Waiting time distribution for electron transport in a molecular junction with electron-vibration interaction

On the elementary level, electronic current consists of individual electron tunnelling events that are separated by random time intervals. The waiting time distribution is a probability to observe the electron transfer in the detector electrode at time $t+\tau$ given that an electron was detected in the same electrode at earlier time $t$. We study waiting time distribution for quantum transport in a vibrating molecular junction. By treating the electron-vibration interaction exactly and molecule-electrode coupling perturbatively, we obtain master equation and compute the distribution of waiting times for electron transport. The details of waiting time distributions are used to elucidate microscopic mechanism of electron transport and the role of electron-vibration interactions. We find that as nonequilibrium develops in molecular junction, the skewness and dispersion of the waiting time distribution experience stepwise drops with the increase of the electric current. These steps are associated with the excitations of vibrational states by tunnelling electrons. In the strong electron-vibration coupling regime, the dispersion decrease dominates over all other changes in the waiting time distribution as the molecular junction departs far away from the equilibrium

Hadron Spectroscopy with Dynamical Chirally Improved Fermions

We simulate two dynamical, mass degenerate light quarks on 16^3x32 lattices with a spatial extent of 2.4 fm using the Chirally Improved Dirac operator. The simulation method, the implementation of the action and signals of equilibration are discussed in detail. Based on the eigenvalues of the Dirac operator we discuss some qualitative features of our approach. Results for ground state masses of pseudoscalar and vector mesons as well as for the nucleon and delta baryons are presented.Comment: 26 pages, 17 figures, 10 table

BaWü-labs on their way : progress of real-world laboratories in Baden-Württemberg

Real-world laboratories aim to create relevant and transferable knowledge and foster societal transformation towards sustainability. Members of the existing laboratories in Baden-Württemberg and experts have discussed the progress and the challenges of these innovative research settings

Lessons Learned from Two Case Studies in Higher Education

As places where future citizens are educated, knowledge is (co-)produced and societal developments are critically reflected, higher education institutions (HEIs) can play a key role in addressing sustainability challenges. In order to accelerate mutual learning, shared problem understanding, and joint development of sustainable solutions, interinstitutional exchange and collaboration between HEIs is crucial. However, little research to date has focused on institutional HEI networks in the field of sustainability. More specifically, we still understand little about the concrete development, implementation, and adaptation of such networks. This article explores early-stage HEI networks for sustainability from a conceptual and empirical stance in order to develop a framework that facilitates structured descriptions of these networks, as well as to foster cross-HEI learning on their effective performance. It therefore combines insights from an explorative literature review, two case studies and an interactive workshop at the ISCN Conference 2018. As results, we first suggest an analytical framework to facilitate a systematic characterization of HEI networks. Second, by applying the framework to the two case studies, we present and discuss lessons learned on how a single HEI can contribute to establishing a network and how it can utilize its network membership effectively to strengthen its efforts for sustainability

Robustness of superconductivity to competing magnetic phases in tetragonal FeS

We have determined the superconducting and magnetic properties of a hydrothermally synthesized powder sample of tetragonal FeS using muon spin rotation ({\mu}SR). The superconducting properties are entirely consistent with those of a recently published study, showing fully gapped behavior and giving a penetration depth of {\lambda}_{ab} = 204(3) nm. However, our zero-field {\mu}SR data are rather different and indicate the presence of a small, non-superconducting magnetic phase within the sample. These results highlight that sample-to-sample variations in magnetism can arise in hydrothermally prepared phases, but interestingly the superconducting behavior is remarkably insensitive to these variations.Comment: 5 pages, 2 figure

Reallabore im Kontext transformativer Forschung : Ansatzpunkte zur Konzeption und Einbettung in den internationalen Forschungsstand

Reallabore sind derzeit ein populärer Forschungsansatz an der Schnittstelle zwischen Wissenschaft und Gesellschaft. Neben vermuteten Potentialen, wie der Erzeugung von Transformationswissen und einem Beitrag zu gesellschaftlichem Wandel, gibt es auch vielfältige offene Fragen, u. a. im Hinblick auf das Verhältnis zu transdisziplinärer Forschung, der Übertragbarkeit des erzeugten Wissens oder der Gestaltung von Experimenten in der "realen Welt". Auch eine breit getragene Definition von Reallaboren existiert derzeit nicht. Dieses Diskussionspapier möchte daher dreierlei leisten: Es beginnt mit dem Herausarbeiten von Reallabor-Merkmalen als a) Beitrag zu Transformationsprozessen, b) Experimenten als zentraler Forschungsmethode, c) Transdisziplinarität als Forschungsmodus, d) dem Ziel der Ausweitung und Übertragung der Ergebnisse und e) Reallaboren als Orten wissenschaftlichen und gesellschaftlichen Lernens. Im Nachgang werden diese Merkmale durch Rückbezug auf die einschlägige Literatur vertieft diskutiert. Abschließend werden mit Reallaboren vergleichbare Forschungsansätze (Sustainable Living Labs, Urban Transition Labs und Niche Experiments) im Hinblick auf ihre Ausgestaltung der fünf herausgearbeiteten Merkmale vorgestellt und Reallabore damit in den internationalen Forschungskontext eingebettet. Das Diskussionspapier will damit Forschenden und Praktiker_innen in Reallaboren eine Orientierung ermöglichen. Die vorgestellten konzeptionellen Überlegungen basieren auf einem thematischen Literatur-Review, ebenso wie Diskussionen mit Reallabor- und Transformationsforschenden in nationalen und internationalen Kontexten. Sie sind im Rahmen der Begleitforschung des Forschungsprojektes "ForReal" zu den Baden-Württembergischen Reallaboren entstanden. Dem Charakter eines Diskussionspapieres entsprechend sind die hier vorstellten Rahmungen zum Reallaboransatz als Angebot zur Diskussion, Erweiterung und Verbesserung zu verstehen

A new physical interpretation of optical and infrared variability in quasars

Changing-look quasars are a recently identified class of active galaxies in which the strong UV continuum and/or broad optical hydrogen emission lines associated with unobscured quasars either appear or disappear on timescales of months to years. The physical processes responsible for this behaviour are still debated, but changes in the black hole accretion rate or accretion disk structure appear more likely than changes in obscuration. Here we report on four epochs of spectroscopy of SDSS J110057.70-005304.5, a quasar at a redshift of $z=0.378$ whose UV continuum and broad hydrogen emission lines have faded, and then returned over the past $\approx$20 years. The change in this quasar was initially identified in the infrared, and an archival spectrum from 2010 shows an intermediate phase of the transition during which the flux below rest-frame $\approx$3400\AA\ has decreased by close to an order of magnitude. This combination is unique compared to previously published examples of changing-look quasars, and is best explained by dramatic changes in the innermost regions of the accretion disk. The optical continuum has been rising since mid-2016, leading to a prediction of a rise in hydrogen emission line flux in the next year. Increases in the infrared flux are beginning to follow, delayed by a $\sim$3 year observed timescale. If our model is confirmed, the physics of changing-look quasars are governed by processes at the innermost stable circular orbit (ISCO) around the black hole, and the structure of the innermost disk. The easily identifiable and monitored changing-look quasars would then provide a new probe and laboratory of the nuclear central engine.Comment: 13 pages, 4 figures, 3 tables. Published in MNRAS. All code and data links on GitHub, https://github.com/d80b2t/WISE_L