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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 685-687 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate an ultrafast graded-gap electron transfer optical modulator structure with electron escape times on the order of 1 ps. All other aspects important for high-speed applications, for example, electroabsorption and electrical behavior remain essentially unaffected.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 1223-1225 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate the dynamics of photoexcited carriers in silicon after interband excitation with optical femtosecond pulses by probing intraband transitions with time-delayed THz pulses. The experimental data at various temperatures are compared with numerical, self-consistent solutions of the intraband polarization and Maxwell's equations. In addition, we deduce the carrier scattering rate from the comparison between experiment and theory. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Digestive diseases and sciences 39 (1994), S. 2069-2073 
    ISSN: 1573-2568
    Keywords: long-term manometry ; normal values ; age
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Although long-term esophageal manometry is increasingly used in clinical practice, the normal values of contraction parameters are poorly defined. In addition, limited data are available on the effect of age on esophageal motility. Therefore, 44 healthy subjects (age range: 22–85 years) were investigated with a probe combining two pressure transducers 10 cm apart. All subjects were asked to follow their normal daily routine. The characteristics of contraction events (amplitude, duration) and type of propagation (propulsive, simultaneous) were analyzed for the total time and predefined periods: meal, daytime (interprandial), and supine. Equally high distal and proximal median pressure amplitudes (39.5 and 37 hPa) and durations (3.4 and 3.2 sec) were observed. The median percentages of propulsive and simultaneous waves were 56% and 10%. The individual contraction characteristics differed significantly in these three selected periods for most motility parameters: distal and proximal pressure amplitudes, distal duration, and propulsive contractions. To evaluate the influence of age on normal values, the subjects were divided into two age groups (median age: 28.5 and 62.4 years). In the elderly group the distal pressure amplitude, the distal duration, and the percentage of simultaneous waves increased, whereas the percentage of propulsive waves, the proximal pressure amplitude, and the proximal duration decreased. However, the differences observed were only minor and rarely reached the level of statistical significance (distal pressure amplitude and duration in the supine period). In conclusion, the physiological motor activity of the esophagus is characterized by significant diurnal variation. Furthermore the motility data are little influenced by age. Therefore, individual contraction characteristics should be considered in the analysis of motility data. Since age is of minor influence on esophageal motility, we believe that it is not required to create age-related control data for study populations of this size.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Digestive diseases and sciences 40 (1995), S. 1445-1450 
    ISSN: 1573-2568
    Keywords: electrogastrography ; normal values ; age ; gender
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Electrogastrography (EGG) permits measurements of the gastric electrical activity. However, normal values of electrical activity are poorly defined. In addition, limited data are available on the effect of age and gender. Therefore, in 40 healthy subjects (age range: 19–90 years) normal values for several EGG parameters were assessed after an overnight fast for 1 hr in the fasting and fed state after ingestion of a standardized solid-liquid meal. The electrical signals were capture by a pair of surface electrodes sonographically placed on the skin overlying the gastric antrum. The dominant electrical frequency was predominantly in the defined normal frequency range between 2 and 4 cycles per minute (cpm) (P〈0.001) and was higher in the postprandial than in the preprandial period (3.1 cpm vs 2.8 cpm,P=0.02). The instability of the electrical rhythm calculated by a dominant frequency instability coefficient (DFIC) was postprandially lower than in the fasting state (P=0.04). The electrical power (amplitude) increased postprandially (postprandial to fasting power ratio =2.4). To evaluate the influence of age and gender on normal values the subjects were divided into four groups (median age: male, 28 and 69 years; female, 25 and 67 years). The most parameters did not differ significantly between the groups. However, DFIC was different between the groups (P〈0.05), with elderly women revealing lowest DFIC. In conclusion, normal values for several EGG parameters evaluated in this study should be included in the analysis of gastric electrical activity. The magnitude of electrical frequency and power are not influenced by age and gender, whereas the instability of the electrical frequency is influenced by these factors.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-2568
    Keywords: ELECTROGASTROGRAPHY ; DYSRHYTHMIAS ; GASTRIC EMPTYING ; FUNCTIONAL DYSPEPSIA ; H. PYLORI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An association between dyspepsia, gastricmotility disorders, and myoelectrical abnormalities hasbeen noted. The objective of the present study was toinvestigate both antral myoelectrical activity and gastric emptying in patients with functionaldyspepsia (FD). Electrogastrography (EGG) was performedin 25 adult patients with FD, which had been evaluatedby score. After an overnight fast, for 1 hr in the pre- and postprandial state (370 kcalliquid-solid test meal) the following EGG parameterswere determined: dominant frequency [DF (cpm)], DF (%)in the normal range (2-4 cpm), bradygastria (〈2 cpm), tachygastria (4-10 cpm), dominant frequencyinstability coefficient (DFIC), and postprandial tofasting power ratio (PR). The data were correlated toresults obtained in 20 age- and gender-matched controls. In addition, in 17 consecutive patients the EGGdata were compared to the gastric retention ofradionuclides after 60 min (liquid-solid phase labeledwith 99mTc colloid). Patients with FDrevealed a preprandial increase in tachygastria compared to controls(P 〈 0.001). Of 17 FD, seven patients exhibiteddelayed gastric emptying (t60 retention 〉68%). Thesepatients showed significantly more pre- and postprandial tachygastrias than patients with normal gastricemptying (P 〈 0.05). The dyspeptic symptology and H.pylori status did not correlate with EGG andradioscintigraphy. Patients with FD frequently revealimpaired gastric emptying and increased tachygastria,which may have pathophysiological significance in someof these patients.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2019-01-24
    Language: English
    Type: article , doc-type:article
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  • 7
    Publication Date: 2021-01-08
    Language: English
    Type: article , doc-type:article
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  • 8
    Publication Date: 2021-01-08
    Language: English
    Type: article , doc-type:article
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  • 9
    Publication Date: 2022-06-13
    Language: English
    Type: article , doc-type:article
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