Remarks on multisymplectic reduction

The problem of reduction of multisymplectic manifolds by the action of Lie groups is stated and discussed, as a previous step to give a fully covariant scheme of reduction for classical field theories with symmetries.Comment: 9 pages. Some comments added in the section "Discussion and outlook" and in the Acknowledgments. New references are added. Minor mistakes are correcte

Contact Zones, Discursive Spaces: The Case of the Silliman University National Writers Workshop

The Silliman University National Writers Workshop’s (SUNWW) historical circumstance has been implicated in the Cold War. As such it is accused of perpetuating colonial ideas on language and literary production. Its use of New Criticism is said to be detrimental to nation-building as this critical pedagogy is seen to be ahistorical and apolitical. This paper investigates the Workshop space and critiques the actual workshop discussions in the years 2019 and 2021. The explorations reveal that the Workshop is a discursive space, a “contact zone” where its participants are always engaged in the act of negotiating ideas about craft, literature and its functions, writing and social responsibility, the reader and its role in interpretation, writers and their agency, reading and criticism. It is a space that affords many possibilities of revisioning and repurposing of these ideas. It is a space of negotiation, meaning-making, and consensus

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

Extended Hamiltonian systems in multisymplectic field theories

We consider Hamiltonian systems in first-order multisymplectic field theories. We review the properties of Hamiltonian systems in the so-called restricted multimomentum bundle, including the variational principle which leads to the Hamiltonian field equations. In an analogous way to how these systems are defined in the so-called extended (symplectic) formulation of non-autonomous mechanics, we introduce Hamiltonian systems in the extended multimomentum bundle. The geometric properties of these systems are studied, the Hamiltonian equations are analyzed using integrable multivector fields, the corresponding variational principle is also stated, and the relation between the extended and the restricted Hamiltonian systems is established. All these properties are also adapted to certain kinds of submanifolds of the multimomentum bundles in order to cover the case of almost-regular field theories.Comment: 36 pp. The introduction and the abstract have been rewritten. New references are added and some little mistakes are corrected. The title has been slightly modifie

Developing a site-conditions map for seismic hazard Assessment in Portugal

The evaluation of site effects on a broad scale is a critical issue for seismic hazard and risk assessment, land use planning and emergency planning. As characterization of site conditions based on the shear-wave velocity has become increasingly important, several methods have been proposed in the literature to estimate its average over the first thirty meters (Vs30) from more extensively available data. These methods include correlations with geologic-geographic defined units and topographic slope. In this paper we present the first steps towards the development of a site–conditions map for Portugal, based on a regional database of shear-wave velocity data, together with geological, geographic, and lithological information. We computed Vs30 for each database site and classified it according to the corresponding geological-lithological information using maps at the smallest scale available (usually 1:50000). We evaluated the consistency of Vs30 values within generalized-geological classes, and assessed the performance of expedient methodologies proposed in the literature

Multivector Fields and Connections. Setting Lagrangian Equations in Field Theories

The integrability of multivector fields in a differentiable manifold is studied. Then, given a jet bundle $J^1E\to E\to M$, it is shown that integrable multivector fields in $E$ are equivalent to integrable connections in the bundle $E\to M$ (that is, integrable jet fields in $J^1E$). This result is applied to the particular case of multivector fields in the manifold $J^1E$ and connections in the bundle $J^1E\to M$ (that is, jet fields in the repeated jet bundle $J^1J^1E$), in order to characterize integrable multivector fields and connections whose integral manifolds are canonical lifting of sections. These results allow us to set the Lagrangian evolution equations for first-order classical field theories in three equivalent geometrical ways (in a form similar to that in which the Lagrangian dynamical equations of non-autonomous mechanical systems are usually given). Then, using multivector fields; we discuss several aspects of these evolution equations (both for the regular and singular cases); namely: the existence and non-uniqueness of solutions, the integrability problem and Noether's theorem; giving insights into the differences between mechanics and field theories.Comment: New sections on integrability of Multivector Fields and applications to Field Theory (including some examples) are added. The title has been slightly modified. To be published in J. Math. Phy

Structural aspects of Hamilton-Jacobi theory

In our previous papers [11,13] we showed that the Hamilton-Jacobi problem can be regarded as a way to describe a given dynamics on a phase space manifold in terms of a family of dynamics on a lower-dimensional manifold. We also showed how constants of the motion help to solve the Hamilton-Jacobi equation. Here we want to delve into this interpretation by considering the most general case: a dynamical system on a manifold that is described in terms of a family of dynamics (`slicing vector fields') on lower-dimensional manifolds. We identify the relevant geometric structures that lead from this decomposition of the dynamics to the classical Hamilton-Jacobi theory, by considering special cases like fibred manifolds and Hamiltonian dynamics, in the symplectic framework and the Poisson one. We also show how a set of functions on a tangent bundle can determine a second-order dynamics for which they are constants of the motion.Comment: 26 pages. Minor changes (some minor mistakes are corrected

Gluon Schwinger-dyson Equation In The Pt-bfm Scheme

Schwinger-Dyson equations provide an appropriate framework for tackling nonperturbative QCD phenomena requiring a continuum treatment. However, an inadequate truncation of this tower of integral equations can compromise the symmetries underlying the theory in question. The synthesis of the Pinch Technique and the Background Field method provides a framework where it is possible to devise a self-consistent truncation scheme, exploiting the Ward identities satisfied by the effective Green's functions that emerge. In this work we review how this truncation scheme is implemented, and show that the new series of dressed diagrams for the background gluon propagator organizes itself in characteristic subsets that are individually transverse. In addition, we discuss how the Background Quantum identity connects the background gluon propagator with the conventional one, computed in the lattice simulations.70613th International Workshop on Hadron PhysicsMAR 22-27, 2015Angra dos Reis, BRAZI

Monitoring of evapotranspirated plant water in the SITIS Platform of Plant Phenotyping for Drought Tolerance.

In the development of new cultivars that are more tolerant to water deficiency, it has become important to identify plants that consume less water during their life cycle and are able to uptake water from deeper soil layers. The system allows scheduling of monitoring either at predefined times or at regular intervals, or the combination between them. With this, it is possible to construct curves of plant water use daily, monthly or according to their phenological stages.Editores: Paulo Sérgio de Paula Herrmann Junior, Paulino Ribeiro Villas Boas