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  • 1990-1994  (12)
  • 1870-1879
  • 1994  (12)
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 2310-2315 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hole drift mobilities have been measured using photocarrier time-of-flight for several hydrogenated amorphous silicon-carbon alloy specimens. We find that, as the band gap increases, the hole drift mobility remains essentially constant. The temperature and dispersion properties were broadly consistent with hole multiple trapping in the valence bandtail. In conjunction with previous drift mobility measurements in hydrogenated amorphous silicon-carbon alloys and hydrogenated amorphous silicon-germanium alloys, these hole measurements complete a simple pattern for the effects of band gap modification on drift mobilities: electron mobilities decline as the band gap is increased or decreased from 1.75 eV, but hole mobilities are relatively unaffected.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    International journal of dermatology 33 (1994), S. 0 
    ISSN: 1365-4632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background. Photography is integral to the practice of dermatology. Digital imaging techniques have only recently been used to assess cutaneous disorders. Previously reported imaging systems have been both expensive and cumbersome. Consequently, they have failed to gain widespread acceptance. Methods. We describe our experience using an inexpensive digital camera. Photographs taken with this portable digital camera (FotoMan) compare favorably to those obtained with conventional 35 mm cameras. Results. This inexpensive digital camera provides photographs of acceptable quality for a variety of dermatologic applications. Images created with this system are available within minutes and are less expensive than traditional photographs. Conclusions. Digital imaging is a new and exciting development. The digital camera described is simple to operate and provides a useful alternative or adjunct to conventional photography.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 6275-6289 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A temperature and pressure dependent study of coherent anti-Stokes Raman scattering (CARS) Q branch spectra of molecular nitrogen and oxygen has been conducted. Spectra at pressures up to 250 MPa and in the temperature range 298 K〈T〈850 K have been obtained using a scanning CARS apparatus. The full-width at half-maximum (FWHM) as well as peak position of collapsed Q branch profiles were measured. Measurements also have been made in synthetic air and in mixtures with argon. A detailed comparison of Q branch CARS band shapes with theoretical models of quantum mechanical and quasiclassical origin has been performed. On the one hand existing scaling laws like the modified energy gap (MEG), energy corrected sudden (exponential) polynomial energy gap [ECS-(E)P], polynomial energy gap (PEG), and statistical polynomial energy gap (SPEG) laws that give analytical expressions for rotational relaxation rates are used in a CARS code to calculate half-widths of the collapsed Q branch of nitrogen and oxygen. Many of these models show significant deviations from experimental results in the high pressure regime investigated here. For nitrogen the PEG-law, although not very suitable at lower densities, at room temperature reasonably reproduces the half-widths in the high pressure regime. The same is true for the ECS-EP law at low and high temperatures, whereas the SPEG-law only gives reasonable results at high temperature. For oxygen only the MEG and ECS-EP laws (at room temperature) give half-widths that are within the error limits of the measurement. On the other hand, within experimental error frequency shifts and half-widths of N2 and O2 CARS-spectra are well described by the classical approach throughout the density range. It is found that dephasing contributions to the density induced spectral shift cannot be neglected at room temperature but are less important at higher temperatures. In comparison to experimental data the quasiclassical model provides physical interpretation of temperature dependent cross sections for rotational energy relaxation processes in nitrogen and oxygen at high densities.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 32 (1994), S. 0 
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: This paper presents a conceptual model, developed by synthesizing the results of many researchers, which describes the geochemical evolution of domestic waste water in conventional on-site septic systems as the result of the interactions of a few major constituents. As described by the model, the evolution of waste water is driven by the microbially catalyzed redox reactions involving organic C and N in waste water and occurs in as many as three different redox zones. Anaerobic digestion of organic matter and production of CO2, CH4, and NH4+ predominate in the first zone, which consists mainly of the septic tank. In the second zone, gaseous diffusion through the unsaturated sediments of the drain field supplies O2 for aerobic oxidation of organic C and NH4+ and a consequent decrease in waste-water alkalinity. The NO3− formed by NH4+ oxidation in this zone is the primary adverse impact of septic systems at most sites and is generally an unavoidable consequence of the proper functioning of conventional septic systems. If adequate O2 is not available in the drain field, aerobic digestion is incomplete, and the accumulation of organic matter may cause septic-system failure. In the third redox zone, NO3 is reduced to N2 by the anaerobic process of denitrification. However, this setting is rarely found below septic systems due to a lack of labile organic C in the natural setting. Consideration of the changing redox and pH conditions in each zone aids our understanding of the fate of other constituents in septic systems.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Pediatric allergy and immunology 5 (1994), S. 0 
    ISSN: 1399-3038
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Pediatric allergy and immunology 5 (1994), S. 0 
    ISSN: 1399-3038
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 7
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    Unknown
    London : Periodicals Archive Online (PAO)
    British Journal of Criminology, Delinquency and Deviant Social Behaviour. 34:3 (1994:Summer) 383 
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 370 (1994), S. 615-620 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In a spontaneously bursting neuronal network in vitro, chaos can be demonstrated by the presence of unstable fixed-point behaviour. Chaos control techniques can increase the periodicity of such neuronal population bursting behaviour. Periodic pacing is also effective in entraining such systems, ...
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Child's nervous system 10 (1994), S. 524-528 
    ISSN: 1433-0350
    Keywords: Proximal shunt failure ; Distal shunt failure ; Time to shunt failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Proximal obstruction is reported to be the most common cause of ventriculoperitoneal (VP) shunt failure, suggesting that imperfect ventricular catheter placement and inadequate valve mechanisms are major causes. This study retrospectively examined patterns of shunt failure in 128 consecutive patients with symptoms of shunt malfunction over a 2-year period. Factors analyzed included site of failure, time from shunt placement or last revision to failure, age of patient at time of failure, infections, and primary etiology of the hydrocephalus. One hundred of these patients required revisions; 14 revisions were due to infections. In this series there was a higher incidence of distal (43%) than of proximal (35%) failure. The difference was not statistically significant when the overall series was considered; however, when factoring time to failure as a variable, marked differences were noted regardless of the underlying cause of hydrocephalus or the age of the patient. Of the 49 patients needing a shunt revision or replacement within 2 years of the previous operation, 50% had proximal malfunction, 14% distal, and 10% had malfunctions attributable directly to the valve itself. Also, 12 of the 14 infections occurred during this time interval. In sharp contrast, of the 51 patients having shunt failure from 2 to more than 12 years after the previous procedure, 72% had distal malfunction, 21% proximal, and only 6% had a faulty valve or infection. This difference between time to failure for proximal versus distal failures was statistically significant (P〈0.00001 for both Student's t-test and non-parametric Mann-Whitney U-test). It is concluded that these data are valuable for interpreting outcome studies of novel valve systems and ventricular catheter placement techniques, by defining a time frame during which these modifications can be reliably evaluated.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurocytology 23 (1994), S. 699-707 
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Implantation of hybridoma cells that secrete a monoclonal antigalactocerebroside into the dorsal columns of ⩽ 9-day-old rat spinal cord results in failure of development of dorsal column myelin in the vicinity of the implant. Clusters of apparently undamaged amyelinated axons remain among the hybridoma cells. Ventral myelin is unaffected. These in vivo results support antibody-mediated inhibition of myelin formation as a potential mechanism underlying failure of remyelination in multiple sclerosis.
    Type of Medium: Electronic Resource
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