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See detailThe Development and Utilization of Scenarios in European Union Energy Policy
Scheibe, Alexander UL

Doctoral thesis (2019)

Scenarios are a strategic planning tool, which essentially enables decision-makers to identify future uncertainties and to devise or adjust organizational strategies. Increasingly, scenario building has ... [more ▼]

Scenarios are a strategic planning tool, which essentially enables decision-makers to identify future uncertainties and to devise or adjust organizational strategies. Increasingly, scenario building has been applied as a planning instrument by public policymakers. At the European Union (EU) level, scenarios are widely used in various policy areas and for different purposes. However, the development and utilization of scenarios in policymaking as well as their concrete impact on the decision process remain an under-explored research field. The academic literature focuses on scenarios in the business domain, where they are a well-established strategic planning component. In public policy, however, the development and use of scenarios conceivably differ from the private sector. In the case of the EU, the potential impact of its distinctive multi-stakeholder and multi-level policymaking environment on the development of scenarios is not sufficiently accounted for in the literature. Moreover, it is uncertain how scenarios are situated in the wider EU political context. This thesis seeks to explain how scenarios are developed and utilized in the EU’s policymaking process. To that end, an institutionalized scenario development exercise from the Union’s energy policy (the Ten-Year Network Development Plan, TYNDP) is investigated as a case study. Drawing from empirical evidence primarily based on elite interviews, the research applies a qualitative-interpretative research framework that combines the analytical concepts of policy networks, epistemic communities, and strategic constructivism. The combination facilitates the design of a theoretical model of inner and outer spheres in EU energy policymaking, accounting for both the role of scenarios in policymaking and the impact of political goals on their development. The research concludes that the wider EU political context of the outer sphere shapes the development of scenarios in the inner sphere and determines how they are utilized in the policymaking process. The expectations of political actors frame the technical expertise in the scenario development process. With regard to the application of scenarios in wider public policy, the research demonstrates that the closer the scenario building is to the decision-making process, the stronger the political impact on the scenarios is likely to be. This is because political actors and decision-makers seek to align the scenario outcomes to their respective preferences. [less ▲]

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See detailA New Optimization Tool for Mega-Constellation Design and its Application to Trunking Systems
Kisseleff, Steven UL; Shankar, Bhavani UL; Spano, Danilo UL et al

in 37th International Communications Satellite Systems Conference (ICSSC), Japan, October 2019 (2019, November)

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See detailUser Terminal Wideband Modem for Very High Throughput Satellites
Kisseleff, Steven UL; Maturo, Nicola UL; Chatzinotas, Symeon UL et al

in 37th International Communications Satellite Systems Conference (ICSSC), Japan, October 2019 (2019, November)

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See detailCharacterization of the MSE Region under a Total Power Budget for Asynchronous Two-Way Relay Networks
Rahimi, Razgar; Shahbazpanahi, Shahram UL; Ottersten, Björn UL

in The Asilomar Conference on Signals, Systems, and Computers, Pacific Grove, CA, 3-6 November 2019 (2019, November)

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See detailPrivacy Aspects and Subliminal Channels in Zcash
Biryukov, Alex UL; Feher, Daniel UL; Vitto, Giuseppe UL

in Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Securit (2019, November)

In this paper we analyze two privacy and security issues for the privacy-oriented cryptocurrency Zcash. First we study shielded transactions and show ways to fingerprint user transactions, including ... [more ▼]

In this paper we analyze two privacy and security issues for the privacy-oriented cryptocurrency Zcash. First we study shielded transactions and show ways to fingerprint user transactions, including active attacks.We introduce two new attacks which we call Danaan-gift attack and Dust attack. Following the recent Sapling update of Zcash protocol we study the interaction between the new and the old zk-SNARK protocols and the effects of their interaction on transaction privacy. In the second part of the paper we check for the presence of subliminal channels in the zk-SNARK protocol and in Pedersen Commitments. We show presence of efficient 70-bit channels which could be used for tagging of shielded transactions which would allow the attacker (malicious transaction verifier) to link transactions issued by a maliciously modified zk-SNARK prover, while would be indistinguishable from regular transactions for the honest verifier/user. We discuss countermeasures against both of these privacy issues. [less ▲]

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See detailComparing Academic Languages: German, English, French
Huemer, Birgit UL; Deroey, Katrien UL; Lejot, Eve UL

Presentation (2019, October 30)

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See detailTHE MARKET SKEWNESS-RETURN RELATIONSHIP
Lehnert, Thorsten UL

Presentation (2019, October 29)

The observed negative relationship between market skewness and excess return or the negative price of market skewness risk in the cross-section of stock returns is somewhat counterintuitive when we ... [more ▼]

The observed negative relationship between market skewness and excess return or the negative price of market skewness risk in the cross-section of stock returns is somewhat counterintuitive when we consider the usual interpretation of e.g. option-implied skewness as an indicator of jump risk or downside risk. One possible explanation for this inconsistency is that there are factors affecting option-implied market skewness other than jump risk in the stock market. In this paper, I find that price pressure associated with “crowded trades” of mutual funds is an important endogenous factor. Given that retail investors are prone to herding, the directional trading of mutual funds is correlated, and their collective actions can generate short-term price pressure on aggregate stock prices. Short sellers systematically exploit these patterns not only in the equity lending market, but also in the options market. In line with this economic channel, I find that firstly, the significant negative relationship between market skewness and returns becomes insignificant, once I control for price pressure. Secondly, the negative relationship is only present for the “bad” downside component of risk-neutral skewness, associated with out-of-the-money put options. For the “good” upside component of risk-neutral skewness, associated with out-of-the-money call options, the relationship is always positive. Thirdly, price pressure affects the skewness-return relationship, which can be clearly distinguished from the impact of flows on the volatility-return relationship in terms of the leverage effect. [less ▲]

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See detailPraxis- und Kontakttag 2019, Soziale Arbeit und Digitalisierung
Böwen, Petra UL

Conference given outside the academic context (2019)

Jährlich findet unter dem Motto "Wissenschaft trifft Praxis, Politik und Oeffentlichkeit" Vernetzung und Kooperation unter allen Akteuren der Sozialen Arbeit statt. Das Programm bietet eine Praxis-Messe ... [more ▼]

Jährlich findet unter dem Motto "Wissenschaft trifft Praxis, Politik und Oeffentlichkeit" Vernetzung und Kooperation unter allen Akteuren der Sozialen Arbeit statt. Das Programm bietet eine Praxis-Messe mit Informationsständen der Organisationen, Fachvorträge, Workshops und Diskussionsrunden [less ▲]

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See detailRussische Immigration nach Luxemburg 1918-1935: Einwanderer aus einem nicht-existierenden Land
Ganschow, Inna UL

Scientific Conference (2019, October 18)

Die Einwanderer_innen aus dem früheren Russischen Reich trugen zur Arbeiterlandschaft im Süden, Norden und Osten Luxemburgs nach dem Ersten Weltkrieg bei. Nimmt man diese „Russen“ genauer unter die Lupe ... [more ▼]

Die Einwanderer_innen aus dem früheren Russischen Reich trugen zur Arbeiterlandschaft im Süden, Norden und Osten Luxemburgs nach dem Ersten Weltkrieg bei. Nimmt man diese „Russen“ genauer unter die Lupe, zeigen sich mindestens drei neue Gruppen, die die bereits vor 1914 bestehende russische Gemeinde vergrößerten. Die ersten sind die ehemaligen Kriegsgefangenen aus den Lagern in Frankreich, Belgien und Deutschland. Ein Teil ist vor Kriegsende als Flüchtlinge im Lande, die anderen kommen nach dem Waffenstillstand im November 1918. Sie wollen nicht zurück nach Russland, wo der Bürgerkriegt tobt. Die zweite Gruppe kommt im Laufe des Bürgerkrieges um 1926-1929 aus Bulgarien und Serbien nach. Es handelt sich um noch zusammenhaltende Weißgardisten, die zu der über die Krim in die Türkei evakuierte Armee von Petr Wrangel gehörten. Schließlich ist die dritte Gruppe der zivilen politischen Flüchtlinge zu erwähnen, die seit den frühen 1920ern meistens über Deutschland nach Luxemburg kamen und öfters Angehörigen der jüdischen Glaubensgemeinschaft waren. Viele von ihnen sind bereits seit den intensivierten Pogromen der ersten russischen Revolution von 1905 in Europa. Die Wanderungsstrukturen dieser verschiedenen und sehr heterogenen Gruppen von „Russen“ stehen im Mittelpunkt des Vortrags. [less ▲]

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See detailLiquid Metals and Liquid Crystals Subject to Flow: From Fundamental Fluid Physics to Functional Fibers
Honaker, Lawrence William UL

Doctoral thesis (2019)

Technology over the past few decades has pushed strongly towards wearable technology, one such form being textiles which incorporate a functional component. There are several ways to produce polymer ... [more ▼]

Technology over the past few decades has pushed strongly towards wearable technology, one such form being textiles which incorporate a functional component. There are several ways to produce polymer fibers on both laboratory and industrial scales, but the implementation of these techniques to spin fibers incorporating a functional heterocore has proven challenging for certain combinations of materials. In general, fiber spinning from polymer solutions, regardless of the method, is a multifaceted process with concerns in chemistry, materials science, and physics, both from fundamental and applied standpoints, requiring balancing of flow parameters (interfacial tension, viscosity, and inertial forces) against solvent extraction. This becomes considerably more complicated when multiple interfaces are present. This thesis explores the concerns involved in the spinning of fibers incorporating functional materials from several standpoints. Firstly, due to the importance of interfacial forces in jet stability, I present a microfluidic interfacial tensiometry technique for measuring the interfacial tension between two immiscible fluids, assembled using glass capillary microfluidics techniques. The advantage of this technique is that it can measure the interfacial tension without reliance on sometimes imprecise external parameters and data, obtaining interfacial tension measurements solely from experimental observations of the deformation of a droplet into a channel and the pressure needed to induce the same. Using the knowledge gained from both microfluidic device assembly and the interfacial tension, I then present the wet spinning of polymer fibers using a glass capillary spinneret. This technique uses a polymer dope flowed along with a coagulation bath tooled to extract solvent, leaving behind a continuous polymer fiber. We were able to spin both pure polymer fibers and elastomer microscale fibers containing a continuous heterocore of a liquid crystal, with the optical properties of the liquid crystal maintained within the fiber. While we were not able to spin fibers of a harder polymer containing a continuous core, either liquid crystalline or of a liquid metal, I present analysis of why the spinning was unsuccessful and analysis that will lead us towards the eventual spinning of such fibers. [less ▲]

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See detailDeep Learning Quality Control for High-Throughput High-Content Screening Microscopy Images
Garcia Santa Cruz, Beatriz UL; Jarazo, Javier UL; Schwamborn, Jens Christian UL et al

Poster (2019, October 10)

Automation of biological image analysis is essential to boost biomedical research. The study of complex diseases such as neurodegenerative diseases calls for big amounts of data to build models towards ... [more ▼]

Automation of biological image analysis is essential to boost biomedical research. The study of complex diseases such as neurodegenerative diseases calls for big amounts of data to build models towards precision medicine. Such data acquisition is feasible in the context of high-throughput high-content screening (HTHCS) in which the quality of the results relays on the accuracy of image analysis. Deep learning (DL) yields great performance in image analysis tasks especially with big amounts of data such as the produced in HTHCS contexts. Such DL and HTHCS strength is also their biggest weakness since DL solutions are highly sensitive to bad quality datasets. Hence, accurate Quality Control (QC) for microscopy HTHCS becomes an essential step to obtain reliable pipelines for HTHCS analysis. Usually, artifacts found on these platforms are the consequence of out-of-focus and undesirable density variations. The importance of accurate outlier detection becomes essential for both the training process of generic ML solutions (i.e. segmentation or classification) and the QC of the input data such solution will predict on. Moreover, during the QC of the input dataset, we aim not only to discard unsuitable images but to report the user on the quality of its dataset giving the user the choice to keep or discard the bad images. To build the QC solution we employed fluorescent microscopy images of rosella biosensor generated in the HTHCS platform. A total of 15 planes ranging from -6z to +7z steps to the two optimum planes. We evaluated 27 known focus measure operators and concluded that they have low sensitivity in noisy conditions. We propose a CNN solution which predicts the focus error based on the distance to the optimal plane, outperforming the evaluated focus operators. This QC allows for better results in cell segmentation models based on U-Net architecture as well as promising improvements in image classification tasks. [less ▲]

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See detailAutomatic Analysis of Facial Expressions Based on Deep Covariance Trajectories
Otberdout, Naima; Kacem, Anis UL; Daoudi, Mohamed et al

in IEEE Transactions on Neural Networks and Learning Systems (2019)

In this article, we propose a new approach for facial expression recognition (FER) using deep covariance descriptors. The solution is based on the idea of encoding local and global deep convolutional ... [more ▼]

In this article, we propose a new approach for facial expression recognition (FER) using deep covariance descriptors. The solution is based on the idea of encoding local and global deep convolutional neural network (DCNN) features extracted from still images, in compact local and global covariance descriptors. The space geometry of the covariance matrices is that of symmetric positive definite (SPD) matrices. By conducting the classification of static facial expressions using a support vector machine (SVM) with a valid Gaussian kernel on the SPD manifold, we show that deep covariance descriptors are more effective than the standard classification with fully connected layers and softmax. Besides, we propose a completely new and original solution to model the temporal dynamic of facial expressions as deep trajectories on the SPD manifold. As an extension of the classification pipeline of covariance descriptors, we apply SVM with valid positive definite kernels derived from global alignment for deep covariance trajectories classification. By performing extensive experiments on the Oulu-CASIA, CK+, static facial expression in the wild (SFEW), and acted facial expressions in the wild (AFEW) data sets, we show that both the proposed static and dynamic approaches achieve the state-of-the-art performance for FER outperforming many recent approaches. [less ▲]

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See detailWYLD Special Symposium: Technological Innovations in Dementia Diagnosis and Care
Leist, Anja UL

Scientific Conference (2019, October)

Researchers and entrepreneurs present technological innovations in dementia diagnosis and care, particularly through the use of wearables, apps, and novel data analysis techniques. These innovations ... [more ▼]

Researchers and entrepreneurs present technological innovations in dementia diagnosis and care, particularly through the use of wearables, apps, and novel data analysis techniques. These innovations address complex challenges of differential dementia diagnosis and ensuring high-quality and safe home and formal care. [less ▲]

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See detailGender inequalities across the life course: A societal perspective on gender differences in dementia
Leist, Anja UL; Ford, Katherine Joy UL

Scientific Conference (2019, October)

Introduction. Women are at increased risk of developing dementia, which can only partly be explained with differences in longevity, sex biology, or differences in detection/diagnosis. A promising approach ... [more ▼]

Introduction. Women are at increased risk of developing dementia, which can only partly be explained with differences in longevity, sex biology, or differences in detection/diagnosis. A promising approach at the population level is the systematic investigation of life course conditions for men and women across countries and cohorts in order to detect if schooling or work opportunities differ by gender. In the cognitive reserve framework, education and work reflect opportunities for cognitively stimulating activities, which increase cognitive reserve across the life course, and which could delay cognitive decline and the diagnosis of dementia. Method. We develop a framework for systematizing gender inequalities across different life stages and life domains, with a focus on systematic disadvantages for women that could be relevant barriers to cognitive reserve development. For the empirical analysis, we gather individual information and performance on cognitive tests from several harmonized cross-national aging surveys, i.e. the U.S. Health and Retirement Study and sister studies (SHARE, ELSA, SAGE), separated by cohort. Historical figures on gender inequalities for countries and cohorts, and their relevant timings in the life course of the older respondents, e.g. during schooling, were gathered from different sources, and merged with the individual-level data. Results. The new framework leads to testable hypotheses in both the Western and global context regarding life-course socialization and schooling and work opportunities that have been different for men and women. We will present preliminary evidence of how female (dis)advantages on different cognitive tests – memory, executive functioning – are mirroring societal gender inequalities. Discussion. We need to better understand how different life-course opportunities for men and women can create gender differences in dementia at old ages in order to identify individuals at risk today and improve conditions for future generations. [less ▲]

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See detailAccess Control Mechanisms Reconsidered with Blockchain Technologies
Steichen, Mathis UL

Doctoral thesis (2019)

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See detailElastic sheath–liquid crystal core fibres achieved by microfluidic wet spinning
Honaker, Lawrence William UL; Vats, Shameek UL; Anyfantakis, Emmanouil UL et al

in Journal of Materials Chemistry C (2019)

While coaxial polymer sheath–liquid crystal core fibres attract interest for fundamental research as well as applied reasons, the main method for achieving them so far, electrospinning, is complex and has ... [more ▼]

While coaxial polymer sheath–liquid crystal core fibres attract interest for fundamental research as well as applied reasons, the main method for achieving them so far, electrospinning, is complex and has significant limitations. It has proven particularly challenging to spin fibres with an elastic sheath. As an alternative approach, we present a microfluidic wet spinning process that allows us to produce liquid crystal core–polyisoprene rubber sheath fibres on a laboratory scale. The fibres can be stretched by up to 300% with intact core–sheath geometry. We spin fibres with nematic as well as with cholesteric liquid crystal in the core, the latter turning the composite fibre into an elastic cylindrical photonic crystal. Iridescent colours are easily observable by the naked eye. As this coaxial wet spinning should be amenable to upscaling, this could allow large-scale production of innovative functional fibres, attractive through the various responsive characteristics of different liquid crystal phases being incorporated into an elastic textile fiber form factor. [less ▲]

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See detailToward Millimeter-Wave Joint Radar Communications: A Signal Processing Perspective
Mishra, Kumar Vijay; Shankar, Bhavani UL; Koivunen, Visa et al

in IEEE Signal Processing Magazine (2019), 36(5), 100-114

Synergistic design of communications and radar systems with common spectral and hardware resources is heralding a new era of efficiently utilizing a limited radio-frequency (RF) spectrum. Such a joint ... [more ▼]

Synergistic design of communications and radar systems with common spectral and hardware resources is heralding a new era of efficiently utilizing a limited radio-frequency (RF) spectrum. Such a joint radar communications (JRC) model has advantages of low cost, compact size, less power consumption, spectrum sharing, improved performance, and safety due to enhanced information sharing. Today, millimeter-wave (mmwave) communications have emerged as the preferred technology for short distance wireless links because they provide transmission bandwidth that is several gigahertz wide. This band is also promising for short-range radar applications, which benefit from the high-range resolution arising from large transmit signal bandwidths. Signal processing techniques are critical to the implementation of mm-wave JRC systems. Major challenges are joint waveform design and performance criteria that would optimally trade off between communications and radar functionalities. Novel multiple-input, multiple-output (MIMO) signal processing techniques are required because mm-wave JRC systems employ large antenna arrays. There are opportunities to exploit recent advances in cognition, compressed sensing, and machine learning to reduce required resources and dynamically allocate them with low overheads. This article provides a signal processing perspective of mm-wave JRC systems with an emphasis on waveform design. [less ▲]

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See detailLearning-Assisted Optimization for Energy-Efficient Scheduling in Deadline-Aware NOMA Systems
Lei, Lei UL; You, Lei; He, Qing et al

in IEEE Transactions on Green Communications and Networking (2019)

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See detailOptimal Resource Allocation for NOMA-Enabled Cache Replacement and Content Delivery
Lei, Lei UL; Vu, Thang Xuan UL; Xiang, Lin UL et al

in IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (IEEE PIMRC 2019) (2019, September)

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See detailNiklas Luhmann: The Place of Court in the Legal System
Sosoe, Lukas UL

Speeches/Talks (2019)

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