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  • 1
    Electronic Resource
    Electronic Resource
    Uptake of SO2 in shoots of Scots pine: field measurements of net flux of sulphur in relation to stomatal conductance (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 5 (1982), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Net fluxes of gaseous sulphur compounds, water vapour and carbon dioxide to current- and one-year-old shoots of Scots pine were simultaneously measured in the field. The shoots were fumigated in temperature-controlled assimilation chambers with sulphur dioxide at concentrations ranging from 40 to 250 μg m−3 (15–95 ppb). The hypothesis that stomatal opening regulates the uptake of sulphur dioxide was tested. The following conclusions were reached concerning the dry deposition of sulphur dioxide to a dry coniferous shoot.There was a marked diurnal variation in the uptake rate of sulphur dioxide. The net deposition velocity of sulphur was about three times higher during the day than during the night during July-October. Stomatal opening was not the primary factor controlling the dry deposition rate of sulphur dioxide. The net dry deposition rate was significantly smaller than the calculated rate based on stomatal conductances for water vapour.Part of this deviation could be explained by re-emission of reduced sulphur compound(s) from the needles. The re-emission of sulphur was a light-dependent process and might be of great significance for the sulphur balance calculations.A variable deposition velocity should be used in atmospheric transport models to account for the diurnal and seasonal variation in the surface resistance of a dry canopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11587612
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  • 2
    Electronic Resource
    Electronic Resource
    Immunogenic Properties of α(1 → 6) Dextran, Its Protein Conjugates, and Conjugates of Its Breakdown Products in Mice (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 19 (1984), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Mice were immunized with α(1–6) dextran, either as such or coupled to protein carriers, and their anti-dextran response was measured by a solid-phase radioimmunoassay and the Farr assay. Like earlier investigators we found that protein-conjugated dextran was more antigenic than plain dextran. Our novel findings were that (1) a standard dose (30 μg of dextran per injection) coupled to strongly antigenic protein (chicken serum albumin (CSA)) was three times more antigenic than dextran coupled to weakly antigenic bovine serum albumin (BSA); (2) dextrans of low molecular weight (1000–10,000 daltons) coupled to CSA induced at least ten times stronger secondary responses than did a similarly coupled macromoleculur dextran (5–40 million daltons); (3) variation of the CHO/protein ratio from 0.3 to 1 had little effect on the antigenicity of the dextran. Increase of the ratio from one appeared 10 decrease immunogenicity when BSA was the carrier but not when CSA was ihe carrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.1984.tb00965.x
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  • 3
    Electronic Resource
    Electronic Resource
    Search for the density effect in inner-shell lonization by ultra relativistic electron impact (1982)
    Springer
    The European physical journal 305 (1982), S. 9-19 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have extended the measurements ofK-andL-shell ionization cross sections by electron impact into the ultra relativistic energy region, 0.9≦E≦2.0 GeV, in order to search for a saturation of the cross section. This phenomenon, which is due to the polarization of the target medium, is called density effect. It is predicted to occur at several hundred MeV impact energy and preferentially for lowZ target elements. Theoretical calculations are presented, based on the one-photon-exchange approximation. The absolute measurements of theK-andL-shell cross sections for Ni(K), Cu(K), Ag(K, L) and Au(L) performed at the 2.5 GeV electron synchrotron of the Bonn University, however, exhibit that the cross sections show no saturation but are still increasing. Furthermore, from theK X-ray yields, obtained at 0.9 and 2.0 GeV by bombarding the lowZ elements S, Ca, Mn, Ni and Ge, we obtain for the corresponding cross section ratio σ K (2GeV)/σ K (0.9GeV)=1.08±0.01 on the average. TheK X-ray yield of a composite Ca — Mn target amounts to $$[\sigma _K (Ca;2.0GeV)/\sigma _K (Mn;2.0GeV)]/[\sigma _K (Ca;0.9GeV/\sigma _K (Mn;0.9GeV)] = 0.99 \pm 0.02.$$ . All three results are in disagreement with theory. This severe discrepancy is discussed but the origin for it is not yet understood.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01415072
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  • 4
    Electronic Resource
    Electronic Resource
    Comment on fusion cross sections in the40Ar+40Ca and40Ca+40Ca systems (1981)
    Springer
    The European physical journal 302 (1981), S. 365-366 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Cross sections for the production of evaporation residues in a fusion reaction have been extracted from measurements of cross sections for elastic, quasi-elastic and deep inelastic scattering of40Ar projectiles on40Ca target nuclei at incident energies ELAB=191, 236 and 272 MeV. The extracted data are compared with the predictions of a one-body window-friction model including a neck configuration in the interaction phase between the projectile and target nuclei. Furthermore, the results for the40Ar+40Ca system are compared to those obtained in the similarly mass-symmetric system40Ca+40Ca where directly measured evaporation residue data are available. The fusion reaction in heavy ion collisions has so far been studied mostly at low incident energies and for systems where the fusion cross section is in good approximation given by the cross section for evaporation residues [1]. This approximation has been verified only for heavy interacting systems (A〉 100 for the combined system). In this paper we comment on the problems of fusion cross sections for the lighter projectile-target combination40Ar+40a and give evidence that this approximation may not be generally valid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01414272
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  • 5
    Electronic Resource
    Electronic Resource
    Measurement of theK-shell fluorescence yield of13Al,20Ca,23V and25Mn for vacancies produced by the relativistic electron impact (1981)
    Springer
    The European physical journal 300 (1981), S. 103-104 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The K-shell fluorescence yield of Al, Ca, V and Mn has been measured by bombarding thin solid targets of 0.5–4.0μg/cm2 on 6–10μg/cm2 carbon backing with relativistic electrons of 30 and 60 MeV and by simultaneous detection of the x-ray and Auger yield by means of a Si(Li) detector and an electrostatic electron spectrometer, respectively. While the values obtained for25Mn (ωK=0.310 −0.020 +0.023 ) and23V(ωK=0.252 −0.018 +0.020 ) agree within their accuracy with known experimental and theoretical data, are the values of20Ca (ωK=0.127 −0.011 +0.013 ) and13Al(ωK=0.027±0.005) lower than experimental or recommended empirical values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01412621
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  • 6
    Electronic Resource
    Electronic Resource
    Quenching of the electron scattering form factor of the 1+ state at 3.48 MeV in88Sr and the influence of theΔ(1232)-isobar (1982)
    Springer
    The European physical journal 305 (1982), S. 231-234 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The form factor for excitation of the 1+ state at 3.48 MeV in88Sr by inelastic electron scattering has been measured for momentum transfersq=0.24–0.62 fm−1. Neither its magnitude nor shape can be described employing the best available nuclear wave functions. We demonstrate with a schematic model that the observed reduction of the form factor may be understood by taking into account a renormalization of theM1-operator due to virtualΔ-hole excitations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01417439
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  • 7
    Electronic Resource
    Electronic Resource
    On the fusion dynamics of40Ar+40Ca — Fusion-fission and fusion-evaporation (1983)
    Springer
    The European physical journal 313 (1983), S. 57-67 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Evaporation residue measurements have been made for the40Ar+40Ca system at high incident energies,E Lab=161, 190, 236 and 273 MeV. A dynamical description of the fusion process is presented, where in a trajectory model both rotational and neck degrees-of-freedom are included. Using this model maximuml-values for fusion are determined and at high incident energies are found to be significantly lower than those found when using the more usual one-dimensional effective nucleus-nucleus potential. The fusion cross sections minus the fission component yields evaporation residue cross sections that are in good agreement with the data. Also, mass distributions of the evaporation residues compare well with statistical-decay model predictions. A comparison is made with the similarly mass-symmetric40Ca+40Ca system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02115843
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  • 8
    Electronic Resource
    Electronic Resource
    Population dynamics and production of Daphnia hyalina Leydig and Daphnia cucullata Sars in Tjeukemeer (1982)
    Springer
    Hydrobiologia 95 (1982), S. 235-259 
    Details
    ISSN: 1573-5117
    Keywords: population dynamics ; secondary production ; Cladocera ; Daphnia ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As part of a research programme on the food chains in Tjeukemeer, the Daphnia hyalina and Daphnia cucullata populations were studied for three successive years. To analyse the factors regulating the production of these two species, their population parameters (density, size distribution, fecundity) and population dynamics (birth rate, mortality rate) were studied and related to environmental factors. Since Daphnia in Tjeukemeer shows continuous recruitment, the population dynamics model ‘INSTAR’ was developed and used to integrate field data with laboratory data on development rates and length-weight relationships. The dynamics of the Daphnia species are mainly regulated by temperature and fish predation, the latter affects both birth rate and mortality. Total annual Daphnia production was 3.1–6.9 g org. dry wt M−2, and annual P/B ratio ranged from 25 to 40 for D. cucullata and from 45 to 49 for D. hyalina.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00044487
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  • 9
    Electronic Resource
    Electronic Resource
    Population dynamics and production of Acanthocyclops robustus (Sars) and Mesocyclops leuckarti (Claus) in Tjeukemeer (1982)
    Springer
    Hydrobiologia 95 (1982), S. 261-274 
    Details
    ISSN: 1573-5117
    Keywords: population dynamics ; secondary production ; cyclopoid copepods ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The population dynamics and production ecology of the two dominant copepod species, Acanthocyclops robustus and Mesocyclops leuckarti, in Tjeukemeer (The Netherlands) were studied for three successive years. Since copepods in Tjeukemeer show continuous recruitment, a population dynamics model ‘INSTAR’ was developed and used to integrate field data on population density, population structure and fecundity and laboratory data on development rates and length-weight relationships. The pattern of size specific mortality indicated that both invertebrate and vertebrate predation were important in the regulation of population numbers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00044488
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  • 10
    Electronic Resource
    Electronic Resource
    INSTAR, a discrete event model for simulating zooplankton population dynamics (1982)
    Springer
    Hydrobiologia 95 (1982), S. 275-285 
    Details
    ISSN: 1573-5117
    Keywords: simulation model ; zooplankton population dynamics ; discrete event formalism ; individual-oriented modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper we discuss the basic principles of discrete event, individual oriented, data based modelling in ecology, and we present an application of this modelling strategy. The strategy is contrasted with some more conventional modelling strategies with respect to its purpose, its basic units and its heuristic properties. INSTAR applies this modelling strategy to the simulation of the fluctuations of the population structure and density of microcrustaceans through the year. The model encompasses one microcrustacean species at a time, and its interface with the rest of the ecosystem; it has been applied to several Cladocera and Copepoda species in a shallow eutrophic lake in the Netherlands (Vijverberg & Richter 1982a, b). Possibilities for extending the model are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00044489
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