Interacting System (interacting + system)

Distribution by Scientific Domains


Selected Abstracts


Combined use of nuclear magnetic resonance and infrared spectroscopy for studying recognition processes between amphenicolic antibiotics and albumin

MAGNETIC RESONANCE IN CHEMISTRY, Issue 7 2003
Silvia Martini
Abstract Biological reactions are mostly concerned with selective interactions between small ligands and macromolecular receptors. The same ligands may activate responses of different intensities and/or effects in the presence of different receptors. Many approaches based on spectroscopic and non-spectroscopic methods have been used to study interactions between small ligands and macromolecular receptors, including methods based on NMR and IR spectroscopic analysis of the solution behaviour of the ligand in the presence of receptors. In this work, we investigated the interaction between ovine serum albumin with two amphenicolic antibiotics [chloramphenicol (CAP) and thiamphenicol (TAP)], using a combined approach based on NMR and IR methodologies, furnishing complementary information about the recognition process occurring within the two systems. The two ligands, despite their similar structures, showed different affinities towards albumin. NMR methodology is based on the comparison of selective () and non-selective () spin,lattice relaxation rates of the ligands in the presence and absence of macromolecular receptors and and temperature dependence analysis. From these studies, the ligand,receptor binding strength was evaluated on the basis of the ,affinity index.' The derivation of the affinity index from chemical equilibrium kinetics for both the CAP,albumin and TAP,albumin systems allowed a comparison of the abilities of the two amphenicolic antibiotics to interact with the protein. IR methodology is based on the comparison of the ligand,protein ,complex' spectra with those of the non-interacting systems. On the basis of the differences revealed, a more thorough IR analysis was performed in order to understand the structural changes which occurred on both ligand and protein molecules within the interacting system. Copyright © 2003 John Wiley & Sons, Ltd. [source]


Equilibration of a dissipative quantum oscillator

ANNALEN DER PHYSIK, Issue 5-6 2007
V. Ambegaokar
Abstract An explicit demonstration is given of a harmonic oscillator in equilibrium approaching the equilibrium of a corresponding interacting system by coupling it to a thermal bath consisting of a continuum of harmonic oscillators. [source]


A study of major mergers using a multi-phase ISM code

ASTRONOMISCHE NACHRICHTEN, Issue 9-10 2009
J. Weniger
Abstract Galaxy interactions are a common phenomenon in clusters of galaxies. Especially major mergers are of particular importance, because they can change the morphological type of galaxies. They have an impact on the mass function of galaxies and they trigger star formation , the main driver of the Galactic Matter Cycle. Therefore, we conducted a study of major mergers by means of a multi-phase ISM code. This code is based on a TREE-SPH-code combined with a sticky particle method allowing for star formation controlled by the properties of a multi-phase ISM. This is in contrast to the usually implemented Schmidt law depending mainly on the gas density. Previously, this code was used on isolated galaxies. Since our star formation recipe is not restricted to a special type of galaxy, it is interesting to apply it to interacting galaxies, too. Our study on major mergers includes a research of global properties of the interacting system, namely the star formation rate and the star formation efficiency, the evaporation and condensation rates, as well as the mass exchange of distinct components, namely stars, diffuse ISM, and clouds. Investigating these properties provides insight to interrelations between various physical processes. The results indicate that the star formation efficiency as well as the evaporation and condensation rates are influenced by the interaction (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Autoantigens in systemic autoimmunity: critical partner in pathogenesis

JOURNAL OF INTERNAL MEDICINE, Issue 6 2009
A. Rosen
Abstract. Understanding the mechanisms of human autoimmune rheumatic diseases presents a major challenge, due to marked complexity involving multiple domains, including genetics, environment and kinetics. In spite of this, the immune response in each of these diseases is largely specific, with distinct autoantibodies associated with different disease phenotypes. Defining the basis of such specificity will provide important insights into disease mechanism. Accumulating data suggest an interesting paradigm for antigen selection in autoimmunity, in which target tissue and immune effector pathways form a mutually reinforcing partnership. In this model, distinct autoantibody patterns in autoimmunity may be viewed as the integrated, amplified output of several interacting systems, including: (i) the specific target tissue, (ii) the immune effector pathways that modify antigen structure and cause tissue damage and dysfunction, and (iii) the homeostatic pathways activated in response to damage (e.g. regeneration/differentiation/cytokine effects). As unique antigen expression and structure may occur exclusively under these amplifying circumstances, it is useful to view the molecules targeted as ,neo-antigens', that is, antigens expressed under specific conditions, rather than ubiquitously. This model adds an important new dynamic element to selection of antigen targets in autoimmunity, and suggests that the amplifying loop will only be identified by studying the diseased target tissue in vivo. [source]


Electron-electron relaxation in disordered interacting systems

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2008
Peter Bozsoki
Abstract We study the relaxation of a non-equilibrium carrier distribution under the influence of the electron-electron interaction in the presence of disorder. Based on the Anderson model, our Hamiltonian is composed from a single particle part including the disorder and a two-particle part accounting for the Coulomb interaction. We apply the equation-of-motion approach for the density matrix, which provides a fully microscopic description of the relaxation. Our results show that the nonequilibrium distribution in this closed and internally interacting system relaxes exponentially fast during the initial dynamics. This fast relaxation can be described by a phenomenological damping rate. The total single particle energy decreases in the redistribution process, keeping the total energy of the system fixed. It turns out that the relaxation rate decreases with increasing disorder. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]