Local Isometric immersions of pseudo-spherical surfaces and evolution equations

The class of differential equations describing pseudo-spherical surfaces, first introduced by Chern and Tenenblat [3], is characterized by the property that to each solution of a differential equation, within the class, there corresponds a 2-dimensional Riemannian metric of curvature equal to $-1$. The class of differential equations describing pseudo-spherical surfaces carries close ties to the property of complete integrability, as manifested by the existence of infinite hierarchies of conservation laws and associated linear problems. As such, it contains many important known examples of integrable equations, like the sine-Gordon, Liouville and KdV equations. It also gives rise to many new families of integrable equations. The question we address in this paper concerns the local isometric immersion of pseudo-spherical surfaces in ${\bf E}^{3}$ from the perspective of the differential equations that give rise to the metrics. Indeed, a classical theorem in the differential geometry of surfaces states that any pseudo-spherical surface can be locally isometrically immersed in ${\bf E}^{3}$. In the case of the sine-Gordon equation, one can derive an expression for the second fundamental form of the immersion that depends only on a jet of finite order of the solution of the pde. A natural question is to know if this remarkable property extends to equations other than the sine-Gordon equation within the class of differential equations describing pseudo-spherical surfaces. In an earlier paper [11], we have shown that this property fails to hold for all other second order equations, except for those belonging to a very special class of evolution equations. In the present paper, we consider a class of evolution equations for $u(x,t)$ of order $k\geq 3$ describing pseudo-spherical surfaces. We show that whenever an isometric immersion in ${\bf E}^3$ exists, depending on a jet of finite order of $u$, then the coefficients of the second fundamental forms are functions of the independent variables $x$ and $t$ only.Comment: Fields Institute Communications, 2015, Hamiltonian PDEs and Applications, pp.N

Nonlocality tests enhanced by a third observer

We consider Bell tests involving bipartite states shared between three parties. We show that the simple inclusion of a third part may greatly simplify the measurement scenario (in terms of the number of measurement settings per part) and allows the identification of previously unknown nonlocal resources.Comment: 4 pags, 4 figs. v2: fig 3 corrected. V3: refs corrected. Close to published versio

ESTUDO DE UM POSICIONADOR ELETRO-HIDRÁULICO OPERANDO COM CARGA NEGATIVA

No presente trabalho é realizado o estudo comportamental de um posicionador eletro-hidráulico assimétrico acoplado a uma carga suspensa e controlado por uma válvula direcional proporcional. Com o objetivo de testar os limites operacionais do servomecanismo, a pressão de trabalho do circuito é alterada e, resultados relacionados às especificações do projeto de controle, em particular, o tempo de assentamento e erro de regime permanente, são analisados. Em acréscimo, faz-se a comparação entre os resultados interligando a válvula ao atuador nas configurações 4/3 e 3/3, onde se observa que, de acordo com as condições de realização do experimento, ambas apresentam vantagens e desvantagens em termos de desempenho estático e dinâmico. Observou-se durante os experimentos que a variação da pressão tornou mais evidente as diferenças de comportamento devidas às características físicas de cada configuração testada do conjunto válvula e atuador, e que limitações do sistema mecânico, como atrito do atuador, zona morta, perda de carga e histerese da válvula, podem limitar o desempenho do sistema no tocante ao atendimento dos requisitos dos parâmetros de controle. Por fim, foi realizado o projeto do controle por meio de um controlador PD, o qual se mostrou satisfatório no atendimento das especificações de projeto

Estudo comparativo entre técnicas de extração de DNA para o futuro diagnóstico do endossimbionte Wolbachia em Haematobia irritans.

Editores técnicos: João de Mendonça Naime, Caue Ribeiro, Maria Alice Martins, Elaine Cristina Paris, Paulino Ribeiro Villas Boas, Ladislau Marcelino Rabello

MOLYBDENUM CATALYZED ACID PEROXIDE BLEACHING OF EUCALYPTUS KRAFT PULP

Molybdenum catalyzed peroxide bleaching (PMo Stage) consists of pulp treatment with hydrogen peroxide under acidic conditions in the presence of a molybdenum catalyst. Molybdenum is applied in catalytic doses (50-200 mg/kg pulp) and may originate from various sources, including (NH4)6Mo7O24.4H2O, Na2MoO4.2H2O, siliconmolybdate, etc. This work is aimed at optimizing the PMo stage and evaluating its industrial application in the OAZDP sequence. Optimum PMo stage conditions for bleaching eucalyptus pulp were 90 ºC, pH 3.5, 2 h, 0.1 kg/adt Mo and 5 kg/adt H2O2. The PMo stage was more efficient to remove pulp hexenuronic acids than lignin. Its efficiency decreased with increasing pH in the range of 1.5-5.5, while it increased with increasing temperature and peroxide and molybdenum doses. The application of the PMo stage as replacement for the A-stage of the AZDP sequence significantly decreased chlorine dioxide demand. The PMo stage caused a decrease of 20-30% in the generation of organically bound chlorine. The quality parameters of the pulp produced during the PMo stage mill trial were comparable to those obtained with the reference A-stage

Study of infection by Babesia bovis and Anaplasma marginale in dairy water buffaloes in the state of São Paulo.

The aim of this study was to evaluate the prevalence of infection by Babesia bovis and Anaplasma margina/e in dairy water buffaloes infested by ticks on farms, either in exclusive buffalo herds or in in mixed herds along with cattle