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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 24 (1981), S. 107-112 
    ISSN: 1432-0630
    Keywords: 06.30 F ; 32 ; 35 ; 52-55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Observation with an improved signal-to-noise ratio of the hyperfine resonance pattern of199Hg+ stored in a radiofrequency trap is reported. A frequency control loop which locks the frequency of a 5MHz quartz crystal oscillator to the hyperfine transition of stored mercury ions, close to 40.5 GHz, is described. In this system, pulses delivered by the photomultiplier are processed digitally. Optimal conditions for the interrogation of the hyperfine transition are specified. A fractional frequency stability σy(τ)=3.6×10−11τ−1/2 for 10s〈τ〈3500s has been obtained. This frequency stability is comparble to that of commercially available cesium beam frequency standards. Prospect for improvement by a factor of at least 10 are discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2161
    Keywords: Key words Bone graft ; Vascularized bone graft ; Limb salvage surgery ; Bone tumor ; Children ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. To describe the imaging findings of vascularized fibular grafts (VFG) in large bone reconstruction in children and teenagers. Design and patients. Fifteen patients aged from 4 to 19 years underwent VFG for bone reconstruction for primary tumors involving bone in 13 cases and for chronic osteomyelitis in 2 cases. Lesions were located in the femur (6 cases), the tibia (6 cases), the humerus, the distal fibula and the ilium. Radiographic follow-up was performed in all patients, radionuclide studies in 12 patients and MRI in 8. Results. Plain films showed a lamellated periosteal reaction on the VFG within 3 weeks following the procedure in all cases. Fusion of VFG and host bone occurred during the first 3 months. Radionuclide uptake of the VFG was seen in all cases but one. MRI showed cortical thickening and conservation of the high signal intensity of fatty marrow on T1-weighted sequences, and periosteal enhancement on dynamic post-contrast studies in all but one of the patients. Conclusion. Radionuclide studies and MRI show the periosteal enhancement and assess the viability of the VFG satisfactorily. However, we feel that plain films may be sufficient to ascertain this viability.
    Type of Medium: Electronic Resource
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