Adiós a Italia en La Colmena

_Traducciones literarias del italiano al español, los textos traducidos son de géneros literarios diversos: poesía, cuentos breves y aforismos

Arrighetto El insomnio

_Traducción del cuento "Insomnio", de Arrigo de Settimelo, conocido como Arrighetto, escritor italiano del siglo XII

Exact solutions and cosmological constraints in fractional cosmology

This paper investigates exact solutions of cosmological interest in fractional cosmology. Given $\mu$, the order of the fractional derivative, and $w$, the matter equation of state, we present particular exact power-law solutions. We discuss the exact general solution of the system obtained by solving a Riccati Equation, where the solution for the scale factor is a combination of power-law. Using cosmological data, we estimate the free parameters $(\alpha_0, \mu)$, where $H_{0}=100\frac{\text{km/s}}{\text{Mpc}}h$, and $\alpha_0:=t_0 H_0 = \frac{1}{6} \left(9 -2 \mu +\sqrt{8 \mu (2 \mu -9)+105}\right)(1+ 2 \epsilon_0)$, is the current age parameter. The joint analysis with data from SNe Ia + OHD leads to $h=0.684_{-0.027}^{+0.031}$, $\mu=1.840_{-0.773}^{+1.446}$ and $\epsilon_0=\left(1.213_{-1.057}^{+0.482}\right)\times 10^{-2}$, where the best-fit values are calculated at $3\sigma$ CL. On the other hand, these best-fit values lead to an age of the Universe with a value of $t_0=\alpha_0/H_0=25.62_{-4.46}^{+6.89}\;\text{Gyrs}$, a current deceleration parameter of $q_{0}=-0.37_{-0.11}^{+0.08}$, both at $3\sigma$ CL, and a current matter density parameter of $\Omega_{m,0}=0.531_{-0.260}^{+0.195}$ at $1\sigma$ CL. Finding a Universe roughly twice older as the one of $\Lambda$CDM is a distinction of Fractional Cosmology. Focusing our analysis on these results, we can conclude that the region in which $\mu>2$ is not ruled out by observations. This region of a parameter is relevant because, in the absence of matter, fractional cosmology gives a power-law solution $a(t)= \left(t/t_0\right)^{\mu-1}$, which is accelerated for $\mu>2$. We present a fractional origin model that leads to an accelerated state without appealing to $\Lambda$ or Dark Energy.Comment: 51 pages, 10 figure

Polynomial Approach and Non-linear Analysis for a Traffic Fundamental Diagram

Vehicular traffic can be modelled as a dynamic discrete form. As in many dynamic systems, the parameters modelling traffic can produce a number of different trajectories or orbits, and it is possible to depict different flow situations, including chaotic ones. In this paper, an approach to the wellknown density-flow fundamental diagram is suggested, using an analytical polynomial technique, in which coefficients are taken from significant values acting as the parameters of the traffic model. Depending on the values of these parameters, it can be seen how the traffic flow changes from stable endpoints to chaotic trajectories, with proper analysis in their stability features