References of "2021"
     in
Bookmark and Share    
Full Text
See detailEssays on the Economics of Forced Displacement and Conflict
Cömertpay, Rana UL

Doctoral thesis (2021)

In Chapter 1, we analyze the determinants of the internal mobility of refugees in Turkey. We track down this mobility relying on geolocalized mobile phone calls data and bring these measures to a micro ... [more ▼]

In Chapter 1, we analyze the determinants of the internal mobility of refugees in Turkey. We track down this mobility relying on geolocalized mobile phone calls data and bring these measures to a micro-founded gravity model in order to estimate the main drivers of refugee mobility across 26 regions in 2017. Our results show that the movements of refugees are sensitive to income differentials and contribute therefore to a more efficient allocation of labor across space. Comparing these findings with those of individuals with a non-refugee status, we find that refugees are more sensitive to variations of income at origin and to distance, while less responsive to changes in income at destination. These findings are robust to the way mobility is inferred from phone data and to the choice of the geographical unit of investigation. Further, we provide evidence against some alternative explanations of mobility such as the propensity to leave refugee camps, transit through Turkey, social magnet effects and sensitivity to agricultural business cycles. In Chapter 2, we exploit annual variations in the presence of refugees to approximate the resulting changes in diversity in the refugee-hosting areas across 23 countries in sub-Saharan Africa. We then assess the relationship between the refugee-corrected diversity indices and the likelihood of conflict between 2005 and 2016. In line with our theoretical framework, the refugee-corrected polarization exacerbates the risk of conflict. A one standard deviation increase in the polarization index raises the incidence of violent conflict by 5 percentage points. Such an effect corresponds to a 10 percent increase, at the mean. The opposite effect is found for the fractionalization index. Our results should not be interpreted as evidence that refugees per se impact the likelihood of violence. Indeed, we do not find any significant correlation between the number of refugees and the occurrence of conflict. Instead, our results point to the risk of conflict when refugees exacerbate ethnic polarization in the hosting communities. On the contrary, a situation where refugee flows raises the level of ethnic fractionalization is likely to see an attenuated risk of violence. This certainly calls for specific interventions in refugee-hosting and polarized communities. We also conduct additional analysis based on individual data and recent COVID-related protests. Results tend to support aggregate results. Refugee-corrected polarization raises the likelihood of experiencing physical assault and interpersonal crime by 2.7 resp. 4.2 percentage points, while no effect can be found for ethnic attachment and trust. Finally, the relevance of our results in the context of the COVID-19 pandemic is explored. In Chapter 3, we study the impact of independent media networks on political accountability during the Arab Spring across the Middle East and North Africa region. The study focuses on two major media networks in the Arab world: Al Jazeera and Al Arabiya. Political accountability is proxied using principally a measure of protests. Data on both political accountability measures and the media networks derive from the Arab Barometer surveys. The regional-level analysis is based on Jordan, Lebanon and Palestine due to data availability. The study uses regional ruggedness as an instrumental variable for the non-random use of independent media among individuals. Results are estimated using a Two-Stage least Squares (2SLS) regression analysis and indicate a positive and significant impact of independent media on political accountability. Several extensions are performed. First, the analysis is replicated for the impact of state media networks and results suggest a significant negative impact on participation to protests. Second, the impact of using independent media for public sector workers' participation to protests is compared with non-public workers. While a significant positive impact of using independent media is found among non-public workers, independent media among public workers seem not to affect their participation to protests. Some channels are tested using additional outcomes such as governmental trust, political alignment, signing petitions and general trust as proxies for political accountability. [less ▲]

Detailed reference viewed: 30 (4 UL)
See detailKeynote: Transnational Families and Childhood throughout the 20th Century
Venken, Machteld UL

Presentation (2021, September 03)

Detailed reference viewed: 111 (1 UL)
Peer Reviewed
See detailLuxembourg Perspectives on Pre-Service Teacher Motivation: What Factors Influence the Choice of Becoming a Teacher, Perseverance and Success?
Rivas, Salvador UL; Poncelet, Débora UL; Reeff, Alain et al

Scientific Conference (2021, September 02)

In 2016, UNESCO estimated that 24.4 million primary school teachers and another 44.4 million secondary school teachers were needed to provide every child in the world access to education. Widespread ... [more ▼]

In 2016, UNESCO estimated that 24.4 million primary school teachers and another 44.4 million secondary school teachers were needed to provide every child in the world access to education. Widespread teacher shortages have led researchers to investigate what motivates candidates to become teachers and to remain in the profession (see for example Watt et al., 2012). Luxembourg is no exception, in 2019 for example, the government wanted to hire 320 new teachers at the fundamental school level; however, only 63 graduates from the country’s main teacher training programme at the University of Luxembourg took the required state exam to join the teaching ranks. The country needs 300 to 400 new fundamental schoolteachers per year to keep up with population growth. To help address this need, we draw on 10 years of admissions data (exam performance and noncognitive indicators) collected from candidates seeking entry to the University of Luxembourg’s teacher training programme. Our study investigates the major correlates, similarities and differences, between candidates that never-registered, i.e., candidates that after being admitted never start the programme; drop-outs, i.e., students that start but never finish; and of course, those that persist until completion. While circumstances may differ between these types of candidates, the first two nevertheless took-up the place that someone else who could have finished and possibly become a teacher. In light of the pressing need for more teachers, this study identifies important factors associated with showing up and staying in the programme until the end. Policy implications are described and discussed. [less ▲]

Detailed reference viewed: 37 (2 UL)
Full Text
Peer Reviewed
See detailTest Case Selection and Prioritization Using Machine Learning: A Systematic Literature Review
Pan, Rongqi; Bagherzadeh, Mojtaba; Ghaleb, Taher et al

in Empirical Software Engineering (2021)

Regression testing is an essential activity to assure that software code changes do not adversely a ect existing functionalities. With the wide adoption of Continuous Integration (CI) in software projects ... [more ▼]

Regression testing is an essential activity to assure that software code changes do not adversely a ect existing functionalities. With the wide adoption of Continuous Integration (CI) in software projects, which increases the frequency of running software builds, running all tests can be time-consuming and resource-intensive. To alleviate that problem, Test case Selection and Prioritiza- tion (TSP) techniques have been proposed to improve regression testing by selecting and prioritizing test cases in order to provide early feedback to developers. In recent years, researchers have relied on Machine Learning (ML) techniques to achieve e ective TSP (ML-based TSP). Such techniques help combine information about test cases, from partial and imperfect sources, into accurate prediction models. This work conducts a systematic literature review focused on ML-based TSP techniques, aiming to perform an in-depth analysis of the state of the art, thus gaining insights regarding fu- ture avenues of research. To that end, we analyze 29 primary studies published from 2006 to 2020, which have been identi ed through a systematic and documented process. This paper addresses ve research questions addressing variations in ML-based TSP techniques and feature sets for training and testing ML models, alternative metrics used for evaluating the techniques, the performance of techniques, and the reproducibility of the published studies. We summarize the results related to our research questions in a high-level summary that can be used as a taxonomy for classifying future TSP studies. [less ▲]

Detailed reference viewed: 55 (0 UL)
Full Text
Peer Reviewed
See detailWarrior candidates: Do voters value combat experience in postwar elections?
Glaurdic, Josip UL; Lesschaeve, Christophe

in Political Research Quarterly (2021)

Electoral competition in postwar societies is often dominated by war veterans. The question whether voters actually reward candidates’ records of war service, however, remains open. We answer it using a ... [more ▼]

Electoral competition in postwar societies is often dominated by war veterans. The question whether voters actually reward candidates’ records of war service, however, remains open. We answer it using a unique dataset with detailed information on the records of combat service of nearly four thousand candidates in two cycles of parliamentary elections held under proportional representation rules with preferential voting in Croatia. Our analysis shows war veterans’ electoral performance to be conditional on the voters’ communities’ exposure to war violence: combat veterans receive a sizeable electoral bonus in areas whose populations were more exposed to war violence, but are penalized in areas whose populations avoided destruction. This divergence is particularly pronounced for candidates of nationalist rightwing parties, demonstrating the importance of the interaction between lived war experiences and political ideology in postwar societies. [less ▲]

Detailed reference viewed: 22 (2 UL)
Full Text
Peer Reviewed
See detailFunctional inequalities on path space of sub-Riemannian manifolds and applications
Cheng, Li Juan UL; Grong, Erlend; Thalmaier, Anton UL

in Nonlinear Analysis (2021), 210(112387), 1-30

We consider the path space of a manifold with a measure induced by a stochastic flow with an infinitesimal generator that is hypoelliptic, but not elliptic. These generators can be seen as sub-Laplacians ... [more ▼]

We consider the path space of a manifold with a measure induced by a stochastic flow with an infinitesimal generator that is hypoelliptic, but not elliptic. These generators can be seen as sub-Laplacians of a sub-Riemannian structure with a chosen complement. We introduce a concept of gradient for cylindrical functionals on path space in such a way that the gradient operators are closable in L^2. With this structure in place, we show that a bound on horizontal Ricci curvature is equivalent to several inequalities for functions on path space, such as a gradient inequality, log-Sobolev inequality and Poincaré inequality. As a consequence, we also obtain a bound for the spectral gap of the Ornstein-Uhlenbeck operator. [less ▲]

Detailed reference viewed: 129 (33 UL)
Full Text
Peer Reviewed
See detailMoral Judgment in Video Games: Effects of Medium, Moral Intuitions and Media-Based Empathy
Grohmann, Lara; Holl, Elisabeth UL; Melzer, André UL

Scientific Conference (2021, September)

Detailed reference viewed: 13 (1 UL)
Full Text
See detailLa Covid-19 vue du Luxembourg: exemple et expérience de l'équipe du Luxembourg Learning Centre
Pausch, Marie-Pierre UL

in Effets et conséquences de la crise sanitaire (2021)

Detailed reference viewed: 40 (1 UL)
Full Text
Peer Reviewed
See detailMeta-Analytic Structural Equation Models of Executive Functions and Math Intelligence in Preschool Children
Emslander, Valentin UL; Scherer, Ronny

Scientific Conference (2021, September)

BACKGROUND: Response inhibition, attention shifting, and working memory updating are the three core executive functions (EFs; Miyake et al., 2000) underlying other cognitive skills that are relevant for ... [more ▼]

BACKGROUND: Response inhibition, attention shifting, and working memory updating are the three core executive functions (EFs; Miyake et al., 2000) underlying other cognitive skills that are relevant for learning and everyday life. For example, they have shown to be differentially related to the mathematical component of intelligence (i.e., math intelligence) in school students and adults. While researchers suppose these three EFs to become more differentiated from early childhood to adulthood, neither the link of these constructs nor their structure has been conclusively established in preschool children yet. Primary studies on path models connecting EFs and math intelligence diverge in the exact relation of EFs and math intelligence. It remains unclear whether inhibition, shifting, and updating exhibit distinct but correlated constructs with respect to their relation to math intelligence. OBJECTIVES: With our meta-analysis, we aimed to (a) synthesize the relation between the three EFs and math intelligence in preschool children; and (b) compare plausible models of the effects of EFs on math intelligence. METHODS/RESULTS: Synthesizing data from 47 studies (363 effect sizes, 30,481 participants) from the last two decades via novel multilevel and multivariate meta-analytic models (Pustejovsky & Tipton, 2020), we found the three core EFs to be significantly related to math intelligence: Inhibition ("r" ̅ = .30, 95 % CI [.25, .35]), shifting ("r" ̅ = .32, 95 % CI [.25, .38]), and updating ("r" ̅ = .36, 95 % CI [.31, .40]). Looking at the three core EFs as one construct, the correlation was "r" ̅ = .34, 95 % CI [.31, .37]. Utilizing correlation-based, meta-analytic structural equation modeling (Jak & Cheung, 2020), our results exhibited significant relations of all EFs to math intelligence. These relations did not differ between the three core EFs. DISCUSSION: Our findings corroborate the positive link between EFs and math intelligence in preschool children and are similar to other age groups. From the model testing, we learned that representing EFs by a latent variable, thus capturing the covariance among the three core EFs, explained substantially more variation in math intelligence than representing them as distinct constructs. [less ▲]

Detailed reference viewed: 91 (1 UL)
See detailIngeborg Bachmanns Simultan und die Frage der Rechtsbindung in Zeiten von Multilingualität und Transkulturalität
Becker, Katrin UL

in Walter, Tonio; Schramm, Edward (Eds.) Dichtung und Wahrheit - und Recht (2021)

Detailed reference viewed: 76 (0 UL)
Full Text
Peer Reviewed
See detailAn Integrative Model of Moral Processing for the Video Game Medium
Melzer, André UL; Holl, Elisabeth UL

Scientific Conference (2021, September)

Detailed reference viewed: 9 (0 UL)
Full Text
Peer Reviewed
See detailQ-Learning-Based SCMA for Efficient Random Access in mMTC Networks With Short Packets
Tran, Duc Dung UL; Sharma, Shree Krishna; Chatzinotas, Symeon UL et al

in Proceedings of 2021 IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (IEEE PIMRC 2021) (2021, September)

In massive machine-type communications (mMTC) networks, the ever-growing number of MTC devices and the limited radio resources have caused a severe problem of random access channel (RACH) congestion. To ... [more ▼]

In massive machine-type communications (mMTC) networks, the ever-growing number of MTC devices and the limited radio resources have caused a severe problem of random access channel (RACH) congestion. To mitigate this issue, several potential multiple access (MA) mechanisms including sparse code MA (SCMA) have been proposed. Besides, the short-packet transmission feature of MTC devices requires the design of new transmission and congestion avoidance techniques as the existing techniques based on the assumption of infinite data-packet length may not be suitable for mMTC networks. Therefore, it is important to find novel solutions to address RACH congestion in mMTC networks while considering SCMA and short-packet communications (SPC). In this paper, we propose an SCMA-based random access (RA) method, in which Q-learning is utilized to dynamically allocate the SCMA codebooks and time-slot groups to MTC devices with the aim of minimizing the RACH congestion in SPC-based mMTC networks. To clarify the benefits of our proposed method, we compare its performance with those of the conventional RA methods with/without Q-learning in terms of RA efficiency and evaluate its convergence. Our simulation results show that the proposed method outperforms the existing methods in overloaded systems, i.e., the number of devices is higher than the number of available RA slots. Moreover, we illustrate the sum rate comparison between SPC and long-packet communications (LPC) when applying the proposed method to achieve more insights on SPC. [less ▲]

Detailed reference viewed: 58 (1 UL)
See detailLa technologie blockchain – et les tendances de la décorporéisation en droit et culture
Becker, Katrin UL

in Pistes. Revue de philosophie contemporaine. Éthique, politique, philosophie des techniques (2021), 1

Detailed reference viewed: 66 (2 UL)
Full Text
Peer Reviewed
See detailThreat Adaptive Byzantine Fault Tolerant State-Machine Replication
Simoes Silva, Douglas UL; Graczyk, Rafal UL; Decouchant, Jérémie et al

Scientific Conference (2021, September)

Critical infrastructures have to withstand advanced and persistent threats, which can be addressed using Byzantine fault tolerant state-machine replication (BFT-SMR). In practice, unattended cyberdefense ... [more ▼]

Critical infrastructures have to withstand advanced and persistent threats, which can be addressed using Byzantine fault tolerant state-machine replication (BFT-SMR). In practice, unattended cyberdefense systems rely on threat level detectors that synchronously inform them of changing threat levels. How- ever, to have a BFT-SMR protocol operate unattended, the state- of-the-art is still to configure them to withstand the highest possible number of faulty replicas f they might encounter, which limits their performance, or to make the strong assumption that a trusted external reconfiguration service is available, which introduces a single point of failure. In this work, we present ThreatAdaptive the first BFT-SMR protocol that is automatically strengthened or optimized by its replicas in reaction to threat level changes. We first determine under which conditions replicas can safely reconfigure a BFT-SMR system, i.e., adapt the number of replicas n and the fault threshold f, so as to outpace an adversary. Since replicas typically communicate with each other using an asynchronous network they cannot rely on consensus to decide how the system should be reconfigured. ThreatAdaptive avoids this pitfall by proactively preparing the reconfiguration that may be triggered by an increasing threat when it optimizes its performance. Our evaluation shows that ThreatAdaptive can meet the latency and throughput of BFT baselines configured statically for a particular level of threat, and adapt 30% faster than previous methods, which make stronger assumptions to provide safety. [less ▲]

Detailed reference viewed: 148 (20 UL)
Full Text
Peer Reviewed
See detailStability of Value-Added Models: Comparing Classical and Machine Learning Approaches
Emslander, Valentin UL; Levy, Jessica UL; Scherer, Ronny et al

Scientific Conference (2021, September)

Background: What is the value that teachers or schools add to the evolution of students’ performance? Value-added (VA) modeling aims to answer this question by quantifying the effect of pedagogical ... [more ▼]

Background: What is the value that teachers or schools add to the evolution of students’ performance? Value-added (VA) modeling aims to answer this question by quantifying the effect of pedagogical actions on students’ achievement, independent of students’ backgrounds (e.g., Braun, 2005). A plethora of VA models exist, and several outcome measures are in use to estimate VA scores, yet without consensus on the model specification (Everson, 2017; Levy et al., 2019). Furthermore, it is unclear whether the most frequently used VA models (i.e., multi-level, linear regression, and random forest models) and outcome measures (i.e., language and mathematics achievement) indicate a similar stability of VA scores over time. Objectives: Drawing from the data of a highly diverse and multilingual school setting, where leveling out the influence of students’ backgrounds is of special interest, we aim to (a) clarify the stability of school VA scores over time; (b) shed light on the sensitivity toward different statistical models and outcome variables; and (c) evaluate the practical implications of (in)stable VA scores for individual schools. Method: Utilizing the representative, longitudinal data from the Luxembourg School Monitoring Programme (LUCET, 2021), we examined the stability of school VA scores. We drew on two longitudinal data sets of students who participated in the standardized achievement tests in Grade 1 in 2014 or 2016 and then again in Grade 3 two years later (i.e., 2016 and 2018, respectively), with a total of 5875 students in 146 schools. School VA scores were calculated using classical approaches (i.e., linear regression and multilevel models) and one of the most commonly used machine learning approaches in educational research (i.e., random forests). Results and Discussion: The overall stability over time across the VA models was moderate, with multilevel models showing greater stability than linear regression models and random forests. Stability differed across outcome measures and was higher for VA models with language achievement as an outcome variable as compared to those with mathematics achievement. Practical implications for schools and teachers will be discussed. [less ▲]

Detailed reference viewed: 174 (3 UL)
See detailDigital Roots. Historicizing Media and Communication Concepts of the Digital Age
Balbi, Gabriele; Ribeiro, Nelson; Schafer, Valerie UL et al

Book published by De Gruyter (2021)

As media environments and communication practices evolve over time, so do theoretical concepts. This book analyzes some of the most well-known and fiercely discussed concepts of the digital age from a ... [more ▼]

As media environments and communication practices evolve over time, so do theoretical concepts. This book analyzes some of the most well-known and fiercely discussed concepts of the digital age from a historical perspective, showing how many of them have pre-digital roots and how they have changed and still are constantly changing in the digital era. Written by leading authors in media and communication studies, the chapters historicize 16 concepts that have become central in the digital media literature, focusing on three main areas. The first part, Technologies and Connections, historicises concepts like network, media convergence, multimedia, interactivity and artificial intelligence. The second one is related to Agency and Politics and explores global governance, datafication, fake news, echo chambers, digital media activism. The last one, Users and Practices, is finally devoted to telepresence, digital loneliness, amateurism, user generated content, fandom and authenticity. The book aims to shed light on how concepts emerge and are co-shaped, circulated, used and reappropriated in different contexts. It argues for the need for a conceptual media and communication history that will reveal new developments without concealing continuities and it demonstrates how the analogue/digital dichotomy is often a misleading one. [less ▲]

Detailed reference viewed: 72 (0 UL)