Relative Standard Error Of Estimate Research Articles

USO DO MÉTODO DA PREDIÇÃO DE PARÂMETROS PARA PROJETAR A DISTRIBUIÇÃO DIAMÉTRICA EM FLORESTAS NATIVAS COM A FUNÇÃO WEIBULL

O objetivo deste trabalho foi utilizar o método da Predição dos Parâmetros da função Weibull 3P (Três Parâmetros) para a projeção da distribuição diamétrica de um Fragmento de Floresta Ombrófila Mista, comparando os resultados com projeções geradas pelos métodos Matriz de Transição e Razão de Movimentos. Os dados são oriundos de 100 parcelas permanentes de 2.500 m² (50 m x 50 m) instaladas na Floresta Nacional de Irati, Estado do Paraná e medidas nos anos de 2002, 2005, 2008 e 2011. Para o método da Predição dos Parâmetros foram ajustados modelos (pelo método stepwise) para projeção de 3, 6 e 9 anos cujas variáveis dependentes foram os parâmetros da função Weibull 3P b e c (o parâmetro a foi fixado em 10,02 cm, correspondente ao valor do diâmetro mínimo mensurado) e como variáveis independentes foram testadas o N.ha-1, G.ha-1, dg, dmin, diâmetros percentis (dP), dmax e suas transformações (inversa, logarítmica e quadrática). Um modelo de sobrevivência foi ajustado para projetar o número de árvores. As projeções obtidas pelo método da Predição dos Parâmetros para 2008 e 2011 foram comparadas com as projeções geradas pelos métodos da Matriz de Transição e Razão de Movimento utilizando-se o teste Kolmogorov-Smirnov (K-S) e o Índice de Reynolds (IR). O desempenho dos ajustes dos modelos foi avaliado pelo índice de Schlaegel (IA) e o erro padrão de estimativa em percentagem (SYX%). Os resultados indicaram bons ajustes para o método da Predição dos Parâmetros da função Weibull. Na comparação com o da Matriz de Transição e Razão de Movimento, o método testado apresentou os melhores resultados de acordo com o teste K-S, porém de acordo com IR, a melhor performance foi verificada pelo método da Matriz da Transição. Nos três métodos analisados houve aderência entre distribuições observadas e estimadas de acordo com o teste K-S.

Axial compressive behaviour of circular CFFT: Experimental database and design-oriented model

Concrete Filled Fibre Reinforced Polymer Tube (CFFT) for new columns construction has attracted significant research attention in recent years. The CFFT acts as a formwork for new columns and a barrier to corrosion accelerating agents. It significantly increases both the strength capacity (Strength enhancement ratio) and the ductility (Strain enhancement ratio) of reinforced concrete columns. In this study, based on predefined selection criteria, experimental investigation results of 134 circular CFFT columns under axial compression have been compiled and analysed from 599 CFFT specimens available in the literature. It has been observed that actual confinement ratio (expressed as a function of material properties of fibres, diameter of CFFT and compressive strength of concrete) has significant influence on the strength and ductility of circular CFFT columns. Design oriented models have been proposed to compute the strength and strain enhancement ratios of circular CFFT columns. The proposed strength and strain enhancement ratio models have significantly reduced Average Absolute Error (AAE), Mean Square Error (MSE), Relative Standard Error of Estimate (RSEE) and Standard Deviation (SD) as compared to other available strength and strain enhancement ratios of circular CFFT column models. The predictions of the proposed strength and strain enhancement ratio models match well with the experimental strength and strain enhancement ratios investigation results in the compiled database.

EVOLUÇÃO DAS VARIÁVEIS DENDROMÉTRICAS DA BRACATINGA POR CLASSE DE SÍTIO

A identificação do ritmo de crescimento das variáveis dendrométricas de espécies florestais com o uso da análise de tronco é rápida, eficiente e de grande importância na tomada de decisões para o manejador florestal. Sendo assim, objetivou-se neste trabalho analisar a evolução das curvas de produção, Incremento Médio Anual (IMA) e Incremento Corrente Anual (ICA) da altura, diâmetro, área transversal e volume individual da Bracatinga (Mimosa scabrella), em diferentes classes de sítio, bem como, ajustar modelos matemáticos para expressar a evolução dessas variáveis, ao longo dos anos. A base de dados proveio da análise completa de tronco de 29 árvores, coletadas na região metropolitana de Curitiba, com idades variando de sete a 18 anos, distribuídas em três classes de sítio. Após as medições e processamento básico dos dados, ajustaram-se seis modelos matemáticos conhecidos na literatura, para cada uma das quatro variáveis dendrométricas em análise, independentemente para cada sítio. O melhor modelo foi escolhido com base no coeficiente de determinação ajustado (R²aj), erro padrão de estimativa em percentagem (Syx%) e análise gráfica de resíduos. Os resultados mostraram que o modelo de Chapman-Richards foi o de melhor ajuste para quase todas as variáveis em análise dentro dos três sítios. Verificou-se, também, que a ordem de culminação do incremento corrente anual seguiu a ordem cronológica esperada, isto é, primeiro a altura, seguida pelo diâmetro, área transversal e, por último, o volume, em todos os sítios.

Breast Density Evaluation Using Spectral Mammography, Radiologist Reader Assessment, and Segmentation Techniques: A Retrospective Study Based on Left and Right Breast Comparison

The purpose of this study was to compare the precision of mammographic breast density measurement using radiologist reader assessment, histogram threshold segmentation, fuzzy C-mean segmentation, and spectral material decomposition. Spectral mammography images from a total of 92 consecutive asymptomatic women (aged 50-69years) who presented for annual screening mammography were retrospectively analyzed for this study. Breast density was estimated using 10 radiologist reader assessment, standard histogram thresholding, fuzzy C-mean algorithm, and spectral material decomposition. The breast density correlation between left and right breasts was used to assess the precision of these techniques to measure breast composition relative to dual-energy material decomposition. In comparison to the other techniques, the results of breast density measurements using dual-energy material decomposition showed the highest correlation. The relative standard error of estimate for breast density measurements from left and right breasts using radiologist reader assessment, standard histogram thresholding, fuzzy C-mean algorithm, and dual-energy material decomposition was calculated to be 1.95, 2.87, 2.07, and 1.00, respectively. The results indicate that the precision of dual-energy material decomposition was approximately factor of two higher than the other techniques with regard to better correlation of breast density measurements from right and left breasts.

Clinical Evaluation of The Determination of Plasma Concentrations of Darunavir, Etravirine, Raltegravir and Ritonavir in Dried Blood Spot Samples

Measurement of drug levels in plasma is currently the gold standard for pharmacological studies. However, venous sampling is not feasible in some populations (e.g., neonates) or may be difficult in certain situations, such as nonhospital-based settings. Dried blood spots (DBS) can be obtained by a simple fingerprick and the subsequent collection of blood on a filter card, allowing patient-friendly sample collection in non-hospital-based settings. Despite these advantages, thus far no clinical evaluation has been performed for the use of DBS concentrations as surrogates for plasma levels. Our purpose was to clinically evaluate DBS sampling for the determination of plasma concentrations for the novel antiretroviral drugs etravirine, darunavir/ritonavir and raltegravir. DBS concentrations were measured in 11 HIV-infected patients using LC-MS/MS. DBS concentrations were proportional to plasma concentrations. All drug concentrations were higher in DBS than in plasma samples. The plasma:DBS ratio and the respective relative standard error of estimate (RSE) of darunavir, etravirine, raltegravir and ritonavir were 0.632 (4.97% RSE), 0.523 (4.84% RSE), 0.617 (14.9% RSE) and 0.592 (2.99% RSE), respectively. Hematocrit did not explain variability in our study. DBS are reproducibly correlated to plasma levels and can be used for monitoring antiretroviral drug exposure in HIV-infected patients.

A fast, sensitive determination of doxorubicin in rat plasma by solid-phase extraction and reversed-phase ion-pair chromatography

A very selective method is described for the determination of doxorubicin in rat plasma. Doxorubicin is extracted from the plasma on a pretreated octadecyl silane column and eluted with phosphate buffer pH 2.6/methanol (25/75, v/v) containing sodium 1-heptanesulfonate as ion-pairing agent. The extraction procedure is suitable for samples which contain doxorubicin encapsulated in liposomes if Triton X-100 is added. A portion of the evaporated eluate is used for high-performance reversed-phase chromatography with the same eluent and a fluorescence detector. Daunorubicin is used as internal standard. Extraction of doxorubicin from plasma is quantitative. The calibration graph is linear for 0.2-100 μg l −1 doxorubicin with a limit of detection of 0.2 μg l −1 for 0.5 ml of plasma. The relative standard error of estimate of the calibration was typically 3%.

Diffuse solar radiation statistics for Italy

In this paper diffuse radiation is correlated with usually measured or more easy computable quantities in order to have a larger number of data available for the various applications of solar energy. Here are used two types of correlation: (a) diffuse radiation as a function of global and extraterrestrial radiation; (b) diffuse radiation as a function of ralative sunshine and extraterrestrial radiation. On the basis of the above correlations, empirical equations have been proposed and their coefficients have been calculated by fitting the experimental data of three Italian stations. The degree of accuracy of the fit has been estimated by a coefficient introduced and called by us “relative standard error of estimate.” In order to compare the proposed formulas, which have different degrees of freedom, it has been used the test of Gauss modified by us. The values of diffuse radiation obtained by the proposed relations agree very well with the experimental data.