Thermovision diagnostics in chosen spine diseases treated by whole body cryotherapy

The non-invasive infrared technique was used in case of the thermal imaging of patients suffering from spine diseases. Measurements were performed for the group of 50 patients during whole body cryotherapy at the second, fifth and tenth day of the rehabilitation cycle. An enhancement of the profile of skin temperature due to body cooling caused an increase in the diagnostic sensitivity of thermovision. The temperature parameters such as temperature contrast (ΔT = T _max ? T _min) and relative change of contrast ratio defined as (ΔT)/(T _mean) in the region of interest (ROI’s) were used to point out differences between the healthy patients and patients suffering from ankylosing spondylitis, sciatica and spondyloarthrosis. The value of the thermovision diagnostic in the case of spine diseases was confirmed by statistical analysis.     

A kernel‐based method to determine optimal sampling times for the simultaneous estimation of the parameters of rival mathematical models

When several models are proposed for one and the same process, experimental design techniques are available to design optimal discriminatory experiments. However, because the experimental design techniques are model‐based, it is important that the required model predictions are not too uncertain. This uncertainty is determined by the quality of the already available data, since low‐quality data will result in poorly estimated parameters, which on their turn result in uncertain model predictions. Therefore, model discrimination may become more efficient and effective if this uncertainty is reduced first. This can be achieved by performing dedicated experiments, designed to increase the accuracy of the parameter estimates. However, performing such an additional experiment for each rival model may undermine the overall goal of optimal experimental design, which is to minimize the experimental effort. In this article, a kernel‐based method is presented to determine optimal sampling times to simultaneously estimate the parameters of rival models in a single experiment. The method is applied in a case study where nine rival models are defined to describe the kinetics of an enzymatic reaction (glucokinase). The results clearly show that the presented method performs well, and that a compromise experiment is found which is sufficiently informative to improve the overall accuracy of the parameters of all rival models, thus allowing subsequent design of an optimal discriminatory experiment. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009     

Application of non-linear regression methods for the estimation of common kinetic parameters from several thermoanalytical curves

Novel methods of unified evaluation of two (or more) thermogravimetric curves have been worked out on the basis of known non-linear parameter estimating procedures (Gauss-Newton-Marquardt-type regression and the direct integral method of Valkó and Vajda were adapted). Their ability to provide estimate for common kinetic parameters of several TG (m?T) or DTG (dm/dt-T) curves were tested for pairs of curves of different heating rates, and for repeated curves of the same heating rate, obtained for the decomposition of CaCO₃ in open crucible. In these cases the Arrhenius terms and then-th order model functions were assumed. The fitting ability of estimations made for single curves and for pairs of curves sharing different number of parameters, was judged on the base of residual deviations (S _res ) and compared to the standard deviation of the measurements. In the case of different heating rates, the two curves could not be described with the assumption of three common parameters, because of the minimum residual deviation was very high. However, sharing of activation energy and preexponential term only, and applying different exponents for the two curves, provided a satisfactory fit by our methods. Whilst in the case of repeated curves, we could find such a common three-parameter set, which has a residual deviation comparable with the standard deviation of the measurements. Because of their flexibility (taking into account the variable number of common parameters and the versatile forms of model equations), these methods seem to be promising means for unified evaluation of several related thermoanalytical curves.     

Effective search of starting values for kinetic parameters estimation

For the calculation of kinetic parameters from thermal data files numeric optimization has been well introduced. But suitable starting values near the global minimum of the sum of deviation squares are needed for a successfully parameter estimation. Namely the search for starting values requires a lot of time and diminishes the effectiveness of the total procedure. Therefore we have developed an algorithm of the automatic search of starting values for the optimization of activation energy end frequency factor of a chemical reaction.This search procedure uses the knowledge of the specific course of the correspondingSDS surface in the near of its global minimum. In this area theSDS describes two plateaus separated by a narrow valley. The search procedure avoids starting values at one of these plateaus. This PC program is part of the complex software package TA-kin v3.3 for kinetic evaluation of thermal measurements.     

Real-time recursive estimation of statistical parameters

Recursive algorithms for the computation of standard deviation and average deviation are derived and their applications in data acquisition are discussed. The relative speeds and accuracies of the two algorithms are compared for synthetic data. The performance of recursive estimation under shot and proportional noise limitations is also described. As an example of the utility of these algorithms, absorbance data with constant confidence intervals are collected regardless of incident and transmitted intensities. The desired precision is specified prior to data acquisition and used to control signal-averaging of the data in real time.     

Application of AIM parameters at ring critical points for estimation of pi-electron delocalization in six-membered aromatic and quasi-aromatic rings

The AIM parameters at the ring critical point (the electron density and its Laplacian, the total electron energy density and both its components, potential and kinetic electron energy densities), have been intercorrelated with aromaticity indices: the geometry-based HOMA and the magnetism-based NICS, NICS(1), and NICS(1)(zz). A set of 33 phenylic rings having possibly a diversified aromatic character, and a set of 20 quasi-rings formed by intramolecular hydrogen and lithium bonds, have been taken into consideration. It has been found that the density of total electron energy, H, may serve as a new quantitative characteristic of pi-electron delocalization. The dependences between H values and aromaticity indices are correlated (cc(H/HOMA)=0.99, cc(H/NICS(1)zz)=0.95).     

On mesh-based Ewald methods: optimal parameters for two differentiation schemes

The particle-particle particle-mesh Ewald method for the treatment of long-range electrostatics under periodic boundary conditions is reviewed. The optimal Green's function for exact (real-space differentiation), which differs from that for reciprocal-space differentiation, is given. Simple analytic formulas are given to determine the optimal Ewald screening parameter given a differentiation scheme, a real-space cutoff, a mesh spacing, and an assignment order. Simulations of liquid water are performed to examine the effect of the accuracy of the electrostatic forces on calculation of the static dielectric constant. A target dimensionless root-mean-square error of 10(-4) is sufficient to obtain a well-converged estimate of the dielectric constant.     

Determination of optimal parameters in the convolution difference resolution enhancement technique

The relationship between the relative resolution, sensitivity and line distortion of convolution difference spectra and the values for the adjustable parameters k and n is investigated. A practical guideline for obtaining optimum results is given.     

Alternative approaches for the estimation of the band broadening parameters in single-detection size exclusion chromatography

New approaches for the determination of the extent of symmetric and asymmetric band broadening (BB) in size exclusion chromatography (SEC) are presented. For this purpose raw data was simulated by starting with either a theoretical Poisson number chain length distribution (NCLD), or a log-normal weight chain length distribution (WCLD). Each distribution was first converted to a BB-free mass chromatogram, as typically obtained from a standard differential refractive index detector. Then, the broadened (or "measured") chromatograms were simulated by convoluting the BB-free chromatograms with a BB function, which was assumed to follow symmetrical (Gauss) as well as unsymmetrical (exponentially modified Gauss) function. A broad range of BB parameters (standard deviation, sigma(BB), and exponential decay, tau(BB)) was used for the simulations. The approaches are based on the determination of the points of inflection belonging to the peak of the broadened chromatogram, and closed as well as empirically derived equations connecting the peak width, its variance, and the parameters sigma(BB) and tau(BB). The developed methods are applicable for Poisson distributions well above a peak chain length of 100.     

Thin film platinum cuff electrodes for neurostimulation: in vitro approach of safe neurostimulation parameters

Thin film technology takes more and more importance in the development of biomedical devices dedicated to functional neurostimulation. Our research about the design of implant neurostimulating electrode is oriented toward thin film cuff electrodes based on a polyimide substrate covered by a chromium/gold/Pt film. The chromium/gold sputtered film serves as adhesion layer and current collector whereas platinum acts as an electrochemical actuator. The electrode surface has been designed to obey safe stimulation criteria (i.e. chemically inert noble metal, low electrode-electrolyte impedance, high electrochemical reversibility, high corrosion stability). The electrochemical behaviour of such platinum electrodes has been assessed and compared to a foil of platinum. Extensive in vitro characterisations of the both electrode types were carried out using AFM, SEM and electrochemical techniques. The role of enhanced surface roughness enabling high double layer capacitances to be achieved was clearly highlighted. The obtained results are discussed, with particular reference to thin film electrodes stability under in vitro electrical stimulation in NaCl 0.9% (physiological serum). Therefore, these thin film devices showed reversible PtOH formation and decomposition making them potentially attractive for the fabrication of implant stimulation cuff electrodes.     

A new method for simultaneous estimation of micellization parameters from conductometric data

A simple method for determination of the counterion binding parameter (alpha) and aggregation number (N) from conductivity data is proposed. The method is based on fitting the values of the first derivative of conductivity (kappa) versus total surfactant concentration (c(t)) function according to the equation derived from the mass action model (MAM) by using different conductivity models. Sodium dodecylsulphate (SDS) and dodecyltrimethylammonium bromide (DTAB) were chosen for validation of the proposed method. It was shown that the method gives a fairly accurate values for micellisation parameters of SDS (N=51-64, alpha=0.74-0.75) and DTAB (N=56-62, alpha=0.77-0.79), both in good agreement with the literature data. In addition, application of the proposed method does not require the value of the critical micelle concentration (cmc).     

Stoichiometry,Ringbom optimal range,and other parameters for the copper(I)-bathocuproine complex

The stoichiometry of the copper(I)-bathocuproine complex is studied and encountered to be in a 1:2 molar ratio.The Ringbom optimal range falls between 0.7 and 4.0 × 10^?6 g of copper ml^?1.Beer's law is obeyed over the range of 0.2–4.4 × 10^?6 g of copper ml^?1, and the molar absorptivity is 1.3 × 10⁴ liters mol^?1 cm^?1.The standard deviation, calculated from 10 determinations on a solution containing 2 × 10^?6 g of copper ml^?1, is 0.020.Thè bathocuproine solvent is changed from ethanol to chloroform.The influence of foreign ions is studied and compared with the results of other authors.     

Application of thermal imaging to assess the superficial skin temperature distribution after local cryotherapy and ultrasound

Thermal imaging is a safe, noninvasive, and quite low-cost technique that allows for the rapid and noninvasive recording of thermal radiation emitted by the human body. In recent years, it is increasingly used for physiotherapy monitoring. The main goal of the study was to compare the influence of two various treatments applied in two various orders, namely local cryotherapy (CRYO) and ultrasound therapy (US). The impact of combined therapies, applied in two various orders, was studied in terms of changes of the superficial temperature distribution on the front right thigh surface. The response to the therapy depending the treated persons’ gender, along with a consensual reaction, was examined. The research material consisted of 30 healthy volunteers, 19–23-year old students, aged 19.93 (± 1.42). All treatments were performed at weekly intervals in the following order: in the first week, CRYO immediately followed by US, and in the second week, ultrasound immediately followed by local cryotherapy. All treatments were performed on the right quadriceps. The combined sequence of local cryotherapy and ultrasound therapy caused temperature decrease in the treated area regardless of their performance order. The temperature decrease considerably depends on the sequence of the applied treatments, and it was more significant after the ultrasound–cryotherapy sequence. Moreover, these changes also lasted longer. Statistically significant influence of the subjects’ gender was observed in case of consensual reaction.     

Experimental estimation of the energy parameters of molecular interactions in soils

The feasibility of determining the parameters of solid-phase particle-adsorbed moisture interlayer molecular interactions in soil from the isotherms of water vapor sorption and the data on the compressive strength of soil particle aggregates are discussed. The calculations are based on the fundamental physicochemical laws, that is, the Gibbs equation for substance adsorption and the Griffith equation for brittle deformations. The obtained characteristics of molecular interactions (the Hamaker complex constants) vary over a narrow range (0.9–2.3) × 10⁻¹⁹ J for soils with different dispersities.     

Interval estimation in the determination of parameters of a kinetic model

The degree of uncertainty in the parameters of a kinetic model resulting from the experimental erros is discussed. For this purpose, the concept of interval estimation of the parameters is introduced and a method given for their determination. The method is illustrated in the determination of the kinetic constants for olefin dehydrogenation.

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Analytical method for assessing exposure of greenhouse applicators to procymidone by gas chromatography and whole body dosimetry

Summary An analytical method for the determination of the potential and actual exposure of agricultural workers to procymidone has been developed. The methodology is based on the whole body technique, using Tyvek Pro-Tech and Sontara as sampling media, and uses hexane extraction, GC-ECD analysis and GC-MSD confirmation. The validation of the analytical method has been carried out incorporating the matrix of coverall in all steps when calculating parameters such as retention time window, limits of detection and quantification, linear ranges and precision. A field sampling strategy has also been developed and the method has been applied to the evaluation of the potential and actual dermal exposure of an applicator and an assistant in normal working conditions.     

A software for the estimation of binding parameters of biochemical equilibria based on statistical probability model

An algorithm is proposed for the estimation of binding parameters for the interaction of biologically important macromolecules with smaller ones from electrometric titration data. The mathematical model is based on the representation of equilibria in terms of probability concepts of statistical molecular thermodynamics. The refinement of equilibrium concentrations of the components and estimation of binding parameters (log site constant and cooperativity factor) is performed using singular value decomposition, a chemometric technique which overcomes the general obstacles due to near singularity. The present software is validated with a number of biochemical systems of varying number of sites and cooperativity factors. The effect of random errors of realistic magnitude in experimental data is studied using the simulated primary data for some typical systems. The safe area within which approximate binding parameters ensure convergence has been reported for the non-self starting optimization algorithms.     

Design of the optimal sector device and determination of its parameters in gas electron diffraction

This work presents a way to select the optimal form of the sector lobe and practical algorithms to determine the sector function of the device in use. Knowledge of the sector function enhances the quality of drawing a background line and ensures the division of multiplicative and additive noise components, thus increasing the reliability of structural parameters determined by gas electron diffraction.