Dynamics of Gravitating Magnetic Monopoles

According to previous work on magnetic monopoles, static regular solutions are nonexistent if the vacuum expectation value of the Higgs field $\eta$ is larger than a critical value $\eta_{{\rm cr}}$, which is of the order of the Planck mass. In order to understand the properties of monopoles for $\eta>\eta_{{\rm cr}}$, we investigate their dynamics numerically. If $\eta$ is large enough ($\gg\eta_{{\rm cr}}$), a monopole expands exponentially and a wormhole structure appears around it, regardless of coupling constants and initial configuration. If $\eta$ is around $\eta_{{\rm cr}}$, there are three types of solutions, depending on coupling constants and initial configuration: a monopole either expands as stated above, collapses into a black hole, or comes to take a stable configuration.Comment: 11 pages, revtex, postscript figures; results for various initial conditions are added; to appear in Phys. Rev.

Critical structure factor in Ising systems

We perform a large-scale Monte Carlo simulation of the three-dimensional Ising model on simple cubic lattices of size L^3 with L=128 and 256. We determine the corresponding structure factor (Fourier transform of the two-point function) and compare it with several approximations and with experimental results. We also compute the turbidity as a function of the momentum of the incoming radiation, focusing in particular on the deviations from the Ornstein-Zernicke expression of Puglielli and Ford.Comment: 16 page

Efeito da utilização de acaricidas em citros, sobre a população de Brevipalpus phoenicis (Geijskes, 1939) e ácaros predadores (Phytoseiidae)

The experiment was carried out in order to study the effects of some acaricides on Brevipalpus phoenicis (Geijskes,1939) (Acari,Tenuipalpidae) and predatory mites (Phytoseiidae) hi citrus. The products tested and dosages in g AI/ 100 / of water were: fenpyroximate (5.0), acrinathrin (0.5), hexythiazox (1.5), amitraz (40.0) and sulphur (225.0). The acaricides fenpyroximate, acrinathrin and hexythiazox were efficient against B. phoenicis up to 127 days from the application date, whereas sulphur and amitraz presented good control up to 92 days and 58 days after treatment, respectively. Hexythiazox was fairly innocuous to predatory mites but, the remaining acaricides caused significant mortality to these mites. The pesticides sulphur, fenpyroximate and acrinathrin induced reductions of the population of phytoseid mites up to 58 days, but amitraz showed reductions up to 92 days after application.Foi conduzido experimento com o objetivo de estudar o efeito de alguns acaricidas sobre Brevipalpus phoenicis (Geijskes,1939) (AcarirTenuipalpidae) e ácaros predadores (Phytoseiidae), em citros. Os produtos testados e as dosagens em g i.a./100 / de água foram: fenpyroximate (5,0), acrinathrin (0,5); hexythiazox (1,5); amitraz (40,0) e enxofre (225,0). Os acaricidas fenpyroximate, acrinathrin e hexythiazox foram eficientes contra B. phoenicis até 127 dias após a aplicação, enquanto que, o enxofre e o amitraz apresentaram bom controle até 92 e 58 dias após o tratamento, respectivamente. O hexythiazox foi praticamente inócuo aos ácaros predadores mas os demais acaricidas foram significativamente prejudiciais a estes ácaros. Os produtos enxofre, fenpyroximate e acrinathrin induziram reduções na população de fitoseíídeos até 58 dias, porém o amitraz apresentou reduções até 92 dias após a pulverização

Efeito da utilização de acaricidas em citros, sobre a população de Brevipalpus phoenicis (Geijskes, 1939) e ácaros predadores (Phytoseiidae)

The experiment was carried out in order to study the effects of some acaricides on Brevipalpus phoenicis (Geijskes,1939) (Acari,Tenuipalpidae) and predatory mites (Phytoseiidae) hi citrus. The products tested and dosages in g AI/ 100 / of water were: fenpyroximate (5.0), acrinathrin (0.5), hexythiazox (1.5), amitraz (40.0) and sulphur (225.0). The acaricides fenpyroximate, acrinathrin and hexythiazox were efficient against B. phoenicis up to 127 days from the application date, whereas sulphur and amitraz presented good control up to 92 days and 58 days after treatment, respectively. Hexythiazox was fairly innocuous to predatory mites but, the remaining acaricides caused significant mortality to these mites. The pesticides sulphur, fenpyroximate and acrinathrin induced reductions of the population of phytoseid mites up to 58 days, but amitraz showed reductions up to 92 days after application.Foi conduzido experimento com o objetivo de estudar o efeito de alguns acaricidas sobre Brevipalpus phoenicis (Geijskes,1939) (AcarirTenuipalpidae) e ácaros predadores (Phytoseiidae), em citros. Os produtos testados e as dosagens em g i.a./100 / de água foram: fenpyroximate (5,0), acrinathrin (0,5); hexythiazox (1,5); amitraz (40,0) e enxofre (225,0). Os acaricidas fenpyroximate, acrinathrin e hexythiazox foram eficientes contra B. phoenicis até 127 dias após a aplicação, enquanto que, o enxofre e o amitraz apresentaram bom controle até 92 e 58 dias após o tratamento, respectivamente. O hexythiazox foi praticamente inócuo aos ácaros predadores mas os demais acaricidas foram significativamente prejudiciais a estes ácaros. Os produtos enxofre, fenpyroximate e acrinathrin induziram reduções na população de fitoseíídeos até 58 dias, porém o amitraz apresentou reduções até 92 dias após a pulverização

Electronic theory for the normal state spin dynamics in Sr2_2RuO4_4: anisotropy due to spin-orbit coupling

Using a three-band Hubbard Hamiltonian we calculate within the random-phase-approximation the spin susceptibility, $\chi({\bf q},\omega)$, and NMR spin-lattice relaxation rate, 1/T$_1$, in the normal state of the triplet superconductor Sr$_2$RuO$_4$ and obtain quantitative agreement with experimental data. Most importantly, we find that due to spin-orbit coupling the out-of-plane component of the spin susceptibility $\chi^{zz}$ becomes at low temperatures two times larger than the in-plane one. As a consequence strong incommensurate antiferromagnetic fluctuations of the quasi-one-dimensional $xz$- and $yz$-bands point into the $z$-direction. Our results provide further evidence for the importance of spin fluctuations for triplet superconductivity in Sr$_2$RuO$_4$.Comment: revised versio

Quadrupolar effect and rattling motion in heavy fermion superconductor PrOs_4Sb_{12}

The elastic properties of a filled skutterudite PrOs_4Sb_{12} with a heavy Fermion superconductivity at T_C=1.85 K have been investigated. The elastic softening of (C_{11}-C_{12})/2 and C_{44} with lowering temperature down to T_C indicates that the quadrupolar fluctuation due to the CEF state plays a role for the Cooper paring in superconducting phase of PrOs_4Sb_{12}. A Debye-type dispersion in the elastic constants around 30 K revealed a thermally activated Gamma_{23} rattling due to the off-center Pr-atom motion obeying tau=tau_{0}exp(E/k_{B}T) with an attempt time tau_0=8.8*10^{-11} sec and an activation energy E=168 K. It is remarkable that the charge fluctuation of the off-center motion with Gamma_{23} symmetry may mix with the quadrupolar fluctuation and enhance the elastic softening of (C_{11}-C_{12})/2 just above T_C.Comment: 5 pages, 4 figures, to be published to Phys. Rev.

Tau Flavour Violation in Sparticle Decays at the LHC

We consider sparticle decays that violate tau lepton number, motivated by neutrino oscillation data. We work in the context of the constrained minimal supersymmetric extension of the Standard Model (CMSSM), in which the different sleptons have identical masses at the GUT scale, and neutrino Dirac Yukawa couplings mix them. We find that the branching ratio for decay of the heavier neutralino chi_2 to chi + tau mu is enhanced when the LSP mass m_chi = m_stau_1, including the region of CMSSM parameter space where coannihilation keeps the relic chi density within the range preferred by cosmology. Thus chi_2 to chi + tau mu decay may provide a physics opportunity for observing the violation of tau lepton number at the LHC that is complementary to tau to mu + gamma decay. Likewise, chi_2 to chi + e mu decay is also enhanced in the coannihilation region, providing a complement to mu to e + gamma decay.Comment: 11 pages, 3 figure

Superprocesses as models for information dissemination in the Future Internet

Future Internet will be composed by a tremendous number of potentially interconnected people and devices, offering a variety of services, applications and communication opportunities. In particular, short-range wireless communications, which are available on almost all portable devices, will enable the formation of the largest cloud of interconnected, smart computing devices mankind has ever dreamed about: the Proximate Internet. In this paper, we consider superprocesses, more specifically super Brownian motion, as a suitable mathematical model to analyse a basic problem of information dissemination arising in the context of Proximate Internet. The proposed model provides a promising analytical framework to both study theoretical properties related to the information dissemination process and to devise efficient and reliable simulation schemes for very large systems

Toxicity of synthetic and natural compounds on Tetranychus urticae and the predator Phytoseiulus macropilis

The objective of this work was to evaluate the toxicity of synthetic and natural compounds on Tetranychus urticae and the predator Phytoseiulus macropilis. Mortality and growth rates of T. urticae and its predator were evaluated after applications of: abamectin, clofentezine, fenpropathrin, fenpyroximate, propargite, sulfur and spiromesifen, at their recommended concentrations; neem oils (Natuneem and Sempre Verde Killer Neem at 1%); and aqueous extracts at 10% of Dieffenbachia brasiliensis, Annona squamosa, Ruta graveolens, Agave angustifolia, Melia azedarach, Sonchus oleraceus, Mentha spicata x M. suaveolens, Allium cepa, Laurus nobilis, and Eucalyptus saligna. The acute toxicity and the influence of the compounds on the instantaneous growth rate of the mites were carried out in laboratory. Extracts of A. cepa, A. angustifolia, neem oil-based products, spiromesifen, propargite, fenpyroximate, abamectin and fenpropathrin caused mortality higher than 83% on T. urticae. Extract of A. angustifolia, Natuneem and clofentezine did not cause significant mortality rates on P. macropilis. Agave angustifolia and Natuneem did not affect significantly the growth rate of this predator. Propargite, fenpyroximate, abamectin, fenpropathrin, spiromesifen and extract of L. nobilis severely affected P. macropilis population