Measurement and analysis of non-Fickian dispersion in heterogeneous porous media

Contaminant breakthrough behavior in a variety of heterogeneous porous media was measured in laboratory experiments, and evaluated in terms of both the classical advection-dispersion equation (ADE) and the continuous time random walk (CTRW) framework. Heterogeneity can give rise to non-Fickian transport patterns, which are distinguished by "anomalous" early arrival and late time tails in breakthrough curves. Experiments were conducted in two mid-scale laboratory flow cells packed with clean, sieved sand of specified grain sizes. Three sets of experiments were performed, using a "homogeneous" packing, a randomly heterogeneous packing using sand of two grain sizes, and an exponentially correlated structure using sand of three grain sizes. Concentrations of sodium chloride tracer were monitored at the inflow reservoir and measured at the outflow reservoir. Breakthrough curves were then analyzed by comparison to fitted solutions from the ADE and CTRW formulations. In all three systems, including the "homogeneous" one, subtle yet measurable differences between Fickian and non-Fickian transport were observed. Quantitative analysis demonstrated that the CTRW theory characterized the full shape of the breakthrough curves far more effectively than the ADE.     

Comparative study on the susceptibility of freshwater species to copper-based pesticides

Copper compounds have been intentionally introduced into water bodies as aquatic plant herbicides, algicides and molluscicides. Copper-based fertilizers and fungicides have been widely used in agriculture as well. Despite the fact that copper is an essential element for all biota, elevated concentrations of this metal have been shown to affect a variety of aquatic organisms. Nonetheless, comparative studies on the susceptibility of different freshwater species to copper compounds have seldom been performed. This study was conducted to compare toxicity of copper-based pesticides (copper oxychloride, cuprous oxide and copper sulfate) to different freshwater target (Raphidocelis subcapitata, a planktonic alga and Biomphalaria glabrata, a snail) and non-target (Daphnia similis, a planktonic crustacean and Danio rerio, a fish) organisms. Test water parameters were as follows: pH = 7.4 +/- 0.1; hardness 44 +/- 1 mg/l as CaCO3; DO 8-9 mg/l at the beginning and > 4 mg/l at the end; temperature, fish and snails 25 +/- 1 degrees C, Daphnia 20 +/- 2 degrees C, algae 24 +/- 1 degrees C. D. similis (immobilization), 48-h EC50s (95% CLs) ranging from 0.013 (0.011-0.016) to 0.043 (0.033-0.057) mg Cu/l, and R. subcapitata (growth inhibition), 96-h IC50s from 0.071 (0.045-0.099) to 0.137 (0.090-0.174) mg Cu/l, were the most susceptible species. B. glabrata (lethality), 48-h LC50s from 0.179 (0.102-0.270) to 0.854 (0.553-1.457) mg Cu/l, and D. rerio (lethality), 48-h LC50s 0.063 (0.045-0.089), 0.192 (0.133-0.272) and 0.714 (0.494-1.016) mg Cu/l, were less susceptible than Daphnia to copper-based pesticides. Findings from the present study therefore suggest that increased levels of copper in water bodies is likely to adversely affect a variety of aquatic species.     

Size assessment via a visual signal in snapping shrimp

Snapping shrimp are highly aggressive decapod crustaceans, with large, asymmetric chelae. Body size determines the outcome of both inter- and intrasexual interactions. Both the body and chela sizes of mated pairs are correlated, but the body size correlation is significantly stronger. In competitive interactions between individuals of the same sex, larger individuals usually win. Because the size of the major chela is a function of body size in both males and females, chela size could be used to assess body size early in interactions, before engaging in more high risk behaviors. To determine whether the major chela is used in size assessment, I presented shrimp with isolated chelae. Male snapping shrimp responded aggressively to isolated chelae when they were fixed open in a display posture, and the degree of aggressive response depended on the relative size of the chela. These data provide direct experimental evidence for the use of a visual signal in size assessment. Females, in contrast, responded aggressively to both the open and closed chela, and their responses did not depend on relative size. This sex difference in response may be due to differences in the value of certain resources, such as shelters, to males and females: females may be more willing to respond aggressively regardless of the apparent size of their opponent, in order to acquire more reliable information regarding size, motivation or fighting ability. Received: 30 December 1994/Accepted after revision: 14 August 1995     

Colony size affects division of labour in the ponerine ant<Emphasis Type="Italic"> Rhytidoponera metallica</Emphasis>

In theory, larger colonies of social insects should have greater colony organisation. While inter-specific comparative studies provide support for this idea, there is little direct intra-specific evidence. We investigated differences in task specialisation between large (>450 workers) and small (<80 workers) colonies of the ponerine ant Rhytidoponera metallica. Observations of individually marked young or old workers revealed greater task specialisation in large colonies. Age polyethism was detected in large but not small colonies. In large colonies, old workers spent significantly more time foraging than young workers did, while young workers spent more time caring for brood. In small colonies, young and old workers spent a similar amount of time foraging and caring for brood. This difference in task allocation patterns in large and small colonies was associated with a difference in contact rates between workers. Workers in small colonies have a lower contact rate between nestmates and a greater variability in time between contacts than workers from large colonies.     

“I feel your pain”: A critical review of organizational research on empathy

Empathy, a multidimensional construct comprised of cognitive, affective, and behavioral dimensions, has been advanced as a critical predictor of prosocial behavior and effectiveness in the workplace. However, despite organizational interest in empathy, there is a lack of consensus on what empathy is, how empathy should be measured, and how empathy research can meaningfully contribute to our understanding of organizational behavior. This paper aims to provide a roadmap for researchers and practitioners interested in empathy in the workplace. We first provide an updated overview of the state of the broader multidisciplinary literature on empathy. On the basis of this literature, we outline the three dimensions of empathy, discuss the distinctions between state/trait and observer/judged empathy, and compare empathy with related constructs. This integrated multidimensional conceptualization provides the basis for our critical review and recommendations. We review the organizational research on empathy (1983–2018), identifying critical issues with how empathy has been conceptualized, measured, and designed, and offer practical recommendations for the advancement of organizational research on empathy. We conclude by highlighting two fundamental questions: (a) is empathy associated with important outcomes of interest to organizations and employees, and (b) can empathy be changed, and if so, how?     

Vegetation Placement for Summer Built Surface Temperature Moderation in an Urban Microclimate

Urban vegetation can mitigate increases in summer air temperature by reducing the solar gain received by buildings. To quantify the temperature-moderating influence of city trees and vine-covered buildings, a total of 13 pairs of temperature loggers were installed on the surfaces of eight buildings in downtown Toronto, Canada, for 6 months during the summer of 2008. One logger in each pair was shaded by vegetation while the other measured built surface temperature in full sunlight. We investigated the temperature-moderating benefits of solitary mature trees, clusters of trees, and perennial vines using a linear-mixed model and a multiple regression analysis of degree hour difference. We then assessed the temperature-moderating effect of leaf area, plant size and proximity to building, and plant location relative to solar path. During a period of high solar intensity, we measured an average temperature differential of 11.7 °C, with as many as 10–12 h of sustained cooler built surface temperatures. Vegetation on the west-facing aspect of built structures provided the greatest temperature moderation, with maximum benefit (peak temperature difference) occurring late in the afternoon. Large mature trees growing within 5 m of buildings showed the greatest ability to moderate built surface temperature, with those growing in clusters delivering limited additional benefit compared with isolated trees. Perennial vines proved as effective as trees at moderating rise in built surface temperature to the south and west sides of buildings, providing an attractive alternative to shade trees where soil volume and space are limited.     

Quantifying iridescent coloration in animals: a method for improving repeatability

Quantification of animal colors is important to a variety of fields of research, especially those dealing with visual communication and sexual selection. Most animal colors are easily measured using well-established spectrophotometric techniques. However, the unique characteristics of iridescent colors present particular challenges and opportunities to quantify novel color metrics. Due to the fine-scale angle dependence of iridescent coloration, color metrics, such as hue and brightness, must be measured using methods that allow for repeatable comparison across individuals (e.g., by carefully controlling and measuring viewing geometry). Here, we explain how the optical characteristics of iridescent colors should be considered when developing measurement techniques, describe the pitfalls of some commonly used techniques, and recommend improved methods and metrics (angular degree of color change and breadth of reflectance) for quantifying iridescent color. In particular, most studies of iridescent birds to date have used less than ideal procedures and have not provided repeatability estimates for their methods. For example, we demonstrate here that measuring coloration from overlapping patches of iridescent feathers may be problematic, and we argue against methods that do not carefully control viewing geometry. We recommend measuring iridescence at maximal reflectance angles using an apparatus that allows for sample rotation, and we compare this technique to some other commonly used methods using iridescent gorget and crown feathers from Anna’s hummingbirds (Calypte anna). Our apparatus allows for the quantification of angular color change, and we found that maximal reflectance measurements using single feathers are highly repeatable both within feather samples and among samples within an individual.     

Leachability of automotive shredder residues burned in a fluidized bed system

This paper presents the results of the study of a combustible fraction of automotive shredder residues (CASRs) and the corresponding ashes generated by combustion on a fluidized bed pilot with the aim to understand the influence of thermal treatment regarding properties for final disposal, such as landfilling. The chemical composition was evaluated and the leachability behaviour of ashes and CASR was investigated using the three more commonly used tests: the European Standard EN 12457, the US TCLP-EPA 1311 and the Dutch availability test EA NEN 7371. Different results were obtained depending on the specific conditions of the methods employed. It was found that both the CASR and the ashes contained large amounts of toxic metals and other undesirable elements, such as Cl and S. For the CASR, in addition to the leachability of organic matter above the limit set for hazardous materials, the release of heavy metals, either under alkaline and acidic conditions was significant, revealing the serious risks associated to the landfilling practices still being undertaken worldwide. Release of organic matter from ashes was insignificant, but solubility of sulphates increased and chlorides exceed the hazardous limits in the case of fly ashes. Toxic metals were found to leach from the ashes only under acidic conditions, except Pb and Cu which also leached from finer ashes at alkaline pH. Cr also leached from ashes at alkaline pH values. Both the Dutch availability and TCLP revealed much higher leaching intensities than the European Standard due to the acidity of leachants. However, it was found that ashes may be more resistant to acidification because they exhibit much higher acid neutralization capacity (ANC) than the untreated CASR. The study undertaken shows that thermal valorisation of the combustible fraction of ASR may avoid the risks associated with their landfilling; however, care has to be taken with the ashes because they also behave as hazardous residues. Although, the mass reduction provided by thermal treatment may make landfilling less expensive, a more profitable reutilization of the ashes should be developed.     

Prenatal diagnosis of cleft lip and/or palate: What do we tell prospective parents?

Cleft lip and/or palate (CL/CP) is the most common congenital craniofacial anomaly and parents often ask, “how did this happen?” Patients and families may benefit from access to a multidisciplinary team (MDT) from prenatal diagnosis into early adulthood. Multiple factors can contribute to the development of a cleft. We discuss the epidemiology and risk factors that increase the likelihood of having a newborn with a cleft. The purpose of this article is to review the prenatal investigations involved in the diagnosis and workup of these patients in addition to postpartum treatment, prognostic factors, and counseling families regarding future recurrence risk.