On the large scale behavior of super-Brownian motion in three dimensions with a single point source

In a recent work, Fleischmann and Mueller (2004) showed the existence of a super-Brownian motion in R^d, d=2,3, with extra birth at the origin. Their construction made use of an analytical approach based on the fundamental solution of the heat equation with a one point potential worked out by Albeverio et al. (1995). The present note addresses two properties of this measure-valued process in the three-dimensional case, namely the scaling of the process and the large scale behavior of its mean

Catalytic superprocesses, collision local times and non-linear boundary value problems

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Product structure of heat phase space and branching Brownian motion

A generical formalism for the discussion of Brownian processes with non-constant particle number is developed, based on the observation that the phase space of heat possesses a product structure that can be encoded in a commutative unit ring. A single Brownian particle is discussed in a Hilbert module theory, with the underlying ring structure seen to be intimately linked to the non-differentiability of Brownian paths. Multi-particle systems with interactions are explicitly constructed using a Fock space approach. The resulting ring-valued quantum field theory is applied to binary branching Brownian motion, whose Dyson-Schwinger equations can be exactly solved. The presented formalism permits the application of the full machinery of quantum field theory to Brownian processes.Comment: 32 pages, journal version. Annals of Physics, N.Y. (to appear

Association between conventional risk factors and different ultrasound-based markers of atherosclerosis at carotid and femoral levels in a middle-aged population

Ultrasound detection of sub-clinical atherosclerosis (ATS) may help identify individuals at high cardiovascular risk. Most studies evaluated intima-media thickness (IMT) at carotid level. We compared the relationships between main cardiovascular risk factors (CVRF) and five indicators of ATS (IMT, mean and maximal plaque thickness, mean and maximal plaque area) at both carotid and femoral levels. Ultrasound was performed on 496 participants aged 45-64years randomly selected from the general population of the Republic of Seychelles. 73.4% participants had ≥1 plaque (IMT thickening ≥1.2mm) at carotid level and 67.5% at femoral level. Variance (adjusted R2) contributed by age, sex and CVRF (smoking, LDL-cholesterol, HDL-cholesterol, blood pressure, diabetes) in predicting any of the ATS markers was larger at femoral than carotid level. At both carotid and femoral levels, the association between CVRF and ATS was stronger based on plaque-based markers than IMT. Our findings show that the associations between CVRF and ATS markers were stronger at femoral than carotid level, and with plaque-based markers rather than IMT. Pending comparison of these markers using harder cardiovascular endpoints, our findings suggest that markers based on plaque morphology assessed at femoral artery level might be useful cardiovascular risk predictor

Apport de la simulation numérique à l'essai de Small Punch Test

Lors de l’essai de Small Punch Test (SPT) (essai de micro emboutissage d’un disque d’épaisseur 0,5 mm et de diamètre 8,9 mm), le matériau est sollicité en contraintes bi-axiales, déformé plastiquement jusqu’à fissuration et, rompu. Des essais de Small Punch Test, réalisés sur l’acier inoxydable 316L, montrent le comportement ductile de l’acier à partir des courbes d’évolution de la force exercée sur l’échantillon en fonction du déplacement. Des essais interrompus couplés à une analyse par microscopie électronique à balayage mettent en évidence l’amorçage de la fissuration et une rupture ductile. Parallèlement, nous avons développé une simulation numérique de l’essai SPT par éléments finis à l’aide du solveur 2D du logiciel implicite FORGE2005. La plasticité des matériaux est modélisée par une relation de type Hollomon ; l’implémentation d’un critère de rupture permet de mettre en évidence l’apparition de la fissuration. La simulation permet de montrer l’évolution des contraintes et des déformations au cours de l’essai, et la propagation de fissures dans l’échantillon

Apport de la simulation numérique à l'essai de Small Punch Test

Lors de l’essai de Small Punch Test (SPT) (essai de micro emboutissage d’un disque d’épaisseur 0,5 mm et de diamètre 8,9 mm), le matériau est sollicité en contraintes bi-axiales, déformé plastiquement jusqu’à fissuration et, rompu. Des essais de Small Punch Test, réalisés sur l’acier inoxydable 316L, montrent le comportement ductile de l’acier à partir des courbes d’évolution de la force exercée sur l’échantillon en fonction du déplacement. Des essais interrompus couplés à une analyse par microscopie électronique à balayage mettent en évidence l’amorçage de la fissuration et une rupture ductile. Parallèlement, nous avons développé une simulation numérique de l’essai SPT par éléments finis à l’aide du solveur 2D du logiciel implicite FORGE2005. La plasticité des matériaux est modélisée par une relation de type Hollomon ; l’implémentation d’un critère de rupture permet de mettre en évidence l’apparition de la fissuration. La simulation permet de montrer l’évolution des contraintes et des déformations au cours de l’essai, et la propagation de fissures dans l’échantillon

A quantum algorithm for solving open system dynamics on quantum computers using noise

In this paper we present a quantum algorithm that uses noise as a resource. The goal of our quantum algorithm is the calculation of operator averages of an open quantum system evolving in time. Selected low-noise system qubits and noisy bath qubits represent the system and the bath of the open quantum system. All incoherent qubit noise can be mapped to bath spectral functions. The form of the spectral functions can be tuned digitally, allowing for the time evolution of a wide range of open-system models at finite temperature. We study the feasibility of this approach with a focus on the solution of the spin-boson model and assume intrinsic qubit noise that is dominated by damping and dephasing. We find that classes of open quantum systems exist where our algorithm performs very well, even with gate errors as high as 1%. In general the presented algorithm performs best if the system-bath interactions can be decomposed into native gates.Comment: 19 pages, 8 figures in total: 10 pages main text with 7 figure

Virus-Like Particles Are Efficient Tools for Boosting mRNA-Induced Antibodies.

mRNA based vaccines against COVID-19 have proven most successful at keeping SARS-CoV-2 pandemic at bay in many countries. Recently, there is an increased interest in heterologous prime-boost vaccination strategies for COVID-19 to maintain antibody responses for the control of continuously emerging SARS-CoV-2 variants of concern (VoCs) and to overcome other obstacles such as supply shortage, costs and reduced safety issues or inadequatly induced immune-responses. In this study, we investigated the antibody responses induced by heterologous prime-boost with vaccines based on mRNA and virus-like particles (VLPs). The VLP-based mCuMVTT-RBM vaccine candidate and the approved mRNA-1273 vaccine were used for this purpose. We find that homologous prime boost regimens with either mRNA or VLP induced high levels of high avidity antibodies. Optimal antibody responses were, however, induced by heterologous regimens both for priming with mRNA and boosting with VLP and vice versa, priming with VLP and boosting with mRNA. Thus, heterologous prime boost strategies may be able to optimize efficacy and economics of novel vaccine strategies