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21.
Dawson GM 《Science (New York, N.Y.)》1899,9(225):592-593
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Experiments in which male sea lions (Zalophus californianus) were removed and reintroduced into a social group demonstrate that barking by larger males restricts movement and barking by other smaller males. Barking and aggression were primarily directed toward animals of most nearly equal size. Two 6-year-olds seeking to establish and maintain territorial status used aggressive tactics similar to those observed in breeding males in the field. 相似文献
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Leland L. Glenna Raymond A. JussaumeJr. Julie C. Dawson 《Agriculture and Human Values》2011,28(2):213-224
Science and technology studies (STS) research challenges the concept of technological determinism by investigating how the
end users of a technology influence that technology’s trajectory. STS critiques of determinism are needed in studies of agricultural
technology. However, we contend that focusing on the agency of end users may mask the role of political-economic factors which
influence technology developments and applications. This paper seeks to mesh STS insights with political-economic perspectives
by accounting for relationships between availability of diverse technologies, variations in political-economic structures,
and farmer interests and characteristics. We present the results of an analysis on the recent development of three wheat varieties:
(a) a wheat variety that was modified genetically to tolerate the herbicide glyphosate, (b) wheat varieties with characteristics
selected to serve specific markets, (c) and emerging research and development of perennial wheat varieties. Using data obtained
through a survey of wheat growers in Washington State, we analyzed whether farmer interest in these three clusters of wheat
varieties was associated with distinct individual characteristics and attitudes and whether those characteristics and attitudes
are consistent with political economic structures. Although our analysis did not allow us to assess the degree of direct influence
that farmers have on the technological development trajectory for these types of wheat, we were able to document variation
in technological alternatives and farmer characteristics related to different political-economic trends. 相似文献
27.
Byun Y Whiteside S Cooksey K Darby D Dawson PL 《Journal of agricultural and food chemistry》2011,59(4):1428-1431
A nanoencapsulation technique was applied to an oxygen-scavenging system, and thermal processing was investigated as an activator to trigger the oxygen-scavenging reaction. α-Tocopherol-loaded polycaprolactone (PCL) nanoparticles (NPs) were prepared using an oil-in-water emulsion solvent evaporation method. The influences of iron(II) chloride, water, and thermal processing on the oxygen-scavenging capability were investigated. NPs without iron(II) chloride, moisture, and thermal processing had no oxygen-scavenging effect. However, the oxygen content (%) in the cup headspace of 20.9% decreased to 20.4% when the oxygen-scavenging system contained NPs, water, and iron(II) chloride. The oxygen content (%) decreased further to 19.5% when water was eliminated from the mixture. In this research, NPs and iron(II) chloride with thermal processing had an oxygen-scavenging capacity of 6.44 cm3 of O2/g and an oxygen-scavenging rate of 0.21 cm3 of O2 g(-1) day(-1). Results indicated that NPs and iron(II) chloride in an oxygen-scavenging system can be used as a heat-activated oxygen scavenger. 相似文献
28.
Parsons BN Williams NJ Pinchbeck GL Christley RM Hart CA Gaskell RM Dawson S 《Veterinary journal (London, England : 1997)》2011,190(2):249-254
Dog ownership is considered a risk factor for campylobacteriosis in humans. This study investigated the prevalence and shedding of Campylobacter spp. in kennelled dogs. Faecal samples (n=399) were collected in longitudinal studies from 52 dogs in two kennels. Campylobacter spp. were isolated using charcoal-based selective agars and direct PCR. The prevalence of Campylobacter spp. in dogs in boarding kennels ranged from 46% (95% CI 22, 72) on entry, to 50% (95% CI 30, 70) overall, and in dogs in 'rescue' kennels from 68% (95% CI 49, 84) on entry to 73% (95%, CI 56, 87) overall. C. upsaliensis was isolated from 62% (95% CI 48, 73) of the dogs, whilst C. jejuni was isolated from 15% (95% CI 7, 26) of animals. The majority of infected dogs entered the kennels already carrying Campylobacter spp., and remained infected throughout their stay. However, in some cases, shedding appeared to commence after kennelling. Given that the prevalence of C. upsaliensis and C. jejuni was relatively high in dogs from both boarding and rescue kennels, such animals may pose a zoonotic risk. 相似文献
29.
Amy M. Treonis Roger Cook Lorna Dawson Susan J. Grayston Tony Mizen 《Biology and Fertility of Soils》2007,43(5):541-548
We studied the effects of the root endoparasitic nematode Heterodera trifolii on rhizodeposition and the root architecture of white clover (Trifolium repens). Rhizosphere solutions were collected from the root systems of plants growing with and without H. trifolii (200 juveniles per inoculated plant) in sand-based microlysimeters. The organic carbon (C) content of these solutions was
analyzed, and they were applied to plant-free soils to investigate microbial responses. Although plant biomass was unaffected
by nematodes, the architecture of the root systems was significantly altered, with a decrease in overall root length and an
increase in the density of lateral branches from the primary root. The presence of nematodes reduced the concentration of
organic compounds in the rhizosphere solutions but only on the final sampling date (75 days). Analysis of microbial signature
phospholipid fatty acids revealed no change in the structure of the microbial communities in soils to which rhizosphere solutions
were applied. However, these microorganisms did respond with changes in substrate utilization patterns (community-level physiological
profiles). Microbes in soils that received rhizosphere solutions from the nematode-infected clover showed lower utilization
of most substrates but higher utilization of oligosugars. These responses appear to be related to changes in roots and rhizodeposition
associated with nematode infection of clover roots. The results of this study suggest that root herbivory can negatively impact
carbon-limited soil microbial communities via changes in root architecture that moderate rhizodeposition. 相似文献
30.
Streptomycete spores germinated most successfully when placed amongst hyphae of fungi that they could subsequently antagonize. The hyphae of many streptomycetes from Picea litter were able to antagonize fungi from the same habitat, but they were less effective against a group of alien fungi. Streptomycete hyphae were shown to be able to grow at the expense of antagonized fungal hyphae which suggested that they were gaining nutrients from the interaction. The fungal-streptomycete interactions were similar to interfungal hyphal interference reactions. No instances of hyphal penetration were recorded. Many bacteria from the H layer were able to lyse dead Streptomycete hyphae and they were shown to be capable of using both dead and living Streptomycete hyphae as a sole C source. Bacteria from the L and F litter layers were less active in these respects. 相似文献