ELKO applications in cosmology

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Exact solutions to Elko spinors in spatially flat Friedmann-Robertson-Walker spacetimes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

CCDM model from quantum particle creation: constraints on dark matter mass

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

WIMP and SIMP dark matter from the spontaneous breaking of a global group

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Leading particle effect, inelasticity, and the connection between average multiplicities in e+e- and pp processes

The Regge-Mueller formalism is used to describe the inclusive spectrum of the proton in pp collisions. From such a description the energy dependences of both average inelasticity and leading proton multiplicity are calculated. These quantities are then used to establish the connection between the average charged particle multiplicities measured in e+e- and pp/p̄p processes. The description obtained for the leading proton cross section implies that Feynman scaling is strongly violated only at the extreme values of xF, that is at the central region (xF≈0) and at the diffraction region (XF≈1), while it is approximately observed in the intermediate region of the spectrum. ©1999 The American Physical Society.

Effect Of Platform Connection And Abutment Material On Stress Distribution In Single Anterior Implant-supported Restorations: A Nonlinear 3-dimensional Finite Element Analysis.

Although various abutment connections and materials have recently been introduced, insufficient data exist regarding the effect of stress distribution on their mechanical performance. The purpose of this study was to investigate the effect of different abutment materials and platform connections on stress distribution in single anterior implant-supported restorations with the finite element method. Nine experimental groups were modeled from the combination of 3 platform connections (external hexagon, internal hexagon, and Morse tapered) and 3 abutment materials (titanium, zirconia, and hybrid) as follows: external hexagon-titanium, external hexagon-zirconia, external hexagon-hybrid, internal hexagon-titanium, internal hexagon-zirconia, internal hexagon-hybrid, Morse tapered-titanium, Morse tapered-zirconia, and Morse tapered-hybrid. Finite element models consisted of a 4×13-mm implant, anatomic abutment, and lithium disilicate central incisor crown cemented over the abutment. The 49 N occlusal loading was applied in 6 steps to simulate the incisal guidance. Equivalent von Mises stress (σvM) was used for both the qualitative and quantitative evaluation of the implant and abutment in all the groups and the maximum (σmax) and minimum (σmin) principal stresses for the numerical comparison of the zirconia parts. The highest abutment σvM occurred in the Morse-tapered groups and the lowest in the external hexagon-hybrid, internal hexagon-titanium, and internal hexagon-hybrid groups. The σmax and σmin values were lower in the hybrid groups than in the zirconia groups. The stress distribution concentrated in the abutment-implant interface in all the groups, regardless of the platform connection or abutment material. The platform connection influenced the stress on abutments more than the abutment material. The stress values for implants were similar among different platform connections, but greater stress concentrations were observed in internal connections.

New coupled quintessence cosmology

A component of dark energy has been recently proposed to explain the current acceleration of the Universe. Unless some unknown symmetry in Nature prevents or suppresses it, such a field may interact with the pressureless component of dark matter, giving rise to the so-called models of coupled quintessence. In this paper we propose a new cosmological scenario where radiation and baryons are conserved, while the dark energy component is decaying into cold dark matter. The dilution of cold dark matter particles, attenuated with respect to the usual a(-3) scaling due to the interacting process, is characterized by a positive parameter epsilon, whereas the dark energy satisfies the equation of state p(x) = omega rho(x) (omega < 0). We carry out a joint statistical analysis involving recent observations from type Ia supernovae, baryon acoustic oscillation peak, and cosmic microwave background shift parameter to check the observational viability of the coupled quintessence scenario here proposed.

Is there a connection between long airplane flight, venous thromboembolism, and sleep-disordered breathing?

Commercial passenger flights have been increasing around the world. The effect of these flights on health is unclear. Venous thromboembolism has been noted after recent long-distance airplane flight, even in the absence of other risk factors. Hypoxia caused by the low ambient pressure during flights could contribute, and individuals with obstructive sleep apnea may be particularly vulnerable. The association between the effects of long airplane travel and sleep-disordered breathing deserves further study. (C) 2008 Elsevier B.V. All rights reserved.

Connection Admission Control for a WDM Optical Network Based on Traffic Monitoring and Bandwidth Release

We proposed a connection admission control (CAC) to monitor the traffic in a multi-rate WDM optical network. The CAC searches for the shortest path connecting source and destination nodes, assigns wavelengths with enough bandwidth to serve the requests, supervises the traffic in the most required nodes, and if needed activates a reserved wavelength to release bandwidth according to traffic demand. We used a scale-free network topology, which includes highly connected nodes ( hubs), to enhance the monitoring procedure. Numerical results obtained from computational simulations show improved network performance evaluated in terms of blocking probability.

Analysis of a semi-rigid connection for precast concrete

This paper presents a study of a specific type of beam-to-column connection for precast concrete structures. Furthermore, an analytical model to determine the strength and the stiffness of the connection, based on test results of two prototypes, is proposed. To evaluate the influence of the strength and stiffness of the connection on the behaviour of the structure, the results of numerical simulations of a typical multi-storey building with semi-rigid connections are also presented and compared with the results using pinned and rigid connections. The main conclusions are: (a) the proposed design model can reasonably evaluate the studied connection strength; (b) the evaluation of strength is more accurate than that of stiffness; (c) for a typical structure, it is possible to increase the number of storeys of the structure from two to four with lower horizontal displacement at the top, and only a small increase of the column base bending moment by replacing the pinned connections with semi-rigid ones; and (d) although there is significant uncertainty in the connection stiffness, the results show that the displacements at the top of the structure, and the column base moments present low susceptibility deviations to this parameter.

Column connection detail, Kangaroo Point House

Hand-made spotted gum column on edge of outdoor room.

Post and beam connection, PNG Coffee Industry Board Office and Warehouse, Goroka

Detailed view of cast iron brackets connecting beams and posts.

Post and beam connection, PNG Coffee Industry Board Office and Warehouse, Goroka

Detailed view of cast iron brackets connecting beams and posts.

Corner connection detail, Sunshine Coast University Library, Maroochydore

Detailed external view of north-west elevation corner.

North-east verandah connection, Sunshine Coast University Library, Maroochydore

View of underside of verandah corrugated steel roofing, polycarbonate sheeting and north-east glass and floor connection.