Random variate generation and connected computational issues for the Poisson–Tweedie distribution

After providing a systematic outline of the stochastic genesis of the Poisson–Tweedie distribution, some computational issues are considered. More specifically, we introduce a closed form for the probability function, as well as its corresponding integral representation which may be useful for large argument values. Several algorithms for generating Poisson–Tweedie random variates are also suggested. Finally, count data connected to the citation profiles of two statistical journals are modeled and analyzed by means of the Poisson–Tweedie distribution

Microbial study of household hygiene conditions and associated Listeria monocytogenes infection risks for Peruvian women

Objectives To develop an exposure and risk assessment model to estimate listeriosis infection risks for Peruvian women. Methods A simulation model was developed utilising Listeria monocytogenes concentrations on kitchen and latrine surfaces in Peruvian homes, hand trace data from Peruvian women and behavioural data from literature. Scenarios involving varying proportions of uncontaminated, or 'clean', surfaces and non-porous surfaces were simulated. Infection risks were estimated for 4, 6 and 8 h of behaviours and interactions with surfaces. Results Although infection risks were estimated across scenarios for various time points (e.g. 4, 6, 8 h), overall mean estimated infection risks for all scenarios were >= 0.31. Infection risks increased as the proportions of clean surfaces decreased. Hand-to-general surface contacts accounted for the most cumulative change in L. monocytogenes concentration on hands. Conclusions In addition to gaining insights on how human behaviours affect exposure and infection risk, this model addressed uncertainties regarding the influence of household surface contamination levels. Understanding the influence of surface contamination in preventing pathogen transmission in households could help to develop intervention strategies to reduce L. monocytogenes infection and associated health risks.Clorox Company12 month embargo; published online: 7 May 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Nutrients and chlorophyll-a dynamics in a temperate reservoir influenced by Asian monsoon along with in situ nutrient enrichment bioassays

Long-term nutrients and chlorophyll-a dynamics during 1993-2000 were analyzed in a temperate reservoir influenced by the Asian monsoon. Nonparametric Mann-Kendall tests and seasonal trend analyses indicated that there were no long-term annual increasing or decreasing trends in major trophic parameters over 8 years, but the monsoon seasonality was evident. Seasonality in chlorophyll (CHL) and total phosphorus (TP) showed a mono-modal pattern, which was closely associated with the monsoon season of July-August, and the magnitude of the mono-modal peak was greater in the headwater zone than in the downlake zone. Such temporal patterns fluctuated interannually over the study period, and the magnitude of the variation was directly controlled by the intensity of the monsoon rain. Empirical models of annual mean CHL-TP were developed supporting the view that phytoplankton in lentic ecosystems responds to P enrichment and that annual mean TP may provide a reliable basis for predicting the average algal abundance. Ambient nutrient analyses, N:P ratios and in situ nutrient enrichment bioassay experiments (NEBs) in premonsoon and postmonsoon supported the P limitation for phytoplankton growth. Ambient nutrients and non-volatile suspended solid (NVSS) data on CHL in the intense monsoon year, however, showed the possibility of light limitation, even though the NEBs did not show the direct evidence. These findings were confirmed by two-dimensional graphic approaches of trophic state index deviations (TSIDs).