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  • Wiley  (134.953)
  • American Physical Society (APS)
  • International Union of Crystallography (IUCr)
  • 2005-2009  (109.909)
  • 1965-1969  (27.782)
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  • 1
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    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 32(L10618), ISSN: 0094-8276
    Publikationsdatum: 2018-12-07
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2016-01-18
    Beschreibung: From a synthesis of recent oceanic observations and paleo-data it is evident that certain species of giant diatoms including Rhizosolenia spp. Thalassiothrix spp. and Ethmodiscus rex may become concentrated at oceanic frontal zones and subsequently form episodes of mass flux to the sediment. Within the nutrient bearing waters advecting towards frontal boundaries, these species are generally not dominant, but they appear selectively segregated at fronts, and thus may dominate the export flux. Ancient Thalassiothrix diatom mat deposits in the eastern equatorial Pacific and beneath the Polar Front in the Southern Ocean record the highest open ocean sedimentation rates ever documented and represent vast sinks of silica and carbon. Several of the species involved are adapted to a stratified water column and may thrive in Deep Chlorophyll Maxima. Thus in oceanic regions and/or at times prone to enhanced surface water stratification (e.g., during meltwater pulses) they provide a mechanism for generating substantial biomass at depth and its subsequent export with concomitant implications for Si export and C drawdown. This ecology has important implications for ocean biogeochemical models suggesting that more than one diatom “functional type” should be used. In spite of the importance of these giant diatoms for biogeochemical cycling, their large size coupled with the constraints of conventional oceanographic survey schemes and techniques means that they are undersampled. An improved insight into these key species will be an important prerequisite for enhancing our understanding of marine biogeochemical cycling and for assessing the impacts of climate change on ocean export production.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , peerRev
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2019-07-17
    Beschreibung: A continuous high-resolution record of digital images has been obtained from the North Greenland Ice Core Project (NorthGRIP) ice core (75.1N, 42.3W) in the depth interval from 1330 m to the bedrock at 3085 m. The ice core stratigraphy is clearly visible throughout the glacial period with the most frequent and brightest visible layers appearing during the coldest events. Down to a depth of 2600 m the horizontal layeringis very regular; below this depth, small irregularities in the layering start to appear, and below 2800 m the visual stratigraphy becomes more uncertain, perhaps because of penetration into climatically warmer ice. Comparison of the visual stratigraphy with high-resolution continuous records of chemical impurities and dust reveals a high degree of correlation, which indicates that the visible layers are caused by these impurities. Anew approach is used to automatically determine annual layer thicknesses from the visual stratigraphy record by carrying out a frequency analysis of the most prominent visible layers in the profile. The result gives strong support for the NorthGRIP timescale model.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2021-05-19
    Beschreibung: 1. Seahorses (Hippocampus spp.), many of which are listed as Vulnerable or Endangered on the IUCN Red List, are traded worldwide as souvenirs, aquarium fish and, primarily, for use in traditional medicines. Given concern over the sustainability of this trade, the genus was added to Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in May 2004. 2. This paper reports findings of the first ever survey of seahorse trade in Africa, conducted in Kenya and Tanzania in May and June 2000. 3. Seahorse trade in Kenya was found to be negligible, with approximately 10 live seahorses exported as aquarium fish annually. Until 1998, however, Kenya may have imported somewhere from 1 to 2.3 t of dried seahorses annually from Tanzania for re-export to Asian medicine markets. Seahorse trade in Tanzania remained substantial, with at least 630–930 kg of dried seahorse exported directly to Asia each year. 4. Accounts of declines in seahorse availability and seahorse size, although few in number, could be early warning signs that wild populations are suffering, at least locally. Close monitoring of future developments in the trade will be essential to allow for timely conservation action as and when necessary, and would contribute to our understanding of the ecological and economical implications of small-scale, non-food fisheries. Copyright # 2004 John Wiley & Sons, Ltd.
    Beschreibung: Published
    Schlagwort(e): Hippocampus spp ; By catch ; Non-food fisheries ; Seahorse trade ; Endangered species ; Aquatic animals
    Repository-Name: AquaDocs
    Materialart: Journal Contribution , Non-Refereed , Article
    Format: 438174 bytes
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 1 (1968), S. 1-19 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The desirability and requirements for a specimen capable of testing the resolving power and other image characteristics of an electron microscope are discussed in detail. In this discussion, the underlying diffraction phenomena are particularly utilized. A partially graphitized carbon black is shown to satisfy the requirements extremely well and constitutes an easily prepared specimen for conducting tests of image quality in the molecular size range. The structure of the test object is known in detail with the result that readily interpretable phase contrast images are obtained. Micrographs illustrating the use of the 3.4 Å (002) spacing for magnification calibration, astigmatism and asymmetry check as well as resolving power are exhibited. The second order c-spacing of 1.7 Å is occasionally found in an image. The micrographs shown herein were taken with two different electron microscopes by different operators obtaining the same structural detail in the images. It is concluded that the carbon black test object offers the best possibilities for evaluating image performance of any specimen yet suggested.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 1 (1968), S. 60-60 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 1 (1968), S. 61-67 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The long range order in a powder sample of Ag3Mg has been studied by X-ray diffraction as a function of quenching temperature below the critical ordering temperature of 665°K. By measuring the positions and integrated intensities of fundamental, superlattice and satellite reflections, the latter arising from the periodic anti-phase boundary structure, the variation with temperature of the overall long range order, antiphase boundary order, and anti-phase boundary periodicity have been determined. It appears that the anti-phase boundaries disorder slightly more with increasing temperature than the average superlattice, and that the boundary spacing, nominally equal to two (M = 2), increases towards that ideal value with increasing disorder below the critical point. These resalts are qualitatively interpreted by extending the reasoning of Sato & Toth on equilibrium long period superlattices to include the case where the Fermi surface becomes progressively more diffuse with increasing disorder.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 1 (1968), S. 84-90 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Bent-glass mirrors can be used to produce a narrow, highly collimated X-ray beam, particularly suitable for photographing diffraction patterns from crystals with very large unit cells (i.e., several hundred Å to a side). A camera is described that employs double-mirror focusing optics with a precession apparatus. A comparison of optical reflection and simple collimation shows that for high resolving power, focusing devices are very much superior to pinhole collimators. The reduction of background is especially noteworthy. Use of this camera has permitted the collection of accurate three-dimensional data from crystals of tomato bushy stunt virus.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 1 (1968), S. 121-122 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A new method for determination of the polarization factor of a crystal monochromator is presented. This method is based on the use of polarized X-rays produced by anomalous transmission or the Borrmann effect. The polarization factors of two quartz (10\overline 11) monochromators of Johansson type have been measured with Cu Kα radiation, and the resulting values are in close agreement with the expression derived from the kinematic diffraction theory.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 1 (1968), S. 128-130 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: An automatic balanced filter box which may be used on most standard X-ray diffraction tubes is described. It is designed to be used in conjunction with a wide variety of automated X-ray diffraction experiments to change Ross filters and insert attenuators into the incident X-ray beam on receipt of appropriate commands from the control system. The positions of the filters and attenuators may be displayed at all times by using feedback signals generated by a combination of light sources and photocells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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