8,955 research outputs found
Background field method in the Wilson formulation
A cutoff regularization for a pure Yang-Mills theory is implemented within
the background field method keeping explicit the gauge invariance of the
effective action. The method has been applied to compute the beta function at
one loop order.Comment: LaTex 13 pages, 1 figure; to appear in Nucl.Phys.
Optical Identification of He White Dwarfs Orbiting Four Millisecond Pulsars in the Globular Cluster 47 Tucanae
We used ultra-deep UV observations obtained with the Hubble Space Telescope
to search for optical companions to binary millisecond pulsars (MSPs) in the
globular cluster 47 Tucanae. We identified four new counterparts (to MSPs
47TucQ, 47TucS, 47TucT and 47TucY) and confirmed those already known (to MSPs
47TucU and 47TucW). In the color magnitude diagram, the detected companions are
located in a region between the main sequence and the CO white dwarf cooling
sequences, consistent with the cooling tracks of He white dwarfs of mass
between 0.15 Msun and 0.20 Msun. For each identified companion, mass, cooling
age, temperature and pulsar mass (as a function of the inclination angle) have
been derived and discussed. For 47TucU we also found that the past accretion
history likely proceeded in a sub-Eddington rate. The companion to the redback
47TucW is confirmed to be a non degenerate star, with properties particularly
similar to those observed for black widow systems. Two stars have been
identified within the 2-sigma astrometric uncertainty from the radio positions
of 47TucH and 47TucI, but the available data prevent us from firmly assessing
whether they are the true companions of these two MSPs.Comment: 27 pages, 7 figures, Accepted for publication by Ap
Breakdown of the Fermi-liquid regime in the 2D Hubbard model from a two-loop field-theoretical renormalization group approach
We analyze the particle-hole symmetric two-dimensional Hubbard model on a
square lattice starting from weak-to-moderate couplings by means of the
field-theoretical renormalization group (RG) approach up to two-loop order.
This method is essential in order to evaluate the effect of the
momentum-resolved anomalous dimension which arises in the
normal phase of this model on the corresponding low-energy single-particle
excitations. As a result, we find important indications pointing to the
existence of a non-Fermi liquid (NFL) regime at temperature displaying
a truncated Fermi surface (FS) for a doping range exactly in between the
well-known antiferromagnetic insulating and the -wave singlet
superconducting phases. This NFL evolves as a function of doping into a
correlated metal with a large FS before the -wave pairing
susceptibility finally produces the dominant instability in the low-energy
limit.Comment: 9 pages, 9 figures; published in Phys. Rev.
A pesquisa algodoeira no nordeste do Brasil.
Caracterizacao da producao de algodao na regiao setentrional do Brasil; Contribuicao da pesquisa e iniciativa privada a problematica do algodao do nordeste no passado; Desafios atuais; Acoes recentes da pesquisa com o algodao no nordeste; Sugestoes finais.bitstream/item/33264/1/A-PESQUISA-ALGODOEIRA.pd
Cultura do gergelim (sesamum indicum L.) no nordeste do Brasil.
Informacos gerais; Sistema de cultivo.bitstream/item/33339/1/CULTURA-DO-GERGELIM.pd
Production, breeding and potential of cowpea crop in Brazil.
About 50 years ago cowpea was reported as a relatively minor tropical legume. However, in the last years, it has been emerging as one of the most important food legume of the 21st century (SINGH, 2010). Brazil is not out of this panorama. Brazilian agriculture is undergoing major technological changes and, in addition, globalization in agribusiness has caused impacts on the production chain of several crops, particularly those heavily dependent on the use of a large volume of agricultural inputs, mainly fertilizers and pesticides. Such crops have had a higher production cost each year. On the other hand, this situation has brought new opportunities. Business farmers have sought new alternatives for their production arrangements. In this context cowpea constitutes one of the best options.bitstream/item/85620/1/Doc-216-Production.pd
Towards a new theory of practice for community health psychology
The article sets out the value of theorizing collective action from a social science perspective that engages with the messy actuality of practice. It argues that community health psychology relies on an abstract version of Paulo Freire’s earlier writing, the Pedagogy of the Oppressed, which provides scholar-activists with a ‘map’ approach to collective action. The article revisits Freire’s later work, the Pedagogy of Hope, and argues for the importance of developing a ‘journey’ approach to collective action. Theories of practice are discussed for their value in theorizing such journeys, and in bringing maps (intentions) and journeys (actuality) closer together
Reptilia, Squamata, Polychrotidae, <i>Anolis fuscoauratus</i> D'Orbigny, 1837: Distribution extension for the state of Rio Grande do Norte, Brazil
We provide the first record of Anolis fuscoauratus D’Orbigny, 1837 for the state of Rio Grande do Norte anda distribution map for the species in the Atlantic Rainforest of northeastern Brazil. The record of A. fuscoauratus in themunicipality of Tibau do Sul, state of Rio Grande do Norte, represents a distribution extension of 170 km northwesternfrom the municipality of Cabedelo, state of Paraíba. This is the northernmost record of this species in the Atlantic Rainforest
Gergelimcultura no trópico semi-árido nordestino.
Caracteristicas da semente, do oleo da torta; Condicoes climaticas favoraveis; Condicoes edaficas satisfatorias; Sistema de cultivo (Passos tecnologicos); Receitas de gergelim elaboradas pela EMATER-PB.bitstream/item/33320/1/CNPA-GERGELIMCUTLURA-NO-TROPICO-SEMI-ARIDO-NORDESTINO-LV-2004-00737.pd
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