2,148 research outputs found
Experimental and theoretical evidences for the ice regime in planar artificial spin ices
In this work, we explore a kind of geometrical effect in the thermodynamics
of artificial spin ices (ASI). In general, such artificial materials are
athermal. Here, We demonstrate that geometrically driven dynamics in ASI can
open up the panorama of exploring distinct ground states and thermally magnetic
monopole excitations. It is shown that a particular ASI lattice will provide a
richer thermodynamics with nanomagnet spins experiencing less restriction to
flip precisely in a kind of rhombic lattice. This can be observed by analysis
of only three types of rectangular artificial spin ices (RASI). Denoting the
horizontal and vertical lattice spacings by a and b, respectively, then, a RASI
material can be described by its aspect ratio =a/b. The rhombic lattice
emerges when =. So, by comparing the impact of thermal
effects on the spin flips in these three appropriate different RASI arrays, it
is possible to find a system very close to the ice regime
Caracterização de sintomas de deficiĂȘncias de micronutrientes em plantas de açaizeiros (Euterpe oleracea Mart.).
Genotype-environment interaction and phenotypic stability for girth growth and rubber yield of Hevea clones in SĂŁo Paulo State, Brazil
Star-forming dwarf galaxies in the Virgo cluster: the link between molecular gas, atomic gas, and dust
We present CO(1-0) and CO(2-1) observations of a sample of 20
star-forming dwarfs selected from the Herschel Virgo Cluster Survey, with
oxygen abundances ranging from 12 + log(O/H) ~ 8.1 to 8.8. CO emission is
observed in ten galaxies and marginally detected in another one. CO fluxes
correlate with the FIR 250 m emission, and the dwarfs follow the same
linear relation that holds for more massive spiral galaxies extended to a wider
dynamical range. We compare different methods to estimate H2 molecular masses,
namely a metallicity-dependent CO-to-H2 conversion factor and one dependent on
H-band luminosity. The molecular-to-stellar mass ratio remains nearly constant
at stellar masses <~ 10 M, contrary to the atomic hydrogen
fraction, M/M, which increases inversely with M. The flattening
of the M/M ratio at low stellar masses does not seem to be related
to the effects of the cluster environment because it occurs for both
HI-deficient and HI-normal dwarfs. The molecular-to-atomic ratio is more
tightly correlated with stellar surface density than metallicity, confirming
that the interstellar gas pressure plays a key role in determining the balance
between the two gaseous components of the interstellar medium. Virgo dwarfs
follow the same linear trend between molecular gas mass and star formation rate
as more massive spirals, but gas depletion timescales, , are not
constant and range between 100 Myr and 6 Gyr. The interaction with the Virgo
cluster environment is removing the atomic gas and dust components of the
dwarfs, but the molecular gas appears to be less affected at the current stage
of evolution within the cluster. However, the correlation between HI deficiency
and the molecular gas depletion time suggests that the lack of gas
replenishment from the outer regions of the disc is lowering the star formation
activity.Comment: 19 pages, 11 figures, accepted for publication in Astronomy &
Astrophysic
Interactions between Plasmopara viticola infection and stilbene synthesis in leaves and berries of ten 'Cabernet Sauvignon' clones
Combining the knowledge that Plasmopara viticola causes considerable damages to Vitis vinifera L. worldwide production and that stilbenes have a regulatory influence on Plasmopara viticola - grapevine interaction, this study compares infection time course and stilbenes production in leaves and berries of ten different clones of 'Cabernet Sauvignon'. Following increasing infection rates, different stilbenes were produced and accumulated in leaves and berries of the same clone. Higher absolute values were found in leaves, where trans-resveratrol reaches up to 8 Όg g-1 fw and Δ-viniferin up to 30 Όg g-1 fw while in berries, the values accumulated only up to a maximum of 3 Όg g-1 fw of trans-piceid and 1,5 Όg g-1 fw Δ-viniferin
Double diffractive meson production and the BFKL Pomeron at colliders
In this Letter we study the double diffractive vector meson production in
collisions assuming the dominance of the BFKL pomeron exchange. We
consider the non-forward solution of the BFKL equation at high energy and large
momentum transfer and estimate the total cross section for the process with antitagged and , where and can
be any two vector mesons (). The
event rates for the future linear colliders are given.Comment: 8 pages, 1 figure, Version to be published in Physical Review
Johnsongrass mosaic virus infecting sorghum in Brazil.
Sorghum bicolor (L.) Moench is cultivated in several tropical and subtropical regions in the world. Among the diseases, the mosaic caused by potyvirus is an important constraint for the agricultural production causing reduction in grain and forage sorghum production. In Brazil, only Sugarcane mosaic virus (SCMV) had previously been reported as the potyvirus species causing mosaic in sorghum and maize. A survey was carried out in sorghum plantations of the State of Minas Gerais, Brazil, during the 2014/2015 crop season for monitoring mosaic disease. Samples of sorghum plants expressing virus disease symptoms were collected for molecular analyzes. Molecular characterization of coat protein (CP) of the potyviruses naturally infecting sorghum, allowed us to identify the Johnsongrass mosaic virus (JGMV) as a new causal agent of mosaic disease in sorghum in Brazil. The sequences of the Brazilian JGMV sorghum-infecting (JGMV-Sr) isolates were deposited in the GenBank under the accession numbers KY952241, KY952242, and KY952243. Comparisons of the CP gene sequences of these Brazilian JGMV-Sr isolates revealed high nucleotide (nt) and amino acid (aa) sequence identities, ranging from 97.93 to 98.23%, and 99.12 to 99.20%, respectively, with the U07218.1 (JGMV-MDKS1) isolate. The Brazilian JGMV-Sr isolates were distinct from the Brazilian forage grasses-infecting (JGMV-Fg) isolates (KT833782 and KT289893). Transmission evaluations showed susceptibility of the teosinte, Sorghum verticilliflorum and Sorghum bicolor (L.) Moench, except line QL3.Maize and sugarcane genotypes were not infected by the Brazilian JGMV-Sr isolate. However, it is important to test more genotypes. This is the first report showing the identification and molecular characterization of the JGMV species naturally infecting sorghum at field conditions, expanding the knowledge about the dynamic and range of the mosaic causal agent for this crop in Brazil
High dillution of Staphysagria and fruit fly biotherapic preparations to manage South American fruit fly, Anastrepha fraterculus, in organic peach orchards.
The peach, Prunus persica, is an important economic crop in southern Brazil, where family farms are predominantly small. The South American fruit fly, Anastrepha fraterculus is a limiting factor to increased production in orchard crops. Increased organic production in Brazil has stimulated research to find ecological based pest management. This research was carried out in order to evaluate the efficacy of preparations at high dilution in managing A. fraterculus in organic peach orchards. Experiments were conducted under field conditions in randomized blocks during 2003/04 and 2004/05. Treatments consisted of A. fraterculus nosodes and Staphysagria homeopathic preparations, both at two high dilution levels, 3CH and 6CH (centesimal hahnemannian dilution method), applied at two spray intervals, 5 and 10 days, and a control. Fruit losses due to A. fraterculus infestation varied from 40 to 98.3%. Although there were significant differences among treatments in the first harvest of two of the three experiments there were no significant differences in the second harvest of any of the experiments. None of the homeopathic preparations reduced the incidence of infested fruit significantly below that of the water control in any of the three experiments. Further studies must combine other strategies such as bagging fruits and planting of early season cultivars. Variation on high dilution potency, dose, and frequency of application must also be considered
Variabilidade entre linhagens de feijoeiro na eficiĂȘncia de utilização de nitrogĂȘnio.
Foi realizado o presente trabalho com o objetivo de identificar linhagens de feijoeiro eficientes na utilização de nitrogĂȘnio
Grafting height does not affect Fusarium wilt control or horticultural performance of Passiflora gibertii N.E.Br. rootstock.
The influence of the grafting height (5, 10, 20 and 30 cm above the root collar) of P. edulis on P. gibertii was evaluated on the incidence of Fusarium wilt and horticultural performance. Plants of P. gibertii grafted on P. edulis and non-grafted plants of both species were also studied. In addition, histopathological studies were also performed on the roots of non-grafted P. edulis collected at three severity stages of Fusarium wilt. In greenhouse, the graft take was inversely related to the grafting height in general. In the field conditions, the plant growth of P. gibertii grafted on P. edulis was superior to its reciprocal grafting, even though the former combination was susceptible to Fop. Plants of P. edulis grafted on P. gibertii at all grafting heights did not present symptoms of Fop, and the number of fruit yield and quality were equivalent, but plant growth was decreased in relation to the non-grafted plants. Starch depletion in the root system of P. edulis was directly related to the severity of the Fusarium wilt. P. gibertii was confirmed as a Fusarium wilt resistant rootstock of P. edulis, with minimal influence of the grafting height for the control of the disease
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