QoS-Aware Middleware for Web Services Composition

The paradigmatic shift from a Web of manual interactions to a Web of programmatic interactions driven by Web services is creating unprecedented opportunities for the formation of online Business-to-Business (B2B) collaborations. In particular, the creation of value-added services by composition of existing ones is gaining a significant momentum. Since many available Web services provide overlapping or identical functionality, albeit with different Quality of Service (QoS), a choice needs to be made to determine which services are to participate in a given composite service. This paper presents a middleware platform which addresses the issue of selecting Web services for the purpose of their composition in a way that maximizes user satisfaction expressed as utility functions over QoS attributes, while satisfying the constraints set by the user and by the structure of the composite service. Two selection approaches are described and compared: one based on local (task-level) selection of services and the other based on global allocation of tasks to services using integer programming

Rational Asset Prices

The mean, co-variability, and predictability of the return of different classes of financial assets challenge the rational economic model for an explanation. The unconditional mean aggregate equity premium is almost seven percent per year and remains high after adjusting downwards the sample mean premium by introducing prior beliefs about the stationarity of the price-dividend ratio and the (non) forecastability of the long-term dividend growth and price-dividend ratio. Recognition that idiosyncratic income shocks are uninsurable and concentrated in recessions contributes toward an explanation. Also borrowing constraints over the investors' life cycle that shift the stock market risk to the saving middle-aged consumers contribute toward an explanation.

Using graphical models and multi-attribute utility theory for probabilistic uncertainty handling in large systems, with application to nuclear emergency management

Although many decision-making problems involve uncertainty, uncertainty handling within large decision support systems (DSSs) is challenging. One domain where uncertainty handling is critical is emergency response management, in particular nuclear emergency response, where decision making takes place in an uncertain, dynamically changing environment. Assimilation and analysis of data can help to reduce these uncertainties, but it is critical to do this in an efficient and defensible way. After briefly introducing the structure of a typical DSS for nuclear emergencies, the paper sets up a theoretical structure that enables a formal Bayesian decision analysis to be performed for environments like this within a DSS architecture. In such probabilistic DSSs many input conditional probability distributions are provided by different sets of experts overseeing different aspects of the emergency. These probabilities are then used by the decision maker (DM) to find her optimal decision. We demonstrate in this paper that unless due care is taken in such a composite framework, coherence and rationality may be compromised in a sense made explicit below. The technology we describe here builds a framework around which Bayesian data updating can be performed in a modular way, ensuring both coherence and efficiency, and provides sufficient unambiguous information to enable the DM to discover her expected utility maximizing policy

Consumption and habits : evidence from panel data

The purpose of this paper is to test for the presence of habit formation in consumption decisions using household panel data. We use the test proposed by Meghir and Weber (1996) and estimate the within -period marginal rate of substitution between commodities, which is robust to the presence of liquidity constraints. To that end, we use a Spanish panel data set in which households are observed up to eight consecutive quarters. This temporal dimension is crucial, since it allows us to take into account time invariant unobserved heterogeneity across households ("fixed effects") and, therefore, to investigate if the relationship between current and past consumption reflects habits or heterogeneity. Our results conf irm the importance of accounting for fixed effects when analyzing intertemporal consumption decisions allowing for time non-separabilities. Once fixed effects are controlled for and a proper set of instruments is used, the results yield supporting evidence of habit formation in the demand system of food at home, transport and services

Time and the Valuation of Environmental Resources

This paper considers the modeling strategies that have been used to incorporate time in revealed and stated preference methods for valuing environmental resources. After reviewing a subset of the economic models for describing time as an input to household production; time in creating habits and persistence in demand for particular services of environmental resources, and time as offering an opportunity for future consumption, the overview suggests that time has been used as a complement in production or consumption to marketed goods in each of these frameworks. The paper suggests two possible alternatives. This structure along with further restrictions to preferences or technology implies that there are other strategies for using revealed preference data to measure the economic value of changes in environmental quality.

Dynamic Elite Partisanship: Party Loyalty and Agenda Setting in the U.S. House

Legislators and legislative parties must strike a balance between collective and member-level goals. While there are legislative and reputational returns to co-ordinated behavior, partisan loyalty has a detrimental effect on members’ electoral success. This article argues that members and parties navigate these competing forces by pursuing partisan legislation when the threat of electoral repercussions is relatively low – when elections are distant. This study tests our theory by examining US House members’ likelihood of voting with their party on both partisan and non-divisive votes during the course of the election cycle in order to assess whether members strategically alter their levels of party loyalty as elections approach. It also explores whether majority parties strategically structure the agenda according to variation in members’ electoral constraints. This approach allows elite partisanship to follow a dynamic process, which is referred to here as dynamic elite partisanship. The results demonstrate that as elections approach, members are less likely to cast party votes, and parties are less inclined to schedule votes that divide the parties. At the same time, the study finds no evidence of strategic variation in members’ voting behavior on broadly consensual votes with election proximity

Female labor supply and the demand for housing

female workers;labour supply;housing

Unobserved Heterogeneity and Intertemporal Nonseparability: Evidence from Consumption Panel Data

In this paper we analyze the importance of intertemporal non-separabilities for consumption decisions using household data. We follow the test suggested by Meghir and Weber (1996), so we exploit the variability of the within-period marginal rate of substitution (MRS) between commodities. We also check for the presence of liquidity constraints by comparing the results obtained from theMRS to those of the Euler equations. For that purpose, we use a Spanish data set in which households are observed up to eight consecutive quarters. This length of the temporal dimension is crucial, since it allows both to account for the dynamics of consumption in the preferences as well as to control for time invariant unobserved heterogeneity across households. Our results confirm the importance of accounting for fixed effects when analyzing intertemporal consumption decisions allowing for time non-separabilities. Once we control for fixed effects and use the adequate set of instruments we do not find evidence of misspecification and the results yield supporting evidence of habit formation.Consumption, panel data, unobserved heterogeneity, habits, durability