We discuss the representability almost everywhere (a.e.) in $ℂ$ of an irreducible algebraic function as the Cauchy transform of a signed measure supported on a finite number of compact semi-analytic curves and a finite number of isolated points. This brings us to the study of trajectories of the particular family of quadratic differentials $A(z-a)(z-b){(z-c)}^{-2}\mathrm{d}{z}^2$. More precisely, we give a necessary and sufficient condition on the complex numbers $a$ and $b$ for these quadratic differentials to have finite critical trajectories....

We consider an inhomogeneous measure μ with the inhomogeneous part a self-similar measure ν, and show that for a given r ∈ (0,∞) the lower and the upper quantization dimensions of order r of μ are bounded below by the quantization dimension $D_r\left(\nu \right)$ of ν and bounded above by a unique number ${\kappa }_r\in (0,\infty )$, related to the temperature function of the thermodynamic formalism that arises in the multifractal analysis of μ.

The quantization dimension function for the image measure of a shift-invariant ergodic measure with bounded distortion on a self-conformal set is determined, and its relationship to the temperature function of the thermodynamic formalism arising in multifractal analysis is established.

We estimate the spreading of the solution of the Schrödinger equation asymptotically in time, in term of the fractal properties of the associated spectral measures. For this, we exhibit a lower bound for the moments of order $p$ at time $T$ for the state $\psi$ defined by $[\frac{1}{T}{\int }_0^T\parallel |X{|}^{p/2}{\mathrm{e}}^{-itH}\psi {\parallel }^2\mathrm{d}t]$. We show that this lower bound can be expressed in term of the generalized Rényi dimension of the spectral measure ${\mu }_{\psi }$ associated to the hamiltonian $H$ and the state $\psi$. We especially concentrate on continuous models.

The Sierpinski gasket and other self-similar fractal subsets of Rd, d ≥ 2, can be mapped by quasiconformal self-maps of Rd onto sets of Hausdorff dimension arbitrarily close to one. In R2 we construct explicit mappings. In Rd, d ≥ 3, the results follow from general theorems on the equivalence of invariant sets for iterated function systems under quasisymmetric maps and global quasiconformal maps. More specifically, we present geometric conditions ensuring that (i) isomorphic systems have quasisymmetrically...

Pour tout compact complètement régulier $T$, on désigne par $M_{\beta }\left(T\right)$ l’espace des mesures de Radon sur le compactifié de Stone-Cech $\beta T$ de $T$ et par $M_{\sigma }\left(T\right)$ son sous-espace formé des mesures $\sigma$-régulières au sens de Varadarajan. On décrit alors sur ces deux espaces des topologies ${\mathbf{T}}_p$, $1\le p\le +\infty$, qui possèdent des propriétés curieuses parmi lesquelles il convient de citer la suivante : pour $1\<p\le +\infty$ et pour tout $T$ non pseudocompact, l’espace $\left(M_{\sigma }\right(T),{\mathbf{T}}_p)$ est non quasi-complet mais ses précompacts sont relativement compacts. Ce résultat permet...

Nous donnons des conditions permettant de vérifier que l’image d’une mesure cylindrique $\mu$ sur un espace vectoriel topologique $E$, par une application linéaire continue dans un autre espace vectoriel topologique $F$, est une mesure de Randon. Dans une première partie, nous donnons des résultats généraux qui portent, soit sur des propriétés géométriques de l’espace $F$, soit sur la mesure cylindrique $\mu$. Dans une seconde partie, nous donnons des conditions plus précises quand $\mu$ est une mesure cylindrique...