Nuclear thermal propulsion test facility requirements and development strategy

The Nuclear Thermal Propulsion (NTP) subpanel of the Space Nuclear Propulsion Test Facilities Panel evaluated facility requirements and strategies for nuclear thermal propulsion systems development. High pressure, solid core concepts were considered as the baseline for the evaluation, with low pressure concepts an alternative. The work of the NTP subpanel revealed that a wealth of facilities already exists to support NTP development, and that only a few new facilities must be constructed. Some modifications to existing facilities will be required. Present funding emphasis should be on long-lead-time items for the major new ground test facility complex and on facilities supporting nuclear fuel development, hot hydrogen flow test facilities, and low power critical facilities

Quantitative multielement analysis using high energy particle bombardment

Charged particles ranging in energy from 0.8 to 4.0 MeV are used to induce resonant nuclear reactions, Coulomb excitation (gamma X-rays), and X-ray emission in both thick and thin targets. Quantitative analysis is possible for elements from Li to Pb in complex environmental samples, although the matrix can severely reduce the sensitivity. It is necessary to use a comparator technique for the gamma-rays, while for X-rays an internal standard can be used. A USGS standard rock is analyzed for a total of 28 elements. Water samples can be analyzed either by nebulizing the sample doped with Cs or Y onto a thin formvar film or by extracting the sample (with or without an internal standard) onto ion exchange resin which is pressed into a pellet

Radiation Rates for Low Z Impurities in Edge Plasmas

The role of impurity radiation in the reduction of heat loads on divertor plates in present experiments such as DIII-D, JET, JT-60, ASDEX, and Alcator C-Mod, and in planned experiments such as ITER and TPX places a new degree of importance on the accuracy of impurity radiation emission rates for electron temperatures below 250 eV for ITER and below 150 eV for present experiments. We have calculated the radiated power loss using a collisional radiative model for Be, B, C, Ne and Ar using a multiple configuration interaction model which includes density dependent effects, as well as a very detailed treatment of the energy levels and meta-stable levels. The "collisional radiative" effects are very important for Be at temperatures below 10 eV. The same effects are present for higher Z impurities, but not as strongly. For some of the lower Z elements, the new rates are about a factor of two lower than those from a widely used, simpler average-ion package (ADPAK) developed for high Z ions and for higher temperatures. Following the approach of Lengyel for the case where electron heat conduction is the dominant mechanism for heat transport along field lines, our analysis indicates that significant enhancements of the radiation losses above collisional radiative model rates due to such effects as rapid recycling and charge exchange recombination will be necessary for impurity radiation to reduce the peak heat loads on divertor plates for high heat flux experiments such as ITER.Comment: Preprint for the 11th PSI meeting, gzipped postscript with 11 figures, 14 page

Characterizing attention deficit hyperactivity disorder with the slip induction task

Attention deficit hyperactivity disorder (ADHD) is marked by increased distractibility and inhibitory deficits. This study sought to understand how individuals diagnosed with ADHD respond when required to inhibit a routine in response to unexpected stimuli. Ten young adults diagnosed with adult ADHD and ten controls completed the Slip Induction Task (SIT), a measure of attention and inhibition during a routine. The SIT involves participants repeatedly responding to a series of arrow cues, and then later adjusting their routine in response to unexpected stimuli. The findings of this study suggest that those with ADHD do not respond less accurately to novel stimuli within a routine. The data also indicate that when adults diagnosed with ADHD do respond correctly to novel stimuli, they do so more quickly than controls. This could imply that those with adult ADHD may be able to more quickly disengage a usual response pattern i f a novel stimulus requires attention

Concerning the Verity of the MMRD Relation for Novae

It has long been claimed that novae reaching the highest luminosity at the peak of their eruptions appear to fade the fastest from maximum light. The relationship between peak brightness and fade rate is known as the Maximum-Magnitude, Rate-of-Decline (MMRD) relation. Lightcurve parameters for the most recent sample of M31 recurrent novae are presented and used to buttress the case that the observed MMRD relation can be explained as a consequence of observational selection effects coupled with expectations from standard nova models.Comment: 5 pages; 1 figure; 1 table (figure data); abbreviated version accepted for publication in Research Notes of the AA

The supernova remnant CTB 37B and its associated magnetar CXOU J171405.7-381031: evidence for a magnetar-driven remnant

We discuss in this Letter the association of the candidate magnetar CXOU J171405.7-381031 with the supernova remnant CTB 37B. The recent detection of the period derivative of the object allowed an estimation of a young characteristic age of only $\sim 1000 yr$. This value is too small to be compatible even with the minimum radius of the remnant $\geq 10 pc$, the value corresponding to the {\it lower} limit of the estimated distance of $10.2 \pm 3.5 kpc$, unless the true distance happens to be even smaller than the lower limit. We argue that a consistent scenario for the remnant origin, in which the latter is powered by the energy injected by a young magnetar, is indeed more accurate to explain the young age, and points out to its non-standard (i.e. magnetar-driven) nature.Comment: 6 pp., 1 figure, to appear in RAA Letter

Scanning Electron Microscopic Analysis of Intraocular Ossification in Advanced Retinal Disease

Chicken eyes from congenic blind (rd/rd) animals showing early, intermediate, and final stages of ossification, similar to the phthisis bulbi condition in man, were examined using scanning and transmission electron microscopy as well as light microscopy and X-ray microanalysis. Early stages of ossification were devoid of mineralized calcium apatite while intermediate and end stages of the disorder contained large amounts of calcium and phosphorus. This process resulted in metaplastic bone formation. An intact Bruch\u27s membrane appeared to separate the choroid from the degenerated pigment epithelium and the developing bone suggesting that its possible origin was metaplasia of the retinal pigment epithelium and the degenerated sensory retina. The end-stage ossification resulted in phthisic bone formation which completely filled the vitreous cavity in a manner very similar to the human condition of phthisis bulbi

Recent advances in exciton based quantum information processing in quantum dot nanostructures

Recent experimental developments in the field of semiconductor quantum dot spectroscopy will be discussed. First we report about single quantum dot exciton two-level systems and their coherent properties in terms of single qubit manipulations. In the second part we report on coherent quantum coupling in a prototype "two-qubit" system consisting of a vertically stacked pair of quantum dots. The interaction can be tuned in such quantum dot molecule devices using an applied voltage as external parameter.Comment: 37 pages, 15 figures, submitted to New Journal of Physics, focus issue on Solid State Quantum Information, added reference