Ref HAL: hal-01996796_v1
DOI: 10.1101/509190
Exporter : BibTex | endNote
Résumé:

During embryogenesis of all vertebrates, haematopoietic stem/progenitor cells 16 (HSPCs) extrude from the aorta by a complex process named Endothelial-to-17 Haematopoietic Transition (EHT). HSPCs will then colonize haematopoietic organs 18 allowing haematopoiesis throughout adult life. The mechanism underlying EHT 19 including the role of each aortic endothelial cell within the global aorta dynamics 20 remains unknown. In the present study, we show for the first time that EHT involves the 21 remodelling of individual cells within a collective migration of endothelial cells which is 22 tightly orchestrated, resulting in HSPCs extrusion in the sub-aortic space without 23 compromising aorta integrity. By performing a cross-disciplinary study which combines 24 high resolution 4D imaging and theoretical analysis based on the concepts of classical 25 mechanics, we propose that this complex developmental process is dependent on 26 mechanical instabilities of the aorta preparing and facilitating the extrusion of HSPCs. 27 28 29 We dedicate this work to the memory of our friend and colleague, V. Lorman. 30 31 All rights reserved. No reuse allowed without permission. (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.

Ref HAL: hal-02010278_v1
Exporter : BibTex | endNote
Résumé:

How glasses break: A randomcritical point for yielding

Ref HAL: hal-01993807_v1
Ref Arxiv: 1804.08765
DOI: 10.1038/s41467-018-07978-1
WoS: 000454756900003
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
41 Citations
Résumé:

We numerically study the evolution of the vibrational density of states $D(\omega)$ of zero-temperature glasses when their kinetic stability is varied over an extremely broad range, ranging from poorly annealed glasses obtained by instantaneous quenches from above the onset temperature, to ultrastable glasses obtained by quenching systems thermalised below the experimental glass temperature. The low-frequency part of the density of states splits between extended and quasi-localized modes. Extended modes exhibit a boson peak crossing over to Debye behaviour ($D(\omega) \sim \omega^2$) at low-frequency, with a strong correlation between the two regimes. Quasi-localized modes instead obey $D(\omega) \sim \omega^4$, irrespective of the glass stability. However, the prefactor of this quartic law becomes smaller in more stable glasses, and the corresponding modes become more localized and sparser. Our work is the first numerical observation of quasi-localized modes in a regime relevant to experiments, and it establishes a direct connection between glass stability and soft vibrational motion in amorphous solids.

Commentaires: 8 pages, 6 figures.Nat. Commun. 10, 26 (2019), https://rdcu.be/bfkWJ

Ref HAL: hal-02152464_v1
Ref Arxiv: 1903.08179
DOI: 10.1016/j.nuclphysb.2019.114720
WoS: 000487935600018
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
3 Citations
Résumé:

Using Sklyanin's classical theory of integrable boundary conditions, we use the Hamiltonian approach to derive new integrable boundary conditions for the Ablowitz-Ladik model on the finite and half infinite lattice. In the case of half infinite lattice, the special and new emphasis of this paper is to connect directly the Hamiltonian approach, based on the classical $r$-matrix, with the zero curvature representation and B\"acklund transformation approach that allows one to implement a nonlinear mirror image method and construct explicit solutions. It is shown that for our boundary conditions, which generalise (discrete) Robin boundary conditions, a nontrivial extension of the known mirror image method to what we call {\it time-dependent boundary conditions} is needed. A careful discussion of this extension is given and is facilitated by introducing the notion of intrinsic and extrinsic picture for describing boundary conditions. This gives the specific link between Sklyanin's reflection matrices and B\"acklund transformations combined with folding, {\it in the case of non-diagonal reflection matrices}. All our results reproduce the known Robin boundary conditions setup as a special case: the diagonal case. Explicit formulas for constructing multisoliton solutions on the half-lattice with our time-dependent boundary conditions are given and some examples are plotted.

Ref HAL: hal-01926766_v1
Ref Arxiv: 1811.02763
DOI: 10.1063/1.5111292
WoS: 000483885000058
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
1 Citation
Résumé:

The $sl_N$-Onsager algebra has been introduced by Uglov and Ivanov in 1995. In this letter, a FRT presentation of the $sl_N$-Onsager algebra is given, its current algebra and commutative subalgebra are constructed. Certain quotients of the $sl_N$-Onsager algebra are then considered, which produce `classical' analogs of higher rank extensions of the Askey-Wilson algebra. As examples, the cases $N=3$ and $N=4$ are described in details.

Commentaires: 13 pages

Ref HAL: hal-01914524_v1
Ref Arxiv: 1810.10547
Ref INSPIRE: 1700428
DOI: 10.1103/PhysRevD.99.023503
WoS: 000454769300005
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
4 Citations
Résumé:

The growth of large scale structure is a battle between gravitational attraction and cosmic acceleration. We investigate the future behavior of cosmic growth under both general relativity (GR) and modified gravity during prolonged acceleration, deriving analytic asymptotic behaviors and showing that gravity generally loses and growth ends. We also note that the “why now” problem is equally striking when viewed in terms of the shutdown of growth. For many models inside GR the gravitational growth index γ also shows today as a unique time between constant behavior in the past and a higher asymptotic value in the future. Interestingly, while f(R) models depart in this respect dramatically from GR today and in the recent past, their growth indices are identical in the asymptotic future and past.

Ref HAL: hal-01852413_v2
Ref Arxiv: 1808.08479
DOI: 10.1007/s00220-019-03609-y
WoS: 000527910200005
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

By enforcing invariance under S-duality in type IIB string theory compactified on a Calabi-Yau threefold, we derive modular properties of the generating function of BPS degeneracies of D4-D2-D0 black holes in type IIA string theory compactified on the same space.Mathematically, these BPS degeneracies are the generalized Donaldson-Thomas invariants counting coherent sheaves with support on a divisor$\cal D$ , at the large volume attractor point. For $\cal D$ irreducible, this function is closely related to the elliptic genus of the superconformal field theory obtained by wrapping M5-brane on $\cal D$ and is therefore known to be modular. Instead, when $\cal D$ is the sum of $n$ irreducible divisors ${\cal D}_i$, we show that the generating function acquires a modular anomaly. We characterize this anomaly for arbitrary $n$ by providing an explicit expression for a non-holomorphic modular completion in terms of generalized error functions. As a result, the generating function turns out to be a (mixed) mock modular form of depth $n−1$.