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See detailProvable Security of (Tweakable) Block Ciphers Based on Substitution-Permutation Networks
Cogliati, Benoît-Michel UL; Dodis, Yevgeniy; Katz, Jonathan et al

in Provable Security of (Tweakable) Block Ciphers Based on Substitution-Permutation Networks (2018)

Substitution-Permutation Networks (SPNs) refer to a family of constructions which build a wn-bit block cipher from n-bit public permutations (often called S-boxes), which alternate keyless and “local” ... [more ▼]

Substitution-Permutation Networks (SPNs) refer to a family of constructions which build a wn-bit block cipher from n-bit public permutations (often called S-boxes), which alternate keyless and “local” substitution steps utilizing such S-boxes, with keyed and “global” permu- tation steps which are non-cryptographic. Many widely deployed block ciphers are constructed based on the SPNs, but there are essentially no provable-security results about SPNs. In this work, we initiate a comprehensive study of the provable security of SPNs as (possibly tweakable) wn-bit block ciphers, when the underlying n-bit permutation is modeled as a public random permutation. When the permutation step is linear (which is the case for most existing designs), we show that 3 SPN rounds are necessary and sufficient for security. On the other hand, even 1-round SPNs can be secure when non-linearity is allowed. Moreover, 2-round non-linear SPNs can achieve “beyond- birthday” (up to 2 2n/3 adversarial queries) security, and, as the number of non-linear rounds increases, our bounds are meaningful for the number of queries approaching 2 n . Finally, our non-linear SPNs can be made tweakable by incorporating the tweak into the permutation layer, and provide good multi-user security. As an application, our construction can turn two public n-bit permuta- tions (or fixed-key block ciphers) into a tweakable block cipher working on wn-bit inputs, 6n-bit key and an n-bit tweak (for any w ≥ 2); the tweakable block cipher provides security up to 2 2n/3 adversarial queries in the random permutation model, while only requiring w calls to each permutation, and 3w field multiplications for each wn-bit input. [less ▲]

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See detailL’écologie dans la littérature de jeunesse au Luxembourg : pour une écocritique comparée intralittéraire
Thiltges, Sébastian UL

in Glesener, Jeanne (Ed.) Lëtzebuerger Literaturen am Verglach (2018)

During the last decades, ecology has become a global socio-political stake, but also a recurrent literary theme. The recent research field of ecocriticism is rooted in the US, but is rapidly spreading ... [more ▼]

During the last decades, ecology has become a global socio-political stake, but also a recurrent literary theme. The recent research field of ecocriticism is rooted in the US, but is rapidly spreading across the scientific and cultural worlds, diversifying its interests and methods. Scholars all over the world particularly stress the importance of developing a comparative ecocriticism that internationally explores ecological discourses in different languages and cultures. According to the book’s aims, this paper compares three works of literature, which address environmental problems and/or try to develop an ecological sensibility, trespassing not national, but linguistic borders. The study of children’s literature has not been waiting for ecocritical theory to attest the importance of ecology as a main theme in texts addressing children. In many ways, education and consciousness-raising of the younger generations are supposed to be crucial, because these future adults will be even more concerned with climate change and will have to offer creative solutions to the environmental crisis. Yet, excessive pedagogy, enforcing awareness or even guilt, of both environmental writings and didactical children’s literature, has been a central aesthetical problem. This invites us not to limit our conclusions to an evaluation of the texts’ ecological substance and correctness, but rather to describe the multiple bonds between nature, aesthetics and narratives. We thus choose three works in three different languages which represent three different literary genres, namely crime fiction, fairy tale and poetry, to suggest that this poetical diversity of languages, motives, themes and narratives has to be seen as literature’s stand for nature’s protection in a multicultural landscape. [less ▲]

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See detailFlagellar number governs bacterial spreading and transport efficiency
Najafi, Javad; Shaebani, Mohammad Reza; John, Thomas et al

in SCIENCE ADVANCES (2018), 4(9),

Peritrichous bacteria synchronize and bundle their flagella to actively swim, while disruption of the bundle leads to a slow motility phase with a weak propulsion. It is still not known whether the number ... [more ▼]

Peritrichous bacteria synchronize and bundle their flagella to actively swim, while disruption of the bundle leads to a slow motility phase with a weak propulsion. It is still not known whether the number of flagella represents an evolutionary adaptation toward optimizing bacterial navigation. We study the swimming dynamics of differentially flagellated Bacillus subtilis strains in a quasi-two-dimensional system. We find that decreasing the number of flagella N-f reduces the average turning angle between two successive run phases and enhances the run time and the directional persistence of the run phase. As a result, having fewer flagella is beneficial for long-distance transport and fast spreading while having a lot of flagella is advantageous for the processes that require a slower spreading, such as biofilm formation. We develop a two-state random walk model that incorporates spontaneous switchings between the states and yields exact analytical expressions for transport properties, in remarkable agreement with experiments. The results of numerical simulations based on our two-state model suggest that the efficiency of searching and exploring the environment is optimized at intermediate values of N-f. The optimal choice of N-f, for which the search time is minimized, decreases with increasing the size of the environment in which the bacteria swim. [less ▲]

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See detailFractionation of cellulose nanocrystals enhances liquid crystal ordering without promoting gelation
Honorato, C.; Lehr, Claudius Moritz UL; Schutz, C. et al

in Abstracts of Papers of the American Chemical Society (2018), 256

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See detailDetermination of the rheological properties of Matrigel for optimum seeding conditions in microfluidic cell cultures
Kane, K. I. W.; Moreno, E. Lucumi; Lehr, Claudius Moritz UL et al

in AIP ADVANCES (2018), 8(12),

Hydrogels are increasingly used as a surrogate extracellular matrix in three-dimensional cell culture systems, including microfluidic cell culture. Matrigel is a hydrogel of natural origin widely used in ... [more ▼]

Hydrogels are increasingly used as a surrogate extracellular matrix in three-dimensional cell culture systems, including microfluidic cell culture. Matrigel is a hydrogel of natural origin widely used in cell culture, particularly in the culture of stem cell-derived cell lines. The use of Matrigel as a surrogate extracellular matrix in microfluidic systems is challenging due to its biochemical, biophysical, and biomechanical properties. Therefore, understanding and characterising these properties is a prerequisite for optimal use of Matrigel in microfluidic systems. We used rheological measurements and particle image velocimetry to characterise the fluid flow dynamics of liquefied Matrigel during loading into a three-dimensional microfluidic cell culture device. Using fluorescence microscopy and fluorescent beads for particle image velocimetry measurements (velocity profiles) in combination with classical rheological measurements of Matrigel (viscosity versus shear rate), we characterised the shear rates experienced by cells in a microfluidic device for three-dimensional cell culture. This study provides a better understanding of the mechanical stress experienced by cells, during seeding of a mixture of hydrogel and cells, into three-dimensional microfluidic cell culture devices. (C) 2018 Author(s). [less ▲]

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See detailDiagnosing Tony Soprano, Norman Bates, Hercule Poirot, and Carol Beer through the DSM-5 AMPD
Bastiaens; Claes; Greiff, Samuel UL

in European Journal of Psychological Assessment (2018), 34

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See detailAdvancing the science of collaborative problem solving
Graesser, Art; Fiore, Steve; Greiff, Samuel UL et al

in Psychological Science in the Public Interest (2018), 19

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See detailWould you prefer your coefficients with a little bias, or rather with a lot of variance?
Fokkema, Marjolein; Greiff, Samuel UL

in European Journal of Psychological Assessment (2018), 34

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See detailFree and Unfree Labour in Brazilian Agriculture
Harnoncourt, Julia UL

Scientific Conference (2018)

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See detailUnfreie Arbeit. Trabalho escravo in der brasilianischen Landwirtschaft.
Harnoncourt, Julia UL

Book published by Promedia (2018)

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See detailFlouernimm a Sproochgeschicht
Mersch, Sam UL

Conference given outside the academic context (2018)

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See detailThe Effect of Morphosyntactic Training on Multilingual Fifth-Graders' Spelling in French
Bilici, Natalia UL; Ugen, Sonja UL; Fayol, Michel UL et al

in Applied Psycholinguistics (2018), 39(6), 1319-1343

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See detailWegenamen als Flurnamen
Mersch, Sam UL

Scientific Conference (2018)

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See detailFacing temptation: neural correlates effects of gambling availability during sport picture exposure
Brevers, Damien UL

in Journal of Behavioral Addictions (2018)

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See detailSeparating the influence of electric charges in magnetic force microscopy images of inhomogeneous metal samples
Arenas, Mónica P.; Martin Lanzoni, Evandro UL; Pacheco, Clara J. et al

in Journal of Magnetism and Magnetic Materials (2018), 446

In this study, we investigate artifacts arising from electric charges present in magnetic force microscopy images. Therefore, we use two austenitic steel samples with different microstructural conditions ... [more ▼]

In this study, we investigate artifacts arising from electric charges present in magnetic force microscopy images. Therefore, we use two austenitic steel samples with different microstructural conditions. Furthermore, we examine the influence of the surface preparation, like etching, in magnetic force images. Using Kelvin probe force microscopy we can quantify the charges present on the surface. Our results show that electrical charges give rise to a signature in the magnetic force microscopy, which is indistinguishable from a magnetic signal. Our results on two differently aged steel samples demonstrate that the magnetic force microscopy images need to be interpreted with care and must be corrected due to the influence of electrical charges present. We discuss three approaches, how to identify these artifacts – parallel acquisition of magnetic force and electric force images on the same position, sample surface preparation to decrease the presence of charges and inversion of the magnetic polarization in two succeeding measurement. [less ▲]

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