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  • 1
    Electronic Resource
    Electronic Resource
    Helium resonance lines in the flare of 15 June, 1973 (1989)
    Springer
    Solar physics 120 (1989), S. 309-341 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Time sequences of He i and He ii resonance line intensities at several sites within the flare of 15 June, 1973 are derived from observations obtained with the Naval Research Laboratory's Slitless Spectroheliograph on Skylab. The data are compared with predictions in six model flare atmospheres based on two values for the heating rate and three for the flux of photoionizing coronal X-rays and EUV. A peak ionizing flux more than 103 times that in the quiet Sun is indicated. For most conditions in flare kernels the He ii Lα and Lβ lines are found to be formed by collisional excitation, thereby contributing to the local cooling of the plasma at temperatures above 6 × 104 K. Emission in the higher Lyman lines is generally the result of a mixture of collisional excitation at these temperatures and photoionization and recombination at temperatures near 2.5 × 104 K. We discuss implications for the common practice of deriving stellar coronal fluxes from He ii 1640 Å fluxes assuming dominance of the recombination mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00159882
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  • 2
    Electronic Resource
    Electronic Resource
    Supporting Start-to-Finish Development of Knowledge Bases (1989)
    Springer
    Machine learning 4 (1989), S. 259-283 
    Details
    ISSN: 0885-6125
    Keywords: knowledge-acquisition tools ; knowledge-base refinement ; knowledge-base development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Developing knowledge bases using knowledge-acquisition tools is difficult because each stage of development requires performing a distinct knowledge-acquisition task. This paper describes these different tasks and surveys current tools that perform them. It also addresses two issues confronting tools for start-to-finish development of knowledge bases. The first issue is how to support multiple stages of development. This paper describes Protos, a knowledge-acquisition tool that adjusts the training it expects and assistance it provides as its knowledge grows. The second issue is how to integrate new information into a large knowledge base. This issue is addressed in the description of a second tool, KI, that evaluates new information to determine its consequences for existing knowledge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022650621889
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  • 3
    Electronic Resource
    Electronic Resource
    Acute toxicity of industrial surfactants toMysidopsis bahia (1989)
    Springer
    Archives of environmental contamination and toxicology 18 (1989), S. 765-772 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Three-to eight-day oldMysidopsis bahia were used to evaluate the acute toxicities of 17 industrial surfactants having a wide range of physiochemical characteristics. LC50s based on nominal concentrations covered approximately three orders of magnitude (〈1 to 〉4,000 mg/L). The base structure of the surfactants (i.e., aromatic or aliphatic, branched or linear) was not a factor controlling toxicity. Low solubility surfactants with low ethylene oxide (EO) molar ratios were the most toxic surfactants tested. Ethylene oxide chain length was the best predictor of toxicity, and would be a good parameter to use to “screen” for surfactant toxicity in hazard assessment. Substitution of terminal OH with SO3 or PO4 reduced toxicity of a selected group of surfactants. Sensitivity ofM. bahia up to 26 days old was not significantly different from that of 3-to 8-day old animals. Use of one surfactant as a reference toxicant demonstrated that sensitivity ofM. bahia was consistent throughout the various tests.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01225014
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  • 4
    Electronic Resource
    Electronic Resource
    Remanent fields and critical currents in Tl2 Ba2Ca2Cu3Ox ceramic (1989)
    Springer
    Applied physics 49 (1989), S. 325-329 
    Details
    ISSN: 1432-0630
    Keywords: 74.60 ; 74.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The temperature and magnetic-field dependences of the remanent magnetization have been determined from far-field measurements for thallium ceramic samples. The current flow that gives rise to the observed magnetization is intragranular. The results are consistent with flux-creep-controlled transport with a distance between pinning centers of ∼- 1/2/μm. Using near-field measurements, the superconducting properties are found to be heterogeneous on a scale of ≫ 1 mm. Magnetic domains have been induced by pplying spatial variation in the applied field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616862
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  • 5
    Electronic Resource
    Electronic Resource
    Supporting start-to-finish development of knowledge bases (1989)
    Springer
    Machine learning 4 (1989), S. 259-283 
    Details
    ISSN: 0885-6125
    Keywords: knowledge-acquisition tools ; knowledge-base refinement ; knowledge-base development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Developing knowledge bases using knowledge-acquisition tools is difficult because each stage of development requires performing a distinct knowledge-acquisition task. This paper describes these different tasks and surveys current tools that perform them. It also addresses two issues confronting tools for start-to-finish development of knowledge bases. The first issue is how to support multiple stages of development. This paper describes Protos, a knowledge-acquisition tool that adjusts the training it expects and assistance it provides as its knowledge grows. The second issue is how to integrate new information into a large knowledge base. This issue is addressed in the description of a second tool, KI, that evaluates new information to determine its consequences for existing knowledge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00130714
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  • 6
    Electronic Resource
    Electronic Resource
    Occurrence of bacterivory in Cryptomonas, a common freshwater phytoplankter (1989)
    Springer
    Oecologia 78 (1989), S. 473-476 
    Details
    ISSN: 1432-1939
    Keywords: Plankton ; Bacterivory ; Mixotrophy ; Phagotrophy ; Cryptomonas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Bacterivory was detected by incorporation of 0.57 μm diameter, fluorescent polystyrene beads and fluorescently labeled bacteria (FLB) in two cultured species of Cryptomonas (C. ovata and C. erosa), and a population of Cryptomonas sp in a humic, mesotrophic lake. Rates of ingestion and clearance were very low, and similar for the cultures and the in situ population. The in situ population incorporated 0.7–1.7 bacteria cell-1 h-1, thereby ingesting 0.3%–2.0% of the total bacterial numbers present in the water per day, and receiving less than 2% of its carbon content per day through bacterivory. Thus, bacterivory by Cryptomonas was quantitatively important neither as a sink for bacterial biomass, nor as a carbon source for the algal cells. Possibly, it served in the uptake of essential nutrients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378736
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  • 7
    Electronic Resource
    Electronic Resource
    Resource partitioning by reef corals as determined from stable isotope composition (1989)
    Springer
    Marine biology 100 (1989), S. 185-193 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pattern of resource partitioning vs depth by corals collected in February 1983 from Jamaica and the Red Sea was determined from their stable carbon isotope composition. Observations were made on isolated zooxanthellae and corresponding algae-free animal tissue from eight species at four depths over a 50 m bathymetric range. Zooxanthellae δ13C was high in shallow water and became lower as depth increased. This trend correlated significantly with the anual integrated photosynthetic rate. The trend is interpreted according to a “depletion-diffusion” hypothesis; in shallow water, at high rates of photosynthesis, metabolic CO2 is nearly depleted and the supply of CO2 from seawater bicarbonate is limited by diffusion. Since most of the available CO2 is fixed, isotope fractionation is minimal. In deeper water, at lower rates of photosynthesis, metabolic CO2 is ample, and isotope fractionation is greater. Animal tissue δ13C was slightly lower than corresponding zooxanthellae values in shallow water. As depth increased the difference between zooxanthellae and animal tissue δ13C increased and the latter approached the δ13C of oceanic particulate organic carbon. These data suggest that carbon is translocated at all depths and that deep-water corals draw significantly on allocthonous sources of carbon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391957
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  • 8
    Electronic Resource
    Electronic Resource
    Microscopic examination and fatty acid characterization of filamentous bacteria colonizing substrata around subtidal hydrothermal vents (1989)
    Springer
    Archives of microbiology 152 (1989), S. 64-71 
    Details
    ISSN: 1432-072X
    Keywords: Thiothrix sp. ; Beggiatoa sp. ; Sulfideoxidizing ; Polyunsaturated ; Fatty acids ; Inclusions ; Sheath ; Southern California ; Ultrastructure ; Sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microscopic examination of the whitish mat that covered the substrata around subtidal hydrothermal vents at White Point in southern California revealed a “Thiothrix-like” bacterium containing sulfur inclusions as the dominant filamentous form in this microbial community. The matlike appearance developed as a result of the closely-packed manner inwhich the basal ends of the filaments were anchored to the substrate. The dominant phospholipid fatty acids of these filaments (16:0, 16:1w7c, 18:0, 18:1w7c) were similar to those recovered from a sample of Beggiatoa isolated from a spring in Florida. Filaments from both sources contained small quantities of C18 and C20 polyunsaturated fatty acids, as well. A larger but less abundant sheathless, filamentous form, which also contained sulfur inclusions and displayed a cell wall structure similar to a previously described Thioploca strain, also colonized the substrata around the subtidal mat. The preservation methods used in the preparation of thin-sections of the subtidal mat material were found to be inadequate for defining some key cellular structures of the large filaments. Nevertheless, the results demonstrate that the filamentous bacteria comprising the microbial mat in the vicinity of the subtidal vents exhibit some of the features of the free-living filamentous microorganisms found in deep-water hydrothermal areas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00447013
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  • 9
    Electronic Resource
    Electronic Resource
    A buckled plate test to measure interfacial toughness in composites (1989)
    Springer
    Journal of materials science 24 (1989), S. 4138-4143 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A new, buckled plate (BP) test has been used to measure transverse toughness as the parameter characterizing interfacial adhesion in unidirectional, continuous-fibre composites. The test is simple, with advantages over other interfacial methods. The theory and experimental details are presented. The results of BP tests are discussed for polycarbonate/carbon fibre composites. Evaluations have been made with regard to specimen dimensions, testing speed, crack length, modulus, fibre volume fraction, and processing conditions. Transverse toughness is a sensitive measure of the interfacial adhesion, giving results similar to transverse tensile strength. The test has also been used to measure longitudinal toughness. This test should be widely applicable to many composite systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01168986
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  • 10
    Electronic Resource
    Electronic Resource
    Chromosomal location of genes controlling heat shock proteins in hexaploid wheat (1989)
    Springer
    Theoretical and applied genetics 78 (1989), S. 873-878 
    Details
    ISSN: 1432-2242
    Keywords: Heat shock proteins ; 2D electrophoresis ; Triticum aestivum ; Gene location ; Gene regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The low molecular weight heat shock protein (HSP) profiles of the hexaploid wheat cultivar “Chinese Spring” and its ditelosomic series were characterized by isoelectric focusing polyacrylamide gel electrophoresis of denatured in vivo radiolabeled proteins. Comparisons of the ditelosomics (DTs) to the euploid “Chinese Spring” enabled the assignment of genes controlling 9 of the 13 targeted HSPs to seven chromosome arms. There did not appear to be a genome-specific action in the regulation of expression of these HSPs. There did appear to be a higher frequency of controlling genes within homoeologous DT lines 3, 4 and 7. Significant variation in protein quantity was evident among the DT lines for some HSPs, while other HSPs were remarkably stable in their expression across all DTs examined. The results are useful in identifying specific DT lines for the investigation of HSP functions in hexaploid wheat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00266674
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