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See detailSocial stratification in higher education trajectories: A sequence-analytical approach
Haas, Christina UL

Scientific Conference (2019, September 13)

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See detailL'imaginaire de la logique contractuelle : subversion, reconnaissance, résonance - autour de l'arrêt Churchill Falls
Bélanger, André; Saint-Onge, Simon; Dufour, Pascale UL et al

Presentation (2019, September 13)

Les trois conférencier(ière)s, avec la collaboration de Jean-Guy Belley, se proposent d’investir le contrat, instrument juridique qui se donne à penser comme un pharmakon, c’est-à-dire comme un bouc ... [more ▼]

Les trois conférencier(ière)s, avec la collaboration de Jean-Guy Belley, se proposent d’investir le contrat, instrument juridique qui se donne à penser comme un pharmakon, c’est-à-dire comme un bouc-émissaire à qui l’on impute un tort social en contexte néo-libéral. Envisager le contrat comme un pharmakon, c’est, certes, percevoir en lui l’expression d’un oubli de la relation de droit comme relation sociale, mais aussi le potentiel d’une solution à ce même problème. À partir de l’arrêt de la Cour suprême Churchill Falls et à travers le spectre de la Théorie critique (la subversion chez Theodor W. Adorno, la reconnaissance chez Axel Honneth et la résonance chez Hartmut Rosa), l’imaginaire du contrat déploie ces deux facettes que sont celles d’être le poison et le remède au déficit relationnel du lien juridique. [less ▲]

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See detailPhysical activity of children and adolescents in Luxembourg during school, physical education and leisure time: An accelerometry-based study
Eckelt, Melanie UL; Bund, Andreas UL; Hutmacher, Djenna UL et al

Poster (2019, September 13)

Objectives: Due to its great importance for development and health, the physical activity (PA) of children has become a key issue in research over the last decade. Simultaneously, the measurement of PA ... [more ▼]

Objectives: Due to its great importance for development and health, the physical activity (PA) of children has become a key issue in research over the last decade. Simultaneously, the measurement of PA has been strongly improved through the development of user-friendly and reliably working accelerometer, which allow to track PA over several consecutive days in an objective way. Although the benefits of accelerometry are well documented also for children (e.g. Hager et al., 2015), especially cross-national studies such as the Health Behaviour in School-aged Children (HBSC) are still using questionnaires and are focused only on overall or leisure time PA. This study as part of the PALUX project (Physical Activity of Children and Youth in Luxembourg) aims to (1) measure children's daily PA patterns using up-to-date accelerometers while (2) differentiating between PA in school, physical education and leisure time. Methods: In total, 242 children and adolescents (134 girls and 108 boys) aged from 10-18 years from 9 different schools in Luxembourg wore the ActiGraph GT3X-BT- accelerometer at the hip for a period of seven consecutive days. Total time in moderate-to-vigorous PA (MVPA) was calculated using the cut-of points from Evenson et al. (2008). Time spent in school and physical education were determined based on timetables provided by the schools. Results: Mean overall MVPA of participants over seven consecutive days was 307.6 min, with 98.4 min (32 %) during school time and 190.7 min (62 %) during leisure time. Only 16.7 min (6 %) of the school time MVPA were performed in physical education. Boys had more overall MVPA than girls (367.9 vs. 258.9 min, t(240) = 6.76, p < .01) due to significant differences in all areas considered here (schooltime: t(215) = 6.26, p < .01; leisure time: t(215) = 6.18, p < .01; physical education: t(188) = 3.07, p < .01). Children spent 25.6 min of an average physical education class of 77 min in MVPA, which is 19.71 % and thus much less than the 50 % recommended by the U.S. Department for Health and Human Sciences. Only 0.5% of the participants (1.2% of the boys and 0% of the girls) achieved this value. Discussion: Overall, 25.6 % of the children and adolescents in Luxembourg met WHO's PA guideline of at least 60 min MVPA per day, which is in line with results from other European countries. According to our data, the achieved MVPA is mainly due to leisure time activities, whereas the potential of school and physical education in providing and promoting PA has apparently not been fully exploited yet. The consistency of these findings will be examined in a second survey in 2019 [less ▲]

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See detailDifferences in physical activity among children with physically active and inactive parents
Eckelt, Melanie UL; Hutmacher, Djenna UL; Steffgen, Georges UL et al

Scientific Conference (2019, September 13)

Objectives: Parental physical activity is considered as positively related to children´s physical activity (PA; Sallis, Prochaska & Taylor, 2000). Since parents serve as role models, have the potential to ... [more ▼]

Objectives: Parental physical activity is considered as positively related to children´s physical activity (PA; Sallis, Prochaska & Taylor, 2000). Since parents serve as role models, have the potential to influence the health-related behavior and, for instance, to alter a mainly sedentary lifestyle of their children (Beets, Cardinal & Alderman, 2010), the impact of parental PA has become a key issue in research. Many studies report associations between parental PA and the PA behavior of their children, e.g., the direct involvement of the parents in activities with their children is related to increased levels of their PA (Adkins, Sherwood, Story, & Davis, 2004; Beets, Vogel, Chapman, Pitetti, & Cardinal, 2007). However, the mechanisms of parental influence are still poorly understood and besides recent studies are based on self-reported data. Therefore, this study aims to examine if parental PA is related to the subjectively and objectively measured PA of their children. Methods: 237 Luxembourgish children and adolescents (134 girls and 103 boys) aged from 10-18 years participated in the study. Via a digital questionnaire, the children indicated if their mother and father are physically active on a regular basis and if they are active together with their parents. Furthermore, the children and adolescents indicated if they are active at least 60 minutes/ day and if they own a membership in a sports club (MoMo physical activity questionnaire). Additionally, children’s PA behavior was objectively assessed by wearing an accelerometer (ActiGraph GT3X-BT) for a period of seven consecutive days. Activity was categorized as sedentary, light physical activity or moderate to vigorous physical activity (MVPA) using age-specific thresholds. Results: A multivariate ANOVA revealed significant differences in self-reported physical activity if the mother was physically active (F (2, 166) = 5.4, p < .01). Thus, children reported subjectively higher daily activity duration (p < .05) and more activities in a regular week (p < .01). There was no impact on self-reported PA if the father was active or the children were active with their parents together. Regarding the objective data, there were no significant differences between children with active parents and children with inactive parents. If the parents were active with their children together there were significant differences (F (3, 229) = 3.2, p < .05), thus MVPA per day was higher (p < .05) and the sedentary time was lower (p < .01). Neither subjective nor objective data revealed gender-specific differences. Discussion: In contrast to other studies, only the mother seems to have an influence on the subjective PA behavior of the children. The fact, that parents being active or in a sports club does not appear to enhance the PA of the children objectively. However, the objective PA is merely affected by being active together. According to this finding, joint activities of parents and children seem to be necessary to promote children’s PA effectively. It is important to note that in our study the parental PA was rated by the children. In future studies, parents should be included via self-report questionnaires and/or accelerometer. [less ▲]

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See detailBringing Digital Oral History to Luxembourg
Lambert, Douglas UL

Scientific Conference (2019, September 13)

Oral history is a field with a growing digital component and, as with other DH fields, computer-based techniques and systems have revolutionized the way we process and present content. One particular set ... [more ▼]

Oral history is a field with a growing digital component and, as with other DH fields, computer-based techniques and systems have revolutionized the way we process and present content. One particular set of activities, which I refer to as Oral History Digital Indexing (OHDI), has been important in shaping new processes and methods for organization, analysis, and curation of digital oral history. I have been directly involved with this work in the United States and am currently working in Luxembourg to explore what aspects of OHDI will be appropriate in Europe. In this presentation I will introduce the organizations, projects, and tools that have helped shape OHDI. Among these projects/products is the Oral History Metadata Synchronizer, or OHMS, which has two important modes of digital indexing for oral histories. One is a transcript synchronization tool and the second an indexing tool, both of which help create multimedia webpages that connect interviews in an audio/video media player with text representations of the content. OHMS and other tools will be highlighted briefly, while emphasizing that no two systems have exactly the same features. One unifying principle behind OHDI tools is that indexing processes, i.e., creating shorter, summarizing text tied to time points in the a/v media, can and should take priority over word-for-word transcription. The indexing concept leads to multiple options for processing, analyzing, and presenting an oral history and OHDI also provides a framework for operating under the inevitable reality that not all digital processing options are feasible to pursue. [less ▲]

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See detailFracture mechanism simulation of inhomogeneous anisotropic rocks by extended finite element method
Mohtarami, Ehsan; Baghbanan, Alireza; Hashemolhosseini, Hamid et al

in Theoretical and Applied Fracture Mechanics (2019), 104

The vast majority of rock masses is anisotropic due to factors such as layering, unequal in-situ stresses, joint sets, and discontinuities. Meanwhile, given the frequently asymmetric distribution of pores ... [more ▼]

The vast majority of rock masses is anisotropic due to factors such as layering, unequal in-situ stresses, joint sets, and discontinuities. Meanwhile, given the frequently asymmetric distribution of pores, grain sizes or different mineralogical compounds in different locations, they are often classified as inhomogeneous materials. In such materials, stress intensity factors (SIFs) at the crack tip, which control the initiation of failure, strongly depend on mechanical properties of the material near that area. On the other hand, crack propagation trajectories highly depend on the orthotropic properties of the rock mass. In this study, the SIFs are calculated by means of anisotropic crack tip enrichments and an interaction integral are developed for inhomogeneous materials with the help of the extended finite element method (XFEM). We also use the T-stress within the crack tip fields to develop a new criterion to estimate the crack initiation angles and propagation in rock masses. To verify and validate the proposed approach, the results are compared with experimental test results and those reported in the literature. It is found that the ratio of elastic moduli, shear stiffnesses, and material orientation angles have a significant impact on the SIFs. However, the rate of change in material properties is found to have a moderate effect on these factors and a more pronounced effect on the failure force. The results highlight the potential of the proposed formulation in the estimation of SIFs and crack propagation paths in inhomogeneous anisotropic materials. [less ▲]

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See detailDISSECTING GENETIC EPISTASIS IN FAMILIAL PARKINSON’S DISEASE USING A DIGENIC PATIENT-DERIVED STEM CELL MODEL
Hanss, Zoé UL

Doctoral thesis (2019)

Parkinson’s disease (PD) is the second most common neurodegenerative disorder worldwide. 10% of PD patients present a familial form of the disease implicating genetic mutations. A variability in terms of ... [more ▼]

Parkinson’s disease (PD) is the second most common neurodegenerative disorder worldwide. 10% of PD patients present a familial form of the disease implicating genetic mutations. A variability in terms of disease expressivity, severity and penetrance can be observed among familial cases. The idea that the classical one-gene one-trait model may not catch the full picture of genetic contribution to PD pathophysiology is increasingly recognized. Therefore, a polygenic model where multiple genes would influence the disease risk and the phenotypic traits in PD should be investigated. Mutations in PRKN, encoding the E3 ubiquitin-protein ligase Parkin, cause young onset autosomal recessive forms of PD. A variability in terms of clinical presentation and neuropathology have been observed in PD patients carrying mutations in Parkin. On the other hand, mutations in GBA were recently recognized as the most common genetic risk factor for developing PD. The incomplete penetrance of the disease in patients with GBA mutations may implicate other genetic factors. Therefore, it can be hypothesized that the interactions between common PD genes like PRKN and GBA can contribute to the phenotypic heterogeneity observed in PD cases. To explore this hypothesis, we generated patient-derived cellular models from several PD patients carrying pathogenic mutations in either both PRKN and GBA (triallelic models) or in only one of them (bi- or monoallelic models). We developed a novel strategy to gene edit the N370S mutation in GBA via CRISPR-Cas9, without interference with its respective pseudogene, which allows for the dissection of the role of GBA in the context of a PRKN mutation on an isogenic background. We identified a specific α-synuclein homeostasis in the triallelic model. The genetic and pharmacological rescue of GBA in the triallelic model modified the observed α-synuclein phenotype, proving the contribution of GBA to the observed phenotype. We then investigated whether Parkin was contributing to the phenotype. The modulation of Parkin function in the context of a GBA mutation induced a modification of the α-synuclein homeostasis. We therefore concluded that both PRKN and GBA are influencing α-synuclein homeostasis in the triallelic model. Nevertheless, the phenotypic outcome of the co-occurrence of these mutations was not additive nor synergistic. We therefore suggest the existence of an epistatic interaction between mutant GCase and Parkin that would underlie the clinical heterogeneity observed in PD patients carrying these mutations. [less ▲]

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See detailIncome Inequality and the Strength of the Origins-Health Gradient in 20 European Countries
Chauvel, Louis UL; Bar-Haim, Eyal UL; Leist, Anja UL

Scientific Conference (2019, September 12)

Health is determined by socio-economic position not only of the individual, but also by that of their parents. The intergenerational transmission of health via parental socioeconomic status is suggested ... [more ▼]

Health is determined by socio-economic position not only of the individual, but also by that of their parents. The intergenerational transmission of health via parental socioeconomic status is suggested to vary according to contextual factors such as income inequality. Earlier studies with a comparative perspective had a limited number of countries available. This study uses 20 countries at up to five waves from the European Social Survey (2008-2016) and SWIID in order to examine the extent to which income inequality is related to the origins-health gradient. The higher the income inequality of a given country and year, the stronger the origins-health gradient. Contrary to earlier findings, this association can be fully explained by intergenerational transmission of status, i.e. education. Implications of this finding are that health is largely determined by educational attainment and associated health behaviors, giving societal context a less prominent role than earlier studies suggested. [less ▲]

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See detailDigital History as Trading Zone? Reflections from a Doctoral Training Unit
van der Heijden, Tim UL

Scientific Conference (2019, September 12)

This paper addresses the question how Digital History “trading zones” are being constituted in practice and how they are situated in physical working environments. The analysis is based on a case study of ... [more ▼]

This paper addresses the question how Digital History “trading zones” are being constituted in practice and how they are situated in physical working environments. The analysis is based on a case study of the Doctoral Training Unit (DTU) “Digital History and Hermeneutics”, an interdisciplinary research and training programme that was established at the Luxembourg Centre for Contemporary and Digital History (C²DH) of the University of Luxembourg. The DTU is designed as an interdisciplinary “trading zone”, in which thirteen doctoral candidates with different disciplinary backgrounds – from history, linguistics and philosophy to computer and information science – reflect on the epistemological and methodological challenges of doing digital history and humanities research (Fickers 2015, 2012). The paper reflects on the project’s first year, in which the doctoral researchers were introduced to various skills and methods in digital humanities as part of the so-called “DH incubation phase”. This phase included trainings in text mining, digital source criticism, database structures, data visualization, GIS analysis, tool criticism and algorithmic critique. The paper presents some of the main practical and epistemological opportunities and challenges of “thinkering”: the playful experimentation with digital tools and technologies for doing historical research. It furthermore reflects on the practical and institutional challenges of constituting an interdisciplinary trading zone, like the DTU. As such, it addresses a number of critical questions: How to build bridges between different knowledge domains in a specific research environment? How to stimulate interdisciplinary collaboration and to get scholars out of their disciplinary or methodological comfort zones? What is at stake in such interdisciplinary trading zones? Who are the traders – and what is being traded? The analysis is informed by studies on interdisciplinarity (Klein 2015, Deegan and McCarty 2012, Stehr and Weingart 2000), trading zones (Collins et al. 2007, Galison 1996, Kemman 2019) and communities of practice (Wenger 1998). Empirically, it draws on a series of semi-structured interviews and thirty-nine self-reflexive training reports, in which the doctoral researchers of the DTU discuss their experiences of doing digital history and hermeneutics in an interdisciplinary setting. Finally, the paper evaluates the suitability of the trading zone concept as analytical framework for studying interdisciplinary collaborations in Digital History as a field. [less ▲]

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See detailAdaptive equation-free multiscale modeling of metallic lattices with geometrical nonlinearity and variability
Chen, Li UL; Berke, Peter; Beex, Lars UL et al

Scientific Conference (2019, September 12)

An equation-free concurrent multiscale framework is proposed to model 3D metallic lattice structures. The proposed equation-free multiscale method (EFMM) is effectively a generalization of the ... [more ▼]

An equation-free concurrent multiscale framework is proposed to model 3D metallic lattice structures. The proposed equation-free multiscale method (EFMM) is effectively a generalization of the quasicontinuum method [2] and relies on the use of fully-resolved domains (FRD) in which all details of the lattice micro-structure are captured, and of coarse-grained domains (CGD) in which a model reduction is performed by interpolation and summation steps. The particularity of the lattice geometrical description is that cross section variations along the lattice struts (caused by the manufacturing process) are explicitly represented by their discretization in several beam finite elements, both in the FRDs and CGDs. The interpolation step of the EFMM refers to a kinematic approximation of the lattice deformation within CGDs based on the displacement of a reduced number of material points. One of the originalities of this work is the consideration of a separate interpolation of each type of kinematic variables within the CGDs, as a function of the connectivity of the lattice beam nodes (i.e. taking the location of different cross sections into account) and their kinematical pattern. This, together with accounting for geometric nonlinearity, by the development and implementation of a 3D co-rotational beam finite element [1], are innovative contributions. Choosing the appropriate sizes of the FRDs and the CGDs for a lattice to be simulated is a trade-off because larger FRDs prevail the accuracy but compromise the efficiency while larger CGDs do the opposite. Since the required sizes of the FRDs and CGDs are generally not known a priori for specific applications, an adaptive coarse-graining strategy is developed. To be specific, the whole lattice is initially considered as a CGD. Two kinds of error indicator are proposed (e.g. the Zienkiewicz-Zhu error indicator [4, 3] and the error indicator based on the discrepancy of strain energy). The error indicator guides on: 1) introducing more material points and rearranging the interpolation for the CGDs; 2) changing the localization-prone parts of the lattice into FRDs. The adaptive EFMM is applied to metallic BCC lattices with various sizes and loading conditions. By comparing to the results of those of the direct numerical simulation (DNS), it is shown that geometrical non-linearities can be captured at a fraction of the DNS cost. [less ▲]

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See detailA Temporal Warehouse for Modern Luxembourgish Text Collections
Gierschek, Daniela UL; Gilles, Peter UL; Purschke, Christoph UL et al

Presentation (2019, September 12)

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See detailA comparison between conventional Earth Observation Satellites and CubeSats; Requirements, Capabilities and Data Quality
Backes, Dietmar UL; Hassani, Saif Alislam UL; Teferle, Felix Norman UL et al

Scientific Conference (2019, September 11)

From its early beginning as an educational tool in 1999, cubesats have evolved into a popular platform for technology demonstrations and scientific instruments. Ideas and innovations sparked from an ... [more ▼]

From its early beginning as an educational tool in 1999, cubesats have evolved into a popular platform for technology demonstrations and scientific instruments. Ideas and innovations sparked from an enthusiastic community led to the development of new Earth Observation (EO) technology concepts based on large constellations of satellites with high-resolution optical imagers previously considered as infeasible. Probably the most significant constellation today is deployed by Planet who are currently operating a fleet larger than 120 3U Dove satellites, which provide an imaging service with up to 3m Ground Sample Distance (GSD). The number of low-cost EO Cubesat systems is constantly increasing. However, for a number of reasons there still seems to be a reluctance to use such data for many EO applications. A better understanding of the capabilities of the current generation of small Cubesats compared to the traditional well-established bigger operational missions of high and medium resolution EO satellites is required. What are the critical capabilities and quality indicators? Due to the limited size and weight of Cubesats, critical system components, e.g. for navigation and communication, always compete with operational payloads such as optical camera/sensor systems. A functional EO system requires balanced payload, which provides adequate navigational capabilities, that match the requirements of the optical imagers (camera) deployed with the system. This study reviews the current performance and capabilities of Cubesats for optical EO and compares them to the capabilities of conventional, dedicated high and medium resolution EO systems. We summarise key performance parameters and quality indicators to evaluate the difference between the systems. An empirical study compares recent very high-resolution (VHR) imagery from big EO satellite missions with available images from Cubesats for the use case in disaster monitoring. Small and agile Nanosatellites or Cubesats already show remarkable performance. Although it is not expected that their performance and capability will match those of current bigger EO satellite missions, they are expected to provide a valuable tool for EO and remote sensing, in particular for downstream industry applications. [less ▲]

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See detailDynamical Modeling Techniques for Biological Time Series Data
Mombaerts, Laurent UL

Doctoral thesis (2019)

The present thesis is articulated over two main topics which have in common the modeling of the dynamical properties of complex biological systems from large-scale time-series data. On one hand, this ... [more ▼]

The present thesis is articulated over two main topics which have in common the modeling of the dynamical properties of complex biological systems from large-scale time-series data. On one hand, this thesis analyzes the inverse problem of reconstructing Gene Regulatory Networks (GRN) from gene expression data. This first topic seeks to reverse-engineer the transcriptional regulatory mechanisms involved in few biological systems of interest, vital to understand the specificities of their different responses. In the light of recent mathematical developments, a novel, flexible and interpretable modeling strategy is proposed to reconstruct the dynamical dependencies between genes from short-time series data. In addition, experimental trade-offs and optimal modeling strategies are investigated for given data availability. Consistent literature on these topics was previously surprisingly lacking. The proposed methodology is applied to the study of circadian rhythms, which consists in complex GRN driving most of daily biological activity across many species. On the other hand, this manuscript covers the characterization of dynamically differentiable brain states in Zebrafish in the context of epilepsy and epileptogenesis. Zebrafish larvae represent a valuable animal model for the study of epilepsy due to both their genetic and dynamical resemblance with humans. The fundamental premise of this research is the early apparition of subtle functional changes preceding the clinical symptoms of seizures. More generally, this idea, based on bifurcation theory, can be described by a progressive loss of resilience of the brain and ultimately, its transition from a healthy state to another characterizing the disease. First, the morphological signatures of seizures generated by distinct pathological mechanisms are investigated. For this purpose, a range of mathematical biomarkers that characterizes relevant dynamical aspects of the neurophysiological signals are considered. Such mathematical markers are later used to address the subtle manifestations of early epileptogenic activity. Finally, the feasibility of a probabilistic prediction model that indicates the susceptibility of seizure emergence over time is investigated. The existence of alternative stable system states and their sudden and dramatic changes have notably been observed in a wide range of complex systems such as in ecosystems, climate or financial markets. [less ▲]

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See detailInteroceptive accuracy in preschool - aged children: The Jumping Jack Paradigm (JJP)
Opdensteinen, K.; Schaan, L.; Pohl, A. et al

Poster (2019, September 11)

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See detailLearning-based Physical Layer Communications for Multiagent Collaboration
Mostaani, Arsham UL; Simeone, Osvaldo; Chatzinotas, Symeon UL et al

in Mostaani, Arsham; Simeone, Osvaldo; Chatzinotas, Symeon (Eds.) et al PIMRC 2019 Proceedings (2019, September 11)

Consider a collaborative task carried out by two autonomous agents that can communicate over a noisy channel. Each agent is only aware of its own state, while the accomplishment of the task depends on the ... [more ▼]

Consider a collaborative task carried out by two autonomous agents that can communicate over a noisy channel. Each agent is only aware of its own state, while the accomplishment of the task depends on the value of the joint state of both agents. As an example, both agents must simultaneously reach a certain location of the environment, while only being aware of their own positions. Assuming the presence of feedback in the form of a common reward to the agents, a conventional approach would apply separately: (\emph{i}) an off-the-shelf coding and decoding scheme in order to enhance the reliability of the communication of the state of one agent to the other; and (\emph{ii}) a standard multiagent reinforcement learning strategy to learn how to act in the resulting environment. In this work, it is argued that the performance of the collaborative task can be improved if the agents learn how to jointly communicate and act. In particular, numerical results for a baseline grid world example demonstrate that the jointly learned policy carries out compression and unequal error protection by leveraging information about the action policy. [less ▲]

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