deletions | additions       diff --git a/Introduction.tex b/Introduction.tex  index a61bff4..6b9af36 100644  --- a/Introduction.tex  +++ b/Introduction.tex 
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u_z = \frac{(3\lambda + 2\mu)}{(\lambda + 2\mu)} \frac{\alpha E \zeta}{\rho C S \zeta} \approx 3 \alpha \frac{E}{\rho C S}   % \label{eq:deplUnidim}  \end{equation}  as in a biological soft tissues, $\mu \gg \lambda$. Taking as an order of magnitude $\alpha$ = 70.10$^{-6}$ K$^{-1}$ (water linear thermal dilatation coefficient), $E$ = 200 mJ, $\rho$ = 1000 kg.m$^{-3}$ (water density), $C$ = 4180 kg.m$^{-3}$ (water calorific capacity) and $S$ = 20 mm$^2$, we obtain a displacement $u_z$= 0.5 $\mu$m. This value is still slightly  smaller than the typical displacement ultrasound  resolution with ultrasound, of displacement, typically  of a few micrometers. This unidimensional analysis cannot explain the induction of shear waves in a thermoelastic expansion, as this displacement is curl-free. However, in In  a tridimensional model, displacements along X and Y axis would also occurs, as  the local expansion acts as dipolar forces parallel to the surface, so displacements along X and Y axis could also lead to shear waves. surface.  In the ablative regime, the local increase of temperature is so high that the surface of the medium is vaporized. This phenomenon creates a stress $\sigma$ in the medium, given by \cite{scruby1990laser}:  \begin{equation} 
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