When drugs are poorly soluble then, instead of the potentiometric determination of dissociation constants, pH-spectrophotometric titration can be used along with nonlinear regression of the absorbance response surface data. Generally, regression models are extremely useful for extracting the essential features from a multiwavelength set of data. Regression diagnostics represent procedures for examining the regression triplet (data, model, method) in order to check (a) the data quality for a proposed model; (b) the model quality for a given set of data; and (c) that all of the assumptions used for least squares hold. In the interactive, PC-assisted diagnosis of data, models and estimation methods, the examination of data quality involves the detection of influential points, outliers and high leverages, that cause many problems when regression fitting the absorbance response hyperplane. All graphically oriented techniques are suitable for the rapid estimation of influential points. The reliability of the dissociation constants for the acid drug silybin may be proven with goodness-of-fit tests of the multiwavelength spectrophotometric pH-titration data. The uncertainty in the measurement of the pK (a) of a weak acid obtained by the least squares nonlinear regression analysis of absorption spectra is calculated. The procedure takes into account the drift in pH measurement, the drift in spectral measurement, and all of the drifts in analytical operations, as well as the relative importance of each source of uncertainty. The most important source of uncertainty in the experimental set-up for the example is the uncertainty in the pH measurement. The influences of various sources of uncertainty on the accuracy and precision are discussed using the example of the mixed dissociation constants of silybin, obtained using the SQUAD(84) and SPECFIT/32 regression programs.

• MeSH
• Antioxidants analysis   chemistry   MeSH
• Time Factors MeSH
• Models, Chemical MeSH
• Financing, Organized MeSH
• Hydrogen-Ion Concentration MeSH
• Pharmaceutical Preparations chemistry   MeSH
• Least-Squares Analysis MeSH
• Regression Analysis MeSH
• Silymarin analysis   chemistry   MeSH
• Spectrophotometry methods   MeSH
• Drug Stability MeSH
• Titrimetry methods   MeSH

In this chapter, we demonstrate the advantage of the simultaneous multicurve nonlinear least-squares analysis over that of the conventional single-curve analysis. Fitting results are subjected to thorough Monte Carlo analysis for rigorous assessment of confidence intervals and parameter correlations. The comparison is performed on a practical example of simulated steady-state reaction kinetics complemented with isothermal calorimetry (ITC) data resembling allosteric behavior of rabbit muscle pyruvate kinase (RMPK). Global analysis improves accuracy and confidence limits of model parameters. Cross-correlation between parameters is also reduced with accompanying enhancement of the model-testing power. This becomes especially important for validation of models with "difficult" highly cross-correlated parameters. We show how proper experimental design and critical evaluation of data can improve the chance of differentiating models.

• MeSH
• Calorimetry MeSH
• Rabbits MeSH
• Monte Carlo Method MeSH
• Least-Squares Analysis MeSH
• Pyruvate Kinase chemistry   metabolism   MeSH
• Animals MeSH
• Check Tag
• Rabbits MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH

A variety of techniques of cell capacitance measurement have been proposed and applied in cellular electrophysiology. They are mostly based on the evaluation of membrane current responses to small changes in the membrane voltage. One of the currently used approaches applies the least-squares fit of an exponential current decay in response to voltage clamped rectangular pulses. In this study, we propose an alternative simpler approach to evaluation of the exponential parts in the current responses to square wave stimulation and present preliminary results of membrane capacitance evaluation. It is based on the property of the exponential function that has not yet been used to measure membrane capacitance. The time constant and the asymptote of the exponential waveform are unambiguously determined by the values read at three points separated by a constant time interval. In order to minimize the effect of noise and deviations from the exponential waveform, the triplet of points is designed to slide along the time axis. The results of the proposed approach and those previously evaluated by the least squares method are comparable. The method described may be advantageous for continuously recording changes in membrane capacitance.

• MeSH
• Algorithms MeSH
• Electric Capacitance MeSH
• Electric Conductivity MeSH
• Electrophysiology MeSH
• Rats MeSH
• Membrane Potentials physiology   MeSH
• Least-Squares Analysis MeSH
• Patch-Clamp Techniques methods   MeSH
• Models, Neurological MeSH
• Neurons MeSH
• Computer Simulation MeSH
• Reproducibility of Results MeSH
• Software MeSH
• Heart Atria pathology   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

OBJECTIVE: T2 maps are more vendor independent than other MRI protocols. Multi-echo spin-echo signal decays to a non-zero offset due to imperfect refocusing pulses and Rician noise, causing T2 overestimation by the vendor's 2-parameter algorithm. The accuracy of the T2 estimate is improved, if the non-zero offset is estimated as a third parameter. Three-parameter Levenberg-Marquardt (LM) T2 estimation takes several minutes to calculate, and it is sensitive to initial values. We aimed for a 3-parameter fitting algorithm that was comparably accurate, yet substantially faster. METHODS: Our approach gains speed by converting the 3-parameter minimisation problem into an empirically unimodal univariate problem, which is quickly minimised using the golden section line search (GS). RESULTS: To enable comparison, we propose a novel noise-masking algorithm. For clinical data, the agreement between the GS and the LM fit is excellent, yet the GS algorithm is two orders of magnitude faster. For synthetic data, the accuracy of the GS algorithm is on par with that of the LM fit, and the GS algorithm is significantly faster. The GS algorithm requires no parametrisation or initialisation by the user. DISCUSSION: The new GS T2 mapping algorithm offers a fast and much more accurate off-the-shelf replacement for the inaccurate 2-parameter fit in the vendor's software.

• MeSH
• Algorithms MeSH
• Time Factors MeSH
• Phantoms, Imaging MeSH
• Image Interpretation, Computer-Assisted methods   MeSH
• Humans MeSH
• Magnetic Resonance Imaging * MeSH
• Least-Squares Analysis MeSH
• Prostatic Neoplasms diagnostic imaging   MeSH
• Image Processing, Computer-Assisted methods   MeSH
• Signal-To-Noise Ratio MeSH
• Probability MeSH
• Regression Analysis MeSH
• Reproducibility of Results MeSH
• Software MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Publication type
• Journal Article MeSH

Seed germination traits in alpine grasslands are poorly understood, despite the sensitivity of these communities to climate change. We hypothesise that germination traits predict species occurrence along the alpine-subalpine elevation gradient. Phylogenetic comparative analyses were performed using fresh seeds of 22 species from alpine and subalpine grasslands (1600-2400 m) of the Cantabrian Mountains, Spain (43° N, 5° W). Laboratory experiments were conducted to characterise germinability, optimum germination temperature and effect of cold and warm stratification on dormancy breaking. Variability in these traits was reduced by phylogenetic principal component analysis (phyl.PCA). Phylogenetic generalised least squares regression (PGLS) was used to fit a model in which species average elevation was predicted from their position on the PCA axes. Most subalpine species germinated in snow-like conditions, whereas most alpine species needed accumulation of warm temperatures. Phylogenetic signal was low. PCA1 ordered species according to overall germinability, whilst PCA2 ordered them according to preference for warm or cold germination. PCA2 significantly predicted species occurrence in the alpine-subalpine gradient, as higher elevation species tended to have warmer germination preferences. Our results show that germination traits in high-mountain grasslands are closely linked to the alpine-subalpine gradient. Alpine species, especially those from stripped and wind-edge communities, prefer warmer germination niches, suggesting that summer emergence prevents frost damage during seedling establishment. In contrast, alpine snowfield and subalpine grassland plants have cold germination niches, indicating that winter emergence may occur under snow to avoid drought stress.

• MeSH
• Phylogeny MeSH
• Germination * MeSH
• Climate Change MeSH
• Cold Temperature MeSH
• Droughts MeSH
• Grassland MeSH
• Seasons MeSH
• Seeds genetics   physiology   MeSH
• Seedlings genetics   physiology   MeSH
• Temperature MeSH
• Tundra MeSH
• Plant Dormancy MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH
• Geographicals
• Spain MeSH

This paper presents a new size estimation method that can be used to estimate size level for software engineering projects. The Algorithmic Optimisation Method is based on Use Case Points and on Multiple Least Square Regression. The method is derived into three phases. The first phase deals with calculation Use Case Points and correction coefficients values. Correction coefficients are obtained by using Multiple Least Square Regression. New project is estimated in the second and third phase. In the second phase Use Case Points parameters for new estimation are set up and in the third phase project estimation is performed. Final estimation is obtained by using newly developed estimation equation, which used two correction coefficients. The Algorithmic Optimisation Method performs approximately 43% better than the Use Case Points method, based on their magnitude of relative error score. All results were evaluated by standard approach: visual inspection, goodness of fit measure and statistical significance.

• MeSH
• Algorithms * MeSH
• Data Interpretation, Statistical * MeSH
• Humans MeSH
• Regression Analysis * MeSH
• Software MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Alienoptera is an insect order recently described from mid-Cretaceous amber [1] and is phylogenetically nested in the Dictyoptera lineage. Alienoptera currently comprises three species: Alienopterus brachyelytrus[1], Alienopterella stigmatica[2] and Caputoraptor elegans[3]. The most interesting is Caputoraptor elegans, which was recently described in Current Biology by Bai and colleagues [3] and which has an unusual cephalo-thoracic device formed by wing-like extensions of the genae and the corresponding edges of the pronotum. Bai and colleagues [3] suggested that the cephalo-thoracic apparatus may have been used to hold the female and male together during copulation. According to this possible function, the cephalo-thoracic apparatus of the female would fit together with the spread forewings of the male while the female was on the back of the male during copulation. This function was proposed based on examination of females and nymphs, and the authors stated that it could be falsified if a male with a similar apparatus were discovered. After examining a male nymph of this species (Figure 1), I here suggest that the cephalo-thoracic apparatus was not used for copulation but was instead used for predation and feeding.

• MeSH
• Phylogeny MeSH
• Amber MeSH
• Nymph anatomy & histology   growth & development   physiology   MeSH
• Predatory Behavior * MeSH
• Cockroaches anatomy & histology   growth & development   physiology   MeSH
• Fossils anatomy & histology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Animals MeSH
• Publication type
• Letter MeSH
• Research Support, Non-U.S. Gov't MeSH

• Keywords
• SPSS 6.1,

• Conspectus
• Lékařské vědy. Lékařství
• NML Fields
• lékařská informatika

Cieľom štúdie bolo popísať vzťah medzi prostredím školy a telesnou zdatnosťou študentov vybraných stredných škôl. Do štúdie boli zapojení študenti a študentky dvanástich náhodne vybraných stredných škôl Prešovského samospravného kraja. Do výskumu bolo zapojených 705 študentov (287 dievčat, 418 chlapcov). Kvalita materiálneho vybavenia a prostredia školy bola hodnotená na základe použitia dotazníka vypracovaného v rámci Texas youth fitness project. Na základe použitia FITNESSGRAMU sme získali údaje o svalovej sile, vytrvalosti, flexibilite a BMI. Vzťah medzi faktormi prostredia a telesnou zdatnosťou študentov sme zisťovali pomocou regresie, ktorá ukázala malé rozdiely medzi jednotlivými školami. Výsledky naznačujú pozitívny vplyv stupňa vzdelania učiteľa, jeho účasti na konferenciách a veľkosti tried študentov na vybrané parametre telesnej zdatnosti študentov.

The purpose of this study was to determine the association between physical education environment and physical fitness levels of students at selected Slovak high schools. Methods: For the purposes of the study, 12 high schools in the Prešov region were selected via cluster sampling. To determine the association between physical education environment and physical fitness levels, 705 students (287 girls, 418 boys) participated in the study. The quality of physical education classes was assessed using selected items of a questionnaire used in a Texas youth fitness project, each school’s physical education environment and policy survey. Data on muscular strength, endurance, flexibility and BMI were collected using the FITNESSGRAM test protocol. To determine the effect of school physical education environment on fitness levels, ordinary least squares regression was used. Analysis of the association between school physical education environment and fitness levels showed minimal differences. The results indicated positive effects of qualified teachers and class size on fitness level measured by selected items of the FITNESSGRAM test battery in high school students. The educational attainment and participation in conferences by teachers and the number of students per class appeared to be the most significant predictors affecting the physical fitness of high school students.

• Keywords
• kvalita výuky, Fitnessgram,
• MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Schools MeSH
• Physical Education and Training * MeSH
• Physical Fitness * MeSH
• Check Tag
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Female MeSH
• Publication type
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Geographicals
• Slovakia MeSH

Carefully controlled gas exchange across the eggshell is essential for the development of the avian embryo. Water vapour conductance (G(H2O)) across the shell, typically measured as mass loss during incubation, has been demonstrated to optimally ensure the healthy development of the embryo while avoiding desiccation. Accordingly, eggs exposed to sub-optimal gas exchange have reduced hatching success. We tested the association between eggshell G(H2O) and putative life-history correlates of adult birds, ecological nest parameters and physical characteristics of the egg itself to investigate how variation in G(H2O) has evolved to maintain optimal water loss across a diverse set of nest environments. We measured gas exchange through eggshell fragments in 151 British breeding bird species and fitted phylogenetically controlled, general linear models to test the relationship between G(H2O) and potential predictor parameters of each species. Of our 17 life-history traits, only two were retained in the final model: wet-incubating parent and nest type. Eggs of species where the parent habitually returned to the nest with wet plumage had significantly higher G(H2O) than those of parents that returned to the nest with dry plumage. Eggs of species nesting in ground burrows, cliffs and arboreal cups had significantly higher G(H2O) than those of species nesting on the ground in open nests or cups, in tree cavities and in shallow arboreal nests. Phylogenetic signal (measured as Pagel's λ) was intermediate in magnitude, suggesting that differences observed in the G(H2O) are dependent upon a combination of shared ancestry and species-specific life history and ecological traits. Although these data are correlational by nature, they are consistent with the hypothesis that parents constrained to return to the nest with wet plumage will increase the humidity of the nest environment, and the eggs of these species have evolved a higher G(H2O) to overcome this constraint and still achieve optimal water loss during incubation. We also suggest that eggs laid in cup nests and burrows may require a higher G(H2O) to overcome the increased humidity as a result from the confined nest microclimate lacking air movements through the nest. Taken together, these comparative data imply that species-specific levels of gas exchange across avian eggshells are variable and evolve in response to ecological and physical variation resulting from parental and nesting behaviours.

• MeSH
• Species Specificity MeSH
• Phylogeny MeSH
• Nesting Behavior physiology   MeSH
• Birds genetics   physiology   MeSH
• Egg Shell physiology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH