Comparing Neural and Attractiveness-based Visual Features for Artwork Recommendation

Advances in image processing and computer vision in the latest years have brought about the use of visual features in artwork recommendation. Recent works have shown that visual features obtained from pre-trained deep neural networks (DNNs) perform very well for recommending digital art. Other recent works have shown that explicit visual features (EVF) based on attractiveness can perform well in preference prediction tasks, but no previous work has compared DNN features versus specific attractiveness-based visual features (e.g. brightness, texture) in terms of recommendation performance. In this work, we study and compare the performance of DNN and EVF features for the purpose of physical artwork recommendation using transactional data from UGallery, an online store of physical paintings. In addition, we perform an exploratory analysis to understand if DNN embedded features have some relation with certain EVF. Our results show that DNN features outperform EVF, that certain EVF features are more suited for physical artwork recommendation and, finally, we show evidence that certain neurons in the DNN might be partially encoding visual features such as brightness, providing an opportunity for explaining recommendations based on visual neural models.Comment: DLRS 2017 workshop, co-located at RecSys 201

Análisis digital y detección de elecciones atípicas

Este trabajo utiliza la Ley de Newcomb-Benford y las pruebas de Beber y Scacco para analizar las elecciones presidenciales desde 1958 hasta el 2006, las presidenciales de 1922, las elecciones de Congreso en 2010, y las votaciones para Alcalde en Cali del 2007. Este es el primer estudio y aplicación sistemática de técnicas cuantitativas para la detección de anomalías en resultados electorales en Colombia. Aunque estas técnicas no ofrecen una prueba de la existencia de fraude, ni identifican el origen o receptor de una posible manipulación de los datos, sí permiten generar alertas que podrían ser utilizadas para priorizar investigaciones. Los resultados muestran la existencia de resultados atípicos en las elecciones presidenciales de 1970 y en las de Senado y Cámara de 2010. También se observan, aunque en menor grado, votaciones atípicas en las presidenciales de 1922, 1982, y en las votaciones de la Alcaldía de Cali 2007.Fraude electoral; Ley de Benford; Pruebas de Beber y Scacco; Análisis digital; Elecciones Colombia.

THE SPANISH CIVIL WAR: A NEW INSTITUTIONAL INTERPRETATION OF THE SOCIAL ORDER AND MILITARY FACTIONS DURING THE SECOND REPUBLIC (1931-1939)

This dissertation presents a new view that emphasizes the role of intra-elite fights in understanding the failure to consolidate democracy during the Second Spanish Republic. The two traditional explanations have emphasized the action of "blocks" and often reflect the ideological tensions behind the interpretation of the Second Republic. Rather than seeing elites as blocks or focusing on ideological divisions, my view focuses on the heterogeneity of interests within elites and how the redistribution of political and economic rents during the Republic relates to the support or animosity of elite factions vis-à-vis the republican government. I apply my view to one specific Spanish elite -the Army- showing that, contrary to traditional interpretations, the military was a non-monolithic organization that was divided into different factions with conflicting interests. I explore the impact that factional military interests had on officers' chosen side (rebel or loyal) during the Spanish Civil War that ended the Republic. The econometric analysis uses a new data set that identifies officers' sides and uses information from military yearbooks to follow officers' individual histories between 1910 and 1936. The results confirm that the Army was a non-monolithic organization where factions behaved differently and responded to the impact from republican military reforms. Officers in favored corps and those that enjoyed greater promotions between 1931 and 1936 were more likely to support the republican regime. I also explore the effect of hierarchy on officers' choice. Results show that subordinates tended to follow the side chosen by their senior officers

Statistical similarity between the compression of a porous material and earthquakes

It has been long stated that there are profound analogies between fracture experiments and earthquakes; however, few works attempt a complete characterization of the parallelisms between these so separate phenomena. We study the Acoustic Emission events produced during the compression of Vycor (SiO2). The Gutenberg-Richter law, the modified Omori's law, and the law of aftershock productivity are found to hold for a minimum of 5 decades, are independent of the compression rate, and keep stationary for all the duration of the experiments. The waiting-time distribution fulfills a unified scaling law with a power-law exponent close to 2.45 for long times, which is explained in terms of the temporal variations of the activity rate.Comment: 4 pages and a bit more, 4 figure