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  • 1985-1989  (6)
  • 1980-1984  (2)
  • 1950-1954  (2)
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  • 1
    Digitale Medien
    Digitale Medien
    Factors influencing particle selection and feeding rate in the polychaete Cistenides (Pectinaria) gouldii (1982)
    Springer
    Marine biology 71 (1982), S. 33-40 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Feeding behavior of the deposit feeding polychaete Cistenides (Pectinaria) gouldii was examined to determine factors affecting particle selection and feeding rate. Worms were found to select large particles preferentially and particle size selection increased with worm size. Particle selection behavior was unaffected by changes in sediment bacterial abundance. Feeding rates were affected by sediment size, bacterial density and worm size. Generally feeding rates increased in sediment containing more food, although the response was worm size specific. When viewed in a theoretical construct these results were inconsistent with predictions of deposit feeder optimal foraging models. Alternative explanations, such as morphological constraints placed upon the polychaete, may explain C. gouldii feeding behavior.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00396990
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  • 2
    Digitale Medien
    Digitale Medien
    Factors regulating population dynamics of the marine bivalve Gemma gemma: intraspecific competition and salinity (1985)
    Springer
    Marine biology 86 (1985), S. 173-182 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A population of Gemma gemma (Totten) was investigated for 6 yr (1978–1983) in Connecticut, USA to determine the relationship between population fluctuations, life tables of successive cohorts and factors affecting life table parameters. Seasonal cycles occurred from 1978–1981. Although density was not abnormally low in summer of 1982, the population declined rapidly thereafter because individuals present during the reproductive season were smaller than the minimal size for reproduction. Forecasts of population size from a time series model based on past densities were compared to forecasts from the intrinsic rates of growth from four separate clam life tables. The latter approach was less precise but more consistent at successfully predicting temporal trends in population abundance. Two factors were identified that potentially controlled population density and structure during the study. Correlational evidence indicated that intraspecific competition between juveniles and adults was intense in 1978 but was reduced during subsequent years. This interaction reduced the size and subsequent fecundity of the young-of-the-year. Correlational evidence also indicated that low salinity in spring of 1978, 1979, 1982 and 1983 reduced juvenile survival, but not that of adults. Qualitative evidence indicated that a third factor, predation, might also have affected G. gemma's population size and structure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00399024
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  • 3
    Digitale Medien
    Digitale Medien
    Morphological divergence of Eastern Pacific and Caribbean isopods: effects of a land barrier and the Panama Canal (1989)
    Springer
    Marine biology 103 (1989), S. 143-152 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The Isthmus of Panama rose approximately 3 million years before the present (mybp) and isolated biotas in the tropical eastern Pacific from those in the Caribbean Sea. Populations that were split by the Isthmus and have evolved in allopatry since that time are known as geminates. The surf zone/beach isopod Excirolana braziliensis Richardson was examined between 1984 and 1989 to test the hypothesis that divergence in geminate isopod morphology has occurred, and that geminate divergence is greater than divergence between local populations from the same coastline. Three morphs of Excirolana braziliensis, one in the Caribbean and two in the eastern Pacific, were discovered using numerical taxonomic methods that adjust for body size. The two Pacific morphs have overlapping large-scale distributions, but those morphs are segregated on a smaller scale by beach. We inferred that one Pacific morph and one Caribbean morph were geminates, based on their relative similarity in shape, their geographical ranges, and natural history information about the organism's dispersal capabilities. The origin of the third morph probably predates the Isthmus of Panama, given its relative dissimilarity from the geminate morphs. The presumed geminates differ primarily with respect to the rostrum, antennae and one male reproductive structure. Divergence between geminates is greater than divergence between local populations of any morph along a coastline. Because only one morph occurs in the Caribbean, that region contains less morphological variation than the eastern Pacific, which contains two morphs. There was weak evidence that some introductions may have taken place in the last century from the Caribbean to the Pacific; however, introductions have not masked the pattern of divergence that has developed over millions of years.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00543341
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  • 4
    Digitale Medien
    Digitale Medien
    Optical probing of comet Halley from the Giotto spacecraft (1986)
    [s.l.] : Nature Publishing Group
    Nature 321 (1986), S. 341-344 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The optical probe experiment2 relies on the fact that \he difference between two consecutive measurements of the spectral radiance is the spatial derivative of the radiance along the line of sight. If one assumes that the coma is optically thin and that steady state is reached between two ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/321341a0
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  • 5
    facet.materialart.
    Unbekannt
    Concerning Allegedly Necessary Nonanalytic Propositions (1951)
    Minneapolis : Periodicals Archive Online (PAO)
    Philosophical Studies. 2 (1951) 17 
    Details
    ISSN: 0031-8116
    Thema: Philosophie
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:6193-1951-002-00-000005
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  • 6
    Digitale Medien
    Digitale Medien
    α 2Macroglobulin-proteinase complexes stimulate prostaglandin E2 synthesis by peritoneal macrophages (1988)
    Springer
    Inflammation research 25 (1988), S. 360-367 
    Details
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract α2Macroglobulin is a proteinase inhibitor which is converted from its native form into an electrophoretically “fast” form by reaction with a proteinase or methylamine. All α2M “fast” forms bind to a specific high-affinity receptor on macrophages. α2M “fast” forms inhibit the interferon-γ (IFN)-induced increase in macrophage Ia expression. This study examined whether α2M-proteinase complexes alter prostaglandin (PG) E2 synthesis, and whether PGE2 mediates α2M “fast” forms effects on macrophage Ia expression. Culture with α2M “fast” forms increased PGE2 accumulation in the medium over control values in a dose-dependent manner. Culture with IFN alone did not increase PGE2 levels, but potentiated the effect of α2M-proteinase complexes on PGE2 levels. Inhibition of PGE2 synthesis did not alter the PGE2 did suppress IFN-induced Ia expression. Thus, α2M-proteinase complexes increase macrophage PGE2 synthesis, but increased synthesis of PGE2 or other cyclooxygenase products is not the mediator of antagonism of IFN-induced Ia expression by α2M-proteinase complexes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01965043
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  • 7
    Digitale Medien
    Digitale Medien
    In vitro modulation of macrophage tumoricidal activity (1980)
    Springer
    Cancer immunology immunotherapy 7 (1980), S. 225-233 
    Details
    ISSN: 1432-0851
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary NaIO4 treatment of mouse adherent peritoneal cells or lymphocyte-free cloned macrophages enhances their cytotoxic and tumoricidal activity. 5×10−3 M NaIO4 treatment of nontumoricidal BCG-activated macrophages renders them completely tumoricidal, whereas the same treatment of stimulated (peptone-normal) macrophages renders them weakly tumoricidal. Addition of LPS in nanogram quantities too low to enhance tumor cell killing by untreated peptone-normal macrophages causes NaIO4-treated peptone-normal macrophages to be maximally tumoricidal. The activating action of NaIO4, MAF, or LPS can be potently, but inconsistently, blocked or reversed by the reducing agent NaBH4 or the aldehyde-reacting agent dimedone. NaIO4 treatment of lymphocyte-free macrophage colonies does not make them cytotoxic, but NaIO4-treated colony macrophages are cytotoxic for tumor cells when cultured in 10 ng/ml LPS (an amount of LPS inadequate to render untreated colony macrophages cytotoxic). Supernatants of NaIO4-treated adherent peritoneal cells contain MAF activity. Thus, the NaIO4-induced enhancement of peritoneal cell tumoricidal activity may result from both direct NaIO4 activating effects on macrophages and indirect NaIO4 effects through NaIO4-induced MAF production.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00205471
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  • 8
    Digitale Medien
    Digitale Medien
    Demographic importance of ecological interactions: how much do statistics tell us? (1986)
    Springer
    Marine biology 93 (1986), S. 305-310 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Many investigators demonstrate the existence of intra- and interspecific interactions through rigorous statistical hypothesis testing. Statistical significance of an interaction, however, does not necessarily imply that it controls a species population size or distribution. Other analytical methods must be used to make these important determinations. This paper demonstrates one method, with an example, to quantify the demographic importance of statistically significant interactions. In our example, some of the statistically significant interactions with the polychaete Clymenella torquata (Leidy) have large impacts on the population growth rate of the bivalve Gemma gemma (Totten), while others do not. This demonstrates the necessity of distinguishing between statistical significance and demographic importance. In some cases, the demographic importance of the same interaction changes through time because of changes in the bivalve's life history. Interactions affecting juvenile bivalves often have a greater demographic importance than those affecting adults; but this is not always the case.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00508268
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  • 9
    Digitale Medien
    Digitale Medien
    Concerning allegedly necessary nonanalytic propositions (1951)
    Springer
    Philosophical studies 2 (1951), S. 17-21 
    Details
    ISSN: 1573-0883
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Philosophie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02199417
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  • 10
    Digitale Medien
    Digitale Medien
    Chemotactic peptide receptor-cytoskeletal interactions and functional correlations in differentiated HL-60 cells and human polymorphonuclear leukocytes (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 141 (1989), S. 119-125 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: We studied the chemotactic peptide receptor/cytoskeletal interactions in HL-60 cells induced to differentiate with different agents and attempted to correlate these observations with the acquisition of different functional responses. Dibutyryl cyclic AMP-treated cells showed rapid superoxide anion production in response to N-formyl-methionyl-leucyl-phenylalanine (FMLP) and slow, sustained response to phorbol myristate acetate (PMA). Retinoic acid-induced cells showed a slow, sustained response to both FMLP and PMA. Interferon-γ-treated cells produced no superoxide anion on stimulation with FMLP, whereas tumor necrosis factor (TNF)-treated cells showed a slight response. Chemotactic peptide receptor association was the same in the HL-60 cells treated with different agents, despite marked differences in the superoxide anion generation and actin polymerization responses to FMLP and PMA in these cells. In mature neutrophils chemotactic peptide receptor association with the cytoskeleton was not affected by either pertussis or cholera toxin. However, both toxins inhibited FMLP-induced actin polymerization and superoxide anion generation. This suggested involvement of a G-protein similar to Gt, rather than Gi or Gs. Neither toxin had any effect on PMA-induced superoxide anion generation. These observations indicate that receptor association with the cytoskeleton may not have a significant role in affecting signal recognition and response. Among the several possible roles suggested, clearance of the occupied receptors may be the most important role of the cytoskeletal association. HL-60 cells induced to differentiate with different agents (because of their varied functional responses) might prove very useful in dissecting the molecular mechanisms regulating stimulus-induced activation of neutrophils.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041410118
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