An approximation algorithm for a general class of parametric optimization problems

Journal of Combinatorial Optimization - In a (linear) parametric optimization problem, the objective value of each feasible solution is an affine function of a real-valued parameter and one is...     

Figuren der reflektierten Improvisation in der sozialp?dagogischen Jugendberatung

Zusammenfassung In dem Aufsatz wird untersucht, was ungeplante und unplanbare Ereignisse für den Bereich der sozialp?dagogischen Jugendberatung bedeuten. Zun?chst wird erl?utert, inwiefern sozialp?dagogisches Beratungshandeln stets Elemente der Improvisation in sich birgt. Es folgen Analysen zur Frage, wie das blo?e Improvisieren zum reflektierten Improvisieren qualifiziert werden kann. Abschlie?end wird dargelegt, welche Handlungsfiguren durch die reflektierte Improvisation in der sozialp?dagogischen Beratung entstehen.

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The author analyses the meaning of not planed and impossible to plan events in the field of social pedagogical counselling of young people. As a first step he describes how far the social pedagogical counselling always includes elements of improvisation. An analysis of the question how norma improvisation could be qualified as reflective improvisation follows. Finally the authors shows which forms of acting emerge using the reflected improvisation in the social pedagogical counselling.

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Stefan Danner, Dr. phil., Professor für Erziehungswissenschaft an der Hochschule für Technik, Wirtschaft und Kultur Leipzig.

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Arbeitsschwerpunkte: Bildungstheorie, Didaktik der Elementarp?dagogik, Jugendarbeit und Erwachsenenbildung, Methoden der Evaluationsforschung.     

Modeling asset returns with alternative stable distributions

In the 1960's Benoit Mandelbrot and Eugene Fama argued strongly in favor of the stable Paretian distribution as a model for the unconditional distribution of asset returns. Although a substantial body of subsequent empirical studies supported this position, the stable Paretian model plays a minor role in current empirical work.

While in the economics and finance literature stable distributions are virtually exclusively associated with stable Paretian distributions, in this paper we adopt a more fundamental view and extend the concept of stability to a variety of probabilistic schemes. These schemes give rise to alternative stable distributions, which we compare empirically using S&P 500 stock return data. In this comparison the Weibull distribution, associated with both the nonrandom-minimum and geometric-random summation schemes dominates the other stable distributions considered-including the stable Paretian model.     

The use and effectiveness of top executive dismissal

We provide a systematic assessment of the empirical evidence on the use and effectiveness of top executive dismissal as a governance and performance improvement mechanism. Our results suggest that poor individual and firm performance significantly increase the likelihood of executive dismissal. A strong power base might help under-performing top executives to extend their tenure in office, but effective ownership and governance structures can provide a counterweight to such entrenchment behaviors. However, our review casts doubt on the effectiveness of top executive dismissal as a means to enhance future firm performance: employing meta-analytical techniques we show that, although the dismissal announcement leads to positive abnormal returns, it has no significant effect on long-term measures of firm performance. On the basis of our findings, we develop a conceptual model of the possible antecedents and consequences of top executive dismissal. We derive implications for boards involved in situations of executive dismissal and for the successors of dismissed executives, and we provide directions for future leadership research on executive dismissal.     

Pricing of Full‐Service Repair Contracts with Learning,Optimized Maintenance,and Information Asymmetry

This article considers the optimal pricing of full‐service (FS) repair contracts by taking into account learning and maintenance efficiency effects, competition from service , and asymmetric information. We analyze on‐call service (OS) and FS contracts in a market where customers exhibit heterogeneous risk aversion. While the customers minimize their disutility over the equipment lifetime, the service provider maximizes expected profits arising from the portfolio of OS and FS contracts. We show that the optimal FS price depends inter alia on the customer's prior cost experience and on OS repair and maintenance costs. The optimal FS price is shown to increase as fewer OS customers are lost to competition, whereas improved repair learning enabled by FS reduces the optimal price. A numerical study based on data from a manufacturer of forklifts highlights the importance of learning in maintenance operations, which constitutes the key benefit of FS contracts; 81% of the customers select the FS option and are willing to pay an insurance premium of around 1.5% of total OS cost against volatility of repair costs.     

Dezentrale Koordination von Stoffströmen in Recyclingnetzwerken

New legal regulations assign an extended product responsibility to the manufacturers, e.g. in the field of Waste Electrical and Electronic Equipment. Therefore, recycling of discarded products becomes increasingly important. For Waste Electrical and Electronic equipment, recycling is usually carried out by service providers, which are organised in recycling networks. In such networks of independent companies, centralized planning is not possible and therefore, a decentralized coordination mechanism is necessary. Within the article, a 2-level coordination approach is developed. This approach seems to be a good starting point for an efficient assignment of recycling tasks within the network, if a central planner is not present. The functionality of the approach is demonstrated based on an example.     

Getting Active in the Gulf: Environmental Attitudes and Action Following Two Mississippi Coastal Disasters

The current study examined the impact of the Gulf Oil Spill and Hurricane Katrina, environmental attitudes, and environmental action among residents of the Mississippi Gulf Coast. The authors sought to determine if disaster impact, worry about the environment, or connection to nature was associated with environmental action following the oil spill and in general. We hypothesized that disaster impact and environmental attitudes would be significantly associated with environmental action. Surveys were administered to 1,108 individuals receiving mental health services in connection with the Gulf Oil Spill. Results indicated that disaster impact was correlated with environmental worry, connection to nature, and action. Additionally, environmental worry and connection to nature were significantly associated with action, as were the effects of Hurricane Katrina to a lesser degree. This study supplements the existing literature by examining environmental attitudes, disaster impact, and their association with environmental action following two disasters.     

Think Tanks: New Organizational Actors in a Changing Swedish Civil Society

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - Policy institutes, or “think tanks”, are becoming increasingly ubiquitous in our societies. In this article,...