Faddeev-Jackiw approach to gauge theories and ineffective constraints

The general conditions for the applicability of the Faddeev-Jackiw approach to gauge theories are studied. When the constraints are effective a new proof in the Lagrangian framework of the equivalence between this method and the Dirac approach is given. We find, however, that the two methods may give different descriptions for the reduced phase space when ineffective constraints are present. In some cases the Faddeev-Jackiw approach may lose some constraints or some equations of motion. We believe that this inequivalence can be related to the failure of the Dirac conjecture (that says that the Dirac Hamiltonian can be enlarged to an Extended Hamiltonian including all first class constraints, without changes in the dynamics) and we suggest that when the Dirac conjecture fails the Faddeev-Jackiw approach fails to give the correct dynamics. Finally we present some examples that illustrate this inequivalence.Comment: 21 pages, Latex. To be published in Int. J. Mod. Phys.

Cu(II) 4-phenoxybenzoate dimers and monomer coordinated by pyridines: synthesis and crystal structures

The complexes [Cu(PhOBz)2(dPy)]2 (PhOBz = 4-phenoxybenzoate; dPy = pyridine (1), 3-phenylpyridine (2), 4-benzylpyridine (3) and 4-phenylpyridine (4) and the complex [Cu(PhOBz)2(4-Phpy)2(H2O)] (5) were prepared and fully characterized. X-ray crystal structures of the five complexes have been determined. Complexes 1-4 consist of binuclear units where both Cu(II) are linked by four syn-syn carboxylate bridges, showing a paddle-wheel unit. The compound 5 is mononuclear and the metal center is coordinated to two PhOBz in monodentate form, two 4-Phpy ligands and one H2O molecule with slightly distorted square pyramidal geometry. Finally, the magnetic properties of compounds 3 and 5 have also been studied, confirming the different strength interactions between Cu(II) cations

Syntheses, supramolecular architectures and photoluminescence properties of Zn(II) complexes based on 3,5-dihydroxybenzoic and pyridine/pyrazole derived ligands

Five new coordination compounds [Zn(μ‑3,5‑DHB)2(H2O)2]n (1a), [Zn(μ‑3,5‑DHB)(μ‑OH2) (H2O)2]n·(3,5‑DHB)n·(4H2O)n (1b), [Zn(3,5‑DHB)2(Isna)2]·2H2O (2), [Zn(3,5‑DHB)2(4‑Acpy)2]·3H2O (3) and [Zn (3,5‑DHB)2(3‑Mepz)2]·H2O (4) (3,5‑HDHB=3,5‑dihydroxybenzoic, Isna=isonicotinamide, 4‑Acpy=4‑acetylpyridine and 3‑Mepz=3‑methylpyrazole) were synthesized in water or water-methanol as solvents. All these compounds have been characterized by elemental analysis, FTIR-ATR and 1H NMR spectroscopies and Powder X-ray diffraction (PXRD). For compounds 1b-4, X-ray crystal structures have been determined. In these compounds, 3,5‑DHB ligand displays different coordination modes. Complex 1b is a coordination polymer, while the addition of the pyridine/pyrazole ligands in the reaction provokes the formation of monomeric compounds (2-4). Moreover, the crystal packing indicates that these complexes expand into 2D/ 3D network structures mainly by intermolecular hydrogen bond interactions. Finally, the photoluminescent properties of these complexes in solid state have also been investigated. The strong emission observed for 1b indicates that it may be a good candidate for photoluminescent devices

Cotilos impactados vs. roscados no cementados: estudio radiológico post-operatorio comparativo

Se han valorado radiografías AP de pelvis obtenidas tras colocación de 102 pró- tesis no cementadas en 97 pacientes: 51 eran del tipo cótilo roscado (CR), y 51 del tipo cótilo impactado (CI). Se ha medido el ángulo de inclinación, la posición del cotilo, el grado de centraje, el grado de protrusión/extrusión, y la superficie de contacto entre cótilo y la cavidad acetabular. Globahnente los CR quedan implantados más verticalmente que los CI (p=0,006), así como más lateralizados (p=0,02). El porcentaje de cótilos bien centrados en relación al acetábulo es mayor entre los CI que entre los CR (p=0,002). Un 19% de los CR quedaron parcialmente extraídos, no llegando a contactar con el fondo de la cavidad acetabular, mientras que en ningún caso de los CI se apreció este problema. En conclusión, a pesar de la teórica ventaja de poseer una estabilidad inicial mayor, la orientación de los CR no resulta tan óptima como la obtenida con los CI, lo que asegura una estabilidad mejor a largo plazo y una menor usura del polietileno.—Post-operative anteroposterior radiographs of the pelvis in 102 patients receiving a cementless total hip arthroplasty were analyzed. In a group, a screwed spherical socket (SCR) was applied, while in other a press-fit impacted socket (IMP) was used. The following parameters were studied: inclination angle, location and centering of the acetabular component, degree of protrusion-extrusion, and porcentage of contact surface between the socket and the acetabulum. SCR sockets appeared to be placed more vertically (p=0.006), and laterally (p=0.02) than IMP prostheses. The percent of properly centered sockets was higher among IMP than among SCR implants (p=0.002). SCR prostheses were found to be partly extruded in 19% of cases while none of the IMP prostheses had this problem. In conclussion, despite the theoretical advantage of the SCR implants having a better initial fixation than the IMP implants, the latter tend to be implanted in a more optimal position, thus ensuring a better longterm stability and therefore less wear problems can be expected

Darboux coordinates for the Hamiltonian of first order Einstein-Cartan gravity

Based on preliminary analysis of the Hamiltonian formulation of the first order Einstein-Cartan action (arXiv:0902.0856 [gr-qc] and arXiv:0907.1553 [gr-qc]) we derive the Darboux coordinates, which are a unique and uniform change of variables preserving equivalence with the original action in all spacetime dimensions higher than two. Considerable simplification of the Hamiltonian formulation using the Darboux coordinates, compared with direct analysis, is explicitly demonstrated. Even an incomplete Hamiltonian analysis in combination with known symmetries of the Einstein-Cartan action and the equivalence of Hamiltonian and Lagrangian formulations allows us to unambiguously conclude that the \textit{unique} \textit{gauge} invariances generated by the first class constraints of the Einstein-Cartan action and the corresponding Hamiltonian are \textit{translation and rotation in the tangent space}. Diffeomorphism invariance, though a manifest invariance of the action, is not generated by the first class constraints of the theory.Comment: 44 pages, references are added, organization of material is slightly modified (additional section is introduced), more details of calculation of the Dirac bracket between translational and rotational constraints are provide

The IFMIF-DONES Project: Design Status and Main Achievements Within the EUROfusion FP8 Work Programme

International Fusion Materials Irradiation Facility-DEMO-Oriented NEutron Source (IFMIF-DONES) is a high-intensity neutron irradiation facility for qualification of fusion reactor materials, which is being designed as part of the European roadmap to fusion-generated electricity. Its main purpose is to study the behavior of materials properties under irradiation in a neutron flux able to simulate the same effects in terms of relevant nuclear responses as those expected in the first wall of the DEMO reactor which is envisaged to follow ITER. It is thus a key facility to support the design, licensing and safe operation of DEMO as well as of the fusion power plants that will be developed afterwards. The start of its construction is foreseen in the next few years. In this contribution, an overview of the IFMIF-DONES neutron source is presented together with a snapshot of the current engineering design status and of the relevant key results achieved within the EUROfusion Work Package Early Neutron Source (WPENS) as part of the 2014–2020 EURATOM Research and Training Programme, complementary to the EU Horizon 2020 Framework Programme (FP8). Moreover, some information on the future developments of the project are given

Biopolymer-based structuring of liquid oil into soft solids and oleogels using water-continuous emulsions as templates

Physical trapping of a hydrophobic liquid oil in a matrix of water-soluble biopolymers was achieved using a facile two-step process by first formulating a surfactant-free oil-in-water emulsion stabilized by biopolymers (a protein and a polysaccharide) followed by complete removal of the water phase (by either high- or low-temperature drying of the emulsion) resulting in structured solid systems containing a high concentration of liquid oil (above 97 wt %). The microstructure of these systems was revealed by confocal and cryo-scanning electron microscopy, and the effect of biopolymer concentrations on the consistency of emulsions as well as the dried product was evaluated using a combination of small-amplitude oscillatory shear rheometry and large deformation fracture studies. The oleogel prepared by shearing the dried product showed a high gel strength as well as a certain degree of thixotropic recovery even at high temperatures. Moreover, the reversibility of the process was demonstrated by shearing the dried product in the presence of water to obtain reconstituted emulsions with rheological properties comparable to those of the fresh emulsion