Passive soil vapor extraction: A cost effectiveness study

An analysis of the cost effectiveness of passive soil vapor extraction (PSVE) is presented. PSVE, or “barometric pumping,” is an approach to the remediation of volatile organic compounds (VOCs) that seeks to harness and enhance the naturally occurring processes of wind and atmospheric pressure changes to facilitate the release of gas-phase contaminants from the subsurface. The technology background and current status are discussed, niches for the potential applicability of PSVE are identified, and a cost comparison with the conventional treatment method of active soil vapor extraction (ASVE) is examined.     

Operation Child-ID: reunifying children with their legal guardians after Hurricane Katrina

Children constitute a vulnerable population and special considerations are necessary in order to provide proper care for them during disasters. After disasters such as Hurricane Katrina, the rapid identification and protection of separated children and their reunification with legal guardians is necessary in order to minimise secondary injuries (i.e. physical and sexual abuse, neglect and abduction). At Camp Gruber, an Oklahoma shelter for Louisianans displaced by Hurricane Katrina, a survey tool was used to identify children separated from their guardians. Of the 254 children at the camp, 36 (14.2 per cent) were separated from their legal guardians. Answering 'no' to the question of whether the accompanying adult was the guardian of the child prior to Hurricane Katrina was a strong predictor (27.8 per cent versus 3.2 per cent) of being listed as 'missing' by the National Center for Missing and Exploited Children (NCMEC). All the children at Camp Gruber who were listed as 'missing' by the NCMEC were subsequently reunited with their guardians.     

THE POTENTIAL FOR REMOTE SENSING OF LOESS SOILS SUSPENDED IN SURFACE WATERS1

ABSTRACT: The potential for detecting the concentration and type of soils suspended in surface water through remote sensing techniques was investigated by studying the spectral reflectance of two types of soils in suspension. In a large tank filled with 7510 liters of water, 20 levels of suspended sediment (soil) concentration (SSC), ranging from 50 to 1000 mg/l were prepared. A high resolution spectroradiometer was used to measure the reflectance at each SSC level. The reflectance spectra of two contrasting soils were distinct in the visible and near infrared (NIR) portions of the electromagnetic spectrum. The wavelength range between 580–690 nm (visible) was found to be optimal for indicating the type of soil, whereas, the wavelength range between 714–880 (NIR) was found to be appropriate for estimating the concentration of sediment suspended in surface waters.     

Does contrast between eggshell ground and spot coloration affect egg rejection?

Obligate avian brood parasitic species impose the costs of incubating foreign eggs and raising young upon their unrelated hosts. The most common host defence is the rejection of parasitic eggs from the nest. Both egg colours and spot patterns influence egg rejection decisions in many host species, yet no studies have explicitly examined the role of variation in spot coloration. We studied the American robin Turdus migratorius, a blue-green unspotted egg-laying host of the brown-headed cowbird Molothrus ater, a brood parasite that lays non-mimetic spotted eggs. We examined host responses to model eggs with variable spot coloration against a constant robin-mimetic ground colour to identify patterns of rejection associated with perceived contrast between spot and ground colours. By using avian visual modelling, we found that robins were more likely to reject eggs whose spots had greater chromatic (hue) but not achromatic (brightness) contrast. Therefore, egg rejection decision rules in the American robin may depend on the colour contrast between parasite eggshell spot and host ground coloration. Our study also suggests that egg recognition in relation to spot coloration, like ground colour recognition, is tuned to the natural variation of avian eggshell spot colours but not to unnatural spot colours.     

Attribution theory in the organizational sciences: A case of unrealized potential

We argue that although attributional processes appear to affect virtually all goal and reward oriented behavior in organizations, they have not received adequate attention in the organizational sciences. In this Incubator, we encourage scholars to unlock the potential of attribution theory to develop more complete explanations of organizational behavior. Copyright © 2010 John Wiley & Sons, Ltd.     

Forecasts of habitat loss and fragmentation due to urban growth are sensitive to source of input data

The conversion of natural habitat to urban settlements is a primary driver of biodiversity loss, and species' persistence is threatened by the extent, location, and spatial pattern of development. Urban growth models are widely used to anticipate future development and to inform conservation management, but the source of spatial input to these models may contribute to uncertainty in their predictions. We compared two sources of historic urban maps, used as input for model calibration, to determine how differences in definition and scale of urban extent affect the resulting spatial predictions from a widely used urban growth model for San Diego County, CA under three conservation scenarios. The results showed that rate, extent, and spatial pattern of predicted urban development, and associated habitat loss, may vary substantially depending on the source of input data, regardless of how much land is excluded from development. Although the datasets we compared both represented urban land, different types of land use/land cover included in the definition of urban land and different minimum mapping units contributed to the discrepancies. Varying temporal resolution of the input datasets also contributed to differences in projected rates of development. Differential predicted impacts to vegetation types illustrate how the choice of spatial input data may lead to different conclusions relative to conservation. Although the study cannot reveal whether one dataset is better than another, modelers should carefully consider that geographical reality can be represented differently, and should carefully choose the definition and scale of their data to fit their research objectives.     

The value of urban open space: Meta-analyses of contingent valuation and hedonic pricing results

Urban open space provides a number of valuable services to urban populations, including recreational opportunities, aesthetic enjoyment, environmental functions, and may also be associated with existence values. In separate meta-analyses of the contingent valuation (CV) and hedonic pricing (HP) literature we examine which physical, socio-economic, and study characteristics determine the value of open space. The dependent variable in the CV meta-regression is defined as the value of open space per hectare per year in 2003 US$, and in the HP model as the percentage change in house price for a 10 m decrease in distance to open space. Using a multi-level modelling approach we find in both the CV and HP analyses that there is a positive and significant relationship between the value of urban open space and population density, indicating that scarcity and crowdedness matter, and that the value of open space does not vary significantly with income. Further, urban parks are more highly valued than other types of urban open space (forests, agricultural and undeveloped land) and methodological differences in study design have a large influence on estimated values from both CV and HP. We also find important regional differences in preferences for urban open space, which suggests that the potential for transferring estimated values between regions is likely to be limited.     

Predicting deer-vehicle collisions in an urban area

Collisions with deer and other large animals are increasing, and the resulting economic costs and risks to public safety have made mitigation measures a priority for both city and wildlife managers. We created landscape models to describe and predict deer-vehicle collision (DVCs) within the City of Edmonton, Alberta. Models based on roadside characteristics revealed that DVCs occurred frequently where roadside vegetation was both denser and more diverse, and that DVCs were more likely to occur when the groomed width of roadside right-of-ways was smaller. No DVCs occurred where the width of the vegetation-free or manicured roadside buffer was greater than 40 m. Landscape-based models showed that DVCs were more likely in more heterogeneous landscapes where road densities were lower and speed limits were higher, and where non-forested vegetation such as farmland was in closer proximity to larger tracts of forest. These models can help wildlife and transportation managers to identify locations of high collision frequency for mitigation. Modifying certain landscape and roadside habitats can be an effective way to reduce deer-vehicle collisions.     

Stronger predation in the tropics shapes species richness patterns in marine communities

Species interactions are widely assumed to be stronger at lower latitudes, but surprisingly few experimental studies test this hypothesis, and none ties these processes to observed patterns of species richness across latitude. We report here the first experimental field test that predation is both stronger and has a disproportionate effect on species richness in the tropics relative to the temperate zone. We conducted predator-exclusion experiments on communities of sessile marine invertebrates in four regions, which span 32 degrees latitude, in the western Atlantic Ocean and Caribbean Sea. Over a three-month timescale, predation had no effect on species richness in the temperate zone. In the tropics, however, communities were from two to over ten times more species-rich in the absence of predators than when predators were present. While micro-and macro-predators likely compete for the limited prey resource in the tropics, micropredators alone were able to exert as much pressure on the invertebrate communities as the full predator community. This result highlights the extent to which exposure to even a subset of the predator guild can significantly impact species richness in the tropics. Patterns were consistent in analyses that included relative and total species abundances. Higher species richness in the absence of predators in the tropics was also observed when species occurrences were pooled across two larger spatial scales, site and region, demonstrating a consistent scaling relationship. These experimental results show that predation can both limit local species abundances and shape patterns of regional coexistence in the tropics. When preestablished diverse tropical communities were then exposed to predation for different durations, ranging from one to several days, species richness was always reduced. These findings confirmed that impacts of predation in the tropics are strong and consistent, even in more established communities. Our results offer empirical support for the long-held prediction that predation pressure is stronger at lower latitudes. Furthermore, we demonstrate the magnitude to which variation in predation pressure can contribute to the maintenance of tropical species diversity.