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 $H^-\to \tau\bar{\nu_\tau}$ and $H^-\to b\bar{t}$. We find that the corrections to the $H^-\to \tau\bar{\nu_\tau}$ decay mode are generally about 0.1%, and can be negligible. But the corrections to the $H^-\to b\bar{t}$ 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 τ−→μ−P1P2\tau^-\to \mu^- P_1 P_2 in the topcolor-assisted technicolor model and the littlest Higgs model with TT parity

The new particles predicted by the topcolor-assisted technicolor ($TC2$) model and the littlest Higgs model with T-parity (called $LHT$ model) can induce the lepton flavor violation ($LFV$) couplings at tree level or one loop level, which might generate large contributions to some $LFV$ processes. Taking into account the constraints of the experimental data on the relevant free parameters, we calculate the branching ratios of the $LFV$ decay processes $\tau^-\to\mu^- P_1 P_2$ with $P_1 P_2$ = $\pi^+\pi^-$, $K^+K^-$ and $K^0\bar{K^0}$ in the context of these two kinds of new physics models. We find that the $TC2$ model and the $LHT$ model can indeed produce significant contributions to some of these $LFV$ decay processes.Comment: 24 pages, 7 figure

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.