Ref HAL: hal-04609830_v1
Ref Arxiv: 2406.02531
Ref INSPIRE: 2794447
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

We construct a hybrid-inflation model where the inflaton potential is generated radiatively, as gauge symmetries guarantee it to be accidentally flat at tree level. The model can be regarded as a small-field version of Natural Inflation, with inflation ending when the mass of a second scalar, the waterfall field, turns tachyonic. This provides a minimal, robust realisation of hybrid inflation, which predicts specific correlations among CMB observables. Tachyonic preheating leads to the production of gravitational waves which, for a low inflationary scale, might be detected by upcoming experiments. Simple variations of the model can give rise to topological defects, such as unstable domain walls. Their dynamics produces a stochastic gravitational-wave background, which can be compatible with the recent detection by pulsar timing arrays.

Ref HAL: hal-04609427_v1
DOI: 10.1021/acs.jpcc.4c01695
Exporter : BibTex | endNote
Résumé:

Since the introduction of hybrid van der Waals heterostructures (h-vdWHs) for device architecture development, many vertically staked organic two-dimensional materials have been investigated in order to control transport properties. This article introduces a novel h-vdWH that achieves periodicinteraction by the development of a superlattice. We describe a complete investigation of the diphenyl-functionalized p-benzoquinonemonoimine zwitterion on highly oriented pyrolytic graphiteand monolayer graphene using high-resolution scanning tunneling microscopy images and numerical simulations. The molecular phase on both substrates exhibits a structurally identical antiparallel dipole alignment in a head-to-tail dimer configuration. Density functional theory calculations reveal that this molecularadsorption induces a local dipole at the graphene interface due to the rearrangement of the electron density distribution.

Ref HAL: hal-04604013_v1
Exporter : BibTex | endNote
Résumé:

Recent advancements in experimental fluorescence microscopy have revolutionized our ability to accurately determine the three-dimensional physical location of multiple chromosomal regions with a resolution down to 50 nm. In this study, we leverage publicly available microscopy data focusing on loci from human Chr21 obtained through multiplexed fluorescence in situ hybridization (mFISH) techniques across various cell lines and treatments. Inspired by models from polymer physics, our analysis delves into the distance distributions between different tagged regions, aiming to elucidate the chromatin's conformational arrangements. Our findings reveal the presence of at least two distinct conformational arrangements, which we term phase α and phase β, coexisting at any given genomic site. These phases exhibit contrasting scaling behaviors: phase α aligns with a crumpled globule model, while phase β suggests a confined yet more extended conformation resembling a looped domain. The identification of these distinct phases not only sheds light on the multifaceted nature of chromatin topology but also offers insights into the impact of cellular context and/or treatments on chromatin structure.

DOI: 10.1038/s41467-024-48176-6

DOI: 10.1088/1742-5468/ad17b6

Ref HAL: hal-04603644_v1
Ref Arxiv: 2405.14523
Ref INSPIRE: 2789653
DOI: 10.48550/arXiv.2405.14523
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

We study the Casimir-Lifshitz force (CLF) between a gold plate and a graphene-covered dielectric grating. Using a scattering matrix (S-matrix) approach derived from the Fourier Modal Method (FMM), we find a significant enhancement in the CLF as compared to a mere dielectric slab coated with graphene, over a wide range of temperatures. Additionally, we demonstrate that the CLF depends strongly on the chemical potential of graphene, with maximal effects observed at lower filling fractions. Finally, we analyse the Casimir force gradient between a gold sphere and a graphene-coated dielectric grating, highlighting potential avenues for experimental measurements.

Ref HAL: hal-04603641_v1
Ref Arxiv: 2306.07172
DOI: 10.1103/PhysRevLett.132.218301
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

We study two models of overdamped self-propelled disks in two dimensions, with and without aligning interactions. Both models support active mesoscale flows, leading to chaotic advection and transport over large length scales in their homogeneous dense fluid states, away from dynamical arrest. They form streams and vortices reminiscent of multiscale flow patterns in turbulence. We show that the characteristics of these flows do not depend on the specific details of the active fluids, and result from the competition between crowding effects and persistent propulsions. This observation suggests that dense active suspensions of self-propelled particles present a type of “active turbulence” distinct from collective flows reported in other types of active systems. Published by the American Physical Society 2024