A Process-based Model with Temperature, Water, and Lab-derived Data Improves Predictions of Daily Culex pipiens/restuans Mosquito Density.

While the number of human cases of mosquito-borne diseases has increased in North America in the last decade, accurate modeling of mosquito population density has remained a challenge. Longitudinal mosquito trap data over the many years needed for model calibration, and validation is relatively rare. In particular, capturing the relative changes in mosquito abundance across seasons is necessary for predicting the risk of disease spread as it varies from year to year. We developed a discrete, semi-stochastic, mechanistic process-based mosquito population model that captures life-cycle egg, larva, pupa, adult stages, and diapause for Culex pipiens (Diptera, Culicidae) and Culex restuans (Diptera, Culicidae) mosquito populations. This model combines known models for development and survival into a fully connected age-structured model that can reproduce mosquito population dynamics. Mosquito development through these stages is a function of time, temperature, daylight hours, and aquatic habitat availability. The time-dependent parameters are informed by both laboratory studies and mosquito trap data from the Greater Toronto Area. The model incorporates city-wide water-body gauge and precipitation data as a proxy for aquatic habitat. This approach accounts for the nonlinear interaction of temperature and aquatic habitat variability on the mosquito life stages. We demonstrate that the full model predicts the yearly variations in mosquito populations better than a statistical model using the same data sources. This improvement in modeling mosquito abundance can help guide interventions for reducing mosquito abundance in mitigating mosquito-borne diseases like West Nile virus.

Pilot-scale bioremediation of PAH-contaminated soils.

The Institute of Gas Technology (IGT) conducted a pilot-scale study at a former manufactured gas plant (MGP) site in New Jersey. The objective of the study was to determine the effectiveness of an innovative chemical/biological treatment process (MGP-REM process) to remediate soils contaminated with polynuclear aromatic hydrocarbons (PAHs). In order to identify the benefits of the MGP-REM process, the system was also operated in the conventional bioremediation mode. Results showed that the MGP-REM process can effectively treat PAH-contaminated MGP site soils, and it reduced the toxicity of the soil by a factor of 50, as indicated by the Microtox Toxicity Test. The MGP-REM process was 70% more efficient than conventional bioremediation in the removal of the PAHs from the soils. Air emissions data suggest that minimal air pollution control and monitoring are required for the slurry-phase application of both the MGP-REM process and the conventional biological treatment. Process economics indicate that the MGP-REM process in a slurry-phase mode has an estimated treatment cost of $100/cubic yard for remediation of PAH-contaminated soils.

Carotid ligation in gerbils. Influence of age, sex, and gonads.

The ill effects of carotid artery occlusion or ligation vary in man and experimental animals according to surgical techniques, environmental conditions, diet, stress, sex, age, strain of the animal, blood pressure, the state of cardiopulmonary system, and other diverse factors. Unilateral carotid artery ligation in most small laboratory animals is an innocuous procedure. The gerbil, a desert rat, has been found to be quite sensitive to unilateral carotid artery ligation. The present experiments were designed to study the influence of age, sex, and castration on end results of the unilateral carotid artery ligation in gerbils. It appears that the young animals prior to sexual maturity and the sexually mature female are more resistant than the sexually mature male. This difference is assumed to be due to the influence of the gonads on the blood flow of the brain.