ISP. The compromise is the typical tradeoff between ISP and thrust magnitude. Thus, transfers which require either impulsive maneuvers or a tight timeline will favor low-ISP platforms. If adequate infrastructure is provided to allow for a refuellable spacecraft, a smaller and lighter vehicle can be used. This vehicle will have a payload mass fraction more in line with an equivalent system with many multiples higher specific impulse. As effective specific impulse increases to values approaching the highest performance electric propulsion systems, the time to destination remains of the same order of magnitude as an impulsive orbital maneuver. Further work must be done to optimize for the positioning and design of fuel depot infrastructure, especially bearing in mind both interactions with high radiation in the Van Allen belts, and ideal orbital planes to seed with these refuel depots

Malondialdehyde Acetaldehyde Adducts (MAA-Adducts) Direct Distinctive Pro-Inflammatory Responses in Endothelial and Macrophage Cell Lines

Chronic inflammation plays a critical role in the pathogenesis of atherosclerosis. At present, the mechanism(s) by which inflammation contributes to this disease isnot entirely understood. Inflammation is known to induce oxidative stress, of which one consequence is lipid peroxidation. This process leads to the production of malondialdehyde (MDA), which can subsequently break down to form acetaldehyde (AA). These two aldehyde by-products can covalently interact with the ε-amino group of lysineswithin proteins and lipoproteins leading to the formation of highly immunogenic malondialdehyde-acetaldehyde adducts (MAA-adducts). The aim of this study was to determine the in-vitro cytokine response of endothelial cells and macrophages treated with MAA-modified human serum albumin (HSA-MAA) and low-density lipoprotein (LDL-MAA). In addition, cells isolated from mice with exposure to MAA and high fat diets were stained and imaged for uptake of the modified macromolecules of interest. We found that exposure of endothelial cells resulted in increased expression of IL-6, TNF-α, ICAM-1, VCAM-1, and MCP-1 in response to incubation with HSA-MAA; whereas, the same treatment of macrophages resulted in increased expression of IL-6, TNF-α, and IL-1b. LDL-MAA incubationresulted in increased TNF-α expression in macrophages, but MCP-1 was elevated in endothelial cells. Interestingly, the quantitative and qualitative uptake of triglycerides was increased in both endothelial and macrophage cells when exposed to LDL-MAA compared to LDL alone. The results of these studies demonstrate that different MAA-adducts elicit unique responses in different cell types. Additionally, the presence of MAA appears to modulate the cells leading to increased uptake of triglycerides and further progression of the inflammatory response.https://digitalcommons.unmc.edu/emet_posters/1003/thumbnail.jp

TECHNICAL AND REGULATORY CONSIDERATIONS IN USING FREIGHT CONTAINERS AS INDUSTRIAL PACKAGES

The United States (US) Department of Energy (DOE), Office of Environmental Management (EM), is actively pursuing activities to reduce the radiological risk and clean up the environmental legacy of the nation's nuclear weapons programs. EM has made significant progress in recent years in the clean-up and closure of sites and is also focusing on longer-term activities necessary for the completion of the clean-up program. The packaging and transportation of contaminated demolition debris and low-level waste (LLW) materials in a safe and cost-effective manner are essential in completing this mission. Toward this end, the US Department of Transportation's (DOT) Final Rule on Hazardous Materials Regulation Final Rule issued January 26, 2004, included a new provision authorizing the use of Freight Containers (e.g., 20 and 40-foot ISO Containers) as Industrial Packages Type 1, 2, or 3 (IP-1, IP-2, and IP-3). This paper will discuss the technical and regulatory considerations in using these newly authorized and large packages for the packaging and transportation of LLW materials

Magnetic Gaps related to Spin Glass Order in Fermionic Systems

We provide evidence for spin glass related magnetic gaps in the fermionic density of states below the freezing temperature. Model calculations are presented and proposed to be relevant for explaining resistivity measurements which observe a crossover from variable-range- to activated behavior. The magnetic field dependence of a hardgap and the low temperature decay of the density of states are given. In models with fermion transport a new metal-insulator transition is predicted to occur due to the spin-glass gap, anteceding the spin glass to quantum paramagnet transition at smaller spin density. Important fluctuation effects due to finite range frustrated interactions are estimated and discussed.Comment: 4 pages, 1 Postscript figure, revised version accepted for publication in Physical Review Letter

Superconducing Alloys with Weak and Strong Scattering: Anderson's Theorem and a Superconductor-Insulator Transition

We have studied the effects of strong impurity scattering on disordered superconductors beyond the low impurity concentration limit. By applying the full CPA to a superconductiong A-B binary alloy, we calculated the fluctuations of the local order parameters $\Delta_{A}, \Delta_{B}$ and charge densities, $n_{A}, n_{B}$ for weak and strong on site disorder. We find that for narrow band alloy s-wav e superconductors the conditions for Anderson's theorem are satisfied in general only for the case of particle-hole symmetry. In this case it is satisfied regardless whether we are in the weak or strong scattering regimes. Interestingly, we find that strong scattering leads to band splitting and in this regime for any band filling we have a critical concentration where a superconductor-insulator quantum phase transition occurs at T=0.Comment: 28 pages, 13 figure