Portable, high intensity isotopic neutron source provides increased experimental accuracy

Small portable, high intensity isotopic neutron source combines twelve curium-americium beryllium sources. This high intensity of neutrons, with a flux which slowly decreases at a known rate, provides for increased experimental accuracy

Effects of Crust Ingestion on Mixer Pump Performance in Tank

In August 1999, a workshop was held at Pacific Northwest National Laboratory to discuss the effects of crust ingestion on mixer pump performance in Hanford Waste Tank 241-SY-101. The main purpose of the workshop was to evaluate the potential for crust ingestion to degrade mixing and/or damage the mixer pump. The need for a previously determined 12-inch separation between the top of the mixer pump inlet and the crust base was evaluated. Participants included a representative from the pump manufacturer, an internationally known expert in centrifugal pump theory, Hanford scientists and engineers, and operational specialists representing relevant fields of expertise. The workshop focused on developing an understanding of the pump design, addressing the physics of entrainment of solids and gases into the pump, and assessing the effects of solids and gases on pump performance. The major conclusions are summarized as follows: * Entrainment of a moderate amount of solids or gas from the crust should not damage the pump or reduce its lifetime, though mixing effectiveness will be somewhat reduced. * Air binding should not damage the pump. Vibration due to ingestion of gas, solids, and objects potentially could cause radial loads that might reduce the lifetime of bearings and seals. However, significant damage would require extreme conditions not associated with the small bubbles, fine solids, and chunks of relatively weak material typical of the crust. * The inlet duct extension opening, 235 inches from the tank bottom, should be considered the pump inlet, not the small gap at 262 inches. * A suction vortex exists at the inlet of all pumps. The characteristics of the inlet suction vortex in the mixer pump are very hard to predict, but its effects likely extend upward several feet. Because of this, the current 12-inch limit should be replaced with criteria based on actual monitored pump performance. The most obvious criterion (in addition to current operational constraints) is to monitor discharge pressure and cease pump operation if it falls below a predetermined amount. * There are no critically necessary tests to prove pump operability or performance before initiating the transfer and back-dilution sequence

Automatic holographic droplet analysis for liquid fuel sprays

The basic scheme for automated holographic analysis involves an optical system for reconstruction of the three dimensional real image of the droplet field, a spatial scanning system to transport a digitizing X-y image sensor through the real image, and processing algorithms for droplet recognition which establish the droplet sizes and positions. The hardware for system demonstrated includes the expanded and collimated beam from a 5 mW helium-neon laser for hologram reconstruction, an imaging lens for magnification of the real image field, and a video camera and digitizer providing 512-by-512 pixel resolution with 8-bit digitization. A mechanical stage is used to scan the hologram in three dimensional space, maintaining constant image magnification. A test droplet hologram is used for development and testing of the image processing algorithms

Adobe Flash as a medium for online experimentation: a test of reaction time measurement capabilities

Adobe Flash can be used to run complex psychological experiments over the Web. We examined the reliability of using Flash to measure reaction times (RTs) using a simple binary-choice task implemented both in Flash and in a Linux-based system known to record RTs with millisecond accuracy. Twenty-four participants were tested in the laboratory using both implementations; they also completed the Flash version on computers of their own choice outside the lab. RTs from the trials run on Flash outside the lab were approximately 20 msec slower than those from trials run on Flash in the lab, which in turn were approximately 10 msec slower than RTs from the trials run on the Linux-based system (baseline condition). RT SDs were similar in all conditions, suggesting that although Flash may overestimate RTs slightly, it does not appear to add significant noise to the data recorded

Significant differences in incubation times in sheep infected with bovine spongiform encephalopathy result from variation at codon 141 in the PRNP gene

The susceptibility of sheep to prion infection is linked to variation in the PRNP gene, which encodes the prion protein. Common polymorphisms occur at codons 136, 154 and 171. Sheep which are homozygous for the A<sub>136</sub>R<sub>154</sub>Q<sub>171</sub> allele are the most susceptible to bovine spongiform encephalopathy (BSE). The effect of other polymorphisms on BSE susceptibility is unknown. We orally infected ARQ/ARQ Cheviot sheep with equal amounts of BSE brain homogenate and a range of incubation periods was observed. When we segregated sheep according to the amino acid (L or F) encoded at codon 141 of the PRNP gene, the shortest incubation period was observed in LL141 sheep, whilst incubation periods in FF<sub>141</sub> and LF<sub>141</sub> sheep were significantly longer. No statistically significant differences existed in the expression of total prion protein or the disease-associated isoform in BSE-infected sheep within each genotype subgroup. This suggested that the amino acid encoded at codon 141 probably affects incubation times through direct effects on protein misfolding rates

EDIN design study alternate space shuttle booster replacement concepts. Volume 2: Design simulation results

Historical weight estimating relationships were developed for the liquid rocket booster (LRB) using Saturn technology, and modified as required to support the EDIN05 study. Mission performance was computed using February 1975 shuttle configuration groundrules to allow reasonable comparison of the existing shuttle with the EDIN05 designs. The launch trajectory was constrained to pass through both the RTLS/AOA and main engine cut-off points. Performance analysis was based on a point design trajectory model which optimized initial tilt rate and exo-atmospheric pitch profile. A gravity turn was employed during the boost phase in place of the shuttle angle-of-attack profile. Engine throttling add/or shutdown was used to constrain dynamic pressure and/or longitudinal acceleration where necessary

Physical Purification of Quantum States

We introduce the concept of a physical process that purifies a mixed quantum state, taken from a set of states, and investigate the conditions under which such a purification map exists. Here, a purification of a mixed quantum state is a pure state in a higher-dimensional Hilbert space, the reduced density matrix of which is identical to the original state. We characterize all sets of mixed quantum states, for which perfect purification is possible. Surprisingly, some sets of two non-commuting states are among them. Furthermore, we investigate the possibility of performing an imperfect purification.Comment: 5 pages, 1 figure; published versio

Association between depressive symptom clusters and food attentional bias

Background The mechanisms underlying the depression-obesity relationship are unclear. Food attentional bias (FAB) represents one candidate mechanism that has not been examined. We evaluated the hypothesis that greater depressive symptoms are associated with increased FAB. Method Participants were 89 normal weight or overweight adults (mean age = 21.2 ± 4.0 years, 53% female, 33% non-white, mean body mass index in kg/m2 = 21.9 ± 1.8 for normal weight; 27.2 ± 1.5 for overweight). Total, somatic, and cognitive-affective depressive symptom scores were computed from the Patient Health Questionnaire-8 (PHQ-8). FAB scores were calculated using reaction times (RT) and eye-tracking (ET) direction and duration measures for a food visual probe task. Age, gender, race/ethnicity, and body fat percent were covariates. Results Only PHQ-8 somatic symptoms were positively associated with RT-measured FAB (β = 0.23, p = .04). The relationship between somatic symptoms and ET direction (β = 0.18, p = .17) and duration (β = 0.23, p = .08) FAB indices were of similar magnitude but were not significant. Somatic symptoms accounted for 5% of the variance in RT-measured FAB. PHQ-8 total and cognitive-affective symptoms were unrelated to all FAB indices (ps ≥ 0.09). Conclusions Only greater somatic symptoms of depression were linked to food attentional bias as measured using reaction time. Well-powered prospective studies should examine whether this bias replicates, particularly for eye-tracking measures, and whether it partially mediates the depression-to-obesity relationship

Water-depth measurement by wave refraction and multispectral techniques

Shallow ocean depth measurements by aerial photographs of wave refraction and wavelength changes and by multispectral scanning of wave reflectio