A study of data analysis techniques. Application to personal data analysis in the context of social networks

En los últimos años la sociedad está experimentando una serie de cambios. Uno de estos cambios es la datificación (“datafication” en inglés). Este término puede ser definido como la transformación sistemática de aspectos de la vida cotidiana de las personas en datos procesados por ordenadores. Cada día, a cada minuto y a cada segundo, cada vez que alguien emplea un dispositivo digital,hay datos siendo guardados en algún lugar. Se puede tratar del contenido de un correo electrónico pero también puede ser el número de pasos que esa persona ha caminado o su historial médico. El simple almacenamiento de datos no proporciona un valor añadido por si solo. Para extraer conocimiento de los datos, y por tanto darles un valor, se requiere del análisis de datos. La ciencia de los datos junto con el análisis de datos se está volviendo cada vez más popular. Hoy en día, se pueden encontrar millones de web APIs estadísticas; estas APIs ofrecen la posibilidad de analizar tendencias o sentimientos presentes en las redes sociales o en internet en general. Una de las redes sociales más populares, Twitter, es pública. Cada mensaje, o tweet, publicado puede ser visto por cualquier persona en el mundo, siempre y cuando posea una conexión a internet. Esto hace de Twitter un medio interesante a la hora de analizar hábitos sociales o perfiles de consumo. Es en este contexto en que se engloba este proyecto. Este trabajo, combinando el análisis estadístico de datos y el análisis de contenido, trata de extraer conocimiento de tweets públicos de Twitter. En particular tratará de establecer si el género es un factor influyente en las relaciones entre usuarios de Twitter. Para ello, se analizará una base de datos que contiene casi 2.000 tweets. En primer lugar se determinará el género de los usuarios mediante web APIs. En segundo lugar se empleará el contraste de hipótesis para saber si el género influye en los usuarios a la hora de relacionarse con otros usuarios. Finalmente se construirá un modelo estadístico para predecir el comportamiento de los usuarios de Twitter en relación a su género

Between broadcast yourself and broadcast whatever: YouTube’s homepage as a synthesis of its business strategy

YouTube is a company representative of its original context, Web 2.0, that originally positioned itself as an open and collaborative platform to broadcast videos created by all kinds of users; their slogan was, and remains, Broadcast yourself. The acquisition of YouTube by Google introduced it in the search for profit in the framework of OTT (over the top) communication. The YouTube homepage reveals the successive business policies followed by the platform. In this work we analyze the evolution of the unlogged homepage of YouTube Spain between 2009 and 2018. We observe the gradual disappearance of the videos produced by private users and its replacement by those made by professional users (youtubers) and cultural industries. There is a remarkable parallelism between the implementation of business models and the greater or lesser recommendation of video from one kind of user or another

Editorial: Aurora Kinases: Classical Mitotic Roles, Non-Canonical Functions and Translational Views

Aurora kinases are key mitotic regulators that have also been associated with tumor development and progression. The interest on this highly conserved family of protein kinases has grown exponentially since they were discovered in the 1990s. Despite the steady increase in the number of laboratories involved and the consequent boost of the volume of research output during the last years, the study of Aurora kinases remains a very dynamic area in which new discoveries frequently keep coming to light. From a clinical perspective, the interest on Aurora kinase biology stems from their identification as targets for drug development; an increasing number of Aurora kinase inhibitors are being tested in preclinical projects and clinical trials. In this Frontiers Research Topic, we have aimed to not only review and revisit different aspects of the functions and regulation of Aurora kinases but also provide a forum for the publication of new developments in the field. We have been privileged to count on contributions from authors and reviewers that include some of the most experienced voices in our research area.Work in our laboratories is supported by grants from Ministerio de Economía, Industría y Competitividad (SAF SAF2016-76929-R), Ligue Nationale Contre le Cancer (LNCC, équipe labelisée 2014-2016), and Wellcome Trust (073915, 077707, and 092076).S

Effects of thinning intensity on radial growth patterns and temperature sensitivity in Pinus canariensis afforestations on Tenerife Island, Spain

The final publication is available at Springer via http://dx.doi.org/10.1007/s13595-011-0125-8The suitability of thinning to prevent forest growth decline from global warming has been 25 scarcely tested in the Macaronesian Canary pine (Pinus canariensis Sweet ex Spreng.). We used tree-ring series from dominant, codominant, and overtopped trees to study the 27 effects of thinning intensity on basal area increments (BAI) and climate sensitivity on windward 28 (wet) and leeward (dry) slopes on Tenerife, Canary Islands. Three replicated blocks of control, 29 light thinning, and heavy thinning stands were set on each slope in 1988, and cores were 30 extracted in 2007. Heavy thinning induced growth release and increased BAI, mainly on dominant and 32 codominant trees, whereas light thinning effects were negligible; their impacts were more intense 33 on windward. Temperature sensitivity was hardly affected by thinning on leeward, where climate 34 control was stronger. On windward, thinning enhanced the influence of summer temperatures. 35 Upper crown classes were overall more sensitive, but overtopped trees responded better in 36 summer. Thinning intensity and aspect greatly influence growth on Canary pine afforestations, but 38 individual responses are highly dependent on crown classes. In addition, thinning may be less 39 effective to modify growth conditions on leeward slopes, at least if it is not intense.We thank A. González, S. Lamas, P. Manso, I. Outeda, B. Rodríguez-Morales and A. Soliño for laboratory assistance, N. Muñoz for statistical advice, and two anonymous reviewers for providing valuable comments on the manuscript. The staff of Corona Forestal Natural Park of Tenerife facilitated site accession. We gratefully acknowledge the effort 380 of staff and technicians that designed and executed the thinning experiment in 1988. V. Rozas benefited by a visiting fellowship to the University of La Laguna, funded by Consellería de Innovación e Industria, Xunta de Galicia, and research contracts by INIA-Xunta de Galicia and 383 CSIC. This research was partially funded by Consellería de Innovación e Industria, Xunta de Galicia (PGIDIT06PXIB502262PR) and INIA, Spanish Ministry of Science and Innovation (RTA2006-00117)

San Pedro Martir observations of microvariability in obscured quasars

Fast brightness variations are a unique tool to probe the innermost regions of active galactic nuclei (AGN). These variations are called microvariability or intra-night variability, and this phenomenon has been monitored in samples of blazars and unobscured AGNs. Detecting optical microvariations in targets hidden by the obscuring torus is a challenging task because the region responsible for the variations is hidden from our sight. However, there have been reports of fast variations in obscured Seyfert galaxies in X-rays, which rises the question whether microvariations can also be detected in obscured AGNs in the optical regime. Because the expected variations are very small and can easily be lost within the noise, the analysis requires a statistical approach. We report the use of a one-way analysis of variance, ANOVA, with which we searched for microvariability. ANOVA was successfully employed in previous studies of unobscured AGNs. As a result, we found microvariable events during three observing blocks: in two we observed the same object (Mrk 477), and in another, J0759+5050. The results on Mrk 477 confirm previous findings. However, since Mrk 477 is quite a peculiar target with hidden broad-line regions, we cannot rule out the possibility that we have serendipitously chosen a target prone to variations.Comment: Research note, 5 pages, 2 figures, accepted for publication in Astronomy and Astrophysic

Convertidores electrónicos de potencia para alimentar LEDs de iluminación desde tensiones muy bajas

XXIV Seminario Anual de Automática, Electrónica Industrial e Instrumentación 2017 (SAAEI'17), Valencia (España)Este artículo describe y valora distintas alternativas para alimentar diodos emisores de luz (LEDs) blancos, de los usados habitualmente para iluminación, desde tensiones mucho menores que la tensión de codo del propio dispositivo emisor de luz. En resumen, se va a estudiar cómo alimentar un LED con tensión de codo entorno de los 3 V desde una única celda de batería de tensión comprendida entre 1,2 y 2 V. En el artículo se valorarán y compararán dos tipos de convertidores para esta aplicación: convertidores CC/CC estándar con diodo Schottky (en vez de diodo PN) y una nueva familia de convertidores CC/CC expresamente pensados para ser usados con LEDs en los que el diodo de la topología es el propio LED. Ambos tipos de soluciones han sido experimentadas, buscando establecer comparaciones entre ellas desde distintos puntos de vista, como son el coste, el rendimiento eléctrico y el rendimiento lumínic

Modular three-phase ac-dc LED driver based on summing the light output of each phase

IEEE Applied Power Electronics Conference and Exposition, San Antonio, (Estados Unidos de Norteamérica), marzo de 2018This work proposes the driving of high power Light-Emitting Diodes (LEDs) luminaires in three phase power grids using each phase to drive an independent LED load. The driving is done by means of a boost converter in charge of controlling the current across its LED load. Moreover, each boost converter needs to achieve Power Factor Correction (PFC) to comply with IEC 61000-3-2 Class C requirements. Hence, achieving unity Power Factor (PF) and low Total Harmonic Distortion (THD). Taking advantage of the light properties, the output of the LED driver will be the sum of the light of each of the phases. Therefore, a theoretical study will be carried out to observe the feasibility of removing the electrolytic capacitor while guaranteeing a flicker free behaviour of the LED luminaire, even if the current of each string is pulsating at twice the mains frequency. In order to validate the study, a prototype has been built comprised of three PFC boost converters disposing of their electrolytic capacitors. The designed prototype operates in the full range of the European three-phase line voltage, which varies between 380 V and 420 V, and it supplies an output light of 42.000 lm at a maximum power of 300 W while achieving an electrical efficiency of 97.5

Full OCT anterior segment biometry: An application in cataract surgery

In vivo three-dimensional (3-D) anterior segment biometry before and after cataract surgery was analyzed by using custom highresolution high-speed anterior segment spectral domain Optical Coherence Tomography (OCT). The system was provided with custom algorithms for denoising, segmentation, full distortion correction (fan and optical) and merging of the anterior segment volumes (cornea, iris, and crystalline lens or IOL), to provide fully quantitative data of the anterior segment of the eye. The method was tested on an in vitro artificial eye with known surfaces geometry at different orientations and demonstrated on an aging cataract patient in vivo. Biometric parameters CCT, ACD/ILP, CLT/ILT Tilt and decentration are retrieved with a very high degree of accuracy. IOL was placed 400 οm behind the natural crystalline lens, The IOL was aligned with a similar orientation of the natural lens (2.47 deg superiorly), but slightly lower amounts (0.77 deg superiorly). The IOL was decentered superiorly (0.39 mm) and nasally (0.26 mm). © 2013 Optical Society of America.This study has been funded by Spanish Government Grant FIS2011-25637 and European Research Council Grant ERC-2011-AdG-294099 to S. Marcos.Peer Reviewe

Optimized design of a high input-voltage-ripple-rejection converter for LED lighting

The asymmetrical half-bridge (AHB) converter has been deeply analyzed as second stage in ac–dc light emitting diode (LED) drivers. Galvanic isolation, high reliability and high efficiency are their main advantages while a limited duty cycle range (i.e., 0–0.5) and a poor dynamic behavior are their main disadvantages. As second stage of an LED driver, the most demanding requirement for its control loop is cancelling the low-frequency ripple introduced by the first stage. According to its limited maximum attainable bandwidth, this is normally achieved by implementing a feedforward loop. Nonetheless, the static gain of the standard AHB converter presents a nonlinear relation between the output voltage and the duty cycle. As a consequence, the effectiveness of this feedforward loop is limited. In this paper, the use of the zeta AHB converter as second stage of an LED driver is analyzed and an optimized design is proposed. Regarding its advantages, it presents an extended duty cycle range (theoretically, 0–1.0). Besides, it presents a linear relation between the output voltage and the duty cycle. Therefore, although its dynamic behavior is still limited, it can perfectly cancel the low-frequency ripple introduced by the first stage of the LED driver by means of a straightforward feedforward loop. The optimized design proposed in this paper is focused on minimizing the losses in the magnetic components (transformer and inductor) by wisely choosing the value of the two turns ratios of the transforme

On supplying LEDs from very low dc voltages with high frequency AC-LED drivers

2018 IEEE 19th Workshop on Control and Modeling for Power Electronics (COMPEL), 25-28 junio, Padua (Italia)This work studies the driving of white Light Emitting Diodes (LEDs) from very low voltages in the range of 1.2 to 2 V. The proposed idea is based on replacing the standard Schottky diode used in conventional converter topologies (i.e., buck, buck-boost and boost) with an LED, while shortcutting the output of the converter. In this configuration, the LED works both as the load and as the rectifier diode of the converter, hence, switching the LED at high frequencies (i.e. > 100 kHz). Moreover, a thorough analytical study is carried out for the two topologies rendered in this work. Particularly emphasizing their static analysis and the obtaining of the boundaries between the different conduction modes. Finally, the idea is validated experimentally by means of the boost converter variation (i.e., DL//S AC-LED driver). The DL//S AC-LED driver has also been compared with a dc-dc boost converter showing a better luminous efficacy while disposing of the Schottky diode and the output capacitor. This analysis is carried out when connected to a Li-Ion battery using a simple control and integrated circuit for its developmen