2,983 research outputs found
Neutron Charge Radius: Relativistic Effects and the Foldy Term
The neutron charge radius is studied within a light-front model with
different spin coupling schemes and wave functions. The cancellation of the
contributions from the Foldy term and Dirac form factor to the neutron charge
form factor is verified for large nucleon sizes and it is independent of the
detailed form of quark spin coupling and wave function. For the physical
nucleon our results for the contribution of the Dirac form factor to the
neutron radius are insensitive to the form of the wave function while they
strongly depend on the quark spin coupling scheme.Comment: 12 pages, 5 figures, Latex, Int. J. Mod. Phys.
Doses de esterco bovino nas características agronômicas e de fibras do algodoeiro herbáceo BRS Rubi.
Two Kerr black holes with axisymmetric spins: An improved Newtonian model for the head-on collision and gravitational radiation
We present a semi-analytical approach to the interaction of two (originally)
Kerr black holes through a head-on collision process. An expression for the
rate of emission of gravitational radiation is derived from an exact solution
to the Einstein's field equations. The total amount of gravitational radiation
emitted in the process is calculated and compared to current numerical
investigations. We find that the spin-spin interaction increases the emission
of gravitational wave energy up to 0.2% of the total rest mass. We discuss also
the possibility of spin-exchange between the holes.Comment: 8 pages, RevTeX, 2 figures, psbox macro include
Ensacamento de frutos de abiu visando à proteção contra o ataque da mosca-das-frutas.
O abiu (Pouteria caimito) é fruto bastante conhecido nos trópicos e consumido in natura. Dentre os principais problemas que afetam a qualidade dos frutos, estão os danos causados por ataque da larva de mosca-das-frutas. O objetivo do trabalho foi determinar o diâmetro do fruto de abiu para efetivar a prática do ensacamento, visando à proteção contra o ataque da mosca. Para isto, foram estabelecidas seis classes de diâmetros: a) frutos com diâmetro menor que 1 cm; b) frutos com diâmetro de 1 a 2 cm; c) frutos com diâmetro de 2 a 3 cm; d) frutos com diâmetro de 3 a 4 cm; e) frutos com diâmetro de 4 a 5 cm; f) frutos com diâmetro maior que 5 cm, e o tratamento-testemunha, que constou de frutos sem proteção. Os sacos para a cobertura dos frutos foram confeccionados em TNT, na cor branca. Após a colheita, os frutos foram medidos e pesados, e depois partidos nos sentidos longitudinal e transversal e avaliados por meio da observação visual, quanto à presença ou ausência de larva da mosca-das-frutas. A eficiência dos tratamentos foi avaliada pela porcentagem de frutos caídos ao chão, e de frutos colhidos com ausência e presença da larva. Foram observados 96,7; 88,3 e 40,0% de queda nos frutos ensacados com diâmetro menor que 1 cm; 1-2 cm, e 2-3 cm, respectivamente. O ensacamento de frutos de abiu com diâmetro entre 1 e 2 cm não é viável devido à alta porcentagem de frutos caídos (96,7%). A maior porcentagem de frutos colhidos sem larva da mosca-dasfrutas (83,3%) é verificada quando os frutos foram ensacados com diâmetro entre três e cinco centímetros
Comparative proteomics between natural Microcystis isolates with a focus on microcystin synthesis.
Produção, qualidade dos frutos e teores de nitrogênio foliar em maracujazeiro-amarelo sob adubação nitrogenada.
Quantum dot to disordered wire crossover: A complete solution in all length scales for systems with unitary symmetry
We present an exact solution of a supersymmetric nonlinear sigma model
describing the crossover between a quantum dot and a disordered quantum wire
with unitary symmetry. The system is coupled ideally to two electron reservoirs
via perfectly conducting leads sustaining an arbitrary number of propagating
channels. We obtain closed expressions for the first three moments of the
conductance, the average shot-noise power and the average density of
transmission eigenvalues. The results are complete in the sense that they are
nonperturbative and are valid in all regimes and length scales. We recover
several known results of the recent literature by taking particular limits.Comment: 4 page
Aspectos morfológicos e citoquímicos das células sanguíneas de três espécies de quelônios recém eclodidos da Reserva Biológica do Abufari, Amazonas, Brasil.
Nonequilibrium Zaklan model on Apollonian Networks
The Zaklan model had been proposed and studied recently using the equilibrium
Ising model on Square Lattices (SL) by Zaklan et al (2008), near the critica
temperature of the Ising model presenting a well-defined phase transition; but
on normal and modified Apollonian networks (ANs), Andrade et al. (2005, 2009)
studied the equilibrium Ising model. They showed the equilibrium Ising model
not to present on ANs a phase transition of the type for the 2D Ising model.
Here, using agent-based Monte-Carlo simulations, we study the Zaklan model with
the well-known majority-vote model (MVM) with noise and apply it to tax evasion
on ANs, to show that differently from the Ising model the MVM on ANs presents a
well defined phase transition. To control the tax evasion in the economics
model proposed by Zaklan et al, MVM is applied in the neighborhood of the
critical noise to the Zaklan model. Here we show that the Zaklan model
is robust because this can be studied besides using equilibrium dynamics of
Ising model also through the nonequilibrium MVM and on various topologies
giving the same behavior regardless of dynamic or topology used here.Comment: 11 pages, 6 figures. arXiv admin note: substantial text overlap with
arXiv:1204.0386 and arXiv:0910.196
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