Exposure estimates for the Houston Area Asthma Study

Procedures for determining exposure extimates for the Houston Area Asthma Study are discussed. Two residential clusters of asthmatics in the Houston area have been studied as part of an overall attempt to assess the health effects of air pollution in the Texas Gulf Coast area. Air pollutant exposure data have been produced according to a three-tier monitoring scheme, i.e. (1) continuous data from centrally-located fixed stations, (2) residential indoor/outdoor measurements, and (3) personal monitoring. This air monitoring network should yield estimates of individual exposures for use in health effect correlations.The fixed sites and mobile continuously monitor ambient levels of ozone, nitrogen oxides, sulfur dioxide, carbon monoxide, and meteorological parameters (wind speed, wind direction, temperature, dew point, solar irradiation, and precipitation). Continuous sequential integrated sampling is preformed for total suspended particulates (TSP) and, inhalable particulates (IP) (total of < 2.5m and 2.5–15.0 m) by dichotomous samplers for 24 hr samplers), aldehydes (bubblers), and aeroallergens (intermittent rotorod samplers). In addition to gravimetric determinations, particulate filters are routinely analyzed for sulfate, nitrate, and (every third day) trace elements. Personal monitoring includes ozone, respirable particles, nitrogen dioxide and formaldehyde. A quality assurance/control program that meets specifications established in the EPA Quality Assurance Handbook for air pollution measurement systems was implemented. Examples of results consisting of unvalidated preliminary data from the monitoring for ozone for three participants is presented and approaches to determining exposure estimates are discussed for both an integrated exposure estimate and short time period exposure estimate.(These studies have been funded by the U.S. Environmental Protection Agency through Cooperative Agreement CR 807108010 and Grant R 808738010. Statements made in this article should not be taken as Agency policy.)     

Evaluation of soil-washing process for “unwashable” clays and silts from the palmerton zinc site

The Palmerton Zinc Site is a Superfund site in Palmerton, Pennsylvania. Its former mineral processing operations have contaminated nearby wells and soils with zinc and cadmium. Preliminary analysis of soil and dust sampling conducted in May 1991 has revealed that the dust poses a potential threat to human health. Based on the results of a previous study, which showed a high percentage of silt and clay in soils from Palmerton residential properties, it was concluded that soil washing is not likely to be a viable method to treat the soil and dust contamination in Palmerton. However, since the completion of this study, a soil-washing process for “unwashable” clays and silts has been developed. A residential soil sample from Palmerton, which had low concentrations of arsenic, cadmium, and lead, and a somewhat high concentration of zinc, was washed in a bench-scale version of this process. The results showed that the new soil-washing process for “unwashable” clays and silts may be a viable method to treat the soil and dust contamination in Palmerton, depending on the soil quality criteria concentrations selected for site cleanup.     

USE OF STATE ESTIMATION TECHNIQUES IN WATER RESOURCE SYSTEM MODELING1

ABSTRACT. A relatively straightforward illustration of the potential uses of State Estimation techniques in water resources modeling is given. Background theory for Linear and Extended Kalman Filters is given; application of the filter techniques to modeling BOD and oxygen deficit in a stream illustrates the importance of model conceptualization, model completeness, uncertainty in model dynamics and incorporation of measurements and measurement errors. Potential applications of state estimation techniques to measurement system design; model building, assessment and calibration; and data extension are explored.     

COVERING BOTTOM SEDIMENTS AS A LAKE RESTORATION TECHNIQUE1

ABSTRACT: Sediment covering to control macrophytes and sediment nutrient release is reviewed. It is concluded that fly ash application to control sediment phosphorus release presents more dangers to the lake than benefits and should not be used. Polyethylene sheeting has not had long term effectiveness due to macrophyte regrowth on its surface. PVC-coated fiberglass screen is expensive but nontoxic and appears to give long term macrophyte control. Similar results may be obtained with spun-bonded polypropylene. Sand, clay, and sheeting to retard nutrient release have received insufficient attention.     

Kinship affects puberty acceleration in mice (Mus musculus)

Summary Juvenile female mice (Mus musculus) were exposed to the soiled bedding of unfamiliar males of different degrees of genetic relatedness. Females exposed to the soiled bedding of first cousins and unrelated males show an acceleration of first oestrus relative to controls. In contrast, females exposed to the soiled bedding of fathers or uncles show no such acceleration.     

Explanative power of variables used in species distribution modelling: an issue of general model transferability or niche shift in the invasive Greenhouse frog (Eleutherodactylus planirostris)

The use of species distribution models (SDMs) to predict potential distributions of species is steadily increasing. A necessary assumption when projecting models throughout space or time is that climatic niches are conservative, but recent findings of niche shifts during biological invasion of particular plant and animal species have indicated that this assumption is not categorically valid. One reason for observed shifts may relate to variable selection for modelling. In this study, we assess differences in climatic niches in the native and invasive ranges of the Greenhouse frog (Eleutherodactylus planirostris). We analyze which variables are more ‘conserved’ in comparison to more ‘relaxed’ variables (i.e. subject to niche shift) and how they influence transferability of SDMs developed with Maxent on the basis of ten bioclimatic layers best describing the climatic requirements of the target species. We focus on degrees of niche similarity and conservatism using Schoener's index and Hellinger distance. Significance of results are tested with null models. Results indicate that the degrees of niche similarity and conservatism vary greatly among the predictive variables. Some shifts can be attributed to active habitat selection, whereas others apparently reflect variation in the availability of climate conditions or biotic interactions between the frogs' native and invasive ranges. Patterns suggesting active habitat selection also vary among variables. Our findings evoke considerable implications on the transferability of SDMs over space and time, which is strongly affected by the choice and number of predictors. The incorporation of ‘relaxed’ predictors not or only indirectly correlated with biologically meaningful predictors may lead to erroneous predictions when projecting SDMs. We recommend thorough assessments of invasive species' ecology for the identification biologically meaningful predictors facilitating transferability.     

Dilution sampling and analysis of particulate matter in biomass-derived syngas

Thermochemical biomass gasification, followed by conversion of the produced syngas to fuels and electrical power, is a promising energy alternative. Real-world characterization of particulate matter (PM) and other contaminants in the syngas is important to minimize damage and ensure efficient operation of the engines it powers and the fuels created from it. A dilution sampling system is demonstrated to quantify PM in syngas generated from two gasification plants utilizing different biomass feedstocks: a BioMax?15 Biopower System that uses raw and torrefied woodchips as feedstocks, and an integrated biorefinery (IBR) that uses rice hulls and woodchips as feedstocks. PM_2.5 mass concentrations in syngas from the IBR downstream of the purification system were 12.8–13.7 μg·m⁻³, which were significantly lower than the maximum level for catalyst protection (500 μg·m⁻³) and were 2–3 orders of magnitude lower than those in BioMax?15 syngas (2247–4835 μg·m⁻³). Ultrafine particle number concentration and PM_2.5 chemical constituents were also much lower in the IBR syngas than in the BioMax?15. The dilution sampling system enabled reliable measurements over a wide range of concentrations: the use of high sensitivity instruments allowed measurement at very low concentrations (∼1 μg·m⁻³), while the flexibility of dilution minimized sampling problems that are commonly encountered due to high levels of tars in raw syngas (∼1 g·m⁻³).     

The call for an increased role of replication,extension, and mixed‐methods study designs in organizational research

Examples from previously published work by the lead author on the role of employee health indicators on individual and organizational outcomes provide an intriguing backdrop through the use of illustration for suggesting some of the many benefits obtained by the incorporation of replication, extension, and mixed‐methods study designs in organizational research. Copyright © 2015 John Wiley & Sons, Ltd.     

Testing environmental effects on taxonomic composition with canonical correspondence analysis: alternative permutation tests are not equal

Environmental and Ecological Statistics - After applying canonical correspondence analysis to metagenomics data with hugely different library sizes (site totals) it became evident that Canoco and...