From Task Classification Towards Similarity Measures for Recommendation in Crowdsourcing Systems

Task selection in micro-task markets can be supported by recommender systems to help individuals to find appropriate tasks. Previous work showed that for the selection process of a micro-task the semantic aspects, such as the required action and the comprehensibility, are rated more important than factual aspects, such as the payment or the required completion time. This work gives a foundation to create such similarity measures. Therefore, we show that an automatic classification based on task descriptions is possible. Additionally, we propose similarity measures to cluster micro-tasks according to semantic aspects.Comment: Work in Progress Paper at HCOMP 201

Standards für Lehr- und Lerntechnologien. Metadaten, Inhaltsformate und Beschreibung von Lernprozessen

Dieses Kapitel führt in die Bedeutung von Standards, die von Informationssystemen für das Lernen und Lehren verwendet werden, ein und stellt deren wichtigste Vertreter/innen vor. Das Einhalten von Standards durch Informationssysteme für Lehren und Lernen ermöglicht den Nutzer/innen Lehr- und Lernressourcen zwischen verschiedenen Informationssystemen austauschen zu können und damit auch verschiedene Informationssysteme unterschiedlicher Anbieter nutzen zu können. Dementsprechend ist ein Grundverständnis der Standards und ihrer jeweiligen Aufgabe bei der Auswahl von Informationssystemen für Lehren und Lernen relevant. Ein Schwerpunkt des Kapitels liegt auf Metadaten. Der Nutzen von Metadaten und Standards für Metadaten zur Beschreibung von Lehr- und Lernressourcen werden erläutert. Da Informationssystemen für Lehren und Lernen häufig von Benutzenden die Eingabe von Metadaten verlangen und in diesen Systemen mittels Metadaten gesucht wird, ist ein Verständnis von Metadaten in diesem Bereich von hoher Relevanz. Neben Standards für Metadaten werden mit dem Sharable Content Object Reference Model (SCORM) und Question and Test Interoperability (QTI) zwei Standards, die den Austausch von Lernressourcen zwischen verschiedenen Informationssystemen ermöglichen, vorgestellt. Zur einheitlichen Beschreibung von Lehr- und Lernprozessen dienen IMS Learning Design (IMS LD) und didaktische Entwurfsmuster, die ebenfalls Gegenstand diese Kapitels sind. Ziel dieses Kapitels ist es, insgesamt für die unterschiedliche Bedeutung und Aufgaben von Standards für Informationssysteme für das Lehren und Lernen zu sensibilisieren und ein Grundverständnis der wichtigsten im Themenbereich relevanten Standards zu vermitteln. (DIPF/Orig.

Effects of weak input side mode suppression ratio and output filtration on the intensity noise of a self-seeded gain switched optical pulses at 2.5 GHz

Mode partition noise is shown to be a cause for concern in terms of the intensity noise induced on a self-seeded gain-switched pulse when filtering is used to increase the side mode suppression ratio (SMSR) of the output signal to >30 dB. The inherent SMSR of a self-seeded gain switched pulse is revealed to be a vital parameter especially when output filtration is used. Our results portray the fact that such a procedure would lead to an introduction of noise on the SSGS pulses if the inherent SMSR is weak, and may ultimately determine whether or not a source is suitable for use in WDM or OTDM optical communication networks

Onset of collective and cohesive motion

We study the onset of collective motion, with and without cohesion, of groups of noisy self-propelled particles interacting locally. We find that this phase transition, in two space dimensions, is always discontinuous, including for the minimal model of Vicsek et al. [Phys. Rev. Lett. {\bf 75},1226 (1995)] for which a non-trivial critical point was previously advocated. We also show that cohesion is always lost near onset, as a result of the interplay of density, velocity, and shape fluctuations.Comment: accepted for publication in Phys. Rev. Let

Optimized pulse source employing an externally injected gain-switched laser diode in conjunction with a nonlinearly chirped grating

In this paper, we demonstrate the generation of transform-limited short optical pulses, which display excellent spectral and temporal qualities by employing a novel technology, based on an externally injected gain-switched laser in conjunction with a nonlinearly chirped grating. Using this technique, 3.5-ps optical pulses exhibiting a time-bandwidth product (TBP) of 0.45 are generated, which are suitable for use in high-speed 80 Gb/s optical time-division multiplexing (OTDM) communications systems. The numerical integration of a set of rate equations using suitable parameters for the devices used in the experiments were carried out to further confirm the feasibility of the proposed method for developing an optimized pulse source for high-speed photonic systems

80 Gb/s optimised pulse source using a gain-switched laser diode in conjunction with a nonlinearly chirped grating

The authors demonstrate the generation of transforms limited short optical pulses, which display excellent spectral and temporal qualities by employing a novel technology, based on an externally injected gain-switched laser in conjunction with a non-linearly chirped grating. Using this technique, 3.5 ps optical pulses, exhibiting a time bandwidth product of 0.45, are generated, which are suitable for use in high-speed 80 Gb/s OTDM communications systems