Brown rats (<Emphasis Type=Italic>Rattus norvegicus</Emphasis>) in urban ecosystems: are the constraints related to fieldwork a limit to their study?

Nowadays, the majority of human beings live in urban ecosystems, with this proportion expected to continue increasing in the future. With the growing importance of urban rat-associated issues (e.g. damages to urban infrastructures, costs of rat-control programs, rat-associated health risks), it is becoming indispensable to fill the identified gaps in knowledge on the urban brown rat regarding, among others, its density, home range, genetic structure, and infectious status. In this context, live-trapping is a crucial prerequisite to any scientific investigation. This paper assesses the main constraints and challenges regarding the urban field and describes the major steps to be considered when planning research on urban rats. The primary challenges are i) the characterization of the urban experimental unit; ii) the choice of a trapping design: the use of live-trapping in capture-mark-recapture design, in association with modern statistics, is highly recommended to answer ecological questions (although these methods, mostly developed in natural ecosystems, need to be implemented for the urban field); iii) the potential ethical considerations with regard to animal welfare and field-worker safety; iv) the building of mutually-beneficial collaborations with city stakeholders, pest control professionals, and citizens. Emphasis must be put on communication to the public and education of field-workers. One major need of modern urban rat research is a peer-validated field methodology allowing reproducibility, repeatability, and inference from urban field studies and enabling researchers to answer long-standing key questions about urban rat ecology.     

Revenue Mobilisation in Sub‐Saharan Africa: Challenges from Globalisation I – Trade Reform

This is the first of two articles evaluating the nature and extent of, and possible responses to, two of the central challenges that globalisation poses for revenue mobilisation in sub‐Saharan Africa: trade liberalisation, and corporate tax competition. Both articles use a new dataset with the features needed to address these issues meaningfully: a disentangling of tariff from commodity tax revenue, and a distinction between resource‐related and other revenues. This first article describes that dataset, and provides a broad picture of revenue developments in the region between 1980 and 2005. Countries’ experiences have varied, but the overall picture is of non‐resource revenues having been essentially stagnant. Within this, however, and with exceptions, reductions in trade tax revenue have been largely offset by increased revenue from domestic sources.     

Evaluation of strategies to mitigate contagion spread using social network characteristics

Computer simulation is an effective tool for assessing mitigation strategies, with recent trends concentrating on agent-based techniques. These methods require high computational efforts in order to simulate enough scenarios for statistical significance. The population individuals and their contacts determined by agent-based simulations form a social network. For some network structures it is possible to gain high accuracy estimates of contagion spread based on the connection structure of the network, an idea that is utilized in this work. A representative social network constructed from the 2006 census of the Greater Toronto Area (Ontario, Canada) of 5 million individuals in 1.8 million households is used to demonstrate the efficacy of our approach. We examine the effects of six mitigation strategies with respect to their ability to contain disease spread as indicated by pre- and post-vaccination reproduction numbers, mean local clustering coefficients and degree distributions. One outcome of the analysis provides evidence supporting the design of mitigation strategies that aim to fragment the population into similarly sized components. While our analysis is framed in the context of pandemic disease spread, the approach is applicable to any contagion such as computer viruses, rumours, social trends, and so on.     

ECONOMIC DETERMINANTS OF THE TIMING OF PREFERENTIAL TRADE AGREEMENT FORMATIONS AND ENLARGEMENTS

Preferential trade agreements (PTAs) have proliferated over the past 60 years. While a small number of recent studies have examined empirically the economic determinants of the likelihood of a pair of countries having a PTA, this study explains empirically the timing of all PTA formations and enlargements from 1950 through 2006 using duration analysis. Our main and novel goal is to predict (in‐ and out‐of‐sample) a substantive share of these 1,560 PTA events using a parsimonious model with mainly economic variables, taking selection dynamics into account. Our analysis reveals that we can predict correctly in‐sample the actual year of entry into force for 26% of the 1,560 bilateral PTA formations/enlargements in the period 1950–2006 among 10,518 pairings of 146 countries using only a few economic and political variables. Moreover, we can predict correctly in‐sample 57% of these PTA events within a 10‐year window leading up to the event using this model. The model also performs well out‐of‐sample for the near term (82%), but not if the out‐of‐sample period is very long. We conclude with an evaluation of the model's ability to predict the timing of the North American Free Trade Agreement, the European Union's formation and enlargements, and the model's ten most likely post‐2006 PTA events. (JEL F14, F15)     

Consumption,time and the environment

This paper combines a time-allocation approach with a model of economic dynamics, based on the accumulation of human capital, and constrained by the environment. Consumption is modelled as an activity, combining time and commodities, and embedded in the environment. An economic interpretation for a structural shortage of time in consumption activities is suggested. It is also shown, that the environmental embeddedness of consumption can contribute to restoring more balanced proportions of time and commodities in consumption. In a dynamic setting the paper also discusses the effects of discounting on consumption, the use of time and the environment. It is found that, within a certain range of the rate of discount, a ‘discounting trap’ may arise, significantly depressing the level of environmental quality in the long-run equilibrium.     

Integral packing of branchings in capacitaded digraphs

We prove that an algorithm of Schrijver, that computes an integral packing of branchings in a capacitaded digraph, produces a packing with no more than \(m + r - 1\) different branchings, where \(m\) is the number of arcs, and \(r\) the number of root-sets of the digraph.     

Your work may be killing you! Workaholism,sleep problems and cardiovascular risk

This study tests the relationships between workaholism (i.e. working excessively and compulsively), sleep problems and cardiovascular risk in 537 employees from five Spanish hospitals. Four types of worker (i.e. workaholics, positive workers, compulsive workers and hard workers) were distinguished, and their health indicators were compared. The results showed that workaholics experienced significantly more sleep problems (i.e. morning tiredness, sleeping while driving and sleeping fewer hours both on weekdays and at weekends, with poorer quality), had higher relative risk scores, and consumed more caffeine and alcohol than the other patterns of worker (positive, compulsive and hard workers). Further analyses revealed that sleep problems fully mediated the relationship between workaholism (i.e. working excessively and compulsively) and cardiovascular risk. The study emphasizes the fact that being a workaholic might be a significant risk factor for having sleep problems and cardiovascular disease.     

A DIRECT TEST OF THE BUFFER‐STOCK MODEL OF SAVING

Recent models with liquidity constraints and impatience emphasize that consumers use savings to buffer income fluctuations. When wealth is below anoptimal target, consumers try to increase their buffer stock of wealth by saving more. When it is above target, they increase consumption. This important implication of the buffer stock model of saving has not been subject to direct empirical testing. We derive from the model an appropriate theoretical restriction and test it using data on working‐age individuals drawn from the 2002 and 2004 Italian Surveys of Household Income and Wealth. One of the most appealing features of the survey is that it has data on the amount of wealth held for precautionary purposes, which we interpret as target wealth in a buffer stock model. The test results do not support buffer stock behavior, even among population groups that are more likely, a priori, to display such behavior. The saving behavior of young households is instead consistent with models in which impatience, relative to prudence, is not as high as in buffer stock models. (JEL: D91)     

Problematizing Fatherhood: Impact of the Intact Family Ideal on Fathers in Hong Kong

Discourses that uphold the superiority of the married two-parent family ignore the findings that parental practice rather than family form matters. Few studies have examined the impact of the hegemonic notion of the intact family on fathers. Based on data from participant observation in a men's center in Hong Kong and in-depth interviews with 20 members, this article analyzes the implied hegemony of the intact family in the new manhood proposed by the center. Results show intact family hegemony led fathers to endure bitter and violent marriages and that divorced fathers felt a sense of failure and guilt toward their children. I argue that the fatherhood movement should abandon the obsession with the intact family and promote involved fathering for all families.