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  • 1990-1994  (6)
Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Microbial ecology 19 (1990), S. 251-257 
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Escherichia coli, Pseudomonas fluorescens, and aPseudomonas sp. strain 133B containing the pSa plasmid were starved in well water for up to 523 days. There were two patterns of apparent antibiotic resistance loss observed. InPseudomonas sp. strain 133B, there was no apparent loss of antibiotic resistance even after starvation for 340 days. InE. coli, by day 49 there was a ten-fold difference between the number of cells that would grow on antibiotic- and nonantibiotic-containing plates. However, over 76% of the cells that apparently lost their antibiotic resistance were able to express antibiotic resistance after first being resuscitated on non-selective media. By day 523, only 12% of these cells were able to express their antibiotic resistance after being resuscitated. After starvation for 49 days, cells that could not grow on antibiotic medium even after resuscitation, showed a permanent loss of chloramphenicol (Cm) resistance but retained resistance to kanamycin (Km) and streptomycin (Sm). Restriction enzyme digests show that a 2.5 to 3.0 Kb region from map location 12.5 to 15.5 Kb was deleted. This coincides with the 2.5 Kb reduction in plasmid size observed in 3 isolates that had lost antibiotic resistance after starvation for 49 days.
    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 73 (1993), S. 7960-7962 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Crack-free transparent ferroelectric Pb0.865La0.09Zr0.65Ti0.35O3 [PLZT (9/65/35)] thin films have been deposited on silicon substrates using the sol-gel deposition technique. An intermediate layer of Pb0.90La0.10Ti0.975O3 (PLT) was used to improve the PLZT's optical quality and to reduce the amount of film cracking. Wet chemical etching, plasma etching, and reactive ion etching were investigated as means of realizing the necessary waveguide structures. Waveguiding was observed in 2–4 mm long by 20 μm wide PLZT (9/65/35) ridge waveguides fabricated by reactive ion beam etching.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 2670-2672 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep level transient spectroscopy (DLTS) has been used to investigate trap levels in sol-gel derived polycrystalline Pb(Zr0.54,Ti0.46)O3 thin films. Metal-ferroelectric-metal capacitor structures 2400 and 3000 A(ring) in thickness were fabricated and characterized using a constant voltage DLTS system. Prominent peaks associated with a single trap level were observed in all samples studied. The activation energy was determined to be 267 meV from DLTS spectra Arrhenius plots. Infrared transmission characterization was performed on PbTiO3 thin films also prepared using sol-gel synthesis. A loss in the transmission at 270±12 meV was observed which we attribute to hole emission from the same trap detected using DLTS.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 25 (1992), S. 797-799 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The Debye–Waller factor of molybdenum has been determined by the powder neutron diffraction technique with a double-axis neutron diffractometer. The B value after correction for thermal diffuse scattering (TDS) was 0.25 (1) Å2, which corresponds to a Debye temperature Θ of 385 (7) K. These values are in good agreement with the values determined by others using X-ray diffraction and inelastic neutron scattering techniques.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 46 (1990), S. 435-437 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The temperature factor of silicon has been determined by the powder neutron diffraction technique employing a double-axis neutron diffractometer. A neutron wavelength of 1.184 Å was used in the experiment. The sample used was a fine powder of silicon of purity 99.999%. The correction to the observed intensities due to thermal diffuse scattering (TDS) was not applied as the neutron velocity of 3.34 km s-1 (corresponding to neutron wavelength of 1.184 Å) is less than the minimum velocity of sound in this crystal. The B value obtained from these experiments was found to be 0.45 (2) Å〈sup/〉, corresponding to a mean-square vibrational amplitude of 0.017 (2) Å2 and to a Debye temperature of 531 (11) K at the sample temperature of 284 K at which the experiment was performed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 40 (1992), S. 145-152 
    ISSN: 1741-0444
    Keywords: Brain glioma ; Classification ; Fuzzy rule extraction ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The current pre-operative assessment of the degree of malignancy in brain glioma is based on magnetic resonance imaging (MRI) findings and clinical data. 280 cases were studied, of which 111 were high-grade malignancies and 169 were low-grade, so that regular and interpretable patterns of the relationships between glioma MRI features and the degree of malignancy could be acquired. However, as uncertainties in the data and missing values existed, a fuzzy rule extraction algorithm based on a fuzzy min-max neural network (FMMNN) was used. The performance of a multi-layer perceptron network (MLP) trained with the error back-propagation algorithm (BP), the decision tree algorithm ID3, nearest neighbour and the original fuzzy min-max neural network were also evaluated. The results showed that two fuzzy decision rules on only six features achieved an accuracy of 84.6% (89.9% for low-grade and 76.6% for high-grade cases). Investigations with the proposed algorithm revealed that age, mass effect, oedema, post-contrast enhancement, blood supply, calcification, haemorrhage and the signal intensity of the T1-weighted image were important diagnostic factors.
    Type of Medium: Electronic Resource
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