« Virial » pressure of the classical one-component plasma

Application of the virial theorem to a Coulomb system of N particles neutralized by a continuous background, leads quite naturally to the definition of a « virial » kinetic pressure for the system of particles, which is fundamentally positive. This definition is related, in a particular case, to the thermodynamic one used in previous works, which has the drawback to give negative values for sufficiently strong coupling.En appliquant le théorème du viriel à un système coulombien de N particules neutralisées par un fond continu, on définit très naturellement une pression cinétique « virielle » du système de particules, qui est une quantité essentiellement positive. Le lien est fait, dans un cas particulier, avec la définition thermodynamique de la pression utilisée dans les travaux précédents, qui a l'inconvénient de donner des valeurs négatives quand le paramètre de couplage est suffisamment grand

Structures singulières non linéaires pour les fluides non collisionnels de l'espace des phases

We study the solutions of the Vlasov-Poisson one dimensional system both for a single repulsive species (beam) and for an electron plasma in presence of a motionless ionic background. An ansatz on the form of the distribution function leads to a solution with a rod structure in phase space. This was already obtained by self-similarity arguments in the beam case. Here we can generalize the initial conditions of the rod and treat both beam and plasma problems. The introduction of the concept of contamination enables the rod to be cut to get rid of non physical boundary conditions but it introduces a time limitation on the validity of the solution for some (or all) particles. As long as particles are not contaminated an invariant can be obtained. Computer simulations support this theory very well.On étudie les solutions du système unidimensionnel de Vlasov-Poisson à la fois pour une espèce répulsive (faisceau) et pour un plasma d'électrons en présence d'un fond neutralisant immobile et continu d'ions. Un ansatz sur la structure de la fonction de distribution introduit une solution ayant la forme d'un bâton dans l'espace des phases - solution déjà obtenue dans le cas du faisceau à l'aide d'arguments de self-similarité. Ici nous pouvons généraliser les conditions initiales du bâton et traiter à la fois des problèmes de faisceau et de plasma. Le concept de contamination permet de limiter le bâton et d'éliminer les conditions aux limites non physiques, mais introduit une limitation sur le temps de validité de la solution pour une partie (ou la totalité) des particules. Tant que les particules ne sont pas contaminées un invariant exact peut être obtenu. Des simulations numériques illustrent très bien cette théorie

Practical Multicore Extension of Functionally and Temporally Correct Real-Time Simulation for Automotive Systems

© 2020, Springer Nature Switzerland AG.Existing simulation methods cannot provide functionally and temporally correct simulations for the cyber-side of automotive systems since they do not correctly model temporal behaviours such as varying execution times and task preemptions. To address such limitations, our previous work proposes a novel simulation technique that guarantees the functional and temporal simulation correctness. However, the simulation technique is designed assuming a single core simulator. In this work, we extend the single core simulator targeting a multicore simulator to enhance the simulation capacity. In this multicore extension, a major challenge is the inter-core interferences in a multicore environment, which causes unpredictability of simulated job execution times, which in turn makes it hard to model the timings of the real cyber-side of an automotive system. To overcome the challenge, this paper empirically analyzes the inter-core interferences for typical automotive workloads and proposes a practical multicore extension approach, which can still provide a functionally and temporally correct simulation, without using complex inter-core isolation mechanisms. Our experimental study shows that the proposed multicore extension approach can significantly improve the simulation capacity over the previous single core simulator while still preserving simulation correctness.N

Secondary-structure characterization by far-UV CD of highly purified uncoupling protein 1 expressed in yeast.

The rat UCP1 (uncoupling protein 1) is a mitochondrial inner-membrane carrier involved in energy dissipation and heat production. We expressed UCP1 carrying a His6 epitope at its C-terminus in Saccharomyces cerevisiae mitochondria. The recombinant-tagged UCP1 was purified by immobilized metal-ion affinity chromatography to homogeneity (>95%). This made it suitable for subsequent biophysical characterization. Fluorescence resonance energy transfer experiments showed that n-dodecyl-beta-D-maltoside-solubilized UCP1-His6 retained its PN (purine nucleotide)-binding capacity. The far-UV CD spectrum of the functional protein clearly indicated the predominance of alpha-helices in the UCP1 secondary structure. The UCP1 secondary structure exhibited an alpha-helical degree of approx. 68%, which is at least 25% higher than the previously reported estimations based on computational predictions. Moreover, the helical content remained unchanged in free and PN-loaded UCP1. A homology model of the first repeat of UCP1, built on the basis of X-ray-solved close parent, the ADP/ATP carrier, strengthened the CD experimental results. Our experimental and computational results indicate that (i) alpha-helices are the major component of UCP1 secondary structure; (ii) PN-binding mechanism does not involve significant secondary-structure rearrangement; and (iii) UCP1 shares similar secondary-structure characteristics with the ADP/ATP carrier, at least for the first repeat