Asymmetric Incentives in Peer-to-Peer Systems

In most application scenarios for Peer-to-Peer systems, in order to achieve an overall acceptable system performance an incentive scheme is required that motivates users to share as much as possible of their free resources Today most peers use connections of asymmetric links, such as A-DSL or cable modems. Therefore, users have significantly more download bandwidth than their available upload bandwidth. Applying this observation to incentive schemes suggests that one unit of upload bandwidth should be valued higher than one download unit. Using such an incentive scheme leads the economy of the system to inflation. The incentive scheme would finally collapse. However, by exhibiting the phenomenon of altruistic behavior altruistic peers would accumulate the waste amount of the incentive units. Thus, inflation might be avoided. Gathering the results of a detailed simulative approach, this paper shows how to balance asymmetric incentive schemes in order to avoid inflation

The Great West Ukrainian Prison Massacre of 1941

After Germany invaded the Soviet Union in 1941, the Soviet secret police, the NKVD, executed a staggering number of political prisoners in Western Ukraine-somewhere between 10,000 and 40,000-in the space of eight days, in one of the greatest atrocities perpetrated by the Soviet state. Yet the Great West Ukrainian Prison Massacre of 1941 is largely unknown. This sourcebook aims to change that, offering detailed scholarly analysis, eyewitness testimonies and profiles of known victims, and a selection of fiction, memoirs, and poetry that testifies to the lasting impact of the massacre in the collective memory of Ukrainians

Principles of building scalable and robust event-based systems

Event-based systems are of tremendous importance for a wide range of distributed applications interacting with physical processes, e.g., traffic management, financial services, manufacturing processes, or health services. Event-based systems support to monitor, analyze events of interest efficiently. Therefore, they enable distributed applications to respond to detected events in the form of appropriate actions. Event-based systems provide as part of the publish/subscribe paradigm, mechanisms for the scalable integration of a variety of information sources, e.g., dedicated sensor networks, mobile devices, or cameras. In addition, event-based systems allow as part of the event processing paradigm to detect correlations between events from distinct information sources. Event-based systems ensure two important forms of decoupling of importance building scalable distributed applications. Decoupling producers of information and consumers of information by ensuring that neither producers need to keep state on the interested consumers nor consumers need to know the producers of information, is a key principle for scalable communications. Furthermore, a step-wise correlation from primary events to events of importance for distributed applications is an enabler to specify distributed applications independent from the underlying sensor infrastructure at hand. In this thesis, we present and discuss principles of building scalable and robust event-based systems. On the one hand, this requires distributed mechanisms to fulfill a wide spectrum of distinct application requirements, e.g., being bandwidth efficient and providing events with low end-to-end latency. On the other hand, the underlying mechanisms for event-based systems need to deal with many levels of dynamics, e. g., dynamics in the rate at which events are produced, dynamics in the interest of producers and consumers, mobility of consumer and producer, failures and changing security privileges to access events. In the context of mechanisms for event distribution, operator execution, operator migration, operator recovery and secure access to events, we highlight problems in the scalable and robust design of those mechanisms. We give an overview on related work in the field and present in a tutorial manner the ideas of six own contributions for realizing distributed event-based systems

The Great West Ukrainian Prison Massacre of 1941

After Germany invaded the Soviet Union in 1941, the Soviet secret police, the NKVD, executed a staggering number of political prisoners in Western Ukraine-somewhere between 10,000 and 40,000-in the space of eight days, in one of the greatest atrocities perpetrated by the Soviet state. Yet the Great West Ukrainian Prison Massacre of 1941 is largely unknown. This sourcebook aims to change that, offering detailed scholarly analysis, eyewitness testimonies and profiles of known victims, and a selection of fiction, memoirs, and poetry that testifies to the lasting impact of the massacre in the collective memory of Ukrainians

Proceedings der 11. Internationalen Tagung Wirtschaftsinformatik (WI2013) - Band 1

The two volumes represent the proceedings of the 11th International Conference on Wirtschaftsinformatik WI2013 (Business Information Systems). They include 118 papers from ten research tracks, a general track and the Student Consortium. The selection of all submissions was subject to a double blind procedure with three reviews for each paper and an overall acceptance rate of 25 percent. The WI2013 was organized at the University of Leipzig between February 27th and March 1st, 2013 and followed the main themes Innovation, Integration and Individualization.:Track 1: Individualization and Consumerization Track 2: Integrated Systems in Manufacturing Industries Track 3: Integrated Systems in Service Industries Track 4: Innovations and Business Models Track 5: Information and Knowledge ManagementDie zweibändigen Tagungsbände zur 11. Internationalen Tagung Wirtschaftsinformatik (WI2013) enthalten 118 Forschungsbeiträge aus zehn thematischen Tracks der Wirtschaftsinformatik, einem General Track sowie einem Student Consortium. Die Selektion der Artikel erfolgte nach einem Double-Blind-Verfahren mit jeweils drei Gutachten und führte zu einer Annahmequote von 25%. Die WI2013 hat vom 27.02. - 01.03.2013 unter den Leitthemen Innovation, Integration und Individualisierung an der Universität Leipzig stattgefunden.:Track 1: Individualization and Consumerization Track 2: Integrated Systems in Manufacturing Industries Track 3: Integrated Systems in Service Industries Track 4: Innovations and Business Models Track 5: Information and Knowledge Managemen

Forschungsbericht Universität Mannheim 2006 / 2007

Sie erhalten darin zum einen zusammenfassende Darstellungen zu den Forschungsschwerpunkten und Forschungsprofilen der Universität und deren Entwicklung in der Forschung. Zum anderen gibt der Forschungsbericht einen Überblick über die Publikationen und Forschungsprojekte der Lehrstühle, Professuren und zentralen Forschungseinrichtungen. Diese werden ergänzt um Angaben zur Organisation von Forschungsveranstaltungen, der Mitwirkung in Forschungsausschüssen, einer Übersicht zu den für Forschungszwecke eingeworbenen Drittmitteln, zu den Promotionen und Habilitationen, zu Preisen und Ehrungen und zu Förderern der Universität Mannheim. Darin zeigt sich die Bandbreite und Vielseitigkeit der Forschungsaktivitäten und deren Erfolg auf nationaler und internationaler Ebene