A comparison of statistical machine learning methods in heartbeat detection and classification

In health care, patients with heart problems require quick responsiveness in a clinical setting or in the operating theatre. Towards that end, automated classification of heartbeats is vital as some heartbeat irregularities are time consuming to detect. Therefore, analysis of electro-cardiogram (ECG) signals is an active area of research. The methods proposed in the literature depend on the structure of a heartbeat cycle. In this paper, we use interval and amplitude based features together with a few samples from the ECG signal as a feature vector. We studied a variety of classification algorithms focused especially on a type of arrhythmia known as the ventricular ectopic fibrillation (VEB). We compare the performance of the classifiers against algorithms proposed in the literature and make recommendations regarding features, sampling rate, and choice of the classifier to apply in a real-time clinical setting. The extensive study is based on the MIT-BIH arrhythmia database. Our main contribution is the evaluation of existing classifiers over a range sampling rates, recommendation of a detection methodology to employ in a practical setting, and extend the notion of a mixture of experts to a larger class of algorithms

Algebraic incremental maintenance of XML views

International audienceMaterialized views can bring important performance benefits when querying XML documents. In the presence of XML document changes, materialized views need to be updated to faithfully reflect the changed document. In this work, we present an algebraic approach for propagating source updates to XML materialized views expressed in a powerful XML tree pattern formalism. Our approach differs from the state of the art in the area in two important ways. First, it relies on set-oriented, algebraic operations, to be contrasted with node-based previous approaches. Second, it exploits state-of-the-art features of XML stores and XML query evaluation engines, notably XML structural identifiers and associated structural join algorithms. We present algorithms for determining how updates should be propagated to views, and highlight the benefits of our approach over existing algorithms through a series of experiments

10381 Summary and Abstracts Collection -- Robust Query Processing

Dagstuhl seminar 10381 on robust query processing (held 19.09.10 - 24.09.10) brought together a diverse set of researchers and practitioners with a broad range of expertise for the purpose of fostering discussion and collaboration regarding causes, opportunities, and solutions for achieving robust query processing. The seminar strove to build a unified view across the loosely-coupled system components responsible for the various stages of database query processing. Participants were chosen for their experience with database query processing and, where possible, their prior work in academic research or in product development towards robustness in database query processing. In order to pave the way to motivate, measure, and protect future advances in robust query processing, seminar 10381 focused on developing tests for measuring the robustness of query processing. In these proceedings, we first review the seminar topics, goals, and results, then present abstracts or notes of some of the seminar break-out sessions. We also include, as an appendix, the robust query processing reading list that was collected and distributed to participants before the seminar began, as well as summaries of a few of those papers that were contributed by some participants

Entrepreneurship, Development, and the Spatial Context Retrospect and Prospect

Entrepreneurship has been a topical issue in the business administration literature, but in the past decade a wave of interest can be observed on the role of entrepreneurship in the economic growth literature. This paper aims to highlight the various contributions to the entrepreneurship literature from the perspective of regional economic development. After a broad overview, particular attention is given to the regional action space of entrepreneurs, including their social and spatial network involvement. The paper concludes with a future research agenda.entrepreneurship, regional growth, action space, networks, SME, virtual organization, innovation

Internationalisation of Innovation: Why Chip Design Moving to Asia

This paper will appear in International Journal of Innovation Management, special issue in honor of Keith Pavitt, (Peter Augsdoerfer, Jonathan Sapsed, and James Utterback, guest editors), forthcoming. Among Keith Pavitt's many contributions to the study of innovation is the proposition that physical proximity is advantageous for innovative activities that involve highly complex technological knowledge But chip design, a process that creates the greatest value in the electronics industry and that requires highly complex knowledge, is experiencing a massive dispersion to leading Asian electronics exporting countries. To explain why chip design is moving to Asia, the paper draws on interviews with 60 companies and 15 research institutions that are doing leading-edge chip design in Asia. I demonstrate that "pull" and "policy" factors explain what attracts design to particular locations. But to get to the root causes that shift the balance in favor of geographical decentralization, I examine "push" factors, i.e. changes in design methodology ("system-on-chip design") and organization ("vertical specialization" within global design networks). The resultant increase in knowledge mobility explains why chip design - that, in Pavitt's framework is not supposed to move - is moving from the traditional centers to a few new specialized design clusters in Asia. A completely revised and updated version has been published as: " Complexity and Internationalisation of Innovation: Why is Chip Design Moving to Asia?," in International Journal of Innovation Management, special issue in honour of Keith Pavitt, Vol. 9,1: 47-73.

Une approche flexible et décentralisée du traitement de requêtes dans les systèmes géo-distribués

This thesis studies the design of query processing systems, across a diversity of geo-distributed settings. Optimising performance metrics such as response time, freshness, or operational cost involves design decisions, such as what derived state (e.g., indexes, materialised views, or caches) to maintain, and how to distribute and where to place the corresponding computation and state. These metrics are often in tension, and the trade-offs depend on the specific application and/or environment. This requires the ability to adapt the query engine's topology and architecture, and the placement of its components. This thesis makes the following contributions: - A flexible architecture for geo-distributed query engines, based on components connected in a bidirectional acyclic graph. - A common microservice abstraction and API for these components, the Query Processing Unit (QPU). A QPU encapsulates some primitive query processing task. Multiple QPU types exist, which can be instantiated and composed into complex graphs. - A model for constructing modular query engine architectures as a distributed topology of QPUs, enabling flexible design and trade-offs between performance metrics. - Proteus, a QPU-based framework for constructing and deploying query engines. - Representative deployments of Proteus and experimental evaluation thereof.Cette thèse présente l'étude de la conception de systèmes de traitement de requêtes dans divers cadres géo-distribués. L'optimisation des mesures de performance telles que le temps de réponse, la fraîcheur ou le coût opérationnel implique des décisions de conception tel que le choix de l’état dérivé (indices, vues matérialisées, caches par ex.) à construire et maintenir, et la distribution et le placement de ces derniers et de leurs calculs. Ces métriques sont souvent opposées et les compromis dépendent de l'application et/ou de la spécificité de l'environnement. La capacité d'adapter la topologie et l'architecture du système de traitement de requêtes devient alors essentielle, ainsi que le placement de ses composants. Cette thèse apporte les contributions suivantes : - Une architecture flexible pour les systèmes de traitement de requêtes géo-distribués, basée sur des composants connectés dans un graphe bidirectionnel acyclique. - Une abstraction de micro-service et une API communes pour ces composants, le Query Processing Unit (QPU). Un QPU encapsule une tâche de traitement de requête primitive. Il existe plusieurs types de QPU qui peuvent être instanciés et composés en graphes complexes. - Un modèle pour construire des architectures de systèmes de traitement de requêtes modulaires composées d’une topologie distribuée de QPUs, permettant une conception flexible et des compromis selon les mesures de performance visées. - Proteus, un framework basé sur les QPU, permettant la construction et le déploiement de systèmes de traitement de requêtes. - Déploiements représentatifs de systèmes de traitement de requêtes à l'aide de Proteus, et leur évaluation expérimentale

Managing the complex data center environment: an Integrated Energy-aware Framework

The problem of Information Technology energy consumption has gained much attention due to the always increasing use of IT both for business and for personal reasons. In particular, data centers are now playing a much more important role in the modern society, where the information is available all the time and everywhere. In this context, the aim of this paper is to study energy efficiency issues within data centers from the Information System perspective. The proposed approach integrates the application and infrastructure capabilities, in which the enactment of adaptation mechanisms is aligned with the business process. Based on both energy and quality dimensions of service-based applications, a model-based approach supports the formulation of new constrained optimization problem that takes into consideration over-constrained solutions where the goal is to obtain the better trade-off between energy and quality requirements. These ideas are combined within a framework where time-based analysis allow the identification of potential system threats and drive the selection of adaptation actions improving overall energy and quality requirements, represented by indicators satisfaction. In addition, the framework includes an evolution mechanism that is able to evaluate past decisions feedback in order to adjust the model according to the current underlying environment. Finally, the benefits of the approach are analyzed in an experimental setting