Technologies for aerobraking

Aerobraking is one of the largest contributors to making both lunar and Mars missions affordable. The use of aerobraking/aeroassist over all propulsive approaches saves as much as 60 percent of the initial mass required in low earth orbit (LEO); thus, the number and size of earth to orbit launch vehicles is reduced. Lunar transfer vehicles (LTV), which will be used to transport personnel and materials from LEO to lunar outpost, will aerobrake into earth's atmosphere at approximately 11 km/sec on return from the lunar surface. Current plans for both manned and robotic missions to Mars use aerocapture during arrival at Mars and at return to Earth. At Mars, the entry velocities will range from about 6 to 9.5 km/sec, and at Earth the return velocity will be about 12.5 to 14 km/sec. These entry velocities depend on trajectories, flight dates, and mission scenarios and bound the range of velocities required for the current studies. In order to successfully design aerobrakes to withstand the aerodynamic forces and heating associated with these entry velocities, as well as to make them efficient, several critical technologies must be developed. These are vehicle concepts and configurations, aerothermodynamics, thermal protection system materials, and guidance, navigation, and control systems. The status of each of these technologies are described, and what must be accomplished in each area to meet the requirements of the Space Exploration Initiative is outlined

Five black educators: founders of schools in the South, 1881-1915

The purpose of this dissertation is to present an analysis of the educational history and philosophy of five black educators who founded schools in the South between 1881, the year that Booker T. Washington\u27s Tuskegee Institute was established, and 1915, the year that Washington died, and who wrote published autobiographies during the same period. Specifically, the political and racial factors that influenced the programs of each school were examined, the development of six features of each institution--students, alumni, faculty, curriculum, extension, and fund raising--was traced from the founding of each school until the publication of the founder\u27s autobiography, and the educational philosophy of each school founder as revealed in his autobiography was interpreted using the formal structure of philosophy (ontology, epistemology, and axiology);This study is organized into six chapters with the first five chapters devoted to an individual educator and the conclusions stated in Chapter 6. The educators and their institutions include: Booker T. Washington and Tuskegee Institute (Ala.) between 1881-1901; William J. Edwards and Snow Hill Institute (Ala.) between 1893-1915; William H. Holtzclaw and Utica Institute (Miss.) between 1903-1915; Laurence C. Jones and The Piney Woods School (Miss.) between 1909-1913; and Thomas O. Fuller and Howe Institute (Tenn.) between 1902-1910;An examination of the educational theories and practices of these five educators did not reveal an exploitation of the aspirations of black students as some interpreters of black education between 1881 and 1915 have charged. Each educator, in his own way, assumed a responsibility for the educational uplift of his students and his community, and each believed that his educational program provided black students with a chance to be honest, self-respecting, and hard-working members of society. Each educator believed that education was the pathway for black people to reach their potential

Trinity Restoration Inc.: Southside Cultural Center Economic Impact Study

Economic development has shifted from location-oriented business models towards a more all-encompassing model that recognizes the advancement of human capital or intellectual property as continuously increasing in value. This microcosmic characteristic of development extends to aid in the growth of society as a whole. The Arts and Culture attract a demographic of inspired and motivated people to the area. It results in the development of the society surrounding art venues. The general population will always seek out entertainment, by installing a venue of artistic expression in South Providence that will motivate the community and propel development. This phenomena has been proven, as denoted through the historical evaluation of artistic venues across America that have generated economic growth in their respective communities

Crossroads Rhode Island: Proposed Social Enterprise Business Plan

Crossroads Rhode Island provides their clients with a continuum of care that includes basic emergency needs, shelter, housing, case management and vocational services for individuals and families. In order to provide these services they rely on the generosity of their donors and supporters who have helped Crossroads to become the largest homeless services organization in Rhode Island. It is important to Crossroads that they stick to their core values of safety, respect, and effectiveness when helping the homeless or at-risk individuals and families secure stable homes

What the inflaton might tell us about RHIC/LHC

Topical phenomena in high-energy physics related to collision experiments of heavy nuclei ("Little Bang") and early universe cosmology ("Big Bang") involve far-from-equilibrium dynamics described by quantum field theory. One example concerns the role of plasma instabilities for the process of thermalization in heavy-ion collisions. The reheating of the early universe after inflation may exhibit rather similar phenomena following a tachyonic or parametric resonance instability. Certain universal aspects associated to nonthermal fixed points even quantitatively agree, and considering these phenomena from a common perspective can be fruitful.Comment: Plenary talk at SEWM08, 9 pages, 6 figure

Uranium(III) coordination chemistry and oxidation in a flexible small-cavity macrocycle

U(III) complexes of the conformationally flexible, small-cavity macrocycle trans-calix[2]benzene[2]pyrrolide (L)2–, [U(L)X] (X = O-2,6-tBu2C6H3, N(SiMe3)2), have been synthesized from [U(L)BH4] and structurally characterized. These complexes show binding of the U(III) center in the bis(arene) pocket of the macrocycle, which flexes to accommodate the increase in the steric bulk of X, resulting in long U–X bonds to the ancillary ligands. Oxidation to the cationic U(IV) complex [U(L)X][B(C6F5)4] (X = BH4) results in ligand rearrangement to bind the smaller, harder cation in the bis(pyrrolide) pocket, in a conformation that has not been previously observed for (L)2–, with X located between the two ligand arene rings

Non-equilibrium field theory

I discuss various topics in relativistic non-equilibrium field theory related to high energy physics and cosmology. I focus on non-perturbative problems and how they can be treated on the lattice.Comment: Plenary talk given at the 18th International Symposium on Lattice Field Theory (Lattice 2000), Bangalore, India, 17-22 Aug 200

A quantitative assessment of the amount of prion diverted to category 1 materials and wastewater during processing

In this article the development and parameterization of a quantitative assessment is described that estimates the amount of TSE infectivity that is present in a whole animal carcass (bovine spongiform encephalopathy [BSE] for cattle and classical/atypical scrapie for sheep and lambs) and the amounts that subsequently fall to the floor during processing at facilities that handle specified risk material (SRM). BSE in cattle was found to contain the most oral doses, with a mean of 9864 BO ID50s (310, 38840) in a whole carcass compared to a mean of 1851 OO ID50s (600, 4070) and 614 OO ID50s (155, 1509) for a sheep infected with classical and atypical scrapie, respectively. Lambs contained the least infectivity with a mean of 251 OO ID50s (83, 548) for classical scrapie and 1 OO ID50s (0.2, 2) for atypical scrapie. The highest amounts of infectivity falling to the floor and entering the drains from slaughtering a whole carcass at SRM facilities were found to be from cattle infected with BSE at rendering and large incineration facilities with 7.4 BO ID50s (0.1, 29), intermediate plants and small incinerators with a mean of 4.5 BO ID50s (0.1, 18), and collection centers, 3.6 BO ID50s (0.1, 14). The lowest amounts entering drains are from lambs infected with classical and atypical scrapie at intermediate plants and atypical scrapie at collection centers with a mean of 3 × 10−7 OO ID50s (2 × 10−8, 1 × 10−6) per carcass. The results of this model provide key inputs for the model in the companion paper published here

Shear Viscosity in the O(N) Model

We compute the shear viscosity in the O(N) model at first nontrivial order in the large N expansion. The calculation is organized using the 1/N expansion of the 2PI effective action (2PI-1/N expansion) to next-to-leading order, which leads to an integral equation summing ladder and bubble diagrams. We also consider the weakly coupled theory for arbitrary N, using the three-loop expansion of the 2PI effective action. In the limit of weak coupling and vanishing mass, we find an approximate analytical solution of the integral equation. For general coupling and mass, the integral equation is solved numerically using a variational approach. The shear viscosity turns out to be close to the result obtained in the weak-coupling analysis.Comment: 37 pages, few typos corrected; to appear in JHE