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  • 1
    Keywords: Report
    Type of Medium: Online Resource
    Pages: Online-Ressource (116 Seiten, 6 MB) , Diagramme, Karten
    Series Statement: Berichte aus dem Institut für Meereskunde an der Christian-Albrechts-Universität Kiel 280
    Language: German
    Note: Zusammenfassung in deutscher und englischer Sprache
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 42 (1977), S. 351-355 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract High numbers of copepod carcasses were found in zooplankton samples taken in the upwelling system off N.W. Africa. The validity of the measurements is discussed. It is suggested that rapid changes in the environment, caused by the pulsation of violent mesoscale upwelling at the shelf edge, result in an increased mortality in zooplankton. Considerations are made on the role of copepod detritus in the upwelling region.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 129 (1997), S. 549-560 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mesozooplankton (〈5 mm) collected by stratified oblique tows with a 1-m2 MOCNESS was examined at four stations in the Arabian Sea, with special reference to the bathypelagic zone. The profiles commenced about 20 m above bottom, at 4430 m as a maximum depth. The highest mesozooplankton biomass concentrations (wet weight per cubic meter) were obtained from the surface layer during night. A secondary maximum was situated between 150 and 450 m, with maximum concentrations at daytime. This layer coincided with the daytime residence depth of the deep scattering layer. The standing crop of the mesozooplankton in the upper 1000 m was highest at station WAST at 16°N; 60°E (ca. 47 000 mg m−2); station CAST at 14°N; 65°E ranked second (ca. 22 500 mg m−2), followed by station SAST at 10°N; 65°E (11 420 mg m−2). The differences can be related to different productivity regimes at the sea surface generated by the Findlater Jet during the SW monsoon. The differences in surface production were also reflected below 1000 m depth, in the bathypelagic zone, with mesozooplankton wet weights of 5330 mg m−2 at WAST, 3210 mg m−2 at CAST, 3390 mg m−2 at EAST (15°N; 65°E) and 2690 mg m−2 at SAST. The decrease of mesozooplankton concentration with depth in the oxygen minimum zone (OMZ) was stronger than in comparable depths of open-ocean areas where an OMZ is absent. Among the discriminated four size classes of mesozooplankton, the largest fraction (2 to 5 mm) indicated a biomass peak at 1200 m depth, which coincided with the lower boundary layer of the OMZ. The rate of decrease of mesozooplankton biomass with depth in the bathypelagic zone was statistically similar between the sites, even though the absolute zooplankton biomass at the sites was different. There is no evidence that the presumed lower carbon degradation rates in the OMZ of the Arabian Sea caused a larger standing crop and less of a decrease in biomass with depth in the bathypelagic zone in comparison to other seas.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 13 (1972), S. 70-88 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The present paper compiles results of recent studies on distribution, abundance, migratory pattern and feeding of invertebrates and early stages of fish in the uppermost layer of the subtropical and boreal Atlantic Ocean. Three ecological groups are described: euneuston, living permanently at the surface; facultative neuston, invading the uppermost layer mainly during night; pseudoneuston, comprising the uppermost part of populations which are mainly concentrated in deeper layers. For several species of fish, a shift in behaviour was found: eggs and yolk-sac larvae are mainly missing from the uppermost layers, young post-larvae staying permanently close to the surface, and old larvae and juveniles performing diurnal vertical migrations. During daytime, the uppermost layer serves as a refuge for only a small number of welladapted organisms, while at dusk and at night considerable immigration occurs. During daytime, zooneuston is mainly carnivorous or omnivorous. In boreal and turbid waters, the ecological differences between the uppermost and lower layers are reduced. Neuston is an important element of the ecosystem in these areas.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 7122-7138 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The importance of the block or band Lanczos method for many-body Green's function calculations of atomic and molecular systems is discussed. The usual computation schemes for determining the Green's function involve the diagonalization of Hermitian secular matrices. Considerable numerical difficulties arise, on the one hand, from the size of these matrices and, on the other hand, from the large number of eigenvalues and eigenvectors which often need to be computed in practice. In the case of the one-particle Green's function it is shown how the computational effort of the diagonalization process can be substantially reduced using block Lanczos. The proposed procedure which consists of a block Lanczos "prediagonalization'' and a subsequent diagonalization of the resulting smaller secular matrices quite naturally exploits the specific structure of the secular problems encountered. Its computational performance is demonstrated in a model application to the benzene molecule. The calculation of the complete valence-shell ionization spectra of the systems BeF2−4, BeF−3, and BeF2 is devised as a further application of the method in the particular case where the treatment of the full secular problem is computationally prohibitively expensive. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 8877-8891 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The existence and properties of the closely related tetrahedral tetracoordinated dianions BeF2−4, MgF2−4, and CaF2−4 in the gas phase are discussed. It is shown that these dianions exist in long-lived intermediate states bound by a barrier to dissociation. To definitely establish whether the added electrons remain bound, the outer-valence ionization potentials have been computed via the Green's function formalism which takes account of relaxation and electron correlation effects beyond the one-particle approximation. The results show that the potential barrier as well as the binding of the excess electrons of the dianions increase along the sequence BeF2−4, MgF2−4, and CaF2−4. The possibility of dynamic autodetachment is analyzed by computing the potential energy surfaces of the lowest anionic and dianionic states of the tetrafluorides at both the independent-particle and the correlated levels. Strong effects of hole localization as a symmetry breaking phenomenon are observed accompanying the outer-valence ionization of the dinegative system sharing most of the outer-valence electron density on the symmetry equivalent fluorine ligands. Attempts are made to interrelate the nature or character of the chemical bonding with the thermodynamic stability of the dianion which also increases in going from BeF2−4 to MgF2−4 and finally to CaF2−4. In this connection, some observations have been made which do not fit into expectations as taught by chemical experience. Calculations on the tetrachloride dianions BeCl2−4, MgCl2−4, and CaCl2−4 have also been performed. The major findings are briefly discussed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Few body systems 2 (1987), S. 33-51 
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The introduction of approximations to evaluate physical properties of few- or many-body systems may violate exact symmetries and conservation laws. If, for example, the numberN of particles is incorrectly reproduced by the approximation, it can be shown that the optical potential for scattering of charged particles exhibits a spurious long-range potential. It is suggested to correct forN by introducing a particle-number-dependent interaction into the Hamiltonian, which does not influence exact results but changes the results of the approximation. The interaction is such that the original working equations of the approximation scheme undergo a trivial change only. As an example a simple model is investigated. It is found that restoringN also substantially improves all observables of the system.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 18 (1991), S. 299-305 
    ISSN: 1434-6079
    Keywords: 79.20.Nc ; 31.20.Tz ; 34.50.Gb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a theoretical analysis on the existence of doubly negative molecular ions in the gas phase. A thorough investigation involves the discussion of two main problems: the stability of the system with respect to dissociation and the stability to the loss of an electron. An adequate treatment of both problems requires the choice of proper basis sets as well as the application of higher levels of theory. As an example the BeF 4 2− dianion is studied in detail. Here we use configuration interaction and many-body Green's function approaches. Strong basis set dependencies in the calculations are observed which have no analogy in neutral systems.
    Type of Medium: Electronic Resource
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  • 9
    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 10
    Publication Date: 2016-10-05
    Description: We review current knowledge and understanding of the biology and ecology of the calanoid copepod Calanus helgolandicus in European waters, as well as provide a collaborative synthesis of data from 18 laboratories and 26 sampling stations in areas distributed from the northern North Sea to the Aegean and Levantine Seas. This network of zooplankton time-series stations has enabled us to collect and synthesise seasonal and multi-annual data on abundance, body size, fecundity, hatching success and vertical distribution of C. helgolandicus. An aim was to enable comparison with its congener Calanus finmarchicus, which has been studied intensively as a key component of European and north east Atlantic marine ecosystems. C. finmarchicus is known to over-winter at depth, whereas the life-cycle of C. helgolandicus is less well understood. Overwintering populations of C. helgolandicus have been observed off the Atlantic coast between 400 and 800 m, while in the Mediterranean there is evidence of significant deep-water populations at depths as great as 4200 m. The biogeographical distribution of C. helgolandicus in European coastal waters covers a wide range of habitats, from open ocean to coastal environments, and its contribution to mesozooplankton biomass ranges from 6% to 93%. Highest abundances were recorded in the Adriatic and off the west coast of Spain. C. helgolandicus is generally found in 9–20 °C water, with maximum abundances from 13–17 °C. In contrast, C. finmarchicus is found in cooler water between 0 and 15 °C, with peak abundances from 0 to 9 °C. As water has warmed in the North Atlantic over recent decades, the range of C. helgolandicus and its abundance on the fringes of its expanding range have increased. This review will facilitate development of population models of C. helgolandicus. This will not only help answer remaining questions but will improve our ability to forecast future changes, in response to a warming climate, in the abundance and distribution of this important species.
    Type: Article , PeerReviewed
    Format: text
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