Finding Near-Optimal Weight Independent Sets at Scale

Computing maximum weight independent sets in graphs is an important NP-hard optimization problem. The problem is particularly difficult to solve in large graphs for which data reduction techniques do not work well. To be more precise, state-of-the-art branch-and-reduce algorithms can solve many large-scale graphs if reductions are applicable. Otherwise, their performance quickly degrades due to branching requiring exponential time. In this paper, we develop an advanced memetic algorithm to tackle the problem, which incorporates recent data reduction techniques to compute near-optimal weighted independent sets in huge sparse networks. More precisely, we use a memetic approach to recursively choose vertices that are likely to be in a large-weight independent set. We include these vertices into the solution, and further reduce the graph. We show that identifying and removing vertices likely to be in large-weight independent sets opens up the reduction space and speeds up the computation of large-weight independent sets remarkably. Our experimental evaluation indicates that we are able to outperform state-of-the-art algorithms. For example, our two algorithm configurations compute the best results among all competing algorithms for 205 out of 207 instances. Thus can be seen as a useful tool when large-weight independent sets need to be computed in~practice

Risk mitigation measures for pesticide runoff: How effective are they?

BACKGROUND: One of the most important sources of pesticide pollution of surface waters is runoff and erosion from agricultural fields after rainfall. This study analyses the efficacy of different risk mitigation measures to reduce pesticide runoff and erosion inputs into surface waters from arable land excluding rice fields. RESULTS: Three groups of risk mitigation measures were quantitatively analyzed: vegetative filter strips, micro-dams in row crops and soil conservation measures. Their effectiveness was evaluated based on a meta-analysis of available experimental data using statistical methods such as classification and regression trees, and exploratory data analysis. Results confirmed the effectiveness of vegetative filter strips and micro-dams. Contrary to common assumption, the width of vegetative filter strips alone is not sufficient to predict their effectiveness. The effectiveness of soil conservation measures (especially mulch-tillage) varied widely. This was in part due to the heterogeneity of the available experimental data, probably resulting from the inconsistent implementation and the inadequate definitions of these measures. CONCLUSION: Both vegetative filter strips and micro-dams are effective and suitable, and can therefore be recommended for quantitative assessment of environmental pesticide exposure in surface waters.However, the processes of infiltration and sedimentation in vegetative filter strips should be simulated with amechanistic model like Vegetative Filter Strip Modeling System, VFSMOD. The reduction effect ofmicro-dams can be modelled by reducing the runoff curve number, e.g., in the pesticide root zone model, PRZM. Soil conservationmeasures are in principle promising, but further well-documented data are needed to determine under which conditions they are effective

Von akustischen Medien zur auditiven Kultur : zum Verhältnis von Medienwissenschaft und Sound Studies

2. Hrsg. des Heftes: Axel Volmar Prof. Dr. Jens Schröter, Dr. Sebastian Gießmann und J-Prof. Dr. Benjamin Beil sind Herausgeber der Reihe. Die Herausgeber der einzelnen Hefte sind renommierte Wissenschaftler und -innen aus dem In- und Ausland.Die Beiträge dieser Navigationen-Ausgabe möchten mit je eigenen wissenschaftsgeschichtlichen, medienarchäologischen, kulturhistorischen, musiksoziologischen und ethnographischen Schwerpunktsetzungen zeigen, auf welche Weise sowohl die Medienwissenschaft als auch die Musikwissenschaft von einem solchen Dialog profitieren. In umgekehrter Stoßrichtung können die einzelnen Studien zugleich verdeutlichen, was die medienwissenschaftliche Forschung durch ihre thematische Ausrichtung, ihre theoretischen Ansätze und methodischen Werkzeuge zur weiteren Elaborierung der ›Sound Studies‹ und des Gegenstandsbereichs ›Auditive Kultur‹ beitragen kann