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See detailMomentary Subjective Age is Associated with Perceived and Physiological Stress in the Daily Lives of Old and Very Old Adults
Kornadt, Anna Elena UL; Pauly, Theresa; Schilling, Oliver et al

in Psychology and Aging (in press)

Subjective age, that is the age people feel in relation to their chronological age, can vary on a day-to-day and even momentary basis. Previous long-term and daily-diary studies have shown that elevated ... [more ▼]

Subjective age, that is the age people feel in relation to their chronological age, can vary on a day-to-day and even momentary basis. Previous long-term and daily-diary studies have shown that elevated stress covaries with older subjective age. However, it is an open question whether such links can also be observed at the momentary level within a given day and go beyond self-reports of stress. Moving ahead, we investigated how two indicators of stress (self-reported: perceived stress; physiological: salivary cortisol) are associated with the age people feel on a momentary basis. We examined data from 118 older (Mage = 66.67 years) and 36 very old adults (Mage = 85.92 years) who reported their momentary subjective age and perceived stress and also provided saliva samples up to seven times a day over seven consecutive days. Dynamic structural equation models showed that both higher momentary perceived stress and higher cortisol levels preceding the measurement predicted an older momentary subjective age. In contrast, subjective age at the previous measurement did not predict subsequent stress. These effects were moderated by participant age group and grip strength, albeit not consistently. Our results corroborate and extend earlier findings that both self-reported and physiological stress are important explanatory variables for people’s subjective age variation even on relatively short time scales, and shed light on differential time-ordered dynamics between stress and subjective age in daily life. Findings also inform theoretical models of subjective age that highlight the importance of contextual, momentary influences on how old people feel and help better understand how biological and psychological processes are intertwined in later life. [less ▲]

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See detail„Ich will mein altes Leben zurück“ – Einblicke in die veränderten Beziehungen, Aktivitäten und das Wohlbefinden luxemburgischer Kinder in der Pandemie
Kirsch, Claudine UL; Neumann, Sascha

in Diskurs Kindheits- und Jugendforschung (in press)

The Covid-19 pandemic has changed children's lives. This paper presents the changes during the pandemic of children’s well-being, relationships and everyday activities from the perspective of six to ... [more ▼]

The Covid-19 pandemic has changed children's lives. This paper presents the changes during the pandemic of children’s well-being, relationships and everyday activities from the perspective of six to twelve-year-olds in Luxembourg. The data draw on interviews carried out in 2020 and standardised surveys in 2020 and 2021. The results show that all children were affected by the pandemic but experienced it differently. Many children expressed fears and worries right at the beginning of the pandemic and these emotions intensified over time. Their leisure time activities shifted from more outside to more domestic activities during the pandemic which in our view corresponds to an intermediate “domestication of childhood”. The survey in the summer of 2021 confirms that many of these changes remained or intensified. [less ▲]

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See detailTranslanguaging in frühkindlichen Bildungseinrichtungen in Luxemburg – mehrsprachiges Handeln von Kindern und Pädagoginnen
Kirsch, Claudine UL; Mortini, Simone; Kemp, Valérie UL

in Meier, Jörg; İnci, Dirim; Blaschitz, Verena (Eds.) Handbuch Mehrsprachigkeit (in press)

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See detailWhen the Going Gets Tough, Do the Tough Go Shopping?
Pan, Xiaodan; Dresner, Martin; Mantin, Binyamin UL

in Journal of Business Logistics (in press)

This study examines the impacts of consumer confidence on stockpiling behavior and, subsequently, retail inventory management. We show how stockpiling behavior evolved during the “Great Recession” of 2008 ... [more ▼]

This study examines the impacts of consumer confidence on stockpiling behavior and, subsequently, retail inventory management. We show how stockpiling behavior evolved during the “Great Recession” of 2008-2009 as consumer confidence waned and demonstrate the impact of this development on inventory management. Drawing on the two-segment household inventory theory consisting of non-stockpiling and stockpiling segments, we use a panel dataset (2005-2015) to calibrate household inventory holdings. This dataset then serves as input for a retailer-level case study. Our empirical analysis reveals significant impacts from changing stockpiling behavior. When consumer confidence is low, both stockpiling and non-stockpiling segments respond by reducing weekly consumption rates; however, the stockpiling segment also significantly lengthens the time between shopping trips, and ultimately increases the duration of inventory holdings. These changes to consumption and stockpiling add complexity to inventory planning, requiring retailers to carefully adjust inventory levels to maintain service levels. [less ▲]

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See detailLocal scaling limits of Lévy driven fractional random fields
Pilipauskaite, Vytauté UL; Surgailis, Donatas

in Bernoulli (in press)

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See detailSemiparametric estimation of McKean-Vlasov SDEs
Belomestny, Denis; Pilipauskaite, Vytauté UL; Podolskij, Mark UL

in Annales de l'Institut Henri Poincaré (B) Probabilités et Statistiques (in press)

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See detailWhich Factors Play a Role in Coco Issuance? Evidence from European Banks.
Wolff, Christian UL

in The Journal of Derivatives (2022), (Fall),

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See detailTranslanguaging pedagogy and creative activism for early education in multilingual Luxembourg
Aleksic, Gabrijela UL

Scientific Conference (2022, September 07)

Luxembourg is a highly linguistically and culturally diverse country. In early education, there are 64 % of four-year old children who not speak Luxembourgish at home (MENJE, 2018). From 2017 ... [more ▼]

Luxembourg is a highly linguistically and culturally diverse country. In early education, there are 64 % of four-year old children who not speak Luxembourgish at home (MENJE, 2018). From 2017, multilingual early education is mandatory, which obliges teachers to develop children’s Luxembourgish, familiarizing them with French, and valuing their home languages. Therefore, the present project aimed to: (1) offer an 18-hours professional development (PD) course in translanguaging pedagogy to 40 teachers over 6 months, (2) strengthen home-school collaboration, and (3) support children’s linguistic, socio-emotional, and cognitive development and engagement in the classroom. The results from teacher questionnaires, focus groups, and interviews, showed that there was some positive change regarding the attitudes towards children’s home languages. The interviews with 17 parents indicated that there was a need for more home-school collaboration. The tests in early literacy and numeracy with 23 preschool children over one year, identified that children performed higher in their home languages. The video observations showed that when the teachers used children’s languages in the classroom, this impacted positively their well-being. Following the principles of creative activism, the author produced: (1) the website with over 100 practical activities on how teachers can involve children’s languages and families, (2) the illustrated book Sumak for parents, showing difficulties with integration in a new country, and (3) the illustrated book, Mara’s song for preschool children, showing how Mara finds her way in the new classroom. [less ▲]

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See detailIndicators for assessing the necessity of power system flexibility: a systematic review and literature meta‐analysis
Bhuiyan, Rajon UL; Weissflog, Jan; Schoepf, Michael et al

Scientific Conference (2022, September)

There are different flexibility options to align power systems to volatile feed-in of renewable electricity sources. The flexibility options differ in the dimensions of time, spatiality, and resource type ... [more ▼]

There are different flexibility options to align power systems to volatile feed-in of renewable electricity sources. The flexibility options differ in the dimensions of time, spatiality, and resource type. To make policy decisions on future energy systems, it is necessary to get a top-down indication of how much power system flexibility is needed. With the ongoing energy transition, there is yet no comprehensive overview of indicators that describe which dimension of flexibility will be necessary to what extent for different energy systems. Therefore, this paper provides a first overview of indicators that can be used to assess the necessity of power system flexibility. Thus, we do a systematic literature review to identify indicators that allow us to estimate the necessity of power system flexibility. We conduct a meta-analysis of these indicators and categorize them as indicators that either stand for an increasing or decreasing necessity of power system flexibility. Our paper can help inform policy, assess needed changes to system operations, increase stakeholder acceptance and investor confidence in implementing new technology and measures. [less ▲]

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See detailWho benefits from air service agreements? The case of international air cargo operations
Wu, You UL; Lange, Anne UL; Mantin, Binyamin UL

in Transportation Research Part B: Methodological (2022), 163

Air service agreements between countries spell out diverse provisions, such as reciprocal capacity allocations. We analyze how such agreements, which regulate total capacity in markets, affect total ... [more ▼]

Air service agreements between countries spell out diverse provisions, such as reciprocal capacity allocations. We analyze how such agreements, which regulate total capacity in markets, affect total welfare and its distribution. We consider the interactions between two competing cargo airlines, their end customers, logistics service providers—who serve as intermediaries between the former two agent types—as well as the policy makers. Accounting for demand uncertainty, we model this interaction as a two-stage game. In the first stage, the policy makers coordinate equal capacity allocations to the two asset providers, whereas in the second stage, the asset providers compete over prices in the spot market. Solving the model, we characterize the pricing strategies employed by the two competing capacity-constrained asset providers in the spot market when facing price sensitive demand from end customers. We further analyze the corresponding capacity decisions. We then compare this coordinated competitive setting with a collaborative setting where the two asset providers can (virtually) merge and act as a monopoly. We find that, compared with the monopoly setting, the coordinated duopoly results in lower capacity, lower profits to the asset providers, larger benefits to both end customers and logistics service providers, and overall lower total welfare. These results suggest that policy makers shall hold an open attitude towards a higher level of cooperation among the asset providers. We carry out robustness checks to verify our insights hold with three, rather than two, asset providers, with different demand distributions, when capacity is costly and when asymmetric capacities are allowed in the spot market. [less ▲]

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See detailObfuscating LLVM Intermediate Representation Source Code with NSGA-II
de la Torre, Juan Carlos; Aragó-Jurado, José Miguel; Jareño, Javier et al

in 15th Intl. Conf. on Computational Intelligence in Security for Information Systems (CISIS'22) (2022, September)

With the generalisation of distributed computing paradigms to sustain the surging demands for massive processing and data-analytic capabilities, the protection of the intellectual property tied to the ... [more ▼]

With the generalisation of distributed computing paradigms to sustain the surging demands for massive processing and data-analytic capabilities, the protection of the intellectual property tied to the executed programs transferred onto these remote shared platforms becomes critical. A more and more popular solution to this problem consists in applying obfuscating techniques, in particular at the source code level. Informally, the goal of obfuscation is to conceal the purpose of a program or its logic without altering its functionality, thus preventing reverse-engineering on the program even with the help of computing resources. This allows to protect software against plagiarism, tampering, or finding vulnerabilities that could be used for different kinds of attacks. The many advantages of code obfuscation, together with its low cost, makes it a popular technique. This paper proposes a novel methodology for source code obfuscation relying on the reference LLVM compiler infrastructure that can be used together with other traditional obfuscation techniques, making the code more robust against reverse engineering attacks. The problem is defined as a Multi-Objective Combinatorial Optimization (MOCO) problem, where the goal is to find sequences of LLVM optimizations that lead to highly obfuscated versions of the original code. These transformations are applied to the back-end pseudo- assembly code (i.e., LLVM Intermediate Representation), thus avoiding any further optimizations by the compiler. Three different problem flavours are defined and solved with popular NSGA-II genetic algorithm. The promising results show the potential of the proposed technique. [less ▲]

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See detailRace And Gender Inequalities In Citations And Research Topics In US
Kozlowski, Diego UL; Monroe-White, Thema

Article for general public (2022)

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See detailLe droit à la sauce piquante n°27 - Aout 2022
Hiez, David UL; Laurent, Rémi

in Le droit à la sauce piquante (2022), 27

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See detailMultilingualism as Challenge for Luxembourgish Literary Historiography
Glesener, Jeanne UL

Scientific Conference (2022, July 29)

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See detailMagnetic Guinier Law and Uniaxial Polarization Analysis in Small Angle Neutron Scattering
Malyeyev, Artem UL

Doctoral thesis (2022)

The present PhD thesis is devoted to the development of the use of the magnetic small-angle neutron scattering (SANS) technique for analyzing the magnetic microstructures of magnetic materials. The ... [more ▼]

The present PhD thesis is devoted to the development of the use of the magnetic small-angle neutron scattering (SANS) technique for analyzing the magnetic microstructures of magnetic materials. The emphasis is on the three aspects: (i) analytical development of the magnetic Guinier law; (ii) the application the magnetic Guinier law and of the generalized Guinier-Porod model to the analysis of experimental neutron data on various magnets such as a Nd-Fe-B nanocomposite, nanocrystalline cobalt, and Mn-Bi rare-earth-free permanent magnets; (iii) development of the theory of uniaxial neutron polarization analysis and experimental testing on a soft magnetic nanocrystalline alloy. The conventional “nonmagnetic” Guinier law represents the low-q approximation for the small-angle scattering curve from an assembly of particles. It has been derived for nonmagnetic particle-matrix-type systems and is routinely employed for the estimation of particle sizes in e.g., soft-matter physics, biology, colloidal chemistry, materials science. Here, the extension of the Guinier law is provided for magnetic SANS through the introduction of the magnetic Guinier radius, which depends on the applied magnetic field, on the magnetic interactions (exchange constant, saturation magnetization), and on the magnetic anisotropy-field radius. The latter quantity characterizes the size over which the magnetic anisotropy field is coherently aligned into the same direction. In contrast to the conventional Guinier law, the magnetic version can be applied to fully dense random-anisotropy-type ferromagnets. The range of applicability is discussed and the validity of the approach is experimentally demonstrated on a Nd-Fe-B-based ternary permanent magnet and on a nanocrystalline cobalt sample. Rare-earth-free permanent magnets in general and the Mn-Bi-based ones in particular have received a lot of attention lately due to their application potential in electronics devices and electromotors. Mn-Bi samples with three different alloy compositions were studied by means of unpolarized SANS and by very small-angle neutron scattering (VSANS). It turns out that the magnetic scattering of the Mn-Bi samples is determined by long-wavelength transversal magnetization fluctuations. The neutron data is analyzed in terms of the generalized Guinier-Porod model and the distance distribution function. The results for the so-called dimensionality parameter obtained from the Guinier-Porod model indicate that the magnetic scattering of a Mn$_{45}$Bi$_{55}$ specimen has its origin in slightly shape-anisotropic structures and the same conclusions are drawn from the distance distribution function analysis. Finally, based on Brown’s static equations of micromagnetics and the related theory of magnetic SANS, the uniaxial polarization of the scattered neutron beam of a bulk magnetic material is computed. The theoretical expressions are tested against experimental data on a soft magnetic nanocrystalline alloy, and both qualitative and quantitative correspondence is discussed. The rigorous analysis of the polarization of the scattered neutron beam establishes the framework for the emerging polarized real-space techniques such as spin-echo small-angle neutron scattering (SESANS), spin-echo modulated small-angle neutron scattering (SEMSANS), and polarized neutron dark-field contrast imaging (DFI), and opens up a new avenue for magnetic neutron data analysis on nanoscaled systems. [less ▲]

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See detailL-invariants of Artin motives
Dimitrov, Mladen; Maksoud, Alexandre UL

in Annales mathématiques du Québec (2022)

We compute Benois L-invariants of weight 1 cuspforms and of their adjoint representations and show how this extends Gross’ p-adic regulator to Artin motives which are not critical in the sense of Deligne ... [more ▼]

We compute Benois L-invariants of weight 1 cuspforms and of their adjoint representations and show how this extends Gross’ p-adic regulator to Artin motives which are not critical in the sense of Deligne. Benois’ construction depends on the choice of a regular submodule which is well understood when the representation is p-regular, as it then amounts to the choice of a “motivic” p-refinement. The situation is dramatically different in the p-irregular case, where the regular submodules are parametrized by a flag variety and thus depend on continuous parameters. We are nevertheless able to show in some examples, how Hida theory and the geometry of the eigencurve can be used to detect a finite number of choices of arithmetic and “mixed-motivic” significance. [less ▲]

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See detailPublications and a new project BELONG
Aleksic, Gabrijela UL

Speeches/Talks (2022)

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See detailPRÉSERVE-MOI ! DES JOURNAUX INTIMES À CEUX DE CONFINEMENT DANS LES ARCHIVES DU WEB
Schafer, Valerie UL

in Le Temps des Médias (2022)

Souvent éphémères, les pages personnelles, les blogs et aujourd’hui les écritures de soi et intimes sur les réseaux socio-numériques, jusqu’aux journaux de confinement nés lors de la crise COVID, sont ... [more ▼]

Souvent éphémères, les pages personnelles, les blogs et aujourd’hui les écritures de soi et intimes sur les réseaux socio-numériques, jusqu’aux journaux de confinement nés lors de la crise COVID, sont toutefois partiellement préservés dans les archives du Web. En explorant leur conservation, notamment au sein de la Bibliothèque nationale de France, et les limites et défis que posent ces sources nativement numériques, il s’agit de saisir les enjeux de préservation de ces contenus personnels, intimes, littéraires, vernaculaires, multimédias, mais aussi les possibilités de recherche qu’ils offrent pour l’histoire du numérique et de ses cultures. [less ▲]

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See detailPotentials of sector coupling to improve the resilience of electricity and gas networks
Leinauer, Christina; Hanny, Lisa; Bhuiyan, Rajon UL et al

Scientific Conference (2022, July)

Global warming leads to an increase in extreme weather events that considerably threaten critical infrastructures (e.g., electricity or gas networks). The failure of one critical infrastructure may have ... [more ▼]

Global warming leads to an increase in extreme weather events that considerably threaten critical infrastructures (e.g., electricity or gas networks). The failure of one critical infrastructure may have far-reaching consequences triggering a “cascade of failures” that affects other critical infrastructures. As extreme weather events usually hit affected regions unexpectedly, flexibility in energy systems is key to sustain resilience and rapidly respond to changing conditions, e.g., failed network lines. Hence, we analyze sector coupling (SC) as one option to increase flexibility and exploit synergies between electricity and gas networks. We investigate SC investments that allow for a bi-directional conversion of gas and electricity in the form of gas-fired power plants or power-to-X technologies and their effect on resilience. We propose a two-level market model where, in the upper-level problem, long-term investments in SC technologies are made in anticipation of short-term market clearing as well as uncertain failures and, in the lower-level problem, SC technologies may be activated. We model extreme weather events as a set of discrete scenarios that pose an external risk to the energy system. In our paper, we derive optimal SC investments representing a trade-off between enhancing system resilience and increasing investments. Moreover, we derive optimal SC responses for selected weather events to guide the operation of SC plants under extreme conditions. [less ▲]

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See detailCompte-rendu de l'ouvrage: Fake News & viralité avant Internet. Les lapins du Père- Lachaise et autres légendes médiatiques
Schafer, Valerie UL

in Le Temps des Médias (2022), 38

Recension de l'ouvrage : Roy Pinker, Fake News & viralité avant Internet. Les lapins du Père- Lachaise et autres légendes média- tiques, Paris, CNRS Éditions, 2020, 231 pages.

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