Last 7 days
Bookmark and Share    
Full Text
See detailSpin texture of two-dimensional topological insulators
Rod, Alexia Nibal UL

Doctoral thesis (2017)

Since the discovery of two-dimensional topological insulators a decade ago, their one-dimensional edge states have attracted significant attention due to their unique properties. For example due to time ... [more ▼]

Since the discovery of two-dimensional topological insulators a decade ago, their one-dimensional edge states have attracted significant attention due to their unique properties. For example due to time-reversal symmetry, they are protected against elastic backscattering and they propagate such that electrons with opposite spins move in opposite directions. In fact, the only necessary symmetry to sustain the edge states is time-reversal symmetry. Moreover in experimental setups, the axial spin symmetry seems to be absent. This absence allows new processes to appear such as inelastic backscattering. However, these consequences were neglected in most theoretical works where the spins are considered to be polarized in the z direction. The aim of this thesis is to provide a more realistic model taking into account a broken axial spin symmetry. In this scheme, we show that a rotation of the spin quantization axis as a function of momentum always appears. This observation leads us to develop a deeper understanding of the size of the rotation related to the material parameters and material models, using also realistic values. It also leads us to understand the implications in real space in cases where translation invariance is lost and how to quantify the rotation in such systems. The new processes which arise when the axial spin symmetry is broken have important consequences for transport in real materials. To see this, we consider a Hall bar with a hole in its middle, i.e. an antidot. This enables us to create two tunneling regions in order to probe the effect of this generic model. We also consider the effect of Coulomb interactions around the hole, as they can be important in such geometry. We discover that it is possible to probe directly the absence of axial spin symmetry. As experimental evidence is important to investigate our theoretical findings, we propose spectroscopic means to probe the spin texture. Finally, we also consider one of the experimentally-known candidate materials, namely InAs/GaSb heterostructures. From the k.p Hamiltonian, it is possible to show that their bandstructure shows some anisotropies. The latter is also reflected in the spin texture of their edge states. [less ▲]

Detailed reference viewed: 13 (4 UL)
Full Text
Peer Reviewed
See detailYoung children capitalising on their entire language repertoire for language learning at school
Kirsch, Claudine UL

in Language, Culture and Curriculum (2017)

While translanguaging has been well researched in bilingual settings with older pupils and has been found to contribute to cognitive and personal development, there is little research on translanguaging ... [more ▼]

While translanguaging has been well researched in bilingual settings with older pupils and has been found to contribute to cognitive and personal development, there is little research on translanguaging of young multilinguals. In trilingual Luxembourg, at school, children learn Luxembourgish aged 4, German aged 6 and French aged 7, with the majority not speaking Luxembourgish on school entry. The number of languages to be learned may leave teachers little space to capitalise on home languages and encourage translanguaging. Drawing on qualitative methods, this paper contextualises and examines the practice and purposes of translanguaging of nursery and primary school children who speak a language other than Luxembourgish at home, while they collaboratively produce oral texts on the iPad app iTEO. The data stem from a longitudinal study using a multi-method approach. The findings indicate that the children made use of their multilingual repertoire in order to communicate, construct knowledge and mark their multilingual identity. Translanguaging was a frequent and legitimate practice in both classes although the older children drew less on home languages other than Luxembourgish. The children’s ability to translanguage and their opportunities for doing so were influenced by the multilingual learning environment, the curriculum and the language learning tasks. [less ▲]

Detailed reference viewed: 19 (6 UL)
See detailInvestigation of the Nuclear Function of Tes, an Actin-Binding LIM Protein and Potential Tumor Suppressor
Vaccaroli, Raffaella UL

Doctoral thesis (2017)

The nucleus and the actin cytoskeleton are two distinct components of the eukaryotic cell. While the actin cytoskeleton is a dynamic structure that confers a high degree of cellular mobility as well as a ... [more ▼]

The nucleus and the actin cytoskeleton are two distinct components of the eukaryotic cell. While the actin cytoskeleton is a dynamic structure that confers a high degree of cellular mobility as well as a connection to the extracellular environment, the nucleus contains the genome and is strongly associated with gene expression from the steps of signal transduction to the actual transcription and the resulting translation. Although both components were initially studied separately, the ever-growing knowledge has lately asserted that they are tightly connected. In line, multitude of actin binding proteins were found to have roles in the nucleus, in addition to their well described roles in the cytoplasm. This research work focuses on the actin cytoskeleton protein Tes and its role in the nucleus. Tes is considered as a tumor suppressor protein, since its expression is reduced in different types of cancer cell lines and primary tumors, while its re-expression inhibits various aspects of cancer progression such as invasiveness and metastasis. As a cytoskeletal protein, Tes has been associated with actin polymerization as well as with cell migration and cell spreading. Our results show that, in addition to its cytoplasmic localization, Tes is localized in the nucleus. Artificial size increase of Tes, using a tag based on multiple GFP proteins, allowed us to assign Tes nuclear import to an active mechanism. Through fluorescence microscopy analysis of different modular fragments of Tes, we demonstrated that its PET and LIM1/2 domains are required for its nuclear localization. We also identified a classical monopartite nuclear localization signal (NLS) harbored within its PET domain, required for Tes import in the nucleus. In addition to Tes nuclear import, we also examined its nuclear export. Using the drug Leptomycin B, we demonstrated that Tes nuclear export is active and dependent on the CRM1-export mechanism. By combining protein sequence analysis with point mutations, we identified and characterized the nuclear export signal (NES) at the N-terminus of Tes. Using a photoconvertible probe, we demonstrated the presence of a slower photoconverted fraction of Tes in the nucleus, compared to the more dynamic cytoplasmic fraction. This prompted us to investigate further the existence of potential nuclear partners of Tes. Quantitative mass spectrometry analysis provided evidence for a potential involvement of Tes in nuclear pathways mediating the remodeling of actin, thus suggesting a novel role for Tes in the reorganization of the nuclear actin cytoskeleton. Furthermore, the proteomics studies associated the nuclear localization of Tes with signaling pathways promoting inflammation and cellular death. These results raised the hypothesis that Tes might promote tumor suppression not only through its cytoplasmic functions, but also through these newly described pathways connected to its nuclear localization. Further investigation will be necessary to fully elucidate the function of Tes in the nuclear compartment. [less ▲]

Detailed reference viewed: 12 (5 UL)
Full Text
Peer Reviewed
See detailTESMA: Requirements and Design of a Tool for Educational Programs
Guelfi, Nicolas UL; Jahic, Benjamin UL; Ries, Benoît UL

in Information (2017)

Defining and managing teaching programs at universities or other institutions is a complex task for which there is not much support in terms of methods and tools. This task becomes even more critical when ... [more ▼]

Defining and managing teaching programs at universities or other institutions is a complex task for which there is not much support in terms of methods and tools. This task becomes even more critical when the time comes to obtain certifications w.r.t. official standards. In this paper, we present an on-going project called TESMA, whose objective is to provide an open-source tool dedicated to the specification and management (including certification) of teaching programs. An in-depth market analysis regarding related tools and conceptual frameworks of the project is presented. This tool has been engineered using a development method called Messir for its requirements elicitation and introduces a domain-specific language dedicated to the teachin [less ▲]

Detailed reference viewed: 35 (21 UL)
Peer Reviewed
See detailDigital Work and the Role of Online Platforms. The Need for an Indirect Approach
Ratti, Luca UL

Scientific Conference (2017, March 22)

Detailed reference viewed: 18 (0 UL)
Full Text
See detailWhat makes Data Science different? A discussion involving Statistics2.0 and Computational Sciences
Ley, Christophe; Bordas, Stéphane UL

E-print/Working paper (2017)

Data Science is today one of the main buzzwords be it in business, industrial or academic settings. Machine learning, experimental design, data-driven modelling are all, undoubtedly, rising disciplines if ... [more ▼]

Data Science is today one of the main buzzwords be it in business, industrial or academic settings. Machine learning, experimental design, data-driven modelling are all, undoubtedly, rising disciplines if one goes by the soaring number of research papers and patents appearing each year. The prospect of becoming a ``Data Scientist'' appeals to many. A discussion panel organised as part of the European Data Science Conference (European Association for Data Science (EuADS)) asked the question: ``What makes Data Science different?'' In this paper we give our own, personal and multi-facetted view on this question, from an engineering and a statistics perspective. In particular, we compare Data Science to Statistics and discuss the connection between Data Science and Computational Science. [less ▲]

Detailed reference viewed: 118 (18 UL)
See detailEchos d'Eco
Freyermuth, Sylvie UL

Presentation (2017, March 20)

Nul n’ignore la grande érudition d’Umberto Eco ni sa curiosité ouvrant son esprit aux plus vastes horizons. C’est pour cette raison que je me suis intéressée aux jeux d’échos qui résonnent dans son œuvre ... [more ▼]

Nul n’ignore la grande érudition d’Umberto Eco ni sa curiosité ouvrant son esprit aux plus vastes horizons. C’est pour cette raison que je me suis intéressée aux jeux d’échos qui résonnent dans son œuvre, tout comme à ceux qui peuplent les créations artistiques qui lui rendent hommage. Qu’il s’agisse de littérature, de cinéma, de linguistique, entre autres domaines, les champs qu’explore Eco se construisent en réseaux qui montrent quel prix il a attaché aux œuvres ouvertes. Ce constat me permettra d’organiser ma conférence-projection autour de la question de l’intertextualité (au sens large), en prenant l’exemple du roman Le Nom de la rose, afin de nous diriger en amont vers les Fictions de Borges et en aval vers l’adaptation cinématographique de ce « polar » médiéval qu’a réalisée Annaud. [less ▲]

Detailed reference viewed: 4 (0 UL)
See detailCross-border evidence gathering: equality of arms within the EU?
van Wijk, Marloes Chantal UL

Doctoral thesis (2017)

The European Union (EU) has set the objective to develop an Area of Freedom, Security and Justice, in which on the one hand freedom of movement is promoted and on the other hand a high level of security ... [more ▼]

The European Union (EU) has set the objective to develop an Area of Freedom, Security and Justice, in which on the one hand freedom of movement is promoted and on the other hand a high level of security is ensured. The EU is therefore adopting measures to enhance international cooperation in criminal matters among the police and judicial authorities of its Member States. The adopted instruments concerning evidentiary matters, such as the gathering, freezing and/or confiscation of information and materials in another EU Member State, seem to serve the main purpose of assisting the authorities in investigating and prosecuting (cross-border) crime. This raises the question to what extent the defence is also given the possibility to gather – or to have gathered – information and materials in another EU Member State with the aim of preparing and presenting its case at trial and, in particular, whether the current (EU) legal framework on cross-border evidence gathering meets the requirements of the principle of equality of arms. This thesis addresses this question by, first of all, discussing the concept of equality of arms, as enshrined in both Article 6 ECHR and Article 47 CFR. It explains to what extent this principle is applicable to cross-border or transnational criminal proceedings and whether it has an autonomous meaning within the EU. In addition, it discusses which requirements can be deduced from the principle in relation to the possibilities of the defence to gather evidence in another EU Member State to prepare and presents its case. Subsequently, the focus is on the development of the European legislation – from both the Council of Europe and the EU – regulating the procedure of cross-border evidence gathering over the last decades. The aim is to explain the position of the defence in this development and to what extent the European legislation gives opportunities to the defence to request the assistance of foreign authorities in obtaining specific information and materials in another EU Member State. In order to understand how the European legislation is applied in practice by the EU Member States, this thesis includes a comparative study of three national jurisdictions: the Netherlands, England and Wales, and Italy. These three jurisdictions each represent a different criminal justice system, either more inquisitorial or adversarial in nature. The comparative study describes how a chosen jurisdiction interprets the principle of equality of arms. Furthermore, it examines to what extent the national jurisdiction allows the defence to carry out independent investigations abroad and how it gives the defence the opportunity to trigger the mechanism of international cooperation and to participate in the requested investigation. Finally, this thesis also includes an analysis of the criminal justice system of the International Criminal Court. In this system evidence gathering depends most of the time on State cooperation and both the Prosecutor and the defence are allowed to conduct independent investigations and seek the assistance of States. It is therefore used as a source of inspiration for potential changes of the EU legislation on cross-border evidence gathering. [less ▲]

Detailed reference viewed: 17 (5 UL)
See detailDas Potenzial fantastischer Literatur im Deutschunterricht
Klose, Anne-Christine UL

Speeches/Talks (2017)

Detailed reference viewed: 5 (1 UL)
Full Text
Peer Reviewed
See detailThe influence of Forced Answering on response behavior in Online Surveys: A reactance effect?
Sischka, Philipp UL; Mergener, Alexandra; Neufang, Kristina Marliese et al

Poster (2017, March 16)

Relevance: Recent studies have shown that the use of the forced answering (FA) option in online surveys results in reduced data. They especially examined that forcing respondents to answer questions in ... [more ▼]

Relevance: Recent studies have shown that the use of the forced answering (FA) option in online surveys results in reduced data. They especially examined that forcing respondents to answer questions in order to proceed through the questionnaire leads to higher dropout rates and lower answer quality. However, no study researched the psychological mechanism behind the correlation of FA on dropout and data quality before. This response behavior has often been interpreted as psychological reactance reaction. So, the Psychological Reactance Theory (PRT) predicts that reactance appears when an individuals’ freedom is threatened and cannot be directly restored. Reactance describes the motivation to restore this loss of freedom. Respondents could experience FA as a loss of freedom, as (s)he is denied the choice to leave a question unanswered. According to PRT, possible reactions in this situation might be to quit survey participation, to fake answers or to show satisficing tendencies. Research content: This study explores the psychological mechanism that effects response behavior in FA condition (compared to non-FA- condition). Our major hypothesis is that forcing respondents to answer will cause reactance, which turns into increasing dropout rates, decreasing answer quality and a satisficing behavior. Methods and Data: We used an online survey-experiment with two conditions (forced and non-forced answering instructions). The sample consists of 914 participants. Throughout the whole questionnaire, a dropout button was implemented on each page. In both conditions, this button led to the same page that fully compliant participants reached at the end of the questionnaire. Reactance was measured with a self-constructed four-item reactance scale. To determine answer quality, we used self-report for faking as well as the analysis of answers to open ended questions. Results: Zero-order effects showed that FA increased state reactance and questionnaire dropout as well as it reduced answer length in open-ended questions. Mediation analysis (Condition -> state reactance -> dropout/answer quality) supported the hypothesis of reactance as an underlying psychological mechanism behind negative FA effects on data quality. Added Value: This is the first study which offers statistical evidence for the often proposed reactance effect influencing response behavior. This offers a base for a deeper psychological reflection of the use of the FA-option. [less ▲]

Detailed reference viewed: 14 (1 UL)
Full Text
See detailCorruption prevention in respect of Members of Parliament, Judges and Prosecutors- Evaluation Report Switzerland
Poirier, Philippe UL

Report (2017)

In a report published, the Council of Europe anti-corruption body (GRECO) highlights the specificities of Switzerland’s institutions which enjoy considerable public confidence. It underlines, however ... [more ▼]

In a report published, the Council of Europe anti-corruption body (GRECO) highlights the specificities of Switzerland’s institutions which enjoy considerable public confidence. It underlines, however, that the very organisation of the system allows subtle pressure to be exerted on politicians and the judiciary (See also the French, German and Italian versions of the report). More specifically, GRECO deems it necessary to increase members of parliament’s (MPs) awareness regarding issues of ethics and conflicts of interest. To this end, it recommends adopting a code, announcing publicly MPs’ conflicts of interest as part of the parliamentary procedure and developing the system for declaring relevant interests. These measures need to be accompanied by a reinforced monitoring of MPs’ compliance with their obligations. While recognising the legitimacy of the principle of the election of judges of the federal courts by the Federal Assembly, GRECO calls for improvements to better ensure the quality and objectivity of the recruitment of these judges. It also underlines the importance of severing ties with the political powers after their election, notably by doing away with the practice of judges paying part of their salary to “their” party. Rules of professional ethics applicable to judges also need to be developed and a transparent disciplinary system put in place. The Office of the Attorney General of the Confederation, which enjoys a large degree of independence, also needs to develop rules of professional ethics applicable to its members and to provide greater transparency in disciplinary matters. The implementation of the 12 recommendations addressed to Switzerland will be assessed by GRECO in the second half of 2018 through its compliance procedure. [less ▲]

Detailed reference viewed: 9 (0 UL)
Full Text
See detailIntegration of the analysis of non-functional properties in Model-Driven Engineering for embedded systems
Brau, Guillaume Sylvain Denis UL

Doctoral thesis (2017)

The engineering of embedded systems relies on two complementary activities: modeling on the one hand enables to represent the system, analysis on the other hand makes it possible to evaluate the various ... [more ▼]

The engineering of embedded systems relies on two complementary activities: modeling on the one hand enables to represent the system, analysis on the other hand makes it possible to evaluate the various non-functional properties (for example, temporal properties with the real-time scheduling analysis). This thesis deals with the integration between these models and analyses: how to apply an analysis on a model? How to manage the analysis process? The first part of this thesis presents a comprehensive approach to answer these questions. This approach is based on four application layers: (1) models to represent the system, (2) accessors to extract data from a model, (3) analyses to compute output data and/or properties from input data (4) contracts to represent the analysis interfaces and orchestrate the analysis process. The second part of this thesis deals with the experimentation of this approach with concrete systems coming from the aerospace: a drone, an exploratory robot and a flight management system. We demonstrate that the accessors enable to apply various real-time scheduling analyses on heterogeneous architectural models, for example written with the industry standard AADL (Architecture Analysis and Design Language) or the new time-triggered language CPAL (Cyber-Physical Action Language). In addition, contracts make it possible to automate complex analysis procedures: which analysis can be applied on a given model? Which are the analyses that meet a given goal? Are there analyses to be combined? Are there interferences between analyses? Etc. [less ▲]

Detailed reference viewed: 29 (7 UL)
Full Text
Peer Reviewed
See detailMonolithic modeling and finite element analysis of piezoelectric energy harvesters
Ravi, Srivathsan UL; Zilian, Andreas UL

in Acta Mechanica (2017)

This paper is devoted to monolithic modeling of piezoelectric energy harvesting devices. From a modeling perspective, piezoelectric energy harvesting is a strongly coupled phenomenon with two-way coupling ... [more ▼]

This paper is devoted to monolithic modeling of piezoelectric energy harvesting devices. From a modeling perspective, piezoelectric energy harvesting is a strongly coupled phenomenon with two-way coupling between the electromechanical effect of the piezoelectric material and the harvesting circuit. Even in applications related to shunt damping, where the attached electrical circuit is passive, accurate modeling of the strong coupling is crucial for proper evaluation of the relevant parameters. The article proposes a monolithic mixed-hybrid finite element formulation for the predictive modeling and simulation of piezoelectric energy harvesting devices. The governing equations of the coupled electromechanical problem are converted into a single integral form with six independent unknown fields. Such a holistic approach provides consistent solution to the coupled field equations which involve structural dynamics, electromechanical effect of the piezoelectric patches and the dynamics of the attached harvesting circuit. This allows accurate computation of the eigenvalues and corresponding mode shapes of a harvester for any finite resistive load coupled to the harvester. The fully three-dimensional mixed-hybrid formulation is capable of analyzing structures with non-uniform geometry and varying material properties. The results of the finite element model are verified against the analytical results of a bimorph harvester with tip mass reported in the literature. [less ▲]

Detailed reference viewed: 24 (11 UL)