Measurement of differential cross sections of single top-quark production in the tt channel in proton-proton collisions at s=8\sqrt{s} = 8 TeV

Differential measurements of single top quark $t$-channel cross sections as a function of the transverse momentum and the absolute value of the rapidity of the top quark are presented. The data collected by the CMS experiment at the LHC at a center-of-mass energy of 8 TeV corresponds to an integrated luminosity of 19.7 fb$^{-1}$. Leptonic decay channels of the top quark, with either a muon or an electron in the final state, are considered. Neural networks are used to separate signal from background contributions. After correcting for selection efficiencies and detector resolution with an unfolding technique, the resulting distributions are found to agree with predictions from different Monte Carlo generators within the estimated uncertainties.Comment: Proceedings of TOP2014, 7th International Workshop on Top Quark Physics, Cannes, France, September 29 - October 3 2014, 4 pages, 6 figure

Effect of strong wakes on waves in two-dimensional plasma crystals

We study effects of the particle-wake interactions on the dispersion and polarization of dust lattice wave modes in two-dimensional plasma crystals. Most notably, the wake-induced coupling between the modes causes the branches to "attract" each other, and their polarizations become elliptical. Upon the mode hybridization the major axes of the ellipses (remaining mutually orthogonal) rotate by $45^\circ$. To demonstrate importance of the obtained results for experiments, we plot spectral densities of the longitudinal and transverse waves revealing distinct fingerprints of the mixed polarization. Furthermore, we show that at strong coupling the hybrid mode is significantly shifted towards smaller wave numbers, away from the border of the first Brillouin zone (where the hybrid mode is localized for a weak coupling).Comment: 10 pages, 6 figure

Mode-coupling regimes in 2D plasma crystals

Diese Arbeit ist eine kumulative Dissertation und besteht aus drei Aufsätzen. Sie setzt die Studien der Diplomarbeit zur eigenständig kohärenten Beschreibung der wakevermittelten Modenkopplung in Plasmakristallen fort. Der erste Aufsatz untersucht die Ionengeschwindigkeitsverteilung (idf) in einem schwach-ionisierten Gas, welches einem homogenen elektrischen Feld ausgesetzt ist und in dem Ladungsaustauschkollisionen der dominante Stoßtyp sind. Die Untersuchung geht dabei nur von elementaren Grundprinzipien aus und ist somit eigenständig kohärent. Die "Referenzverteilung" wird mittels einer Monte-Carlo-Simulation (MC-Simulation) am Beispiel des energieabhängigen Wirkungsquerschnitts für Argon berechnet. Ich nutze mehrere analytische Modelle (basierend auf einem konstanten Wirkungsquerschnitt oder konstanter Stoßfrequenz) und vergleiche die entsprechenden idfs untereinander, sowie mit der Referenzlösung. Es zeigt sich, dass kein Modell für den experimentell häufig wichtigen Fall eines schwach suprathermalen Ionenstroms mit befriedigender Genauigkeit anwendbar ist. Einen konstanten Wirkungsquerschnitt und Separabilität der idf annehmend, sowie darauf folgende Maxwell-gewichtete Mittelung, reduziert die integro-differentielle Boltzmanngleichung zu einer gewöhnlichen Differentialgleichung. Ich zeige, dass ihre Lösung die Resultate der MC-Simulation, für beliebige Stärke des Ionenstroms, mit großer Genauigkeit reproduziert. Das gewonnene Modell lässt sich auf eine Vielzahl von Problemen im Bereich der komplexen Plasmen anwenden - darunter der Ladungsvorgang der Staubteilchen, die Bildung von Wakefeldern und nicht-Hamiltonische Dynamik. Im zweiten Aufsatz behandle ich das vorrangige Beispiel eines nicht-Hamiltonischen Prozesses in zweidimensionalen (2D) Plasmakristallen: Die Modenkopplungsinstabilität (MCI), induziert durch die wakevermittelte Wechselwirkung der Staubteilchen. Durch das Einbinden des Formalismus einer linearen Plasmarückantwort (zur eigenständig kohärenten Beschreibung der Teilchenwechselwirkung) wird die bisherige Theorie erweitert. Ich verwende dazu die Ergebnisse des ersten Aufsatzes für subthermale und suprathermale Ionenströme. Ein Abbildungsverfahren setzt die eigenständig kohärenten Kopplungskoeffizienten und das effektive Dipolmoment der Wakes miteinander in Beziehung. Das Dipolmoment ist ein fundamentaler Parameter, welcher die Modenkopplung im üblicherweise verwendeten "Yukawa-Punktwake-Modell" charakterisiert. Ich wende das Abbildungsverfahren auf verfügbare experimentelle Daten an. Die resultierende Größenordnung des Dipolmoment zeigt in mehreren Fällen das Vorliegen starker Modenkopplung an. Diese wurde zuvor nie systematisch untersucht. Dieses Ergebnis motiviert die Untersuchungen der dritten Veröffentlichung: Ich studiere den Einfluss starker Staubteilchen-Wake-Wechselwirkungen auf Dispersion und Polarisation von Staubgittermoden in 2D-Plasmakristallen. Die starke Kopplung bewirkt eine "Anziehung" zwischen den Moden und macht ihre Polarisationen elliptisch. Bei Hybri- disierung rotieren die Hauptachsen der Lissajous-Ellipsen um 45° (bleiben aber weiterhin senkrecht zueinander). Um die Implikationen für Experimente aufzuzeigen, berechne ich die entsprechenden Teilchenbahnen und spektrale Dichten der longitudinalen und transversalen Moden. Beide Observablen offenbaren deutliche Spuren elliptischer Polarisation. Abschließend untersuche ich die Verschiebung der Hybridisierung bei starker Kopplung. Der Effekt ist signifikant: Das Einsetzen der Hybridisierung erfolgt bei Wellenzahlen welche merklich kleiner sind als die Grenze der Brillouin-Zone (wo die Hybridmode bei schwacher Kopplung zuerst auftritt).The present work is a cumulative thesis consisting of three refereed publications. It continues the diploma studies dealing with the self-consistent investigation of wake-mediated mode-coupling in plasma crystals. In the first paper, I investigate the ion-velocity distribution function (idf) of a weakly- ionized gas, subjected to a uniform electric field and ion-neutral charge-exchange collisions. The "reference" idf, based on the energy-dependent cross-section for argon, is calculated by Monte-Carlo (MC) simulations. I consider several analytical models (based on either constant cross-section or constant collision-frequency) and compare them with each other and to MC results. It is demonstrated that none of available models applies to the experimentally often relevant situation of slightly suprathermal ion-flow. Assuming constant cross-section and separability of idf, followed by subsequent application of Maxwellian- averaging, the integro-differential Boltzmann equation is reduced to a simple differential equation. Evidently, its solution reproduces the reference idf with good accuracy for arbitrary value of field strength. These studies are of fundamental importance for a variety of problems in complex plasmas - among them the charging of dust grains, the formation of wake fields and non-Hamiltonian dynamics. The second paper deals with the primary example of non-Hamiltonian dynamics in two-dimensional (2D) plasma crystals: The mode-coupling instability (MCI), induced by the wake-mediated interactions between grains. The corresponding theory is extended by using the linear-response formalism for the self-consistent description of particle interactions. In this approach, I employ the results from the first paper for subthermal and suprathermal regimes of ion flow. A mapping procedure relates the self-consistent coupling coefficients to the effective wake dipole moment - the parameter essentially characterizing the mode coupling in the framework of conventionally used Yukawa/point-wake model. I apply the mapping to several available experiments and compare theoretically obtained dipole moments with experimental data. In several cases, the resulting magnitude of dipole moment indicates strong mode-coupling, which was never systematically studied. In the third publication, I investigate the effects of strong grain-wake interactions on dispersion and polarization of dust-lattice wave modes in 2D plasma crystals. Strong coupling causes an "attraction effect" between the modes, making their polarizations elliptical. Upon hybridization, the Lissajous ellipses major axes rotate by 45° (but remain mutually orthogonal). I show the implications for experiments by calculating representative particle trajectories and spectral densities of longitudinal and transverse waves. Both these observables reveal the distinct fingerprints of elliptical polarization. Furthermore, I investigate the shift of the hybrid mode at strong coupling. The effect is found to be significant: The hybridization onset is at wave numbers which are notably smaller than the border of the first Brillouin zone (where the onset takes place in the regime of weak coupling)

Give us the power! : how a firm’s empowerment philosophy affects consumers’ purchase intention, future loyalty intention, word-of-mouth intention and hedonic experience

Companies increasingly involve their consumers into the development of new ideas and products. While some companies actively communicate their user-driven firm philosophy others do not. This study identifies how a firm’s empowerment philosophy can change consumer-firm relationships and thereby affect consumers’ judgments and behavioral intentions in order to draw conclusions regarding a firm’s marketing strategy. A betweensubjects experimental study exposed respondents either to an employee-driven firm (1), a userdriven firm where the respondents were empowered themselves (2), a user-driven firm (3) or a user-driven firm with in-group participants (4). Findings indicate that a user-driven firm philosophy positively affects consumers’ purchase intention, word-of-mouth intention, future loyalty intention and hedonic experience for low complexity hedonic products. The effects occur for both empowered and non-participating observing consumers. Overall, firm philosophy affects all these variables through firm identification but also through feelings of psychological ownership. Moreover, similarity mediates the effects of firm philosophy on both firm identification and psychological ownership. Hence, perceived similarity to the product creators is the key to create firm identification and feelings of psychological ownership.Cada vez mais, empresas recorrem aos seus clientes para criar novas ideias e produtos. Enquanto que algumas empresas comunicam ativamente as suas filosofias empresariais orientadas para o consumidor, outras não o fazem. Este estudo identifica a maneira como a filosofia empresarial baseada num maior poder de decisão do consumidor pode alterar as relações consumidor-empresa e desta forma influenciar as perceções e intenções comportamentais dos consumidores de modo a tomarem posições acerca da estratégia de marketing de uma empresa. O estudo experimental expôs os participantes a um dos seguintes tipos de empresa: (1).empresa cujo produto final é proposto exclusivamente pelos seus colaboradores; (2).empresa cujo produto é proposto somente pelos participantes; (3).empresa que tem em consideração não só os participantes, mas também outros consumidores; (4) empresa que apenas considera grupos de referência (in-group). Os resultados obtidos demonstram que uma filosofia orientada para o consumidor afeta a intenção de compra dos consumidores, o passa-a-palavra, a intenção de lealdade futura e a experiência de consumo de produtos hedónicos com pouca complexidade. Os efeitos ocorrem não só nos participantes com poder de decisão, mas também em consumidores não-participantes. Geralmente a filosofia da empresa influencia as referidas variáveis não só através da identificação com a empresa, mas também através de sentimentos de posse psicológica. Adicionalmente, esta influência tem como intermediário o sentimento de similaridade. Dito isto, a perceção de similaridade com os responsáveis pelo desenvolvimento dos produtos é essencial para a criação de identificação com a empresa e para o surgimento de sentimentos de posse psicológica

Middleware for Work Support in Industrial Contexts (MiWSICx)

It is generally acknowledged that technological innovation is leading to an increase in the complexity of industrial work. Hence, work assistance has emerged as an important theme in the context of cyber-physical production systems and Industry 4.0 to assist workers in assembly, logistics, maintenance and supervision. Recent research in this domain has focused on demonstrating assistance applications using mobile computing devices such as tablets, smartphones, AR/VR glasses and wearables, but the aspects of technology induced complexity in industrial work distribution, concurrency, information complexity, and variability of information interaction, and their subsequent effect on human workers is yet to be tackled. This paper has two core contributions: first, it reframes the problem of complex industrial work through activity theory, which leads to a conceptual model that couples human information needs to interactive artefacts within an activity context. Second, the problem of assistance is viewed as managing information flow between multiple devices grouped into fluid and adaptive activity contexts, managed by MiWSICx, (Middleware for Work Support in Industrial Contexts) a novel, distributed middleware designed using the actor model of concurrent computation

Хімічна інженерна освіта: історія розвитку

У статті висвітлюється питання підготовки інженерів-хіміків для народного господарства в системі вищої освіти України.The article is devoted to the problem training of chemical engineer for national economy in system of the higher education of the Ukraine

Nonlinear regime of the mode-coupling instability in 2D plasma crystals

The transition between linear and nonlinear regimes of the mode-coupling instability (MCI) operating in a monolayer plasma crystal is studied. The mode coupling is triggered at the centre of the crystal and a melting front is formed, which travels through the crystal. At the nonlinear stage, the mode coupling results in synchronisation of the particle motion and the kinetic temperature of the particles grows exponentially. After melting of the crystalline structure, the mean kinetic energy of the particles continued to grow further, preventing recrystallisation of the melted phase. The effect could not be reproduced in simulations employing a simple point-like wake model. This shows that at the nonlinear stage of the MCI a heating mechanism is working which was not considered so far.Comment: 6 pages, 4 figure

Applying Human-Centered Design Methods in Industry – a Field Report

Human-centered design methods are nowadays widely used in the design of consumer products. These methods aim at designing products with a high usability and a positive user experience (UX). However, in the domain of the design of industrial machines, design is often driven by functional requirements mostly neglecting the usability and user experience of products. Together with a medium-sized manufacturer of industrial laundry machines we applied the human-centered design process in an industrial context. In this field report, we describe the human-centered design methods applied in the project, the adaptations we had to make in the process and the challenges and opportunities for applying human-centered design in an industrial environment in general

Human-centered User Interfaces for Automated Driving – (Un-)exploited Potentials

Designing user interfaces for (highly) automated driving is a complex task since users vary considerably regarding their needs and preferences. Therefore, a one-size-fits-all approach will not be sufficient for designing these interfaces. Thus, in this paper we aim to identify unexploited potentials in this area. We do so by performing a systematic literature review. Our contributions are 1) a systematization of human-centered user interface design for automated driving in four key aspects, 2) the research intensity per aspect, 3) the unexploited potential within each aspect and 4) the potentials of the relations between them. Concretely, current research lacks frameworks supporting the customization of the named interfaces based on user characteristics. Among others, personalization of displayed information shows unexploited potentials for acceptance and usability. Thus, we recommend future research to focus on human-centricity accounting for individual needs instead of the interface itself