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  • 2000-2004  (3)
  • 1990-1994  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 8 (2001), S. 773-775 
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The structure of implantation-induced damage in Ge has been investigated using high resolution extended X-ray absorption fine structure spectroscopy(EXAFS). EXAFS data analysis was performed with the Cumulant Method. For the crystalline-to-amorphous transformation, a progressive increase in bond-length was observed without the presence of an asymmetry in interatomic distance distribution (RDF). Beyond the amorphization threshold the RDF was dose dependent and asymmetric, where the bond-length and asymmetry increased as functions of ion dose. Such an effect was attributed to the formation of three- and five-fold coordinated atoms within the a morphous phase. Low-temperature thermal annealing resulted in structural relaxation of the amorphous phase as evidenced by a reduction in the centroid ,asymmetry and width of the RDF, as consistent with a reduction in the fraction of non four-fold coordinated atoms.The results have been compared to other EXAFS studies of amorphous Ge, and it issuggested thatthe range of bond-lengths reported therein is related to the sample preparation method and state of relaxation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-7276
    Keywords: carcinoembryonic antigen ; circulating tumour cells ; colorectal cancer ; false positive results ; RT-PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We assessed whether circulating cell positivity using RT-PCR for carcinoembryonic antigen (CEA) cDNA was affected by venesection via a needle compared/with a pre-aspirated venous cannula, and by increased PCR cycles. Systemic blood was sampled by needle and pre-aspirated cannula in 101 healthy individuals with no cancer history. After erythrocyte removal, samples were subjected to RT-PCR using specific primers for CEA, with 29 or 35 RT-PCR cycles. There was a significant difference between the number of subjects whose samples were negative when collected via needle venesection and positive when collected via pre-aspirated cannula, compared with positive by needle venesection and negative by pre-aspirated cannula for both 29 (P=0.016) and 35 (P=0.011) RT-PCR cycles. Venesection technique (P=0.01) and number of cycles (P=0.003) were significant predictors of a positive result. Positive results in healthy subjects were reduced to less than 3% when an aspirated cannula was used for venesection and 〉29 PCR cycles were avoided.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Using angle-dependent photoemission spectra of core and valence levels we show that metallic, single crystal K3C60 is terminated by an insulating or weakly-conducting surface layer. We attribute this to the effects of strong intermolecular correlations combined with the average surface charge state. Several controversies on the electronic structure are thereby resolved.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of intelligent manufacturing 2 (1991), S. 261-268 
    ISSN: 1572-8145
    Keywords: AI ; neural networks ; expert system ; process control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper presents an architecture which combines artificial neural networks (ANNs) and an expert system (ES) into a hybrid, self-improving artificial intelligence (AI) system. The purpose of this project is to explore methods of combining multiple AI technologies into a hybrid intelligent diagnostic and advisory system. ANNs and ESs have different strengths and weaknesses, which can be exploited in such a way that they are complementary to each other: strengths in one system make up for weaknesses in the other, andvice versa. There is, presently, considerable interest in ways to exploit the strengths of these methodologies to produce an intelligent system which is more robust and flexible than one using either technology alone. Any process which involves both data-driven (bottom-up) and concept-driven (top-down) processing is especially well suited to displaying the capabilities of such a hybrid system. The system can take an incoming pattern of signals, as from various points in an automated manufacturing process, and make intelligent process control decisions on the basis of the pattern as preprocessed by the ANNs, with rule-based heuristic help or corroboration from the ES. Patterns of data from the environment which can be classified by either the ES or a human consultant can result in a high-level ANN being created and trained to recognize that pattern on future occurrences. In subsequent cases in which the ANN and the ES fail to agree on a decision concerning the environmental situation, the system can resolve those differences and retrain the networks and/or modify the models of the environment stored in the ES. Work on a hybrid system for perception in machine vision has been funded initially by an Oak Ridge National Laboratory seed grant, and most of the system components are operating presently in a parallel distributed computer environment.
    Type of Medium: Electronic Resource
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