A comparative evaluation of nonlinear dynamics methods for time series prediction

A key problem in time series prediction using autoregressive models is to fix the model order, namely the number of past samples required to model the time series adequately. The estimation of the model order using cross-validation may be a long process. In this paper, we investigate alternative methods to cross-validation, based on nonlinear dynamics methods, namely Grassberger-Procaccia, K,gl, Levina-Bickel and False Nearest Neighbors algorithms. The experiments have been performed in two different ways. In the first case, the model order has been used to carry out the prediction, performed by a SVM for regression on three real data time series showing that nonlinear dynamics methods have performances very close to the cross-validation ones. In the second case, we have tested the accuracy of nonlinear dynamics methods in predicting the known model order of synthetic time series. In this case, most of the methods have yielded a correct estimate and when the estimate was not correct, the value was very close to the real one

“El guapo” y “'O guarracino”: supervivencias de un personaje a ritmo de son jarocho y tarantela / “El guapo” y “O guarracino”: Survivals of a character to the rhythm of son jarocho and tarantela

El artículo compara dos piezas lírico-musicales anónimas, tradicionales en sus respectivas regiones de pertenencia: el son jarocho “El guapo”, del estado de Veracruz (México), y la tarantela “'O guarracino”, napolitana. La base de la comparación estriba en la supervivencia de un personaje de larga tradición, perteneciente al orbe cultural hispánico en toda su amplitud: el guapo/guappo, un personaje burlesco por jactancioso y fanfarrón, remedo y parodia del valiente. Se examinan las características del personaje en las dos composiciones, procedentes de dos lugares que en su momento pertenecieron muy claramente a dicho orbe cultural compartido, poniéndolas en relación con los tópicos y motivos literarios tradicionales que subyacen a su construcción, notando peculiaridades léxicas especialmente significativas, analizando los recursos formales que intervienen en la arquitectura de las piezas (como el paralelismo, la enumeración y la acumulación, la animalización). La comparación entre las dos composiciones evidencia una serie de analogías e incluso un diálogo entre los motivos que en ellas aparecen, comprobando su filiación compartida.The paper compares two poetical and musical anonymous pieces, each of them traditional in the region it belongs to: the son jarocho “El guapo”, from the state of Veracruz (Mexico), and the Neapolitan tarantella “'O guarracino”. The comparison is based on the persistence of a character that comes from a long tradition, belonging to the Hispanic cultural world at large: the guapo/guappo, a farcical figure – a braggard and a swashbuckler, mimic and parody of the brave man. The paper examines the characteristics of the guapo persona in both compositions, linking them to the traditional literary topoi and motifs underlying the character's construction, noting especially significant lexical peculiarities, analysing the formal features participating in the pieces' architecture (such as parallelism, enumeration and accumulation, animalization). The comparison between the two compositions highlights a series of analogies and a dialogue between the featured motifs, proving their shared filiation

“The Deepest and Widest Metaphor for Life” Re-visions of Christian Faith in Robert Penn Warren’s Later Poetry

While it would be foolish to assert that Warren was a committed Christian and unequivocal believer, a kind of tempered faith does exist in some of Warren’s poems from Now and Then: Poems 1976-1978. Manuscript revisions of “Amazing Grace in the Back Country” and “Heart of the Backlog” reveal Warren’s struggle to find faith, not his conviction of living in it. However, “Heart of Autumn,” the final poem in the volume, points to the conscious act of surrendering to the depth of theistic conflict in its preceding counterparts

Analysis of similarity measurements in CBIR using clustered tamura features for biomedical images

Content based image retrieval (CBIR) is an important research topic in many applications, in particular in the biomedical field. In this domain, the CBIR has the aim of helping to improve the diagnosis, retrieving images of patients for which a diagnosis has already been made, similar to the current image. The main issue of CBIR is the selection of the visual contents (feature descriptors) of the images to be extracted for a correct image retrieval. The second issue is the choice of the similarity measurement to use to compare the feature descriptors of the query image to ones of the other images of the database. This paper focuses on a comparison among different similarity measurements in CBIR, with particular interest to a biomedical images database. The adopted technique for CBIR is based on clustered Tamura features. The selected similarity measurements are used both to evaluate the adopted technique for CBIR and to estimate the stability of the results. A comparison with some methods in literature has been carried out, showing the best results for the proposed technique

Magnification Control in Winner Relaxing Neural Gas

An important goal in neural map learning, which can conveniently be accomplished by magnification control, is to achieve information optimal coding in the sense of information theory. In the present contribution we consider the winner relaxing approach for the neural gas network. Originally, winner relaxing learning is a slight modification of the self-organizing map learning rule that allows for adjustment of the magnification behavior by an a priori chosen control parameter. We transfer this approach to the neural gas algorithm. The magnification exponent can be calculated analytically for arbitrary dimension from a continuum theory, and the entropy of the resulting map is studied numerically conf irming the theoretical prediction. The influence of a diagonal term, which can be added without impacting the magnification, is studied numerically. This approach to maps of maximal mutual information is interesting for applications as the winner relaxing term only adds computational cost of same order and is easy to implement. In particular, it is not necessary to estimate the generally unknown data probability density as in other magnification control approaches.Comment: 14pages, 2 figure

A note on some mathematical models on the effects of Bt-maize exposure

Some mathematical models for the estimation of the effects of Cry1Ab and Cry1F Bt-maize exposure in the biodiversity are discussed. Novel results about these models are obtained and described in the note. The exact formula for the proportion of the population that suffers mortality exposed to Cry1Ab pollen, underlining its dependence on the margin from the Bt crop edge, is derived. In addition, regarding Cry1F pollen effects, it is proposed a procedure, using a probabilistic and statistical approach, that computes the width of the non Bt-stripes used as mitigation measures. Finally, it has been derived a lower bound, using probabilistic consideration, on the species sensitivity of Lepidoptera.Comment: 10 pages, 1 figure. Early draft of a paper accepted for publication on Environmental and Ecological Statistic

¡Aprender de las poblanas! Figuras, imaginarios y prácticas sociales en los versos alrededor del teatro entre los siglos XVIII y XIX

This paper examines different types of written poetic texts, both manuscript and printed, that circulated in various shapes, formats and media during the 18th century in New Spain. Beyond playscripts themselves, texts are related to the theatre of the time, to poems written by actors and other people in the trade, to showbiz gossip. From these texts emerge some figures and representations that conforms the New Spain social imaginary.Este artículo presenta diferentes textos poéticos, tanto impresos como manuscritos, que se divulgaron por distintos medios, formatos y soportes (entre los cuales el pliego de cordel) durante el siglo XVIII en la Nueva España. Más allá de los propios textos dramáticos, se trata de textos relacionados al teatro de la época, desde las ideas y concepciones acerca del mismo, hasta poemas escritos por la misma gente de teatro, pasando por chismes de la farándula. De dichos textos emergen algunas de las figuras y las representaciones que conforman el imaginario social que en ese momento rodeaba el teatro