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  • Digitale Medien  (11)
  • ELECTROGASTROGRAPHY  (4)
  • Engineering General  (4)
  • Electrogastrogram  (3)
Materialart
  • Digitale Medien  (11)
Erscheinungszeitraum
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Annals of biomedical engineering 26 (1998), S. 859-869 
    ISSN: 1573-9686
    Schlagwort(e): Spectral analysis ; Matching pursuit ; Stomach ; Gastric motility ; Electrogastrography ; Evolutionary programming ; Signal analysis ; Electrogastrogram
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Abstract The electrogastrogram (EGG) is a surface measurement of gastric myoelectrical activity. The normal frequency of gastric myoelectrical activity in humans is 3 cycles/min. Abnormal frequencies in gastric myoelectrical activity have been found to be associated with functional disorders of the stomach. The aim of this article was, therefore, to develop new time-frequency analysis methods for the detection of gastric dysrhythmia from the EGG. A concept of overcomplete signal representation was used. Two algorithms were proposed for the optimization of the overcomplete signal representation. One was a fast algorithm of matching pursuit and the other was based on an evolutionary program. Computer simulations were performed to compare the performance of the proposed methods in comparison with existing time-frequency analysis methods. It was found that the proposed algorithms provide higher frequency resolution than the short time Fourier transform and Wigner-Ville distribution methods. The practical application of the developed methods to the EGG is also presented. It was concluded that these methods are well suited for the time-frequency analysis of the EGG and may also be applicable to the time-frequency analysis of other biomedical signals. © 1998 Biomedical Engineering Society. PAC98: 8780+s, 0705Kf
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Digestive diseases and sciences 43 (1998), S. 2384-2391 
    ISSN: 1573-2568
    Schlagwort(e): ELECTROGASTROGRAPHY ; FUNCTIONAL DYSPEPSIA ; GASTROINTESTINAL MOTILITY ; GASTRIC EMPTYING
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The aim of this study was to investigateabnormalities in pediatric patients with functionaldyspepsia. Fifteen symptomatic pediatric patientsdiagnosed with functional dyspepsia and 17 aged-matchedhealthy controls were studied. Gastric myoelectricalactivity was recorded using surface electrogastrographyfor 1 hr in the fasting state and 1 hr after a testmeal. It was found that, in comparison with thecontrols, the children with functional dyspepsia had alower percentage of 2- to 4-cpm slow waves in bothfasting state (66.0 ± 4.7% vs 79.7 ± 3.1%,P 〈 0.07) and fed state (72.4 ± 5.4% vs 85.0± 2.9%, P 〈 0.04), and a significantly higherinstability of the dominant frequency in both fastingstate (0.50 ± 0.05 vs 0.31 ± 0.04, P 〈0.01) and fed state (0.39 ± 0.05 vs 0.25 ±0.03, P 〈 0.05). It was also found the postprandial increase inEGG dominant power in the patients was inverselycorrelated with the total symptom score (r = 0.63, P =0.03). It was concluded that abnormal gastricmyoelectrical activity may play a role in the pathogenesis ofpediatric functional dyspepsia.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Digestive diseases and sciences 43 (1998), S. 1678-1684 
    ISSN: 1573-2568
    Schlagwort(e): ELECTROGASTROGRAPHY ; GASTROINTESTINAL MOTILITY ; FUNCTIONAL DYSPEPSIA ; GASTRIC EMPTYING
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The aim of this study was to investigate gastricmyoelectrical activity in patients with functionaldyspepsia. Thirteen healthy subjects and 14 patientswith functional dyspepsia participated in the study. The electrogastrogram (EGG) recording was madein each subject for 30 min in the fasting state and 120min after a standard test meal of 475 calories. Spectralanalysis methods were applied to derive quantitative EGG parameters. There was no difference in theEGG between the patients and controls in the fastingstate. However, abnormalities in the postprandial EGGwere found in the patients. The percentage of 2-4 cpmwaves was significantly lower (74.4 ± 4.0% vs85.7 ± 1.6%, P 〈 0.03) and the postprandialincrease in EGG dominant power was significantly less(–0.52 ± 0.92 dB vs 2.24 ± 0.88 dB,P 〈 0.03) in patients than in controls. It was alsofound that the percentage of postprandial 2-4 cpm wavescould be used to differentiate the patients withfunctional dyspepsia from the healthy controls with a specificity of 100% and a sensitivity of 43%. It was concluded that a subset of patients withfunctional dyspepsia have impaired gastric myoelectricalactivity in the fed state.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Digestive diseases and sciences 43 (1998), S. 1023-1030 
    ISSN: 1573-2568
    Schlagwort(e): ELECTROGASTROGRAPHY ; GASTROINTESTINAL MOTILITY ; GASTRIC EMPTYING ; STOMACH
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The efficiency and efficacy of theelectrogastrogram (EGG) involve a few practical factors,including recording length, sample size, and thecharacteristics of subjects. The aim of this study wasto investigate the effect of these factors on the accuracy ofEGG analysis. Gastric myoelectrical activity wasrecorded using electrogastrography in 24 subjects (ages22-91 years) for 1 hr in the fasting state and 2 hr after a test meal. Computerized spectralanalysis was performed to compute EGG parameters,including dominant frequency, dominant power, and thepercentage of 2-4 cycles per minute (cpm) slow waves. A parameter called misinterpretation was definedto investigate the effect of recording length. Theresults were as follows: (1) Using the recording lengthof 1 hr in each state as a gold standard, themisinterpretation for the recording length of 30 min was 27% forthe dominant frequency and 17% for the dominant power.When the recording length was reduced to 15 min, themisinterpretation increased to 61% for the dominant frequency and 38% for the dominant power. (2)With a sample size of 10 subjects and a recording lengthof 60 min, a statistically significant postprandialincrease was observed in the dominant frequency and power, and a trend in the postprandialincrease of the regularity of the EGG was noted. Whenthe sample size increased to 24 subjects, a significantpostprandial increase was found in all these parameters. (3) None of the EGG parameters exhibited anysignificant difference between the younger and oldersubjects or between men and women. In conclusion, arecording length of 30-60 min seems to be appropriate and produces reliable and predictable results.Age and gender do not affect any of the EGGparameters.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Digestive diseases and sciences 44 (1999), S. 56-62 
    ISSN: 1573-2568
    Schlagwort(e): GASTRIC SLOW WAVES ; GASTRIC MOTILITY ; GASTRIC EMPTYING ; ELECTROACUPUNCTURE ; ELECTROGASTROGRAPHY
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The aim of this study was to investigate thecharacteristics of the gastric slow wave duringdifferent phases of the migrating myoelectrical complex(MMC) and the effect of electroacupuncture on the MMC. The experiment was performed in eight hounddogs implanted with one pair of bipolar serosalelectrodes 2 cm proximal to the pylorus. Gastricmyoelectrical activity was recorded for three completecycles of the MMC in two sessions, one withelectroacupuncture at points ST36 and PC6 and the otherat sham points. The acupuncture was performed for 30 minin phase I of the second cycle of the MMC. Spectral analysis was performed to compute the frequencyand power (amplitude) of the gastric slow wave, whereasblind visual analysis was applied to compute theappearance of spike potentials and the length of each phase of the MMC. It was found that therewas a significant difference in the frequency and powerof the gastric slow wave during different phases of theMMC (P 〈 0.05). Phase I was characterized with the highest frequency and lowest power ofthe gastric slow wave, whereas phase III exhibited thehighest power in the slow wave. It was also found thatin comparison with the sham points, electroacupuncture at the acupoints increased the number of spikebursts. This increase was not significant during the MMCcycle with electroacupuncture (34.4 ± 4.1 vs 27.5± 2.5%, P 〉 0.05) but became significant during the cycle after electroacupuncture (39.8± 3.3% vs 27.5 ± 2.5%, P 〈 0.0005).Similarly, during the MMC cycle after electroacupunctureat the acupoints, there was a significant decrease in the length of phase I (14.8 ± 2.2 vs46.9 ± 6.1 min, P 〈 0.003) and a significantincrease in the length of phase II (75.6 ± 9.9 vs30.6 ± 4.1 min, P 〈 0.003) and phase III (25.8± 0.6 vs 22.1 ± 0.7 min, P 〈 0.003). A similarincrease was observed during the MMC cycle withelectroacupuncture but was not statisticallysignificant. In conclusion, the gastric slow wave hasthe highest power during phase III of the MMC, indicatingthat the antral contraction is characterized not only bythe appearance of spikes, but also by the increasedpower of the slow wave. Electroacupuncture at acupoints of ST36 and PC6 enhances the gastric MMC byreducing the length of phase I and increasing the lengthof phases II and III.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 29 (1991), S. 351-357 
    ISSN: 1741-0444
    Schlagwort(e): Bioelectric potential ; Electrogastrogram ; Electromyography ; Gastric motility ; Slow wave ; Stomach
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The gastric electric activity paces the contractions of the stomach and can be measured noninvasively using surface electrodes placed on the abdomen. In this paper, response of the gastric electric activity to water and a solid meal was investigated using surface electrodes. Applying an improved recording technique, power spectral analysis and statistical analysis methods, the gastric electric activity in preprandial, postwater and postprandial states was measured and analysed from ten healthy volunteers. To more convincingly show the effect of water and the solid meal on the gastric slow wave and gastric motility, simultaneous recordings of the cutaneous EGG and manometric activities in the stomach were performed in three gastroparetic patients. It was found that water does not induce contractions of the stomach, but the gastric slow wave amplitude increases (p〈0·05) and frequency decreases (p〈0·05). The solid meal results in an increase in both the amplitude (p〈0·01) and the frequency (p〈0·02) of the gastric slow wave. It appears that the postprandial EGG amplitude increases because of a combination of stomach contractions and gastric distension bringing the stomach closer to the recording electrodes. The slow wave frequency, however, correlates well with stomach contractions.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 31 (1993), S. 60-67 
    ISSN: 1741-0444
    Schlagwort(e): Electrogastrogram ; Electrogastrography ; Gastric motility ; Intestinal motility ; Myoelectrical activity ; Spectral analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 479-490 
    ISSN: 1069-8299
    Schlagwort(e): Modal reaction method ; modal participation factor ; support motion ; discrete system ; modal equivalent mass ; quasi-static decomposition ; Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: An efficient method, called the modal reaction method, for calculating the modal participation factors for support motion problems is proposed. It is found that modal reactions at supports proportionally describe the magnitudes of the modal participation factors. Thus, the modal participation factor for support motion problems can be calculated very efficiently, saving more than 99 per cent, for the given example with 640 degreees of freedom, of the CPU time compared with using the popular quasistatic decomposition method.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 831-846 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: As an effort to predict effectively the actual collapse load of a structure, a series of numerical studies on the stability of shell structures are made. The difference in formulation between the two types of linear buckling loads, the classical and the fully linearized, is first demonstrated. Their correlations with respect to the actual stability limit of the structure are compared, and finally the two types of critical load approximations are obtained at various stages of a nonlinear analysis to study the pattern of convergence to the actual collapse load. It is found that the fully linearized buckling analysis, when combined with nonlinear analysis, can serve as a useful tool for prediction of the stability limit of a structure. While for most types of structures the approximation is within engineering accuracy, the rate of convergence of the extrapolated critical load also gives some insight to the accuracy of the approximation.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 21 (1995), S. 129-139 
    ISSN: 0271-2091
    Schlagwort(e): numerical technique ; boundary layer equations ; reacting flow ; full coupling ; finite rate chemistry effects ; thermal radiation effects ; Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau
    Notizen: A new numerical scheme for reacting axisymmetric jet flows formed between a fuel jet and co-flowing air has been developed. The model is mathematically described by a set of non-linear parabolic partial differential equations in two space dimensions, i.e. the boundary layer equations. The numerical scheme that the programme uses for solving the fully coupled conservation equations of mass, momentum, energy and species is a generaliztion of the discretization technique recently developed by Villasenor (J. Math. Comput. Simul., 36, 203-208 (1994)). Chemical production (and destruction) of the species is allowed to occur through N elementary reversible (or irreversible) reactions involving k species, although in the present model the reaction rates are evaluated with a simplified kinetic mechanism for a one-step global reaction. Thermal radiation is considered assuming an optically thin limit and adopting the grey medium approximation. Allowances are made for natural convection effects and variable thermodynamic and molecular transport properties. The performance of the model in solving the coupled aerodynamic and finite rate chemistry effects is tested by comparing model predictions with experimental data of Mitchell et al. (Combust. Flame, 37, 227-244 (1980)) for a buoyant, laminar, diffusion axisymmetric methane-air flame.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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