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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Manuscripta mathematica 63 (1989), S. 115-128 
    ISSN: 1432-1785
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper, we affirmatively answer an open question raised by P.Szeptycki and Vlech in (9) and give a new characterization of p-uniformly convex Banach space. The Lipschitz stability of the set of ε-Chebyshev centers Gε(A) under the perturbations of A and G is also proved.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 546-549 (May 2007), p. 2163-2166 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this work, (Fe,Co)–Zr–B–Cu films have been deposited on glass and Si substrates byDC magnetron sputtering method. X-ray diffraction analysis was used to identify the structure of thefilms. A transmission electron microscope (TEM) was employed to observe the microstructure for thefilms. Magnetic properties at room temperature were investigated by a Vibrating SampleMagnetometer (VSM). It was obtained that the as-deposited films on glass and Si substrates were inan amorphous state. In addition, it has been found that the coercivity is dependent on film thicknesses
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Noncontact Endocardial Mapping. Introduction: Mapping endocardial activation and repolarization processes is critical to the study of arrhythmias and selection of therapeutic procedures. Previously, we developed methodology for reconstructing endocardial potentials from potentials measured with a noncontact, intracavitary probe. This study further develops and evaluates the ability of the approach to provide detailed information on the spatiotemporal characteristics of the activation process. Specifically, we reconstructed endocardial electrograms and isochrones throughout the activation process over the entire endocardium during a single beat. Methods and Results: Cavity potentials were measured with a 65-electrode probe placed inside an isolated canine left ventricle. Endocardial potentials were measured simultaneously using 52 electrodes. Potentials were acquired during subendocardial pacing from different locations. Computed electrograms at various sites closely resemble the measured electrograms (correlation coefficient 〉 0.9 at 60% of the electrodes). Computed isochrones locate subendocardial pacing sites with 10-mm accuracy. Two pacing sites, 17 mm apart, were resolved. Critical regions, such as areas of isochrone crowding, were accurately reconstructed. Conclusions: Results indicate the applicability of the approach to mapping the cardiac excitation process on a beat-by-beat basis without occluding the ventricle. The ability of locating electrical events (e.g., single or multiple initiation sites) is demonstrated. Importantly, the method is shown to be capable of reconstructing electrograms over the entire endocardium and determining nonuniformities of activation spread (e.g., areas of slow conduction). These capabilities are important to clinical application in the electrophysiology laboratory and experimental studies of arrhythmias in the intact animal.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 13 (2002), S. 0 
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Noncontact Mapping of Arrhythmogenic Substrates. Introduction: In previous studies, we established methodology for reconstructing endocardial potential maps, electrograms, and isochrones from a noncontact intracavitary catheter during a single beat. Recently, we evaluated this approach using a 9-French (3-mm) spiral catheter in a normal heart preparation. Here we extend the approach to hearts with structural disease and examine its ability to detect and characterize abnormal electrophysiologic (EP) substrates and to map ventricular arrhythmias on a beat-by-beat basis. Methods and Results: Reconstruction of endocardial potentials from cavity potentials measured with 82 electrodes mounted on a 9-French spiral catheter was performed in an isolated canine left ventricle (LV). Endocardial potentials were recorded with 91 intramural needles, providing a gold standard for evaluating the noncontact reconstruction. Studies were performed in a normal LV (control) and the same LV 3 hours after left anterior descending coronary artery occlusion and ethanol injection to create an infarct. Abnormal EP characteristics over the infarct were faithfully reconstructed, including (1) low potentials and electrogram derivatives; (2) fractionated electrograms; (3) small deflections on electrograms reflecting local activation; and (4) slow discontinuous conduction transverse to fibers. During arrhythmia, beat-to-beat dynamic shifts of initiation site and activation pattern were captured by the reconstruction. Conclusion: Noncontact, nonexpendable catheter mapping can locate and characterize abnormal EP substrates and can capture the endocardial sequence of an arrhythmia during a single beat.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 11 (2000), S. 0 
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Electrophysiologic Noncontact Endocardial Mapping. Introduction: The need for high-resulution simultaneous mapping of cardiac excitation and arrhythmias on a heat-hy-heat basis is widely recognized. Here we validate a noncontact mapping approach that combines a spiral catheter design with mathematical reconstruction to generate potential maps, electrograms, and activation maps (isochrones) on the entire left ventricular endocardial surface during a single beat. The approach is applicable to any heart chamher.Methods and Results: The catheter is 3 mm (9 French) in diameter and carries 96 electrodes. Reconstruction accuracy is evaluated through direct comparison with endocardial data measured with 95 needle electrodes. Results show that endocardial potentials, electrograms, and isochrones are reconstructed with good accuracy during pacing from single or multiple sites (simulating ectopic activity). Pacing sites can be located to within 5 mm of their actual position, and intersite distances of 17 mm can be resolved during dual pacing. The reconstructed potential pattern reflects the intramural depth of pacing. The reconstructions are robust in the presence of geometric errors, and the accuracy is minimally reduced when only 62 catheter electrodes are used (32 are sufficient for pacing site localization).Conclusion: The study demonstrates that simultaneous endocardial mapping can be accomplished during a single beat from a spiral-shaped noncontact catheter with good accuracy.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature medicine 10 (2004), S. 422-428 
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Over 7 million people worldwide die annually from erratic heart rhythms (cardiac arrhythmias), and many more are disabled. Yet there is no imaging modality to identify patients at risk, provide accurate diagnosis and guide therapy. Standard diagnostic techniques such as the electrocardiogram (ECG) ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell reports 1 (1981), S. 48-51 
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Following ultraviolet mutagenesis, we have isolated two Na+ dependent variants from haploid suspension cultures of soybean cells. No selection was used in the isolation procedure. These cells cannot grow in 1 mM Na+ but can grow in 17 mM Na+. The strains also grow in 33 or 65 mM Na+, concentrations in which the parent cell line dies. [22Na] was used to measure the accumulation of Na+ by parent and variant cell lines. Two- to three-fold less Na+ is retained by the variant cell lines.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 240-242 (May 2003), p. 547-550 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 218-220 (Nov. 2001), p. 51-54 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Annals of biomedical engineering 26 (1998), S. 994-1009 
    ISSN: 1573-9686
    Keywords: EP catheter mapping ; Simultaneous endocardial mapping ; Noncontact endocardial mapping ; Endocardial potential mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract In previous studies, we established methodology for reconstructing endocardial potentials, electrograms and isochrones from a non-contact intracavitary probe during a single beat. The probe was too large to be introduced percutaneously. Here we examine the possibility of similar mapping with a small multielectrode catheter that could be introduced percutaneously and does not expand inside the cavity. Cavity geometry and endocardial potentials were recorded in an isolated canine left ventricle. Simulated catheter probes were introduced into the cavity. Probe potentials were computed from the measured endocardial potentials and perturbed to include measurement noise, geometrical errors, and limited electrode density. Endocardial potentials were then reconstructed from the perturbed probe potentials and compared to the actual measured potentials. Of all probes simulated, a 3.0 mm (9F) catheter that assumes a curved geometry (e.g., a J shape) inside the cavity performed best (better than a larger 7.6 mm cylinder simulating an inflatable probe). Without bending, a straight cylindrical probe of the same size (9F, 3.0 mm) did not perform well. Sixty probe electrodes were needed for accurate reconstruction. The J-probe reconstruction was very robust in the presence of noise (10%) and of geometry errors (3 mm shift, 10° rotation). The results demonstrate the feasibility of accurate single-beat endocardial mapping using a 9F percutaneous multielectrode catheter that assumes a J shape in the cavity without the need for expansion (e.g., into a balloon or a “basket”). The robustness of the procedure to noise and geometrical errors suggests its applicability in the clinical EP laboratory and the possibility of determining probe position in vivo using current imaging modalities. © 1998 Biomedical Engineering Society. PAC98: 8759Wc
    Type of Medium: Electronic Resource
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