Theory of Out-of-Equilibrium Ultrafast Relaxation Dynamics in Metals

Ultrafast laser excitation of a metal causes correlated, highly nonequilibrium dynamics of electronic and ionic degrees of freedom, which are however only poorly captured by the widely-used two-temperature model. Here we develop an out-of-equilibrium theory that captures the full dynamic evolution of the electronic and phononic populations and provides a microscopic description of the transfer of energy delivered optically into electrons to the lattice. All essential nonequilibrium energy processes, such as electron-phonon and phonon-phonon interactions are taken into account. Moreover, as all required quantities are obtained from first-principles calculations, the model gives an exact description of the relaxation dynamics without the need for fitted parameters. We apply the model to FePt and show that the detailed relaxation is out-of-equilibrium for picoseconds.Comment: 6 pages, 5 figure

Solar wind effects on the outer ion coma of Comet Halley

A simple two-dimensional model is developed to examine the composition of the cometary ion coma in the region outside the ionopause which is strongly affected by the solar wind. Two-dimensional ion distributions are obtained assuming a cylindrically symmetric ion coma which accounts for the dynamic effects of the mass-loaded solar wind flow around the cometary ionosphere. The results of this model are discussed in the context of analyzing the GIOTTO ion data

Correlated exponential functions in high precision calculations for diatomic molecules

Various properties of the general two-center two-electron integral over the explicitly correlated exponential function are analyzed for the potential use in high precision calculations for diatomic molecules. A compact one dimensional integral representation is found, which is suited for the numerical evaluation. Together with recurrence relations, it makes possible the calculation of the two-center two-electron integral with arbitrary powers of electron distances. Alternative approach via the Taylor series in the internuclear distance is also investigated. Although numerically slower, it can be used in cases when recurrences lose stability. Separate analysis is devoted to molecular integrals with integer powers of interelectronic distances $r_{12}$ and the vanishing corresponding nonlinear parameter. Several methods of their evaluation are proposed.Comment: 26 pages, includes two tables with exemplary calculation

Human endothelial dysfunction: EDRFs

Since the detection of nitric oxide two and a half decades ago, there has been an incredible boost in endothelial function research, which is fascinating the research community. Physiologically, endothelial cells synthesize a number of vasoactive substances. In particular, several endothelium-derived relaxing factors (EDRFs) have been characterized, whereby nitric oxide is the most important. In humans, endothelial dysfunction is one of the first clinically detectable alterations in the development of atherosclerosis and is characterized by an imbalance in the release of vasoactive substances. Thus, it is the aim of this article to give an overview about endothelial function in humans, to summarize the different possibilities to assess endothelial function in this species, and to give an overview of the role of EDRFs in different cardiovascular disease

Einfluss antihypertensiver Medikamente auf die Endothelfunktion

Zusammenfassung: Bei Patienten mit arterieller Hypertonie liegt eine Endotheldysfunktion vor. Eine reduzierte Verfügbarkeit von gefäßerweiterndem Stickstoffmonoxid (NO) sowie ein Überschuss an vasokonstriktiven Substanzen (z.B. Endothelin oder Angiotensin II) sind als Ursache der gestörten endothelabhängigen Vasodilatation anzusehen. Das Vorhandensein einer Endotheldysfunktion korreliert mit kardiovaskulären Ereignissen und hat auch prognostische Bedeutung. Die Reduktion des Blutdrucks per se ist nicht ausreichend, um die Endothelfunktion zu verbessern. Die verschiedenen Substanzklassen der Antihypertensiva beeinflussen die Gefäßfunktion in unterschiedlicher Art und Weis