Design verification test matrix development for the STME thrust chamber assembly

This report presents the results of the test matrix development for design verification at the component level for the National Launch System (NLS) space transportation main engine (STME) thrust chamber assembly (TCA) components including the following: injector, combustion chamber, and nozzle. A systematic approach was used in the development of the minimum recommended TCA matrix resulting in a minimum number of hardware units and a minimum number of hot fire tests

Lifetime and polarization of the radiative decay of excitons, biexcitons and trions in CdSe nanocrystal quantum dots

Using the pseudopotential configuration-interaction method, we calculate the intrinsic lifetime and polarization of the radiative decay of single excitons (X), positive and negative trions (X+ and X−), and biexcitons (XX) in CdSe nanocrystal quantum dots. We investigate the effects of the inclusion of increasingly more complex many-body treatments, starting from the single-particle approach and culminating with the configuration-interaction scheme. Our configuration-interaction results for the size dependence of the single-exciton radiative lifetime at room temperature are in excellent agreement with recent experimental data. We also find the following. (i) Whereas the polarization of the bright exciton emission is always perpendicular to the hexagonal c axis, the polarization of the dark exciton switches from perpendicular to parallel to the hexagonal c axis in large dots, in agreement with experiment. (ii) The ratio of the radiative lifetimes of mono- and biexcitons (X):(XX) is ~1:1 in large dots (R=19.2 Å). This ratio increases with decreasing nanocrystal size, approaching 2 in small dots (R=10.3 Å). (iii) The calculated ratio (X+):(X−) between positive and negative trion lifetimes is close to 2 for all dot sizes considered

Hawaii's Federally Subsidized Public School Lunch Program and the Hawaii Department of Education's Food Safety Requirements for It

This fact sheet provides general considerations of using Hawaii-grown produce in the public school lunch program. Items covered include freshness, self-sufficiency, sustainability, economic viabiity, and Department of Education requirements

Wakefield damping for the CLIC crab cavity

A crab cavity is required in the CLIC to allow effective head-on collision of bunches at the IP. A high operating frequency is preferred as the deflection voltage required for a given rotation angle and the RF phase tolerance for a crab cavity are inversely proportional to the operating frequency. The short bunch spacing of the CLIC scheme and the high sensitivity of the crab cavity to dipole kicks demand very high damping of the inter-bunch wakes, the major contributor to the luminosity loss of colliding bunches. This paper investigates the nature of the wakefields in the CLIC crab cavity and the possibility of using various damping schemes to suppress them effectively

Radiative Models of Sagittarius A* and M87 from Relativistic MHD Simulations

Ongoing millimeter VLBI observations with the Event Horizon Telescope allow unprecedented study of the innermost portion of black hole accretion flows. Interpreting the observations requires relativistic, time-dependent physical modeling. We discuss the comparison of radiative transfer calculations from general relativistic MHD simulations of Sagittarius A* and M87 with current and future mm-VLBI observations. This comparison allows estimates of the viewing geometry and physical conditions of the Sgr A* accretion flow. The viewing geometry for M87 is already constrained from observations of its large-scale jet, but, unlike Sgr A*, there is no consensus for its millimeter emission geometry or electron population. Despite this uncertainty, as long as the emission region is compact, robust predictions for the size of its jet launching region can be made. For both sources, the black hole shadow may be detected with future observations including ALMA and/or the LMT, which would constitute the first direct evidence for a black hole event horizon.Comment: 8 pages, 2 figures, submitted to the proceedings of AHAR 2011: The Central Kiloparse

Associated degeneration of ventral tegmental area dopaminergic neurons in the rat nigrostriatal lactacystin model of parkinsonism and their neuroprotection by valproate

AbstractParkinson’s disease (PD) manifests clinically as bradykinesia, rigidity, and development of a resting tremor, primarily due to degeneration of dopaminergic nigrostriatal pathways in the brain. Intranigral administration of the irreversible ubiquitin proteasome system inhibitor, lactacystin, has been used extensively to model nigrostriatal degeneration in rats, and study the effects of candidate neuroprotective agents on the integrity of the dopaminergic nigrostriatal system. Recently however, adjacent extra-nigral brain regions such as the ventral tegmental area (VTA) have been noted to also become affected in this model, yet their integrity in studies of candidate neuroprotective agents in the model have largely been overlooked. Here we quantify the extent and distribution of dopaminergic degeneration in the VTA of rats intranigrally lesioned with lactacystin, and quantify the extent of VTA dopaminergic neuroprotection after systemic treatment with an epigenetic therapeutic agent, valproate, shown previously to protect dopaminergic SNpc neurons in this model. We found that unilateral intranigral administration of lactacystin resulted in a 53.81% and 31.72% interhemispheric loss of dopaminergic SNpc and VTA neurons, respectively. Daily systemic treatment of lactacystin lesioned rats with valproate however resulted in dose-dependant neuroprotection of VTA neurons. Our findings demonstrate that not only is the VTA also affected in the intranigral lactacystin rat model of PD, but that this extra-nigral brain region is substrate for neuroprotection by valproate, an agent shown previously to induce neuroprotection and neurorestoration of SNpc dopaminergic neurons in this model. Our results therefore suggest that valproate is a candidate for extra-nigral as well as intra-nigral neuroprotection

Ethane-beta-Sultam Modifies the Activation of the Innate Immune System Induced by Intermittent Ethanol Administration in Female Adolescent Rats

Intermittent ethanol abuse or ‘binge drinking’ during adolescence induces neuronal damage, which may be associated with cognitive dysfunction. To investigate the neurochemical processes involved, rats were administered either 1 g/kg or 2 g/kg ethanol in a ‘binge drinking’ regime. After only 3 weeks, significant activation of phagocytic cells in the peripheral (alveolar macrophages) and the hippocampal brain region (microglia cells) was present,as exemplified by increases in the release of pro-inflammatory cytokines in the macrophages and of iNOS in the microglia. This was associated with neuronal loss in the hippocampus CA1 region. Daily supplementation with a taurine prodrug, ethane-β-sultam, 0.028 g/kg, during the intermittent ethanol loading regime, supressed the release of the pro-inflammatory cytokines and of reactive nitrogen species, as well as neuronal loss, particularly in the rats administered the lower dose of ethanol, 1 g/kg. Plasma, macrophage and hippocampal taurine levels increased marginally after ethane-β-sultam supplementation. The ‘binge drinking’ ethanol rats administered 1 g/kg ethanol showed increased latencies to those of the control rats in their acquisition of spacial navigation in the Morris Water Maze, which was normalised to that of the controls values after ethane-β-sultam administration. Such results confirm that the administration of ethane-β-sultam to binge drinking rats reduces neuroinflammation in both the periphery and the brain, suppresses neuronal loss, and improved working memory of rats in a water maze study

Analytical solutions of bound timelike geodesic orbits in Kerr spacetime

We derive the analytical solutions of the bound timelike geodesic orbits in Kerr spacetime. The analytical solutions are expressed in terms of the elliptic integrals using Mino time $\lambda$ as the independent variable. Mino time decouples the radial and polar motion of a particle and hence leads to forms more useful to estimate three fundamental frequencies, radial, polar and azimuthal motion, for the bound timelike geodesics in Kerr spacetime. This paper gives the first derivation of the analytical expressions of the fundamental frequencies. This paper also gives the first derivation of the analytical expressions of all coordinates for the bound timelike geodesics using Mino time. These analytical expressions should be useful not only to investigate physical properties of Kerr geodesics but more importantly to applications related to the estimation of gravitational waves from the extreme mass ratio inspirals.Comment: A typo in the first expression in equation 21 was fixe

Future Orientation as a Protective Factor for African American Adolescents Exposed to Community Violence

For African American youth disproportionately exposed to community violence and the associated risk of externalizing behaviors, developmental assets that reduce the risk for externalizing behaviors and enhance adaptive coping should be explored. In a sample of 572 African American adolescents (Mage = 15.85; SD = 1.42), the current study explored whether future orientation or gender buffered the impact of community violence exposure on externalizing behaviors. The current study also examined the interaction between future orientation, gender, and violence-specific coping strategies to determine their association with externalizing behaviors. Future orientation moderated the relationship between violence exposure and delinquent, but not aggressive, behaviors. Future orientation interacted differently with coping for males and females to predict externalizing behaviors. Research and clinical implications are discussed