A SLR on Customer Dropout Prediction

Dropout prediction is a problem that is being addressed with machine learning algorithms; thus, appropriate approaches to address the dropout rate are needed. The selection of an algorithm to predict the dropout rate is only one problem to be addressed. Other aspects should also be considered, such as which features should be selected and how to measure accuracy while considering whether the features are appropriate according to the business context in which they are employed. To solve these questions, the goal of this paper is to develop a systematic literature review to evaluate the development of existing studies and to predict the dropout rate in contractual settings using machine learning to identify current trends and research opportunities. The results of this study identify trends in the use of machine learning algorithms in different business areas and in the adoption of machine learning algorithms, including which metrics are being adopted and what features are being applied. Finally, some research opportunities and gaps that could be explored in future research are presented.info:eu-repo/semantics/publishedVersio

Impact of regulation fair disclosure on corporate communications with investors

In this study we report laser ablation–inductively coupled plasma–mass spectrometer U-Pb ages of granitoids from the so-called early granodiorites of the northwest Iberian Variscan belt. The U-Pb results attest to significant magmatic activity in Visean time (ca. 347–337 Ma) that generated a hitherto poorly constrained granitoid suite in the northwest Iberian tract of the western European Variscan belt realm. This early Carboniferous suite (ECS) is mainly composed of peraluminous cold and hot crustal granodiorites and monzogranites with minor associated mafic rocks that attest to minor involvement of mantle melting. Based on the geochronological and geochemical data, we compare the Visean granitoids with younger Variscan granitoids in northwest Iberia and, in view of the tectonothermal scenarios of the Variscan collision in northwest Iberia, propose a model for the genesis of the ECS in northwest Iberia that involves rapid melting upon fast exhumation of the thickened Gondwanan crust in the course of the protracted Variscan collision.This work has been funded by the Spanish Ministry of Economy and Competitiveness under the project ODRE III—Oroclines & Delamination: Relations & Effects (CGL2013-46061-P) and Происхождение, металлогения, климатические эффекты и цикличность Крупных Изверженных Провинций (КИП) (Origin, metallogeny, climatic effects, and cyclical large igneous provinces) (14.Y26.31.0012; Russian Federation) to Gutiérrez-Alonso and López-Carmona and CGL-2016-76438-P to Fernández-Suárez. López-Carmona was also funded by a “Juan de la Cierva” grant (reference FJCI-2014-20740).Peer reviewe

Star-formation histories of local luminous infrared galaxies

We present the analysis of the integrated spectral energy distribution (SED) from the ultraviolet (UV) to the far-infrared and H$\alpha$ of a sample of 29 local systems and individual galaxies with infrared (IR) luminosities between 10^11 Lsun and 10^11.8 Lsun. We have combined new narrow-band H$\alpha$+[NII] and broad-band g, r optical imaging taken with the Nordic Optical Telescope (NOT), with archival GALEX, 2MASS, Spitzer, and Herschel data. The SEDs (photometry and integrated H$\alpha$ flux) have been fitted with a modified version of the MAGPHYS code using stellar population synthesis models for the UV-near-IR range and thermal emission models for the IR emission taking into account the energy balance between the absorbed and re-emitted radiation. From the SED fits we derive the star-formation histories (SFH) of these galaxies. For nearly half of them the star-formation rate appears to be approximately constant during the last few Gyrs. In the other half, the current star-formation rate seems to be enhanced by a factor of 3-20 with respect to that occured ~1 Gyr ago. Objects with constant SFH tend to be more massive than starbursts and they are compatible with the expected properties of a main-sequence (M-S) galaxy. Likewise, the derived SFHs show that all our objects were M-S galaxies ~1 Gyr ago with stellar masses between 10^10.1 and 10^11.5 Msun. We also derived from our fits the average extinction (A_v=0.6-3 mag) and the polycyclic aromatic hydrocarbons (PAH) luminosity to L(IR) ratio (0.03-0.16). We combined the A_v with the total IR and H$\alpha$ luminosities into a diagram which can be used to identify objects with rapidly changing (increasing or decreasing) SFR during the last 100 Myr.Comment: 16 pages + online material, accepted for publication in A&

Chromaffin-cell stimulation triggers fast millimolar mitochondrial Ca2+ transients that modulate secretion

Producción CientíficaActivation of calcium-ion (Ca2+) channels on the plasma membrane and on intracellular Ca2+ stores, such as the endoplasmic reticulum, generates local transient increases in the cytosolic Ca2+ concentration that induce Ca2+ uptake by neighbouring mitochondria. Here, by using mitochondrially targeted aequorin proteins with different Ca2+ affinities, we show that half of the chromaffin-cell mitochondria exhibit surprisingly rapid millimolar Ca2+ transients upon stimulation of cells with acetylcholine, caffeine or high concentrations of potassium ions. Our results show a tight functional coupling of voltage-dependent Ca2+ channels on the plasma membrane, ryanodine receptors on the endoplasmic reticulum, and mitochondria. Cell stimulation generates localized Ca2+ transients, with Ca2+ concentrations above 20–40 mM, at these functional units. Protonophores abolish mitochondrial Ca2+ uptake and increase stimulated secretion of catecholamines by three- to fivefold. These results indicate that mitochondria modulate secretion by controlling the availability of Ca2+ for exocytosis.2015-03-1

Higher prevalence of X-ray selected AGN in intermediate age galaxies up to z~1

We analyse the stellar populations in the host galaxies of 53 X-ray selected optically dull active galactic nuclei (AGN) at 0.34<z<1.07 with ultra-deep (m=26.5) optical medium-band (R~50) photometry from the Survey for High-z Absorption Red and Dead Sources (SHARDS). The spectral resolution of SHARDS allows us to consistently measure the strength of the 4000 AA break, Dn(4000), a reliable age indicator for stellar populations. We confirm that most X-ray selected moderate-luminosity AGN (L_X<10^44 erg/s) are hosted by massive galaxies (typically M*>10^10.5 M_sun) and that the observed fraction of galaxies hosting an AGN increases with the stellar mass. A careful selection of random control samples of inactive galaxies allows us to remove the stellar mass and redshift dependencies of the AGN fraction to explore trends with several stellar age indicators. We find no significant differences in the distribution of the rest-frame U-V colour for AGN hosts and inactive galaxies, in agreement with previous results. However, we find significantly shallower 4000 AA breaks in AGN hosts, indicative of younger stellar populations. With the help of a model-independent determination of the extinction, we obtain extinction-corrected U-V colours and light-weighted average stellar ages. We find that AGN hosts have younger stellar populations and higher extinction compared to inactive galaxies with the same stellar mass and at the same redshift. We find a highly significant excess of AGN hosts with Dn(4000)~1.4 and light weighted average stellar ages of 300-500 Myr, as well as a deficit of AGN in intrinsic red galaxies. We interpret failure in recognising these trends in previous studies as a consequence of the balancing effect in observed colours of the age-extinction degeneracy.Comment: Accepted for publication in MNRAS, 12 pages, 8 figures, 1 tabl

Impacto de la violencia colectiva en la salud. Resultados del estudio ISAVIC en el País Vasco

ResumenObjetivoA pesar de la ubicuidad de la violencia y de su posible importancia para la salud de las personas y las colectividades, su papel y mecanismos de acción en este sentido no están apenas analizados. Este estudio, realizado en los años 2005-2008 en el País Vasco, trata de estimar la asociación de la violencia colectiva con la salud de sus víctimas primarias.MétodosSe emparejó una muestra intencional de 33 víctimas primarias (receptores directos de la violencia o familiares en primer grado de personas asesinadas), en función de su edad, sexo, nivel de estudios y provincia de residencia, con sujetos (en una proporción 1:5) procedentes de una muestra representativa de la población mayor de 16 años residente en el País Vasco. Todos completaron un cuestionario que incluía medidas de salud (WHO-DAS-II-12, GHQ-12, SF-12, escalas de soledad y estigma) y variables potencialmente mediadoras (apoyo y clima social, y otras). Se compararon mediante regresiones condicionales a la experiencia de violencia colectiva.ResultadosLas víctimas primarias presentan entre cuatro y siete veces un mayor riesgo de padecer peor salud física y emocional, y ocho veces más de sufrir alteraciones funcionales. También perciben una mayor soledad y estigma, y valoran negativamente el apoyo y el clima social. No se observó asociación en los sujetos que declararon exposición a una violencia interpersonal leve.ConclusionesLos resultados sugieren que la violencia colectiva se asocia a una pérdida considerable de salud en las víctimas primarias. Su asociación en la población general requiere una investigación más específica.AbstractObjectivesDespite the ubiquity of violence and its possible impact on individual and collective health, the role and causal pathways of this phenomenon as a health determinant have not been widely studied. The present study was conducted between 2005 and 2008 in the Basque Region of Spain and aimed to estimate the health effects of collective violence on its primary victims.MethodsA purposive sample of 33 primary victims (direct victims of collective violence and the first degree relatives of murder victims) was matched (1:5 ratio) with a random selection of persons drawn from a representative sample of the population aged more than 16 years old living in the Basque Region. Matching criteria were age, sex, educational level and province of residence. All participants completed a questionnaire that included health status measures (WHO-DAS-II-12, GHQ-12, SF-12, loneliness and stigma scales) and other potentially mediating variables such as social support and emotional climate. The results were assessed by regression analysis conditional to exposure to collective violence.ResultsThe odds of perceiving worse physical and emotional health were 4 to 7 times higher among primary victims than among the general population and were 8 times higher for experiencing functional disability. Primary victims also perceived more loneliness and stigma and negatively valued their social support and emotional climate. No significant impact was found among the general population with some experience of interpersonal violence.ConclusionsThese results suggest that collective violence is associated with substantial impairment in health status. More specific studies to assess the health effects of collective violence in the general population are warranted

Estudio a corto plazo en artroplastia total de cadera no cementada con par de fricción cerámica-cerámica

Se revisan 38 prótesis con par de fricción cerámica-cerámica en 31 pacientes intervenidos durante los años 2000 a 2003. La edad media era de 47,3 años. La valoración clínica con la escala de Harris pasó de 53 puntos de media en el preoperatorio a 97 en el postoperatorio lo que permitió establecer un 76,3% de resultados excelentes y un 23,7 de buenos. No hemos podido constatar ninguna complicación asociada al par cerámica-cerámica. Los resultados iniciales con el par cerámica-cerámica son superponibles a otras pares de fricción, su utilización en implantes que han demostrado su eficacia con otros pares de fricción, la mejoría en la fabricación y la estricta observación de la técnica quirúrgica permite obviar el riesgo de fractura. Merced a su baja incidencia de desgaste y buen comportamiento biológico representa una alternativa real para su implantación en pacientes jóvenes o con una actividad elevada.From 2000 to 2003, 38 patients underwent ceramic on ceramic bearing total hip artrhoplasty. Mean age was 47.3 years. Clinical evaluation with the harris hip score increased from 53 points preoperatively to 97 postoperatively. There were no complications associated with ceramic on ceramic bearing.Initial results are similar to those found with others bearing surfaces. The use of ceramics in implants that have shown their effectiviness with others bearing surfaces, improvement in manufactured of the ceramics and a carefull surgery decreased the risk os fracture. Low incidence of wear debris and biological caracteristics makes ceramics a real alternative in young or high activity patients

Milky Way demographics with the VVV survey. IV. PSF photometry from almost one billion stars in the Galactic bulge and adjacent southern disk

Accepted for publication in a forthcoming issue of Astronomy & Astrophysics. Reproduced with permission from Astronomy & Astrophysics. © 2018 ESO.Context. The inner regions of the Galaxy are severely affected by extinction, which limits our capability to study the stellar populations present there. The Vista Variables in the Vía Láctea (VVV) ESO Public Survey has observed this zone at near-infrared wavelengths where reddening is highly diminished. Aims. By exploiting the high resolution and wide field-of-view of the VVV images we aim to produce a deep, homogeneous, and highly complete database of sources that cover the innermost regions of our Galaxy. Methods. To better deal with the high crowding in the surveyed areas, we have used point spread function (PSF)-fitting techniques to obtain a new photometry of the VVV images, in the ZY JHK s near-infrared filters available. Results. Our final catalogs contain close to one billion sources, with precise photometry in up to five near-infrared filters, and they are already being used to provide an unprecedented view of the inner Galactic stellar populations. We make these catalogs publicly available to the community. Our catalogs allow us to build the VVV giga-CMD, a series of color-magnitude diagrams of the inner regions of the Milky Way presented as supplementary videos. We provide a qualitative analysis of some representative CMDs of the inner regions of the Galaxy, and briefly mention some of the studies we have developed with this new dataset so far.Peer reviewe

Quality estimation of the electrocardiogram using cross-correlation among leads

Background Fast and accurate quality estimation of the electrocardiogram (ECG) signal is a relevant research topic that has attracted considerable interest in the scientific community, particularly due to its impact on tele-medicine monitoring systems, where the ECG is collected by untrained technicians. In recent years, a number of studies have addressed this topic, showing poor performance in discriminating between clinically acceptable and unacceptable ECG records. Methods This paper presents a novel, simple and accurate algorithm to estimate the quality of the 12-lead ECG by exploiting the structure of the cross-covariance matrix among different leads. Ideally, ECG signals from different leads should be highly correlated since they capture the same electrical activation process of the heart. However, in the presence of noise or artifacts the covariance among these signals will be affected. Eigenvalues of the ECG signals covariance matrix are fed into three different supervised binary classifiers. Results and conclusion The performance of these classifiers were evaluated using PhysioNet/CinC Challenge 2011 data. Our best quality classifier achieved an accuracy of 0.898 in the test set, while having a complexity well below the results of contestants who participated in the Challenge, thus making it suitable for implementation in current cellular devices.National Institute of General Medical Sciences (U.S.) (Grant R01GM104987)Spain (Research Grant TEC2013-46067-R)Spain (Research Grant TEC2013-48439-C4-1-R)Spain (Research Grant TEC2010-19263