http://www.recercat.cat:80/handle/2072/48808 www.ub.edu Fri, 24 May 2013 02:32:17 GMT 2013-05-24T02:32:17Z http://www.recercat.cat:80/bitstream/id/26376/ http://www.recercat.cat:80/handle/2072/48808 http://www.recercat.cat:80/handle/2072/210670 Microscopic derivation of a NN*(1440) potential Juliá-Diaz, Bruno; Fernández, F.; González Cámara, Pablo; Valcarce, A. We derive a NN*(1440) potential from a nonrelativistic quark-quark interaction and a quark cluster model for the baryons. By making use of the Born-Oppenheimer approximation, we examine quark Pauli correlations in detail. A comparison with the NN potential derived in the same framework is done. This makes it possible to emphasize the role of quark antisymmetry beyond baryon antisymmetry and to discuss the use of phenomenological NN*(1440) baryonic potentials. http://www.recercat.cat:80/handle/2072/210670 http://www.recercat.cat:80/handle/2072/204984 New method for measuring longitudinal fuctuations and directed flow in ultrarelativistic heavy ion reactions Csernai, L. P.; Eyyubova, G.; Magas, V. K. It has been shown in recent ALICE@LHC measurements that the odd flow harmonics, in particular, a directed flow v1, occurred to be weak and dominated by random fluctuations. In this work we propose a new method, which makes the measurements more sensitive to the flow patterns showing global collective symmetries. We demonstrate how the longitudinal center of mass rapidity fluctuations can be identified, and then the collective flow analysis can be performed in the event-by-event center of mass frame. Such a method can be very effective in separating the flow patterns originating from random fluctuations, and the flow patterns originating from the global symmetry of the initial state. http://www.recercat.cat:80/handle/2072/204984 http://www.recercat.cat:80/handle/2072/184056 A high-sensitivity differential scanning calorimeter with magnetic field for magnetostructural transitions Marcos, Jordi; Casanova i Fernàndez, Fèlix; Batlle Gelabert, Xavier; Labarta, Amílcar; Planes Vila, Antoni; Mañosa, Lluís We have developed a differential scanning calorimeter capable of working under applied magnetic fields of up to 5 T. The calorimeter is highly sensitive and operates over the temperature range 10¿300 K. It is shown that, after a proper calibration, the system enables determination of the latent heat and entropy changes in first-order solid¿solid phase transitions. The system is particularly useful for investigating materials that exhibit the giant magnetocaloric effect arising from a magnetostructural phase transition. Data for Gd5(Si0.1Ge0.9)4 are presented. http://www.recercat.cat:80/handle/2072/184056 http://www.recercat.cat:80/handle/2072/184055 Heat pulse line-source method to determine thermal conductivity of consolidated rocks Fernández i Ortiga, Manel; Banda, E. (Enric); Rojas Blasi, Emilio An instrument designed to measure thermal conductivity of consolidated rocks, dry or saturated, using a transient method is presented. The instrument measures relative values of the thermal conductivity, and it needs calibration to obtain absolute values. The device can be used as heat pulse line source and as continuous heat line source. Two parameters to determine thermal conductivity are proposed: TMAX, in heat pulse line source, and SLOPE, in continuous heat line source. Its performance is better, and the operation simpler, in heat pulse line-source mode with a measuring time of 170 s and a reproducibility better than 2.5%. The sample preparation is very simple on both modes. The performance has been tested with a set of ten rocks with thermal conductivity values between 1.4 and 5.2 W m¿1 K¿1 which covers the usual range for consolidated rocks. http://www.recercat.cat:80/handle/2072/184055 http://www.recercat.cat:80/handle/2072/184054 New experimental apparatus for the study of the Bénard-Rayleigh problem Moreno, J.; Jiménez, J.; Córdoba, A.; Rojas Blasi, Emilio; Zamora, M. A new experimental system to measure the equivalent thermal conductivity of a liquid with regard to the Bénard-Rayleigh problem was constructed. The liquid is enclosed within walls of polymethylmethacrylate between two copper plates in which there are thermocouples to measure the difference in temperature between the lower and upper surfaces of the layer of liquid. Heat flux is measured by means of a linear heat fluxmeter consisting of 204 thermocouples in series. The fluxmeter was calibrated and the linear relationship that exists between the heat flux and the emf generated was verified. The thermal conductivity of the polymethylmethacrylate employed was measured and measurements of the equivalent conductivity in cylindrical boundaries of two silicone oils were made. The critical value of the temperature difference and the contribution of the convective process to the transmission of heat were determined. http://www.recercat.cat:80/handle/2072/184054 http://www.recercat.cat:80/handle/2072/183974 Dynamics of driven three-dimensional thin films: from hdrophilic to superhydrophobic substrates Ledesma Aguilar, Rodrigo Andrés; Hernández Machado, Aurora; Pagonabarraga Mora, Ignacio We study the forced displacement of a thin film of fluid in contact with vertical and inclined substrates of different wetting properties, that range from hydrophilic to hydrophobic, using the lattice-Boltzmann method. We study the stability and pattern formation of the contact line in the hydrophilic and superhydrophobic regimes, which correspond to wedge-shaped and nose-shaped fronts, respectively. We find that contact lines are considerably more stable for hydrophilic substrates and small inclination angles. The qualitative behavior of the front in the linear regime remains independent of the wetting properties of the substrate as a single dispersion relation describes the stability of both wedges and noses. Nonlinear patterns show a clear dependence on wetting properties and substrate inclination angle. The effect is quantified in terms of the pattern growth rate, which vanishes for the sawtooth pattern and is finite for the finger pattern. Sawtooth shaped patterns are observed for hydrophilic substrates and low inclination angles, while finger-shaped patterns arise for hydrophobic substrates and large inclination angles. Finger dynamics show a transient in which neighboring fingers interact, followed by a steady state where each finger grows independently. http://www.recercat.cat:80/handle/2072/183974 http://www.recercat.cat:80/handle/2072/183973 Three-dimensional aspects of fluid flows in channels. I. Meniscus and thin film regimes Ledesma Aguilar, Rodrigo Andrés; Hernández Machado, Aurora; Pagonabarraga Mora, Ignacio We study the forced displacement of a fluid-fluid interface in a three-dimensional channel formed by two parallel solid plates. Using a lattice-Boltzmann method, we study situations in which a slip velocity arises from diffusion effects near the contact line. The difference between the slip and channel velocities determines whether the interface advances as a meniscus or a thin film of fluid is left adhered to the plates. We find that this effect is controlled by the capillary and Péclet numbers. We estimate the crossover from a meniscus to a thin film and find good agreement with numerical results. The penetration regime is examined in the steady state. We find that the occupation fraction of the advancing finger relative to the channel thickness is controlled by the capillary number and the viscosity contrast between the fluids. For high viscosity contrast, lattice-Boltzmann results agree with previous results. For zero viscosity contrast, we observe remarkably narrow fingers. The shape of the finger is found to be universal. http://www.recercat.cat:80/handle/2072/183973 http://www.recercat.cat:80/handle/2072/183972 Three-dimensional aspects of fluid flows in channels. II. Effects of meniscus and thin film regimes on viscous fingers Ledesma Aguilar, Rodrigo Andrés; Pagonabarraga Mora, Ignacio; Hernández Machado, Aurora We perform a three-dimensional study of steady state viscous fingers that develop in linear channels. By means of a three-dimensional lattice-Boltzmann scheme that mimics the full macroscopic equations of motion of the fluid momentum and order parameter, we study the effect of the thickness of the channel in two cases. First, for total displacement of the fluids in the channel thickness direction, we find that the steady state finger is effectively two-dimensional and that previous two-dimensional results can be recovered by taking into account the effect of a curved meniscus across the channel thickness as a contribution to surface stresses. Second, when a thin film develops in the channel thickness direction, the finger narrows with increasing channel aspect ratio in agreement with experimental results. The effect of the thin film renders the problem three-dimensional and results deviate from the two-dimensional prediction. http://www.recercat.cat:80/handle/2072/183972 http://www.recercat.cat:80/handle/2072/183971 Interfacial instabilities of a fluid annulus in a rotating Hele-Shaw cell Carrillo Galdó, Lluís; Soriano i Fradera, Jordi; Ortín, Jordi We have studied the interfacial instabilities experienced by a liquid annulus as it moves radially in a circular Hele-Shaw cell rotating with angular velocity Omega. The instability of the leading interface (oil displacing air) is driven by the density difference in the presence of centrifugal forcing, while the instability of the trailing interface (air displacing oil) is driven by the large viscosity contrast. A linear stability analysis shows that the stability of the two interfaces is coupled through the pressure field already at a linear level. We have performed experiments in a dry cell and in a cell coated with a thin fluid layer on each plate, and found that the stability depends substantially on the wetting conditions at the leading interface. Our experimental results of the number of fingers resulting from the instability compare well with the predictions obtained through a numerical integration of the coupled equations derived from a linear stability analysis. Deep in the nonlinear regime we observe the emission of liquid droplets through the formation of thin filaments at the tip of outgrowing fingers. http://www.recercat.cat:80/handle/2072/183971 http://www.recercat.cat:80/handle/2072/183970 Bifurcations and chaos in single-roll natural convection with low Prandtl number Mercader, Isabel; Batiste, O.; Ramírez Piscina, Laureano; Ruiz, Xavier; Rüdiger, S.; Casademunt i Viader, Jaume Convective flows of a small Prandtl number fluid contained in a two-dimensional cavity subject to a lateral thermal gradient are numerically studied by using different techniques. The aspect ratio (length to height) is kept at around 2. This value is found optimal to make the flow most unstable while keeping the basic single-roll structure. Two cases of thermal boundary conditions on the horizontal plates are considered: perfectly conducting and adiabatic. For increasing Rayleigh numbers we find a transition from steady flow to periodic oscillations through a supercritical Hopf bifurcation that maintains the centrosymmetry of the basic circulation. For a Rayleigh number of about ten times that of the Hopf bifurcation the system initiates a complex scenario of bifurcations. In the conductive case these include a quasiperiodic route to chaos. In the adiabatic one the dynamics is dominated by the interaction of two Neimark-Sacker bifurcations of the basic periodic solutions, leading to the stable coexistence of three incommensurate frequencies, and finally to chaos. In all cases, the complex time-dependent behavior does not break the basic, single-roll structure. http://www.recercat.cat:80/handle/2072/183970 http://www.recercat.cat:80/handle/2072/183969 Low viscosity contrast fingering in a rotating Hele-Shaw cell Alvarez Lacalle, Enrique; Ortín, Jordi; Casademunt i Viader, Jaume We study the fingering instability of a circular interface between two immiscible liquids in a radial Hele-Shaw cell. The cell rotates around its vertical symmetry axis, and the instability is driven by the density difference between the two fluids. This kind of driving allows studying the interfacial dynamics in the particularly interesting case of an interface separating two liquids of comparable viscosity. An accurate experimental study of the number of fingers emerging from the instability reveals a slight but systematic dependence of the linear dispersion relation on the gap spacing. We show that this result is related to a modification of the interface boundary condition which incorporates stresses originated from normal velocity gradients. The early nonlinear regime shows nearly no competition between the outgrowing fingers, characteristic of low viscosity contrast flows. We perform experiments in a wide range of experimental parameters, under conditions of mass conservation (no injection), and characterize the resulting patterns by data collapses of two characteristic lengths: the radius of gyration of the pattern and the interface stretching. Deep in the nonlinear regime, the fingers which grow radially outwards stretch and become gradually thinner, to a point that the fingers pinch and emit drops. We show that the amount of liquid emitted in the first generation of drops is a constant independent of the experimental parameters. Further on there is a sharp reduction of the amount of liquid centrifugated, punctuated by periods of no observable centrifugation. http://www.recercat.cat:80/handle/2072/183969 http://www.recercat.cat:80/handle/2072/183968 Radial displacement of a fluid annulus in a rotating Hele¿Shaw cell Carrillo Galdó, Lluís; Soriano i Fradera, Jordi; Ortín, Jordi The radial displacement of a fluid annulus in a rotating circular Hele-Shaw cell has been investigated experimentally. It has been found that the flow depends sensitively on the wetting conditions at the outer interface. Displacements in a prewet cell are well described by Darcy's law in a wide range of experimental parameters, with little influence of capillary effects. In a dry cell, however, a more careful analysis of the interface motion is required; the interplay between a gradual loss of fluid at the inner interface, and the dependence of capillary forces at the outer interface on interfacial velocity and dynamic contact angle, result in a constant velocity for the interfaces. The experimental results in this case correlate in the form of an empirical scaling relation between the capillary number Ca and a dimensionless group, related to the ratio of centrifugal to capillary forces, which spans about three orders of magnitude in both quantities. Finally, the relative thickness of the coating film left by the inner interface, alpha i, is obtained as a function of Ca. http://www.recercat.cat:80/handle/2072/183968 http://www.recercat.cat:80/handle/2072/183967 Coarsening of solid-liquid mixtures in a random acceleration field Thomson, J. Ross; Casademunt i Viader, Jaume; Drolet, François; Vials Giménez, Jorge The effects of flow induced by a random acceleration field (g-jitter) are considered in two related situations that are of interest for microgravity fluid experiments: the random motion of isolated buoyant particles, and diffusion driven coarsening of a solid-liquid mixture. We start by analyzing in detail actual accelerometer data gathered during a recent microgravity mission, and obtain the values of the parameters defining a previously introduced stochastic model of this acceleration field. The diffusive motion of a single solid particle suspended in an incompressible fluid that is subjected to such random accelerations is considered, and mean squared velocities and effective diffusion coefficients are explicitly given. We next study the flow induced by an ensemble of such particles, and show the existence of a hydrodynamically induced attraction between pairs of particles at distances large compared with their radii, and repulsion at short distances. Finally, a mean field analysis is used to estimate the effect of g-jitter on diffusion controlled coarsening of a solid-liquid mixture. Corrections to classical coarsening rates due to the induced fluid motion are calculated, and estimates are given for coarsening of Sn-rich particles in a Sn-Pb eutectic fluid, an experiment to be conducted in microgravity in the near future. http://www.recercat.cat:80/handle/2072/183967 http://www.recercat.cat:80/handle/2072/183923 Cavity flow induced by a fluctuating acceleration field Thomson, J. Ross; Casademunt i Viader, Jaume; Viñals Giménez, Jorge http://www.recercat.cat:80/handle/2072/183923 http://www.recercat.cat:80/handle/2072/183922 Diffusion of passive scalars under stochastic convection Careta Pons, Agustí; Sagués i Mestre, Francesc; Sancho, José M. The diffusion of passive scalars convected by turbulent flows is addressed here. A practical procedure to obtain stochastic velocity fields with well¿defined energy spectrum functions is also presented. Analytical results are derived, based on the use of stochastic differential equations, where the basic hypothesis involved refers to a rapidly decaying turbulence. These predictions are favorable compared with direct computer simulations of stochastic differential equations containing multiplicative space¿time correlated noise. http://www.recercat.cat:80/handle/2072/183922 http://www.recercat.cat:80/handle/2072/183921 Front dynamics in turbulent media Martí Pérez, Arturo C.; Sagués i Mestre, Francesc; Sancho, José M. A study of a stable front propagating in a turbulent medium is presented. The front is generated through a reaction-diffusion equation, and the turbulent medium is statistically modeled using a Langevin equation. Numerical simulations indicate the presence of two different dynamical regimes. These regimes appear when the turbulent flow either wrinkles a still rather sharp propagating interfase or broadens it. Specific dependences of the propagating velocities on stirring intensities appropriate to each case are found and fitted when possible according to theoretically predicted laws. Different turbulent spectra are considered. http://www.recercat.cat:80/handle/2072/183921 http://www.recercat.cat:80/handle/2072/183920 Langevin approach to generate synthetic turbulent flows Martí Pérez, Arturo C.; Sagués i Mestre, Francesc; Sancho, José M.; Sancho, José M. We present an analytical scheme, easily implemented numerically, to generate synthetic Gaussian turbulent flows by using a linear Langevin equation, where the noise term acts as a stochastic stirring force. The characteristic parameters of the velocity field are well introduced, in particular the kinematic viscosity and the spectrum of energy. As an application, the diffusion of a passive scalar is studied for two different energy spectra. Numerical results are compared favorably with analytical calculations. http://www.recercat.cat:80/handle/2072/183920 http://www.recercat.cat:80/handle/2072/183919 Radial dose function of a 90Sr 90Y seed in water and A150: Comment on Calibration and characterization of beta-particle sources for intravascular brachytherapy Asenjo, J.; Fernández Varea, José María; Sánchez-Reyes, A.; Wang, C.-K. Intravascular brachytherapy with beta sources has become a useful technique to prevent restenosis after cardiovascular intervention. In particular, the Beta-Cath high-dose-rate system, manufactured by Novoste Corporation, is a commercially available 90Sr 90Y source for intravascular brachytherapy that is achieving widespread use. Its dosimetric characterization has attracted considerable attention in recent years. Unfortunately, the short ranges of the emitted beta particles and the associated large dose gradients make experimental measurements particularly difficult. This circumstance has motivated the appearance of a number of papers addressing the characterization of this source by means of Monte Carlo simulation techniques. http://www.recercat.cat:80/handle/2072/183919 http://www.recercat.cat:80/handle/2072/183702 On the zeta-function regularization of a two-dimensional series of epsten-Hurwitz type Elizalde, E. (Emili), 1950- For a few years now, the study of quantum field theories in partially compactified space-time manifolds has acquired increasing importance in several domains of quantum physics. Let me just mention the issues of dimensional reduction and spontaneous compactification, and the multiple questions associated with the study of quantum field theories in the presence of boundaries (like the Casimir effect) and on curved space-time (manifolds with curvature and nontrivial topology), a step towards quantum gravity. http://www.recercat.cat:80/handle/2072/183702 http://www.recercat.cat:80/handle/2072/183701 Topologies for poin distributions Elizalde, E. (Emili), 1950- The concepts of void and cluster for an arbitrary point distribution in a domain D are defined and characterized by some parameters such as volume, density, number of points belonging to them, shape, etc. After assigning a weight to each void and clusterwhich is a function of its characteristicsthe concept of distance between two point configurations S1 and S2 in D is introduced, both with and without the help of a lattice in the domain D. This defines a topology for the point distributions in D, which is different for the different characterizations of the voids and clusters. http://www.recercat.cat:80/handle/2072/183701 http://www.recercat.cat:80/handle/2072/183700 Stochastic processes induced by dichotomous markov noise: Some exact dynamical results Sancho, José M. Stochastic processes defined by a general Langevin equation of motion where the noise is the non-Gaussian dichotomous Markov noise are studied. A non-FokkerPlanck master differential equation is deduced for the probability density of these processes. Two different models are exactly solved. In the second one, a nonequilibrium bimodal distribution induced by the noise is observed for a critical value of its correlation time. Critical slowing down does not appear in this point but in another one. http://www.recercat.cat:80/handle/2072/183700 http://www.recercat.cat:80/handle/2072/183699 Canonical Noether symmetries and commutativity properties for gauge systems Gràcia, Xavier; Pons Ràfols, Josep Maria For a dynamical system defined by a singular Lagrangian, canonical Noether symmetries are characterized in terms of their commutation relations with the evolution operators of Lagrangian and Hamiltonian formalisms. Separate characterizations are given in phase space, in velocity space, and through an evolution operator that links both spaces. 2000 American Institute of Physics. http://www.recercat.cat:80/handle/2072/183699 http://www.recercat.cat:80/handle/2072/183698 Gauge transformations in Einstein-Yang-Mills theories Pons Ràfols, Josep Maria; Salisbury, D. C.; Shepley, L. C. We discuss the relation between spacetime diffeomorphisms and gauge transformations in theories of the YangMills type coupled with Einsteins general relativity. We show that local symmetries of the Hamiltonian and Lagrangian formalisms of these generally covariant gauge systems are equivalent when gauge transformations are required to induce transformations which are projectable under the Legendre map. Although pure YangMills gauge transformations are projectable by themselves, diffeomorphisms are not. Instead, the projectable symmetry group arises from infinitesimal diffeomorphism-inducing transformations which must depend on the lapse function and shift vector of the spacetime metric plus associated gauge transformations. Our results are generalizations of earlier results by ourselves and by Salisbury and Sundermeyer. 2000 American Institute of Physics. http://www.recercat.cat:80/handle/2072/183698 http://www.recercat.cat:80/handle/2072/183697 Dynamical properties of nonmarkovian stochastic differential equations Hernández Machado, Aurora; San Miguel Ruibal, Maximino We study nonstationary non-Markovian processes defined by Langevin-type stochastic differential equations with an OrnsteinUhlenbeck driving force. We concentrate on the long time limit of the dynamical evolution. We derive an approximate equation for the correlation function of a nonlinear nonstationary non-Markovian process, and we discuss its consequences. Non-Markovicity can introduce a dependence on noise parameters in the dynamics of the correlation function in cases in which it becomes independent of these parameters in the Markovian limit. Several examples are discussed in which the relaxation time increases with respect to the Markovian limit. For a Brownian harmonic oscillator with fluctuating frequency, the non-Markovicity of the process decreases the domain of stability of the system, and it can change an infradamped evolution into an overdamped one. http://www.recercat.cat:80/handle/2072/183697 http://www.recercat.cat:80/handle/2072/183696 Poincar-Cartan integral invariant and canonical transformation for singular lagrangians Dominici, D.; Gomis Torné, Joaquim In this work we develop the canonical formalism for constrained systems with a finite number of degrees of freedom by making use of the PoincarCartan integral invariant method. A set of variables suitable for the reduction to the physical ones can be obtained by means of a canonical transformation. From the invariance of the PoincarCartan integral under canonical transformations we get the form of the equations of motion for the physical variables of the system. http://www.recercat.cat:80/handle/2072/183696 http://www.recercat.cat:80/handle/2072/183695 Dirac and reduced quantization: A Lagrangian approach and Application to Coset Spaces Ordoñez, C.; Pons Ràfols, Josep Maria A Lagrangian treatment of the quantization of first class Hamiltonian systems with constraints and Hamiltonian linear and quadratic in the momenta, respectively, is performed. The first reduce and then quantize and the first quantize and then reduce (Diracs) methods are compared. A source of ambiguities in this latter approach is pointed out and its relevance on issues concerning self-consistency and equivalence with the first reduce method is emphasized. One of the main results is the relation between the propagator obtained la Dirac and the propagator in the full space. As an application of the formalism developed, quantization on coset spaces of compact Lie groups is presented. In this case it is shown that a natural selection of a Dirac quantization allows for full self-consistency and equivalence. Finally, the specific case of the propagator on a two-dimensional sphere S2 viewed as the coset space SU(2)/U(1) is worked out. 1995 American Institute of Physics. http://www.recercat.cat:80/handle/2072/183695 http://www.recercat.cat:80/handle/2072/183694 Higher order Lagrangian systems: Geometric structures, Dynamics, and Constraints Gràcia, Xavier; Pons Ràfols, Josep Maria; Román-Roy, Narciso In order to study the connections between Lagrangian and Hamiltonian formalisms constructed from aperhaps singularhigher-order Lagrangian, some geometric structures are constructed. Intermediate spaces between those of Lagrangian and Hamiltonian formalisms, partial Ostrogradskiis transformations and unambiguous evolution operators connecting these spaces are intrinsically defined, and some of their properties studied. Equations of motion, constraints, and arbitrary functions of Lagrangian and Hamiltonian formalisms are thoroughly studied. In particular, all the Lagrangian constraints are obtained from the Hamiltonian ones. Once the gauge transformations are taken into account, the true number of degrees of freedom is obtained, both in the Lagrangian and Hamiltonian formalisms, and also in all the intermediate formalisms herein defined. http://www.recercat.cat:80/handle/2072/183694 http://www.recercat.cat:80/handle/2072/183693 On the many-time formulation of classical particle dynamics Longhi, G.; Lusanna, L.; Pons Ràfols, Josep Maria Starting from the standard one-time dynamics of n nonrelativistic particles, the n-time equations of motion are inferred, and a variational principle is formulated. A suitable generalization of the classical LieKnig theorem is demonstrated, which allows the determination of all the associated presymplectic structures. The conditions under which the action of an invariance group is canonical are studied, and a corresponding Noether theorem is deduced. A formulation of the theory in terms of n first-class constraints is recovered by means of coisotropic imbeddings. The proposed approach also provides for a better understanding of the relativistic particle dynamics, since it shows that the different roles of the physical positions and the canonical variables is not peculiar to special relativity, but rather to any n-time approach: indeed a nonrelativistic no-interaction theorem is deduced. http://www.recercat.cat:80/handle/2072/183693 http://www.recercat.cat:80/handle/2072/183692 Poincaré is a subgroup of Galilei in one space dimension more Elizalde, E. (Emili), 1950- Through an imaginary change of coordinates, the ordinary Poincar algebra is shown to be a subalgebra of the Galilei one in four space dimensions. Through a subsequent contraction the remaining Lie generators are eliminated in a natural way. An application of these results to connect Galilean and relativistic field equations is discussed. http://www.recercat.cat:80/handle/2072/183692 http://www.recercat.cat:80/handle/2072/183691 Perturbation theory and locality in the Field-Antifield formalism Gomis Torné, Joaquim; París, Jordi The BatalinVilkovisky formalism is studied in the framework of perturbation theory by analyzing the antibracket BecchiRouetStoraTyutin (BRST) cohomology of the proper solution S0. It is concluded that the recursive equations for the complete proper solution S can be solved at any order of perturbation theory. If certain conditions on the classical action and on the gauge generators are imposed the solution can be taken local. http://www.recercat.cat:80/handle/2072/183691