Spectral and optical properties in the antiphase stripe phase of the cuprate superconductors

We investigate the superconducting order parameter, the spectral and optical properties in a stripe model with spin (charge) domain-derived scattering potential $V_{s}$ ($V_{c}$). We show that the charge domain-derived scattering is less effective than the spin scattering on the suppression of superconductivity. For $V_{s}\gg V_{c}$, the spectral weight concentrates on the ($\pi,0$) antinodal region, and a finite energy peak appears in the optical conductivity with the disappearance of the Drude peak. But for $V_{s}\approx V_{c}$, the spectral weight concentrates on the ($\pi/2,\pi/2$) nodal region, and a residual Drude peak exists in the optical conductivity without the finite energy peak. These results consistently account for the divergent observations in the ARPES and optical conductivity experiments in several high-$T_c$ cuprates, and suggest that the "insulating" and "metallic" properties are intrinsic to the stripe state, depending on the relative strength of the spin and charge domain-derived scattering potentials.Comment: 7 pages, 4 figure

Boundary Singularity for Thermal Transpiration Problem of the Linearized Boltzmann Equation

We study the boundary singularity of the fluid velocity for the thermal transpiration problem in the kinetic theory. Logarithmic singularity has been demonstrated through the asymptotic and computational analysis. The goal of this paper is to confirm this logarithmic singularity through exact analysis. We use an iterated scheme, with the “gain” part of the collision operator as a source. The iterated scheme is appropriate for large Knudsen numbers considered here and yields an explicit leading term

Native and multimeric vitronectin exhibit similar affinity for heparin: Differences in heparin binding properties induced upon denaturation are due to self-association into a multivalent form

For many years, the concept that the heparin-binding sequence is sequestered within vitronectin and exposed upon denaturation of the protein has guided experimental design and interpretation of related structure- function studies on the protein. To evaluate binding of heparin to both native and denatured/renatured vitronectin, methods for monitoring binding in solution have been developed. A fluorescence method based on changes in an extrinsic probe attached to heparin has been used to evaluate heparin binding to native and denatured/renatured vitronectin. This approach indicates that there are not major differences in intrinsic heparin-binding affinities between native and renatured protein and invalidate the currently accepted model for a cryptic heparin-binding sequence in the protein. Denaturation and renaturation of vitronectin under near physiological solution conditions is accompanied invariably by self-association of the protein into a multimeric form (Zhuang, P., Blackburn, M. N., and Peterson, C. B. (1996) J. Biol. Chem. 271, 14323-14332), resulting in exposure of multiple heparin-binding sites on the surface of the oligomer. On the basis of the binding data from solution studies and interaction of the native monomer and the denatured multimeric form of vitronectin with a heparin column, along with evaluation of the ionic strength dependence of heparin binding to these vitronectin forms in solution, an alternative model is favored to account for the altered heparin binding properties of vitronectin associated with denaturation of the protein. This model proposes that multivalent interactions between heparin and multimeric vitronectin are responsible for differences in heparin affinity chromatography and ionic strength dependence compared with the native protein

Identification of Small-Molecule Inhibitors against Meso-2, 6-Diaminopimelate Dehydrogenase from Porphyromonas gingivalis

Species-specific antimicrobial therapy has the potential to combat the increasing threat of antibiotic resistance and alteration of the human microbiome. We therefore set out to demonstrate the beginning of a pathogen-selective drug discovery method using the periodontal pathogen Porphyromonas gingivalis as a model. Through our knowledge of metabolic networks and essential genes we identified a “druggable” essential target, meso-diaminopimelate dehydrogenase, which is found in a limited number of species. We adopted a high-throughput virtual screen method on the ZINC chemical library to select a group of potential small-molecule inhibitors. Meso-diaminopimelate dehydrogenase from P. gingivaliswas first expressed and purified in Escherichia coli then characterized for enzymatic inhibitor screening studies. Several inhibitors with similar structural scaffolds containing a sulfonamide core and aromatic substituents showed dose-dependent inhibition. These compounds were further assayed showing reasonable whole-cell activity and the inhibition mechanism was determined. We conclude that the establishment of this target and screening strategy provides a model for the future development of new antimicrobials

Singularity of the Velocity Distribution Function in Molecular Velocity Space

We study the boundary singularity of the solutions to the Boltzmann equation in the kinetic theory. The solution has a jump discontinuity in the microscopic velocity ζ on the boundary and a secondary singularity of logarithmic type around the velocity tangential to the boundary, ζn∼0-, where ζn is the component of molecular velocity normal to the boundary, pointing to the gas. We demonstrate this secondary singularity by obtaining an asymptotic formula for the derivative of the solution on the boundary with respect to ζnn that diverges logarithmically when ζn∼0-. Our study is for the thermal transpiration problem between two plates for the hard sphere gases with sufficiently large Knudsen number and with the diffuse reflection boundary condition. The solution is constructed and its singularity is studied by an iteration procedure

An improvement in the moment-preserving thresholding method

[[abstract]]Thresholding is frequently used for image segmentation. One of the most popular approach to thresholding is the moment-preserving thresholding method proposed by Tsai in 1985. However, it does not work well when the peaks of a histogram have a great size variation. Hence, in this study we propose a simple and effective improvement in Tsai's method such that suitable thresholds can be found even when the histogram has peaks with a great size variation. Experimental results show the effectiveness of the proposed improvement. Int J Imaging Syst Technol, 18, 365-370, 200

An Improvement in the Moment-Preserving Thresholding Method

[[abstract]]Thresholding is frequently used for image segmentation. One of the most popular approach to thresholding is the moment-preserving thresholding method proposed by Tsai in 1985. However, it does not work well when the peaks of a histogram have a great size variation. Hence, in this study we propose a simple and effective improvement in Tsai's method such that suitable thresholds can be found even when the histogram has peaks with a great size variation. Experimental results show the effectiveness of the proposed improvement. (C) 2008 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 18, 365-370. 2008: Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.2016

Biharmonic Riemannian submersions from 3-manifolds

An important theorem about biharmonic submanifolds proved independently by Chen-Ishikawa [CI] and Jiang [Ji] states that an isometric immersion of a surface into 3-dimensional Euclidean space is biharmonic if and only if it is harmonic (i.e, minimal). In a later paper [CMO2], Cadeo-Monttaldo-Oniciuc shown that the theorem remains true if the target Euclidean space is replaced by a 3-dimensional hyperbolic space form. In this paper, we prove the dual results for Riemannian submersions, i.e., a Riemannian submersion from a 3-dimensional space form of non-positive curvature into a surface is biharmonic if and only if it is harmonic