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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 41 (2000), S. 3007-3015 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: The Bach equation, i.e., the vacuum field equation following from the Lagrangian L=CijklCijkl, will be completely solved for the case that the metric is conformally related to the Cartesian product of two two-spaces; this covers the spherically and the plane symmetric space–times as special subcases. Contrary to other approaches, we make a covariant 2+2-decomposition of the field equation, and so we are able to apply results from two-dimensional gravity. Finally, some cosmological solutions will be presented and discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 1827-1830 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nitrogen self-diffusion studies in amorphous precursor-derived Si3BC4.3N2 ceramics were carried out, using ion implanted stable 15N isotopes as tracers and secondary ion mass spectrometry for depth profiling. The analysis of the diffusion profiles in the range of 1500–1700 °C did not show the typical Gaussian broadening of the implantation profiles. Instead, we observed the occurrence of a high concentration region where the width of the implantation profile is nearly unchanged due to implantation damage, and a low concentration region where diffusion occurs. The experimentally determined diffusivities obey an Arrhenius behavior with an activation enthalpy of about H=7 eV and a pre-exponential factor D0 in the order of 5 m2/s which indicates a diffusion mechanism via vacancy-like defects. © 2000 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 76 (2000), S. 3173-3175 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose a method for all-optical switching and wavelength conversion using electromagnetically induced transparency (EIT). We discuss the mechanism for the transfer of information in this scheme and determine the conditions for which N×N wavelength conversion can be realized. We compare the properties and limits of an EIT-based switch to conventional wavelength converters. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 19 (2000), S. 201-204 
    ISSN: 1573-4846
    Keywords: ATO ; ITO ; redispersed particles ; transparent conductive coatings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new wet chemical concept to produce coatings by dip, spin or spray processes is presented. It is based on the preparation of solutions made of crystalline nanoparticles fully redispersable in a solvent. It is exemplified for the preparation of SnO2 : Sb (ATO) and In2O3 : Sn (ITO) transparent conducting coatings. The process combines the advantages of using particles having already a low resistivity and the possibility to sinter the coatings at low temperature. The particles are prepared using an in-situ monitoring of the surface energy to control the growth of the particles and to avoid their agglomeration. The dried powders can be fully redispersed in alcohol (ITO) or water (ATO). Single layers with thickness up to 200 nm (ATO) and 400 nm (ITO) have been fabricated. The sheet resistance of the coatings decreases with the sintering temperature. Typical values are 430 Ω□ for ATO (550°C) and 380 Ω□ for ITO (550°C). Sols made by redispersing the powders in organosilanes allow to produce coatings at low temperature with antistatic (R □ 〉 100 kΩ□) and anti-glare properties (R □ 〉 100 kΩ□, 60 to 80 gloss units).
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 19 (2000), S. 39-51 
    ISSN: 1573-4846
    Keywords: sol-gel synthesis ; nanocomposite review ; ormosils ; glass fiber binder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Nanoparticles containing hybrid materials became of interest for many areas in the last decade. The reason for this is the fact that, in addition to the molecular inorganic-organic hybrid network, the physical, electronical, optical or catalytical properties of nanoparticles resulting from the inorganic crystalline, glassy or metallic properties also can be used for the material tailoring. For this reason, a survey is given over some interesting developments. Furthermore, in case studies, examples are given for the effect of nanoparticles on the two component Ormosil type of hybrids composed of ethyl ortho-silicate (TEOS) and methylethoxy(methoxy)triethoxy silane (MTEOS, MTMOS). It was shown that the 6 nm SiO2-containing nanocomposite hybrid sols can be dried in form of thick films up to 14 μm after a one step dip-coating process and densified crack-free. This is attributed to the increase of relaxation ability and flexibility. This nanocomposite based on TEOS, MTEOS and particulate SiO2 has been used to develop an industrial process for a new type of environmentally friendly glass fiber mat with a temperature resistance up to 600°C.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Intensivmedizin und Notfallmedizin 37 (2000), S. 7-18 
    ISSN: 1435-1420
    Keywords: Key words Autonomic dysfunction – heart rate variability – baroreflex sensitivity – chemoreflex sensitivity – intensive care medicine ; Schlüsselwörter Autonome Dysfunktion – Herzfrequenz-variabilität – Baroreflexsensitivität – Chemoreflexsensitivität – Intensivmedizin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Analyse der sympathisch-vagalen Balance vermittelt bei vielen Krankheitsbildern wertvolle Informationen hinsichtlich Prognose und Behandlungsstrategien. Zur Erfassung dieses Parameters bei Intensivpatienten dienen vor allem die Analyse der Herzfrequenzvariabilität und der Baroreflexsensitivität, die wohldefiniert und in großen prospektiven Studien erprobt sind. Die ventilatorischen und kardialen Chemoreflexsensitivitäten dagegen als potentielle Prädiktoren maligner kardialer Arrhythmien und der Prognose bei chronischer Herzinsuffizienz sind zur Zeit Gegenstand intensiver Forschungsaktivitäten. Ziel ist es, die Aussagekraft bei diesen Krankheitsbildern zu validieren. Auch Sepsis und MODS als besonders für die Intensivmedizin relevante Erkrankungen sind mit einer Beeinträchtigung der autonomen Funktion, gemessen als Reduktion der Herzfrequenzvariabilität, verbunden. Die Einschränkung der Herzfrequenzvariabilität bei solchen Patienten ist ein Hinweis auf den Verlust der neuro-humoralen Organinteraktion („Uncoupling of biological oscillators“). Diese Idee scheint im pathophysiologischen Konzept der Sepsis und des MODS zunehmend an Attraktivität zu gewinnen.
    Notes: Summary The assessment of the impaired sympathetic-vagal balance provides in many disorders unique information concerning prognosis and treatment strategies. Especially the indications for using the heart rate variability analysis and the baroreflex sensitivity evaluation are well defined and proven in large prospective studies. The ventilatory and cardiac chemoreflex sensitivities are tools which could improve prediction of malignant cardiac arrhythmias and the prognosis of patients with advanced chronic heart failure. They are at this stage in the focus of intense research. Especially sepsis and MODS, as ICU-relevant disorders, are coupled with an impairment of autonomic function. Thus, the reduction of heart rate variability in such patients culminated in the loss of the nerval-humoral organ interaction (“uncoupling of biological oscillators”) hypothesis. This idea nowadays contributes to the pathophysiological concept of the clinical manifestations of sepsis and MODS.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1435-1285
    Keywords: Key words Coarctation of the aorta ; patent ductus arteriosus ; ventricular function ; heart failure ; surgical repair ; Schlüsselwörter ; Aortenisthmusstenose ; offener Ductus Botalli ; Ventrikelfunktion ; Herzinsuffizienz ; operative Korrektur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Wir beschreiben den Krankheitsverlauf einer 36-jährigen Frau mit unbehandelter Aortenisthmusstenose und offenem Ductus Botalli, die aufgrund einer ausgeprägten linksventrikulären Dysfunktion eine therapierefraktäre Herzinsuffizienz entwickelte. Nach operativer Korrektur der Aortenisthmusstenose und Ductusresektion normalisierte sich die linksventrikuläre Pumpfunktion, sodass davon ausgegangen werden kann, dass auch schwere linksventrikuläre Dysfunktionen auf dem Boden langjähriger Druck- und Volumenbelastung durch angeborene Herzfehler nach operativer Korrektur reversibel sein können.
    Notes: Summary We report on the history of a 36-year-old woman with untreated coarctation of the aorta and patent ductus arteriosus who developed refractory heart failure due to severely impaired left ventricular function. After coarctation repair and duct resection, left ventricular function improved to normal. Even in the presence of longstanding left ventricular pressure and volume overload, subsequent severe myocardial failure may be reversible by surgical repair.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Surgical endoscopy and other interventional techniques 14 (2000), S. 644 -648 
    ISSN: 1432-2218
    Keywords: Key words: Bronchoscopy — Children — Foreign body aspiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: There is still considerable controversy about the diagnostic procedure, the endoscopic approach, and the complication rate with foreign body aspiration in children. Methods: Review of our data for 98 children suspected for foreign body aspiration between January 1990 and December 1998 was performed. Results: In this data review, 78% of the children studied were younger than 2 years. A foreign body aspiration was identified in 70%, and 67% had a definite history of aspiration. Predominant clinical features were fever (46%), pneumonia (39%), and coughing (29%). Pathologic chest radiographs were found in 84% of the children Sixty-two percent of the foreign bodies were trapped in the right lung, and 87% were of organic in origin. In 93%, a single endoscopic procedure was successful in removing the foreign bodies. The mean time between aspiration and bronchoscopic extraction was 5.4 days (range, 1 h to 36 weeks). The procedure-related morbidity rate was 0.96% and the mortality 0. Conclusions: Outcome and complications were found to depend mainly on the time the foreign body stayed in the tracheobronchial system. Early bronchoscopy is paramount in any case of suspected foreign body aspiration, and it is mandatory to increase the awareness of the population and medical professionals.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 247 (2000), S. 81-87 
    ISSN: 1432-1459
    Keywords: Key words Dementia ; Vascular ¶dementia ; Alzheimer’s disease ; Risk factors, stroke ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This review describes differing profiles of vascular risk factors in different types of dementia. Although vascular risk factors are related to various types of strokes, their independent effect on the occurrence of poststroke dementia appears to be small. Various risk factors have been identified for microangiopathy-related cerebral abnormalities, such as white matter changes and lacunae, which are the core lesions for the development of a vascular dementia syndrome without stroke symptoms. Most consistently, arterial hypertension and diabetes mellitus have been found to be associated with such brain abnormalities. Diastolic blood pressure seems to be of particular importance as recent investigations demonstrate that this factor is related to the course of multiple lacunar strokes and the progression of white matter disease. Epidemiological studies report that various vascular risk factors including arterial hypertension, diabetes mellitus, and atrial fibrillation may also be associated with Alzheimer’s disease. There is also evidence of a direct relationship between Alzheimer’s disease and general atherosclerosis. Further investigations are needed to determine whether these associations are due to the weakness of diagnostic criteria, or whether vascular risk factors indeed modulate the clinical expression of primary degenerative dementia. Common susceptibility genes leading to shared risk factors may be one of the reasons for a higher coincidence of Alzheimer’s disease and vascular dementia than can be expected by chance. A modulatory effect of vascular risk factors in the development of primary degenerative dementia may extend treatment options.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    HNO 48 (2000), S. 963-971 
    ISSN: 1433-0458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Bilder und Videos sind die geeigneten Medien zur Dokumentation von normalen und pathologischen Befunden. Zwischen den ersten Farbbildern und der Entwicklung des ersten digitalen Fotoapparats liegen nur 150 Jahre. Wie schnell sich die Technik der digitalen Foto- und Videodokumentation entwickelt und welche Rolle Sie für den HNO-Arzt in Klinik und Praxis spielt, wird in dem nachfolgenden Beitrag beschrieben. Teil 1 befasst sich mit dem digitalen Bild, Teil 2 in der nächsten Ausgabe der “HNO” berichtet über das digitale Video und Möglichkeiten der Archivierung. Die verwendeten Fachausdrücke sind im Glossar am Ende des Beitrags erklärt.
    Type of Medium: Electronic Resource
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