A new feature extraction method for odour classification

A new method for real time classification of volatile chemical substance traces is presented. The method is based on electrochemical signals of an array of semiconductor gas sensors. In these sensor signals characteristic patterns of different substances are hidden. There are non-linear correlative relationships between the measured sensor signals and the chemical substances which are treated using two methods derived from statistical learning theory (Support Vector Machine - SVM, Maximum Likelihood Estimation - MLE) for the detection of the substance characteristics in the sensor signals. A key criterion for the presented pattern recognition is a newly developed type of features, which is specially adapted to the low frequency signals of semiconductor sensors. The presented features are based on the evaluation of the range of the transient response in the sensor signals in the frequency domain.To derive the new features, both real measurement data and synthetic generated signals were used. In the experiments the focus was set on the creation of reproducible sensor signals to get characteristic signal patterns. Synthetic signals were derived from a Gaussian Plume Model. With the new features, training data sets were calculated using the classification methods SVM and MLE. With these training data sets new sensor measurements may be assigned to the substances which are to be sought. The advantage of the presented method is that no feature reduction is needed and no loss of information occurs in the learning process.The classification results based on the new features have been compared with the classification based on a conventional method for feature extraction. It was proved that the recognition rate of the substances used with the new feature type is higher.The substance classification is primarily limited by the sensitivity of the semiconductor sensors, because sufficiently large sensor signals must have been provided to obtain appropriate substance patterns. At the present stage of development the method presented is suitable for the classification of substance groups, such as nitro aromatics or alcohols, but not for specific substances.     

Benchmarking urban six‐degree‐of‐freedom simultaneous localization and mapping

Quite a number of approaches for solving the simultaneous localization and mapping (SLAM) problem exist by now. Some of them have recently been extended to mapping environments with six‐degree‐of‐freedom poses, yielding 6D SLAM approaches. To demonstrate the capabilities of the respective algorithms, it is common practice to present generated maps and successful loop closings in large outdoor environments. Unfortunately, it is nontrivial to compare different 6D SLAM approaches objectively, because ground truth data about the outdoor environments used for demonstration are typically unavailable. We present a novel benchmarking method for generating the ground truth data based on reference maps. The method is then demonstrated by comparing the absolute performance of some previously existing 6D SLAM algorithms that build a large urban outdoor map. © 2008 Wiley Periodicals, Inc.     

Synthesis and investigation of α,ω-methacryloyl terminated epoxide-amine macromonomers

Summary ,-methacryloyl-poly (epoxide-amine)-macromonomers were synthesized by reaction of bisphenol-A diglycidylether DGEBA and methacrylic acid followed by addition polymerization of unreacted expoxide groups with primary monoamines or disecondary diamines, respectively. The resultant macromonomers having M_n (vpo)-values between 530 and 2000 g/mol were analysed by IR-, ¹H-NMR- and ¹³C-NMR-spectroscopy. HPLC and GPC analysis were used to determine the distribution of oligomers. The macromonomers are glassy or viscous liquids with T_g between 0 and 50 °C depending on the nature of the amine and polymerization degree.     

Wirbelschicht-Technologie: Neuentwicklungen für Kraftwerkstechnik und Umweltschutz

Fluidized bed technology: recent developments for power station engineering and pollution abatement . The principle of fluidization has been successfully applied to numerous areas of chemical engineering. Combustion of coal in a fluidized bed consisting of particles of ash and limestone or dolomite permits low-pollution utilization of coals having lower heating values or high sulphur contents without any need for removing sulphur from the exhaust gases. The present state of the art and world-wide development work on fluidized combustion are considered, as are the future prospects of this new energy technology.     

Measurements of the 17O excess in water with the equilibration method

The equilibration method is the present-day standard method for measuring delta18O in water samples. The mass-to-charge ratio of 45 is measured at the same time but generally not used for further analysis. We show that an improved equilibration method can be used for precise determination of delta17O in addition to that of delta18O, and therefore can estimate 17O excess values to a precision of better than 0.1 per thousand. To control the masking effect of the 14 times more abundant 13C on mass 45, we propose to use a chemical buffer in the water samples to keep the pH value and therefore the fractionation during the equilibration process of the 13C constant. With this improved method, the precision for the delta18O value could also be slightly improved from 0.05 to 0.03 per thousand. Furthermore, we discuss the influences of the amount of water, the temperature, the CO2 gas pressures, and changes in the pH during the measuring procedure on oxygen and carbon isotopes. We noticed that measured delta45 values are a good control for delta18O measurements. This study tries to fathom the possibilities and limitations of the equilibration method for measuring 17O excess values of water samples.     

Synthesis and hydrothermal treatment of nanostructured hydroxyapatite of controllable sizes

Nanoparticulate systems have been studied for targeted and controlled release of therapeutic agents; and size is one of the major determinants of their in vivo clearance kinetics by the MPS macrophages. As such, it is important to control the size of hydroxyapatite nanoparticles during synthesis. The results show that the size of hydroxyapatite nanoparticles, synthesized through chemical precipitation, increases with increasing synthesis time. Particle sizes were also observed to increase in a linear correlation with temperature. Crystallinity and carbonate-substitution of the nanoparticles also increased with temperature. Hydrothermal, performed as a post-synthesis treatment, improves particle morphology, giving particles with regular surface contours, well-defined sizes and lower particle agglomeration. By controlling synthesis temperature and time, hydroxyapatite nanoparticles with well-defined sizes and morphology can be obtained.     

Entrack: Probabilistic Spherical Regression with Entropy Regularization for Fiber Tractography

International Journal of Computer Vision - White matter tractography, based on diffusion-weighted magnetic resonance images, is currently the only available in vivo method to gather information on...     

Exosomes Secreted from Amniotic Membrane Contribute to Its Anti-Fibrotic Activity

Amniotic membranes (AM) have anti-fibrotic activity. Exosomes (nano-sized vesicles) function as conduits for intercellular transfer and contain all the necessary components to induce the resolution of fibrosis. In this study, we tested the hypothesis that the anti-fibrotic activity of AM is mediated by exosomes. AM-derived exosomes or amniotic stromal cell-derived exosomes were isolated and characterized. Anti-fibrotic activity of exosomes was evaluated using human hepatic stellate cells (LX-2), an in vitro model of fibrosis. Exosomes isolated from AM tissue-conditioned media had an average size of 75 nm. Exosomes significantly inhibited the proliferation of TGFβ1-activated LX-2 but had no effect on the proliferation of non-activated LX-2 cells. Exosomes also reduced the migration of LX-2 in a scratch wound assay. Furthermore, exosomes reduced the gene expression of pro-fibrotic markers such as COL1A1, ACTA, and TGFβ1 in LX-2 cells. Interestingly, exosomes isolated from AM tissue under hypoxic conditions seemed to show a stronger anti-fibrotic activity than exosomes isolated from tissue under normoxic conditions. Exosomes released by in vitro cultured AM stromal cells were smaller in size compared with tissue exosomes and also showed anti-fibrotic activity on LX-2 cells. In conclusion, AM-tissue-released exosomes contribute to the anti-fibrotic activity of AM. This is the first report of isolation, characterization, and functional evaluation of exosomes derived from amniotic tissues with the direct comparison between tissue-derived exosomes and cultured cell-derived exosomes.