Examination of the concept of degree of rate control by first-principles kinetic Monte Carlo simulations

The conceptual idea of degree of rate control (DRC) approaches is to identify the "rate limiting step" in a complex reaction network by evaluating how the overall rate of product formation changes when a small change is made in one of the kinetic parameters. We examine two definitions of this concept by applying it to first-principles kinetic Monte Carlo simulations of the CO oxidation at RuO2(110). Instead of studying experimental data we examine simulations, because in them we know the surface structure, reaction mechanism, the rate constants, the coverage of the surface and the turn-over frequency at steady state. We can test whether the insights provided by the DRC are in agreement with the results of the simulations thus avoiding the uncertainties inherent in a comparison with experiment. We find that the information provided by using the DRC is non-trivial: It could not have been obtained from the knowledge of the reaction mechanism and of the magnitude of the rate constants alone. For the simulations the DRC provides furthermore guidance as to which aspects of the reaction mechanism should be treated accurately and which can be studied by less accurate and more efficient methods. We therefore conclude that a sensitivity analysis based on the DRC is a useful tool for understanding the propagation of errors from the electronic structure calculations to the statistical simulations in first-principles kinetic Monte Carlo simulations.Comment: 27 pages including 5 figures; related publications can be found at http://www.fhi-berlin.mpg.de/th/th.htm

Matter Induced Bimetric Actions for Gravity

The gravitational effective average action is studied in a bimetric truncation with a nontrivial background field dependence, and its renormalization group flow due to a scalar multiplet coupled to gravity is derived. Neglecting the metric contributions to the corresponding beta functions, the analysis of its fixed points reveals that, even on the new enlarged theory space which includes bimetric action functionals, the theory is asymptotically safe in the large $N$ expansion.Comment: 34 pages, no figures

Bimetric Renormalization Group Flows in Quantum Einstein Gravity

The formulation of an exact functional renormalization group equation for Quantum Einstein Gravity necessitates that the underlying effective average action depends on two metrics, a dynamical metric giving the vacuum expectation value of the quantum field, and a background metric supplying the coarse graining scale. The central requirement of "background independence" is met by leaving the background metric completely arbitrary. This bimetric structure entails that the effective average action may contain three classes of interactions: those built from the dynamical metric only, terms which are purely background, and those involving a mixture of both metrics. This work initiates the first study of the full-fledged gravitational RG flow, which explicitly accounts for this bimetric structure, by considering an ansatz for the effective average action which includes all three classes of interactions. It is shown that the non-trivial gravitational RG fixed point central to the Asymptotic Safety program persists upon disentangling the dynamical and background terms. Moreover, upon including the mixed terms, a second non-trivial fixed point emerges, which may control the theory's IR behavior.Comment: 35 pages, 3 figure

Non-Commutative Geometry, Multiscalars, and the Symbol Map

Starting from the concept of the universal exterior algebra in non-commutative differential geometry we construct differential forms on the quantum phase-space of an arbitrary system. They bear the same natural relationship to quantum dynamics which ordinary tensor fields have with respect to classical hamiltonian dynamics.Comment: 8 pages, late

Übertragbarkeit von Erfolgsfaktoren der Pionierländer des Ökolandbaus auf die mittel- und osteuropäischen Länder

Ergebnisse/Diskussion: Die ermittelten Erfolgsfaktoren in den Pionierländern Österreich und Schweiz gliedern sich zum Einen in das indirekte und zum Anderen in das direkte Marktumfeld. Im indirekten Marktumfeld sind die Vernetzheit der Akteure am Markt, die Oligopol-Stellung entlang der Vermarktungs- und Verarbeitungskette, die transparente Verwendung der Biolabel und das Interesse der Konsumenten verantwortlich für eine erfolgreiche Marktentwicklung. Da die zu erschließenden Märkte relativ klein waren, teilte sich die Marktmacht schnell auf. So existiert z.B. in der Schweiz der zentrale Dachverband BIO SUISSE, der mit seinem bekannten Knospe-Label ein staatliches Biosiegel überflüssig macht. Daneben gibt es auf Handelsseite die Coop und die Migros, die um Ökomarktanteile kämpfen und den Markt dominieren. Im direkten Marktumfeld sind vor allem das Engagement des Einzelhandels (Investitionsbereitschaft, Pflege der Sortimente etc.) und die Kooperation unter den Bioverbänden als Erfolgsfaktoren zu nennen. Fazit: Die mittel- und osteuropäischen Länder sind aufgrund ihrer Geschichte noch in der Phase der Marktentwicklung, in der Bioprodukte auf dem Binnemarkt eine Nische ausfüllen. Begrenzte Kapitalressourcen und Liquiditätsprobleme bei den Produzenten und Verarbeitern behindern Investitionen. Bisher mangelt es bei der Entwicklung der Ökomärkte vor allem an einer Vernetzung der Akteure in Politik, Produktion, Markt und Wissenschaft. Für die erfolgreiche Weiterentwicklung der ökologischen Landwirtschaft ist der Ausbau von Verarbeitungskapazitäten und die Schaffung on Absatzkanälen notwendig. Basierend auf dem internationalen Vergleich lässt sich außerdem ableiten, dass eine Zersplitterung die erfolgreiche Marktorganisation behindert und daher vermieden werden sollte. Von staatlicher Seite aus kann eine deutliche Unterstützung das Wachstum im Ökomarkt stabilisieren und ausbauen. Nur die Länder, denen es zukünftig gelingt, einen Binnenmarkt für Bioprodukte zu entwickeln, werden unabhängig von importierenden Ländern produzieren können und nicht dem Preisdruck nach unten nachgeben müssen

The Socialist Impact on Christian-Muslim Shared St. Naum Monastery

Shared religious places may be provocative phenomena—for the members of the sharing communities as well as for uninvolved observers. An increasing number of research literature focusing on the contesting character of such places and the consequences for the identities of sharing communities serves as evidence for that thesis. The heads of the theoretical discussion regarding the influence of sharing religious and political identities are the anthropologists, Robert Hayden and Glenn Bowman. Due to the long-lasting Christian- Muslim contacts characterized by peaceful as well as conflicting interaction, both bring examples from Southeastern Europe, especially from the post-Yugoslavian context. It is obvious that the conclusion is based on the historic events they emphasize as significant identity markers. In fact, every historic period with its political system and ideas influences the negotiation of the past and the creation of current religious and political identities. Based on qualitative-empirical fieldwork data and historic findings, this article investigates the socialist impact on the Christian and Muslim contact at the Sveti Naum Monastery in Macedonia, as an example for shared religious places