Optimal moment to change pressure regulator and sprayer kit on center pivot irrigation machines: a theoretical proposal

A theoretical model was developed in order to determine the optimal moment for substituting the sprayer and pressure regulator kit on a center pivot irrigation machine. The model is based on the hypothesis that pressure regulator and sprayer deterioration decrease irrigation uniformity. To compensate the deficit that happens at under irrigated areas, an increase on irrigation depth is required. The model considers: additional water consumption and energy costs, maintenance and labor costs, as well as yield losses associated with under or over irrigated areas. The sum of all these components is compared to buying and installing a new spray kit cost, allowing the farmer to decide the best moment to renovate the sprayer and pressure regulator kits on a center pivot irrigation machine based on economic criteria.

Phytoseiidae (Acari: Mesostigmata) on plants of the central region of the Brazilian cerrado

Four surveys of Phytoseiidae species associated with native plants were conducted in ten fragments of Cerrado sensu stricto to determine the species associated with the plants of this region. Twelve of the most common plant species were sampled in each fragment. Twenty six phytoseiid species were recorded during the surveys. Stryphnodendron adstringens was the host plant that had the highest number of species (eight species). Amblyseius neochiapensis Lofego, Moraes and McMurtry 2000 and Neoseiulus tunus (De Leon) 1967 were the most common phytoseiid species. These species occurred on 24 and 20 host species, respectively. Approximately 76 % of the phytoseiids found belonged to the subfamily Amblyseiinae Muma, 1961. Almost 27 % of phytoseiid species recorded were associated with only one plant species. In addition, approximately two thirds of species found in this study also occur in the Atlantic Forest. The comparison of our results from the central areas with previous surveys in peripheral areas of the Cerrado showed that only 12 phytoseiid species were common to both areas.

Dinámica poblacional y convivencia interétnica: el campesinado indígena mesoamericano en el presente

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Síndrome antifosfolípide e trombocitopenia na infância

Objective: To report the case of a child diagnosed with antiphospholipid syndrome associated with severe thrombocytopenia, and to review the literature on the subject. Case description: Child aged nine years and eight months old with severe thrombocytopenia associated with a positive anticardiolipin antibody. Data were collected by clinical history, physical examination, and laboratorial exams. Diagnosis was confirmed according to criteria established for the antiophospholipid syndrome, associated with the presence of the most common manifestations of the syndrome in children: livedo reticularis and thrombocytopenia. Comments: The antiphospholipid syndrome is an uncommon pediatric disease, and clinical manifestations such as decreased platelet number should be considered.

Preparation and characterization of poly(ε-caprolactone) nanospheres containing the local anesthetic lidocaine

The objective of this work was to develop a modified release system for the local anesthetic lidocaine (LDC), using poly(ε-caprolactone) (PCL) nanospheres (NSs), to improve the pharmacological properties of the drug when administered by the infiltration route. In vitro experiments were used to characterize the system and investigate the release mechanism. The NSs presented a polydispersion index of 0.072, an average diameter of 449.6nm, a zeta potential of -20.1mV, and an association efficiency of 93.3%. The release profiles showed that the release of associated LDC was slower than that of the free drug. Atomic force microscopy analyses showed that the spherical structure of the particles was preserved as a function of time, as well as after the release experiments. Cytotoxicity and pharmacological tests confirmed that association with the NSs reduced the toxicity of LDC, and prolonged its anesthetic action. This new formulation could potentially be used in applications requiring gradual anesthetic release, especially dental procedures. © 2012 Wiley Periodicals, Inc.

An exact series solution for the vibration analysis of cylindrical shells with arbitrary boundary conditions

In this paper, an exact series solution for the vibration analysis of circular cylindrical shells with arbitrary boundary conditions is obtained, using the elastic equations based on Flügge's theory. Each of the three displacements is represented by a Fourier series and auxiliary functions and sought in a strong form by letting the solution exactly satisfy both the governing differential equations and the boundary conditions on a point-wise basis. Since the series solution has to be truncated for numerical implementation, the term exactly satisfying should be understood as a satisfaction with arbitrary precision. One of the important advantages of this approach is that it can be universally applied to shells with a variety of different boundary conditions, without the need of making any corresponding modifications to the solution algorithms and implementation procedures as typically required in other techniques. Furthermore, the current method can be easily used to deal with more complicated boundary conditions such as point supports, partial supports, and non-uniform elastic restraints. Numerical examples are presented regarding the modal parameters of shells with various boundary conditions. The capacity and reliability of this solution method are demonstrated through these examples. © 2012 Elsevier Ltd. All rights reserved.

Two new species of Diaptomidae (Crustacea: Copepoda: Calanoida) from the Neotropical Region (Paraná River)

Two new species of Diaptomidae were found in the Middle Paraná River. The new species are referred to as Diaptomus curvatus sp. nov. and Diaptomus frutosae sp. nov. Important character states in Diaptomus curvatus include: right fifth leg with a well-developed endopod and with the lateral spine of the second exopod segment curved and longer than the segment on which it is inserted, plus the presence of a large dorsal process on urosomite 4 of the male. For Diaptomus frutosae they include: a differentiated hook-like process on segment 20 with chitinous protuberances at base of male right antennule; the last segment of the right leg 5 of male is triangular, and the lateral spine inserted distal to mid-level of this segment. Both species are placed in Diaptomus sensu lato as a temporary placement. http://www.zoobank.org/urn:lsid:zoobank.org:pub:FECDD6C4-C0AC-4043-ADDD-F29539B451F0. © 2013 Copyright Taylor and Francis Group, LLC.

Nota de la Secretaría sobre las posibles repercusiones del Mercado Común Europeo en las exportaciones latinoamericanas

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Notas para la discusión de la Primera Reunión de Empresarios de Países de la Asociación Latinoamericana de Integración (ALADI) sobre comercio y financiamiento

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Enhanced bulk and superficial hydrophobicities of starch-based bionanocomposites by addition of clay

In this work, thermoplastic starch (TPS)-clay bionanocomposites were obtained by an innovative methodology using a combination of methodologies commonly used in the composites and nanocomposites preparations. The main objectives or novelties were to confirm efficiency of the processing methodology by field emission gun scanning electron microscopy and investigate the effect of clay content on the spectroscopic, bulk and surface hydrophilic/hydrophobic properties of these bionanocomposites. Raman and FTIR spectroscopies confirmed the changes in the spectroscopic properties of the TPS bionanocomposites with the addition of the clay materials. Water absorption and contact angle measurements were also used to analyze the effect of the clay content on the hydrophilic properties of the TPS bionanocomposites. The results also showed that the addition of the cloisite-Na+ clay increased the bulk and surface hydrophobicities of the TPS matrix, which may increase its industrial application, particularly in manufacturing of food containers. © 2013 Elsevier B.V.

Reforma y modernización del Estado en Centroamérica

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Evolução do peso, consumo alimentar e qualidade de vida de mulheres com mais de dois anos da cirurgia bariátrica

Pós-graduação em Alimentos e Nutrição - FCFAR

Centroamérica: evolución del proceso de integración subregional, 1999-2000

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Experiencias en América Latina sobre el cálculo del producto trimestral

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