Inversion of Eddy-Current Data via Conjugate Gradients

In a companion paper, [1], we developed a rigorous, nonlinear model for inverting eddy-current data by means of the conjugate gradient algorithm. In this paper we will present some results obtained from the linearized version of the rigorous model. In this version we assume that the electric field within the flaw is simply the incident field that exists in the absence of the flaw

The Copernicus Complexio: Statistical Properties of Warm Dark Matter Haloes

The recent detection of a 3.5 keV X-ray line from the centres of galaxies and clusters by Bulbul et al. and Boyarsky et al. has been interpreted as emission from the decay of 7 keV sterile neutrinos which could make up the (warm) dark matter (WDM). As part of the Copernicus Complexio (COCO) programme, we investigate the properties of dark matter haloes formed in a high-resolution cosmological N-body simulation from initial conditions similar to those expected in a universe in which the dark matter consists of 7 keV sterile neutrinos. This simulation and its cold dark matter (CDM) counterpart have ∼13.4 bn particles, each of mass ∼105 h−1 M⊙, providing detailed information about halo structure and evolution down to dwarf galaxy mass scales. Non-linear structure formation on small scales (M200 ≲ 2 × 109 h−1 M⊙) begins slightly later in COCO-WARM than in COCO-COLD. The halo mass function at the present day in the WDM model begins to drop below its CDM counterpart at a mass ∼2 × 109 h−1 M⊙ and declines very rapidly towards lower masses so that there are five times fewer haloes of mass M200 = 108 h−1 M⊙ in COCO-WARM than in COCO-COLD. Halo concentrations on dwarf galaxy scales are correspondingly smaller in COCO-WARM, and we provide a simple functional form that describes its evolution with redshift. The shapes of haloes are similar in the two cases, but the smallest haloes in COCO-WARM rotate slightly more slowly than their CDM counterparts

Alginate reduces the increased uptake of cholesterol and glucose in overweight male subjects: a pilot study

Dietary fibers are of particular interest in the prevention and management of obesity and consequent pathologies. Among the proposed mechanisms of action of fiber is the modulation of nutrient uptake from the small intestine. We have used a crossover study design in human subjects to monitor the uptake of glucose, cholesterol, and triacylglycerols in human subjects with normal and high body mass index. Our data demonstrate that uptakes of glucose, triacylglycerols, and cholesterol are all increased with increasing body fat. We demonstrate that treatment with a 1.5-g dose of a strong-gelling alginate may restore uptake of cholesterol and glucose to the levels of healthy subjects. These data indicate a potential therapeutic application of gelling fibers. (C) 2008 Published by Elsevier Inc

Velocity Statistics in the Two-Dimensional Granular Turbulence

We studied the macroscopic statistical properties on the freely evolving quasi-elastic hard disk (granular) system by performing a large-scale (up to a few million particles) event-driven molecular dynamics systematically and found that remarkably analogous to an enstrophy cascade process in the decaying two-dimensional fluid turbulence. There are four typical stages in the freely evolving inelastic hard disk system, which are homogeneous, shearing (vortex), clustering and final state. In the shearing stage, the self-organized macroscopic coherent vortices become dominant. In the clustering stage, the energy spectra are close to the expectation of Kraichnan-Batchelor theory and the squared two-particle separation strictly obeys Richardson law.Comment: 4 pages, 4 figures, to be published in PR

Actinide complexation kinetics: rate and mechanism of dioxoneptunium (V) reaction with chlorophosphonazo III

Rates of complex formation and dissociation in NpO{sub 2}{sup +}- Chlorophosphonazo III (2,7-bis(4-chloro-2-phosphonobenzeneazo)-1,8- dihydroxynapthalene-3,6-disulfonic acid)(CLIII) were investigated by stopped-flow spectrophotometry. Also, limited studies were made of the rates of reaction of La{sup 3+}, Eu{sup 3+}, Dy{sup 3+}, and Fe{sup 3+} with CLIII. Rate determining step in each system is an intramolecular process, the NpO{sub 2}{sup +}-CLIII reaction proceeding by a first order approach to equilibrium in the acid range from 0.1 to 1.0 M. Complex formation occurs independent of acidity, while both acid dependent and independent dissociation pathways are observed. Activation parameters for the complex formation reaction are {Delta}H=46.2{+-}0.3 kJ/m and {Delta}S=7{+-} J/mK (I=1.0 M); these for the acid dependent and independent dissociation pathways are {Delta}H=38.8{+-}0.6 kJ/m, {Delta}S=-96{+-}18 J/mK, {Delta}H=70.0{+-} kJ/m, and {Delta}S=17{+-}1 J/mK, respectively. An isokinetic relationship is observed between the activation parameters for CLIII complex formation with NpO{sub 2}{sup +}, UO{sub 2}{sup 2+}, Th{sup 4+}, and Zr{sup 4+}. Rates of CLIII complex formation reactions for Fe{sup 3+}, Zr{sup 4+}, NpO{sub 2}{sup +}, UO{sub 2}{sup 2+}, Th{sup 4+}, La{sup 3+}, Eu{sup 3+}, and Dy{sup 3+} correlate with cation radius rather than charge/radius ratio

Actinide Complexation Kinetics: Rate and Mechanism of Dioxoneptunium(V) Reaction with Chlorophosphonazo III

Rates of complex formation and dissociation in NpO{sub 2}{sup +}- Chlorophosphonazo III (2,7-bis(4-chloro-2-phosphonobenzeneazo)-1,8- dihydroxynapthalene-3,6-disulfonic acid)(CLIII) were investigated by stopped-flow spectrophotometry. Also, limited studies were made of the rates of reaction of La{sup 3+}, Eu{sup 3+}, Dy{sup 3+}, and Fe{sup 3+} with CLIII. Rate determining step in each system is an intramolecular process, the NpO{sub 2}{sup +}-CLIII reaction proceeding by a first order approach to equilibrium in the acid range from 0.1 to 1.0 M. Complex formation occurs independent of acidity, while both acid dependent and independent dissociation pathways are observed. Activation parameters for the complex formation reaction are {Delta}H=46.2{+-}0.3 kJ/m and {Delta}S=7{+-} J/mK (I=1.0 M); these for the acid dependent and independent dissociation pathways are {Delta}H=38.8{+-}0.6 kJ/m, {Delta}S=-96{+-}18 J/mK, {Delta}H=70.0{+-} kJ/m, and {Delta}S=17{+-}1 J/mK, respectively. An isokinetic relationship is observed between the activation parameters for CLIII complex formation with NpO{sub 2}{sup +}, UO{sub 2}{sup 2+}, Th{sup 4+}, and Zr{sup 4+}. Rates of CLIII complex formation reactions for Fe{sup 3+}, Zr{sup 4+}, NpO{sub 2}{sup +}, UO{sub 2}{sup 2+}, Th{sup 4+}, La{sup 3+}, Eu{sup 3+}, and Dy{sup 3+} correlate with cation radius rather than charge/radius ratio

QCD Corrections and the Endpoint of the Lepton Spectrum in Semileptonic B Decays

Recently, Neubert has suggested that a certain class of nonperturbative corrections dominates the shape of the electron spectrum in the endpoint region of semileptonic $B$ decay. Perturbative QCD corrections are important in the endpoint region. We study the effects of these corrections on Neubert's proposal. The connection between the endpoint of the electron spectrum in semileptonic $B$ decay and the photon spectrum in $b\rightarrow s\gamma$ is outlined.Comment: 18 pages, uses REVTeX, UCSD/PTH 93-38, CALT-68-1910, JHU-TIPAC-930029 (some changes to the discussion of subleading radiative corrections, and minor typos fixed

Three-nucleon mechanisms in photoreactions

The $^{12}$C$(\gamma,ppn)$ reaction has been measured for E$_{\gamma}$=150-800 MeV in the first study of this reaction in a target heavier than $^3$He. The experimental data are compared to a microscopic many body calculation. The model, which predicts that the largest contribution to the reaction arises from final state interactions following an initial pion production process, overestimates the measured cross sections and there are strong indications that the overestimate arises in this two-step process. The selection of suitable kinematic conditions strongly suppresses this two-step contribution leaving cross sections in which up to half the yield is predicted to arise from the absorption of the photon on three interacting nucleons and which agree with the model. The results indicate $(\gamma,3N)$ measurements on nuclei may be a valuable tool for obtaining information on the nuclear three-body interaction.Comment: 5 pages, 3 figure

Extragenic suppressor mutations in ΔripA disrupt stability and function of LpxA

Background: Francisella tularensis is a Gram-negative bacterium that infects hundreds of species including humans, and has evolved to grow efficiently within a plethora of cell types. RipA is a conserved membrane protein of F. tularensis, which is required for growth inside host cells. As a means to determine RipA function we isolated and mapped independent extragenic suppressor mutants in ΔripA that restored growth in host cells. Each suppressor mutation mapped to one of two essential genes, lpxA or glmU, which are involved in lipid A synthesis. We repaired the suppressor mutation in lpxA (S102, LpxA T36N) and the mutation in glmU (S103, GlmU E57D), and demonstrated that each mutation was responsible for the suppressor phenotype in their respective strains. We hypothesize that the mutation in S102 altered the stability of LpxA, which can provide a clue to RipA function. LpxA is an UDP-N-acetylglucosamine acyltransferase that catalyzes the transfer of an acyl chain from acyl carrier protein (ACP) to UDP-N-acetylglucosamine (UDP-GlcNAc) to begin lipid A synthesis. Results: LpxA was more abundant in the presence of RipA. Induced expression of lpxA in the ΔripA strain stopped bacterial division. The LpxA T36N S102 protein was less stable and therefore less abundant than wild type LpxA protein. Conclusion: These data suggest RipA functions to modulate lipid A synthesis in F. tularensis as a way to adapt to the host cell environment by interacting with LpxA