949 resultados para LOW-DENSITY
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The aim of this research is to make a bibliometric analysis of the journal Scire: Representación y Organización del Conocimiento, edited in Spain, in order to evidence the most productive institutions and countries, as well as to build a cooperation network and calculate the density indicators, centrality degree and betweenness. The 292 articles of the period 1996 to 2010 were analyzed. It was found out that, of the institutions participating in the articles, 25 institutions have been clearly the most productive. Almost all of them are Spanish, except four Brazilian ones and three more from three different countries. The institutional network showed a low density, but several cooperative sub-networks were identified, which suggest the existence of an international dialogue among researchers on the discipline.
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The aim of the present research is to analyse Ancib’s scientific production in the workgroup GT7 named Production and Communication of Information in ST&I, between the years of 2003 and 2009, through bibliometric indicators, from which it is possible to indicate what is more important or significant within a scientific field or context, so as to therefore analyse trends, existing relations or processes. The bibliometric studies are an approach method for the analysis of science behaviour in a given field. More specifically, by means of production and connection indicators, it aims at revealing and portraying the most productive authors, the kind of authorship present in this group, the most recurrent themes, most productive institutions, and the collaborative network determined by the institutional coauthorships and their indicators, so as to map and visualize the main researchers and institutions of the present GT, within the period of time in question. The research procedure derived from studying the 94 research project results presented in the period, where the paper reference, summary and corresponding key words can be found. Analysis concerning the most productive authors, most recurrent themes, kinds of authorship and most productive institutions have been carried out from the variables under review. The collaborative network between the institutions was built using the Pajek software, and, with the help of the Ucinet software, indicators of degree centrality, betweeness centrality, and closeness centrality have been reached, besides the calculation of density. The results point to 11 researchers and 9 institutions as the most productive ones. The collaborative institutional network was shown to be fragile, presenting low density, and in general the participating institutions have presented low centrality indexes. As a conclusion, it has been observed that the themes focus, in general, on bibliometric analysis and their indicators, using regional and national data as their universe.
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Pós-graduação em Engenharia Mecânica - FEB
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Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Agronomia (Horticultura) - FCA
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Juniperus virginiana (eastern redcedar) is encroaching into mesic prairies of the southern Great Plains, USA, and is altering the hydrologic cycle. We used the thermal dissipation technique to quantify daily water use of J. virginiana into a mesic prairie by measuring 19 trees of different sizes from different density stands located in north-central Oklahoma during 2011. We took the additional step to calibrate our measurements by comparing thermal dissipation technique estimates to volumetric water use for a subset of trees. Except for days with maximum air temperature below -3 degrees C, J. virginiana trees used water year round, reached a peak in late May, and exhibited reduced water use in summer when soil water availability was low. Overall daily average water use was 24 l (+/- 21.81 s.d.) per tree. Trees in low density stands used more water than trees with similar diameters from denser stands. However, there was no difference in water use between trees in different density stands when expressed on a canopy area basis. Approximately 50% of variation in water use that remained after accounting for the factors site, tree, and day was explained using a physiologically-based model that included daily potential evapotranspiration, maximum vapour pressure deficit, maximum temperature, solar radiation, and soil water storage between 0 and 10 cm. Our model suggested that a J. virginiana woodland with a closed canopy is capable of transpiring almost all precipitation reaching the soil in years with normal precipitation, indicating the potential for encroachment to reduce water yield for streamflow and groundwater recharge. Copyright (C) 2013 John Wiley & Sons, Ltd.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Bone quality and quantity are important factors with regard to the survival rate of dental implants. The aim of this study was to conduct a systematic review of dental implants inserted in low-density bone and to determine the survival rate of dental implants with surface treatments over time. A systematic review of the literature was undertaken by two independent individuals; the Medline/PubMed database was searched for the period July 1975 to March 2013. Relevant reports on bone quality and osseointegration of dental implants were selected. The search retrieved 1018 references, and after inclusion and exclusion criteria were applied, 19 studies were selected for review. A total of 3937 patients, who had received a total of 12,465 dental implants, were analyzed. The survival rates of dental implants according to the bone density were: type I, 97.6%; type II, 96.2%; type III, 96.5%; and type IV, 88.8%. The survival rate of treated surface implants inserted in low-density bone was higher (97.1%) than that of machined surface implants (91.6%). Surface-treated dental implants inserted in low-density bone have a high survival rate and may be indicated for oral rehabilitation. However, more randomized studies are required to better evaluate this issue.
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The over-production of reactive oxygen species (ROS) can cause oxidative damage to a large number of molecules, including DNA, and has been associated with the pathogenesis of several disorders, such as diabetes mellitus (DM), dyslipidemia and periodontitis (PD). We hypothesise that the presence of these diseases could proportionally increase the DNA damage. The aim of this study was to assess the micronucleus frequency (MNF), as a biomarker for DNA damage, in individuals with type 2 DM, dyslipidemia and PD. One hundred and fifty patients were divided into five groups based upon diabetic, dyslipidemic and periodontal status (Group 1 - poor controlled DM with dyslipidemia and PD; Group 2 - well-controlled DM with dyslipidemia and PD; Group 3 - without DM with dyslipidemia and PD; Group 4 - without DM, without dyslipidemia and with PD; and Group 5 - without DM, dyslipidemia and PD). Blood analyses were carried out for fasting plasma glucose, HbA1c and lipid profile. Periodontal examinations were performed, and venous blood was collected and processed for micronucleus (MN) assay. The frequency of micronuclei was evaluated by cell culture cytokinesis-block MN assay. The general characteristics of each group were described by the mean and standard deviation and the data were submitted to the Mann-Whitney, Kruskal-Wallis, Multiple Logistic Regression and Spearman tests. The Groups 1, 2 and 3 were similarly dyslipidemic presenting increased levels of total cholesterol, low density lipoprotein cholesterol and triglycerides. Periodontal tissue destruction and local inflammation were significantly more severe in diabetics, particularly in Group 1. Frequency of bi-nucleated cells with MN and MNF, as well as nucleoplasmic bridges, were significantly higher for poor controlled diabetics with dyslipidemia and PD in comparison with those systemically healthy, even after adjusting for age, and considering Bonferroni's correction. Elevated frequency of micronuclei was found in patients affected by type 2 diabetes, dyslipidemia and PD. This result suggests that these three pathologies occurring simultaneously promote an additional role to produce DNA impairment. In addition, the micronuclei assay was useful as a biomarker for DNA damage in individuals with chronic degenerative diseases.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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The non-ferrous materials have got so many mechanical, physical and chemical advantageous properties so that is provided to them consolidated position in industry. In this context, aluminium alloys have been seen a lot on many applications of engineering areas – specially on automotive, aeronautical and aerospace due to their main properties such as low density, high corrosion resistance, favorable structure weight / material resistance relation, among others characteristics that are mencioned through this study. This study aims to analyze the aluminium alloys behavior on a general context when they are used on turning process, taking for examples the 6262 and 7050 aluminium alloys. In this way, the analysis studies the datas obtained during the turning tests realized on 3 steps each one; those datas are concerning the medium and total rugosities – obtained with the assistance of a portable Surface Roughness Finish Tester, as well as the chips obtained during the tests - visual analysis, and the cutting tools wear – with the assistance of an optical microscope, under different conditions of application of cutting fluids (dry machining, application of coolant in abundance and MQL – Minimum Quantity of Lubricant). The results concerning this study show detailed information about influence of cutting fluids on the machining by turning of the aluminium alloys related on this work and also about aluminium alloys in general when they are used on turning processes with different conditions from one another. By this way, it was evident the MQL technique is the best one for the 6262 alloy. However, for 7050 alloy, it was evident that the dry machining is responsible for the best results
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In view of the need to develop a device for security and lateral protection, due to the Resolution 323/09 of CONTRAN, which requires the use of such equipment for most trucks and tow trucks, the objective of this work is to develop a project for an aluminum lateral protection device, according to the ABNT NBR 14.148 regulation, that, among many specifications, stipulates that the equipment must support a load of 5 kN and suffer a maximum deflection of 30mm, but does not say what material it should be made of. The reason for choosing aluminum is because of its low density, so as not to significantly increase the curb weight of the truck, which, consequently, reduces CO2 emissions and maintenance expenses. Additionally, this material presents a good resistance/weight ratio, high resistance to corrosion, excellent surface finish and it's fully recyclable; reason why it has been gaining the attention of many industry segments. For the realization of the project, profiles were chosen to make the assembly of the set, and then a finite elements analysis was performed in the HyperWorks software, to verify if the designed device would support the loads stipulated by the regulation. One details to note is that these simulation programs could show inaccuracies, because of the size and shape of the elements that compose the mesh, and for many other reasons, so it is necessary that, even with the results coming back satisfactory, actual physical tests are conducted to validate the proper functioning of the equipment, which was not done for this study
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The use of ceramic materials in ballistic armor is considerable. Such materials can be very harder and lighter than metallic materials commonly used and it presents advantages to replace metallic materials when necessary toughness can be achieved. However, as SiC and Al2O3 ceramic, traditionally used for shielding, still have high manufacturing cost or low density do not have enough to shield applications such as aircraft. An alternative is the glass-ceramics, ceramics obtained by controlled crystallization of glasses, whose properties can be adjusted by choosing the chemical composition of glass, heat treatment of crystallization and special treatments such as ion exchange on the surface, resulting in increased mechanical strength . The objective of this project is to study the kinetics of crystallization of a glass composition based on cordierite (2MgO.2Al2O3.5SiO2), low density and high hardness, for the manufacture of glass-ceramics for ballistic tests. Shown in this report are results of heat treatment of crystallization and characterization by thermal analysis (DSC) glass obtained previously, indicating uneven distribution of crystals, and drying, weighing, mixing of raw materials and a new fusion of glass, the same composition