Methodology for the Calculation of Annualized Incremental Risks in Systems of Dams

In the past few years, the field of dam safety has approached risk informed methodologies throughout the world and several methodologies and programs are appearing to aid in the systematization of the calculations. The most common way of implementing these calculations is through the use of event trees, computing event probabilities, and incremental consequences. This methodology is flexible enough for several situations, but its generalization to the case of systems of several dams is complex and its implementation in a completely general calculation methodology presents some problems. Retaining the event tree framework, a new methodology is proposed to calculate incremental risks. The main advantage of this proposed methodology is the ease with which it can be applied to systems of several dams: with a single risk model that describes the complete system and with a single calculation the incremental risks of the system can be obtained, being able to allocate the risk of each dam and of each failure mode. The article shows how both methodologies are equivalent and also applies them to a case study.     

Water Price Regulation: A Review of Portuguese Tariff Recommendations

The context of severe economic crisis and financial constraints has reinforced existing pressures on services considered to be of community interest by public authorities and therefore subject to specific public service obligations. This is the case of the water industry, with increased pressure for full cost recovery and on the use of prices as a tool for the management of water resources in EU countries. The Portuguese situation confirms these trends and the expected increases in water tariffs raise special concerns. In these volatile times it is particularly relevant to analyze the management and regulatory work of the Portuguese Water and Waste Services Regulation Authority, which recently acquired extended powers in pricing regulation. Findings reveal a complexity of tariff schemes in Portuguese municipalities, with tariff recommendations being a clear commitment to selected economic theory proposals and the harmonization of price schemes in the heterogeneous water utilities national context.     

Dynamic evolution of alliance portfolios

This research advances in the conceptualization and the operationalization of the factors or microdynamics that determine the choice of partners. Most of the literature in this area of research has centered on the individual alliance without taking into account the set of alliances that a firm makes. This research applies a holistic approach, analyzing the set of alliances as a whole and points to the factors related to alliance portfolios that affect the choice of partners. The authors propose a longitudinal model that allows us to analyze the evolution of interorganizational networks. A Simulation Investigation for Empirical Network Analysis (SIENA) has been applied to a sample of 229 firms, analyzing 10,556 strategic alliances established between them over a 12 year period. The results show that certain factors over which managers exercise a degree of control (deliberate endogenous microdynamics) exert significant influences on the choice of partners by the focal actor and thereby on the dynamic configuration of alliance portfolios.     

Macroeconomic conditions, institutional factors and demographic structure: What causes welfare caseloads?

Some of the possible determinants of changes observed in welfare caseloads are analysed in this study. The paper attempts to explain variations in welfare caseloads on the basis of four different factors: macroeconomic conditions, interactions with other income maintenance programmes, changes in the programme's parameters and changes in the demographic structure. Different models are tested by applying time series techniques. The data employed are of an administrative nature and cover the whole period that the Madrid programme has been in operation. The results show that the effects of both unemployment and institutional variables are strong and significant. Macroeconomic effects on caseloads could be offset or reinforced by changes in unemployment protection and reforms of the programme's parameters. The significant effects found for the share of lone-parent applicants also show that demographic shifts could shape the trends of welfare rolls regardless of the changes in unemployment or the implementation of institutional reforms. The authors would like to thank Juan Gabriel Rodríguez, Minoru Kunizaki, Miguel Angel Malo and three anonymous referees for their comments and suggestions. Financial and technical support from the Spanish Institute for Fiscal Studies, the Inter-ministerial Commission on Science and Technology (SEC 2001-0746) and the Social Services Department of the Madrid Government is also gratefully acknowledged. Responsible editor: Christian Dustmann.     

Violence Exposure and Drug Use in Central American Youth: Family Cohesion and Parental Monitoring as Protective Factors

Associations between witnessing serious violence and drug use, and the protective influences of family cohesion and parental monitoring, were investigated among 9,840 adolescents (50.5% female, M age=15.29 years, SD=1.76) living in Panama and Costa Rica. After accounting for demographics and parental and sibling substance use, witnessing serious violence was associated with greater drunkenness, tobacco use, number of illicit drugs used, and problems with drugs and alcohol. In every analysis, exposure to violence was associated with more drug use, while family cohesion and parental monitoring attenuated risk. Further, family cohesion and parental monitoring exerted a protective‐stabilizing effect on number of illicit drugs used and on problems with drugs and alcohol. There were few interactions with age. Implications for prevention are discussed.     

Public Life and Globalization as Cultural Vision*

Dans cette étude, nous examinons les répercussions sociales de la mondialisation dans une perspective culturelle. Notre analyse porte sur le conflit qui existe entre le discours sur la mondialisation et les priorités locales, entre les droits de l'individu et les engagements des pouvoirs publics ainsi que sur la difficulté de trouver de nouveaux points d'ancrage de l'identité culturelle dans un contexte où les frontières territoriales entre les États s'effacent et où les idées de progres, de modernité et d'évolution se sont érodées. Ces traits accompagnent la transformation amorcée dans le cadre des relations complexes et hégémoniques qui caractérisent aujourd'hui le système mondial. Ce conflit et ces problèmes demeurent un axe fondamental du débat politique. Nous suggérons que les différentes formes de participation se traduisent de diverses façons dans le champ de l'expression politique et dans Interprétation des exigences sociales et des droits, et influent sur la vie publique à la veille du XXI^esiécle. This article explores the social implications of globalization as cultural vision. Discussion bears upon the tension between the discourse of globality and local priorities, of individual rights and public commitments, and upon the problems of finding new ways for grounding identities as territorial state boundaries are weakened and the ideas of progress, modernity and evolutionary perspectives are eroded as part of a process of change initiated in the developed and hegemonic settings of the world system. It is claimed that these tensions and problems remain a crucial axis of political debate. It is suggested that different patterns of participation meld in manifold ways into recreated forms of political will and varied interpretations of social claims on and rights to affect the shaping of public life at the turn of the century.     

A Semi-parametric Bayesian Analysis of Survival Data Based on Lévy-driven Processes

In the presence of covariate information, the proportional hazards model is one of the most popular models. In this paper, in a Bayesian nonparametric framework, we use a Markov (Lévy-driven) process to model the baseline hazard rate. Previous Bayesian nonparametric models have been based on neutral to the right processes, which have a number of drawbacks, such as discreteness of the cumulative hazard function. We allow the covariates to be time dependent functions and develop a full posterior analysis via substitution sampling. A detailed illustration is presented.     

Identifying Preferences for Conditional Cooperation Using Individual Beliefs

The relationship between contributions and elicited beliefs in a repeated two-person public good experiment is modeled with the help of a parsimounious random-utility function that allows for conditionally cooperative, opportunistic, and altruistic patterns of behavior. Under standard assumptions, a latent-class mixed logit specification with three sub-populations is shown to capture well heterogeneity in individual contribution levels over time, while also accomodating for different degrees of heteroscedasticity. The estimation results are consistent with the conjecture that the majority of players in public goods games are strongly conditional cooperators, with smaller fractions of the population leaning to opportunistic or altruistic behavior.     

Size does matter: Passive sampling in urban parks of a regional bat assemblage

Urban Ecosystems - We studied the occurrence of bats in urban parks in the city of Madrid (Spain), and the resulting patterns were compared with bat occurrence in the surrounding region. In this...