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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Digestive diseases and sciences 43 (1998), S. 1023-1030 
    ISSN: 1573-2568
    Keywords: ELECTROGASTROGRAPHY ; GASTROINTESTINAL MOTILITY ; GASTRIC EMPTYING ; STOMACH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Digestive diseases and sciences 43 (1998), S. 1678-1684 
    ISSN: 1573-2568
    Keywords: ELECTROGASTROGRAPHY ; GASTROINTESTINAL MOTILITY ; FUNCTIONAL DYSPEPSIA ; GASTRIC EMPTYING
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-2568
    Keywords: ELECTROGASTROGRAPHY ; FUNCTIONAL DYSPEPSIA ; GASTROINTESTINAL MOTILITY ; GASTRIC EMPTYING
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Digestive diseases and sciences 44 (1999), S. 56-62 
    ISSN: 1573-2568
    Keywords: GASTRIC SLOW WAVES ; GASTRIC MOTILITY ; GASTRIC EMPTYING ; ELECTROACUPUNCTURE ; ELECTROGASTROGRAPHY
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 21 (1995), S. 129-139 
    ISSN: 0271-2091
    Keywords: numerical technique ; boundary layer equations ; reacting flow ; full coupling ; finite rate chemistry effects ; thermal radiation effects ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: 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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 831-846 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: 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.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 847-865 
    ISSN: 0029-5981
    Keywords: interlaminar shear stress ; layer reduction technique ; composite laminate ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Interlaminar stress plays an important role in the delamination failure of laminated composites. A recently presented theory, the Interlaminar Shear Stress Continuity Theory (ISSCT), can directly and accurately predict interlaminar shear stresses in laminated composites by the constitutive equations. The present study further generalizes the derivation to a complete form from which many displacement-based laminate theories can be derived. Most of all, both the single-layer and multiple-layer approaches are incorporated into the analysis in the thickness direction. The laminate is discretized into several sublaminates and, then, a layerwise theory is applied in the analysis of this reduced laminate. This reduction in the number of layers used in the analysis makes the calculation of interlaminar shear stresses on the interested interface in a thick laminate more efficient. In addition, numerical solutions in closed-form and finite element form for laminates under cylindrical bending and bidirectional bending are examined. It is found that in the thickness direction the cubic order of the interpolation function and the discretization with four to six sublaminates can reduce the computational efforts dramatically and retain the accuracy of the predicted stresses within ±8 per cent.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 479-490 
    ISSN: 1069-8299
    Keywords: Modal reaction method ; modal participation factor ; support motion ; discrete system ; modal equivalent mass ; quasi-static decomposition ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: 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.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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