Memory effects for a stochastic fractional oscillator in a magnetic field.

The problem of random motion of harmonically trapped charged particles in a constant external magnetic field is studied. A generalized three-dimensional Langevin equation with a power-law memory kernel is used to model the interaction of Brownian particles with the complex structure of viscoelastic media (e.g.

Stochastic multiresonance and correlation-time-controlled stability for a harmonic oscillator with fluctuating frequency.

The long-time behavior of the first two moments and the correlation function for the output signal of a harmonic oscillator with fluctuating frequency subjected to an external periodic force and an additive thermal noise is considered analytically. The colored fluctuations of the oscillator frequency are modeled as a three-level Markovian noise. Using the Shapiro-Loginov formula, the exact expressions of several stochastic resonance (SR) characteristics such as the spectral amplification, the variance of the output signal, the signal-to-noise ratio, and the SR gain have been calculated.

Colored-noise-induced Hopf bifurcations in predator-prey communities.

A broad class of (N+1) -species ratio-dependent predator-prey stochastic models, which consist of one predator population and N prey populations, is considered. The effect of a fluctuating environment on the carrying capacities of prey populations is taken into account as colored noise. In the framework of the mean-field theory, approximate self-consistency equations for prey-populations mean density and for predator-population density are derived (to the first order in the noise variance).

Intravascular ultrasound imaging: an essential component of angioplasty assessment and vascular stent deployment.

Potential early complications of balloon angioplasty include occlusion due to vessel wall recoil, medial dissection, creation of intimal flaps, spasm and luminal thrombosis. These features have also been implicated in the development of restenosis and late occlusion. As a possible solution to these problems, an endovascular scaffold (stent) was proposed by Dotter in the 1960s, and initial studies suggested that use of such a device in specific circumstances may reduce complications related to major dissection, vessel recoil and spams.

Three-dimensional transrectal ultrasound: preliminary patient evaluation.

Transrectal ultrasound is uniquely useful in diagnosing and localizing the extent of lower colon and rectal disease. This paper reports the preliminary evaluation of three-dimensional intraluminal ultrasound imaging of normal and diseased rectal segments. The three-dimensional reconstructions were produced using a computerized PC based image analysis system which aligns ultrasound images to produce the three-dimensional images.