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  • Springer  (41)
  • 2020-2022
  • 2000-2004  (41)
  • 1985-1989
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  • 2000  (41)
  • 1
    Electronic Resource
    Electronic Resource
    Film Model Approximation for Multicomponent Adsorption (2000)
    Springer
    Adsorption 6 (2000), S. 5-13 
    Details
    ISSN: 1572-8757
    Keywords: multicomponent adsorption ; diffusion ; Maxwell-Stefan model ; linear driving force approximation ; Langmuir isotherm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An approximate rate equation based on a film-model representation of diffusional mass transfer is developed to describe the kinetics of multicomponent adsorption. The model describes mass transfer as a pseudo-steady state diffusion process through a flat film of thickness equal to one fifth of the particle radius. Starting with an irreversible thermodynamics description of multicomponent diffusion, the flux relationships are integrated across the film yielding analytical expressions for the rate of mass transfer in a multicomponent adsorption system, when adsorption equilibria are described by the extended Langmuir isotherm. The new approximate rate equation can be conveniently used in the numerical simulation of adsorption systems with concentration-dependent micropore or surface diffusivity, and describes the effects of diffusional flux coupling. Results of accuracy comparable with that obtained when using the classical linear-driving-force approximation for systems with constant diffusivities are obtained with this new rate equation for both batch and fixed-bed adsorption calculations. A generalization of the approach based on the Gibbs adsorption isotherm describes mass transfer rates in terms of the spreading-pressure gradient and provides an extension to other multicomponent isotherm forms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008927713530
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  • 2
    Electronic Resource
    Electronic Resource
    Selecting Decomposable Models for Word-Sense Disambiguation: TheGrling-Sdm System (2000)
    Springer
    Computers and the humanities 34 (2000), S. 159-164 
    Details
    ISSN: 1572-8412
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Media Resources and Communication Sciences, Journalism
    Notes: Abstract This paper describes the grling-sdm system, which is asupervised probabilistic classifier that participated in the 1998SENSEVAL competition for word-sense disambiguation. This systemuses model search to select decomposable probability models describingthe dependencies among the feature variables.These types of models have been found to be advantageous in terms ofefficiency and representational power. Performance on the SENSEVALevaluation data is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002439708427
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  • 3
    Electronic Resource
    Electronic Resource
    The `Qualitative' Versus `Quantitative' Research Debate: A Question of Metaphorical Assumptions? (2000)
    Springer
    International journal of value-based management 13 (2000), S. 189-197 
    Details
    ISSN: 1572-8528
    Keywords: research ; methodology ; objectivism ; subjectivism ; dualism ; social world ; metaphor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract A great deal of criticism has been aimed at empirical-analytic research because of its narrow focus. However, a similar criticism can be leveled at qualitative research. The purpose of this manuscript is not to champion one approach at the expense of the other, but rather to focus on discussing the assumptions of each methodological approach in terms of metaphorical thinking.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007850027589
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  • 4
    Electronic Resource
    Electronic Resource
    Evolutionarily conserved and divergent expression of members of the FGF receptor family among vertebrate embryos, as revealed by FGFR expression patterns in Xenopus (2000)
    Springer
    Development genes and evolution 210 (2000), S. 345-357 
    Details
    ISSN: 1432-041X
    Keywords: Key words Xenopus fibroblast growth factor receptor ; Xenopus fibroblast growth factor receptor-4 ; Induction ; Neural crest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Fibroblast growth factors (FGFs) mediate many cell-cell signaling events during early development. While the actions of FGFs have been well-studied, the roles played by specific members of the FGF receptor (FGFR) family are poorly understood. To characterize the roles played by individual FGFRs we compared the regulation and expression of the three Xenopus FGFRs described to date (XFGFR-1, XFGFR-2, and XFGFR-4). First, we describe the expression of Xenopus FGFR-4; XFGFR-4 is present as a maternal mRNA and is found in the embryo through at least the tadpole stage. XFGFR-4 and XFGFR-1 mRNAs are present at comparable levels, arguing that both mediate FGF signaling during early development. Second, the expression of XFGFR-4 in animal caps differs from the expression of XFGFR-1 and XFGFR-2, suggesting that the FGFRs are independently regulated in ectoderm. Third, using whole-mount in situ hybridization, we show that XFGFR-1, XFGFR-2, and XFGFR-4 are expressed in dramatically different patterns, arguing that specific FGF signaling events are mediated by different members of the FGFR family. Among these, FGF signaling during the induction of neural crest cells is likely to be mediated by XFGFR-4. Comparison of our results with previously reported FGFR expression patterns reveals that FGFR-1 expression is highly conserved among vertebrate embryos, and FGFR-2 expression shows many features that are conserved and some that are divergent. In contrast, the expression pattern of FGFR-4 is highly divergent among vertebrate embryos.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270000076
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  • 5
    Electronic Resource
    Electronic Resource
    The cost of mutualism in a fly-fungus interaction (2000)
    Springer
    Oecologia 124 (2000), S. 85-90 
    Details
    ISSN: 1432-1939
    Keywords: Key words  Botanophila ; Epichloë ; Mutualism ; Mycophagy ; Pollinating parasites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Botanophila flies act as ”pollinating” parasites of the ascomycetous fungus, Epichloë elymi. Flies transfer fungal spermatia (gametes) among fungi as they visit their hosts for oviposition. Fly larvae consume the products of cross-fertilization (ascospores). We tested whether the cost to the fungus of engaging in the obligate mutualism rises as fly visitation increases and whether mechanisms operate to prevent excessive exploitation of the fungus. Fungi and flies were monitored over 3 years. We recorded the reproductive output of fungi, the amount of feeding by fly larvae on host reproductive tissues, and the mortality of fly eggs and larvae. In two of three years, fly eggs were randomly dispersed; eggs were clumped in the remaining year. The reproductive output of fungi did not decrease with increasing egg load; rather, fungal reproductive output tended to increase as more eggs were laid on fungi. Larval feeding was only weakly associated with the number of eggs on fungi. The lack of over-exploitation of the fungus by the fly shows that the interaction was stable during the period of time we conducted our study. Our data suggest the stability was primarily due to high fly egg/larval mortal-ity that increased as egg load increased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050027
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  • 6
    Electronic Resource
    Electronic Resource
    Characterisation of pea cytosolic glutathione reductase expressed in transgenic tobacco (2000)
    Springer
    Planta 211 (2000), S. 537-545 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Glutathione reductase – Enzyme characterisation (leaf GR) –Nicotiana (glutathione reductase) –Pisum (GOR2 cDNA) – Transgenic tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract.  Expression in transgenic tobacco (Nicotiana tabacum L.) of a pea (Pisum sativum L.) GOR2 cDNA, encoding an isoform of glutathione reductase (GOR2), resulted in a 3- to 7-fold elevation of total foliar glutathione reductase (GR) activity. The enzyme encoded by GOR2 was confirmed to be extraplastidial in organelle fractionation studies and was considered most likely to be localised in the cytosol. A partial purification of GOR2 was achieved but a standard affinity chromatography step, using adenosine-2′,5′-diphosphate-Sepharose and often employed in the purification of GR from diverse sources, was unsuccessful with this isoform. Preparative isoelectric focussing was employed as part of the purification procedure of GOR2 and a complete separation from plastidial/mitochondrial glutathione reductase (GOR1) was achieved. The isoform GOR2 was shown to have a slower migration on non-denaturing polyacrylamide gels compared with GOR1 and properties typical of GR enzymes from plant sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250000304
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  • 7
    Electronic Resource
    Electronic Resource
    Lattice Cones in Euclidean Space (2000)
    Springer
    Semigroup forum 60 (2000), S. 159-171 
    Details
    ISSN: 1432-2137
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002339910011
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  • 8
    Electronic Resource
    Electronic Resource
    XAS of carbon supported platinum fuel cell electrocatalysts: advances towards real time investigations (2000)
    Springer
    Topics in catalysis 10 (2000), S. 231-239 
    Details
    ISSN: 1572-9028
    Keywords: carbon supported platinum ; electrocatalysts ; EXAFS ; EDE ; dispersive ; fuel cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The utility of XAS to provide detailed information regarding thestructure of supported electrocatalysts has previously been demonstrated. Areview of the literature relating to carbon supported Pt fuel cellelectrocatalysts is presented. Improvements in the time resolution of the datacollection which have become possible with the introduction of energydispersive monochromators are discussed and a critical analysis of the effectof these improvements is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/B:TOCA.0000015159.32671.be
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  • 9
    Electronic Resource
    Electronic Resource
    Genetic and Environmental Variation in Acyl Glucose Ester Production and Glandular and Nonglandular Trichome Densities in Datura wrightii (2000)
    Springer
    Journal of chemical ecology 26 (2000), S. 2801-2823 
    Details
    ISSN: 1573-1561
    Keywords: Acyl sugar esters ; glandular trichomes ; water availability ; genetic variation ; allocation cost ; chemical defense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Natural populations of Datura wrightii in southern California are dimorphic for trichome type. Some plants within populations produce greater than 85% glandular trichomes, whereas other produce mainly nonglandular trichomes. Glandular trichome exudates in D. wrightii consist of glucose esterified with straight chain C6–C9 acids. These exudates, and similar exudates in other species, confer resistance to several insect herbivore species. We tested the hypothesis that water was limiting sugar ester production and examined the extent to which trichome density was determined by environmental factors by measuring the concentrations of sugar esters and the densities of trichomes on leaves of plants grown under different irrigation treatments. Water did not limit sugar ester production, as unwatered plants produced 36% more millimoles of glucose esters per square centimeter of leaf surface than did watered plants. Although the addition of water increased leaf size, densities of both nonglandular and glandular trichomes did not change with leaf length or area, suggesting that plants having larger leaves initiated more trichomes in order to maintain nearly constant densities. Millimoles of sugar esters produced did not correlate with densities of glandular trichomes, suggesting that other factors in addition to glandular trichome number govern the production of sugar esters for plant defense.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026493927622
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  • 10
    Electronic Resource
    Electronic Resource
    Virus Membrane Fusion Proteins: Biological Machines that Undergo a Metamorphosis (2000)
    Springer
    Bioscience reports 20 (2000), S. 597-612 
    Details
    ISSN: 1573-4935
    Keywords: membrane fusion ; viral glycoprotein ; heptad repeats ; proteolytic processing ; glycosylation ; oligomerization ; fusion peptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Fusion proteins from a group of widely disparate viruses, including the paramyxovirus F protein, the HIV and SIV gp160 proteins, the retroviral Env protein, the Ebola virus Gp, and the influenza virus haemagglutinin, share a number of common features. All contain multiple glycosylation sites, and must be trimeric and undergo proteolytic cleavage to be fusogenically active. Subsequent to proteolytic cleavage, the subunit containing the transmembrane domain in each case has an extremely hydrophobic region, termed the fusion peptide, or at near its newly generated N-terminus. In addition, all of these viral fusion proteins have 4–3 heptad repeat sequences near both the fusion peptide and the transmembrane domain. These regions have been demonstrated from a tight complex, in which the N-terminal heptad repeat forms a trimeric-coiled coil, with the C-terminal heptad repeat forming helical regions that buttress the coiled-coil in an anti-parallel manner. The significance of each of these structuralelements in the processing and function of these viral fusion proteins is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010467106305
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