24,623 research outputs found
Probing the two-scale-factor universality hypothesis by exact rotation symmetry-breaking mechanism
We probe the two-scale factor universality hypothesis by evaluating, firstly
explicitly and analytically at the one-loop order, the loop quantum corrections
to the amplitude ratios for O() scalar field theories with
rotation symmetry-breaking in three distinct and independent methods in which
the rotation symmetry-breaking mechanism is treated exactly. We show that the
rotation symmetry-breaking amplitude ratios turn out to be identical in the
three methods and equal to their respective rotation symmetry-breaking ones,
although the amplitudes themselves, in general, depend on the method employed
and on the rotation symmetry-breaking parameter. At the end, we show that all
these results can be generalized, through an inductive process based on a
general theorem emerging from the exact calculation, to any loop level and
physically interpreted based on symmetry ideas.Comment: 17 pages, 3 figure
Experimental Observation of Quantum Correlations in Modular Variables
We experimentally detect entanglement in modular position and momentum
variables of photon pairs which have passed through -slit apertures. We
first employ an entanglement criteria recently proposed in [Phys. Rev. Lett.
{\bf 106}, 210501 (2011)], using variances of the modular variables. We then
propose an entanglement witness for modular variables based on the Shannon
entropy, and test it experimentally. Finally, we derive criteria for
Einstein-Podolsky-Rosen-Steering correlations using variances and entropy
functions. In both cases, the entropic criteria are more successful at
identifying quantum correlations in our data.Comment: 7 pages, 4 figures, comments welcom
Magnetic phases evolution in the LaMn1-xFexO3+y system
We have investigated the crystal structure and magnetic properties for
polycrystalline samples of LaMn1-xFexO3+y, in the whole range x=0.0 to x=1.0,
prepared by solid state reaction in air. All samples show the ORT-2
orthorhombic structure that suppresses the Jahn-Teller distortion, thus
favoring a ferromagnetic (FM) superexchange (SE) interaction between
Mn^{3+}-O-Mn^{3+}. For x=0.0 the oxygen excess (y ~ 0.09) produces vacancies in
the La and Mn sites and generates a fraction around 18% of Mn^{4+} ions and 82%
of the usual Mn^{3+} ions, with possible double exchange interaction between
them. The Fe doping in this system is known to produce only stable Fe^{3+}
ions. We find an evolution from a fairly strong FM phase with a Curie
temperature T_{C} ~ 160 K, for x=0.0, to an antiferromagnetic (AFM) phase with
T_{N} = 790 K, for x=1.0, accompanied by clear signatures of a cluster-glass
behavior. For intermediate Fe contents a mixed-phase state occurs, with a
gradual decrease (increase) of the FM (AFM) phase, accompanied by a systematic
transition broadening for 0.2 < x < 0.7. A model based on the expected exchange
interaction among the various magnetic-ion types, accounts very well for the
saturation-magnetization dependence on Fe doping.Comment: 27 pages, 9 figure
Technologies for creation or rehabilitation of urban neigh-bourhoods in energy-effícient communities
Due to the rapid urbanization process, more than 50% of the world population li- ves today in urban areas, and considering the case of Portugal, this figure exceeds even 70% and with a tendency to increase. This continuous search for cities and the urban lifestyle, generates an increasing con- sumption of resources, and many of these are non-renewable. Energy is now intrinsi- cally linked to technological development, given it powers all such systems. The use of fossil fuels to supply the required energy is causing global environmental and health issues and is impacting on all Ufe forms on the planet. Tlierefore, it is necessary to replace fossil fuels with renewable energies, biofuels and eco materials and related tech- nologies and to try and find a way to deve- lop sustainable zero emission Solutions for all urban areas.Tlie energy matrix in which cities were established is based on non-renewable and highly polluting forms. In this way, it is necessary to create urban strategies and tech- nologies that allow the creation of energy efficient urban communities. So, this article aims to discuss energy-efficiency in communities, management Systems and energy use strategies. As an example, they are pre- sented Portuguese case studies of recogni- sed merit
Ureia com tecnologias agregadas na produção de milho em um cambissolo.
bitstream/item/142257/1/BP-94.pd
Assessment of carotenoids in pumpkins after different home cooking conditions.
The aim of this study was to assess the total carotenoid, a- and B-carotene, and 9 and 13-Z- B-carotene isomer contents in C. moschata after different cooking processes
Selection of cotton lines for high oil content.
The objective of this work was to evaluate the oil content and characters related to fiber quality and yield in cotton lines (Gossypium hirsutum), in order to select genotypes with high oil content and acceptable levels of the other characters. Twenty-two F6 lines and three checks were cultivated in three field trials ? two in the municipality of Apodi, in the state of Rio Grande do Norte, and one in the municipality of Barbalha, in the state of Ceará, both in Brazil. The genetic parameters and the genetic gain from selecting 20% of the lines were estimated according to their means in each environment and in the group of environments. Regarding oil content, there is genetic variability, and the selection based on the overall mean is indicated, since this character showed high heritability, with 4.58% expected gain. The lines selected with this criterion have oil contents between 23.52 and 24.51%, which are higher than those of the Brazilian cultivar BRS Aroeira with the highest grain oil content (22.04%).Título em português: Seleção de linhagens de algodão para alto teor de óleo
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