358 research outputs found
Magnetic relaxation phenomena and cluster glass properties of La{0.7-x}Y{x}Ca{0.3}MnO{3} manganites
The dynamic magnetic properties of the distorted perovskite system
La{0.7-x}Y{x}Ca{0.3}MnO{3} (0 <= x <= 0.15) have been investigated by
ac-susceptibility and dc magnetization measurements, with emphasis on
relaxation and aging studies. They evidence for x >= 0.10 the appearance of a
metallic cluster glass phase, that develops just below the ferromagnetic
transition temperature. The clusters grow with decreasing temperature down to a
temperature T(f0) at which they freeze due to severe intercluster frustration.
The formation of these clusters is explained by the presence of yttrium induced
local structural distortions that create localized spin disorder in a magnetic
lattice where double-exchange ferromagnetism is dominant.Comment: Accepted for publication in Phys. Rev.
Effects of R-parity Violation on the Charged Higgs Boson Decays
We calculate one-loop R-parity-violating couplings corrections to the
processes and . We find that the
corrections to the decay mode are generally about
0.1%, and can be negligible. But the corrections to the decay
mode can reach a few percent for the favored parameters.Comment: 17 pages,6 figures. One type error in the title correcte
AVALIAÇÃO DOS EFEITOS DE DIFERENTES CONCENTRAÇÕES DE CLORO NA DESCAPSULAÇÃO E ECLOSÃO DE LARVAS DE ARTEMIA (Artemia sp.)
This paper was prepared in the Aquaculture Laboratory of the Federal University of the State of Parana, Brazil, with the purpose of determining the best sodium hypochloride (NaClO with 6% active ingredient) dosage to be employed in the artemia oocysts hatching process.The artemia oocysts were hydrated for 1 hour, filtered and submitted to a 10-minute chlorine treatment. The chlorine dosages tested were the following (NaClO - 6% sodium hypochloride): 0.38g, 0.75g, 1.50g, 3.00g and 6.00g of active ingredient per liter of water. Soon after chlorine application the oocysts were rinsed to eliminate the chlorine and immediately the oocysts were put into transparent plastic vials with water in the constant aeration and luminosity, where they remained for 53 hours. For the nauplii count one mililiter of the vial was put into a test tube with an interconnected aeration. Three counts were made for all repetitions and the threshold analysed was the number of hatched larvae per mililiter of hatching solution. The results were submitted to a normality test and it was determined that the hatching results did not show a normal pattern, therefore, it was not possible to use those averages as a comparison basis between treatments. Subsequently non-parametric tests were performed using the overall average as a comparison basis between treatments.Techically one can see the superiority of treatment with 1.50g of active chlorine, which resulted in the highest hatching-out counts, with 50% of the observed data presented 140 larvae hatched per milimiter.O presente trabalho foi realizado no Laboratório de Aqüicultura da Universidade Federal do Paraná (UFPR), com o objetivo de determinar a melhor dose de hipoclorito de sódio (NaClO com 6% de ingrediente ativo) a ser empregada na descapsulação de oocistos de artemia. Os oocistos de artemia foram hidratados durante 1 hora, filtrados e submetidos aos tratamentos com cloro durante 10 minutos. As dosagens de cloro testadas foram as seguintes (NaClO - hipoclorito de sódio 6%): 0,38g, 0,75g, 1,50g, 3,00g e 6,00g de ingrediente ativo por litro de água. Depois da aplicação do cloro fez-se a lavagem dos oocistos para eliminar o cloro aplicado e logo após os oocistos foram colocados na água em frascos plásticos transparentes com aeração e luminosidade constante onde ficaram durante 53 horas. Para contagem dos náuplios foi pipetado um mililitro do frasco com aeração ligada. Para todas as repetições foram feitas três contagens e o parâmetro analisado foi o número de larvas eclodidas por mililitro da solução de eclosão. Os resultados foram submetidos a um teste de normalidade e foi verificado que os resultados de eclosão não tinham distribuição normal, portanto as médias não puderam ser usadas como termo de comparação entre os tratamentos. Então foram realizados testes não-paramétricos que usam a mediana como parâmetro de comparação entre os tratamentos. Tecnicamente observa-se a superioridade do tratamento de 1,50g de cloro ativo que apresentou o ponto máximo de eclosão, tendo 50% dos dados de eclosão ao redor de 140 larvas eclodidas por mililitro
Epidemiologic situation of bovine brucellosis in the State of Mato Grosso, Brazil
Caracterizou-se a brucelose bovina em Mato Grosso por meio de um estudo transversal realizado em 2003 para auxiliar na implementação do Programa Nacional de Controle e Erradicação da Brucelose e Tuberculose. No Estado, estratificado em quatro circuitos pecuários, foram amostrados 13.684 animais, provenientes de 1.152 rebanhos. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e os soros reagentes foram testados pelo 2-mercaptoetanol (ME) e concomitantemente retestados pelo teste de Rosa Bengala para resultado conclusivo. As prevalências de focos e de animais infectados foram: 41,2% [38,0-44,4%] e 10,2% [7,4-13,1%], respectivamente. Nos circuitos produtivos, as prevalências de focos foram 36,9% [29,2-45,2%], 27,2% [22,8-32,1%], 40,4% [38,8-46,2%] e 50,3% [44,5-56,1%]; e as prevalências de animais 7,9% [3,0-12,9%], 4,1% [2,8-5,4%], 8,1% [5,2-11,1%] e 15,3% [9,2-21,3%], respectivamente, para os circuitos 1, 2, 3 e 4. Os fatores de risco (odds ratio, OR) associados à condição de foco no Estado foram: exploração de gado de corte (OR= 1,8 [1,2-2,5]), exploração mista (OR=1,8 [1,2-2,7]), número de fêmeas no rebanho de 11 a 50 (OR=4,8 [1,1-20,8]), número de fêmeas no rebanho acima de 51 (OR=6,8 [1,6-29,0]), ocorrência de aborto (OR=1,7 [1,3-2,2]). A brucelose está homogeneamente distribuída no Estado, o que permite uniformidade de medidas sanitárias. Adicionalmente, sugere-se a intensificação da vacinação de fêmeas para todo o Estado. _______________________________________________________________________________________________________ ABSTRACTA study to characterize bovine brucellosis in the State of Mato Grosso was carried out in 2003 in order to support the implementation of the National Program for the Control and Eradication of Bovine Brucellosis. The State was divided into four productive regions, and 13,684 bovines from 1,152 herds were sampled. The serum samples were screened for antibodies to Brucella spp. by the Rose-Bengal test (RBT) and all RBT-positive sera were re-tested by the 2-mercaptoethanol test (2-ME), and again by RBT for confirmation. The prevalence of infected herds and animals in the State of Mato Grosso were 41.2% [38.0-44.4%] and 10.2% [7.4-13.1%], respectively. In the productive regions, the prevalence of infected herds were 36.9% [29.2-45.2%], 27.2% [22.8-32.1%], 40.4% [38.8-46.2%], and 50.3% [44.5-56.1%], respectively; and the prevalence of infected animals were 7.9% [3.0-12.9%], 4.1% [2.8-5.4%], 8.1% [5.2-11.1%], and 15.3% [9.2-21.3%], respectively, for regions 1, 2, 3, and 4. The risk factors (odds ratio, OR) associated with the presence of the infection in the State were: beef cattle farming (OR=1.8 [1.2-2.5]), mixed (beef and dairy) cattle farming (OR=1.8 [1.2-2.7]), farms with 11 to 50 females (OR=4.8 [1.1-20.8]), farms with more than 51 females (OR=6.8 [1.6-29.0]), and occurrence of abortion (OR=1.7 [1.3-2.2]). Given that brucellosis is homogeneously distributed in the State, uniform sanitary measures might be adopted. As a homogeneous additional measure for the State, the intensification of female vaccination is suggested
Supersymmetric Regularization, Two-Loop QCD Amplitudes and Coupling Shifts
We present a definition of the four-dimensional helicity (FDH) regularization
scheme valid for two or more loops. This scheme was previously defined and
utilized at one loop. It amounts to a variation on the standard 't
Hooft-Veltman scheme and is designed to be compatible with the use of helicity
states for "observed" particles. It is similar to dimensional reduction in that
it maintains an equal number of bosonic and fermionic states, as required for
preserving supersymmetry. Supersymmetry Ward identities relate different
helicity amplitudes in supersymmetric theories. As a check that the FDH scheme
preserves supersymmetry, at least through two loops, we explicitly verify a
number of these identities for gluon-gluon scattering (gg to gg) in
supersymmetric QCD. These results also cross-check recent non-trivial two-loop
calculations in ordinary QCD. Finally, we compute the two-loop shift between
the FDH coupling and the standard MS-bar coupling, alpha_s. The FDH shift is
identical to the one for dimensional reduction. The two-loop coupling shifts
are then used to obtain the three-loop QCD beta function in the FDH and
dimensional reduction schemes.Comment: 44 pages, minor corrections and clarifications include
Lepton flavor violation decays in the topcolor-assisted technicolor model and the littlest Higgs model with parity
The new particles predicted by the topcolor-assisted technicolor ()
model and the littlest Higgs model with T-parity (called model) can
induce the lepton flavor violation () couplings at tree level or one loop
level, which might generate large contributions to some processes. Taking
into account the constraints of the experimental data on the relevant free
parameters, we calculate the branching ratios of the decay processes
with = , and
in the context of these two kinds of new physics models. We find
that the model and the model can indeed produce significant
contributions to some of these decay processes.Comment: 24 pages, 7 figure
Fusarium wilt incidence and common bean yield according to the preceding crop and the soil tillage system
The objective of this work was to evaluate the effects of preceding crops and tillage systems on the incidence of Fusarium wilt (Fusarium oxysporum f. sp. phaseoli) and common bean (Phaseolus vulgaris) yield. The cultivar BRS Valente was cultivated under center‑pivot irrigation in the winter seasons of 2003, 2004 and 2005, after several preceding crops established in the summer seasons. Preceding crops included the legumes Cajanus cajan (pigeon pea), Stylosanthes guianensis, and Crotalaria spectabilis; the grasses Pennisetum glaucum (millet), Sorghum bicolor (forage sorghum), Panicum maximum, and Urochloa brizantha; and a consortium of maize (Zea mays) and U. brizantha (Santa Fé system). Experiments followed a strip‑plot design, with four replicates. Fusarium wilt incidence was higher in the no‑tillage system. Higher disease incidences corresponded to lower bean yields in 2003 and 2004. Previous summer cropping with U. brizantha, U. brizantha + maize consortium, and millet showed the lowest disease incidence. Therefore, the choice of preceding crops must be taken into account for managing Fusarium wilt on irrigated common bean crops in the Brazilian Cerrado
Thermodynamics of phantom energy in the presence of a Reissner-Nordstrom black hole
In this paper, we study the validity of the generalized second law (GSL) in
phantom dominated universe in the presence of a Reissner-Nordstr\"{o}m (RN)
black hole. Our study is independent of the origin of the phantom like behavior
of the considered universe. We also discuss the GSL in the neighborhood of
transition from quintessence to phantom regime. We show that for a constant
equation of state parameter, the GSL may be satisfied provided that the
temperature is proportional to de Sitter temperature. It is shown that in
models with (only) a transition from quintessence to phantom regime the
generalized second law does not hold in the transition epoch. Next we show that
if the phantom energy has a chemical potential, then the GSL will hold if the
mass of black hole is above from a critical value.Comment: 5 pages, Accepted for publication in Astrophysics & Space Scienc
Gravitational Wave Emission from Galactic Radio Pulsars
We consider in this work continuous gravitational wave (GW) emission from
non-axisymmetric radio pulsars. We treat in some detail the observational
issues related to the known radio pulsar sample with the aim of unveiling the
actual number of sources contributing to GW, which are likely to be the main
contributors of GWs. It is shown that the operation of spheroidal GW detectors
and full-size interferometers could detect this component of the radiation or
impose useful limits on the effective oblateness of young radio pulsars.Comment: 7 pages, RevTex , no figures , to appear in Phys. Rev.
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