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See detailSelf-reported dependence on mobile phones in young adults: A European cross-cultural empirical survey.
Lopez-Fernandez, Olatz; Kuss, Daria J.; Romo, Lucia et al

in Journal of behavioral addictions (in press)

Background and aims Despite many positive benefits, mobile phone use can be associated with harmful and detrimental behaviors. The aim of this study was twofold: to examine (a) cross-cultural patterns of ... [more ▼]

Background and aims Despite many positive benefits, mobile phone use can be associated with harmful and detrimental behaviors. The aim of this study was twofold: to examine (a) cross-cultural patterns of perceived dependence on mobile phones in ten European countries, first, grouped in four different regions (North: Finland and UK; South: Spain and Italy; East: Hungary and Poland; West: France, Belgium, Germany, and Switzerland), and second by country, and (b) how socio-demographics, geographic differences, mobile phone usage patterns, and associated activities predicted this perceived dependence. Methods A sample of 2,775 young adults (aged 18-29 years) were recruited in different European Universities who participated in an online survey. Measures included socio-demographic variables, patterns of mobile phone use, and the dependence subscale of a short version of the Problematic Mobile Phone Use Questionnaire (PMPUQ; Billieux, Van der Linden, & Rochat, 2008). Results The young adults from the Northern and Southern regions reported the heaviest use of mobile phones, whereas perceived dependence was less prevalent in the Eastern region. However, the proportion of highly dependent mobile phone users was more elevated in Belgium, UK, and France. Regression analysis identified several risk factors for increased scores on the PMPUQ dependence subscale, namely using mobile phones daily, being female, engaging in social networking, playing video games, shopping and viewing TV shows through the Internet, chatting and messaging, and using mobile phones for downloading-related activities. Discussion and conclusions Self-reported dependence on mobile phone use is influenced by frequency and specific application usage. [less ▲]

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See detailBacArena: Individual-Based Metabolic Modeling of Heterogeneous Microbes in Complex Communities
Bauer, Eugen UL; Zimmermann, Johannes; Baldini, Federico UL et al

in PLoS Computational Biology (in press)

Recent advances focusing on the metabolic interactions within and between cellular populations, have emphasized the importance of microbial communities for human health. Constraint-based modeling, with ... [more ▼]

Recent advances focusing on the metabolic interactions within and between cellular populations, have emphasized the importance of microbial communities for human health. Constraint-based modeling, with flux balance analysis in particular, has been established as a key approach for studying microbial metabolism, whereas individual-based modeling has been commonly used to study complex dynamics between interacting organisms. In this study, we combine both techniques into the R package BacArena (https://cran.r-project.org/package=BacArena), to generate novel biological insights into Pseudomonas aeruginosa biofilm formation as well as a seven species model community of the human gut. For our P. aeruginosa model, we found that cross-feeding of fermentation products cause a spatial differentiation of emerging metabolic phenotypes in the biofilm over time. In the human gut model community, we found that spatial gradients of mucus glycans are important for niche formations, which shape the overall community structure. Additionally, we could provide novel hypothesis concerning the metabolic interactions between the microbes. These results demonstrate the importance of spatial and temporal multi-scale modeling approaches such as BacArena. [less ▲]

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See detailAutomated Test Case Generation as a Many-Objective Optimisation Problem with Dynamic Selection of the Targets
Panichella, Annibale UL; Kifetew, Fitsum; Tonella, Paolo

in IEEE Transactions on Software Engineering (in press)

The test case generation is intrinsically a multi-objective problem, since the goal is covering multiple test targets (e.g., branches). Existing search-based approaches either consider one target at a ... [more ▼]

The test case generation is intrinsically a multi-objective problem, since the goal is covering multiple test targets (e.g., branches). Existing search-based approaches either consider one target at a time or aggregate all targets into a single fitness function (whole-suite approach). Multi and many-objective optimisation algorithms (MOAs) have never been applied to this problem, because existing algorithms do not scale to the number of coverage objectives that are typically found in real-world software. In addition, the final goal for MOAs is to find alternative trade-off solutions in the objective space, while in test generation the interesting solutions are only those test cases covering one or more uncovered targets. In this paper, we present DynaMOSA (Dynamic Many-Objective Sorting Algorithm), a novel many-objective solver specifically designed to address the test case generation problem in the context of coverage testing. DynaMOSA extends our previous many-objective technique MOSA (Many-Objective Sorting Algorithm) with dynamic selection of the coverage targets based on the control dependency hierarchy. Such extension makes the approach more effective and efficient in case of limited search budget. We carried out an empirical study on 346 Java classes using three coverage criteria (i.e., statement, branch, and strong mutation coverage) to assess the performance of DynaMOSA with respect to the whole-suite approach (WS), its archive-based variant (WSA) and MOSA. The results show that DynaMOSA outperforms WSA in 28% of the classes for branch coverage (+8% more coverage on average) and in 27% of the classes for mutation coverage (+11% more killed mutants on average). It outperforms WS in 51% of the classes for statement coverage, leading to +11% more coverage on average. Moreover, DynaMOSA outperforms its predecessor MOSA for all the three coverage criteria in 19% of the classes with +8% more code coverage on average. [less ▲]

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See detailThe European Center of Science Productivity: Research Universities and Institutes in France, Germany, and the United Kingdom
Powell, Justin J W UL; Dusdal, Jennifer UL

in Powell, Justin J W; Baker, David P; Fernandez, Frank (Eds.) The Century of Science: The Global Triumph of the Research University (in press)

Growth in scientific productivity over the 20th century resulted significantly from three major countries in European science—France, Germany, and the United Kingdom. We chart the development of ... [more ▼]

Growth in scientific productivity over the 20th century resulted significantly from three major countries in European science—France, Germany, and the United Kingdom. We chart the development of universities and research institutes that bolster Europe’s key position in global science. We uncover both stable and dynamic patterns of productivity in the fields of STEM, including health, over the twentieth century. On-going internationalization of higher education and science has been accompanied by increasing competition and collaboration. Despite policy goals to foster innovation and expand research capacity, policies cannot fully account for the differential growth of scientific productivity we chart from 1975 to 2010. Our neoinstitutional framework facilitates explanation of differences in institutional settings, organizational forms, and organizations that produce the most European research. We measure growth of published peer-reviewed articles indexed in Thomson Reuters’ Science Citation Index Expanded (SCIE). Organizational forms vary in their contributions, with universities accounting for nearly half but rising in France; ultrastable in Germany at four-fifths, and growing at around two-thirds in the UK. Differing institutionalization pathways created the conditions necessary for continuous, but varying growth in scientific productivity in the European center of global science. The research university is central in all three countries, and we identify organizations leading in research output. Few analyses explicitly compare across time, space, and different levels of analysis. We show how important European science has been to overall global science productivity. In-depth comparisons, especially the organizational fields and forms in which science is produced, are crucial if policy is to support research and development. [less ▲]

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See detailThe Century of Science: The Global Triumph of the Research University
Powell, Justin J W UL; Baker, David P.; Fernandez, Frank

Book published by Emerald (in press)

In The Century of Science, a multicultural, international team of authors examines the global rise of scholarly research in science, technology, engineering, mathematics, and health (STEM+) fields. At the ... [more ▼]

In The Century of Science, a multicultural, international team of authors examines the global rise of scholarly research in science, technology, engineering, mathematics, and health (STEM+) fields. At the beginning of the 20th century, the global center-point of scientific productivity was about half way between Western Europe and the U.S., in the North Atlantic. Then, the center moved steadily westward and slightly southward—reflecting the burgeoning science capacity of the U.S. supported by America’s thriving public and private universities, technological innovation, and overall economic growth. After WWII, this began to change as the course of the world’s scientific center of gravity turned and for the next 70 years traveled eastward, the direction it still travels, especially due to the rise of China and other prolific East Asian countries, such as Japan, Taiwan, and South Korea. Europe continues to be the center of global science. Focusing on these developments, this volume provides historical and sociological understandings of the ways that higher education has become an institution that, more than ever before, shapes science and society. Case studies, supported by the most historically and spatially extensive database on STEM+ publications available, of selected countries in Europe, North America, East Asia, and the Middle East, emphasize recurring themes: the institutionalization and differentiation of higher education systems to the proliferation of university-based scientific research fostered by research policies that support continued university expansion leading to the knowledge society. Growing worldwide, research universities appear to be the most legitimate sites for knowledge production. Countries like France, Germany, the United Kingdom, the United States, and Japan began the 20th century with prerequisites in place to realize the emerging model of university-based research. Over the past several decades, China, South Korea, and Taiwan, with different historical legacies and conflicts in education and research policy, have witnessed explosive growth, sustained by public and private funds. Qatar recently embarked on an ambitious government-driven effort to develop a world-class university sector and cultivate academic STEM+ research from scratch. These more recent entrants to the global scientific enterprise pose the question whether it is possible to leapfrog across decades, or even centuries, of cultivating university systems, to compete globally. Simultaneously with international and regional competition, world-leading science increasingly implies collaboration across cultural and political borders as global scientific production and networking continue to rise exponentially. This volume’s case studies offer new insights into how countries develop the university-based knowledge thought fundamental to meeting social needs and economic demands. Despite repeated warnings that universities would lose in relevance to other organizational forms in the production of knowledge, our findings demonstrate incontrovertibly that universities have become more—not less—important actors in the world of knowledge. The past hundred years have seen the global triumph of the research university. [less ▲]

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See detailIslamic banking development and access to credit
Leon, Florian UL; Weill, Laurent

in Pacific-Basin Finance Journal (in press)

The recent expansion of Islamic banks raises questions on its economic implications. The aim of this paper is to investigate the impact of Islamic banking development on access to credit. We combine data ... [more ▼]

The recent expansion of Islamic banks raises questions on its economic implications. The aim of this paper is to investigate the impact of Islamic banking development on access to credit. We combine data from a unique hand-collected database that covers Islamic banks with firm-level data covering developing and emerging countries over the period of 2006 to 2009. We find that Islamic banking development has overall no impact on credit constraints, while banking development and conventional banking development alleviate obstacles to financing. However Islamic banking development exerts a positive impact on access to credit when conventional banking development is low. Hence we support the view that Islamic banking does not overall alleviate obstacles to financing, but it can act as substitute to conventional banking. [less ▲]

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See detailRESTful API Automated Test Case Generation
Arcuri, Andrea UL

in RESTful API Automated Test Case Generation (in press)

Nowadays, web services play a major role in the development of enterprise applications. Many such applications are now developed using a service-oriented architecture (SOA), where microservices is one of ... [more ▼]

Nowadays, web services play a major role in the development of enterprise applications. Many such applications are now developed using a service-oriented architecture (SOA), where microservices is one of its most popular kind. A RESTful web service will provide data via an API over the network using HTTP, possibly interacting with databases and other web services. Testing a RESTful API poses challenges, as inputs/outputs are sequences of HTTP requests/responses to a remote server. Many approaches in the literature do black-box testing, as the tested API is a remote service whose code is not available. In this paper, we consider testing from the point of view of the developers, which do have full access to the code that they are writing. Therefore, we propose a fully automated white-box testing approach, where test cases are automatically generated using an evolutionary algorithm. Tests are rewarded based on code coverage and fault finding metrics. We implemented our technique in a tool called EVOMASTER, which is open-source. Experiments on two open-source, yet non-trivial RESTful services and an industrial one, do show that our novel technique did automatically find 38 real bugs in those applications. However, obtained code coverage is lower than the one achieved by the manually written test suites already existing in those services. Research directions on how to further improve such approach are therefore discussed. [less ▲]

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See detailMany Independent Objective (MIO) Algorithm for Test Suite Generation
Arcuri, Andrea UL

in Many Independent Objective (MIO) Algorithm for Test Suite Generation (in press)

Automatically generating test suites is intrinsically a multi- objective problem, as any of the testing targets (e.g, statements to exe- cute or mutants to kill) is an objective on its own. Test suite ... [more ▼]

Automatically generating test suites is intrinsically a multi- objective problem, as any of the testing targets (e.g, statements to exe- cute or mutants to kill) is an objective on its own. Test suite generation has peculiarities that are quite di erent from other more regular optimi- sation problems. For example, given an existing test suite, one can add more tests to cover the remaining objectives. One would like the smallest number of small tests to cover as many objectives as possible, but that is a secondary goal compared to covering those targets in the rst place. Furthermore, the amount of objectives in software testing can quickly become unmanageable, in the order of (tens/hundreds of) thousands, es- pecially for system testing of industrial size systems. Traditional multi- objective optimisation algorithms can already start to struggle with just four or ve objectives to optimize. To overcome these issues, di erent techniques have been proposed, like for example the Whole Test Suite (WTS) approach and the Many-Objective Sorting Algorithm (MOSA). However, those techniques might not scale well to very large numbers of objectives and limited search budgets (a typical case in system test- ing). In this paper, we propose a novel algorithm, called Many Indepen- dent Objective (MIO) algorithm. This algorithm is designed and tailored based on the speci c properties of test suite generation. An empirical study, on a set of arti cial and actual software, shows that the MIO al- gorithm can achieve higher coverage compared to WTS and MOSA, as it can better exploit the peculiarities of test suite generation. [less ▲]

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See detailEVOSUITE at the SBST 2017 Tool Competition
Fraser, Gordon; Rojas, Jos´e Miguel; Campos, Jos´e et al

in International Workshop on SEARCH-BASED SOFTWARE TESTING (SBST) (in press)

EVOSUITE is a search-based tool that automatically generates unit tests for Java code. This paper summarises the results and experiences of EVOSUITE’s participation at the fifth unit testing competition ... [more ▼]

EVOSUITE is a search-based tool that automatically generates unit tests for Java code. This paper summarises the results and experiences of EVOSUITE’s participation at the fifth unit testing competition at SBST 2017, where EVOSUITE achieved the highest overall score. [less ▲]

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See detailGenerating Unit Tests with Structured System Interactions
Havrikov, Nikolas; Gambi, Alessio; Zeller, Andreas et al

in Automation of Software Test (AST) (in press)

There is a large body of work in the literature about automatic unit tests generation, and many successful results have been reported so far. However, current approaches target library classes, but not ... [more ▼]

There is a large body of work in the literature about automatic unit tests generation, and many successful results have been reported so far. However, current approaches target library classes, but not full applications. A major obstacle for testing full applications is that they interact with the environment. For example, they establish connections to remote servers. Thoroughly testing such applications requires tests that completely control the interactions between the application and its environment. Recent techniques based on mocking enable the generation of tests which include environment interactions; however, generating the right type of interactions is still an open problem. In this paper, we describe a novel approach which addresses this problem by enhancing search-based testing with complex test data generation. Experiments on an artificial system show that the proposed approach can generate effective unit tests. Compared with current techniques based on mocking, we generate more robust unit tests which achieve higher coverage and are, arguably, easier to read and understand. [less ▲]

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See detailDer Deutschunterricht: Flucht und Vertreibung in der deutschen Literatur
Pavlik, Jennifer UL; Thurn, Nike

Book published by Friedrich Verlag (2018)

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See detailMultiscale Modelling of Damage and Fracture in Discrete Materials Using a Variational Quasicontinuum Method
Rokos, Ondrej; Peerlings, Ron; Beex, Lars UL et al

Scientific Conference (2017, September 05)

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See detailIs Big Data Sufficient for a Reliable Detection of Non-Technical Losses?
Glauner, Patrick UL; Migliosi, Angelo UL; Meira, Jorge Augusto UL et al

in Proceedings of the 19th International Conference on Intelligent System Applications to Power Systems (ISAP 2017) (2017, September)

Non-technical losses (NTL) occur during the distribution of electricity in power grids and include, but are not limited to, electricity theft and faulty meters. In emerging countries, they may range up to ... [more ▼]

Non-technical losses (NTL) occur during the distribution of electricity in power grids and include, but are not limited to, electricity theft and faulty meters. In emerging countries, they may range up to 40% of the total electricity distributed. In order to detect NTLs, machine learning methods are used that learn irregular consumption patterns from customer data and inspection results. The Big Data paradigm followed in modern machine learning reflects the desire of deriving better conclusions from simply analyzing more data, without the necessity of looking at theory and models. However, the sample of inspected customers may be biased, i.e. it does not represent the population of all customers. As a consequence, machine learning models trained on these inspection results are biased as well and therefore lead to unreliable predictions of whether customers cause NTL or not. In machine learning, this issue is called covariate shift and has not been addressed in the literature on NTL detection yet. In this work, we present a novel framework for quantifying and visualizing covariate shift. We apply it to a commercial data set from Brazil that consists of 3.6M customers and 820K inspection results. We show that some features have a stronger covariate shift than others, making predictions less reliable. In particular, previous inspections were focused on certain neighborhoods or customer classes and that they were not sufficiently spread among the population of customers. This framework is about to be deployed in a commercial product for NTL detection. [less ▲]

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See detailDiscussant
Greiff, Samuel UL

Scientific Conference (2017, August)

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See detaileXtended Variational Quasicontinuum Methodology for Modelling of Crack Propagation in Discrete Lattice Systems
Rokos, Ondrej; Peerlings, Ron; Zeman, Jan et al

Scientific Conference (2017, July 17)

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See detailAn equation-free multiscale method: a result of extending the quasicontinuum method to irregular structures
Beex, Lars UL; Kerfriden, Pierre

Scientific Conference (2017, July 16)

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