A Simple Method of Calculating Dispersion from Urban Area Sources

A simple but physically realistic model is shown to be adequate for estimating pollutant concentrations due to area sources in cities. In this model, the surface concentration is directly proportional to the local area source strength and inversely proportional to the wind speed. The model performs nearly as well as much more complex models that require the use of digital computers.     

Ozone and other air quality-related variables affecting visibility in the southeast United States

An analysis of ozone (O3) concentrations and several other air quality-related variables was performed to elucidate their relationship with visibility at five urban and semi-urban locations in the southeast United States during the summer seasons of 1980-1996. The role and impact of O3 on aerosols was investigated to ascertain a relationship with visibility. Regional trend analysis over the 1980s reveals an increase in maximum O3 concentration coupled with a decrease in visibility. However, a similar analysis for the 1990s shows a leveling-off of both O3 and visibility; in both cases, the results were not statistically significant at the 5% level. A case study of site-specific trends at Nashville, TN, followed similar trends. To better understand the relationships between O3 concentration and visibility, the analysis was varied from yearly through daily to hourly averaged values. This increased temporal resolution showed a statistically significant inverse relationship between visibility and O3. Site-specific hourly r2 values ranged from 0.02 to 0.43. Additionally, by performing back-trajectory analysis, it was found that the visibility degraded by air mass migration over polluted areas.     

The interaction of heavy metals with urban soils: sorption behaviour of Cd, Cu, Cr, Pb and Zn with a typical mixed brownfield deposit

This study investigated the sorption characteristics and release of selected heavy metals (Cd, Cu, Cr, Pb and Zn) from a typical urban soil material from a derelict brownfield site in Western Scotland, UK. The study aimed to evaluate contaminant interactions with an urban substrate, comprising a mix of mineral soil and residue materials (e.g. brick, concrete, wood). This type of material has received little consideration in the literature to date. Soil samples were subject to a sequence of test involving batch equilibration and dynamic leaching, in single (non-competitive) and multi-element (competitive) solutions. The batch experiments were carried out in unadjusted and close to soil field pH conditions (pH 2 and 7, respectively). The equilibrium adsorption capacity for heavy metals was measured and extrapolated using the Langmuir isotherm. The parameters of the isotherms x(m) (the maximum amount adsorbed per unit mass of adsorbent (mg/g)) and b (adsorption constant (m(3)/g)) were calculated for Cd, Cu, Cr, Pb as single-element and multi-element solutions. The adsorption from the single-element solution was more effective than adsorption under multi-element conditions, due to competitive effects. For example, the adsorption of copper from a single-element solution was over four times greater than for a multi-element solution. In the case of Cr and Zn, migration of metal from soil to solution was observed. Adsorption capacity at pH 2 followed the order Cr>Cu>Pb>Cd and at pH 7 Cd>Zn, with precipitation affecting Cu and Pb behaviour. During the column leaching experiment, most of the heavy metals were irreversibly bound to the soil, but in the case of Cr some movement from soil into solution was observed. The results also showed that Cd, Cu, Pb and Zn were removed from the solution and adsorbed on the soil. No significant difference in the metal removal from single- and multi-element solutions was observed. Overall, the urban residue behaved in a similar manner to mineral soils despite a significant component of anthropogenic solid materials.     

Functional Properties of Extruded Starch Acetate Blends

Starch acetate, with degree of substitution of 2, was blended with 0, 7.5 and 15% polylactic acid (PLA), Eastar Bio Copolyester 14766 (EBC) or Mater-Bi ZF03U (MBI) and 10%, 13%, or 16% (d.b.) ethanol and twin-screw extruded at 160°C barrel temperature. Physical characteristics of the extrudates, such as radial expansion ratio, unit and bulk densities, and of the mechanical properties, including unit spring index and bulk spring index, were measured. Type of polymer, polymer content, and ethanol content significantly affected the physical characteristics and mechanical properties. The sample extruded with 7.5% PLA and 13% ethanol had the highest expansion ratio and bulk spring index. The sample with 15% MBI and 16% ethanol had the lowest unit density, while the sample with 7.5% PLA and 16% ethanol had lowest bulk denisty. The highest unit spring index was expressed in the sample containing 7.5% PLA and 10% ethanol.     

Can infantile hereditary agranulocytosis be diagnosed prenatally?

Fetoscopy and fetal blood sampling were performed in an attempt at prenatal monitoring of a pregnancy at risk for infantile hereditary agranulocytosis (Kostmann's disease). In smears of fetal blood three segmented neutrophils were found out of 200 nucleated cells (1 2/ per cent). Their presence, although in a lower percentage than in six age-matched controls, was considered to indicate that the fetus was not affected. The newborn infant has developed normally and at the age of four months has a normal number of segmented neutrophils in his peripheral blood. Feasibility of prenatal diagnosis of infantile hereditary agranulocytosis is discussed.     

Risk Analysis of Hunting of Seal Populations in the Baltic

Vulnerabilities of grey seal ( Halichoerus grypus) and ringed seal ( Phoca hispida) populations in the Baltic Sea were evaluated for potential opening of the populations for hunting. We used ecological risk analysis to assess the effects of environmental and demographic stochasticity and uncertain and partly missing population data on the modeled outcomes. The impact of different harvesting strategies on the long-term sustainability of seal populations was analyzed with four different models with increasing complexity and population detail. It appears the simpler the population model used, the more overconfident results it gave with regard to the hunting policy to be adopted. Therefore, it proves risky in population management decisions to rely on simplistic calculations based on growth rate and estimated population size alone. This is even more so if the population estimates have a wide error margin. Due to an unknown, but presumably positive number of seal kills in the Baltic at present, the sustainable harvest is likely to be close to zero for both seal species. Our risk analysis strongly suggests refraining from Baltic seal hunting now, with their current population sizes, and in the future if the development of population numbers cannot be assessed accurately enough.     

Aufnahme und Verteilung von Trichloressigsäure in Trieben Norwegischer Fichte

To elucidate the uptake of TCA by roots and its distribution in Norway spruce shoots, experiments with [¹⁴C]TCA were carried out in combination with radioactivity measurements after combustion, and with autoradiographic detection methods. It was shown that the uptake of TCA by spruce shoots is faster during the growth period in June than in the post-growth period in September. A high uptake of radioactivity was observed in the current-year needles, especially in the top of them, and in the corc cambium of the one-year-old wooden parts of the spruce shoots. The results of our experiments suggest uptake of TCA into spruce needles from the soil water with the transpiration stream.     

Adaptive strategies of territory formation

How do territorial animals gain ownership of an area? Early modelling has considered the evolution of fighting when the winner can claim the right to the resource. Recently, alternative hypotheses have been offered where repeated interactions lead to division of space through 'nagging' instead of one decisive fight. However, these models assume that animals avoid areas in which they have taken part in aggressive interactions, but do not consider whether avoidance itself is adaptive. We aim to bridge this gap between mechanistic and adaptive explanations, by presenting a game-theory model where individuals choose whether to return to an area after a fight with a specific outcome (win, loss, draw). We show that avoidance of areas where fights have occurred can be adaptive, but only if benefits of access to the area are low compared to costs of fighting. Otherwise, one individual (typically the winner) responds by returning to the area, and the other (loser) avoids it. In such cases, space is gained by winning fights. We also consider the role of conventions. If responses to fights were purely conventional, paradoxical strategies where losers of fights gain ownership would be equally logical as common-sense ones where winners claim ownership. Paradoxical solutions can be stable but only when there is little difference in fighting ability between the competitors, when individuals adhere very strictly to a behavioural rule without much random variation, and when the population in its ancient state used a paradoxical strategy.