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  • 1
    Electronic Resource
    Electronic Resource
    Phase and Triple Point Behaviour in Capillary Confined Co〈sub〉2〈/sub〉 (1994)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 175-178 (Nov. 1994), p. 347-350 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/00/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.175-178.347.pdf
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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    A Comparison of Test Procedures for the Detection of Antibody to Borrelia burgdorferi (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 539 (1988), 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.1749-6632.1988.tb31911.x
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  • 6
    Electronic Resource
    Electronic Resource
    Seaweed-herbivore-predator interactions: host-plant specialization reduces predation on small herbivores (1989)
    Springer
    Oecologia 81 (1989), S. 418-427 
    Details
    ISSN: 1432-1939
    Keywords: Ascoglossans ; Caphyra rotundifrons ; Chemical defense ; Chlorodesmis ; Plant-herbivore-predator interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Because feeding specialization among marine herbivores is rare, marine communities provide a simplified system for identifying factors selecting for specialization. On Australia's Great Barrier Reef, we investigated interactions among the chemically-defended seaweed Chlorodesmis fastigiata, herbivores specialized on this alga, and potential predators of these herbivores. Chlorodesmis is a low preference food for reef fishes but appears to be the only food of the crab Caphyra rotundifrons and the ascoglossan gastropods Elysia sp. and Cyerce nigricans. The crab is found only in patches of Chlorodesmis, feeds solely on the alga, and selectively shelters in it in laboratory choice experiments. Crab grazing on the red seaweed Acanthophora spicifera was stimulated when this alga was coated with increasing concentrations of the cytotoxic diterpenoid chlorodesmin, the major secondary metabolite of Chlorodesmis. Crabs did not sequester Chlorodesmis metabolites but avoided predators by sheltering in the unpalatable alga. All crabs tethered on the reef without access to Chlorodesmis patches were rapidly eaten; those with access to Chlorodesmis patches were much less susceptible to predation. The cryptic ascoglossan Elysia sp. was found exclusively in patches of Chlorodesmis and sequestered metabolites from the alga. Living Elysia were unpalatable to the common wrasse Thalassoma lunare in laboratory assays, but the crude organic extract of Elysia did not significantly deter feeding by Thalassoma. Elysia sequestered chlorodesmin, which deterred feeding by reef fishes in field assays but was ineffective against Thalassoma in laboratory assays at 5% food dry mass. Unlike Elysia, the aposematically colored ascoglossan Cyerce nigricans sequestered Chlorodesmis metabolites in relatively small amounts, but produced larger amounts of unrelated polypropionate compounds. Cyerce were never attacked by fishes and the crude organic extract of this slug strongly deterred feeding by wrasses in laboratory assays. The dorid nudibranch Gymnodoris sp. was found only in Chlorodesmis patches and appeared to be a specialized predator on Elysia; it would not prey on Cyerce. Data from this and other recent investigations demonstrate that some small marine herbivores feed selectively or exclusively on seaweeds that are chemically defended from fishes. This association reduces predation on the herbivores and suggests that escape from and deterrence of predation may be a dominant factor selecting for specialization among these herbivores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377093
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  • 7
    Electronic Resource
    Electronic Resource
    Amphipods on seaweeds: partners or pests? (1990)
    Springer
    Oecologia 83 (1990), S. 267-276 
    Details
    ISSN: 1432-1939
    Keywords: Amphipods ; Ampithoe ; Epiphytes ; Herbivory ; Sargassum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Herbivorous marine amphipods have been implicated as important grazers on filamentous and ephemeral algae, and thus as beneficial to macrophytes in reducing overgrowth by epiphytic competitors. In North Carolina, USA, amphipods comprise 97% of all macroscopic animals inhabiting the abundant brown seaweed Sargassum filipendula, and peak in abundance between late winter and early summer. I used outdoor tank experiments to test the species-specific impact of common phytal amphipods on the growth of Sargassum and its epiphytes. The results show that seaweed-associated amphipods are a trophically diverse group that could either increase or decrease host fitness depending on their feeding preferences. The amphipods Ampithoe marcuzii, Caprella penantis, and Jassa falcata each significantly reduced growth of epiphytes on Sargassum plants relative to amphipod-free controls, while Ericthonius brasiliensis had no significant effect on Sargassum or its epiphytes. However, amphipod grazing was not necessarily beneficial to Sargassum. A. marcuzii consumed Sargassum in one outdoor tank experiment, reducing its mass by 11%, while Sargassum plants without amphipods grew by 81%. Epiphytes (mostly diatoms and the filamentous brown alga Ectocarpus siliculosus) and detritus remained abundant on these plants suggesting that A. marcuzii preferred the host to its epiphytes. Similarly, when given simultaneous access to Sargassum and to several common foliose and filamentous epiphytes in the lab, A. marcuzii ate Sargassum almost exclusively. The other three amphipods ate no macroalgae. In contrast to A. marcuzii, C. penantis consistently reduced epiphytes with no negative effect on Sargassum. Thus the species composition of the amphipod fauna can determine whether these animals increase or decrease seaweed fitness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317764
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  • 8
    Electronic Resource
    Electronic Resource
    Prey nutritional quality and the effectiveness of chemical defenses against tropical reef fishes (1992)
    Springer
    Oecologia 90 (1992), S. 333-339 
    Details
    ISSN: 1432-1939
    Keywords: Chemical defenses ; Coral reefs ; Nutritional quality ; Plant-herbivore interactions ; Predator-prey interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Many coral-reef seaweeds and sessile invertebrates produce both secondary chemicals and mineral or fibrous skeletal materials that can reduce their susceptibility to consumers. Although skeletal materials often have been assumed to function as physical defenses, their deterrent effectiveness may derive from their reduction of prey nutritional quality as well as from noxiousness of the skeletal material itself. To test the relative importance of prey nutritional quality and chemical defenses in susceptibility to predation, we offered reef fishes on Guam a choice of artificial foods varying in nutritional quality (4% versus 22% protein) and in secondary chemistry (spanning approximately natural concentration ranges). Field feeding assays were performed with pachydictyol A from the pantropical brown seaweed genus Dictyota, manoalide from the Micronesian sponge Luffariella variabilis, and a brominated diphenyl ether from the Micronesian sponge Dysidea sp. The results indicated that chemical defenses were less effective in high- than in low-quality foods. In paired assays with metabolite-free controls, all three compounds at natural concentrations significantly reduced feeding by reef fishes only in assays using low-quality food, and not in assays with high-quality food. When fishes were offered an array of artificial foods varying in both food quality and metabolite concentration, food quality significantly affected fish feeding in all three cases, while secondary chemistry was significant in only one. Thus differences in nutritional quality, within the natural range among reef organisms, can be comparable to or greater in importance than secondary chemistry in affecting feeding preferences of their consumers. Reduced nutritional quality may be an important selective advantage of producing indigestible structural materials, in addition to their roles as physical support and defense, in coral reef organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317689
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  • 9
    Electronic Resource
    Electronic Resource
    A comparison of new techniques for the detection and determination of triazine herbicides separated by thin-layer chromatography (1969)
    Springer
    Microchimica acta 57 (1969), S. 480-489 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Flüssigkeits-Szintillationszählung zur Bestimmung von14C-markiertem Ametryn in Dünnschichtchromatogrammen wurde eingehend geprüft. Alterung, Löschungseffekt von Trägersubstanz und Adsorptionsmitteln, Temperaturbeständigkeit der Verbindung in adsorbiertem Zustand wurden untersucht. Die Reproduzierbarkeit beträgt 1 bis 2%, die Nachweisgrenze 0,005μg pro Tüpfel, das Signal-Hintergrund-Verhältnis 3∶1. Zur Lokalisierung der Flecken wurde die Fluoreszenzlöschung herangezogen. Die Ausbeute nach 30 Minuten Entwicklung auf Silikagelplatten war ungefähr 90% Ametryn, unabhängig vom Laufmittel. Bei zweidimensionaler Arbeitsweise wurden 75% wiedergefunden. Die Ausbeute aus Wasser- und Bodenproben lag zwischen 78 und 88%.
    Notes: Summary The use of the liquid scintillation counting method for the determination of14C labelled ametryne on thin-layer chromatograms has been thoroughly investigated. Aging, quenching effect of carrier and adsorbents as well as temperature stability of the compound in the adsorbed state have been studied. The method has a reproducibility of 1 to 2% and a detection limit of 0.005μg per spot at a 3 ∶ 1 signal to background ratio. Fluorescence quenching was used for the location of spots on the chromatogram. Recovery studies were carried out by this method. After 30 minutes development on a chromatoplate coated with silicagel, about 90% of the ametryne was recovered independent of solvent system used. About 75% of the ametryne was recovered from a two-dimensional chromatogram. Recoveries of ametryne from water and soil samples ranged between 78 and 88%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01216449
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  • 10
    Electronic Resource
    Electronic Resource
    Iron toxicity and other chemical soil constraints to rice in highland swamps of Burundi (1994)
    Springer
    Plant and soil 166 (1994), S. 109-115 
    Details
    ISSN: 1573-5036
    Keywords: Fe toxicity ; highland swamp ; Histosol ; Mn ; leaf mineral content ; organic carbon ; peat ; rice ; soil pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Iron toxicity is suspected to be a major nutritional disorder in rice cropping systems established on flooded organic soils that contain reductible iron. A pot trial was carried out to assess Fe toxicity to rice in flooded Burundi highland swamp soils with a wide range of organic carbon contents. Soil and leaf analyses were performed and total grain weight was determined. Clear Fe toxicity was diagnosed, based on leaf Fe content at panicle differentiation. Leaf Fe contents higher than 250 μg g−1 dry matter induced lower Mg (and probably Mn) uptake, and a 50% total grain weight reduction. These features were associated with exchangeable Fe equivalent fractions higher than 86%. Besides, several non-Fe toxic soils exhibited an Mg-Mn imbalance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02185487
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