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See detailQuantification of Stable Isotope Traces Close to Natural Enrichment in Human Plasma Metabolites Using Gas Chromatography-Mass Spectrometry
Krämer, Lisa; Jäger, Christian UL; Trezzi, Jean-Pierre UL et al

in Metabolites (2018), 8(1), 15

Currently, changes in metabolic fluxes following consumption of stable isotope-enriched foods are usually limited to the analysis of postprandial kinetics of glucose. Kinetic information on a larger ... [more ▼]

Currently, changes in metabolic fluxes following consumption of stable isotope-enriched foods are usually limited to the analysis of postprandial kinetics of glucose. Kinetic information on a larger diversity of metabolites is often lacking, mainly due to the marginal percentage of fully isotopically enriched plant material in the administered food product, and hence, an even weaker 13C enrichment in downstream plasma metabolites. Therefore, we developed an analytical workflow to determine weak 13C enrichments of diverse plasma metabolites with conventional gas chromatography-mass spectrometry (GC-MS). The limit of quantification was increased by optimizing (1) the metabolite extraction from plasma, (2) the GC-MS measurement, and (3) most importantly, the computational data processing. We applied our workflow to study the catabolic dynamics of 13C-enriched wheat bread in three human subjects. For that purpose, we collected time-resolved human plasma samples at 16 timepoints after the consumption of 13C-labeled bread and quantified 13C enrichment of 12 metabolites (glucose, lactate, alanine, glycine, serine, citrate, glutamate, glutamine, valine, isoleucine, tyrosine, and threonine). Based on isotopomer specific analysis, we were able to distinguish catabolic profiles of starch and protein hydrolysis. More generally, our study highlights that conventional GC-MS equipment is sufficient to detect isotope traces below 1% if an appropriate data processing is integrated. [less ▲]

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See detailThe RAE/REF have engendered evaluation selectivity and strategic behaviour, reinforced scientific norms, and further stratified UK higher education
Marques, Marcelo UL; Powell, Justin J W UL; Zapp, Mike UL et al

Article for general public (2018)

The UK’s periodic research assessment exercise has grown larger and more formalised since its first iteration in 1986. Marcelo Marques, Justin J.W. Powell, Mike Zapp and Gert Biesta have examined what ... [more ▼]

The UK’s periodic research assessment exercise has grown larger and more formalised since its first iteration in 1986. Marcelo Marques, Justin J.W. Powell, Mike Zapp and Gert Biesta have examined what effects it has had on the submitting behaviour of institutions, considering the intended and unintended consequences in the field of education research. Findings reveal growing strategic behaviour, including high selectivity of submitted staff, the reinforcement of scientific norms with respect to the format and methodological orientation of submitted research outputs, and an explicit concentration of funding. [less ▲]

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See detailLanguage and nationality attitudes as distinct factors that influence speaker evaluations: Explicit versus implicit attitudes in Luxembourg
Lehnert, Tessa Elisabeth UL; Krolak, Sabine UL; Hörstermann, Thomas UL

in Language & Communication (2018)

Many language attitude models have proposed that attitudes towards a speaker’s linguistic aspects have an influence on evaluations of that speaker. However, only a little attention has been paid to how a ... [more ▼]

Many language attitude models have proposed that attitudes towards a speaker’s linguistic aspects have an influence on evaluations of that speaker. However, only a little attention has been paid to how a speaker’s nationality might affect speaker evaluations. We examined whether language and nationality attitudes, on both explicit and implicit levels, are distinct concepts, and whether these attitude types affect speaker evaluations. Findings confirmed the convergent and discriminant validity of language and nationality attitudes, thus confirming their conceptual distinctness. Moreover, explicit language attitudes affected explicit speaker evaluations, a finding that is discussed in the light of its implications for future research. [less ▲]

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See detailSuburbanisation and Suburbanisms – Making Sense of Continental European Developments
Hesse, Markus UL; Siedentop, Stefan

in Raumforschung und Raumordnung (2018)

This paper provides a brief overview of recent developments and debates concerned with suburbanisation in continental Europe. While current discourses in urban research and practice still focus on ... [more ▼]

This paper provides a brief overview of recent developments and debates concerned with suburbanisation in continental Europe. While current discourses in urban research and practice still focus on processes of reurbanisation and the gentrification of inner-city areas, suburbia continues to exist and thrive. Depending on the definition applied, suburban areas still attract a large share of in-migration and employment growth in cities of the developed countries. Given that popular meta-narratives on suburbia and suburbanisation are often spurred by, or refer to, North American suburban studies, we take a different perspective here, one based on continental European trajectories of development in and across city-regional areas that are considered to be suburban, and on social processes that are associated with suburbanisation (suburbanisms). Thus, we aim to avoid a biased understanding of suburbia as a spatial category, which is often considered mono-functional, non-sustainable, or in generic decline. Instead, we observe that suburban variety is huge, and the distinction between urban core and fringe seems to be as ambiguous as ever. The paper, which also introduces the theme of this special issue of “Raumforschung und Raumordnung | Spatial Research and Planning”, bundles our findings along four themes: on suburbia as a place of economic development, on the shifting dynamics of housing between core and fringe locales, on the life-cyclic nature of suburbanisation, and on strategies for redevelopment. Finally, we discuss certain topics that may deserve to be addressed by future research, particularly on the European variant of suburbanisation and suburbs. [less ▲]

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See detailEarly childhood education in Luxembourg and Switzerland
Neumann, Sascha UL

Presentation (2018, February 08)

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See detailThe promise of solution-processed Fe2GeS4 thin films in iron chalcogenide photovoltaics
Liu, Mimi; Berg, Dominik M.; Hwang, Po-Yu et al

in Journal of Materials Science (2018)

The olivine Fe2GeS4, featuring non-toxic elements, cost-effective synthesis, and suitable optoelectronic properties, recently emerged as a promising light-absorbing candidate. Fe2GeS4 precursor powders ... [more ▼]

The olivine Fe2GeS4, featuring non-toxic elements, cost-effective synthesis, and suitable optoelectronic properties, recently emerged as a promising light-absorbing candidate. Fe2GeS4 precursor powders obtained via a simple solutionbased process were converted to highly crystalline Fe2GeS4 powders upon a thermal treatment in controlled atmosphere. Thin films fabricated by dip coating in the Fe2GeS4 precursor dispersion and subjected to the same thermal treatment render high-purity Fe2GeS4 thin films with a band gap of 1.4 eV, measured by room-temperature photoluminescence. Using Fe2GeS4 thin films as the sole absorber in a solution-based solar cell, open-circuit voltages of 361 mV are observed, while the use of the Fe2GeS4 films as counter electrodes in dyesensitized solar cell constructs enhances the overall power conversion efficiency of the cell by a factor of five. This is the first report of a photovoltaic device based on Fe2GeS4. [less ▲]

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See detailThe value of education among immigrants and non-immigrants and how this translates into educational aspirations: a comparison of four European countries
Hadjar, Andreas UL; Scharf, Jan UL

in Journal of Ethnic and Migration Studies (2018), early online

Starting out from the frequent empirical finding that immigrants exhibit higher educational aspirations than non-immigrants, we analyse the role of immigrants’ value of education, i.e. the subjective ... [more ▼]

Starting out from the frequent empirical finding that immigrants exhibit higher educational aspirations than non-immigrants, we analyse the role of immigrants’ value of education, i.e. the subjective belief that education is beneficial for one’s life, in idealistic and realistic educational aspirations in four distinct institutional settings, comparing Sweden, Germany, the Netherlands and England. While the first part of the analyses relates to how immigrants differ from non-immigrants in the value they assign to education, the second part centres on country differences considering immigrant integration policies and education systems as crucial factors. A third part relates to the links between the value of education and educational aspirations to gain some insight into how the value of education may contribute to educational decisions. Analyses are based on longitudinal data of the Children of Immigrants Longitudinal Survey in Four European Countries (CILS4EU). While results show that immigrants assign a higher value to education, the value of education does play a minor role in idealistic and realistic educational aspirations. The results of the country comparison are rather ambivalent, including very weak support for the argument that immigrants strive for education to a higher extent in countries with less favourable conditions. [less ▲]

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See detailMicrofluidic Tensiometry Technique for the Characterization of the Interfacial Tension between Immiscible Liquids.
Honaker, Lawrence William UL; Lagerwall, Jan UL; Jampani, Venkata UL

in Langmuir (2018)

The interfacial tension between two immiscible fluids is of critical importance for understanding many natural phenomena as well as in industrial production processes; however, it can be challenging to ... [more ▼]

The interfacial tension between two immiscible fluids is of critical importance for understanding many natural phenomena as well as in industrial production processes; however, it can be challenging to measure this parameter with high accuracy. Most commonly used techniques have significant shortcomings because of their reliance on other data such as density or viscosity. To overcome these issues, we devise a technique that works with very small sample quantities and does not require any data about either fluid, based on micropipette aspiration techniques. The method facilitates the generation of a droplet of one fluid inside of the other, followed by immediate in situ aspiration of the droplet into a constricted channel. A modified Young-Laplace equation is then used to relate the pressure needed to produce a given deformation of the droplet's radius to the interfacial tension. We demonstrate this technique on different systems with interfacial tensions ranging from sub-millinewton per meter to several hundred millinewton per meter, thus over 4 orders of magnitude, obtaining precise results in agreement with the literature solely from experimental observations of the droplet deformation. [less ▲]

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See detailConservation Laws Shape Dissipation
Rao, Riccardo UL; Esposito, Massimiliano UL

in New Journal of Physics (2018), 20

Starting from the most general formulation of stochastic thermodynamics—i.e. a thermodynamically consistent nonautonomous stochastic dynamics describing systems in contact with several reservoirs —we ... [more ▼]

Starting from the most general formulation of stochastic thermodynamics—i.e. a thermodynamically consistent nonautonomous stochastic dynamics describing systems in contact with several reservoirs —we define a procedure to identify the conservative and the minimal set of nonconservative contributions in the entropy production. The former is expressed as the difference between changes caused by time-dependent drivings and a generalized potential difference. The latter is a sum over the minimal set of flux-force contributions controlling the dissipative flows across the system. When the system is initially prepared at equilibrium (e.g. by turning off drivings and forces), a finite-time detailed fluctuation theorem holds for the different contributions. Our approach relies on identifying the complete set of conserved quantities and can be viewed as the extension of the theory of generalized Gibbs ensembles to nonequilibrium situations. [less ▲]

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See detailIdentification and Characterization of Variant Intolerant Sites across Human Protein 3-Dimensional Structures
Iqbal, Sumaiya; Berg Jespersen, Jakob; Perez-Palma, Eduardo et al

in Biophysical Journal (2018, February 02), 114(3, Suppl. 1), 664

The functional interpretation of genetic variation in disease-associated genes is far outpaced by data generation. Existing algorithms for prediction of variant consequences do not adequately distinguish ... [more ▼]

The functional interpretation of genetic variation in disease-associated genes is far outpaced by data generation. Existing algorithms for prediction of variant consequences do not adequately distinguish pathogenic variants from benign rare variants. This lack of statistical and bioinformatics analyses, accompanied by an ever-increasing number of identified variants in biomedical research and clinical applications, has become a major challenge. Established methods to predict the functional effect of genetic variation use the degree of amino acid conservation across species in linear protein sequence alignment. More recent methods include the spatial distribution pattern of known patient and control variants. Here, we propose to combine the linear conservation and spatial constrained based scores to devise a novel score that incorporates 3-dimensional structural properties of amino acid residues, such as the solvent-accessible surface area, degree of flexibility, secondary structure propensity and binding tendency, to quantify the effect of amino acid substitutions. For this study, we develop a framework for large-scale mapping of established linear sequence-based paralog and ortholog conservation scores onto the tertiary structures of human proteins. This framework can be utilized to map the spatial distribution of mutations on solved protein structures as well as homology models. As a proof of concept, using a homology model of the human Nav1.2 voltage-gated sodium channel structure, we observe spatial clustering in distinct domains of mutations, associated with Autism Spectrum Disorder (>20 variants) and Epilepsy (>100 variants), that exert opposing effects on channel function. We are currently characterizing all variants (>300k individuals) found in ClinVar, the largest disease variant database, as well as variants identified in >140k individuals from general population. The variant mapping framework and our score, informed with structural information, will be useful in identifying structural motifs of proteins associated with disease risk. [less ▲]

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See detailWho Decides What? Judicial Deference in International Economic Adjudication
Fahner, Johannes Hendrik UL

Presentation (2018, February 01)

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See detailReligionsunterricht in Luxemburg aus diskurstheoretischer Sicht: eine spannende Geschichte und eine spannungsvolle Zukunft
Weber, Jean-Marie UL

in Jean, Ehret; Zeien, Jean-Louis (Eds.) Herausforderung Religion(en) und Schule(n) (2018)

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See detailOn the effect of grains interface parameters on the macroscopic properties of polycrystalline materials
Akbari, Ahmad; Kerfriden, Pierre; Bordas, Stéphane UL

in Computers & Structures (2018), 196

In this paper, the influence of microscopic parameters on the macroscopic behaviour of polycrystalline materials under different loading configuration is investigated. Linear elastic grains with zero ... [more ▼]

In this paper, the influence of microscopic parameters on the macroscopic behaviour of polycrystalline materials under different loading configuration is investigated. Linear elastic grains with zero thickness cohesive interfaces are considered at the microscale with in depth introduction of effective parameters. A multiscale method based on homogenisation technique is employed to bridge the scales. In order to minimize the homogenisation error, a representative volume element (RVE) of the microscopic structure is statistically determined to be used in the numerical analysis. For each loading condition of the RVE, several numerical examinations are conducted to illustrate the relationship between the microscopic parameters. Finally, the effects of microscopic critical fracture energies, maximum tensile and shear strengths of grain interfaces on the mechanical properties, i.e. stress-strain curve and yield surface at the macroscale are discussed in details. It is shown that macroscopic yield surface and stress strain curves can be used to characterise the microscopic properties. [less ▲]

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See detailLimit theorems for symmetric U-statistics using contractions
Döbler, Christian UL; Peccati, Giovanni UL

E-print/Working paper (2018)

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See detailMultiple crack detection in 3D using a stable XFEM and global optimization
Agathos, Konstantinos; Chatzi, Eleni; Bordas, Stéphane UL

in Computational Mechanics (2018)

A numerical scheme is proposed for the detection of multiple cracks in three dimensional (3D) structures. The scheme is based on a variant of the extended finite element method (XFEM) and a hybrid ... [more ▼]

A numerical scheme is proposed for the detection of multiple cracks in three dimensional (3D) structures. The scheme is based on a variant of the extended finite element method (XFEM) and a hybrid optimizer solution. The proposed XFEM variant is particularly well-suited for the simulation of 3D fracture problems, and as such serves as an efficient solution to the so-called forward problem. A set of heuristic optimization algorithms are recombined into a multiscale optimization scheme. The introduced approach proves effective in tackling the complex inverse problem involved, where identification of multiple flaws is sought on the basis of sparse measurements collected near the structural boundary. The potential of the scheme is demonstrated through a set of numerical case studies of varying complexity. [less ▲]

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See detailContributions to the asymptotic study of Hermite driven processes
Tran, Thi Thanh Diu UL

Doctoral thesis (2018)

This thesis consists of two parts. Part I is an introduction to Hermite processes, Hermite random fields, Fisher information and to the papers constituting the thesis. More precisely, in Section 1 we ... [more ▼]

This thesis consists of two parts. Part I is an introduction to Hermite processes, Hermite random fields, Fisher information and to the papers constituting the thesis. More precisely, in Section 1 we introduce Hermite processes in a nutshell, as well as some of its basic properties. It is the necessary background for the articles [a] and [c]. In Section 2 we consider briefly the multiparameter Hermite random fields and we study some less elementary facts which are used in the article [b]. In section 3, we recall some terminology about Fisher information related to the article [d]. Finally, our articles [a] to [d] are summarised in Section 4. Part II consists of the articles themselves: [a] T.T. Diu Tran (2017): Non-central limit theorem for quadratic functionals of Hermite-driven long memory moving average processes. Stochastic and Dynamics, 18, no. 4. [b] T.T. Diu Tran (2016): Asymptotic behavior for quadratic variations of nonGaussian multiparameter Hermite random fields. Under revision for Probability and Mathematical Statistics. [c] I. Nourdin, T.T. Diu Tran (2017): Statistical inference for Vasicek-type model driven by Hermite processes. Submitted to Stochastic Process and their Applications. [d] T.T. Diu Tran (2017+): Fisher information and multivariate Fouth Moment Theorem. Main results have already been obtained. It should be submitted soon. [less ▲]

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See detailIntegrating User- and System-Centric Perspectives into Collaborative Compound Document Authoring
Klein, Johannes UL

Doctoral thesis (2018)

Computer-supported collaborative work is increasingly common in our professional and personal life. However, the expectations and requirements of the users are frequently neglected when addressing the ... [more ▼]

Computer-supported collaborative work is increasingly common in our professional and personal life. However, the expectations and requirements of the users are frequently neglected when addressing the technological challenges associated with the development of a distributed collaboration system. The proposed collaboration environment employs an integrative approach to distributed compound document authoring, including both a user- and system-centric perspective on collaborative work. An interruption-free, reliable, and responsive shared work environment with a near real-time representation of the work of others is a core expectation from the users. In order to provide these features, a fine-granular, graph-based data representation has been developed to serve as the basis for this approach. The data representing individual compound document elements is partitioned over sets of three distinct nodes in the graph structure. This separation of metadata and payload data enables the precise attribution of editing operations while maintaining an adaptable and extensible data representation. User-specific preferences allow for the individualization of a user's work environment to account for personal preferences, requirements from the current collaboration scenario, or limitations of the employed computer system. Support for complex, data type-specific editing commands is integrated with a concurrent command application and Layered Consistency Management model. This enables a near real-time representation of the work of others, the preservation of the users' editing intentions, and the maintenance of a globally consistent data state. Intra- and inter-document relations retain semantic connections between distinct data structure elements. Together with an element's supplemental data, this related information enables additional, autonomous conflict resolution approaches and facilitates a comprehensive representation of the conflict in case of a manual resolution process. By integrating these functionalities into one coherent system, the users are provided with an unobtrusive, yet reliable and feature-rich distributed work environment able to actively support collaborative compound document authoring. [less ▲]

Detailed reference viewed: 22 (7 UL)