Sampling from the posterior distribution using Markov chain Monte Carlo (MCMC) methods can require an exhaustive number of iterations to fully explore the correct posterior. This is often the case when the posterior of interest is multi-modal, as the MCMC sampler can become trapped in a local mode for a large number of iterations. In this paper, we introduce the pseudo-extended MCMC method as a...

A passive air sampler, using 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole, was evaluated for the determination of formaldehyde in indoor environments. Chromatography paper cleaned using a 3% hydrogen peroxide solution was experimentally determined as being the optimum absorption filter for the collection of formaldehyde (0.05 microg cm(-2) formaldehyde). From a linear-regression analysis betwe...

Porous polyurethane foam was evaluated to replace the eight nylon meshes used as a substrate to collect nanoparticles in the Nanoparticle Respiratory Deposition (NRD) sampler. Cylindrical (25-mm diameter by 40-mm deep) foam with 110 pores per inch was housed in a 25-mm-diameter conductive polypropylene cassette cowl compatible with the NRD sampler. Pristine foam and nylon meshes were evaluated ...

The objective of this work was to investigate the ability of the Wagner-Leith passive aerosol sampler to measure indoor exposures over periods of 24 hours to 2 weeks. An automated analysis technique was developed so that lower aerosol concentrations could be sampled over shorter time periods. A test of the new analytical method against a manual method showed good agreement. The passive sampler ...

Discrete Gaussian sampling is an integral part of many lattice based cryptosystems such as public-key encryption, digital signature schemes and homomorphic encryption schemes. In this paper we propose a compact and fast Knuth-Yao sampler for sampling from a narrow discrete Gaussian distribution with very high precision. The designed samplers have a maximum statistical distance of 2 to a true di...

Ambient bioaerosols are ubiquitous in the daily environment and can affect health in various ways. However, few studies have been conducted to comprehensively evaluate personal bioaerosol exposure in occupational and indoor environments because of the complex composition of bioaerosols and the lack of standardized sampling/analysis methods. We conducted a study to determine the most efficient c...