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

Pre-multisymplectic constraint algorithm for field theories

We present a geometric algorithm for obtaining consistent solutions to systems of partial differential equations, mainly arising from singular covariant first-order classical field theories. This algorithm gives an intrinsic description of all the constraint submanifolds. The field equations are stated geometrically, either representing their solutions by integrable connections or, what is equivalent, by certain kinds of integrable m-vector fields. First, we consider the problem of finding connections or multivector fields solutions to the field equations in a general framework: a pre-multisymplectic fibre bundle (which will be identified with the first-order jet bundle and the multimomentum bundle when Lagrangian and Hamiltonian field theories are considered). Then, the problem is stated and solved in a linear context, and a pointwise application of the results leads to the algorithm for the general case. In a second step, the integrability of the solutions is also studied. Finally, the method is applied to Lagrangian and Hamiltonian field theories and, for the former, the problem of finding holonomic solutions is also analized.Comment: 30 pp. Presented in the International Workshop on Geometric Methods in Modern Physics (Firenze, April 2005

Geometric reduction in optimal control theory with symmetries

A general study of symmetries in optimal control theory is given, starting from the presymplectic description of this kind of system. Then, Noether's theorem, as well as the corresponding reduction procedure (based on the application of the Marsden-Weinstein theorem adapted to the presymplectic case) are stated both in the regular and singular cases, which are previously described.Comment: 24 pages. LaTeX file. The paper has been reorganized. Additional comments have been included in Section 3. The example in Section 5.2 has been revisited. Some references have been adde

Depredación oportunista sobre Turdus grayi (Passeriformes: Turdidae) por Dasyprocta punctata (Rodentia: Dasyproctidae) en San Vito, Costa Rica

On June 5, 2016 (08h00), we observed a predation event of this rodent on a songbird in the Wilson Botanical Garden of the Las Cruces Biological Station in San Vito, Province of Puntarenas, Costa Rica (8,785, -82,95916; 1200 msnm). Initially a male of D. punctata fed on fruits and roots, but suddenly after moving stealthily, he pounced on a yigüirro pigeon or brown blackbird (Turdus grayi). After capturing it with its front legs, the rodent killed it with its incisive teeth, and subsequently moved a few meters to start consuming it (Figure 1). The position that Guatusa used to prey and subsequently consume the bird is the same one it uses to feed on seeds; sitting on its hind legs and manipulating the food with the front legs (Mora & Moreira 1984). After about 15 minutes the rodent had consumed part of the bird including muscles, viscera and even its head. Finally, the rodent fled without leaving remains of the dam on the site when taking part of the carcass in the snoutEl 05 de junio de 2016 (08h00), observamos un evento de depredación de este roedor sobre un ave canora en el Jardín Botánico Wilson de la Estación Biológica Las Cruces en San Vito, Provincia de Puntarenas, Costa Rica (8.785, -82.95916;1200 msnm). Inicialmente un macho de D. punctata se alimentaba de frutos y raíces, pero repentinamente tras desplazarse sigilosamente se abalanzó sobre un pichón de yigüirro o mirlo pardo (Turdus grayi). Tras capturarlo con sus patas delanteras, el roedor lo mató con sus dientes incisivos, y posteriormente se desplazó algunos metros hasta empezar a consumirlo (Figura 1). La posiciónque usó la Guatusa para depredar y posteriormente consumir el ave es la misma que usa para alimentarse de semillas; sentándose en sus patas traseras y manipulando el alimento con las delanteras (Mora & Moreira 1984). Tras unos 15 minutos el roedor había consumido parte del ave incluyendo músculos, vísceras e incluso su cabeza. Finalmente, el roedor huyó sin dejar restos de la presa en el sitio al llevarse parte de la carcasa en el hocic

Unambiguous Formalism for Higher-Order Lagrangian Field Theories

The aim of this paper is to propose an unambiguous intrinsic formalism for higher-order field theories which avoids the arbitrariness in the generalization of the conventional description of field theories, which implies the existence of different Cartan forms and Legendre transformations. We propose a differential-geometric setting for the dynamics of a higher-order field theory, based on the Skinner and Rusk formalism for mechanics. This approach incorporates aspects of both, the Lagrangian and the Hamiltonian description, since the field equations are formulated using the Lagrangian on a higher-order jet bundle and the canonical multisymplectic form on its dual. As both of these objects are uniquely defined, the Skinner-Rusk approach has the advantage that it does not suffer from the arbitrariness in conventional descriptions. The result is that we obtain a unique and global intrinsic version of the Euler-Lagrange equations for higher-order field theories. Several examples illustrate our construction.Comment: 21 pages; 4 diagrams; (this version) corrected typos; moved paragraphs; publishe

The miniJPAS survey:star-galaxy classification using machine learning

Future astrophysical surveys such as J-PAS will produce very large datasets, which will require the deployment of accurate and efficient Machine Learning (ML) methods. In this work, we analyze the miniJPAS survey, which observed about 1 deg2 of the AEGIS field with 56 narrow-band filters and 4 ugri broad-band filters. We discuss the classification of miniJPAS sources into extended (galaxies) and point-like (e.g. stars) objects, a necessary step for the subsequent scientific analyses. We aim at developing an ML classifier that is complementary to traditional tools based on explicit modeling. In order to train and test our classifiers, we crossmatched the miniJPAS dataset with SDSS and HSC-SSP data. We trained and tested 6 different ML algorithms on the two crossmatched catalogs. As input for the ML algorithms we use the magnitudes from the 60 filters together with their errors, with and without the morphological parameters. We also use the mean PSF in the r detection band for each pointing. We find that the RF and ERT algorithms perform best in all scenarios. When analyzing the full magnitude range of 1521). We use our best classifiers, with and without morphology, in order to produce a value added catalog available at https://j-pas.org/datareleases

J-PLUS: A first glimpse at spectrophotometry of asteroids -- The MOOJa catalog

Context: The Javalambre Photometric Local Universe Survey (J-PLUS) is an observational campaign that aims to obtain photometry in 12 ultraviolet-visible filters (0.3-1 {\mu}m) of approximately 8 500 deg{^2} of the sky observable from Javalambre (Teruel, Spain). Due to its characteristics and strategy of observation, this survey will let us analyze a great number of Solar System small bodies, with improved spectrophotometric resolution with respect to previous large-area photometric surveys in optical wavelengths. Aims: The main goal of this work is to present here the first catalog of magnitudes and colors of minor bodies of the Solar System compiled using the first data release (DR1) of the J-PLUS observational campaign: the Moving Objects Observed from Javalambre (MOOJa) catalog. Methods: Using the compiled photometric data we obtained very-low-resolution reflectance (photospectra) spectra of the asteroids. We first used a {\sigma}-clipping algorithm in order to remove outliers and clean the data. We then devised a method to select the optimal solar colors in the J-PLUS photometric system. These solar colors were computed using two different approaches: on one hand, we used different spectra of the Sun, convolved with the filter transmissions of the J-PLUS system, and on the other, we selected a group of solar-type stars in the J-PLUS DR1, according to their computed stellar parameters. Finally, we used the solar colors to obtain the reflectance spectra of the asteroids. Results: We present photometric data in the J-PLUS filters for a total of 3 122 minor bodies (3 666 before outlier removal), and we discuss the main issues of the data, as well as some guidelines to solve the

Modelos in vitro e in vivo para el estudio del desarrollo del injerto en pistacho

Resumen del trabajo presentado en la X Reunión de la Sociedad Española de Cultivo In Vitro de Tejidos Vegetales, celebrada en Zaragoza(España), del 23 al 24 de octubre de 2013Este trabajo profundiza en el estudio de los problemas que afectan al injerto de pistacho en campo, donde los injertos muestran baja tasa de éxito y un alto porcentaje de necrosis. Los injertos in vitro han demostrado ser un buen modelo para el estudio del injerto. Se realizaron dos tipos de injerto: de hendidura y bisel, utilizando cornicabra (P. terebinthus) como patrón y pistacho (P. vera) como variedad. Homoinjertos del patrón fueron utilizados como control. Los homoinjertos in vivo de cornicabra (P. terebinthus) han mostrado que el injerto de bisel con yemas subapicales es el más adecuado con un 35% de éxito y un 20% de necrosis tras 6 semanas frente al de escudete (0% de éxito y 100% de necrosis). In vitro, porciones de brotes de P. vera de 10-20 mm de longitud, con o sin ápice, fueron injertados en brotes de cornicabra con o sin raíces. Más del 70% de los brotes injertados sobrevivieron tras 3-5 semanas de cultivo, pero con escaso crecimiento de las yemas injertadas. Los tejidos del injerto mostraron uniones, que pudieron ser observadas histológicamente 15 días después del injerto. In vivo, estudios iniciales de heteroinjertos P. vera/P. terebinthus mostraron resultados prometedores, ya que 5 injertos de 12 realizados (42%) seguían creciendo 2 meses después el injerto. Se realizaron estudios sobre el crecimiento de plantas de semilla del patrón cornicabra en diferentes condiciones para identificar los factores que influyen en el desarrollo posterior de la planta injertada. Las plantas mostraron crecimiento continuado y mayor vigor en condiciones de invernadero con luz continua.Este trabajo ha sido parcialmente financiado por el proyecto INIA-FEDER RTA2010-00053-C03-02 y RTA2010-00053-C03-03 y por el Grupo de Excelencia A43 (Gobierno de Aragón). M.Y.G.P. Ha disfrutado de un beca del subprograma FPI INIA-CCAA