On improving robustness of LDA and SRDA by using tangent vectors

This is the author’s version of a work that was accepted for publication in Pattern Recognition Letters. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Pattern Recognition Letters, [Volume 34, Issue 9, 1 July 2013, Pages 1094–1100] DOI: 10.1016/j.patrec.2013.03.001[EN] In the area of pattern recognition, it is common for few training samples to be available with respect to the dimensionality of the representation space; this is known as the curse of dimensionality. This problem can be alleviated by using a dimensionality reduction approach, which overcomes the curse relatively well. Moreover, supervised dimensionality reduction techniques generally provide better recognition performance; however, several of these tend to suffer from the curse when applied directly to high-dimensional spaces. We propose to overcome this problem by incorporating additional information to supervised subspace learning techniques using what is known as tangent vectors. This additional information accounts for the possible differences that the sample data can suffer. In fact, this can be seen as a way to model the unseen data and make better use of the scarce training samples. In this paper, methods for incorporating tangent vector information are described for one classical technique (LDA) and one state-of-the-art technique (SRDA). Experimental results confirm that this additional information improves performance and robustness to known transformations.Work partially supported through the EU 7th Framework Programme grant tranScriptorium (Ref: 600707), by the Spanish MEC under the STraDA research project (TIN2012-37475-C02-01) and by the Generalitat Valenciana under grant Prometeo/2009/014.Villegas Santamaría, M.; Paredes Palacios, R. (2013). On improving robustness of LDA and SRDA by using tangent vectors. Pattern Recognition Letters. 34(9):1094-1100. https://doi.org/10.1016/j.patrec.2013.03.0011094110034

Passive-Aggressive online learning with nonlinear embeddings

[EN] Nowadays, there is an increasing demand for machine learning techniques which can deal with problems where the instances are produced as a stream or in real time. In these scenarios, online learning is able to learn a model from data that comes continuously. The adaptability, efficiency and scalability of online learning techniques have been gaining interest last years with the increasing amount of data generated every day. In this paper, we propose a novel binary classification approach based on nonlinear mapping functions under an online learning framework. The non-convex optimization problem that arises is split into three different convex problems that are solved by means of Passive-Aggressive Online Learning. We evaluate both the adaptability and generalization of our model through several experiments comparing with the state of the art techniques. We improve significantly the results in several datasets widely used previously by the online learning community. (C) 2018 Elsevier Ltd. All rights reserved.This work was developed in the framework of the PROM-ETEOII/2014/030 research project "Adaptive learning and multi modality in machine translation and text transcription", funded by the Generalitat Valenciana. The work of the first author is financed by Grant FPU14/03981, from the Spanish Ministry of Education, Culture and Sport.Jorge-Cano, J.; Paredes Palacios, R. (2018). Passive-Aggressive online learning with nonlinear embeddings. Pattern Recognition. 79:162-171. https://doi.org/10.1016/j.patcog.2018.01.019S1621717

Study of Convolutional Neural Networks for Global Parametric Motion Estimation on Log-Polar Imagery

[EN] The problem of motion estimation from images has been widely studied in the past. Although many mature solutions exist, there are still open issues and challenges to be addressed. For instance, in spite of the well-known performance of convolutional neural networks (CNNs) in many computer vision problems, only very recent work has started to explore CNNs to learning to estimate motion, as an alternative to manually-designed algorithms. These few initial efforts, however, have focused on conventional Cartesian images, while other imaging models have not been studied. This work explores the yet unknown role of CNNs in estimating global parametric motion in log-polar images. Despite its favourable properties, estimating some motion components in this model has proven particularly challenging with past approaches. It is therefore highly important to understand how CNNs behave when their input are log-polar images, since they involve a complex mapping in the motion model, a polar image geometry, and space-variant resolution. To this end, a CNN is considered in this work for regressing the motion parameters. Experiments on existing image datasets using synthetic image deformations reveal that, interestingly, standard CNNs can successfully learn to estimate global parametric motion on log-polar images with accuracies comparable to or better than with Cartesian images.This work was supported in part by the Universitat Jaume I, Castellon, Spain, through the Pla de promocio de la investigacio, under Project UJI-B2018-44; and in part by the Spanish Ministerio de Ciencia, Innovacion y Universidades through the Research Network under Grant RED2018-102511-T.Traver, VJ.; Paredes Palacios, R. (2020). Study of Convolutional Neural Networks for Global Parametric Motion Estimation on Log-Polar Imagery. IEEE Access. 8:149122-149132. https://doi.org/10.1109/ACCESS.2020.3016030S149122149132

Estrés postraumático asociado a la participación en los conflicto bélicos del Ecuador en el siglo xx en los miembros de la asociación de comandos y/o paracaidistas en servicio activo y pasivo de las de las Fuerzas Armadas “Grad. Juan Francisco Donoso Game”

Materiales y métodos: La muestra fue tomada de ex combatientes de las guerras de 1941,1981, 1995 para lo cual se aplicó encuestas (Test del Trauma de Davidson y encuesta sociodemográfica) a 185 militares en servicio activo y pasivo. Se incluyeron preguntas para determinar la existencia de estrés post traumático y asociarlo con las variables sociodemográficas como son la edad, nivel de instrucción, estado civil y su condición militar, además de preguntas relacionadas con el combate bélico. Los datos obtenidos, fueron registrados, codificados y organizados en tablas de recolección; su análisis, se realizó mediante el uso del sistema SPSS 23 licencia PUCE. Resultados: La prevalencia alcanzo un valor de 73.5 % con intervalos de confianza que van 67.64 % y a 81.36% , según la clasificación de las etapas de la vida como indica la Organización mundial de la salud, se da a conocer que la población estudiada se encuentra en adultos jóvenes en un 43.8%, adultos medios en 38.4%, adultos posteriores en 13% y la senectud en un 9% se evidencio que el nivel de escolaridad máximo que alcanzaron los miembros de la asociaron fue de 10.3% corresponde a la primaria, 81.1 % correspondiente a la secundaria, 7% correspondiente a la universidad y 1.6 % al nivel de instrucción superior o post grado el estado civil actual no validada con la cedula de ciudadanía fue de casados 90.3% divorciados 3.8% unión de hecho 5.9% y no se reportó ningún caso de soltería o viudez. Sus creencias religiosas fueron 89,7% de los católicos, 8.1% de los cristianos evangélicos, 1.1 % de testigos de Jehová, 0.5 se autodenomina agnóstico y 0.5% se autodenominan ateos. La muestra consultada encuentra domiciliados en un 44.3% Pichincha, 15.1% Cotopaxi y 40.5% otras Provincias. Su rango o jerarquía militar máxima alcanzada hasta la actualidad o hasta su egreso es de 45.9% Sargento, 30.8 cabo, 14.6% sub oficial, 6.5% soldado, 1.1 % capitán 0.5% coronel y 0.5% general el descanso posterior a la guerra promedio de 10 días con una mediana de 8 días sin moda y una desviación estándar de 11 días teniendo en consideración que el mínimo fue de 0 días y el máximo de 60 días. el grupo no ningún ex combatiente de 1941, en cambio de 1981 se encontró un 10.8 %, de 1995 un 83.8 % y que han actuado en sendos combates 5.4%. No presentaron complicaciones físicas o psicológicas 87% miembros, mientras que 13% si presentaron. El tiempo que permanecían en conflicto bélico de forma activa fue en promedio de 68 días con una mediana de 60 días una moda de 30 días y una desviación estándar de 48 días, sabiendo que el mínimo de días fue de 3 y el máximo de 210 días Conclusiones: La asociación entre el trastorno de estrés post traumático y ex combatientes de las guerras del siglo XX en Ecuador presento una prevalencia de 73.5% según nuestra muestra desacuerdo al entrecruzamiento de variables únicamente la edad y la religión presentaron resultados estadísticamente significativos p=0.001 la edad se ha demostrado que es un factor de riesgo para el TEPT p=0.001. La jerarquía militar es un factor protector para el TEPT p=0.001.haber estado en 2 conflictos bélicos corresponde a un factor de riesgo para TEPT p=0.001. Se encontró datos estadísticamente significativos en la variable edad, por lo que no se pudo realizar la regresión logística binaria

Statistics of Core Lifetimes in Numerical Simulations of Turbulent, Magnetically Supercritical Molecular Clouds

We present measurements of the mean dense core lifetimes in numerical simulations of magnetically supercritical, turbulent, isothermal molecular clouds, in order to compare with observational determinations. "Prestellar" lifetimes (given as a function of the mean density within the cores, which in turn is determined by the density threshold n_thr used to define them) are consistent with observationally reported values, ranging from a few to several free-fall times. We also present estimates of the fraction of cores in the "prestellar", "stellar'', and "failed" (those cores that redisperse back into the environment) stages as a function of n_thr. The number ratios are measured indirectly in the simulations due to their resolution limitations. Our approach contains one free parameter, the lifetime of a protostellar object t_yso (Class 0 + Class I stages), which is outside the realm of the simulations. Assuming a value t_yso = 0.46 Myr, we obtain number ratios of starless to stellar cores ranging from 4-5 at n_thr = 1.5 x 10^4 cm^-3 to 1 at n_thr = 1.2 x 10^5 cm^-3, again in good agreement with observational determinations. We also find that the mass in the failed cores is comparable to that in stellar cores at n_thr = 1.5 x 10^4 cm^-3, but becomes negligible at n_thr = 1.2 x 10^5 cm^-3, in agreement with recent observational suggestions that at the latter densities the cores are in general gravitationally dominated. We conclude by noting that the timescale for core contraction and collapse is virtually the same in the subcritical, ambipolar diffusion-mediated model of star formation, in the model of star formation in turbulent supercritical clouds, and in a model intermediate between the previous two, for currently accepted values of the clouds' magnetic criticality.Comment: 25 pages, 8 figures, ApJ accepted. Fig.1 animation is at http://www.astrosmo.unam.mx/~e.vazquez/turbulence/movies/Galvan_etal07/Galvan_etal07.htm