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  • Articles  (77)
  • Springer  (62)
  • Wiley-Blackwell  (12)
  • Geological Society of America
  • 2000-2004  (24)
  • 1975-1979  (27)
  • 1965-1969  (10)
  • 1905-1909  (16)
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  • Articles  (77)
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  • 1
    ISSN: 1432-1939
    Keywords: Seed dispersal Seed shadow Hornbills Telemetry Tropical frugivory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. We studied two species of Ceratogymna hornbills, the black-casqued hornbill, C. atrata, and the white-thighed hornbill, C. cylindricus, in the tropical forests of Cameroon, to understand their movement patterns and evaluate their effectiveness as seed dispersers. To estimate hornbill contribution to a particular tree species' seed shadow we combined data from movements, determined by radio-tracking, with data from seed passage trials. For 13 individuals tracked over 12 months, home range varied between 925 and 4,472 ha, a much larger area than reported for other African avian frugivores. Seed passage times ranged from 51 to 765 min, with C. atrata showing longer passage times than C. cylindricus, and larger seeds having longer gut retention times than smaller seeds. Combining these data, we estimated that seed shadows were extensive for the eight tree species examined, with approximately 80% of seeds moved more than 500 m from the parent plant. Maximum estimated dispersal distances for larger seeds were 6,919 and 3,558 m for C. atrata and C. cylindricus, respectively. The extent of hornbill seed shadows suggests that their influence in determining forest structure will likely increase as other larger mammalian dispersers are exterminated.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Meteorology and atmospheric physics 26 (1977), S. 39-50 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Description / Table of Contents: Zusammenfassung Im Dezember 1975 wurden durch eine Fesselballonsonde die vertikalen Temperatur- und Windprofile im Gore River Valley im westlichen Colorado ermittelt. Aus Beobachtungen an einem wolkenlosen Morgen bei einer anfangs starken Inversion im Tal zeigte sich, daß die Inversionsobergrenze stetig um 120 m Std−1. absank und nach ungefähr vier Stunden den Talgrund erreichte. Schwache Talabwinde wehten innerhalb der Inversionsschicht. während stärkere Talaufwinde oberhalb derselben herrschten. Eine Hypothese wird vorgeschlagen, um diese Beobachtungen zu erklären. Die Abkühlung am späten Nachmittag und am Abend, wobei die Bildung einer Inversion einsetzte, deren Schichtdicke in weniger als zwei Stunden 175 m betrug, ist Gegenstand einer gesonderten Untersuchung. Winde innerhalb der Inversionsschicht wurden nicht mehr von den Winden in der freien Atmosphäre beeinflußt und blieben im Laufe der Nacht sehr schwach. Bewölkung während der Erwärmungsperiode an einem Morgen hatte zur Folge, daß das Temperaturprofil sich Isothermie näherte, indem Erwärmung gleichmäßig im ganzen Luftraum des Tales sich fortsetzte.
    Notes: Summary A tethered balloon sounder was used to collect vertical temperature and wind structure data in the Gore River Valley of Western Colorado during December, 1975. Observations taken on a clear morning in which a deep inversion was initially present in the valley showed that the inversion top descended at a steady rate of ∼120 m hr−1. reaching the valley bottom after approximately 4 hours. Weak down-valley winds were present within the inversion layer while stronger up-valley winds prevailed above. A hypothesis is presented to account for these observations. A case study is presented for afternoon and evening cooling in which a ground-based inversion developed to a depth of 175 m in less than 2 hours. Winds within the inversion became decoupled from the synoptic-scale winds and remained very weak during the night. The effect of cloud cover during a morning heating cycle was to make the temperature soundings approach isothermal while sensible heating continued throughout the valley volume.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of intelligent and robotic systems 29 (2000), S. 349-387 
    ISSN: 1573-0409
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Current learning approaches to computer vision have mainly focussed on low-level image processing and object recognition, while tending to ignore high-level processing such as understanding. Here we propose an approach to object recognition that facilitates the transition from recognition to understanding. The proposed approach embraces the synergistic spirit of soft computing, exploiting the global search powers of genetic programming to determine fuzzy probabilistic models. It begins by segmenting the images into regions using standard image processing approaches, which are subsequently classified using a discovered fuzzy Cartesian granule feature classifier. Understanding is made possible through the transparent and succinct nature of the discovered models. The recognition of roads in images is taken as an illustrative problem in the vision domain. The discovered fuzzy models while providing high levels of accuracy (97%), also provide understanding of the problem domain through the transparency of the learnt models. The learning step in the proposed approach is compared with other techniques such as decision trees, naïve Bayes and neural networks using a variety of performance criteria such as accuracy, understandability and efficiency.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 54 (2000), S. 681-685 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract New methods of determining the structural groups —COOH and —CH2— have been developed. The investigation of carboxyl groups is possible both after derivatization with p-fluorophenacylbromide and by quantitative interpretation of the Fourier transform infrared (FT IR) spectra. There exists a linear relationship between the results of these two methods that is generally valid for the analysis of all brown coal components. The maximum extinction coefficient of the symmetric stretching vibration band of the CH2 groups has been determined using model substances. This allows quantification of this structural group directly from the FT IR spectrum. The results agree with the contents of methylene groups as determined by 13C-cross polarization–magic angle spinning–nuclear magnetic resonance (13C CPMAS NMR) spectroscopy. Using these methods, the COOH and CH2 groups contained in brown coals of the North Rhine region and in their bioconversion products have been quantified.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Physics in perspective 2 (2000), S. 313-326 
    ISSN: 1422-6960
    Keywords: Key words. History of science; Ireland; Rosse Telescope; St. Patrick's College; Birr Demense; Irish National Museum (Galway); Giant's Causeway.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Newly-prosperous Ireland has a number of sites which the scientific traveller can visit. There are apparatus museums at Birr and Maynooth, and a collection of early apparatus at the physics department of the Irish National University in Galway. The main attraction at Birr is the Rosse Telescope, with its 6-ft diameter speculum, built in the 1840s, and recently refurbished. Travellers to Northern Ireland can see applied geology at the Giant's Causeway.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Environmental management 1 (1977), S. 343-348 
    ISSN: 1432-1009
    Keywords: Flood-plain vegetation ; Land use ; Channelization ; Bank-stabilization ; Flood-plain forest succession
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Changes in vegetation and land use since 1826 were evaluated along the 800 kilometer portion of the Missouri River flood-plain that extends across the State of Missouri using County Land Office Survey records for 1826 and aerial photos for 1937, 1958, and 1972. The combined results show a decline in flood-plain forest coverage from 76% in 1826 to 13% in 1972; cultivated land increased from 18% to 83% during the same time. Uncultivated-unforested areas increased from 6% in 1826 to 27% in 1937, then declined to 1% in 1972; these changes occurred coincident with extensive bank-stabilization and channelization activities initiated in 1912 by the U.S. Army Corps of Engineers. Riverbank stabilization activity since that time may account for the increased rate of decline in flood-plain forests from 0.25% per year between 1826 and 1937 to 1.6% per year between 1937 and 1972. The overall species composition of the 1826 flood-plain forests was found to be most similar to mature forest stands evaluated in 1972; similar frequencies in 1826 and 1972 occurred for hackberry (Celtis occidentalis; 80% in 1826, 83% in 1972), elm (Ulmus spp.; 80% and 83%), and sycamore (Platanus occidentalis; 57% and 50%). Pawpaw (Asimina triloba), found only in mature flood-plain forests in 1972, was recorded along 54% of the 1826 section lines. These combined data indicate (1) that pre-settlement flood-plain forests were extensive and included frequent, mature stands, (2) that in certain areas substantial portions of the flood-plain were in cultivation prior to extensive riverbank stabilization and channelization, and (3) that increased flood-plain forest clearing occurred coincident with increased bank-stabilization activities.
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  • 7
    ISSN: 1573-4927
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Carbonic anhydrase IdMichigan, an electrophoretic variant of human red cell carbonic anhydrase I, was purified from erythrocytes obtained from an individual heterozygous for the trait. Primary structural analysis indicates that a lysine residue has exchanged for a threonine residue in the variant enzyme. After isolation, there was approximately 1.8 times as much normal as variant enzyme. Thermostability studies demonstrated that carbonic anhydrase Id was more thermolabile than the normal enzyme. The normal and variant enzymes showed no differences in specific carboxylesterase activity or CO2 hydratase activity. Utilizing the carboxylesterase activity toward β-naphthyl acetate, the normal and variant enzymes had similar Michaelis constants, pH profiles, and rates of inhibition by acetazolamide. Immunochemical studies did not demonstrate an antigenic difference for the variant enzyme.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Biochemical genetics 3 (1969), S. 25-35 
    ISSN: 1573-4927
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The phosphoglucomutase (PGM) electrophoretic phenotype of the mouse (Mus musculus) consists of several distinct components which can be grouped into two major zones designated PGM-1 and PGM-2. Evidence presented here indicates that each zone is controlled by a single genetic locus denoted Pgm-1 and Pgm-2, respectively. Two variant forms segregated at the Pgm-1 locus. They were codominantly expressed and inherited as alleles at an autosomal locus. The alleles were termed Pgm-1 a (fast) and Pgm-1 b (slow). These alleles were separately fixed in a number of inbred strains of mice. Preliminary evidence based on wild mouse phenotypes indicates that variant forms also exist for PGM-2 which are inherited as alleles at an autosomal locus. Genetic linkage relationships have not been determined for these loci. PGM-1 variants and PGM-2 were expressed in mouse fibroblasts in vitro.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 156 (1975), S. 475-482 
    ISSN: 1432-0878
    Keywords: Annulate lamellae ; Spermatocytes ; Grasshoppers ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intranuclear and cytoplasmic annulate lamellae were studied in grasshopper spermatocytes (Melanoplus) with the electron microscope. Although cytoplasmic annulate lamellae were observed in all three species examined, intranuclear annulate lamellae were found in only one species. The intranuclear annulate lamellae encompass certain nuclear material adjacent to the nuclear envelope forming a vesicle that is extruded into the spermatocyte cytoplasm. In this same species, cytoplasmic annulate lamellae are seen contiguous with granular masses of varying size. These structures were noted as being morphologically indistinguishable from the “yolk nuclei” of dragonfly oocytes (Kessel and Beams, 1969; Kessel, 1973).
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  • 10
    ISSN: 1573-4927
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Erythrocyte and tissue lactate dehydrogenase (LDH) electrophoretic patterns of 26 rodent species from ten families were examined. The LDH B gene was observed to range in erythrocyte expression from species without detectable B subunits to those which predominantly expressed B subunits. However, the shift in erythrocyte B gene expression was not observed in the tissue LDH electrophoretic patterns between rodent species. Species which did not express erythrocyte B subunits, or only small quantities of B subunits, were restricted to the suborder Myomorpha. In erythrocytes of other rodent species, and most mammals, LDH B subunits are expressed equally or in excess of A subunits. The results suggest either structural differences in the LDH B gene between Myomorph and non-Myomorph rodents or a regulator gene which controls the expression of the B gene in Myomorph erythrocytes. Existing evidence favors the latter hypothesis.
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