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  • 1990-1994  (3)
  • 1985-1989  (1)
  • 1965-1969
  • 1993  (3)
  • 1986  (1)
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  • 1990-1994  (3)
  • 1985-1989  (1)
  • 1965-1969
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  • 1
    Electronic Resource
    Electronic Resource
    Acoustic properties of proton-exchanged LiNbO3 studied using the acoustic microscopy V(z) technique (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 2517-2522 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report measurements of proton-exchanged LiNbO3 using acoustic microscopy in the V(z) mode, together with optical waveguide mode observations. In the present case, samples were prepared using dilute benzoic acid containing a small mole percent of lithium benzoate. Substantial changes in surface acoustic wave (SAW) propagation velocity due to proton exchange have been observed on all three major-axis crystal cuts, with both increase and decrease in velocity occurring, depending on propagation direction. Changes in attenuation are also observed. Using the V(z) technique with a line-focus cylindrical lens has enabled complete velocity surfaces for proton-exchanged lithium niobate to be obtained with reasonable precision, based on simplified isotropic calculations of acoustic propagation in layered media and the assumption that the proton-exchange region is uniform with a depth obtainable from optical waveguide mode calculations. It is concluded that the V(z) acoustic microscopy technique can provide a powerful tool in the study of the SAW properties of proton-exchanged LiNbO3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337114
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Glial Fibrillary Acidic Protein (GFAP) Indicates in Vivo Exposure to Environmental Contaminants: PCBs in the Atlantic Tomcod (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 679 (1993), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1993.tb18329.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Genetic population structure in two tropical sponge-dwelling shrimps that differ in dispersal potential (1993)
    Springer
    Marine biology 116 (1993), S. 459-470 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The spatial context in which “host races” of parasitic animals originate is a central issue in the controversial theory of sympatric speciation. Sponge-dwelling shrimps in the genus Synalpheus provide a good system for evaluating the possibility of resource-associated divergence in sympatry. I used allozyme electrophoresis to assess the genetic population structure of two Caribbean Synalpheus species sampled in 1988 to 1990 at a hierarchy of spatial scales. S. brooksi Coutière is a host-generalist, using several sponge species in an area, and develops directly, with no planktonic larval stage. G-tests and estimates of F ST revealed highly structured populations in this species, with significant differentiation among samples from individual reefs within a region, and strong divergence among regions (Panama, Belize, Florida). Moreover, samples of S. brooksi taken from the two sponges Spheciospongia vesparium (Lamarck) and Agelas clathrodes (Schmidt) in Panama, and separated by ≤3 km, showed significant differentiation at both of the loci that were polymorphic in these populations. Genetic distances between these host-associated populations averaged 〉60% greater than distances between samples from the same host species and were comparable to, or greater tha, those for some inter-regional comparisons. These genetic data corroborate a previous finding of demographic differences between the same populations. The second species, S. pectiniger Coutière, occurs only in Spheciospongia vesparium, and produces swimming larvae. Although allele frequencies in this species differed significantly among the three regions, S. pectiniger showed no differentiation within regions, and significantly lower differentiation (F ST) among regions than its direct-developing congener. These data suggest that genetic population structure in these two commensal crustaceans is related to dispersal potential, and that restricted dispersal may allow the divergence of host-associated populations on a local scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350063
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Postcrania and the specific mate recognition system (1993)
    Springer
    Human evolution 8 (1993), S. 281-289 
    Details
    ISSN: 1824-310X
    Keywords: Hominids ; Recognition Concept of Species ; Specific Mate Recognition System ; Postcrania
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Recognition Concept of Species is examined for its potential usefulness in discriminating speciation events in the hominid fossil record. Controversies over species-specific characteristics amongHomo erectus and archaicHomo sapiens have centred on traits of the skull, largely because this element is most commonly preserved. Modern humans have an intuitive knowledge of their own Specific Mate Recognition System (SMRS), and therefore have the opportunity to compare their own SMRS to that of fossil hominids and the extent pongids. Such comparison suggests that our own skeletal SMRS may depend less on features of the skull than on the morphology of the postcranial anatomy. We propose that these components be further examined in this regard. We tentatively conclude that examination of the Recognition Concept of Species indicates that from lateHomo erectus onwards, the same SMRS has been shared in common by all hominids, including modernHomo sapiens. This suggests that, following the SMRS criterion, none of these forms can be categorized as separate species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02438118
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    Paper (German National Licenses)
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