38,039 research outputs found
An approach for the detection of point-sources in very high resolution microwave maps
This paper deals with the detection problem of extragalactic point-sources in
multi-frequency, microwave sky maps that will be obtainable in future cosmic
microwave background radiation (CMB) experiments with instruments capable of
very high spatial resolution. With spatial resolutions that can be of order of
0.1-1.0 arcsec or better, the extragalactic point-sources will appear isolated.
The same holds also for the compact structures due to the Sunyaev-Zeldovich
(SZ) effect (both thermal and kinetic). This situation is different from the
maps obtainable with instruments as WMAP or PLANCK where, because of the
smaller spatial resolution (approximately 5-30 arcmin), the point-sources and
the compact structures due to the SZ effect form a uniform noisy background
(the "confusion noise"). Hence, the point-source detection techniques developed
in the past are based on the assumption that all the emissions that contribute
to the microwave background can be modeled with homogeneous and isotropic
(often Gaussian) random fields and make use of the corresponding spatial
power-spectra. In the case of very high resolution observations such an
assumption cannot be adopted since it still holds only for the CMB. Here, we
propose an approach based on the assumption that the diffuse emissions that
contribute to the microwave background can be locally approximated by
two-dimensional low order polynomials. In particular, two sets of numerical
techniques are presented containing two different algorithms each. The
performance of the algorithms is tested with numerical experiments that mimic
the physical scenario expected for high Galactic latitude observations with the
Atacama Large Millimeter/Submillimeter Array (ALMA).Comment: Accepted for publication on "Astronomy & Astrophysics". arXiv admin
note: substantial text overlap with arXiv:1206.4536 Replaced version is the
accepted one and published in A&
On the particle spectrum and the conformal window
We study the SU(3) gauge theory with twelve flavours of fermions in the
fundamental representation as a prototype of non-Abelian gauge theories inside
the conformal window. Guided by the pattern of underlying symmetries, chiral
and conformal, we analyze the two-point functions theoretically and on the
lattice, and determine the finite size scaling and the infinite volume fermion
mass dependence of the would-be hadron masses. We show that the spectrum in the
Coulomb phase of the system can be described in the context of a universal
scaling analysis and we provide the nonperturbative determination of the
fermion mass anomalous dimension gamma*=0.235(46) at the infrared fixed point.
We comment on the agreement with the four-loop perturbative prediction for this
quantity and we provide a unified description of all existing lattice results
for the spectrum of this system, them being in the Coulomb phase or the
asymptotically free phase. Our results corroborate the view that the fixed
point we are studying is not associated to a physical singularity along the
bare coupling line and estimates of physical observables can be attempted on
either side of the fixed point. Finally, we observe the restoration of the U(1)
axial symmetry in the two-point functions.Comment: 40 pages, 22 figure
One,Two,Zero: Scales of Strong Interactions
We discuss our results on QCD with a number of fundamental fermions ranging
from zero to sixteen. These theories exhibit a wide array of fascinating
phenomena which have been under close scrutiny, especially in recent years,
first and foremost is the approach to conformality. To keep this review
focused, we have chosen scale generation, or lack thereof as a guiding theme,
however the discussion will be set in the general framework of the analysis of
the phases and phase transitions of strong interactions at zero and nonzero
temperature.Comment: 15 pages, prepared for IJMPA Special Issue 'Recent Nonperturbative
Developments in QCD-like Theories
Chiral symmetry restoration in QCD with many flavours
We discuss the phases of QCD in the parameter space spanned by the number of
light flavours and the temperature with respect to the realisation of chiral
and conformal symmetries. The intriguing interplay of these symmetries is best
studied by means of lattice simulations, and some selected results from our
recent work are presented here.Comment: 10 pages, proceedings of the 9th International Workshop on Critical
Point and Onset of Deconfinement, 17-21 November, 2014, ZiF, Bielefeld,
German
Avaliação de novas cultivares de estilosantes consorciadas com gramíneas tropicais para produção de carne bovina.
O objetivo desse trabalho foi estudar a consorciação de quatro ecotipos de estilosantes (um Stylosantes capitata; dois de Stylosanthes seabrana, um multilinha de Stylosanthes macrocephala) e do estilosantecampo- grande com as gramíneas Brachiaria decumbens, Brachiaria brizanta cv. Marandu e Andropogon gayanus cv Planaltina sob pastejo para a produção de carne
O sistema agrissilvipastoril como alternativa de recuperação de áreas degradadas da Bacia Hidrográfica do Rio Formoso.
Screening preliminar dos contaminantes emergentes encontrados em ETEs da região metropolitana do Recife-PE empregando cromatografia líquida acoplada à espectrometria de massas de alta resolução.
Importância da distribuição de chuvas para o cultivo de milho no agreste sergipano.
O Agreste Sergipano é uma das mesorregiões onde a cultura do milho é cultivada com alta tecnologia. Nesse contexto, os efeitos relacionados ao déficit hídrico podem trazer perdas significativas à produtividade. O objetivo desse trabalho foi avaliar o possível efeito da distribuição de chuvas sobre o comportamento produtivo do milho em um experimento de campo em dois anos agrícolas. O estudo foi realizado na Estação Experimental Jorge Sobral da Embrapa Tabuleiros Costeiros, localizada no município de Nossa Senhora das Dores (SE), por meio da execução de um experimento de campo, conduzido nas safras de 2012 e 2013. Concluiu-se que a safra de 2012, mesmo com precipitações abaixo da média dos últimos 10 anos, teve uma produtividade absoluta maior quando comparada com a safra de 2013
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