3,615 research outputs found
Estudo da diversidade de begomovirus em tomateiro cultivado na região da caatinga do Brasil.
O presente trabalho teve como objetivo analisar a diversidade de begomovirus infectando tomateiro no Nordeste brasileiro.Resumo 673-
Magnetic response and quantum critical behavior in the doped two-leg extended Hubbard ladder
We have investigated quantum critical behavior in the doped two-leg extended
Hubbard ladder, by using a weak-coupling bosonization method. In the ground
state, the dominant fluctuation changes from the conventional d-wave-like
superconducting (SCd) state into density-wave states, with increasing
nearest-neighbor repulsions and/or decreasing doping rate. The competition
between the SCd state and the charge-density-wave state coexisting with the
p-density-wave state becomes noticeable on the critical point, at which the gap
for magnetic excitations vanishes. Based on the Majorana-fermion description of
the effective theory, we calculate the temperature dependence of the magnetic
response such as the spin susceptibility and the NMR relaxation rate, which
exhibit unusual properties due to two kinds of spin excitation modes. On the
quantum critical point, the spin susceptibility shows paramagnetic behavior
with logarithmic corrections and the NMR relaxation rate also exhibits
anomalous power-law behavior. We discuss the commensurability effect due to the
umklapp scattering and relevance to the two-leg ladder compounds
Sr_{14-x}Ca_xCu_{24}O_{41}.Comment: 18 pages, 9 figures, accepted for publication in Phys. Rev.
Some closure operations in Zariski-Riemann spaces of valuation domains: a survey
In this survey we present several results concerning various topologies that
were introduced in recent years on spaces of valuation domains
Hydrodynamic response of rotationally supported flows in the Small Shearing Box model
The hydrodynamic response of the inviscid small shearing box model of a
midplane section of a rotationally supported astrophysical disk is examined. An
energy functional is formulated for the general nonlinear problem.
It is found that the fate of disturbances is related to the conservation of
this quantity which, in turn, depends on the boundary conditions utilized:
is conserved for channel boundary conditions while it is not
conserved in general for shearing box conditions. Linearized disturbances
subject to channel boundary conditions have normal-modes described by Bessel
Functions and are qualitatively governed by a quantity which is a
measure of the ratio between the azimuthal and vertical wavelengths. Inertial
oscillations ensue if - otherwise disturbances must in general be
treated as an initial value problem. We reflect upon these results and offer a
speculation.Comment: 6 pages, resubmitted to Astronomy and Astrophysics, shortened with
references adde
Characterization of bean necrotic mosaic virus: a member of a novel evolutionary lineage within the genus Tospovirus.
Tospoviruses (Genus Tospovirus, Family Bunyaviridae) are phytopathogens responsible for significant worldwide crop losses. They have a tripartite negative and ambisense RNA genome segments, termed S (Small), M (Medium) and L (Large) RNA. The vector-transmission is mediated by thrips in a circulative-propagative manner. For new tospovirus species acceptance, several analyses are needed, e.g., the determination of the viral protein sequences for enlightenment of their evolutionary history
Charge-Density-Wave Formation in the Doped Two-Leg Extended Hubbard Ladder
We investigate electronic properties of the doped two-leg Hubbard ladder with
both the onsite and the nearest-neighbor Coulomb repulsions, by using the the
weak-coupling renormalization-group method. It is shown that, for strong
nearest-neighbor repulsions, the charge-density-wave state coexisting with the
p-density-wave state becomes dominant fluctuation where spins form intrachain
singlets. By increasing doping rate, we have also shown that the effects of the
nearest-neighbor repulsions are reduced and the system exhibits a quantum phase
transition into the d-wave-like (or rung-singlet) superconducting state. We
derive the effective fermion theory which describes the critical properties of
the transition point with the gapless excitation of magnon. The phase diagram
of the two-leg ladder compound, Sr_{14-x}Ca_xCu_{24}O_{41}, is discussed.Comment: 4 pages, 2 figure
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