The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
L N Ivanov - One of the best experts on this subject based on the ideXlab platform.
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DC strong-field Stark effect: consistent quantum-Mechanical approach
Journal of Physics B: Atomic Molecular and Optical Physics, 1993Co-Authors: Alexander V. Glushkov, L N IvanovAbstract:The energies and the widths of the Stark resonances for the hydrogen atom are calculated using a new approach. It is based on the operator form of the perturbation theory of the Schrodinger equation. The method includes the physically reasonable distorted-waves approximation in the frame of the formally exact quantum-Mechanical Procedure. The zero-order Hamiltonian possessing only stationary states is determined only by its spectrum without specifying its explicit form. The method of calculation of the perturbation theory matrix elements is described.
Christian A. J. Schulze-bauer - One of the best experts on this subject based on the ideXlab platform.
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A Layer-Specific Three-Dimensional Model for the Simulation of Balloon Angioplasty using Magnetic Resonance Imaging and Mechanical Testing
Annals of Biomedical Engineering, 2002Co-Authors: Gerhard A. Holzapfel, Michael Stadler, Christian A. J. Schulze-bauerAbstract:A detailed understanding of the Mechanical Procedure of balloon angioplasty requires three-dimensional (3D) modeling and efficient numerical simulations. We have developed a 3D model for eight distinct arterial components associated with specific Mechanical responses. The 3D geometrical model is based on in vitro magnetic resonance imaging of a human stenotic postmortem artery and is represented by nonuniform rational B-spline surfaces. Mechanical tests of the corresponding vascular tissues provide a fundamental basis for the formulation of large strain constitutive laws, which model the typical anisotropic, highly nonlinear, and inelastic Mechanical characteristics under supraphysiological loadings. The 3D finite-element realization considers the balloon–artery interaction and accounts for vessel-specific axial in situ prestretches. 3D stress states of the investigated artery during balloon expansion and stent deployment were analyzed. Furthermore, we studied the changes of the 3D stress state due to model simplifications, which are characterized by neglecting axial in situ prestretch, assuming plane strain states, and isotropic material responses, as commonly utilized in previous works. Since these simplifications lead to maximum stress deviations of up to 600%—where even the stress character may interchange—the associated models are, in general, inappropriate. The proposed approach provides a tool that has the potential (i) to improve procedural protocols and the design of interventional instruments on a lesion-specific basis, and (ii) to determine postangioplasty Mechanical environments, which may be correlated with restenosis responses. © 2002 Biomedical Engineering Society. PAC2002: 8719Rr, 8761Lh, 8710+e
Suchitra Sumitranholgersson - One of the best experts on this subject based on the ideXlab platform.
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isolation and characterization of human primary enterocytes from small intestine using a novel method
Scandinavian Journal of Gastroenterology, 2012Co-Authors: Priti Chougule, Gustaf Herlenius, Nidia Hernandez, P B Patil, Bo Xu, Suchitra SumitranholgerssonAbstract:Cell culture studies of enterocytes are important in many fields. However, there are difficulties in obtaining cell lines from adult human intestine, such as microbial contamination of cultures from the tissue samples, short life span of enterocytes, overgrowth of mesenchymal cells, etc. Various model used to obtain adult intestinal cell lines are very complex requiring use of feeder layer or gel matrices. The aim of this study was to establish a novel method for the simple and reproducible isolation of human enterocytes. Enterocytes were isolated from SI samples (n = 5) obtained from cadaveric donors using a Mechanical Procedure, and separation with immunomagnetic beads coated with anti-EpCAM antibodies. Light and electron microscopy, flow cytometry and immunocytochemistry techniques were used to characterize the isolated cells. Immunohistochemical staining of normal SB biopsies confirmed that the cell cultures maintained an in vivo phenotype as reflected in cytokeratin expression CK18, CK20 and expression of intestine-specific markers such as sucrase isomaltase and maltase glucoamylase. Furthermore, the cells strongly expressed TLR-5, 6, 7, 8 and 10 and several molecules such as CD40, CD86, CD44, ICAM-1 and HLA-DR which are important in triggering cell-mediated immune responses. This novel technique provides a unique in vitro system to study the biology of enterocytes in normal conditions as well as to study inflammatory processes in various small bowel disorders.
Byungkook Lee - One of the best experts on this subject based on the ideXlab platform.
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Relation between volume correction and the standard state.
Biophysical chemistry, 1994Co-Authors: Byungkook LeeAbstract:The suggestion by Sharp et al. (Biochemistry 30 (1991) 9686) that a volume correction should be made to the standard chemical potential of a non-polar solute molecule in water is examined by re-deriving their results using an exact statistical Mechanical Procedure and comparing them with those of a couple of other similar schemes. It is shown that their suggestion is equivalent to choosing a standard state based on the ideal gas behavior.
I. A. Ivanov - One of the best experts on this subject based on the ideXlab platform.
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Time evolution of the lateral-velocity distribution for a strong-field-ionization process
Physical Review A, 2016Co-Authors: I. A. IvanovAbstract:We study time development of a cusp in the lateral-velocity distribution for the process of strong-field ionization. The lateral-velocity distribution is computed using an ab initio quantum Mechanical Procedure for the moments of time inside and after the end of the laser pulse. We show that at the moment of time corresponding to the midpoint of the laser pulse the lateral-velocity distribution is a smooth Gaussian curve, its parameters agreeing very well with the predictions of the tunelling theories. At the moment of time corresponding to the end of the pulse the lateral-velocity distribution narrows considerably, showing the initial stage of the cusp-formation process due to the Coulomb focusing effect. Following evolution of the ionized wave packet yet further in time we consider the cusp formation in detail.