830 resultados para IPv6, Denial of Service, Coloured Petri Nets, Risk Analysis, IPv6threats
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Phylogenetic studies of some species of the genus Coffea. II-numerical analysis of isoenzymatic data
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The Arachis section is the most important of the nine sections of the genus Arachis because it includes the cultivated peanut, Arachis hypogaea. The genetic improvement of A. hypogaea using wild relatives is at an early stage of development in spite of their potential as sources of genes, including those for disease and pests resistance, that are not found in the A. hypogaea primary gene pool. Section Arachis species germplasm has been collected and maintained in gene banks and its use and effective conservation depends on our knowledge of the genetic variability contained in this material. Microsatellites are routinely used for the analysis of genetic variability because they are highly polymorphic and codominant. The objective of this study was to evaluate the transferability of microsatellite primers and the assay of genetic variability between and within the germplasm of some species of the Arachis section. Fourteen microsatellite loci developed for three different species of Arachis were analyzed and 11 (78%) were found to be polymorphic. All loci had transferability to all the species analyzed. The polymorphic loci were very informative, with expected heterozygosity per locus ranging from 0.70 to 0.94. In general, the germplasm analyzed showed wide genetic variation. © 2006 Sociedade Brasileira de Genética.
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Bone decalcification is a time-consuming process. It takes weeks and preservation of the tissue structure depends on the quality and velocity of the demineralization process. In the present study, a decalcification methodology was adapted using microwaving to accelerate the decalcification of rat bone for electron microscopic analysis. The ultrastructure of the bone decalcified by microwave energy was observed. Wistar rats were perfused with paraformaldehyde and maxillary segments were removed and fixed in glutaraldehyde. Half of specimens were decalcified by conventional treatment with immersion in Warshawsky solution at 4oC during 45 days, and the other half of specimens were placed into the beaker with 20 mL of the Warshawsky solution in ice bath and thereafter submitted to irradiation in a domestic microwave oven (700 maximum power) during 20 s/350 W/±37°C. In the first day, the specimens were irradiated 9 times and stored at 40°C overnight. In the second day, the specimens were irradiated 20 times changing the solution and the ice after each bath. After decalcification, some specimens were postfixed in osmium tetroxide and others in osmium tetroxide and potassium pyroantimonate. The specimens were observed under transmission electron microscopy. The results showed an increase in the decalcification rate in the specimens activated by microwaving and a reduction of total experiment time from 45 days in the conventional method to 48 hours in the microwave-aided method.
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The intension of this paper was to review and discuss some of the current quantitative analytical procedures which are used for quality control of pharmaceutical products. The selected papers were organized according to the analytical technique employed. Several techniques like ultraviolet/visible spectrophotometry, fluorimetry, titrimetry, electroanalytical techniques, chromatographic methods (thin-layer chromatography, gas chromatography and high-performance liquid chromatography), capillary electrophoresis and vibrational spectroscopies are the main techniques that have been used for the quantitative analysis of pharmaceutical compounds. In conclusion, although simple techniques such as UV/VIS spectrophotometry and TLC are still extensively employed, HPLC is the most popular instrumental technique used for the analysis of pharmaceuticals. Besides, a review of recent works in the area of pharmaceutical analysis showed a trend in the application of techniques increasingly rapid such as ultra performance liquid chromatography and the use of sensitive and specific detectors as mass spectrometers.
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Multipulse rectifier topologies based on autoconnections, or differential connections, are more and more applied as interface stages between the mains and power converters. These topologies mitigate many low-order current harmonics in the utility, reducing the THD (total harmonic distortion) and increasing the power factor. This paper presents a mathematical model based on phasor diagrams, that results in a single expression able to unify all differential topologies connections (Delta and Wye), for both step-up or step-down autotransformers, for 12 and 18-pulse AC-DC converters. The proposed family of converters can be designed for any relationship between the input voltage and the load voltage. An immediate application would be the retrofit, i.e. to replace a conventional rectifier with poor quality of the processed energy by the 12 or 18 pulses rectifier with Wye or Delta-differential connection. The design procedure, simple and fast, is developed and tested for a prototype rating 6 kW and 250 V on the DC load © 2010 IEEE.
Disability in the Caribbean. A study of four countries: a socio-demographic analysis of the disabled
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Includes bibliography
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Objectives: The aim of this study was to analyze the stress distribution on dentin/adhesive interface (d/a) through a 3-D finite element analysis (FEA) varying the number and diameter of the dentin tubules orifice according to dentin depth, keeping hybrid layer (HL) thickness and TAǴs length constant. Materials and Methods: 3 models were built through the SolidWorks software: SD - specimen simulating superficial dentin (41 x 41 x 82 μm), with a 3 μm thick HL, a 17 μm length Tag, and 8 tubules with a 0.9 μm diameter restored with composite resin. MD - similar to M1 with 12 tubules with a 1.2 μm diameter, simulating medium dentin. DD - similar to M1 with 16 tubules with a 2.5 μm diameter, simulating deep dentin. Other two models were built in order to keep the diameter constant in 2.5 μm: MS - similar to SD with 8 tubules; and MM - similar to MD with 12 tubules. The boundary condition was applied to the base surface of each specimen. Tensile load (0.03N) was performed on the composite resin top surface. Stress field (maximum principal stress in tension - σMAX) was performed using Ansys Wokbench 10.0. Results: The peak of σMAX (MPa) were similar between SD (110) and MD (106), and higher for DD (134). The stress distribution pathway was similar for all models, starting from peritubular dentin to adhesive layer, intertubular dentin and hybrid layer. The peak of σMAX (MPa) for those structures was, respectively: 134 (DD), 56.9 (SD), 45.5 (DD), and 36.7 (MD). Conclusions: The number of dentin tubules had no influence in the σMAX at the dentin/adhesive interface. Peritubular and intertubular dentin showed higher stress with the bigger dentin tubules orifice condition. The σMAX in the hybrid layer and adhesive layer were going down from superficial dentin to deeper dentin. In a failure scenario, the hybrid layer in contact with peritubular dentin and adhesive layer is the first region for breaking the adhesion. © 2011 Nova Science Publishers, Inc.
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The texture of concrete blocks is very important and is often the decisive factor when choosing a product, particularly if the building specifications call for high-strength blocks allied to low-cost finish, in which case exposed blocks with a closer texture are often preferred. Furthermore, a closer texture, especially for exteriors, may be a vital factor in ensuring the building's durability. At present, however, there is no standard to quantify the texture of a structural block. Further, when studying masonry blocks compressive strength should never be overlooked. This article discusses a procedure to produce concrete block textures with and without the addition of lime, but still to achieve the required compressive strength. The method used in this study, to evaluate texture, proved to be simpler and cheaper than methods reported by other authors in the literature. The addition of small quantities of lime proved beneficial for both texture and compressive strength. Increasing the amount of lime further, however, only improved texture.
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Includes bibliography
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Most of the established procedures for analysis of aeroelastic flutter in the development of aircraft are based on frequency domain methods. Proposing new methodologies in this field is always a challenge, because the new methods need to be validated by many experimental procedures. With the interest for new flight control systems and nonlinear behavior of aeroelastic structures, other strategies may be necessary to complete the analysis of such systems. If the aeroelastic model can be written in time domain, using state-space formulation, for instance, then many of the tools used in stability analysis of dynamic systems may be used to help providing an insight into the aeroelastic phenomenon. In this respect, this paper presents a discussion on the use of Gramian matrices to determine conditions of aeroelastic flutter. The main goal of this work is to introduce how observability gramian matrix can be used to identify the system instability. To explain the approach, the theory is outlined and simulations are carried out on two benchmark problems. Results are compared with classical methods to validate the approach and a reduction of computational time is obtained for the second example. © 2013 Douglas Domingues Bueno et al.
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Incluye Bibliografía
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Includes bibliography