Steffen Friedrich

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Thirty-four alcoholics were treated with acupuncture to the ear and the body in a randomized single-blind placebo-controlled design over 14 days. Orthodox points and placebo needles to orthodox points were used daily for a total of 10 treatments starting on the first day of admission as add-on therapy to standard medication with carbamazepine. The primary(More)
There are numerous approaches towards quantifying the performance of NoSQL datastores with respect to dimensions that are notoriously hard to capture such as staleness or consistency in general. Many of these approaches, though, are built on assumptions regarding the underlying infrastructure or the test scenario and may lead to invalid results, if those(More)
In recent years, various distributed NoSQL datastores have been developed that offer horizontal scalability and higher availability than traditional relational databases, but fewer querying options and only reduced consistency guarantees. The diversity of the design space makes it difficult to understand the performance implications of individual system(More)
With the rise of the web 2.0 and the Internet of things, it has become feasible to track all kinds of information over time, in particular fine-grained user activities and sensor data on their environment and even their biometrics. However, while efficiency remains mandatory for any application trying to cope with huge amounts of data, only part of the(More)
Today, data is generated and consumed at unprecedented scale. This has lead to novel approaches for scalable data management subsumed under the term “NoSQL” database systems to handle the ever-increasing data volume and request loads. However, the heterogeneity and diversity of the numerous existing systems impede the well-informed selection of a data store(More)
The expiration-based caching model of the web is generally considered irreconcilable with the dynamic workloads of cloud database services, where expiration dates are not known in advance. In this paper, we present the Cache Sketch data structure which makes expiration-based caching of database records feasible with rich tunable consistency guarantees. The(More)
Die Kompetenzen einer informatischen Bildung der Schülerinnen und Schüler sind hinsichtlich der notwendigen Bestandteile noch nicht ausreichend genug charakterisiert. In diesem Kontext haben sich mit Unterstützung der Gesellschaft für Informatik e.V. Fachleute aus Schulen und Hochschulen zusammengefunden, um Standards für eine informatische Bildung(More)