Development and implementation of a rapid real-time polymerase chain reaction assay for the detection of toxigenic Vibrio cholerae in water

Assays which use real-time polymerase chain reaction (PCR) technology can be developed for the rapid identification of genetic sequences carried by waterborne pathogens. Rand Water has established facilities within which a selection of PCR assays will be developed. This paper reports on the optimisation and validation of the first assay to be implemented. This assay facilitates the detection of the ctxA gene of toxigenic Vibrio cholerae (V. cholerae) strains. The assay also includes an internal process control in the form of an Escherichia coli (E. coli) strain carrying a single genomic copy of the gfp gene from Aequorea victoria. Establishment of the assay required the selection of suitable PCR primers and probes for both the ctxA and gfp genes. This was followed by an optimisation phase where ideal PCR cycling conditions and primer/probe concentrations were established. A validation phase established the performance parameters of the assay. Parameters assessed included: limit of detection, sensitivity, specificity, reproducibility and robustness. The validation was conducted using potable water, surface water and sewage effluent matrices. The process has resulted in the establishment of a robust assay for the detection of toxigenic V. cholerae strains within 24 hours after samples are received.Keywords: real-time PCR, Vibrio cholerae O1, ctxA gene, validatio

Factors Influencing Trust-Supporting Mechanisms in European Agri-Food Chains

The role of trust in eight selected agri-food chains in four EU countries is explored. The empirical analysis is based on a qualitative assessment of 28 expert interviews conducted in summer/autumn 2005. The findings suggest that trust is more pronounced among SMEs which are characterised by the existence of personal relationships between business partners. However, as is clear for pork breeders, if a source of distrust exists, trust may not fully develop. Also, if the general economic situation is difficult, the development of trust may be hampered, because all chain participants are struggling to command a share of a diminishing margin within the chain. Finally, if economic power is distributed unevenly, as is the case in Germany, Ireland, Spain and the UK where retailers dominate most chains, trust towards the more powerful may be limited.trust, economic relationships, EU, agri-food chains, Agribusiness,

Use of molecular genetics and historical records to reconstruct the history of local communities

Recent advances in molecular genetics made the inference of past demographic events through the analysis of gene pools from modern populations possible. The technology uses genetic markers toprovide previously unavailable resolution into questions of human evolution, migration and the historical relationship of separated human populations. Some of the genetic markers used to measurevariation (polymorphism) within populations are found in the Y-chromosome and mitochondrial DNA. Variations in these two types of DNA can be grouped into continent-specific haplogroups or lineages.Geographic origin can be assigned to each lineage, and consequently trace back migration pattern of human populations. Y-chromosome and mitochondrial DNA are used to construct paternal and maternal lineages respectively. The use of these molecular techniques together with historical records in an integrated manner can greatly benefit the study of the social history of admixed communities, such as the Cape Muslim community living in the Western Cape of South Africa

Agri-food chain relationships in Europe – empirical evidence and implications for sector competitiveness

The roles of business relationships in selected European agri-food chains are analysed. Using survey data from 1,442 farmers, food processors and retailers in two commodity sectors (meat and cereals) and across six different EU countries, we test the empirical relevance of several theory-based determinants influencing the choice of relationship type and the sustainability of inter-enterprise relationships. This is undertaken for the overall dataset and separately for different chain stages (farmer-processor versus the processor-retailer relationships), commodities and individual countries. Overall, we find that sector and enterprise-specific determinants seem to influence the choice of a certain relationship type while chain-internal, dyadic factors affect the sustainability of relationships. A logistic regression analysis reveals that the preference for a relationship type, while being highly chain-specific, depends on the long-term orientation and the strive for independence of an enterprise and the product-quality requirements within a corresponding market. As for the sustainability of the analysed relationships, structural equation modelling results suggest that its most important determinant is effective communication, with its two components, adequate communication frequency and high information quality, being equally important. The existence of personal bonds and an equal power distribution between buyers and suppliers are the second most important determinants, followed by the negative impact of key staff leaving. The analysis also reveals that the relative importance of these determinants differs significantly across the two considered chain stages and between the countries investigated. Agribusiness managers, seeking to improve their supplier or buyer relationships, need to consider the crucial role of effective communication and the positive contribution that the existence of personal bonds can make to the development and maintenance of sustainable interactions.business relationships, agri-food chains, competitiveness, Agribusiness,

Inland extent of the Weddell Sea Rift imaged by new aerogeophysical data

Peer reviewedPostprin

Structure and evolution of Cenozoic arc magmatism on the Antarctic Peninsula: a high resolution aeromagnetic perspective

The Antarctic Peninsula (AP) consists of a long lived and uniquely well preserved magmatic arc system. The broad tectonic structure of the AP arc is well understood. However, magmatic processes occurring along the arc are only constrained by regional geophysical and relatively sparse geological data. Key questions remain about the timing, volume, and structural controls on magma emplacement. We present new high resolution aeromagnetic data across Adelaide Island, on the western margin of the AP revealing the complex structure of the AP arc/forearc boundary. Using digital enhancement, 2-D modelling and 3-D inversion we constrain the form of the magnetic sources at the arc/forearc boundary. Our interpretation of these magnetic data, guided by geological evidence and new zircon U-Pb dating, suggests significant Palaeogene to Neogene magmatism formed ∼25 per cent of the upper crust in this region (∼7500 km3). Significant structural control on Neogene magma emplacement along the arc/forearc boundary is also revealed. We hypothesize that this Neogene magmatism reflects mantle return flow through a slab window generated by Late Palaeogene cessation of subduction south of Adelaide Island. This mantle process may have affected the final stages of arc magmatism along the AP margin

Please mind the gap: students’ perspectives of the transition in academic skills between A-level and degree level geography

This paper explores first-year undergraduates’ perceptions of the transition from studying geography at pre-university level to studying for a degree. This move is the largest step students make in their education, and the debate about it in the UK has been reignited due to the government’s planned changes to A-level geography. However, missing from most of this debate is an appreciation of the way in which geography students themselves perceive their transition to university. This paper begins to rectify this absence. Using student insights, we show that their main concern is acquiring the higher level skills required for university learning

Canadian clinical guidelines for periodic eye examinations in children aged 0-5 years: Have we got it right?

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Students’ Perceptions of Learning Processes as Co-Authors of Digital Tabletop Activities

We conducted a small-scale study in order to explore students’ perceptions of the learning processes when engaged as co-authors of content for collaborative higher order thinking skills learning tasks. We specifically designed the process to allow for self-critique – where authors can observe their creations being solved and therefore understand where they may improve their design. We collected data over a three-day period from a sample of twelve thirteen year olds, working in teams, authoring content for Digital Mysteries (a higher order thinking skills collaborative learning application based on the digital tabletop). The study was structured to follow Bloom’s taxonomy, a continuum of cognitive skills that develop during a learning process. We found that 1) rather than follow this continuum, skills developed in a non-linear manner due to the abstract nature of the authoring activity, and 2) the students’ demonstrated good metacognitive insights into the authoring task, technology and collaborative learning as a whole

Benefit of an electronic head‐mounted low vision aid

Purpose: To evaluate the efficacy of electronic head-mounted low vision aid (e-LVA) SightPlus (GiveVision, UK, givevision.net) and to determine which people with low vision would see themselves likely using an e-LVA like this. Methods: Sixty participants with low vision aged 18 to 93 used SightPlus during an in-clinic study session based on a mixed methods design. Visual acuity (ETDRS), contrast sensitivity (Pelli-Robson) and reading performance (MNREAD) were measured binocularly at baseline (no device), with the device in ‘normal’ mode (zoom only), and with preferred enhanced mode (zoom and one of four digital image enhancements). At the end of the session, a short questionnaire recorded willingness to use an e-LVA like SightPlus, potential use cases, positive/negative comments and adverse effects. Results: Binocular distance visual acuity improved significantly by 0.63 logMAR on average (p < 0.0001) to 0.20 logMAR. Contrast sensitivity improved significantly by 0.22 log units (p < 0.0001) to 1.21 log units with zoom only and by 0.40 log units to 1.37 log units with zoom and preferred image enhancement. Reading performance improved significantly for near visual acuity and critical print size (p < 0.015), although reading speed significantly decreased (p < 0.0001). Nearly half (47%) of the participants indicated they would use an e-LVA like SightPlus, especially for television, reading and entertainment (e.g. theatre). Multivariate logistic regression showed that proportion of lifetime affected by sight loss, baseline contrast sensitivity and use of electronic LVAs explained 41% of the variation in willingness to use. Conclusions: SightPlus improves visual function in people with low vision and would be used in its current form by one half of the people who tried it. Adverse effects were infrequent and resolved when the device was removed. Future work should focus on comparing e-LVAs through repeatable real-world tasks and impact on quality of life