Non-Adiabatic Vibrational Damping of Molecular Adsorbates: Insights into Electronic Friction and the Role of Electronic Coherence

We present a perturbation approach rooted in time-dependent density-functional theory to calculate electron hole (eh)-pair excitation spectra during the non-adiabatic vibrational damping of adsorbates on metal surfaces. Our analysis for the benchmark systems CO on Cu(100) and Pt(111) elucidates the surprisingly strong influence of rather short electronic coherence times. We demonstrate how in the limit of short electronic coherence times, as implicitly assumed in prevalent quantum nuclear theories for the vibrational lifetimes as well as electronic friction, band structure effects are washed out. Our results suggest that more accurate lifetime or chemicurrent-like experimental measurements could characterize the electronic coherence.Comment: Article as accepted for publication in Physical Review Letter

Teaching in Europe and researching in the United States

No abstract available

Imitation and the Evolution of Walrasian Behavior: Theoretically Fragile but Behaviorally Robust

A well-known result by Vega-Redondo implies that in symmetric Cournot oligopoly, imitation leads to the Walrasian outcome where price equals marginal cost. In this paper we show that this result is not robust to the slightest asymmetry in fixed costs. Instead of obtaining the Walrasian outcome as unique prediction, every outcome where agents choose identical actions will be played some fraction of the time in the long run. We then conduct experiments to check this fragility. We obtain that, contrary to the theoretical prediction, the Walrasian outcome is still a good predictor of behavior.Evolutionary game theory; Stochastic stability; Imita- tion; Cournot markets; Information; Experiments; Simulations

Imitation and the Evolution of Walrasian Behavior: Theoretically Fragile but Behaviorally Robust

A well-known result by Vega-Redondo implies that in symmetric Cournot oligopoly, imitation leads to the Walrasian outcome where price equals marginal cost. In this paper we show that this result is not robust to the slightest asymmetry in fixed costs. Instead of obtaining the Walrasian outcome as unique prediction, every outcome where agents choose identical actions will be played some fraction of the time in the long run. We then conduct experiments to check this fragility. We obtain that, contrary to the theoretical prediction, the Walrasian outcome is still a good predictor of behavior.

Imitation and the Evolution of Walrasian Behavior: Theoretically Fragile but Behaviorally Robust

A well-known result by Vega-Redondo (1997) implies that in symmetric Cournot oligopoly, imitation leads to the Walrasian outcome where price equals marginal cost. In this paper, we show that this result is not robust to the slightest asymmetry in fixed costs. Instead of obtaining the Walrasian outcome as unique prediction, every outcome where agents choose identical actions will be played some fraction of the time in the long run. We then conduct experiments to check this fragility. We obtain that, contrary to the theoretical prediction, the Walrasian outcome is still a good predictor of behavior.evolutionary game theory, stochastic stability, imitation, Cournot markets, information, experiments, simulations

Electronic friction-based vibrational lifetimes of molecular adsorbates: Beyond the independent atom approximation

We assess the accuracy of vibrational damping rates of diatomic adsorbates on metal surfaces as calculated within the local-density friction approximation (LDFA). An atoms-in-molecules (AIM) type charge partitioning scheme accounts for intra-molecular contributions and overcomes the systematic underestimation of the non-adiabatic losses obtained within the prevalent independent atom approximation. The quantitative agreement obtained with theoretical and experimental benchmark data suggests the LDFA-AIM as an efficient and reliable approach to account for electronic dissipation in ab initio molecular dynamics simulations of surface chemical reactions.Comment: 5 pages including 2 figure

Succinate:quinone oxidoreductases from ϵ-proteobacteria11Dedicated to Achim Kröger on the occasion of his 65th birthday

AbstractThe ϵ-proteobacteria form a subdivision of the Proteobacteria including the genera Wolinella, Campylobacter, Helicobacter, Sulfurospirillum, Arcobacter and Dehalospirillum. The majority of these bacteria are oxidase-positive microaerophiles indicating an electron transport chain with molecular oxygen as terminal electron acceptor. However, numerous members of the ϵ-proteobacteria also grow in the absence of oxygen. The common presence of menaquinone and fumarate reduction activity suggests anaerobic fumarate respiration which was demonstrated for the rumen bacterium Wolinella succinogenes as well as for Sulfurospirillum deleyianum, Campylobacter fetus, Campylobacter rectus and Dehalospirillum multivorans. To date, complete genome sequences of Helicobacter pylori and Campylobacter jejuni are available. These bacteria and W. succinogenes contain the genes frdC, A and B encoding highly similar heterotrimeric enzyme complexes belonging to the family of succinate:quinone oxidoreductases. The crystal structure of the W. succinogenes quinol:fumarate reductase complex (FrdCAB) was solved recently, thus providing a model of succinate:quinone oxidoreductases from ϵ-proteobacteria. Succinate:quinone oxidoreductases are being discussed as possible therapeutic targets in the treatment of several pathogenic ϵ-proteobacteria

Direct-to-Consumer (DTC)-Marketing auf dem deutschen Pharmamarkt: Entwicklungsstand und Chancen

Der direkten Bewerbung von verschreibungspflichtigen Arzneimitteln beim Patienten – also dem Endkunden – sind in Deutschland enge Grenzen gesetzt. Das Heilmittelwerbegesetz dient hier seit 1965 dem Verbraucherschutz indem es das gesamte Werberecht auf dem Gebiet des Heilwesens unter folgenden Leitsatz stellt: „Die Werbung für Arzneimittel darf nach Art, Form und Inhalt nicht geeignet sein, den Entschluss zum Kauf, zur Verschreibung oder zur Anwendung des Arzneimittels unsachlich zu beeinflussen“. Auch auf europäischer Ebene wurden 1992 entsprechende Verordnungen zum Verbot von Werbemaßnahmen für verschreibungspflichtige Medikamente verabschiedet. Die pharmazeutische Industrie in Deutschland verhält sich angesichts der geltenden Vorschriften noch sehr zögerlich hinsichtlich ihrer auf den Endkunden gerichteten Maßnahmen. Andererseits hat man erkannt, dass die Patienten – und hier insbesondere die chronisch Kranken – in zunehmendem Maße gut informiert und emanzipiert sind und so auf die Verschreibungsgewohnheiten der Ärzte starken Einfluss ausüben. Aus dieser Erkenntnis heraus gewinnt die direkte Patientenansprache für die Arzneimittelhersteller an Bedeutung. Es besteht aber weiterhin eine große Unsicherheit bezüglich der rechtlichen Rahmenbedingungen und der Erfolgsaussichten beim Einsatz von Direct- to-Consumer (DTC)-Maßnahmen. Vor diesem Hintergrund skizziert der vorliegende Beitrag den Entwicklungsstand des DTC-Marketing in Deutschland. Die Aussagen basieren dabei auf einer unter den größten deutschen Pharmaherstellern durchgeführten Befragung von Marketing- Experten. Es wird weiterhin umschrieben, welche Möglichkeiten für pharmazeutische Anbieter auf dem deutschen Markt bestehen, verschreibungspflichtige Arzneimittel mit Maßnahmen des DTC-Marketing zu begleiten. Dabei wird auf Erfahrungen mit DTCMarketing in den USA und Neuseeland rekurriert. --

Terrestrial climate variability and seasonality changes in the Mediterranean region between 15 000 and 4000 years BP deduced from marine pollen records

Pollen-based climate reconstructions were performed on two high-resolution pollen marines cores from the Alboran and Aegean Seas in order to unravel the climatic variability in the coastal settings of the Mediterranean region between 15 000 and 4000 years BP (the Lateglacial, and early to mid-Holocene). The quantitative climate reconstructions for the Alboran and Aegean Sea records focus mainly on the reconstruction of the seasonality changes (temperatures and precipitation), a crucial parameter in the Mediterranean region. This study is based on a multi-method approach comprising 3 methods: the Modern Analogues Technique (MAT), the recent Non-Metric Multidimensional Scaling/Generalized Additive Model method (NMDS/GAM) and Partial Least Squares regression (PLS). The climate signal inferred from this comparative approach confirms that cold and dry conditions prevailed in the Mediterranean region during the Oldest and Younger Dryas periods, while temperate conditions prevailed during the Bølling/Allerød and the Holocene. Our records suggest a West/East gradient of decreasing precipitation across the Mediterranean region during the cooler Late-glacial and early Holocene periods, similar to present-day conditions. Winter precipitation was highest during warm intervals and lowest during cooling phases. Several short-lived cool intervals (i.e. Older Dryas, another oscillation after this one (GI-1c2), Gerzensee/Preboreal Oscillations, 8.2 ka event, Bond events) connected to the North Atlantic climate system are documented in the Alboran and Aegean Sea records indicating that the climate oscillations associated with the successive steps of the deglaciation in the North Atlantic area occurred in both the western and eastern Mediterranean regions. This observation confirms the presence of strong climatic linkages between the North Atlantic and Mediterranean regions