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  • 1
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 2308-2314 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Measurements for the determination of the complex permittivity of liquid and solid materials based on the use of whispering gallery (WG) dielectric resonators are presented. The procedure implies the measurement of the electromagnetic parameters of the involved resonator interacting with the material under study. The field distribution in the different WG resonant modes was obtained by an analytical calculation under the mode matching method approximation. The results of this calculation, combined with the experimental data, well account for the values of the complex permittivity of materials of interest. Due to the peculiar properties of WG resonators, the method shares the advantages of the wideband systems with the sensitivity and accuracy of the resonator systems in dielectric measurements. Dielectric permittivity of alumina (Al2O3) and of cyclohexane is measured in the frequency range 18–26 GHz. The overall accuracy of the measurements is discussed and the different sources of errors analyzed. Specific attention is paid to the measurements of variations of dielectric properties to monitor some physico–chemical processes. Finally, preliminary measurements at hundreds of GHz show that the procedure is particularly useful for study of dielectric properties up to the THz frequency region. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4122-4127 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Experiments of microwave spectroscopy of gases at low pressures are performed with some advantages using dielectric waveguide cells. The construction of an improved version of a dielectric waveguide spectrometer is described. Details on the experimental methods utilized for gas handling and for the observation of some absorption lines of HNO3, O3, and H2O in the 18–26.5-GHz frequency band, and of the CS radical at 49 GHz are given.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1787-1793 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A probe head especially useful for electron paramagnetic resonance (EPR) spectrometers working at high field—high frequency is presented. The probe head is based on the whispering gallery mode dielectric resonators that proved very effective in the ultrahigh frequency range. The excitation network uses a properly shaped dielectric waveguide sharing its external field pattern with the field of the resonators. Very simple resonators made with polyethylene in both single and doubly stacked disk configurations are used. The experimental characterization by a submillimeter network analyzer shows for the resonances studied in a wide range of frequencies up to (approximate)400 GHz high loaded merit factor QL values and good coupling factors. Resonators also maintain their general characteristics when large quantities of low loss samples for EPR measurements are properly inserted. Preliminary EPR spectra of diphenylpicrylhyldrazyl at 7 and 10 T obtained with the novel apparatus are finally presented. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd.
    Journal of the European Academy of Dermatology and Venereology 18 (2004), S. 0 
    ISSN: 1468-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Cutaneous necrosis is an infrequent but well-documented complication of oral anticoagulants. In the pathogenesis of cutaneous necrosis induced by oral anticoagulants recent hypotheses favour the combined role of local factors and a transient unbalance of coagulation mechanisms leading to an hypercoagulable state. There exists a genetic factor that determines a decreased level of two vitamin-K dependent glycoproteins, namely protein C and protein S. We present the case of an obese woman that developed an extensive cutaneous necrosis while receiving acenocoumarol for a deep venous thrombosis. She had an heterozygous deficit for protein C. The histopathologic findings of vessel thrombi and red blood cell extravasation were consistent with the clinical picture. A biopsy specimen taken from an initial lesion disclosed images of leucocytoclastic vasculitis. We reviewed the literature focusing on the pathogenesis and the histopathology of the disease.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Journal of the European Academy of Dermatology and Venereology 19 (2005), S. 0 
    ISSN: 1468-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Bazex syndrome is a paraneoplastic dermatosis characterized by acral psoriasiform lesions associated with an underlying neoplasm. We present the case of a 64-year-old patient that was diagnosed with squamous cell lung carcinoma after being evaluated for lesions compatible with paraneoplastic acrokeratosis. With a high frequency Bazex syndrome is the earliest marker of an underlying subclinical neoplasm. An early suspicion is of the outmost importance in order to perform a prompt diagnosis of an underlying malignancy. We propose a diagnostic algorithm upon suspicion of acrokeratosis paraneoplastica and review the pathogenesis of this entity.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Il nuovo cimento della Società Italiana di Fisica 3 (1984), S. 673-681 
    ISSN: 0392-6737
    Schlagwort(e): Atomic and molecular measurement and techniques
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Beschreibung / Inhaltsverzeichnis: Riassunto Si studia il comportamento di, un risuonatore di zaffiro alla frequenza di 50 GHz ed a temperature variabili tra 20 e 850 °C. Si danno le misure del coefficiente termico della frequenza di risonanza tra 20 e 850°C e del fattore di merito a 850°C. Si forniscono dettagli sul montaggio del risuonatore in una struttura aperta, priva di pareti metalliche esposte al campo e.m. che circonda il risuonatore.
    Kurzfassung: Резюме Исследуются параметрьи сапфирового резонатора на частоте 50 ГГц. Измеряются тепловой козффиициент для резонансной частотьи ивеличина добротности в области температур от 20 до 850°C. Резонатор представляет конфичурацию с открьтой структурой без металлических частей. Резонатор позволяет работать при вьисоких температурах иего добротность зависит тольло от внутренних диэлек-трических потерь кристалла. Полученньие результатьи покзяивают, что сапфировый резонатор может работать при температурах вплоть до 850°C.
    Notizen: Summary The resonant-frequency temperature coefficient andQ-value of a sapphire resonator at 50 GHz has been measured at temperatures ranging from 20 to 850°C. The resonator operates in an open-structure configuration, without any metal part. In this way it is possible to work at high temperatures, theQ-factor being affected only by the intrinsic dielectric losses of the crystal. The results indicate that the sapphire resonator is well suited for applications up to 850°C.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1420-9071
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Abnormally high serum levels of the soluble receptor of human T lymphocytes for sheep erythrocytes were found, by electroimmunodiffusion, in patients with carcinoma or other solid tumors, leukemia, lymphoma, uremia and lepromatous leprosy.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Il nuovo cimento della Società Italiana di Fisica 1 (1982), S. 49-69 
    ISSN: 0392-6737
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Beschreibung / Inhaltsverzeichnis: Riassunto Quando vapori di potassio sono illuminati dalla luce di un laser a colorante risonante con la transizione fondamentale 4S→4P, si osservano transizioni sia da livelli atomici molto alti, sia dalivelli molecolari. In questo articolo si descrive uno studio spettroscopico di questi fenomeni e si dà la prova sperimentale che il meccanismo responsabile della popolazione di alcuni dei livelli non direttamente eccitati dal laser richiede la creazione di un plasma nel vapore.
    Kurzfassung: Резюме Обпучение паров калия лазером на красителях с основными переходами 4S→4P приводит к возбуждению высоколежащих атомных и молекулярных состояний. В этой работе мы сообщаем резулбтаты спектроскопических исследований этого явления и экспериментальное подтверждение, что механизм, ответственный за заселение некоторых уровней, в результате не прямого возбуждения лазером, включает образование плазмы в паре.
    Notizen: Summary The illumination of potassium vapour by means of a c.w. dye-laser resonant with the fundamental 4S→4P transitions results in the excitation of high-lying atomic and molecular states. In the present paper we report a spectroscopic study of this phenomenon and experimental evidence that the mechanisms responsible for the population of some of the levels not directly excited by the laser involve the creation of a plasma in the vapour.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Il nuovo cimento della Società Italiana di Fisica 16 (1994), S. 117-126 
    ISSN: 0392-6737
    Schlagwort(e): Intensities and shapes of molecular spectral lines and bands ; Atmospheric optics ; Optical spectroscopy and spectrometers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Summary Diode laser spectroscopy of ammonia ro-vibrational overtone transitions has been performed in the near IR, by using direct absorption, wavelength modulation, and two-tone frequency modulation techniques. Pressure broadening coefficients in air, hydrogen, helium and self-broadening have been measured. The high sensitivity of the apparatus permitted the detection of 70 p.p.m. of NH3 in air per meter of path at atmospheric pressure. New lines have been observed in the 719.9 nm band.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Il nuovo cimento della Società Italiana di Fisica 13 (1991), S. 677-685 
    ISSN: 0392-6737
    Schlagwort(e): Intensities and shapes of molecular spectral lines and bands ; Atmospheric optics ; Laser beam propagation ; LIDAR measurements
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Summary Diode laser spectroscopy of water vapour has been performed in the near IR and the pressure broadening coefficients in nitrogen and in air have been measured for one rotovibrational line. Detection of water vapour in the atmosphere has been obtained and an evaluation of the sensitivity of our apparatus is reported. Discussion for further improvements is made.
    Materialart: Digitale Medien
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