Clustering approach applied on an artificial neural network model to predict PM10 in mega cities of México

A cluster-based artificial neural network model called CLASO (Classification-Assemblage-Association) has been proposed to predict the maximum of the 24-h moving average of PM10 concentration on the next day in the three largest metropolitan areas of Mexico. The model is a self-organised, real-time learning neural network, which builds its topology via a process of pattern classification by using an historical database. This process is based on a supervised clustering technique, assigning a class to each centroid of the hidden layer, employing the Euclidean distance as a hierarchical criterion. A set of ARIMA models was compared with CLASO model in the forecast performance of the 24-h average PM10 concentration on the next day. In general, CLASO model produced more accurate predictions of the maximum of the 24-h moving average of PM10 concentration than the ARIMA models, although the latter showed a minor tendency to underpredict the results. The CLASO model solely requires to be built a historical database of the air quality parameter, an initial radius of classification and the learning factor. CLASO has demonstrated acceptable predictions of 24-h average PM10 concentration by using exclusively regressive PM10 concentrations. The forecasting capabilities of the model were found to be satisfactory compared to the classical models, demonstrating its potential application to the other major pollutants used in the Mexican air quality index

Transiciones, conflictos y democracia : estudios de coyuntura

México ha vivido un largo proceso de transición que ha desencadenado dinamismos económicos, culturales y políticos. En la actual coyuntura, estos dinamismos muestran toda su complejidad, su inevitable articulación y la tensión entre las fuerzas que intentan sostener un viejo modelo de gobernar y decidir el rumbo del país, y aquellas que buscan abrirse a un espectro mucho más amplio y diversificado de actores. En ellos se conjuntan las aspiraciones más legítimas de los mexicanos por avanzar en el reconocimiento y respeto de la pluralidad étnica, de género y entre generaciones, y por impulsar una dinámica en la que —en medio de los procesos de mundialización— los distintos grupos e intereses de los mexicanos puedan ser incluidos. La transición mexicana tiende a centrarse en la dimensión política. La intensidad que cobran los procesos políticos y el énfasis que importantes analistas ponen en dichos procesos, contribuyen a que esta asociación vaya cobrandoíuerza. En este sentido, es necesario advertir que en las transiciones la tendencia privatizadora, la reducción del gasto social, así como la necesidad de pactos sociales que sean respetados, la participación creciente de la sociedad civil, etc. son factores importantes que, en medio de contradicciones, van generando nuevos esquemas de relación entre gobierno y sociedad.ITESO, A.C

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements