An artifact in fits to conic-based surfaces

It is common in Physiological Optics to fit the corneal and the lens surfaces to conic-based surfaces (usually ellipse-based surfaces), obtaining their characteristic radius of curvature and asphericity. Here we show that the variation in radius and asphericity due to experimental noise is strongly correlated. This correlation is seen both in experimental data of the corneal topographer Pentacam and in simulations. We also show that the effect is a characteristic of the geometry of ellipses, and not restricted to any experimental device or fitting procedure.Comment: 5 pages, 5 figure

Los eventos distintivos en grandes destinos del turismo cultural. El caso del año Greco en Toledo (España)

Cultural tourism has really taken off in the last decade touristic destinies are now part of a highly competitive market. The heritage has turned into an economic asset. Generalization of its trading is now in place through various touristic products. This is the case of cultural events focusing tourism. Among them stand out hallmark events. These are exceptional events. They take place in order to improve the attractiveness and cost effectiveness of a touristic destination. These occurrences are an opportunity to organize them through remembrance services. In this article we go through hallmark events in main cultural touristic destinies. That´s the reason why we carry out a study in order to analyze later events after Greco´s death in the city of Toledo, the IV centenary of his death. The approach used consists of a literary revision, direct observation analyze sources of information and a poll amongst visitors and inhabitants. The results will show the great economic and touristic scope of the event. However among visitors, Greco´s year was a secondary reason to attend the venue. In the host community 40% of the inhabitants didn´t take part in the event.El turismo cultural se ha expandido en las últimas décadas. Los destinos turísticos son parte de un mercado altamente competitivo. El patrimonio se ha convertido en un valor económico. Se ha producido la generalización de su comercialización a través de distintos productos turísticos. Es el caso de los eventos culturales con vocación turística. Entre ellos, destacan los eventos distintivos (hallmark events). Son acontecimientos excepcionales. Se desarrollan para mejorar el atractivo y la rentabilidad de un destino. Las efemérides son una oportunidad para organizarlos mediante la celebración de conmemoraciones. En este artículo se analizan los eventos distintivos en grandes destinos del turismo cultural. Con este fin, se realiza un estudio de caso a través del análisis post evento del IV Centenario de la muerte del Greco en la ciudad de Toledo. La metodología empleada consta de la revisión literaria, de la observación directa, del estudio de fuentes y de una encuesta entre visitantes y residentes. Los resultados demostrarán el gran alcance económico y turístico del evento. Sin embargo, entre los visitantes, el Año Greco fue un motivo secundario para acudir al destino. En la comunidad anfitriona, el 40% de los residentes no participaron en el evento

A general trimming approach to robust Cluster Analysis

We introduce a new method for performing clustering with the aim of fitting clusters with different scatters and weights. It is designed by allowing to handle a proportion $\alpha$ of contaminating data to guarantee the robustness of the method. As a characteristic feature, restrictions on the ratio between the maximum and the minimum eigenvalues of the groups scatter matrices are introduced. This makes the problem to be well defined and guarantees the consistency of the sample solutions to the population ones. The method covers a wide range of clustering approaches depending on the strength of the chosen restrictions. Our proposal includes an algorithm for approximately solving the sample problem.Comment: Published in at http://dx.doi.org/10.1214/07-AOS515 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Rationale for Timing of Follow-Up Visits to Assess Gluten-Free Diet in Celiac Disease Patients Based on Data Mining

The assessment of compliance of gluten-free diet (GFD) is a keystone in the supervision of celiac disease (CD) patients. Few data are available documenting evidence-based follow-up frequency for CD patients. In this work we aim at creating a criterion for timing of clinical follow-up for CD patients using data mining. We have applied data mining to a dataset with 188 CD patients on GFD (75% of them are children below 14 years old), evaluating the presence of gluten immunogenic peptides (GIP) in stools as an adherence to diet marker. The variables considered are gender, age, years following GFD and adherence to the GFD by fecal GIP. The results identify patients on GFD for more than two years (41.5% of the patients) as more prone to poor compliance and so needing more frequent follow-up than patients with less than 2 years on GFD. This is against the usual clinical practice of following less patients on long term GFD, as they are supposed to perform better. Our results support different timing follow-up frequency taking into consideration the number of years on GFD, age and gender. Patients on long term GFD should have a more frequent monitoring as they show a higher level of gluten exposure. A gender perspective should also be considered as non-compliance is partially linked to gender in our results: Males tend to get more gluten exposure, at least in the cultural context where our study was carried out. Children tend to perform better than teenagers or adultMinisterio de Economía y Competitividad TIN2017-88209-C2-2-RJunta de Andalucía US-126334