Homophily and Agency: Creating Effective Sustainable Development Networks

Community networks are self-organized groupings that form for many different reasons. Some networks, connected mainly through bonding ties, are based on personal interests and relationships; others, based mainly on bridging ties, centre around broader interests. These networks form to create collective agency for engaging with social, environmental, and other issues through the concentration of social capital. The multi-scaled and evolutionary nature of sustainable development issues requires that community groups dedicated to engaging with such issues be particularly diverse, resilient, and flexible. As such, they must build a large number of bridging ties leading to external resources and limit the potential for bonding ties to impose constraining norms upon the group. Over time, however, volunteer groups tend towards a state of homophily, the tendency of groups to form from similar actors and then become more similar with time. This tendency leads to a decrease in the number of the bridging ties that help to provide group agency. Homophily must be actively recognized within community sustainable development groups if they are to remain effective over the long term. This paper suggests methods to prevent and control group homophily drawn from experience in forming small, time-limited sustainable development networks. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue     

Effects of self-esteem and gender on goal choice

The relationship between enduring or personality characteristics and goal choice has been of considerable theoretical, but little empirical interest in recent years. From an expectancy value perspective, we addressed the impact of self-esteem and gender on choice of goal difficulty level. As predicted, esteem and gender made significant contributions to the prediction of goal choice. The implications of these findings for future research in organizational settings, goal setting theory, and the relationship between goals and tasks are discussed.     

Multiphase transfer processes in waste rock piles producing acid mine drainage: 2. Applications of numerical simulation

Acid mine drainage (AMD) results from the oxidation of sulfides, mainly pyrite, present in mine wastes, either mill tailings or waste rock. This is the second of two papers describing the coupled physical processes taking place in waste rock piles undergoing AMD production. Since the oxidation of pyrite involves the consumption of oxygen and the production of heat, the oxidation process initiates coupled processes of gas transfer by diffusion and convection as well as heat transfer. These processes influence the supply of oxygen that is required to sustain the oxidation process. This second paper describes a numerical simulator used to represent the interaction of these coupled transfer processes. Numerical simulations are applied to two large sites with extensive characterization programs and widely different properties and behavior that were described in the first paper. The South Dump of the Doyon mine in Canada is permeable and has a high pyrite oxidation rate, thus making temperature-driven air convection the main oxygen supply mechanism. The Nordhalde of the Ronnenberg mining district in Germany contains lower permeability material which is less reactive, thus leading to a more balanced contribution of gaseous diffusion and convection as oxygen supply mechanisms. Overall, simulations allow a coherent representation of the conditions monitored within the waste rock piles and the confirmation of their physical properties. Conceptual simulations are also carried out to illustrate the potential effect of border membranes and layered co-mingling as mitigation methods used to control AMD production in either active or future waste rock piles.     

Quantifying construction and demolition waste: An analytical review

Quantifying construction and demolition (C&D) waste generation is regarded as a prerequisite for the implementation of successful waste management. In literature, various methods have been employed to quantify the C&D waste generation at both regional and project levels. However, an integrated review that systemically describes and analyses all the existing methods has yet to be conducted. To bridge this research gap, an analytical review is conducted. Fifty-seven papers are retrieved based on a set of rigorous procedures. The characteristics of the selected papers are classified according to the following criteria - waste generation activity, estimation level and quantification methodology. Six categories of existing C&D waste quantification methodologies are identified, including site visit method, waste generation rate method, lifetime analysis method, classification system accumulation method, variables modelling method and other particular methods. A critical comparison of the identified methods is given according to their characteristics and implementation constraints. Moreover, a decision tree is proposed for aiding the selection of the most appropriate quantification method in different scenarios. Based on the analytical review, limitations of previous studies and recommendations of potential future research directions are further suggested.     

Driving self-restriction in high-risk conditions: how do older drivers compare to others?

Introduction

Many older drivers self-restrict or avoid driving under high-risk conditions. Little is known about the onset of driving self-restrictions or how widespread self-restrictions are among drivers of all ages.

Methods

The Second Injury Control and Risk Survey (ICARIS-2) was a nationwide cross-sectional, list-assisted random-digit-dial telephone survey from 2001 to 2003. National prevalence estimates and weighted percentages of those reporting driving self-restrictions were calculated. Multivariable logistic regression was used to explore associations between specific self-restrictions and age group, adjusting for other personal characteristics.

Results

More than half of all drivers reported at least one driving self-restriction. The most commonly reported restriction was avoidance of driving in bad weather (47.5%), followed by at night (27.9%) and on highways or high-speed roads (19%). A greater percentage of young adult women (18-24 years) reported self-restricting in bad weather compared to women in other age groups, and the percentage of drivers self-restricting at night, in bad weather, and on highways or high-speed roads increased steeply after age 64. We found that women, those in low income groups, and those who had driven low annual mileage were more likely to self-restrict.

Conclusions

In addition to assessing self-restrictions among older drivers, a new finding from our study is that self-restrictions are also quite prevalent among younger age groups. Driving self-restrictions may be better understood as a spectrum across ages in which drivers’ reasons for restriction change.

Impact on industry

Future research on the ability of driving self-restrictions to reduce actual crash risk and prevent injuries is needed.     

Factors influencing private and public environmental protection behaviors: results from a survey of residents in Shaanxi, China

Currently one of the largest and most rapidly developing countries, China also has some of the world's most severe environmental problems. China will most likely need to use all of the potential major strategies currently available to solve the country's huge environmental challenges, including promoting individual conservation behavior through educational campaigns and encouraging public environmental advocacy. This paper summarized the findings of a survey of 347 residents of Shaanxi province on environmental attitudes and behaviors. The survey found generally high levels of environmental knowledge and high recognition of the seriousness of environmental issues, moderate levels of individual actions supporting environmental resource conservation and low levels of public environmental behaviors, particularly for organized public advocacy. Further analysis indicated that the perceived importance of environmental protection is the most important factor influencing individual environmental resource conservation, but not public advocacy behaviors. Implications for environmental campaigns are discussed.     

Temporal and spatial variation in the δ<Superscript>15</Superscript>N and δ<Superscript>13</Superscript>C values of fish and squid from Alaskan waters

To test the hypothesis that stable isotope ratios from marine organisms vary, the δ¹⁵N and δ¹³C values from fish and squid collected in Alaskan waters were measured across years (1997, 2000, and 2005), seasons, geographic locations, and different size/age classes, and between muscle tissue and whole animals. Temporal, geographic, and ontogenetic differences in stable isotope ratios ranged from 0.5–2.5‰ (δ¹⁵N) to 0.5–2.0‰ (δ¹³C). Twenty-one comparisons of stable isotope values between whole organisms and muscle tissue revealed only four small differences each for δ¹⁵N and δ¹³C, making costly and space prohibitive collection of whole animals unnecessary. The data from this study indicate that significant variations of stable isotope values from animals in marine systems necessitates collection of prey and predator tissues from the same time and place for best interpretation of stable isotope analysis in foraging ecology studies.