Estirpes de bactérias selecionadas para a otimização da fixação biológica de nitrogênio em leguminosas florestais .

Este comunicado apresenta resultados de pesquisas referente a seleção de estirpes em condições estéreis para Chamaecrista nictitans (L.) Moench, Mimosa pellita L. e Mimosa floculosa Burkart (etapa 2) e em condições não estéreis para Mimosa xantocentra Mart. e Erythrina falcata Benth (etapa 3). As estirpes testadas pertencem a coleção do Laboratório de Leguminosas da Embrapa Agrobiologia.bitstream/item/42764/1/COT120-09.pd

Robustness of bipartite Gaussian entangled beams propagating in lossy channels

Subtle quantum properties offer exciting new prospects in optical communications. Quantum entanglement enables the secure exchange of cryptographic keys and the distribution of quantum information by teleportation. Entangled bright beams of light attract increasing interest for such tasks, since they enable the employment of well-established classical communications techniques. However, quantum resources are fragile and undergo decoherence by interaction with the environment. The unavoidable losses in the communication channel can lead to a complete destruction of useful quantum properties -- the so-called "entanglement sudden death". We investigate the precise conditions under which this phenomenon takes place for the simplest case of two light beams and demonstrate how to produce states which are robust against losses. Our study sheds new light on the intriguing properties of quantum entanglement and how they may be tamed for future applications.Comment: To be published - Nature Photonic

Estirpes de rizóbio eficientes na fixação biológica de nitrogênio para leguminosas com potencial de uso na recuperação de áreas mineradas.

Este trabalho teve como objetivo selecionar estirpes de rizóbio eficientes na fixação biológica de nitrogênio para leguminosas herbáceas de crescimento rápido e sistema radicular profuso Tephrosia adunca e Mimosa xanthocentra.bitstream/CNPAB-2010/35739/1/cot115.pdfParceria; UFRRJ

Equation level matching: An extension of the method of matched asymptotic expansion for problems of wave propagation

We introduce an alternative to the method of matched asymptotic expansions. In the "traditional" implementation, approximate solutions, valid in different (but overlapping) regions are matched by using "intermediate" variables. Here we propose to match at the level of the equations involved, via a "uniform expansion" whose equations enfold those of the approximations to be matched. This has the advantage that one does not need to explicitly solve the asymptotic equations to do the matching, which can be quite impossible for some problems. In addition, it allows matching to proceed in certain wave situations where the traditional approach fails because the time behaviors differ (e.g., one of the expansions does not include dissipation). On the other hand, this approach does not provide the fairly explicit approximations resulting from standard matching. In fact, this is not even its aim, which to produce the "simplest" set of equations that capture the behavior

Enhancement of bichromatic high-harmonic generation with a high-frequency field

Using a high-frequency field superposed to a linearly polarized bichromatic laser field composed by a wave with frequency $\omega$ and a wave with frequency $2\omega$, we show it is possible to enhance the intensity of a group of high harmonics in orders of magnitude. These harmonics have frequencies about 30% higher than the monochromatic-cutoff frequency, and, within the three-step-model framework, correspond to a set of electron trajectories for which tunneling ionization is strongly suppressed. Particular features in the observed enhancement suggest that the high-frequency field provides an additional mechanism for the electron to reach the continuum. This interpretation is supported by a time-frequency analysis of the harmonic yield. The additional high frequency field permits the control of this group of harmonics leaving all other sets of harmonics practically unchanged, which is an advantage over schemes involving only bichromatic fields.Comment: 6 pages RevTex, 5 figures (ps files), Changes in text, figures, references and equations include

Phases of quantum states in completely positive non-unitary evolution

We define an operational notion of phases in interferometry for a quantum system undergoing a completely positive non-unitary evolution. This definition is based on the concepts of quantum measurement theory. The suitable generalization of the Pancharatnan connection allows us to determine the dynamical and geometrical parts of the total phase between two states linked by a completely positive map. These results reduce to the knonw expressions of total, dynamical and geometrical phases for pure and mixed states evolving unitarily.Comment: 2 figure

Non-Hermitian Hamiltonians with real eigenvalues coupled to electric fields: from the time-independent to the time dependent quantum mechanical formulation

We provide a reviewlike introduction into the quantum mechanical formalism related to non-Hermitian Hamiltonian systems with real eigenvalues. Starting with the time-independent framework we explain how to determine an appropriate domain of a non-Hermitian Hamiltonian and pay particular attention to the role played by PT-symmetry and pseudo-Hermiticity. We discuss the time-evolution of such systems having in particular the question in mind of how to couple consistently an electric field to pseudo-Hermitian Hamiltonians. We illustrate the general formalism with three explicit examples: i) the generalized Swanson Hamiltonians, which constitute non-Hermitian extensions of anharmonic oscillators, ii) the spiked harmonic oscillator, which exhibits explicit supersymmetry and iii) the -x^4-potential, which serves as a toy model for the quantum field theoretical phi^4-theory.Comment: 14 pages, 3 figures, to appear in Laser Physics, minor typos correcte

Time evolution of non-Hermitian Hamiltonian systems

We provide time-evolution operators, gauge transformations and a perturbative treatment for non-Hermitian Hamiltonian systems, which are explicitly time-dependent. We determine various new equivalence pairs for Hermitian and non-Hermitian Hamiltonians, which are therefore pseudo-Hermitian and in addition in some cases also invariant under PT-symmetry. In particular, for the harmonic oscillator perturbed by a cubic non-Hermitian term, we evaluate explicitly various transition amplitudes, for the situation when these systems are exposed to a monochromatic linearly polarized electric field.Comment: 25 pages Latex, 1 eps figure, references adde

Assessment of in vitro biofilm formation and antifungal susceptibility of Candida albicans isolates from vulvovaginal candidiasis

Objectives Vulvovaginal candidiasis (VVC) is an inflammation of the genital mucosa, which mainly affects the vulva and vagina. Candida spp. are considered commensal fungus, however, when there is imbalance in the microbiota or the host immune system is compromised, these can become pathogenic. C. albicans is responsible for most cases of VVC and is able of expressing mechanisms which allow the colonization or infection in the host. These factors related yeasts, including the growth of strains resistant to antifungal agents and virulence attributes (such as biofilm formation) are important in the development of VVC. In this sense, the objective of this study was to evaluate the in vitro biofilm formation and susceptibility to antifungal of C. albicans isolates from patients with vulvovaginal candidiasis. Methods For the study were analyzed 30 clinical isolates of Candida albicans. The clinical isolates were separated in groups of 10 samples of the according to symptoms presented by the patients: asymptomatic (AS), vulvovaginal candidiasis (VVC) and recurrent vulvo- vaginal candidiasis (RVVC). For all isolates were analyzed biofilm formation and minimal inhibitory concentration (MIC) for fluconazole and nystatin. The MIC was performed according to M27-A3 protocol of the Clinical Laboratory Standards Institute. Biofilm forming ability was assessed through quantification of total biomass by crystal violet (CV) staining, performed on 96-well microplates containing a cellular suspension of 1 9 107 cells ml1 and incubated for 24 h at 37°C. Results Antifungal susceptibility testing is showed in table 1. The isolates were tested to the two antifungals. The MIC raging from 0.125 to 2 lg ml1 for fluconazole and 1 to 4 lg ml1 to nystatin. The figure 1 show the quantification of the total biomass. It was evident that all the C. albicans isolates were able to form biofilm, although differences occurred depending on the isolated and consequently the group. Importantly it was noted that, in general, VVC and RVVC groups had similar capacity biofilm formation. On the other hand, these groups had less total biomass (average Abs = 1,091 ` 0.88) compared with AS group (average Abs = 1,521 ` 1.32). Conclusion Although all the samples analyzed are sensitive to anti- fungals tested research of resistant strains is relevant, since recurrences are related to cases of VVC. Nystatin and fluconazole were effective in small concentrations for the isolates analysed. All samples were able to form biofilm and the average of the group of asymptomatic patients greater than the others. Thus, the capacity to form- ing biofilm is an important virulence factor in the persistence of microorganisms in infectious processes and represent an increase in resistance to antifungal and host defense