ABSTRACT We consider a transmission problem for a string composed by two components: one of them is a viscoelastic material (with viscoelasticity of memory type), and the other is an elastic material (without dissipation effective over this component). Additionally, we consider that in one end is attached a tip load. The main result is that the model is exponentially stable if and only if the memory effect is effective over the string. When there is no memory effect, then there is a lack of exponential stability, but the tip load produces a polynomial rate of decay. That is, the tip load is not strong enough to stabilize exponentially the system, but produces a polynomial rate of decay.

Resumo O objetivo deste estudo foi acompanhar a variação da densidade populacional de Lymnaea columella, hospedeiro intermediário de Fasciola hepatica, em diferentes tipos de coleções hídricas e bebedouros na área do Instituto Federal de Educação, Ciência e Tecnologia do Espírito Santo, na microrregião do Caparaó, município de Alegre, estado do Espírito Santo, Brasil. Foram realizadas coletas mensais em pontos determinados entre áreas de drenagem e bebedouros de animais nos setores de bovinocultura e caprinocultura durante os anos de 2010 a 2013. As médias de temperatura, precipitação e a frequência de exemplares de L. columella foram analisadas graficamente de acordo com a média mensal ao longo do período avaliado. Foram coletados 2.038 moluscos, sendo 1558 de L. columella, espécie predominante em todos os pontos amostrados. A maior média de espécimes observadas para L. columella foi nos anos de 2010 e 2013 (51,0), ocorrendo um decréscimo em 2011 (19,8). A temperatura apresentou média de 23,7°C e precipitação de 141 mm/ano. Picos de precipitação ocorreram em Março (2011, 2013) e Novembro (2012), nestes períodos foi observado aumento populacional de L. columella. Não houve diferença significativa na relação entre as espécimes observadas com as estações do ano (seca-chuvosa), dessa forma, a população de L. columella se mostrou estável, podendo ser encontrada durante todo ano.

Abstract The aim of this study was to monitor the population density of Lymnaea columella, an intermediate host of Fasciola hepatica, in various aquatic habitats and in drinking water in the area of the Instituto Federal de Educação, Ciência e Tecnologia do Espírito Santo, on Caparaó Microregion, municipality of Alegre, state of Espírito Santo, Brazil. Monthly samplings were performed at certain points between drainage areas and drinking water in cattle and goat production systems during the years 2010 to 2013. The mean temperature, precipitation and the frequency of samples of L. columella were analysed graphically according the monthly average during the study period. A total of 2,038 molluscs were collected, 1558 of which were L. columella, that predominated in all sampled points. The highest average of specimens observed for L. columella was in the years 2010 and 2013 (51.0), and occurred decreased in 2011 (19.8). The temperature and precipitation averaged is 23.7 °C and 141 mm/year, respectively. Rainfall peak occurred in March (2011, 2013) and November (2012), during these periods the population of L. columella growth. There was no significant difference in the relationship between the specimens observed with seasons (dry-wet), thus the population of L. columella remained stable and can be found throughout the year.

Soil mictobiota catties out important functions in ecosystems, since it influences growth, mineral nutrition and plant health. Phosphorus (P) is the most limiting nutrient in tropical soils and P-solubilizing microorganisms (PSMs) and the arbuscular mycorrhizal fungi (AMF) are the most important groups of the soil microbial community. The aim of this study was to evaluate the effect of inoculating PSMs and AMF on the development of cashew trees (Anacardium othonianum Rizzini) from the Brazilian Cerrado growing on different substrates. An experiment was carried out in a greenhouse and the experimental design was completely randomized with a factorial 4 × 2 arrangement of treatments: PSMs, AMF, PSMs + AMF and the control. In addition, two substrates were used: a pure one with a sandy loam texture and a mixture of clay loam and clayish textures. Twelve replicates were performed. Data were subjected to an analysis of variance, and means were compared with the Tukey test (p<0.05). The co-inoculation with PSMs and AMF resulted in greater height and shoot dry matter of seedlings compared to isolated inoculations with these organisms. Seedlings increased height and shoot fresh and dry matter when grown in a mixture of substrates (soil with clay loam and clay textures). The use of a mixture of substrates also resulted in a greater symbiotic efficiency of Glomus etunicatum.

La microbiota del suelo desarrolla importantes funciones en los ecosistemas, ya que influye en el crecimiento, la nutrición mineral y la salud de las plantas. El fósforo (P) es el nutrimento más limitante en los suelos tropicales, y los microorganismos solubilizadores de P (MSP) y los hongos micorrízicos arbusculares (HMA) son los grupos más importantes de la comunidad microbiana del suelo. El objetivo de este estudio fue evaluar el efecto de la inoculación de MSP y HMA en el desarrollo de árboles de anacardo (Anacardium othonianum Rizzini) de el Cerrado Brasileño con distintos sustratos. Se realizó un experimento en invernadero y el diseño experimental fue completamente aleatorio con un arreglo factorial de 4 × 2 de los tratamientos: MSP, HMA, MSP+HMA y el control. Además, se usaron dos sustratos: uno puro, con textura franco arenoso, y una mezcla de texturas franco arcillosa y arcillosa. Se realizaron 12 réplicas. Los datos se procesaron con un análisis de varianza y las medias se compararon con la prueba de Tukey (p<0.05). La coinoculación con MSP y HMA resultó en mayor altura y materia seca del vástago de las plántulas comparado con las inoculaciones aisladas con estos organismos. Las plántulas aumentaron su altura y materia húmeda y seca del vástago al cultivarse en una mezcla de sustratos (suelo con texturas franco arcillosa y arcillosa). El uso de una mezcla de sustratos también resultó en una eficiencia simbiótica mayor con Glomus etunicatum.

Avaliou-se o estado nutritivo de jovens plantas de Eucalyptus globulus, num sistema experimental com diferentes opções de gestão de resíduos de abate e de disponibilidade de nutrientes, por análise foliar (teores de N, P, Ca, K e Mg, área foliar, e teores de clorofila e carotenóides) e espectroradiométrica (medidor foliar de clorofila, SPAD502). Os tratamentos foram: remoção dos resíduos de abate (R); como R e aplicação de fertilizantes (RF); como R e sementeira de leguminosas (RL); distribuição dos resíduos de abate na superfície do solo (S); como S seguido e aplicação de fertilizantes (SF); incorporação dos resíduos de abate no solo por intermédio de gradagem (I); como I e aplicação de fertilizantes (IF); como I e com sementeira de leguminosas (IL). As árvores do tratamento I apresentaram maior crescimento do que as dos tratamentos R e S; a aplicação de fertilizantes apenas levou a acréscimo de crescimento nos tratamentos em que os resíduos foram mantidos no sítio (SF e IF). Os teores de N foram no início positivamente afectados pelas leguminosas (tratamentos IL e RL), mas após a aplicação de fertilizantes foram substancialmente mais elevados nos tratamentos IF, RF e SF do que nos outros, sendo a diferença reduzida no período outonal seguinte; semelhante padrão foi observado para os valores de SPAD. Os teores de Ca e Mg por seu turno decresceram substancialmente nos tratamentos correspondentes à aplicação de fertilizantes. Os valores do SPAD correlacionaram-se (P<0,05) com os teores de N, Ca e Mg, bem como com a área foliar específica. O método espectroradiométrico, desde que adequadamente calibrado, mostrou ser uma técnica alternativa para monitorizar o estado de nutrição de jovens plantas de E. globulus.

The nutritional state of young plants of Eucalyptus globulus was evaluated, in different scenarios of harvest residues management and nutrient availability, by foliar (N, Ca, Mg, P and K contents and leaf area, chlorophyll and carotenoids contents) and spectroradiometric analysis (SPAD-502 chlorophyll meter). Treatments were removal of harvest residues (R); as R and fertilizer application (RF); as R and legume seeding (RL); distribution of harvest residues on the soil surface (S); as S and fertilizer application (SF); incorporation of harvest residues into the soil by harrowing (I); as I and fertilizer application (IF); as I and leguminous seeding (IL). Trees of treatment I showed greater growth than those of R and S treatments; the application of fertilizers increased the growth only in treatments where harvest residues were kept in the site (SF and IF). Initially, N contents were positively affected by the leguminous (treatments RL and IL), but, after fertilizer application, the highest N contents were observed in treatments IF, RF and SF compared with the others, the differences being reduced in the next autumn season; a similar trend was observed for values of SPAD. In contrast, contents of Ca and Mg strongly decreased in treatments where fertilizers were applied. SPAD values were correlated (P<0.05) with N, Ca and Mg contents, as well as with specific leaf area. The spectroradiometric technique, since properly calibrated, could be an alternative method to monitor the nutritional state of young plants of E. globulus.

Com o objetivo de se identificarem os fatores de risco associados à presença de infecção por toxoplasmose em rebanhos caprinos no estado do Ceará, Brasil, soros sanguíneos de 2362 caprinos foram testados por meio de ELISA. A prevalência estimada pelo ELISA foi 25,1%. Os fatores de risco identificados nas propriedades foram: idade dos animais, número de gatos, comedouro manufaturado de madeira e ausência de comedouro. Em caprinos com mais de 37 meses de idade o risco de estarem infectados pelo T. gondii foi 2,01 vezes maior (IC 95%; 1,55 - 2,61) que em animais mais jovens. Maior risco de infecção foi observado em fazendas com mais de 10 gatos (OR = 1,73; IC 95% 1,01 - 3,33). Quando a propriedade utilizava comedouros de madeira, o risco de estarem infectados foi também maior (OR = 7.81; IC 95%; 1.66 - 36.67). Animais oriundos de propriedades sem comedouro também apresentaram alto risco de infecção (OR = 5.50; IC 95%; 1,24 - 24,39).

In order to identify possible risk factors for T. gondii infection in goat herds in Ceará, Brazil, 2362 serum samples were tested by ELISA. The serological prevalence was 25.1%. The risk factors identified for Toxoplasma gondii infection in goat herds were age, number of cats, use of wooden feeding troughs and absence of feeding troughs. Goats older than 37 months had 2.01 (CI 95%; 1.55 - 2.61) higher risk of infection than younger animals. Greater risk of infection was observed in farms with more than 10 cats (OR = 1.73; CI 95%; 1.01 - 3.33). The use of wooden feeding troughs represented a high probability of infection (OR = 7.81; CI 95%; 1.66 - 36.67). The lack of feeding troughs also represented a high probability of infection (OR = 5.50; CI 95%; 1.24 - 24.39).

O estudo da quantidade e da atividade da biomassa microbiana pode fornecer subsídios importantes para o planejamento do uso correto da terra, considerando a natureza dinâmica dos microrganismos do solo. Este trabalho objetivou verificar alterações em atributos biológicos indicadores da qualidade do solo na adoção de sistemas de manejo em áreas originalmente sob cerrado nativo, e selecionar os atributos com melhor desempenho em indicar tais alterações. Amostras de solo foram coletadas em três profundidades (0-10, 10-20 e 20-40 cm) em Latossolo Vermelho distrófico típico textura argilosa no município de Morrinhos (GO). Foram selecionadas cinco propriedades agrícolas, baseadas na sua representatividade para a região com relação ao histórico de uso e às características dos sistemas de manejo adotados. Estes consistiram de: cerrado nativo, pastagem, plantio direto, plantio direto com histórico de gradagem superficial, plantio convencional de longa duração e plantio convencional recente após pastagem. O cerrado nativo foi tomado como referência, uma vez que todos os sistemas foram instalados em área originalmente de cerrado. Foram avaliados: carbono da biomassa microbiana (Cmic), respiração basal, quociente metabólico (qCO2) e relação Cmic/CO. Em adição, foram avaliados o carbono orgânico total (CO) e alguns atributos de fertilidade do solo. A adoção dos sistemas agrícolas e da pastagem reduziu os teores de Cmic na camada superficial, em relação ao cerrado nativo. Excetuando o sítio sob cerrado, o maior valor de Cmic foi observado na pastagem e o menor no plantio convencional de longa duração. Não foram observadas diferenças significativas entre os sistemas de manejo para respiração basal e qCO2. O Cmic indicou alterações significativas na instalação de sistemas de manejo em relação ao cerrado nativo e, embora tenha apontado diferenças apenas entre dois dos cinco sistemas cultivados, foi indicativo de maior equilíbrio da microbiota do solo no cerrado.

Due to the dynamic nature of soil microorganisms, the study of microbial biomass quantity and activity can furnish important information for the planning of adequate land use. The objective of this work was to verify alterations in biological attributes of soil quality indicators after the adoption of management systems in originally native cerrado areas, and to select the attributes with the best performance of indicating such alterations. Soil samples were collected at three depths (0-10, 10-20, and 20-40 cm) in a clayey texture, typic Dystrophic Red Latosol (Oxisol) in Morrinhos county, Goiás State. Five farms were chosen, based on their representativeness for the region in relation to their history of use and the characteristics of the adopted management systems. These systems included: native cerrado, pasture, no-till, no-till with a history of superficial harrowing, long-term conventional tillage, and recent conventional tillage following pasture. The native cerrado was considered reference, once all test areas had originally been covered by this vegetation type. The following attributes were evaluated: carbon of microbial biomass (Cmic), basal respiration, metabolic quotient (qCO2) and Cmic/OC ratio. In addition, the total organic carbon (OC) and some soil fertility attributes were evaluated. The introduction of agricultural systems and pasture reduced the Cmic amounts in the surface layer in comparison to the native cerrado. Without considering the site under cerrado, the highest Cmic value was observed in the pasture and the lowest one in the long-term conventional tillage soil. No significant differences in basal respiration and qCO2 values were observed among the management systems. The Cmic indicated significant alterations caused by the implantation of management systems in relation to the native cerrado. Though it had revealed differences only between two of the five cultivated systems, the Cmic was an indicator for a higher microbiota equilibrium in the soil under cerrado.

OBJECTIVE: To identify risk factors associated with Trypanosoma cruzi infections in areas under surveillance in the State of Minas Gerais, Brazil. METHODS:A model using a nested case-control design incorporated within a serological survey of schoolchildren which was employed to evaluate the effectiveness of the Chagas disease control programme. FINDINGS:In a sample of 40 374 schoolchildren (aged 7-14 years) surveyed, 16 children tested positive for T. cruzi antibody (by indirect immunofluorescence and indirect haemagglutination). In the case-control study, each case was randomly matched to three seronegative controls (classroom and age + 1 year). Compared to controls, T. cruzi-seropositive children were more likely to have a seropositive mother (odds ratio (OR) = 6.8; 95% confidence interval (CI) = 0.71-63.9) or a seropositive family member (OR = 8.6; 95% CI = 1.0-75.5). CONCLUSION:Use of the nested case-control model in a sero-epidemiological survey to evaluate risk factors for T. cruzi transmission was adequate for assessing the effectiveness of a Chagas disease control programme.

OBJETIVO: Identificar los factores de riesgo asociados a las infecciones por Trypanosoma cruzi en zonas sometidas a vigilancia en el Estado de Minas Gerais (Brasil). MÉTODOS: Para evaluar la eficacia de un programa de lucha contra la enfermedad de Chagas, se empleó un modelo anidado de casos y testigos incorporado en una encuesta serológica de escolares. RESULTADOS: En la muestra de 40 374 escolares (de 7- 14 años) encuestados, 16 niños dieron positivo para los anticuerpos contra T. cruzi (por inmunofluorescencia indirecta y hemaglutinación indirecta). En el estudio de casos y testigos, cada caso se emparejó al azar con tres testigos seronegativos (de la misma clase y con una diferencia de edad máxima de un año). En comparación con los testigos, los niños seropositivos para T. cruzi presentaban una mayor probabilidad de tener una madre seropositiva (razón de posibilidades (OR) = 6,8; IC95%: 0,71-63,9) o un familiar seropositivo (OR = 8,6; IC95%: 1,0-75,5). CONCLUSIÓN: El uso de un modelo de casos y testigos anidado en una encuesta seroepidemiológica para evaluar los factores de riesgo de transmisión de T. cruzi fue un medio adecuado para determinar la eficacia de un programa de lucha contra la enfermedad de Chagas.

OBJECTIF:Identifier les facteurs de risque associés aux infections par Trypanosoma cruzi dans des zones couvertes par la surveillance dans l’Etat de Minas Gerais (Brésil). MÉTHODES: Un modèle faisant appel à une étude castémoins emboîtée dans une enquête sérologique réalisée sur des écoliers a été utilisé pour évaluer l’efficacité du programme de lutte contre la maladie de Chagas. RÉSULTATS: Dans un échantillon de 40 374 écoliers (âgés de 7 à 14 ans) enquêtés, 16 possédaient des anticorps dirigés contre T. cruzi (détectés par immunofluorescence indirecte et hémagglutination indirecte). Dans l’étude cas-témoins, chaque cas était apparié à 3 témoins séronégatifs choisis par tirage au sort parmi les élèves de leur classe et ayant le même âge à un an prés. Par rapport aux témoins, les enfants ayant une sérologie positive pour T. cruzi avaient une probabilité plus grande d’avoir une mère également positive (odds ratio (OR) = 6,8 ; intervalle de confiance (IC) à 95%: 0,71- 63,9) ou un membre de la famille positif (OR = 8,6 ; IC 95%: 1,0-75,5). CONCLUSION: L’inclusion d’une étude cas-témoins emboîtée dans une enquête sérologique afin de rechercher les facteurs de risque de transmission de T. cruzi était utile pour évaluer l’efficacité d’un programme de lutte contre la maladie de Chagas.

Sexually transmitted diseases (STD) are very frequent in the whole world. Males who do not use a condom during their sexual relations are at great risk. We report cases of STD during six months of observation, among homosexual/bisexual males who participate in the Project Horizonte. There were 16 cases of genital warts, 6 cases of human immunodeficiency virus infection, 24 cases of unspecific urethritis, 28 cases of herpes simplex virus infection, 30 cases of syphilis, 58 cases of gonorrhea and 84 cases of pediculosis. We concluded that a condom must be used in all sexual relations and new counseling techniques are needed, to avoid this situation.

The development in C3H mice of thirteen strains of Trypanosoma cruzi belonging to different zymodemes ans schizodemes was studied. Host mortality, virulence, histiotropism, parasitemia and polymorphism of the parasites were recorded. The strains were grouped into: a) high virulence - causing 100% mortality and characterized by predominance of bery broad trypomastigotes in the bloodstream at the end of infection; b) medium virulence - causing no mortality and with a predominance of broad trypomastigotes; c) low virulence - causing no mortality with blood forms not described due to the very low parasitemia. During 18 months maintenance the parasitemia curves were kept constant for all strains except one. A direct correlation between either zymodeme or schizodeme and experimental biological properties of T. cruzi strains was not found. However, the parasitemia was subpatent and patent for strains from zymodeme C and the others respectively. Furthermore the high virulence seems to be related to one of two shizodemes found within zymodeme B strains. All strains presenting patent parasitemia independent of shizodeme and ymodeme showed a myotropism towards heart and skeletal muscle with varible inflammatory intensity. The present study confirmed the heterogeneity found by isoenzyme and K-DNA patterns among the strains of T. cruzi isolated from chagasic patients in Bambuí, Minas Gerais State, Brasil.