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See detailCortisol rapidly increases baroreflex sensitivity of heart rate control, but does not affect cardiac modulation of startle
Schulz, André UL; Richter, Steffen; Ferreira de Sá, Diana S. et al

in Physiology and Behavior (2020), 215(1), 112792

Cortisol, the final product of human HPA axis activation, rapidly modulates the cortical processing of afferent signals originating from the cardiovascular system. While peripheral effects have been ... [more ▼]

Cortisol, the final product of human HPA axis activation, rapidly modulates the cortical processing of afferent signals originating from the cardiovascular system. While peripheral effects have been excluded, it remains unclear whether this effect is mediated by cortical or subcortical (e.g. brainstem) CNS mechanisms. Cardiac modulation of startle (CMS) has been proposed as a method to reflect cardio-afferent signals at subcortical (potentially brainstem-) level. Using a single blind, randomized controlled design, the cortisol group (n = 16 volunteers) received 1 mg cortisol intravenously, while the control group (n = 16) received a placebo substance. The CMS procedure involved the assessment of eye blink responses to acoustic startle stimuli elicited at six different latencies to ECG-recorded R-waves (R + 0, 100, 200, 300, 400 and 500 ms). CMS was assessed at four measurement points: baseline, -16 min, +0 min, and +16 min relative to substance application. Baroreflex sensitivity (BRS) of heart rate (HR) control was measured non-invasively based on spontaneous beat-to-beat HR and systolic blood pressure changes. In the cortisol group, salivary cortisol concentration increased after IV cortisol administration, indicating effective distribution of the substance throughout the body. Furthermore, BRS increased in the cortisol group after cortisol infusion. There was no effect of cortisol on the CMS effect, however. These results suggest that low doses of cortisol do not affect baro-afferent signals, but central or efferent components of the arterial baroreflex circuit presumably via rapid, non-genomic mechanisms. [less ▲]

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See detailHeart and brain: cortical representation of cardiac signals is disturbed in borderline personality disorder, but unaffected by oxytocin administration
Schmitz, M.; Müller, L. E.; Schulz, André UL et al

in Journal of Affective Disorders (2020), 264(1), 24-28

Background: Emotional dysregulation, a core feature of borderline personality disorder (BPD) has recently been linked to deficits in the cortical representation of bodily signals. Oxytocin modulates the ... [more ▼]

Background: Emotional dysregulation, a core feature of borderline personality disorder (BPD) has recently been linked to deficits in the cortical representation of bodily signals. Oxytocin modulates the salience of external social cues. However, its role in interoception is still not fully understood. The aim of the current study was to replicate reduced heartbeatevoked potentials (HEPs) as a marker for the cortical representation of cardiac signals in BPD and to explore potential effects of oxytocin on HEP amplitude. Methods: Fifty-three medication-free women with a DSM-IV diagnosis of BPD and sixty healthy female controls (HCs) participated in the study. In a randomized, double-blind placebo-controlled trial, participants self-administered either 24 I.U. of oxytocin or placebo and took part in a 5-minute resting-state electrocardiogram (ECG) with parallel electroencephalogram (EEG) measurement. In addition, emotional dysregulation and BPD symptomatology were assessed with self-report questionnaires. Results: Patients with BPD had significantly lower mean HEP amplitudes than HCs. Furthermore, HEP amplitudes were negatively correlated with emotional dysregulation in the whole sample. However, oxytocin had no significant effect on HEP amplitude. Limitations: Only female participants were investigated and no clinicial controls were included. Conclusions: This is the first replication from an independent sample showing a reduced cortical representation of cardiac signals in BPD patients. This, together with other bodyrelated symptoms, suggests deficits in the processing of bodily signals, which seem to be associated with emotional dysregulation. Whether oxytocin influences HEP during emotion regulation tasks needs to be investigated in future studies. [less ▲]

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See detailFatigue phase-field damage modeling of rubber using viscous dissipation: Crack nucleation and propagation
Loew, Pascal Juergen UL; Peters, Bernhard UL; Beex, Lars UL

in Mechanics of Materials (2020), 142

By regularizing sharp cracks within a pure continuum setting, phase-damage models offer the ability to capture crack nucleation as well as crack propagation. Crack branching and coalescence can ... [more ▼]

By regularizing sharp cracks within a pure continuum setting, phase-damage models offer the ability to capture crack nucleation as well as crack propagation. Crack branching and coalescence can furthermore be described without any additional efforts, as geometrical descriptions of the cracks are not required. In this contribution, we extend our previous phase-field model for rate-dependent fracture of rubbers in a finite strain setting (Loew et al., 2019) to describe damage under cyclic loading. The model is derived from the balance of mechanical energy and introduces a fatigue damage source as a function of the accumulated viscous dissipation under cyclic loading. We use uniaxial cyclic tension to present the influence of the fatigue material parameters and to confirm the model’s energy balance. The parameters are subsequently identified using monotonic and cyclic experiments of a plane stress nature. Finally, the model is validated by separate experiments, which demonstrate that the model accurately predicts (fatigue) crack nucleation as well as propagation. [less ▲]

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See detailThe Integration Between National and International Regulation of Space Resources Activities Under Public International Law
Salmeri, Antonino UL

in Journal of Space Law (2019), 43(1), 60-85

In light of the current tendency of regulating space resources activities through national legislation, this article addresses the validity of such emerging practice under Public International Law (PIL ... [more ▼]

In light of the current tendency of regulating space resources activities through national legislation, this article addresses the validity of such emerging practice under Public International Law (PIL). To this end, the article first recalls the traditional debate between Monism and Dualism about the relationship between municipal and international law. This analysis is further completed by focusing also on the counter-position between two cornerstones of PIL, the principles of State sovereignty and Pacta Sunt Servanda. Next, the article assesses the exposure of national law “integrating” international law, focusing on ex post conflicts between the two sources as regulated by Article 27 of the Vienna Convention on the Law of Treaties. Accordingly, the article will show that States not willing to adapt their national laws will have to face international responsibility under the Draft Articles on State Responsibility for Internationally Wrongful Acts. Based on the above, the article then presents the related legal consequences, both at the international and national levels. Finally, the article closes by assessing the role of interpretative declarations and the defense of persistent objector as possible legal tools for dissenting States. [less ▲]

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See detailHow Acceptable Is This? How User Experience Factors Can Broaden our Understanding of the Acceptance of Privacy Trade-Offs
Distler, Verena UL; Lallemand, Carine UL; Koenig, Vincent UL

in Computers in Human Behavior (2019)

Privacy is a timely topic that is increasingly scrutinized in the public eye. In spite of privacy and security breaches, people still frequently compromise their privacy in exchange for certain benefits ... [more ▼]

Privacy is a timely topic that is increasingly scrutinized in the public eye. In spite of privacy and security breaches, people still frequently compromise their privacy in exchange for certain benefits of a technology or a service. This study builds on both technology acceptance (TA) and user experience (UX) research in order to explore and build hypotheses regarding additional dimensions that might play a role in the acceptability of privacy tradeoffs that are not currently accounted for in TA models. Using four scenarios describing situations with potential privacy trade-offs, we conducted a focus group study with 8 groups of participants (N = 32). Our results suggest that factors influencing privacy trade-offs go beyond existing TA factors alone. A technology's perceived usefulness plays an important role, as well as dimensions related to context, previous experiences, perceived autonomy and the feeling of control over the data being shared. [less ▲]

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See detailEditorial: teachers’ attitudes and self‐efficacy beliefs with regard to inclusive education
Pit-Ten Cate, Ineke UL; Schwab, Susanne; Hecht, Petra et al

in Journal of Research in Special Educational Needs (2019), 19(S1), 3-7

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See detailIdentification of pathogenic variant enriched regions across genes and gene families
Perez-Palma, Eduardo; May, Patrick UL; Iqbal, Sumaiya et al

in Genome Research (2019)

Missense variant interpretation is challenging. Essential regions for protein function are conserved among gene family members, and genetic variants within these regions are potentially more likely to ... [more ▼]

Missense variant interpretation is challenging. Essential regions for protein function are conserved among gene family members, and genetic variants within these regions are potentially more likely to confer risk to disease. Here, we generated 2,871 gene family protein sequence alignments involving 9,990 genes and performed missense variant burden analyses to identify novel essential protein regions. We mapped 2,219,811 variants from the general population into these alignments and compared their distribution with 76,153 missense variants from patients. With this gene family approach, we identified 465 regions enriched for patient variants spanning 41,463 amino acids in 1,252 genes. As a comparison, testing the same genes individually we identified less patient variant enriched regions involving only 2,639 amino acids and 215 genes. Next, we selected de novo variants from 6,753 patients with neurodevelopmental disorders and 1,911 unaffected siblings, and observed an 8.33-fold enrichment of patient variants in our identified regions (95% C.I.=3.90-Inf, p-value = 2.72x10-11). Using the complete ClinVar variant set, we found that missense variants inside the identified regions are 106-fold more likely to be classified as pathogenic in comparison to benign classification (OR = 106.15, 95% C.I = 70.66-Inf, p-value < 2.2 x 10-16). All pathogenic variant enriched regions (PERs) identified are available online through the “PER viewer” a user-friendly online platform for interactive data mining, visualization and download. In summary, our gene family burden analysis approach identified novel pathogenic variant enriched regions in protein sequences. This annotation can empower variant interpretation. [less ▲]

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See detailScaffolding support through integration of learning material
Grevisse, Christian UL; Rothkugel, Steffen UL; Reuter, Robert UL

in Smart Learning Environments (2019), 6(28),

The ever-growing amount of learning material poses a challenge to both learners and teachers. In order to perform a learning task, students often need to search for additional information. Inquiry might ... [more ▼]

The ever-growing amount of learning material poses a challenge to both learners and teachers. In order to perform a learning task, students often need to search for additional information. Inquiry might be hampered if they do not know what exactly to search for, especially if they lack prior knowledge in a domain. Furthermore, they might need to recall meta-information, e.g., the implicit links between learning resources or the location of an explanation within a document. In addition, their performance in a learning task might suffer from the constant need for further information. As the authoring of learning material is a time-intensive task, reusability of resources in different contexts should be enabled. In this paper, we present the ALMA-Yactul ecosystem, a holistic approach for student-centered integration of learning material. Based on semantic annotations, learners are provided with scaffolding support for retrieving material related to their current study task. This integration of resources is showcased in a variety of applications and domains, such as a plugin for an IDE or an enhanced sketchnoting app. Moreover, we show how Yactul, a gamified student response platform, can benefit from semantic annotations and integration of learning material. Additionally, teachers are provided with semi-automatic annotation support in the popular Office 365 suite to foster the reusability of their content. Apart from presenting the results of its usage in university classes, we also show how high school students without prior knowledge benefitted from this scaffolding support. A significantly better performance in resolving programming-related tasks could be observed compared to a traditional search process. Finally, the ecosystem is evaluated against a state-of-the-art technology integration model. [less ▲]

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See detailA performance evaluation of weight-constrained conditioned portfolio optimization
Schiltz, Jang UL; Boissaux, Marc UL

Scientific Conference (2019, December 20)

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See detailA deep neural network approach to predicting clinical outcomes of neuroblastoma patients
Tranchevent, Leon-Charles UL; Azuaje, Francisco; Rajapakse, Jagath

in BMC Medical Genomics (2019), 12(8), 178

Background The availability of high-throughput omics datasets from large patient cohorts has allowed the development of methods that aim at predicting patient clinical outcomes, such as survival and ... [more ▼]

Background The availability of high-throughput omics datasets from large patient cohorts has allowed the development of methods that aim at predicting patient clinical outcomes, such as survival and disease recurrence. Such methods are also important to better understand the biological mechanisms underlying disease etiology and development, as well as treatment responses. Recently, different predictive models, relying on distinct algorithms (including Support Vector Machines and Random Forests) have been investigated. In this context, deep learning strategies are of special interest due to their demonstrated superior performance over a wide range of problems and datasets. One of the main challenges of such strategies is the “small n large p” problem. Indeed, omics datasets typically consist of small numbers of samples and large numbers of features relative to typical deep learning datasets. Neural networks usually tackle this problem through feature selection or by including additional constraints during the learning process. Methods We propose to tackle this problem with a novel strategy that relies on a graph-based method for feature extraction, coupled with a deep neural network for clinical outcome prediction. The omics data are first represented as graphs whose nodes represent patients, and edges represent correlations between the patients’ omics profiles. Topological features, such as centralities, are then extracted from these graphs for every node. Lastly, these features are used as input to train and test various classifiers. Results We apply this strategy to four neuroblastoma datasets and observe that models based on neural networks are more accurate than state of the art models (DNN: 85%-87%, SVM/RF: 75%-82%). We explore how different parameters and configurations are selected in order to overcome the effects of the small data problem as well as the curse of dimensionality. Conclusions Our results indicate that the deep neural networks capture complex features in the data that help predicting patient clinical outcomes. [less ▲]

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See detailInter-regional innovation cooperation and structural heterogeneity:Does being a rural, or border region, or both, make a difference?
Hjaltadottir, Rannveig Edda UL; Makkonen, Teemu; Mitze, Timo Friedel

in Journal of Rural Studies (2019)

This paper analyses the determinants of inter-regional innovation cooperation in European knowledge networks. Our main goal is to assess whether structural heterogeneity in the context of the “urban ... [more ▼]

This paper analyses the determinants of inter-regional innovation cooperation in European knowledge networks. Our main goal is to assess whether structural heterogeneity in the context of the “urban-rural dichotomy†and international borders can explain differences in the regions’ engagement in inter-regional innovation coopera-tion. We estimate a gravity equation to model innovation cooperation, proxied by inter-regional co-patent ap-plications, as a function of region-specific context conditions as well as technological and geographical distance. Our data comprise dyadic information on 203 NUTS2 regions in 15 European countries (EU-15) for the year 2010. The empirical results show that the basic gravity mechanisms drive the direction and strength of in-novation cooperation between EU regions; i.e., geographical distance acts as an impediment to inter-regional co-patent applications. Regarding the importance of structural heterogeneity, we find that pairs of rural regions have lower levels of innovation cooperation compared to urban regions. Similarly, border regions are generally disadvantaged compared to non-border regions in terms of the intensity of innovation cooperation. However, while the latter result points to a negative border effect, our gravity model estimates also show that pairs of border regions are more active in terms of close geographical innovation cooperation (e.g., through international cross-border cooperation), which partly compensates for the negative border effect. This finding not only holds for urban but also rural border regions and may reflect policy attempts to support border regions, e.g., by strengthening the level of international cross-border cooperation within the EU. [less ▲]

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See detailOptimization of Rate Fairness in Multi-Pair Wireless-Powered Relaying System
Bui, Van-Phuc; Nguyen, van Dinh UL; Nguyen, Hieu et al

in IEEE Communications Letters (2019)

This letter considers a multi-pair decode-andforward relay network where a power-splitting (PS) protocol is adopted at the energy-constrained relay to provide simultaneous wireless information and energy ... [more ▼]

This letter considers a multi-pair decode-andforward relay network where a power-splitting (PS) protocol is adopted at the energy-constrained relay to provide simultaneous wireless information and energy harvesting (EH). To achieve higher efficiency of EH, we propose a new PS-based EH architecture at the relay by incorporating an alternating current (AC) computing logic, which is employed to directly use the wirelessly harvestedACenergyforcomputationalblocks.Underanonlinear EHcircuit,ourgoalistomaximizethefairnessofend-to-endrate amonguserpairssubjecttopowerconstraints,resultinginanonconvex problem. We propose an iterative algorithm to achieve a suboptimal and efficient solution to this challenging problem by leveraging the inner approximation framework. Numerical results demonstrate that the proposed algorithm outperforms the traditional direct current computing and other baseline schemes. [less ▲]

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See detailInvestigation of the Sharkskin melt instability using optical Fourier analysis
Gansen, Alex UL; Rehor, Martin UL; Sill, Clemens et al

in Journal of Applied Polymer Science (2019)

An optical method allowing the characterization of melt flow instabilities typically occurring during an extrusion process of polymers and polymer compounds is presented. It is based on a camera‐acquired ... [more ▼]

An optical method allowing the characterization of melt flow instabilities typically occurring during an extrusion process of polymers and polymer compounds is presented. It is based on a camera‐acquired image of the extruded compound with a reference length scale. Application of image processing and transformation of the calibrated image to the frequency domain yields the magnitude spectrum of the instability. The effectiveness of the before mentioned approach is shown on Styrene‐butadiene rubber (SBR) compounds, covering a wide range of silica filler content, extruded through a Göttfert capillary rheometer. The results of the image‐based analysis are compared with the results from the sharkskin option, a series of highly sensitive pressure transducers installed inside the rheometer. A simplified version of the code used to produce the optical analysis results is included as supplementary material. [less ▲]

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See detailThe Zooniverse and the Historian
Tatarinov, Juliane UL

Diverse speeches and writings (2019)

https://dhh.uni.lu/2019/12/19/the-zooniverse-and-the-historian/

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See detailHome literacy environment and family language policy of immigrant families in Luxembourg
Aleksic, Gabrijela UL; Bebic, Dzoen Dominique UL

Scientific Conference (2019, December 18)

Early literacy skills are critical for children’s later academic achievement. A wealth of research showed that children’s home languages should not be abandoned, as they are crucial for promoting dynamic ... [more ▼]

Early literacy skills are critical for children’s later academic achievement. A wealth of research showed that children’s home languages should not be abandoned, as they are crucial for promoting dynamic multilingualism, assuring cross-linguistic transfer and developing identities. To explore home literacy environment and family language policy of language minority preschool children in Luxembourg, we obtained 603 parent questionnaires, tested 226 children age 4 to 6 in their home languages and Luxembourgish, and interviewed 31 families. The results from the questionnaires showed that the home resources and parent involvement influenced children’s language awareness and their print knowledge irrespective of parent’s education and their wealth. Concerning children’s competences in Luxembourgish, children with positive attitudes towards their school did better than their peers in other schools. In the interviews, parents explained that maintaining home language is important for keeping connections with family, friends and their culture. This is the language parents feel emotionally connected to and the easiest to transmit to their children. Language maintenance is mostly achieved through conversations, movies, games and books in the home languages, children’s attendance of language schools on weekends, celebrations of traditions as well as holidays in the native country of the parents. The home language is, however, not something parents enforce too strictly, as they mostly correct the children’s linguistic mistakes by simple repetition. It is often with great pride that parents report their children having an excellent proficiency in their home language. Finally, through our professional development training in translanguaging we are helping teachers to integrate children’s different home languages and cultures into the classroom and strengthen the home-school collaboration in order to support children’s well-being, learning and identities. [less ▲]

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See detailDeep Pattern Mining for Program Repair
Liu, Kui UL

Doctoral thesis (2019)

Error-free software is a myth. Debugging thus accounts for a significant portion of software maintenance and absorbs a large part of software cost. In particular, the manual task of fixing bugs is tedious ... [more ▼]

Error-free software is a myth. Debugging thus accounts for a significant portion of software maintenance and absorbs a large part of software cost. In particular, the manual task of fixing bugs is tedious, error- prone and time-consuming. In the last decade, automatic bug-fixing, also referred to as automated program repair (APR) has boomed as a promising endeavor of software engineering towards alleviating developers’ burden. Several potentially promising techniques have been proposed making APR an increasingly prominent topic in both the research and practice communities. In production, APR will drastically reduce time-to-fix delays and limit downtime. In a development cycle, APR can help suggest changes to accelerate debugging. As an emergent domain, however, program repair has many open problems that the community is still exploring. Our work contributes to this momentum on two angles: the repair of programs for functionality bugs, and the repair of programs for method naming issues. The thesis starts with highlighting findings on key empirical studies that we have performed to inform future repair approaches. Then, we focus on template-based program repair scenarios and explore deep learning models for inferring accurate and relevant patterns. Finally, we integrate these patterns into APR pipelines, which yield the state of the art repair tools. The dissertation includes the following contributions: • Real-world Patch Study: Existing APR studies have shown that the state-of-the-art techniques in automated repair tend to generate patches only for a small number of bugs even with quality issues (e.g., incorrect behavior and nonsensical changes). To improve APR techniques, the community should deepen its knowledge on repair actions from real-world patches since most of the techniques rely on patches written by human developers. However, previous investigations on real-world patches are limited to statement level that is not sufficiently fine-grained to build this knowledge. This dissertation starts with deepening this knowledge via a systematic and fine-grained study of real-world Java program bug fixes. • Fault Localization Impact: Existing test-suite-based APR systems are highly dependent on the performance of the fault localization (FL) technique that is the process of the widely studied APR pipeline. However, APR systems generally focus on the patch generation, but tend to use similar but different strategies for fault localization. To assess the impact of FL on APR, we identify and investigate a practical bias caused by the FL step in a repair pipeline. We propose to highlight the different FL configurations used in the literature, and their impact on APR systems when applied to the real bugs. Then, we explore the performance variations that can be achieved by “tweaking” the FL step. • Fix Pattern Mining: Fix patterns (a.k.a. fix templates) have been studied in various APR scenarios. Particularly, fix patterns have been widely used in different APR systems. To date, fix pattern mining is mainly studied in three ways: manually summarization, transformation inferring and code change action statistics. In this dissertation, we explore mining fix patterns for static bugs leveraging deep learning and clustering algorithms. • Avatar: Fix pattern based patch generation is a promising direction in the APR community. Notably, it has been demonstrated to produce more acceptable and correct patches than the patches obtained with mutation operators through genetic programming. The performance of fix pattern based APR systems, however, depends on the fix ingredients mined from commit changes in development histories. Unfortunately, collecting a reliable set of bug fixes in repositories can be challenging. We propose to investigate the possibility in an APR scenario of leveraging code changes that address violations by static bug detection tools. To that end, we build the Avatar APR system, which exploits fix patterns of static analysis violations as ingredients for patch generation. • TBar: Fix patterns are widely used in patch generation of APR, however, the repair performance of a single fix pattern is not studied. We revisit the performance of template-based APR to build comprehensive knowledge about the effectiveness of fix patterns, and to highlight the importance of complementary steps such as fault localization or donor code retrieval. To that end, we first investigate the literature to collect, summarize and label recurrently-used fix patterns. Based on the investigation, we build TBar, a straightforward APR tool that systematically attempts to apply these fix patterns to program bugs. We thoroughly evaluate TBar on the Defects4J benchmark. In particular, we assess the actual qualitative and quantitative diversity of fix patterns, as well as their effectiveness in yielding plausible or correct patches. • Debugging Method Names: Except the issues about semantic/static bugs in programs, we note that how to debug inconsistent method names automatically is important to improve program quality. In this dissertation, we propose a deep learning based approach to spotting and refactoring inconsistent method names in programs. [less ▲]

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See detailFrom home to early childhood education: beliefs, language ideologies and OPOL
Kirsch, Claudine UL

Scientific Conference (2019, December 18)

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