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Full-Text Articles in Physical Sciences and Mathematics

Aflatoxin B1 Albumin Adducts In Plasma And Aflatoxin M1 In Urine Are Associated With Plasma Concentrations Of Vitamins A And E, Francis A. Obuseh, Pauline E. Jolly, Yi Jiang, Faisal M. B. Shuaib, John Waterbor, William O. Ellis, Chandrika J. Piyathilake, Renee A. Desmond, Evans Afriyie-Gyawu, Timothy D. Phillips Dec 2010

Aflatoxin B1 Albumin Adducts In Plasma And Aflatoxin M1 In Urine Are Associated With Plasma Concentrations Of Vitamins A And E, Francis A. Obuseh, Pauline E. Jolly, Yi Jiang, Faisal M. B. Shuaib, John Waterbor, William O. Ellis, Chandrika J. Piyathilake, Renee A. Desmond, Evans Afriyie-Gyawu, Timothy D. Phillips

Evans Afriyie-Gyawu

Background: Although aflatoxin exposure has been shown to be associated with micronutrient deficiency in animals, there are few investigations on the effects of aflatoxin exposure on micronutrient metabolism in humans.
Objective: To examine the relationship between aflatoxin B1 (AFB1) albumin adducts (AF-ALB) in plasma and the aflatoxin M1 (AFM1) metabolite in urine and plasma concentrations of retinol (vitamin A) and α-tocopherol (vitamin E) in Ghanaians.
Methods: A cross-sectional study of 147 adult participants was conducted. Blood and urine samples were tested for aflatoxin and vitamins A and E levels.
Results: Multivariable analysis showed that participants with high AF-ALB (≥ 0.80 …


Observation Of A Red-Blue Detuning Asymmetry In Matter-Wave Superradiance, L. Deng, E. W. Hagley, Qiang Cao, Xiaorui Wang, Xinyu Luo, Ruquan Wang, Marvin G. Payne, Fan Yang, Xiaoji Chen, Mingsheng Zhan Nov 2010

Observation Of A Red-Blue Detuning Asymmetry In Matter-Wave Superradiance, L. Deng, E. W. Hagley, Qiang Cao, Xiaorui Wang, Xinyu Luo, Ruquan Wang, Marvin G. Payne, Fan Yang, Xiaoji Chen, Mingsheng Zhan

Marvin G. Payne

We report the first experimental observation of strong suppression of matter-wave superradiance using blue-detuned pump light and demonstrate a pump-laser detuning asymmetry in the collective atomic recoil motion. In contrast to all previous theoretical frameworks, which predict that the process should be symmetric with respect to the sign of the detuning of the pump laser from the one-photon resonance, we find that for condensates the symmetry is broken. With high condensate densities and red-detuned pump light the distinctive multiorder, matter-wave scattering pattern is clearly visible, whereas with blue-detuned pump light superradiance is strongly suppressed. However, in the limit of a …


Differential Geometry Based Solvation Model I: Eulerian Formulation, Zhan Chen, Nathan A. Baker, Guo-Wei Wei Nov 2010

Differential Geometry Based Solvation Model I: Eulerian Formulation, Zhan Chen, Nathan A. Baker, Guo-Wei Wei

Zhan Chen

This paper presents a differential geometry based model for the analysis and computation of the equilibrium property of solvation. Differential geometry theory of surfaces is utilized to define and construct smooth interfaces with good stability and differentiability for use in characterizing the solvent–solute boundaries and in generating continuous dielectric functions across the computational domain. A total free energy functional is constructed to couple polar and nonpolar contributions to the solvation process. Geometric measure theory is employed to rigorously convert a Lagrangian formulation of the surface energy into an Eulerian formulation so as to bring all energy terms into an equal …


One-Dimensional Wave Equations Defined By Fractal Laplacians, John Fun-Choi Chan, Sze-Man Ngai, Alexander Teplyaev Oct 2010

One-Dimensional Wave Equations Defined By Fractal Laplacians, John Fun-Choi Chan, Sze-Man Ngai, Alexander Teplyaev

Sze-Man Ngai

We study one-dimensional wave equations defined by a class of fractal Laplacians. These Laplacians are defined by fractal measures generated by iterated function systems with overlaps. We prove the existence and uniqueness of weak solutions. We also study numerical computations of the solutions and prove the convergence of the approximation scheme. This is a joint work with John F. Chan and Alexander Teplyaev.


Metallization Of Nanofilms In Strong Adiabatic Electric Fields, Maxim Durach, Anastasia Rusina, Matthias F. Kling, Mark I. Stockman Aug 2010

Metallization Of Nanofilms In Strong Adiabatic Electric Fields, Maxim Durach, Anastasia Rusina, Matthias F. Kling, Mark I. Stockman

Anastasia Rusina

We introduce an effect of metallization of dielectric nanofilms by strong, adiabatically varying electric fields. The metallization causes optical properties of a dielectric film to become similar to those of a plasmonic metal (strong absorption and negative permittivity at low optical frequencies). This is a quantum effect, which is exponentially size-dependent, occurring at fields on the order of 0.1  V/Å and pulse durations ranging from ∼1  fs to ∼10  ns for a film thickness of 3–10 nm.


Generalized Complex Hamiltonian Torus Actions: Examples And Constraints, Thomas Baird, Yi Lin Mar 2010

Generalized Complex Hamiltonian Torus Actions: Examples And Constraints, Thomas Baird, Yi Lin

Yi Lin

Consider an effective Hamiltonian torus action T×MM on a topologically twisted,generalized complex manifold M of dimension 2n. We prove that the rank(T)≤n−2 and that the topological twisting survives Hamiltonian reduction. We then construct a large new class of such actions satisfying rank(T)=n−2, using a surgery procedure on toric manifolds.


Electromagnetic Wave Dynamics In Matter-Wave Superradiant Scattering, Marvin G. Payne, Lu Deng, Edward G. Hagley Feb 2010

Electromagnetic Wave Dynamics In Matter-Wave Superradiant Scattering, Marvin G. Payne, Lu Deng, Edward G. Hagley

Marvin G. Payne

We present a small-signal wave propagation theory on matter-wave superradiant scattering. We show, in a longitudinally excited condensate, that the backward-propagating, superradiantly generated optical field propagates with ultraslow group velocity and that the small-signal gain profile has a Bragg resonance. We further show a unidirectional suppression of optical superradiant scattering, and explain why matter-wave superradiance can occur only when the pump laser is red detuned. This is the first analytical theory on field propagation in matter-wave superradiance that can explain all matter-wave superradiance experiments to date that used a single-frequency, long-pulse, red-detuned laser.


Dark Matter Halos And Evolution Of Bars In Disk Galaxies: Varying Gas Fraction And Gas Spatial Resolution, Jorge Villa-Vargas, Isaac Schlosman, Clayton Heller Jan 2010

Dark Matter Halos And Evolution Of Bars In Disk Galaxies: Varying Gas Fraction And Gas Spatial Resolution, Jorge Villa-Vargas, Isaac Schlosman, Clayton Heller

Jorge Villa-Vargas

We conduct numerical experiments by evolving gaseous/stellar disks embedded in live dark matter halos aiming at quantifying the effect of gas spatial resolution and gas content on the bar evolution. Three model sequences have been constructed using different resolutions, and the gas fraction has been varied along each sequence within the range of fg = 0%-50%, but keeping the disk and halo properties unchanged. We find that the spatial resolution becomes important with an increase in the gas content. For the higher resolution model sequences, we observe a bimodal behavior in the bar evolution with respect to the gas …


Metallization Of Nanofilms In Strong Adiabatic Electric Fields, Maxim Durach, Anastasia Rusina, Matthias F. Kling, Mark I. Stockman Jan 2010

Metallization Of Nanofilms In Strong Adiabatic Electric Fields, Maxim Durach, Anastasia Rusina, Matthias F. Kling, Mark I. Stockman

Maxim Durach

We introduce an effect of metallization of dielectric nanofilms by strong, adiabatically varying electric fields. The metallization causes optical properties of a dielectric film to become similar to those of a plasmonic metal (strong absorption and negative permittivity at low optical frequencies). This is a quantum effect, which is exponentially size-dependent, occurring at fields on the order of 0.1  V/Å and pulse durations ranging from ∼1  fs to ∼10  ns for a film thickness of 3–10 nm.


Substrate Specificity And Kinetic Studies Of Pads 1, 3, And 4 Identify Potent And Selective Inhibitors Of Protein Arginine Deiminase 3, Bryan Knuckley, Corey P. Causey, Justin E. Jones, Monica Bhatia, Christina J. Dreyton, Tanesha C. Osborne, Hidenari Takahara, Paul R. Thompson Jan 2010

Substrate Specificity And Kinetic Studies Of Pads 1, 3, And 4 Identify Potent And Selective Inhibitors Of Protein Arginine Deiminase 3, Bryan Knuckley, Corey P. Causey, Justin E. Jones, Monica Bhatia, Christina J. Dreyton, Tanesha C. Osborne, Hidenari Takahara, Paul R. Thompson

Tanesha C. Osborne

Protein citrullination has been shown to regulate numerous physiological pathways (e.g., the innate immune response and gene transcription) and is, when dysregulated, known to be associated with numerous human diseases, including cancer, rheumatoid arthritis, and multiple sclerosis. This modification, also termed deimination, is catalyzed by a group of enzymes called the protein arginine deiminases (PADs). In mammals, there are five PAD family members (i.e., PADs 1, 2, 3, 4, and 6) that exhibit tissue-specific expression patterns and vary in their subcellular localization. The kinetic characterization of PAD4 was recently reported, and these efforts guided the development of the two most …


A Chloroacetamidine-Based Inactivator Of Protein Arginine Methyltransferase 1: Design, Synthesis, And In Vitro And In Vivo Evaluation, Obiamaka Obianyo, Corey P. Causey, Tanesha C. Osborne, Justin E. Jones, Young-Ho Lee, Michael R. Stallcup, Paul R. Thompson Jan 2010

A Chloroacetamidine-Based Inactivator Of Protein Arginine Methyltransferase 1: Design, Synthesis, And In Vitro And In Vivo Evaluation, Obiamaka Obianyo, Corey P. Causey, Tanesha C. Osborne, Justin E. Jones, Young-Ho Lee, Michael R. Stallcup, Paul R. Thompson

Tanesha C. Osborne

Protein arginine methyltransferases (PRMTs) catalyze the post-translational methylation of arginine residues. PRMT1 is the predominant mammalian isozyme, and is responsible for generating the majority of the asymmetrically dimethylated arginine found in vivo. The dysregulation of this enzyme has been implicated in heart disease and cancer; thus, its inhibition would be useful in the treatment of these diseases. Herein, we describe the most potent PRMT1 inhibitor described to date. This compound, denoted C21, is a chloroacetamidine-containing peptide that is able to irreversibly bind and inactivate the enzyme selectively. We have also shown that the coactivator activity of PRMT1 is selectively inhibited …


Chvátal-Erdös Type Theorems, Ralph J. Faudree, Jill R. Faudree, Ronald J. Gould, Michael S. Jacobson, Colton Magnant Jan 2010

Chvátal-Erdös Type Theorems, Ralph J. Faudree, Jill R. Faudree, Ronald J. Gould, Michael S. Jacobson, Colton Magnant

Colton Magnant

The Chvátal-Erdös theorems imply that if G is a graph of order n ≥ 3 with κ(G) ≥ α(G), then G is hamiltonian, and if κ(G) > α(G), then G is hamiltonian-connected. We generalize these results by replacing the connectivity and independence number conditions with a weaker minimum degree and independence number condition in the presence of sufficient connectivity. More specifically, it is noted that if G is a graph of order n and k ≥ 2 is a positive integer such that κ(G) ≥ k, δ(G) > (n+k2-k)/(k+1), and δ(G) ≥ α(G)+k-2, then G is hamiltonian. It is shown that if …


Towards An Automation Of The Circle Method, Andrew Sills Jan 2010

Towards An Automation Of The Circle Method, Andrew Sills

Andrew V. Sills

The derivation of the Hardy-Ramanujan-Rademacher formula for the number of partitions of n is reviewed. Next, the steps for finding analogous formulas for certain restricted classes of partitions or overpartitions is examined, bearing in mind how these calculations can be automated in a CAS. Finally, a number of new formulas of this type which were conjectured with the aid of Mathematica are presented along with results of a test for their numerical accuracy.