Previous work on thermally induced arsenic deactivation in highly doped silicon has proven the generation bf vacancies and suggests the formation of arsenic-vacancy clusters as the deactivation mechanism. Using positron annihilation spectroscopy in the two-detector coincidence geometry, we are able ...

Motivated by a recent report by Dickey et al. [Phys. Med. Biol. 46, 2359 (2001)], who demonstrated optical property retrieval by using relative radiance measurements at a single position, we investigate the uniqueness of relative radiance measurements for quantifying the optical properties of turbid...

Background and Objectives: Fluoroptic sensors are used to measure interstitial temperatures but their utility for monitoring laser interstitial thermal therapy (LITT) is unclear because these sensors exhibit a measurement artefact when exposed to the near-infrared (NIR) treatment light. This study i...

Monte Carlo computer simulations were used to investigate the effects of shape anisotropy and electrostatic interactions as mechanisms for orientational ordering of solutes in nematic liquid crystals. The simulation results were analyzed in terms of two theories of solute ordering which derive mean-...

We present data from a two-region (coagulated and native tissue) Monte Carlo simulation in spherical geometry to assess the feasibility of using optical fluence and radiance information for determining the boundary of tissue coagulation during thermal therapy. Our results demonstrate that radiance o...

We employ off-lattice Monte Carlo simulations to study lateral diffusion in lipid-sterol bilayers using a two-dimensional model system which has been designed to simulate the experimental phase diagrams of both lipid-cholesterol and lipid-lanosterol systems. We focus on the effects of varying sterol...

We study the first order solid-fluid phase transition of a system of semi-flexible Lennard-Jones chains using molecular dynamics simulations. Thermodynamic integration methods are used to calculate the free energy of the solid and fluid phases. The solid phase free energy per chain can be calculated...

A density-functional theory for the isotropic-nematic phase transition in fluids of rigid or semiflexible fused hard-sphere chains, developed previously by the authors, is extended to diblock chains each consisting of both a rigid and a flexible part. The theory is compared with recent Monte Carlo s...

We use molecular dynamics simulations to study an entropy-driven collapse transition of a flexible polymer in a solvent. Monomers and solvent particles interact with a steeply repulsive soft-sphere potential. We consider a nonadditive potential system in which the effective diameter describing the s...

In this paper we report on the electrical characterization of conductive polyaniline and its derivatives. Conductivity measurements were also performed on the intercalated phases formed by the encapsulation of the polymers into layered molybdenum disulfide. These measurements were performed using th...

Positron annihilation spectra of arsenic- and gold-implanted silicon are compared:with spectra from bulk samples of arsenic and gold. Spectra with strongly reduced background intensities were recorded using a two detector coincidence system with a variable-energy positron beam. It is shown that feat...

Coarse-grained models that preserve hydrodynamics provide a natural approach to study collective properties of soft-matter systems. Here, we demonstrate that commonly used integration schemes in dissipative particle dynamics give rise to pronounced artifacts in physical quantities such as the compre...

A novel scanning tunneling microscope (STM) is described which is constructed almost entirely of one metal e.g. aluminum and uses bimorph piezoelectric disks as the x, y, z drive elements. The design uses a simple, rugged tripod configuration for the fine motion drive arms. Coarse motion of the samp...

Interstitial laser photocoagulation (ILP) was performed in vitro in lean bovine and chicken muscle by delivering 1.6 W of continuous-wave Nd:YAG laser energy (1064 nm) from a 400-mum core optical fiber for 300s. The resulting thermal coagulation lesion was consistently larger when the delivered ener...

A novel scanning tunneling microscope (STM) is described which is constructed almost entirely of one metal e.g. aluminum and uses bimorph piezoelectric disks as the x, y, z drive elements. The design uses a simple, rugged tirpod configuration for the fine motion drive arms. Coarse motion of the samp...

We report Monte Carlo simulations of the nematic-smectic phase transition for a system of hard spherocylinders with infinite length-to-diameter ratio. A finite-size scaling analysis suggests that this system undergoes a first-order phase transition. When combined with other simulations of the phase ...

Monte Carlo computer simulations were used to investigate the phase behaviour of a Lebwohl-Lasher binary liquid-crystal mixture. A finite-size scaling analysis confirmed the first-order nature of the transition. The calculated nematic-isotopic phase coexistence region and the orientational order par...