How farmers matter in shaping agricultural technologies: social and structural characteristics of wheat growers and wheat varieties     

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   

α-Tocopherol-loaded Polycaprolactone (PCL) nanoparticles as a heat-activated oxygen scavenger     

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   

Prevalence and shedding patterns of Campylobacter spp. in longitudinal studies of kennelled dogs     

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   

Effects of a plant parasitic nematode (Heterodera trifolii) on clover roots and soil microbial communities     

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   

Interactions between bacteria,streptomycetes and fungi from Picea sitchensis litter     

C.H. Dickinson  D. Dawson  M. Goodfellow 《Soil biology & biochemistry》1981,13(1):65-71

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   

Design,Evaluation and Application of a Continuously Stirred Tank Reactor System for Use in Nitric Acid Air Pollutant Studies     

Padgett  Pamela E.  Bytnerowicz  Andrzej  Dawson  Philip J.  Riechers  George H.  Fitz  Dennis R. 《Water, air, and soil pollution》2004,151(1-4):35-51

Nitric acid (HNO₃) vapor is a significant component of air pollution. Dry deposition of HNO₃ is thought to be a major contributor to terrestrial loading of anthropogenically-derived nitrogen (N), but many questions remain regarding the physico-chemical process of deposition and the biological responses to accumulation of dry-deposited HNO₃ on surfaces. To examine these processes experimentally, a continuously stirred tank reactor (CSTR) fumigation system has been constructed. This system enables simultaneous fumigation at several concentrations in working volumes 1.3 m dia by 1.3 m ht, allowing for simultaneous fumigation of many experimental units. Evaluation of the system indicates that it is appropriate for long-term exposures of several months duration and capable of mimicking patterns of diurnal atmospheric HNO₃ concentrations representative of areas with different levels of pollution.  相似文献   

Studies on the role of feline calicivirus in chronic stomatitis in cats.     

J O Knowles  F McArdle  S Dawson  S D Carter  C J Gaskell  R M Gaskell 《Veterinary microbiology》1991,27(3-4):205-219

Two groups of cats were inoculated oro-nasally with one of two isolates of feline calicivirus (FCV) from clinical cases of chronic stomatitis. All cats developed signs typical of acute FCV infection; namely, ocular and nasal discharge, conjunctivitis, and marked oral ulceration. None of the cats shed virus beyond 28 days. Seronegative control cats were then infected with a lower dose of one isolate, but again only acute signs were seen and no carriers produced. The original cats were then re-infected with the heterologous isolate. As before, only signs of acute disease were seen, but the range of clinical signs and severity was reduced. Virus shedding patterns in one group were similar to those seen originally, but in the other the duration was reduced. No chronic stomatitis developed over the 10 months of the study. Serum virus neutralising and serum and salivary class specific immunoglobulin responses were investigated. Although long-term carriers were not induced, no relationship between cessation of virus shedding in an individual animal and systemic and local antibody responses was seen.  相似文献   

霉菌毒素结合制剂在营养策略中所扮演的角色     

Karl A.Dawson 《中国家禽》2001,23(9):32-35

1 简介霉菌毒素是霉菌代谢的次级产物，这种物质很可能在饲料的制造与贮存过程中污染到饲料。目前已知至少有300种以上霉菌代谢产物会使动物及人类中毒，全世界谷物中有25％受到霉菌毒素的污染，而且达到可量测的浓度。在这些毒素中，已知有很多种物质明显影响动物的健康，对动物生产造成重大影响。2 霉菌毒素的产生在自然状态下霉菌毒素的产生是一个全球性问题，但是世界上某些特定地区霉菌毒素产生的情形比其他地区频繁。在较冷或气候较温和的地区，例如加拿大、美国的北部及多数欧洲国家，黄曲霉毒素并不是主要问题，除了进口的饲料原料…  相似文献   

Oral dermatophilosis in a cat: a case report     

G. J. Baker  R. G. Breeze  Christine O. Dawson 《The Journal of small animal practice》1972,13(11):649-653

An oral lesion in a cat caused by the actinomycete Dermatophilus con-golensis is described. Multiple granulomata were present in biopsy material taken from a tongue lesion. After surgical excision and daily penicillin therapy the condition regressed.
Résumé. Une lésion oralle dans un chat, causée par l'actinomycète Dermatophilus congolensis est décrit. Des granulomes multiples étaient présentes dans la substance de la biopsie, prise de la lésion de la langue. Après l'excision chirurgicale et la thérapie journalière de pénicilline, la condition décroissait.
Zusammenfassung. Man beschreibt eine orale Verletzung in einer Katze, die durch den Strahlenpilz Dermatophilus congolensis , verursachet wird. Die multipelen Granulomata waren im Stoff von der Biopsie, Welches von der Verletzung der Zunge, genommen wird. Der Zustand klang ab, nach der chirurgischen Exicision und nach der täglichen Heilung von Penizillin.  相似文献   

Antibody titres to lamb rotavirus in colostrum and milk of vaccinated ewes.     

P W Wells  D R Snodgrass  J A Herring  A M Dawson 《The Veterinary record》1978,103(3):46-48

Ewes were vaccinated two to three weeks prior to mating with a formalin-treated preparation of lamb rotavirus. The colostrum and milk produced by vaccinated ewes after the subsequent pregnancy were shown to contain significantly higher titres of antibody to the virus than did mammary secretions from non-vaccinates. The virus neutralising antibody activity was associated with IgG in both colostrum and milk. However, IgG concentrations in the mammary secretions of vaccinates and non-vaccinates did not differ. It is suggested that vaccination of the dam may be of value in protecting the suckled neonatal lamb against rotavirus infection.  相似文献