Typical Gibbs configurations for the 1d Random Field Ising Model with long range interaction

We study a one--dimensional Ising spin systems with ferromagnetic, long--range interaction decaying as n^{-2+\a}, \a \in [0,\frac 12], in the presence of external random fields. We assume that the random fields are given by a collection of symmetric, independent, identically distributed real random variables, gaussian or subgaussian with variance $\theta$. We show that for temperature and variance of the randomness small enough, with an overwhelming probability with respect to the random fields, the typical configurations, within volumes centered at the origin whose size grow faster than any power of $\th^{-1}$, % {\bf around the origin} are intervals of $+$ spins followed by intervals of $-$ spins whose typical length is \simeq \th^{-\frac{2}{(1-2\a)}} for 0\le \a<1/2 and $\simeq e^{\frac 1 {\th^{2}}}$ for \a=1/2

Results of an A109 simulation validation and handling qualities study

The results for the validation of a mathematical model of the Agusta A109 helicopter, and subsequent use of the model as the baseline for a handling qualities study of cockpit centerstick requirements, are described. The technical approach included flight test, non-realtime analysis, and realtime piloted simulation. Results of the validation illustrate a time- and frequency-domain approach to the model and simulator issues. The final A109 model correlates well with the actual aircraft with the Stability Augmentation System (SAS) engaged, but is unacceptable without the SAS because of instability and response coupling at low speeds. Results of the centerstick study support the current U.S. Army handling qualities requirements for centerstick characteristics

A variational scheme for hyperbolic obstacle problems

We consider an obstacle problem for (possibly non-local) wave equations, and we prove existence of weak solutions through a convex minimization approach based on a time discrete approximation scheme. We provide the corresponding numerical implementation and raise some open questions

Time-like lorentzian minimal submanifolds as singular limits of nonlinear wave equations

We consider the sharp interface limit $\epsilon \to 0$ of the semilinear wave equation $u_{tt} - \Delta u + \nabla W(u)/ \epsilon^2 = 0$ in $\mathbf R^{1+n}$, where $u$ takes values in $\mathbf R^k$, $k = 1,2$, and $W$ is a double-well potential if $k = 1$ and vanishes on the unit circle and is positive elsewhere if $k = 2$. For fixed $\epsilon > 0$ we find some special solutions, constructed around minimal surfaces in $\mathbf R^n$. In the general case, under some additional assumptions, we show that the solutions converge to a Radon measure supported on a time-like $k$-codimensional minimal submanifold of the Minkowski space-time. This result holds also after the appearence of singularities, and enforces the observation made by J. Neu that this semilinear equation can be regarded as an approximation of the Born-Infeld equation

A variable delay integrated receiver for differential phase-shift keying optical transmission systems

An integrated variable delay receiver for DPSK optical transmission systems is presented. The device is realized in silicon-on-insulator technology and can be used to detect DPSK signals at any bit-rates between 10 and 15 Gbit/s

Investigation of Hamamatsu H8500 phototubes as single photon detectors

We have investigated the response of a significant sample of Hamamatsu H8500 MultiAnode PhotoMultiplier Tubes (MAPMTs) as single photon detectors, in view of their use in a ring imaging Cherenkov counter for the CLAS12 spectrometer at the Thomas Jefferson National Accelerator Facility. For this, a laser working at 407.2nm wavelength was employed. The sample is divided equally into standard window type, with a spectral response in the visible light region, and UV-enhanced window type MAPMTs. The studies confirm the suitability of these MAPMTs for single photon detection in such a Cherenkov imaging application

The Mouth and Lupus

The oral cavity is often referred to as a “mirror of the body” and can be the first site with clinical signs of a sometimes distant systemic disease. The oral manifestations of various systemic conditions may precede or follow closely the involvement of other parts of the body and, in some instances, can be the dominant feature that warrants a particular emphasis upon investigation and/or treatment. Oral disease can sometimes be having the greatest negative impact upon a patient with systemic illness. The presence of oral ulcers (including nasopharyngeal ulcers) is one of the 11 criteria defined by the American College of Rheumatology for the diagnosis of systemic lupus erythematosus (SLE). A thorough examination of the oral tissues can provide useful information to clinicians for an early diagnosis of SLE. Oral lesions would normally improve if lupus is adequately controlled and their reoccurrence is often an indicator of a new disease flare-up. A wide spectrum of oral signs and symptoms caused by lupus has been described and might be related not only to the disease itself, but also to concomitant secondary conditions or be the effect of different medications