Solitons in the Horava-Witten supergravity

We study classical BPS five-brane solutions in the Horava-Witten supergravity. The presence of the eleventh dimension add a new feature, namely the dependence of the solution on this new coordinate. For gauge five-branes with an instanton size less than the eleventh radius and in the neighborhood of the center of the neutral five-brane, important corrections to the ten-dimensional solution appear for all values of the string coupling constant. We compute the mass and magnetic charge of the five-brane solitons and the result is shown to agree with the membrane and five-brane quantization conditions. Compactified to four dimensions, our solutions are interpreted as axionic strings

Finite element analysis of gradient coil deformation and vibration in NMR microscopy

Resolution degradation due to gradient coil deformation and vibration in NMR microscopy is investigated using finite element analysis. From the analysis, deformations due to the Lorentz force can be as large as 1-10 μm depending on the gradient strength and coil frame material. Thus, these deformations can be one of the major resolution limiting factors in NMR microscopy. Coil vibration, which depends on the input current waveform and resolution degradation due to time-variant deformation and time-invariant deformation are investigated by numerical simulations

Preliminary assessment of industrial needs for an advanced ocean technology

A quick-look review of selected ocean industries is presented for the purpose of providing NASA OSTA with an assessment of technology needs and market potential. The size and growth potential, needs and problem areas, technology presently used and its suppliers, are given for industries involved in deep ocean mining, petrochemicals ocean energy conversion. Supporting services such as ocean bottom surveying; underwater transportation, data collection, and work systems; and inspection and diving services are included. Examples of key problem areas that are amenable to advanced technology solutions are included. Major companies are listed

Evaluation of Retinal Nerve Fiber Layer Thickness in Patients with Multiple Sclerosis

Background: Multiple sclerosis (MS) is a neurodegenerative disease, and is considered a chronic inflammatory disease. Retinal nerve fiber layer (RNFL) thickness as a structural biomarker for axonal loss in MS.Objective: The aim of the present study was to assess the role of optical coherence tomography (OCT) in detecting RNFL in MS patients without history of optic neuritis and to correlate with disease duration and disease disability. Patients and methods: Case-control study included 34 patients with clinically definite relapsing remitting multiple sclerosis (RRMS) and 34 age- and sex-matched individuals (other than MS) served as the controls. They were selected from the inpatients wards and Outpatients Clinic of Neurology Department, Zagazig University Hospitals. All patients were subjected to full history taking, clinical examination as well as laboratory and specific investigations. Results: The mean age was 34.56 ± 8.79 years in MS patients and 34.03 ± 8.79 years in controls. VEP 42.9% is with delay of p100 wave in bilateral eyes, and prolongal p100 laterary in bilateral eyes in 54.3%. There was a highly statistical significant difference between groups as regard RNFL average thickness and RNFL symmetry. Expanded disability status scale (EDSS) showed independently associated with RNFL.Conclusion: The thickness of the RNFL observed by OCT in MS patients is dramatically reduced when compared to controls, according to the current study. OCT is a valuable tool for determining the thickness of the RNFL in MS patients

How to obtain a covariant Breit type equation from relativistic Constraint Theory

It is shown that, by an appropriate modification of the structure of the interaction potential, the Breit equation can be incorporated into a set of two compatible manifestly covariant wave equations, derived from the general rules of Constraint Theory. The complementary equation to the covariant Breit type equation determines the evolution law in the relative time variable. The interaction potential can be systematically calculated in perturbation theory from Feynman diagrams. The normalization condition of the Breit wave function is determined. The wave equation is reduced, for general classes of potential, to a single Pauli-Schr\"odinger type equation. As an application of the covariant Breit type equation, we exhibit massless pseudoscalar bound state solutions, corresponding to a particular class of confining potentials.Comment: 20 pages, Late

Supersymmetric WZW σ\sigma Model on Full and Half Plane

We study classical integrability of the supersymmetric U(N) $\sigma$ model with the Wess-Zumino-Witten term on full and half plane. We demonstrate the existence of nonlocal conserved currents of the model and derive general recursion relations for the infinite number of the corresponding charges in a superfield framework. The explicit form of the first few supersymmetric charges are constructed. We show that the considered model is integrable on full plane as a concequence of the conservation of the supersymmetric charges. Also, we study the model on half plane with free boundary, and examine the conservation of the supersymmetric charges on half plane and find that they are conserved as a result of the equations of motion and the free boundary condition. As a result, the model on half plane with free boundary is integrable. Finally, we conclude the paper and some features and comments are presented.Comment: 12 pages. submitted to IJMP

Three routes to the exact asymptotics for the one-dimensional quantum walk

We demonstrate an alternative method for calculating the asymptotic behaviour of the discrete one-coin quantum walk on the infinite line, via the Jacobi polynomials that arise in the path integral representation. This is significantly easier to use than the Darboux method. It also provides a single integral representation for the wavefunction that works over the full range of positions, $n,$ including throughout the transitional range where the behaviour changes from oscillatory to exponential. Previous analyses of this system have run into difficulties in the transitional range, because the approximations on which they were based break down here. The fact that there are two different kinds of approach to this problem (Path Integral vs. Schr\"{o}dinger wave mechanics) is ultimately a manifestation of the equivalence between the path-integral formulation of quantum mechanics and the original formulation developed in the 1920s. We discuss how and why our approach is related to the two methods that have already been used to analyse these systems.Comment: 25 pages, AMS preprint format, 4 figures as encapsulated postscript. Replaced because there were sign errors in equations (80) & (85) and Lemma 2 of the journal version (v3

Characterization of B-doped polycrystalline diamond films using thermally stimulated luminescence

International audienceThe effect of different rates of boron incorporation during the growth in diamond on the thermoluminescence (TL) features of this material is investigated. TL studies performed between liquid nitrogen temperature (LNT) and 320 K show some phosphorescence and two other peaks at 226 and 266 K. For the first time, boron level in polycrystalline diamond films was identified by TL by an intense glow peak at 226 K and activation energy of about 0.35 eV. For this main peak, spectral analysis shows a prominent broad band luminescence peaking at 2.56 eV. At 77 K, another emission band was observed at 2.22 eV. This is in agreement with the fact that the recombination mechanisms involve two different recombination centers and, therefore, phosphorescence at 77 K and the main peak at 226 K are of different nature, i.e. the TL peak at 226 K is due to boron while phosphorescence is hence, probably due to a shallow donor level. The behavior of TL intensity relative to the main component at 226 K observed on all the films and linked to boron level decreases with increasing boron concentration