Truncated Infinitesimal Shifts, Spectral Operators and Quantized Universality of the Riemann Zeta Function
Hafedh HERICHI, Michel L. LAPIDUS
- 2013-05-15 (M/13/12)
mRNA diffusion as a mechanism of morphogenesis in Drosophila early development
- 2013-04-29 (M/13/11)
In Drosophila early development, bicoid mRNA of maternal origin is deposited in one of the poles of the egg, determining the anterior tip of the embryo and the position of the head of larvae. The deposition of mRNAs is done during oogenesis by the mother ovary cells and is transported into the oocyte along microtubules. Initially, the oocyte has only one nucleus, but after fertilization and deposition of the egg, nuclear duplication by mitosis is initiated without the formation of cellular membranes. During the first 14 nuclear divisions of the developing embryo, bicoid mRNA of maternal origin is translated into protein in the ribosomes and accumulates near the external nuclear walls of the recently formed nuclei. Here, we show that mRNA diffusion is the main morphogenesis mechanism explaining consistently the establishment of Bicoid protein gradients. Moreover, we show that if diffusion for both bicoid mRNA and Bicoid protein were assumed, a steady distribution of Bicoid protein would result, with a constant concentration along the embryo, contradicting observations.
Equivariant operational Chow rings of spherical varieties and T-linear varieties.
Richard Paul GONZALES VILCARROMERO
- 2013-04-12 (M/13/10)
We stablish localization theorems for the equivariant operational Chow rings (or equivariant Chow cohomology) of singular spherical varieties and T-linear varieties. Our main results provide a GKM description of these
rings in the case of spherical varieties admitting a BB-decomposition
into algebraic rational cells. Our description extends certain topological results to intersection theory on singular varieties.
Dynamic trajectory control of gliders
Rui DILãO, João FONSECA
- 2013-04-04 (M/13/09)
A new dynamic control algorithm in order to direct the trajectory of a glider to a pre-assigned target point is proposed.
The algorithm runs iteratively and the approach to the target point is self-correcting. The algorithm is applicable to any non-powered lift-enabled vehicle (glider) travelling in planetary atmospheres. As a proof of concept, we have
applied the new algorithm to the command and control of the trajectory of the Space Shuttle during the Terminal Area Energy Management (TAEM) phase.
Chemotaxis with directional sensing during Dictyostelium aggregation
Rui DILãO, Marcus HAUSER
- 2013-03-24 (M/13/07)
With an in silico analysis, we show that the chemotactic
movements of colonies of the starving amoeba Dictyostelium discoideum are driven by a force that depends on both the direction of propagation (directional sensing) of
reaction-diffusion chemotactic waves and on the gradient of
the concentration of the chemoattractant.
It is shown that the directional sensing of amoebae is due to
the sensitivity of the cells to the time variation of the
concentration of the chemoattractant combined with its gradient.
It is also shown that chemotaxis exclusively
driven by local concentration gradients leads to unstable local
motion, preventing cells from aggregation. These facts show
that the formation of mounds, which initiate multicellularity in Dictyostelium
caused by the sensitivity of the amoebae to three factors, namely,
to the direction of propagation of the chemoattractant, to its gradient, and to the spiral spatial topology of the propagating chemoattractant.
The regulation of gene expression in eukaryotes: bistability and oscillations in repressilator models
- 2013-03-24 (M/13/08)
To model the regulation of gene expression in eukaryotes by transcriptional activators and repressors, we introduce delays in conjugation with the mass action law.
Delays are associated with the time gap between the mRNA transcription in the nucleoplasm and the protein synthesis in the cytoplasm.
After re-parameterisation of the m-repressilator model with the Hill cooperative parameter n,
for n=1, the m-repressilator is deductible from the mass action law and, in the limit $n \to \infty$, it is a Boolean type model. With this embedding and with delays, if m is odd and n>1, we show that there is always a choice of parameters for which the m-repressilator model has sustained oscillations (limit cycles), implying that the 1-repressilator is the simplest genetic mechanism leading to sustained oscillations in eukaryotes. If m is even and n>1, there is always a choice of parameters for which the m-repressilator model has bistability.
Noyaux du transfert automorphe de Langlands et formules de Poisson non linéaires: Notes de cours
- 2013-02-18 (M/13/06)
On weakly group-theoretical non-degenerate braided fusion categories
- 2013-02-01 (M/13/05)
We show that the Witt class of a weakly group-theoretical non-degenerate braided fusion category belongs to the subgroup generated by classes of non-degenerate pointed braided fusion categories and Ising braided categories. This applies in particular to solvable non-degenerate braided fusion categories. We also give some sufficient conditions for a braided fusion category to be weakly group-theoretical or solvable in terms of the factorization of its Frobenius-Perron dimension and the Frobenius-Perron dimensions of its simple objects. As an application, we prove that every non-degenerate braided fusion category whose Frobenius-Perron dimension is a natural number less than 1800, or an odd natural number less than 33075, is weakly group-theoretical.
Special Functions in Minimal Representations
- 2013-01-22 (M/13/04)
Minimal representations of a real reductive group G are the `smallest' irreducible unitary representations of G.
We discuss special functions that arise in the analysis of L^2-model of minimal representations.
Rankin-Cohen Operators for Symmetric Pairs
Toshiyuki KOBAYASHI, Michael PEVZNER
- 2013-01-10 (M/13/03)
Sur la correspondance de Simpson p-adique. II : aspects globaux
Ahmed ABBES, Michel GROS
- 2013-01-09 (M/13/02)
We develop a new approach for the p-adic Simpson correspondence, closely related to the original approach of Faltings, but also inspired by the work of Ogus and Vologodsky on an analogue in characteristic p>0. This second article is devoted to the global aspects of the theory.
Sur la correspondance de Simpson p-adique. 0 : une vue d'ensemble
Ahmed ABBES, Michel GROS
- 2013-01-09 (M/13/01)
We develop a new approach for the p-adic Simpson correspondence, closely related to the original approach of Faltings, but also inspired by the work of Ogus and Vologodsky on an analogue in characteristic p>0. The aim of this article is to give an extensive overview of the theory that has been developped in two articles, the first one (arXiv:1102.5466) devoted to the local aspects and the second one (arXiv:1301.0904) to the global aspects.