83 research outputs found
Antecipação do período de diagnose foliar em laranjeira 'Pêra' no Amazonas.
O objetivo deste trabalho foi avaliar a possibilidade de se antecipar o período de realização da diagnose foliar em laranjeira 'Pêra'. Vinte e sete pomares representativos da região produtora de laranja do Estado do Amazonas foram monitorados durante o ano agrícola de 2011/2012. Foram realizadas diagnoses da composição nutricional (CND) em amostras foliares retiradas durante a floração e quando a árvore apresentava frutos com três e seis meses de idade (época tradicional para o monitoramento nutricional). Pomares com produtividade superior a 25 Mg ha‑1 foram selecionados para o estabelecimento dos padrões de referência. O estado nutricional da laranja variou com o estádio fenológico no qual se realizou a amostragem foliar, o que fez com que fosse necessário estabelecer normas CND para cada período. Com a antecipação da diagnose para o período de floração, observouse aumento nas concentrações foliares de N, P, K e Cu diminuição e nas de Ca. A antecipação da diagnose foliar em laranja 'Pêra' depende da geração de padrões nutricionais CND específicos para cada época de amostragem
Application of Renormalization to Potential Scattering
A recently proposed renormalization scheme can be used to deal with
nonrelativistic potential scattering exhibiting ultraviolet divergence in
momentum space. A numerical application of this scheme is made in the case of
potential scattering with divergence for small r, common in molecular
and nuclear physics, by the use of cut-offs in momentum and configuration
spaces. The cut-off is finally removed in terms of a physical observable and
model-independent result is obtained at low energies. The expected variation of
the off-shell behavior of the t matrix arising from the renormalization scheme
is also discussed.Comment: 15 pages plus 5 figure
Simulation of I-V Hysteresis Branches in An Intrinsic Stack of Josephson Junctions in High Superconductors
I-V characteristics of the high T superconductor
BiSrCaCO shows a strong hysteresis, producing many
branches. The origin of hysteresis jumps is studied by use of the model of
multi-layered Josephson junctions proposed by one of the authors (T. K.). The
charging effect at superconducting layers produces a coupling between the next
nearest neighbor phase-differences, which determines the structure of
hysteresis branches. It will be shown that a solution of phase motions is
understood as a combination of rotating and oscillating phase-differences, and
that, at points of hysteresis jumps, there occurs a change in the number of
rotating phase-differences. Effects of dissipation are analyzed. The
dissipation in insulating layers works to damp the phase motion itself, while
the dissipation in superconducting layers works to damp relative motions of
phase-differences. Their effects to hysteresis jumps are discussed.Comment: 18 pages, Latex, 8 figures. To be appear in Phys.Rev.B Vol.60(1999
Universality in Four-Boson Systems
We report recent advances on the study of universal weakly bound four-boson
states from the solutions of the Faddeev-Yakubovsky equations with zero-range
two-body interactions. In particular, we present the correlation between the
energies of successive tetramers between two neighbor Efimov trimers and
compare it to recent finite range potential model calculations. We provide
further results on the large momentum structure of the tetramer wave function,
where the four-body scale, introduced in the regularization procedure of the
bound state equations in momentum space, is clearly manifested. The results we
are presenting confirm a previous conjecture on a four-body scaling behavior,
which is independent of the three-body one. We show that the correlation
between the positions of two successive resonant four-boson recombination peaks
are consistent with recent data, as well as with recent calculations close to
the unitary limit. Systematic deviations suggest the relevance of range
corrections.Comment: Accepted for publication in special issue of Few-Body Systems devoted
to the Sixth Workshop on the Critical Stability of Quantum Few-Body Systems,
October 2011, Erice, Sicily, Ital
Environmental restoration by aquatic angiosperm transplants in transitional water systems: The Venice Lagoon as a case study
The paper reports the results obtained after 4 years of aquatic angiosperm transplants in areas of the Venice Lagoon (North Adriatic Sea, Mediterranean) where meadows almost disappeared due to eutrophication, pollution and overexploitation of clam resources. The project LIFE12 NAT/IT/000331-SeResto, funded by the European Union, allowed to recolonize the Habitat 1150* (coastal lagoons) in the northernmost part of the lagoon, by extensive manual transplants of small sods or single rhizomes of Zostera marina, Zostera noltei, Ruppia cirrhosa and, in some stations also of Cymodocea nodosa. Over the 4 years of the project more than 75,000 rhizomes were transplanted in 35 stations with the support of local stakeholders (fishermen, hunters and sport clubs). Plants took root in 32 stations forming extensive meadows on a surface of approx. 10 km2 even if some failures were recorded in areas affected by outflows of freshwater rich in nutrients and suspended particulate matter. The rapid recovery of the ecological status of the involved areas was the result of this meadow restoration, which was in compliance with Water Framework Directive (WFD 2000/60/EC) objectives. Moreover, the monitoring of environmental parameters in the water column and in surface sediments allowed to identify the best conditions for successful transplants. Small, widespread interventions and the participation of local stakeholders in the environmental recovery, make this action economically cheap and easily transposable in other similar environments
Pentaquark as Kaon-Nucleon Resonance
Several recent experiments have reported evidence for a narrow feature in the
K(+)-neutron system, an apparent resonant state ~ 100 MeV above threshold and
with a width < 25 MeV. This state has been labelled as Theta(+) (previously as
Z(*)), and because of the implied inclusion of a anti-strange quark, is
referred to as a pentaquark, that is, five quarks within a single bag. We
present an alternative explanation for such a structure, as a higher angular
momentum resonance in the isospin zero K(+) -N system. One might call this an
exit channel or a molecular resonance. In a non-relativistic potential model we
find a possible candidate for the kaon-nucleon system with relative angular
momentum L=3, while L=1 and 2 states possess centrifugal barriers too low to
confine the kaon and nucleon in a narrow state at an energy so high above
threshold. A rather strong state-dependence in the potential is essential,
however, for eliminating an observable L=2 resonance at lower energies.Comment: 4 page
Pairing Symmetry Competition in Organic Superconductors
A review is given on theoretical studies concerning the pairing symmetry in
organic superconductors. In particular, we focus on (TMTSF)X and
-(BEDT-TTF)X, in which the pairing symmetry has been extensively
studied both experimentally and theoretically. Possibilities of various pairing
symmetry candidates and their possible microscopic origin are discussed. Also
some tests for determining the actual pairing symmtery are surveyed.Comment: 16 pages, 8 figures, to be published in J. Phys. Soc. Jpn., special
issue on "Organic Conductors
Effect of Coulomb Forces on the Position of the Pole in the Scattering Amplitude and on Its Residue
Explicit expressions of the vertex constant for the decay of a nucleus into
two charged particles for an arbitrary orbital momentum are derived for the
standard expansion of the effective-range function , as well as when
the function has a pole. As physical examples, we consider the bound
state of the nucleus and the resonant states of the nuclei
He and He in the s-wave, and those of and
in the p-wave. For the systems and the pole
trajectories are constructed in the complex planes of the momentum and of the
renormalized vertex constant. They correspond to a transition from the
resonance state to the virtual state while the Coulomb forces gradually
decrease to zero.Comment: 17 pages, 5 figure
Receita pública e bem-estar social nos municípios mineiros emancipados no período de 1988 a 1997
O movimento de descentralizações política, administrativa e fiscal intensificado a partir de 1988 tinha como objetivo promover a transferência de poder, recursos e atribuições para os governos locais. Além disso, esse fenômeno impulsionou o processo de emancipação municipal com o intuito de aproximar o poder público da sociedade, promovendo a melhoria da prestação de serviços. Este estudo apresenta a análise das receitas públicas e do bem-estar social dos municípios mineiros emancipados no período de 1988 a 1997. Para tanto, utilizaram-se testes de médias no intuito de comparar o desempenho dos municípios emancipados com o desempenho de seus municípios de origem. Como conclusão, verificou-se que os novos municípios são beneficiados com as transferências governamentais e possuem a mesma capacidade de arrecadação tributária dos seus municípios de origem. Não obstante, isso não permitiu que os citados municípios apresentassem nível de bem-estar superior em relação aos municípios de origem, assim como maior eficiência na gestão desses recursos, uma vez que estão mais próximos dos usuários
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