Calculations, and comparison with an ideal minimum, of trimmed drag for conventional and canard configurations having various levels of static stability

Classical drag equations were used to calculate total and induced drag and ratios of stabilizer lift to wing lift for a variety of conventional and canard configurations. The Flight efficiencies of such configurations that are trimmed in pitch and have various values of static margin are evaluated. Classical calculation methods are compared with more modern lifting surface theory

A bright millisecond radio burst of extragalactic origin

Pulsar surveys offer one of the few opportunities to monitor even a small fraction (~0.00001) of the radio sky for impulsive burst-like events with millisecond durations. In analysis of archival survey data, we have discovered a 30-Jy dispersed burst of duration <5 ms located three degrees from the Small Magellanic Cloud. The burst properties argue against a physical association with our Galaxy or the Small Magellanic Cloud. Current models for the free electron content in the Universe imply a distance to the burst of <1 Gpc No further bursts are seen in 90-hr of additional observations, implying that it was a singular event such as a supernova or coalescence of relativistic objects. Hundreds of similar events could occur every day and act as insightful cosmological probes.Comment: 18 pages, 4 figures. Accepted by Science. Published electronically via Science Express on September 27, 200

Clinical and laboratory studies of the bacterial pathogenesis and management of Pouchitis

20-50% of patients develop pouchitis following restorative proctocolectomy for ulcerative colitis (UC). Pre-pouch ileitis (PPI) also develops in some of these patients. Bacteria are implicated in the pathogenesis of pouchitis and antibiotics are the mainstay of treatment. Studies were performed to examine the role of bacteria in the pathogenesis of this disease and to develop new treatment. Further studies examined the prevalence and implications of PPI and the efficacy and complications associated with maintenance antibiotic therapy. 16s rRNA sequencing demonstrated an increase in Proteobacteria and a reduction in Bacteroidetes in the UC compared with the familial adenomatous polyposis (FAP) cohort, but only limited differences between the UC non-pouchitis and pouchitis groups. We were unable to identify an individual species or phylotype specifically associated with pouchitis. Treatment with elemental diet produced a symptomatic improvement in 71% of chronic pouchitis patients but none entered clinical remission. Patients with PPI were identified, the prevalence, symptoms and short term outcomes of this group were studied. PPI was identified in 5.7% of patients with UC. All patients had associated pouchitis but not all were symptomatic. PPI was not associated with reclassification to Crohn’s disease. A subgroup of patients with symptomatic pre-pouch ileitis were treated with combination antibiotic therapy and 86% entered remission. Faecal samples from patients with antibiotic resistant pouchitis were grown on agar and sensitivity patterns identified. Following guided antibiotic therapy 80% of patients entered remission. Stool analysis also identified the presence of extended spectrum beta-lactamase (ESBL) resistant coliforms in 35% of patients with chronic pouchitis. Not all were symptomatic. PPI was associated with an increased risk of ESBL. Patients treated with maintenance antibiotic therapy were identified. Pre-pouch ileitis was associated with an increased risk of relapse. Reported side effects were rare and treatment was associated with an improved quality of life

Analytical Model for the Optical Functions of Indium Gallium Nitride with Application to Thin Film Solar Photovoltaic Cells

This paper presents the preliminary results of optical characterization using spectroscopic ellipsometry of wurtzite indium gallium nitride (InxGa1-xN) thin films with medium indium content (0.38<x<0.68) that were deposited on silicon dioxide using plasma-enhanced evaporation. A Kramers-Kronig consistent parametric analytical model using Gaussian oscillators to describe the absorption spectra has been developed to extract the real and imaginary components of the dielectric function ({\epsilon}1, {\epsilon}2) of InxGa1-xN films. Scanning electron microscope (SEM) images are presented to examine film microstructure and verify film thicknesses determined from ellipsometry modelling. This fitting procedure, model, and parameters can be employed in the future to extract physical parameters from ellipsometric data from other InxGa1-xN films

Asymptotics of the partition function for random matrices via Riemann-Hilbert techniques, and applications to graphical enumeration

We study the partition function from random matrix theory using a well known connection to orthogonal polynomials, and a recently developed Riemann-Hilbert approach to the computation of detailed asymptotics for these orthogonal polynomials. We obtain the first proof of a complete large N expansion for the partition function, for a general class of probability measures on matrices, originally conjectured by Bessis, Itzykson, and Zuber. We prove that the coefficients in the asymptotic expansion are analytic functions of parameters in the original probability measure, and that they are generating functions for the enumeration of labelled maps according to genus and valence. Central to the analysis is a large N expansion for the mean density of eigenvalues, uniformly valid on the entire real axis.Comment: 44 pages, 4 figures. To appear, International Mathematics Research Notice

Turbulence measurements in a swirling confined jet flowfield using a triple hot-wire probe

An axisymmetric swirling confined jet flowfield, similar to that encountered in gas turbine combustors was investigated using a triple hot-wire probe. The raw data from the three sensors were digitized using ADC's and stored on a Tektronix 4051 computer. The data were further reduced on the computer to obtain time-series for the three instantaneous velocity components in the flowfield. The time-mean velocities and the turbulence quantities were deduced. Qualification experiments were performed and where possible results compared with independent measurements. The major qualification experiments involved measurements performed in a non-swirling flow compared with conventional X-wire measurements. In the swirling flowfield, advantages of the triple wire technique over the previously used multi-position single hot-wire method are noted. The measurements obtained provide a data base with which the predictions of turbulence models in a recirculating swirling flowfield can be evaluated