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  • 1
    Electronic Resource
    Electronic Resource
    Yield Constant for Acanthamoeba polyphaga in Batch and Continuous Culture (1981)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 28 (1981), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . A two-stage chemostat modified to accommodate the growth of adhesive organisms was used to determine the yield constant, Y, of a representative soil amoeba, Acanthamoeba polyphaga, utilizing as its prey Pseudomonas paucimobilis. The first stage consisted of a glucose-limited bacterial culture in steady state. The second stage consisted of a simplified predator-prey system, nongrowing bacteria serving as the limiting substrate for amoebae. A refined methodology to more accurately determine Y was developed, and Y for Acanthamoeba polyphaga in batch and continuous culture was determined to be 19.1%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1981.tb05323.x
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  • 2
    Electronic Resource
    Electronic Resource
    Mercantilism Revisited (1980)
    Cambridge : Cambridge University Press
    The @historical journal 23 (1980), S. 773-791 
    Details
    ISSN: 0018-246X
    Source: Cambridge Journals Digital Archives
    Topics: History
    Notes: The intention of this paper is to look at some of the problems which arise in attempts to provide ‘explanations’ of mercantilism and especially its English manifestations. By ‘explanations’ I mean the efforts which some writers have made causally to relate the historical appearance of sets of economic notions or general recommendations on economic policy or even acts of economic policy by the state to particular long-term phenomena of, or trends in, economic history. Historians of economic thought have not generally made such attempts. With a few exceptions they have normally concerned themselves with tracing and analysing the contributions to economic theory made by those labelled as mercantilists. The most extreme case of non-explanation is provided by Eli Heckscher's reiterated contention in his two massive volumes that mercantilism was not to be explained by reference to the economic circumstances of the time; mercantilist policy was not to be seen as ‘the outcome of the economic situation’; mercantilist writers did not construct their system ‘out of any knowledge of reality however derived’. So strongly held an antideterminist fortress, however congenial a haven for some historians of ideas, has given no comfort to other historians – economic or political, Marxist or non-Marxist – who obstinately exhibit empiricist tendencies. Some forays against the fortress have been made. Barry Supple's analysis of English commerce in the early seventeenth century and the resulting presentation of mercantilist thought and policy as ‘the economics of depression’ has passed into the textbooks and achieved the status of an orthodoxy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1017/S0018246X80000016
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  • 3
    Electronic Resource
    Electronic Resource
    Morgan, PaulGrant, E. G.Patten, JohnBeckett, J. V.Wrightson, Keith; Levine, DavidWallerstein, Immanuel: Warwickshire Apprentices in the Stationers' Company of London, 1563–1700A Warwickshire Colliery in the Seventeenth CenturyPre-Industrial England. Geographical EssaysCoal and Tobacco. The Lowthers and the Economic Development of West Cumberland, 1660–1760Poverty and Piety in an English Village: Terling, 1525–1700The Modern World-System. II. Mercantilism and the Consolidation of the European World-Economy, 1600–1750 : Leeds, Dugdale Society, 1978Leeds, Dugdale Society, 1979Folkestone, Dawson, 1979Cambridge, Cambridge University Press, 1981New York, Academic Press, 1979New York, Academic Press, 1980 (1982)
    Cambridge : Cambridge University Press
    The @historical journal 25 (1982), S. 447-455 
    Details
    ISSN: 0018-246X
    Source: Cambridge Journals Digital Archives
    Topics: History
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1017/S0018246X00011663
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of nitrogen and phosphorus on blue grama growth and mycorrhizal infection (1982)
    Springer
    Oecologia 54 (1982), S. 260-265 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The purpose of this study was to examine the growth response of Bouteloua gracilis, with and without the vescular-arbuscular mycorrhiza (VAM), Glomus fasciculatus, to varying levels of phosphorus and nitrogen (as NH + 4 ) and to determine whether nitrogen and phosphorus levels influence VAM establishment. Bouteloua gracilis was grown in 225 g of soil in a factorial experiment combining four levels of ammonium nitrogen (4, 30, 60, and 126 μg/g), four levels of phosphorus (3, 7, 12, and 22 μg/g), and with VAM spores or no spores. Bouteloua gracilis showed enhanced growth with increased nutrients over the entire range of experimental amendments. Shoot nitrogen concentration for all plants ranged from an average of 0.73% at the low amendment level to 1.61% at the high level, whereas shoot total averages ranged from 2.43 mg at the low amendment to 16.4 mg at the high amendment. Mean shoot phosphorus concentrations ranged from 0.109% at the low amendment level to 0.150% at the high amendment, while totals averaged 5.29 mg at the low amendment and 11.8 mg at the high amendment level. Infected plants were consistently smaller than uninfected plants. This reduction was significant at high nitrogen-low phosphorus, where percent infection was highest (71%). At low nitrogen levels, moderate infection (17%) was established at all phosphorus levels. No infection occurred when both nitrogen and phosphorus levels were high. The lack of a positive nutrient or biomass response to VAM establishment is contrary to most published reports, but is similar to a lack of response shown with certain grasses and other plants. It is possible that the parasitic nature of the response to infection represents the early phase of infection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378401
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  • 5
    Electronic Resource
    Electronic Resource
    Mineralization of cellulose in the presence of chitin and assemblages of microflora and fauna in soil (1983)
    Springer
    Oecologia 60 (1983), S. 103-110 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Nitrogen content is an important factor controlling decomposition of resistant substrates. We examined the decomposition of purified cellulose in the presence of a structurally similar, resistant organic N compound, chitin. Carbon-14-labelled cellulose was added to sterile ari-dried sandy loam soil in flasks, half of which were also amended with purified chitin. Grassland soil organisms-a fungus (Fusarium oxysporum) or a bacterium (Flavobacterium sp.) with or without their respective nematode grazers (Aphelenchus avenae or Pelodera sp.) were added to the substrateamended soils, and decomposition was monitored by carbon dioxide evolution and NH 4 + −N mineralization. More 14CO2 was evolved and at a higher rate from the fungal treatment than from the bacterial treatment. Grazing enhanced 14CO2 and total CO2 evolution and NH 4 + −N mineralization in the bacterial treatments and NH 4 + −N mineralization in the fungal treatments. Nitrogen was mineralized both from native organic sources and from chitin. The addition of chitin did not enhance and, in most cases, decreased cellulose decomposition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379327
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  • 6
    Electronic Resource
    Electronic Resource
    Earthworms and enchytraeids in conventional and no-tillage agroecosystems: A biocide approach to assess their role in organic matter breakdown (1990)
    Springer
    Biology and fertility of soils 10 (1990), S. 1-10 
    Details
    ISSN: 1432-0789
    Keywords: Earthworm ; Enchytraeid ; Tillage ; Organic matter ; Biocide ; Agroecosystems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Earthworm and enchytraeid densities and biomass were sampled over an 18-month period in conventional and no-tillage agroecosystems. Overall, earthworm densities and biomass in the no-till system were 70% greater than under conventional tilling, and enchytraeid densities and biomass in the no-till system were 50%–60% greater. To assess the role of annelids in the breakdown of soil organic matter, carbofuran was applied to field enclosures and target (earthworm and enchytraeid biomass, standing stocks of organic matter) and non-target effects (bacteria, fungi, protozoa, nematode and microarthropod densities, litter decay rates, plant biomass) were determined in two 10-month studies. In the winter-fall study, carbofuran reduced the annelid biomass, and total soil organic matter standing stocks were 47% greater under no-till with carbofuran compared to control enclosures. Twelve percent of the difference could have been due to non-target effects of carbofuran, as determined from litterbag decay rates. In the summer-spring study, carbofuran again significantly reduced the annelid biomass, and treated pens in the no-till area had significantly greater standing stocks of fine organic matter (43%–45%). Although the densities of bacteria and nematodes were reduced in carbofuran-treated litterbags under a no-till system, the rates of decay were not reduced and estimates of the amount of organic matter processed could not be adjusted for non-target effects. A 76% difference in the standing stock of coarse organic matter between control and carbofuran-treated pens in the conventional-till system indicated further non-target effects. We concluded that our estimates of the amount of organic matter processed by annelids in no-till and conventionally tilled agroecosystems represented a maximum potential because of the confounding non-target effects of carbofuran.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336117
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  • 7
    Electronic Resource
    Electronic Resource
    The distribution and abundance of soil nematodes in East African savannas (1991)
    Springer
    Biology and fertility of soils 12 (1991), S. 67-72 
    Details
    ISSN: 1432-0789
    Keywords: Nematodes ; Microbivores ; Savannas ; Detrital food webs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nematodes were sampled from sites under and between tree canopies in Tsavo National Park, Kenya. We tested the hypothesis that more nematodes would be present in the generally moister soil, under the canopy, with a larger biomass of green grass prevailing for many months of the year. We found that microbivorous nematodes comprised the bulk of the populations, approximately 90% of the total. Bacterivores were more numerous (approximately 3×105 on average) versus fungivores (approximately 5×104 on average) per m2, to 10 cm depth. All four trophic groups (plant parasites and omnivore/predators in addition to the microbivore groups mentioned above) were significantly higher under acacia than baobab in a drier site, but not significantly different under the two tree species in a wetter site. Only bacterivores were significantly different with respect to distance from the tree, with higher numbers associated with the higher microbial biomasses under the tree canopies. These higher microbial biomasses were reflected in 2.5 times more potentially mineralizable N under the tree canopies at the drier site. We suggest that belowground detrital and microbivorous food webs in savannas may be similar to those in temperate grasslands. Further proof of this idea awaits more extensive research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369390
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  • 8
    Electronic Resource
    Electronic Resource
    Soil biology, soil ecology, and global change (1992)
    Springer
    Biology and fertility of soils 14 (1992), S. 104-111 
    Details
    ISSN: 1432-0789
    Keywords: Global change ; Scaling ; Hierarchies ; Soil organisms ; Soil processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This overview paper addresses aspects of scaling in space and time, and scaling in relation to micro-and macrohabitats. Ecological processes in soils are examined for possible generalizations about processes and organisms, across a wide range of different habitats. Problems of scaling in space and time that have an important impact on processes associated with global change are outlined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336258
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of streptomycin, cycloheximide, Fungizone, captan, carbofuran, cygon, and PCNB on soil microorganisms (1984)
    Springer
    Microbial ecology 10 (1984), S. 345-358 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eight biocides were chosen to determine whether they had any effects on nontarget organisms in soil and to what extent they would reduce their target populations under laboratory experimental conditions. A simplified microcosm system was utilized in which reduced species arrays that included field populations of either only bacteria and fungi, or bacteria, fungi, and protozoa (no nematodes, arthropods, or plants) were inoculated into sterilized soil. In a second set of experiments, plants were grown in sterilized soil. A bactericide-streptomycin-four fungicides-cycloheximide, Fungizone (amphotericin B), captan, and PCNB (quintozene)-an acaricide-cygon-an insecticide-nematicide-carbofuran-and an insecticide-diazinon-were used. Each biocide had effects on nontarget organisms although the increases or decreases, with respect to the control, were of only limited duration. Reductions in target groups were typically of longer duration. Streptomycin, applied at 1 mg·g−1 soil, did not decrease bacterial populations during the experimental incubation. At 3 mg·g−1 soil, streptomycin decreased the numbers of bacteria that grew on tryptone agar, but also reduced active hyphae. Fungizone was the most effective of the 4 fungicides tested in reducing active hyphae. Increased bacterial populations were usually observed following fungal reductions. Carbofuran had the fewest effects on the test organisms (bacteria, fungi, and protozoa). Only an initial stimulation of bacterial and fungal populations was observed with cygon although it also increased NH4 +-N concentrations in soil during most of the incubation, as did streptomycin and cycloheximide. A transitory increase in fungal populations following a decrease in ciliate numbers was observed in the cygon with grazers treatments. Diazinon reduced all microbial populations and inorganic nitrogen concentrations measured. Cygon and PCNB decreased growth of blue grama plants, while streptomycin reduced shoot weights of blue grama. These results should be useful in assessing the effects of these biocides when applied to more complex systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02015559
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of freeze-thaw stress on bacterial populations in soil microcosms (1983)
    Springer
    Microbial ecology 9 (1983), S. 329-340 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To test the effect of freezing on soil biota, isolated from the shortgrass prairie of northeastern Colorado, a series of experiments were performed using gnotobiotic soil microcosms.Pseudomonas paucimobilis was used to examine the effects of freezing on bacteria of different growth stages. Secondly, the effect of multiple freeze-thaw cycles was tested on an assemblage of bacterial species. Lastly, the effect of freezing on predator-prey interactions was studied usingP. paucimobilis and an amoebal predator,Acanthamoeba polyphaga. A temperature of −9°C was not detrimental toP. paucimobilis at any growth stage. A single severe freeze-thaw cycle (−27°C to 23°C) resulted in 40–60% mortality ofP. paucimobilis and the mixed bacteria, although additional freezing events did not reduce the populations further. Multiple freeze-thaw cycles (−9°C to 23°C) gave 40–60% mortality ofP. paucimobilis and the mixed bacteria. Predator-prey population cycles were possibly desynchronized by freeze-thaw events.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02019022
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