47 research outputs found

    Travelling on Graphs with Small Highway Dimension

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    We study the Travelling Salesperson (TSP) and the Steiner Tree problem (STP) in graphs of low highway dimension. This graph parameter was introduced by Abraham et al. [SODA 2010] as a model for transportation networks, on which TSP and STP naturally occur for various applications in logistics. It was previously shown [Feldmann et al. ICALP 2015] that these problems admit a quasi-polynomial time approximation scheme (QPTAS) on graphs of constant highway dimension. We demonstrate that a significant improvement is possible in the special case when the highway dimension is 1, for which we present a fully-polynomial time approximation scheme (FPTAS). We also prove that STP is weakly NP-hard for these restricted graphs. For TSP we show NP-hardness for graphs of highway dimension 6, which answers an open problem posed in [Feldmann et al. ICALP 2015]

    Linking Proteomic and Transcriptional Data through the Interactome and Epigenome Reveals a Map of Oncogene-induced Signaling

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    Cellular signal transduction generally involves cascades of post-translational protein modifications that rapidly catalyze changes in protein-DNA interactions and gene expression. High-throughput measurements are improving our ability to study each of these stages individually, but do not capture the connections between them. Here we present an approach for building a network of physical links among these data that can be used to prioritize targets for pharmacological intervention. Our method recovers the critical missing links between proteomic and transcriptional data by relating changes in chromatin accessibility to changes in expression and then uses these links to connect proteomic and transcriptome data. We applied our approach to integrate epigenomic, phosphoproteomic and transcriptome changes induced by the variant III mutation of the epidermal growth factor receptor (EGFRvIII) in a cell line model of glioblastoma multiforme (GBM). To test the relevance of the network, we used small molecules to target highly connected nodes implicated by the network model that were not detected by the experimental data in isolation and we found that a large fraction of these agents alter cell viability. Among these are two compounds, ICG-001, targeting CREB binding protein (CREBBP), and PKF118–310, targeting ÎČ-catenin (CTNNB1), which have not been tested previously for effectiveness against GBM. At the level of transcriptional regulation, we used chromatin immunoprecipitation sequencing (ChIP-Seq) to experimentally determine the genome-wide binding locations of p300, a transcriptional co-regulator highly connected in the network. Analysis of p300 target genes suggested its role in tumorigenesis. We propose that this general method, in which experimental measurements are used as constraints for building regulatory networks from the interactome while taking into account noise and missing data, should be applicable to a wide range of high-throughput datasets.National Science Foundation (U.S.) (DB1-0821391)National Institutes of Health (U.S.) (Grant U54-CA112967)National Institutes of Health (U.S.) (Grant R01-GM089903)National Institutes of Health (U.S.) (P30-ES002109

    Operational Research: Methods and Applications

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    Throughout its history, Operational Research has evolved to include a variety of methods, models and algorithms that have been applied to a diverse and wide range of contexts. This encyclopedic article consists of two main sections: methods and applications. The first aims to summarise the up-to-date knowledge and provide an overview of the state-of-the-art methods and key developments in the various subdomains of the field. The second offers a wide-ranging list of areas where Operational Research has been applied. The article is meant to be read in a nonlinear fashion. It should be used as a point of reference or first-port-of-call for a diverse pool of readers: academics, researchers, students, and practitioners. The entries within the methods and applications sections are presented in alphabetical order. The authors dedicate this paper to the 2023 Turkey/Syria earthquake victims. We sincerely hope that advances in OR will play a role towards minimising the pain and suffering caused by this and future catastrophes

    Operational Research: methods and applications

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    This is the final version. Available on open access from Taylor & Francis via the DOI in this recordThroughout its history, Operational Research has evolved to include methods, models and algorithms that have been applied to a wide range of contexts. This encyclopedic article consists of two main sections: methods and applications. The first summarises the up-to-date knowledge and provides an overview of the state-of-the-art methods and key developments in the various subdomains of the field. The second offers a wide-ranging list of areas where Operational Research has been applied. The article is meant to be read in a nonlinear fashion and used as a point of reference by a diverse pool of readers: academics, researchers, students, and practitioners. The entries within the methods and applications sections are presented in alphabetical order. The authors dedicate this paper to the 2023 Turkey/Syria earthquake victims. We sincerely hope that advances in OR will play a role towards minimising the pain and suffering caused by this and future catastrophes

    Einfluss der Wirtschaftskrise auf die Verkehrstaugslichkeit von Straßenfahrzeugen in der Republik Kroatien

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    The impact of the economic crisis, i.e. the decrease in purchasing power in the Republic of Croatia, has been reflected negatively on the sales of new road vehicles and the maintenance plan of used road vehicles. A comparison of the results of technical inspections on vehicle roadworthiness has indicated a slight increase in unroadworthy vehicles, with a tendency for this to increase. Unroadworthiness and the average age of vehicles amounting to 12.18 years prompt for thinking about road safety in the Republic of Croatia. This paper aims to establish the extent of the increase in vehicle unroadworthiness and the importance of its reduction in order to increase road safety. The Republic of Croatia has adopted the National Road Safety Program for 2011-2020, accepting thereby a task that will be difficult to accomplish without organising training on the importance of vehicle roadworthiness.Die Folgen der Wirtschaftskrise bzw. die verminderte Kaufkraft in der Republik Kroatien haben den Verkauf von neuen und den Instandhaltungsplan von gebrauchten Straßenfahrzeugen negativ beeinflusst. Durch den Vergleich der mit der Verkehrstauglichkeit von Straßenfahrzeugen verbundenen Ergebnisse technischer Kontrollen ließ sich ein leichter Anstieg von verkehrsuntauglichen Fahrzeugen, mit einer Tendenz zur Erhöhung, feststellen. Die technische Untauglichkeit sowie das Durchschnittsalter von Straßenkraftfahrzeugen von 12,18 Jahren lassen Bedenken ĂŒber die Sicherheit des Straßenverkehrs in der Republik Kroatien aufkommen. Das Ziel dieser Untersuchung war es festzustellen, wie stark die Verkehrsuntauglichkeit von Straßenfahrzeugen angestiegen ist sowie auf die Wichtigkeit ihrer Minderung hinzuweisen, mit dem Zweck, die Sicherheit des Straßenverkehrs zu erhöhen. Die Republik Kroatien hat das Nationalprogramm der Sicherheit im Straßenverkehr 2011-2020 verabschiedet und sich dadurch vor eine schwierige Aufgabe gestellt, die sie ohne Schulungsveranstaltungen, welche die Wichtigkeit der Verkehrstauglichkeit von Fahrzeugen zum Thema haben, wohl kaum erfĂŒllen kann

    A Robust Learning-Based Detection and Tracking Algorithm

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    A Memetic Algorithm for Vertex-Biconnectivity Augmentation

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    This paper considers the problem of augmenting a given graph by a cheapest possible set of additional edges in order to make the graph vertex-biconnected. A real-world instance of this problem is the enhancement of an already established computer network to become robust against single node failures. The presented memetic algorithm includes an effective preprocessing of problem data and a fast local improvement strategy which is applied during initialization, mutation, and recombination. Only feasible, locally optimal solutions are created as candidates. Empirica
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