Abstract

We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log 10 increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV—CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences—is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.

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Standards like SOAP, WSDL, and UDDI facilitate the proliferation of services. Based on these technologies, processes are a means to combine services to applications and to provide new value-added services. For large information systems, a centralized process engine is no longer appropriate due to limited scalability. Instead, in this paper, we propose a distributed and decentralized process engine that routes process instances directly from one peer to the next. Such a peer-to-peer process execution promises good scalability characteristics since it is able to dynamically balance the load of processes and services among all available service providers. Therefore, navigation costs only accumulate on peers that are directly involved in the execution. However, this requires sophisticated strategies for the replication of meta-data for peer-to-peer process execution. Especially, replication mechanisms should avoid frequent accesses to global information repositories. In our system, called OSIRIS (Open Service Infrastructure for Reliable and Integrated Process Support), we deploy a publish/subscribe-based replication scheme together with freshness predicates to significantly reduce replication costs. This way, OSIRIS can support process-based applications in a dynamically evolving system without limiting scalability and correctness. Experiments have shown very promising results with respect to scalability. In addition, OSIRIS provides a flexible infrastructure that can be extended seamlessly in a modular way. This paper demonstrates the extension towards distributed concurrency control.

Abstract. Standards like SOAP, WSDL, and UDDI facilitate the proliferation of services. Based on these technologies, processes are a means to combine services to applications and to provide new value-added services. For large information systems, a centralized process engine is no longer appropriate due to limited scalability. Instead, in this paper, we propose a distributed and decentralized process engine that routes process instances directly from one node to the next ones. Such a Peer-to-Peer Process Execution (P 3 E) promises good scalability characteristics since it is able to dynamically balance the load of processes and services among all available service providers. Therefore, navigation costs only accumulate on nodes that are directly involved in the execution. However, this requires sophisticated strategies for the replication of meta information for P 3 E. Especially, replication mechanisms should avoid frequent accesses to global information repositories. In our system called Osiris (Open Service Infrastructure for Reliable and Integrated Process Support), we deploy a clever publish/subscribe based replication scheme together with freshness predicates to significantly reduce replication costs. This way, OSIRIS can support process-based applications in a dynamically evolving system without limiting scalability and correctness. First experiments have shown very promising results with respect to scalability.

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Vom 14. bis 20. Nov. 1997 führte das Referenzlabor für Radongas-Konzentrationsmessungen des Paul Scherrer Instituts die Vergleichsmessung 1997 für Radongasdetektoren und -messgeräte durch. An der Exposition in einer Referenzatmosphäre der PSI-Radonkammer mit einer mittleren Radongaskonzentration von 3860 Bqm-3 beteiligten sich 15 Privatpersonen, Firmen oder Institutionen mit total 154 Detektoren und drei Messgeräten. Die Mehrheit der Teilnehmer waren vom Bundesamt für Gesundheit anerkannte Messstellen für Radongasmessungen in Häusern. Für die Anerkennung von Messstellen wird verlangt, dass die Messwerte bei einer PSI-Vergleichsmessung nicht mehr als 15% vom Referenzwert abweichen (Rückführbarkeitskriterium) und dass die Streuung der Einzelwerte des Mittelwerts von fünf Detektorresultaten nicht mehr als 15% beträgt (Reproduzierbarkeitskriterium). Die gemittelten Resultate von Elektret-Ionisationskammern, Kernspurdetektoren und Messgeräten erfüllten bis auf drei Ausnahmen die geforderten Kriterien.