2,138 research outputs found
Tricritical behavior in epidemic dynamics with vaccination
We scrutinize the phenomenology arising from a minimal vaccination-epidemic
(MVE) dynamics using three methods: mean-field approach, Monte Carlo
simulations, and finite-size scaling analysis. The mean-field formulation
reveals that the MVE model exhibits either a continuous or a discontinuous
active-to-absorbing phase transition, accompanied by bistability and a
tricritical point. However, on square lattices, we detect no signs of
bistability, and we disclose that the active-to-absorbing state transition has
a scaling invariance and critical exponents compatible with the continuous
transition of the directed percolation universality class. Additionally, our
findings indicate that the tricritical and crossover behaviors of the MVE
dynamics belong to the universality class of mean-field tricritical directed
percolation.Comment: 12 pages, 6 figures and 2 tables. Version closer to the published
pape
Comparative study of the biological behaviour in hamster of two isolates of leishmania characterized respectively as L. major-like and L. donovani
Hamster inoculated intraperitoneally with 1 x 10(7) parasites of L. donovani and L. major-like of the New World were studied in groups of 15, 30, 60 and 90 days of infection. The parasite load and density showed progressive increase with the evolution of the infection and was higher in the L. donovani groups than in the L. major-like groups. The L. major-like groups showed parasite density higher in the spleen than in the liver and was similar in both organs in L. donovani groups. The histopathology showed a diffuse marked hyperplasia and hypertrophy of the reticuloendothelial system with high parasitism in the L. donovani groups while there was focal involvement of these organs in L. major-like groups, forming nodules of macrophages that were scantly parasitised. The biological behaviour could be useful in the preliminary studies of Leishmania strain in regional laboratories and understanding the histopathology of lesions caused by different leishmania species.Experimentos utilizando-se hamsters inoculados intraperitonealmente com 1 x 10(7) parasitas de 2 cepas, L. donovani (MHOM/BR/72/LD 46) e L. major-like (MCAN/BR/73/LD 70) isoladas no Novo Mundo foram realizados e estudados em grupos de 15, 30, 60 e 90 dias de infecção. A carga e a densidade parasitária mostraram progressivo aumento com a evolução da infecção e foi maior nos grupos inoculados com L. donovani do que nos grupos inoculados com L. major-like. Os grupos inoculados com L. major-like mostraram densidade parasitária maior no baço que no fÃgado e foram semelhantes em ambos os órgãos nos grupos inoculados com L. donovani. A histopatologia mostrou intensa e difusa hyperplasia e hipertrofia do sistema reticuloendotelial com alto parasitismo nos grupos inoculados com L. donovani, enquanto foi encontrado envolvimento focai nestes órgãos nos grupos inoculados com L. major-like, formando nódulos de macrófagos discretamente parasitados. O comportamento biológico seria útil em estudos preliminares de identificação de cepas de Leishmania em laboratórios regionais e na compreensão da histopatologia das lesões causadas por diferentes espécimes de leishmanias
Random networks with q-exponential degree distribution
We use the configuration model to generate networks having a degree
distribution that follows a -exponential,
, for arbitrary values of the
parameters and . We study the assortativity and the shortest path
of these networks finding that the more the distribution resembles a pure power
law, the less well connected are the corresponding nodes. In fact, the average
degree of a nearest neighbor grows monotonically with . Moreover,
our results show that -exponential networks are more robust against random
failures and against malicious attacks than standard scale-free networks.
Indeed, the critical fraction of removed nodes grows logarithmically with
for malicious attacks. An analysis of the -core
decomposition shows that -exponential networks have a highest -core,
that is bigger and has a larger than pure scale-free networks. Being at
the same time well connected and robust, networks with -exponential degree
distribution exhibit scale-free and small-world properties, making them a
particularly suitable model for application in several systems.Comment: 6 pages, 8 figure
Chest helical computed tomography scan shows pulmonary micronodules and condensation in acute schistosomiasis mansoni
Interpretation of Unresolved Mossbauer Spectra in Compounds of I~~~*
Recebido em 2 de Setembro de 1971 The Mossbauer-effect absorption spectra of the rare earth tri-iodides, Lal,, Gdl, and Erl, show evidence of unresolved quadrupole splitting. We propose that the electric field gradient (EFG) responsible for the interaction can be associated with a partially filled p hole (hd in the 5s25p6 eiectronic configuration of I-. The quadrupole coupling parameters and isomer shifts are determined from a least squares fitting of the data using as initial estimates the C[" NQR data for equivalent rare earth tri-chlorides. For Lal, , Gdl, and Erl, these ar
An unusual case report: treatment of cocaine-dependent patient with an atypical antipsychotic
Electron-electron Bound States in Parity-Preserving QED3
By considering the Higgs mechanism in the framework of a parity-preserving
Planar Quantum Electrodynamics, one shows that an attractive electron-electron
interaction may come out. The e-e interaction potential emerges as the
non-relativistic limit of the Moller scattering amplitude and it may result
attractive with a suitable choice of parameters. Numerical values of the e-e
binding energy are obtained by solving the two-dimensional Schrodinger
equation. The existence of bound states is to be viewed as an indicative that
this model may be adopted to address the pairing mechanism in some systems
endowed with parity-preservation.Comment: 6 pages, 1 table, style revte
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