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PMID 31704936
DOI: 10.1038/s41467-019-13010-x
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6 Citations

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Ref Arxiv: 1903.09108
DOI: 10.1103/PhysRevLett.123.175501
WoS: WOS:000491998300008
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Résumé:

Ultrastable vapor-deposited glasses display uncommon material properties. Most remarkably, upon heating they are believed to melt via a liquid front that originates at the free surface and propagates over a mesoscopic crossover length, before crossing over to bulk melting. We combine swap Monte Carlo with molecular dynamics simulations to prepare and melt isotropic amorphous films of unprecedendtly high kinetic stability. We are able to directly observe both bulk and front melting, and the crossover between them. We measure the front velocity over a broad range of conditions, and a crossover length scale that grows to nearly $400$ particle diameters in the regime accessible to simulations. Our results disentangle the relative roles of kinetic stability and vapor deposition in the physical properties of stable glasses.

Commentaires: 7 pages, 6 figures; accepted for publication in Phys. Rev. Lett. Réf Journal: Phys. Rev. Lett. 123, 175501 (2019)

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Controlled motion and positioning of colloids and macromolecular complexes in a fluid, as well as catalytic particles in active environments, are fundamental processes in physics, chemistry and biology. Here we focus on an active biological system for which precise experimental results are available. Our work is fully inspired by studies of one of the most widespread and ancient mechanisms of liquid phase macromolecular segregation and positioning known in nature: bacterial DNA segregation systems. Efficient bacterial chromosome segregation typically requires the coordinated action of a three-component, fueled by adenosine triphosphate machinery called the partition complex. We can distinguish two steps: (i) a process of phase transition [2,3] to built a membraneless region of high protein concentration (partition complex) (ii) the action of molecular motor action upon the complex to create a chemical force. We mainly present a phenomenological model of reaction-diffusion for two families of proteins [1] describing the step (ii), the dynamics of the segregation of paired chromosomes. We also discuss the step (i) the phase transition mechanism giving rise to macromolecular assembly of proteins. Our predictions are compared to Super Resolution microscopy and microbiology experiments [1,2,3].[1] Walter J.-C., Dorignac J., Lorman V., Rech J., Bouet J.-Y., Nollmann M., Palmeri J., Parmeggiani A. and Geniet F., Phys. Rev. Lett. 119, 028101 (2017).[2] Debaugny R., Sanchez A., Rech J., Labourdette D., Dorignac J., Geniet F., Palmeri J., Parmeggiani A., Boudsocq, Leberre V., Walter* J.-C. and Bouet* J.-Y Mol. Syst. Biol. 14, e8516 (2018)[3] David G., Walter J.-C., Broedersz C., Dorignac J., Geniet F., Parmeggiani A., Walliser N.-O. and Palmeri J., submitted to Phys. Rev. Lett. [arXiv/1811.09234] (2019).

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Ref Arxiv: 1908.08363
Ref INSPIRE: 1750592
DOI: 10.1103/PhysRevD.100.114006
WoS: 000499979100004
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2 Citations
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We apply the renormalization group optimized perturbation theory (RGOPT) to evaluate the QCD (matter) pressure at the two-loop level considering three flavors of massless quarks in a dense and cold medium. Already at leading order (αs0), which builds on the simple one loop (RG resummed) term, our technique provides a nontrivial nonperturbative approximation which is completely renormalization group invariant. At the next-to-leading order the comparison between the RGOPT and the perturbative QCD predictions shows that the former method provides results which are in better agreement with the state-of-the-art higher order perturbative results, which include a contribution of order αs3ln2αs. At the same time one also observes that the RGOPT predictions are less sensitive to variations of the arbitrary MS¯ renormalization scale than those obtained with perturbative QCD. These results indicate that the RGOPT provides an efficient resummation scheme which may be considered as an alternative to lattice simulations at high baryonic densities.

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DOI: 10.1103/PhysRevB.100.081301
WoS: WOS:000478993500002
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The dynamic coupling between spin and charge currents in nonmagnetic conductors is considered. As a consequence of this coupling, the spin dynamics is directly reflected in the electrical impedance of the sample, with a relevant frequency scale defined by spin relaxation and spin diffusion. This allows the observation of the electron spin resonance by purely electrical measurements.