Unbalanced exchange flow and its implications for the night cooling of buildings by displacement ventilation

Environmental Fluid Mechanics - Passive ventilation of buildings at night forms an essential part of a low-energy cooling strategy, enabling excess heat that has accumulated during the day to...     

Brain cancer incidence rates and the presence of nuclear reactors in US states: a hypothesis-generating study

Environmental Geochemistry and Health - The etiology of brain cancer is poorly understood. The only confirmed environmental risk factor is exposure to ionizing radiation. Because nuclear reactors...     

PCB126 blocks the thermogenic beiging response of adipocytes

Environmental Science and Pollution Research - Subcutaneous white adipose tissue is capable of becoming thermogenic in a process that is referred to as “beiging.” Beiging is associated...     

Efficacy of Bacteroides measurements for reducing the statistical uncertainty associated with hydrologic flow and fecal loads in a mixed use watershed

This paper presents an analysis of the occurrence and uncertainty of source-specific Bacteroides and Escherichia coli in a stream in a mixed land-use watershed with human, cattle, and wildlife fecal inputs located in a karstic geologic region during baseflow conditions. The objectives of the study were to evaluate the occurrence, hydrologic significance, and source of fecal mass in the stream using assays for total Bacteroides (AllBac) and bovine-specific Bacteroides (BoBac), and then to compare these measurements with E. coli densities and loads. Samples were collected during baseflow conditions over several months at seven different main channel sites in the Stock Creek watershed, a 49.3 km2 basin located in Knoxville, TN (USA). We determined instantaneous loads for total fecal loads, bovine fecal loads, and E. coli from measured flow rates and the representative Bacteroides fecal masses and/or E. coli densities. The study indicated a strong correlation between total fecal load (kg d(-1)), bovine fecal load (kg d(-1)), E. coli load rate (CFU d(-1)), 7-d antecedent precipitation, and turbidity. The various datasets were used to establish parameter correlations and spatial dependencies throughout the watershed. The data analysis demonstrated two prevalent patterns throughout the watershed: (i) a runoff-dominated transport and occurrence; and (ii) potential groundwater-dominated transport and occurrence.     

Habitat as a mediator of mesopredator‐driven mammal extinction

A prevailing view in dryland systems is that mammals are constrained by the scarcity of fertile soils and primary productivity. An alternative view is that predation is a primary driver of mammal assemblages, especially in Australia, where 2 introduced mesopredators—feral cat (Felis catus) and red fox (Vulpes vulpes)—are responsible for severe declines of dryland mammals. We evaluated productivity and predation as drivers of native mammal assemblage structure in dryland Australia. We used new data from 90 sites to examine the divers of extant mammal species richness and reconstructed historic mammal assemblages to determine proportional loss of mammal species across broad habitat types (landform and vegetation communities). Predation was supported as a major driver of extant mammal richness, but its effect was strongly mediated by habitat. Areas that were rugged or had dense grass cover supported more mammal species than the more productive and topographically simple areas. Twelve species in the critical weight range (CWR) (35–5500 g) that is most vulnerable to mesopredator predation were extirpated from the continent's central region, and the severity of loss of species correlated negatively with ruggedness and positively with productivity. Based on previous studies, we expect that habitat mediates predation from red foxes and feral cats because it affects these species’ densities and foraging efficiency. Large areas of rugged terrain provided vital refuge for Australian dryland mammals, and we predict such areas will support the persistence of CWR species in the face of ongoing mammal declines elsewhere in Australia.     

Case study approach to modeling historical disinfection by-product exposure in Iowa drinking waters

In the 1980 s, a case–control epidemiologic study was conducted in Iowa(USA) to analyze the association between exposure to disinfection by-products(DBPs) and bladder cancer risk. Trihalomethanes(THMs), the most commonly measured and dominant class of DBPs in drinking water, served as a primary metric and surrogate for the full DBP mixture.Average THM exposure was calculated, based on rough estimates of past levels in Iowa. To reduce misclassification, a follow-up study was undertaken to improve estimates of past THM levels and to re-evaluate their association with cancer risk. In addition, the risk associated with haloacetic acids, another class of DBPs, was examined. In the original analysis, surface water treatment plants were assigned one of two possible THM levels depending on the point of chlorination. The re-assessment considered each utility treating surface or groundwater on a case-by-case basis. Multiple treatment/disinfection scenarios and water quality parameters were considered with actual DBP measurements to develop estimates of past levels. The highest annual average THM level in the re-analysis was156 μg/L compared to 74 μg/L for the original analysis. This allowed the analysis of subjects exposed at higher levels( 96 μg/L). The re-analysis established a new approach, based on case studies and an understanding of the water quality and operational parameters that impact DBP formation, for determining historical exposure.     

中国、印度和世界的新秩序《世界报告2006》第一章(续)

转向世界粮食市场 与严重依赖外国石油的状况形成鲜明对照的是,中国和印度如今在粮食方面处于自给自足的状态,并为它们的成就而自豪（图1-2）.这两个国家都经历过严重饥荒的困难历史,都不希望这一悲剧情况重演.自从1985年以来,中国进口的粮食从来没有超过其消费总量的6%,而印度进口的粮食也没有超过其消费总量的3%（表1-3）.但是,在未来的几十年内,这两个大国是否可以避免求助于全球粮食市场（主要指小麦、水稻、玉米和其他主要基本食品）,已成为这两个国家和全球的一个尚待解决的、重要的问题.这是由于：世界粮食市场与石油市场的状况一样,与20世纪比较,指望生产过剩已经远非那么可靠了.     

The effect of vegetation density on male mate guarding and extra-territorial forays in the yellow-breasted chat (<Emphasis Type="Italic">Icteria virens</Emphasis>)

Extra-pair paternity is widely documented in birds, but the behaviors that lead to extra-pair copulations (EPCs) have been less well studied, particularly in territorial songbirds. We studied the behaviors associated with extra-territorial forays (ETFs) and male mate guarding in a socially monogamous, but genetically promiscuous, neotropical migrant passerine, the yellow-breasted chat (Icteria virens). Focal observations and radiotelemetry revealed that both males and females engaged in ETFs. 65% of the females in our study engaged in at least one foray onto a neighboring territory. 50% of males also were observed engaging in ETFs, but males were much more conspicuous during these intrusions compared to females. Females preferred to remain close to the ground in areas where vegetation was the densest. Female behavior was difficult to observe during ETFs but females sometimes interacted with neighboring extra-pair males. Males attempted to guard their mates by remaining close to them and following them during extra-territorial intrusions. We observed instances in which a male attacked his mate and appeared to herd her back to his territory. However a males ability to maintain close proximity to his mate was significantly and negatively correlated with vegetation density. Our results suggest that the behaviors which lead to extra-pair encounters are influenced by the behavior of all participants and are modified by the characteristics of the habitat.