Phenology of the Diamondback moth (Plutella xylostella) in the UK and provision of decision support for brassica growers

In the UK, severe infestations by Plutella xylostella occur sporadically and are due mainly to the immigration of moths. The aim of this study was to develop a more detailed understanding of the phenology of P. xylostella in the UK and investigate methods of monitoring moth activity, with the aim of providing warnings to growers. Plutella xylostella was monitored using pheromone traps, by counting immature stages on plants, and by accessing citizen science data (records of sightings of moths) from websites and Twitter. The likely origin of migrant moths was investigated by analysing historical weather data. The study confirmed that P. xylostella is a sporadic but important pest, and that very large numbers of moths can arrive suddenly, most often in early summer. Their immediate sources are countries in the western part of continental Europe. A network of pheromone traps, each containing a small camera sending images to a website, to monitor P. xylostella remotely provided accessible and timely information, but the particular system tested did not appear to catch many moths. In another approach, sightings by citizen scientists were summarised on a web page. These were accessed regularly by growers and, at present, this approach appears to be the most effective way of providing timely warnings

Suppressing higher aims? Buried institutional logics resurface in public service broadcasting in Zimbabwe, 1970-2008

Zimbabwe Broadcasting Corporation operates in a complex institutional environment, with contestation over logics – some idealised, others cynical – about what it means to be a public service broadcaster. This paper draws upon the institutional logics perspective to analyse secondary data source for signs about how institutional logics might help to explain the curious, periodic resurfacing of ideals of independence, drawn in part from the legacy of its roots in the logics of public service broadcasting developed in the BBC and not always enacted the ideals would have it

Hazard analysis and critical control point (HACCP) in seafood processing: an analysis of its application and use in regulation in the Sultanate of Oman

When considering the supply of fish products to consumers, the adoption of food safety management systems throughout the 'net to plate' continuum is of a paramount importance. It is essential to safeguard consumers and to facilitate regional and international trade. This study has assessed the technical barriers and benefits associated with the implementation of management system incorporating HACCP and related pre-requisite programmes in the seafood processors in the Sultanate of Oman. A survey, using qualitative surveys and interviews, was conducted out to verify the level of implementation of the seafood safety and quality requirements. A total of 22 (92% returned) HACCP processors, and 15 (83% returned) non-HACCP processors and 15 (75%) officials completed the questionnaires. Differences between processors operating with or without a HACCP system in place have been identified. The survey of local officials provided an additional perspective on the issues involved. The implications of handling practices in the seafood supply chain, seafood trade and the cost implications of implementing HACCP-based food safety management systems were also assessed. In comparison to the non-HACCP processors, the results indicated that HACCP firms were more diversified in their export markets and were able to target the more lucrative markets such as EU, Japan and America. However, the processors felt that the main barrier for exporting to these markets was the restriction imposed by the government on exporting certain species which reduced their ability to meet contracts with these countries. The study has also shown inadequate execution of prerequisite programmes due mainly to lack of training delivered to food handlers and a poor knowledge of food safety concepts. In particular there is an overreliance on the use of CCPs to control hazards when prerequisite programmes would be more appropriate is many situations. When considering whether to implement HACCP-based control systems, the seafood processors identified barriers linked to costs as their main concerns. However, whilst recognising this issue, the officials also highlighted barriers linked to the lack of expertise, skills and commitment of the staff. In general, the study highlighted significant gaps which undermine the effectiveness and success of implementing safety and quality requirements to meet national legislative obligations. These include: poor attitudes and understanding toward HACCP and its pre-requisite programmes, lenient enforcement by the authorities, the lack of training and consultancy organizations in the country, a lack of awareness. The overlapping structure of the regulatory authorities in the country and the distribution of national inspection resources have also been identified as an issue of concern

Soft topographic map for clustering and classification of bacteria

In this work a new method for clustering and building a topographic representation of a bacteria taxonomy is presented. The method is based on the analysis of stable parts of the genome, the so-called “housekeeping genes”. The proposed method generates topographic maps of the bacteria taxonomy, where relations among different type strains can be visually inspected and verified. Two well known DNA alignement algorithms are applied to the genomic sequences. Topographic maps are optimized to represent the similarity among the sequences according to their evolutionary distances. The experimental analysis is carried out on 147 type strains of the Gammaprotebacteria class by means of the 16S rRNA housekeeping gene. Complete sequences of the gene have been retrieved from the NCBI public database. In the experimental tests the maps show clusters of homologous type strains and present some singular cases potentially due to incorrect classification or erroneous annotations in the database

Maximum principle and mutation thresholds for four-letter sequence evolution

A four-state mutation-selection model for the evolution of populations of DNA-sequences is investigated with particular interest in the phenomenon of error thresholds. The mutation model considered is the Kimura 3ST mutation scheme, fitness functions, which determine the selection process, come from the permutation-invariant class. Error thresholds can be found for various fitness functions, the phase diagrams are more interesting than for equivalent two-state models. Results for (small) finite sequence lengths are compared with those for infinite sequence length, obtained via a maximum principle that is equivalent to the principle of minimal free energy in physics.Comment: 25 pages, 16 figure

Active flow control systems architectures for civil transport aircraft

Copyright @ 2010 American Institute of Aeronautics and AstronauticsThis paper considers the effect of choice of actuator technology and associated power systems architecture on the mass cost and power consumption of implementing active flow control systems on civil transport aircraft. The research method is based on the use of a mass model that includes a mass due to systems hardware and a mass due to the system energy usage. An Airbus A320 aircraft wing is used as a case-study application. The mass model parameters are based on first-principle physical analysis of electric and pneumatic power systems combined with empirical data on system hardware from existing equipment suppliers. Flow control methods include direct fluidic, electromechanical-fluidic, and electrofluidic actuator technologies. The mass cost of electrical power distribution is shown to be considerably less than that for pneumatic systems; however, this advantage is reduced by the requirement for relatively heavy electrical power management and conversion systems. A tradeoff exists between system power efficiency and the system hardware mass required to achieve this efficiency. For short-duration operation the flow control solution is driven toward lighter but less power-efficient systems, whereas for long-duration operation there is benefit in considering heavier but more efficient systems. It is estimated that a practical electromechanical-fluidic system for flow separation control may have a mass up to 40% of the slat mass for a leading-edge application and 5% of flap mass for a trailing-edge application.This work is funded by the Sixth European Union Framework Programme as part of the AVERT project (Contract No. AST5-CT-2006-030914

Stops making sense: translational trade-offs and stop codon reassignment

Background Efficient gene expression involves a trade-off between (i) premature termination of protein synthesis; and (ii) readthrough, where the ribosome fails to dissociate at the terminal stop. Sense codons that are similar in sequence to stop codons are more susceptible to nonsense mutation, and are also likely to be more susceptible to transcriptional or translational errors causing premature termination. We therefore expect this trade-off to be influenced by the number of stop codons in the genetic code. Although genetic codes are highly constrained, stop codon number appears to be their most volatile feature. Results In the human genome, codons readily mutable to stops are underrepresented in coding sequences. We construct a simple mathematical model based on the relative likelihoods of premature termination and readthrough. When readthrough occurs, the resultant protein has a tail of amino acid residues incorrectly added to the C-terminus. Our results depend strongly on the number of stop codons in the genetic code. When the code has more stop codons, premature termination is relatively more likely, particularly for longer genes. When the code has fewer stop codons, the length of the tail added by readthrough will, on average, be longer, and thus more deleterious. Comparative analysis of taxa with a range of stop codon numbers suggests that genomes whose code includes more stop codons have shorter coding sequences. Conclusions We suggest that the differing trade-offs presented by alternative genetic codes may result in differences in genome structure. More speculatively, multiple stop codons may mitigate readthrough, counteracting the disadvantage of a higher rate of nonsense mutation. This could help explain the puzzling overrepresentation of stop codons in the canonical genetic code and most variants