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  • 1
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new levitation apparatus coupled to a synchrotron-derived x-ray source has been developed to study the structure of liquids at temperatures up to 3000 K. The levitation apparatus employs conical nozzle levitation using aerodynamic forces to stably position solid and liquid specimens at high temperatures. A 270 W CO2 laser was used to heat the specimens to desired temperatures. Two optical pyrometers were used to record the specimen temperature, heating curves, and cooling curves. Three video cameras and a video recorder were employed to obtain and record specimen views in all three dimensions. The levitation assembly was supported on a three-axis translation stage to facilitate precise positioning of the specimen in the synchrotron radiation beam. The levitation system was enclosed in a vacuum chamber with Be windows, connections for vacuum and gas flow, ports for pyrometry, video, and pressure measurements. The vacuum system included automatic pressure control and multi-channel gas flow control. A phosphor screen coupled to a high-resolution video microscope provided images of the x-ray beam and specimen shadow which were used to establish the specimen position. The levitation apparatus was integrated with x-ray diffractometers located at X-6B and X-25 beamlines at the National Synchrotron Light Source. X-ray structural measurements have been obtained on a number of materials including Al2O 3, Ni, Si, Ge, and other metallic and ceramic materials in the liquid state. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 1379-1381 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Palladium is known to exhibit an acceptor state at EC−0.22 eV in n-type Si and a donor state at EV+0.31 eV in p-type Si. We have identified a third level at EV+(0.140±0.005) eV and attribute it to the double donor state of substitutional Pd. The Pd level positions are very similar to the corresponding levels for Pt. The double donor states of both metals show an electric field dependence of the emission rates and a thermal activation of the hole capture cross sections. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 1584-1586 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The midgap level in platinum doped n-type silicon, which was proposed to be the dominant recombination center, is identified as a platinum-hydrogen complex. Hydrogenation of the samples is achieved by wet-chemical etching at room temperature. Defect profiles, determined by deep level transient spectroscopy, clearly associate the level with the concentration profile of atomic hydrogen. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International journal of colorectal disease 12 (1997), S. 243-245 
    ISSN: 1432-1262
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé. Les résultats de la réparation isolée du sphincter interne ont étéévalués chez cinq patients présentant une incontinence anale persistante après un geste chirurgical ayant lésé le sphincter interne. Tous présentaient une incontinence passive pour les solides et les liquides. Les symptômes, les résultats de la manométrie ano-rectale et de l'échographie endo-anale ont étéévalués avant et après correction chirurgicale. Après l'intervention, trois patients se disent améliorés mais présentent toujours des symptômes persistants; aucun patient n'a retrouvé une continence complète. Trois patients présentent une augmentation de la pression de repos et de la pression de contraction maxi-male mais chez un seul patient, ces valeurs sont dans la limite de la norme. En post-opératoire, l'échographie endo-anale montre une persistance du défect du sphincter interne chez tous les cas et dans deux, cet examen met en évidence une lésion méconnue du sphincter externe. Bien que quelques patients se sentent améliorés, les résultats cliniques manométriques et radiologiques après réparation du sphincter anal interne sont décevants.
    Notes: Abstract. The results of repair to the internal and sphincter alone has been evaluated in five patients with persistent anal incontinence following surgery which affected the internal anal sphincter. All had passive incontinence for solid or liquid stool. Symptoms, anorectal manometry, and anal endosonography were evaluated before and after surgery. After surgery three patients felt improved but had still persistent symptoms, and no patients achieved full continence. Three patients showed an increased maximal and resting pressure, but only one of them was within the normal range. Post operatively, all the anal ultrasound scans showed a persistent internal sphincter defect, and two showed an unsuspected external anal sphincter defect. Although some patients felt symptomatically improved, the overall clinical, manometric and radiological findings after internal and sphincter repair were disappointing.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1262
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé. Le but de cette étude est de déterminer la fiabilité des potentiels évoqués corticaux après stimulation électrique du canal anal. Des potentiels évoqués corticaux ont été enregistrés chez 243 patients se plaignant de douleurs périnéales (28 patients), d'impuissance (55 patients) d'incontinence fécale (52 patients), d'incontinence urinaire (30 patients), de constipation (49 patients), et chez 29 patients neurologiques, par stimulation du sphincter anal externe et du pénis ou du clitoris. La reproductibilité inter- et intra-observateurs a étéétudiée par codage des interprétations données par trois observateurs à l'occasion de deux évaluations distinctes. L'influence des caractéristiques de l'enregistrement et des données cliniques a été déterminée. Afin d'étudier le rôle de l'opérateur, cinq opérateurs ont investigué les patients mais un seul était particulièrement entraîné pour cette investigation. L'interprétation des courbes d'enregistrement par les observateurs était peu reproductible dans 15% des cas, dépendant du temps écoulé entre les deux lectures et dépendant de la qualité de l'enregistrement. L'interprétation de la réponse cérébrale après la stimulation anale est dépendante de l'observateur et influencée par sa connaissance des données cliniques. Ceci a également été observée avec la mesure des potentiels corticaux évoqués après stimulation du pénis ou du clitoris, toutefois dans une moindre mesure. La méthode du potentiel évoqué cérébral est également dépendante de l'opérateur, particulièrement après la stimulation anale. Lorsque une étude des potentiels corticaux évoqués par stimulation périnéale est nécessaire en pratique clinique, il semble logique de préférer la technique des potentiels corticaux évoqués par stimulation du pénis ou du clitoris, car ils semblent plus faciles à obtenir que ceux observés après stimulation anale si les investigateurs ne sont pas particulièrement familiers avec les méthodes électrophysiologiques et, car les premiers sont davantage opérateurs et observateurs dépendants.
    Notes: Abstract. The aim of this study was to assess the reliability of cortical evoked potentials after electrical stimulation of the anal canal. Cortical evoked potentials were recorded on 243 patients presenting with perineal pain (28 patients), impotence (55 patients), anal incontinence (52 patients), urinary continence (30 patients), constipation (49 patients), and on 29 neurological patients, by stimulating the external anal sphincter and penis (or clitoris). The inter- and intra-observer reproducibility was studied by coding recordings interpreted by three different observers on two separate occasions. The influence of recording characteristics and clinical data were assessed. To study operator dependence, five operators investigated the patients. Only one of them was well trained in this technique. The interpretation of the coded curves by the observers was poorly reproducible in about 15% of cases, depending on time between the two readings and the quality of recordings. The interpretation of cerebral responses after anal stimulation were observer-dependent and influenced by the knowledge of clinical data. This was also observed with cortical evoked potentials after electrical stimulation of the penis or clitoris, but to a lesser extent. The cerebral evoked potentials method was also operator-dependent, mainly after anal stimulation. When a study of cortical evoked potentials by perineal stimulation is needed in clinical practice, it seems logical to prefer cortical evoked potentials by penile or clitoral stimulation as they seem easier to obtain than those evoked by anal stimulation if the investigators are not well trained for the performance of electrophysiological studies as the former are much less operator- and observer-dependent.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A search for an abundant and economical source of isoflavones, particularly genistein, led to the discovery that the erythromycin-producing organism Saccharopolyspora erythraea also produces this promising new cancer-prevention agent. Erythromycin fermentation is a large-scale, soybean-based process used world-wide for the commercial production of this medically important antibiotic. Results from this study indicate that genistin (the glucoside form of genistein), which is added to the fermentation in the soybean media, was converted to genistein through the action of a β-glucosidase produced by the organism. Genistein was co-extracted with erythromycin from the fermentation broth, then separated from erythromycin during the second step of the purification process for the production of erythromycin.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2102
    Keywords: Key words Magnetic resonance imaging • Myocardial perfusion • Data evaluation ; Schlüsselwörter MR Bildgebung • Myokardperfusion • Datenauswertung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Zielsetzung: Ziel der Studie war die Erprobung einer Dreischicht Saturation Recovery Turbo FLASH Sequenz bei der Untersuchung der regionalen Myokardperfusion. Für die Datenauswertung stellen wir qualitative und quantitative Nachverarbeitungsmethoden vor, die wir an Probanden und Patienten testeten. Material und Methode: Wir untersuchten 8 gesunde Probanden und 4 Patienten mit Myokardinfarkten. Parameter der verwendeten Saturation Recovery Turbo FLASH Sequenz waren: TR = 2,5 ms, TE = 1,2 ms und α = 8°. Es wurden drei 10 mm dicke Schichten akquiriert. Zur Datenanalyse berechneten wir pixelweise Signalintensitäts-Zeit Kurven und werteten diese nach der Signalintensitätszunahme über den Ausgangswert und Signalintensitätsanstieg aus. Die Ergebnisse stellten wir farbkodiert dar. Zur quantitativen Datenauswertung nach Indikatorverdünnungstheorie entwickelten wir einen Rückfaltungsalgorithmus, der die arterielle Inputfunktion bei der Berechnung der myokardialen Mean Transit Time (MTT) berücksichtigt. Ergebnisse: Mit Hilfe der farbkodierten Parameterbilder konnten normal perfundierte von hypoperfundierte Myokardarealen gut unterschieden werden. Die mit unseres Algorithmus berechneten MTTs waren kürzer als die mit bisherigen Methoden abgeschätzten. Mit aus der Literatur ermittelten MTT Werten stimmten unsere MTTs besser überein. Infarktareale zeigten verlängerte MTTs. Schlußfolgerung: Eine Saturation Recovery Turbo FLASH Sequenz ist für die Untersuchung der regionalen Myokardperfusion in bis zu drei Schichten geeignet. Farbkodierte Parameterbilder können hypoperfundierte Myokardareale qualitativ darstellen. Für eine Berechnung der myokardialen MTT liefert ein Rückfaltungsalgorithmus verbesserte Abschätzungen der myokardialen MTT.
    Notes: Summary Purpose: Purpose of this study was to test a triple slice saturation recovery turbo FLASH sequence for myocardial perfusion imaging. In addition data-evaluation-tools for qualitative and quantitative perfusion parameters are presented and preliminary tested. Material and Methods: We examined 8 healthy volunteers and 4 patients with myocardial infarction. Parameters of the saturation recovery turbo FLASH sequence were as follows: TR = 2.5 msec, TE = 1.2 msec, α = 8 °, 3 slices, thickness 10 mm. For data analysis signal-intensity time curves were calculated pixel by pixel and evaluated for signal-intensity-increase over baseline and signal-intensity-upslope. Images were displayed color-coded. For quantitative data analysis we used the indicator dilution theory and developed a deconvolution algorithm which takes the arterial input function into account to calculate the myocardial mean transit time (MTT). Results: The color-coded parametermaps showed uniform conditions in normal myocardium of volunteers, but reduced signal-intensity-increase over baseline and signal-intensity-upslope for infarcted areas in patients. The MTTs calculated using our algorithm were significantly shorter than those assessed with previous methods and matched better with values derived from literature. Infarcted areas show prolonged MTTs in comparison to normal myocardium. Conclusion: A triple slice saturation recovery turbo FLASH sequence is suitable for myocardial perfusion imaging. Color-coded parametermaps can visualize hypoperfused areas. For calculating myocardial MTTs using indicator dilution therapy a deconvolution algorithm is necessary.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1572-994X
    Keywords: influenza B virus ; hemagglutinin ; evolution ; antigenic drift
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Nucleotide sequences of the hemagglutinin (HA) gene of twelve influenza B strains and their deduced amino acid sequences were extracted from the GenBank and compared to those of early isolates. Separate analyses of nonsynonymous and synonymous substitutions for the HA1 and HA2 regions individually indicate that the percentage of nonsynonymous substitutions in the HA1 ranges from 44.4–56.0% but in the HA2 from 0.0–6.5%. The results suggest that positive selection as well as negative selection played a role in the evolution of the influenza B HA gene with the former acting on the HA1 and the latter on the HA2.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1572-9680
    Keywords: long-term conservation ; Sahel ; seed collection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The International Centre for Research in Agroforestry (ICRAF) coordinates a research network in the Semi-arid Lowlands of West Africa (SALWA) in four countries: Burkina Faso, Niger, Mali and Senegal. Prosopis africana, an important agroforestry tree species is seriously threatened in this eco-region. ICRAF organized seed collections of this species for long-term conservation and subsequent utilization by small-scale farmers in the West African Sahel. Prior to the collection, ICRAF, the International Plant Genetic Resources Institute (IPGRI) and International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) organized a planning workshop with collaborating national research institutes. Out of this workshop came a consensus on the strategy, logistics and choice of collection sites. To collect as much genetic diversity of P. africana in the SALWA region as possible, 34 collection sites were selected: 15 in Niger, eight in Mali, seven in Burkina Faso and four in Senegal. The main aim of the collection was to capture the genetic diversity within P. africana before the valuable genetic resources are lost. This paper reviews the methodology and results of the germplasm collection.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 61 (1997), S. 683-688 
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantum chemical calculations using the density functional theory were performed to model the mechanism of selective catalytic reduction of NO by NH3 on a supported vanadium oxide monolayer. In the first step, the adsorption of NH3 on a bimetallic cluster representative of vanadium oxide, containing a terminal V—O adjacent to a V—OH group, was investigated. The calculations indicate that NH3 may be strongly adsorbed on V=OH (Brönsted acid site) as NH+4(ads); subsequently, NO reacts with this activated NH3 to yield the reaction products N2 and H2O. The present results give support to a dual-site Eley-Rideal-type mechanism involving a Brönsted site. © 1997 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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