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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6096-6098 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two-dimensional magnetic behavior in thin films and in layered magnets apparently falls into one of only two universality classes. The first is that of the 2D Ising model, characterized by a magnetization exponent β=1/8. The second, with β≈0.23, is observed in systems with planar spin symmetry. Recently it has been shown, using a modified renormalization group calculation, that β=0.23 is a property of a finite size XY model. Although there is no broken symmetry in this system, correlations below the Kosterlitz–Thouless transition temperature decay so slowly that a magnetization occurs in any realizable system, and β=0.23 is a result of two-dimensional fluctuations. By considering a large number of experimental situations we demonstrate that this rule is generally obeyed, and can be used as a test to identify two-dimensional behavior.
    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 75 (1994), S. 5955-5957 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The universal jump in the spin-wave stiffness is a characteristic property of the Kosterlitz–Thouless–Berezinskii phase transition in an infinitely large 2D-XY magnet. It has recently been demonstrated [S. T. Bramwell and P. C. W. Holdsworth, J. Phys. Condens. Matt. 5, L53 (1993)] that finite-size rounding is much more important in two-dimensional than in three-dimensional systems. This is because the properties of the phase transition depend logarithmically, rather than algebraically, on the system size. Consequently, finite-size rounding will be dominant in any real, macroscopic 2D-XY magnet. How the rounded universal jump still exhibits observable universal properties is discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 49 (1994), S. 0 
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
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    London, etc. : Periodicals Archive Online (PAO)
    British journal of psychology. 81 (1990) 483 
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  • 5
    ISSN: 1432-2161
    Keywords: Bone tumour ; Bone neoplasm ; Ewing's sarcoma ; MR imaging ; Chemotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Magnetic resonance (MR) imaging was performed in 26 patients with Ewing's sarcoma of bone preceding and following neoadjuvant chemotherapy, to assess tumour response non-invasively prior to surgery. T1- and T2-weighted spin echo images were obtained. Changes including intra- and extramedullary signal intensities, tumour demarcation, tumour volume and the appearance of residual extramedullary tumour were compared with histopathology of the resected specimens. Reduction of tumour volume was significantly higher in good responders. Other single parameters did not correlate with histologic tumour response. However, when several MR parameters summarized in a classification system were combined, a positive correlation with histopathologic response was found. A limited decrease of tumour volume (〈25%) and/or residual soft tissue mass following chemotherapy correlated with a poor response. An inhomogeneous, well-defined cuff of abnormal tissue encircling the bone and/or radiological disappearance of the soft tissue tumour component following chemotherapy correlated with good response. Twenty-three out of 26 patients were correctly classified by MR as good or poor responders. Minimal residual disease (〈10% of the entire tumour volume), observed histologically, could not be identified with MR imaging. Tumour volume reduction and residual extramedullary tumour, rather than changes of signal intensity, are major features for evaluating the response to chemotherapy in Ewing's sarcoma.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 6 (1993), S. 247-254 
    ISSN: 1572-9605
    Keywords: Melt-texture growth ; YBa2Cu3O7−δ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The melt-texture growth (MTG) method has been shown to be effective in fabricating high-T csuperconducting bulk samples with highly oriented layers of single crystals. The critical current densityJ cof the typical samples are enhanced significantly. Furthermore, making use of the nonzero spatial temperature gradient at certain locations of a common tube furnace, we fabricated Y-123 bulk samples with various dopants allowingJ cup to ≈3.0×104 A cm−2 in our recent investigations. We followed up our project by analyzing the relations among the crucial parameters involved in the modified version of the MTG process. These parameters include the temperature gradient, the time rate of change of temperature, the “growth front” of the crystal, etc. Our study indicates that some of the empty space regions that appear between layers are only shallow “gap lines.” True layers of single crystals do exist, and we present an explanation for the growth of crystal layers along special directions as observed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 6 (1993), S. 19-25 
    ISSN: 1572-9605
    Keywords: Isotope effects ; YBa2Cu3O7 ; Cooper pairing interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The recent oxygen isotope effect measurement made in the system YBa2-x La x Cu3O7 (0≤x≤0.5) is analyzed using the “two-carrier” model which describes a superconducting system as a mass anisotropic system consisting of charge carriers with two different masses as a result of lattice defects or oxygen deficiency. The extent to which Ba, Cu, and O atoms participate in the phonon-mediated Cooper pairing interaction is elucidated. The relationship between the theoretically deduced mass anisotropic factor andT c agrees closely with the experimental results of Uemuraet al. [28]. Furthermore, the superconducting energy gap toT c ratio is found to be close to 3.5. Excellent agreement is also achieved between the theoretically calculated oxygen isotopic constant and the experimental results of Bornemann and Morris [12].
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 6 (1993), S. 327-334 
    ISSN: 1572-9605
    Keywords: YBa2Cu3O7−δ ; transmission electron microscope ; grain alignment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Previously, we have observed that parallel lattice fringes show up regularly in MTG samples, indicative of good alignment of unit cells in strips of size ∼ 100 nm × a few times 100 nm. We have prepared films (∼ 80 nm) for TEM observation using YBCO material fabricated by the conventional solid-state reaction method in order to study the crystal texture in a length scale from a few 100 nm down to ∼3 Å. Parallel lattice fringes are observed to stretch across a cross-section ∼0.3×0.5 μm2. Cross lattice fringes intersecting at 90° and 45° are observed as rare events. This result suggests that the degree of alignment in the crystal texture is higher than expected inside a grain of size ∼ a few μm.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 6 (1993), S. 365-372 
    ISSN: 1572-9605
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract In our previous work we showed that gradients of temperatureT inside the heating chamber and∂T/∂t are the necessary conditions for growing oriented crystal layers inside bulk samples. Using a simple muffle furnace, we have successfully fabricated “layers” of YBCO samples. Powder layers of Y-123 and Y-211 in different structures were compressed to make sample pellets before heat treatment in order to create internal temperature gradients inside the samples when they were heated. SEM observation proved that the crystal layers grew from both the top and bottom surfaces of the sample independently of the original powder layers before heat treatment. Moreover, we found that the crystal layers are not “true layers” but “bulk crystal with gap lines.” EDX analysis confirmed that the 123 and 211 phases coexist in almost all of the samples. Using the concept of internal temperature gradients, we show that it is possible to carry out modified melt-texture growth even in a muffle furnace.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-2161
    Keywords: Bone tumour ; Bone neoplasm ; Ewing's sarcoma ; Chemotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A uniform classification of response to chemotherapy is essential to allow comparison of local effect and ultimate prognosis between different therapy schedules. We define a histological grading system for assessment of the response to chemotherapy in Ewing's sarcoma, based on the amount and architectural pattern of residual histologically viable-appearing tumour, the preferential sites of minimal residual tumour and the amount of tumour necrosis. Twenty-six consecutive patients with a biopsy-proven Ewing's sarcoma were treated with chemotherapy prior to surgery. The effect of chemotherapy was evaluated microscopically on the specimens obtained after surgery. Response to chemotherapy was classified as minimal or no effect (〈10% tumour necrosis), moderate effect (solid areas of remnant viable tumour), minimal residual disease, and no evidence of disease (100% tumour necrosis or well-vascularized fibrous tissue). The subperiosteal area in particular, and, less frequently, soft tissues and intramedullary compartment were identified as sites of predilection for persistence of microscopic viable tumour foci, frequently depicted as pseudo-rosettes in a characteristic scattered pattern. Although it is not well known whether morphological viability of these residual clusters in Ewing's sarcoma indicates biological viability, accurate preoperative local staging, with special attention to preferential sites of residual viable tumour, is essential. The proposed grading system can be used to standardize assessment of chemotherapy in trials, and may serve as a standard for non-invasive monitoring of preoperative chemotherapy with magnetic resonance imaging.
    Type of Medium: Electronic Resource
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