Transfer-matrix approach to multiband Josephson junctions

We study the influence of multiple bands on the properties of Josephson junctions. In particular we focus on the two gap superconductor magnesium diboride. We present a formalism to describe tunneling at a point contact between two MgB2 electrodes generalizing the transfer-matrix approach to multiple bands. A simple model is presented to determine the effective hopping amplitudes between the different energy bands as a function of the misorientation angle of the electrodes. We calculate the critical current and the current-voltage characteristics for N-I-S and S-I-S contacts with different orientation for junctions with both high and low transparency. We find that interband tunneling processes become increasingly important with increasing misorientation angle. This is reflected in certain features in the differential tunneling conductance in both the tunneling limit as well as for multiple Andreev reflections.Comment: 13 pages, 8 figure

Spectrum of low energy excitations in the vortex state: comparison of Doppler shift method to quasiclassical approach

We present a detailed comparison of numerical solutions of the quasiclassical Eilenberger equations with several approximation schemes for the density of states of s- and d-wave superconductors in the vortex state, which have been used recently. In particular, we critically examine the use of the Doppler shift method, which has been claimed to give good results for d-wave superconductors. Studying the single vortex case we show that there are important contributions coming from core states, which extend far from the vortex cores into the nodal directions and are not present in the Doppler shift method, but significantly affect the density of states at low energies. This leads to sizeable corrections to Volovik's law, which we expect to be sensitive to impurity scattering. For a vortex lattice we also show comparisons with the method due to Brandt, Pesch, and Tewordt and an approximate analytical method, generalizing a method due to Pesch. These are high field approximations strictly valid close to the upper critical field Bc2. At low energies the approximate analytical method turns out to give impressively good results over a broad field range and we recommend the use of this method for studies of the vortex state at not too low magnetic fields.Comment: 11 pages, 11 figures; revised version, error in Fig. 6b remove

Disorder-induced freezing of dynamical spin fluctuations in underdoped cuprates

We study the dynamical spin susceptibility of a correlated d-wave superconductor (dSC) in the presence of disorder, using an unrestricted Hartree-Fock approach. This model provides a concrete realization of the notion that disorder slows down spin fluctuations, which eventually "freeze out". The evolution of disorder-induced spectral weight transfer agrees qualitatively with experimental observations on underdoped cuprate superconductors. For sufficiently large disorder concentrations, static spin density wave (SDW) order is created when droplets of magnetism nucleated by impurities overlap. We also study the disordered stripe state coexisting with a dSC and compare its magnetic fluctuation spectrum to that of the disorder-generated SDW phase.Comment: 5 pages, 4 figure

F. Scott Fitzgerald in the city of lights: Success and Failure in Tender is the Night Through the Lens of Buffalo, New York

53 pages. A thesis presented to the Department of English and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Arts, Spring 2014.F. Scott Fitzgerald's spent the early part of his childhood growing up in Buffalo and the region of Western New York. from 1896-1908. New York plays an important role in the way he conceptualizes success and failure. This can he seen most notably played out in Tender is rhe Night, where Bulralo serves as a location of, and catalyst for. failure of morality and failure of the American Dream. Both of these tailures operate under an umbrella of ambition and social class that can be seen through the lens of Buffalo. New York. Through explorations ofthe social and cultural history of Buffalo, fitzgerald's experiences as described in his Ledger. and a close reading analysis of Tender is !he Nigh/. this thesis explores the way that Buffalo is employed to play into a wider thematic function of ideas of success and failure

Aetiology and risk factors of deep tissue injury explained : Enabling a more prosperous and sustainable society

The soft tissues covering bony prominences often encounter unique biomechanical challenges. Although not intended to tolerate high loads and deformation, they become part of the weight-bearing structure in surgical and bedfast patients, wheelchair users and lower-limb amputees. Consequently, deep soft tissue layers may be damaged, resulting in Deep Tissue Injury (DTI). However, the underlying aetiological and risk factors are subject to ongoing debates. Based on a scoping review, the state-of-the-art knowledge on DTI is presented