a certain temperature. For that we consider the quark pressure difference from the zero-temperature value $$\label{nu}
      \nu (T) = \frac{p(T)-p(0)}{\pi^2T^4/90},$$ in order that the total $\nu (0)=0$. Here $p(T)=-V(M^*_f,T,\mu =0)$, where $M^*_f$ denotes the gap equation solution at a given $T$. Dividing the pressure in eq. (\[nu\]) by $\pi^2T^4/90$, the result is presented in Stefan-Boltzmann units, i.e. one explicitly counts the number of relevant degrees of freedom.

It is known that in the case of massless quarks of two and three flavors the fermionic degrees of freedom at $T>T_c$ are estimated as $\nu =(7/8)\times 
3\times 2\times 4=21$ and $\nu =(7/8)\times 3\times 3\times 4=31.5$, respectively. The system studied here consists of three-types of light quarks: $u,d,s$. Hence $\nu$ is expected to be in the interval $21<\nu <31.5$ in the region $T>T_c$, where chiral symmetry is “restored” (up to the explicit symmetry breaking effects caused by the current quark masses). Indeed, the solid curves $\nu (T/T_c)$, plotted for the sets (a) and (b) in fig. \[fig-1\], at some values $T/T_c>1$ enter the interval and approach asymptotically the upper bound $\nu =31.5$ at high $T$: in particular, we have already at $T/T_c =2.5$ that $\nu (2.5)=30.95$ (set (a)) and $\nu (2.5) =30.25$ (set 