Mode-coupling approach to near-cuspidal patterns in planar fluid flows.

We investigate the evolution of the interface separating two Newtonian fluids of different viscosities in two-dimensional Stokes flow driven by suction or injection. A second-order, mode-coupling theory is used to explore key morphological aspects of the emerging interfacial patterns in the stage of the flow that bridges the purely linear and fully nonlinear regimes. In the linear regime, our analysis reveals that an injection-driven expanding interface is stable, while a contracting motion driven by suction is unstable. Moreover, we find that the linear growth rate associated with this suction-driven instability is independent of the viscosity contrast between the fluids. However, second-order results tell a different story, and show that the viscosity contrast is crucial in determining the morphology of the interface. Our theoretical description is applicable to the entire range of viscosity contrasts, and provides insights on the formation of near-cusp pattern-forming structures. Reproduction of fully nonlinear, n-fold symmetric near-cuspidal shapes previously obtained through conformal mapping techniques substantiates the validity of our mode-coupling approach.

Isolation and characterization of the aerobic bacterial microbiota of the esophagus and its probable association with obstructive caseous lesions in green turtles (Chelonia mydas) / Isolamento e caracterização da microbiota bacteriana aeróbia do esôfago e sua provável associação com lesões caseosas obstrutivas em tartarugas-verdes (Chelonia mydas)

Caseous lesions in the esophagus of green turtles (Chelonia mydas) from the coast of Brazil have been described as obstructive lesions and can lead to the death of these animals. However, their etiology remains unclear. The aim of this study was to isolate and characterize the aerobic bacterial microbiota of the esophagus of green turtles (C. mydas) from the Brazilian coast and to verify its possible participation in the etiology of caseous lesions. For this, 42 animals were used, 33 alive and healthy and 9 naturally dead that had esophageal lesions confirmed by necropsy, from Anchieta and Piúma beaches, Espírito Santo. Microbiological tests and morphological evaluation of the esophagus were performed. We isolated 14 different bacterial agents from healthy animal samples, with the prevalence of Pseudomonas aeruginosa being (36.36%), Staphylococcus aureus (33.33%), Aeromonas hydrophila (27.27%), and Vibrio alginolyticus (24.24%). In dead animals, only three distinct agents were isolated: S. aureus (50.00%), A. hydrophila (25.00%), and V. alginolyticus (25.00%). Morphological evaluation revealed a predominance of the lesions at the gastroesophageal junction, with multifocal-to-coalescent distribution, discrete intensity, and absence of obstruction. Ulcerations and caseous exudates, inflammatory infiltrates, parasitic eggs, and giant foreign body cells were also observed as well as bacterial lumps and glandular alterations, such as necrosis, adenitis, and fragments of adult parasites. There was a positive correlation between bacterial lumps and microbiological culture and a negative correlation between bacterial lumps and microbiological culture with parasites. Thus, it was noted that the esophageal aerobic microbiota of C. mydas was predominantly composed of Gram-negative bacteria such as P. aeruginosa, A. hydrophila, and V. alginolyticus, in addition to several enterobacteria and Gram-positive bacteria, such as S. aureus. These agents are opportunists and may be involved in the etiology of caseous esophagitis in association with other pathogens as co-factors working in association or, even in a secondary way.(AU)

A ocorrência de lesão caseosa no esôfago de tartarugas-verdes (Chelonia mydas) da costa do Brasil tem sido descrita como de caráter obstrutivo e pode causar a morte dos animais. No entanto, sua etiologia permanece pouco esclarecida. Objetivou-se isolar e caracterizar a microbiota aeróbica esofágica das tartarugas-verdes (C. mydas) da costa brasileira e verificar sua possível participação na etiologia das lesões caseosas. Foram utilizados 42 animais, 33 vivos e hígidos e nove mortos naturalmente que apresentavam lesão esofágica confirmada pela necropsia, provenientes de Anchieta e Piúma, Espírito Santo, nos quais foram feitos testes microbiológicos e avaliação morfológica do esôfago. Foram isolados 14 agentes bacterianos diferentes nas amostras de animais saudáveis, com prevalência de Pseudomonas aeruginosa (36,36%), Staphylococcus aureus (33,33%), Aeromonas hydrophila (27,27%) e Vibrio alginolyticus (24,24%). Nos animais mortos, foram isolados apenas três agentes distintos: S. aureus (50,00%), A. hydrophila (25,00%) e V. alginolyticus (25,00%). A avaliação morfológica revelou predominância da lesão em junção gastroesofágica, com distribuição multifocal a coalescente, intensidade discreta e ausência de obstrução. Observou-se ainda ulceração e exsudato caseoso, infiltrado inflamatório, ovos de parasitos e células gigantes do tipo corpo estranho, além de grumos bacterianos e de alterações glandulares, como necrose, adenite e fragmentos de parasitos adultos. Houve correlação positiva dos grumos bacterianos com cultivo microbiológico e negativa dos grumos bacterianos e cultivo microbiológico com parasitos. Assim, nota-se que a microbiota esofágica aeróbica de C. mydas é constituída predominantemente por bactérias Gram-negativas como P. aeruginosa, A. hydrophila e V. alginolyticus, além de diversas enterobatérias e por Gram-positivas, como S. aureus. Esses agentes são oportunistas e podem estar envolvidos na etiologia da esofagite caseosa em associação a outros patógenos como co-fatores agindo em associação, ou mesmo, por via de infecção secundária.(AU)

Wrinkling and folding patterns in a confined ferrofluid droplet with an elastic interface.

A thin elastic membrane lying on a fluid substrate deviates from its flat geometry on lateral compression. The compressed membrane folds and wrinkles into many distinct morphologies. We study a magnetoelastic variant of such a problem where a viscous ferrofluid, surrounded by a nonmagnetic fluid, is subjected to a radial magnetic field in a Hele-Shaw cell. Elasticity comes into play when the fluids are brought into contact, and due to a chemical reaction, the interface separating them becomes a gel-like elastic layer. A perturbative linear stability theory is used to investigate how the combined action of magnetic and elastic forces can lead to the development of smooth, low-amplitude, sinusoidal wrinkles at the elastic interface. In addition, a nonperturbative vortex sheet approach is employed to examine the emergence of highly nonlinear, magnetically driven, wrinkling and folding equilibrium shape structures. A connection between the magnetoelastic shape solutions induced by a radial magnetic field and those produced by nonmagnetic means through centrifugal forces is also discussed.

Elastic fingering in rotating Hele-Shaw flows.

The centrifugally driven viscous fingering problem arises when two immiscible fluids of different densities flow in a rotating Hele-Shaw cell. In this conventional setting an interplay between capillary and centrifugal forces makes the fluid-fluid interface unstable, leading to the formation of fingered structures that compete dynamically and reach different lengths. In this context, it is known that finger competition is very sensitive to changes in the viscosity contrast between the fluids. We study a variant of such a rotating flow problem where the fluids react and produce a gellike phase at their separating boundary. This interface is assumed to be elastic, presenting a curvature-dependent bending rigidity. A perturbative weakly nonlinear approach is used to investigate how the elastic nature of the interface affects finger competition events. Our results unveil a very different dynamic scenario, in which finger length variability is not regulated by the viscosity contrast, but rather determined by two controlling quantities: a characteristic radius and a rigidity fraction parameter. By properly tuning these quantities one can describe a whole range of finger competition behaviors even if the viscosity contrast is kept unchanged.

Stationary patterns in centrifugally driven interfacial elastic fingering.

A vortex sheet formalism is used to search for equilibrium shapes in the centrifugally driven interfacial elastic fingering problem. We study the development of interfacial instabilities when a viscous fluid surrounded by another of smaller density flows in the confined environment of a rotating Hele-Shaw cell. The peculiarity of the situation is associated to the fact that, due to a chemical reaction, the two-fluid boundary becomes an elastic layer. The interplay between centrifugal and elastic forces leads to the formation of a rich variety of stationary shapes. Visually striking equilibrium morphologies are obtained from the numerical solution of a nonlinear differential equation for the interface curvature (the shape equation), determined by a zero vorticity condition. Classification of the various families of shapes is made via two dimensionless parameters: an effective bending rigidity (ratio of elastic to centrifugal effects) and a geometrical radius of gyration.

Interfacial elastic fingering in Hele-Shaw cells: a weakly nonlinear study.

We study a variant of the classic viscous fingering instability in Hele-Shaw cells where the interface separating the fluids is elastic, and presents a curvature-dependent bending rigidity. By employing a second-order mode-coupling approach we investigate how the elastic nature of the interface influences the morphology of emerging interfacial patterns. This is done by focusing our attention on a conventionally stable situation in which the fluids involved have the same viscosity. In this framework, we show that the inclusion of nonlinear effects plays a crucial role in inducing sizable interfacial instabilities, as well as in determining the ultimate shape of the pattern-forming structures. Particularly, we have found that the emergence of either narrow or wide fingers can be regulated by tuning a rigidity fraction parameter. Our weakly nonlinear findings reinforce the importance of the so-called curvature weakening effect, which favors the development of fingers in regions of lower rigidity.

[Immunization with synthetic peptide anti-tick Rhipicephalus (Boophilus) microplus SBm7462 via mucosal routes]. / Imunização com o peptídeo sintético anti carrapato Rhipicephalus (Boophilus) microplus SBM7462® por vias de mucosa.

The mucosal immunization consists on antigen administration in these surfaces it is a not invasive method, inductor of local and systemic immune response. This work evaluated the immune response of the synthetic vaccine anti-tick Rhipicephalus (Boophilus) microplus SBm7462®, via oral and nasal routes. Were used 60 BALB/c mice, divided in three groups of 20 animals each (I: oral immunization; II: nasal immunization; III: animals not immunized). Nine and 15 days after the first and the second immunization was collected, separately for each group, T cells from the immunized animals, cultivating them per 10 days. After the incubation, were determined the percentage of cellular viability and the specific nature of this T cells, which had held as memory T cell. The averages of T cell SBm7462-reagents had been submitted to the analysis of variance and comparison for Tukey test, 5% of probability. Group II presented higher cellular proliferation "in vitro". For ELISA test, were positive only two animals in group I and eight in group II. The oral and nasal routs alternatively viable for immunization with the synthetic peptide SBm7462®, however require greater number of doses to induce responses with high levels of immunoglobulins.

[Molecular analysis of the antigenic sequence (SBm7462®) from Bm86 of the Rhipicephalus (Boophilus) microplus and similarity with Rhipicephalus sanguineus and Hyalomma anatolicum anatolicum]. / Análise molecular da sequência antigênica (SBm7462®) da BM86 doRhipicephalus (Boophilus) microplus E similaridade com Rhipicephalussanguineus E Hyalomma anatolicum anatolicum

The vaccination represents optimum method evaluated with effective cost to prevent economic losses and to increase the duration and quality of life of the production animals. . Diverse vaccines are produced from the intestinal protein Bm86 of the Rhipicephalus. (B.) microplus. The knowledge of the conservation of the gene bm86 is very important to evaluate the vaccine efficiency and the possibility of reaction crossed between different species of ticks. Samples of R. (B.) microplus come from different localities had been sequenced. The analyses of multiple alignments of the sequences had been made through the BioEdit program 7.0.5.3 version and the verification of polymorphism for visual inspection. In this work the alignment of all was become fulfilled sequences using itself BLAST in the search for similarity. Similarity was observed enters the sequenced fragments of R. (B.) microplus with the sequence of the protein Rs86 de Rhipicephalus sanguineus and with protein HA98 of the tick Hyalomma anatolicum anatolicum. The results give molecular support to synthetic the vaccine use based in the gene bm86 (SBm7462®) to be used in different species of ticks.

[Elaboration and evaluation of a candidate to the DNA vaccine using synthetic genes derived from the peptídeo SBm7462 against the carrapato Rhiphicephalus (Boophilus) microplus]. / Elaboração E avaliação de um candidato à vacina de DNA, utilizando-se genes sintéticos derivados do peptídeo SBm7462contra o carrapato Rhiphicephalus (Boophilus) microplus.

Rhiphicephalus (Boophilus) microplus is one of the most important arthropods in veterinary medicine due economic losses and health problems caused in cattle production. The vaccination represents optimum method evaluated with effective cost to prevent economic losses and to increase the duration and quality of life of the production animals. A synthetic peptide, SBm 7462, derived from Bm86, has been shown great results in control of ticks. The construction and synthesis of one nucleotide sequence based on this peptide might be useful for design a DNA vaccine that has many advances than peptide vaccine. A gene, called seq1, was constructed with a three repetition of nucleotide sequence of SBm 7462. It was cloned into a pCIneo vector expression in mammals and injected in BALB/c mouse. When mice were inoculated with the expression cassette they did not response in ELISA. They elevated antibody titles only when vaccinated with the synthetic peptide SBm7462®. And, the best titles of immunoglobulins were seen when the SBm7462® was administered subcutaneously.