Exact Results for the Kuramoto Model with a Bimodal Frequency Distribution

We analyze a large system of globally coupled phase oscillators whose natural frequencies are bimodally distributed. The dynamics of this system has been the subject of long-standing interest. In 1984 Kuramoto proposed several conjectures about its behavior; ten years later, Crawford obtained the first analytical results by means of a local center manifold calculation. Nevertheless, many questions have remained open, especially about the possibility of global bifurcations. Here we derive the system's complete stability diagram for the special case where the bimodal distribution consists of two equally weighted Lorentzians. Using an ansatz recently discovered by Ott and Antonsen, we show that in this case the infinite-dimensional problem reduces exactly to a flow in four dimensions. Depending on the parameters and initial conditions, the long-term dynamics evolves to one of three states: incoherence, where all the oscillators are desynchronized; partial synchrony, where a macroscopic group of phase-locked oscillators coexists with a sea of desynchronized ones; and a standing wave state, where two counter-rotating groups of phase-locked oscillators emerge. Analytical results are presented for the bifurcation boundaries between these states. Similar results are also obtained for the case in which the bimodal distribution is given by the sum of two Gaussians.Comment: 28 pages, 7 figures; submitted to Phys. Rev. E Added comment

Effect of baculovirus spodoptera isolates in Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) larvae and their characterization by RAPD.

The total of 22 Baculovirus isolates surveyed in different corn producing regions in Brazil were used against fall armyworm, Spodoptera frugiperda (J.E. Smith). The viruses were purified and their suspensions were used to feed fall armyworm larvae from 4th and 5th instar. The mortality rate was checked daily and the infected larvae were frost after death, what generally occurred between the 5th and 7th day after virus ingestion. The 22 Baculovirus isolates were used in six concentrations (from 103 to 108 polyhedra/ml) and one check treatment with water. Mortality rate, larval period, pupal period, pupa weight and lethal concentration (LC50) were determined for all isolates. Significant differences were found among all isolates and different concentrations, also interaction between isolate x virus concentration for all characteristics evaluated, except for pupal period. Amplification patterns of 54 RAPD markers, being 41 polymorphic among the isolates, were used to evaluate the genetic distance and its correlation with the fall armyworm larvae mortality rate. The genetic diversity calculated by the Jaccard's coefficient using the molecular data allowed a division of the isolates into two groups, with a high level of confidence. These groups did not present any association with the mortality rate caused by the isolates or with their geographical distribution. However, a RAPD fragment OPW04.2280 was highly associated with the larvae mortality rate and with LC50, explaining 23 and 65% of the phenotypic variation for these traits among the isolates, respectively.

SIMULATION AND EXPERIMENTAL EVALUATION OF AN INNOVATIVE ROTARY COMPRESSOR WITH VARIABLE SPEED DISPLACERS

This paper describes preliminary studies of a new rotary compressor with variable speed displacers. Two displacers rotate concentrically, in an annular space, at variable and phased angular velocities, thus creating two variable-volume compression spaces between them. The displacers are individually driven by two concentric shafts. An innovative driving mechanism imposes phased variable angular speeds to the shafts and, consequently, to the displacers, thus providing a volume variation in the gas compression spaces. The driving mechanism also offers a convenient way of capacity control, from zero to 100%, at constant electric motor speed. A mathematical model simulating the performance was developed. A traditional simulation model for positive displacement compressors was employed, where mass and energy conservation equations, in differential form, were applied to the control volumes (two compression spaces). Uniformly distributed thermodynamic properties of gas, varying with time, were assumed for each control volume. Equations describing the volume variation with time, the gas to cylinder wall heat transfer and gas flow through valve ports and leakage passages were also employed. The resulting mathematical model was a system of ordinary differential equations, the numerical integration of which provides the time-history of pressure and temperature of the gas inside the compression chambers. A prototype was also constructed and tested. First performance results are presented, showing the compressor behaviour under different operational conditions

De Finetti theorem on the CAR algebra

The symmetric states on a quasi local C*-algebra on the infinite set of indices J are those invariant under the action of the group of the permutations moving only a finite, but arbitrary, number of elements of J. The celebrated De Finetti Theorem describes the structure of the symmetric states (i.e. exchangeable probability measures) in classical probability. In the present paper we extend De Finetti Theorem to the case of the CAR algebra, that is for physical systems describing Fermions. Namely, after showing that a symmetric state is automatically even under the natural action of the parity automorphism, we prove that the compact convex set of such states is a Choquet simplex, whose extremal (i.e. ergodic w.r.t. the action of the group of permutations previously described) are precisely the product states in the sense of Araki-Moriya. In order to do that, we also prove some ergodic properties naturally enjoyed by the symmetric states which have a self--containing interest.Comment: 23 pages, juornal reference: Communications in Mathematical Physics, to appea

Host defense responses restricts the growth of the fungus Colletotrichum lindemuthianum in cowpea, TE 97 411-1E resistant genotype.

Cowpea is the main subsistence crop in the semiarid North-east of Brazil. However, very few is known concerning to its defense mechanisms against fungi. The objective of this present work was to evaluate the infection strategies of the hemibiotrophic fungi Colletotrichum lindemuthianum and the associated cytological defense responses of two cowpea genotypes, TE 97-411-1E (resistant) and BR 3 Tracuateua (susceptible). The infection process of the fungi in both genotypes occurred preferentially through the leaf epidermal cells by penetration tubes emerged from appressoria. The resistant cowpea genotype, TE 97-411-1E, showed enhanced penetration resistance to C. lindemuthianum associated with higher epidermal H2O2 accumulation, papilla formation, and increase in phenylalanine ammonialyase activity, possibly related to accumulation of phenolic compounds and host cell wall lignification. Macroscopic examination of the primary leaves revealed the presence of shrunken necrotic lesions characteristic of anthracnose in infected BR 3 Tracuateua, whereas in TE 97-411-1E cell death was also observed but only in a reduced percentage of the infection sites. In summary the results obtained in the present study suggested that TE 97-411-1E genotype is more resistant to C. lindemuthianum compared to BR 3 Tracuateua, as it developed more effective defense responses against the establishment of the pathogen

Respostas de defesa da planta impedem o crescimento do fungo Colletotrichum gloeosporioides no genótipo de feijão-caupi BR 3 Tracuateua.

O feijão-caupi [Vigna unguiculata (L.) Walp.] é uma das culturas mais importantes no semiárido do Nordeste do Brasil. Embora tolerante às condições climáticas adversas, esta espécie é constantemente atacada por patógenos, ocasionando perdas na produção. Assim, o presente trabalho foi conduzido para avaliar que estratégias de infecção o patógeno Colletotrichum gloeosporioides utiliza para infectar e se desenvolver nos genótipos de feijão-caupi BR 3 Tracuateua e TE 97-411-1E e para verificar as respostas citológicas de defesa do feijão-caupi, como também o papel da fenilalanina amônia liase (PAL) no processo de infecção. Exame macroscópico mostrou um alto número de folhas primárias com lesões necróticas em TE 97-411-1E comparado com BR 3-Tracuateua. O processo de infecção foi iniciado indiretamente, via abertura dos estômatos, por tubos germinativos, sem formação de apressório. A atividade da PAL nas folhas de feijão-caupi aumentou em dois diferentes tempos após inoculação em ambos os genótipos. O primeiro pico pode estar associado a biossíntese inicial de compostos fenólicos e o segundo ao acúmulo posterior de compostos fenólicos e lignificação da parede celular do hospedeiro. O presente trabalho fornece evidências que a PAL tem um importante papel nas estratégias de defesa que o feijão-caupi emprega para se defender contra o fungo C. gloeosporioides. O crescimento do patógeno foi mais evidente no genótipo TE 97-411-1E, sugerindo que este é mais suscetível ao fungo do que BR 3-Tracuateua

A Search for "Dwarf" Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies

We have completed an optical spectroscopic survey of the nuclear regions (r < 200 pc) of a large sample of nearby galaxies. Although the main objectives of the survey are to search for low-luminosity active galactic nuclei and to quantify their luminosity function, the database can be used for a variety of other purposes. This paper presents measurements of the spectroscopic parameters for the 418 emission-line nuclei, along with a compilation of the global properties of all 486 galaxies in the survey. Stellar absorption generally poses a serious obstacle to obtaining accurate measurement of emission lines in nearby galactic nuclei. We describe a procedure for removing the starlight from the observed spectra in an efficient and objective manner. The main parameters of the emission lines (intensity ratios, fluxes, profile widths, equivalent widths) are measured and tabulated, as are several stellar absorption-line and continuum indices useful for studying the stellar population. Using standard nebular diagnostics, we determine the probable ionization mechanisms of the emission-line objects. The resulting spectral classifications provide extensive information on the demographics of emission-line nuclei in the local universe. This new catalog contains over 200 objects showing spectroscopic evidence for recent star formation and an equally large number of active galactic nuclei, including 46 which show broad H-alpha emission. These samples will serve as the basis of future studies of nuclear activity in nearby galaxies.Comment: To appear in the Astrophysical Journal Supplements. LaTex, 31 pages, plus an additional 23 figures and 5 tables. AASTex macro aaspp4.st

Asymptotic distribution of quasi-normal modes for Kerr-de Sitter black holes

We establish a Bohr-Sommerfeld type condition for quasi-normal modes of a slowly rotating Kerr-de Sitter black hole, providing their full asymptotic description in any strip of fixed width. In particular, we observe a Zeeman-like splitting of the high multiplicity modes at a=0 (Schwarzschild-de Sitter), once spherical symmetry is broken. The numerical results presented in Appendix B show that the asymptotics are in fact accurate at very low energies and agree with the numerical results established by other methods in the physics literature. We also prove that solutions of the wave equation can be asymptotically expanded in terms of quasi-normal modes; this confirms the validity of the interpretation of their real parts as frequencies of oscillations, and imaginary parts as decay rates of gravitational waves.Comment: 66 pages, 6 figures; journal version (to appear in Annales Henri Poincar\'e

Benzotiadiazol (BTH) induz atividades das enzimas peroxidase, b-1,3-Glucanase e formação de lignina em feijão-caupi.

O feijão-caupi se constitui numa importante fonte de proteínas, carboidratos e vitaminas sendo cultivado em vários países em desenvolvimento. Entretanto, herbívoros e fitopatógenos são responsáveis por grandes perdas nesta cultura. Para diminuir estes problemas, estratégias envolvendo o uso de elicitores químicos da resposta de defesa vegetal têm sido desenvolvidas. Dentre esses elicitores há aqueles que induzem resposta sistêmica adquirida (SAR) como o BTH [(1,2,3)-Benzothiadiazole-7-carbotioico S-metil ester]. Este trabalho teve como objetivo avaliar se o BTH é capaz de induzir a expressão de proteínas relacionadas à patogênese como peroxidase (POX), -1,3-glucanase (GLU), fenilalanina amônia-liase (PAL) e o aumento do conteúdo de lignina em folhas de feijão-caupi, cv. TE-97- 411. Dez dias após plantio, a parte aérea das plantas foi borrifada com diferentes concentrações de BTH. Para determinação das atividades enzimáticas, foram utilizadas folhas coletadas com 48 horas, e, para lignina, com 10 e 15 dias após tratamento. Aumento nas atividades destas enzimas, com exceção da PAL, e na deposição de lignina foi observado nas plantas tratadas. Estes resultados sugerem que o BTH representa uma estratégia potencial para ativação da defesa bioquímica do feijão-caupi