Vertices with the Second Neighborhood Property in Eulerian Digraphs

The Second Neighborhood Conjecture states that every simple digraph has a vertex whose second out-neighborhood is at least as large as its first out-neighborhood, i.e. a vertex with the Second Neighborhood Property. A cycle intersection graph of an even graph is a new graph whose vertices are the cycles in a cycle decomposition of the original graph and whose edges represent vertex intersections of the cycles. By using a digraph variant of this concept, we prove that Eulerian digraphs which admit a simple cycle intersection graph have not only adhere to the Second Neighborhood Conjecture, but that local simplicity can, in some cases, also imply the existence of a Seymour vertex in the original digraph.Comment: This is the version accepted for publication in Opuscula Mathematic

Job-related stress and burnout

Occupational stress is a topic of substantial interest to organizational researchers and managers, as well as society at large. Stress arising from work conditions can be pervasive and significant in its impact on individuals, their families and organizations. There is also a widespread belief that management of job stress is a key factor for enhancing individual performance on the job, hence increasing organizational effectiveness. Sethi and Schuler 1984 outlined four major reasons why job stress and coping have become prominent issues: a concern for individual employee health and well-being; b the financial impact on organizations including days lost due to stress-related illness; c organizational effectiveness; and d legal obligations on employers to provide safe and healthy working environments

The Economics of Pollution: Policy, Productivity, and the Structure of Road Networks

Air pollution impacts economic activity, and economic activity creates air pollution. Understanding this endogenous nexus is critical as any policy designed to affect one will inevitably affect the other. My research explores both sides of this nexus. Specifically, I identify the economic effects from the implementation of an international climate agreement (the Kyoto Protocol); I determine the impact of air pollution on physical productivity and determine which pollutants are responsible for this effect; and I link urban form to vehicular emissions via the structure of road networks. The first chapter of this dissertation studies the impact of the Kyoto Protocol on the cement manufacturing industry. The Kyoto Protocol is an international agreement signed in 1997 to reduce emissions of carbon dioxide and mitigate the consequences of global climate change. Early studies of the effectiveness of the Kyoto Protocol have attributed it to approximately a 7-10\% reduction in global carbon dioxide emissions compared to a ``business as usual\u27\u27 outcome. Given the carbon intensity of cement manufacturing, I examine the impact of the Kyoto Protocol on cement manufacturing output and carbon dioxide emissions. Using an instrumental variables difference-in-differences approach, I find that nations with binding emissions targets under the Kyoto Protocol saw a 5\% reduction in both cement manufacturing and carbon dioxide emissions from cement manufacturing compared to other nations. Based on the relative magnitude of these effects, it appears that the Kyoto Protocol may have led to technological innovation in cement manufacturing. Using data on carbon intensities for cement manufacturing, I support this notion and find further evidence that it fostered diffusion of existing, cleaner technologies from relatively more developed nations during the first phase, and technical innovation by these nations during the second phase. By examining the effect on net cement imports, I do not find evidence that the reduction in carbon dioxide emissions resulted in carbon leakage. Using estimates of the social cost of carbon from the economics literature and the results from this paper, back of the envelope calculations suggest that the Kyoto Protocol had an economic gain of \$7.4 billion from the reduction of carbon dioxide emissions from cement manufacturing alone. The second chapter of this dissertation studies the impact of air pollution on ultramarathon performance. Air pollution is known to lower worker productivity in myriad settings. However, causal inference studies using reliable air pollution data to study the effect of air pollution on physical productivity in outdoor settings over periods of time comparable to a workday are sparse, especially using US data. Furthermore, studies identifying the specific pollutant(s) responsible for this effect are even less common. By using ultramarathon race performances as a measure of physical productivity and spatiotemporal variation in ambient pollution levels, I find that particulate matter (PM10) is the key pollutant responsible for decreasing consistent, metered physical productivity in outdoor settings. In addition to this, this chapter also extends the existing literature by suggesting a distinction in which pollutants affect physical productivity along an aerobic/anaerobic divide, thereby explaining part of the existing divide in the air pollution and physical productivity literature. I also provide the first evidence of gender-based differences in the effects of air pollution on physical productivity. The third chapter of this dissertation studies the relationship between road network structure and air pollution. Transportation is one of the primary contributors to local pollution stocks and flows. Thus, I consider how the structure of local road networks and the accompanying vehicular emissions might affect pollution stocks and flows. I present a pollution stock and flow model building on the Fundamental Law of Road Congestion that considers the impact of road network structure, and use this to generate hypotheses for how the structure of road networks should affect pollution stocks and flows. The main avenues for these effects are via traffic congestion and the opportunity cost of driving. Using topological indices to describe the structure of road networks, I test these hypotheses via a Hausman-Taylor approach using a measure of urban form as an instrument to address the endogeneity of the network structure. I find evidence supporting the hypotheses that better connected road networks, i.e., those with fewer bottlenecks and which generally allow for more efficient traversal, lead to lower levels of pollution stocks and flows. I also find evidence that drivers adapt to more circuitous road networks with lower levels of driving. These mechanisms are confirmed by regressing measures of congestion and the opportunity cost of driving against the topological indices

The limitations of market driven sustainability: The case of environmental management systems for food production in Australia.

Environmental Management Systems (EMSs) address environmental risks in supply chains and certification of environmental claims. Governments supporting EMSs have encouraged producers to respond to anticipated consumer environmental concerns. Attempts at implementing EMSs have rarely been in direct response to market demand but are usually farmer organisation driven - to forestall increased regulation. In Australia, consumer demand for foods produced to environmentally sustainable standards is minimal because consumers don't believe these products offer special benefits. EMS implementation is expensive and onerous; and the products require a market premium. Food consumers have difficulty differentiating the terms organic, environmentally-friendly, and sustainably-produced in food labelling.EMS, environmental marketing, sustainable food production, eco-labelling, Environmental Economics and Policy,

Garfield County resident perceptions of the indirect effects of the 2002 Winter Olympics

This study examined rural resident perceptions of a nearby mega-event. Tourism leaders can gauge resident perceptions and thereby plan development in conjunction with the local people, not in spite of them; It is anticipated that the 2002 Winter Olympics will have some impact on Garfield County, Utah. Using social exchange theory, the study sought to better understand public sentiment regarding the upcoming mega-event. Certain resident values were examined in relation to tourism; The results show that some residents perceive that the Olympics will bring opportunities, but most residents do not anticipate any impact from the event. Residents who are economically dependent upon tourism and those who participate in outdoor activities support the Olympics. Environmentally conscious residents are opposed to the Olympics. Most residents indicate that they do not support or oppose the event

Exploring the opportunities for sustainable food labelling : a supply chain perspective

This study examines supply chain members&rsquo; beliefs regarding the opportunities to develop foods produced under an \u27eco-friendly\u27 label. The study involved in-depth interviews with 17 Australian senior managers in food organisations who have marketing responsibilities and who have expert product and consumer knowledge (c.f. Clift and Wright 2000, Peattie 2000). The findings suggest that respondents have widely different beliefs regarding the meaning of \u27eco-friendly\u27 and believe that claims regarding \u27eco-friendly\u27 characteristics are difficult to substantiate. They further suggested that \u27eco-friendly\u27 considerations are not a major influencer of consumer food purchase decisions at present and thus \u27eco-friendly\u27 production was not a strategic focus of their companies. Respondents felt that \u27eco-friendly\u27 labelling would not be successful until consumers&rsquo; value \u27eco-friendly\u27 food attributes.<br /