The lattice Landau gauge gluon propagator: lattice spacing and volume dependence

The interplay between the finite volume and finite lattice spacing is investigated using lattice QCD simulations to compute the Landau gauge gluon propagator. Comparing several ensembles with different lattice spacings and physical volumes, we conclude that the dominant effects, in the infrared region, are associated with the use of a finite lattice spacing. The simulations show that decreasing the lattice spacing, while keeping the same physical volume, leads to an enhancement of the infrared gluon propagator. In this sense, the data from $\beta=5.7$ simulations, which uses an $a \approx 0.18$ fm, provides a lower bound for the infinite volume propagator.Comment: Final version to appear in Phys Rev

The spectral content of SDO/AIA 1600 and 1700 \AA\ filters from flare and plage observations

The strong enhancement of the ultraviolet emission during solar flares is usually taken as an indication of plasma heating in the lower solar atmosphere caused by the deposition of the energy released during these events. Images taken with broadband ultraviolet filters by the {\em Transition Region and Coronal Explorer} (TRACE) and {\em Atmospheric Imaging Assembly} (AIA 1600 and 1700~\AA) have revealed the morphology and evolution of flare ribbons in great detail. However, the spectral content of these images is still largely unknown. Without the knowledge of the spectral contribution to these UV filters, the use of these rich imaging datasets is severely limited. Aiming to solve this issue, we estimate the spectral contributions of the AIA UV flare and plage images using high-resolution spectra in the range 1300 to 1900~\AA\ from the Skylab NRL SO82B spectrograph. We find that the flare excess emission in AIA 1600~\AA\ is { dominated by} the \ion{C}{4} 1550~\AA\ doublet (26\%), \ion{Si}{1} continua (20\%), with smaller contributions from many other chromospheric lines such as \ion{C}{1} 1561 and 1656~\AA\ multiplets, \ion{He}{2} 1640~\AA, \ion{Si}{2} 1526 and 1533~\AA. For the AIA 1700~\AA\ band, \ion{C}{1} 1656~\AA\ multiplet is the main contributor (38\%), followed by \ion{He}{2} 1640 (17\%), and accompanied by a multitude of other, { weaker} chromospheric lines, with minimal contribution from the continuum. Our results can be generalized to state that the AIA UV flare excess emission is of chromospheric origin, while plage emission is dominated by photospheric continuum emission in both channels.Comment: Accepted for publication in ApJ Skylab NRL SO82B data used in this work available at http://dx.doi.org/10.5525/gla.researchdata.68

Cosmological Bianchi Class A models in S\'aez-Ballester theory

We use the S\'aez-Ballester (SB) theory on anisotropic Bianchi Class A cosmological model, with barotropic fluid and cosmological constant, using the Hamilton or Hamilton-Jacobi approach. Contrary to claims in the specialized literature, it is shown that the S\'aez-Ballester theory cannot provide a realistic solution to the dark matter problem of Cosmology for the dust epoch, without a fine tunning because the contribution of the scalar field in this theory is equivalent to a stiff fluid (as can be seen from the energy--momentum tensor for the scalar field), that evolves in a different way as the dust component. To have similar contributions of the scalar component and the dust component implies that their past values were fine tunned. So, we reinterpreting this null result as an indication that dark matter plays a central role in the formation of structures and galaxy evolution, having measureable effects in the cosmic microwave bound radiation, and than this formalism yield to this epoch as primigenius results. We do the mention that this formalism was used recently in the so called K-essence theory applied to dark energy problem, in place to the dark matter problem. Also, we include a quantization procedure of the theory which can be simplified by reinterpreting the theory in the Einstein frame, where the scalar field can be interpreted as part of the matter content of the theory, and exact solutions to the Wheeler-DeWitt equation are found, employing the Bianchi Class A cosmological models.Comment: 24 pages; ISBN: 978-953-307-626-3, InTec

Audiobooks business model - technologic challenges, case study

In English-speaking countries, the audiobook is a popular format and used very often. In Portugal the audiobook is an unknown format of the majority of the population, there are few audiobooks in Portuguese, and the ones that are found, are mostly in Brazilian Portuguese. With this work, we intend studying the business and production models present in the English-speaking countries, indicating the way for Portuguese companies to have success. In the course of this work, a preliminary recording was made, in order to know the difficulties related to the recording of an audiobook. The recording was provided to the University student community, to conduct a questionnaire about the quality of the recorded audiobook. The results of the questionnaire are presented and analyzed.info:eu-repo/semantics/publishedVersio

Audiobook- the paradigm of the portuguese publishing market

Initially, the audiobook was not a product to be marketed, being produced only for libraries, in order to allow access to information for the blind. In 2005, with the appearance of the first specialized audiobook, publishers in Portugal, the audiobooks began to be produced in order to be commercialized. The audiobook market in Portugal is small, having only 2 companies: Boca palavras que alimentam e a Companhia Nacional de Música. The Portuguese companies have very low sales volumes; which do not exceed a hundred thousand euros. The paper presents the business and production models of audiobooks in USA and proposes their adaptation to Portugal. In order to obtain the degree of acceptance of this format among the Portuguese society, two recordings of a book by a renowned Portuguese writer were made. The two records were made according to a set of technical requirements in order to ensure the quality of the audiobook. The two recordings were evaluated through a questionnaire. The results of the questionnaire are presented and analysed. From the analysis of the questionnaire, it seems that the Portuguese market of audiobooks has yet to be explored. It also seems that it worth the effort because Portuguese community is very open to new technologies and easily uses the internet market. Anyhow, it seems that some marketing campaigns are needed in order to change the actual preference of the printed book face to the virtual version.info:eu-repo/semantics/publishedVersio