Semitransparency in interaction-free measurements

We discuss the effect of semitransparency in a quantum-Zeno-like interaction-free measurement setup, a quantum-physics based approach that might significantly reduce sample damage in imaging and microscopy. With an emphasis on applications in electron microscopy, we simulate the behavior of probe particles in an interaction-free measurement setup with semitransparent samples, and we show that the transparency of a sample can be measured in such a setup. However, such a measurement is not possible without losing (i.e., absorbing or scattering) probe particles in general, which causes sample damage. We show how the amount of lost particles can be minimized by adjusting the number of round trips through the setup, and we explicitly calculate the amount of lost particles in measurements which either aim at distinguishing two transparencies or at measuring an unknown transparency precisely. We also discuss the effect of the sample causing phase shifts in interaction-free measurements. Comparing the resulting loss of probe particles with a classical measurement of transparency, we find that interaction-free measurements only provide a benefit in two cases: first, if two semitransparent samples with a high contrast are to be distinguished, interaction-free measurements lose less particles than classical measurements by a factor that increases with the contrast. This implies that interaction-free measurements with zero loss are possible if one of the samples is perfectly transparent. A second case where interaction-free measurements outperform classical measurements is if three conditions are met: the particle source exhibits Poissonian number statistics, the number of lost particles cannot be measured, and the transparency is larger than approximately 1/2. In all other cases, interaction-free measurements lose as many probe particles as classical measurements or more.Comment: 11 pages, 10 figure

Leader 4.0: Umgang mit der Digital Skills Gap im Unternehmen

Digitalisierung ist inzwischen in nahezu allen Lebensbereichen omnipräsent, besonders Unternehmen müssen daher den Weg der digitalen Transformation gehen, um weiterhin auf dem Markt relevant zu bleiben. Vor allem der Umgang mit der Digital Skills Gap stellt für Unternehmen eine Herausforderung dar. Dies führt zu einer veränderten Arbeitswelt und damit zu dem Bedarf an einem neuen Führungskonzept, dem Leader 4.0. Obwohl diesem Thema eine hohe Bedeutung zukommt, die sich in der Zukunft noch verstärken wird, gibt es hierzu bisher nicht viele Forschungsansätze. Diese Arbeit bietet daher eine Zusammenstellung der in der Literatur bereits aufgeführten Eigenschaften und Fähigkeiten, welche einen Leader 4.0 ausmachen sowie Strategien des Leader 4.0 zur Lösung der Problematik der Digital Skills Gap. Hierfür werden mittels einer systematischen Literaturrecherche zunächst die digitale Transformation im Unternehmen und ihre Herausforderungen als Ursache der Veränderungen in der Arbeitswelt betrachtet. Weiterhin werden auf Basis dieser neuen Anforderungen notwendige Kompetenzen eines Leader 4.0 aus der Literatur zusammengetragen. Abschließend erläutert dieser Text Möglichkeiten, wie der Leader 4.0 der Digital Skills Gap im Unternehmen begegnen kann. Besonders im Bereich der Digital Skills Gap gibt es noch einen hohen Forschungsbedarf, den weitere Arbeiten adressieren sollten.:Motivation Schlüsselkonzepte Digitale Transformation im Unternehmen Die Digital Skills Gap und der Leader 4.0 Zusammenfassun

Combining Cluster Validation Indices for Detecting Label Noise

In this paper, we show that cluster validation indices can be used for filtering mislabeled instances or class outliers prior to training in supervised learning problems. We propose a technique, entitled Cluster Validation Index (CVI)-based Outlier Filtering, in which mislabeled instances are identified and eliminated from the training set, and a classification hypothesis is then built from the set of remaining instances. The proposed approach assigns each instance several cluster validation scores representing its potential of being an outlier with respect to the clustering properties the used validation measures assess. We examine CVI-based Outlier Filtering and compare it against the Local Outlier Factor (LOF) detection method on ten data sets from the UCI data repository using five well-known learning algorithms and three different cluster validation indices. In addition, we study and compare three different approaches for combining the selected cluster validation measures. Our results show that for most learning algorithms and data sets, the proposed CVI-based outlier filtering algorithm outperforms the baseline method (LOF). The greatest increase in classification accuracy has been achieved by using union or ranked-based median strategies to assemble the used cluster validation indices and global filtering of mislabeled instances

Finite-Temperature Collective Dynamics of a Fermi Gas in the BEC-BCS Crossover

We report on experimental studies on the collective behavior of a strongly interacting Fermi gas with tunable interactions and variable temperature. A scissors mode excitation in an elliptical trap is used to characterize the dynamics of the quantum gas in terms of hydrodynamic or near-collisionless behavior. We obtain a crossover phase diagram for collisional properties, showing a large region where a non-superfluid strongly interacting gas shows hydrodynamic behavior. In a narrow interaction regime on the BCS side of the crossover, we find a novel temperature-dependent damping peak, suggesting a relation to the superfluid phase transition

Dynamics of a strongly interacting Fermi gas: the radial quadrupole mode

We report on measurements of an elementary surface mode in an ultracold, strongly interacting Fermi gas of 6Li atoms. The radial quadrupole mode allows us to probe hydrodynamic behavior in the BEC-BCS crossover without being influenced by changes in the equation of state. We examine frequency and damping of this mode, along with its expansion dynamics. In the unitarity limit and on the BEC side of the resonance, the observed frequencies agree with standard hydrodynamic theory. However, on the BCS side of the crossover, a striking down shift of the oscillation frequency is observed in the hydrodynamic regime as a precursor to an abrupt transition to collisionless behavior; this indicates coupling of the oscillation to fermionic pairs.Comment: 11 pages, 11 figures v2: minor change

The development of the Femme fatale in Film Noir

Im Rahmen dieser Bachelorarbeit soll zunächst der Wandel des Film Noir von seiner Entstehung bis heute herausgestellt werden. Ziel dabei ist es, einen Vergleich einer klassischen und einer modernen Femme fatale anzufertigen. Schwerpunkt der Arbeit ist eine Analyse von zwei Filmen, die sich beide dem Noir zuordnen lassen und eine starke Frauenrolle beinhalten. Zwischen den Filmen Double Indemnity (1944) und Basic Instinct (1992) liegt eine große Zeitspanne, weshalb sie sich gut eignen, um die Veränderung der Femme fatale durch das Noir-Genre hinweg darstellen zu können

Préface

Entre le 25 janvier et le 11 février 2011, un soulèvement populaire a mis fin à trente ans de règne de Hosni Moubarak. La jeunesse, qui forme la grande majorité de la population égyptienne et dont toute la vie avait été soumise à la domination d’un président unique, est descendue dans la rue pour réclamer le départ du président et la fin de son système de gouvernance autoritaire. Humiliations et arbitraire quotidiens, violence des relations politiques, corruption généralisée, inflation non ma..