phase transition in certain regimes of the $T$-$\mu_q$ plane, depending on the couplings [@Theis:1984qc; @Zschiesche:2001dx; @Zschiesche:2004si]. Using this EoS, a phase structure including a first-order phase transition and a critical endpoint at finite $\mu_B$ is obtained [@Zschiesche:2006rf]. This EoS has already been successfully applied to a hydrodynamic calculation [@Steinheimer:2007iy].

To visualize the differences of these EoS, Fig. \[press\_t\] shows the average pressure of the expanding system, from central Pb+Pb collisions at $E_{\rm lab} = 20A$ GeV (left plot) and $158A$ GeV (right plot), as a function of time (in the center of mass frame). The vertical line in each plot indicates the starting time of the hydro evolution. The mean value of the pressure has been obtained by weighting the pressure, $P_{i}$, in every cell $i$ by its energy density, $\varepsilon_{i}$, and integrating over the hydrodynamic grid

$$<P> =\frac{\sum_{i}{ P_{i}\cdot\varepsilon_{i} }
}{\sum_{i}{\varepsilon_{i}}}.$$

![Time (in the center of mass frame) evolution of the average pressure for all three EoS and a central Pb+Pb collision at $E_{\rm
lab}=20A$ GeV (left plot) and $E_{\rm lab}=158A$ GeV (right plot). The vertical line in each plot indicates the starting time of the hydro evolution.[]{data-label="press_t"}](press_t.eps){width="48.00000%"}

All curves in Fig. \[press\_t\] are plotted until the point in 