Subjective Quality Assessment of the Impact of Buffer Size in Fine-Grain Parallel Video Encoding

Fine-Grain parallelism is essential for real-time video encoding performance. This usually implies setting a fixed buffer size for each encoded block. The choice of this parameter is critical for both performance and hardware cost. In this paper we analyze the impact of buffer size on image subjective quality, and its relation with other encoding parameters. We explore the consequences on visual quality, when minimizing buffer size to the point of causing the discard of quantized coefficients for highest frequencies. Finally, we propose some guidelines for the choice of buffer size, that has proven to be heavily dependent, in addition to other parameters, on the type of sequence being encoded. These guidelines are useful for the design of efficient realtime encoders, both hardware and software

Natural PQ symmetry in the 3-3-1 model with a minimal scalar sector

In the framework of a 3-3-1 model with a minimal scalar sector we make a detailed study concerning the implementation of the PQ symmetry in order to solve the strong CP problem. For the original version of the model, with only two scalar triplets, we show that the entire Lagrangian is invariant under a PQ-like symmetry but no axion is produced since an U(1) subgroup remains unbroken. Although in this case the strong CP problem can still be solved, the solution is largely disfavored since three quark states are left massless to all orders in perturbation theory. The addition of a third scalar triplet removes the massless quark states but the resulting axion is visible. In order to become realistic the model must be extended to account for massive quarks and invisible axion. We show that the addition of a scalar singlet together with a Z_N discrete gauge symmetry can successfully accomplish these tasks and protect the axion field against quantum gravitational effects. To make sure that the protecting discrete gauge symmetry is anomaly free we use a discrete version of the Green-Schwarz mechanism.Comment: 18 pages, 1 figure, 3 table

Rb-Sr and single - zircon grain 207Pb / 206Pb chronology of the Monesterio granodiorite and related migmatites. Evidence of a Late Cambrian melting event in the Ossa-Morena Zone, Iberian Massif

The Monesterio granodiorite, a small granodioritic body placed in a migmatitic complex in the SW of the Olivenza-Monesterio antiform, is a key plutonic body to understanding the relationships among the magmatism, metamorphism, and deformation in the Ossa-Morena Zone, SW Iberian Massif. We dated the granodiorite with the single zircon stepwise-evaporation 207Pb/206Pb method, and the related migmatization event with the Rb-Sr method on leucosomes. Our results indicate that the Monesterio granodiorite crystallised at 510 ± 7 Ma and its protolith had a component with Upper Proterozoic zircons with a minimum age of 1696 Ma. Leucosomes give a Rb-Sr age of 511 ± 40 Ma (MSWD =1,7) with initial 87Sr/86Sr =0.70914 ± 0.00048. The lower initial 87Sr/86Sr of the granodiorite and its calc-alkaline chemistry precludes it from having derived from the same protolith as the migmatites. The existence of different magmatic bodies in the Ossa-Morena Zone with ages clustering around 500-510 Ma reveals the existence of a significant melting event during the Late Cambrian that involved protoliths with very different geochemical and isotopic signatures.La granodiorita de Monesterio es un pequeño cuerpo emplazado en un complejo migmatítico en el SO del antiforme Olivenza-Monesterio, importante para entender las relaciones entre magmatismo, metamorfismo y deformación en la Zona de Ossa-Morena. Se ha datado la granodiorita por el método de evaporación secuencial de 207Pb/206Pb en cristal único de circón y los leucosomes de las migmatitas circundantes por el método Rb-Sr. Los datos indican una edad de cristalización de la granodiorita de 510 ± 4 Ma y un posible protolito Proterozoico Superior con una edad mínima de ∼1.700 Ma, obtenida a partir de núcleos heredados de los circones analizados. Los leucosomes dan una edad Rb-Sr de 511 ± 40 Ma, con una relación 87Sr/86Sr=0,70914 ± 0,00048. La relación inicial de 87Sr/86Sr en la granodiorita (∼0,7049) es mucho más baja que en los leucosomes, lo que junto con su naturaleza calcoalcalina indica que no derivan del mismo protolito. La existencia en la zona de Ossa-Morena de diferentes cuerpos magmáticos con edades en tomo a 500-510 Ma, indica un evento de fusión importante durante el Cámbrico Superior desarrollado sobre protolitos con características geoquímicas e isotópicas muy diferentes

SU(3)_LxU(1)_N Model for Right-Handed Neutrino Neutral Currents

A model based on the \mbox{SU(3)}_L\otimes \mbox{U(1)}_N gauge group, in which neutrinos have right-handed neutral currents is considered. We argue that in order to have a result consistent with low-energy one, the right-handed neutrino component must be treated as correction instead of an equivalent spin state.Comment: 6 pages, Latex, no figures, Accepted for publication in Phys. Rev.

Volume fluctuations and compressibility of a vibrated granular gas

The volume fluctuations in the steady state reached by a vibrated granular gas of hard particles confined by a movable piston on the top are investigated by means of event driven simulations. Also, a compressibility factor, measuring the response in volume of the system to a change in the mass of the piston, is introduced and measured. From the second moment of the volume fluctuations and the compressibility factor, an effective temperature is defined, by using the same relation as obeyed by equilibrium molecular systems. The interpretation of this effective temperature and its relationship with the granular temperature of the gas, and also with the velocity fluctuations of the movable piston, is discussed. It is found that the ratio of the temperature based on the volume fluctuations to the temperature based on the piston kinetic energy, obeys simple dependencies on the inelasticity and on the piston-particle mass ratio

Comment on ``Majoron emitting neutrinoless double beta decay in the electroweak chiral gauge extensions''

We point out that if the majoron-like scheme is implemented within a 331 model, there must exist at least three different mass scales for the scalar vacuum expectation values in the model.Comment: 4 pages, no figures, Revtex. To be published in Physical Review

Lepton masses in a supersymmetric 3-3-1 model

We consider the mass generation for both charginos and neutralinos in a 3-3-1 supersymmetric model. We show that R-parity breaking interactions leave the electron and one of the neutrinos massless at the tree level. However the same interactions induce masses for these particles at the 1-loop level. Unlike the similar situation in the MSSM the masses of the neutralinos are related to the masses of the charginos.Comment: RevTex, 11 pages incluing 2 .eps figures. Extended published versio

Fixed points and vacuum energy of dynamically broken gauge theories

We show that if a gauge theory with dynamical symmetry breaking has non-trivial fixed points, they will correspond to extrema of the vacuum energy. This relationship provides a different method to determine fixed points.Comment: 17 pages, uuencoded latex file, 3 figures, uses epsf and epsfig. Submitted to Mod. Phys. Lett.