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See detailMoving beyond language(s): a case study on a newcomer’s translanguaging practices
Degano, Sarah UL; Kirsch, Claudine UL

in European Journal of Applied Linguistics (2020)

Numerous scholars have investigated translanguaging in students with a migration background by examining the deployment of their linguistic repertoire. By contrast, few studies have adopted a social ... [more ▼]

Numerous scholars have investigated translanguaging in students with a migration background by examining the deployment of their linguistic repertoire. By contrast, few studies have adopted a social semiotic perspective on translanguaging. Similarly, studies on newcomers in this field are scarce. Newcomers, especially those to the trilingual education system in Luxembourg, face significant language challenges. The present paper explores the ways in which Portuguese-speaking Harry combined the resources of his semiotic repertoire in science and French lessons in Year 4, and discusses different combinations of resources. Findings based on field notes and video-recordings of classroom activities show that the eleven-year-old engaged in learning by activating his prior knowledge and deploying his semiotic repertoire in resourceful ways. He mobilised features of five languages, coordinated linguistic, paralinguistic and extralinguistic resources, and aligned his resources to those of his peers. Furthermore, he reproduced the semiotic combinations of peers as well as the translanguaging practices in class. We show that a newcomer orchestrates his semiotic resources in complex ways to communicate, make meaning and engage in learning processes. Further research into the deployment of the semiotic repertoire at school is needed. [less ▲]

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See detailDistinct Cargos of Small Extracellular Vesicles Derived from Hypoxic Cells and Their Effect on Cancer Cells
Walbrecq, Geoffroy; Margue, Christiane UL; Behrmann, Iris UL et al

in International Journal of Molecular Sciences (2020)

Hypoxia is a common hallmark of solid tumors and is associated with aggressiveness, metastasis and poor outcome. Cancer cells under hypoxia undergo changes in metabolism and there is an intense crosstalk ... [more ▼]

Hypoxia is a common hallmark of solid tumors and is associated with aggressiveness, metastasis and poor outcome. Cancer cells under hypoxia undergo changes in metabolism and there is an intense crosstalk between cancer cells and cells from the tumor microenvironment. This cross talk is facilitated by small extracellular vesicles (sEVs; diameter between 30 and 200 nm), including exosomes and microvesicles, which carry a cargo of proteins, mRNA, ncRNA and other biological molecules. Hypoxia is known to increase secretion of sEVs and has an impact on the composition of the cargo. This sEV-mediated crosstalk ultimately leads to various biological effects in the proximal tumor microenvironment but also at distant, future metastatic sites. In this review, we discuss the changes induced by hypoxia on sEV secretion and their cargo as well as their effects on the behaviour and metabolism of cancer cells, the tumor microenvironment and metastatic events. [less ▲]

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See detailMeasuring Executive Functions and their Relations to Mathematical Skills in Preschool Children: A Meta-Analysis
Emslander, Valentin UL; Scherer, Ronny

Scientific Conference (2020, July)

Introduction: Executive functions (inhibition, attention shifting, working memory) are linked to mathematical skills in school students and adults. This link is particularly important because performance ... [more ▼]

Introduction: Executive functions (inhibition, attention shifting, working memory) are linked to mathematical skills in school students and adults. This link is particularly important because performance in school mathematics is predictive of various competencies later in life. While some researchers argue that tests of executive functions and mathematical skills measure the same underlying construct, others argue that they measure distinct but correlated constructs. Also, evidence on the differentiation of cognitive skills over time exists. Clarifying the relation between executive functions and mathematical skills is, however, challenging, especially because preschoolers cannot fill in commonly used questionnaires that require them to read. As a consequence, researchers have to resort to behavioral, verbal, apparatus-, or computer-based assessments of executive functions. Objectives/Methodology: With this meta-analysis of 26 studies containing 238 effect sizes, we examined the link between executive functions and early mathematical skills for a total sample of 24,256 preschool children. Specifically, we synthesized the corresponding correlations and sought to clarify which executive function assessments were used for preschool children and how the assessment characteristics may moderate the correlation between executive functions and mathematical skills. Results: Utilizing three-level random-effects meta-analysis, we found a moderate correlation between executive functions and mathematical skills in preschool children, r = 0.35. The type of assessment (behavioral, verbal, apparatus-, or computer-based assessments) did not moderate this relation. Differentiating between the three executive functions revealed average correlations of r = 0.31 between math and inhibition, r = 0.38 between math and attention shifting, and r = 0.36 between math and updating. These analyses will be supplemented by further moderator analyses. Conclusions: Our findings support the significant link between executive functions and mathematical skills in preschoolers—yet, the average correlations do not suggest that both measures are identical. Results will be discussed against the background of deployed assessments and testing environments. [less ▲]

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See detailOn the practical security of white-box cryptography
Wang, Junwei UL

Doctoral thesis (2020)

Cryptography studies how to secure communications and information. The security of a cryptosystem depends on the secrecy of the underlying key. White-box cryptography explores methods to hide a ... [more ▼]

Cryptography studies how to secure communications and information. The security of a cryptosystem depends on the secrecy of the underlying key. White-box cryptography explores methods to hide a cryptographic key into some software deployed in the real world. Classical cryptography only assumes that the adversary accesses the target cryptographic primitive in a black-box manner in which she can only observe or manipulate the input and output of the primitive, but cannot know or tamper with its internal details. The gray-box model further allows an adversary to exploit key- dependent sensitive information leaked from the execution of physical implementations. All sorts of side-channel attacks exploit some physical information leakage, such as the power consumption of the device. The white-box model considers the worst-case scenario in which the adversary has complete control over the software and its execution environment. The goal of white-box cryptography is to securely implement a cryptographic primitive against such a powerful adversary. Although the scientific community has proposed some candidate solutions to build white-box cryptography, all have proven ineffective. Consequently, this problem has remained open for almost two decades since the concept was introduced. The continuous growth in market demand and the emerging potential applications have driven the industry to deploy secretly-designed proprietary solutions. Al- though this paradigm of achieving security through obscurity contradicts the widely accepted Kerckhoffs' principle in cryptography, this is currently the only option for white-box cryptography. Security experts have reported how gray-box attacks could be used to extract keys from several publicly available white-box implementations. In a gray-box attack, the adversary adapts side-channel analysis techniques to the white-box context, i.e., to target computation traces made of noise-free run- time information instead of the noisy physical leakage. Gray-box attacks are generic since they do not require any a priori knowledge of the implementation and hence avoid costly reverse engineering. Some non-publicly scrutinized industrial white- box schemes in the market are believed to be under the threat of gray-box attacks. This thesis focuses on the analysis and improvement of gray-box attacks and the associated countermeasures for white-box cryptography. We first provide an in- depth analysis of why gray-box attacks are capable of breaking the classical white- box design which is based on table encodings. Next, we introduce a new gray-box at- tack named linear decoding analysis and show that linearly encoding sensitive information is insufficient to protect the cryptographic software. Afterward, we describe how to combine state-of-the-art countermeasures to resist gray-box attacks and comprehensively elaborate on the (in)effectiveness of these combined countermeasures in terms of computation complexity. Finally, we introduce a new attack technique that exploits the data-dependency of the targeted implementation to substantially lower the complexity of the existing gray-box attacks on white-box cryptography. In addition to the theoretical analyses and new attack techniques introduced in this thesis, we report some attack experiments against practical white-box implementations. In particular, we could break the winning implementations of two consecutive editions of the well-known WhibOx white-box cryptography competition. [less ▲]

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See detailSupporting Citizens’ Political Decision-Making Using Information Visualisation
Graf, Vanessa; Graf-Drasch, Valerie; Tiefenbeck, Verena et al

in Proceedings of the 28th European Conference on Information Systems (ECIS) (2020, June 17)

Individual decision-making is a complex process. If carried out by individual citizens in the context of politically relevant decisions, serious consequences at all levels of a society might occur. That ... [more ▼]

Individual decision-making is a complex process. If carried out by individual citizens in the context of politically relevant decisions, serious consequences at all levels of a society might occur. That is why these decisions need to be made with care and preferably on a broad set of information to reflect citizens’ true preferences. However, due to limited attention, citizens often consider only salient aspects in their decision-making. To mitigate unwanted consequences following therefrom, citizens are in dire need of decision-support. We address this need by developing an Information Systems (IS) tool. Being based on information visualisation, our tool supports citizens by providing instant feedback. To ensure a meaningful engagement, the IS tool is designed according to gamification principles. A first instantiation in the context of renewable energy acceptance in Germany yields three key findings: First, we find indications that young, urban, and environmentally aware citizens are willing to accept a high percentage of renewable wind energy. Second, we find that the tool influences citizens’ decision-making. Third, we find citizens to update, however not completely turn over their preferred level of renewable wind energy after interaction with the tool. This holds true across different cross-sections of the population. [less ▲]

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See detailThe Energy Consumption of Blockchain Technology: Beyond Myth
Sedlmeir, Johannes; Ulrich Buhl, Hans; Fridgen, Gilbert UL et al

in Business & Information Systems Engineering (2020)

When talking about blockchain technology in academia, business, and society, frequently generalizations are still heared about its – supposedly inherent – enormous energy consumption. This perception ... [more ▼]

When talking about blockchain technology in academia, business, and society, frequently generalizations are still heared about its – supposedly inherent – enormous energy consumption. This perception inevitably raises concerns about the further adoption of blockchain technology, a fact that inhibits rapid uptake of what is widely considered to be a groundbreaking and disruptive innovation. However, blockchain technology is far from homogeneous, meaning that blanket statements about its energy consumption should be reviewed with care. The article is meant to bring clarity to the topic in a holistic fashion,looking beyond claims regarding the energy consumption of Bitcoin, which have, so far, dominated the discussion. [less ▲]

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See detailHypoxia-Induced Adaptations of miRNomes and Proteomes in Melanoma Cells and Their Secreted Extracellular Vesicles
Walbrecq, Geoffroy; Lecha, Odile; Gaigneaux, Anthoula UL et al

in Cancers (2020)

Reduced levels of intratumoural oxygen are associated with hypoxia-induced pro-oncogenic events such as invasion, metabolic reprogramming, epithelial–mesenchymal transition, metastasis and resistance to ... [more ▼]

Reduced levels of intratumoural oxygen are associated with hypoxia-induced pro-oncogenic events such as invasion, metabolic reprogramming, epithelial–mesenchymal transition, metastasis and resistance to therapy, all favouring cancer progression. Small extracellular vesicles (EV) shuttle various cargos (proteins, miRNAs, DNA and others). Tumour-derived EVs can be taken up by neighbouring or distant cells in the tumour microenvironment, thus facilitating intercellular communication. The quantity of extracellular vesicle secretion and their composition can vary with changing microenvironmental conditions and disease states. Here, we investigated in melanoma cells the influence of hypoxia on the content and number of secreted EVs. Whole miRNome and proteome profiling revealed distinct expression patterns in normoxic or hypoxic growth conditions. Apart from the well-known miR-210, we identified miR-1290 as a novel hypoxia-associated microRNA, which was highly abundant in hypoxic EVs. On the other hand, miR-23a-5p and -23b-5p were consistently downregulated in hypoxic conditions, while the protein levels of the miR-23a/b-5p-predicted targetIPO11were concomitantly upregulated. Furthermore, hypoxic melanoma EVs exhibit a signature consisting of six proteins (AKR7A2, DDX39B, EIF3C, FARSA, PRMT5, VARS), which were significantly associated with a poor prognosis for melanoma patients, indicating that proteins and/or miRNAs secreted by cancer cells may be exploited as biomarkers. [less ▲]

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See detailNational Banking Law in the European Single Supervisory Mechanism
Voordeckers, Olivier UL

Doctoral thesis (2020)

In 2013, the European Central Bank acquired the competence to apply national banking law in a direct manner to banks established in the euro area, as part of its supervisory competence under the Single ... [more ▼]

In 2013, the European Central Bank acquired the competence to apply national banking law in a direct manner to banks established in the euro area, as part of its supervisory competence under the Single Supervisory Mechanism. This marks the first instance of direct administration of national law by a European institution. The thesis scrutinises the salient features as well as the strengths and weaknesses of this new administrative system in the landscape of European Union law. [less ▲]

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See detailMeasures of Executive Functions and Mathematical Skills are Distinct Even at a Young Age: A Meta-Analysis with Preschool Children
Emslander, Valentin UL; Scherer, Ronny

Scientific Conference (2020)

Measures of executive functions (inhibition, attention shifting, working memory) are linked to measures of mathematical skills in school students and adults. However, the magnitude of this relation in ... [more ▼]

Measures of executive functions (inhibition, attention shifting, working memory) are linked to measures of mathematical skills in school students and adults. However, the magnitude of this relation in preschool children is unclear. Following the literature on the differentiation of cognitive skills over time, some researchers suggest that tests of executive functions and mathematical skills measure the same underlying construct, while others suggest that they measure correlated but distinct constructs. This dispute does not only tap the question of how the constructs can be understood but also the question of cost and test efficiency (i.e., assessments of single vs. multiple constructs). Clarifying the relation between measures of the two constructs can be especially challenging because preschoolers cannot fill in commonly used questionnaires that require them to read. Thus, researchers have to resort to behavioral, verbal, apparatus-, or computer-based assessments of executive functions. As a result, executive functions may vary in their relation to mathematical skills as a consequence of their measurement. We examined the link between executive functions and early mathematical skills measures, conducting a meta-analysis of 26 studies containing 238 effect sizes for a total sample of 24,256 preschool children. Specifically, we synthesized the corresponding correlations and aimed to clarify which executive function assessments were used for preschool children and how assessment characteristics may moderate the correlation between executive functions and mathematical skills. Three-level random-effects meta-analysis revealed a small to moderate average correlation between executive functions and mathematical skills measures of preschool children, r = 0.35. The type of assessment (behavioral, verbal, apparatus-, or computer-based assessments) did not moderate this relation. Investigating the three executive functions separately, we found average correlations of r = 0.31 between mathematical skills and inhibition, r = 0.38 between mathematical skills and attention shifting, and r = 0.36 between mathematical skills and updating. These analyses will be supplemented by further moderator and sensitivity analyses. These findings emphasize the significant link between executive functions and mathematical skills measures in preschoolers—hereby, supporting that the measures of both constructs are distinct. In addition, under-researched areas around the assessment of executive functions and mathematical abilities will be discussed. [less ▲]

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See detailHow microbial community composition, sorption and simultaneous application of six pharmaceuticals affect their dissipation in soils
Kodesova, Radka; Chronakova, Alica; Grabicova, Katerina et al

in Science of the Total Environment (2020), 746

Pharmaceuticals may enter soils due to the application of treated wastewater or biosolids. Their leakage from soils towards the groundwater, and their uptake by plants is largely controlled by sorption ... [more ▼]

Pharmaceuticals may enter soils due to the application of treated wastewater or biosolids. Their leakage from soils towards the groundwater, and their uptake by plants is largely controlled by sorption and degradation of those compounds in soils. Standard laboratory batch degradation and sorption experiments were performed using soil samples obtained from the top horizons of seven different soil types and 6 pharmaceuticals (carbamazepine, irbesartan, fexofenadine, clindamycin and sulfamethoxazole), which were applied either as single-solute solutions or as mixtures (not for sorption). The highest dissipation half-lives were observed for citalopram (average DT50,S for a single compound of 152 ± 53.5 days) followed by carbamazepine (106.0 ± 17.5 days), irbesartan (24.4 ± 3.5 days), fexofenadine (23.5 ± 20.9 days), clindamycin (10.8 ± 4.2 days) and sulfamethoxazole (9.6 ± 2.0 days). The simultaneous application of all compounds increased the half-lives (DT50,M) of all compounds (particularly carbamazepine, citalopram, fexofenadine and irbesartan), which is likely explained by the negative impact of antibiotics (sulfamethoxazole and clindamycin) on soil microbial community. However, this trend was not consistent in all soils. In several cases, the DT50,S values were even higher than the DT50,M values. Principal component analyses showed that while knowledge of basic soil properties determines grouping of soils according sorption behavior, knowledge of the microbial community structure could be used to group soils according to the dissipation behavior of tested compounds in these soils. The derived multiple linear regression models for estimating dissipation half-lives (DT50,S) for citalopram, clindamycin, fexofenadine, irbesartan and sulfamethoxazole always included at least one microbial factor (either amount of phosphorus in microbial biomass or microbial biomarkers derived from phospholipid fatty acids) that deceased half-lives (i.e., enhanced dissipations). Equations for citalopram, clindamycin, fexofenadine and sulfamethoxazole included the Freundlich sorption coefficient, which likely increased half-lives (i.e., prolonged dissipations). [less ▲]

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See detailAlzette: A 64-Bit ARX-box - (Feat. CRAX and TRAX)
Beierle, Christof; Biryukov, Alexei UL; Cardoso Dos Santos, Luan UL et al

in Advances in Cryptology - CRYPTO 2020 - 40th Annual International Cryptology Conference, CRYPTO 2020, Santa Barbara, CA, USA, August 17-21, 2020, Proceedings, Part III (2020)

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See detailHow to reveal the secrets of an obscure white-box implementation
Goubin, Louis; Paillier, Pascal; Rivain, Matthieu UL et al

in Journal of Cryptographic Engineering (2019), 10(1), 49--66

White-box cryptography protects key extraction from software implementations of cryptographic primitives. It is widely deployed in DRM and mobile payment applications in which a malicious attacker might ... [more ▼]

White-box cryptography protects key extraction from software implementations of cryptographic primitives. It is widely deployed in DRM and mobile payment applications in which a malicious attacker might control the entire execution environment. So far, no provably secure white- box implementation of AES has been put forward, and all the published practical constructions are vulnerable to differential computation analysis (DCA) and differential fault analysis (DFA). As a consequence, the industry relies on home-made obscure white-box implementations based on secret designs. It is therefore of interest to investigate the achievable resistance of an AES implementation to thwart a white-box adversary in this paradigm. To this purpose, the ECRYPT CSA project has organized the WhibOx contest as the catch the flag challenge of CHES 2017. Researchers and engineers were invited to participate either as designers by submitting the source code of an AES-128 white-box implementation with a freely chosen key, or as breakers by trying to extract the hard-coded keys in the submitted challenges. The participants were not expected to disclose their identities or the underlying designing/attacking techniques. In the end, 94 submitted challenges were all broken and only 13 of them held more than 1 day. The strongest (in terms of surviving time) implementation, submitted by Biryukov and Udovenko, survived for 28 days (which is more than twice as much as the second strongest implementation), and it was broken by a single team, i.e., the authors of the present paper, with reverse engineering and algebraic analysis. In this paper, we give a detailed description of the different steps of our cryptanalysis. We then generalize it to an attack methodology to break further obscure white-box implementations. In particular, we formalize and generalize the linear decoding analysis that we use to extract the key from the encoded intermediate variables of the target challenge. [less ▲]

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See detailHigher-Order DCA against Standard Side-Channel Countermeasures
Bogdanov, Andrey; Rivain, Matthieu; Philip, S. Vejre et al

in Polian, Ilia; Stöttinger, Marc (Eds.) Constructive Side-Channel Analysis and Secure Design (2019, March 16)

At CHES 2016, Bos et al. introduced differential computational analysis (DCA) as an attack on white-box software implementations of block ciphers. This attack builds on the same principles as DPA in the ... [more ▼]

At CHES 2016, Bos et al. introduced differential computational analysis (DCA) as an attack on white-box software implementations of block ciphers. This attack builds on the same principles as DPA in the classical side-channel context, but uses computational traces consisting of plain values computed by the implementation during execution. It was shown to be able to recover the key of many existing AES white-box implementations. The DCA adversary is passive, and so does not exploit the full power of the white-box setting, implying that many white-box schemes are insecure even in a weaker setting than the one they were designed for. It is therefore important to develop implementations which are resistant to this attack. We investigate the approach of applying standard side-channel countermeasures such as masking and shuffling. Under some necessary conditions on the underlying randomness generation, we show that these countermeasures provide resistance to standard (first-order) DCA. Furthermore, we introduce higher-order DCA, along with an enhanced multivariate version, and analyze the security of the countermeasures against these attacks. We derive analytic expressions for the complexity of the attacks – backed up through extensive attack experiments – enabling a designer to quantify the security level of a masked and shuffled implementation in the (higher-order) DCA setting. [less ▲]

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See detailSozialpsychologie und die AfD – Wieviel Psychologie steckt im Wahlprogramm?
Emslander, Valentin UL; Bolli, Swantje; Schellen, Guido

Speeches/Talks (2018)

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See detailDie Psychologie des Widerstands: Sozialpsychologische Mechanismen im AfD-Wahlprogramm erkennen
Emslander, Valentin UL; Bolli, Swantje; Leistikow, Helen et al

Presentation (2018, May)

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See detailSozialpsychologie und die AfD – Wieviel Psychologie steckt im Wahlprogramm?
Emslander, Valentin UL; Bolli, Swantje; Leistikow, Helen et al

Presentation (2018, January)

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