CEIP El Monte robotizado

Se presenta la preparaci??n del alumnado para su participaci??n en la 1.?? competici??n de robots celebrada en Canarias. Se muestra el desarrollo y resultado de una iniciativa de innovaci??n educativa motivadora para el centro, que permiti?? la adquisici??n de diversas competencias b??sicas y aprendizajes, previstos y no previstos, de gran valor educativo. La actividad implic?? tareas de dise??o, montaje, investigaci??n, programaci??n, exposici??n y evaluaci??n, comprobando si las construcciones permit??an la realizaci??n completa de las pruebas demandadas en la competici??n. Se ejecutaron los mismos pasos que los efectuados en una empresa de ingenier??a cuando crea una m??quina para la soluci??n de uno o varios problemas.

A Monte Carlo method for accelerating the computation of animated radiosity sequences

Realistic rendering animation is known to be an expensive processing task when physically-based global illumination methods are used in order to improve illumination details. This paper presents an acceleration technique to compute animations in radiosity environments. The technique is based on an interpolated approach that exploits temporal coherence in radiosity. A fast global Monte Carlo pre-processing step is introduced to the whole computation of the animated sequence to select important frames. These are fully computed and used as a base for the interpolation of all the sequence. The approach is completely view-independent. Once the illumination is computed, it can be visualized by any animated camera. Results present significant high speed-ups showing that the technique could be an interesting alternative to deterministic methods for computing non-interactive radiosity animations for moderately complex scenarios

A Monte Carlo-Based Fiber Tracking Algorithm using Diffusion Tensor MRI

Diffusion tensor magnetic resonance imaging, which measures directional information of water diffusion in the brain, has emerged as a powerful tool for human brain studies. In this paper, we introduce a new Monte Carlo-based fiber tracking approach to estimate brain connectivity. One of the main characteristics of this approach is that all parameters of the algorithm are automatically determined at each point using the entropy of the eigenvalues of the diffusion tensor. Experimental results show the good performance of the proposed approach

Error and complexity of random walk Monte Carlo radiosity

The author studies the error and complexity of the discrete random walk Monte Carlo technique for radiosity, using both the shooting and gathering methods. The author shows that the shooting method exhibits a lower complexity than the gathering one, and under some constraints, it has a linear complexity. This is an improvement over a previous result that pointed to an O(n log n) complexity. The author gives and compares three unbiased estimators for each method, and obtains closed forms and bounds for their variances. The author also bounds the expected value of the mean square error (MSE). Some of the results obtained are also shown

Entre el santo y el rey: los festejos realizados en Quito en el año de 1603 por la Canonización de San Raimundo de Peñafort

Esta tesis estudia las festividades que se celebraron en Quito por la canonización de San Raimundo de Peñafort en 1603. Su propósito fundamental es abordar el tema desde una propuesta de análisis a través de la cual sea posible analizar tanto los conflictos que se sucedieron en ellas. Así como los procesos de conformación de identidades individuales o colectivas que se generaron en estas fiestas. En la fiesta de San Raimundo, se pretendió construir una memoria colectiva para todos los quiteños a partir de la jerarquización social colonial que primaba en la época, donde la clasificación social a partir de elementos étnicos tenía mucha importancia; de la religiosidad militante del catolicismo de la Contrarreforma y de una mentalidad de la fiesta en la que el exceso y el derroche cobraban mayor importancia que el ahorro y la mesura. No obstante, esta memoria no era estable ni permanente porque en ella se hacía presente el conflicto social en toda su intensidad y complejidad. El conflicto social que se manifiesta con mayor claridad en la fiesta que se estudia es el que se existía entre el poder local y el poder central; es decir entre criollos y la Corona española. Sin embargo, esto no significa que entre las élites locales y los demás sectores de la sociedad colonial no se hubiera presentado conflictos; pero lastimosamente las fuentes disponibles solo permiten apreciar el conflicto antes mencionado, ya que ellas fueron escritas por personas totalmente vinculadas a los intereses de las élites locales o de los criollos.

Literatura y memoria en El monte, de Lydia Cabrera

Este trabajo hace una reflexión acerca de El monte, obra de la autora cubana Lydia Cabrera, publicada en 1954. Se trata de un texto de gran importancia para el folklor y la tradición oral del pueblo cubano, muy en especial para la cultura afrocubana, pues la autora rescató, de los últimos descendientes de los negros de nación, el caudal de leyendas, tradiciones, creencias, magia y supersticiones que estos hombres y mujeres conservaban de la lejana África. Debido a la cuantiosa y diversa información que nos ofrece el libro, es que éste ha sido concebido como texto híbrido, polifónico y heterogéneo que, en correspondencia con sus múltiples facetas escriturarias, ofrece múltiples posibilidades de lecturas. Ante esta disyuntiva, hemos optado por escoger dos entre las numerosas lecturas, la literaria y la de la memoria. En cuanto a la literatura, el trabajo analiza el valor de la obra a partir de los contextos de elaboración y recepción. Lydia elabora el texto como narradora ficcionalizada, cuya voluntad es narrar, hacer grato lo que cuenta, interpretar, dar sentido a los testimonios que ha escuchado de sus informantes, y de la misma forma pueden ser recibidos éstos: tanto el lector familiarizado con los temas como el ajeno a ellos, leen el texto como una ficción que tiene su referente en fenómenos culturales. Por otra parte, al ahondar en la memoria de sus informantes, L. Cabrera se percata de la existencia de una serie de núcleos de resistencia, de ordenamientos secretos que reproducen creencias, tradiciones que datan de la época colonial y se mantienen hasta nuestros días; ellas son las casas- templos en el caso de la Regla de Ocha o Santería y la Regla Conga o de Palo Monte y la Sociedad Secreta Abakuá. Para anoticiarnos de estas instituciones, la escritora explora, en su propio beneficio, tres de las propiedades de la memoria, (variabilidad, selectividad y significación), que le dan sentido a lo escrito. Al finalizar su recorrido por este mundo mágico de los negros, la investigadora nos revela su vinculación espiritual con el objeto de su investigación y su viaje se nos presenta como una verdadera travesía transcultural.

La canonización de Raimundo de Peñafort en Quito. Un ritual barroco entre la exhibición y el ocultamiento (1603) [Estudios]

Tomando como caso de estudio los festejos en honor de la canonización de Raimundo de Peñafort en Quito, en 1603, el artículo ofrece una reflexión alrededor de la cultura barroca en Hispanoamérica desde el punto de vista de la soberanía. El texto muestra cómo las élites quiteñas se apropiaron de las festividades organizadas en Quito en honor al santo catalán. Los criollos utilizaron las celebraciones en honor a San Raimundo como una estrategia política para solicitar a la Corona que deroguen los castigos impuestos a la ciudad luego de la Rebelión de las Alcabalas (1593).

Monte Carlo phase diagram for diblock copolymer melts

A partial phase diagram is constructed for diblock copolymer melts using lattice-based Monte Carlo simulations. This is done by locating the order-disorder transition (ODT) with the aid of a recently proposed order parameter and identifying the ordered phase over a wide range of copolymer compositions (0.2 <= f <= 0.8). Consistent with experiments, the disordered phase is found to exhibit direct first-order transitions to each of the ordered morphologies. This includes the spontaneous formation of a perforated-lamellar phase, which presumably forms in place of the gyroid morphology due to finite-size and/or nonequilibrium effects. Also included in our study is a detailed examination of disordered cylinder-forming (f=0.3) diblock copolymers, revealing a substantial degree of pretransitional chain stretching and short-range order that set in well before the ODT, as observed previously in analogous studies on lamellar-forming (f=0.5) molecules. (c) 2006 American Institute of Physics.

Monte Carlo phase diagram for diblock copolymer melts

The phase diagram for diblock copolymer melts is evaluated from lattice-based Monte Carlo simulations using parallel tempering, improving upon earlier simulations that used sequential temperature scans. This new approach locates the order-disorder transition (ODT) far more accurately by the occurrence of a sharp spike in the heat capacity. The present study also performs a more thorough investigation of finite-size effects, which reveals that the gyroid (G) morphology spontaneously forms in place of the perforated-lamellar (PL) phase identified in the earlier study. Nevertheless, there still remains a small region where the PL phase appears to be stable. Interestingly, the lamellar (L) phase next to this region exhibits a small population of transient perforations, which may explain previous scattering experiments suggesting a modulated-lamellar (ML) phase.

Modelling heterotachy in phylogenetic inference by reversible-jump Markov chain Monte Carlo

The rate at which a given site in a gene sequence alignment evolves over time may vary. This phenomenon-known as heterotachy-can bias or distort phylogenetic trees inferred from models of sequence evolution that assume rates of evolution are constant. Here, we describe a phylogenetic mixture model designed to accommodate heterotachy. The method sums the likelihood of the data at each site over more than one set of branch lengths on the same tree topology. A branch-length set that is best for one site may differ from the branch-length set that is best for some other site, thereby allowing different sites to have different rates of change throughout the tree. Because rate variation may not be present in all branches, we use a reversible-jump Markov chain Monte Carlo algorithm to identify those branches in which reliable amounts of heterotachy occur. We implement the method in combination with our 'pattern-heterogeneity' mixture model, applying it to simulated data and five published datasets. We find that complex evolutionary signals of heterotachy are routinely present over and above variation in the rate or pattern of evolution across sites, that the reversible-jump method requires far fewer parameters than conventional mixture models to describe it, and serves to identify the regions of the tree in which heterotachy is most pronounced. The reversible-jump procedure also removes the need for a posteriori tests of 'significance' such as the Akaike or Bayesian information criterion tests, or Bayes factors. Heterotachy has important consequences for the correct reconstruction of phylogenies as well as for tests of hypotheses that rely on accurate branch-length information. These include molecular clocks, analyses of tempo and mode of evolution, comparative studies and ancestral state reconstruction. The model is available from the authors' website, and can be used for the analysis of both nucleotide and morphological data.

Inference on microsatellite mutation processes in the invasive mite, Varroa destructor, using reversible jump Markov chain Monte Carlo

Varroa destructor is a parasitic mite of the Eastern honeybee Apis cerana. Fifty years ago, two distinct evolutionary lineages (Korean and Japanese) invaded the Western honeybee Apis mellifera. This haplo-diploid parasite species reproduces mainly through brother sister matings, a system which largely favors the fixation of new mutations. In a worldwide sample of 225 individuals from 21 locations collected on Western honeybees and analyzed at 19 microsatellite loci, a series of de novo mutations was observed. Using historical data concerning the invasion, this original biological system has been exploited to compare three mutation models with allele size constraints for microsatellite markers: stepwise (SMM) and generalized (GSM) mutation models, and a model with mutation rate increasing exponentially with microsatellite length (ESM). Posterior probabilities of the three models have been estimated for each locus individually using reversible jump Markov Chain Monte Carlo. The relative support of each model varies widely among loci, but the GSM is the only model that always receives at least 9% support, whatever the locus. The analysis also provides robust estimates of mutation parameters for each locus and of the divergence time of the two invasive lineages (67,000 generations with a 90% credibility interval of 35,000-174,000). With an average of 10 generations per year, this divergence time fits with the last post-glacial Korea Japan land separation. (c) 2005 Elsevier Inc. All rights reserved.

Bayesian analysis of correlated evolution of discrete characters by reversible-jump Markov chain Monte Carlo

We describe a Bayesian method for investigating correlated evolution of discrete binary traits on phylogenetic trees. The method fits a continuous-time Markov model to a pair of traits, seeking the best fitting models that describe their joint evolution on a phylogeny. We employ the methodology of reversible-jump ( RJ) Markov chain Monte Carlo to search among the large number of possible models, some of which conform to independent evolution of the two traits, others to correlated evolution. The RJ Markov chain visits these models in proportion to their posterior probabilities, thereby directly estimating the support for the hypothesis of correlated evolution. In addition, the RJ Markov chain simultaneously estimates the posterior distributions of the rate parameters of the model of trait evolution. These posterior distributions can be used to test among alternative evolutionary scenarios to explain the observed data. All results are integrated over a sample of phylogenetic trees to account for phylogenetic uncertainty. We implement the method in a program called RJ Discrete and illustrate it by analyzing the question of whether mating system and advertisement of estrus by females have coevolved in the Old World monkeys and great apes.

Detecting recombination in 4-taxa DNA sequence alignments with Bayesian hidden Markov models and Markov chain Monte Carlo

This article presents a statistical method for detecting recombination in DNA sequence alignments, which is based on combining two probabilistic graphical models: (1) a taxon graph (phylogenetic tree) representing the relationship between the taxa, and (2) a site graph (hidden Markov model) representing interactions between different sites in the DNA sequence alignments. We adopt a Bayesian approach and sample the parameters of the model from the posterior distribution with Markov chain Monte Carlo, using a Metropolis-Hastings and Gibbs-within-Gibbs scheme. The proposed method is tested on various synthetic and real-world DNA sequence alignments, and we compare its performance with the established detection methods RECPARS, PLATO, and TOPAL, as well as with two alternative parameter estimation schemes.