Quantum Isotropization of the Universe

We consider minisuperspace models constituted of Bianchi I geometries with a free massless scalar field. The classical solutions are always singular (with the trivial exception of flat space-time), and always anisotropic once they begin anisotropic. When quantizing the system, we obtain the Wheeler-DeWitt equation as a four-dimensional massless Klein-Gordon equation. We show that there are plenty of quantum states whose corresponding bohmian trajectories may be non-singular and/or presenting large isotropic phases, even if they begin anisotropic, due to quantum gravitational effects. As a specific example, we exhibit field plots of bohmian trajectories for the case of gaussian superpositions of plane wave solutions of the Wheeler-DeWitt equation which have those properties. These conclusions are valid even in the absence of the scalar field.Comment: 10 pages, RevTeX, 3 Postscript figures, uses graficx.st

Contribución al estudio de las mineralizaciones Pb-Zn en el entorno macizo granítico de las Peñas de Haya (Guipúzcoa-Navarra)

Se presenta un primer estudio de las mineralizaciones filonianas PbZn asociadas a pizarras oscuras v granito tardihercínico. Las menas y gangas aparecen fuertemente deformadas y brechificadas y es frecuente la removilización de los sulfuros. En el proceso de formación de estas mineralizaciones se distinguen varias fases: una fase hidrotermal de edad hercínica post-intrusiva y una última fase de removilización. Las paragénesis principales permiten clasificar estos yacimientos como mesotermales. Se discuten los modelos genéticos más probables

Static quantities of a neutral bilepton in the 331 model with right-handed neutrinos

A neutral vector boson can possess static electromagnetic properties provided that the associated field is no self-conjugate. This possibility is explored in the $SU_C(3) X SU_L(3) X U_N(1)$ model with right-handed neutrinos, which predicts a complex neutral gauge boson $Y^0$ in a nontrivial representation of the electroweak group. In this model the only nonvanishing form factors are the CP-even ones, which arise from both the quark and gauge sectors, and contribute to the magnetic dipole and the electric quadrupole moments of this neutral particle.Comment: 10 pages, 6 figures, submitted to Phys. Rev.

Best practice in undertaking and reporting health technology assessments : Working Group 4 report

[Executive Summary] The aim of Working Group 4 has been to develop and disseminate best practice in undertaking and reporting assessments, and to identify needs for methodologic development. Health technology assessment (HTA) is a multidisciplinary activity that systematically examines the technical performance, safety, clinical efficacy, and effectiveness, cost, costeffectiveness, organizational implications, social consequences, legal, and ethical considerations of the application of a health technology (18). HTA activity has been continuously increasing over the last few years. Numerous HTA agencies and other institutions (termed in this report “HTA doers”) across Europe are producing an important and growing amount of HTA information. The objectives of HTA vary considerably between HTA agencies and other actors, from a strictly political decision making–oriented approach regarding advice on market licensure, coverage in benefits catalogue, or investment planning to information directed to providers or to the public. Although there seems to be broad agreement on the general elements that belong to the HTA process, and although HTA doers in Europe use similar principles (41), this is often difficult to see because of differences in language and terminology. In addition, the reporting of the findings from the assessments differs considerably. This reduces comparability and makes it difficult for those undertaking HTA assessments to integrate previous findings from other HTA doers in a subsequent evaluation of the same technology. Transparent and clear reporting is an important step toward disseminating the findings of a HTA; thus, standards that ensure high quality reporting may contribute to a wider dissemination of results. The EUR-ASSESS methodologic subgroup already proposed a framework for conducting and reporting HTA (18), which served as the basis for the current working group. New developments in the last 5 years necessitate revisiting that framework and providing a solid structure for future updates. Giving due attention to these methodologic developments, this report describes the current “best practice” in both undertaking and reporting HTA and identifies the needs for methodologic development. It concludes with specific recommendations and tools for implementing them, e.g., by providing the structure for English-language scientific summary reports and a checklist to assess the methodologic and reporting quality of HTA reports

Bilepton effects on the WWV^* vertex in the 331 model with right-handed neutrinos via a SU_L(2)XU_Y(1) covariant quantization scheme

In a recent paper, we investigated the effects of the massive charged gauge bosons (bileptons) predicted by the minimal 331 model on the off-shell vertex WWV^* (V=gamma, Z) using a SU_L(2) X U_Y(1) covariant gauge-fixing term for the bileptons. We proceed along the same lines and calculate the effects of the gauge bosons predicted by the 331 model with right-handed neutrinos. It is found that the bilepton effects on the WWV^* vertex are of the same order of magnitude than those arising from the SM and several of its extensions, provided that the bilepton mass is of the order of a few hundred of GeVs. For heavier bileptons, their effects on the WWV^* vertex are negligible. The behavior of the form factors at high energies is also discussed as it is a reflect of the gauge invariance and gauge independence of the WWV^* Green function obtained via our quantization method.Comment: Replaced to match published versio

Distribution patterns of bottom trawl faunal assemblages in Porcupine bank: implications for Porcupine surveys stratification design.

The distribution patterns of bottom trawl faunal assemblages in Porcupine bank is addressed using data from two bottom trawl surveys performed in the area. Hierarchical cluster analyses and canonical ordination analyses are applied respectively to define the different assemblages and to evaluate the main structuring environmental factors using information on depth, latitude, longitude, bottom temperature and salinity. Analyses are performed with two different matrices one in numbers of individuals per species in each haul and another in biomass of main commercial species in each haul. Three large assemblages are discriminated by hierarchical cluster analyses: shelf, outer-shelf and shelf-break, with some subgroups within each of them consistent in the results of both data matrices. Depth is the main structuring environmental factor in the area. Longitude has also an important effect on the bottom trawl assemblages distribution pattern, this effect is more likely to be related with relief structure and ground types differences in both sides of Porcupine bank. The original strata design used in Porcupine surveys, based on previous information on commercial catches, does not agree with the results of this study, but more information on the bathymetry in the area is needed to implement new bathymetric strata.Versión de edito