A subsampling method for the computation of multivariate estimators with high breakdown point

All known robust location and scale estimators with high breakdown point for multivariate sample's are very expensive to compute. In practice, this computation has to be carried out using an approximate subsampling procedure. In this work we describe an alternative subsampling scheme, applicable to both the Stahel-Donoho estimator and the estimator based on the Minimum Volume Ellipsoid, with the property that the number of subsamples required is substantially reduced with respect to the standard subsampling procedures used in both cases. We also discuss some bias and variability properties of the estimator obtained from the proposed subsampling process

Using angles to identify concentrated multivariate outliers

This article describes a procedure for the detection of multivariate outliers based on the analysis of certain angular properties of the observations. The method is simple, exploratory in nature, and particularly well suited for the detection of concentrated contamination patterns, in which the outliers appear to form a cluster, separated from the sample. It is shown that it presents good properties for the identification of contaminations on high-dimensional sample spaces and for high contamination levels, including some cases in which methods based on robust estimators (the minimum covariance determinant and minimum volume ellipsoid estimators, the Stahel–Donoho estimator, or other recent proposals) may fail. The use of the procedure is illustrated through several examplesPublicad

The role of Libraries in Cultural Centres Abroad: an insight

This research paper sets up a typology of libraries managed by cultural centres abroad. Nearly 2,200 libraries linked to a dozen of different cultural organizations provide not only traditional services such as loan and access to printed and audiovisual materials but they also approach local citizens, offering help and services in matters of education, literacy, cooperation, social issues or development. These actions may fit under the label of cultural diplomacy actions. This paper analyses the relevance of those cultural centres and offers a classification through a table including networks of institutions of the thirty most significant cultural centres worldwide

Modelos de Refracción Astronómica

Se resumen en esta monografía la teoría básica sobre refracción astronómica para ser aplicada a observaciones topográficas a astros. Se comentan también los diferentes modelos matemáticos existentes hasta la fecha

What do researchers think about paying to publish open access – findings from a global survey

Through different mechanisms pay to publish models have been established globally as one of the key routes to the open access publication of academic research. This model has introduced new kinds of inequalities into scholarly communication, but to what extent to researchers perceive the problematic nature of these business models? Drawing on findings from an international survey, Francisco Segado-Boj, Juan-Jose Prieto-Gutierrez and Juan Martín-Quevedo explore attitudes towards the pay to publish model across different demographics

The role of libraries in cultural centres Abroad: an insight

This research paper sets up a typology of libraries managed by cultural centres abroad. Nearly 2,200 libraries linked to a dozen of different cultural organizations provide not only traditional services such as loan and access to printed and audiovisual materials but they also approach local citizens, offering help and services in matters of education, literacy, cooperation, social issues or development. These actions may fit under the label of cultural diplomacy actions. This paper analyses the relevance of those cultural centres and offers a classification through a table including networks of institutions of the thirty most significant cultural centres worldwide

Synovial chondromatosis of the temporomandibular joint

La condromatosis sinovial (CS) es una enfermedad de etiología desconocida, la cual pude definirse como un proceso benigno sinovial caracterizado por la formación de nódulos cartilaginosos metaplásicos dentro del tejido conectivo de las superficies articulares, se le considera un fenómeno metaplásico activo más que un proceso neoplásico; presenta una marcada preferencia por afectar a mujeres constituyendo casi el 70% de los casos reportados, el rango de edad es amplio y oscila entre los 18 y 75 años con una media de 44.6 años. Dentro de los principales hallazgos clínicos destacan: sintomatología dolorosa, presencia de crepitación, aumento de volumen y limitación de la apertura bucal. La CS es una entidad poco frecuente de la cual se han reportado no más de 75 casos en la literatura inglesa, sólo 66 de ellos comprobados histológicamente, la mayoría afectando principalmente grandes articulaciones como cadera, rodilla y hombro; pero si la frecuencia es rara en estas localizaciones, lo es más aún en la articulación temporomandibular. El objetivo del presente artículo es el de reportar un caso clínico a la vez que se realiza una breve revisión de la literatura

The role of libraries in cultural centres Abroad: an insight

This research paper sets up a typology of libraries managed by cultural centres abroad. Nearly 2,200 libraries linked to a dozen of different cultural organizations provide not only traditional services such as loan and access to printed and audiovisual materials but they also approach local citizens, offering help and services in matters of education, literacy, cooperation, social issues or development. These actions may fit under the label of cultural diplomacy actions. This paper analyses the relevance of those cultural centres and offers a classification through a table including networks of institutions of the thirty most significant cultural centres worldwide

Jumping over the paywall: Strategies and motivations for scholarly piracy and other alternatives

Despite the advance of the Open Access (OA) movement, most scholarly production can only be accessed through a paywall. We conduct an international survey among researchers (N=3,304) to measure the willingness and motivations to use (or not use) scholarly piracy sites, and other alternatives to overcome a paywall such as paying with their own money, institutional loans, just reading the abstract, asking the corresponding author for a copy of the document, asking a colleague to get the document for them, or searching for an OA version of the paper. We also explore differences in terms of age, professional position, country income level, discipline, and commitment to OA. The results show that researchers most frequently look for OA versions of the documents. However, more than 50% of the participants have used a scholarly piracy site at least once. This is less common in high-income countries, and among older and better-established scholars. Regarding disciplines, such services were less used in Life & Health Sciences and Social Sciences. Those who have never used a pirate library highlighted ethical and legal objections or pointed out that they were not aware of the existence of such libraries

Synthesis of Enantiopure Oxygen- and Nitrogen-Containing Heterocycles by Diastereoselective Ring-Closing Metathesis Reaction in Perhydro-1,3-benzoxazine Derivatives

Producción CientíficaDiastereoselective ring‐closing metathesis reactions on chiral trienic perhydro‐1,3‐benzoxazines derived from (−)‐8‐aminomenthol featuring two diastereotopic olefin chains is described. The diastereochemical outcome of the cyclization appeared to be dependent on the length and position of the olefin chains in perhydro‐1,3‐benzoxazine, the degree of substitution of the double bonds and the ruthenium catalyst used. After separation of the diastereomers, and removal of the chiral auxiliary, enantiopure oxygen‐ and nitrogen‐containing heterocycles were obtained.Ministerio de Economía, Industria y Competitividad (Project FEDER-CTQ2014-59870-P)Junta de Castilla y León (Ref. Project FEDER-VA115P17