54,511 research outputs found
Gauge fields in a string-cigar braneworld
In this work we investigate the properties of an Abelian gauge vector field
in a thin and in a smoothed string-like braneworld, the so-called string-cigar
model. This thick brane scenario satisfies the regularity conditions and it can
be regarded as an interior and exterior string-like solution. The source
undergoes a geometric Ricci flow which is connected to a variation of the bulk
cosmological constant. The Ricci flow changes the width and amplitude of the
massless mode at the brane core and recover the usual thin string-like behavior
at large distances. By numerical means we obtain the Kaluza-Klein (KK) spectrum
for both the thin brane and the string-cigar. It turns out that both models
exhibit a mass gap between the massless and the massive modes and between the
high and the low mass regimes. The KK modes are smooth near the brane and their
amplitude are enhanced by the string-cigar core. The analogue Schr\"odinger
potential is also tuned by the geometric flow.Comment: The discussion about the Kaluza-Klein spectrum of the gauge field was
improved. Numerical analysis was adapted to the conventional notation on
Kaluza-Klein number. Some graphics were modified for considering other
notation. Results unchanged. References added. Corrected typos. 17 pages. 6
figures. To match version to appears in Physics Letters
Investigation of the agricultural resources in Sri Lanka
The author has identified the following significant results. Several in-house capabilities were developed. The facilities to prepare color composites of excellent quality were developed, using bulk B/W 70 mm transparencies or 1:1,000,000 positive transparencies. These color composites were studied through optical devices on light tables. A zoom transfer scope was also added, enabling direct transfer of LANDSAT composite data on to base maps
Pressure effect in the X-ray intrinsic position resolution in noble gases and mixtures
A study of the gas pressure effect in the position resolution of an
interacting X- or gamma-ray photon in a gas medium is performed. The intrinsic
position resolution for pure noble gases (Argon and Xenon) and their mixtures
with CO2 and CH4 were calculated for several gas pressures (1-10bar) and for
photon energies between 5.4 and 60.0 keV, being possible to establish a linear
match between the intrinsic position resolution and the inverse of the gas
pressure in that energy range. In order to evaluate the quality of the method
here described, a comparison between the available experimental data and the
calculated one in this work, is done and discussed. In the majority of the
cases, a strong agreement is observed
Recomendações técnicas para o uso agrícola do composto de lixo urbano no Estado de São Paulo.
Por que proceder a compostagem dos resíduos sólidos urbanos? Qual é a composição do lixo urbano brasileiro e paulista? Por que utilizar composto de lixo urbano na agricultura? Que efeitos pode-se esperar nas propriedades dos solos? Quais as características, maturidade e composição requeridas de compostos de lixo urbano para o seu uso na agricultura? Existe alguma legislação para o uso agrícola do composto de lixo urbano? Base científica dos índices do composto.Situação do cinturão verde de São Paulo.O risco ambiental seria apenas devido a metais pesados contidos nos resíduos sólidos? E a questão dos patógenos e outros componentes orgânicos não oferece risco à saúde das pessoas? É possível haver sanilização do solo pela aplicação do composto?Onde, quando e quanto de composto de lixo urbano deve-se aplicar nas principais culturas do Estado de São Paulo? Em síntese, que cuidados ou restrições devem ser observados para o uso agrícola do composto?bitstream/CNPTIA/9962/1/circtec3.pdfAcesso em: 28 maio 2008
Correlation length scalings in fusion edge plasma turbulence computations
The effect of changes in plasma parameters, that are characteristic near or
at an L-H transition in fusion edge plasmas, on fluctuation correlation lengths
are analysed by means of drift-Alfven turbulence computations. Scalings by
density gradient length, collisionality, plasma beta, and by an imposed shear
flow are considered. It is found that strongly sheared flows lead to the
appearence of long-range correlations in electrostatic potential fluctuations
parallel and perpendicular to the magnetic field.Comment: Submitted to "Plasma Physics and Controlled Fusion
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