2,636 research outputs found

    Needs and priorities for research into management of the Caatinga region of Northeastern Brazil.

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    Relatorio de consultoria junto ao CPATSA em atividade para fortalecer o Programa de Pesquisa de Recursos Naturais (producao e utilizacao de pastagem) atraves de planejamento, avaliacao e recomendacao sobre pesquisa do uso dos recursos de pastagem no semi-arido brasileiro.bitstream/item/136293/1/2740-1.pd

    Hot methane line lists for exoplanet and brown dwarf atmospheres

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    We present comprehensive experimental line lists of methane (CH4) at high temperatures obtained by recording Fourier transform infrared emission spectra. Calibrated line lists are presented for the temperatures 300 - 1400 degC at twelve 100 degC intervals spanning the 960 - 5000 cm-1 (2.0 - 10.4 microns) region of the infrared. This range encompasses the dyad, pentad and octad regions, i.e., all fundamental vibrational modes along with a number of combination, overtone and hot bands. Using our CH4 spectra, we have estimated empirical lower state energies (Elow in cm-1) and our values have been incorporated into the line lists along with line positions (cm-1) and calibrated line intensities (S' in cm molecule-1). We expect our hot CH4 line lists to find direct application in the modeling of planetary atmospheres and brown dwarfs.Comment: Supplementary material is provided via the Astrophysical Journal referenc

    review of paediatric liver resections in Johannesburg: Experiences and preferred technique

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    Background. Liver resections are widely performed in paediatric surgery. Many techniques exist to achieve vascular control, minimise bleeding and complete the parenchymal division.Methods. We retrospectively reviewed all liver resections performed in the Department of Paediatric Surgery at our institution between January 2005 and June 2012. Data pertaining to basic demographics, indications for surgery, parenchymal transection techniques, morbidity, mortality and histology were collated.Results. Twenty-one resections were performed in children aged 6 weeks - 11 years; 18 for malignant liver disease (including 9 hepatoblastomas), and 3 for benign disease. We describe 1 perioperative mortality secondary to torsion of the liver remnant, and no surgical morbidity. Three cases underwent total hepatic vascular exclusion with sharp parenchymal transection. The remaining patients underwent selective vascular inflow and outflow control using the Cavitron Ultra Sonic Aspirator and Harmonic Scalpel to divide the parenchyma.Conclusion. Care for these patients should be multidisciplinary.High-volume units and access to liver transplantation offer optimal results. No technique is proven superior to the ‘clamp crush’ technique of parenchymal transection. Knowledge of hepatic anatomy is key to minimising morbidity, and surgeons should be familiar with and have the flexibility to use all techniques of vascular control

    A blowup criterion for ideal viscoelastic flow

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    We establish an analog of the Beale-Kato-Majda criterion for singularities of smooth solutions of the system of PDE arising in the Oldroyd model for ideal viscoelastic flow

    Detection of s-Triazine pesticides in natural waters by modified large-volume direct injection HPLC

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    There is a need for simple and inexpensive methods to quantify potentially harmful persistent pesticides often found in our water-ways and water distribution systems. This paper presents a simple, relatively inexpensive method for the detection of a group of commonly used pesticides (atrazine, simazine and hexazinone) in natural waters using large-volume direct injection high performance liquid chromatography (HPLC) utilizing a monolithic column and a single wavelength ultraviolet–visible light (UV–vis) detector. The best results for this system were obtained with a mobile phase made up of acetonitrile and water in a 30:70 ratio, a flow rate of 2.0 mL min−1, and a detector wavelength of 230 nm. Using this method, we achieved retention times of less than three minutes, and detection limits of 5.7 μg L−1 for atrazine, 4.7 μg L−1 for simazine and 4.0 μg L−1 for hexazinone. The performance of this method was validated with an inter-laboratory trial against a National Association of Testing Authorities (NATA) accredited liquid chromatography–mass spectrometry/mass spectrometry (LC–MS/MS) method commonly used in commercial laboratories

    The Social Ethics of Jesus

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    Well-posedness of the Ericksen-Leslie system

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    In this paper, we prove the local well-posedness of the Ericksen-Leslie system, and the global well-posednss for small initial data under the physical constrain condition on the Leslie coefficients, which ensures that the energy of the system is dissipated. Instead of the Ginzburg-Landau approximation, we construct an approximate system with the dissipated energy based on a new formulation of the system.Comment: 16 page

    Effect of Several Design Variables on Internal Performance of Convergent-plug Exhaust Nozzles

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    Numerous experiments were conducted to determine factors which affect the internal performance of convergent-plug exhaust nozzles. The results of these experiments, which include effects of such things as plug shape, nozzle inlet Mach number, and outer-shell characteristics, provide a basis for optimum desifn from the standpoint of weight and size. The results also show performance penalties which can result when the nozzle is too small
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