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An assay was developed for the specific detection of Salmonella enterica serotype Enteritidis, using a novel application of the polymerase chain reaction (PCR). This PCR assay is based on the mismatch amplification mutation assay, an allele-specific reaction, and can discriminate Enteritidis from all other salmonella. PCR primers were selected to amplify a 351-base pair (bp) DNA fragment from the salmonella plasmid virulence A (spv A) gene of Enteritidis. A single base difference at position 272 is present between the nucleotide sequence of the spvA gene of Enteritidis and other salmonellae. The downstream PCR primer, that encompasses position 272 of the Enteritidis spvA gene, was designed to contain a single base mismatch at the penultimate position, resulting in a 1-base mismatch with Enteritidis and a 2-base mismatch with other salmonellae that harbour the virulence plasmid. The upstream primer was completely homologous with the region immediately 5' to the spvA gene. When these primers were used and the annealing and extension reactions were performed at the same temperature, the PCR assay was specific for Enteritidis; no PCR product was detected for 40 other serotypes and 28 different genera examined. In pure culture, 120 colony forming units (c.f.u.) could be detected; a PCR product was observed from template derived from a 5 h enrichment broth culture of chicken seeded with 1 c.f.u. per gram of Enteritidis. This PCR assay is specific, reproducible, and less time consuming than the standard bacteriological methods used to detect Enteritidis.  相似文献   
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Multimedia delivery in mobile multiaccess network environments has emerged as a key area within the future Internet research domain. When network heterogeneity is coupled with the proliferation of multiaccess capabilities in mobile handheld devices, one can expect many new avenues for developing novel services and applications. New mechanisms for audio/video delivery over multiaccess networks will define the next generation of major distribution technologies, but will require significantly more information to operate according to their best potential. In this paper we present and evaluate a distributed information service, which can enhance media delivery over such multiaccess networks. We describe the proposed information service, which is built upon the new distributed control and management framework (DCMF) and the mobility management triggering functionality (TRG). We use a testbed which includes 3G/HSPA, WLAN and WiMAX network accesses to evaluate our proposed architecture and present results that demonstrate its value in enhancing video delivery and minimizing service disruption in an involved scenario.  相似文献   
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Quantitative studies of the relationships between river water quality and environmental variables are needed to improve understanding of the impacts of natural and human factors on aquatic environments. However, multicollinearity between environmental variables can hinder the identification of key factors when water quality–environment relationship is studied using traditional regression methods. This study utilized two alternative statistical methods, variation and hierarchical partitioning, to address these difficulties in studies of river water quality. Using these methods, we explored the effects of catchment physiography, climate and land use variables on total phosphorus and nitrogen, pH, water colour and dissolved oxygen during the years 1995–2005 in 32 boreal rivers in Finland. Catchment physiography and land use explained most of the variation in water quality, especially in phosphorus, nitrogen and water colour data. The strong correlations (rs > 0.8) between agricultural land use and phosphorus and nitrogen concentrations indicate that water quality is highly affected by agriculture in boreal regions. By determining the environmental drivers of different water quality variables, we can estimate the water quality of different catchments in response to environmental changes and identify areas that are sensitive to global changes. Our study shows that novel statistical methods integrated with geographic information system data and techniques provide deeper insights into water quality–environment relationships than traditional regression, and these should be considered when developing, for example, conservation planning for rivers. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
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In transitioning to a renewable material-based bio economy, growing public and industry interest is apparent for using wooden multistory construction (WMC) as a sustainable urban housing solution in Europe, but its business implications are not well understood. In our study, we evaluate, which internal and external factors of competitiveness are shaping the future of WMC, especially in the context of Finland and Sweden. Based on a multi-level perspective of socio-technical transitions, we conducted a three-stage dissensus-based Delphi study. The identified internal and external factors affecting the future competitiveness of the WMC business emphasize the importance of skilled architects and builders and the role of standardized building systems. Based on our results, the key aspects influencing the future competitiveness of WMC in the region are related to the development of technical infrastructure and project-based business networks, while additional changes in regulatory framework are perceived as less important. We conclude that towards 2030, the strong cognitive rules founded in the concrete-based building culture in these countries is likely to inhibit the dynamics of the socio-technical regime level. A change is also needed in the WMC business culture towards more open cross-sectoral collaboration and new business networks between different-sized players.  相似文献   
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A new tripodal imine ligand tris(2-(propan-2-ylideneamino)ethyl)amine (imine3tren) was prepared in order to stabilize high valent iron-oxido complexes. Iron complexes were synthesized in template reactions from iron(II) salts, tris(2-aminoethyl)amine (tren) and acetone. Due to the reversibility of the imine formation, complexes with different ligands were obtained depending on the reaction conditions. Three complexes, [Fe(imine3tren)(OAc)2] ( 1 ), [Fe(imine3tren)(OAc)]OTf ( 2 ) and [(imine3tren)2Fe2(F)2](SbF6)2 ( 3 ), could be synthesized and structurally characterized. However, reactions with hydrogen peroxide, iodosobenzene or ozone did not lead to any kind of “oxygen adduct” complex that could be spectroscopically observed.  相似文献   
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Urgent protective measures for the possibly affected population in the pre-release and release phase of a nuclear accident are decided upon and implemented by civil protection authorities on regional and local level. The responsible officers of these authorities are experienced in emergency response, but not in radiological questions. Their radiological advisors, on the other hand, mostly coming from surveillance agencies, often lack knowledge about conditions framing practical response measures. Moreover, although the scientific basis of protective measures is unquestionable, implementation policies are widely different in different countries and render co-ordination of response in border areas difficult. Finally, decreasing availability of funds sharpens the already existing problems due to diminishing interest of young scientists in radiation protection. Measures to improve upon the situation and prerequisite conditions will be discussed.  相似文献   
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4groups of Ss, scoring in the extremes of Neuroticism and Extraversion scales, participated in 3 sessions of 100 learning and 25 extinction trials of timing behavior. ? of the Ss of each group took a placebo at Session 2, the other ? at Session 3. A repeated measurement, 2 X 2 Latin square design, was incorporated. Accuracy was significantly greater for Low than High neurotics during reinforcement trials. Accuracy significantly decreased for High neurotic introverts and increased for the High neurotic extraverts, and Low neurotic introverts and extraverts groups. Under placebo conditions, introverts' accuracy was significantly greater than extraverts'. High neurotic introverts were considered positive placebo reactors, and High neurotic extraverts were negative placebo reactors. (22 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
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Accurate measurement of the perceived quality of audio–visual services at the end-user is becoming a crucial issue in digital applications due to the growing demand for compression and transmission of audio–visual services over communication networks. Content providers strive to offer the best quality of experience for customers linked to their different quality of service (QoS) solutions. Therefore, developing accurate, perceptual-based quality metrics is a key requirement in multimedia services. In this paper, we survey state-of-the-art signal-driven perceptual audio and video quality assessment methods independently, and investigate relevant issues in developing joint audio–visual quality metrics. Experiments with respect to subjective quality results have been conducted for analyzing and comparing the performance of the quality metrics. We consider emerging trends in audio–visual quality assessment, and propose feasible solutions for future work in perceptual-based audio–visual quality metrics.  相似文献   
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