Improving the Interpretability of Classification Rules Discovered by an Ant Colony Algorithm: Extended Results

The vast majority of Ant Colony Optimization (ACO) algorithms for inducing classification rules use an ACO-based procedure to create a rule in an one-at-a-time fashion. An improved search strategy has been proposed in the cAnt-MinerPB algorithm, where an ACO-based procedure is used to create a complete list of rules (ordered rules)-i.e., the ACO search is guided by the quality of a list of rules, instead of an individual rule. In this paper we propose an extension of the cAnt-MinerPB algorithm to discover a set of rules (unordered rules). The main motivations for this work are to improve the interpretation of individual rules by discovering a set of rules and to evaluate the impact on the predictive accuracy of the algorithm. We also propose a new measure to evaluate the interpretability of the discovered rules to mitigate the fact that the commonly-used model size measure ignores how the rules are used to make a class prediction. Comparisons with state-of-the-art rule induction algorithms, support vector machines and the cAnt-MinerPB producing ordered rules are also presented

A new sequential covering strategy for inducing classification rules with ant colony algorithms

Ant colony optimization (ACO) algorithms have been successfully applied to discover a list of classification rules. In general, these algorithms follow a sequential covering strategy, where a single rule is discovered at each iteration of the algorithm in order to build a list of rules. The sequential covering strategy has the drawback of not coping with the problem of rule interaction, i.e., the outcome of a rule affects the rules that can be discovered subsequently since the search space is modified due to the removal of examples covered by previous rules. This paper proposes a new sequential covering strategy for ACO classification algorithms to mitigate the problem of rule interaction, where the order of the rules is implicitly encoded as pheromone values and the search is guided by the quality of a candidate list of rules. Our experiments using 18 publicly available data sets show that the predictive accuracy obtained by a new ACO classification algorithm implementing the proposed sequential covering strategy is statistically significantly higher than the predictive accuracy of state-of-the-art rule induction classification algorithms

Evolving Recursive Programs using Non-recursive Scaffolding

Genetic programming has proven capable of evolving solutions to a wide variety of problems. However, the successes have largely been with programs without iteration or recursion; evolving recursive programs has turned out to be particularly challenging. The main obstacle to evolving recursive programs seems to be that they are particularly fragile to the application of search operators: a small change in a correct recursive program generally produces a completely wrong program. In this paper, we present a simple and general method that allows us to pass back and forth from a recursive program to an associated non-recursive program. Finding a recursive program can be reduced to evolving non-recursive programs followed by converting the optimum non-recursive program found to the associated optimum recursive program. This avoids the fragility problem above, as evolution does not search the space of recursive programs. We present promising experimental results on a test-bed of recursive problems

Uncertainty quantification to assess a reduced model for the remote heating of a polymer

This article studies the feasibility of a 1D radiative transfer model to compute the thermal source for a remote heating problem associated to the physics of the so-called plasmonic resonance (PR) in a synthetic polymeric material. The PR is responsible for converting the optical radiation from the incident laser beam into an equivalent thermal source and is achieved by embedding gold nanoparticles during the design of the synthetic polymer. Since the Radiative Transfer Equation cannot be analytically solved for a real experimental case, a two-staged simplified process is considered which requires the uncertainty quantification as a prior stage, in order to make an appropriate control of the resulting temperature profile. In this work, we include propagation errors for lattices of 1D, 2D and 3D geometries, due to the approximate laser source profile used, as well as those arisen from uncertainties in the thermal parameters and the ones derived from the variables involved in the design of the polymer. Computational simulations for a suitable experimental polymer are carried out using COMSOL®. Corresponding results show the scope of the reduced model in terms of a range of parameter values where it can be effectively used in practice.Publicado en: Mecánica Computacional vol. XXXV, no. 21Facultad de Ingenierí

Uncertainty quantification to assess a reduced model for the remote heating of a polymer

This article studies the feasibility of a 1D radiative transfer model to compute the thermal source for a remote heating problem associated to the physics of the so-called plasmonic resonance (PR) in a synthetic polymeric material. The PR is responsible for converting the optical radiation from the incident laser beam into an equivalent thermal source and is achieved by embedding gold nanoparticles during the design of the synthetic polymer. Since the Radiative Transfer Equation cannot be analytically solved for a real experimental case, a two-staged simplified process is considered which requires the uncertainty quantification as a prior stage, in order to make an appropriate control of the resulting temperature profile. In this work, we include propagation errors for lattices of 1D, 2D and 3D geometries, due to the approximate laser source profile used, as well as those arisen from uncertainties in the thermal parameters and the ones derived from the variables involved in the design of the polymer. Computational simulations for a suitable experimental polymer are carried out using COMSOL®. Corresponding results show the scope of the reduced model in terms of a range of parameter values where it can be effectively used in practice.Publicado en: Mecánica Computacional vol. XXXV, no. 21Facultad de Ingenierí

Uncertainty quantification to assess a reduced model for the remote heating of a polymer

This article studies the feasibility of a 1D radiative transfer model to compute the thermal source for a remote heating problem associated to the physics of the so-called plasmonic resonance (PR) in a synthetic polymeric material. The PR is responsible for converting the optical radiation from the incident laser beam into an equivalent thermal source and is achieved by embedding gold nanoparticles during the design of the synthetic polymer. Since the Radiative Transfer Equation cannot be analytically solved for a real experimental case, a two-staged simplified process is considered which requires the uncertainty quantification as a prior stage, in order to make an appropriate control of the resulting temperature profile. In this work, we include propagation errors for lattices of 1D, 2D and 3D geometries, due to the approximate laser source profile used, as well as those arisen from uncertainties in the thermal parameters and the ones derived from the variables involved in the design of the polymer. Computational simulations for a suitable experimental polymer are carried out using COMSOL®. Corresponding results show the scope of the reduced model in terms of a range of parameter values where it can be effectively used in practice.Publicado en: Mecánica Computacional vol. XXXV, no. 21Facultad de Ingenierí

Diagnóstico ecográfico en un caso clínico de quiste paraprostático canino

El artículo describe el diagnóstico ecográfico de un caso clínico de quiste paraprostático en un perro, discutiendo la importancia de la imagen en el diagnóstico de afecciones prostáticas y mostrando imágenes radiológicas y ecográficas.This paper describes the ultrasonographic diagnosis in a case of paraprostatic cyst in a dog. Importance of imaging diagnostic methods in prostatic diseases are discussed. Radiologic and ultrasound images are shown

Verificación artroscópica del diagnóstico por resonancia magnética de las lesiones meniscales

La utilización de la Imagen por Resonancia Magnética (IRM) como prueba diagnóstica en la patología de la rodilla, se presenta como alternativa no invasiva fundamental. Se ha diseñado un protocolo a doble ciego junto al servicio de radiodiagnóstico de nuestro hospital a través del cual se han evaluado un total de 31 pacientes donde los hallazgos de la IRM son contrastados con la exploración artroscópica posterior. Para el menisco interno, la precisión diagnóstica de la IRM es del 93 % y del 87% para el externo. Como conclusiones de mayor relieve, la sensibilidad de la exploración fue del 90% para el interno y del 75% para el externo y respecto a la especificidad, en el interno resultó ser del 100% y del 91% en el externo. Los valores predictivo negativo y positivo fueron respectivamente del 85 y 100% en el menisco interno y del 84 y 75% en el externo. Se encontró mayor dificultad diagnóstica en la porción anterior del menisco externo y falta de precisión ocasional en definir el tipo y extensión de la lesión.The use of Magnetic Resonance Imaging (MIR) as a diagnostic trial in the pathology of the knee, has become an important non invasive alternative. We have designed a double blind protocol with the Department of Radiology through we have evaluated 31 patients analyzing the MRI results in relation with the arthroscopic findings. For the medial meniscus, the accuracy of the MRI was 93 % and 87% for the lateral. As main conclusions, the sensibility was 90% for the medial meniscus and 75% for the lateral one and about specificity, we found a result of 100% for the medial meniscus and 91% for the lateral. The negative and positive predictive values were respectively 85% and 100% for the medial and 84% and 75% for the lateral. We noted more diagnostic difficulties in the anterior portion of lateral meniscus and lack of precission in the determination of the type and extension of the meniscal injury

Reconstrucción del ligamento cruzado anterior con plastia mixta de semitendinoso y fibra de Kennedy-Lad

—Se han evaluado los resultados de la reconstrucción del ligamento cruzado anterior (LCA) con una plastia mixta de tendón del semitendinoso y fibra sintética de KennedyLAD en veinticinco pacientes con un mínimo de dos años de seguimiento postoperatorio (media de treinta y ocho meses). Se trataba en todos los casos de lesiones crónicas donde la cirugía consistió en la reconstrucción del LCA y meniscectomías parciales cuando fueron necesarias. La evaluación se llevó a cabo mediante pruebas funcionales (Lysholm) y clínicas (Marshall), pruebas de estabilidad manual (Lachman, pivot, cajón neutro anterior), medidas instrumentales de estabilidad con artrómetro (KT-1000), índice de actividad y apreciación subjetiva. Los datos indican que el comportamiento de la plastia es adecuado en el 92% de los casos proporcionando a los pacientes una función articular satisfactoria en su vida diaria incluyendo la actividad deportiva.The authors assess the results of the anterior cruciate ligament (ACL) reconstruction by means of a semitendinous tendon and Kennedy LAD composite graft. Minimum followup has been two years (mean of thirty eight months). In every cases the lesion was considered as chronic and surgery consisted of ACL reconstruction and partial meniscectomy if neccessary. Studies performed to asses the results included: functional (Lysholm) and clinical (Marshall) tests, manual stability tests (Lachman, pivot-shift, neutral anterior drawer), instrumented stability measurement (KT-1000 arthrometer), activity score and subjective patient self-assessment. The data collected indicate that the performance of the composite graft is adequate in 92% of the cases, allowing the patients a satisfactory knee joint function in their daily life including sporting activities

Refactoring in Automatically Generated Programs

Refactoring aims at improving the design of ex- isting code by introducing structural modifications without changing its behaviour. It is used to adjust a system’s design in order to facilitate its maintenance and extendability. Since deciding which refactoring to apply and where it should be applied is not a straightforward decision, search-based approaches to automating the task of software refactoring have been proposed recently. So far, these approaches have been applied only to human-written code. Despite many years of computer programming experience, certain problems are very difficult for programmers to solve. To address this, researches have developed methods where computers automatically create program code from a description of the problem to be solved. One of the most popular forms of automated program creation is called Genetic Programming (GP). The aim of this work is to make GP more effective by introducing an automated refactoring step, based on the refactoring work in the software engineering community. We believe that the refactoring step will enhance the ability of GP to produce code that solves more complex problems, as well as result in evolved code that is both simpler and more idiomatically structured than that produced by traditional GP methods