Isotropization of the universe during inflation

A primordial inflationary phase allows one to erase any possible anisotropic expansion thanks to the cosmic no-hair theorem. If there is no global anisotropic stress, then the anisotropic expansion rate tends to decrease. What are the observational consequences of a possible early anisotropic phase? We first review the dynamics of anisotropic universes and report analytic approximations. We then discuss the structure of dynamical equations for perturbations and the statistical properties of observables, as well as the implication of a primordial anisotropy on the quantization of these perturbations during inflation. Finally we briefly review models based on primordial vector field which evade the cosmic no-hair theorem.Comment: 9 pages, 3 figures. Invited review article for the French Academy of Scienc

A-twisted correlators and Hori dualities

The Hori-Tong and Hori dualities are infrared dualities between two-dimensional gauge theories with $\mathcal{N}{=}(2,2)$ supersymmetry, which are reminiscent of four-dimensional Seiberg dualities. We provide additional evidence for those dualities with $U(N_c)$, $USp(2N_c)$, $SO(N)$ and $O(N)$ gauge groups, by matching correlation functions of Coulomb branch operators on a Riemann surface $\Sigma_g$, in the presence of the topological $A$-twist. The $O(N)$ theories studied, denoted by $O_+ (N)$ and $O_- (N)$, can be understood as $\mathbb{Z}_2$ orbifolds of an $SO(N)$ theory. The correlators of these theories on $\Sigma_g$ with $g > 0$ are obtained by computing correlators with $\mathbb{Z}_2$-twisted boundary conditions and summing them up with weights determined by the orbifold projection.Comment: 45 pages plus appendix; v2: updated bibliography and acknowledgement

Weak-lensing BB-modes as a probe of the isotropy of the universe

We compute the angular power spectrum of the $B$-modes of the weak-lensing shear in a spatially anisotropic spacetime. We find that there must also exist off-diagonal correlations between the $E$-modes, $B$-modes, and convergence that allow one to reconstruct the eigendirections of expansion. Focusing on future surveys such as Euclid and SKA, we show that observations can constrain the geometrical shear in units of the Hubble rate at the percent level, or even better, offering a new and powerful method to probe our cosmological model.Comment: 4 pages, 3 figures. This version matches the published on

Molecular Genetic Typing of Staphylococcus aureus from Cows, Goats, Sheep, Rabbits and Chickens

End of project reportsS. aureus can also cause a number of infections in animals such as tick-associated pyaemia in lambs, staphylococcosis in rabbits, septicaemia, abscesses and chondronecrosis in chickens and pneumonia and osteomyelitis complex in turkeys. S. aureus is the most frequent cause of bovine mastitis, a disease that is of economic importance worldwide (Beck et al., 1992). Typically staphylococcal mastitis is chronic in nature, with subclinical mastitis being the most common form

Acetylation Controls the Subcellular Localization of Thyroid Hormone Receptor α1

Thyroid hormone is produced by the thyroid gland through the hypothalamic-pituitary-thyroid axis. It is critical for growth, development, and homeostasis, and its action is mediated by the thyroid hormone receptor alpha1 (TRα1). TRα1 is a transcription factor that activates or represses target genes in response to thyroid hormone. Although primarily localized to the nucleus at steady state, TRα1 shuttles rapidly between the nucleus and cytosol. This thesis research focused on elucidating how post-translational modification of TRα1 modulates its nucleocytoplasmic transport. TRα1 is known to be acetylated at lysine residues 128, 132, and 134. In order to determine whether acetylation of TRα1 plays a role in regulating nucleocytoplasmic transport, expression plasmids for GFP or mCherry-tagged TRα1 mutants that mimic acetylation (lysine to glutamine substitutions) and nonacetylation (lysine to arginine substitutions) were constructed. Fluorescence microscopy was used to determine the nuclear/cytosolic (N/C) ratio of the fusion proteins in transfected cells by measuring fluorescence intensity. N/C data showed that the TRα1 nonacetylation mimic and wild-type TRα1 both have a primarily nuclear localization, and that intracellular distribution patterns of the TRα1 nonacetylation mimic and wild-type TRα1 were not hormone dependent. Furthermore, when co-transfected the presence of the TRα1 nonacetylation mimic did not change wild-type TRα1 localization. In contrast, the TRα1 acetylation mimic showed a lower N/C ratio compared to wild-type TRα1, indicating a significant decrease in nuclear localization. Taken together, these data suggest that interactions between TRα1 and transport factors may depend on electrostatic interactions. These findings will extend understanding of the role of post-translational modifications in regulating the fine balance between nuclear import, export, and nuclear retention, and how this interplays with TRα1 transcriptional regulation

Viscous spreading of an inertial wave beam in a rotating fluid

We report experimental measurements of inertial waves generated by an oscillating cylinder in a rotating fluid. The two-dimensional wave takes place in a stationary cross-shaped wavepacket. Velocity and vorticity fields in a vertical plane normal to the wavemaker are measured by a corotating Particule Image Velocimetry system. The viscous spreading of the wave beam and the associated decay of the velocity and vorticity envelopes are characterized. They are found in good agreement with the similarity solution of a linear viscous theory, derived under a quasi-parallel assumption similar to the classical analysis of Thomas and Stevenson [J. Fluid Mech. 54 (3), 495-506 (1972)] for internal waves

Direct measurements of anisotropic energy transfers in a rotating turbulence experiment

We investigate experimentally the influence of a background rotation on the energy transfers in decaying grid turbulence. The anisotropic energy flux density, ${\bf F} ({\bf r}) =$, where $\delta {\bf u}$ is the vector velocity increment over separation ${\bf r}$, is determined for the first time using Particle Image Velocimetry. We show that rotation induces an anisotropy of the energy flux $\nabla \cdot {\bf F}$, which leads to an anisotropy growth of the energy distribution $E({\bf r}) = < (\delta {\bf u})^2 >$, in agreement with the K\'arm\'an-Howarth-Monin equation. Surprisingly, our results prove that this anisotropy growth is essentially driven by a nearly radial, but orientation-dependent, energy flux density ${\bf F} ({\bf r})$.Comment: to appear in Physical Review Letters (July 8, 2011 issue