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  • 1
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    PANGAEA
    In:  Supplement to: Ehrmann, Werner; Schmiedl, Gerhard; Seidel, Martin; Krüger, Stefan; Schulz, Hartmut (2016): A distal 140 ka sediment record of Nile discharge and East African monsoon variability. Climate of the Past, 12(3), 713-727, https://doi.org/10.5194/cp-12-713-2016
    Publication Date: 2019-01-26
    Description: Clay mineral assemblages in a sediment core from the distal Nile discharge plume off Israel have been used to reconstruct the late Quaternary Nile sediment discharge into the Eastern Mediterranean Sea (EMS). The record spans the last ca. 140 ka. Smectite abundances indicate the influence of the Blue Nile and Atbara that have their headwaters in the volcanic rocks of the Ethiopian highlands. Kaolinite abundances indicate the influence of wadis, which contribute periodically to the suspension load of the Nile. Due to the geographical position, the climate and the sedimentary framework of the EMS is controlled by two climate systems. The long-term climate regime was governed by the African monsoon that caused major humid periods with enhanced sediment discharge at 132 to 〈126 ka (AHP5), 116 to 99 ka (AHP4), and 89 to 77 ka (AHP3). They lasted much longer than the formation of the related sapropel layers S5 (〉2 ka), S4 (3.5 ka) and S3 (5 ka). During the last glacial period (MIS 4-2) the long-term changes of the monsoonal system were superimposed by millennial-scale changes of an intensified mid-latitude glacial system. This climate regime caused short but pronounced drought periods in the Nile catchment, which are linked to Heinrich Events and alternate with more humid interstadials. The clay mineral record further implies that feedback mechanisms between vegetation cover and sediment discharge of the Nile are detectable but of minor importance for the sedimentary record in the southeastern Mediterranean Sea during the investigated African Humid Periods.
    Type: Dataset
    Format: text/tab-separated-values, 7312 data points
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  • 2
    ISSN: 1432-0649
    Keywords: PACS: 47.27.-i; 42.62.Fi; 47.55.Kf
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The feasibility of liquid-phase velocity measurements in dense sprays by 2D laser-based flow tagging is demonstrated. Velocity measurements in dense sprays are difficult with conventional techniques because of the high number densities of droplets, the optical thickness of the medium, and multiple light-scattering effects. The present flow-tagging technique is based on phosphorescent tracer molecules, which are excited by a grid of pulsed ‘write’ laser beams. The motion of the tagged droplet groups can be observed by a CCD camera in this way. In addition, multiple consecutive velocity measurements are performed by ‘droplet-group tracking’. This yields the acceleration along the trajectory of individual groups of droplets in unsteady sprays.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4475-4477 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Small-angle neutron scattering was used to study the magnetic properties of intracellular magnetite crystals (magnetosomes) in the bacterium, Aquaspirillum magnetotacticum, grown in pure culture. An average of 20 single-domain magnetite (Fe3O4) particles of diameter 400–500 A(ring) are arranged in a chain that longitudinally traverses each cell. The net magnetic dipole moment carried by each chain is sufficient to orient the bacterium in the geomagnetic field. A contrast variation series, performed on a nonmagnetic variant, established that a 30% D2O/H2O ratio in the suspension buffer resulted in the minimization of the scattering from the bacterium itself, thereby enhancing that from the magnetosomes. Measurements of A. magnetotacticum in 30% D2O and an applied field of 25 G confirmed that the scattering from the magnetite particles in bacteria grown under iron-rich conditions is of ferromagnetic character, while that from magnetosomes in bacteria grown under iron-starved conditions is characteristic of superparamagnetic particles. In both cases, the wave-vector dependence of the scattering can be represented by a sum of Lorentzian plus Lorentzian squared terms, from which longitudinal as well as transverse spin correlation lengths were extracted. The results describe dynamic spin correlation lengths on the order of 50 A(ring), which are superposed on the static magnetosome cluster.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The excitation energy transfer (EET) of a bichromophoric cross-shaped molecule was investigated by stationary polarized fluorescence spectroscopy in the solid state. For this purpose 2,2′,7,7′-tetrakis(biphenyl-4-yl)-9,9′-spirobifluorene was embedded in a polymeric bisphenol-A-polycarbonate (PC) matrix. The dependence of the fluorescence on concentration and wavelength was determined. The role of the intermolecular and intramolecular EET is dealt with separately and discussed by means of the degree of polarization. The intermolecular excitation energy transfer is described in terms of a Förster transfer mechanism. The intramolecular transfer is prevented for the zero-point vibrational levels by the molecular cross-shaped structure, but is found for a wide range of wavelength, presumably based on vibrationally excited states. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2012-07-18
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Nuclear Materials 141-143 (1986), S. 119-123 
    ISSN: 0022-3115
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Physics
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A laser-based technique is presented that can be used to measure the instantaneous velocity field of the continuous phase in sprays and aerosols. In contrast to most well established laser-based velocity measurement techniques, this method is independent of particle seeding and Mie scattering. Instead of that it is based on gaseous flow tracers and laser-induced fluorescence (LIF). Inhomogeneous tracer gas distributions, which are created by an incomplete, turbulent mixing process, are exploited for flow tracing. The velocity field can be measured close to the droplets, because frequency-shifted LIF is separated from Mie scattering by optical filters. Validation tests and results from a water spray in air are given. Accuracy and spatial resolution are discussed in detail.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The feasibility of simultaneous measurements of the instantaneous velocity fields of gaseous and liquid phase is demonstrated in a laminar, unsteady two-phase flow. Thus, the instantaneous relative velocity field can be measured in such media. This is achieved by combining Particle Image Velocimetry (PIV) and a gas-phase velocimetry technique, which is based on laser-induced fluorescence (LIF) from a gaseous tracer. The wavelength shift of LIF is exploited to separate it from Mie scattering from the liquid phase. The new technique and the PIV measurement system work independently in this approach. Thus, the measurement accuracy and precision of the new technique can be validated by comparing it to the PIV results in regions of the flow field where the relative velocity vanishes.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 82 (1991), S. 221-226 
    ISSN: 1432-2242
    Keywords: Outcrossing rate ; Plant density ; Mixed mating model ; Isozymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In this paper, the mating systems of experimental populations of C. laminuligera and C. lutea are described. Outcrossing rates (t) were estimated for four populations of C. laminuligera and three populations of C. lutea using allozyme phenotypes of open-pollinated individual plant families. Populations were grown at densities of 1.0 × 1.0 m (low) and 0.04 × 0.3 m (high). Pollen and ovule frequencies and single locus and multilocus outcrossing rates were estimated for each population using the mixed-mating model. Multilocus estimates of t ranged from 0.83 to 0.98 and 1.00 to 1.01 for low and high density populations of C. laminuligera, respectively, and 0.17 to 0.26 and 0.36 to 0.54 for low and high density populations of C. lutea, respectively. C. laminuligera is predominantly allogamous; however, selfing rates as great as 17% were observed for this species. C. lutea is predominantly autogamous, but outcrossing rates as great as 54% were observed for this species. Outcrossing rates increased as density increased within C. lutea populations.
    Type of Medium: Electronic Resource
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