RESUMO Neste trabalho descreve-se de maneira detalhada, tanto analíticamente quanto numericamente, a detecção e a classificação de pontos críticos na trajetória primária de equilíbrio de sistemas estruturais. Utiliza-se a Formulação Lagrangiana Total para descrever a cinemática de um elemento de barra bi-articulado 3D. Através desta formulação obtém-se o vetor de forças internas e a matriz de rigidez tangente que levam em conta os efeitos da não linearidade geométrica. Assume-se um modelo constitutivo linear elástico para o estado uniaxial de tensão-deformação, usando a deformação de Green-Lagrange e a tensão axial do segundo tensor de Piola-Kirchhoff que são energéticamente conjugados. Como estudo de caso apresenta-se um sistema físico simples com três graus de liberdades composto por duas barras bi-articuladas 3D e uma mola linear. Por fim, determinam-se as condições geométricas e físicas para a coalescência entre os pontos limites e de bifurcação.

ABSTRACT Using both analytical and numerical approaches, this paper describes in detail the detection and classification of critical points in the primary equilibrium path of structural systems. The Total Lagrangian formulation is employed to describe the kinematics of a biarticulated prismatic 3D bar element. With this formulation, the internal force vector and the tangent stiffness matrix including the geometric nonlinearity effects are obtained. An elastic linear constitutive model is assumed for the uniaxial stress-strain state. Such model uses the Green-Lagrange strain tensor and the second Piola-Kirchhoff axial stress tensor which are energetically conjugate tensors. As a study case, the article presents a simple structural system with three degrees of freedom made up of two bi-articulated prismatic 3D bars and a linear spring. Finally, the geometrical and physical conditions for the coalescence between limit and bifurcation points are determined.

Avaliaram-se o consumo e o desempenho de ovinos alimentados com silagens de cana-de-açúcar tratadas com óxido de cálcio (CaO) e cloreto de sódio (NaCl). Utilizaram-se sete tratamentos: controle (silagem sem aditivo), silagens com 0,5; 1,0 e 1,5% de CaO e silagens com 0,5; 1,0 e 2,0% de NaCl, com quatro repetições. Os animais consumiram maior quantidade de matéria seca e de nutrientes digestíveis totais quando se adicionou 0,5% de NaCl ou ainda 1,0 e 1,5% de CaO. Quanto à fibra em detergente neutro e à proteína bruta, observou-se maior consumo quando se adicionou 0,5% de NaCl ou 1,0% de CaO. Não foi observado efeito da dieta sobre o ganho médio diário de peso. A adição de 0,5% de cloreto de sódio e 1,0% de óxido de cálcio à silagem de cana-de-açúcar resultou em aumento no consumo e melhora no desempenho de ovinos.

The intake and performance of lambs fed with sugarcane silages treated with whitewash and chloride sodium were evaluated. Seven treatments were used: untreated silage (control); silages treated with 0.5; 1.0 and 1.5% of CaO (whitewash); and silages treated with 0.5; 1.0 and 2.0% of NaCl, with four replicates per treatment. The animals were fed a higher amount of dry matter and total digestible nutrients when the sugarcane silages were treated with 0.5% of NaCl, 1.0 and 1.5% of CaO. The intake of neutral detergent fiber and crude protein increased when the lambs were fed silages treated with 0.5% of NaCl and 1.0% of CaO. The average daily gain did not differ among treatments. The inclusion of 0.5% of sodium chloride and 1.0% of whitewash in sugarcane silages increased the intake and improved the performance of lambs.

O experimento in vitro foi realizado para avaliar a ação do extrato etanólico das folhas do melão-de-São-Caetano (Momordica charantia L.) sobre o desenvolvimento de ovos e motilidade de larvas de nematóides gastrintestinais de caprinos. As larvas foram obtidas de coproculturas e a recuperação de ovos foi feita pela técnica dos quatro tamises, a partir de fezes de caprinos naturalmente infectados da mesorregião do Sertão Paraibano. O extrato foi utilizado nas diluições de 50; 25; 12,5; 6,25 e 3,12% para ambos os testes e como controle positivo e para controle negativo, utilizou-se água destilada estéril. As placas foram examinadas ao microscópio óptico para contagem dos ovos em desenvolvimento e larvas móveis e imóveis, após 24, 48 e 72 horas de incubação. As concentrações do extrato etanólico de M. charantia e os tratamentos controle negativo e positivo diferiram quanto ao número de ovos inviáveis. No teste de motilidade larval as concentrações acima de 12% apresentaram médias significativas quanto ao número de larvas inviáveis. Nas condições ensaiadas a M. charantia apresentou atividade ovicida e larvicida.

The experiment in vitro was performed to evaluate the action of the ethanolic extract of "melão de São Caetano" (Momordica charantia L.) leaves on the development of eggs and motility of larvae of gastrointestinal nematodes from goats. The nematode larvae were obtained from coproculture and the recovery of eggs was done in sieves, from feces of naturally infected goats from the Mesoregion of Paraíba State. The extract was used at the dilutions of 50, 25, 12.5, 6.25 and 3.12% for both tests and as positive control; for negative control, sterile distilled water was used. The plates were examined under optical microscope to count the eggs in development and mobile larvae after 24, 48 and 72 h of incubation. The concentrations of M. charantia ethanolic extract and the negative and positive controls differed as to the number of eggs that were not viable. In the larval motility test, concentrations higher than 12% had significant means as to the number of larvae that were not viable. Under the tested conditions, M. charantia showed larvicidal and ovicidal activity.

The aim of the present study was to determine the ventilation/perfusion ratio that contributes to hypoxemia in pulmonary embolism by analyzing blood gases and volumetric capnography in a model of experimental acute pulmonary embolism. Pulmonary embolization with autologous blood clots was induced in seven pigs weighing 24.00 ± 0.6 kg, anesthetized and mechanically ventilated. Significant changes occurred from baseline to 20 min after embolization, such as reduction in oxygen partial pressures in arterial blood (from 87.71 ± 8.64 to 39.14 ± 6.77 mmHg) and alveolar air (from 92.97 ± 2.14 to 63.91 ± 8.27 mmHg). The effective alveolar ventilation exhibited a significant reduction (from 199.62 ± 42.01 to 84.34 ± 44.13) consistent with the fall in alveolar gas volume that effectively participated in gas exchange. The relation between the alveolar ventilation that effectively participated in gas exchange and cardiac output (V Aeff/Q ratio) also presented a significant reduction after embolization (from 0.96 ± 0.34 to 0.33 ± 0.17 fraction). The carbon dioxide partial pressure increased significantly in arterial blood (from 37.51 ± 1.71 to 60.76 ± 6.62 mmHg), but decreased significantly in exhaled air at the end of the respiratory cycle (from 35.57 ± 1.22 to 23.15 ± 8.24 mmHg). Exhaled air at the end of the respiratory cycle returned to baseline values 40 min after embolism. The arterial to alveolar carbon dioxide gradient increased significantly (from 1.94 ± 1.36 to 37.61 ± 12.79 mmHg), as also did the calculated alveolar (from 56.38 ± 22.47 to 178.09 ± 37.46 mL) and physiological (from 0.37 ± 0.05 to 0.75 ± 0.10 fraction) dead spaces. Based on our data, we conclude that the severe arterial hypoxemia observed in this experimental model may be attributed to the reduction of the V Aeff/Q ratio. We were also able to demonstrate that V Aeff/Q progressively improves after embolization, a fact attributed to the alveolar ventilation redistribution induced by hypocapnic bronchoconstriction.

Dengue hemorrhagic fever (DHF) is a severe febrile disease, characterized by abnormalities in hemostasis and increased vascular permeability, which in some cases results in hypovolemic shock syndrome and in dengue shock syndrome. The clinical features of DHF include plasma leakage, bleeding tendency and liver involvement. We studied the histopathological features of a fatal case of dengue-3 virus infection. The patient, a 63-year old male, presented with an acute onset of severe headache, myalgia and maculopapular rash. Tissue fragments (liver, spleen, lung, heart, kidney and lymph nodes) were collected for light microscopy studies and stained by standard methods. Histopathology revealed severe tissue damage, caused by intense hemorrhage, interstitial edema and inflammation. Some tissue sections were also processed with the immunoperoxidase reaction, which revealed the dengue viral antigen. Dengue-3 virus was isolated and identified with electron microscopy in a C6/36 cell culture inoculated with the patient's serum. Viral particles were detected in the infected cell culture.