Estimates of Particle Hygroscopicity during the Southeastern Aerosol and Visibility Study

ABSTRACT

Aerosol water content was determined from relative humidity controlled optical particle counter (ASASP-X) size distribution measurements made during the Southeastern Aerosol and Visibility Study (SEAVS) in the Great Smoky Mountains National Park during summer 1995. Since the scattering response function of the ASASP-X is sensitive to particle refractive index, a technique for calibrating the ASASP-X for any real refractive index was developed. A new iterative process was employed to calculate water mass concentration and wet refractive index as functions of relative humidity. Experimental water mass concentrations were compared to theoretically predicted values assuming only ammonium sulfate compounds were hygroscopic. These comparisons agreed within experimental uncertainty. Estimates of particle hygroscopicity using a rural aerosol model of refractive index as a function of relative humidity demonstrated no significant differences from those made with daily varying refractive index estimates. Although aerosol size parameters were affected by the assumed chemical composition, forming ratios of these parameters nearly canceled these effects.     

Aphid population response to agricultural landscape change: A spatially explicit,individual-based model

A spatially explicit individual-based simulation model has been developed to represent aphid population dynamics in agricultural landscapes. The application of the model to Rhopalosiphum padi (L.) population dynamics is detailed, including an outline of the construction of the model, its parameterisation and validation. Over time, the aphids interact with the landscape and with one another. The landscape is modified by varying a simple pesticide regime, and the multi-scale spatial and temporal implications for a population of aphids is analysed. The results show that a spatial modelling approach that considers the effects on the individual of landscape properties and factors such as wind speed and wind direction provides novel insight into aphid population dynamics both spatially and temporally. This forms the basis for the development of further simulation models that can be used to analyse how changes in landscape structure impact upon important species distributions and population dynamics.     

A harvest failure approach to assess the threat from an invasive species

We present the idea of using potential infringements on annual allowable harvest targets as an approach to estimate threats from invasive species to the forest products sector. The approach uses present-day harvest levels as a reference level to estimate when and where the impact of a nonnative forest pest could become economically damaging. We use a generic model that simulates spread and damage by nonnative invasive species, basic harvest and forest growth through time. The concept is illustrated with a case study of a new nonnative invasive pest, Sirex noctilio Fabricius on pine resources in eastern Canada. Impacts of invasion on wood supply, in particular, the point at which present-day harvest levels are not attainable, were identified for 77 non-overlapping geographical regions that delimit the primary wood supply areas around large mills and wood processing facilities in eastern Canada. The results identify the minimum area of a pest outbreak that could trigger harvest shortages (approximately 12.5–14 M ha of pine forests in Ontario and Quebec). Beyond this level, the amount of host resource available for harvesting in any given year declines rapidly. The failure to sustain broad-scale harvest targets may be an attractive and intuitive indicator for policy makers and regulators interested in developing control and “slow-the-spread” programs for non-native forest pests.     

Demography and disappearing merchandise: How older workforces influence retail shrinkage

Prior research on retail shrinkage has taken a largely individual‐level approach to theorizing about why it occurs, showing that older employees are less prone to theft and more vigilant in preventing customer shoplifting than younger personnel. However, given the influence of organizational contexts on organizational behavior, theorizing about shrinkage may be enhanced by the consideration of business‐unit level contextual variables. The present study addressed this concern by examining the relationship between store‐level age composition, whistle‐blowing (WB) climate, and shrinkage in 726 retail stores. Results indicated that the negative mean age–shrinkage relationship was stronger when there was less age diversity or a climate more supportive of WB. Moreover, the negative WB climate–shrinkage linkage was stronger when the mean age was higher. Copyright © 2011 John Wiley & Sons, Ltd.     

Use of local tidal records to identify relative sea level change: accuracy and error for decision makers

The Intergovernmental Panel on Climate Change (IPCC) considers eustatic sea level rise to be a major impact driven by climate change. Relative sea level change, whether positive or negative, will affect industries, communities and ecology along the world??s coastlines and estuaries. Estimates of global eustatic sea level rise between 1961 and 2003 are 1.8?±?0.5?mm a^?1, reflecting results from validated global tide gauge records. Over the last two decades, several studies have used automatic tide gauge records with at least 80?years of data to generate global prediction models. The IPCC recognises that global change is not uniform, therefore local policy for flood management and coastal protection should rely on local change models that incorporate glacio-isostatic adjustment (GIA) and apply accurate data correction techniques. Some of the longest tidal records are held within the Northern Hemisphere, e.g. Cascais, Amsterdam, Aberdeen, Sheerness and Newlyn. The UK provides several important case studies highlighting changes in relative sea level between the north and the south, primarily due to variations in GIA rates of land uplift and subsidence. Tide gauge records are held by a variety of governmental, non-governmental and private organisations. However, each source may typically compile data in different ways, relying on diverse equipment and recording techniques, often with variations in frequency, length, quality and corrections applied. Even within a single organisation there may be differences in dataset quality. This paper examines some of the key sources of error when working with historical tidal datasets in local geographic areas and aims to identify the limitations of locally derived data thereby assisting in the determination of relative sea level trends that are of widespread value to infrastructure and policy makers.     

STREAM-CHANNEL INCISION FOLLOWING DRAINAGE-BASIN URBANIZATION1

ABSTRACT: Urbanization of a drainage basin results in pervasive hydrologic changes that in turn initiate long-term changes in stream channels. Increases in peak discharges and in durations of high flows result in either quasi-equilibrium channel expansion, where cross-section area increases in near-proportion to the discharge increase, or catastrophic channel incision, where changes occur far out of proportion to the discharge increases that initiated them. Field data and hydrologic modeling of rapidly urbanizing basins in King County, Washington, define conditions of flow, topography, geology, and channel roughness that identify streams susceptible to incision. Channel slope and geologic material are particularly critical; thus simple map overlays, nearly irrespective of contributing drainage area, provide a valuable planning tool for identification of susceptible terrain. Where such conditions exist, basal shear stress provides a quantifiable parameter for predicting likely problems, although knickpoints are typical in such settings and confound simple calculation of sediment-transport rates. Where urbanization proceeds in such areas, effective mitigation of the incision hazards requires a degree of stormwater control far in excess of standards typically applied to present development activity.     

OPINIONS RELATING TO FLUORIDATION: DEVELOPMENT OF MEASURES1

ABSTRACT. Elected officials, technical specialists and the public are talking more about “citizen input” into the decision process, and how the people view a given issue or kind of public service. However, problem definition and valid instruments are needed before we can meaningfully predict or understand public attitude relating to a particular issue or concept. The fluoridation of community water supplies was chosen for the present methodological demonstration. This issue achieves a high level of controversy among many public segments [Crain, Katz and Rosenthal, 1969; Davis, 1959; McNeal, 1957]. By 1950, there was widespread endorsement for a national program relating to controlled water fluoridation. Yet, public acceptance of this particular technological advance has not been very high.     

Hygroscopic organic aerosols during BRAVO?

The hygroscopic properties of the organic fraction of aerosols are poorly understood. The ability of organic aerosols to absorb water as a function of relative humidity (RH) was examined using data collected during the 1999 Big Bend Regional Aerosol and Visibility Observational Study (BRAVO). (On average, organics accounted for 22% of fine particulate matter with an aerodynamic diameter less than 2.5 microm (PM2.5) mass). Hourly RH exceeded 80% only 3.5% of the time and averaged 44%. BRAVO aerosol chemical composition and dry particle size distributions were used to estimate PM2.5 light scattering (Bsp) at low and high ambient RH. Liquid water growth associated with inorganic species was sufficient to account for measured Bsp for RH between 70 and 95%.     

The Surface Roughness of a Rubber Soling Material Determines the Coefficient of Friction on Water-Lubricated Surfaces

For more than a decade, evidence has been accumulating that points to the fact that the microscopic roughness of the footwear soling surface is a major determinant of slip-resistance on lubricated surfaces, but conclusive experimental proof has been lacking. This article describes an experiment in which five pairs of shoes were soled with the same rubber compound. Four of the pairs were abraded by different grades of grit to produce a range of roughness values. The coefficient of friction (CoF) of the five solings was then measured repeatedly by the walking traction method on wet surfaces including glazed wall tiles, vinyl asbestos coated with the wax floor polish, and both sides of a sheet of float glass. The Kruskal-Wallis statistical test proved beyond doubt that the soling roughness is a major factor in determining the CoF of this rubber soling material; p < 10⁻⁵. Nearly all of the grip was due to surface roughness of the soling material on these atypically smooth floors, although the surface roughness of the floors also had a significant effect on CoF; p < 0.003. Float glass is shown to be a promising reference floor material for the measurement of CoF of footwear; there was no statistical difference between results for the two sides of the glass sheet. Float glass could be used in the development of a standard CoF test method because new sheets of glass from the same manufacturer are identical and extremely smooth. The specification of CoF values for solings/floors combinations in lubricated conditions is of little value unless associated with roughness measurements and knowledge of how wear will affect the surface roughness of the sole. This article reports the first evidence that any specification of flooring by measuring CoF based on dry surfaces could lead to an increase in the number of injuries caused by slipping on the wet surfaces. Published by Elsevier Science Ltd     

The importance of the “not-so-cool” sectors: creative solutions to reconcile environmental and economic sustainability within a floodplain

Creative cities are generally considered as “cool” spaces which attract a particular “creative class” whose ability to innovate and transform – particularly in the media and cultural sectors – offers urban economies a competitive edge. This paper argues that, in the face of dangerous climate change, the creativity of the “not-so-cool” sectors needs to be acknowledged and valued. A case study of Salford in the north-west of England shows how political, technological and economic creativity has secured sustainable regeneration within a floodplain. It is argued that the concept of “creativity” in urban economic discourse needs to be widened to acknowledge the importance of the creativity of planners, civil engineers and builders in securing environmentally sustainable cities. Environmental sustainability, it suggests, not only underpins economic sustainability. Faced with dangerous climate change and society's need to respond, the skills and expertise can in themselves contribute to a city's competitiveness.