Trading Zones of Digital History

Doctoral thesis (2019)

As long as there have been computers, there have been scholars pulling at historians, challenging them to use these computers for historical research. Yet what role computers can have in historical ... [more ▼]

As long as there have been computers, there have been scholars pulling at historians, challenging them to use these computers for historical research. Yet what role computers can have in historical research is a matter of continuous debate. Under the signifier of “digital history”, historians have experimented with tools, concepts, and methods from other disciplines, mostly computer science and computational linguistics, to benefit the historical discipline. The collaborations that emerge through these experiments can be characterised as a two-sided uncertainty: historians uncertain how they as historians should use digital methods, and computational experts uncertain how digital methods should work with historical data sets. The opportunity that arises from these uncertainties is that historians and computational experts need to negotiate the methods and concepts under development. In this thesis, I investigate these negotiations as trading zones, as local spaces of negotiation. These negotiations are characterised as a duality of boundary practices. First, boundary crossing, the crossing of boundaries of disciplines, discourses, and institutions to collaborate. Second, boundary construction, the establishment of boundaries of groups and communities to preserve disciplinary values and remain recognisable as part of a community of practice. How boundary crossing and construction are balanced, whether disciplinary boundaries are shifted, and to what extent historians’ practices are transformed by continued interaction with computational experts, are open questions demanding closer scrutiny. These considerations lead to the research question underlying this thesis: how are historians affected by interactions with computational experts in the context of digital history collaborations? I investigate this question through a mixed-methods, multi-sited ethnographic approach, consisting of an open online survey which received 173 responses, 4.5 years of observations at the University of Luxembourg, 37 interviews, and an LDA topic modelling analysis of 10,918 blog posts from 73 historians between 2008-2017. Through these approaches, I examine trading zones as configured by three different dimensions. First, connectedness, the extent to which collaborators connect with one another through physical proximity, communication, and the sharing of practices. Second, power asymmetry, the extent to which participants shape their own field of action as well as the fields of action of their collaborators. Third, cultural maintenance, the extent to which collaborators become more alike or stay apart by adopting new practices or displacing previous practices. On a macro level, referring to the global historical discipline, I conclude that methodological approaches developed in local trading zones have hardly diffused to macro solutions. Insofar digital infrastructures were appropriated in the macro community, these were aligned with traditional practices. Rather than transforming historical scholarship, the challenge was to provide infrastructures congruent with existing values and practices. On a meso level, referring to the historians engaged in digital history trading zones, I conclude that the effect of interactions was dependent on individual decisions and incentives. Some historians experimented with or adopted computational practices and concepts. Yet other historians detached their work from the shared objective of a collaboration in order to reduce risks, as well as to maintain disciplinary practices. The majority of participants in trading zones were scholars from the humanities, physically distant from collaborators, communicating more often with disciplinary peers than with cross-disciplinary collaborators. As such, even when participating in trading zones of digital history, a significant number of historians remained aligned with traditional practices. Changing practices were regularly not in the direction of computational practices, but to incentives of politics or funding. While historians that participated in digital history trading zones therefore did learn new practices, this did not entail a computational transformation of their scholarship. Finally, on a micro level, some historians chose to engage intensively with computational experts. I call these individuals digital history brokers, who exemplified significant shifts in practices. Brokers conducted project management; coordinated practices from archival and library domains such as data collection, transformation, and description; learned about the potential and limitations of computational technologies and where to apply these; employed inter-languages to translate between the different collaborating domains; and finally transformed historical questions into infrastructural problems. Digital history brokers thereby not only developed interactional expertise to collaborate with computational experts. They furthermore developed political proficiency to negotiate the socio- economic potential of digital history strategies with politics, university administrators, and funding agencies. I therefore describe the practices of brokers as infrastructuring, covering a duality of negotiations. First, cross-disciplinary socio-technical negotiations with computational experts how to support scholarly practices with digital technology. Second, intra-disciplinary socio-political negotiations how to diffuse those practices within the community of practice. Digital history brokers therefore transform their own practices, so that other historians do not have to on meso or macro levels, but can employ digitised sources and digital methodology through infrastructures in a fashion that naturally fits into their practices as historians. I thereby provide a critical view on digital history grounded in how it is conducted and negotiated. This thesis is therefore aimed mainly at scholars interested in digital history and its relation to the historical discipline and to digital humanities, as well as scholars interested in studying digital history as a specific case of cross-disciplinarity. [less ▲]

The Effect of ATP INDUCED CALCIUM DYNAMICS ON EPITHELIAL TO MESENCHYMAL TRANSITIONS

Doctoral thesis (2019)

Cells respond to a multitude of external triggers by a limited number of signaling pathways activated by receptors on plasma membrane, such as receptor tyrosine kinases (RTKs) or G protein-coupled ... [more ▼]

Cells respond to a multitude of external triggers by a limited number of signaling pathways activated by receptors on plasma membrane, such as receptor tyrosine kinases (RTKs) or G protein-coupled receptors (GPCRs). These pathways do not simply convey the downstream signal, but instead the signal is very often processed by encoding and integrated with the current state of the cell. A traditional transcriptional analysis tends to provide an averaged output measured in a population, what often masks the behavior of individual cells. However, with recent single cell techniques developments, it is possible to investigate transcription in individual living cells. This contributed tremendously to the understanding of development and progression of many diseases including cancer. The more we understand about this high complexity of signaling mechanisms and multitude of cellular safety countermeasures, the more we see cancer as a microevolution state of “rebellious cells” (cells entering the fate opposite to the one intended) following a patch through a discreet system. This thesis specifically focused on the temporal aspect of signaling in the context of the epithelia-to-mensenchymal transition (EMT) by combining single cell experiments and bioinformatics analysis. We investigated cellular signaling changes in response to different dynamical profiles of the stimuli. In particular, we used the HMLER cell line, which is a metastatic breast cancer model for the epithelial to mesenchymal transition. By applying stochastic or oscillatory pulses of extracellular ATP-induced Ca2+ signals with different interspike intervals, we were investigating different transcription states from those evoked by constant ATP-induced Ca2+ dose responses. In order to precisely apply those stimulation profiles, we have developed and established a perfusion system. This device allows to treat population of cells simultaneously with the exact same dynamical profiles. Cells treated by these well controlled signals were subsequently processed by the single cell RNA-seq technique Drop-seq for transcriptional analysis. The resulting high dimensional digital gene expression matrices were analyzed by a developed high-throughput computational analysis pipeline. This analysis includes the identification of differentially expressed genes and cellular clusters (states) by dimensionality reduction methods (PCA, t-SNE) and pathway analysis. We evaluated changes and trends of genes from difference dynamical profiles by investigating their involvement in stress, stemness and regulation of motility. First, we confirmed that oscillatory stimulation with extracellular ATP (eATP) tends to lower the burden of cellular stress and apoptosis related pathways while maintaining its other effector functions compared to constant eATP stimulation. Interestingly, stochastic spiking of extracellular ATP in our setup led to a massive (~80%) increase in overall differential gene expression compared to deterministic oscillatory stimulation with the same period. Consequentially, stochastic signaling seems to activate a much wider range of biological pathways, which indicates the much higher complexity in information processing capability of producing rebellious cells during cancer progression and metastasis. On the other hand, our findings suggests that oscillatory eATP stimulation could contribute to EMT by lowering ID3 expression compared to stochastic stimulation where we observed a stronger upregulation of IRS2. Finally, we integrated the DEGs into biological processes involved in each conditions and put these new insights into the context of the eATP-induced Ca2+ induced epithelial to mesenchymal transition. Overall, this thesis has applied recent single cell technologies to characterize underlying principles of cellular heterogeneity induced by cell signaling and specifically investigated the complex mechanisms of cell fate in the context of EMT [less ▲]

Numerical analysis of gait load distribution in the human pelvis and design of a biomechanical testing device: experimental assessment of two implants for anterior fragility fractures

Doctoral thesis (2019)

The current project research was conducted at the University of Luxembourg in cooperation with orthopaedic surgeons from the Centre Hospitalier de Luxembourg and the Universitätsklinikum des Saarlandes ... [more ▼]

The current project research was conducted at the University of Luxembourg in cooperation with orthopaedic surgeons from the Centre Hospitalier de Luxembourg and the Universitätsklinikum des Saarlandes. The main objective was to investigate the gait load distribution in the human pelvis and the influence of the stiffness of the pubic symphysis and the sacroiliac joints on this force transmission in order to numerically and experimentally assess the stability provided by two reconstruction systems for anterior fragility fractures. To begin with, the global approach consisted in combining inverse dynamics and finite element methods to investigate physiological loadings applied to the pelvis during the gait cycle. Then, an experimental test bench was designed to reproduce those gait conditions on artificial pelvises for biomechanical assessment of different systems used for fragility fractures of the pelvis. At first, muscles forces and joint contact forces from the gait applied to the pelvis were calculated by inverse dynamics with an experimentally validated musculoskeletal model. Implementation in a finite element model including bones and joints of the pelvis highlighted that superior rami experience the highest stresses. Fracture of a superior ramus changed the initial load distribution by increasing the stresses at the inferior ramus and on the posterior structures. Combination of superior and inferior rami fractures on the same side redirected the forces backwards and showed high stresses on the sacral alae where compression fractures are commonly seen clinically. Reconstruction devices showed differences in stability at early stage of healing with benefits provided by the iliopubic subcutaneous plate. No noticeable differences compared to the Supra-Acetabular External Fixator were seen during later healing. Regarding the influence of the joint stiffness on the load distribution in a healthy pelvis, an increase of PS stiffness redirected loads to the anterior pelvis whereas an increase of PS laxity redirected loads to the posterior structures. A fusion of the sacroiliac joints did not show noticeable changes in the normal load distribution. Following the computational investigation, an experimental test bench was designed with numerical engineering tools. The biomechanical setup aimed at reproducing loadings observed during previously studied moments of the gait on artificial pelvises with fused joints. Static loadings and cyclic loadings were performed on artificial pelvises with and without reconstruction devices: first with a superior ramus fracture only and then with superior and inferior rami fractures. The Supra-Acetabular External Fixator and the iliopubic subcutaneous plate did not show any significant stability difference when a superior ramus fracture is considered. When including the inferior ramus fracture on the same side, the iliopubic subcutaneous plate significantly improved the stability of the reconstructed pelvis by reducing IV the displacement of the superior fracture, contrary to the Supra-Acetabular External Fixator that did not show any improvement. For both configurations, no fatigue phenomenon was observed during cyclic loadings simulating four days of walking for a patient (5 000 cycles). There is no conflict of interest related to this work. [less ▲]

Le Droit de la Coopération Décentralisée au Mali: Une Approche Juridique du Droit Administratif International

Doctoral thesis (2019)

Le droit des collectivités territoriales autorise un grand nombre de types de coopération allant du jumelage à la forme contractuelle ou conventionnelle. Parmi ceux-ci, la coopération décentralisée occupe ... [more ▼]

Le droit des collectivités territoriales autorise un grand nombre de types de coopération allant du jumelage à la forme contractuelle ou conventionnelle. Parmi ceux-ci, la coopération décentralisée occupe une place déterminante. Elle concerne toutes les actions extérieures effectuées par les collectivités territoriales. Cependant, cette coopération décentralisée des collectivités territoriales maliennes demeure toujours subtile .Le concept manque encore de précision, ce qui provoque une confusion dans sa compréhension par les élus et les agents des collectivités territoriales à la recherche de solution aux multiples questionnements sur le régime juridique de ces conventions. Si le législateur a tenté de règlementer la compétence, il reste muet toujours sur le régime juridique. Ces accords de coopération décentralisée semblent n’appartenir à aucune catégorie juridique précise. Dans l’optique de la détermination d’un droit, nous avons tenté de prendre les considérations des exigences du droit interne et du droit international. Dans un premier temps, l’étude s’intéresse aux questions relatives à l’élaboration du régime de la coopération décentralisée. Elle fait ressortir les fondements légaux nationaux et internationaux ainsi que la qualification de ces accords. Dans un second temps, l’étude s’intéresse aux problèmes de la mise en œuvre des conventions de coopération décentralisée dont l’objectif est de démontrer le caractère exécutoire des conventions de coopération ainsi que les différentes alternatives de résolution du contentieux. Enfin, l’objet de cette thèse tente de préciser le régime juridique des conventions conclues entre les collectivités territoriales maliennes et leurs partenaires étrangers dans la perspective de privilégier le droit administratif local à caractère international [less ▲]

Legal Design for the General Data Protection Regulation. A Methodology for the Visualization and Communication of Legal Concepts

Doctoral thesis (2019)

Privacy policies are known to be impenetrable, lengthy, tedious texts that are hardly read and poorly understood. Therefore, the General Data Protection Regulation (GDPR) introduces provisions to enhance ... [more ▼]

Privacy policies are known to be impenetrable, lengthy, tedious texts that are hardly read and poorly understood. Therefore, the General Data Protection Regulation (GDPR) introduces provisions to enhance the transparency of such documents and suggests icons as visual elements to provide “in an easily visible, intelligible and clearly legible manner a meaningful overview of the intended processing.” The present dissertation discusses how design, and in particular legal design, can support the concrete implementation of the GDPR’s transparency obligation. Notwithstanding the many benefits that visual communication demonstrably provides, graphical elements do not improve comprehension per se. Research on graphical symbols for legal concepts is still scarce, while both the creation and consequent evaluation of icons depicting abstract or unfamiliar concepts represent a challenge. More- over, precision of representation can support the individuals’ sense-making of the meaning of graphical symbols, but at the expense of simplicity and us- ability. Hence, this research proposed a methodology that combines semantic web technologies with principles of semiotics and ergonomics, and empirical methods drawn from the emerging discipline of legal design, that was used to create and evaluate DaPIS, the Data Protection Icon Set meant to support the data subjects’ navigation of privacy policies. The icon set is modeled on PrOnto, an ontological representation of the GDPR, and is organized around its core modules: personal data, roles and agents, processing operations, processing purposes, legal bases, and data subjects’ rights. In combination with the description of a privacy policy in the legal standard XML Akoma Ntoso, such an approach makes the icons machine-readable and semi-automatically retrievable. Icons can thus serve as information markers in lengthy privacy statements and support the navigation of the text by the data subject. [less ▲]

Stress - modulated bulk photovoltaic effect in polar oxide crystals

Doctoral thesis (2019)

Light-induced phenomena in ferroelectric materials have been exploited for decades for optoelectronic applications. Homogeneous illumination of a non-centrosymmetric ferroelectric material creates ... [more ▼]

Light-induced phenomena in ferroelectric materials have been exploited for decades for optoelectronic applications. Homogeneous illumination of a non-centrosymmetric ferroelectric material creates anomalously high voltages exceeding a value which is usually limited by its band gap. This phenomenon is called the bulk-photovoltaic effect (BPVE). Lithium niobate is a prototypical material for BPVE. The only limiting factor in lithium niobate is its low photo-current values, which can be improved by doping the crystal with donor metals. This study focuses primarily on light induced processes in mono-domain lithium niobate single crystals doped with transition metal ions, particularly the influence of stress on the BPVE. The effect of stress on BPVE is termed the piezo-photovoltaic effect (PPVE). This thesis report is framed to systemically introduce topics which cause, influence and aid in understanding the PPVE. Topics such as the symmetry in crystals, their physical properties, the intrinsic bulk photovoltaic effect (BPVE) are introduced and the structure, defects, light-induced charge transport in donor doped lithium niobate and the reason behind the appearance of BPVE are discussed in this report. The techniques and experimental arrangements used in this work are detailed in this thesis. A direct evidence of BPVE and the influence of stress is shown in the results. Transition metal doped lithium niobate crystals are oriented via x-ray diffraction (XRD) and a basic chemical characterization is undertaken using secondary ion mass spectrometry (SIMS) to identify dopant elements. Absorption spectroscopy in the UV/VIS/NIR range revealed windows in the spectra indicating photo-excitation of the donor doped ions. The absorption lines show that a shift in the fundamental band-edge occurs in lithium niobate for different dopant elements. Electron paramagnetic resonance (EPR) spectrometry is performed on the samples to confirm the location of the dopant ion in the crystal matrix by indicating its symmetry. The difference in the dopant concentration and the change in the oxidation state of the dopant ion under light illumination is obtained from EPR study. Direct measurements to obtain bulk photovoltaic current density in iron doped- lithium niobate single crystals are performed at increasing intensities at different wavelengths to determine the BPV coefficients. This study provides a quantitative analysis of different components of the BPV tensor values. The highest BPV component measured along the polar axis with extraordinary light polarisation is observed when iron doped lithium niobate is illuminated with light wavelength 450 nm. Obtained BPV tensor components are corroborated by the influence of the structural environment and the dipole interactions on charge transport mechanism of BPVE. The charge transport mechanism and the obtained values of the BPV tensor components are justified and discussed on the basis of the polaronic charge transport phenomena existing in the literature. The influence of stress on BPVE is measured using a custom-designed set-up. The PPV components in lithium niobate are experimentally investigated for stress levels in the 1MPa - 10MPa range. A detailed discussion on the experimental observations are given in this report. The prime discovery of this thesis is the intrinsic character of the piezo-photovoltaic effect (PPVE), where increase in the light induced current is observed when the crystal is subjected to uniaxial compressive stress. The Young's modulus of lithium niobate is 202 GPa. Applying 10 MPa compressive stress translates to strain levels of just 50 ppm. 10 MPa of compressive stress along the polar axis of the crystal increased the short-circuit photo-current by 73%. When stress is applied perpendicular to the polar axis, about 370% increase in short-circuit photocurrent was observed with just 50 ppm of strain, which is a drastic for such moderate amounts of stress levels. This study proves the vitality of strain tuning to increase the PV properties in crystalline solar cells. Extrapolating the observed effect, PPVE is envisioned as a phenomenon which could be exploited in other polar oxide ceramics and thin-films where large photovoltaic energy generation can be made possible beating the existing limits. [less ▲]

The cause of interface recombination in Cu-rich CIS thin film solar cells

Doctoral thesis (2019)

Cu(In,Ga)Se2 (CIGS) thin film solar cells are considered one of the most promising thin film technologies reaching efficiencies beyond 22 %. The record efficiencies for CIGS thin film solar cells are ... [more ▼]

Cu(In,Ga)Se2 (CIGS) thin film solar cells are considered one of the most promising thin film technologies reaching efficiencies beyond 22 %. The record efficiencies for CIGS thin film solar cells are based on CIGS absorbers grown under Cu-deficiency conditions. CIGS absorbers grown under Cu-excess (Cu-rich) show larger grains and better transport properties compared to CIGS absorbers grown under Cu-deficiency (Cu-poor) conditions. However, solar cells based on Cu-rich CIGS absorbers suffer from significantly lower efficiencies compared to Cu-poor CIGS solar cells. The lower efficiency of Cu-rich CIGS solar cells compared to Cu-poor CIGS cells is attributed to lower open circuit voltage (VOC) in Cu-rich CIGS cells compared to Cu-poor CIGS cells. The reason behind the lower VOC values was investigated and was attributed to recombination losses at the absorber/buffer interface and higher doping of Cu-rich CIGS cells compared to Cu-poor CIGS cells but the complete picture behind the origin of these interface recombination losses and high doping in Cu-rich CIGS cells was not fully understood. The work of this thesis explains why Cu-rich CIGS cells suffer from interface recombination losses, higher doping and lower efficiencies. This explanation is divided into three parts: The first part characterizes Cu-rich and Cu-poor solar cells of the ternary CIS and the quaternary CIGS. This part confirms that Cu-rich CI(G)S solar cells suffer from lower efficiencies, lower VOC, interface recombination losses and higher doping compared to Cu-poor CI(G)S solar cells. Moreover, a 200±20 meV defect was observed for Cu-rich CIS cells. The second part introduces different post-deposition treatments (PDTs) to Cu-rich CI(G)S cells. An ex-situ KF, in-situ KF and a Se-only PDT were introduced to Cu-rich CIS cells. All the three treatments succeeded in improving the VOC, improving the interface recombination losses, decreasing the doping and passivating the 200±20 meV defect that has been identified as a Se-related defect in Cu-rich CIS solar cells. A Ga-Se PDT was introduced to Cu-rich CIGS solar cells and successfully improved the VOC, improved the interface recombination losses and decreased the doping of Cu-rich CIGS solar cells. The third part analyses the changes observed on Cu-rich CI(G)S cells before and after the PDTs. Based on these observations, it was concluded that the origin behind both the interface recombination losses and the high doping of Cu-rich CI(G)S cells is a Se-related acceptor defect (detected by admittance measurements for Cu-rich CIS and speculated for Cu-rich CIGS). The passivation of this defect reduces the recombination losses at the absorber/buffer interface, decreases the doping, improves the VOC and consequently leads to an increase in the efficiency of Cu-rich CI(G)S solar cells. Moreover, this part shows that the Se-related defect is formed as a result of the strong etching step that is mandatory for Cu-rich CI(G)S absorbers to remove conductive copper selenide secondary phases. Applying the same strong etching conditions to Cu-poor CIS absorbers leads to the formation of the Se-related defect. After understanding that the Se-related defect is formed as a result of the strong etching conditions and that the Se-related defect can be passivated with PDTs that are rich in Se, an alternative mean of passivating this defect without PDTs was proposed. The Se-related defect was shown to be passivated using buffer layers of high enough thiourea (source of Sulphur) and without any PDTs leading to the reduction of interface recombination losses, decrease of the doping, increase of the VOC and increase of the efficiency of Cu-rich CIS cells. To conclude, the reason behind the interface recombination losses and high doping in Cu-rich CI(G)S solar cells is a Se-related acceptor defect originating after etching the absorbers with strong etching conditions. This defect can be passivated with high enough chalcogen either with PDTs (high enough Selenium) or buffer layers (high enough Sulphur). [less ▲]

Targeted DNA repair gene expression study in Glioblastoma patient biopsies: Clinical impact and characterization of the NEIL3 glycosylase, a novel candidate target for therapy

Doctoral thesis (2019)

MOBILITY ANALYSIS AND PROFILING FOR SMART MOBILITY SERVICES: A BIG DATA DRIVEN APPROACH. An Integration of Data Science and Travel Behaviour Analytics

Doctoral thesis (2019)

Smart mobility proved to be an important but challenging component of the smart cities paradigm. The increased urbanization and the advent of sharing economy require a complete digitalisation of the way ... [more ▼]

Smart mobility proved to be an important but challenging component of the smart cities paradigm. The increased urbanization and the advent of sharing economy require a complete digitalisation of the way travellers interact with the mobility services. New sharing mobility services and smart transportation models are emerging as partial solutions for solving some tra c problems, improve the resource e ciency and reduce the environmental impact. The high connectivity between travellers and the sharing services generates enormous quantity of data which can reveal valuable knowledge and help understanding complex travel behaviour. Advances in data science, embedded computing, sensing systems, and arti cial intelligence technologies make the development of a new generation of intelligent recommendation systems possible. These systems have the potential to act as intelligent transportation advisors that can o er recommendations for an e cient usage of the sharing services and in uence the travel behaviour towards a more sustainable mobility. However, their methodological and technological requirements will far exceed the capabilities of today's smart mobility systems. This dissertation presents a new data-driven approach for mobility analysis and travel behaviour pro ling for smart mobility services. The main objective of this thesis is to investigate how the latest technologies from data science can contribute to the development of the next generation of mobility recommendation systems. Therefore, the main contribution of this thesis is the development of new methodologies and tools for mobility analysis that aim at combining the domain of transportation engineering with the domain of data science. The addressed challenges are derived from speci c open issues and problems in the current state of the art from the smart mobility domain. First, an intelligent recommendation system for sharing services needs a general metric which can assess if a group of users are compatible for speci c sharing solutions. For this problem, this thesis presents a data driven indicator for collaborative mobility that can give an indication whether it is economically bene cial for a group of users to share the ride, a vehicle or a parking space. Secondly, the complex sharing mobility scenarios involve a high number of users and big data that must be handled by capable modelling frameworks and data analytic platforms. To tackle this problem, a suitable meta model for the transportation domain is created, using the state of the art multi-dimensional graph data models, technologies and analytic frameworks. Thirdly, the sharing mobility paradigm needs an user-centric approach for dynamic extraction of travel habits and mobility patterns. To address this challenge, this dissertation proposes a method capable of dynamically pro ling users and the visited locations in order to extract knowledge (mobility patterns and habits) from raw data that can be used for the implementation of shared mobility solutions. Fourthly, the entire process of data collection and extraction of the knowledge should be done with near no interaction from user side. To tackle this issue, this thesis presents practical applications such as classi cation of visited locations and learning of users' travel habits and mobility patterns using historical and external contextual data. [less ▲]

OPTICAL ANALYSIS OF EFFICIENCY LIMITATIONS OF CU(IN,GA)SE2 GROWN UNDER COPPER EXCESS

Doctoral thesis (2019)

Solar cells made from the compound semiconductor Cu(In,Ga)Se2 reach efficiencies of 22:9 % and are thus even better than multi crystalline silicon solar cells. All world records are achieved using ... [more ▼]

Solar cells made from the compound semiconductor Cu(In,Ga)Se2 reach efficiencies of 22:9 % and are thus even better than multi crystalline silicon solar cells. All world records are achieved using absorber layers with an overall copper deficient composition, but Cu-rich grown samples have multiple favourable properties. However, especially losses in the open circuit voltage limit the device performance. Within this work these efficiency limitations of chalcopyrites grown with copper excess are investigated. The work has been divided into four chapters addressing different scientific questions. (i) Do alkali treatments improve Cu-rich absorber layers? The alkali treatment, which lead to the recent improvements of the efficiency world record, is adapted to CuInSe2 samples with Cu-rich composition. The treatment leads to an improvement of the VOC which originates roughly equally from an improvement of the bulk and the removal of a defect close to the interface. The treatment also improves the VOC of Cu-poor samples. In both cases, the treatment increases the fill factor (FF) and leads to a reduction of copper content at the surface. (ii) Is the VOC limited by deep defects in Cu-rich Cu(In,Ga)Se2? A deep defect, which likely limits the VOC, is observed in photoluminescence measurements (PL) independent of a surface treatment. The defect level is proposed to originate from the second charge transition of the CuIn antisite defect (CuIn(-1/-2)). During the investigation also a peak at 0:9 eV is detected and attributed to a DA-transition involving a third acceptor situated (135 ± 10) meV above the valence band. The A3 proposed to originate from the indium vacancy (VIn). Furthermore the defect was detected in admittance measurements and in Cu(In,Ga)Se2 samples with low gallium content. (iii) Is the diode factor intrinsically higher in Cu-rich chalcopyrites? Cu-rich solar cells exhibit larger diode ideality factors which reduce the FF. A direct link between the power law exponent from intensity dependent PL measurements of absorbers and the diode factor of devices is derived and verified using Cu-poor Cu(In,Ga)Se2 samples. This optical diode factor is the same in Cu-rich and Cu-poor samples. (iv) Is the quasi Fermi level splitting (qFLs) of Cu-rich Cu(In,Ga)Se2 absorber layers comparable to Cu-poor samples? Measuring the qFLs of passivated Cu-rich and Cu-poor Cu(In,Ga)Se2 samples, on average a 120 meV lower splitting is determined for Cu-rich samples. This difference increases with gallium content and is likely linked to a defect moving deeper into the bandgap, possibly related to the second charge transition of the CuIn antisite defect. Overall, samples with Cu-rich composition are not limited by the diode factor. However, a deep defect band causes recombination lowering the qFLs and thus the VOC. This defect is not removed by alkali treatments. A key component to improve Cu-rich solar cells in the future, especially Cu(In,Ga)Se2, will be to remove or passivate this defect level. [less ▲]

DEUTSCHE SOLDATENGRÄBER DES ZWEITEN WELTKRIEGES ZWISCHEN HELDENVERHERRLICHUNG UND ZEICHEN DER VERSÖHNUNG – KULTURWISSENSCHAFTLICH-HISTORISCHE FALLSTUDIEN ZUR ENTWICKLUNG DES UMGANGES MIT DEM KRIEGSTOD

Doctoral thesis (2019)

Ten cultural-historical case studies investigate how deaths in war were dealt with based on soldier graves of the Second World War. In this dissertation, the resting places of the fallen German soldiers ... [more ▼]

Ten cultural-historical case studies investigate how deaths in war were dealt with based on soldier graves of the Second World War. In this dissertation, the resting places of the fallen German soldiers offer a unique perspective in the evaluation of death during a violent conflict and in the post-war period. The examination frame extends from 1939 to the present and follows the reception and importance of the graves and the fallen in military, politics and society. Some single chapters of this thesis have been already published or are intended for publication. Methodologically, the study consists of empirical work, such as the analysis of unpublished archival sources, as well as hermeneutical tools in the form of interviews, surveys, local documentation, and field studies of burial sites and exhumations. Two terms – hero glorification and signs of reconciliation – illustrate the differences in how the meaning of the graves and their dead soldiers was perceived. This difference highlights the change in values and meaning that the graves had to face. In the Second World War, the Wehrmacht responded to the nearly five million German casualties with mythical hero stories, propaganda and parades, but also with an elaborate administration system and rules concerning the dead and their graves. The instructions for the soldier’s death included details about the material and inscription of the gravestone to the identification of unknown dead. The graves sustained a structure and organization in accordance with a modern military grave system. The claim to a single grave and the registration and notification of the relatives was included in the Wehrmacht. The denotation of the dead as heroes and their resting places as heroes' graves (Heldengräber) and heroes' groves (Heldenhaine) shows the attempt to integrate them into the ideology and propaganda of the National Socialist regime. However, the management of graves, as well as the cult of heroes, had to fail due to the reality of war – i.e., the number of casualties, the chaotic conditions at the front and the defeat of the Germans. The hero's glorification could not be maintained after the end of the war. In post-war society, an attempt was made to defuse the symbolism of military death and put it into a neutral and harmless context other than National Socialism. The continuation of the graves’ management, the search for unknown resting places and the construction of cemeteries could no longer be operated by the military. Under the slogan of reconciliation and the expression of peace and understanding instead, access to the Wehrmacht graves was reached first in Western Europe, after 1989 in Eastern Europe by the Volksbund Deutsche Kriegsgräberfürsorge e.V. The Volksbund builds and cares for cemeteries and exhumes the remains until the present. This effort is still being made by the Germans today and illustrates the importance of war graves care in modern international context. The studies show how mutable and dependent are the meaning and symbolism of the death of a soldier within different political and social constructs and epochs. In these studies, the range of soldiers' graves as a research topic is clarified and further perspectives for questions and investigation contexts are shown. The investigation of German soldiers' graves of the Second World War in terms of their relevance is of particular importance. The fact that great efforts are still being made to find and maintain the resting places of dead soldiers more than 70 years after the war demonstrates the political dimension of the war dead and their graves. Above all, the distinctiveness of these objects as resting places for German soldiers makes an interesting and even controversial topic for science, politics and society not only in Germany but also in other European countries. [less ▲]

Investigating trust in a multilingual theatre project: Potentialities for a humanising pedagogy

Doctoral thesis (2019)

Education plays a vital role in shaping social realities by promoting dialogue, solidarity, mutual understanding, and positive social interactions. However, some pedagogical approaches are believed to not ... [more ▼]

Education plays a vital role in shaping social realities by promoting dialogue, solidarity, mutual understanding, and positive social interactions. However, some pedagogical approaches are believed to not shoulder the responsibility to counter current social, economic, and political forces in Europe and beyond that present challenges in terms of social cohesion and ways of living together. This study contributes to recent debates concerning a change of dominant school practices by recognising learning and teaching as collaborative processes between teachers and students and trust as a central element in education. Despite the interest in and positive appraisal of trust in education, little attention has been paid to concrete teaching practices and strategies on how to implement trust in learning and teaching. A case study of a multilingual theatre project of a primary school class and a video ethnographic approach allowed to explore details of classroom practices, (inter-)actions, and activities. This research set out to explore four questions: (a) What are “signs of trust” in an educational context?; (b) How and in what ways can a teacher build, maintain, or strengthen trust?; (c) How and in what ways can “signs of trust” shape interactions in the classroom?; (d) How can “sings of trust” be analysed? As a result of more than 80 hours of video-recorded participant observations and interview data, the results of this investigation show that the classroom teacher continuously and consistently maintained a work environment based on six attributes of trust identified in the literature: vulnerability, benevolence, reliability, competence, honesty, and openness. Most importantly, she valued and promoted responsibility, autonomy, collaboration, and peer support. The teacher’s verbal and non-verbal trustworthy and trusting behaviour is then interpreted as the driving force behind the pupils’ engagement as active, competent, and reliable partners in all aspects of the theatre project. In fact, the pupils signalled ownership of their learning, proactively and independently engaged with the curriculum, and positively oriented towards each other’s relationships and competences. Despite the exploratory nature and small sample of participants, the findings of this study highlight that education imbued with trust offers opportunities of growth for both teachers and students. Moreover, the data suggests that the achievement and maintenance of trust can be seen as a collaborative effort involving all members of the classroom community and facilitated by a myriad of meaning-making resources (verbal, non-verbal, with objects, even a simple look in the eye or a smile). If the debate about the value of trust for all learners is to be moved forward, a better understanding of the wider impacts on personal and social lives needs to be gained. [less ▲]

FUNCTIONAL CHARACTERISATION OF THE A30P MUTATION IN ALPHA-SYNUCLEIN GENE IN A PATIENT-DERIVED CELLULAR MODEL OF PARKINSON’S DISEASE

Doctoral thesis (2019)

Our study aims to perform detailed phenotyping of the A30P alpha-synuclein familial case of PD, allowing to identify underlying mechanisms of the disease that may translate into novel therapies ... [more ▼]

Our study aims to perform detailed phenotyping of the A30P alpha-synuclein familial case of PD, allowing to identify underlying mechanisms of the disease that may translate into novel therapies. Parkinson’s disease (PD) is the second most common neurodegenerative disease. Approximately 20% of PD cases are known to have a genetic cause. From these, mutations in SNCA, the gene encoding alpha-synuclein, are linked to an autosomal dominant inheritance of the disease. In 1998, our group discovered the second known point mutation within the SNCA gene, causing an A30P exchange of the peptide sequence. We generated first patient-derived cellular model of the A30P alpha-synuclein mutation carrier, by obtaining fibroblasts from an affected sibling of the index patient, an unaffected sibling of the patient, and an age-matched gender-matched non-PD control. We reprogrammed these fibroblasts into induced pluripotent stem cells (iPSCs), and differentiated them into midbrain dopaminergic neurons. We obtained enriched cultures of 80% midbrain neurons (FoxA2+/Tuj1+), with approximately 12 % dopaminergic (TH+), for which we observed electrophysiological activity and dopamine release. We detected a significant reduction of the protein level of mitochondria complexes II, IV, and V in the patient lines compared with the controls, additionally we found a significant impairment of mitochondrial respiration and an increased susceptibility of the cells to oxidative stress. Gene-edited isogenic controls were generated to dissect mutation-specific effects. Furthermore, we investigated mitochondrial morphology and dynamics, and how these processes contribute to the dopaminergic neurodegeneration. Additionally, we were implementing previously established readouts on our high-throughput automated screening platform that will allow us to identify FDA approved compounds with potential to be re-purposed and used as PD treatment. We believe that detailed phenotyping of the A30P alpha-synuclein monogenic case may help to identify underlying mechanisms of the disease that may translate into novel therapies, which would also apply to the more common sporadic forms of PD. [less ▲]

From Information Theory Puzzles in Deletion Channels to Deniability in Quantum Cryptography

Doctoral thesis (2019)

Research questions, originally rooted in quantum key exchange (QKE), have branched off into independent lines of inquiry ranging from information theory to fundamental physics. In a similar vein, the ... [more ▼]

Research questions, originally rooted in quantum key exchange (QKE), have branched off into independent lines of inquiry ranging from information theory to fundamental physics. In a similar vein, the first part of this thesis is dedicated to information theory problems in deletion channels that arose in the context of QKE. From the output produced by a memoryless deletion channel with a uniformly random input of known length n, one obtains a posterior distribution on the channel input. The difference between the Shannon entropy of this distribution and that of the uniform prior measures the amount of information about the channel input which is conveyed by the output of length m. We first conjecture on the basis of experimental data that the entropy of the posterior is minimized by the constant strings 000..., 111... and maximized by the alternating strings 0101..., 1010.... Among other things, we derive analytic expressions for minimal entropy and propose alternative approaches for tackling the entropy extremization problem. We address a series of closely related combinatorial problems involving binary (sub/super)-sequences and prove the original minimal entropy conjecture for the special cases of single and double deletions using clustering techniques and a run-length encoding of strings. The entropy analysis culminates in a fundamental characterization of the extremal entropic cases in terms of the distribution of embeddings. We confirm the minimization conjecture in the asymptotic limit using results from hidden word statistics by showing how the analytic-combinatorial methods of Flajolet, Szpankowski and Vallée, relying on generating functions, can be applied to resolve the case of fixed output length and n → ∞. In the second part, we revisit the notion of deniability in QKE, a topic that remains largely unexplored. In a work by Donald Beaver it is argued that QKE protocols are not necessarily deniable due to an eavesdropping attack that limits key equivocation. We provide more insight into the nature of this attack and discuss how it extends to other prepare-and-measure QKE schemes such as QKE obtained from uncloneable encryption. We adopt the framework for quantum authenticated key exchange developed by Mosca et al. and extend it to introduce the notion of coercer-deniable QKE, formalized in terms of the indistinguishability of real and fake coercer views. We also elaborate on the differences between our model and the standard simulation-based definition of deniable key exchange in the classical setting. We establish a connection between the concept of covert communication and deniability by applying results from a work by Arrazola and Scarani on obtaining covert quantum communication and covert QKE to propose a simple construction for coercer-deniable QKE. We prove the deniability of this scheme via a reduction to the security of covert QKE. We relate deniability to fundamental concepts in quantum information theory and suggest a generic approach based on entanglement distillation for achieving information-theoretic deniability, followed by an analysis of other closely related results such as the relation between the impossibility of unconditionally secure quantum bit commitment and deniability. Finally, we present an efficient coercion-resistant and quantum-secure voting scheme, based on fully homomorphic encryption (FHE) and recent advances in various FHE primitives such as hashing, zero-knowledge proofs of correct decryption, verifiable shuffles and threshold FHE. [less ▲]

Co-evolutionary Hybrid Bi-level Optimization

Doctoral thesis (2019)

Multi-level optimization stems from the need to tackle complex problems involving multiple decision makers. Two-level optimization, referred as ``Bi-level optimization'', occurs when two decision makers ... [more ▼]

Multi-level optimization stems from the need to tackle complex problems involving multiple decision makers. Two-level optimization, referred as ``Bi-level optimization'', occurs when two decision makers only control part of the decision variables but impact each other (e.g., objective value, feasibility). Bi-level problems are sequential by nature and can be represented as nested optimization problems in which one problem (the ``upper-level'') is constrained by another one (the ``lower-level''). The nested structure is a real obstacle that can be highly time consuming when the lower-level is $\mathcal{NP}-hard$. Consequently, classical nested optimization should be avoided. Some surrogate-based approaches have been proposed to approximate the lower-level objective value function (or variables) to reduce the number of times the lower-level is globally optimized. Unfortunately, such a methodology is not applicable for large-scale and combinatorial bi-level problems. After a deep study of theoretical properties and a survey of the existing applications being bi-level by nature, problems which can benefit from a bi-level reformulation are investigated. A first contribution of this work has been to propose a novel bi-level clustering approach. Extending the well-know ``uncapacitated k-median problem'', it has been shown that clustering can be easily modeled as a two-level optimization problem using decomposition techniques. The resulting two-level problem is then turned into a bi-level problem offering the possibility to combine distance metrics in a hierarchical manner. The novel bi-level clustering problem has a very interesting property that enable us to tackle it with classical nested approaches. Indeed, its lower-level problem can be solved in polynomial time. In cooperation with the Luxembourg Centre for Systems Biomedicine (LCSB), this new clustering model has been applied on real datasets such as disease maps (e.g. Parkinson, Alzheimer). Using a novel hybrid and parallel genetic algorithm as optimization approach, the results obtained after a campaign of experiments have the ability to produce new knowledge compared to classical clustering techniques combining distance metrics in a classical manner. The previous bi-level clustering model has the advantage that the lower-level can be solved in polynomial time although the global problem is by definition $\mathcal{NP}$-hard. Therefore, next investigations have been undertaken to tackle more general bi-level problems in which the lower-level problem does not present any specific advantageous properties. Since the lower-level problem can be very expensive to solve, the focus has been turned to surrogate-based approaches and hyper-parameter optimization techniques with the aim of approximating the lower-level problem and reduce the number of global lower-level optimizations. Adapting the well-know bayesian optimization algorithm to solve general bi-level problems, the expensive lower-level optimizations have been dramatically reduced while obtaining very accurate solutions. The resulting solutions and the number of spared lower-level optimizations have been compared to the bi-level evolutionary algorithm based on quadratic approximations (BLEAQ) results after a campaign of experiments on official bi-level benchmarks. Although both approaches are very accurate, the bi-level bayesian version required less lower-level objective function calls. Surrogate-based approaches are restricted to small-scale and continuous bi-level problems although many real applications are combinatorial by nature. As for continuous problems, a study has been performed to apply some machine learning strategies. Instead of approximating the lower-level solution value, new approximation algorithms for the discrete/combinatorial case have been designed. Using the principle employed in GP hyper-heuristics, heuristics are trained in order to tackle efficiently the $\mathcal{NP}-hard$ lower-level of bi-level problems. This automatic generation of heuristics permits to break the nested structure into two separated phases: \emph{training lower-level heuristics} and \emph{solving the upper-level problem with the new heuristics}. At this occasion, a second modeling contribution has been introduced through a novel large-scale and mixed-integer bi-level problem dealing with pricing in the cloud, i.e., the Bi-level Cloud Pricing Optimization Problem (BCPOP). After a series of experiments that consisted in training heuristics on various lower-level instances of the BCPOP and using them to tackle the bi-level problem itself, the obtained results are compared to the ``cooperative coevolutionary algorithm for bi-level optimization'' (COBRA). Although training heuristics enables to \emph{break the nested structure}, a two phase optimization is still required. Therefore, the emphasis has been put on training heuristics while optimizing the upper-level problem using competitive co-evolution. Instead of adopting the classical decomposition scheme as done by COBRA which suffers from the strong epistatic links between lower-level and upper-level variables, co-evolving the solution and the mean to get to it can cope with these epistatic link issues. The ``CARBON'' algorithm developed in this thesis is a competitive and hybrid co-evolutionary algorithm designed for this purpose. In order to validate the potential of CARBON, numerical experiments have been designed and results have been compared to state-of-the-art algorithms. These results demonstrate that ``CARBON'' makes possible to address nested optimization efficiently. [less ▲]

Sociographie des associations islamiques au Luxembourg, à l'aune de l'institutionnalisation

Doctoral thesis (2019)

Supporting Change in Product Lines Within the Context of Use Case-driven Development and Testing

Doctoral thesis (2019)

Product Line Engineering (PLE) is a crucial practice in many software development environments where systems are complex and developed for multiple customers with varying needs. At the same time, many ... [more ▼]

Product Line Engineering (PLE) is a crucial practice in many software development environments where systems are complex and developed for multiple customers with varying needs. At the same time, many business contexts are use case-driven where use cases are the main artifacts driving requirements elicitation and many other development activities. In these contexts, variability information is often not explicitly represented, which leads to ad-hoc change management for use cases, domain models and test cases in product families. In this thesis, we address the problems of modeling variability in requirements with additional traceability to feature models and the manual and error prone requirements configuration and regression testing in product families. We provide the following contributions: - A modeling method for capturing variability information in product line use case and domain models by relying exclusively on commonly used artifacts in use-case driven development, thus avoiding unnecessary modeling overhead. - An approach for automated configuration of product specific use case and domain models that guides customers in making configuration decisions and automatically generates use case diagrams, use case specifications, and domain models for configured products. - A change impact analysis approach for evolving configuration decisions in product line use case models that automatically identifies the impact of decision changes on other decisions, and incrementally reconfigures product specific use case diagrams and specifications for evolving decisions. - An approach for automated classification and prioritization of system test cases in a family of products that automatically classifies and prioritizes, for each new product, system test cases of previous product(s) in a product line, and provides guidance in modifying existing system test cases to cover new use case scenarios that have not been tested in the product line before. All our approaches have been developed and evaluated in close collaboration with our industry partner IEE. [less ▲]

Decentring the Museum: Examining Young People's Perceptions and Experiences from a Sociocultural Perspective.

Doctoral thesis (2019)

The relationship between young people and museums has been a topic of discussion since the late 1970s. Many developments have been observed in this respect, yet some museums still find it challenging to ... [more ▼]

The relationship between young people and museums has been a topic of discussion since the late 1970s. Many developments have been observed in this respect, yet some museums still find it challenging to engage with young people. Furthermore, the debate surrounding this relationship is often underpinned by unhelpful generalisations about young people that impede thinking and practice; for example, that young people lack interest in museums or find them boring. Previous research has principally investigated the subject through an ‘education and learning’ lens and from a perspective that takes museums as the starting point. This thesis aims to enrich our understanding by taking a sociocultural perspective and by centring the focus on young people. The thesis, therefore, actively seeks to decentre the museum: theoretically, by using an interdisciplinary framework; and practically, by conducting fieldwork outside museums. Through a qualitative approach, this study places young people’s experiences and perceptions of museums in a wider social and cultural context. Focus groups were conducted with young people aged 12–21 in youth clubs in Luxembourg. This thesis reveals the complex and nuanced ways in which the focus-group participants think about museums in relation to their everyday lives. It also highlights the tensions and ambivalence underlying their perceptions and experiences. Furthermore, the study shows that the power inequalities that young people face in social life are likely to be perpetuated in the museum. Indeed, the participants’ experiences of museums are shaped, in large part, by lack of individual choice. Visits that are enforced by facilitators, such as the school and the family, can create barriers to engagement. This thesis makes the case that it is important for museums and facilitators to acknowledge the diversity of young people, hear and value their points of view, and respect their autonomy and freedom of choice. [less ▲]

Essays on Convertibles and Stock Markets

Doctoral thesis (2019)

Automated Identification of National Implementations of European Union Directives With Multilingual Information Retrieval Based On Semantic Textual Similarity

Doctoral thesis (2019)

The effective transposition of European Union (EU) directives into Member States is important to achieve the policy goals defined in the Treaties and secondary legislation. National Implementing Measures ... [more ▼]

The effective transposition of European Union (EU) directives into Member States is important to achieve the policy goals defined in the Treaties and secondary legislation. National Implementing Measures (NIMs) are the legal texts officially adopted by the Member States to transpose the provisions of an EU directive. The measures undertaken by the Commission to monitor NIMs are time-consuming and expensive, as they resort to manual conformity checking studies and legal analysis. In this thesis, we developed a legal information retrieval system using semantic textual similarity techniques to automatically identify the transposition of EU directives into the national law at a fine-grained provision level. We modeled and developed various text similarity approaches such as lexical, semantic, knowledge-based, embeddings-based and concept-based methods. The text similarity systems utilized both textual features (tokens, N-grams, topic models, word and paragraph embeddings) and semantic knowledge from external knowledge bases (EuroVoc, IATE and Babelfy) to identify transpositions. This thesis work also involved the development of a multilingual corpus of 43 directives and their corresponding NIMs from Ireland (English legislation), Italy (Italian legislation) and Luxembourg (French legislation) to validate the text similarity based information retrieval system. A gold standard mapping (prepared by two legal researchers) between directive articles and NIM provisions was prepared to evaluate the various text similarity models. The results show that the lexical and semantic text similarity techniques were more effective in identifying transpositions as compared to the embeddings-based techniques. We also observed that the unsupervised text similarity techniques had the best performance in case of the Luxembourg Directive-NIM corpus. We also developed a concept recognition system based on conditional random fields (CRFs) to identify concepts in European directives and national legislation. The results indicate that the concept recognitions system improved over the dictionary lookup program by tagging the concepts which were missed by dictionary lookup. The concept recognition system was extended to develop a concept-based text similarity system using word-sense disambiguation and dictionary concepts. The performance of the concept-based text similarity measure was competitive with the best performing text similarity measure. The labeled corpus of 43 directives and their corresponding NIMs was utilized to develop supervised text similarity systems by using machine learning classifiers. We modeled three machine learning classifiers with different textual features to identify transpositions. The results show that support vector machines (SVMs) with term frequency-inverse document frequency (TF-IDF) features had the best overall performance over the multilingual corpus. Among the unsupervised models, the best performance was achieved by TF-IDF Cosine similarity model with macro average F-score of 0.8817, 0.7771 and 0.6997 for the Luxembourg, Italian and Irish corpus respectively. These results demonstrate that the system was able to identify transpositions in different national jurisdictions with a good performance. Thus, it has the potential to be useful as a support tool for legal practitioners and Commission officials involved in the transposition monitoring process. [less ▲]

AUSLANDSSTUDIUM AN DER SCHWELLE ZUM ERWACHSENWERDEN. AUSGESTALTUNG UND BEDEUTUNG DES AUSLANDSAUFENTHALTES UNTER CREDIT UND DEGREE STUDIERENDEN AUS LUXEMBURG

Doctoral thesis (2019)

Impacts of Agroecology-based Development Programs on Smallholder Farmers’ Livelihoods in Eastern Burkina Faso

Doctoral thesis (2019)

Learning from 30 years of transition- A reconstruction of sustainable development in Beckerich and its implications on Luxembourgish rural development

Doctoral thesis (2019)

A study of the molecular mechanisms underlying the response of human colorectal adenomacarcinoma enterocytes to prebiotics and probiotics

Doctoral thesis (2018)

The human gastrointestinal tract (GIT) microbiome plays essential roles in maintaining human health. A variety of diseases including colorectal cancer (CRC) are associated with microbial dysbiosis ... [more ▼]

The human gastrointestinal tract (GIT) microbiome plays essential roles in maintaining human health. A variety of diseases including colorectal cancer (CRC) are associated with microbial dysbiosis. Administration of microbial isolates associated with health benefits (e.g. prebiotics) together with specific dietary components (e.g., probiotics) may find application as supportive therapeutic options in the treatment and management of CRC. Although microbiome-modulating therapeutics hold great promise, such approaches are presently not formally integrated into treatment plans. To obtain better understanding of combined pre- and probiotic regimens in relation to CRC, the present study was dedicated to investigate the effects of selected prebiotics on the proliferation of CRC primary cells and conventional CRC-cell lines, the effects of prebiotics on the growth and metabolism of selected probiotic strains, and the combinatorial/synbiotic effects of selected pre- and probiotics on CRC proliferation. In addition, this work established the in vitro gut-on-a chip HuMiX model with a simulated high-fibre medium for co-culturing human and microbial cells in HuMiX. Furthermore, the anti-carcinogenic combinatorial effects of dietary fiber (e.g., prebiotics), and GIT bacteria (e.g., probiotics) were evaluated using human GIT transcriptomes and metabolomes in HuMiX. An integrated in vitro and in silico modeling approach was finally established to decipher the complex cross-talk between gut bacteria, dietary components and human host cells. My results demonstrate that in stark contrast to the individual pre- or probiotic treatments, the synbiotic regimen of the probiotic Lactobacillus rhamnosus GG and dietary fiber results in the down-regulation of genes involved in pro-carcinogenic pathways and drug resistance (e.g., ABC transporters) and reduced levels of the oncometabolite lactate. Distinct ratios of organic and short-chain fatty acids are produced during the simulated regimens. Treatment of primary CRC-derived cells with a molecular cocktail reflecting the synbiotic regimen attenuated self-renewal capacity. The developped integrated in vitro and in silico modelling approach provides mechanistic insights into the interplay between pre- and probiotics and elucidation of the microbiota-host relationship. In summary, my dissertation work illustrates the potential of HuMiX to be used for nutritional studies and more precisely for studying the underlying mechanisms of the effects that dietary components (e.g., dietary fiber) and probiotics have on CRC-derived cells. Thereby, this dissertation work highlights the potential for formulating efficacious dietary supplements including synbiotics in the context of therapeutic regimens for microbiome-linked diseases in the future. [less ▲]

Essays on Chinese Internal Migrant Workers' Choices: Children's location and education

Doctoral thesis (2018)

Droit de la consommation et régime de l'obligation. Essai de construction d’un régime de l’obligation consumériste au travers de l’exemple de la prescription

Doctoral thesis (2018)

While Civil law is traditionally based on equality between contractors, Consumer protection Law was built around the notion of unbalanced contractual relationship, the consumer being the weaker party ... [more ▼]

While Civil law is traditionally based on equality between contractors, Consumer protection Law was built around the notion of unbalanced contractual relationship, the consumer being the weaker party. This study revolves around limitation periods and foreclosure, known to be Civil law mechanisms, and their use and reception by Consumer Law. Is the two year period granted to the professional to seek specific performance likely to be interrupted ? Do negociations revolving around a purchased good’s hidden defects suspend the brief period granted to the consumer to claim for specific performance ? How does French Consumer Protection Law allocate late payment of debts that have been extinguished by the statute of limitations ? This study consists in systematic analyses of available litigations obtained through courts' Open data. It aims to highlight phenomena such as rules resumption, rules adjustment or rules creation through the problematic of unbalanced, B to C, contractual relationships. Three sights were fixed for this purpose : - demonstrating how inadequate Civil Law, Consumer Law and Commercial Law are considering the contractual unbalances inherent to B to C relationships, through some examples of mass litigations (nature of the statute of limitations, commencement date of the limitation period, causes for interruption and suspension of the limitation period, court’s function) ; - highlighting the lack of strong, unchanging jurisprudence on the subject, at the expense of legal safety and legal rules quality ; - offering a new, rational model of limitation period for Consumer Law, taking into account the very specific problematics of each parties. The result of the above study could provide the basis for a reflection on a new Consumer legislation. [less ▲]

Defining, Measuring, and Enabling Transparency for Electronic Medical Systems

Doctoral thesis (2018)

Transparency is a novel concept in the context of Information and Communication Technology (ICT). It has arisen from regulations as a data protection principle, and it is now being studied to encompass ... [more ▼]

Transparency is a novel concept in the context of Information and Communication Technology (ICT). It has arisen from regulations as a data protection principle, and it is now being studied to encompass the peculiarities of digital information. Transparency, however, is not the first security concept to be borrowed from regulations; privacy once emerged from discussions on individual’s rights. Privacy began to be vigorously debated in 1890, when Warren and Brandeis analysed legal cases for which penalties were applied on the basis of defamation, infringement of copyrights, and violation of confidence. The authors defended that those cases were, in fact, built upon a broader principle called privacy. But privacy was only given a structured definition almost one century later, in 1960, when Prosser examined cases produced after Warren and Brandeis’ work, classifying violation of privacy into four different torts; it took twenty years more before the concept was thoroughly studied for its functions in ICT. Guidelines by the OECD outlined principles to support the discussion of privacy as a technical requirement. Proceeded by international standards for a privacy framework (ISO/IEC 29100), which translated the former legal concepts into information security terms, such as data minimisation, accuracy, and accountability. Transparency has a younger, but comparable history; the current General Data Protection Regulation (GDPR) defines it as a principle which requires “that any information and communication relating to the processing of those personal data be easily accessible and easy to understand [..]". However, other related and more abstract concepts preceded it. In the Health Insurance Portability and Accountability Act (HIPAA) of 1996, the Privacy Rule demands to document privacy policies and procedures and to notify individuals of uses of their health information. Former European Directives, i.e., 95/46/EC and 2011/24/EU, establish “the right for individuals to have access to their personal data concerning their health [..] also in the context of cross-border healthcare”. The same did the Freedom of Information Act (FOIA) of 1966, instituting that any person has a right to obtain from agencies information regarding their records. These and other similar requests refer to the transversal quality called transparency. Similarly to what happened with privacy, transparency was also the subject of guidelines that clarify its interpretation in ICT. However, no framework or standard has been defined yet that translates transparency into a technical property. This translation is the goal of our work. This thesis is dedicated to debate existing interpretations for transparency, to establish requirements and measurement procedures for it, and to study solutions that can help systems adhere to the transparency principle from a technical perspective. Our work constitutes an initial step towards the definition of a framework that helps accomplish meaningful transparency in the context of Electronic Medical Systems. [less ▲]

Integration of omics data for biotechnology-relevant microbial communities

Doctoral thesis (2018)

Naturally occurring and artificial bacterial communities play an import role in many biotechnological processes. To elucidate bacterial interactions that are important for potential optimized ... [more ▼]

Naturally occurring and artificial bacterial communities play an import role in many biotechnological processes. To elucidate bacterial interactions that are important for potential optimized biotechnological applications, high-throughput measurements of biomolecules, metagenomics, metratranscriptomics,metaproteomics, and meta-metabolomics provide a detailed snapshot of mixed microbial consortia. Integration of multiple layers of omics data allows to reconstruct structure and function of complex microbial communities and is demonstrated for two different model systems. The first chapter focuses on synthetic communities consisting of strains representing key species found in biomining operations and acid mine drainage and that are of economical interest for copper production. A high-quality closed reference genome for L. ferriphilum was obtained by DNA sequencing and was subsequently used to integrate functional omics data, i.e. transcriptomic and proteomic profiling. The combination of genomics, genome annotation, and functional omics data allowed an in-depth characterization of L. ferriphilum in culture medium and in the presence of the iron sulfide mineral chalcopyrite, an economically relevant copper ore. Subsequently, analyses were performed for co-cultures of up to three organisms highlighting specific interaction mechanisms. The cultures without L. ferriphilum showed higher copper solubilisation rates, as the highly efficient iron oxidiser might raise the redox potential above the optimal range. For in situ studies, reference-based analyses are of limited use, e.g. due to a lack in reference genomes of culturable isolates. Hence, the second chapter focuses on an approach to study mixed microbial communities independent of prior knowledge and available reference genomes. A timeseries of oleaginous floating sludge samples that spans over one and a half years was analysed by integrating metagenomic, metatranscriptomic, metaproteomic, and meta-metabolomic data. This allowed the reconstruction of population level genomes and the characterization of the niches of the respective populations. The functional potential was assessed, as well as expression profiles over time, yielding a detailed view on lifestyle strategies and the potential impact of abiotic factors. Understanding the niche ecology of the predominant lipid accumulators in the system could lead towards optimized biofuel production. [less ▲]

Analysis of the cohesive zone behaviour through advanced multi-physics simulation technology

Doctoral thesis (2018)

Entrepreneurial Teams, New Venture Direction and Growth: Evidence from Luxembourg

Doctoral thesis (2018)

New ventures can be an important driver of economic growth and technological progress. Yet, many new ventures fail and do not overcome the challenges of the early entrepreneurial phase. Extant research ... [more ▼]

New ventures can be an important driver of economic growth and technological progress. Yet, many new ventures fail and do not overcome the challenges of the early entrepreneurial phase. Extant research has acknowledged that the people who jointly start and manage a new venture have a key impact on its subsequent success and development. However, a discrepancy exists in how the interplay of their characteristics, cognition, and actions ultimately shape the way a new venture evolves. Therefore the primary purpose of this thesis is to contribute to this research stream by exploring the multifaceted role of entrepreneurial teams for new venture direction and growth. This is done with the aid of three research papers relying on a multiple case study and a specifically designed dataset from Luxembourg. The first paper illuminates how the shared pre-start-up transition moments of entrepreneurial team members influence the joint decision logic in the initial venture phase. Focusing on the composition of entrepreneurial teams, the second paper illustrates early activities that allow new ventures to leverage the diverse educational backgrounds of their team members to achieve financial growth. Lastly, the third paper explores aspects of leadership in new ventures and uncovers how agreement on an early shared vision affects subsequent changes in the entrepreneurial team, taking into account members’ relational ties. This thesis makes important contributions to research in entrepreneurship and strategic management, adding to a more fine-grained view on the micro-foundations and outcomes of entrepreneurial action. Also, it has practical implications for entrepreneurs, their mentors and investors, entrepreneurship education and policymakers. [less ▲]

Zebrafish models of Dravet syndrome: discovery of antiseizure drug leads and analysis of behavioural comorbidities

Doctoral thesis (2018)

Dravet syndrome (DS) is one of the most frequent genetic epilepsies, with an incidence of 1/30,000. Most DS patients are pharmacoresistant, in that they do not respond adequately to currently available ... [more ▼]

Dravet syndrome (DS) is one of the most frequent genetic epilepsies, with an incidence of 1/30,000. Most DS patients are pharmacoresistant, in that they do not respond adequately to currently available anticonvulsant drugs (ASDs). Beside the seizure occurrence in these patients, many DS patients also suffer from cognitive impairment that can be aggravated by some of the seizure medications prescribed. Preclinical models such as mouse models of Dravet syndrome have been developed and described to exhibit cognitive deficits similar to those of DS patients, but are only suitable for the evaluation of small number of compounds, thereby limiting their utility for drug discovery. An animal model with higher screening throughput would therefore be of value for drug discovery efforts focused on seizure reduction and decrease of the comorbidities associated with DS. Recent studies on zebrafish have demonstrated its ability to be a promising in vivo model for DS. Two different zebrafish DS models - one based on a loss-of-function mutation in the zebrafish ortholog of SCN1A, the other based on an antisense knockdown of this gene - exhibit seizure-like behaviour and epileptiform discharges that are exacerbated by hyperthermia. The mutant line was also described to display greater anxiety levels. In this Doctoral thesis project, we are investigating these zebrafish DS models with regard to (1) their seizure occurrence and potential reduction following exposure to several anticonvulsant drug candidates, and (2), their cognitive functions in order to determine possible similarities with cognitive impairment in human DS patients. Our results indicate these zebrafish DS models to exhibit memory impairment and higher anxiety levels. These findings provide an initial insight into the resemblance between human patients and zebrafish in terms of comorbidities. Finally, we also identified several novel anticonvulsant compounds and drug candidates with antiseizure activity in these zebrafish DS models. [less ▲]

Link Optimization in Future Generation Satellite Systems

Doctoral thesis (2018)

In recent years, communication networks have seen a huge growth in the amount of requested throughput, pushed from the combination of two main drivers: the introduction of new services and the improvement ... [more ▼]

In recent years, communication networks have seen a huge growth in the amount of requested throughput, pushed from the combination of two main drivers: the introduction of new services and the improvement of existing ones, requiring increased amount of traffic (e.g. higher quality of video content). These effects mandate the constant evolution of current systems in order to cope with the growing user demand and should be tackled from multiple angles. On the one hand, better utilization of available resources might help in the short term to keep up with the market and has always been an important priority for operators of terrestrial and satellite networks alike. On the other hand, acquisition and exploitation of currently unused resources might fuel the growth for a significantly longer period of time, ensuring longevity and thus enabling future-proofing of current systems. Both these topics are addressed in this thesis with specific applications relevant to satellite communication networks. In the first part, this thesis focuses on maximization of the user capacity by better exploiting the available radio resources. Motivated by the substantial capacity gains enabled by a higher bandwidth allocation, we investigate the optimization of satellite systems employing full-frequency reuse on the user downlink. Unlike most of the literature on the subject, usually resorting to precoding techniques to mitigate the interference, we propose a combination of predistortion and precoding to jointly counteract on-board non-linear distortions and multi-user interference. First, a flexible framework for the optimization of transmit processing schemes in communication chains is presented. This framework expands on the application of the well known gradient descent technique by applying it to the maximization of the received Signal to Noise plus Interference ratio in complex communication systems. To do so, it identifies a suitable mathematical representation of various key blocks of the system and exploits the chain rule of the derivative to compute the overall gradient as a cascade of the single components. Afterwards, this framework is validated by optimizating the coefficients of the proposed predistortion architecture for the satellite system in analysis. The obtained results highlight the flexibility of the developed optimization framework and the benefits of the suggested predistortion strategy compared to existing state of the art solutions. In the second part of the thesis, the focus is shifted towards investigating the exploitation of novel resources by looking at the use of optical frequencies for ground-to-space feeder links. The topic is introduced by a survey of existing benefits and limitations of free space optical communications. Subsequently, the implications of employing optical frequencies in long distance ground-to-space feeder links with transparent satellites are addressed. Furthermore, a powerful and flexible simulation tool was developed and exploited during the course of this thesis to model and assess the Physical (PHY) layer performance of hybrid optical/Radio Frequencies (RF) satellite networks. This tool is presented together with the scenarios and results obtained as part of the project ONSET (Optical Feeder Links Study for Satellite Networks - ESA Contract No. 40000113462/15/NL/NDe). Finally, the thesis investigates a scenario that combines the transmit processing techniques analyzed in the first part and the context of optical feeder links evaluated in the second part. A hybrid optical/RF system is considered with an electrical predistorter in place to counteract the impairments induced by the combined effects of electrical and optical non-linearities encountered along the end-to-end chain. The developed mathematical framework is exploited to jointly optimize the predistortion coefficients and the working point for the electro-optical modulator. The performance results obtained after the optimization procedure demonstrate the efficacy of the proposed approach for hybrid optical/RF systems with analog modulations. [less ▲]

Privacy-preserving Recommender Systems Facilitated By The Machine Learning Approach

Doctoral thesis (2018)

Recommender systems, which play a critical role in e-business services, are closely linked to our daily life. For example, companies such as Youtube and Amazon are always trying to secure their profit by ... [more ▼]

Recommender systems, which play a critical role in e-business services, are closely linked to our daily life. For example, companies such as Youtube and Amazon are always trying to secure their profit by estimating personalized user preferences and recommending the most relevant items (e.g., products, news, etc.) to each user from a large number of candidates. State-of-the-art recommender systems are often built on top of collaborative filtering techniques, of which the accuracy performance relies on precisely modeling user-item interactions by analyzing massive user historical data, such as browsing history, purchasing records, locations and so on. Generally, more data can lead to more accurate estimations and more commercial strategies, as such, service providers have incentives to collect and use more user data. On the one hand, recommender systems bring more income to service providers and more convenience to users; on the other hand, the user data can be abused, arising immediate privacy risks to the public. Therefore, how to preserve privacy while enjoying recommendation services becomes an increasingly important topic to both the research community and commercial practitioners. The privacy concerns can be disparate when constructing recommender systems or providing recommendation services under different scenarios. One scenario is that, a service provider wishes to protect its data privacy from the inference attack, a technique aims to infer more information (e.g., whether a record is in or not) about a database, by analyzing statistical outputs; the other scenario is that, multiple users agree to jointly perform a recommendation task, but none of them is willing to share their private data with any other users. Security primitives, such as homomorphic encryption, secure multiparty computation, and differential privacy, are immediate candidates to address privacy concerns. A typical approach to build efficient and accurate privacy-preserving solutions is to improve the security primitives, and then apply them to existing recommendation algorithms. However, this approach often yields a solution far from the satisfactory-of-practice, as most users have a low tolerance to the latency-increase or accuracy-drop, regarding recommendation services. The PhD program explores machine learning aided approaches to build efficient privacy-preserving solutions for recommender systems. The results of each proposed solution demonstrate that machine learning can be a strong assistant for privacy-preserving, rather than only a troublemaker. [less ▲]

Wine as an Investment

Doctoral thesis (2018)

During the last two decades, the wine auction market experienced non-monotonic dynamics and provided abnormal returns. When fine wine prices started to rise in the mid-1980s, wine investing transcended ... [more ▼]

During the last two decades, the wine auction market experienced non-monotonic dynamics and provided abnormal returns. When fine wine prices started to rise in the mid-1980s, wine investing transcended from a pastime into a serious investment transforming wine into a widespread investment activity. As an alternative asset, fine wine attracts increased attention among individual and institutional investors in recent years, particularly during the financial crisis due to its diversification potential. Economists also began evaluating wine as a new alternative asset class. In this thesis, we review the wine auction markets, study the price dynamics, and answer some fundamental questions. To build solid conclusions, we developed the largest French wine auction database encompassing the last 20 years. We summary our main contributions as follows. First, we review and explain the growth in recent global wine auction markets. Second, we construct price indices with hedonic regression models to observe market movements. Third, we investigate wine investment’s diversification potential. Wine in an optimal portfolio can improve the risk-return characteristics; however, the augmentation depends significantly on the market segmentation to which the investor applies it. Fourth, we analyze the wine price bubbles and collapses detection using a newly developed econometric approach. We elucidate strong evidence of two bubbles in the Bordeaux and Burgundy wine auction markets, whereas Rhône wine price behaved in a similar, but less significant, trend as Bordeaux and Burgundy wine markets. Finally, we examine the price determinants with a particular focus on the expert effect on this experienced good. We illuminate expert influence remains economically and statistically significant throughout the sample period. Using event study methodology, we disentangle the expert effect from other price variations and assert the market significantly reflects expert’s big re-ratings in the short term, yet the effect diminishes over time. However, this re-rating effect holds insignificant for modest changes. [less ▲]

Transatlantic Iron Corpornations: The Expansion of Luxembourg's Steel Industry to Brazil and the Emergence of Industry-Related Social Welfare in Minas Gerais, ca. 1910-1965

Doctoral thesis (2018)

Bildungswerte und Schulentfremdung: Institutions- und Kompositionseffekte in den Bildungskontexten Luxemburgs und der Schweiz

Doctoral thesis (2018)

Values and attitudes towards schooling – as the core concepts of this research – are increasingly recognized as important factors affecting educational achievement and attainment. Values of Education (VoE ... [more ▼]

Values and attitudes towards schooling – as the core concepts of this research – are increasingly recognized as important factors affecting educational achievement and attainment. Values of Education (VoE) are conceptualised along the five instrumental goals outlined in the social production function theory by Lindenberg (1991; Ormel et al., 1999). School alienation (SAL) is defined as negative attitudes towards academic domains of schooling, namely teachers and learning (Hascher & Hadjar, 2018: 179). Based on the assumption that SAL depicts a process intensified over the course of secondary education (Finn, 1989), this dissertation finds evidence for developmental trends between grade seven and grade eight comparatively across country settings and to show how educational contexts and the perceived VoE affect SAL. This sociological study provides an in-depth comparison of the stratified school systems of Luxembourg and of the Canton of Berne (Switzerland) based upon newly-collected panel data of the international research project School Alienation in Switzerland and Luxembourg (SASAL) (N = 465/508). Following the distinction of primary and secondary effects of social origin by Boudon (1974), these core concepts are discussed in the frames of Bourdieu’s (1982 [1979], 1992) habitus theory, emphasizing the transmission of cultural capital in families, and of rational choice approaches (e.g. Esser, 1999). Moreover, theoretical approaches on disparities structured by gender (e.g. Breen et al., 2010) and migration background (Kristen & Dollmann, 2010) as well as further axes of educational inequalities are considered to explain found differences in students’ educational values and attitudes towards schooling. The validation of the measurement instrument of VoE by means of factor analysis indicates four dimensions of VoE among school students in these contexts: stimulation as an intrinsic value, comfort and status related to standards of living and future career goals, behavioural confirmation in terms of expectations of significant others, and the social goal affection. Structural equation models demonstrate that the lower value of stimulation through education among boys mediates their higher level of SAL across country contexts. Yet, a higher value of comfort/status among students increases the development of negative attitudes. Whereas immigrant students’ higher behavioural confirmation in the Canton of Bern backs the immigrant optimism thesis (Kao & Tienda, 1995), immigrant students in Luxembourg reveal a general lower VoE and are more alienated from teachers. Contextual effects estimated in multilevel models explain the higher prevalence of alienation from learning in Luxembourgish classrooms. Within the stratified and segregated secondary schooling, students in the academic track are more alienated compared to students in technical secondary education. This result contradicts the differentiation–polarization theory (Van Houtte, 2006) in the context of Luxembourg. On the other hand, in Berne, alienation from learning does not differ between school tracks, but is overall lower in the less segregated, more permeable schools. Classroom composition effects, however, show no clear pattern. In line with prior research, alienation from learning is lower in Luxembourgish classrooms with a higher percentage of immigrant students. With regard to the consequences of SAL, the results show a negative impact of alienation from learning on school achievement in both country settings. Deriving implications, the findings provide some arguments in favour of comprehensive school models. [less ▲]

The Significance of the Place of Performance in Commercial Contracts under the European Union Choice of Law Rules

Doctoral thesis (2018)

The central theme of this thesis is that the place of performance is of considerable significance as a connecting factor in international commercial contracts. This thesis challenges and questions the ... [more ▼]

The central theme of this thesis is that the place of performance is of considerable significance as a connecting factor in international commercial contracts. This thesis challenges and questions the approach of the European legislator, which does not explicitly give the place of performance special significance in the determination of the applicable law in the absence of choice for commercial contracts. This thesis proposes that the place of performance should be explicitly given special significance under a revised Article 4 of Rome I Regulation. Second, it is argued that the absolute significance given to the place of performance in determining foreign country overriding mandatory rules is a good reason why the place of performance should be explicitly given special significance under a revised Article 4 of Rome I Regulation. Third, inspired by the coherence between matters of European Union jurisdiction and choice of law in civil and commercial matters, it is argued that the place of performance which is given special significance under the European Union rules on the allocation of jurisdiction for commercial contracts is a good reason why the place of performance should be explicitly given special significance under a revised Article 4 of Rome I Regulation. This thesis then concludes by proposing a model revised Article 4 of Rome I Regulation that could be used as an international solution by legislators, judges, arbitrators, and other decision makers who wish to reform their choice of law rules in determining the applicable law in the absence of choice for international commercial contracts. [less ▲]

Impact of floating bodies on buildings and structures during flooding

Doctoral thesis (2018)

Flood is one of the most serious natural disasters that affect human beings, so how to effectively reduce flood damage to human beings is of vital im- portance. One of the keys to reducing flood damage is ... [more ▼]

Flood is one of the most serious natural disasters that affect human beings, so how to effectively reduce flood damage to human beings is of vital im- portance. One of the keys to reducing flood damage is to design buildings effectively enough to withstand flooding and the impact of floating debris on the structures. Although, many studies exist to address the impact of floods on structures, the impact of floating debris on the buildings and structures, i.e. wall or bridge during flooding have not been fully addressed yet. Thus, the objec- tive of this dissertation is to predict the trajectory of floating debris of rivers during flooding and analyze its impact on the structures. For achieving this goal, a numerical tool based on the mesh-less method of Smoothed Particle Hydrodynamics (SPH), Discrete Element Method (DEM) and Finite Element Method (FEM) is proposed in this dissertation. Where SPH is employed to describe the fluid flow and DEM is employed to ob- tain the contact force between the floating debris and structures. And a coupling model of SPH and DEM is presented and implemented based on the OpenFPM, a scalable and open C++ framework for particles and mesh simulation in parallel. Buildings and structures are represented by Finite Element Method (FEM) mesh, for which impact with floating debris is de- termined. These contacts of floating debris cause forces at the positions of impact, e.g. mechanical load and are evaluated by using commercial Finite Element Analysis (FEA) software Abaqus. As a result, a numerical tool combing the SPH-DEM and FEA is presented in this dissertation It is worth to notice, that treating the inlet/outlet con- dition in SPH is a challenging issue due to its Lagrangian nature. A suitable boundary treatment for the inlet / outlet condition in SPH for river flooding problem in 3D is unavailable in literatures. Thus, this dissertation extended the open boundary treatment for SPH using semi-analytical conditions and Riemann solver in 2D (Ferrand et al., 2017) to 3D. Which in results, a new open boundary treatment that is suitable for describing the inlet/outlet condition of SPH in 3D is presented and applied to describe the inlet/outlet condition in this dissertation. The numerical tool is applied to study the scenario of floating trees, trans- porting in the Mosel river and hitting the flood control wall at Kesten town in the west Germany during flooding. As the result of simulation shows, the floating trees are driven by the river and heading to the downstream and eventually collide with the flood control wall. This impact causes the flood control wall crack from the position of impact. Which means that the flood control wall is not capable of standing the impact of floating trees that transported in the river. [less ▲]

Andreï Makine et la cognition humaine. Pour une transbiographie

Doctoral thesis (2018)

This dissertation proposes a systematic analysis of Andreï Makine’s oeuvre. We read his prose through the prism of cognitive literary studies, a recent theoretical and methodological field which explores ... [more ▼]

This dissertation proposes a systematic analysis of Andreï Makine’s oeuvre. We read his prose through the prism of cognitive literary studies, a recent theoretical and methodological field which explores the interaction between literary interpretation on the one hand, and the human brain and mind on the other. We focus on the depiction of the affect, the imagination and the limits of cognition, while pinpointing, at the same time, the narrative techniques and the stylistic devices that contribute to create a work whose goal is not only to illustrate reality, but also to transfigure it. Thus, we analyse Makine’s novels from a dynamic perspective, asking what impact they could have on the reader, and proposing an innovative hypothesis concerning the relation between the author's biography and his literary output. According to this hypothesis, the writer’s work is not autobiographical (according to Philippe Lejeune’s definition of the concept of autobiography) nor autofictional (Vincent Colonna), and it requires the coining of a new concept able to define it. We call this concept – which consists of the conscious and recurrent recreation of a meaningful biographical event through fiction – a “transbiography”. [less ▲]

Normative Policy Coherence for Development in EU External Policies: A Case Study of the European Union's Development and Trade Policies towards Vietnam

Doctoral thesis (2018)

The global discourse on people-centered development appeals for a normative dimension in donor policies. As a major donor organization, the European Union (EU) presents itself as a normative actor on the ... [more ▼]

The global discourse on people-centered development appeals for a normative dimension in donor policies. As a major donor organization, the European Union (EU) presents itself as a normative actor on the global stage. However, it is often criticized for lacking normative practice. This dissertation addresses this criticism and assesses the EU’s normative policy coherence for development by examining norm implementation across development and trade policies. The guiding research questions are the following: Are the EU’s development and trade policies coherent in implementing norms; and if not, why are they incoherent? Normative policy coherence for development is defined as the coherent implementation of EU norms (democracy, freedom, gender equality, good governance, human rights, justice, liberty, non-discrimination, peace, rule of law, solidarity and sustainability) across development and non-development policies. A case study of EU development and trade policies addressing Vietnam is used to illustrate normative policy coherence for development in the transition phase from an EU-Vietnam donor-recipient relationship to a mutual trade relationship. This research contributes to existing literature on policy coherence for development, public policy, normative power Europe and regionalism through the in-depth analysis of normativity in EU policy implementation. It examines EU normative power in the EU-Vietnam relationship with particular focus on normative policy coherence and places this relationship in the context of EU-ASEAN relations. A qualitative methodology is utilized in this dissertation is supported by the case study design within which the congruence method has been used for the analysis. The data set is comprised of European Union policy documents and semi-structured interviews conducted by the author in Brussels, Belgium, and Hanoi and Ho Chi Minh City, Vietnam, which were coded and analyzed in Atlas.ti. The results show that normative policy coherence for development is undermined for several reasons. First, in policy implementation, norms are seen as a political matter and not as a development or trade matter. In contrast to policy guidelines, which are infused by normative commitments such as respect for human rights and fundamental freedoms, subsequent implementation stages do not correspond to this commitment. Second, policy networks, which could function as an opportunity for cooperation and coherence, are split ii by sector, which reinforces the divide between political, developmental and economic matters and in doing so they undermine normative policy coherence. Third, the EU’s relations with ASEAN do not directly undermine EU-Vietnam relations and, therefore, normative coherence in policies addressed at Vietnam is only indirectly affected by EU interests in ASEAN. Causes of normative incoherence in EU policy implementation can be linked to the institutional divide between political and technical matters, which are reinforced by sectoral divisions in the delegations abroad. [less ▲]

A Dual-Grid Multiscale Approach to CFD-DEM Couplings for Multiphase Flow

Doctoral thesis (2018)

This thesis focuses on a novel dual-grid multiscale approach to CFD- DEM1 couplings, proposes its advantages in terms of numerical proper- ties and performance, and provides examples of engineering ... [more ▼]

This thesis focuses on a novel dual-grid multiscale approach to CFD- DEM1 couplings, proposes its advantages in terms of numerical proper- ties and performance, and provides examples of engineering applications that can benefit from it. In recent years, CFD-DEM couplings are be- coming a more and more adopted solution for the numerical simulation of particle-laden flows. In particular, couplings based on the volume av- eraging technique have become a standard for numerical simulations in chemical and process engineering. Furthermore, they are rapidly spread- ing to civil, geotechnical and mechanical applications due to their ability in dealing with arbitrarily complex mixtures of continuum and granular media. Despite the several advantages that these Eulerian-Lagrangian cou- plings provide, their rigorous application to complex scenarios is currently limited by two main factors. First, the computational traceability of the solutions can become problematic due to the lack of a general theory on the subject. In particular, grid-convergence studies for the solution of the continuous phases are often not feasible due to the averaging procedure that imposes limitations on the grid structure and refinement. Second, the parallel implementation of these numerical schemes holds important disadvantages in terms of memory consumption and inter-physics com- munication load. These disadvantages are significantly limiting the ex- tension of these approaches to large-scale scenarios. This thesis collects some of the most significant works published in the last years on a novel approach that allows solving the two above- mentioned problems, and, therefore, tackling more complex and expen- sive scenarios. I refer to this approach as dual-grid multiscale approach for CFD-DEM couplings. It consists in using two different computational grids, one for the coupling between continuum and discrete entities and one for the solution of the so-obtained continuum equations. The two grids, i.e. the two problems, are in this way resolved on two different scales. The first scale or “bulk” scale is chosen to optimize the averag- ing operation. At this length-scale, the discrete entities are considered as zero-dimensional, and interact with the fluid with local exchanges of momentum, mass, and energy. The second scale or “fluid-fine” scale is identified as the one at which a unique solution for the averaged equa- tions can be provided. In practice, this is chosen as the one at which the solution of the fluid equations becomes grid-independent. An inter-scale communication is adopted by interpolating fields from the fluid-fine scale to the bulk one and vice-versa. The theoretical description of the method is first provided with par- ticular reference to the DEM-VOF coupling. Even in its simplest version, the multiscale approach is shown to generate grid-convergent solutions and significantly higher accuracy than a standard CFD-DEM coupling. This shows how the new approach is able to overcome the first main limitation described above. Then, an optimized parallel implementation of the method is pro- posed to show how this multiscale approach can provide significant ben- efits also for what concerns the execution time. Technically, this is made possible by moving the communication cost of the coupling from the inter-physics communication that characterized the standard CFD-DEM couplings to an optimized inter-scale communication routine. This en- ables the method to overcome a major bottleneck of the parallel execution of CFD-DEM couplings and therefore the second main limitation of those schemes. Finally, the dual-grid multiscale method is applied to approach in- dustrially relevant problems that were till now out-of-reach for standard CFD-DEM couplings, proving how this technique can have direct real- case application and produce immediate benefits for practitioners willing to adopt it. [less ▲]

IDENTIFYING PHOSPHO-PROTEOMIC PATTERNS INDICATIVE OF RESPONSIVENESS TO TARGETED THERAPY IN MELANOMA

Doctoral thesis (2018)

The New Generation of Bilateral Free Trade Agreements - A New Legal Instrument of the Union’s External Action

Doctoral thesis (2018)

The NGFTAs are considered as new legal instruments of the EU external action as they refer to a new generation of free trade agreements that go further in integration, beyond the simple elimination of ... [more ▼]

The NGFTAs are considered as new legal instruments of the EU external action as they refer to a new generation of free trade agreements that go further in integration, beyond the simple elimination of import tariffs and other trade barriers while also addressing non-trade related measures. The research examines the significance and the implication of the NGFTAs as a new legal instrument by more closely considering the limits of the attributed competences and how the reformed ISDS could affect the autonomy of the EU. Analysing these instruments has shown the need to establish a clear balance between the protection of the autonomous legal order, and at the same time maintaining the EU’s objective of trade liberalization. The dispute settlement mechanism and its relation to the EU legal order and international courts and tribunals have become of particular importance. This is due to the remaining possibility that the ICS may interfere with the EU’s exclusive competence to preserve the system of vertical allocation of competence. The division of responsibility between the EU and its Member States seems to be the key to preserve the autonomy of the EU legal order, in relation to the issues of competence. An appropriate balance may be seen through further emphasizing the duty of sincere cooperation, in particular in relation to the ICS. Moreover, the division of responsibility plays a significant role between the EU and its Member States and seems to be the key role to preserve the autonomy of the EU legal order. The anticipated Opinion 1/17, which provide for further guidance will have a decisive impact on the NGFTAs, concerning the future compliance with EU law in relation to both compatibility and design. [less ▲]

Model and parameter identification through Bayesian inference in solid mechanics

Doctoral thesis (2018)

Predicting the behaviour of various engineering systems is commonly performed using mathematical models. These mathematical models include application-specific parameters that must be identified from ... [more ▼]

Predicting the behaviour of various engineering systems is commonly performed using mathematical models. These mathematical models include application-specific parameters that must be identified from measured data. The identification of model parameters usually comes with uncertainties due to model simplifications and errors in the experimental measurements. Quantifying these uncertainties can effectively improve the predictions as well as the performance of the engineering systems. Bayesian inference provides a probabilistic framework for quantifying these uncertainties in parameter identification problems. In a Bayesian framework, the user's initial knowledge, which is represented by a probability distribution, is updated by measurement data through Bayes' theorem. In the first two chapters of this thesis, Bayesian inference is developed for the identification of material parameters in elastoplasticity and viscoelasticity. The effect of the user's prior knowledge is systematically studied with respect to the number of measurements available. In addition, the influence of different types of experiments on the uncertainty is studied. Since all mathematical models are simplifications of reality, uncertainties of the model itself may also be incorporated. The third chapter of this thesis presents a Bayesian framework for parameter identification in elastoplasticity in which not only the uncertainty of the experimental output is included (i.e. stress measurements), but also the uncertainty of the model and the uncertainty of the experimental input (i.e. strain). Three different formulations for describing the model uncertainty are considered: (1) a random variable which is taken from a normal distribution with constant parameters, (2) a random variable which is taken from a normal distribution with an input-dependent mean, and (3) a Gaussian random process with a stationary covariance function. In the fourth chapter of this thesis, a Bayesian scheme is proposed to identify material parameter distributions, instead of material parameters. The application in this chapter are random fibre networks, in which the set of material parameters of each fibre is assumed to be a realisation from a material parameter distribution. The fibres behave either elastoplastically or in a perfectly brittle manner. The goal of the identification scheme is to avoid the experimentally demanding task of testing hundreds of constituents. Instead, only 20 fibres are considered. In addition to their material randomness, the macroscale behaviours of these fibre networks are also governed by their geometrical randomness. Another question aimed to be answered in this chapter is therefore is `how precise the material randomness needs to be identified, if the geometrical randomness will also influence the macroscale behaviour of these discrete networks'. [less ▲]

Engineering Smart Software Services for Intelligent Pervasive Systems

Doctoral thesis (2018)

Pervasive computing systems, envisioned as systems that blend with the physical environment to enhance the quality of life of its users, are rapidly becoming a not so distant reality. However, many ... [more ▼]

Pervasive computing systems, envisioned as systems that blend with the physical environment to enhance the quality of life of its users, are rapidly becoming a not so distant reality. However, many challenges must be addressed before realizing the goal of having such computing systems as part of our everyday life. One such challenge is related to the problem of how to develop in a systematic way the software that lies behind pervasive systems, operating them and allowing them to intelligently adapt both to users' changing needs and to variations in the environment. In spite of the important strides done in recent years concerning the engineering of software that places the actual, immediate needs and preferences of users in the center of attention, to the best of our knowledge no work has been devoted to the study of the engineering process for building software for pervasive systems. In this dissertation we focus on the engineering process to build smart software services for pervasive systems. Specifically, we first introduce as our first major contribution a model for the systematic construction of software for pervasive systems, which has been derived using analytical, evidence-based, and empirical methodologies. Then, on the basis of the proposed model, we investigate two essential mechanisms that provide support for the engineering of value-added software services for smart environments, namely the learning of users' daily routines and the continuous identification of users. For the case of learning users' daily routines, we propose what is our second main contribution: a novel approach that discovers periodic-frequent routines in event data from sensors and smart devices deployed at home. For the continuous identification of users we propose what is our third major contribution: a novel approach based on behavioral biometrics which is able to recognize identities without requiring any specific gesture, action, or activity from the users. The two approaches proposed have been extensively evaluated through studies in the lab, based on synthetic data, and in the wild, showing that they can be effectively applied to different scenarios and environments. In sum, the engineering model proposed in this dissertation is expected to serve as a basis to further the research and development efforts in key aspects that are necessary to build value-added smart software services that bring pervasive systems closer to the way they have been envisioned. Furthermore, the approaches proposed for learning users' daily routines and recognizing users' identities in smart environments are aimed at contributing to the investigation and development of the data analytics technology necessary for the smart adaptation and evolution of the software in pervasive systems to users' needs. [less ▲]

Standardisierte unternehmensübergreifende Wertstrommethode (StreaM)

Doctoral thesis (2018)

In the course of globalization, complex corporate networks arise in which diverse players are involved in the value-added process. Particularly at the interfaces of the value chain, there are challenges ... [more ▼]

In the course of globalization, complex corporate networks arise in which diverse players are involved in the value-added process. Particularly at the interfaces of the value chain, there are challenges in terms of communication and cooperation, since so far no uniform procedure for the visualization, analysis and continuous improvement of product and information flows is used. These difficulties occur both within organizations and especially across company boundaries. In particular, no internationally recognized value stream standard exists at present, which is inter alia a result of a low cooperativeness of organizations due to a lack of trust, inadequate knowledge and insufficient incentives. The inconsistent use of Value Stream Management (VSM) affects many economic sectors worldwide. These inconsistent VSM approaches lead to inefficiencies, such as rework and coordination difficulties in the case of value stream audits, which represent an avoidable waste of time, natural and financial resources. In the scientific literature, a large number of fundamental VSM approaches, modifications and further developments are available that serve as a basis for the present work. The existing VSM approaches include provisions, e.g. in terms of symbols, data boxes, associated process variables and their calculation, which are each extensive, diverse and in some cases process-specific. In contrast, complex, globally distributed value chain structures require a holistic approach for the modeling of value streams. In the context of this dissertation, a VSM draft standard will be generated by means of a comparison of existing VSM approaches. Based on four different value stream levels, a multi-stage approach for the visualization, analysis and continuous improvement of cross-company product and information flows will be developed. The present thesis thus provides the methodological basis on the way towards an internationally recognized VSM standard and demonstrates in addition the potential of efficient and targeted application of VSM in value networks. On the one hand, standardizing the VSM method will enable an improved communication and cooperation along value chains in different economic sectors. On the other hand, the holistic approach helps to identify, show and implement improvement measures across company borders and ultimately leads to a reduction or ideally to the elimination of waste from an end customer perspective. The developed approach allows organizations worldwide to assess internal as well as cross-company value streams in a structured manner, to design them flexibly and to implement them effectively in practice. [less ▲]

A decision support system for energy saving in Waste Water Treatment Plants

Doctoral thesis (2018)

Waste Water Treatment Plants (WWTPs) are complex facilities, in which an efficient energy management can produce relevant benefits for the environment and the economy. Today, big data can be used for a ... [more ▼]

Waste Water Treatment Plants (WWTPs) are complex facilities, in which an efficient energy management can produce relevant benefits for the environment and the economy. Today, big data can be used for a more efficient plant management, enabling high-frequency assessment and ultimately a more efficient use of resources. In order to achieve this, a computer-based support is necessary to analyse the enormous amount of data that WWTP sensors can produce. When this PhD project started, the literature review showed that, in the WWTP domain, the few available decision support systems (DSSs) were promising but still with large room for improvements; in fact, these tools were plant-specific, focussed mainly on process parameters and (most of them) working with low-frequency aggregated data (yearly data). This thesis instead proposes a cooperative decision support system called Shared Knowledge Decision Support System (SK-DSS). SK-DSS is plant generic, i.e. able to simultaneously work with many WWTPs and based on key performance indicators. SK-DSS analyses the processes occurring in the plants and provide case-based solutions. Moreover, this DSS provides a platform to enable the plant managers to exchange information and cooperate. This thesis proposes the model of SK-DSS, a web-application, and applications to improve the energy performance of pump, blowers and biogas. [less ▲]

Advanced Symbol-level Precoding Schemes for Interference Exploitation in Multi-antenna Multi-user Wireless Communications

Doctoral thesis (2018)

The utilization of multi-antenna transmitters relying on full frequency reuse has proven to be an effective strategy towards fulfilling the constantly increasing throughput requirements of wireless ... [more ▼]

The utilization of multi-antenna transmitters relying on full frequency reuse has proven to be an effective strategy towards fulfilling the constantly increasing throughput requirements of wireless communication systems. As a consequence, in the last two decades precoding has been a prolific research area, due to its ability to handle the interference arising among simultaneous transmissions addressed to different co-channel users. The conventional precoding strategies aim at mitigating the multi-user interference (MUI) by exploiting the knowledge of the channel state information (CSI). More recently, novel approaches have been proposed where the aim is not to eliminate the interference, but rather to control it so as to achieve a constructive interference effect at each receiver. In these schemes, referred to as symbol-level precoding (SLP), the data information (data symbols) is used together with the CSI in the precoding design, which can be addressed following several optimization strategies. In the context of SLP, the work carried out in this thesis is mainly focused on developing more advanced optimization strategies suitable to non-linear systems, where the per-antenna high-power amplifiers introduce an amplitude and phase distortion on the transmitted signals. More specifically, the main objective is to exploit the potential of SLP not only to achieve the constructive interference at the receivers, but also to control the per-antenna instantaneous transmit power, improving the power dynamics of the transmitted waveforms. In fact, a reduction of the power variation of the signals, both in the spatial dimension (across the different antennas) and in the temporal dimension, is particularly important for mitigating the non-linear effects. After a detailed review of the state of the art of SLP, the first part of the thesis is focused on improving the power dynamics of the transmitted signals in the spatial dimension, by reducing the instantaneous power imbalances across the different antennas. First, a SLP per-antenna power minimization scheme is presented, followed by a related max-min fair formulation with per-antenna power constraints. These approaches allow to reduce the power peaks of the signals across the antennas. Next, more advanced SLP schemes are formulated and solved, with the objective of further improving the spatial dynamics of the signals. Specifically, a first approach performs a peak power minimization under a lower bound constraint on the per-antenna transmit power, while a second strategy minimizes the spatial peak-to-average power ratio. The second part of this thesis is devoted to developing a novel SLP method, referred to as spatio-temporal SLP, where the temporal variation of the transmit power is also considered in the SLP optimization. This new model allows to minimize the peak-to-average power ratio of the transmitted waveforms both in the spatial and in the temporal dimensions, thus further improving the robustness of the signals to non-linear effects. Then, this thesis takes one step further, by exploiting the developed spatio-temporal SLP model in a different context. In particular, a spatio-temporal SLP scheme is proposed which enables faster-than-Nyquist (FTN) signaling over multi-user systems, by constructively handling at the transmitter side not only the MUI but also the inter-symbol interference (ISI). This strategy allows to benefit from the increased throughput provided by FTN signaling without imposing additional complexity at the user terminals. Extensive numerical results are presented throughout the thesis, in order to assess the performance of the proposed schemes with respect to the state of the art in SLP. The thesis concludes summarizing the main research findings and identifying the open problems, which will constitute the basis for the future work. [less ▲]

Disambiguation of Researcher Careers: Shifting the Perspective from Documents to Authors

Doctoral thesis (2018)

The thesis describes an algorithm that disambiguates the namespaces of inventors and researchers, spawned by their patents and publications, into career paths. A probabilistic theory to assess the risk of ... [more ▼]

The thesis describes an algorithm that disambiguates the namespaces of inventors and researchers, spawned by their patents and publications, into career paths. A probabilistic theory to assess the risk of erroneously linking documents of namesakes, different individuals with a mutual name, into one career bypasses the need for training datasets, thereby avoiding a namesake bias caused by the inherent underestimation of namesakes in training/benchmark data. The economic relevance of identified careers is illustrated by two applications. The first one outlines the impact of inter-regional inventor mobility in Italy on the total factor productivity of the sending and receiving regions. We show that an inflow of high skilled labor has a significant positive effect on TFP, while outflow decreases it. We further separate mobility in firm-internal relocation and job switches to find a more pronounced effect for the latter mobility. The second application observes the reaction of German university researchers to an exogenous change in federal law pertaining the property rights of their inventions equivalent to the Bayh Dole Act. Being able to trace their careers along with the careers of an unaffected control group allows us to evaluate the efficacy of technology transfer offices replacing the former informal activities of the university professors in regard of academic entrepreneurship. We find that an overall decrease of university patenting neutralizes any institutionalized efforts of spurring entrepreneurship at the expense of informal faculty-firm networks as channels for knowledge transfer. [less ▲]

Essays on M&As and Innovation

Doctoral thesis (2018)