Distributed Dominating Set Approximations beyond Planar Graphs

The Minimum Dominating Set (MDS) problem is one of the most fundamental and challenging problems in distributed computing. While it is well-known that minimum dominating sets cannot be approximated locally on general graphs, over the last years, there has been much progress on computing local approximations on sparse graphs, and in particular planar graphs. In this paper we study distributed and deterministic MDS approximation algorithms for graph classes beyond planar graphs. In particular, we show that existing approximation bounds for planar graphs can be lifted to bounded genus graphs, and present (1) a local constant-time, constant-factor MDS approximation algorithm and (2) a local $\mathcal{O}(\log^*{n})$-time approximation scheme. Our main technical contribution is a new analysis of a slightly modified variant of an existing algorithm by Lenzen et al. Interestingly, unlike existing proofs for planar graphs, our analysis does not rely on direct topological arguments.Comment: arXiv admin note: substantial text overlap with arXiv:1602.0299

Metaheuristics for Order Batching and Sequencing in Manual Order Picking Systems

Order picking deals with the retrieval of articles from their storage locations in order to satisfy customer requests. A major issue in manual order picking systems concerns of the transformation and consolidation of customer orders into picking orders (order batching). In practice, customer orders have to be completed by certain due dates in order to avoid delay in the shipment to customers or in production. The composition of the picking orders, their processing times and the sequence according to which they are released have a significant impact on whether and to which extent given due dates are violated. This paper presents how metaheuristics can be used in order to minimize the total tardiness for a given set of customer orders. The first heuristic is based on Iterated Local Search, the second one is inspired by the Attribute-Based Hill Climber, a heuristic based on a simple tabu search principle. In a series of extensive numerical experiments, the performance of these metaheuristics is analyzed for different classes of instances. We will show that the proposed methods provide solutions which may allow for operating order picking systems more efficiently. Solutions can be improved by 46% on average, compared to the ones obtained by standard constructive heuristics such as an application of the Earliest Due Date rule.Warehouse Management, Order Batching, Batch Sequencing, Due Dates, Iterated Local Search, Attribute-Based Hill Climber

Shadows and cavities in protoplanetary disks: HD163296, HD141569A, and HD150193A in polarized light

The morphological evolution of dusty disks around young (few Myr-old) stars is pivotal to better understand planet formation. Since both dust grains and the global disk geometry evolve on short timescale, high-resolution imaging of a sample of objects may provide important hints towards such an evolution. We enlarge the sample of protoplanetary disks imaged in polarized light with high-resolution by observing the Herbig Ae/Be stars HD163296, HD141569A, and HD150193A. We integrate our data with previous datasets to paint a larger picture of their morphology. We report a weak detection of the disk around HD163296 in both H and Ks band. The disk is resolved as a broken ring structure with a significan surface brightness drop inward of 0.6 arcsec. No sign of extended polarized emission is detected from the disk around HD141569A and HD150193A. We propose that the absence of scattered light in the inner 0.6 arcsec around HD163296 and the non-detection of the disk around HD150193A may be due to similar geometric factors. Since these disks are known to be flat or only moderately flared, self-shadowing by the disk inner wall is the favored explanation. We show that the polarized brightness of a number of disks is indeed related to their flaring angle. Other scenarios (such as dust grain growth or interaction with icy molecules) are also discussed. On the other hand, the non-detection of HD141569A is consistent with previous datasets revealing the presence of a huge cavity in the dusty disk.Comment: 10 pages, 5 figures; accepted by Astronomy & Astrophysic

The Next Generation of Medical Decision Support : A Roadmap Toward Transparent Expert Companions

Artikelnummer 507973Increasing quality and performance of artificial intelligence (AI) in general and machine learning (ML) in particular is followed by a wider use of these approaches in everyday life. As part of this development, ML classifiers have also gained more importance for diagnosing diseases within biomedical engineering and medical sciences. However, many of those ubiquitous high-performing ML algorithms reveal a black-box-nature, leading to opaque and incomprehensible systems that complicate human interpretations of single predictions or the whole prediction process. This puts up a serious challenge on human decision makers to develop trust, which is much needed in life-changing decision tasks. This paper is designed to answer the question how expert companion systems for decision support can be designed to be interpretable and therefore transparent and comprehensible for humans. On the other hand, an approach for interactive ML as well as human-in-the-loop-learning is demonstrated in order to integrate human expert knowledge into ML models so that humans and machines act as companions within a critical decision task. We especially address the problem of Semantic Alignment between ML classifiers and its human users as a prerequisite for semantically relevant and useful explanations as well as interactions. Our roadmap paper presents and discusses an interdisciplinary yet integrated Comprehensible Artificial Intelligence (cAI)-transition-framework with regard to the task of medical diagnosis. We explain and integrate relevant concepts and research areas to provide the reader with a hands-on-cookbook for achieving the transition from opaque black-box models to interactive, transparent, comprehensible and trustworthy systems. To make our approach tangible, we present suitable state of the art methods with regard to the medical domain and include a realization concept of our framework. The emphasis is on the concept of Mutual Explanations (ME) that we introduce as a dialog-based, incremental process in order to provide human ML users with trust, but also with stronger participation within the learning process

Ethnography in Health Services Research: Oscillation Between Theory and Practice

The well-known divergence between what policy and protocol look like on paper, and what happens in the actual practice of daily life remains a central challenge in health services provision and research. This disparity is usually referred to as the theory–practice gap and contributes to concerns that scientific evidence fails to make substantial impacts on the processes of service delivery. In this article, we present an argument for the inclusion of ethnographic methods in health services research and show that this approach enables researchers to address this divergence by working within it. We trace how ethnography, through generative processes of oscillation, can take us beyond lamenting the gap and capture the relational dynamics of people working together in complex systemic arrangements. By moving from example to methodological reflection, to principle of research, we demonstrate how the oscillation of ethnographic research between theory and practice can productively contribute to the field of health service research

Neugier und epistemisches Handeln

Spezifische epistemische Neugier ist ein motivationaler Zustand, der durch konkrete Fragen ausgelöst und durch Wissenserwerb befriedigt wird. In der vorliegenden Arbeit geht es um die Entstehungsbedingungen spezifischer epistemischer Neugier und die Charakteristika neugiermotivierten Handelns. In kritischer Auseinandersetzung mit vorhandenen Neugiertheorien wird ein integratives Modell entwickelt, dem zufolge Neugier auf der metakognitiven Erfahrung einer gesteigerten kognitiven Aktivität beruht. Derartige metakognitive Erfahrungen können fehlattribuiert werden, wenn ein extrinsisches Ziel vorliegt. Eine zentrale Implikation des Modells besagt daher, dass die Neugierentstehung durch übergeordnete Ziele bei der Auseinandersetzung mit Fragen gehemmt werden kann. Ableitungen aus dem Modell wurden in zwei Experimenten und einer Fragebogenstudie untersucht. Insgesamt sprechen die Ergebnisse der Experimente und der Fragebogenstudie dafür, dass die durch eine Frage ausgelöste kognitive Aktivität sich nur bei geringer Instrumentalität in Neugier niederschlägt. Die Ergebnisse der Fragebogenstudie zeigen darüber hinaus, dass neugiermotiviertes Handeln durch den Einsatz epistemischer (wahrheitsorientierter) Verarbeitungsstrategien gekennzeichnet ist

Zur Aussprache von Anglizismen im österreichischen Deutsch

Die vorliegende Arbeit gewährt einen Einblick in ein Randthema der Anglizismenforschung: das Spannungsfeld zwischen Kodifikation und Realisierung von Xenophonen im Kontext der Erstsprache Deutsch. Begreifen wir das Englische als Adstrat des Deutschen, so nehmen wir als selbstverständlich an, dass lexikalische Elemente der Gebersprache in die Replikasprache (hier: Deutsch) eingehen. Was aber passiert auf der Ebene der Laute? Das englische Lautin-ventar unterscheidet sich vom deutschen in mehr Punkten als gemeinhin angenommen. Nicht nur in Birthday stellt den Deutschsprachigen vor die Frage, ob ein möglicherweise gekünsteltes [θ] angebracht ist, oder ob doch bequem auf Börsdee ausgewichen werden kann. Beinahe jeder Laut des Englischen wird durch einen deutschen ersetzt, sobald ein Fremdwort im Deutschen gebraucht wird. Diese Ersetzungen folgen bestimmten Prinzipien, etwa dem Prinzip der Similarität: Je ähnlicher ein fremder Laut seiner deutschen Entspre-chung, umso eher wird er eingedeutscht, da den wenigsten Sprachbenutzern der Unterschied überhaupt bewusst ist (z.B.: /a:/ in Vater vs. /ɑ:/ in father). Umgekehrt werden diejenigen Laute, die besonders fremd klingen, häufig intendiert original ausgesprochen, da etwa die Ersetzung von /θ/ in thanks durch /s/ stark stigmatisiert ist. Letztlich entscheidet sich der Sprachbenutzer immer – bewusst oder unbewusst – für eine eher deutsche oder eine eher englische Aussprache. Diese Entscheidung hängt nun wesentlich von den Englischkenntnissen des Sprechers und seiner Einstellung zu Englisch ab, aber auch der Kontext, in dem eine Äußerung getätigt wird, sowie die Bekanntheit des betreffenden Wortes sind von Bedeutung. Der Laie mag nun im Alltag wenig Gedanken an derartige Entscheidungsprozesse verlieren, doch Berufssprecher und andere professionelle Sprachbenutzer (Linguisten, Lehrer, Logopäden etc.) benötigen zur Ausübung ihrer Tätigkeit zuverlässige Nachschlagewerke, in denen die Ausspracheregeln des Deutschen und seiner Fremdwörter kodifiziert sind. Nun divergieren aber besonders hinsichtlich der lautlichen Kodifikation von Anglizismen die An-gaben in den verfügbaren Aussprachewörterbüchern teilweise erheblich. Die vorliegende Arbeit untersucht eben diese Angaben und zeigt die Unterschiede und Mängel einiger wich-tiger Kodizes auf. Besonders der unterschiedliche Grad der Eindeutschung und unterschiedli-che Transkriptionssysteme liefern oft mehr Fragen als Antworten. Ausgehend von den Er-gebnissen der Untersuchung der Wörterbücher wird schließlich die These formuliert, dass für das Deutsche sogenannte periphere Phoneme angenommen werden können. Schließlich wird empirisch überprüft, welche Laute besonders häufig von Sprechern des österreichi-schen Deutsch original ausgesprochen werden und deshalb in der Kodifikation in Ausspra-chewörterbüchern berücksichtigt werden sollten.This paper intends to grant an insight into a quite special area of Anglicism research: the gap between codification and realisation of xenophones within the context of German as a first language. If we consider English an adstratum of German it seems obvious that numerous lexical elements of the source language enter the borrowing language (i.e. German). How-ever, what happens on the phonological level? The English sound inventory differs from the German one in many more respects than we might think. Not only as in birthday con-fronts the German-speaking individual with the decision whether to produce a probably arti-ficial sounding [θ], or resort to the more convenient Börsdee. Almost every English sound is being substituted by a German one as soon as a foreign word is used in German. Substitution in this case follows certain principles, such as phonological similarity. The closer the percep-tual similarity of a foreign sound, the more likely it is Germanised ( i.e. substituted by a Ger-man sound), because hardly any language user is aware of their difference (e.g. /a:/ in Vater vs. /ɑ:/ in father). Reversely, especially salient foreign sounds are being adopted and pro-duced originally quite often. Both problematic and prominent, /θ/ as in thanks is readily pronounced originally, because its substitution by /s/ is stigmatised. At the end of the day the language user – consciously or unconsciously – opts for a rather German or a rather English pronunciation. This decision largely depends on the individual proficiency of and attitude towards English, the context in which an utterance is made, as well as on the prevalence of the very word. The average language user might not be troubled by these decisions in eve-ryday life, but professionals, such as newsreaders, actors, linguists and teachers need au-thoritative reference books where the correct pronunciation of German an its loanwords is codified. However, especially the phonetic codification of Anglicisms appears to be very di-vergent throughout the pronunciation dictionaries at hand. This paper intends to examine some relevant dictionaries and reveal their differences and inconsistencies. Especially differ-ent degrees of “Germanisation” as well as divergent transcription conventions sometimes provide more questions than answers. Taking the examination of the pronunciation diction-aries as a starting point the existence of so called peripheral phonemes can be hypothesised. Finally, the existence of these peripheral phonemes is being validated empirically. The ques-tion is: Which sounds are adopted and pronounced originally by speakers of Austrian German quite frequently and should therefore be considered peripheral phonemes in pronunciation dictionaries