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

Seleção do coqueiro anão verde para produção de polpa.

bitstream/item/90698/1/cot-62-2.pdfISSN 1678-1937

Development Of A Balb/c Mouse Model Of Helicobacter Pylori Infection With Fresh And Frozen Bacteria.

An experimental model for H. pylori infection was established by intragastrically challenging BALB/c mice with 1 ml (10(8) CFU/ml) of suspension for two consecutive days. Animals were divided into three groups. GA: mice inoculated with fresh bacteria; GB: mice inoculated with frozen bacteria, and GC: mice inoculated with brucella broth (control group). Animals were killed at 7, 14, 21, 28, 35 and 60 days pi and fragments of stomach and duodenum were collected, paraffin embedded and stained by hematoxylin-eosin and Giemsa. The results showed that challenged mice exhibited mild duodenitis and gastritis. In group GA, infiltration in the duodenum was lymphoplasmacytic until day 35; in group GB, it was lymphomonocytic for 60 days pi. In the stomach, H. pylori induced lymphomonocytic infiltration that was present from days 7 to 60 in group GA. In group GB, it was only present from days 14 to 35. In conclusion, our data suggested that freezing altered pathogenic properties of H. pylori and probably inhibited expression of bacterial antigens and consequently the establishment and maintenance of infection. Although the animals developed mild duodenitis and gastritis, the BALB/c mouse is not susceptible to developing peptic ulcers during H. pylori infection.38101-

Análise in silico de aquaporinas potencialmente envolvidas com o estresse hídrico nas interações café- e citros-Xylella fastidiosa.

No Brasil, um dos importantes problemas enfrentados por produtores de café e citros envolve os danos causados pela bactéria Xylella fastidiosa. Esta bactéria causa o entupimento dos vasos do xilema e impede a passagem de água e nutrientes, o que causa uma condição biológica de estresse hídrico. Os genomas de citros e café têm sido investigados funcionalmente e várias seqüências expressas (ESTs) foram identificadas a partir de diversas condições biológicas. Bibliotecas de EST utilizando folhas e ramos infectados com X. fastidiosa foram construídas em citros e café, respectivamente. A análise in silico das ESTs nesses tecidos revelou genes comuns expressos em ambas as culturas. Alguns destes genes codificam para proteínas relacionados com a resposta de estresse hídrico, incluindo a aquaporina, a ?drought-induced protein Di19-like protein DIP? e a ?fiber protein Fb2?. Estes genes foram analisados neste estudo

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

Avaliação de sorgo biomassa visando a produção de bioenergia.

O objetivo deste trabalho foi caracterizar o potencial agronômico de linhagens de sorgo biomassa visando à geração de energia. O ensaio foi implantado no ano agrícola de 2013/2014, em Sete Lagoas-MG, com semeadura realizada no final do mês de janeiro de 2014. O delineamento experimental foi em blocos casualizados, com 3 repetições e 10 genótipos de sorgo. As parcelas experimentais foram constituídas por 2 fileiras de cinco metros, espaçadas de 0,70m. As avaliações foram feitas em uma fileira central de cada parcela e as características avaliadas foram florescimento, altura de plantas (AP), produção de massa verde total (PMV), produção de massa seca total (PMS). Os dados de PMV e PMS foram convertidos para t.ha-1. Híbridos de sorgo biomassa, sensíveis ao fotoperíodo, apresentaram ciclo médio de seis meses e porte alto (superior a 4m) que refletiu em alto potencial produtivo de biomass