A model for Hopfions on the space-time S^3 x R

We construct static and time dependent exact soliton solutions for a theory of scalar fields taking values on a wide class of two dimensional target spaces, and defined on the four dimensional space-time S^3 x R. The construction is based on an ansatz built out of special coordinates on S^3. The requirement for finite energy introduces boundary conditions that determine an infinite discrete spectrum of frequencies for the oscillating solutions. For the case where the target space is the sphere S^2, we obtain static soliton solutions with non-trivial Hopf topological charges. In addition, such hopfions can oscillate in time, preserving their topological Hopf charge, with any of the frequencies belonging to that infinite discrete spectrum.Comment: Enlarged version with the time-dependent solutions explicitly given. One reference and two eps figures added. 14 pages, late

Local roughness exponent in the nonlinear molecular-beam-epitaxy universality class in one-dimension

We report local roughness exponents, $\alpha_{\text{loc}}$, for three interface growth models in one dimension which are believed to belong the non-linear molecular-beam-epitaxy (nMBE) universality class represented by the Villain-Lais-Das Sarma (VLDS) stochastic equation. We applied an optimum detrended fluctuation analysis (ODFA) [Luis et al., Phys. Rev. E 95, 042801 (2017)] and compared the outcomes with standard detrending methods. We observe in all investigated models that ODFA outperforms the standard methods providing exponents in the narrow interval $\alpha_{\text{loc}}\in[0.96,0.98]$ consistent with renormalization group predictions for the VLDS equation. In particular, these exponent values are calculated for the Clarke-Vvdensky and Das Sarma-Tamborenea models characterized by very strong corrections to the scaling, for which large deviations of these values had been reported. Our results strongly support the absence of anomalous scaling in the nMBE universality class and the existence of corrections in the form $\alpha_{\text{loc}}=1-\epsilon$ of the one-loop renormalization group analysis of the VLDS equation

Adaptive linearizing control of bioreactors

In this communication we shall present developments concerning the synthesis of Single-Input, Single-Output (SISO) and Multi-Input, Multi-Output (MIMO) adaptive linearizing algorithms for the operation of bioreactors. Results will be illustrated for the baker’s yeast fermentation process. The synthesis of these non-linear control laws is performed by employing differential geometry techniques with system linearization by state feedback. The controller design includes a step of order reduction of the process state model. The adaptive feature comes from the on-line estimation of the required process time varying parameters. The adaptive algorithm proposed enforces a desired and pre-set second order convergence dynamics as originally introduced by Oliveira et al. (1). Formulating the estimator on this basis leaves the user with the choice of two simple and intuitive tuning parameters with physical meaning - a damping coefficient and a natural period of oscillation.Instituto de Sistemas e Robótica; Universidade do Porto. Faculdade de Engenharia; Comunidade Europeia, programa HC&M

Unidentified Galactic High-Energy Sources as Ancient Pulsar Wind Nebulae in the light of new high energy observations and the new code

In a Pulsar Wind Nebula (PWN), the lifetime of inverse Compton (IC) emitting electrons exceeds the lifetime of its progenitor pulsar (as well as its shell-type remnant), but it also exceeds the age of those that emit via synchrotron radiation. Therefore, during its evolution, the PWN can remain bright in IC so that its GeV-TeV gamma-ray flux remains high for timescales much larger (for 10^5 - 10^6 yrs) than the pulsar lifetime and the X-ray PWN lifetime. In this scenario, the magnetic field in the cavity induced by the wind of the progenitor star plays a crucial role. This scenario is in line with the discovery of several unidentified or "dark" sources in the TeV gamma-ray band without X-ray counterparts; and it is also finding confirmation in the recent discoveries at GeV gamma rays. Moreover, these consequences could be also important for reinterpreting the detection of starburst galaxies in the TeV gamma-ray band when considering a leptonic origin of the gamma-ray signal. Both theoretical aspects and their observational proofs will be discussed, as well as the first results of our new modeling code.Comment: Proceedings of the 5th International Symposium on High-Energy Gamma-Ray Astronomy (Gamma2012

Análise de dois métodos de quantificação de DNA em amostras de diferentes populações de açaizeiro.

Em reações PCR faz-se necessário trabalhar com DNA de boa qualidade. E conhecer a eficiência de cada processo na análise de DNA, tais como a extração e a quantificação do DNA. A quantificação envolve a estimativa da concentração do DNA obtida, que depende do tipo e quantidade de amostra disponível. Dentre os métodos disponíveis para quantificação tem-se a eletroforese em gel de agarose, que permite a resolução de ácidos nuciéicos, um método comparativo, e a utilização do fluorímetro, um equipamento que trabalha com alterações nas caracteristicas de f1uorescência na presença de DNA, um método quantitativo. O objetivo deste trabalho foi analisar esses dois métodos na quantificação de amostras de DNA de açaizeiro verificando a eficácia e a praticidade. Foram extraídos DNA's de folíolos de 87 matrizes de açaizeiro de três populações. A concentração do DNA genômico foi estimada de duas formas: em gel de agarose a 1,0% utilizando a comparação do DNA total com três concentrações do DNA lambda (50, 100 e 200 ng/ IJL) e em fluorímetro, marca Hoefer DyNA Quant 200, por meio da média de duas ou três leituras, conforme a variação de 10% para mais ou para menos da amostra quantificada. O método mais eficaz foi escolhido através de estatística simples, envolvendo média, valores mínimos e máximos e coeficiente de variação para cada população e para amostra total. A quantificação na agarose detectou 87,76; 64,4 e 61,03 ng para as populações de Breves, São Sebastião da Boa Vista e BRS- Pa. A variação ficou entre O e 200ng. No f1uorímetro as quantificações foram 82,06; 82,24 e 49,85 ng para as populações de Breves, São Sebastião da Boa Vista e BRS-Pa. Ficando a variação entre 8 e 335,5ng. A análise desses métodos mostra que os dois métodos são considerados eficientes, sendo a agarose o método mas prático

Requisitos e realização de uma instalação experimental para estudos de modelização e controlo em processos de fermentação

O presente trabalho descreve a integração de técnicas de controlo automático em processos biotecnológicos. Fazse uma análise dos requisitos específicos que uma instalação experimental (reactor biológico e sistema informático) deve apresentar para estudos de monitorização e controlo. É descrito um sistema de aquisição de dados e controlo por computador para processos de fermentação, com aplicação a um processo de produção de fermento de padeiro à escala laboratorial.This work concerns the integration of automatic control techniques in biotechnological processes. An analysis of the specific requirements of an experimental set up (biological reactor equipment plus hard- and software system) for monitoring and control studies is presented. A data acquisition and computer controlled system is described for fermentation processes, with particular application, in this instance, to baker’s yeast production at laboratory scale

Influencia de práticas culturais na infestação da mosca-branca e da geminivirose em tomateiro orgânico.

Este trabalho teve por objetivo determinar a influência dos sistemas de irrigação, do tipo de cobertura do solo e do cultivo consorciado no ataque da mosca-branca e na incidência de geminivirose em tomateiro para mesa conduzido em sistema de orgânico. O Experimento foi conduzido na área de pesquisa e produção orgânica de hotaliças da Embrapa Hortaliças (CNPH).CD-ROM. Suplemento. Trabalho apresentado no 51. Congresso Brasileiro de Olericultura, Viçosa, MG

Genetic diversity of peanut (Arachis hypogaea L.) and its wild relatives based on the analysis of hypervariable regions of the genome

BACKGROUND: The genus Arachis is native to a region that includes Central Brazil and neighboring countries. Little is known about the genetic variability of the Brazilian cultivated peanut (Arachis hypogaea, genome AABB) germplasm collection at the DNA level. The understanding of the genetic diversity of cultivated and wild species of peanut (Arachis spp.) is essential to develop strategies of collection, conservation and use of the germplasm in variety development. The identity of the ancestor progenitor species of cultivated peanut has also been of great interest. Several species have been suggested as putative AA and BB genome donors to allotetraploid A. hypogaea. Microsatellite or SSR (Simple Sequence Repeat) markers are co-dominant, multiallelic, and highly polymorphic genetic markers, appropriate for genetic diversity studies. Microsatellite markers may also, to some extent, support phylogenetic inferences. Here we report the use of a set of microsatellite markers, including newly developed ones, for phylogenetic inferences and the analysis of genetic variation of accessions of A. hypogea and its wild relatives. RESULTS: A total of 67 new microsatellite markers (mainly TTG motif) were developed for Arachis. Only three of these markers, however, were polymorphic in cultivated peanut. These three new markers plus five other markers characterized previously were evaluated for number of alleles per locus and gene diversity using 60 accessions of A. hypogaea. Genetic relationships among these 60 accessions and a sample of 36 wild accessions representative of section Arachis were estimated using allelic variation observed in a selected set of 12 SSR markers. Results showed that the Brazilian peanut germplasm collection has considerable levels of genetic diversity detected by SSR markers. Similarity groups for A. hypogaea accessions were established, which is a useful criteria for selecting parental plants for crop improvement. Microsatellite marker transferability was up to 76% for species of the section Arachis, but only 45% for species from the other eight Arachis sections tested. A new marker (Ah-041) presented a 100% transferability and could be used to classify the peanut accessions in AA and non-AA genome carriers. CONCLUSION: The level of polymorphism observed among accessions of A. hypogaea analyzed with newly developed microsatellite markers was low, corroborating the accumulated data which show that cultivated peanut presents a relatively reduced variation at the DNA level. A selected panel of SSR markers allowed the classification of A. hypogaea accessions into two major groups. The identification of similarity groups will be useful for the selection of parental plants to be used in breeding programs. Marker transferability is relatively high between accessions of section Arachis. The possibility of using microsatellite markers developed for one species in genetic evaluation of other species greatly reduces the cost of the analysis, since the development of microsatellite markers is still expensive and time consuming. The SSR markers developed in this study could be very useful for genetic analysis of wild species of Arachis, including comparative genome mapping, population genetic structure and phylogenetic inferences among species

Stellar parameters for stars of the CoRoT exoplanet field

Aims:To support the computation and evolutionary interpretation of periods associated with the rotational modulation, oscillations, and variability of stars located in the CoRoT fields, we are conducting a spectroscopic survey for stars located in the fields already observed by the satellite. These observations allow us to compute physical and chemical parameters for our stellar sample. Method: Using spectroscopic observations obtained with UVES/VLT and Hydra/Blanco, and based on standard analysis techniques, we computed physical and chemical parameters ($T_{\rm{eff}}$, $\log \,(g)$, $\rm{[Fe/H]}$, $v_{\rm{mic}}$, $v_{\rm{rad}}$, $v \sin \,(i)$, and $A(\rm{Li})$) for a large sample of CoRoT targets. Results: We provide physical and chemical parameters for a sample comprised of 138 CoRoT targets. Our analysis shows the stars in our sample are located in different evolutionary stages, ranging from the main sequence to the red giant branch, and range in spectral type from F to K. The physical and chemical properties for the stellar sample are in agreement with typical values reported for FGK stars. However, we report three stars presenting abnormal lithium behavior in the CoRoT fields. These parameters allow us to properly characterize the intrinsic properties of the stars in these fields. Our results reveal important differences in the distributions of metallicity, $T_{\rm eff}$, and evolutionary status for stars belonging to different CoRoT fields, in agreement with results obtained independently from ground-based photometric surveys. Conclusions: Our spectroscopic catalog, by providing much-needed spectroscopic information for a large sample of CoRoT targets, will be of key importance for the successful accomplishment of several different programs related to the CoRoT mission, thus it will help further boost the scientific return associated with this space mission.Comment: 43 pages, 17 figures, accepted for publication in A&