Asymptotic behaviour and optimal word size for exact and approximate word matches between random sequences

The present work is concerned with a fast and accurate sequence comparison method: the count of the number of words of length k letters shared by two sequences, also known as the D2 statistic. We link recent theoretical advances in the characterization of D2 asymptotic distributions with applications to biological sequences. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Multifrequency EPR and redox reactivity investigations of a bis(mu-thiolato)-dicopper(II,II) complex

From a new tripodal ligand [N2SS'H] with mixed N, S(thioether), and S(thiolate) donor set, the corresponding bis(mu-thiolato)dicopper(II) complex has been prepared and characterized. X-ray crystallographic analysis of the complex [Cu2(N2SS')2](ClO4)2.C4H10O (1) demonstrates that the two five-coordinated Cu atoms are bridged by two thiolates leading to a nearly planar Cu2S2 core with a Cu1...Cu1* distance of 3.418(8) A and a large bridging angle Cu1S1Cu1* of 94.92 degrees. X-band (10 GHz), Q-band (34 GHz), and F-Band (115 GHz) EPR spectra of 1 are consistent with a weakly coupled dicopper(II,II) center attributed to an S = 1 state. Simulations for the three frequencies are obtained with a unique set of electronic parameters. The mean values of the spin Hamiltonian parameters for 1 are D = 0.210(3) cm(-1), E = 0.0295(5) cm(-1), |E/D| = 0.140, gx = 2.030(2), gy = 2.032(2), gz = 2.128(2). The electrochemical one-electron reduction of 1 generates the mixed-valent CuIICuI species. EPR and UV-vis spectra are consistent with a type I localized mixed-valent species, while dinuclear CuA centers of native cytochrome c oxidase (CcO)1-3 or nitrous oxide reductase (N2OR)4 have a delocalized CuIICuI mixed-valent state. After reoxidation of the CuIICuI species, the initial complex 1 is regenerated through a reversible interconversion process.     

Chironomic stylization of intonation

Intonation stylization is studied using "chironomy," i.e., the analogy between hand gestures and prosodic movements. An intonation mimicking paradigm is used. The task of the ten subjects is to copy the intonation pattern of sentences with the help of a stylus on a graphic tablet, using a system for real-time manual intonation modification. Gestural imitation is compared to vocal imitation of the same sentences (seven for a male speaker, seven for a female speaker). Distance measures between gestural copies, vocal imitations, and original sentences are computed for performance assessment. Perceptual testing is also used for assessing the quality of gestural copies. The perceptual difference between natural and stylized contours is measured using a mean opinion score paradigm for 15 subjects. The results indicate that intonation contours can be stylized with accuracy by chironomic imitation. The results of vocal imitation and chironomic imitation are comparable, but subjects show better imitation results in vocal imitation. The best stylized contours using chironomy seems perceptually indistinguishable or almost indistinguishable from natural contours, particularly for female speech. This indicates that chironomic stylization is effective, and that hand movements can be analogous to intonation movements.     

Straightforward high-order numerical dissipation via the viscous term for direct and large eddy simulation

In this short note, we show how to use a highly accurate finite-difference scheme to compute second derivatives in the Navier–Stokes equations while ensuring targeted numerical dissipation. This approach, essentially non conservative, is shown to be close to an upwind method and is straightforward to implement with a negligible computational extra cost. The benefit offered by the resulting discrete operator is illustrated for the direct computation of sound in aeroacoustics and in the more general context of large-eddy simulation through connections with hyperviscosity and spectral vanishing viscosity.     

Total synthesis of amorfrutin A via a palladium-catalyzed migratory prenylation–aromatization sequence

The total synthesis of amorfrutin A, a prenyl bibenzyl natural product has been achieved in five steps from 2,2,6-trimethyl-4H-1,3-dioxin-4-one. The key step of the synthesis is an efficient palladium(0)-catalyzed decarboxylative prenylation migration and aromatization sequence.     

Incompact3d: A powerful tool to tackle turbulence problems with up to O(105) computational cores

Understanding the nature of complex turbulent flows remains one of the most challenging problems in classical physics. Significant progress has been made recently using high performance computing, and computational fluid dynamics is now a credible alternative to experiments and theories in order to understand the rich physics of turbulence. In this paper, we present an efficient numerical tool called Incompact3d that can be coupled with massive parallel platforms in order to simulate turbulence problems with as much complexity as possible, using up to O(10⁵) computational cores by means of direct numerical simulation (DNS). DNS is the simplest approach conceptually to investigate turbulence, featuring the highest temporal and spatial accuracy and it requires extraordinary powerful resources. This paper is an extension of Laizet et al.(Comput. Fluids 2010; 39 (3):471–484) where the authors proposed a strategy to run DNS with up to 1024 computational cores. Copyright © 2010 John Wiley & Sons, Ltd.     

Spectral conditions for admissibility and observability of wave systems: applications to finite element schemes

In this article, we derive uniform admissibility and observability properties for the finite element space semi-discretizations of , where A ₀ is an unbounded self-adjoint positive definite operator with compact resolvent. To address this problem, we present a new spectral approach based on several spectral criteria for admissibility and observability of such systems. Our approach provides very general admissibility and observability results for finite element approximation schemes of , which stand in any dimension and for any regular mesh (in the sense of finite elements). Our results can be combined with previous works to derive admissibility and observability properties for full discretizations of . We also present applications of our results to controllability and stabilization problems. The author was partially supported by the “Agence Nationale de la Recherche” (ANR), Project C-QUID, number BLAN-3-139579.     

Diviseurs Des Nombres Ellipséphiques

Les propriétés multiplicatives des nombres ellipséphiques peuvent être obtenues à l’aide des moments de la série génératrice de cette suite. Nous donnons des estimations précises pour les grands moments par deux méthodes distinctes: l’une combinatoire fournit un résultat précis dans le cas réputé le plus difficile des nombres n’utilisant que les 0 et les 1; la seconde purement analytique fournit un résultat sans condition sur les chiffres.

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A New Look at Mourre’s Commutator Theory

Mourre’s commutator theory is a powerful tool to study the continuous spectrum of self-adjoint operators and to develop scattering theory. We propose a new approach of its main result, namely the derivation of the limiting absorption principle (LAP) from a so called Mourre estimate. We provide a new interpretation of this result. Received: September 20, 2006. Revised: February 1, 2007.     

Synthesis of unsymmetrical saturated or diacetylenic cationic bolaamphiphiles

This work presents the synthesis of novel unsymmetrical bolaamphiphiles bearing a sugar residue and a cationic glycine betaine moiety connected to both ends of a C₂₂ or C₃₂ oligomethylene bridging chain possessing or not a diacetylenic unit. Preliminary transmission electron microscopy (TEM) studies revealed the polymorphism of these bola lipids with regard to their self-assembled morphologies in water depending on the presence or not of the diacetylenic functionality and on alkyl chain length.