Time-dependent Mechanics and Lagrangian submanifolds of Dirac manifolds

A description of time-dependent Mechanics in terms of Lagrangian submanifolds of Dirac manifolds (in particular, presymplectic and Poisson manifolds) is presented. Two new Tulczyjew triples are discussed. The first one is adapted to the restricted Hamiltonian formalism and the second one is adapted to the extended Hamiltonian formalism

Memoria comercial y estudio sobre el desarrollo de los negocios.: Memoria comercial y estudio sobre el desarrollo de los negocios - Año 1932/1933 (28/06/1933)

Copia digital. Valladolid: : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-201

Symmetries in Classical Field Theory

The multisymplectic description of Classical Field Theories is revisited, including its relation with the presymplectic formalism on the space of Cauchy data. Both descriptions allow us to give a complete scheme of classification of infinitesimal symmetries, and to obtain the corresponding conservation laws.Comment: 70S05; 70H33; 55R10; 58A2

On the Hamilton-Jacobi Theory for Singular Lagrangian Systems

We develop a Hamilton-Jacobi theory for singular lagrangian systems using the Gotay-Nester-Hinds constraint algorithm. The procedure works even if the system has secondary constraints.Comment: 36 page

URLs can facilitate machine learning classification of news stories across languages and contexts

Comparative scholars studying political news content at scale face the challenge of addressing multiple languages. While many train individual supervised machine learning classifiers for each language, this is a costly and time-consuming process. We propose that instead of rely-ing on thematic labels generated by manual coding, researchers can use ‘distant’ labels created by cues in article URLs. Sections reflected in URLs (e.g., nytimes.com/politics/) can therefore help create training material for supervised machine learning classifiers. Using cues provided by news media organizations, such an approach allows for efficient political news identification at scale while facilitating imple-mentation across languages. Using a dataset of approximately 870,000 URLs of news-related content from four countries (Italy, Germany, Netherlands, and Poland), we test this method by providing a comparison to ‘classical’ supervised machine learning and a multilingual BERT model, across four news topics. Our results suggest that the use of URL section cues to distantly annotate texts provides a cheap and easy-to-implement way of classifying large volumes of news texts that can save researchers many valuable resources without having to sacrifice quality

ESTUDIO DEL COMPORTAMIENTO ESTRUCTURAL DE LOSAS MACIZAS DE CONCRETO REFORZADO PARA VIVIENDA

A partir de resultados analíticos de ejemplos ilustrativos y del reporte de características observadas, quedó demostradoque las losas macizas de concreto reforzado para vivienda no son diseñadas ni construidas adecuadamente en el ámbitode la zona de estudio, lo que explica los altos porcentajes de fallas observadas en servicio. Fue calculado el índice deconfiabilidad en seis viviendas representativas al considerar tres posibles escenarios de la corrosión del acero de refuerzo,con lo que se mostró un alto riesgo de falla o cuantiosas inversiones en mantenimiento. Se concluyó que para el correctodiseño de las losas deberá no sólo revisarse la resistencia a flexión sino principalmente controlar las deformacionesverticales, el agrietamiento por contracción y la permeabilidad, lo cual implica especificar un concreto denso y durable.Se presentan recomendaciones específicas

European nautical tourists: exploring destination image perceptions

Purpose – Nautical tourism is considered to be an under-exploited research area, if we take into account its evolution and growth prospects. This lack of knowledge is probably one of the main reasons the sector has not reached its maximum. The present paper aims at exploring the European nautical tourists´ perceptions of image, in relation to the type of nautical sport they carry out and the type of nautical destination they visit. Methodology – The research was conducted in the Canary Islands and Morocco during 2013 and 2014. The sample covered 433 European nautical tourists pursuing different nautical sports and was organised into two groups. Structured questionnaires with personal interviews were implemented. Choosing a mature nautical destination and an emerging one enriched the comparative approach for the study. The findings indicate there are clearly similar profiles amongst the groups of tourists visiting both regions, and that the perceived image varies between a nautical tourist doing sailing and a nautical tourist motivated by other nautical sports. The data analysis reveals that perceptions also vary according to the more intensive and extensive use of the destinations. Originality – This empirical study provides useful insights into the demand for nautical tourism, the perceptions and evaluations of the ports and marinas as well as the destinations themselves, which can be used as a guide for the tourism industry managers and the Government Authorities to develop more effective marketing and positioning strategies. The study of the destination image in nautical tourism is a contribution to the progress beyond the state of the sector