Contribuição ao conhecimento sobre os Miobantia Giglio-Tos (Mantodea, Thespidae, Miopteryginae), com associação molecular de sexos dimórficos e estágios imaturos, e descrição de quatro espécies novas

O gênero neotropical de louva-a-deus Miobantia Giglio-Tos inclui seis espécies com uma história taxonômica complexa. Embora freqüentemente encontradas na Mata Atlântica, pouco se sabe sobre elas e alguns obstáculos tornam difícil identificá-las, como o dimorfismo sexual elevado e o conhecimento de ambos os sexos para apenas uma das seis espécies. Este trabalho investiga os limites taxonômicos das espécies de Miobantia através de uma análise cladística, utilizando 99 caracteres morfológicos, além de seqüenciamento de 700 pb do gene mitocondrial COI para a associação de sexos dimórficos e ninfas. A variação intra-específica é também investigada a partir de um grande número de espécimes de M. fuscata (Giglio-Tos) para escolher características mais relevantes para a separação das espécies a serem utilizados nos comentários taxonómicos e nas chaves de identificação. O macho de M. aptera Giglio-Tos, e as fêmeas de M. ciliata (Stål) e M. fuscata são descritos pela primeira vez, e são fornecidas redescrições dos machos destas e da fêmea de M. aptera com base em numerosos dados complementares. Miobantia nebulosa (Giglio-Tos) é proposta como sinônimo júnior de M. rustica (Fabr.), com base na comparação entre seus tipos, incluindo a investigação de genitália masculina, e a espécie é redescrita. Adicionalmente, quatro novas espécies são aqui descritas: M. sp. nov. 1 sp. nov., M. sp. nov. 2 sp. nov., M. sp. nov. 3 sp. nov., e M. sp. nov. 4 sp. nov.; ambos os sexos são descritos, com exceção apenas para o macho de M. sp. nov. 2. Chaves de identificação são fornecidas para machos e fêmeas das espécies válidas, e figuras das características diagnósticas são fornecidas para todos eles. A distribuição das espécies é mapeada de acordo com dados da literatura e 50 novos registros

Dynamical demixing of a binary mixture under sedimentation

We investigate the sedimentation dynamics of a binary mixture, the species of which differ by their Stokes coefficients but are identical otherwise. We analyze the sedimentation dynamics and the morphology of the final deposits using Brownian dynamics simulations for mixtures with a range of sedimentation velocities of both species. We found a threshold in the sedimentation velocities difference above which the species in the final deposit are segregated. The degree of segregation increases with the difference in the Stokes coefficients or the sedimentation velocities above the threshold. We propose a simple mean-field model that captures the main features of the simulated deposits

Universal R-C crossover in current-voltage characteristics for unshunted array of overdamped Nb-AlO_x-Nb Josephson junctions

We report on some unusual behavior of the measured current-voltage characteristics (CVC) in artificially prepared two-dimensional unshunted array of overdamped Nb-AlO_x-Nb Josephson junctions. The obtained nonlinear CVC are found to exhibit a pronounced (and practically temperature independent) crossover at some current I_{cr}=\left(\frac{1}{2\beta_C}-1\right)I_C from a resistance R dominated state with V_R=R\sqrt{I^2-I_C^2} below I_{cr} to a capacitance C dominated state with V_C=\sqrt{\frac{\hbar}{4eC}} \sqrt{I-I_C} above I_{cr}. The origin of the observed behavior is discussed within a single-plaquette approximation assuming the conventional RSJ model with a finite capacitance and the Ambegaokar-Baratoff relation for the critical current of the single junction

Manifestation of geometric resonance in current dependence of AC susceptibility for unshunted array of Nb-AlOx-Nb Josephson junctions

A pronounced resonance-like structure has been observed in the current dependence of AC susceptibility for two-dimensional array of unshunted Nb-AlOx-Nb Josephson junctions. Using a single-plaquette approximation, we were able to successfully fit our data assuming that resonance structure is related to the geometric (inductive) properties of the array.Comment: to appear in Physica C (in press

Agroecologia e desenvolvimento sustentável.

O desenvolvimento sustentável tem suas bases conceituais assentadas na Agenda XXI de 1992, que será revisitada na Rio +20, em junho de 2012, como resultado do pacto firmado pelas Nações Unidas com o mundo, para enfrentar os desafios socioambientais e econômicos decorrentes da crise mundial iniciada na década de 1970. Assim, nos últimos 20 anos, todo o sistema econômico vem tentando se ajustar ao que é denominado desenvolvimento sustentável

Synchronization and Stability in Noisy Population Dynamics

We study the stability and synchronization of predator-prey populations subjected to noise. The system is described by patches of local populations coupled by migration and predation over a neighborhood. When a single patch is considered, random perturbations tend to destabilize the populations, leading to extinction. If the number of patches is small, stabilization in the presence of noise is maintained at the expense of synchronization. As the number of patches increases, both the stability and the synchrony among patches increase. However, a residual asynchrony, large compared with the noise amplitude, seems to persist even in the limit of infinite number of patches. Therefore, the mechanism of stabilization by asynchrony recently proposed by R. Abta et. al., combining noise, diffusion and nonlinearities, seems to be more general than first proposed.Comment: 3 pages, 3 figures. To appear in Phys. Rev.

Percolation with long-range correlated disorder

Long-range power-law correlated percolation is investigated using Monte Carlo simulations. We obtain several static and dynamic critical exponents as function of the Hurst exponent $H$ which characterizes the degree of spatial correlation among the occupation of sites. In particular, we study the fractal dimension of the largest cluster and the scaling behavior of the second moment of the cluster size distribution, as well as the complete and accessible perimeters of the largest cluster. Concerning the inner structure and transport properties of the largest cluster, we analyze its shortest path, backbone, red sites, and conductivity. Finally, bridge site growth is also considered. We propose expressions for the functional dependence of the critical exponents on $H$

Deciphering M-T diagram of shape memory Heusler alloys: reentrance, plateau and beyond

We present our recent results on temperature behaviour of magnetization observed in Ni_47Mn_39In_14 Heusler alloys. Three regions can be distinguished in the M-T diagram: (I) low temperature martensitic phase (with the Curie temperature T_CM = 140 K), (II) intermediate mixed phase (with the critical temperature T_MS = 230 K) exhibiting a reentrant like behavior (between T_CM and T_MS) and (III) high temperature austenitic phase (with the Curie temperature T_CA = 320 K) exhibiting a rather wide plateau region (between T_MS and T_CA). By arguing that powerful structural transformations, causing drastic modifications of the domain structure in alloys, would also trigger strong fluctuations of the order parameters throughout the entire M-T diagram, we were able to successfully fit all the data by incorporating Gaussian fluctuations (both above and below the above three critical temperatures) into the Ginzburg-Landau scenario