96 resultados para Tomas Rivera


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Objective: This research presents the construction of an attributional questionnaire concerning the different parental models and factors that are involved in family interactions. Method: A mixed methodology was used as a foundation to develop items and respective pilots that allowed checking the validity and internal consistency of the instrument using expert judgment. Results: An instrument of 36 statements was organized into 12 categories to explore the parental models according to the following factors: parental models, breeding patterns, attachment bonds and guidelines for success, and promoted inside family contexts. Analyzing these factors contributes to the children’s development within the familiar frown, and the opportunity for socio-educational intervention. Conclusion: It is assumed that the family context is as decisive as the school context; therefore, exploring the nature of parental models is required to understand the features and influences that contribute to the development of young people in any social context.





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The soil water available to crops is defined by specific values of water potential limits. Underlying the estimation of hydro-physical limits, identified as permanent wilting point (PWP) and field capacity (FC), is the selection of a suitable method based on a multi-criteria analysis that is not always clear and defined. In this kind of analysis, the time required for measurements must be taken into consideration as well as other external measurement factors, e.g., the reliability and suitability of the study area, measurement uncertainty, cost, effort and labour invested. In this paper, the efficiency of different methods for determining hydro-physical limits is evaluated by using indices that allow for the calculation of efficiency in terms of effort and cost. The analysis evaluates both direct determination methods (pressure plate - PP and water activity meter - WAM) and indirect estimation methods (pedotransfer functions - PTFs). The PTFs must be validated for the area of interest before use, but the time and cost associated with this validation are not included in the cost of analysis. Compared to the other methods, the combined use of PP and WAM to determine hydro-physical limits differs significantly in time and cost required and quality of information. For direct methods, increasing sample size significantly reduces cost and time. This paper assesses the effectiveness of combining a general analysis based on efficiency indices and more specific analyses based on the different influencing factors, which were considered separately so as not to mask potential benefits or drawbacks that are not evidenced in efficiency estimation.

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ABSTRACT Trichoderma species are non-pathogenic microorganisms that protect against fungal diseases and contribute to increased crop yields. However, not all Trichoderma species have the same effects on crop or a pathogen, whereby the characterization and identification of strains at the species level is the first step in the use of a microorganism. The aim of this study was the identification – at species level – of five strains of Trichoderma isolated from soil samples obtained from garlic and onion fields located in Costa Rica, through the analysis of the ITS1, 5.8S, and ITS2 ribosomal RNA regions; as well as the determination of their individual antagonistic ability over S. cepivorum Berkeley. In order to distinguish the strains, the amplified products were analyzed using MEGA v6.0 software, calculating the genetic distances through the Tamura-Nei model and building the phylogenetic tree using the Maximum Likelihood method. We established that the evaluated strains belonged to the species T. harzianum and T. asperellum; however it was not possible to identify one of the analyzed strains based on the species criterion. To evaluate their antagonistic ability, the dual culture technique, Bell’s scale, and the percentage inhibition of radial growth (PIRG) were used, evidencing that one of the T. asperellum isolates presented the best yields under standard, solid fermentation conditions.

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O objetivo deste trabalho foi isolar bactérias ácido-lácticas do intestino de tilápias-do-nilo, e avaliar seu potencial probiótico. Foram isoladas cepas de bactérias ácido-lácticas, e foi avaliada a inibição aos patógenos in vitro. As cepas com os melhores resultados foram identificadas e utilizadas no experimento de colonização do trato intestinal de tilápias-do-nilo, via suplementação na dieta, em delineamento inteiramente ao acaso, com três tratamentos e quatro repetições. Foram avaliados: o total de bactérias, as bactérias ácido-lácticas, Vibrio ssp. e Pseudomonas ssp. A cepa com melhor resultado foi utilizada na infecção experimental, em delineamento inteiramente ao acaso, em esquema fatorial 2x3: dieta suplementada com a cepa e dieta-controle; e os peixes não submetidos à injeção, peixes submetidos à injeção de solução salina e à injeção de Enterococcus durans, com três repetições. Foram avaliados os parâmetros hematológicos. As duas cepas identificadas foram: Lactobacillus plantarum e Lactobacillus brevis, que colonizaram o trato intestinal de tilápias, contudo L. plantarum teve menor número total de bactérias e de Pseudomonas ssp. Foi observado maior número total de eritrócitos, trombócitos, leucócitos, linfócitos, neutrófilos e monócitos, em peixes alimentados com L. plantarum e submetidos à injeção de E. durans. O L. plantarum tem efeito probiótico e melhora o sistema imune das tilápias.

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El objetivo de este trabajo fue evaluar la influencia de la fertilización mineral nitrogenada, después de la poda del cafeto robusta, sobre la productividad del cultivo y algunos indicadores químicos (pH, materia orgánica) y microbiológicos (respiración biológica y nitrificación) de dos Cambisoles en Tercer Frente, Santiago de Cuba y La Alcarraza, Holguín, durante los años 2003-2007. Se estudió la respuesta a dosis crecientes de nitrógeno (0 hasta 400 kg ha-1), en presencia de un fondo fijo de P (50 kg ha-1) y K (160 kg ha-1), en un diseño experimental de bloques al azar, con cuatro réplicas. Para productividades entre 0,50 y 0,84 Mg ha-1 de café, son suficientes 75 kg ha-1 de N. Aplicaciones de 100 kg ha-1 de N permitieron productividades de 1,22 a 1,25 Mg ha-1de café. Con dosis de 153 kg ha-1 de N, se logran producciones de 1,80 Mg ha-1 de café, mientras que para productividades superiores a 2 Mg ha-1 se necesita aplicar 200 kg ha-1 en ambos suelos. Se encontró un incremento importante en las productividades del cafeto por cada quilogramo de N aplicado, que osciló entre 2,13 y 7,80. Las dosis propuestas por sitio no afectaron la actividad microbiana y la materia orgánica de los suelos. Se encontró disminución del pH del suelo respecto a su estado inicial.

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O objetivo deste trabalho foi avaliar a assimilação metabólica de nitrogênio em plântulas de seringueira cultivadas na presença de nitrato ou de amônio, por meio da quantificação da atividade das enzimas redutase do nitrato (RN), glutamina sintetase (GS), glutamato sintase (GOGAT) e glutamato desidrogenase (GDH). Os seguintes tratamentos foram avaliados: fontes de N - controle, sem aplicação de N; amônio a 8 mmol L-1; e nitrato a 8 mmol L-1 - e tempos de exposição - 0 e 27 dias -, em arranjo fatorial 3x2, no delineamento inteiramente casualizado, com quatro repetições. A forma amoniacal promoveu maior assimilação metabólica de N, o que resultou em maior acúmulo de aminoácidos. A assimilação, tanto da forma nítrica quanto da amoniacal, aconteceu principalmente via GS/GOGAT; parte do N nítrico é assimilado nas raízes, com pequena participação da GDH, e parte é translocada para outros órgãos. O N amoniacal é totalmente assimilado nas raízes, com significativa participação da GDH. Nas folhas, a GS participa tanto da assimilação primária como da reassimilação do amônio fotorrespirado, independentemente da fonte nitrogenada, enquanto a enzima GDH tem papel secundário, independentemente da fonte ou do tempo de exposição. A atividade da RN in vitro é detectada somente em raízes e caules.

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O objetivo deste trabalho foi determinar a associação genética entre escores visuais de conformação e as características de ganho de peso médio diário e de velocidade de crescimento em bovinos da raça Angus à desmama e ao sobreano. Os componentes de covariância foram estimados por modelo animal de análise tetracaracterística, com uso do método de inferência bayesiana, tendo-se assumido o modelo linear para: ganho de peso médio diário do nascimento à desmama (GMD) e da desmama ao sobreano (GMS); e velocidade de ganho de peso do nascimento à desmama (VD) e da desmama ao sobreano (VS). Um modelo não linear (de limiar) foi utilizado para os escores de conformação à desmama (CD) e ao sobreano (CS). As médias a posteriori, para a herdabilidade direta, foram: 0,12±0,023 (CD), 0,15±0,020 (GMD), 0,15±0,024 (VD), 0,17±0,020 (CS), 0,17±0,023(GMS), e 0,17±0,023 (VS). A correlação genética variou de -0,09±0,11 a 0,60±0,06, entre os escores CD e CS e as características de ganho médio diário de peso e velocidade de ganho de peso. A correlação entre CD e CS foi 0,52±0,089. A seleção direta para escores visuais de conformação, ganho médio diário e velocidade de ganho responde de forma lenta à seleção, tanto à desmama como ao sobreano.

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O objetivo deste trabalho foi avaliar a fauna parasitária dos peixes híbridos cachapinta (Pseudoplatystoma corruscans macho x P. reticulatum fêmea) e jundiara (Leiarius marmoratus macho x P. reticulatum fêmea) no período de larvicultura. Um total de 315 animais, 126 híbridos jundiara e 189 híbridos cachapinta, foram examinados de acordo com o estágio de desenvolvimento: larvas, pós-larvas e alevinos. Larvas e pós-larvas foram prensadas entre lâmina e lamínula e observadas sob microscopia óptica. Os alevinos foram observados externamente em estereomicroscópio e necropsiados para avaliação interna dos órgãos. Foram aferidos os parâmetros de qualidade de água em todas as fases de cultivo. O exame parasitológico revelou a presença dos protozoários Epistylis sp. e Trichodina sp., no tegumento e nas brânquias, Ichthyophthirius multifiliis no tegumento, dos helmintos Monogenea nas brânquias, e das metacercárias de digenéticos em brânquias, baço, rins, fígado e intestino, em ambos os híbridos analisados. Os parasitos Epystilis sp., Trichodina sp. e metacercária de digenéticos ocorrem com maior frequência nos dois híbridos, nas fases de pós-larvas e alevinos. Há maior prevalência e diversidade de parasitos na fase de alevinagem dos híbridos estudados.

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O objetivo deste trabalho foi descrever a fauna parasitária de cachara (Pseudoplatystoma reticulatum) cultivado em tanque-rede, no rio Paraguai. Dez peixes com peso médio de 598,0±81,3 g e comprimento total médio de 38,6±1,6 cm foram examinados. Todos os peixes necropsiados apresentaram infestação por pelo menos duas espécies de parasitos. Entre os parasitos, foram encontrados Ichthyophthirius multifiliis (Ciliophora), Myxobolus sp. e Henneguya sp. (Myxozoa), Monogenoidea, Choanoscolex abscissus e Nominoscolex sudobim (Cestoda), Dolops carvalhoi (Crustacea) e Digenea. O protozoário Ichthyophthirius multifiliis foi o parasito com maior prevalência.

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Objective: The present study was aimed at evaluating the viability of replacing 18F with 99mTc in dose calibrator linearity testing. Materials and Methods: The test was performed with sources of 99mTc (62 GBq) and 18F (12 GBq) whose activities were measured up to values lower than 1 MBq. Ratios and deviations between experimental and theoretical 99mTc and 18F sources activities were calculated and subsequently compared. Results: Mean deviations between experimental and theoretical 99mTc and 18F sources activities were 0.56 (± 1.79)% and 0.92 (± 1.19)%, respectively. The mean ratio between activities indicated by the device for the 99mTc source as measured with the equipment pre-calibrated to measure 99mTc and 18F was 3.42 (± 0.06), and for the 18F source this ratio was 3.39 (± 0.05), values considered constant over the measurement time. Conclusion: The results of the linearity test using 99mTc were compatible with those obtained with the 18F source, indicating the viability of utilizing both radioisotopes in dose calibrator linearity testing. Such information in association with the high potential of radiation exposure and costs involved in 18F acquisition suggest 99mTc as the element of choice to perform dose calibrator linearity tests in centers that use 18F, without any detriment to the procedure as well as to the quality of the nuclear medicine service.

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We have developed an easy method for the synthesis of thirteen compounds derived from 1,2,4-triazoles through a carboxylic acid and hydrazinophthalazine reaction, with a 75-85% yield mediated by the use of agents such as 1-ethyl-3-(3'-dimethylaminopropyl)-carbodiimide hydrochloride and 1-hydroxybenzotriazole. The operational simplicity of this method and the good yield of products make it valuable for the synthesis of new compounds with pharmacological activity.

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It was carried out an electrochemical study of the cobalt electrodeposition onto HOPG electrode from an aqueous solution containing 10-2 M of CoSO4 + 1M (NH4)2SO4. Nucleation parameters such as nucleation rate, density of active nucleation sites, saturation nucleus and the rate constant of the proton reduction reaction (kPR) were determined from potentiostatic studies. An increase in kPR values with the decrease in the applied potential suggested a competition between H+ and Co2+ by the active sites on the surface. The ΔG energy calculated for the formation of stable nucleus was 8.21x10-21 J/nuclei. The AFM study indicated the formation of small clusters of 50-400 nm in diameter and 2-120 nm in height.

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The aims of this study were to formulate calcium-alginate beads containing glibenclamide, characterize the resulting microparticles, evaluate the release characteristics of this type of delivery system in an in vitro dissolution test, and compare it with two commercially available trademarks (Daonil® and Glibetab®). We obtained glibenclamide loaded calcium-alginate beads with a rough surface and a particle size between 150-200 µm. For the in vitro dissolution test Daonil® at 45 min showed a Q > 70%, whereas Glibetab® and glibenclamide calcium-alginate beads a Q < 70%; in spite of that glibenclamide calcium-alginate beads showed significant release properties.

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In this work we report the synthesis of sulfonamide derivatives using a conventional procedure and with solid supports, such as silica gel, florisil, alumina, 4Å molecular sieves, montmorillonite KSF, and montmorillonite K10 using solvent-free and microwave-assisted methods. Our results show that solid supports have a catalytic activity in the formation of sulfonamide derivatives. We found that florisil, montmorillonite KSF, and K10 could be used as inexpensive alternative catalysts that are easily separated from the reaction media. Additionally, solvent-free and microwave-assisted methods were more efficient in reducing reaction time and in increasing yield.

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We describe the synthesis of 12 new ethyl and methyl quinoxaline-7-carboxylate 1,4-di-N-oxide derivatives on solid supports with room temperature and microwave-assisted solvent-free procedures. Results show that solid supports have good catalytic activity in the formation of quinoxaline 1,4-di-N-oxide derivatives. We found that florisil and montmorillonite KSF and K10 could be used as new, easily available, inexpensive alternatives of catalysts. Additionally, room temperature and microwave-irradiation solvent-free synthesis was more efficient than a conventional procedure (Beirut reaction), reducing reaction time and increasing yield.