Parametric Competition in non-autonomous Hamiltonian Systems

In this work we use the formalism of chord functions (\emph{i.e.} characteristic functions) to analytically solve quadratic non-autonomous Hamiltonians coupled to a reservoir composed by an infinity set of oscillators, with Gaussian initial state. We analytically obtain a solution for the characteristic function under dissipation, and therefore for the determinant of the covariance matrix and the von Neumann entropy, where the latter is the physical quantity of interest. We study in details two examples that are known to show dynamical squeezing and instability effects: the inverted harmonic oscillator and an oscillator with time dependent frequency. We show that it will appear in both cases a clear competition between instability and dissipation. If the dissipation is small when compared to the instability, the squeezing generation is dominant and one can see an increasing in the von Neumann entropy. When the dissipation is large enough, the dynamical squeezing generation in one of the quadratures is retained, thence the growth in the von Neumann entropy is contained

Avaliação das silagens do sorgo BRS-610 em sete estádios de maturação pela técnica in vitro semiautomática de produção de gases.

Avaliou-se a qualidade da silagem do sorgo BRS-610 produzida em sete estádios de maturação dos grãos, pela técnica in vitro semi automática de produção de gases. O delineamento foi inteiramente ao acaso, com quatro repetições por tratamento, e as médias foram comparadas pelo teste Scott-knott. Os parâmetros potencial máximo de produção de gases, tempo de colonização, taxa de produção de gases e degradabilidade efetiva da matéria seca para as taxas de passagem de 2, 5 e 8%/h foram obtidos pelo modelo de France et al. O potencial máximo de produção de gases não diferiu entre as silagens e indicou média de 170,5mLmg de matéria seca. Entre leitoso/pastoso e pastoso houve menor tempo de colonização. As maiores taxas de fermentação foram observadas nas silagens produzida entre os estádios pastoso/farináceo a seco. As degradabilidades efetivas foram semelhantes entres as silagens, com média de 46,2%. O sorgo BRS-610 produziu silagem de qualidade satisfatória, com destaque para a silagem produzida com a planta no estádio pastoso/farináceo, por associar melhor taxa de fermentação e menor tempo de colonização

Gene flow from transgenic common beans expressing the bar gene.

Gene flow is a common phenomenon even in self-pollinated plant species. With the advent of genetically modified plants this subject has become of the utmost importance due to the need for controlling the spread of transgenes. This study was conducted to determine the occurrence and intensity of outcrossing in transgenic common beans. In order to evaluate the outcross rates, four experiments were conducted in Santo Antonio de Goiás (GO, Brazil) and one in Londrina (PR, Brazil), using transgenic cultivars resistant to the herbicide glufosinate ammonium and their conventional counterparts as recipients of the transgene. Experiments with cv. Olathe pinto and the transgenic line Olathe M1/4 were conducted in a completely randomized design with ten replications for three years in one location, whereas the experiments with cv. Pérola and the transgenic line Pérola M1/4 were conducted at two locations for one year, with the transgenic cultivar surrounded on all sides by the conventional counterpart. The outcross occurred at a negligible rate of 0.00741% in cv. Pérola, while none was observed (0.0%) in cv. Olathe pinto. The frequency of gene flow was cultivar dependent and most of the observed outcross was within 2.5 m from the edge of the pollen source

Diferenciação de cultivares de feijão de origem transgênica e convencional por RMN HR-MAS de 1H e análise quimiométrica.

O objetivo do presente estudo foi avaliar as diferenças na composição química dos grãos dos cultivares Olathe Pinto convencional e o seu geneticamente modificado (Olathe Pinto 5.1) e uma possível transferência gênica aos cultivares Pontal e Perola, utilizando a ressonância magnética nuclear, em análise particular da técnica HR-MAS, e técnicas quimiométricas.Conpeex 2010

Caracterização parcial de geminivirus de feijoeiro e de plantas daninhas coletadas em campo de feijoeiro.

O feijoeiro continua sendo severamente afetado pela presença do mosaico dourado, causado pelo Bean Golden mosaic virus (BGMV). Epidemias de mosca branca (Bemisia tabaci) 2012/2013 causou grandes perdas principalmente devido ao BGMV. Foram coletadas amostras de plantas com sintomas de geminiviroses em Phaseolus vulgaris de Ponte Nova - PN (MG), Sida sp, e Nicandra physaloides, em Santo Antônio de Goiás (GO)

Abundance trend with condensation temperature for stars with different Galactic birth places

During the past decade, several studies reported a correlation between chemical abundances of stars and condensation temperature (also known as Tc trend). However, the real astrophysical nature of this correlation is still debated. The main goal of this work is to explore the possible dependence of the Tc trend on stellar Galactocentric distances, Rmean. We used high-quality spectra of about 40 stars observed with the HARPS and UVES spectrographs to derive precise stellar parameters, chemical abundances, and stellar ages. A differential line-by-line analysis was applied to achieve the highest possible precision in the chemical abundances. We confirm previous results that [X/Fe] abundance ratios depend on stellar age and that for a given age, some elements also show a dependence on Rmean. When using the whole sample of stars, we observe a weak hint that the Tc trend depends on Rmean. The observed dependence is very complex and disappears when only stars with similar ages are considered. To conclude on the possible dependence of the Tc trend on the formation place of stars, a larger sample of stars with very similar atmospheric parameters and stellar ages observed at different Galactocentric distances is neededComment: Accepted by A&

Avaliação da plasticidade morfológica de cultivares de feijoeiro comum.

Os objetivos do trabalho foram determinar quais as características fenológicas são mais eficientes na avaliação da plasticidade e classificar cultivares de feijoeiro comum quanto a plasticidade em diferentes espaçamento entre linhas e número de plantas por metro

Constraining planet structure and composition from stellar chemistry: trends in different stellar populations

The chemical composition of stars that have orbiting planets provides important clues about the frequency, architecture, and composition of exoplanet systems. We explore the possibility that stars from different galactic populations that have different intrinsic abundance ratios may produce planets with a different overall composition. We compiled abundances for Fe, O, C, Mg, and Si in a large sample of solar neighbourhood stars that belong to different galactic populations. We then used a simple stoichiometric model to predict the expected iron-to-silicate mass fraction and water mass fraction of the planet building blocks, as well as the summed mass percentage of all heavy elements in the disc. Assuming that overall the chemical composition of the planet building blocks will be reflected in the composition of the formed planets, we show that according to our model, discs around stars from different galactic populations, as well as around stars from different regions in the Galaxy, are expected to form rocky planets with significantly different iron-to-silicate mass fractions. The available water mass fraction also changes significantly from one galactic population to another. The results may be used to set constraints for models of planet formation and chemical composition. Furthermore, the results may have impact on our understanding of the frequency of planets in the Galaxy, as well as on the existence of conditions for habitability.Comment: Accepted for publication in Astronomy & Astrophysic

Distinguishing the albedo of exoplanets from stellar activity

Light curves show the flux variation from the target star and its orbiting planets as a function of time. In addition to the transit features created by the planets, the flux also includes the reflected light component of each planet, which depends on the planetary albedo. This signal is typically referred to as phase curve and could be easily identified if there were no additional noise. As well as instrumental noise, stellar activity, such as spots, can create a modulation in the data, which may be very difficult to distinguish from the planetary signal. We analyze the limitations imposed by the stellar activity on the detection of the planetary albedo, considering the limitations imposed by the predicted level of instrumental noise and the short duration of the observations planned in the context of the CHEOPS mission. As initial condition, we have assumed that each star is characterized by just one orbiting planet. We built mock light curves that included a realistic stellar activity pattern, the reflected light component of the planet and an instrumental noise level, which we have chosen to be at the same level as predicted for CHEOPS. We then fit these light curves to try to recover the reflected light component, assuming the activity patterns can be modeled with a Gaussian process.We estimate that at least one full stellar rotation is necessary to obtain a reliable detection of the planetary albedo. This result is independent of the level of noise, but it depends on the limitation of the Gaussian process to describe the stellar activity when the light curve time-span is shorter than the stellar rotation. Finally, in presence of typical CHEOPS gaps in the simulations, we confirm that it is still possible to obtain a reliable albedo.Comment: Accepted for publication in A&A, 14 pages, 12 figure