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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 10 (1988), S. 915-932 
    ISSN: 0392-6737
    Keywords: Quantum effects on the structure and dynamics of nondegenerate fluids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto In questo lavoro si applica la teoria della matriceU per dedurre un'espressione esplicita per lo spettro d'energia di eccitazione dell'4He liquido. Usando un modello per il potenziale chimico efficace per l'4He si è in grado di produrre uno spettro di eccitazione molto simile a quello osservato. L'inverso della massa efficace, cioè 1/m *, è ottenuto in funzione del momentok. Si trova che il rapporto tra massa efficace e la massa dell'atomo di elio ak=2.0 Å−1, cioè vicino alla profondità del rotore, èm * (k=2.0 Å−1)/m He= =0.18298, mentre quello ak=1.0 Å−1 èm * (k=1.0 Å−1)/m he=−0.17103. Il risultato teorico dello spettro di eccitazione è coerente con i dati sperimentali.
    Abstract: Резюме В этой статье мы применяем теориюU-матрицы для вывода явного выражения для энергетического спектра возбуждений Зидкого4He. Используя модель для эффективного химического потенциала для4He, мы воспроизводим спектр возбуждений который оказывается очень близким к зкспериментально наблюдаемому. Вычисляется обратная величина эффективной массы, т.е. 1/m *, как функция импульсаk. Получено отношение эффективной массы к массе атома гелия приk=2.0 Å−1, которое составляетm * (k=2.0 Å−1)/m He=0.18298, тогда как это отношение приk=1.0 Å−1 равноm * (k=1.0 Å−1)/m He=−0.17103. Теоретический результат для спектра возбужений согласуется с имеющимися экспериментальными данными.
    Notes: Summary In this paper, we apply theU-matrix theory to derive an explicit expression for the excitation energy spectrum of liquid4He. Using a model for the effective chemical potential for4He, we are able to produce an excitation spectrum which is very close to the observed one. The inverse of the effective mass,i.e. 1/m *, is obtained as a function of momentumk. The ratio between the effective mass and the mass of helium atom atk=2.0 Å−1,i.e. near the roton depth, is found to bem *(k=2.0 Å−1)/m He=0.18298, while the ratio atk=1.0 Å−1 ism *(k=1.0 Å−1)/m He=−0.17103. The theoretical result of the excitation spectrum is consistent with observational data.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 10 (1988), S. 247-276 
    ISSN: 0392-6737
    Keywords: Boson degeneracy and superfluidity of helium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Impiegando la teoria della matriceU nella forma presente, abbiamo presentato una teoria microscopica di un sistema interagente diN bosoni a temperatura non nulla. L'hamiltoniana include un termine che descrive l'influenza esterna, un termine per un'interazione a 2 particelle e une che riguarda l'interazione di tipo dipolare. Per studiare lo stato fondamentale dell'4He liquido s'include solo l'interazione a 2 particelle. Basandoci su dati di scattering, abbiamo dedotto la funzione potenziale a 2 particelle. Con quella, calcoliamo numericamente la distribuzione dell'impulso aT=1.1K per diversi gruppi di parametri. Si mostra che le curve teoriche sono in buon accordo con i risultati osservati. Le corrispondenti curve del fattore di struttura del liquido si adattano benissimo ai dati misurati e il risultato migliore per l'energia dello stato fondamentale è − 7.12K.
    Abstract: Резюме Используь теориюU-матрицы, мы предлагаем микроскопическую теорию взаимодеюствующейN-бозонной системы при ненулевых температурах. Гамильтониан включает член, описывающий внешнее влияние, член двух-частичного взаимодействия и член, относящийся к дипольному типу взаимодействия. При исследовании основного состояния шидкого4He учитяватся только двух-частичное взаимодействие. Основываясь на данных по рассеянию, мы выводим двух-частичную потенциальную функцию. Мы численно определяем распределение по импульсам приT=1.1K для некоторых систем параметров. Показывается, что теоретические кривые согласуются с наблюденными результатами. Соответст вующий структурный фактор зидкости хорошо согласуется с экспериментальными данными. Полученная величина энергии основного состояния составляет −7.12 K.
    Notes: Summary Employing theU-matrix theory in the present form we have presented a microscopic theory of an interactingN-boson system at nonzero temperature. The Hamiltonian includes a term describing the external influence, a term for a two-particle interaction and one pertaining to the dipole-type interaction. To study the ground state of liquid4He, only the two-particle interaction is included. Based on scattering data, we have deduced the two-particle potential function. With that we calculate numerically the momentum atT=1.1 K for several sets of parameters. It is shown that the theoretical curves agree well with the observed results. The corresponding liquid-structure-factor curves fit the measured data very well and the best result for the ground-state energy is −7.12K.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Haemophilia 10 (2004), S. 0 
    ISSN: 1365-2516
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary.  Acquired factor VIII inhibitor causes a rare but life-threatening form of bleeding disorder, owing to the formation of auto-antibodies against FVIII. Treatment modalities include the use of immunosuppressive drugs such as cyclophosphamide and corticosteroids, plasmapheresis and i.v. immunoglobulin. A patient with idiopathic acquired FVIII inhibitor presented with serious bleeding complications resistant to all the above therapeutic modalities. Treatment with cyclosporin, however, resulted in a prompt and complete response. The lack of side-effects and the relatively quick response suggest that cyclosporin may be tried as front line treatment for patients with acquired FVIII inhibitors.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 13 (2000), S. 393-400 
    ISSN: 1572-9605
    Keywords: spin gap ; ion size ; magnetic doping ; resistivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Y(Ba1−x Gd x )2Cu3O7−δ compounds with x = 0 ∼ 0.15 are prepared using the solid reaction technique. With structure analysis by Rietveld refinement of x-ray diffraction, we find that Gd3+ ions prefer to occupy Y sites within lighter doping x ≤ 0.08 due to ion size effects, then begin partially to occupy Ba sites with doping content increasing, which gives vital influence on superconductivity and spin-gap properties. The magnetic doping effects of Gd3+ ions on spin-gap properties are investigated in detail by contrast of the distinguished behaviors between T* and T c, indicating that spin-gap temperature is not completely determined by the carrier density, but strongly dependent on the strength of interplane antiferromagnetic coupling. Finally, we propose an expression of in-plane resistivity dependent on the maximal width of spin-gap Δ0 to derive their values for different samples, which almost keep constant with the increase of Gd doping contents.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 9 (1996), S. 551-554 
    ISSN: 1572-9605
    Keywords: Iodometric titration ; superconductor ; indicator ; oxygen content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We present an improved double titration method for high-T c superconductors, in which the major step is adding KSCN as an indicator of the end point after the starch end point. By adding it, a greater amount of Na2S2O3 solution can be added after the starch end point, at least 0.12 ml. We found that adding KSCN can lead to precise measuring results and reduce the experimental error. The oxygen contents of two series of superconductors were determined by this approach. For YBa2Cu3O y , the errors are Δp∼0.003 and Δy∼0.005, which are lower than that of other reports.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 4 (1991), S. 461-467 
    ISSN: 1572-9605
    Keywords: High-T c superconductors ; size quantization ; superconductor-semiconductor arrays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Subsequent to our observation that the Tl- and Bi-based cuprate high-T c superconductors are built of superconductor-semiconductor arrays (P. C. W. Fung and W. Y. Kwok,J. Superconduct., this issue), we investigate in this paper the possibility ofT c enhancement arising from the effect of change of phonon spectrum and the effect of size quantization when one or more semiconductor blocks is attached to the basic superconductor in the unit cell.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 30 (1978), S. 621-629 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Measurements of the mechanical quality factor Q in a single crystal of silicon vs. temperature have been made. A value of 2 × 109 has been measured at T = 3.5K.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 44 (1981), S. 259-264 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Two new internal friction peaks have been observed in single-crystal silicon in the temperature range from 100 to 270 K of the Arrhenius-type relaxation at kilohertz frequencies. The activation energies of the two peaks are 0.14 and 0.20 eV. We attribute them to vibration of trapped interstital oxygen and the oxygen-vacancy complex, respectively.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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