630 research outputs found
A Sensitive Faraday Rotation Setup Using Triple Modulation
The utilization of polarized targets in scattering experiments has become a
common practice in many major accelerator laboratories. Noble gases are
especially suitable for such applications, since they can be easily
hyper-polarized using spin exchange or metastable pumping techniques. Polarized
helium-3 is a very popular target because it often serves as an effective
polarized neutron due to its simple nuclear structure. A favorite cell material
to generate and store polarized helium-3 is GE-180, a relatively dense
aluminosilicate glass. In this paper, we present a Faraday rotation method,
using a new triple modulation technique, where the measurement of the Verdet
constants of SF57 flint glass, pyrex glass, and air were tested. The
sensitivity obtained shows that this technique may be implemented in future
cell wall characterization and thickness measurements. We also discuss the
first ever extraction of the Verdet constant of GE-180 glass for four
wavelength values of 632 nm, 773 nm, 1500 nm, and 1547 nm, whereupon the
expected 1/{\lambda}^{2} dependence was observed.Comment: 4 pages, 2 figures Updated version for RSI submissio
Reconstructing the Inflaton Potential
A review is presented of recent work by the authors concerning the use of
large scale structure and microwave background anisotropy data to determine the
potential of the inflaton field. The importance of a detection of the
stochastic gravitational wave background is emphasised, and some preliminary
new results of tests of the method on simulated data sets with uncertainties
are described. (Proceedings of ``Unified Symmetry in the Small and in the
Large'', Coral Gables, 1994)Comment: 13 pages, uuencoded postscript file with figures included (LaTeX file
available from ARL), FERMILAB-Conf 94/189
K-2 Mathematicians & Writers: Professional Learning Communities for Developing Conceptual Understanding
National Council of Teachers of Mathematics (NCTM) has long supported the use of children’s literature, writing, and manipulatives to improve conceptual understanding of mathematics (2000). In a professional learning community for K-2 teachers, professional development was designed and implemented on ways to incorporate literacy and manipulatives into a mathematics lesson. The teachers were charged with collaboratively planning lessons that included multiple components: the standard(s), a mathematics activity, manipulatives, a writing task, and children’s literature. As the data were analyzed, it became apparent that while most of the lessons were well connected, this did not happen for all of the lessons. In addition, we observed that there were cases of teacher misconceptions. We feel these misconceptions contributed to the lack of connectedness in some of the lessons
Confidence set of putative quantitative trait loci in whole genome scans with application to the Genetic Analysis Workshop 17 simulated data
As genetic maps become more highly dense, the ability to sufficiently localize putative disease loci becomes an achievable goal. This has prompted an increased interest in methods for constructing confidence intervals for the location of variants that contribute to a trait. Such intervals are important because, by reducing the number of candidate loci, they can help in the design of cost-effective and time-efficient follow-up studies. We introduce a new approach that can be used in whole-genome scans to obtain a confidence set of loci that contribute at least a predetermined percentage h to the overall genetic variation of a quantitative phenotype. The method is developed in the framework of generalized linear mixed models and can accommodate families of arbitrary size and structure. We apply our method to the Genetic Analysis Workshop 17 simulated data where we scan chromosomes 6, 15, 20, 21, and 22 to uncover loci regulating the simulated phenotype Q2. For the analyses we had prior knowledge of the simulation model used to generate the phenotype
Soft-Sediment Recruitment Dynamics of Early Blue Crab Stages in Mississippi Sound
In order to understand the recruitment dynamics of early blue crabs, it is necessary to sample quantitatively across early stages and habitats at appropriate spatio-temporal scales. Few studies of early blue crab recruitment have considered the potential role of soft-sediment habitat or directly related megalopal supply to local densities of early stages. During a 7-wk peak recruitment period, fluctuations in early stages of blue crabs from settlement collectors were significantly cross-correlated between two sites separated by 7.5 km, showing connectivity on this large spatial scale. Moreover, numbers of megalopae from settlement collectors were directly correlated with densities of early juveniles from nearby soft-sediment, showing that settlement collectors may reflect local recruitment intensity. Significant habitat variables included depth and salinity (i.e., water mass) for small post-settlement juveniles (CW), and substrate type for large juveniles ( greater than or equal to6 mm CW). Early juveniles from soft-sediment habitat were spatially aggregated at relatively low densities; although initial rates of loss may not be as high there as in structured habitats. Thus, soft-sediment habitat may subsidize the supply of early juvenile stages to structured habitats
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APPLICATION OF NONSPHERICAL FISSILE CONFIGURATION IN WASTE CONTAINERS AT SRS
Transuranic (TRU) solid waste that has been generated as a result of the production of nuclear material for the United States defense program at the Savannah River Site (SRS) has been stored in more than 30,000 55-gallon drums and carbon steel boxes since 1953. Nearly two thirds of those containers have been processed and shipped to the Waste Isolation Pilot Plant. Among the containers assayed so far, the results indicate several drums with fissile inventories significantly higher (600-1000 fissile grams equivalent (FGE) {sup 239}Pu) than their original assigned values. While part of this discrepancy can be attributed to the past limited assay capabilities, human errors are believed to be the primary contributor. This paper summarizes the application of nonspherical fissile material configuration in waste containers, resulting in less restrictive mass and spacing limits, increased storage capacity, and several administrative controls for handling and storage of waste containers being modified without compromising safety
Homozygosity by descent mapping of blood pressure in the Old Order Amish: evidence for sex specific genetic architecture
<p>Abstract</p> <p>Background</p> <p>High blood pressure is a well established risk factor for morbidity and mortality acting through heart disease, stroke and cardiovascular disease. Genome wide scans have linked regions of nearly every human chromosome to blood pressure related traits. We have capitalized on beneficial qualities of the Old Order Amish of Lancaster, PA, a closed founder population with a relatively small number of founders, to perform a genome wide homozygosity by descent mapping scan. Each individual in the study has a non zero probability of consanguinity. Systolic and diastolic blood pressures are shown to have appreciable dominance variance components.</p> <p>Results</p> <p>Areas of two chromosomes were identified as suggestive of linkage to SBP and 5 areas to DBP in either the overall or sex specific analyses. The strongest evidence for linkage in the overall sample was to Chromosome 18q12 (LOD = 2.6 DBP). Sex specific analyses identified a linkage on Chromosome 4p12-14 (LOD in men only = 3.4 SBP). At Chromosome 2q32-33, an area where we previously reported significant evidence for linkage to DBP using a conventional identity by descent approach, the LOD was 1.4; however an appreciable sex effect was observed with men accounting for most of the linkage (LOD in men only = 2.6).</p> <p>Conclusion</p> <p>These results add evidence to a sex specific genetic architecture to blood pressure related traits, particularly in regions of linkage on chromosome 2, 4 and 18.</p
The Concept and Analytical Investigation of CO2 and Steam Co-Electrolysis for Resource Utilization in Space Exploration
CO2 acquisition and utilization technologies will have a vital role in designing sustainable and affordable life support and in situ fuel production architectures for human and robotic exploration of Moon and Mars. For long-term human exploration to be practical, reliable technologies have to be implemented to capture the metabolic CO2 from the cabin air and chemically reduce it to recover oxygen. Technologies that enable the in situ capture and conversion of atmospheric CO2 to fuel are essential for a viable human mission to Mars. This paper describes the concept and mathematical analysis of a closed-loop life support system based on combined electrolysis of CO2 and steam (co-electrolysis). Products of the coelectrolysis process include oxygen and syngas (CO and H2) that are suitable for life support and synthetic fuel production, respectively. The model was developed based on the performance of a co-electrolysis system developed at Idaho National Laboratory (INL). Individual and combined process models of the co-electrolysis and Sabatier, Bosch, Boudouard, and hydrogenation reactions are discussed and their performance analyses in terms of oxygen production and CO2 utilization are presented
Fluctuations and Bubble Dynamics in First-Order Phase Transitions
We numerically examine the effect of thermal fluctuations on a first-order
phase transition in 2+1 dimensions. By focusing on the expansion of a single
bubble we are able to calculate changes in the bubble wall's velocity as well
as changes in its structure relative to the standard case where the bubble
expands into a homogeneous background. Not only does the wall move faster, but
the transition from the symmetric to the asymmetric phase is no longer smooth,
even for a fairly strong transition. We discuss how these results affect the
standard picture of electroweak baryogenesis.Comment: Latex, 30 pages, 11 ps figures, short discussion added in conclusions
and minor clarifications, accepted to Phys Rev
Hydrodynamic Detonation Instability in Electroweak and QCD Phase Transitions
The hydrodynamic stability of deflagration and detonation bubbles for a first
order electroweak and QCD phase transition has been discussed recently with the
suggestion that detonations are stable. We examine here the case of a
detonation more carefully. We find that in front of the bubble wall
perturbations do not grow with time, but behind the wall modes exist which grow
exponentially. We briefly discuss the possible meaning of this instability.Comment: 12 pages, 3 figures available on request, Latex,
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