Visual Recognition and Categorization on the Basis of Similarities to Multiple Class Prototypes

To recognize a previously seen object, the visual system must overcome the variability in the object's appearance caused by factors such as illumination and pose. Developments in computer vision suggest that it may be possible to counter the influence of these factors, by learning to interpolate between stored views of the target object, taken under representative combinations of viewing conditions. Daily life situations, however, typically require categorization, rather than recognition, of objects. Due to the open-ended character both of natural kinds and of artificial categories, categorization cannot rely on interpolation between stored examples. Nonetheless, knowledge of several representative members, or prototypes, of each of the categories of interest can still provide the necessary computational substrate for the categorization of new instances. The resulting representational scheme based on similarities to prototypes appears to be computationally viable, and is readily mapped onto the mechanisms of biological vision revealed by recent psychophysical and physiological studies.

Evaluation of sets of oriented and non-oriented receptive fields as local descriptors

Local descriptors are increasingly used for the task of object recognition because of their perceived robustness with respect to occlusions and to global geometrical deformations. We propose a performance criterion for a local descriptor based on the tradeoff between selectivity and invariance. In this paper, we evaluate several local descriptors with respect to selectivity and invariance. The descriptors that we evaluated are Gaussian derivatives up to the third order, gray image patches, and Laplacian-based descriptors with either three scales or one scale filters. We compare selectivity and invariance to several affine changes such as rotation, scale, brightness, and viewpoint. Comparisons have been made keeping the dimensionality of the descriptors roughly constant. The overall results indicate a good performance by the descriptor based on a set of oriented Gaussian filters. It is interesting that oriented receptive fields similar to the Gaussian derivatives as well as receptive fields similar to the Laplacian are found in primate visual cortex.

Support Vector Machines: Training and Applications

The Support Vector Machine (SVM) is a new and very promising classification technique developed by Vapnik and his group at AT&T Bell Labs. This new learning algorithm can be seen as an alternative training technique for Polynomial, Radial Basis Function and Multi-Layer Perceptron classifiers. An interesting property of this approach is that it is an approximate implementation of the Structural Risk Minimization (SRM) induction principle. The derivation of Support Vector Machines, its relationship with SRM, and its geometrical insight, are discussed in this paper. Training a SVM is equivalent to solve a quadratic programming problem with linear and box constraints in a number of variables equal to the number of data points. When the number of data points exceeds few thousands the problem is very challenging, because the quadratic form is completely dense, so the memory needed to store the problem grows with the square of the number of data points. Therefore, training problems arising in some real applications with large data sets are impossible to load into memory, and cannot be solved using standard non-linear constrained optimization algorithms. We present a decomposition algorithm that can be used to train SVM's over large data sets. The main idea behind the decomposition is the iterative solution of sub-problems and the evaluation of, and also establish the stopping criteria for the algorithm. We present previous approaches, as well as results and important details of our implementation of the algorithm using a second-order variant of the Reduced Gradient Method as the solver of the sub-problems. As an application of SVM's, we present preliminary results we obtained applying SVM to the problem of detecting frontal human faces in real images.

La teoría de la justicia y la Corte Constitucional: el reconocimiento de los derechos humanos de las personas y parejas homosexuales en Colombia. Análisis de la jurisprudencia de constitucionalidad 1998 - 2009

El documento busca identificar hacia que tipo de solución al problema de la opresión de la población homosexual tienden los fundamentos teóricos de la jurisprudencia de constitucionalidad de la Corte Constitucional (1998 - 2009) que protege los Derechos Humanos de las personas y parejas homosexuales en Colombia, en términos de la teoría de la justicia desde la perspectiva del reconocimiento. Los pasos seguidos en esta investigación son: (i) identificación de las fuentes y formas de la opresión de la cual es víctima la población homosexual en occidente, (ii) identificación de la forma como ha operado dicha opresión —heteronormatividad— en Colombia, a través de un breve análisis del discurso jurídico, (iii) descripción de las soluciones que la teoría de la justicia como reconocimiento plantea al problema de la opresión de la población homosexual y, por último, (iv) análisis de los fundamentos teóricos de la jurisprudencia seleccionada a la luz de los criterios de la teoría de la justicia señalados. Como hipótesis se plantea que de las tres soluciones —afirmativa (política de la diferencia), transformativa (política queer) e intermedia (reforma no reformista) —, es la primera la que marca la tendencia.

WAIS seminar: Alan Walks Wales: Data and Challenges

Abstract This seminar is a research discussion around a very interesting problem, which may be a good basis for a WAISfest theme. A little over a year ago Professor Alan Dix came to tell us of his plans for a magnificent adventure:to walk all of the way round Wales - 1000 miles 'Alan Walks Wales'. The walk was a personal journey, but also a technological and community one, exploring the needs of the walker and the people along the way. Whilst walking he recorded his thoughts in an audio diary, took lots of photos, wrote a blog and collected data from the tech instruments he was wearing. As a result Alan has extensive quantitative data (bio-sensing and location) and qualitative data (text, images and some audio). There are challenges in analysing individual kinds of data, including merging similar data streams, entity identification, time-series and textual data mining, dealing with provenance, ontologies for paths, and journeys. There are also challenges for author and third-party annotation, linking the data-sets and visualising the merged narrative or facets of it.

Molecular basis of circadian behaviour Lecture

For BIOL2040. Originally in Blackboard and uploaded to Edshare for linking in Efolio site.

Implementación de sistemas de información en los procesos de logística inversa de los Sets Quirúrgicos de Ortopedia

El presente documento es el producto de un análisis en cuanto al área de Logística Inversa del grupo empresarial AMAREY, el cual cuenta en la actualidad con más de dieciséis sistemas de sets quirúrgicos de ortopedia, es decir: sistema para mano, pie, radio, cadera, tibia, hombro, entre otros; de los cuales se tienen una cantidad específica de cada sistema, es decir: 4 sets del sistema Axsos. Se encuentra que la compañía no cuenta con ningún tipo de ayuda que le pueda brindar información exacta y a tiempo sobre las entradas y las salidas de los equipos de cirugía. Por lo anterior el resultado de la investigación está orientada a proponer la implementación de sistemas de información en los proceso de logística inversa de los sets quirúrgicos de ortopedia, con el fin de obtener una mejor gestión de la calidad al realizar la trazabilidad del material crítico y del set en general.

Aspectos jurídico administrativos de los desastres naturales y del reasentamiento poblaciónal y su planteamiento como política pública

Esta investigación tiene el propósito de analizar los aspectos jurídicos de los desastres naturales y del reasentamiento poblacional. Se presentan las distintas tipologías del reasentamiento poblacional desde la óptica estatal para señalar su importancia en las actividades de las autoridades administrativas. En el trabajo se muestra la vulnerabilidad del Estado Colombiano frente a la ocurrencia de desastres naturales, por la falta de planeación efectiva y la poca importancia de la reducción del riesgo en la agenda pública. Desarrolla igualmente, el fundamento de la responsabilidad de la administración frente a desastres de la naturaleza y su papel ante la protección de los derechos humanos. Además, desarrolla el reasentamiento poblacional como mecanismo de atención y prevención de desastres naturales, y la normatividad nacional y de la región andina en la cual está contenido. Establece estrategias de acción estatal para la atención práctica de los desastres naturales, el planteamiento del reasentamiento poblacional como política pública y herramientas de protección de la población vulnerable. Por último, plantea la importancia de la reducción de los riesgos de la población ante desastres de la naturaleza y la necesidad de protección del Estado de las poblaciones vulnerables para mejorar sus condiciones de vida.

Is there a common genetic basis for autoimmune diseases?

Autoimmune diseases (ADs) represent a diverse collection of diseases in terms of their demographic profile and primary clinical manifestations. The commonality between them however, is the damage to tissues and organs that arises from the response to self-antigens. The presence of shared pathophysiological mechanisms within ADs has stimulated searches for common genetic roots to these diseases. Two approaches have been undertaken to sustain the “common genetic origin” theory of ADs. Firstly, a clinical genetic analysis showed that autoimmunity aggregates within families of probands diagnosed with primary Sjögren's (pSS) syndrome or type 1 diabetes mellitus (T1D). A literature review supported the establishment of a familiar cluster of ADs depending upon the proband's disease phenotype. Secondly, in a same and well-defined population, a large genetic association study indicated that a number of polymorphic genes (i.e. HLA-DRB1, TNF and PTPN22) influence the susceptibility for acquiring different ADs. Likewise, association and linkage studies in different populations have revealed that several susceptibility loci overlap in ADs, and clinical studies have shown that frequent clustering of several ADs occurs. Thus, the genetic factors for ADs consist of two types: those which are common to many ADs (acting in epistatic pleitropy) and those that are specific to a given disorder. Their identification and functional characterization will allow us to predict their effect as well as to indicate potential new therapeutic interventions. Both autoimmunity family history and the co-occurrence of ADs in affected probands should be considered when performing genetic association and linkage studies.

Genetic basis of Sjögren's syndrome. How strong is the evidence?

Sjögren's syndrome (SS) is a late-onset chronic autoimmune disease (AID) affecting the exocrine glands, mainly the salivary and lachrymal. Genetic studies on twins with primary SS have not been performed, and only a few case reports describing twins have been published. The prevalence of primary SS in siblings has been estimated to be 0.09% while the reported general prevalence of the disease is approximately 0.1%. The observed aggregation of AIDs in families of patients with primary SS is nevertheless supportive for a genetic component in its etiology. In the absence of chromosomal regions identified by linkage studies, research has focused on candidate gene approaches (by biological plausibility) rather than on positional approaches. Ancestral haplotype 8.1 as well as TNF, IL10 and SSA1 loci have been consistently associated with the disease although they are not specific for SS. In this review, the genetic component of SS is discussed on the basis of three known observations: (a) age at onset and sex-dependent presentation, (b) familial clustering of the disease, and (c) dissection of the genetic component. Since there is no strong evidence for a specific genetic component in SS, a large international and collaborative study would be suitable to assess the genetics of this disorder.

Biological Basis and Clinical Application of Serum Tumor Markers

Cancer is the result of the accumulation of changes in molecules with important functions in processes such as cell proliferation, apoptosis, cell death and gene repair. Molecules, substances or altered pathways constitute tumor markers or biomarkers useful in clinical monitoring of cancer patients, because they have demonstrated to be suitable for the valuation of the patient’s treatment and it efficiency. Determination of tumor markers has not been very successful due to the low sensitivity and specificity of the techniques used and the requirement of large volumes of biological samples or the use of invasive methods for collecting them. The serum tumor markers arise, as a useful tool to obtain information about the disease progress and constitute as a scientific challenge to improve its applicability in early diagnosis, prognosis, monitoring of the disease and evaluation of therapeutic efficacy.

Factores asociados a recaída en pacientes con cáncer de mama de una institución de Bogotá

Introducción: El cáncer de seno es la primera causa de cáncer entre las mujeres, además es la primera causa de muerte por cáncer entre las hispanas y la segunda entre otras razas, sin contar con el gran impacto social y económico que conlleva esta patología. Esto motiva la realización de estudios propios, que permitan ampliar nuestro conocimiento y aportar a la literatura colombiana, una publicación que refleje los factores asociados a la recaída en el cáncer de mama. Métodos: Estudio observacional analítico retrospectivo de casos y controles en el que se tomaron 267 historias clínicas de pacientes con diagnóstico de cáncer de seno, clasificadas según estadio clínico y expresión molecular del tumor, se analizaron los factores más fuertemente asociados a la recaída. Resultados: La población total consistió en 267 mujeres de las cuales 58 presentaron recaída, con un relación caso – control, 1:3. Al evaluar los grupos se evidencia homogeneidad en cuanto a edad, tipo de neoplasia, paridad e histología con lo que concluimos que estos grupos son comparables. Se presentó una tasa de mortalidad de 13,8 % en las pacientes que presentaron recaída tumoral vs un 0% de mortalidad en aquellas pacientes sin recaída. Adicionalmente se evidencia una relación entre la presencia del receptor HER 2 y recaída tumoral, que aunque no es estadísticamente significativa (p = 0.112) es importante tener en cuenta por su significancia clínica. Por su parte la presencia de receptor de estrógenos y progestágenos no es un predictor de recaída. La realización de cirugía se muestra como un factor de protección (OAR: 0.046 p = 0.008). Finalmente se encontró una asociación estadísticamente significativa como variables de asociación a recaída tumoral: la edad (p=0.009), el estadio clínico en el momento del diagnóstico (p= <0.001) y la clasificación molecular del tumor (p= 0.016). Conclusiones: Se identificaron como factores asociados a recaída tumoral en pacientes con cáncer de mama de una institución de Bogotá, Colombia a: la edad, el estadio clínico en el momento del diagnóstico y la clasificación molecular del tumor, confirmando la agresividad de los tumores triple negativos. Todos los hallazgos son compatibles a lo descrito en la literatura mundial. Esto permite definir la necesidad de generar en nuestro país estrategias de salud pública, que permitan la educación a todos los grupos etarios para el tamizaje en población joven que está siendo afectada, la detección en estadios tempranos del cáncer de mama, asociados a priorización del manejo y mejoras en la ruta de atención de las pacientes que permitan impactar positivamente en el desenlace y calidad de vida de las mujeres con esta patología. Adicionalmente estos resultados impulsan a la continua investigación de nuevas tecnologías y medicamentos que permitan combatir los tumores más agresivos molecularmente hablando.

Confidence sets for asset correlations in portfolio credit risk

Asset correlations are of critical importance in quantifying portfolio credit risk and economic capitalin financial institutions. Estimation of asset correlation with rating transition data has focusedon the point estimation of the correlation without giving any consideration to the uncertaintyaround these point estimates. In this article we use Bayesian methods to estimate a dynamicfactor model for default risk using rating data (McNeil et al., 2005; McNeil and Wendin, 2007).Bayesian methods allow us to formally incorporate human judgement in the estimation of assetcorrelation, through the prior distribution and fully characterize a confidence set for the correlations.Results indicate: i) a two factor model rather than the one factor model, as proposed bythe Basel II framework, better represents the historical default data. ii) importance of unobservedfactors in this type of models is reinforced and point out that the levels of the implied asset correlationscritically depend on the latent state variable used to capture the dynamics of default,as well as other assumptions on the statistical model. iii) the posterior distributions of the assetcorrelations show that the Basel recommended bounds, for this parameter, undermine the levelof systemic risk.

Language teaching : theoretical basis and curricular design.

Este libro intenta ofrecer una panorámica diferente de la enseñanza de idiomas y llenar el vacío con el que con mucha frecuencia se encuentran los opositores al cuerpo de Enseñanza de Escuelas Oficiales de Idiomas y de Secundaria cuando deciden buscar información sobre un amplio temario. Esta obra combina una base teórica, que cubre aspectos sobre las teorías del lenguaje y de la enseñanza, con un diseño curricular práctico. La primera parte consta de cuatro bloques: 1) El proceso de comunicación, funciones del lenguaje y comunicación oral y escrita. 2) Competencia comunicativa y enseñanza comunicativa del inglés. 3) Teorías sobre el aprendizaje y la adquisición de un idioma extranjero, el concepto de interlenguaje y el tratamiento de error. 4) Evolución de la enseñanza de idiomas. La segunda parte trata del diseño curricular: los objetivos principales que se persiguen en la enseñanza de un idioma, los contenidos, la metodología a seguir con los estudiantes y criterios de evaluación. Es un tratado basado en la propia experiencia personal de la autora como profesora de inglés.

Basis set superposition error-counterpoise corrected potential energy surfaces : application to hydrogen peroxide ... X (X=F-, Cl-, Br-, Li+, Na+) complexes

Møller-Plesset (MP2) and Becke-3-Lee-Yang-Parr (B3LYP) calculations have been used to compare the geometrical parameters, hydrogen-bonding properties, vibrational frequencies and relative energies for several X- and X+ hydrogen peroxide complexes. The geometries and interaction energies were corrected for the basis set superposition error (BSSE) in all the complexes (1-5), using the full counterpoise method, yielding small BSSE values for the 6-311 + G(3df,2p) basis set used. The interaction energies calculated ranged from medium to strong hydrogen-bonding systems (1-3) and strong electrostatic interactions (4 and 5). The molecular interactions have been characterized using the atoms in molecules theory (AIM), and by the analysis of the vibrational frequencies. The minima on the BSSE-counterpoise corrected potential-energy surface (PES) have been determined as described by S. Simón, M. Duran, and J. J. Dannenberg, and the results were compared with the uncorrected PES