Higher-order Cartan symmetries in k-symplectic field theory

For k-symplectic Hamiltonian field theories, we study infinitesimal transformations generated by certain kinds of vector fields which are not Noether symmetries, but which allow us to obtain conservation laws by means of a suitable generalization of the Noether theorem.Comment: 11 page

Singular Lagrangian Systems on Jet Bundles

The jet bundle description of time-dependent mechanics is revisited. The constraint algorithm for singular Lagrangians is discussed and an exhaustive description of the constraint functions is given. By means of auxiliary connections we give a basis of constraint functions in the Lagrangian and Hamiltonian sides. An additional description of constraints is also given considering at the same time compatibility, stability and second-order condition problems. Finally, a classification of the constraints in first and second class is obtained using a cosymplectic geometry setting. Using the second class constraints, a Dirac bracket is introduced, extending the well-known construction by Dirac.Comment: 65 pages. LaTeX fil

Unified formalism for higher-order non-autonomous dynamical systems

This work is devoted to giving a geometric framework for describing higher-order non-autonomous mechanical systems. The starting point is to extend the Lagrangian-Hamiltonian unified formalism of Skinner and Rusk for these kinds of systems, generalizing previous developments for higher-order autonomous mechanical systems and first-order non-autonomous mechanical systems. Then, we use this unified formulation to derive the standard Lagrangian and Hamiltonian formalisms, including the Legendre-Ostrogradsky map and the Euler-Lagrange and the Hamilton equations, both for regular and singular systems. As applications of our model, two examples of regular and singular physical systems are studied.Comment: 43 pp. We have corrected and clarified the statement of Propositions 2 and 3. A remark is added after Proposition

High-Speed Rail Versus Air Transportation: Case Study of Madrid–Barcelona, Spain.

Travel time savings, better quality of the supplied services, greater comfort for the users, and improved accessibility are the main factors of success of High Speed Rail(HSR)links. This paper presents the results from a revealed and stated preference survey conducted to both HSR and air transport users in the Madrid Barcelona corridor. The data gathered from the stated preference survey was used to calibrate a modal choice model aiming at explaining competition between HSR and air transportation in the corridor. From the model, the authors obtain that prices and service frequency are the most important variables to compete with the other mode. In addition, they found that check-in and security controls at the airport are a crucial variable for the users in their modal choice. Other policies, such as the improvement of parking facilities at the train stations, play a secondary role

The invasive species Asparagopsis taxiformis (Bonnemaisoniales, Rhodophyta) on Andalusian coast (Southern Spain): reproductive stages, new records and invaded communities

The invasive species Asparagopsis taxiformis (Bonnemaisoniales, Rhodophyta) on Andalusian coasts (Southern Spain): reproductive stages, new records and invaded communities.The present study provides new records from Andalusian coasts of the exotic invasive seaweed Asparagopsis taxiformis (Delile) Trevisan. These records demonstrate that A. taxiformis has rapidly and widely expanded its distribution range in this region, from Almería to Cádiz (Strait of Gibraltar).The latter locality may represent the western geographical limit of the species in the Mediterranean Sea. Spermatangial heads and cystocarps were observed in the collected gametophytes. Additionally, we report the first record of the tetrasporophytic stage, Falkenbergia hillebrandii (Bornet) Falkenberg from the Andalusian coast, although tetraspores were not encountered in these samples. Consequently, information on the affected communities and arguments for considering A. taxiformis as an invasive species in the Andalusian coast are provided.La especie invasora Asparagopsis taxiformis (Bonnemaisoniales, Rhodophyta) en las costas andaluzas (Sur de España): fases reproductivas, nuevas citas y comunidades invadidas. El presente trabajo aporta nuevas citas para las costas andaluzas de la especie exótica invasora de macroalga Asparagopsis taxiformis (Delile) Trevisan. Estas citas muestran que la especie ha aumentado ampliamente su área de distribución de manera rápida en esta región, desde Almería hasta Cádiz (Estrecho de Gibraltar). Esta última localidad representaría el límite occidental de la especie en el mar Mediterráneo. En las muestras recogidas de gametofitos se pudieron observar ramas espermatangiales y cistocarpos. Se aporta la primera cita del estadio tetrasporofítico, Falkenbergia hillebrandii (Bornet) Falkenberg en las costas andaluzas, aunque no se observaron tetrásporas en estas muestras. Se informa sobre las comunidades afectadas y se dan argumentos para considerar a A.taxiformis invasora en las costas andaluzas

Educación y cultura popular: ensayo sobre las posibilidades educativas del folklore andino

El presente estudio es el producto de un equipo de antropólogos y sociólogos que puede ser tomado como el resultado de un esfuerzo para esbozar un modelo de aplicación antropológico. Intenta buscar en el mundo andino los contenidos del desarrollo curricular, en función de su propia cosmovisión. Este trabajo trata de escapar a la orientación educativa de espíritu colonial; e intenta convertir a la escuela en un lugar de encuentro recreativo y respetuoso de culturas y hombres diferentes

Symmetries and conservation laws in the Gunther k-symplectic formalism of field theory

This paper is devoted to studying symmetries of k-symplectic Hamiltonian and Lagrangian first-order classical field theories. In particular, we define symmetries and Cartan symmetries and study the problem of associating conservation laws to these symmetries, stating and proving Noether's theorem in different situations for the Hamiltonian and Lagrangian cases. We also characterize equivalent Lagrangians, which lead to an introduction of Lagrangian gauge symmetries, as well as analyzing their relation with Cartan symmetries.Comment: 29 page

Contribution to the knowledge of flat bugs from the temperate south america (hemiptera: heteroptera)

New Aradidae findings as localities and provinces are given from Argentina. Mezira regularis Champion is mentioned for the first time for this country. This work includes a result of studied material of Aradidae that belongs to the Museo de La Plata and Fundacion Miguel Lillo (Argentina).Fil: Contreras, Eugenia Fernanda. Universidad Nacional de Jujuy. Instituto de Biología de la Altura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Neder de Román, L. E.. Universidad Nacional de Jujuy. Instituto de Biología de la Altura; ArgentinaFil: Coscarón, M. C.. Universidad Nacional de Jujuy. Instituto de Biología de la Altura; Argentin

Contribution to the knowledge of flat bugs from the temperate south america (hemiptera: heteroptera)

New Aradidae findings as localities and provinces are given from Argentina. Mezira regularis Champion is mentioned for the first time for this country. This work includes a result of studied material of Aradidae that belongs to the Museo de La Plata and Fundacion Miguel Lillo (Argentina).Fil: Contreras, Eugenia Fernanda. Universidad Nacional de Jujuy. Instituto de Biología de la Altura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Neder de Román, L. E.. Universidad Nacional de Jujuy. Instituto de Biología de la Altura; ArgentinaFil: Coscarón, M. C.. Universidad Nacional de Jujuy. Instituto de Biología de la Altura; Argentin