8,876 research outputs found
Ergodic Transport Theory, periodic maximizing probabilities and the twist condition
The present paper is a follow up of another one by A. O. Lopes, E. Oliveira
and P. Thieullen which analyze ergodic transport problems. Our main focus will
a more precise analysis of case where the maximizing probability is unique and
is also a periodic orbit.
Consider the shift T acting on the Bernoulli space \Sigma={1, 2, 3,..,
d}^\mathbb{N} A:\Sigma \to \mathbb{R} a Holder potential.
Denote m(A)=max_{\nu is an invariant probability for T} \int A(x) \; d\nu(x)
and, \mu_{\infty,A}, any probability which attains the maximum value. We assume
this probability is unique (a generic property). We denote \T the bilateral
shift. For a given potential Holder A:\Sigma \to \mathbb{R}, we say that a
Holder continuous function W: \hat{\Sigma} \to \mathbb{R} is a involution
kernel for A, if there is a Holder function A^*:\Sigma \to \mathbb{R}, such
that, A^*(w)= A\circ \T^{-1}(w,x)+ W \circ \T^{-1}(w,x) - W(w,x). We say that
A^* is a dual potential of A. It is true that m(A)=m(A^*). We denote by V the
calibrated subaction for A, and, V^* the one for A^*. We denote by I^* the
deviation function for the family of Gibbs states for \beta A, when \beta \to
\infty.
For each x we get one (more than one) w_x such attains the supremum above.
That is, solutions of V(x) = W(w_x,x) - V^* (w_x)- I^*(w_x).
A pair of the form (x,w_x) is called an optimal pair. If \T is the shift
acting on (x,w) \in {1, 2, 3,.., d}^\mathbb{Z}, then, the image by \T^{-1} of
an optimal pair is also an optimal pair.
Theorem - Generically, in the set of Holder potentials A that satisfy
(i) the twist condition,
(ii) uniqueness of maximizing probability which is supported in a periodic
orbit, the set of possible optimal w_x, when x covers the all range of possible
elements x in \in \Sigma, is finite
Comparative study on the susceptibility of freshwater species to copper-based pesticides.
Abstract Copper compounds have been intentionally introduced into water bodies as aquatic plant herbicides, algicides and molluscicides. Copper-based fertilizers and fungicides have been widely used in agriculture as well. Despite the fact that copper is an essential element for all biota, elevated concentrations of this metal have been shown to affect a variety of aquatic organisms. Nonetheless, comparative studies on the susceptibility of different freshwater species to copper compounds have seldom been performed. This study was conducted to compare toxicity of copper-based pesticides (copper oxychloride, cuprous oxide and copper sulfate) to different freshwater target (Raphidocelis subcapitata, a planktonic alga and Biomphalaria glabrata, a snail) and non-target (Daphnia similis, a planktonic crustacean and Danio rerio, a fish) organisms. Test water parameters were as follows: pH=7.4 ± 0.1; hardness 44 ± 1 mg/l as CaCO3; DO 8?9 mg/l at the beginning and >4 mg/l at the end; temperature, fish and snails 25 ± 1 °C, Daphnia 20 ± 2 °C, algae 24 ± 1 °C. D. similis (immobilization), 48-h EC50s (95% CLs) ranging from 0.013 (0.011?0.016) to 0.043 (0.033?0.057) mg Cu/l, and R. subcapitata (growth inhibition), 96-h IC50s from 0.071 (0.045?0.099) to 0.137 (0.090?0.174) mg Cu/l, were the most susceptible species. B. glabrata (lethality), 48-h LC50s from 0.179 (0.102?0.270) to 0.854 (0.553?1.457) mg Cu/l, and D. rerio (lethality), 48-h LC50s 0.063 (0.045?0.089), 0.192 (0.133?0.272) and 0.714 (0.494?1.016) mg Cu/l, were less susceptible than Daphnia to copper-based pesticides. Findings from the present study therefore suggest that increased levels of copper in water bodies is likely to adversely affect a variety of aquatic species
A Review on Geotrichum Lipases: Production, Purification, Immobilization and Applications
Lipases are enzymes produced from innumerous microorganisms, plants and animal cells. They catalyze reactions of different lipid sources. The Geotrichum fungi are good producers of lipases with high hydrolytic activity and specificity for unsaturated fatty acids. A great number of studies have reported the importance of lipase from this genus and described important fermentation parameters for the enzyme production, such as nutrients, temperature, pH, inoculum, time of fermentation and others. Furthermore, different strategies have been used to purify and immobilize lipases from Geotrichum and
innumerous applications are cited in different processes as polyunsaturated fatty acids enrichment, hydrolysis and esterification of fat and oils, synthesis of aromas, biodiesel, and many others. This review highlights fundamental aspects of the production, purification, characterization, immobilization, and the applications of lipases produced by the genus Geotrichum
Determinação de perdas de solo, água e nutrientes em Latossolo Amarelo, textura argilosa do Nordeste paraense.
bitstream/item/34520/1/ORIENTAL-BP19.pd
Produção integrada no Vale do São Francisco: situação e perspectivas - a produção intergrada de uvas como caso de sucesso.
Avanços e sucessos da produção integrada de uva no vale do São Francisco.
A fruticultura no pólo agrícola Petrolina-PE/Juazeiro-BA, situado na região do Submédio do Vale do São Francisco, tem se caracterizado por apresentar uma rápida expansão da área cultivada, um elevado crescimento da produção e um significativo desenvolvimento do setor exportador de frutas, condicionando a região a vislumbrar uma perspectiva concreta de promover uma grande melhoria sócio-econômica. Entre as fruteiras cultivadas neste importante pólo de irrigação, com potencial para inserção no mercado externo, destaca-se a uva de mesa, responsável por 99% das exportações brasileiras de uvas finas de mesa, cuja área plantada é de aproximadamente, 10.890 ha e produção de 81.595 kg (VALEXPORT, 2009). O objetivo do trabalho foi dar continuidade às ações implementadas da Produção Integrada de Uvas Finas de Mesa e implantar este sistema em novas áreas, tendo como área piloto o Submédio do Vale do São Francisco, de acordo com as Normas Técnicas Específicas para a PI-Uva, estabelecidas pela Instrução Normativa nº 20, do MAPA
Análise preliminar da morfologia e da micromorfologia de alguns solos antrópicos dos municípios de Barcarena, Abaetetuba e Mojú, Nordeste do Pará.
Grand-canonical Thermodynamic Formalism via IFS: volume, temperature, gas pressure and grand-canonical topological pressure
We consider here a dynamic model for a gas in which a variable number of
particles can be located at a
site. This point of view leads us to the grand-canonical framework and the need
for a chemical potential. The dynamics is played by the shift acting on the set
of sequences , where the alphabet is
. Introducing new variables like the
number of particles and the chemical potential , we adapt the concept
of grand-canonical partition sum of thermodynamics of gases to a symbolic
dynamical setting considering a Lipschitz family of potentials % (A_N)_{N \in
\mathbb{N}_0}, . Our main results will be obtained
from adapting well-known %properties the results will be obtained through the
use of known properties of the Thermodynamic Formalism for IFS with weights to
our setting. In this direction, we introduce the grand-canonical transfer
(Ruelle) operator: , when, and
We show
the existence of the main eigenvalue, an associated eigenfunction, and an
eigenprobability for . Considering the concept of
entropy for holonomic probabilities on % , we relate
these items with the variational problem of maximizing grand-canonical
pressure. In another direction, in the appendix, we briefly digress on a
possible interpretation of the concept of topological pressure as related to
the gas pressure of gas thermodynamics
Experimental determination of the non-extensive entropic parameter
We show how to extract the parameter from experimental data, considering
an inhomogeneous magnetic system composed by many Maxwell-Boltzmann homogeneous
parts, which after integration over the whole system recover the Tsallis
non-extensivity. Analyzing the cluster distribution of
LaSrMnO manganite, obtained through scanning tunnelling
spectroscopy, we measure the parameter and predict the bulk magnetization
with good accuracy. The connection between the Griffiths phase and
non-extensivity is also considered. We conclude that the entropic parameter
embodies information about the dynamics, the key role to describe complex
systems.Comment: Submitted to Phys. Rev. Let
Relação entre características bioquímicas e agronômicas e o enfezamento pálido em milho.
Foram avaliadas, em plântulas de milho, características bioquímicas, como possíveis marcadores para seleção de genótipos resistentes ao enfezamento pálido, causado por Spiroplasma kunkelii, bem como o efeito dessa doença sobre o crescimento e a produção de genótipos de milho. Para isto, espiroplasma foi inoculado nas plântulas das linhagens parentais susceptíveis, P1, e resistente, P2, e nas gerações F1, F2 e F3. Essas linhagens parentais, utilizadas também em intercruzamentos para obtenção das demais gerações, são oriundas do programa de melhoramento da Embrapa Milho e Sorgo. A altura das plantas (AP), a altura de espiga (AE) e a produção de grãos (PG) foram as características afetadas pela infecção por espiroplasma, que causou reduções médias de, respectivamente, 9,60%, 12,83% e 42% nesses parâmetros. Elevados valores, acima de 0,80, foram obtidos em correlações fenotípica e genotípica entre nota da espiga (NE) e severidade da doença enfezamento pálido (SEV), entre SEV e PG e entre NE e PG, mostrando que essas características podem ser utilizadas como critério para seleção de genótipos resistentes ao enfezamento pálido. Dentre as características bioquímicas avaliadas, verificou-se tendência de as plantas resistentes apresentarem maiores valores de teor de proteínas solúveis e menores valores de atividade específica da peroxidase (PODesp). As correlações fenotípicas entre os teores de ácido ferúlico (FA) e 5,5`-di-ferúlico (DFA) e SEV não foram significativas e os zimogramas da peroxidase não apresentaram isoformas que estivessem associadas especificamente à resistência ou à susceptibilidade ao enfezamento pálido
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