998 resultados para Co-variables
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Mode of access: Internet.
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Celtis sinensis is an introduced plant species to the southeastern region of Queensland that has had a destructive affect on indigenous plant Communities and its pollen has been identified as an allergen Source. Pollen belonging to C. sinensis was sampled during a 5-year (June 1994-May 1999) atmospheric pollen-monitoring programme in Brisbane, Australia, using a Burkard 7-day spore trap. The seasonal incidence of airborne C. sinensis pollen (CsP) in Brisbane occurred over a brief period each year during spring (August-September), while peak concentrations were restricted to the beginning of September. individual CsP seasons were heterogeneous with daily counts within the range 1-10 grains m(-3) on no more than 60 sampling days; however, smaller airborne concentrations of CsP were recorded out of each season. Correlation co-efficients were significant each year for temperature (p0.05) and relative humidity (p>0.05). A significant relationship (r(2)=0.81, p=0.036) was established between the total CsP count and pre-seasonal average maximum temperature; however, periods of precipitation (>2mm) were demonstrated to significantly lower the daily concentrations of CsP from the atmosphere. Given the environmental and clinical significance of CsP and its prevalence in the atmosphere of Brisbane, a Clinical population-based Study is required to further understand the pollen's importance as a seasonal sensitizing source in this region.
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Analyzing geographical patterns by collocating events, objects or their attributes has a long history in surveillance and monitoring, and is particularly applied in environmental contexts, such as ecology or epidemiology. The identification of patterns or structures at some scales can be addressed using spatial statistics, particularly marked point processes methodologies. Classification and regression trees are also related to this goal of finding "patterns" by deducing the hierarchy of influence of variables on a dependent outcome. Such variable selection methods have been applied to spatial data, but, often without explicitly acknowledging the spatial dependence. Many methods routinely used in exploratory point pattern analysis are2nd-order statistics, used in a univariate context, though there is also a wide literature on modelling methods for multivariate point pattern processes. This paper proposes an exploratory approach for multivariate spatial data using higher-order statistics built from co-occurrences of events or marks given by the point processes. A spatial entropy measure, derived from these multinomial distributions of co-occurrences at a given order, constitutes the basis of the proposed exploratory methods. © 2010 Elsevier Ltd.
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Analyzing geographical patterns by collocating events, objects or their attributes has a long history in surveillance and monitoring, and is particularly applied in environmental contexts, such as ecology or epidemiology. The identification of patterns or structures at some scales can be addressed using spatial statistics, particularly marked point processes methodologies. Classification and regression trees are also related to this goal of finding "patterns" by deducing the hierarchy of influence of variables on a dependent outcome. Such variable selection methods have been applied to spatial data, but, often without explicitly acknowledging the spatial dependence. Many methods routinely used in exploratory point pattern analysis are2nd-order statistics, used in a univariate context, though there is also a wide literature on modelling methods for multivariate point pattern processes. This paper proposes an exploratory approach for multivariate spatial data using higher-order statistics built from co-occurrences of events or marks given by the point processes. A spatial entropy measure, derived from these multinomial distributions of co-occurrences at a given order, constitutes the basis of the proposed exploratory methods. © 2010 Elsevier Ltd.
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Factors associated with survival were studied in 84 neuropathologically documented cases of the pre-senile dementia frontotemporal dementia lobar degeneration (FTLD) with transactive response (TAR) DNA-binding protein of 43 kDa (TDP-43) proteinopathy (FTLD-TDP). Kaplan-Meier survival analysis estimated mean survival as 7.9 years (range: 1-19 years, SD = 4.64). Familial and sporadic cases exhibited similar survival, including progranulin (GRN) gene mutation cases. No significant differences in survival were associated with sex, disease onset, Braak disease stage, or disease subtype, but higher survival was associated with lower post-mortem brain weight. Survival was significantly reduced in cases with associated motor neuron disease (FTLD-MND) but increased with Alzheimer's disease (AD) or hippocampal sclerosis (HS) co-morbidity. Cox regression analysis suggested that reduced survival was associated with increased densities of neuronal cytoplasmic inclusions (NCI) while increased survival was associated with greater densities of enlarged neurons (EN) in the frontal and temporal lobes. The data suggest that: (1) survival in FTLD-TDP is more prolonged than typical in pre-senile dementia but shorter than some clinical subtypes such as the semantic variant of primary progressive aphasia (svPPA), (2) MND co-morbidity predicts poor survival, and (3) NCI may develop early and EN later in the disease. The data have implications for both neuropathological characterization and subtyping of FTLD-TDP.
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Composites based on alumina (Al2O3), tungsten carbide (WC) and cobalt (Co) exhibit specific properties such as low density, high oxidation resistance, high melting point and high chemical inertia. That composite shows to be a promising material for application in various fields of engineering. In this work, the mechanical properties of the composite (Al2O3 – WC – Co), particularly density and hardness, were evaluated according to the effects of the variables of powder processing parameters, green compact and sintered. Powder composites with the composition of 80 wt% Al2O3, 18 wt% WC and 2 wt% Co were processed by high energy ball milling in a planetary mill for 50 hours as well as mixed by manual mixing in a glass vessel with the same proportion. Samples were collected (2, 10, 20, 30, 40 and 50 hours) during the milling process. Then, the powders were compacted in a cylindrical die with 5 mm in diameter in a uniaxial press with pressures of 200 and 400 MPa. The sintering was in two stages: first, the solid phase sintering was performed at 1126 and 1300 °C for 1 hour with a heating rate of 10 °C/min in a resistive furnace under argon atmosphere for green samples compacted in 200 and 400 MPa; the second sintering was performed on dilatometer in solid phase at 1300 °C for green sample compacted in 200 MPa, another sintering also was performed on dilatometer, this time in liquid phase at 1550 °C for green samples compacted in 200 and 400 MPa, with the same parameters used in resistive furnace. The raw materials were characterized by X – ray diffraction (XRD), X – ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and laser particlemeter. The sintered samples were subjected to microhardness testing. The results showed that high energy milling achieved to the objectives regarding the particle size and the dispersion of composite phases. However, the hardness did not achieve to significant results, this is an indication that the composite has low fracture toughness.
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Composites based on alumina (Al2O3), tungsten carbide (WC) and cobalt (Co) exhibit specific properties such as low density, high oxidation resistance, high melting point and high chemical inertia. That composite shows to be a promising material for application in various fields of engineering. In this work, the mechanical properties of the composite (Al2O3 – WC – Co), particularly density and hardness, were evaluated according to the effects of the variables of powder processing parameters, green compact and sintered. Powder composites with the composition of 80 wt% Al2O3, 18 wt% WC and 2 wt% Co were processed by high energy ball milling in a planetary mill for 50 hours as well as mixed by manual mixing in a glass vessel with the same proportion. Samples were collected (2, 10, 20, 30, 40 and 50 hours) during the milling process. Then, the powders were compacted in a cylindrical die with 5 mm in diameter in a uniaxial press with pressures of 200 and 400 MPa. The sintering was in two stages: first, the solid phase sintering was performed at 1126 and 1300 °C for 1 hour with a heating rate of 10 °C/min in a resistive furnace under argon atmosphere for green samples compacted in 200 and 400 MPa; the second sintering was performed on dilatometer in solid phase at 1300 °C for green sample compacted in 200 MPa, another sintering also was performed on dilatometer, this time in liquid phase at 1550 °C for green samples compacted in 200 and 400 MPa, with the same parameters used in resistive furnace. The raw materials were characterized by X – ray diffraction (XRD), X – ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and laser particlemeter. The sintered samples were subjected to microhardness testing. The results showed that high energy milling achieved to the objectives regarding the particle size and the dispersion of composite phases. However, the hardness did not achieve to significant results, this is an indication that the composite has low fracture toughness.
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Systematic, high-quality observations of the atmosphere, oceans and terrestrial environments are required to improve understanding of climate characteristics and the consequences of climate change. The overall aim of this report is to carry out a comparative assessment of approaches taken to addressing the state of European observations systems and related data analysis by some leading actors in the field. This research reports on approaches to climate observations and analyses in Ireland, Switzerland, Germany, The Netherlands and Austria and explores options for a more coordinated approach to national responses to climate observations in Europe. The key aspects addressed are: an assessment of approaches to develop GCOS and provision of analysis of GCOS data; an evaluation of how these countries are reporting development of GCOS; highlighting best practice in advancing GCOS implementation including analysis of Essential Climate Variables (ECVs); a comparative summary of the differences and synergies in terms of the reporting of climate observations; an overview of relevant European initiatives and recommendations on how identified gaps might be addressed in the short to medium term.
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[EN] Background: Plasma biochemical and hematologic variables are important in the management of endangered sea turtles, such as loggerheads. However, studies on blood biochemistry and hematology of loggerheads are limited, and different concentrations according to variable criteria have been reported. Objective: The purpose of this study was to establish and compare baseline plasma chemistry and hematology values in Eastern Atlantic juvenile and adult nesting loggerhead sea turtles (Caretta caretta).
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El objetivo de la mayoría de las compañías se centra en obtener el liderazgo de su respectivo mercado, desarrollando diferentes estrategias, las cuales buscan ganar la preferencia del cliente en el momento de seleccionar una marca. Como variable crítica para lograrlo se encuentra la generación de una ventaja competitivaque lo diferencie de sus competidores. Sin embargo, la construcción de una ventaja competitiva es un proceso complejo que parte de la identificación de las necesidades del mercado.Es decir, sólo se obtendrá una ventaja competitiva si la empresaconoce realmente cuáles son los aspectos a los que el mercado les asigna valor, logrando satisfacerlos mejor que la competencia y de manera sostenible. El presente artículo se centra en lametodología para identificar esas variables críticas en la decisión de compra en los mercados industriales, las cuales permitirán a la organización ajustar su estrategia para lograr la preferencia de compra. Aunque se centra en la industria de materialesautoadhesivos, la aplicación de esta metodología y su marco de referencia se ajustan a cualquier mercado de tipo industrial, donde las decisiones son tomadas por grupos de compras multidisciplinarios y tienen una mayor complejidad técnica que las decisiones en los segmentos de productos de consumo masivo.
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Local anesthetic agents cause temporary blockade of nerve impulses productiong insensitivity to painful stimuli in the area supplied by that nerve. Bupivacaine (BVC) is an amide-type local anesthetic widely used in surgery and obstetrics for sustained peripheral and central nerve blockade. in this study, we prepared and characterized nanosphere formulations containing BVC. To achieve these goals, BVC loaded poly(DL-lactide-co-glycolide) (PLGA) nanospheres (NS) were prepared by nanopreciptation and characterized with regard to size distribution, drug loading and cytotoxicity assays. The 2(3-1) factorial experimental design was used to study the influence of three different independent variables on nanoparticle drug loading. BVC was assayed by HPLC, the particle size and zeta potential were determined by dynamic light scattering. BVC was determined using a combined ultrafiltration-centrifugation technique. The results of optimized formulations showed a narrow size distribution with a polydispersivity of 0.05%, an average diameter of 236.7 +/- 2.6 nm and the zeta potential -2.93 +/- 1,10 mV. In toxicity studies with fibroblast 3T3 cells, BVC loaded-PLGA-NS increased cell viability, in comparison with the effect produced by free BVC. In this way, BVC-loaded PLGA-NS decreased BVC toxicity. The development of BVC formulations in carriers such as nanospheres could offer the possibility of controlling drug delivery in biological systems, prolonging the anesthetic effect and reducing toxicity.
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Funciones de varias variables y sus derivadas con aplicaciones a la administración, las Ciencias Sociales y la Economía es una lección en la que, además de los conceptos fundamentales fe funciones de varias variables, se construyen gráficas en dos y tres dimensiones, algunas de ellas utilizando software matemático; de igual manera, se muestran aplicaciones de funciones de producción, costo y demanda, curvas de indiferencia e isocuantas, aplicaciones a la administración, las ciencias sociales y la economía de la diferencia total, análisis marginal, costo promedio marginal, tasa marginal de sustitución, artículos sustitutos y complementarios, y finalmente, se le da importancia al planteamiento de problemas de optimización empleando los multiplicadores de Lagrange.
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Este estudio realiza una categorización regional de los países en América Latina con respecto de las categorizaciones globales teniendo en cuenta los índices de competitividad, crecimiento económico y desarrollo humano. El objetivo es actualizar los análisis sobre la situación regional de forma cuantitativa involucrando el grado de asimetría en la competitividad. Esta relación entre el posicionamiento global y regional ha influenciado directamente la evolución del tejido empresarial
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This is an ecological, analytical and retrospective study comprising the 645 municipalities in the State of São Paulo, the scope of which was to determine the relationship between socioeconomic, demographic variables and the model of care in relation to infant mortality rates in the period from 1998 to 2008. The ratio of average annual change for each indicator per stratum coverage was calculated. Infant mortality was analyzed according to the model for repeated measures over time, adjusted for the following correction variables: the city's population, proportion of Family Health Programs (PSFs) deployed, proportion of Growth Acceleration Programs (PACs) deployed, per capita GDP and SPSRI (São Paulo social responsibility index). The analysis was performed by generalized linear models, considering the gamma distribution. Multiple comparisons were performed with the likelihood ratio with chi-square approximate distribution, considering a significance level of 5%. There was a decrease in infant mortality over the years (p < 0.05), with no significant difference from 2004 to 2008 (p > 0.05). The proportion of PSFs deployed (p < 0.0001) and per capita GDP (p < 0.0001) were significant in the model. The decline of infant mortality in this period was influenced by the growth of per capita GDP and PSFs.
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The aim of this study was to evaluate the performance of the Centers for Dental Specialties (CDS) in the country and associations with sociodemographic indicators of the municipalities, structural variables of services and primary health care organization in the years 2004-2009. The study used secondary data from procedures performed in the CDS to the specialties of periodontics, endodontics, surgery and primary care. Bivariate analysis by χ2 test was used to test the association between the dependent variable (performance of the CDS) with the independents. Then, Poisson regression analysis was performed. With regard to the overall achievement of targets, it was observed that the majority of CDS (69.25%) performance was considered poor/regular. The independent factors associated with poor/regular performance of CDS were: municipalities belonging to the Northeast, South and Southeast regions, with lower Human Development Index (HDI), lower population density, and reduced time to deployment. HDI and population density are important for the performance of the CDS in Brazil. Similarly, the peculiarities related to less populated areas as well as regional location and time of service implementation CDS should be taken into account in the planning of these services.