Pre-melting of crossing vortex lattices

The pre-melting of high vortex density planes observed recently in layered superconductors in tilted magnetic field is explained theoretically. Based on the structural information of the crossing lattices of pancake and Josephson vortices the effective vortex cage potential at different lattice sites is determined numerically. Melting takes place when the thermal energy allows proliferation of vacancy-interstitial pairs. It is found that the increased density of pancake vortex stacks in the planes containing Josephson vortices, rather than their incommensurate structure, is the main cause for pre-melting.Comment: 5 pages, 4 figure

Districting Problems - New Geometrically Motivated Approaches

This thesis focuses on districting problems were the basic areas are represented by points or lines. In the context of points, it presents approaches that utilize the problem\u27s underlying geometrical information. For lines it introduces an algorithm combining features of geometric approaches, tabu search, and adaptive randomized neighborhood search that includes the routing distances explicitly. Moreover, this thesis summarizes, compares and enhances existing compactness measures

Copper Phenoxyl Complexes

The work described in the following was inspired by radical copper enzymes such as Galactose Oxidase (GO). GO catalyses the two-electron oxidation of terminal alcohols to the corresponding aldehydes using air oxygen. Transfer of two electrons is possible, since GO contains two magnetically coupled one-electron redox centres: a tyrosylate ligand from the apo-protein, which exists either in the tyrosylate or the tyrosyl radical form and is bound to a copper ion possessing two stable oxidation states (+I and +II). The catalytic activity of GO can be assigned to the Cu-OTyr (Tyr = Tyrosine, or more general Cu-Oaryl) motive, which is also found in all complexes synthesised and characterised in this thesis. The ligands specifically designed for this study, contain substituted, non-substituted or aromatically enlarged phenoxy moieties and belong to various compound classes: O,N,O pincer ligands, O,O',N donor ligands, salen type ligands, phenol-substituted triazole ligands, phenalenone ligands, benzoquinone ligands und acridine ligands. All of them were used to synthesise Cu(II) complexes, selected ligands (e.g. O,O',N, donor ligands) were additionally coordinated to Ni(II), Zn(II), Fe(II), Fe(III) and Co(II). All compounds were fully characterised using NMR or EPR spectroscopy, UV/vis/NIR-absorption spectroscopy, emission spectroscopy, cyclic voltammetry, spectroelectrochemistry, elemental analysis and XRD. These studies focus on (a) the electrochemical properties of the two one-electron redox couples Cu(II)/Cu(I) und [PhO•+]/[PhO], (b) the influence of ligand- and complex structure on both redox pairs and (c) the catalytic activity of the complexes resulting from their electrochemical properties. The latter was investigated by test reactions using benzyl alcohol as substrate and an in situ generated catalyst. Furthermore, detailed investigations on reactions yielding the active radical species Cu(II)-[OPh•+] under catalysis conditions were performed using a phenol-substituted triazole ligand system. Two methods were compared, one starting from a Cu(I) precursor, which is oxidised by air oxygen to yield the copper radical complex and the second starting from Cu(II) complexes which undergo a disproportionation reaction forming the active radical species and a Cu(I) byproduct

Mechatronische Osteosyntheseplatte

Ziel dieses Projektes ist die Entwicklung eines miniaturisierten vollimplantierbaren Gerätes zur Verlängerung von Kiefer- und Schädelknochen, basierend auf den Erkenntnissen von Plattenosteosynthese-Verfahren. Dieses Gerät, im folgenden Mechatronische Osteosyntheseplatte (kurz MO) oder Distraktor genannt, ist ein kleiner Teleskopaktuator, der eine Kraft von mindestens 30 N erzeugt, die zur Verlängerung eines Knochens benötigt wird. Der Antrieb erfolgt durch Formgedächtnisdrähte aus einer Nickel-Titan-Legierung, die im Inneren des Gerätes gespannt sind. Diese Drähte werden über eine drahtlose niederfrequente Energieeinkopplung mit Strom versorgt. Über einen Ratschenmechanismus wird die Kraft auf eine teleskopartig ausfahrende Platte übertragen. Der Distraktor wird direkt auf den Knochen mit kommerziell erhältlichen Titan-Knochenschrauben aufgeschraubt. Die Neuerung bei dieser Entwicklung ist u.a. der Antrieb durch Drähte aus Formgedächtnislegierung, sowie die vollständige Implantierbarkeit des Gerätes. Formgedächtnislegierungen können in kaltem Zustand mit geringem Kraftaufwand verformt werden. Werden sie anschließend erhitzt, so „erinnert“ sich die Legierung an ihre ursprüngliche Form und nimmt den vorherigen unverformten Zustand wieder ein. Ziel dieser Neuentwicklung ist, durch das vollständige Verschließen des operierten Bereichs die Infektionsgefahr zu minimieren, das Risiko für den Patienten zu senken und den Behandlungskonfort zu erhöhen. Durch die minimierte Narbenbildung wird das kosmetische Ergebnis ebenfalls verbessert. Desweiteren soll die Erfassung von Messwerten für Weg und Kraft integriert werden, um so dem betreuenden Arzt Auskunft über den Fortschritt des Verlängerungsprozess und die Heilung zu geben. Eingesetzt wird die Osteosynthese durch Knochenverlängerung in der plastischen Chirurgie bei Missbildungen, Fehlstellungen oder Unfällen

A local model of writing program assessment : fourteen community college faculty define and evaluate writing proficiency.

The introduction to this doctoral dissertation is an argument for locating Writing Across the Curriculum programs on the community-college campus for several reasons, among them the proximity of the disciplines on the community college campus, the increasingly underprepared community college student, and movements toward accountability and assessment at the local and state levels. As an example of what a WAC program may accomplish in the area of program assessment, which developed from WAC proper in the last decade of the last century, Chapters One, Two and Three present data I collected from fourteen faculty volunteers who gave up a beautiful Saturday in May of 1995 to read and evaluate a set of randomly selected student essays. Chapter One summarizes faculty responses to a ten-minute freewriting exercise, in which I asked respondents to describe or define proficient writing from the perspectives of their disciplines. In their responses, I locate four global characteristics used by a simple majority of respondents and 21 other characteristics used by at least one respondent. I argue that these characteristics, especially the global ones, constitute our College\u27s local definition of proficiency. I close the chapter pointing out that future WAC workshops could include discussions of global and other characteristics locating them in student work, and discussing how to teach them, both in writing classes and elsewhere. Although the data in Chapter One are incomplete, they provide a starting place for a teacher-researcher who is interested in how colleagues across the campus describe writing. They also prompt questions about whether the respondents know what they are saying when they use terms like style, purpose, grammar, and audience. Do they really look for the characteristics they claimed to look for in their freewritings? Are there other characteristics to be added to the list? Chapters Two and Three report and interpret additional data from the workshop. Each faculty member read and evaluated end of semester ENG 102 papers, rating them NP (nonproficient), P (proficient), or HP (highly proficient). These chapters are based on an unpublished study Dr. Tom Blues created at the University of Kentucky in May of 1993. Blues was ahead of his time by several years. In 1996, the Southern Association of Colleges and Schools (SACS) mandated an exit-exam for all students in ENG 102 and ENG 105 at Jefferson Community College. I show that a qualitative program assessment could complement or eventually replace the quantitative outside evaluation we are now using and conclude that in 1995 faculty in areas other than English often confused terms associated with writing, but generally returned to their freewriting definitions and descriptions throughout their evaluations. Chapter Four summarizes my conclusions and recommendations, discusses the benefits of local, constructivist assessments in a culture that increasingly truncates and supplants genuine, holistic writing and undermines progress (Shafer 242). The chapter ends with practical recommendations mostly for my colleagues in the Writing Program at Jefferson Community College. Where do we go from here? That sort of thing

Dynamics of optomechanical spatial solitons in dual-nanoweb structures

We theoretically investigate the stability and dynamics of self-channelled beams that form via nonlocal optomechanical interactions in dual-nanoweb microstructured fibers. These "optomechanicons" represent a novel class of spatial soliton