Krichever-Novikov type algebras. Definitions and Results

E-print/Working paper (2018)

Data Protection Directive (EU) 2016/680 for Police and Criminal Justice Authorities

E-print/Working paper (2017)

In May 2018, the EU Data Protection Reform became applicable. In particular the General Data Protection Regulation (EU) 2016/679 (GDPR), which repealed Directive 95/46/EC on 25 May 2018 attracted much ... [more ▼]

In May 2018, the EU Data Protection Reform became applicable. In particular the General Data Protection Regulation (EU) 2016/679 (GDPR), which repealed Directive 95/46/EC on 25 May 2018 attracted much attention, albeit resembling its predecessor. Alongside the GDPR, the Reform encompassed a Directive (EU) 2016/680 establishing rules for the protection of individuals with regard to the processing of personal data by competent authorities for purposes of law enforcement (LED). The LED put forth great achievements in areas that had previously not been regulated by EU law. Therefore, the LED constitutes a major step forward in establishing a comprehensive EU data protection regime, as the first horizontal and legally binding instrument laying down the rules for national and cross-border processing of personal data in the area of law enforcement. Although the LED received way less attention than the GDPR, two main objectives of the Directive are too important to be neglected: the increased level of fundamental rights protection in the area of police and criminal justice, and the improved sharing of personal data between the Member States, as they will be able to rely on uniform data protection rules. The LED is a modern instrument, designed for the processing of personal data by Law Enforcement Authorities (LEAs) in the Digital Age, which is why there is no doubt that instruments such as the Directive are rapidly gaining in importance and visibility: firstly, an increased number of criminal acts is being committed online or with the help of online tools. Perpetrators of crime leave digital traces that may support LEAs in their tasks of crime prevention, detection, investigation and prosecution. Secondly, as perpetrators are becoming more tech-savvy, LEAs turned to new investigative techniques, including big data analytics. The term big data police technologies may include predictive systems that identify people or places suspected of crime, surveillance systems to monitor at-risk areas and search systems to mine data for investigative clues or to develop intelligence nets of helpful data for groups or across communities. Thirdly, EU rules on the processing of personal data by LEAs are undergoing consolidation, with the LED acting as a locomotive. The rules of the LED, which had to be transposed into the national laws of all 28 Member States and the four Schengen Area States (Norway, Iceland, Switzerland and Lichtenstein) by 6 May 2018, benefited from the attention given to the GDPR, as some of the Regulation’s solutions could simply be taken over. However, a number of provisions were developed specifically for the LED. This Article will give a general overview of the LED structure, its scope and briefly present the ten chapters. The second part of the Article will address four distinct features enshrined in the LED, focussing on automated individual decision-making (Article 11), the indirect exercise of data subject rights (Article 17), the obligation for competent authorities to keep logs (Article 25) and the provisions on international transfers (Articles 35-39). It will thereby critically assess the articles and point to both similarities and differences with regard to the GDPR. [less ▲]

Isolation of nucleic acids from low biomass samples: detection and removal of sRNA contaminants

E-print/Working paper (2017)

Sequencing-based analyses of low-biomass samples are known to be prone to misinterpretation due to the potential presence of contaminating molecules derived from laboratory reagents and environments. Due ... [more ▼]

Sequencing-based analyses of low-biomass samples are known to be prone to misinterpretation due to the potential presence of contaminating molecules derived from laboratory reagents and environments. Due to its inherent instability, contamination with RNA is usually considered to be unlikely. Here we report the presence of small RNA (sRNA) contaminants in widely used microRNA extraction kits and means for their depletion. Sequencing of sRNAs extracted from human plasma samples was performed and significant levels of non-human (exogenous) sequences were detected. The source of the most abundant of these sequences could be traced to the microRNA extraction columns by qPCR-based analysis of laboratory reagents. The presence of artefactual sequences originating from the confirmed contaminants were furthermore replicated in a range of published datasets. To avoid artefacts in future experiments, several protocols for the removal of the contaminants were elaborated, minimal amounts of starting material for artefact-free analyses were defined, and the reduction of contaminant levels for identification of bona fide sequences using 'ultra-clean' extraction kits was confirmed. In conclusion, this is the first report of the presence of RNA molecules as contaminants in laboratory reagents. The described protocols should be applied in the future to avoid confounding sRNA studies. [less ▲]

Die allgemeine Lebenszufriedenheit von Schülern in Luxemburg

E-print/Working paper (2017)

Gesundheitsbeschwerden von Schülern in Luxemburg

E-print/Working paper (2017)

Family, Community and Life-Cycle Earnings: Evidence from Siblings and Youth Peers

E-print/Working paper (2017)

L'ethnographie du travail

E-print/Working paper (2017)

Übergewicht bei Schülern in Luxemburg

E-print/Working paper (2017)

3D Printing: The Next 5 years by Claude Wolf – Into the Future engineered by the Zs

E-print/Working paper (2017)

3D Printing: The Next 5 years by Claude Wolf – Into the Future engineered by the Zs The future of 3D Printing or Additive Manufacturing [AM] will be driven by the next generation of engineers who are just ... [more ▼]

3D Printing: The Next 5 years by Claude Wolf – Into the Future engineered by the Zs The future of 3D Printing or Additive Manufacturing [AM] will be driven by the next generation of engineers who are just about to qualify, the Z generation (1994-2010). Do we, educators, know this Z generation? Do we know what motivates them? The Z generation is a generation of digital natives interacting with PCs, iPads, smartphones and the internet since birth, a pragmatic and short term orientated generation. Our prejudice brands them as unprepared and unmotivated, with their 10 second attention spans, but in reality, they have already proven they are creative, determined and hardworking as well as team oriented, when they are given the opportunity. They have understood that 3D printing offers them this opportunity. [less ▲]

Dynamics of Income Rank Volatility: Evidence from Germany and the US

E-print/Working paper (2017)

This paper presents a methodology for comparing income rank volatility profiles over time and across distributions. While most of the existing measures are affected by changes in marginal distributions ... [more ▼]

This paper presents a methodology for comparing income rank volatility profiles over time and across distributions. While most of the existing measures are affected by changes in marginal distributions, this paper proposes a framework that is based on individuals’ relative positions in the distribution, and is neutral in relation to structural changes that occur in the economy. Applying this approach to investigate rank volatility in Germany and the US over three decades, we show that while poorer individuals within both countries are the most volatile, the volatility trend for the middle class in each of these countries differs. [less ▲]

Isogeometric analysis of thin Reissner-Mindlin plates and shells: Locking phenomena and generalized local B-bar method

E-print/Working paper (2017)

We propose a generalized local $\bar{B}$ framework, addressing locking in degenerated Reissner-Mindlin plate and shell formulations in the context of isogeometric analysis. Parasitic strain components are ... [more ▼]

We propose a generalized local $\bar{B}$ framework, addressing locking in degenerated Reissner-Mindlin plate and shell formulations in the context of isogeometric analysis. Parasitic strain components are projected onto the physical space locally, i.e. at the element level, using a least-squares approach. The formulation is general and allows the flexible utilization of basis functions of different order as the projection bases. The present formulation is much cheaper computationally than the global $\bar{B}$ method. Through numerical examples, we show the consistency of the scheme, although the method is not Hu-Washizu variationally consistent. The numerical examples show that the proposed formulation alleviates locking and yields good accuracy for various thicknesses, even for slenderness ratios of $1 \times 10^5$, and has the ability to capture deformations of thin shells using relatively coarse meshes. From the detailed numerical study, it can be opined that the proposed method is less sensitive to locking and mesh distortion. [less ▲]

Notes on the Schwarzian tensor and measured foliations at infinity of quasifuchsian manifolds.

E-print/Working paper (2017)

The boundary at infinity of a quasifuchsian hyperbolic manifold is equiped with a holomorphic quadratic differential. Its horizontal measured foliation $f$ can be interpreted as the natural analog of the ... [more ▼]

The boundary at infinity of a quasifuchsian hyperbolic manifold is equiped with a holomorphic quadratic differential. Its horizontal measured foliation $f$ can be interpreted as the natural analog of the measured bending lamination on the boundary of the convex core. This analogy leads to a number of questions. We provide a variation formula for the renormalized volume in terms of the extremal length $\ext(f)$ of $f$, and an upper bound on $\ext(f)$. \par We then describe two extensions of the holomorphic quadratic differential at infinity, both valid in higher dimensions. One is in terms of Poincar\'e-Einstein metrics, the other (specifically for conformally flat structures) of the second fundamental form of a hypersurface in a "constant curvature" space with a degenerate metric, interpreted as the space of horospheres in hyperbolic space. This clarifies a relation between linear Weingarten surfaces in hyperbolic manifolds and Monge-Amp\`ere equations. Notes aiming at clarifying the relations between different points of view and introducing one new notion, no real result. Not intended to be submitted at this point [less ▲]

Herman Van Rompuy [biography]

E-print/Working paper (2017)

Herman Van Rompuy (b. 1947) is a Belgian and European politician. In his capacity as President of the European Council (2009-2014), he played a key role in the EU's response to the financial crisis and in ... [more ▼]

Herman Van Rompuy (b. 1947) is a Belgian and European politician. In his capacity as President of the European Council (2009-2014), he played a key role in the EU's response to the financial crisis and in the strengthening of the European framework of economic governance. [less ▲]

Research Report

E-print/Working paper (2017)

Who Trade at Better Prices?

E-print/Working paper (2017)

The European Commission’s "Reflection Paper on Harnessing Globalisation"

E-print/Working paper (2017)

The new EC reflection paper on globalisation sets new accents, but contains no major departure from current policy orientations. It takes a clear stand for free trade, while attacking "unfair competition ... [more ▼]

The new EC reflection paper on globalisation sets new accents, but contains no major departure from current policy orientations. It takes a clear stand for free trade, while attacking "unfair competition" and arguing for a "balanced, rules-based and progressive trade and investment agenda". Despite its insistence on a managed globalisation and a fair redistribution of its benefits, its proposals are unlikely to allay domestic anxieties and external criticism. [less ▲]

3. Forschungsbericht zur Weiterentwicklung des Arbeitsqualitätsindexes in Luxemburg

E-print/Working paper (2017)

Der Survey zu dem „Quality of Work Index Luxembourg“ (QoW), der von der Universität Luxemburg und der luxemburgischen Chambre des Salariés entwickelt wurde (Steffgen, Kohl, 2013; Sischka, Steffgen, 2015 ... [more ▼]

Der Survey zu dem „Quality of Work Index Luxembourg“ (QoW), der von der Universität Luxemburg und der luxemburgischen Chambre des Salariés entwickelt wurde (Steffgen, Kohl, 2013; Sischka, Steffgen, 2015, 2016), wurde 2016 bereits zum vierten Mal mittels einer telefonischen Befragung durchgeführt. Ziel des Index ist es, die erlebte Arbeitssituation und -qualität luxemburgischer Arbeitnehmer zu erfassen. Der vorliegende Bericht dokumentiert die psychometrische Testung der Güte des aktuellen Erhebungsinstruments. Dazu erfolgt zunächst eine Beschreibung der für die Skalen genutzten Items, die Überprüfung der internen Konsistenz der jeweiligen Skala mittels verschiedener Reliabilitätsstatistiken (Cronbach’s Alpha, Korrelationsanalysen der Items) sowie Koeffizienten zur Beschreibung der Skalenverteilung. Explorative und konfirmatorische Faktorenanalysen dienen dazu, zu testen, ob die Items auf den a priori festgelegten Faktoren laden und ob sich die unterstellte Faktorenstruktur auch in den Daten zeigt. Außerdem werden die Zusammenhänge der Skalen mittels Korrelationsanalysen überprüft. Die QoW-Skalen werden außerdem auf verschiedene Well-Being-Skalen regressiert, um deren Relevanz für den QoW-Index zu prüfen. Da der QoW Survey teilweise als Panelbefragung durchgeführt wird, wird außerdem geklärt, ob es hinsichtlich demographischer Eigenschaften der Befragten, hinsichtlich der QoW-Skalen oder hinsichtlich verschiedener Well-Being-Maße zu systematischen Ausfällen seit der letzten Welle gekommen ist. Ebenso werden einige Längsschnitt-Regressionsanalysen gerechnet, um zu überprüfen, ob einige Arbeitsbedingungen längerfristige Effekte auf das Well-Being der Arbeitnehmer aufweisen. Abschließend wird das gesamte Erhebungsinstrument zusammenfassend diskutiert und Empfehlungen bezüglich der weiteren Entwicklung der Skalen gegeben. [less ▲]

La restructuration des dettes publiques saisie par le droit de l'Union européenne

E-print/Working paper (2017)

En juillet 2015, le sommet de la zone euro fait part de l'existence de "sérieux doutes" sur le caractère soutenable de la dette grecque. La possibilité d'un reprofilage de la dette est envisagé et sa ... [more ▼]

En juillet 2015, le sommet de la zone euro fait part de l'existence de "sérieux doutes" sur le caractère soutenable de la dette grecque. La possibilité d'un reprofilage de la dette est envisagé et sa discussion reportée à la réalisation de la première évaluation des mesures d'ajustement mises en oeuvre par la Grèce. Toute décote nominale est cependant formellement exclue, car contraire au droit de l'Union. Les discussions se sont ouvertes au printemps 2016 sur les modalités d'allègement de la dette publique de la Grèce. Le sujet a été au coeur de la réunion de l'Eurogroupe du 22 mai. Aucun accord n'a été trouvé, mais les discussions continuent. Dans ce contexte, Frédéric Allemand a présenté le 17 mai dernier une communication sur la saisine des opérations de restructuration par le droit de l'Union lors du séminaire de recherche pluridisciplinaire "Les administrations publiques à l'épreuve de leur dette" organisé par Jean-François Boudet (Université Paris II) et Caroline Lequesne-Roth (Université de Nice). L'auteur conclut à la compétence de l'Union pour encadrer la restructuration des dettes publiques des États membres. [less ▲]

Gesundheitsverhalten von Arbeitnehmern in Luxemburg

E-print/Working paper (2017)

Insbesonders unter den jüngeren Arbeitnehmern und unter den Arbeitnehmern mit geringer Bildung ist der Anteil der Raucher vergleichsweise hoch. Männliche und ältere Arbeitnehmer weisen wieder einen ... [more ▼]

Insbesonders unter den jüngeren Arbeitnehmern und unter den Arbeitnehmern mit geringer Bildung ist der Anteil der Raucher vergleichsweise hoch. Männliche und ältere Arbeitnehmer weisen wieder einen vergleichsweise hohen Alkoholkonsum auf. Differenziert nach Berufsgruppen zeigen vor allem Arbeitnehmer in Handwerksberufen sowie Manager und Führungskräfte einen hohen Alkoholkonsum. Die Arbeitnehmer in der jüngsten Altersgruppe (16 bis 24 Jährige) schlafen durchschnittlich etwas länger, im Vergleich zu den älteren Arbeitnehmern. Außerdem ist die Sporthäufigkeit in der jüngsten Altersgruppe am höchsten. Männliche Arbeitnehmer sowie Arbeitnehmer ohne Partner oder ohne Kinder treiben ebenfalls überduchschnittlich häufig Sport. Etwa 17% der Arbeitnehmer leidet unter Adipositas. Knapp 30% der Arbeitnehmer leidet manchmal oder häufiger an gesundheitlichen Problemen. Unter den gesundheitlichen Problemen sind Rückenprobleme besonders häufig, gefolgt von Schlafschwierigkeiten und Kopfschmerzen. Herzprobleme sind dagegen eher selten ausgeprägt. Arbeitnehmer mit Hochschulabschluss sowie Manager und Führungskräfte sind seltener von Gesundheitsproblemen betroffen. Gesundheitliche Probleme sind insgesamt mit Zigarettenkonsum, Schlafstunden pro Tag, Sporthäufigkeit und Body Mass Index assoziiert: Je weniger geraucht wird, je mehr geschlafen und Sport getrieben wird und je geringer das körperliche Gewicht der Arbeitnehmer, desto weniger Gesundheitsprobleme liegen tendenziell vor. [less ▲]

Scaling evidence of the homothetic nature of cities

E-print/Working paper (2017)

In this paper we analyse the profile of land use and population density with respect to the distance to the city centre for the European city. In addition to providing the radial population density and ... [more ▼]

In this paper we analyse the profile of land use and population density with respect to the distance to the city centre for the European city. In addition to providing the radial population density and soil-sealing profiles for a large set of cities, we demonstrate a remarkable constancy of the profiles across city size. Our analysis combines the GMES/Copernicus Urban Atlas 2006 land use database at 5m resolu- tion for 300 European cities with more than 100.000 inhabitants and the Geostat population grid at 1km resolution. Population is allocated proportionally to surface and weighted by soil sealing and density classes of the Urban Atlas. We analyse the profile of each artificial land use and population with distance to the town hall. In line with earlier literature, we confirm the strong monocentricity of the European city and the negative exponential curve for population density. Moreover, we find that land use curves, in particular the share of housing and roads, scale along the two horizontal dimensions with the square root of city population, while population curves scale in three dimensions with the cubic root of city population. In short, European cities of different sizes are homothetic in terms of land use and population density. While earlier literature documented the scaling of average densities (total surface and population) with city size, we document the scaling of the whole radial distance profile with city size, thus liaising intra-urban radial analysis and systems of cities. In addition to providing a new empirical view of the European city, our scaling offers a set of practical and coherent definitions of a city, independent of its population, from which we can re-question urban scaling laws and Zipf’s law for cities. [less ▲]

Universal Reasoning, Rational Argumentation and Human-Machine Interaction

E-print/Working paper (2017)

Classical higher-order logic, when utilized as a meta-logic in which various other (classical and non-classical) logics can be shallowly embedded, is well suited for realising a universal logic reasoning ... [more ▼]

Classical higher-order logic, when utilized as a meta-logic in which various other (classical and non-classical) logics can be shallowly embedded, is well suited for realising a universal logic reasoning approach. Universal logic reasoning in turn, as envisioned already by Leibniz, may support the rigorous formalisation and deep logical analysis of rational arguments within machines. A respective universal logic reasoning framework is described and a range of exemplary applications are discussed. In the future, universal logic reasoning in combination with appropriate, controlled forms of rational argumentation may serve as a communication layer between humans and intelligent machines. [less ▲]

Population ageing [glossary]

E-print/Working paper (2017)

Population ageing is a major trend in contemporary European societies. A consequence of welcome shifts in life expectancy and fertility, it nevertheless entails important challenges for the adequacy ... [more ▼]

Population ageing is a major trend in contemporary European societies. A consequence of welcome shifts in life expectancy and fertility, it nevertheless entails important challenges for the adequacy, sustainability, and competitiveness of social and economic systems. [less ▲]

The maximum number of systoles for genus two Riemann surfaces with abelian differentials

E-print/Working paper (2017)

This article explores the length and number of systoles associated to holomorphic $1$-forms on surfaces. In particular, we show that up to homotopy, there are at most $10$ systolic loops on such a genus ... [more ▼]

This article explores the length and number of systoles associated to holomorphic $1$-forms on surfaces. In particular, we show that up to homotopy, there are at most $10$ systolic loops on such a genus two surface and that the bound is realized by a unique translation surface up to homothety. We also provide sharp upper bounds on the the number of homotopy classes of systoles for a holomorphic $1$-form with a single zero in terms of the genus. [less ▲]

Images of Galois representations in mod p Hecke algebras

E-print/Working paper (2017)

Wohlbefinden von Arbeitnehmern in Luxemburg

E-print/Working paper (2017)

Vergleicht man die Teilnehmer der Quality of Work Index Luxembourg Umfrage mit anderen europäischen Arbeitnehmern, zeigen die Teilnehmer aus Luxemburg im Durchschnitt ein geringeres Wohlbefinden ... [more ▼]

Vergleicht man die Teilnehmer der Quality of Work Index Luxembourg Umfrage mit anderen europäischen Arbeitnehmern, zeigen die Teilnehmer aus Luxemburg im Durchschnitt ein geringeres Wohlbefinden. Insbesondere jüngere Arbeitnehmer weisen ein tendenziell geringeres Wohlbefinden auf. Differenziert man die Arbeitnehmer nach Berufsgruppen, zeigen Manager und Führungskräfte, Arbeitnehmer in Dienstleistungsberufen sowie Hilfsarbeitskräfte das höchste Wohlbefinden. Arbeitnehmer mit geringeren faktischen Wochenstundenzahlen sowie Arbeitnehmer, die in kleinen Betrieben (1-4 Beschäftigte) arbeiten, berichten über ein höheres Wohlbefinden. Das Wohlbefinden ist hierbei nachweislich mit unterschiedlichen Arbeitsbedingungen assoziiert. So weisen Arbeitnehmer, je höher ihre Partizipation, ihre Rollenklarheit bei der Arbeit sowie ihre Arbeitsplatzsicherheit ist umso ein höheres Wohlbefinden auf. Das Wohlbefinden ist außerdem positiv mit Arbeitszufriedenheit, wahrgenommenem Respekt bei der Arbeit und negativ mit Stress und Burnout korreliert. [less ▲]

Real-time Error Control for Surgical Simulation

E-print/Working paper (2017)

Real-time simulations are becoming increasingly common for various applications, from geometric design to medical simulation. Two of the main factors concurrently involved in defining the accuracy of ... [more ▼]

Real-time simulations are becoming increasingly common for various applications, from geometric design to medical simulation. Two of the main factors concurrently involved in defining the accuracy of surgical simulations are: the modeling error and the discretization error. Most work in the area has been looking at the above sources of error as a compounded, lumped, overall error. Little or no work has been done to discriminate between modeling error (e.g. needle-tissue interaction, choice of constitutive models) and discretization error (use of approximation methods like FEM). However, it is impossible to validate the complete surgical simulation approach and, more importantly, to understand the sources of error, without evaluating both the discretization error and the modeling error. Our objective is thus to devise a robust and fast approach to measure the discretization error via a posteriori error estimates, which are then used for local remeshing in surgical simulations. To ensure that the approach can be used in clinical practice, the method should be robust enough to deal, as realistically as possible, with the interaction of surgical tools with the organ, and fast enough for real-time simulations. The approach should also lead to an improved convergence so that an economical mesh is obtained at each time step. The final goal is to achieve optimal convergence and the most economical mesh, which will be studied in our future work. [less ▲]

Populism [glossary]

E-print/Working paper (2017)

A chameleonic concept, populism can be defined as an ideology, a communication style, a political strategy, or a misguided category. Its key elements are a positive appreciation of people, a negative view ... [more ▼]

A chameleonic concept, populism can be defined as an ideology, a communication style, a political strategy, or a misguided category. Its key elements are a positive appreciation of people, a negative view of the elite, and the exaltation of untrammeled popular sovereignty against representative democracy and liberal constitutionalism. The fortune of the term, despite its theoretical and practical drawbacks, is the reflection of intrinsic antinomies of modern democracy and of a growing popular dissatisfaction toward the performance of representative governments and institutions. [less ▲]

Institutional Determinants of Early Job Insecurity in Nine European Countries: Country Report Switzerland

E-print/Working paper (2017)

An overview of institutional determinants of early job insecurity in Switzerland.

The Turkish State of Emergency Under Turkish Constitutional Law and International Human Rights Law

E-print/Working paper (2017)

Wealth accumulation over the life course. The role of disadvantages across the employment history

E-print/Working paper (2017)

In this study wealth is employed as an often neglected but highly stratified well-being measure in sociology. I relate the employment history and especially the accumulating disadvantages like ... [more ▼]

In this study wealth is employed as an often neglected but highly stratified well-being measure in sociology. I relate the employment history and especially the accumulating disadvantages like nonemployment and lower occupations to wealth in old age. In particular, I am interested in determining whether an adverse employment history prevents wealth accumulation and which factors influence wealth accumulation across the life course. I use comparative data from the Survey of Health, Ageing and Retirement and combine it with the retrospective panel SHARELIFE to retrieve information about the complete employment history. The relevance of wealth varies significantly across households and in the wider national context. Hence, a contextual perspective is included to account for the difference in wealth rates and wealth inequality in the European countries. The results show that cumulative nonemployment and employment in lower occupations has significant disadvantages for wealth accumulation in old age. However, large differences for men and women persist. Particularly, the household composition and household factors are decisive in the effectuality of these disadvantages. The relation of life course employment and especially disadvantages to accumulated wealth in old aged is stronger in conservative countries than in other welfare regimes. [less ▲]

Liberté de circulation des personnes : citoyenneté de mouvement, citoyenneté en mouvement

E-print/Working paper (2017)

Stein's Overreaction Puzzle: A Note

E-print/Working paper (2017)

Harnack estimates for nonlinear parabolic equations under the Ricci flow

E-print/Working paper (2017)

In this paper, we consider first the Li-Yau Harnack estimates for a nonlinear parabolic equation $\partial_{t}u=\Delta_{t}u-qu -au(\ln u)^{\alpha}$ under the Ricci flow, where $\alpha>0$ is a constant. To ... [more ▼]

In this paper, we consider first the Li-Yau Harnack estimates for a nonlinear parabolic equation $\partial_{t}u=\Delta_{t}u-qu -au(\ln u)^{\alpha}$ under the Ricci flow, where $\alpha>0$ is a constant. To extend these estimates to a more general situation, in the second part, we consider the gradient estimates for a positive solution of the nonlinear parabolic equation $\partial _{t}u=\Delta _{t}u+hu^{p}$ on a Riemannian manifold whose metrics evolve under the geometric flow $\partial _{t}g(t)=-2S_{g(t)}$. To obtain these estimates, we introduce a quantity $\underline{\boldsymbol{S}}$ along the flow which measures whether the tensor $S_{ij}$ satisfies the second contracted Bianchi identity. Under conditions on ${\rm Ric}_{g(t)}, S_{g(t)}$, and $\underline{\boldsymbol{S}}$, we obtain the gradient estimates. [less ▲]

Integrated likelihood based inference for nonlinear panel data models with unobserved effects

E-print/Working paper (2017)

Grenzüberschreitende Alltagspraktiken in der Großregion SaarLorLux

E-print/Working paper (2017)

This paper examines everyday practices carried out by the inhabitants of Saarland, Lorraine, Luxembourg, Rhineland-Palatinate and Wallonia in neighbouring regions abroad. The key consideration here is ... [more ▼]

This paper examines everyday practices carried out by the inhabitants of Saarland, Lorraine, Luxembourg, Rhineland-Palatinate and Wallonia in neighbouring regions abroad. The key consideration here is that the Greater Region SaarLorLux can be defined as a cross-border reality of life based on the cross-border implementation of everyday practices of its inhabitants. In such a socio-constructivist perspective, it is not asked what the Greater Region SaarLorLux is, but in what ways it is constituted or how it manifests itself in the everyday life of its inhabitants. [less ▲]

Bounds for the mod 2 cohomology of GL_2(Z[sqrt(-2)][1/2])

E-print/Working paper (2017)

Documentation TwinLife Data: Cognitive Abilities.

E-print/Working paper (2017)

Zygosity Determination in Twin Studies: A Validation of Zygosity Questionnaires Using DNA in the German TwinLife Study.

E-print/Working paper (2017)

Online deliberation: state of the art

E-print/Working paper (2017)

In the last decade, the issue of online deliberation (or web-deliberation) has gained an important visibility among the scholars in the domain of political science, political philosophy, political ... [more ▼]

In the last decade, the issue of online deliberation (or web-deliberation) has gained an important visibility among the scholars in the domain of political science, political philosophy, political communication as well as software designers. It corresponds not only to a topic of analysis – that can be broadly defined as the quantitative and qualitative assessment of the political and public debates online - but also to a democratic model of e-democracy, that aims to shape the different political usage of the web according to the deliberative values. A pertinent way to analyze this broad phenomenon is to subdivide its analysis in three sections which content is partly based on updated findings of my book Promises and Limits of web-deliberation. The first section refers to the deliberative theory on which the empirical research is based. The second section deals with the complex issue of operationalizing the deliberative theory. The last section provides an overview of the online deliberative empirical studies that were conducted this last decade by distinguishing three broad research fields: i) The studies that aim at measuring the usage of the political web-debates and the characteristics of the users; ii) The studies that identify and compare the social and political actors that offer possibilities of online debates; iii) The studies assessing the quality of deliberation in different discursive online settings and the ones aiming at defining the factors that could explain variations in web-deliberation. [less ▲]

#Soapboxscience – Hochbegabung kommunizieren.

E-print/Working paper (2017)

To MigrateWith orWithout Ones’ Children in China - That is the Question

E-print/Working paper (2017)

Where should Chinese internal migrant parents locate their school-aged children: migrate with them or leave them behind? And should they invest in private education of their children? Empirical evidence ... [more ▼]

Where should Chinese internal migrant parents locate their school-aged children: migrate with them or leave them behind? And should they invest in private education of their children? Empirical evidence based on the 2009 wave of the Rural-Urban Migration Survey in China (RUMiC) data is inconclusive. We use an overlapping generations model to find a theoretical optimum that maximizes parents’ utility which includes the children’s educational performance. Depending on the educational investment parents make and the relocation cost of children, we provide necessary and sufficient conditions for migrant parents to take their children to migrate and whether they should provide their children with private education. As the choices of migrant parents affect not only their children’s human capital accumulation, but also on the economic potential of their descendants, we present both short- and long-term consequences of the parents decision. [less ▲]

Large Portfolio Risk Management and Optimal Portfolio Allocation with Dynamic Elliptical Copulas

E-print/Working paper (2017)

Homotopical algebraic context over differential operators

E-print/Working paper (2017)

Premiers pas dans le métier d'enseignant: quand la langue s'en mêle

E-print/Working paper (2017)

Explaining employers’ hiring decisions: A comparative study of employers’ risk assessment

E-print/Working paper (2017)

In order to investigate the scarring effect of early job insecurity on future employment chances we have implemented a factorial survey experiment with recruiters based on real vacancies in Bulgaria ... [more ▼]

In order to investigate the scarring effect of early job insecurity on future employment chances we have implemented a factorial survey experiment with recruiters based on real vacancies in Bulgaria, Greece, Norway and Switzerland. We contribute to recruitment research at least in three ways: First, the multinational design allows us to run comparative analysis across countries, which are carried out along the national dimensions youth unemployment rate, employment protection regulation and type of educational system. Second, we differentiate between two different forms of early job insecurity – unemployment and work experience in deskilling jobs, and we demonstrate that the sole focus on unemployment, as it is the case in the prevalent labour market research, is not sufficient in order to fully understand labour market outcomes caused by different forms of job insecurities. Third, since our sample consists of real recruiters who were hiring for current jobs at the time when the study was carried out, we provide a unique cross-country data set of high external validity. Our findings suggest that scarring effects of early job insecurity vary across countries and across occupational fields, and while scarring caused by work experience in deskilling jobs seems to be enforced by strong employment protection regulations, unemployment scarring seems to stronger where national unemployment is low. Further, the differences in recruiter’s evaluation across occupational fields indicate that signalling value of education may vary depending on specific sectors. Not at least, we contribute to debates around active labour market policies, arguing that measures aiming at quick labour market reintegration without consideration of job quality may not be the most sustainable solution, as work experience in a deskilling job does not lead to better recruiter’s evaluation. [less ▲]

The Vanishing of Low-Dimensional Cohomology Groups of the Witt and the Virasoro algebra

E-print/Working paper (2017)

A proof of the vanishing of the first and the third cohomology groups of the Witt algebra with values in the adjoint module is given. The proofs given in the present article are completely algebraic and ... [more ▼]

A proof of the vanishing of the first and the third cohomology groups of the Witt algebra with values in the adjoint module is given. The proofs given in the present article are completely algebraic and independent of any underlying topology. They are a generalization of the ones provided by Schlichenmaier, who proved the vanishing of the second cohomology group using purely algebraic methods. In the case of the third cohomology group though, extra difficulties arise and the involved proofs are distinctly more complicated. [less ▲]

Generalized Ricci flow II: Existence for complete noncompact manifolds

E-print/Working paper (2017)

Deformations of pre-symplectic structures and the Koszul L-infty-algebra

E-print/Working paper (2017)

We study the deformation theory of pre-symplectic structures, i.e. closed two-forms of fixed rank. The main result is a parametrization of nearby deformations of a given pre-symplectic structure in terms ... [more ▼]

We study the deformation theory of pre-symplectic structures, i.e. closed two-forms of fixed rank. The main result is a parametrization of nearby deformations of a given pre-symplectic structure in terms of an $L_\infty$-algebra, which we call the Koszul $L_\infty$-algebra. This $L_\infty$-algebra is a cousin of the Koszul dg Lie algebra associated to a Poisson manifold, and its proper geometric understanding relies on Dirac geometry. In addition, we show that a quotient of the Koszul $L_{\infty}$-algebra is isomorphic to the $L_\infty$-algebra which controls the deformations of the underlying characteristic foliation. Finally, we show that the infinitesimal deformations of pre-symplectic structures and of foliations are both obstructed. [less ▲]

Defense semantics of argumentation: encoding reasons for accepting arguments

E-print/Working paper (2017)

In this paper we show how the defense relation among abstract arguments can be used to encode the reasons for accepting arguments. After introducing a novel notion of defenses and defense graphs, we ... [more ▼]

In this paper we show how the defense relation among abstract arguments can be used to encode the reasons for accepting arguments. After introducing a novel notion of defenses and defense graphs, we propose a defense semantics together with a new notion of defense equivalence of argument graphs, and compare defense equivalence with standard equivalence and strong equivalence, respectively. Then, based on defense semantics, we define two kinds of reasons for accepting arguments, i.e., direct reasons and root reasons, and a notion of root equivalence of argument graphs. Finally, we show how the notion of root equivalence can be used in argumentation summarization. [less ▲]

Asymptotic distribution of nodal intersections for arithmetic random waves

E-print/Working paper (2017)