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  • 1
    Electronic Resource
    Electronic Resource
    Requirements of an Ice Nucleus (1961)
    [s.l.] : Nature Publishing Group
    Nature 192 (1961), S. 448-449 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In what follows we present what we believe to be the first experimental demonstration that ice nuclea-tion is indeed a function of the surface charge of the nucleating substrate. The surface charge of silver iodide particles in contact with an aqueous solution is readily controlled by the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/192448a0
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  • 2
    Electronic Resource
    Electronic Resource
    Relationship between vegetation state and bite dimensions of sheep grazing contrasting plant species and its implications for intake rate and diet selection (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 50 (1995), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: This study used both experimental evidence and a mathematical model to address some differences in interpretation in the literature on the relationship between sward height and the bite dimensions (bite depth, bite area and bite mass) of sheep grazing contrasting vegetation types. Individual non-fasted sheep were released onto small areas (10 × 10m) of white clover (Trifolium repens) and perennial ryegrass (Lolium perenne) and bite dimensions were measured as they grazed across patches (0·7 × 0·7 m) of predetermined sward surface height (SSH). Sward heights were 4, 7, 10, 13 and 16cm for white clover patches and 4, 6, 5, 9, 11·5 and 14cm for ryegrass patches. Four sheep were assigned to each plant species and each sheep grazed one patch of each height (five patches/sheep). Bite depth, bite area and bite mass increased linearly with SSH in both white clover and ryegrass. At a given SSH, bite depth was similar in white clover and ryegrass, but bite area and bite mass were greater in white clover than in ryegrass. The linear relationships observed between bite mass and SSH contrasted with the asymptotic relationships observed in some other studies, but it is suggested that different relationships may arise because of methodological differences between studies. Furthermore, when linear relationships for bite mass were compared with asymptotic relationships for bite mass in a mechanistic model of animals grazing from ryegrass-white clover pastures it was demonstrated that the nature of the relationship had relatively little effect on the relationship between intake rate and SSH. This was because intake rate depended on the fundamental mechanistic relationship between bite mass and prehension bite rate. This relationship meant that the greater bite masses found when linear relationship were assumed were associated with reduced prehension bite rates and thus the effect on intake rate was relatively small. In addition, the predictions of the model regarding the bases of diet selection by animals grazing ryegrass-white clover mixtures were simplified, and stabilized, when linear relationships were assumed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1995.tb02332.x
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  • 3
    Electronic Resource
    Electronic Resource
    The spatial pattern of vegetation in cut and grazed grass/white clover pastures (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 51 (1996), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The spatial patterns of white clover and sward surface height (SSH) that developed In established perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) pastures undercutting lent every 4 weeks to 5 cm) and gracing (continuously grazed with sheep to 5 cm) were measured. While clover cover was recorded in 1000 contiguous 5 × 5-cm quadrats down 50-m permanent transects from early spring to late autumn. Measurements of SSH were made at 10-cm intervals down the same transect. Spatial pattern was analysed using two-term local quadrat variance and patch-gap analysis. At least two scales of spatial pattern existed for white clover when defoliation treatments began. White clover was not distributed at random but found in patches (mean size = 1.1 m) where it was finely intermixed with grass. Patches, separated by gaps (regions of no clover) (mean size = 2.3 m), were in turn aggregated into ‘patches of patches’, separated by larger gaps (mean size = 4.1 m). Under grazing the pattern of patches and gaps did not alter. Under cutting, patch size increased and gap size decreased, explaining in part the greater mass and cover of white clover that arose in cut than grazed swards during the experiment. No new patches of white clover due to seedling establishment or clonal growth were observed in either cut or grazed swards. The intensity of pattern increased in both cut and grazed swards, but the increase was greater m cut swards. The initial single scale of spatial pattern of SSH of tall patches (mean size = 1.2 m) separated by short patches (mean size = 2.7 m) did not change under grazing. SSH became uniform under cutting. It is suggested that the response of plants to selective (spatially heterogeneous) grazing is a crucial factor in the development and maintenance of spatial pattern in grasslands. The importance of spatial pattern to our understanding and interpretation of plant-plant and plant-animal interactions and to the composition of temperate grasslands is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1996.tb02057.x
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  • 4
    Electronic Resource
    Electronic Resource
    Seedling recruitment dynamics of forage and weed species under continuous and rotational sheep grazing in a temperate New Zealand pasture (2005)
    Oxford, UK : Blackwell Science Ltd
    Grass and forage science 60 (2005), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Understanding the grazing conditions under which plant populations are limited by seed availability (seed limitation) is important for devising management schemes that aim to manipulate the establishment of weed and forage species. Seeds of three weed species (Cirsium arvense, C. vulgare and Rumex obtusifolius) and five forage species (Lolium perenne, Lotus uliginosus syn. L. pedunculatus, Paspalum dilatatum, Plantago lanceolata and Trifolium repens) were broadcast sown into L. perenne–T. repens pastures in Manawatu, New Zealand and five sheep-grazing and two slug-grazing (with and without molluscicide) treatments were imposed in a split-plot design. Of the five sheep-grazing treatments, four compared continuous grazing with rotational grazing at intervals of 12, 24 and 36 d in spring, with all four grazed under a common rotation for the remainder of the year. The fifth treatment was continuous grazing all year. Seed sowing increased seedling emergence of C. vulgare, L. perenne, P. lanceolata, R. obtusifolius and T. repens under all sheep- and slug-grazing treatments, with differences in seedling densities persisting for at least 21 months. Seed sowing did not increase seedling densities of C. arvense, L. uliginosus or P. dilatatum. The effects of sheep-grazing management on seedling emergence and survival were uncoupled. For the five seed-limited species, seedling emergence was greater on pastures that were rotationally grazed during spring compared with those that were continuously grazed. However, seedling survival was lower in pastures grazed rotationally during summer, autumn and winter, so that after 21 months seedling numbers were greater on plots that were continuously grazed all year. Exclusion of slugs increased seedling recruitment of T. repens but had no impact on the other species. As weed and forage species responded in a similar way to sheep-grazing management (increased under continuous, decreased under rotational), it is unlikely that the goals of reducing weed invasions and enhancing forage species establishment could be carried out concurrently in established pastures with the same management.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.2005.00467.x
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  • 5
    Electronic Resource
    Electronic Resource
    A simple capillary rise apparatus to measure wettability in metal–ceramic systems (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3839-3843 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An apparatus to measure the wettability parameter using the familiar capillary rise principle for a liquid metal/alloy in contact with a ceramic tube was constructed. The liquid levels outside and inside the capillary tube were measured using acoustic feedback and an electrical continuity technique, respectively. Measurements made by immersing silicon carbide, alumina, and silica tubes in various pure metals and alloys are presented and compared to previously published data in the literature. Reproducible measurements were obtained for nonwetting systems; however, the expected capillary rise was not observed for reaction wetting systems. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145174
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  • 6
    Electronic Resource
    Electronic Resource
    Nucleation of Ice by Mechanical Shock (1969)
    [s.l.] : Nature Publishing Group
    Nature 223 (1969), S. 390-391 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] It seemed to us surprising that shock waves of such low intensity should induce nucleation, although it is known4 that special types of very strong shock waves, with pressures greater than 20 kbar, can cause the reversible freezing of water to ice.VII. We therefore undertook a study of the effect ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/223390a0
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  • 7
    Electronic Resource
    Electronic Resource
    Chemometrics: Experimental design (1996)
    Springer
    Chromatographia 42 (1996), S. 473-473 
    Details
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272142
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  • 8
    Electronic Resource
    Electronic Resource
    Book reviews (1993)
    Springer
    Chromatographia 35 (1993), S. 459-462 
    Details
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278603
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  • 9
    Electronic Resource
    Electronic Resource
    Rodent seed predation and seedling recruitment in mesic grassland (1999)
    Springer
    Oecologia 118 (1999), S. 288-296 
    Details
    ISSN: 1432-1939
    Keywords: Key words Seed density ; Seedling emergence ; Small mammal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seedling recruitment of two grasses (Arrhenatherum elatius and Festuca rubra) and two herbs (Centaurea nigra and Rumex acetosa) was measured in areas with and without rodents to which seeds of each species were sown at three seed densities (1000, 10,000 and 50,000 seeds m−2) in two seasons (spring and autumn 1995). Seed removal was measured for 10-day periods and the fate of seedlings was followed for 15 months after sowing. The proportion of seed removed ranged from 6 to 85% and increased with increasing seed density for each species. Rodents had no effect on seedling emergence or survival in the spring sowing. In the autumn sowing, rodents reduced seedling emergence of all four species sown at 1000 and 10,000 seeds m−2 but had no impact at 50,000 seeds m−2, presumably because of microsite limitation. We suggest the difference between spring and autumn arose because emergence was seed limited in autumn but microsite limited in spring; microsite availability was higher in autumn because a summer drought killed plants, reduced plant biomass and opened up the sward. Fifteen months after the autumn sowing, fewer A. elatius and C. nigra seedlings survived on plots exposed to rodents. This result reflected not only the reduced seedling emergence but also increased seedling mortality (seedling herbivory) in sites exposed to rodents. In contrast, F. rubra and R.acteosa showed density-dependent seedling survival which compensated for initial differences in seedling emergence, so that no effect of rodents remained after 15 months. The results suggest that rodent seed predation and seedling herbivory exert strong effects on seedling recruitment of A.elatius and C. nigra when recruitment conditions are favourable (conditions that lead to high microsite availability) and may contribute to both species being maintained at low densities in the grassland. The results also demonstrate that highly significant impacts of rodent seed predation at the seedling emergence stage can disappear by the time of plant maturation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050729
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  • 10
    Electronic Resource
    Electronic Resource
    Changes in endogenous hormones in apple during bud burst induced by defoliation (1984)
    Springer
    Plant growth regulation 2 (1984), S. 117-134 
    Details
    ISSN: 1573-5087
    Keywords: Abscisic acid ; apple ; bud burst ; cytokinins ; defoliation ; gibberellins ; tropical horticulture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Under the tropical conditions of East Java, terminal buds of apple burst at any time of the year in response to removal of the subtending leaves. Following two such defoliations, two weeks apart on separate trees, there was a decrease in abscisic acid (ABA), a three-fold increase in gibberellin-like substances (GAs) and only a slight increase in cytokinin-like substances (CKs) in the apex tissue of closed buds. These changes preceded bud opening and the associated increases in fresh and dry weight, and may be causally related to bud burst. In open buds (i.e. young expanding leaves) the concentration of CKs was greater, and the concentrations of ABA and GAs less, than the concentrations in closed buds. As the leaves expanded, ABA increased and GAs and CKs decreased in concentration. The decrease in concentration of GAs and CKs, however, was due to the rise in dry weight of the expanding tissue; the amounts of all three hormones (per apex) increased. During bud burst there was a concurrent decrease in the CKs of subtending stems, suggesting a transfer into the expanding bud tissues. Removal of the old leaves by defoliation may remove the source of ABA and allow the amount of GAs in the apex to rise, bud burst following. Stem CKs may be utilized in the expansion of the new leaves in the bursting buds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024860
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