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See detailIf there’s something strange in your [cyber]hood – who you gonna call?
Schmitz, Sandra UL

Scientific Conference (2022, July 07)

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See detailRezension zu Jonas Springer, Die Bundeswehr und die Belgischen Streikräfte in Deutschland
Brüll, Christoph UL

in Wissenschaftlicher Literaturanzeiger (2022), 61(2),

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See detailCountry-level Variation of Dementia Prevalence in Europe - Comparing OECD and SHARE Data
Klee, Matthias UL; Langa, Kenneth, M.; Leist, Anja UL

Presentation (2022, July 07)

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See detailEnergy Efficiency Optimization for Backscatter Enhanced NOMA Cooperative V2X Communications under Imperfect CSI
Khan, Wali Ullah UL; Jamshed, Muhammad Ali; Lagunas, Eva UL et al

in IEEE Transactions on Intelligent Transportation Systems (2022)

Automotive-Industry 5.0 will use beyond fifth-generation (B5G) technologies to provide robust, computationally intelligent, and energy-efficient data sharing among various onboard sensors, vehicles, and ... [more ▼]

Automotive-Industry 5.0 will use beyond fifth-generation (B5G) technologies to provide robust, computationally intelligent, and energy-efficient data sharing among various onboard sensors, vehicles, and other devices. Recently, ambient backscatter communications (AmBC) have gained significant interest in the research community for providing battery-free communications. AmBC can modulate useful data and reflect it towards near devices using the energy and frequency of existing RF signals. However, obtaining channel state information (CSI) for AmBC systems would be very challenging due to no pilot sequences and limited power. As one of the latest members of multiple access technology, non-orthogonal multiple access (NOMA) has emerged as a promising solution for connecting large-scale devices over the same spectral resources in B5G wireless networks. Under imperfect CSI, this paper provides a new optimization framework for energy-efficient transmission in AmBC enhanced NOMA cooperative vehicle-to-everything (V2X) networks. We simultaneously minimize the total transmit power of the V2X network by optimizing the power allocation at BS and reflection coefficient at backscatter sensors while guaranteeing the individual quality of services. The problem of total power minimization is formulated as non-convex optimization and coupled on multiple variables, making it complex and challenging. Therefore, we first decouple the original problem into two sub-problems and convert the nonlinear rate constraints into linear constraints. Then, we adopt the iterative sub-gradient method to obtain an efficient solution. For comparison, we also present a conventional NOMA cooperative V2X network without AmBC. Simulation results show the benefits of our proposed AmBC enhanced NOMA cooperative V2X network in terms of total achievable energy efficiency. [less ▲]

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See detailThe Multi-Level System of Space Mining: Regulatory Aspects and Enforcement Options
Salmeri, Antonino UL

Doctoral thesis (2022)

Few contests that space mining holds the potential to revolutionize the space sector. The utilization of space resources can reduce the costs of deep space exploration and kick-off an entirely new economy ... [more ▼]

Few contests that space mining holds the potential to revolutionize the space sector. The utilization of space resources can reduce the costs of deep space exploration and kick-off an entirely new economy in our solar system. However, whether such a revolution will happen for good or for worse depends also on the enactment of appropriate regulation. Under the right framework, space mining will be able to deliver on its promise of a new era of prosperous and sustainable space exploration. But with the wrong rules (or lack thereof), unbalanced space resource activities can destabilize the space community to a truly unprecedented scale. With companies planning mining operations on the Moon already during this decade, the regulation of space resource activities has thus become one of the most pressing and crucial topics to be addressed by the global space community. In this context, this thesis provides a first-of-its-kind, comprehensive and innovative analysis of the regulatory and enforcement options currently shaping the multi-level governance of space mining. In addition to this, the thesis also suggests a series of correctives that can improve the system and ensure the peaceful, rational, safe, and sustainable conduct of space mining. Structurally, the thesis moves from general to particular and is divided in three chapters. Chapter 1 discusses the relationship between space law and international law to contextualize the specific assessment of space mining. Chapter 2 analyses the current regulatory framework applicable to space mining, considering both the international and national levels. Finally, Chapter 3 identifies potential enforcement options, assesses them in terms of effectiveness and legitimacy, and further proposes some pragmatic correctives to reinforce the governance system. [less ▲]

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See detailGeneralising from conventional pipelines using deep learning in high‑throughput screening workfows
Garcia Santa Cruz, Beatriz UL; Sölter, Jan; Gomez Giro, Gemma UL et al

in Scientific Reports (2022)

The study of complex diseases relies on large amounts of data to build models toward precision medicine. Such data acquisition is feasible in the context of high-throughput screening, in which the quality ... [more ▼]

The study of complex diseases relies on large amounts of data to build models toward precision medicine. Such data acquisition is feasible in the context of high-throughput screening, in which the quality of the results relies on the accuracy of the image analysis. Although state-of-the-art solutions for image segmentation employ deep learning approaches, the high cost of manually generating ground truth labels for model training hampers the day-to-day application in experimental laboratories. Alternatively, traditional computer vision-based solutions do not need expensive labels for their implementation. Our work combines both approaches by training a deep learning network using weak training labels automatically generated with conventional computer vision methods. Our network surpasses the conventional segmentation quality by generalising beyond noisy labels, providing a 25% increase of mean intersection over union, and simultaneously reducing the development and inference times. Our solution was embedded into an easy-to-use graphical user interface that allows researchers to assess the predictions and correct potential inaccuracies with minimal human input. To demonstrate the feasibility of training a deep learning solution on a large dataset of noisy labels automatically generated by a conventional pipeline, we compared our solution against the common approach of training a model from a small manually curated dataset by several experts. Our work suggests that humans perform better in context interpretation, such as error assessment, while computers outperform in pixel-by-pixel fne segmentation. Such pipelines are illustrated with a case study on image segmentation for autophagy events. This work aims for better translation of new technologies to real-world settings in microscopy-image analysis. [less ▲]

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See detailTransatlantic Chattel Slavery, 1815–1888
Erpelding, Michel UL

in Lovall, Erin; Stefanelli, Justine (Eds.) Reparations Under International Law for Enslavement of African Persons in the Americas and the Caribbean: Proceedings of the Symposium, May 20–21, 2021 (2022, July 06)

This paper addresses the question of the legality and illegality of slavery-related practices during the 19th century under Western international law.

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See detailCentrality and city size effects on NO2 ground and tropospheric concentrations within European cities
Wei, Yufei UL; Caruso, Geoffrey UL; Lemoy, Rémi

Scientific Conference (2022, July 06)

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

Scientific Conference (2022, July 06)

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See detailReductions of algebraic numbers and Artin's conjecture on primitive roots
Sgobba, Pietro UL

Doctoral thesis (2022)

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See detailQuality of Work and Quality of Employment Profiles and their longitudinal impact on well-being
Sischka, Philipp UL; Fernandez de Henestrosa, Martha UL; Steffgen, Georges UL

Scientific Conference (2022, July 06)

Many studies on job quality operationalize job quality as a composite indicator (Munoz de Bustillo et al., 2011) and investigate its link with different well-being outcomes or investigate the incremental ... [more ▼]

Many studies on job quality operationalize job quality as a composite indicator (Munoz de Bustillo et al., 2011) and investigate its link with different well-being outcomes or investigate the incremental effects of specific job characteristics on well-being. However, these variable-centered approaches on job quality ignore the fact that certain job characteristic configurations cluster in specific employee groups (Van Aeren et al., 2014). Thus, the current longitudinal study employs a person-centered approach (i.e., latent profile and transition analysis (LPA/LTA), e.g., Spurk et al., 2020) to identify groups of employees that show different job characteristic profiles (over time). Data were collected via CATI or CAWI within a stratified random sample from Luxembourg’s working population (nWave 1 = 1,689; nWave 2 = 848). The survey contains eleven quality of work and six quality of employment dimensions that were used as indicators for the latent profile analysis. Moreover, the survey contains different mental health and work-related attitudinal outcomes. Fit indices and substantive interpretability/utility were jointly considered to determine the number of profiles. To explore the relationships between the latent categorical variable and the other variables, we followed the three-step procedure (e.g., Asparouhov & Muthén, 2014) LPA revealed five profiles, i.e., poor working conditions (1), medium working conditions, high work intensity (2), high working conditions, medium work intensity (3), high working conditions, high work intensity and physical demands (4), medium working conditions, low work intensity (5). Cross-sectionally, these profiles were meaningfully linked with mental and attitudinal outcomes. LTA suggests the stability of these profiles within one year, with varying impact depending on mental health and work-related attitudinal outcome. Scholars and policy makers need to be aware of job characteristic configurations. To promote employee’s well-being organizations and policy makers need to redesign the ecological contexts of working conditions depending on its profiles. [less ▲]

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See detailEssays on Market Microstructure and Financial Markets Stability
Levin, Vladimir UL

Doctoral thesis (2022)

The present doctoral thesis consists of three main chapters. The chapters of the thesis can be considered independently. Each of the three chapters raises a research question, reviews the related ... [more ▼]

The present doctoral thesis consists of three main chapters. The chapters of the thesis can be considered independently. Each of the three chapters raises a research question, reviews the related literature, proposes a method for the analysis, and, finally, reports results and conclusions. Chapter 1 is entitled Dark Trading and Financial Markets Stability and it is based on a working paper co-authored with Prof. Dr. Jorge Goncalves and Prof. Dr. Roman Kraussl. This paper examines how the implementation of a new dark order -- Midpoint Extended Life Order (M-ELO) on Nasdaq -- impacts financial markets stability in terms of occurrences of mini-flash crashes in individual securities. We use high-frequency order book data and apply panel regression analysis to estimate the effect of dark order trading activity on market stability and liquidity provision. The results suggest a predominance of a speed bump effect of M-ELO rather than a darkness effect. We find that the introduction of M-ELO increases market stability by reducing the average number of mini-flash crashes, but its impact on market quality is mixed. Chapter 2 is entitled Dark Pools and Price Discovery in Limit Order Markets and it is a single-authored work. This paper examines how the introduction of a dark pool impacts price discovery, market quality, and aggregate welfare of traders. I use a four-period model where rational and risk-neutral agents choose the order type and the venue and obtain the equilibrium numerically. The comparative statics on the order submission probability suggests a U-shaped order migration to the dark pool. The overall effect of dark trading on market quality and aggregate welfare was found to be positive but limited in size and depended on market conditions. I find mixed results for the process of price discovery. Depending on the immediacy need of traders, price discovery may change due to the presence of the dark venue. Chapter 3 is entitled Machine Learning and Market Microstructure Predictability and it is another single-authored piece of work. This paper illustrates the application of machine learning to market microstructure research. I outline the most insightful microstructure measures, that possess the highest predictive power and are useful for the out-of-sample predictions of such features of the market as liquidity volatility and general market stability. By comparing the models' performance during the normal time versus the crisis time, I come to the conclusion that financial markets remain efficient during both periods. Additionally, I find that high-frequency traders activity is not able to forecast accurately neither of the market features. [less ▲]

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See detailArbeitnehmer in Luxemburg wünschen sich verstärkt eine Reduktion ihrer vertraglichen Arbeitszeit
Sischka, Philipp UL; Steffgen, Georges UL

E-print/Working paper (2022)

Im Rahmen dieser Newsletter wird aufgezeigt, wie sich die gewünschte Wochenarbeitszeit von Arbeitnehmern sowie die Differenz zwischen gewünschter Wochenarbeitszeit und vertraglicher Wochenarbeitszeit in ... [more ▼]

Im Rahmen dieser Newsletter wird aufgezeigt, wie sich die gewünschte Wochenarbeitszeit von Arbeitnehmern sowie die Differenz zwischen gewünschter Wochenarbeitszeit und vertraglicher Wochenarbeitszeit in den vergangenen Jahren in Luxemburg entwickelt haben. Dabei zeigt sich, dass der Anteil an Arbeitnehmern, die gerne weniger arbeiten würden, zwischen 2018 und 2021 deutlich gestiegen ist (von 32,8% auf 43,9%). Die Arbeitnehmer, die gerne weniger pro Woche arbeiten würden, möchten im Durchschnitt etwa 8 Stunden weniger arbeiten. Diese Entwicklungen fallen jedoch differenziert nach verschiedenen Arbeitnehmer-Gruppen unterschiedlich aus. So wünschen sich Arbeitnehmer im Vergleich zu Arbeitnehmerinnen konstant eine längere Arbeitszeit. Differenziert nach Alter, sind es vor allem die ältesten Arbeitnehmer, die sich im Durchschnitt die kürzeste Wochenarbeitszeit wünschen. Arbeitnehmer, die gerne weniger arbeiten würden, berichten tendenziell auch über schlechtere Arbeitsbedingungen im Vergleich zu Arbeitnehmern, deren gewünschte Arbeitszeit mit ihrer vertraglichen Arbeitszeit übereinstimmt. Auch berichten Arbeitnehmer, die gerne weniger pro Woche arbeiten würden, über ein geringeres Wohlbefinden. [less ▲]

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See detailClimate Risk and Price Jumps
Lehnert, Thorsten UL

Scientific Conference (2022, July 05)

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See detailEconomic Sanctions and International Investment Law: Investor and State Defences
Garcia Olmedo, Javier UL

Scientific Conference (2022, July 04)

This workshop examines the law and practice of economic sanctions in light of current developments in the Ukraine-Russia conflict. It explores the legality and implementation of, and possible challenges ... [more ▼]

This workshop examines the law and practice of economic sanctions in light of current developments in the Ukraine-Russia conflict. It explores the legality and implementation of, and possible challenges to, economic sanctions imposed by a number of international actors (including the US, the EU and the UK), as well as their potential impact on businesses and dispute resolution. [less ▲]

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See detailLa question de la licéité des politiques coloniales au regard du principe du droit intertemporel en droit international public: Texte annoté d’une intervention prononcée le 4 juillet 2022 lors d’une audition devant la Commission spéciale « Passé colonial » de la Chambre des Représentants de Belgique
Erpelding, Michel UL

Diverse speeches and writings (2022)

Delivered at a hearing of the Special Committee on Belgium's Colonial Past of the Belgian Chamber of Representatives, this speech challenges the alleged lawfulness of colonial policies under the ... [more ▼]

Delivered at a hearing of the Special Committee on Belgium's Colonial Past of the Belgian Chamber of Representatives, this speech challenges the alleged lawfulness of colonial policies under the intertemporal law principle in public international law based on two considerations. First, due to the development of the history of international law as a fully fledged discipline, we now have a more granular view of the law applicable to international relations in the past. More particularly, recent studies in the field of the history of international law have shown that many colonial policies (e.g. mass murder of colonized populations, "excessive" forced labour, or even the unilateral imposition of colonial rule) were actually illegal under positive late 19th century international law. Second, a simple mechanical application of the intertemporal law principle is now increasingly understood as impossible to reconcile with the universal character of today's international community, sparking increasing calls in favour of a "decolonization" of this principle in order to rid it of its inherently discriminatory nature. [less ▲]

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See detailNon-Orthogonal Multiple Access for Next-Generation Satellite Systems: Flexibility Exploitation and Resource Optimization
Wang, Anyue UL

Doctoral thesis (2022)

In conventional satellite communication systems, onboard resource management follows pre-design approaches with limited flexibility. On the one hand, this can simplify the satellite payload design. On the ... [more ▼]

In conventional satellite communication systems, onboard resource management follows pre-design approaches with limited flexibility. On the one hand, this can simplify the satellite payload design. On the other hand, such limited flexibility hardly fits the scenario of irregular traffic and dynamic demands in practice. As a consequence, the efficiency of resource utilization could be deteriorated, evidenced by mismatches between offered capacity and requested traffic in practical operations. To overcome this common issue, exploiting multi-dimension flexibilities and developing advanced resource management approaches are of importance for next-generation high-throughput satellites (HTS). Non-orthogonal multiple access (NOMA), as one of the promising new radio techniques for future mobile communication systems, has proved its advantages in terrestrial communication systems. Towards future satellite systems, NOMA has received considerable attention because it can enhance power-domain flexibility in resource management and achieve higher spectral efficiency than orthogonal multiple access (OMA). From ground to space, terrestrial-based NOMA schemes may not be directly applied due to distinctive features of satellite systems, e.g., channel characteristics and limited onboard capabilities, etc. To investigate the potential synergies of NOMA in satellite systems, we are motivated to enrich this line of studies in this dissertation. We aim at resolving the following questions: 1) How to optimize resource management in NOMA-enabled satellite systems and how much performance gain can NOMA bring compared to conventional schemes? 2) For complicated resource management, how to accelerate the decision-making procedure and achieve a good tradeoff between complexity reduction and performance improvement? 3) What are the mutual impacts among multiple domains of resource optimization, and how to boost the underlying synergies of NOMA and exploit flexibilities in other domains? The main contributions of the dissertation are organized in the following four chapters: First, we design an optimization framework to enable efficient resource allocation in general NOMA-enabled multi-beam satellite systems. We investigate joint optimization of power allocation, decoding orders, and terminal-timeslot assignment to improve the max-min fairness of the offered-capacity-to-requested-traffic ratio (OCTR). To solve the mixed-integer non-convex programming (MINCP) problem, we develop an optimal fast-convergence algorithmic framework and a heuristic scheme, which outperform conventional OMA in matching capacity to demand. Second, to accelerate the decision-making procedure in resource optimization, we attempt to solve optimization problems for satellite-NOMA from a machine-learning perspective and reveal the pros and cons of learning and optimization techniques. For complicated resource optimization problems in satellite-NOMA, we introduce deep neural networks (DNN) to accelerate decision making and design learning-assisted optimization schemes to jointly optimize power allocation and terminal-timeslot assignment. The proposed learning-optimization schemes achieve a good trade-off between complexity and performance. Third, from a time-domain perspective, beam hopping (BH) is promising to mitigate the capacity-demand mismatches and inter-beam interference by selectively and sequentially illuminating suited beams over timeslots. Motivated by this, we investigate the synergy and mutual influence of NOMA and BH for satellite systems to jointly exploit power- and time-domain flexibilities. We jointly optimize power allocation, beam scheduling, and terminal-timeslot assignment to minimize the capacity-demand gap. The global optimal solution may not be achieved due to the NP-hardness of the problem. We develop a bounding scheme to tightly gauge the global optimum and propose a suboptimal algorithm to enable efficient resource assignment. Numerical results demonstrate the synthetic synergy of combining NOMA and BH, and their individual performance gains compared to the benchmarks. Fourth, from the spatial domain, adaptive beam patterns can adjust the beam coverage to serve irregular traffic demand and alleviate co-channel interference, motivating us to investigate joint resource optimization for satellite systems with flexibilities in power and spatial domains. We formulate a joint optimization problem of power allocation, beam pattern selection, and terminal association, which is in the format of MINCP. To tackle the integer variables and non-convexity, we design an algorithmic framework and a low-complexity scheme based on the framework. Numerical results show the advantages of jointly optimizing NOMA and beam pattern selection compared to conventional schemes. In the end, the dissertation is concluded with the main findings and insights on future works. [less ▲]

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See detailSelf-regulation of phenotypic noise synchronizes emergent organization and active transport in confluent microbial environments
Dhar, Jayabrata UL; Thai, Le Phuong Anh UL; Ghoshal, Arkajyoti UL et al

in Nature Physics (2022)

The variation associated with different observable characteristics—phenotypes—at the cellular scale underpins homeostasis and the fitness of living systems. However, if and how these noisy phenotypic ... [more ▼]

The variation associated with different observable characteristics—phenotypes—at the cellular scale underpins homeostasis and the fitness of living systems. However, if and how these noisy phenotypic traits shape properties at the population level remains poorly understood. Here we report that phenotypic noise self-regulates with growth and coordinates collective structural organization, the kinetics of topological defects and the emergence of active transport around confluent colonies. We do this by cataloguing key phenotypic traits in bacteria growing under diverse conditions. Our results reveal a statistically precise critical time for the transition from a monolayer biofilm to a multilayer biofilm, despite the strong noise in the cell geometry and the colony area at the onset of the transition. This reveals a mitigation mechanism between the noise in the cell geometry and the growth rate that dictates the narrow critical time window. By uncovering how rectification of phenotypic noise homogenizes correlated collective properties across colonies, our work points at an emergent strategy that confluent systems employ to tune active transport, buffering inherent heterogeneities associated with natural cellular environment settings. [less ▲]

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