Generation of stochastic mixed-mode oscillations in a pair of VDP oscillators with direct-indirect coupling.

Environmental noise can lead to complex stochastic dynamical behavior in nonlinear systems. In this paper, we studied the phenomenon of a pair of Van der Pol (VDP) oscillators with direct-indirect coupling affected by Gaussian white noise. That is to say, a noise-induced equilibrium transition oscillation was observed in three types of different parameter regions, where the deterministic system had two kinds of stable equilibrium points. Meanwhile, with the noise intensity increasing, we found that the stochastic system will constantly switch between two stable equilibrium points. To analyze the stochastic behavior, we used the stochastic sensitivity equation and confidence ellipse method. When the confidence ellipsoid crossed the boundary of the attraction basin of the equilibrium point, the system entered into the state of stochastic mixed-mode oscillations, which was consistent with the simulation results.

Application of chemometric tools in the development and sensory evaluation of gluten-free cracknel biscuits with the addition of chia seeds and turmeric powder.

Gluten-free biscuits were developed with the addition of chia seeds (Salvia hispanica L.) and turmeric powder. An experimental design 22 were employed in the formulation optimization that promotes better sensory acceptance through acceptance test with a hedonic scale of 9 points. For characterization purposes, the centesimal composition from chia seeds and the turmeric powder were determined. The biscuits were produced from an optimized formulation with and without chia seeds and turmeric powder with microbiological results safe for consumption by evaluation Salmonella sp., positive coagulase Staphylococcus, and Coliforms to 45 °C. The Principal Components Analysis (PCA) was used in the investigation of sensory results (color, flavor, texture, smell, appearance, overall impression). It was also considered the habits of consuming food with/without gluten, purchase intentions, including age and gender. The results show that there is no distinction between the biscuits with the addition of chia seeds and turmeric powder. A statistical test using the confidence ellipse confirms that there no significant difference, at a 95% confidence level, among the sensory results for the biscuits with and without chia seeds and turmeric powder.

Muscle-driven and torque-driven centrodes during modeled flexion of individual lumbar spines are disparate.

Lumbar spine biomechanics during the forward-bending of the upper body (flexion) are well investigated by both in vivo and in vitro experiments. In both cases, the experimentally observed relative motion of vertebral bodies can be used to calculate the instantaneous center of rotation (ICR). The timely evolution of the ICR, the centrode, is widely utilized for validating computer models and is thought to serve as a criterion for distinguishing healthy and degenerative motion patterns. While in vivo motion can be induced by physiological active structures (muscles), in vitro spinal segments have to be driven by external torque-applying equipment such as spine testers. It is implicitly assumed that muscle-driven and torque-driven centrodes are similar. Here, however, we show that centrodes qualitatively depend on the impetus. Distinction is achieved by introducing confidence regions (ellipses) that comprise centrodes of seven individual multi-body simulation models, performing flexion with and without preload. Muscle-driven centrodes were generally directed superior-anterior and tail-shaped, while torque-driven centrodes were located in a comparably narrow region close to the center of mass of the caudal vertebrae. We thus argue that centrodes resulting from different experimental conditions ought to be compared with caution. Finally, the applicability of our method regarding the analysis of clinical syndromes and the assessment of surgical methods is discussed.

Comparison between quantitative descriptive analysis and flash profile in profiling the sensory properties of commercial red sufu (Chinese fermented soybean curd).

BACKGROUND: Red sufu is a type of sufu produced by solid-state fermentation of soybean curd and coloration with red mold rice. The purposes of this study were: (i) to characterize commercial red sufu samples using the quantitative descriptive analysis (QDA) and flash profile (FP) by ten trained and ten untrained panelists, respectively; (ii) to compare the differences in panel performance, descriptive abilities and sensory maps between the two methodologies; and (iii) to compare the efficiency between QDA and FP using red sufu as the matrix. Techniques in multivariate analysis were utilized to explore the data. RESULTS: Results from generalized procrustes analysis (GPA) showed that panel performance by QDA was more repeatable and reached higher homogeneity than that by FP. Despite the confidence ellipse results of the 12 red sufus being better discriminated by QDA, the RV coefficient was high (RV = 0.852) between the configurations of the two-dimensional model (F1 and F2) of the two methodologies, indicating that the two methods are similar and closely related. Overall, QDA provided more accurate and detailed information, while FP provided a similar sensory map on product location and descriptive results. CONCLUSION: The FP technique appeared to be an efficient alternative approach to quickly evaluate sensory properties, including appearance, flavor, aroma and textural properties of an array of red sufu products. © 2018 Society of Chemical Industry.

Open source posturography.

CONCLUSION: The proposed validation goal of 0.9 in intra-class correlation coefficient was reached with the results of this study. With the obtained results we consider that the developed software (RombergLab) is a validated balance assessment software. The reliability of this software is dependent of the used force platform technical specifications. OBJECTIVE: Develop and validate a posturography software and share its source code in open source terms. METHODS: Prospective non-randomized validation study: 20 consecutive adults underwent two balance assessment tests, six condition posturography was performed using a clinical approved software and force platform and the same conditions were measured using the new developed open source software using a low cost force platform. Intra-class correlation index of the sway area obtained from the center of pressure variations in both devices for the six conditions was the main variable used for validation. RESULTS: Excellent concordance between RombergLab and clinical approved force platform was obtained (intra-class correlation coefficient =0.94). A Bland and Altman graphic concordance plot was also obtained. The source code used to develop RombergLab was published in open source terms.

The role of isotope ratio mass spectrometry as a tool for the comparison of physical evidence.

This paper considers how likelihood ratios can be derived for a combination of physical, chemical and isotopic measurements. Likelihood ratios were formulated based on the characteristics of a small convenience sample of 20 duct tapes. The propositions considered were: The physical and isotopic characteristics of ten rolls of duct tape were shown to be consistent throughout each roll. The width and thickness of the tapes and the density of the scrim fibres provided equivalent information and the combined physical characteristics provided a basis upon which to discriminate between many of the samples. Scatter-plots and confidence ellipses provided a convenient method to group the isotopic composition of the tape backing material and provided a basis to discriminate between samples which were physically indistinguishable. Considering both the physical and isotopic characteristics it was possible, at best, to ascertain that the evidence provided moderately strong support for the proposition that two samples of tape were derived from the same batch (LR=400). Kernel density estimates were used to model the distribution of isotopic compositions of the backing material. Using this technique it was possible to estimate objectively the probability that a sample with given characteristics could be drawn, at random, from the background population and to calculate a likelihood ratio based on the propositions above. The strength of evidence which could be presented by either model was ultimately limited by the size of the background sample.

Epileptic seizure classification in EEG signals using second-order difference plot of intrinsic mode functions.

Epilepsy is a neurological disorder which is characterized by transient and unexpected electrical disturbance of the brain. The electroencephalogram (EEG) is a commonly used signal for detection of epileptic seizures. This paper presents a new method for classification of ictal and seizure-free EEG signals. The proposed method is based on the empirical mode decomposition (EMD) and the second-order difference plot (SODP). The EMD method decomposes an EEG signal into a set of symmetric and band-limited signals termed as intrinsic mode functions (IMFs). The SODP of IMFs provides elliptical structure. The 95% confidence ellipse area measured from the SODP of IMFs has been used as a feature in order to discriminate seizure-free EEG signals from the epileptic seizure EEG signals. The feature space obtained from the ellipse area parameters of two IMFs has been used for classification of ictal and seizure-free EEG signals using the artificial neural network (ANN) classifier. It has been shown that the feature space formed using ellipse area parameters of first and second IMFs has given good classification performance. Experimental results on EEG database available by the University of Bonn, Germany, are included to illustrate the effectiveness of the proposed method.

Ellipse area calculations and their applicability in posturography.

The quantification of postural sway is considered to be an essential part of posturography and is important for research and clinical utility. A widely used method to calculate the scatter of center of pressure data is an ellipse that encloses about 100(1-α)% of the observations. However, underlying definitions and terminologies have been misused in many cases. Hence, outcomes of different studies are proved to be incommensurable. In order to attain inter-study comparability, standardization of calculation methods has to be advanced. This work features a comprehensive and consistent overview of the methods for elliptic area approximation contrasting general principles of confidence and prediction regions. As a result, we recommend the usage of the prediction ellipse, as far as we demonstrate that confidence ellipses emerge to be inappropriate for posturographic scatter evaluation. Furthermore, we point at problems that come along with different sample sizes.

Estimativas da qualidade de linhas poligonais topográficas / Quality estimations of topographical traverses

O objetivo deste artigo é descrever um procedimento que contribui com estimativas de qualidade de levantamento topográficos mediante a pré-análise e estimativas obtidas a partir de análise pós-ajustamento. As estimativas são dadas pelo teste qui-quadrado da forma quadrática do erro de fechamento, pelo teste qui-quadrado da forma quadrática dos resíduos obtidos no ajustamento pelo método dos mínimos quadrados, pelo teste data snooping de Baarda, pela elipse dos erros, pela elipse de confiança, pelo círculo do erro de posição e pelo círculo do erro médio. Estes conceitos são examinados por meio de valores numéricos no caso de uma linha poligonal simples implantada no campus da Universidade Federal de Santa Maria e medida com um taquímetro eletrônico.

The objective through this article is to describe a procedure that contributes with quality survey estimations by means pre-analysis survey and estimations by means post-adjustment. The estimations are given by the chi-square test of the quadratic form of misclosures, the chi-square of the quadratic form of residuals from the least-squares adjustment method, the Baarda's data snooping test, the standard ellipse, the confidence ellipse, position error circle and mean error circle. These concepts are examined through the numerical values provided in the case of a simple topographical traverse which was implanted at the Universidade Federal de Santa Maria Campus with electronic tachymeter.

Study of Copper and Purine-Copper Complexes on Modified Carbon Electrodes by Cyclic and Elimination Voltammetry.

Using a paraffin impregnated graphite electrode (PIGE) and mercury-modifiedpyrolytic graphite electrode with basal orientation (Hg-PGEb) copper(II) and Cu(II)-DNApurine base solutions have been studied by cyclic (CV) and linear sweep voltammetry(LSV) in connection with elimination voltammetry with linear scan (EVLS). In chlorideand bromide solutions (pH 6), the redox process of Cu(II) proceeded on PIGE with twocathodic and two anodic potentially separated signals. According to the eliminationfunction E4, the first cathodic peak corresponds to the reduction Cu(II) e⁻ → Cu(I) withthe possibility of fast disproportionation 2Cu(I) → Cu(II) Cu(0). The E4 of the secondcathodic peak signalized an electrode process controlled by a surface reaction. Theelectrode system of Cu(II) on Hg-PGEb in borate buffer (pH 9.2) was characterized by onecathodic and one anodic peak. Anodic stripping voltammetry (ASV) on PIGE and cathodicstripping voltammetry (CSV) on Hg-PGEb were carried out at potentials where thereduction of copper ions took place and Cu(I)-purine complexes were formed. By usingASV and CSV in combination with EVLS, the sensitivity of Cu(I)-purine complexdetection was enhanced relative to either ASV or CSV alone, resulting in higher peakcurrents of more than one order of magnitude. The statistical treatment of CE data wasused to determine the reproducibility of measurements. Our results show that EVLS inconnection with the stripping procedure is useful for both qualitative and quantitativemicroanalysis of purine derivatives and can also reveal details of studied electrodeprocesses.