Multivector Field Formulation of Hamiltonian Field Theories: Equations and Symmetries

We state the intrinsic form of the Hamiltonian equations of first-order Classical Field theories in three equivalent geometrical ways: using multivector fields, jet fields and connections. Thus, these equations are given in a form similar to that in which the Hamiltonian equations of mechanics are usually given. Then, using multivector fields, we study several aspects of these equations, such as the existence and non-uniqueness of solutions, and the integrability problem. In particular, these problems are analyzed for the case of Hamiltonian systems defined in a submanifold of the multimomentum bundle. Furthermore, the existence of first integrals of these Hamiltonian equations is considered, and the relation between {\sl Cartan-Noether symmetries} and {\sl general symmetries} of the system is discussed. Noether's theorem is also stated in this context, both the ``classical'' version and its generalization to include higher-order Cartan-Noether symmetries. Finally, the equivalence between the Lagrangian and Hamiltonian formalisms is also discussed.Comment: Some minor mistakes are corrected. Bibliography is updated. To be published in J. Phys. A: Mathematical and Genera

Effect of Berry Weight and its Components on the Contents of Sugars and Anthocyanins of Three Varieties of Vitis vinifera L. under Different Water Supply Conditions

The influence of berry size on wine quality is a matter of debate. With the aim to contribute to that debate,a study of the influence of the varieties Tannat, Merlot and Cabernet Sauvignon on berry weight, onberry components (flesh, seeds and skin) and on the varieties’ oenological potential under different watersupply conditions was carried out in Uruguay between 2001 and 2004. Replicated samples of 250 berriesper vineyard were gathered at technological maturity at harvest. Berry weight and volume, weight ratioamong each of the components and anthocyanin potential (ApH1 ) were measured and a basic analysis ofthe must was carried out. The vine water status was established through the measurement of pre-dawnleaf water potential. The tests showed that berry weight and sugar content were positively correlated anddepended on variety, as was evident from the proportions of the berry components. Flesh weight wasthe most important determinant of berry weight, and flesh weight changed with the weight of the seeds.Larger values of these two components explained the heavier berries of the Tannat variety. On the otherhand, Tannat berries had higher contents and concentrations of anthocyanins and sugars, and displayedthe largest variation in these chemical compounds. Berry weight, weight and proportion of skin or theirrelationships did not determine anthocyanin contents or concentration. In response to the years’ waterconditions, different varieties showed different behaviours, explaining the variation in weight and in thecomposition of the berries

On the k-Symplectic, k-Cosymplectic and Multisymplectic Formalisms of Classical Field Theories

The objective of this work is twofold: First, we analyze the relation between the k-cosymplectic and the k-symplectic Hamiltonian and Lagrangian formalisms in classical field theories. In particular, we prove the equivalence between k-symplectic field theories and the so-called autonomous k-cosymplectic field theories, extending in this way the description of the symplectic formalism of autonomous systems as a particular case of the cosymplectic formalism in non-autonomous mechanics. Furthermore, we clarify some aspects of the geometric character of the solutions to the Hamilton-de Donder-Weyl and the Euler-Lagrange equations in these formalisms. Second, we study the equivalence between k-cosymplectic and a particular kind of multisymplectic Hamiltonian and Lagrangian field theories (those where the configuration bundle of the theory is trivial).Comment: 25 page

Scanning electron microscopy of the oral apparatus and buccopharyngeal cavity of Atelognathus salai larvae (Anura, Neobatrachia)

The aim of this study is to describe the horny structures of the buccal apparatus and buccopharyngeal cavity of A. salai by means ofscanning electron microscopy (SEM), and to compare them to those of the other known species of Atelognathus and related genera

Sensitivity of the NEXT experiment to Xe-124 double electron capture

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMDouble electron capture by proton-rich nuclei is a second-order nuclear process analogous to double beta decay. Despite their similarities, the decay signature is quite different, potentially providing a new channel to measure the hypothesized neutrinoless mode of these decays. The Standard-Model-allowed two-neutrino double electron capture (2νEC EC) has been predicted for a number of isotopes, but only observed in 78Kr, 130Ba and, recently, 124Xe. The sensitivity to this decay establishes a benchmark for the ultimate experimental goal, namely the potential to discover also the lepton-number-violating neutrinoless version of this process, 0νEC EC. Here we report on the current sensitivity of the NEXT-White detector to 124Xe 2νEC EC and on the extrapolation to NEXT-100. Using simulated data for the 2νEC EC signal and real data from NEXT-White operated with 124Xe-depleted gas as background, we define an optimal event selection that maximizes the NEXT-White sensitivity. We estimate that, for NEXT-100 operated with xenon gas isotopically enriched with 1 kg of 124Xe and for a 5-year run, a sensitivity to the 2νEC EC half-life of 6 × 1022 y (at 90% confidence level) or better can be reache

Forest landscape restoration in the drylands of Latin America

Forest Landscape Restoration (FLR) involves the ecological restoration of degraded forest landscapes, with the aim of benefiting both biodiversity and human well-being. We first identify four fundamental principles of FLR, based on previous definitions. We then critically evaluate the application of these principles in practice, based on the experience gained during an international, collaborative research project conducted in six dry forest landscapes of Latin America. Research highlighted the potential for FLR; tree species of high socioeconomic value were identified in all study areas, and strong dependence of local communities on forest resources was widely encountered, particularly for fuelwood. We demonstrated that FLR can be achieved through both passive and active restoration approaches, and can be cost-effective if the increased provision of ecosystem services is taken into account. These results therefore highlight the potential for FLR, and the positive contribution that it could make to sustainable development. However, we also encountered a number of challenges to FLR implementation, including the difficulty of achieving strong engagement in FLR activities among local stakeholders, lack of capacity for community-led initiatives, and the lack of an appropriate institutional and regulatory environment to support restoration activities. Successful implementation of FLR will require new collaborative alliances among stakeholders, empowerment and capacity building of local communities to enable them to fully engage with restoration activities, and an enabling public policy context to enable local people to be active participants in the decision making process. © 2012 by the author(s). Published here under license by the Resilience Alliance

Invariant Forms and Automorphisms of Locally Homogeneous Multisymplectic Manifolds

It is shown that the geometry of locally homogeneous multisymplectic manifolds (that is, smooth manifolds equipped with a closed nondegenerate form of degree > 1, which is locally homogeneous of degree k with respect to a local Euler field) is characterized by their automorphisms. Thus, locally homogeneous multisymplectic manifolds extend the family of classical geometries possessing a similar property: symplectic, volume and contact. The proof of the first result relies on the characterization of invariant differential forms with respect to the graded Lie algebra of infinitesimal automorphisms, and on the study of the local properties of Hamiltonian vector fields on locally multisymplectic manifolds. In particular it is proved that the group of multisymplectic diffeomorphisms acts (strongly locally) transitively on the manifold. It is also shown that the graded Lie algebra of infinitesimal automorphisms of a locally homogeneous multisymplectic manifold characterizes their multisymplectic diffeomorphisms.Comment: 25 p.; LaTeX file. The paper has been partially rewritten. Some terminology has been changed. The proof of some theorems and lemmas have been revised. The title and the abstract are slightly modified. An appendix is added. The bibliography is update

Opciones para el desarrollo del empleo rural no agrícola en América Latina y el Caribe

El empleo y el ingreso rurales no agrícolas constituyen una vía muy importante de salida de la pobreza, para muchos hogares e individuos rurales que carecen de los recursos necesarios para intentar otras opciones de progreso, como puede ser la emigración o el trabajo agrícola por cuenta propia. El documento presenta una visión de estas actividades rurales no agrícolas como elementos deseables de una sociedad rural moderna, lo que contrasta con los esquemas que ven en la caída del empleo agrícola una manifestación de progreso económico. El trabajo describe las características, los tipos y la importancia y potencialidades del empleo y del ingreso rurales no agrícolas en varios países de la región; y presenta recomendaciones para el desarrollo de estrategias de fomento del empleo y del ingreso rurales no agrícolas, incluyendo el diseño de políticas públicas orientadas a aumentar las opciones para el desarrollo de las economías rurales de la región.Agronegocio, Política agrícola, Desarrollo rural, empleo rural no agrícola, ingreso rural no agrícola, América Latina, erna, irna