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  • 1
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective To investigate the use of a digital imaging system for colposcopy, its use for image analysis and quantification of the colposcopic features that may predict histological outcome as defined by large loop excision of transformation zone.Design Prospective programme study of all patients undergoing colposcopy for cytological abnormalities.Setting Dudley Road Hospital, Birmingham.Subject Fifty consecutive patients having cytological and colposcopic abnormality treated with large loop excision of transformation zone formed the study group.Main outcome measures Pretreatment and colposcopic features correlated with histological diagnosis of excised transformation zone.Results Index cytology and current smoking status are the most important variables for prediction of histological diagnosis. Other important variables are focality of lesion, surface pattern, intercapillary distance and degree of acetowhiteness.Conclusion Digital imaging colposcopy allows image capture, processing and objective analysis. This methodology holds advantages for basic and clinical research, teaching, diagnostics and clinical audit. The system can act as a quality control tool for colposcopy units. This system should prove invaluable for further quantitative studies, for natural history studies and for those patients with deferred treatment of their cytological and colposcopic abnormalities. The statistical models described may be incorporated into the system and can aid the colposcopist in management of the woman with abnormal cervical cytology and colposcopic abnormality.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 60 (1993), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 1676-1680 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetic and structural properties of pulsed laser deposited MnZn–ferrite films have been examined. The results show that the uniaxial anisotropy, ferromagnetic resonance linewidth and coercive force are strongly influenced by the microstructure of the films, and the saturation magnetization and first-order magnetocrystalline anisotropy constant depend on intrinsic properties such as composition and cation site occupation. A comparison of bulk and film magnetic properties shows that the magnetic properties of the films are comparable to the bulk, which makes pulsed laser deposition ferrite films a prime candidate for thin film high-frequency microwave device applications.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6740-6740 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The series of compounds Pb2Sr2(R/Ca)Cu3O8, (R=Ce-Tm) are known to superconduct at temperatures as high as Tc=84 K. We have studied the relationship between superconductivity and magnetism in the Ce and Pr analogs. In addition, we report the synthetic route and the magnetic properties of the actinide analog Pb2Sr2(Cm/Ca)Cu3O8. The parent compound Pb2Sr2CmCu3O8 is not a superconductor, but shows evidence of long range magnetic ordering at about 18 K. This is a much higher temperature than is observed for any of the other R-ion parent compounds. These results will be discussed in terms of the different hybridization and bonding properties of the 4f and 5f electrons, and how these differences influence superconductivity. These results will be compared with the Pr and Cm analogs of the other superconducting series RBa2Cu3O7 and R2−xThxCuO4.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 1489-1496 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The local environment of Cm3+ in a borosilicate glass has been probed by a combination of laser spectroscopy, structural modeling, and extended x-ray absorption fine structure (EXAFS) spectroscopy. The Stark splitting for the Cm f–f state transitions is significantly larger than the inhomogeneous line broadening that results from the disordered environment. As a result, the Cm optical spectrum can be fit using an effective operator Hamiltonian to obtain a set of crystal-field parameters. The fitting procedure, which requires the use of a descent-in-symmetry approach, provides a set of parameters for a best fit within tetragonal symmetry. These parameters are then linked to the local environment of Cm through exchange-charge modeling (ECM) of crystal field interactions. Cm in our borosilicate glass is best modeled with six oxygen ions with approximately tetragonal symmetry, and at an average distance of 2.31 (3) Å. The results of crystal-field modeling are supported by EXAFS results. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 8277-8289 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report a systematic analysis of the crystal-field spectra of four fluoride compounds containing tetravalent actinide ions. The first part of this work [J. Chem. Phys. 95, 7194 (1991)] provided interpretation of the absorption spectra of UF4, NpF4, and PuF4. To extend our analysis to heavier elements of the series, low-temperature absorption spectra of AmF4 and CmF4, and site selective laser-induced emission and excitation spectra of Cm4+:CeF4 and Bk4+:CeF4 were obtained. A model energy level calculation was found to be in good agreement with the experimental results. It is shown that the crystal-field interaction in combination with spin–orbital coupling results in significant J mixing in the excited states, but ground state wave functions are still relatively pure in J character for the tetravalent actinide ions Am4+, Cm4+, and Bk4+. Trends in the parameters of the effective operator Hamiltonian are compared with those of a Hartree–Fock free-ion model. Interpretation of the ground-state splitting of the nominal S-state ion Bk4+ in CeF4 and color center formation in AmF4 are also discussed.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The principal factors that limit intensities of short-lived radioactive ion beams produced by the isotope separator on-line technique are time delays due to diffusion of radioactive species from solid or liquid target materials and their effusive-flow transport to the ion source. Although diffusion times can be reduced by proper design of short diffusion length, highly refractory targets, effusive-flow times are more difficult to assess. After diffusion from the target material, the species must travel through the target material and vapor transport system to the ion source. The time required for effusive-flow transport to the ion source depends on the conduction path, chemical reactions between the species and target material and materials of construction, as well as the physical size and geometry of the transport system. We have developed a fast valve (0.1 ms closing time) for introducing gaseous or vapor-state species into the target/vapor transport/ion source/system that permits measurement of effusive-flow times for any gaseous or vaporous species (chemically active or chemically inactive) through any vapor transport system, independent of size and geometry. Characteristic times are determined from the exponential decay of the momentum analyzed ion beam intensity for the species during effusive flow through the vapor transport system under evaluation. This article describes the effusive-flow apparatus and presents characteristic time spectra and characteristic effusive-flow time data for noble gases flowing through a serial-flow target reservoir system. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Since modern high frequency device technology is shifting towards planar miniaturization, ferrite films will play an important role in facilitating the design and fabrication nonreciprocal monolithic integrated devices such as isolators and circulators. The authors have examined magnetic and structural properties for a series of pulsed laser deposited (PDL) single crystal MnZn-ferrite films. The films were epitaxially grown on (001) MgO at substrate temperatures of 300 °C, 400 °C, 600 °C, and 800 °C in an oxygen partial pressure of 30 mTorr. The film microstructure, crystal structure, and composition were characterized by SEM, x-ray diffraction and atomic absorption spectroscopy, respectively. The magnetocrystalline anisotropy constant K1, uniaxial anisotropy constant Ku, saturation magnetization Ms, and coercive force Hc were examined by torque and vibrating sample magnetometry. Ferrimagnetic resonance measurements were made on the films to obtain the linewidth ΔH. A comparison of the magnetic, structural, and chemical properties shows that K1 and Ms scale with the Fe2+ ion concentration and that Ku, Ms, and ΔH are very sensitive to the microstructure. The values of K1, Ms, and ΔH obtained for films deposited at 800 °C were compared with those of bulk MnZn-ferrite and found to exceed the bulk values (Table I), thus making PLD ferrite films very attractive for nonreciprocal device applications.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5321-5321 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin films of Fe with interleaved Cr have generated considerable interest because of the antiferromagnetic coupling between the Fe layers. This coupling has been examined using ferromagnetic resonance and other measurements. The results have been explained on the basis of the phenomenological expression for the magnetic free energy. We have determined the magnetic free energy for a single-crystal Fe/Cr/Fe(001) sandwich grown by molecular beam epitaxy using torque magnetometry. At fields below the anisotropy field, both the torque and free energy show a complex switching of the antiferromagnetically coupled Fe moments (Fig. 1). Preliminary calculations show that the exchange and the angle between the antiferromagnetically coupled Fe moments can be determined directly from these curves. We shall discuss our measurements and calculations and compare our results with the earlier ferromagnetic resonance results.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 4620-4633 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hole trapping phenomena in SiO2 were examined using an optically assisted hot carrier injection technique on p-channel insulated gate field effect transistors. It was found that only a single, field-dependent, capture-cross-section hole trap is present. The capture cross section of these hole traps at a field of 4 mV/cm across the gate insulator, corresponding to a gate voltage just above the threshold voltage, was found to be 8.5×10−14 cm2. Injected holes were found to trap with an initial efficiency of approximately 60% at this gate field. Depopulation of trapped holes at room temperature was also examined, and found to be significant. The neutral hole trap density in unirradiated device gate insulators after post-metal annealing was found to be approximately 7.0×1012 cm−2. Based on a study of the threshold voltage shift as a function of gate insulator thickness, coupled with the model recently proposed by Walters and Reisman for determining charge centroid, it appears that for oxides with thicknesses greater than 10 nm, the hole traps lie in a band of finite thickness with a charge centroid 5 nm from the substrate-SiO2 interface. In addition, there exists a layer approximately 3.7 nm thick at each interface that appears void of trapped charge. Therefore, oxides less than 7.4 nm thick should not trap charge, which was found to be the case experimentally. This implies that as devices are scaled down, hole trapping will disappear, which is of particular significance in oxides subjected to ionizing irradiation, either during processing or during use.
    Type of Medium: Electronic Resource
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