University of Würzburg

About: University of Würzburg is a education organization based out in Wurzburg, Bayern, Germany. It is known for research contribution in the topics: Population & Gene. The organization has 31437 authors who have published 62203 publications receiving 2337033 citations. The organization is also known as: Julius-Maximilians-Universität Würzburg & Würzburg University.

Hidden symmetries in the energy levels of excitonic 'artificial atoms'

Abstract: Quantum dots1,2,3,4,5,6,7 or ‘artificial atoms’ are of fundamental and technological interest—for example, quantum dots8,9 may form the basis of new generations of lasers The emission in quantum-dot lasers originates from the recombination of excitonic complexes, so it is important to understand the dot's internal electronic structure (and of fundamental interest to compare this to real atomic structure) Here we investigate artificial electronic structure by injecting optically a controlled number of electrons and holes into an isolated single quantum dot The charge carriers form complexes that are artificial analogues of hydrogen, helium, lithium, beryllium, boron and carbon excitonic atoms We observe that electrons and holes occupy the confined electronic shells in characteristic numbers according to the Pauli exclusion principle In each degenerate shell, collective condensation of the electrons and holes into coherent many-exciton ground states takes place; this phenomenon results from hidden symmetries (the analogue of Hund's rules for real atoms) in the energy function that describes the multi-particle system Breaking of the hidden symmetries leads to unusual quantum interferences in emission involving excited states

SGLT-2 inhibitors and cardiovascular risk: Proposed pathways and review of ongoing outcome trials

Abstract: Given the multi-faceted pathogenesis of atherosclerosis in type 2 diabetes mellitus (T2DM), it is likely that interventions to mitigate this risk must address cardiovascular (CV) risk factors beyond glucose itself. Sodium glucose cotransporter-2 (SGLT-2) inhibitors are newer antihyperglycaemic agents with apparent multiple effects. Inherent in their mode of action to decrease glucose reabsorption by the kidneys by increasing urinary glucose excretion, these agents improve glycaemic control independent of insulin secretion with a low risk of hypoglycaemia. In this review, we outline those CV risk factors that this class appears to influence and provide the design features and trial characteristics of six ongoing outcome trials involving more than 41,000 individuals with T2DM. Those risk factors beyond glucose that can potentially be modulated positively with SGLT-2 inhibitors include blood pressure, weight, visceral adiposity, hyperinsulinaemia, arterial stiffness, albuminuria, circulating uric acid levels and oxidative stress. On the other hand, small increases in low-density lipoprotein (LDL)-cholesterol levels have also been observed for the class, which theoretically might offset some of these benefits. The potential translational impact of these effects is being tested with outcome trials, also reviewed in this article, powered to assess both macrovascular as well as certain microvascular outcomes in T2DM. These are expected to begin to report in late 2015.

Femtosecond pulse shaping by an evolutionary algorithm with feedback

Abstract: We report on computer controlled compression of femtosecond laser pulses using a programmable liquid crys- tal spatial light modulator which is feedback-controlled by an evolutionary algorithm. This algorithm generates the opti- mal laser field on the basis of feedback from the experiment by optimizing the laser pulse iteratively. Without knowledge of the (chirped) input pulses, the experimental signal (second harmonic light=SHG) is maximized by the algorithm, thus re- sulting in fully compressed pulses. This method only makes use of the experiment's response (SHG signal) on the formed pulses. No other parameters need to be considered. This ap- proach leads to many experimental applications in all fields of optics and ultrafast spectroscopy where particularly shaped pulses are advantageous.

Quantification of YouTube QoE via Crowdsourcing

Abstract: This paper addresses the challenge of assessing and modeling Quality of Experience (QoE) for online video services that are based on TCP-streaming. We present a dedicated QoE model for You Tube that takes into account the key influence factors (such as stalling events caused by network bottlenecks) that shape quality perception of this service. As second contribution, we propose a generic subjective QoE assessment methodology for multimedia applications (like online video) that is based on crowd sourcing - a highly cost-efficient, fast and flexible way of conducting user experiments. We demonstrate how our approach successfully leverages the inherent strengths of crowd sourcing while addressing critical aspects such as the reliability of the experimental data obtained. Our results suggest that, crowd sourcing is a highly effective QoE assessment method not only for online video, but also for a wide range of other current and future Internet applications.