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  • Articles: DFG German National Licenses  (6)
  • 1990-1994  (6)
  • 1965-1969
  • 1991  (6)
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  • Articles: DFG German National Licenses  (6)
Material
Years
  • 1990-1994  (6)
  • 1965-1969
Year
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 1469-1474 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-temperature photoconductive mixing measurements have been performed on n- and p-type compensated Si at a microwave beat frequency of 253 MHz. The dependence of the transport parameters (electron-hole recombination lifetime and drift velocity) on temperature and electric field obtained from this experimental technique, are discussed. At high temperatures (T≥35 K for n-type and T≥60 K for p-type), the drift velocity is determined by neutral impurity and ionized impurity, and charge carrier-phonon scattering. In the carrier freeze-out regime (T≤35 K for n-type, T≤60 K for p-type) hopping charge transport is the dominant mechanism determining the drift velocity.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 25 (1991), S. 0 
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY 1. Secondary production of chironomids (Diptera: Chironomidae) in a third-order northern Indiana stream was estimated using species-specific, and in most cases cohort-specific, life-history data from the field.2. Chironomid life-history patterns were diverse, ranging from one to four generations per year in addition to asynchronous development. Cohort production intervals (CPI) for all taxa ranged from 56 to 266 days. CPI for cohorts of conspecifics differed up to 3-fold.3. Annual secondary production was estimated using the instantaneous growth method or the size—frequency method depending on whether cohorts were distinguishable or not. Total annual chironomid production was 29 700 mg dry mass m−2, which is the highest value reported for chironomids from a north temperate stream.4. Eighty per cent of the total chironomid production was attributed to five species: Diamesa nivoriunda (33.9%), Cricotopus bicinctus (16.6%), Pagastia sp. (10.2%), C. trifascia (9.7%) and Orthodadius obumbratus (9.6%).5. The annual P:B ratio ranged from 4.7 to 21.9. Thus, high secondary production was due to high mean annual standing stocks and not to rapid biomass turnover.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Environmental management 15 (1991), S. 731-747 
    ISSN: 1432-1009
    Keywords: Polystyrene foam ; Paper ; Packaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract An analysis of the overall relative merits of the use of uncoated paper vs molded polystyrene bead foam in single-use 8-oz cups is described here as a manageable example of the use of paper vs plastics in packaging. In raw material requirements the paper cup required about 2.5 times its finished weight of raw wood and about the same hydrocarbon fueling requirement as is needed for the polystyrene foam cup. To process the raw materials about six times as much steam, 13 times as much electric power, and twice as much cooling water are consumed to produce the paper cup as compared to the polystyrene foam cup. Emission rates to air are similar and to water are generally higher for the paper cup. Virtually all primary use factors favor polystyrene foam over paper. Once used both cup types may be recycled. Landfill disposal of the two items under dry conditions will occupy similar landfill volumes after compaction and will confer similarly slow to nonexistent decomposition to either option. Under wet conditions polystyrene foam will not readily degrade, but may help other materials to do so. Paper under wet conditions will biodegrade to produce methane, a significant greenhouse gas, biochemical oxygen demand to any leachate, and instability to the land surface during the process. Both materials can be incinerated cleanly in a municipal waste stream with the option of energy recovery, to yield an ash volume of 2%–5% of the incoming waste volume. Overall this analysis would suggest that polystyrene foam, with an extension to plastics in general, should be given more evenhanded consideration relative to paper in packaging applications than is currently the case.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Scientometrics 20 (1991), S. 333-357 
    ISSN: 1588-2861
    Source: Springer Online Journal Archives 1860-2000
    Topics: Information Science and Librarianship , Nature of Science, Research, Systems of Higher Education, Museum Science
    Notes: Abstract In 1987, an analysis of the CHI/NSFScience Literature Indicators Data-Base by the author and his colleagues suggested that the UK's percentage share of the world publication and citation totals had continued to fall over 1981–84, although at a slower rate than previously. That finding has recently been challenged byBraun, Glänzel andSchubert who, by combining 28 publication-based indicators, concluded that there was no statistically significant evidence for such a decline. This paper examines the reasons for the discrepancy. It is argued that the methodology ofBraun et al. is seriously flawed, as well as being inconsistent with work that they have published elsewhere. By adopting a more consistent and realistic set of indicators and applying them to the data ofBraun et al., one arrives at results entirely consistent with those derived from the CHI/NSF data-base.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Scientometrics 22 (1991), S. 369-377 
    ISSN: 1588-2861
    Source: Springer Online Journal Archives 1860-2000
    Topics: Information Science and Librarianship , Nature of Science, Research, Systems of Higher Education, Museum Science
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 29 (1991), S. 63-69 
    ISSN: 1741-0444
    Keywords: Eye tracking movement ; Hinkley test ; Innovations ; Kalman filter ; Saccades ; Time series
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A simple but efficient algorithm has been developed for computer analysis of eye tracking movements. The program separates smooth pursuit and saccadic eye movements. Separation of the two components is achieved using a twostep process of saccade detection. First, an AR model of the velocity of the smooth component is identified and used to determine a Kalman filter. Secondly the innovation sequence generated by this filter allows saccade detection. The precise beginning and end of each saccade are found using a Hinkley algorithm. Examples are given of analysis procedure for eye tracking of a random moving target. The method proved to be highly reliable and could be easily extended to other eye movements such as nystagmus.
    Type of Medium: Electronic Resource
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