In this paper, we combine polynomial functions, Generalized Estimating Equations, and bootstrap-based model selection to test for signatures of linear or nonlinear relationships between body surface temperature and am...In this paper, we combine polynomial functions, Generalized Estimating Equations, and bootstrap-based model selection to test for signatures of linear or nonlinear relationships between body surface temperature and ambient temperature in endotherms. Linearity or nonlinearity is associated with the absence or presence of cutaneous vasodilation and vasoconstriction, respectively. We obtained experimental data on body surface temperature variation from a mammalian model organism as a function of ambient temperature using infrared thermal imaging. The statistical framework of model estimation and selection successfully detected linear and nonlinear relationships between body surface temperature and ambient temperature for different body regions of the model organism. These results demonstrate that our statistical approach is instrumental to assess the complexity of thermoregulation in endotherms.展开更多
The aim of this paper is to prove the existence of one or multiple solutions of nonlinear difference equations coupled to a general set of boundary conditions.Before to do this,we construct a discrete operator whose f...The aim of this paper is to prove the existence of one or multiple solutions of nonlinear difference equations coupled to a general set of boundary conditions.Before to do this,we construct a discrete operator whose fixed points coincide with the solutions of the problem we are looking for.Moreover,we introduce a strong positiveness condition on the related Green's function that allows us to construct suitable cones where to apply adequate fixed point theorems.Once we have the general existence result,we deduce,as a particular case,the existence of solutions of a second order difference equation with nonlocal perturbed Dirichlet conditions.展开更多
Determining the levels of heavy metals in honey is a measure to control its quality. The objective of this study was to determine the contents of Cd, Cu, Pb and Zn in honey of stingless bee. The differential pulse ano...Determining the levels of heavy metals in honey is a measure to control its quality. The objective of this study was to determine the contents of Cd, Cu, Pb and Zn in honey of stingless bee. The differential pulse anodic stripping voltammetry (DPASV) was used to determine the trace elements in honey samples. Pb was detected in 100% of the samples, Cu and Zn in 98.15%, and Cd only in 33.33%. The trace elements analyzed detected in the samples remained within tolerable levels in foods for human consumption.展开更多
The novel of COVID-19 disease started in late 2019 making the worldwide governments came across a high number of critical and death cases,beyond constant fear of the collapse in their health systems.Since the beginnin...The novel of COVID-19 disease started in late 2019 making the worldwide governments came across a high number of critical and death cases,beyond constant fear of the collapse in their health systems.Since the beginning of the pandemic,researchers and authorities are mainly concerned with carrying out quantitative studies(modeling and predictions)overcoming the scarcity of tests that lead us to under-reporting cases.To address these issues,we introduce a Bayesian approach to the SIR model with correction for underreporting in the analysis of COVID-19 cases in Brazil.The proposed model was enforced to obtain estimates of important quantities such as the reproductive rate and the average infection period,along with the more likely date when the pandemic peak may occur.Several under-reporting scenarios were considered in the simulation study,showing how impacting is the lack of information in the modeling.展开更多
In this paper, methods based on ranks and signs for estimating the parameters of thefirst-order integer-valued autoregressive model in the presence of additive outliers are proposed. In particular, we use the robust s...In this paper, methods based on ranks and signs for estimating the parameters of thefirst-order integer-valued autoregressive model in the presence of additive outliers are proposed. In particular, we use the robust sample autocorrelations based on ranks and signsto obtain estimators for the parameters of the Poisson INAR(1) process. The effects ofadditive outliers on the estimates of parameters of integer-valued time series are examined. Some numerical results of the estimators are presented with a discussion of theobtained results. The proposed methods are applied to a dataset concerning the numberof different IP addresses accessing the server of the pages of the Department of Statistics of the University of Würzburg. The results presented here give motivation to use themethodology in practical situations in which Poisson INAR(1) process contains additiveoutliers.展开更多
文摘In this paper, we combine polynomial functions, Generalized Estimating Equations, and bootstrap-based model selection to test for signatures of linear or nonlinear relationships between body surface temperature and ambient temperature in endotherms. Linearity or nonlinearity is associated with the absence or presence of cutaneous vasodilation and vasoconstriction, respectively. We obtained experimental data on body surface temperature variation from a mammalian model organism as a function of ambient temperature using infrared thermal imaging. The statistical framework of model estimation and selection successfully detected linear and nonlinear relationships between body surface temperature and ambient temperature for different body regions of the model organism. These results demonstrate that our statistical approach is instrumental to assess the complexity of thermoregulation in endotherms.
基金partially supported by Xunta de Galicia(Spain),project EM2014/032 and AIE,Spain and FEDER,grant MTM2016-75140-Psupported by the Bulgarian National Science Fundation under Project DN 12/4“Advanced Analytical and Numerical Methods for Nonlinear Differential Equations with Applications in Finance and Environmental Pollution”,2017。
文摘The aim of this paper is to prove the existence of one or multiple solutions of nonlinear difference equations coupled to a general set of boundary conditions.Before to do this,we construct a discrete operator whose fixed points coincide with the solutions of the problem we are looking for.Moreover,we introduce a strong positiveness condition on the related Green's function that allows us to construct suitable cones where to apply adequate fixed point theorems.Once we have the general existence result,we deduce,as a particular case,the existence of solutions of a second order difference equation with nonlocal perturbed Dirichlet conditions.
文摘Determining the levels of heavy metals in honey is a measure to control its quality. The objective of this study was to determine the contents of Cd, Cu, Pb and Zn in honey of stingless bee. The differential pulse anodic stripping voltammetry (DPASV) was used to determine the trace elements in honey samples. Pb was detected in 100% of the samples, Cu and Zn in 98.15%, and Cd only in 33.33%. The trace elements analyzed detected in the samples remained within tolerable levels in foods for human consumption.
文摘The novel of COVID-19 disease started in late 2019 making the worldwide governments came across a high number of critical and death cases,beyond constant fear of the collapse in their health systems.Since the beginning of the pandemic,researchers and authorities are mainly concerned with carrying out quantitative studies(modeling and predictions)overcoming the scarcity of tests that lead us to under-reporting cases.To address these issues,we introduce a Bayesian approach to the SIR model with correction for underreporting in the analysis of COVID-19 cases in Brazil.The proposed model was enforced to obtain estimates of important quantities such as the reproductive rate and the average infection period,along with the more likely date when the pandemic peak may occur.Several under-reporting scenarios were considered in the simulation study,showing how impacting is the lack of information in the modeling.
文摘In this paper, methods based on ranks and signs for estimating the parameters of thefirst-order integer-valued autoregressive model in the presence of additive outliers are proposed. In particular, we use the robust sample autocorrelations based on ranks and signsto obtain estimators for the parameters of the Poisson INAR(1) process. The effects ofadditive outliers on the estimates of parameters of integer-valued time series are examined. Some numerical results of the estimators are presented with a discussion of theobtained results. The proposed methods are applied to a dataset concerning the numberof different IP addresses accessing the server of the pages of the Department of Statistics of the University of Würzburg. The results presented here give motivation to use themethodology in practical situations in which Poisson INAR(1) process contains additiveoutliers.
