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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 2843-2852 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Measurements of the spectral and intensity dependences of the optically-induced reversal of current collapse in a GaN metal-semiconductor field-effect transistor (MESFET) have been compared to calculated results. The model assumes a net transfer of charge from the conducting channel to trapping states in the high-resistivity region of the device. The reversal, a light-induced increase in the trap-limited drain current, results from the photoionization of trapped carriers and their return to the channel under the influence of the built-in electric field associated with the trapped charge distribution. For a MESFET in which two distinct trapping centers have been spectrally resolved, the experimentally measured dependence upon light intensity was fitted using this model. The two traps were found to have very different photoionization cross-sections but comparable concentrations (4×1011 cm−2 and 6×1011 cm−2), suggesting that both traps contribute comparably to the observed current collapse.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 3527-3529 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The two deep traps responsible for current collapse in AlGaN/GaN high electron mobility transistors grown by metalorganic vapor-phase epitaxy have been studied by photoionization spectroscopy. Varying the growth pressure of the high resistivity GaN buffer layer results in a change in the deep trap incorporation that is reflected in the observed current collapse. Variations in the measured trap concentrations with growth pressure and carbon incorporation indicate that the deepest trap is a carbon-related defect, while the mid-gap trap may be associated with grain boundaries or dislocations. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 13 (2001), S. 251-264 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The active nature of vorticity is investigated in order to understand its difference with a passive scalar. The direct cascade down to small scales is examined through both classical and new diagnostics (based on tracer gradient properties) in numerical simulations of freely decaying two-dimensional (2D) turbulence. During the transient evolution of turbulence, the passive scalar possesses a stronger cascade due to different alignment properties with the equilibrium orientations obtained in the adiabatic approximation by Lapeyre et al. [Phys. Fluids 11, 3729 (1999)] and Klein et al. [Physica D 146, 246 (2000)]. In strain-dominated regions, the passive scalar gradient aligns better with the equilibrium orientation than the vorticity gradient does, while the opposite is true in effective-rotation-dominated regions. A study of the kinematic alignment properties shows that this is due to structures with closed streamlines in the latter regions. However, in the final evolutionary stage of turbulence, both active and passive tracer gradients have identical orientations (i.e., there is a perfect alignment between the two gradients, all the more so when they are stronger). The effect of diffusion on the cascade is also studied. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 15 (2001), S. 0 
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In a previous study, the use of a citric acid test meal produced a rapid dose-dependent increase in urease activity that was significantly greater than that resulting from a pudding meal, ascorbic acid or sodium citrate. The mechanism was hypothesized to be related to the ability of citric acid to delay gastric emptying and possibly to enhance intragastric distribution of the urea.〈section xml:id="abs1-2"〉〈title type="main"〉Objective:To compare the effects of sodium citrate, two doses of citric acid and a pudding meal on gastric motor function.〈section xml:id="abs1-3"〉〈title type="main"〉Method:Eleven normal healthy volunteers were investigated using non-invasive techniques to measure gastric emptying and gastric motility. We evaluated gastric emptying using the Meretek 13Ceebiscuit solid phase gastric emptying breath test, which employs a 340-calorie biscuit containing 200 mg of the edible 13C-blue–green alga Spirulina platensis, after the administration of test meals of pudding, 2 g and 4 g of citric acid and 2 g of sodium citrate. Electrogastrograms (Digitrapper EGG) were also recorded for 30 min before and 180 min after the test meal.〈section xml:id="abs1-4"〉〈title type="main"〉Results:Gastric emptying, as assessed by the half-time (T1/2), was delayed similarly with the pudding (136.8 ± 9 min) and with 4 g of citric acid (144.5 ± 7 min) (P 〉 0.7). Sodium citrate (108.7 ± 6 min) and 2 g of citric acid (110.1 ± 6 min) had similar effects on gastric emptying (P=0.986), and were significantly less effective in delaying gastric emptying (P 〈 0.01) compared to pudding or 4 g of citric acid. The electrogastrograms remained normal and there were no differences among meals and no relation with the gastric emptying results.〈section xml:id="abs1-5"〉〈title type="main"〉Conclusions:The increased intragastric urea hydrolysis associated with citric acid test meals cannot be attributed to delayed gastric emptying. Changes in the intragastric distribution of urea or a direct effect of citric acid on the bacteria (e.g. via the cytoplasmic protein, UreI) are more likely to be responsible.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Neurosurgical review 3 (1980), S. 57-65 
    ISSN: 1437-2320
    Keywords: Choroid plexus ; Choroid plexus papilloma ; Papillary ependymoma ; Brain metastasis ; Pneumococcal meningitis ; Colloidal iron reaction ; Lectin receptors ; Neuraminic acid mucopolysaccharides ; Neuraminidase ; Plexus chorioideus ; Papillom des Plexus chorioideus ; papilläres Ependymom ; Ca-Metastase ; Pneumokokken-Meningitis ; kolloidale Eisenreaktion ; Lektinrezeptoren ; Sialo-Mucopolysaccharide ; Neuraminidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die luminale Oberfläche der Zellen des Plexus chorioideus und der Plexuspapillome ist mit einem Überzug aus Sialo-Mucopolysacchariden bedeckt, der mit der kolloidalen Eisenreaktion nach Hale darstellbar ist und mit Neuraminidase entfernt werden kann. Nach Neuraminidase-Vorbehandlung lassen sich an den Zelloberflächen mit Fluorochrommarkierten Lektinen der Erdnuß (PNA) und von Rhicinus communis (RCA) spezifische, bestimmten Kohlehydraten entsprechende Rezeptoren nachweisen. Die Identität der PNA-Rezeptoren mit dem Thomsen-Friedenreich Antigen legt deren immunologische Bedeutung bei bakteriellen oder viralen Infektionen nahe. Die Anwendung dieser histochemischen Methoden scheint darüber hinaus eine differentialdiagnostische Klärung zwischen Plexuspapillomen und anderen papillären Tumoren (Ca-Metastasen, papilläre Ependymome) zu ermöglichen.
    Notes: Summary The surface of the cells of the normal choroid plexus and of the plexus papillomas is coated by sialomucopolysaccharides, containing substances which are positively stained with the colloidal iron (Hale-) reaction. After pretreatment with neuraminidase sialic acid is removed rendering the membrane negative to the Hale reaction. Using FITC- or rhodamine-labelled PNA (Arachis hypogaea) and RCA (Rhicinus communis) lectins specific receptors are demonstrable. The identity of these distinct oligosaccharides containing receptors with the Thomsen-Friedenreich antigens suggests the possibility of an immunologic significance, e. g. in bacterial or viral infections of the brain. The application of histochemical techniques seem suitable to clarify the differential-diagnosis between choroid plexus papillomas on the one hand and metastasis of carcinoma and papillary ependymomas on the other hand.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1433-0385
    Keywords: Keywords: IRM ; Surgery of the thyroid gland ; Surface electrode ; Routine monitoring. ; Schlüsselwörter: IRM ; Schilddrüsenchirurgie ; Oberflächenelektrode ; Routinemonitoring.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. In den letzten Jahren haben sich im wesentlichen 2 unterschiedliche Verfahren des Recurrensmonitorings durchgesetzt: Zum einen die Ableitung von spontanen bzw. evozierten Potentialen mit Hilfe von endoskopisch applizierten Stichelektroden, die in die Kehlkopfadduktoren gestochen werden, zum anderen die zunehmende Verwendung nicht-invasiver Elektroden. Letztere können entweder in Form spezieller Tuben mit integrierten Elektroden oder, wie im Fall der Postcricoidelektrode, in Form von getrennt zum Tubus in die Rachenhinterwand einzubringender Elektroden Anwendung finden. Eine neue Möglichkeit stellt die, von uns in dieser Arbeit beschriebene, an den Tubus anzuklebende Oberflächenelektrode dar. Während der Untersuchungsperiode mit dem intraoperativen Recurrens Monitoring (IRM) betrug bei allen Operationen und Indikationen die Häufigkeit permanenter Paresen 1/174 (0,6 %). Den Vorteil des IRM sehen wir im wesentlichen auch in der schnelleren und sicheren Erkennung des N. laryngeus recurrens; das intraoperative Recurrensmonitoring kann und soll eine schonende und sichere Operationstechnik nicht ersetzen. Wir schlußfolgern, daß das intraoperative Recurrensmonitoring mit Hilfe einer Oberflächenelektrode, die am Tubus festgeklebt wird, eine sichere, zuverlässige und wenig invasive Methode ist, um intraoperativ den N. recurrens zu überwachen.
    Notes: Abstract. In recent years, two methods of intraoperative monitoring of the laryngeal nerve have mostly been used: evoked electromyographic responses via endscopically applied needle electrodes inserted into the adducting laryngeal muscles, and non-invasive electrodes like special tubes with integrated electrodes or separately insertable electrodes like the postcricoid electrode or disposable electrodes attached to the tube, as used in this study. The incidence of recurrent nerve paresis or paralysis during the IRM period was 1/174 nerves (0.6 %). The advantage of the IRM is the quick and certain identification of the nerve; intraoperative monitoring cannot replace a proper surgical technique. We conclude that the IRM, using a laryngeal surface electrode attached to the tube, is a safe and reliable method.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1572-9982
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Type of Medium: Electronic Resource
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