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  • 1
    Electronic Resource
    Electronic Resource
    Growth and reproductive rates of Littorina rudis from three contrasted shores in North Wales, UK (1980)
    Springer
    Marine biology 58 (1980), S. 47-54 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Data are presented on growth and reproductive rates of Littorina rudis Maton from 3 contrasted habitats: a sheltered saltmarsh, a moderately sheltered boulder shore and an exposed cliff face. Growth was fastest in L. rudis from the moderately sheltered boulder shore, followed closely by snails from the sheltered saltmarsh. Growth was much slower and the asymptotic size much less in L. rudis from the exposed cliff face, this being attributed to the reduced time available for foraging caused by longer and more erratic periods when the substratum dries out. Eggs extracted from the brood chambers of the saltmarsh L. rudis took about 72 d to hatch in the laboratory at 10°C. No seasonal trend was detected in the percentage of sexually mature snails, which fluctuated erratically round about 54 to 99% in each population. Similarly, the ratio of females: males fluctuated erratically about 1.0. The number of eggs and embryos held in the brood chamber peaked in May–June and birth rates (release of young from the brood chamber) peaked in July-August. Following a lull in August, the brood chamber contents were maintained at moderately high levels throughout the winter, whereas the birth rates declined to very low levels. These differences in the seasonal cycle of brood chamber contents and birth rates were probably caused by seasonal differences in embryological development rate and in the propensity of the young to leave the brood chamber. Fecundity increased with parental size and, because of this, the smaller, slower growing exposed-shore L. rudis had much lower potential fecundities than L. rudis from the other shores. However, the size-specific fecundity of the exposedshore L. rudis was about 1.7 times that of L. rudis on the more sheltered shores. This difference was apparently not attributable to smaller young or to a greater capacity of the brood chamber in the exposedshore L. rudis, and must therefore have been caused by higher rates of egg production. 18% of mature females from the boulder shore and 5% of those from the cliff face were oviparous, having a jelly gland in place of the brood chamber.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386879
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  • 2
    Electronic Resource
    Electronic Resource
    Segregational mechanisms of sex chromosomes in megaloptera (Neuropteroidea) (1980)
    Springer
    Chromosoma 81 (1980), S. 307-314 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In male meiocytes of 2 species of the megalopteran family Corydalidae, Corydalus cornutus (L.) (2n=24, comprising 11 pairs of autosomes plus X and Y in the male and 2 Xes in the female) and Neohermes filicornis (Banks) (2n=22, comprising 10 pairs of autosomes plus X and Y in the male and 2 Xes in the female), the sex chromosomes invariably form a bivalent and segregate synchronously with the autosomes. In Neohermes this sex-bivalent is of the parachute type. Absence of autosomal univalents and of the straight-jacket deformation of chromosomes in individual spindle units further distinguishes these megalopteran meiocytes from those of Neuroptera and Raphidioptera previously described. The bearing of these findings on phylogenetic relationships of the recent Orders of the Neuropteroidea is briefly considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00368144
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  • 3
    Electronic Resource
    Electronic Resource
    Transcapillary exchange and retention of fluoride, strontium, EDTA, sucrose, and antipyrine in bone (1980)
    Springer
    Calcified tissue international 31 (1980), S. 173-181 
    Details
    ISSN: 1432-0827
    Keywords: Bone blood flow ; Capillary permeability ; Tracer exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The extractions of85Sr2+,18F−, sucrose-14C, EDTA-51Cr, and antipyrine-14C in bone were determined by the multiple indicator-dilution method. Fluoride and strontium extractions were 18 to 70% during a single transcapillary passage, and those of EDTA and sucrose were from 11 to 59%, whereas extraction of antipyrine was 87%. Injections of85Sr2+ and18F− made when perfusion was done alternately with blood and plasma resulted in similar fractional extractions. When flow and extraction were measured simultaneously, extraction was related inversely to flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02407178
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  • 4
    Electronic Resource
    Electronic Resource
    Persistence of three organophosphorus insecticides in artificial ponds and some biological implications (1980)
    Springer
    Archives of environmental contamination and toxicology 9 (1980), S. 269-279 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract The persistence and biological impact of the organophosphorus insecticides, Abate®, Reldan®, and Dursban®, were studied following the application of 10 ppb to a series of artificial polyethylene-lined ponds and a single natural pond inoculated with leaf litter. Disappearance of the insecticides from water could be described in terms of two phases: early posttreatment, in which rapid partitioning took place; and, a variable time period, characterized by slowly decreasing residues. Of the three pesticides, Dursban was the most persistent followed by Reldan and Abate in that order. The rapid initial disappearance of the pesticides from water was primarily attributable to adsorption on bottom sediments and polyethylene. Polyethylene appeared to have a greater affinity for the pesticides than did the sediments. However, desorption from the polyethylene contributed to residual concentrations in the water of artificial ponds for prolonged periods. Dursban was most toxic to cladoceran and copepod populations. Cladocerans were more sensitive to the three insecticides than were cyclopod and calanoid copepods or copepod nauplii. Chlorophyll concentrations as a measure of algal biomass were always greater in ponds treated with Abate or Dursban than in untreated ponds, supporting the conclusion that algal blooms result from the elimination of Zooplankton predation. It was concluded that in artificial polyethylene-lined ponds residues persisted for longer times than in natural ponds. The resulting prolonged period in which Zooplankton were absent leads to an increased probability of algal blooms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01057407
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  • 5
    Electronic Resource
    Electronic Resource
    Larval competition in serially transferred populations of Drosophila melanogaster (1980)
    Springer
    Oecologia 45 (1980), S. 396-403 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Experiments showed that larval competition for food is not always the result of decreases in the amount of food available per larva as population density increases. The feeding period during which the larvae try to attain the minimum survival weight may be restricted when food quantity is not limiting. The scramble type competition involves both exploitation and interference components, in degrees which vary with population density.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00540213
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  • 6
    Electronic Resource
    Electronic Resource
    Reproductive effort of winkles (Littorina spp.) with contrasted methods of reproduction (1980)
    Springer
    Oecologia 47 (1980), S. 130-136 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Reproductive effort was compared in Littorina rudis (ovoviviparous), L. nigrolineata (benthic eggs with direct development), L. neritoides and L. littorea (planktonic eggs and larvae). Three indices of reproductive effort were used: the proportion of total production committed to reproduction per unit time, the cumulative proportion of total production committed to reproduction up to a given age, and the ratio of reproductive production per unit time to somatic biomass at the beginning of the unit time interval. The indices were plotted against age and the snails ranked in order of their reproductive efforts at equivalent ages. When plotted on axes of absolute time, all three indices ranked the snails in the order L. neritoides〈L. rudis≈L. littorea〈L. nigrolineata. The rank order of reproductive efforts on a time axis standardized for growth rate was L. littorea〈L. rudis〈L. nigrolineata≈L. neritoides, and on a time axis standardized for generation time was L. neritoides≈L. rudis〈L. nigrolineata. The implications and relative merits of the different expressions of reproductive effort are discussed. No general relationship was found between the magnitude of reproductive effort and either reproductive type or population ecology among the Littorina spp., or among other intertidal prosobranchs reviewed from the literature. Semelparous species had among the highest reproductive efforts, but there was no clear separation in this respect from certain iteroparous species. Parental investment, measured as the energy content of an egg plus any accompanying jelly or capsular material, was one to two orders of magnitude greater in the species with direct development than in those with indirect development. There were significant differences between egg and hatchling sizes of L. rudis from three contrasted types of shore and these differences were thought to be correlated with the intensity of desiccation and predation on hatchlings rather than with demographic factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00541788
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of combined nitrogen on anapleurotic carbon assimilation and bleeding sap composition in Phaseolus vulgaris L. (1980)
    Springer
    Planta 148 (1980), S. 338-345 
    Details
    ISSN: 1432-2048
    Keywords: Allantoin ; Amino acids ; Bleeding sap ; Nitrogen fixation ; Phaseolus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dwarf french beans, Phaseolus vulgaris L., were grown with or without inoculation with rhizobia (strain 3644), and with or without a combined nitrogen source (nitrate or ammonium ions). The distribution of radioactivity into products of dark 14CO2 assimilation was studied in roots or nodules from these plants. A detailed study was also made of the distribution and rates of excretion of nitrogen in xylem bleeding sap in 28 day old plants grown on the various sources of nitrogen. Whereas detached nodules accumulated radioactive glycine, serine and glutamate when incubated with 14CO2, bleeding sap from plants root fed 14CO2 contained low levels of radioactivity in these compounds but higher levels in allantoin. Chemical analysis showed allantoin to be the major compound transported in the xylem of nodulated plants, whether or not they were fed on combined nitrogen. In contrast uninoculated plants accumulated mainly amino acids in the bleeding sap, the amount and chemical composition of which depended on the combined nitrogen source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388121
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  • 8
    Electronic Resource
    Electronic Resource
    Reproductive success of screech owls fed Aroclor® 1248 (1980)
    Springer
    Archives of environmental contamination and toxicology 9 (1980), S. 661-665 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Aroclor® 1248 was fed to captive screech owls (Otus asio) at the rate of three ppm in the diet to determine if reproductive effects such as fewer eggs per clutch, lower hatchability, malformation of the chicks, or higher mortality rates of chicks would appear in this raptorial species as they did in chickens. There were no effects on eggshell thickness, number of eggs laid, young hatched, and young fledged from feeding a low level of Aroclor® 1248 to captive screech owls. The polychlorinated biphenyl (PCB) residues found in the eggs of the dosed birds ranged from 3.9 ppm to 17.8 ppm. Background PCB residues in the diet of all experimental birds ranged from non-detected to 0.62 ppm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01055541
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  • 9
    Electronic Resource
    Electronic Resource
    Book reviews (1980)
    Springer
    Human ecology 8 (1980), S. 295-310 
    Details
    ISSN: 1572-9915
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Ethnic Sciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01561029
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  • 10
    Electronic Resource
    Electronic Resource
    A theoretical model of the manfacture of reaction-bonded silicon nitride with particular emphasis on the effect of ambient reaction temperature and compact size (1980)
    Springer
    Journal of materials science 15 (1980), S. 2345-2353 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An analysis of the exothermic, irreversible silicon-nitrogen reaction, based on the particle-pellet model, is presented using mixed type boundary conditions to represent external resistances. The mathematical model incorporates a sharp ″cut-off″ in the reaction and takes into account its transient behaviour. The resulting system of partial differential equations is solved numerically using an explicit finite difference scheme. The effects of varying the ambient reaction temperature and compact size on the temperature distribution inside the nitriding compact and on the solid product formation rate, are examined. The results obtained are in acceptable agreement with previous experimental research by other workers, which illustrates how the model adequately represents the silicon-nitrogen reaction. An investigatory report on the validity of the Arrhenius equation for determining the thermal activation energy of this reaction is also presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00552327
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