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See detailCPSDebug: a tool for explanation of failures in cyber-physical systems
Bartocci, Ezio; Manjunath, Niveditha; Mariani, Leonardo et al

in CPSDebug: a tool for explanation of failures in cyber-physical systems (2020)

Debugging Cyber-Physical System models is often challenging, as it requires identifying a potentially long, complex and heterogenous combination of events that resulted in a violation of the expected ... [more ▼]

Debugging Cyber-Physical System models is often challenging, as it requires identifying a potentially long, complex and heterogenous combination of events that resulted in a violation of the expected behavior of the system. In this paper we present CPSDebug, a tool for supporting designers in the debugging of failures in MAT- LAB Simulink/Stateflow models. CPSDebug implements a gray-box approach that combines testing, specification mining, and failure analysis to identify the causes of failures and explain their propagation in time and space. The evaluation of the tool, based on multiple usage scenarios and faults and direct feedback from engineers, shows that CPSDebug can effectively aid engineers during debugging tasks. [less ▲]

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See detailSchon alles gesagt zur satzinternen Großschreibung? Perspektiven auf die aktuellen Diskussionen in der Sprachdidaktik
Weth, Constanze UL

in Deutschunterricht (Der): Beiträge zu seiner Praxis und wissenschaftlichen Grundlegung (2020), 2020(2), 44-52

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See detailStrukturierte Analyse von Nachfrageflexibilität im Stromsystem und Ableitung eines generischen Geschäftsmodells für (stromintensive) Unternehmen
Haupt, Leon; Körner, Marc-Fabian; Schoepf, Michael UL et al

in Zeitschrift für Energiewirtschaft (2020)

The expansion of renewable energy requires appropriate flexibility in the electricity system in order to maintain the balance between electricity generation and consumption at all times. The industrial ... [more ▼]

The expansion of renewable energy requires appropriate flexibility in the electricity system in order to maintain the balance between electricity generation and consumption at all times. The industrial sector plays a central role for a successful energy transition due to the power-intensive processes and the resulting high electricity demand. Industrial demand response may be a cost-effective alternative to other flexibility options. At the same time, companies can reduce electricity procurement costs by providing demand response. Nevertheless, due to a complex decision-making environment and a lack of planning security, only a few companies are currently exploiting the existing potential. To reach the goals of the energy transition, the potential used must still be raised significantly, i.e., companies must align their demand for electricity more closely to the existing supply of electricity. This article supports companies in this transformation process by illustrating dimensions and characteristics of a business model for demand response. Through a literature study and subsequent expert workshops, a generic business model for companies is derived that provides transparency regarding the necessary activities and resources for enabling and implementing demand response. The results were developed using the established Business Model Canvas. This supports companies that have not yet started to use demand response in their business model development and thus reduces barriers to entry. The results presented contribute to an increase in the demand response potential of the industry. [less ▲]

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See detailSemantic associations between arithmetic and space: Evidence from temporal order judgements.
Andres, Michael; Salvaggio, Samuel; Lefèvre, Nathalie et al

in Memory & cognition (2020), 48(3), 361-369

Spatial biases associated with subtraction or addition problem solving are generally considered as reflecting leftward or rightward attention shifts along a mental numerical continuum, but an alternative ... [more ▼]

Spatial biases associated with subtraction or addition problem solving are generally considered as reflecting leftward or rightward attention shifts along a mental numerical continuum, but an alternative hypothesis not implying spatial attention proposes that the operator (plus or minus sign) may favour a response to one side of space (left or right) because of semantic associations. We tested these two accounts in a series of temporal order judgement experiments that consisted in the auditory presentation of addition or subtraction problems followed 200 ms (Experiments 1-2) or 800 ms (Experiment 3) later by the display of two lateralized targets in close temporal succession. To dissociate the side where the operation first brought their attention from the side they had to respond to, we asked participants to report which of the left or right target appeared first or last on screen. Under the attention-orienting account, addition should elicit more rightward responses than subtraction when participants have to focus on the first target, but more leftward responses when they have to focus on the last target, because the latter is opposite to the side where the operation first brought their attention. Under the semantic account, addition should elicit more rightward responses than subtraction, no matter the focus is on the first or last target, because participants should systematically favour the side conceptually linked to the operator. The results of the three experiments converge to indicate that, in lateralized target detection tasks, the spatial biases induced by arithmetic operations stem from semantic associations. [less ▲]

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See detailContrasting Classical and Machine Learning Approaches in the Estimation of Value-Added Scores in Large-Scale Educational Data
Levy, Jessica UL; Mussack, Dominic UL; Brunner, Martin et al

in Frontiers in Psychology (2020), 11

There is no consensus on which statistical model estimates school value-added (VA) most accurately. To date, the two most common statistical models used for the calculation of VA scores are two classical ... [more ▼]

There is no consensus on which statistical model estimates school value-added (VA) most accurately. To date, the two most common statistical models used for the calculation of VA scores are two classical methods: linear regression and multilevel models. These models have the advantage of being relatively transparent and thus understandable for most researchers and practitioners. However, these statistical models are bound to certain assumptions (e.g., linearity) that might limit their prediction accuracy. Machine learning methods, which have yielded spectacular results in numerous fields, may be a valuable alternative to these classical models. Although big data is not new in general, it is relatively new in the realm of social sciences and education. New types of data require new data analytical approaches. Such techniques have already evolved in fields with a long tradition in crunching big data (e.g., gene technology). The objective of the present paper is to competently apply these “imported” techniques to education data, more precisely VA scores, and assess when and how they can extend or replace the classical psychometrics toolbox. The different models include linear and non-linear methods and extend classical models with the most commonly used machine learning methods (i.e., random forest, neural networks, support vector machines, and boosting). We used representative data of 3,026 students in 153 schools who took part in the standardized achievement tests of the Luxembourg School Monitoring Program in grades 1 and 3. Multilevel models outperformed classical linear and polynomial regressions, as well as different machine learning models. However, it could be observed that across all schools, school VA scores from different model types correlated highly. Yet, the percentage of disagreements as compared to multilevel models was not trivial and real-life implications for individual schools may still be dramatic depending on the model type used. Implications of these results and possible ethical concerns regarding the use of machine learning methods for decision-making in education are discussed. [less ▲]

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See detailHybrid Erythrocyte Liposomes: Functionalized Red Blood Cell Membranes for Molecule Encapsulation
Himbert, Sebastian; Blacker, Matthew J.; Kihm, Alexander et al

in Advanced Biosystems (2020), 4(3), 1900185-11

The modification of erythrocyte membrane properties provides a new tool towards improved drug delivery and biomedical applications. The fabrication of hybrid erythrocyte liposomes is presented by doping ... [more ▼]

The modification of erythrocyte membrane properties provides a new tool towards improved drug delivery and biomedical applications. The fabrication of hybrid erythrocyte liposomes is presented by doping red blood cell membranes with synthetic lipid molecules of different classes (PC, PS, PG) and different degrees of saturation (14:0, 16:0-18:1). The respective solubility limits are determined, and material properties of the hybrid liposomes are studied by a combination of X-ray diffraction, epi-fluorescent microscopy, dynamic light scattering (DLS), Zeta potential, UV-vis spectroscopy, and Molecular Dynamics (MD) simulations. Membrane thickness and lipid orientation can be tuned through the addition of phosphatidylcholine lipids. The hybrid membranes can be fluorescently labelled by incorporating Texas-red DHPE, and their charge modified by incorporating phosphatidylserine and phosphatidylglycerol. By using fluorescein labeled dextran as an example, it is demonstrated that small molecules can be encapsulated into these hybrid liposomes. [less ▲]

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See detailEffect of Red Blood Cell Aging In Vivo on Their Aggregation Properties In Vitro: Measurements with Laser Tweezers
Ermolinskiy, Petr; Lugovtsov, Andrei; Yaya, Francois et al

in Applied Sciences (2020), 10(21), 7581-10

Red blood cell (RBC) aggregation highly influences hemorheology and blood microcirculation in the human body. The aggregation properties of RBCs can vary due to numerous factors, including RBC age. The ... [more ▼]

Red blood cell (RBC) aggregation highly influences hemorheology and blood microcirculation in the human body. The aggregation properties of RBCs can vary due to numerous factors, including RBC age. The aim of this work was to estimate in vitro the differences in the RBC aggregation properties of different RBC age populations in single-cell experiments using laser tweezers. RBCs from five healthy volunteers were separated into four subpopulations by Percoll density gradient centrifugation. Each subpopulation of the RBC was separately resuspended in autologous plasma or dextran 70 kDa (50 mg/mL). The aggregation force between the single cells was measured with holographic laser tweezers. The obtained data demonstrated an enhancement of RBC aggregation force in doublets with age: the older the cells, the higher the aggregation force. The obtained data revealed the differences between the aggregation and aggregability of RBC in dependence of the RBC in vivo age. [less ▲]

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See detailSurveillance, indépendance et intégrité
Marx, Claude; Limpach, Marc; Majerus, Benoît UL

Book published by CSSF (2020)

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See detailThis is not a scandal in Luxembourg
Majerus, Benoît UL

in Entreprises et Histoire (2020)

At the beginning of the 1970s, Investors Overseas Service (IOS), a Panamanian company run by an American businessman, Bernie Cornfeld, with some of its subsidiaries domiciled in Luxembourg, experienced a ... [more ▼]

At the beginning of the 1970s, Investors Overseas Service (IOS), a Panamanian company run by an American businessman, Bernie Cornfeld, with some of its subsidiaries domiciled in Luxembourg, experienced a spectacular collapse. This was the first time that the Luxembourg financial centre appeared in the local and international media as a player in a globalised financial world. The crash of IOS referred to by some European press outlets as a Luxembourgish scandal, was not described in the same terms by the Luxembourg press and political elite. This case study examines how (financial) scandals erupt and are closed down in small countries. [less ▲]

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See detailModulation of coherent phonon amplitudes in low-dimensional materials by ultrafast laser pulse trains
Nugraha, Ahmad R.; Hanna, Muhammad Y.; Suprayoga, Edi et al

in AIP Conference Proceedings (2020), 2256(1), 020005

We theoretically investigate how coherent phonon amplitudes in low dimensional materials can be modulated by ultrafast laser pulse trains. Important laser parameters for the modulation of coherent phonon ... [more ▼]

We theoretically investigate how coherent phonon amplitudes in low dimensional materials can be modulated by ultrafast laser pulse trains. Important laser parameters for the modulation of coherent phonon amplitudes are the pulse width, repetition period, and number of pulses in the pulse train. We find that it is possible to switch on or switch off the radial breathing mode (RBM) and the G-band phonons in a single wall carbon nanotube (SWNT), as a typical model of low-dimensional materials. In particular, if the repetition period matches with integer multiple of the RBM phonon period, the RBM phonon could be switched on, while the other modes are switched off. On the other hand, for the G-band, which has a higher frequency (shorter period) than the RBM, the number of pulses in the pulse train also affects the switching process. The ratios of the G-band and RBM amplitudes are found to be significantly enhanced at certain integer multiples of pulse number as a function of SWNT diameter. Such a “magic number” phenomenon in ultrafast spectroscopy can be extended to other low-dimensional materials, in which we may realize a phonon switch in the future. [less ▲]

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See detailThe insurance effect of renewable distributed energy resources against uncertain electricity price developments
Fridgen, Gilbert UL; Halbrügge, Stephanie; Olenberger, Christian et al

in Energy Economics (2020), 91

To combat climate change, many countries all around the world currently foster the development of renewable energy sources (RES). However, in contrast to traditional energy systems that relied on few ... [more ▼]

To combat climate change, many countries all around the world currently foster the development of renewable energy sources (RES). However, in contrast to traditional energy systems that relied on few central power plants, RES are typically highly decentral and spread all over a country. Against this backdrop, the promotion of a decentralization of the energy system by fostering a regional balance of energy demand and supply with a corresponding increase in energy democracy is seen as a promising approach. However, energy democracy driven by an increasing involvement of consumers requires adequate investments of consumers in their own local RES in order to become active players, usually called prosumers. Risk associated with uncertain long-term electricity price developments is generally seen as a barrier to investments. In contrast, we describe that an investment in distributed energy resources (DERs) may actually serve as a consumer's insurance against price risk. Our results set out that the consideration of risk-aversion may actually positively shift an investment decision in renewable DERs. This is due to the prosumer becoming more self-sufficient and less dependent on uncertain price developments. To analyze such an insurance effect, we create a formal decision model considering the prosumer's risk-aversion and derive the prosumer's optimal investment in renewable DERs. However, our results also indicate that under some circumstances the insurance effect disappears: When a prosumer turns into a predominant producer, the prosumer is again exposed to risk in terms of uncertain revenues. Ultimately, our work highlights the importance of a consideration of the insurance effect when assessing an investment in renewable DERs. [less ▲]

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See detailLocal constancy for reductions of two-dimensional crystalline representations
Torti, Emiliano UL

E-print/Working paper (2020)

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See detailNumber Theory for Cryptography (Lecture Notes)
Wiese, Gabor UL

Learning material (2020)

In these lectures (8 hours taught in November 2020), we mention some topics from (algebraic) number theory as well as some related concepts from (algebraic) geometry that can be useful in cryptography. We ... [more ▼]

In these lectures (8 hours taught in November 2020), we mention some topics from (algebraic) number theory as well as some related concepts from (algebraic) geometry that can be useful in cryptography. We cannot go deeply into any of the topics and most results will be presented without any proofs. One of the things that one encounters are `ideal lattices'. In the examples I saw, this was nothing but (an ideal in) an order in a number field, which is one of the concepts that we present here in its mathematical context (i.e. embedded in a conceptual setting). It has been noted long ago (already in the 19th century) that number fields and function fields of curves have many properties in common. Accordingly, we shall also present some basic topics on affine plane curves and their function fields. This leads us to mention elliptic curves, however, only in an affine version (instead of the better projective one); we cannot go deeply into that topic at all. The material presented here is classical and very well known. [less ▲]

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See detailGeneral Principles of EU Law and EU Administrative Law
Hofmann, Herwig UL

in Peers, Steve; Barnard, Catherine (Eds.) European Union Law (2020)

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See detailCross-sectional focusing of red blood cells in a constricted microfluidic channel
Abay, Asena; Recktenwald, Steffen M.; John, Thomas et al

in SOFT MATTER (2020), 16(2), 534-543

Constrictions in blood vessels and microfluidic devices can dramatically change the spatial distribution of passing cells or particles and are commonly used in biomedical cell sorting applications ... [more ▼]

Constrictions in blood vessels and microfluidic devices can dramatically change the spatial distribution of passing cells or particles and are commonly used in biomedical cell sorting applications. However, the three-dimensional nature of cell focusing in the channel cross-section remains poorly investigated. Here, we explore the cross-sectional distribution of living and rigid red blood cells passing a constricted microfluidic channel by tracking individual cells in multiple layers across the channel depth and across the channel width. While cells are homogeneously distributed in the channel cross-section pre-contraction, we observe a strong geometry-induced focusing towards the four channel faces post-contraction. The magnitude of this cross-sectional focusing effect increases with increasing Reynolds number for both living and rigid red blood cells. We discuss how this non-uniform cell distribution downstream of the contraction results in an apparent double-peaked velocity profile in particle image velocimetry analysis and show that trapping of red blood cells in the recirculation zones of the abrupt construction depends on cell deformability. [less ▲]

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See detailOrigin of the Flat Band in Heavily Cs-Doped Graphene
Ehlen, N; Hell, M; Marini, G et al

in ACS Nano (2020), 14(1), 1055

A flat energy dispersion of electrons at the Fermi level of a material leads to instabilities in the electronic system and can drive phase transitions. Here we show that the flat band in graphene can be ... [more ▼]

A flat energy dispersion of electrons at the Fermi level of a material leads to instabilities in the electronic system and can drive phase transitions. Here we show that the flat band in graphene can be achieved by sandwiching a graphene monolayer by two cesium (Cs) layers. We investigate the flat band by a combination of angle-resolved photoemission spectroscopy experiment and the calculations. Our work highlights that charge transfer, zone folding of graphene bands, and the covalent bonding between C and Cs atoms are the origin of the flat energy band formation. Analysis of the Stoner criterion for the flat band suggests the presence of a ferromagnetic instability. The presented approach is an alternative route for obtaining flat band materials to twisting bilayer graphene which yields thermodynamically stable flat band materials in large areas. [less ▲]

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See detailAssessment of Fibrinogen Macromolecules Interaction with Red Blood Cells Membrane by Means of Laser Aggregometry, Flow Cytometry, and Optical Tweezers Combined with Microfluidics
Semenov, Alexey N.; Lugovtsov, Andrei E.; Shirshin, Evgeny A. et al

in BIOMOLECULES (2020)

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See detailEuropa – Quo Vadis? Ein kritischer Kommentar zum EZB-Urteil des BVerfG
Hofmann, Herwig UL; Numerous, Others

in Europäische Zeitschrift für Wirtschaftsrecht (2020)

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See detailEfficiency Fluctuations of Stochastic Machines Undergoing a Phase Transition
Vroylandt, Hadrien; Esposito, Massimiliano UL; Verley, Gatien

in Physical Review Letters (2020), 124(25), 250603

Detailed reference viewed: 21 (2 UL)