Discrimination of axonal neuropathy using sensitivity and specificity statistical measures

In needle electromyography, general mathematical methods of pattern recognition and signal analysis can be used to detect motor unit potentials and to classify various types of muscle diseases. The goal of the paper is to contribute to various methods enabling discrimination of individuals with axonal neuropathy (a positive set) from normal cases (a control set) using signals acquired from muscle activities. Data from a control set of 104 individuals and a set of 76 patients were used to validate selected methods of their separation and classification. Different features in both the time and frequency domains were studied to obtain the most reliable results . This novel approach involves comparison of individual features based on adaptive signal thresholding, as well as their combination, using supervised sigmoidal neural networks for their classification. Specificity, sensitivity and accuracy of the features used to detect individuals with axonal neuropathy was analysed using the receiver operating characteristic curves and confusion analysis. An accuracy higher than 93 % was achieved for the given sets of individuals and the optimal criterion values. The proposed modified Willison amplitude together with statistical and spectral properties of signal components classified individuals into sets of healthy and neuropathic patients by artificial neural networks with sensitivity 96.1 % and sufficient accuracy in the wide range of criterion values.     

Multivariate online kernel density estimation with Gaussian kernels

We propose a novel approach to online estimation of probability density functions, which is based on kernel density estimation (KDE). The method maintains and updates a non-parametric model of the observed data, from which the KDE can be calculated. We propose an online bandwidth estimation approach and a compression/revitalization scheme which maintains the KDE's complexity low. We compare the proposed online KDE to the state-of-the-art approaches on examples of estimating stationary and non-stationary distributions, and on examples of classification. The results show that the online KDE outperforms or achieves a comparable performance to the state-of-the-art and produces models with a significantly lower complexity while allowing online adaptation.     

Comparison of two micromechanical models for predicting elasto-plastic response of wood–plastic composites

The mechanical response of wood- and cellulose-filled polymers and its comparison to analytical models is studied in this article. To model the elasto-plastic response of the wood–plastic composite (WPC), two explicit semi-analytical micromechanical methods were used: Mori–Tanaka Method (MTM) and Generalised Method of Cells (GMC). For experimental purpose, several test specimens composed of matrix polypropylene (PP) or polystyrene (PS) and filled with wood or cellulose short fibres of different length to width aspect ratio and various volume fractions were injection moulded. Tensile testing was then used to gain experimental data, which were then compared to the calculated prediction of proposed micromechanical models to test their applicability. The comparison of results show that both methods can accurately predict the response of the composite in the elastic area; however Mori–Tanaka Method can achieve better results when forecasting plastic deformations of wood–plastic composites.     

Comparison of selected physical and mechanical properties of densified beech wood plasticized by ammonia and saturated steam

Gaseous ammonia treatment in combination with densification of wood has been known for several decades, but these days there is no industrial production of materials modified in this way; also, little has been published in this area of wood science. In this study, selected physical and mechanical properties, i.e. density profile, bending strength, hardness and moisture absorption were investigated for Lignamon (1), which was obtained from the Czech industrial production. Selected properties were also investigated using steam-densified beech (2) and native beech (3) and compared with each other. Densitometry of Lignamon showed a large variability in the density profile compared to that of only densified beech. It is affected by the degree of densification, temperature and moisture gradients, and their relationship to the glass transition of the wood cell wall. Modulus of elasticity, hardness, moisture exclusion and anti-swelling efficiency of Lignamon are enhanced compared to densified beech. The enhanced dimensional stability and lower hygroscopicity of Lignamon are probably caused by heat treatment during the process. Further investigation will be carried out with self-produced Lignamon samples.     

Channel Estimation Method for OFDM in Low SNR Based on Two-dimensional Spreading

In this paper, we present a channel estimation method based on two-dimensional signal spreading applicable to orthogonal frequency multiple access multicarrier systems. Our method exploits a spreading of a transmitted data signal as well as a pilot signal over the assigned frequency range and time period. As a spreading sequence we exploited orthogonal Walsh–Hadamard sequences. When compared with traditional pilot symbol based channel estimation, our method is beneficial in low signal to noise ratio (SNR). For a comparison of our method with state-of-the-art channel estimation method, we utilized an open source LTE downlink simulator developed at TU Vienna. This enables a reproducibility of our results. Considering the LTE system, our method outperforms the traditional approach in typical range of SNR from \(-\) 5 to 10 dB. For a comparison of a throughput performance, a number of channel models has been employed.     

Relation between blood hydrolases and small-intestinal contents

Absorption of enzymes in the small intestine and some mechanisms providing the enzymatic homeostasis in the body were studied in isolated portions of the small intestine of rats in chronic experiments on rats and dogs, and in clinically observed subjects. A conclusion has been made that under normal conditions the level of enzyme resorption is low, and it is localized in the distal portions of the small intestine. Changes in the hydrolytic activity of blood and urine are the result of not only the resorption of pancreatic enzymes from the small intestine, but also of the shifts in their incretion by the pancreas when enzymes are introduced into the duodenum, and the secretion of enzymes in the pancreatic juice is lowered, while their incretion by the pancreas into the blood flow is increased.     

Complexity of dimension three and some related edge-covering characteristics of graphs

We study systems of inference rules for multivalued dependencies in database relations. For such systems we define a new notion of completeness in which the underlying universe of attributes is left undetermined, whereas the earlier studied concept of completeness refers to a fixed finite universe. We introduce a new inference rule, the subset rule, and using this rule we prove that a certain system is complete. Furthermore we clarify the role of the so-called complementation rule.     

A multiple shutdown method for managing evacuation in case of major fire accidents in chemical clusters

This paper may be regarded as the second part of a larger article. The basic decision model developed in the first part of the article by Reniers et al. [G.L.L. Reniers, N. Pauwels, A. Audenaert, B.J.M. Ale, K. Soudan, Management of evacuation in case of fire accidents in chemical industrial areas, J. Hazard. Mater., 147 (2007) 478-487] is extended to determine both the optimal time and the optimal mode to stop the ongoing activities in case of a major fire possibly giving rise to an escalating event. Chemical plants have multiple modes to stop their production processes, differing with respect to the resulting costs, and with respect to the required time and personnel to complete the shutdown operations. The existence of an additional and more economic (but slower) shutdown mode might encourage the decision maker to stop the production processes earlier, in a less intervening manner, whereas the availability of an additional faster (but less economic) shutdown procedure might stimulate the decision maker to stop the production processes later, in a more intervening manner.     

Extraction of breathing features using MS Kinect for sleep stage detection

This paper presents the contactless measuring of breathing using the MS Kinect depth sensor and compares the results obtained with records of breathing taken by polysomnography (PSG). We explore the methods of signal denoising, resampling, and spectral analysis of acquired data as well as feature extraction and their Bayesian classification. The proposed methodology was applied for analysis of the long-term monitoring of individuals who were observed simultaneously by PSG and MS Kinect in the sleep laboratory. After time synchronization of polysomnographic and MS Kinect video data, features were extracted from both signals and compared. The average error of the frequency while being evaluated by MS Kinect that was related to that obtained by PSG was 3.75 %. The mean accuracy of the Bayesian classification of features into two classes (i.e. wake or sleep) was 88.90 and 88.95 % for the PSG and MS Kinect measurements, respectively. The strong likeness of features supports the hypothesis that contactless techniques may represent a valid alternative to the present approach of sleep monitoring, thereby allowing data acquisition in the home environment as well.     

The wettability and bonding performance of densified VTC beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) bonded with phenol–formaldehyde adhesive and liquefied wood

The influence of viscoelastic thermal compression (VTC) on surface wettability and bonding performance of wood was evaluated. Low quality beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) were densified with the VTC process to different degrees of densification. Control and densified strips were bonded with phenol–formaldehyde (PF) adhesive and liquefied wood (LW). Shear strength of bonded assemblies was determined after 1 week of conditioning at 20 °C and relative humidity of 65 %. Wettability was determined on the basis of the contact angle of water, PF adhesive, and LW using the Wilhelmy method. Results showed that densification of beech and spruce wood did not significantly affect the shear strength of specimens bonded with PF adhesive. In beech assemblies bonded with LW shear strength decreased significantly with increased density, whereas in bonded spruce specimens decrease of shear strength was not significant. It was found that degree of densification and bonding process used in the study were not appropriately chosen for spruce wood specimens, since major deformations after the bonding process occurred. Wettability changed significantly after densification. Contact angle of water and LW increased after densification, whereas contact angle of PF showed inverse trend and decreased after VTC process. Furthermore, the degree of densification had a minor effect on the wettability.