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See detailAb initio calculations of the lattice dynamics of boron nitride nanotubes
Wirtz, Ludger UL; Rubio, A.; de la Concha, R. A. et al

in Physical Review B (2003), 68(4),

We present an extensive first-principles study of the phonons in boron nitride nanotubes using density functional perturbation theory in the local density approximation. Based on the nonsymmorphic rod ... [more ▼]

We present an extensive first-principles study of the phonons in boron nitride nanotubes using density functional perturbation theory in the local density approximation. Based on the nonsymmorphic rod-group symmetry of the tubes, the Raman- and infrared-active modes at the Gamma point of the one-dimensional Brillouin zone are evaluated. For zigzag and chiral nanotubes, the set of infrared-active modes is a subset of the Raman- active modes. In particular, the radial breathing mode is not only Raman but also infrared active. However, for armchair tubes, the sets of infrared-and Raman- active modes are disjoint. This may serve to spectroscopically distinguish between macroscopic samples of zigzag-chiral and armchair nanotubes. We present the frequencies of the active modes of zigzag, chiral, and armchair tubes as a function of the tube diameter and compare the results with the frequencies obtained by the zone-folding method, i.e., the rolling of a single hexagonal BN sheet into a tube. Except for the high-frequency tangential modes, the zone-folding results are in very good agreement with the ab initio calculations. The radial breathing mode frequency can be derived by folding a sheet of finite width. Finally, we show that the effects of bundling on the phonon frequencies are small. This demonstrates that the obtained results for isolated BN tubes may serve as a basis for an accurate assignment of phonon modes in spectroscopic measurements. [less ▲]

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See detailAb Initio Calculations of Ultrashort Carrier Dynamics in Two-Dimensional Materials: Valley Depolarization in Single-Layer WSe2
Molina-Sanchez, Alejandro UL; Sangalli, Davide; Wirtz, Ludger UL et al

in Nano Letters (2017), 17

In single-layer WSe2, a paradigmatic semiconducting transition metal dichalcogenide, a circularly polarized laser field can selectively excite electronic transitions in one of the inequivalent K± valleys ... [more ▼]

In single-layer WSe2, a paradigmatic semiconducting transition metal dichalcogenide, a circularly polarized laser field can selectively excite electronic transitions in one of the inequivalent K± valleys. Such selective valley population corresponds to a pseudospin polarization. This can be used as a degree of freedom in a “valleytronic” device provided that the time scale for its depolarization is sufficiently large. Yet, the mechanism behind the valley depolarization still remains heavily debated. Recent time–dependent Kerr experiments have provided an accurate way to visualize the valley dynamics by measuring the rotation of a linearly polarized probe pulse applied after a circularly polarized pump pulse. We present here a clear, accurate and parameter–free description of the valley dynamics. By using an atomistic, ab initio approach we fully disclose the elemental mechanisms that dictate the depolarization effects. Our results are in excellent agreement with recent time–dependent Kerr experiments. We explain the Kerr dynamics and its temperature dependence in terms of electron–phonon me- diated processes that induce spin–flip inter–valley transitions. [less ▲]

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See detailAb initio perspective on the Mollwo-Ivey relation for F centers in alkali halides
Tiwald, Paul; Karsai, Ferenc; Laskowski, Robert et al

in Physical Review. B: Condensed Matter and Materials Physics (2015), 92

We revisit the well-known Mollwo-Ivey relation that describes the ``universal'' dependence of the absorption energies of F-type color centers on the lattice constant a of alkali-halide crystals, E-abs ... [more ▼]

We revisit the well-known Mollwo-Ivey relation that describes the ``universal'' dependence of the absorption energies of F-type color centers on the lattice constant a of alkali-halide crystals, E-abs proportional to a(-n). We perform both state-of-the-art ab initio quantum chemistry and post-DFT calculations of F-center absorption spectra. By ``tuning'' independently the lattice constant and the atomic species we show that the scaling with the lattice constant alone 2 in agreement with the ``particle-in-the-box'' model. Keeping the lattice constant fixed and changing the atomic species enables us to quantify the ion-size effects which are shown to be responsible for the exponent n approximate to 1.8. [less ▲]

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See detailAb-initio study of the temperature effects on the optical properties of transition metal dichalcogenides
Molina-Sanchez, Alejandro UL; Palummo, Maurizia; Marini, Andrea et al

Scientific Conference (2015, March 05)

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See detailL'abbaye Neumunster - et tout un ancien quartier urbain
Pauly, Michel UL

in Abbaye de Neumunster (2004)

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See detailThe abbot and the Monastic Community in the Gaelic Churches, 550 to 800
Pettiau, Hérold UL

in Glyn S. Burgess; Strijbosch, Clara (Eds.) The Brendan Legend. Texts and Versions (2006)

This chapters deals with aspects of the organisation of monastic communities in the Gaelic Churches from 550 to 800. It focusses on the role of the head of the community, the abbot, regarding general ... [more ▼]

This chapters deals with aspects of the organisation of monastic communities in the Gaelic Churches from 550 to 800. It focusses on the role of the head of the community, the abbot, regarding general questions of monastic discipline, organising of the liturgical life of the community, regulation of the diet and of the food provision in the community. [less ▲]

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See detailABCA1 regulatory variants influence coronary artery disease independent of effects on plasma lipid levels
Zwarts, K. Y.; Clee, S. M.; Zwinderman, A. H. et al

in Clinical Genetics (2002), 61(2), 115-125

The authors have previously shown that individuals heterozygous for ABCA1 mutations have decreased high density lipoprotein cholesterol, increased triglycerides and an increased frequency of coronary ... [more ▼]

The authors have previously shown that individuals heterozygous for ABCA1 mutations have decreased high density lipoprotein cholesterol, increased triglycerides and an increased frequency of coronary artery disease (CAD), and that single nucleotide polymorphisms (SNPs) in the coding region of the ABCA1 gene significantly impact plasma lipid levels and the severity of CAD in the general population. They have now identified several SNPs in non-coding regions of ABCA1 which may be important for the appropriate regulation of ABCA1 expression (i.e. in the promoter, intron 1 and the 5′ untranslated region), and have examined the phenotypic effects of these SNPs in the REGRESS population. Out of 12 SNPs, four were associated with a clinical outcome. A threefold increase in coronary events with an increased family history of CAD was evident for the G-191C variant. Similarly, the C69T SNP was associated with a twofold increase in events. In contrast, the C-17G was associated with a decrease in coronary events and the InsG319 was associated with less atherosclerosis. For all these SNPs, the changes in atherosclerosis and CAD occurred without detectable changes in plasma lipid levels. These data suggest that common variation in non-coding regions of ABCA1 may significantly alter the severity of atherosclerosis, without necessarily influencing plasma lipid levels. [less ▲]

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See detailABCDE Tutorial LuxLogAI 2018 - Default entailment course
Weydert, Emil UL

Scientific Conference (2018)

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See detailAbdications of Sovereignty in State Action and Horizontal Effect Jurisprudence
Van Der Walt, Johan Willem Gous UL

in Kahana, Tsvi; Scolnicov, Anat (Eds.) Boundaries of State, Boundaries of Rights: Human Rights, Private Actors, and Positive Obligations (2016)

This article argues that different regimes of horizontal effect adjudication invariably turn on different attitudes to state sovereignty. Aversions to horizontal effect are usually a reflection of an ... [more ▼]

This article argues that different regimes of horizontal effect adjudication invariably turn on different attitudes to state sovereignty. Aversions to horizontal effect are usually a reflection of an apprehension regarding state sovereignty (understood as a threat to liberty) whereas endorsements of horizonal effect usually reflect a positive regard for state sovereingty (as a condition for liberty). [less ▲]

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See detailAbel-Preis an Mathematiker Lennart Carleson
Molitor-Braun, Carine UL; Mortini, Raymond

Article for general public (2006)

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See detailAbel-Preis für Mathematiker Mischa Gromov
Mortini, Raymond; Schlichenmaier, Martin UL

Article for general public (2009)

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See detailAbelian varieties over finitely generated fields and the conjecture of Geyer and Jarden on torsion
Arias De Reyna Dominguez, Sara UL; Gajda, Wojciech; Petersen, Sebastian

in Mathematische Nachrichten (2013), 286(13), 1269-1286

In this paper we prove the Geyer-Jarden conjecture on the torsion part of the Mordell-Weil group for a large class of abelian varieties defined over finitely generated fields of arbitrary characteristic ... [more ▼]

In this paper we prove the Geyer-Jarden conjecture on the torsion part of the Mordell-Weil group for a large class of abelian varieties defined over finitely generated fields of arbitrary characteristic. The class consists of all abelian varieties with big monodromy, i.e., such that the image of Galois representation on l-torsion points, for almost all primes l, contains the full symplectic group. [less ▲]

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See detailAbelian varieties over number fields, tame ramification and big Galois image
Arias De Reyna Dominguez, Sara UL; Kappen, Christian

in Mathematical Research Letters (2013), 20(01), 1-17

Given a natural number n ≥ 1 and a number field K, we show the existence of an integer l_0 such that for any prime number l ≥ l_0 , there exists a finite extension F/K, unramified in all places above l ... [more ▼]

Given a natural number n ≥ 1 and a number field K, we show the existence of an integer l_0 such that for any prime number l ≥ l_0 , there exists a finite extension F/K, unramified in all places above l, together with a principally polarized abelian variety A of dimension n over F such that the resulting l-torsion representation ρ_{A,l} : G_F → GSp(A[l]) is surjective and everywhere tamely ramified. In particular, we realize GSp_{2n}(F_l) as the Galois group of a finite tame extension of number fields F' /F such that F is unramified above l. [less ▲]

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See detailAbelian varieties with tame and surjective Galois representations
Arias De Reyna Dominguez, Sara UL

Scientific Conference (2013, August)

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See detailAberrant splicing of the tumor suppressor CYLD promotes the development of chronic lymphocytic leukemia via sustained NF-kappaB signaling.
Hahn, M.; Burckert, J.-P.; Luttenberger, C. A. et al

in Leukemia (2017), 32(1), 72-82

The pathogenesis of chronic lymphocytic leukemia (CLL) has been linked to constitutive NF-kappaB activation but the underlying mechanisms are poorly understood. Here we show that alternative splicing of ... [more ▼]

The pathogenesis of chronic lymphocytic leukemia (CLL) has been linked to constitutive NF-kappaB activation but the underlying mechanisms are poorly understood. Here we show that alternative splicing of the negative regulator of NF-kappaB and tumor suppressor gene CYLD regulates the pool of CD5(+) B cells through sustained canonical NF-kappaB signaling. Reinforced canonical NF-kappaB activity leads to the development of B1 cell-associated tumor formation in aging mice by promoting survival and proliferation of CD5(+) B cells, highly reminiscent of human B-CLL. We show that a substantial number of CLL patient samples express sCYLD, strongly implicating a role for it in human B-CLL. We propose that our new CLL-like mouse model represents an appropriate tool for studying ubiquitination-driven canonical NF-kappaB activation in CLL. Thus, inhibition of alternative splicing of this negative regulator is essential for preventing NF-kappaB-driven clonal CD5(+) B-cell expansion and ultimately CLL-like disease. [less ▲]

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See detailThe ability to read numbers: A universal measure?
Tymms, Peter; Aleksic, Gabrijela UL; Bartholo, Tiago et al

in AERA (2018)

This study tests the hypothesis that there is a single pathway for the order in which children learn to identify numbers. Although a prime facie case can be made, systematic variation might be expected ... [more ▼]

This study tests the hypothesis that there is a single pathway for the order in which children learn to identify numbers. Although a prime facie case can be made, systematic variation might be expected because of teaching, or language of instruction, or country of origin. This study concludes that such variations are minor and that the pathway that children follow when learning to identify numbers follows the same pattern across different groups. This finding is significant in furthering our knowledge of children’s early mathematics development; it suggests that there is a universal developmental scale from which the diverse aspects of mathematical development can be viewed. This lays the foundation for international comparisons of the mathematical development of young children. [less ▲]

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See detailAblenkung. Kafkas Idee des literarischen Suizids
Mein, Georg UL

in Zeitschrift für Deutsche Philologie (2003), (2), 266-286

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See detailL'abolition de l'esclavage fête ses 130 ans au Brésil...
Santana, Dominique UL

Article for general public (2018)

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See detailAbolition de l’exequatur et présomption de compatibilité avec les droits fondamentaux
Cuniberti, Gilles UL

in Revue Critique de Droit International Privé (2014)

Detailed reference viewed: 14 (1 UL)