Experimental stress-strain analysis of tapered silica optical fibers with nanofiber waist

We experimentally determine tensile force-elongation diagrams of tapered optical fibers with a nanofiber waist. The tapered optical fibers are produced from standard silica optical fibers using a heat and pull process. Both, the force-elongation data and scanning electron microscope images of the rupture points indicate a brittle material. Despite the small waist radii of only a few hundred nanometers, our experimental data can be fully explained by a nonlinear stress-strain model that relies on material properties of macroscopic silica optical fibers. This is an important asset when it comes to designing miniaturized optical elements as one can rely on the well-founded material characteristics of standard optical fibers. Based on this understanding, we demonstrate a simple and non-destructive technique that allows us to determine the waist radius of the tapered optical fiber. We find excellent agreement with independent scanning electron microscope measurements of the waist radius

Linewidths in bound state resonances for helium scattering from Si(111)-(1x1)H

Helium-3 spin-echo measurements of resonant scattering from the Si(111)–(1 × 1)H surface, in the energy range 4–14 meV, are presented. The measurements have high energy resolution yet they reveal bound state resonance features with uniformly broad linewidths. We show that exact quantum mechanical calculations of the elastic scattering, using the existing potential for the helium/Si(111)–(1 × 1)H interaction, cannot reproduce the linewidths seen in the experiment. Further calculations rule out inelastic and other mechanisms that might give rise to losses from the elastic scattering channels. We show that corrugation in the attractive part of the atom–surface potential is the most likely origin of the experimental lineshapes

Graphene Physics in Graphite

Single layers of carbon dubbed "graphenes", from which graphite is built, have attracted broad interest in the scientific community because of recent exciting experimental results. Graphene is interesting from a fundamental research perspective, as well as for potential technological applications. Here, we provide a brief overview of recent developments in this field, focusing especially on the electronic properties of graphite. Experimental evidence indicates that high-quality graphite is a multi-layer system with nearly decoupled 2D graphene planes. Based on experimental observations, we anticipate that thin graphite samples and not single layers will be the most promising candidates for graphene-based electronics.Comment: 9 pages including 2 figures, correction of typo

A new class of semiclassical wave function uniformizations

We present a new semiclassical technique which relies on replacing complicated classical manifold structure with simpler manifolds, which are then evaluated by the usual semiclassical rules. Under circumstances where the original manifold structure gives poor or useless results semiclassically the replacement manifolds can yield remarkable accuracy. We give several working examples to illustrate the theory presented here.Comment: 12 pages (incl. 12 figures

Indexing Romance Language Use? Zur Anwendbarkeit eines aktuellen Theoriemodells aus den USA auf die soziolinguistische Analyse der romanischen Sprachen und insbesondere des Katalanischen

Summary: Social indexicality and enregisterment are basic notions of a theoretical model elaborated in the USA, whose aim is to describe the relationship between the use of language variation and patterns of social behavior on a level of formal classifications. This analytical approach is characterized by focusing on the interrelation of social performance and language awareness. In our contribution we want to show how this modern methodology can give new impetus to the study of today’s problem areas in Europe like ‘migration and language’ or ‘urban life and language use’. In particular, we are interested in the case of Catalan which has been treated for some time by proponents of the North-American enregisterment theory. This leads us to indicate that explicit ways of social conduct like language shift or the emblematic use of linguistic forms can be interpreted with regard to the social indexicality of Catalan. We thus analyze them in a way which shows that authenticity and integration in Catalan society can be achieved to a considerable extent by practicing forms of linguistic enregisterment. [Keywords: Social indexicality; enregisterment; sociolinguistics; language variation; urban dialect; multilingualism; migration; Catalan

Regionaler Sprachgebrauch in Fachkontexten: Lexikologische und textuelle Untersuchungen zu Gestaltung und Dynamik fachsprachlicher Kompetenz in zweisprachigen Regionen der europäischen Romania

Die Arbeit ist ein Beitrag zu der Erforschung gesprochener Sprache in Bezug auf bestimmte Textformen und kommunikative Inhalte unter gleichzeitiger Berücksichtigung ausgewählter Sprachkontaktsituationen. Es fällt auf, dass die gesprochene Sprache bislang zwar eingehend unter den Gesichtspunkten ihrer formalen Strukturiertheit (Lexikon, Morphologie, Syn- tax) untersucht worden ist, der Sprachinhalt und die textuelle Gestaltungsebene aber stark vernachlässigt wurden. Insbesondere liegen noch keine größeren Untersuchungen zu den normativen Bedingungen und der kommunikativen Funktion gesprochener Sprache in enger definierten Bereichen (thematischen Sektoren) des alltäglichen gesellschaftlichen Lebens vor. Entsprechende sys- tematisch ermittelte Textcorpora stehen ebenfalls nicht zur Verfügung.Im Mittelpunkt des allgemeiner definierten Untersuchungsinteresses steht die Analyse der Sprachkompetenz in ihrer Bezugnahme auf verschiedene Wis- sensdimensionen und gesellschaftliche Normen

Indexicality and Enregisterment as Theoretical Approaches to the Sociolinguistic Analysis of Romance Languages

Social indexicality and enregisterment are basic notions of a theoretical model elaborated in the United States, the aim of which is to describe the relationship between the use of language variation and patterns of social behavior at the level of formal classification. This analytical approach is characterized by focusing on the interrelation of social performance and language awareness. In my contribution, I want to show how this modern methodology can give new impetus to the study of today’s problem areas in Europe, such as migration and language or urban life and language use. In particular, I am interested in the case of Catalan, which has been studied for some time by proponents of the North American enregisterment theory. This leads me to indicate that explicit forms of social conduct, such as language shift or the emblematic use of linguistic forms, can be interpreted with regard to the social indexicality of Catalan. I thus analyze them in a way which shows that authenticity and integration in Catalan society can be achieved to a considerable extent by practicing forms of linguistic enregisterment