The Projected Gross-Pitaevskii Equation for harmonically confined Bose gases

We extend the Projected Gross Pitaevskii equation formalism of Davis et al. [Phys. Rev. Lett. \bf{87}, 160402 (2001)] to the experimentally relevant case of harmonic potentials. We outline a robust and accurate numerical scheme that can efficiently simulate this system. We apply this method to investigate the equilibrium properties of a harmonically trapped three-dimensional Bose gas at finite temperature, and consider the dependence of condensate fraction, position and momentum distributions, and density fluctuations on temperature. We apply the scheme to simulate an evaporative cooling process in which the preferential removal of high energy particles leads to the growth of a Bose-Einstein condensate. We show that a condensate fraction can be inferred during the dynamics even in this non-equilibrium situation.Comment: 11 pages, 7 figure

Critical temperature of a trapped Bose gas: comparison of theory and experiment

We apply the Projected Gross-Pitaevskii equation (PGPE) formalism to the experimental problem of the shift in critical temperature $T_c$ of a harmonically confined Bose gas as reported in Gerbier \emph{et al.} [Phys. Rev. Lett. \textbf{92}, 030405 (2004)]. The PGPE method includes critical fluctuations and we find the results differ from various mean-field theories, and are in best agreement with experimental data. To unequivocally observe beyond mean-field effects, however, the experimental precision must either improve by an order of magnitude, or consider more strongly interacting systems. This is the first application of a classical field method to make quantitative comparison with experiment.Comment: revtex4, four pages, three figures. v2: updated to published version. Several additions to figures, and better explanations in text in response to referee comment

Evaluation of a technique to generate artificially thickened boundary layers in supersonic and hypersonic flows

The feasibility of using a contoured honeycomb model to generate a thick boundary layer in high-speed, compressible flow was investigated. The contour of the honeycomb was tailored to selectively remove momentum in a minimum of streamwise distance to create an artificially thickened turbulent boundary layer. Three wind tunnel experiments were conducted to verify the concept. Results indicate that this technique is a viable concept, especially for high-speed inlet testing applications. In addition, the compactness of the honeycomb boundary layer simulator allows relatively easy integration into existing wind tunnel model hardware

Classical Region of a Trapped Bose Gas

The classical region of a Bose gas consists of all single-particle modes that have a high average occupation and are well-described by a classical field. Highly-occupied modes only occur in massive Bose gases at ultra-cold temperatures, in contrast to the photon case where there are highly-occupied modes at all temperatures. For the Bose gas the number of these modes is dependent on the temperature, the total number of particles and their interaction strength. In this paper we characterize the classical region of a harmonically trapped Bose gas over a wide parameter regime. We use a Hartree-Fock approach to account for the effects of interactions, which we observe to significantly change the classical region as compared to the idealized case. We compare our results to full classical field calculations and show that the Hartree-Fock approach provides a qualitatively accurate description of classical region for the interacting gas.Comment: 6 pages, 5 figures; updated to include new results with interaction

Maturation of the gilt\u27s uterus before puberty: response to progesterone at different ages

We determined the age at which progesterone induced certain responses in the gilt\u27s uterus. The prepubertal maturation permitting each response is being studied currently with the intent of using the information to develop methods to improve litter size in pigs, perhaps by identifying markers for uterine function that could be used before gilts enter the breeding herd.; Swine Day, Manhattan, KS, November 16, 199

Advancement in the Use of Optical Properties for Water Quality and Water Reuse in Public Water Treatment Cycles

Dissolved organic matter (DOM) is a complex mixture of organic compounds resulting from the breakdown and transformational products of higher forms of organic matter (i.e., plants, animals and microbes). DOM is also a ubiquitous constituent of natural and treated waters and known to play key roles in many environmental and engineered and treated systems. Examples include the global carbon flux, fate and transport of contaminants, light absorption and photochemistry in water, and the production of disinfection byproducts in water treatment systems. Analysis of molecular size and optical properties have emerged as useful techniques to characterize DOM in terms of source and chemical composition of DOM. These relationships are useful to the water treatment industry and allow DOM to be used as surrogates for the removal of contaminants and differentiate between water sources such as natural surface water and treated wastewater effluent. The main goal of my research is to advance the understanding of DOM molecular size and optical properties, their relationship to one another, and how they can be utilized in the water treatment industry, especially for potable water reuse treatment applications and the development of optical based sensors and probes. My research is primarily conducted using a size exclusion chromatography system (SEC) coupled with absorbance, fluorescence, and dissolved organic carbon (DOC) detection. In the Chapter 1, I develop a method to calculate fluorescence quantum yield as a function of molecular size and demonstrate the ability of this method to provide compositional information regarding absorbing and fluorescing fractions of DOM. In Chapter 2, I apply mass balance principals to blends of DOM sources to demonstrate conservative mixing behavior with respect to the molecular size distributions and optical properties of DOM. Finally, in Chapter 6, I investigate the composition of &ldquo;protein-like&rdquo; fluorescence components in DOM for a paired surface water and wastewater effluent to advance the understanding of these metrics in the context of an urban water cycle and inform future development of optical sensors.</p

Thymus Ontogeny in Frogs: T-Cell Renewal at Metamorphosis

Metamorphosis in amphibians presents a unique problem for the developing immune system. Because tadpoles are free-living, they need an immune system to protect against potential pathogens. However, at metamorphosis, they acquire a variety of new adultspecific molecules to which the tadpole immune system must become tolerant. We hypothesized that Xenopus laevis tadpoles may avoid potentially destructive antiself responses by largely discarding the larval immune system at metamorphosis and acquiring a new one. By implanting triploid (3N) thymuses into diploid (2N) hosts, we examined the influx and expansion of host T-cell precursors in the donor thymus of normally metamorphosing and metamorphosis-inhibited frogs. We observed that donor thymocytes are replaced by host-derived cells during metamorphosis, but inhibition of metamorphosis does not prevent this exchange of cells. The implanted thymuses export T cells to the spleen. This donor-derived pool of cells declines after metamorphosis in normally developing frogs but is retained to a greater extent if metamorphosis is inhibited. These studies confirm previous observations of a metamorphosis-associated wave of expansion of T cells and demonstrate that it is not dependent on the relatively high concentrations of thyroid hormones required for metamorphosis. Although some larval T cells persist through metamorphosis, others may be destroyed or the larval population is significantly diluted by the expanding adult population

CONCRETE REFLECTED ARRAYS OF U(93.2) METAL

During the period from 1963 – 1973, experiments involving highly enriched uranium units were performed at the Oak Ridge National Laboratory Critical Experiments Facility to determine various critical configurations of three-dimensional arrays. The experiments formed a four-part series, and were reported by several different experimenters; the results of interest for this evaluation are those reported for the fourth experimentation, Critical Three-Dimensional Arrays of Neutron Interacting Units: Part IV, published and performed by D.W.Magnuson (Ref 1). Information is also available in the logbook . This set of experiments utilized subcritical metal units on a split table apparatus to determine critical configurations for 2×2×2 arrangements of highly enriched uranium reflected by concrete. Magnuson manipulated the configuration of several uranium cylinders and blocks within a concrete reflector. The different permutations utilized uranium cylinders of two different heights in various positions in the three dimensional array; certain cases also placed thin uranium blocks on top of the cylinders. The thickness of the surrounding concrete, as well as the inner dimensions of the concrete reflector was also varied in certain cases. The variations resulted in fourteen different experimental permutations or configurations. All fourteen configurations were judged to be unacceptable for use as criticality safety benchmarks. All experiments were initially evaluated; however only three configurations were evaluated in detail. Configurations 2, 4, 6 and 12 were not evaluated in detail because they are subcritical and configurations 5, 7, 8, 9, and 10 were also were not evaluated in detail because they were supercritical by more than beta effective (~0.007), or prompt critical. The experiments evaluated in detail for this benchmark were configurations 1, 3, and 11. The experimental report also contains the information for HEU-MET-FAST-056. Closely related work has been recorded in HEU-MET-FAST-053, which is a benchmark evaluation of a different series of three dimensional array experiments with four different moderator materials. HEU-MET-FAST-023 and HEU-MET-FAST-026 are also related because they utilize the same metal cylinders as these experiments