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Institution

University of Luxembourg

EducationLuxembourg, Luxembourg
About: University of Luxembourg is a education organization based out in Luxembourg, Luxembourg. It is known for research contribution in the topics: Population & European union. The organization has 4744 authors who have published 22175 publications receiving 381824 citations.


Papers
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Journal ArticleDOI
TL;DR: A method and a tool called aToucan is proposed, building on existing work, to automatically generate a UML analysis model comprising class, sequence and activity diagrams from a use case model and to automatically establish traceability links between model elements of the use case models and the generated analysis model.
Abstract: The transition from an informal requirements specification in natural language to a structured, precise specification is an important challenge in practice. It is particularly so for object-oriented methods, defined in the context of the OMG's Model Driven Architecture (MDA), where a key step is to transition from a use case model to an analysis model. However, providing automated support for this transition is challenging, mostly because, in practice, requirements are expressed in natural language and are much less structured than other kinds of development artifacts. Such an automated transformation would enable at least the generation of an initial, likely incomplete, analysis model and enable automated traceability from requirements to code, through various intermediate models. In this article, we propose a method and a tool called aToucan, building on existing work, to automatically generate a UML analysis model comprising class, sequence and activity diagrams from a use case model and to automatically establish traceability links between model elements of the use case model and the generated analysis model. Note that our goal is to save effort through automated support, not to replace human abstraction and decision making.Seven (six) case studies were performed to compare class (sequence) diagrams generated by aToucan to the ones created by experts, Masters students, and trained, fourth-year undergraduate students. Results show that aToucan performs well regarding consistency (e.g., 88p class diagram consistency) and completeness (e.g., 80p class completeness) when comparing generated class diagrams with reference class diagrams created by experts and Masters students. Similarly, sequence diagrams automatically generated by aToucan are highly consistent with the ones devised by experts and are also rather complete, for instance, 91p and 97p message consistency and completeness, respectively. Further, statistical tests show that aToucan significantly outperforms fourth-year engineering students in this respect, thus demonstrating the value of automation. We also conducted two industrial case studies demonstrating the applicability of aToucan in two different industrial domains. Results showed that the vast majority of model elements generated by aToucan are correct and that therefore, in practice, such models would be good initial models to refine and augment so as to converge towards to correct and complete analysis models. A performance analysis shows that the execution time of aToucan (when generating class and sequence diagrams) is dependent on the number of simple sentences contained in the use case model and remains within a range of a few minutes. Five different software system descriptions (18 use cases altogether) were performed to evaluate the generation of activity diagrams. Results show that aToucan can generate 100p complete and correct control flow information of activity diagrams and on average 85p data flAow information completeness. Moreover, we show that aToucan outperforms three commercial tools in terms of activity diagram generation.

89 citations

Journal ArticleDOI
TL;DR: In this article, the authors show that the degradation of thin-film chalcogenide kesterite absorbers is universal and that the degraded surface of CZTSe absorbers contains grains of ZnSe.
Abstract: Thin-film chalcogenide kesterites Cu2ZnSnS4 and Cu2 ZnSnSe4 (CZTSSe) are promising candidates for the next-generation thin-film solar cells. They exhibit a high natural abundance of Cu, Zn, Sn and S2, a high absorption coefficient, and a tunable direct bandgap between 1.0 and 1.5 eV. A prerequisite for the use of CZTSSe as absorber layers in photovoltaic applications on large scales is a detailed knowledge of the formation reaction. Recently, we have shown that a decomposition/formation equilibrium governs the formation reaction. The presence of Sn(S,Se) during the high-temperature preparation steps is essential to prevent decomposition. This improves the solar cell efficiency from 0.02% to 6.1%. In this paper, we show that the decomposition is universal. Absorbers produced by high-temperature coevaporation and samples produced by low-temperature precursor fabrication followed by annealing in a tube furnace in S or Se atmosphere are compared in order to elucidate that in all cases, the loss of Sn(S,Se) forms a degraded surface region. We demonstrate that the degraded surface of CZTSe absorbers contains grains of ZnSe. These new insights can be used to explain why some of the synthesis routines described in the literature yield much better efficiencies than others.

88 citations

Journal ArticleDOI
TL;DR: This work shows that inhibition of autophagy is a promising strategy against glioblastoma and identifies ATG9 as a novel target in hypoxia-inducedAutophagy, and combines with hypoxIA-inducing agents may provide benefit by allowing to decrease the effective dose of Autophagy inhibitors.
Abstract: Hypoxia is negatively associated with glioblastoma (GBM) patient survival and contributes to tumour resistance. Anti-angiogenic therapy in GBM further increases hypoxia and activates survival pathways. The aim of this study was to determine the role of hypoxia-induced autophagy in GBM. Pharmacological inhibition of autophagy was applied in combination with bevacizumab in GBM patient-derived xenografts (PDXs). Sensitivity towards inhibitors was further tested in vitro under normoxia and hypoxia, followed by transcriptomic analysis. Genetic interference was done using ATG9A-depleted cells. We find that GBM cells activate autophagy as a survival mechanism to hypoxia, although basic autophagy appears active under normoxic conditions. Although single agent chloroquine treatment in vivo significantly increased survival of PDXs, the combination with bevacizumab resulted in a synergistic effect at low non-effective chloroquine dose. ATG9A was consistently induced by hypoxia, and silencing of ATG9A led to decreased proliferation in vitro and delayed tumour growth in vivo. Hypoxia-induced activation of autophagy was compromised upon ATG9A depletion. This work shows that inhibition of autophagy is a promising strategy against GBM and identifies ATG9 as a novel target in hypoxia-induced autophagy. Combination with hypoxia-inducing agents may provide benefit by allowing to decrease the effective dose of autophagy inhibitors.

88 citations

Journal ArticleDOI
TL;DR: In this article, the symmetry criteria for antiferroelectric (AFE) phase transitions are defined by the local symmetry of the polar crystallographic sites emerging at an AFE phase transition with the macroscopic symmetry.
Abstract: At variance with structural ferroic phase transitions which give rise to macroscopic tensors coupled to macroscopic fields, criteria defining antiferroelectric (AFE) phase transitions are still under discussion due to the absence of specific symmetry properties characterizing their existence. They are recognized by the proximity of a ferroelectric (FE) phase induced under applied electric field, with a double hysteresis loop relating the induced polarization to the electric field and a typical anomaly of the dielectric permittivity. Here, we show that there exist indeed symmetry criteria defining AFE transitions. They relate the local symmetry of the polar crystallographic sites emerging at an AFE phase transition with the macroscopic symmetry of the AFE phase. The dielectric properties of AFE transitions are deduced from a Landau theoretical model in which ferroelectric and ferrielectric phases are shown to stabilize as the result of specific symmetry-allowed couplings of the AFE order parameter with the field-induced polarization.

88 citations

Posted Content
TL;DR: In this article, a sample of German domestic merger and acquisitions (M&As) in the 1990s is analyzed to analyze the importance of a related technology portfolio in the decision to acquire a particular firm.
Abstract: This paper empirically investigates a sample of German domestic merger and acquisitions (M&As) in the 1990s to analyze the importance of a related technology portfolio in the decision to acquire a particular firm. The novelty of this analysis lies in the fact that the sample does not contain exclusively large firms, but also a large share of small and medium-sized entrprises (SMEs). The empirical results suggest that firms engage in M&As to strengthen their technological competencies. A related technology portfolio is, in particular, important for the decision to acquire SMEs. This suggests an information advantage of acquirers with related technologies.

88 citations


Authors

Showing all 4893 results

NameH-indexPapersCitations
Jun Wang1661093141621
Leroy Hood158853128452
Andreas Heinz108107845002
Philippe Dubois101109848086
John W. Berry9735152470
Michael Müller9133326237
Bart Preneel8284425572
Bjorn Ottersten81105828359
Sander Kersten7924623985
Alexandre Tkatchenko7727126863
Rudi Balling7523819529
Lionel C. Briand7538024519
Min Wang7271619197
Stephen H. Friend7018453422
Ekhard K. H. Salje7058119938
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202360
2022250
20211,671
20201,776
20191,710
20181,663