University of Konstanz

About: University of Konstanz is a education organization based out in Konstanz, Baden-Württemberg, Germany. It is known for research contribution in the topics: Population & Visualization. The organization has 12115 authors who have published 27401 publications receiving 951162 citations. The organization is also known as: University of Constance & Universität Konstanz.

Observation of molecular orbital gating.

Abstract: The ultimate in electronic device miniaturization would be the creation of circuit elements consisting of an individual molecule. A single-molecule transistor exploiting the electrostatic modulation of a molecule's orbital energy is a theoretical possibility. Now Hyunwook Song and colleagues report the successful realization of such a device, a proof of concept that should enhance the practical prospects for molecularly engineered electronics. A longstanding aim in molecular-scale electronics is to create a true transistor analogue in which charge transport through a molecule is directly controlled by external modulation of the molecular orbitals. The observation of such a solid-state molecular device is now reported. The data demonstrate that true molecular transistors can be created, and clear the way for molecularly engineered electronic devices. The control of charge transport in an active electronic device depends intimately on the modulation of the internal charge density by an external node1. For example, a field-effect transistor relies on the gated electrostatic modulation of the channel charge produced by changing the relative position of the conduction and valence bands with respect to the electrodes. In molecular-scale devices2,3,4,5,6,7,8,9,10, a longstanding challenge has been to create a true three-terminal device that operates in this manner (that is, by modifying orbital energy). Here we report the observation of such a solid-state molecular device, in which transport current is directly modulated by an external gate voltage. Resonance-enhanced coupling to the nearest molecular orbital is revealed by electron tunnelling spectroscopy, demonstrating direct molecular orbital gating in an electronic device. Our findings demonstrate that true molecular transistors can be created, and so enhance the prospects for molecularly engineered electronic devices.

Switching off mentally: predictors and consequences of psychological detachment from work during off-job time.

Abstract: Psychological detachment from work refers to the off-job experience of "switching off" mentally. It is hypothesized that a high degree of workload encountered during the work day has a negative impact on subsequent detachment processes and that psychological detachment from work is positively related to well-being. Eighty-seven individuals from various occupations provided questionnaire and daily survey measures over a period of 3 working days. Multilevel analysis showed that workload was negatively related to psychological detachment from work during evening hours. Psychological detachment from work was associated with positive mood and low fatigue. The negative relationship between psychological detachment and fatigue was particularly strong on days with high time pressure.

Machine learning & artificial intelligence in the quantum domain: a review of recent progress.

Abstract: Quantum information technologies, on the one hand, and intelligent learning systems, on the other, are both emergent technologies that are likely to have a transformative impact on our society in the future. The respective underlying fields of basic research-quantum information versus machine learning (ML) and artificial intelligence (AI)-have their own specific questions and challenges, which have hitherto been investigated largely independently. However, in a growing body of recent work, researchers have been probing the question of the extent to which these fields can indeed learn and benefit from each other. Quantum ML explores the interaction between quantum computing and ML, investigating how results and techniques from one field can be used to solve the problems of the other. Recently we have witnessed significant breakthroughs in both directions of influence. For instance, quantum computing is finding a vital application in providing speed-ups for ML problems, critical in our 'big data' world. Conversely, ML already permeates many cutting-edge technologies and may become instrumental in advanced quantum technologies. Aside from quantum speed-up in data analysis, or classical ML optimization used in quantum experiments, quantum enhancements have also been (theoretically) demonstrated for interactive learning tasks, highlighting the potential of quantum-enhanced learning agents. Finally, works exploring the use of AI for the very design of quantum experiments and for performing parts of genuine research autonomously, have reported their first successes. Beyond the topics of mutual enhancement-exploring what ML/AI can do for quantum physics and vice versa-researchers have also broached the fundamental issue of quantum generalizations of learning and AI concepts. This deals with questions of the very meaning of learning and intelligence in a world that is fully described by quantum mechanics. In this review, we describe the main ideas, recent developments and progress in a broad spectrum of research investigating ML and AI in the quantum domain.

Sympatric speciation in Nicaraguan crater lake cichlid fish

Abstract: One of the hottest controversies in evolutionary biology is sympatric speciation, the formation of new species in the absence of geographical boundaries. The controversy is about whether it happens or not: it ‘should’ in theory but it is difficult to prove it. Two new examples of the phenomenon are reported this week, one in fish and one (online) in plants, convincing evidence that as Darwin suggested, sympatric speciation is likely to be common. The fishy example is the formation of Amphilophus zaliosus from A. citrinellus in a volcanic crater lake in Nicaragua. And in plants, the curly palm Howea belmoreana and the thatch palm H. forsteriana diverged on Lord Howe Island, a volcanic island 480 km east of Australia in the Tasman Sea. Sympatric speciation, the formation of species in the absence of geographical barriers, remains one of the most contentious concepts in evolutionary biology. Although speciation under sympatric conditions seems theoretically possible1,2,3,4,5, empirical studies are scarce and only a few credible examples of sympatric speciation exist6. Here we present a convincing case of sympatric speciation in the Midas cichlid species complex (Amphilophus sp.) in a young and small volcanic crater lake in Nicaragua. Our study includes phylogeographic, population-genetic (based on mitochondrial DNA, microsatellites and amplified fragment length polymorphisms), morphometric and ecological analyses. We find, first, that crater Lake Apoyo was seeded only once by the ancestral high-bodied benthic species Amphilophus citrinellus, the most common cichlid species in the area; second, that a new elongated limnetic species (Amphilophus zaliosus) evolved in Lake Apoyo from the ancestral species (A. citrinellus) within less than ∼10,000 yr; third, that the two species in Lake Apoyo are reproductively isolated; and fourth, that the two species are eco-morphologically distinct.

Nanophase-Separated Polymer Films as High-Performance Antireflection Coatings

Abstract: Optical surfaces coated with a thin layer to improve light transmission are ubiquitous in everyday optical applications as well as in industrial and scientific instruments. Discovered first in 1817 by Fraunhofer, the coating of lenses became standard practice in the 1930s. In spite of intensive research, broad-band antireflection coatings are still limited by the lack of materials with low refractive indices. A method based on the phase separation of a macromolecular liquid to generate nanoporous polymer films is demonstrated that creates surfaces with high optical transmission.