Fermion Representation Of The Rolling Tachyon Boundary Conformal Field Theory

A free fermion representation of the rolling tachyon boundary conformal field theory is constructed. The representation is used to obtain an explicit, compact, exact expression for the boundary state. We use the boundary state to compute the disc and cylinder amplitudes for the half-S-brane.Comment: 27 page

Propagation of Detonation Waves in Tubes Split from a PDE Thrust Tube

A Pulse Detonation Engine (PDE) combusts a fuel air mixture through detonation. Existing designs require spark plugs in each separate thrust tube to ignite premixed reactants. A single thrust tube could require the spark plug to fire hundreds of times per second for long durations. This paper reports on the use of a continuously propagating detonation wave as both a thrust producer and a single ignition source for a multi-tube system. The goal was to minimize ignition complexity and increase reliability by limiting the number of ignition sources. The work includes a systematic investigation of single tube geometric effects on detonations. These results were subsequently used to further examine conditions for splitting detonations i.e. the division of a detonation wave into two separate detonation waves. Finally a dual thrust tube system was built and tested that successfully employed a single spark to initiate detonation in separate thrust tubes

Rayleigh Imaging of Graphene and Graphene Layers

We investigate graphene and graphene layers on different substrates by monochromatic and white-light confocal Rayleigh scattering microscopy. The image contrast depends sensitively on the dielectric properties of the sample as well as the substrate geometry and can be described quantitatively using the complex refractive index of bulk graphite. For few layers (<6) the monochromatic contrast increases linearly with thickness: the samples behave as a superposition of single sheets which act as independent two dimensional electron gases. Thus, Rayleigh imaging is a general, simple and quick tool to identify graphene layers, that is readily combined with Raman scattering, which provides structural identification.Comment: 8 pages, 9 figure

Linear Predictability vs. Bull and Bear Market Models in Strategic Asset Allocation Decisions: Evidence from UK Data

Most papers in the portfolio choice literature have examined linear predictability frameworks based on the idea that simple but flexible Vector Autoregressive (VAR) models can be expanded to produce portfolio allocations that hedge against the bull and bear dynamics typical of financial markets through careful selection of predictor variables that capture business cycles and market sentiment. Yet, a distinct literature exists that shows that nonlinear econometric frameworks, such as Markov switching, are also natural tools to compute optimal portfolios arising from the existence of good and bad market states. This paper examines whether and how simple VARs can produce portfolio rules similar to those obtained under a simple Markov switching, by studying the effects of expanding both the order of the VAR and the number/selection of predictor variables included. In a typical stock-bond strategic asset allocation problem for U.K. data, we compute the out-of-sample certainty equivalent returns for a wide range of VARs and compare these measures of performance with those of nonlinear models. We conclude that most VARs cannot produce portfolio rules, hedging demands, or (net of transaction costs) out-of-sample performances that approximate those obtained from equally simple nonlinear frameworks

A novel method for detecting Lipoarabinomannan in urine with the promise of meeting the WHO target product profile for the diagnosis of tuberculosis

The diagnosis of tuberculosis largely relies on the detection of Mycobacterium tuberculosis (M. tuberculosis) via pathogen-specific DNA or bacterial culture from sputum samples. As the only point-of-care test so far, urinary lipoarabinomannan (LAM) has been endorsed by the World Health Organization for the diagnosis of tuberculosis in people living with HIV.In this study, the electrochemiluminescence LAM research assay (EclLAM) was used to measure LAM in the urine of HIV-sero-negative individuals with pulmonary tuberculosis and to monitor anti-tuberculosis treatment. Urine samples from 18 patients with microbiologically confirmed tuberculosis were analyzed before and after the initiation of anti-tuberculosis therapy and 17 healthy controls via the S4-20/A194-01 antibody pair.The assay identified 13/18 (72.2 %) patients with tuberculosis and was negative in 17/17 (100.0 %) controls (AUC 0.88). The results of the reactive urine LAM tests correlated with the detection of M. tuberculosis growth in culture (r = 0.94, p In conclusion, the LAM-specific antibody assay is promising to fulfill the WHO target product profile for the diagnosis of tuberculosis