Convergence radius of perturbative Lindblad driven non-equilibrium steady states

We address the problem of analyzing the radius of convergence of perturbative expansion of non-equilibrium steady states of Lindblad driven spin chains. A simple formal approach is developed for systematically computing the perturbative expansion of small driven systems. We consider the paradigmatic model of an open $XXZ$ spin 1/2 chain with boundary supported ultralocal Lindblad dissipators and treat two different perturbative cases: (i) expansion in system-bath coupling parameter and (ii) expansion in driving (bias) parameter. In the first case (i) we find that the radius of convergence quickly shrinks with increasing the system size, while in the second case (ii) we find that the convergence radius is always larger than $1$, and in particular it approaches $1$ from above as we change the anisotropy from easy plane ($XY$) to easy axis (Ising) regime

Fast method for the determination of short-chain-length polyhydroxyalkanoates (scl-PHAs) in bacterial samples by In Vial-Thermolysis (IVT)

none8siA new method based on the GC–MS analysis of thermolysis products obtained by treating bacterial samples at a high temperature (above 270 C) has been developed. This method, here named “In-Vial- Thermolysis” (IVT), allowed for the simultaneous determination of short-chain-length polyhydrox- yalkanoates (scl-PHA) content and composition. The method was applied to both single strains and microbial mixed cultures (MMC) fed with different carbon sources. The IVT procedure provided similar analytical performances compared to previous Py-GC–MS and Py- GC-FID methods, suggesting a similar application for PHA quantitation in bacterial cells. Results from the IVT procedure and the traditional methanolysis method were compared; the correlation between the two datasets was fit for the purpose, giving a R2 of 0.975. In search of further simplification, the rationale of IVT was exploited for the development of a “field method” based on the titration of thermolyzed samples with sodium hydrogen carbonate to quantify PHA inside bacterial cells. The accuracy of the IVT method was fit for the purpose. These results lead to the possibility for the on-line measurement of PHA productivity. Moreover, they allow for the fast and inexpensive quantification/characterization of PHA for biotechnological process control, as well as investigation over various bacterial communities and/or feeding strategies.mixedF. Abbondanzi; G. Biscaro; G. Carvalho; L. Favaro; P. Lemos; M. Paglione; C. Samorì; C. TorriF. Abbondanzi; G. Biscaro; G. Carvalho; L. Favaro; P. Lemos; M. Paglione; C. Samorì; C. Torr

Efeito de agentes desinfestantes e antioxidantes no estabelecimento de ápices caulinares in vitro de cultivares de bananeira.

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Pair creation of higher dimensional black holes on a de Sitter background

We study in detail the quantum process in which a pair of black holes is created in a higher D-dimensional de Sitter (dS) background. The energy to materialize and accelerate the pair comes from the positive cosmological constant. The instantons that describe the process are obtained from the Tangherlini black hole solutions. Our pair creation rates reduce to the pair creation rate for Reissner-Nordstrom-dS solutions when D=4. Pair creation of black holes in the dS background becomes less suppressed when the dimension of the spacetime increases. The dS space is the only background in which we can discuss analytically the pair creation process of higher dimensional black holes, since the C-metric and the Ernst solutions, that describe respectively a pair accelerated by a string and by an electromagnetic field, are not know yet in a higher dimensional spacetime.Comment: 10 pages; 1 figure included; RexTeX4. v2: References added. Published version. v3: Typo in equation (46) fixe

Concentrações de citocinina e carvão ativado na micropropagação de pimenta-do-reino.

A pimenta-do-reino (Piper nigrum) tem grande importância para a economia do Norte do Brasil. A pimentado-reino é propagada principalmente por estaquia que, além de ser pouco eficiente, pode possibilitar a propagação da doença fusariose. Dessa forma, testes para verificar a eficiência da micropropagação são pertinentes. O objetivo do trabalho foi testar concentrações de BAP - 6-benzilaminopurina (0,5, 1,5, 3,0 e 4,5mg L-1) e a adição de carvão ativado a 0,2% ao meio de cultura na micropropagação de pimenta-do-reino. O meio de cultura foi composto de sais e vitaminas de Murashige & Skoog, 3% de sacarose e 8g L-1 de ágar. Foram utilizados como explantes ápices caulinares de plântulas da cultivar ?Bragantina? germinadas in vitro. Os tratamentos foram avaliados em esquema fatorial 4x2, em delineamento inteiramente casualizado. Após 45 dias no estabelecimento, foi avaliado o número de brotos, mas não foi observada diferença significativa entre os tratamentos, considerando-se os dois fatores e a interação entre eles. Após 45 dias no primeiro subcultivo, foram avaliados o número de brotos e de explantes (segmentos nodais). A interação entre BAP e carvão ativado teve efeito significativo para número de brotos e de explantes, sendo que o carvão influenciou o efeito das concentrações de BAP. A concentração de 0,5mg L-1 de BAP na ausência de carvão ativado gerou maior número de brotos e de explantes. O carvão ativado não é necessário na fase de proliferação de gemas de pimenta-do-reino da cultivar ?Bragantina?.Título em inglês: Cytokynin concentrations and activated charcoal on black pepper micropropagation

Effect of Water Content on the Thermal Inactivation Kinetics of Horseradish Peroxidase Freeze-Dried from Alkaline pH

The thermal inactivation of horseradish peroxidase freeze-dried from solutions of different pH (8, 10 and 11.5, measured at 25 C) and equilibrated to different water contents was studied in the temperature range from 110 to 150 C. The water contents studied (0.0, 1.4, 16.2 and 25.6 g water per 100 g of dry enzyme) corresponded to water activities of 0.0, 0.11, 0.76 and 0.88 at 4 C. The kinetics were well described by a double exponential model. The enzyme was generally more stable the lower the pH of the original solution, and for all pH values, the maximum stability was obtained at 1.4 g water/100 g dry enzyme. Values of z were generally independent of water content and of the pH of the original solution, and in the range of 15–25 °C, usually found in neutral conditions, with the exception of the enzyme freeze dried from pH 11.5 and equilibrated with phosphorus pentoxide, where a z-value of the stable fraction close to 10 C was found