@article{WesselSchwarzSaparinetal.2002, author = {Wessel, Niels and Schwarz, Udo and Saparin, Peter and Kurths, J{\"u}rgen}, title = {Symbolic dynamics for medical data analysis}, isbn = {3-936142-09-2}, year = {2002}, abstract = {Observational data of natural systems, as measured in medical measurements are typically quite different from those obtained in laboratories. Due to the peculiarities of these data, wellknown characteristics, such as power spectra or fractal dimension, often do not provide a suitable description. To study such data, we present here some measures of complexity, which are basing on symbolic dynamics. Firstly, a motivation for using symbolic dynamics and measures of complexity in data analysis based on the logistic map is given and next, two applications to medical data are shown. We demonstrate that symbolic dynamics is a useful tool for the risk assessment of patients after myocardial infarction as well as for the evaluation of th e architecture of human cancellous bone.}, language = {en} } @article{MavangaMikelskisLeisner2002, author = {Mavanga, Gil Gabriel and Mikelskis, Helmut and Leisner, Antje}, title = {Evaluationsstudie zur Optik in Mosambik}, series = {Zur Didaktik der Physik und Chemie}, journal = {Zur Didaktik der Physik und Chemie}, publisher = {Leuchtturm-Verl.}, address = {Alsbach/Bergstraße}, isbn = {3-88064-304-0}, year = {2002}, language = {de} } @article{MalbergWesselHasartetal.2002, author = {Malberg, Hagen and Wessel, Niels and Hasart, Annett and Osterziel, Karl Joseph and Voss, Andreas}, title = {Advanced analysis of the spontaneous baroreflex sensitivity, blood pressure and heart rate variability in patients with dilated cardiomyopathy}, year = {2002}, abstract = {Baroreflex sensitivity (BRS) is an important parameter in the classification of patients with reduced left ventricular function. This study aimed at investigating BRS in patients with dilated cardiomyopathy (DCM) and in healthy subjects (controls), as well as comparing the values of BRS parameters with parameters of heart rate variability (HRV) and blood pressure variability (BPV). ECG, continuous blood pressure and respiration curves were recorded for 30 min in 27 DCM patients and 27 control subjects. The Dual Sequence Method (DSM) includes the analysis of spontaneous fluctuations in systolic blood pressure and the corresponding beat-to-beat intervals of heart rate to estimate bradycardic, opposite tachycardic and delayed baroreflex fluctuations. The number of systolic blood pressure/beat-to- beat interval fluctuations in DCM patients was reduced in comparison with controls (DCM patients: male, 154.4+/-93.9 ms/ mmHg; female, 93.7+/-40.5 ms/mmHg; controls: male, 245.5+/-112.9 ms/mmHg; female, 150.6+/-55.8 ms/mmHg, P<0.05). The average slope in DCM patients was lower than in controls (DCM, 5.3+/-1.9 ms/mmHg; controls, 8.0+/-5.4 ms/mmHg; P<0.05). Discriminant function analysis showed that, in the synchronous range of the standard sequence method, the DCM and control groups could be discriminated to only 76\% accuracy, whereas the DSM gave an improved accuracy of 84\%. The combination of six parameters of HRV, BPV and DSM gives an accuracy of classification of 96\%, whereas six parameters of HRV and BPV could separate the two groups to only 88\% accuracy. Thus the DSM leads to an improved characterization of autonomous regulation in order to differentiate between DCM patients and healthy subjects. BRS in DCM patients is significantly reduced and apparently less effective.}, language = {en} } @article{MarwanWesselMeyerfeldtetal.2002, author = {Marwan, Norbert and Wessel, Niels and Meyerfeldt, Udo and Schirdewan, Alexander and Kurths, J{\"u}rgen}, title = {Recurrence-plot-based measures of complexity and its application to heart-rate-variability data}, year = {2002}, abstract = {The knowledge of transitions between regular, laminar or chaotic behavior is essential to understand the underlying mechanisms behind complex systems. While several linear approaches are often insufficient to describe such processes, there are several nonlinear methods which however require rather long time observations. To overcome these difficulties, we propose measures of complexity based on vertical structures in recurrence plots and apply them to the logistic map as well as to heart rate variability data. For the logistic map these measures enable us not only to detect transitions between chaotic and periodic states, but also to identify laminar states, i.e. chaos-chaos transitions. The traditional recurrence quantification analysis fails to detect the latter transitions. Applying our new measures to the heart rate variability data, we are able to detect and quantify the laminar phases before a life-threatening cardiac arrhythmia occurs thereby facilitating a prediction of such an event. Our findings could be of importance for the therapy of malignant cardiac arrhythmias.}, language = {en} } @article{CserDonnerSchwarzetal.2002, author = {Cser, Adrienn and Donner, Reik Volker and Schwarz, Udo and Otto, Andreas H. and Geiger, M. and Feudel, Ulrike}, title = {Towards a better understanding of laser beam melt ablation using methods of statistical analysis}, isbn = {88-87030-44-8}, year = {2002}, abstract = {Laser beam melt ablation, as a contact free machining process, offers several advantages compared to conventional processing mechanisms. Although the idea behind it is rather simple, the process has a major limitation: with increasing ablation rate surface quality of the workpiece processed declines rapidly. The structures observed show a clear dependence of the line energy. In dependence of this parameter several regimes of the process have been separated. These are clearly distinguishable as well in the surfaces obtained as in the signals gained by the measurement of the process emissions which is the observed quantity chosen.}, language = {en} } @article{ChristliebWisotzkiGrasshoff2002, author = {Christlieb, N. and Wisotzki, Lutz and Graßhoff, G.}, title = {Statistical methods of automatic spectral classification and their application to the Hamburg/ESO Survey}, year = {2002}, abstract = {We employ classical statistical methods of multivariate classification for the exploitation of the stellar content of the Hamburg/ESO objective prism survey (HES). In a simulation study we investigate the precision of a three- dimensional classification (Teff, log g, [Fe/H]) achievable in the HES for stars in the effective temperature range 5200 K10 (typically corresponding to BJ<16.5). The accuracies in log g and [Fe/H] are better than 0.68 dex in the same S/N range. These precisions allow for a very efficient selection of metal-poor stars in the HES. We present a minimum cost rule for compilation of complete samples of objects of a given class, and a rejection rule for identification of corrupted or peculiar spectra. The algorithms we present are being used for the identification of other interesting objects in the HES data base as well, and they are applicable to other existing and future large data sets, such as those to be compiled by the DIVA and GAIA missions.}, language = {en} } @article{AbelCelaniErgnietal.2002, author = {Abel, Markus and Celani, A. and Ergni, V. and Vulpiani, A.}, title = {Front speed enhancement in cellular flows}, issn = {1054-1500}, year = {2002}, language = {en} } @book{Breuer2002, author = {Breuer, Elmar}, title = {Physik plus : mit f{\"a}cher{\"u}bergreifenden Themen und Projektangeboten ; Kl. 9/10, [Hauptbd.], Gymnasium Sachsen-Anhalt}, editor = {Mikelskis, Helmut and Wilke, Hans-Joachim}, publisher = {Volk-und-Wissen-Verl.}, address = {Berlin}, isbn = {3-06-020981-2}, pages = {224 S.}, year = {2002}, language = {de} } @phdthesis{Casu2002, author = {Casu, Maria Benedetta}, title = {Electronic structure of heterocyclic organic semiconductors}, publisher = {Mensch \& Buch Verl.}, address = {Berlin}, isbn = {3-89820-309-3}, pages = {101 S.}, year = {2002}, language = {en} } @phdthesis{Boeckmann2002, author = {B{\"o}ckmann, Christine}, title = {Bestimmung atmosph{\"a}rischer Aerosolparameter mit Hilfe von regularisierenden Inversionsverfahren}, pages = {167 S. : Anh.}, year = {2002}, language = {de} }