Variance Reduction with Array-RQMC for Tau-Leaping Simulation of Stochastic Biological and Chemical Reaction Networks.

We explore the use of Array-RQMC, a randomized quasi-Monte Carlo method designed for the simulation of Markov chains, to reduce the variance when simulating stochastic biological or chemical reaction networks with [Formula: see text]-leaping. The task is to estimate the expectation of a function of molecule copy numbers at a given future time T by the sample average over n sample paths, and the goal is to reduce the variance of this sample-average estimator. We find that when the method is properly applied, variance reductions by factors in the thousands can be obtained.

The application of forecasting techniques to modeling emergency medical system calls in Calgary, Alberta.

We develop and evaluate time-series models of call volume to the emergency medical service of a major Canadian city. Our objective is to offer simple and effective models that could be used for realistic simulation of the system and for forecasting daily and hourly call volumes. Notable features of the analyzed time series are: a positive trend, daily, weekly, and yearly seasonal cycles, special-day effects, and positive autocorrelation.

Microwave synthesis and characterization of Co-ferrite nanoparticles.

Stable CoFe(2)O(4) nanoparticles have been obtained by co-precipitation using a microwave heating system. Transmission electron microscopy images analysis shows an agglomeration of particles with an average size of about 5 nm, and X-ray diffraction reveals the presence of a pure ferrite nanocrystalline phase. X-ray photoelectron spectroscopy and thermal gravimetric analysis show the presence of organic matter in the range of about 16 wt%.

The prospective role of transesophageal echocardiography in the diagnosis and management of patients with suspected infective endocarditis.

Study Objectives: Transesophageal echocardiography (TEE) has a high sensitivity for the diagnosis of infective endocarditis (IE), but the prospective role of TEE when added to a careful clinical examination has not been well-studied.

Design: We compared the results of TEE to a clinical evaluation by an infectious disease specialist in 43 consecutive patients in whom TEE was ordered to rule out IE. Prior to TEE, the patients were classified on clinical grounds as to their likelihood of IE using a modification of the von Reyn criteria.

Surgical site infections after arthroscopy: Outbreak investigation and case control study.

Purpose: The goal of this study was to determine the causes of increased post-arthroscopy surgical site infections (SSIs) and to define risk factors for infection.

Type Of Study: Outbreak investigation and case control study at a university-affiliated community hospital from 1994 to 1996, with surveillance through 1999.

Methods: Demographic, clinical, and microbiological data were collected on 27 post-arthroscopy SSIs from 1994 through 1999.