Modelos cosmológicos no estándar

El Modelo Estándar Cosmológico es el modelo más simple y elegante capaz de explicar el origen y la evolución del universo, así como la mayoría de los datos experimentales y observaciones realizados hasta el momento. El Modelo Estándar se apoya sobre ciertas hipótesis, como la homogeneidad e isotropía del universo a gran escala, y resulta interesante poner a prueba estas hipótesis. El modelo de Lemaître-Tolman-Bondi (LTB) relaja la hipótesis de la homogeneidad para ver si pueden reproducirse los datos observacionales. El objetivo de este trabajo es presentar el modelo LTB, explicando sus características y exponiendo algunas confrontaciones con los datos experimentales

Análisis mediante teoría de redes de interacciones en sistemas complejos reales

En este trabajo se presenta el estudio del impacto de la salida de Reino Unido de la Unión Europea en la red de proyectos europeos del programa Horizon 2020. Para ello, se han analizado las redes de colaboración de los centros de investigación de Europa antes y después del Brexit. Además, se han generado redes en las que se han eliminado de manera aleatoria la misma cantidad de centros que centros británicos existen. De este modo, la comparación entre los valores de las propiedades de estas redes con las anteriormente mencionadas nos aportará información valiosa sobre el papel que juega Reino Unido en los proyectos de I+D europeos

Solving Color Reproducibility between Digital Devices: A Robust Approach of Smartphones Color Management for Chemical (Bio)Sensors

In the past twelve years, digital image colorimetry (DIC) on smartphones has acquired great importance as an alternative to the most common analytical techniques. This analysis method is based on fast, low-cost, and easily-accessible technology, which can provide quantitative information about an analyte through the color changes of a digital image. Despite the fact that DIC is very widespread, it is not exempt from a series of problems that are not fully resolved yet, such as variability of the measurements between smartphones, image format in which color information is stored, power distribution of the illuminant used for the measurements, among others. This article proposes a methodology for the standardization and correction of these problems using self-developed software, together with the use of a 3D printed light box. This methodology is applied to three different colorimetric analyses using different types and brands of smartphones, proving that comparable measurements between devices can be achieved. As color can be related to many target analytes, establishing this measurement methodology can lead to new control analysis applicable to diverse sectors such as alimentary, industrial, agrarian, or sanitary

The Hurst Exponent as an Indicator to Anticipate Agricultural Commodity Prices

Anticipating and understanding fluctuations in the agri-food market is very important in order to implement policies that can assure fair prices and food availability. In this paper, we contribute to the understanding of this market by exploring its efficiency and whether the local Hurst exponent can help to anticipate its trend or not. We have analyzed the time series of the price for different agri-commodities and classified each day into persistent, anti-persistent, or white-noise. Next, we have studied the probability and speed to mean reversion for several rolling windows. We found that in general mean reversion is more probable and occurs faster during anti-persistent periods. In contrast, for most of the rolling windows we could not find a significant effect of persistence in mean reversion. Hence, we conclude that the Hurst exponent can help to anticipate the future trend and range of the expected prices in this market