SCIENTIFIC trials can be cumbersome and lengthy, while exploratory, farm-based ‘trials’ lack scientific rigour but can be done quickly and cheaply. This paper debates the usefulness of exploratory ‘trials’. Six exploratory ‘trials ’ were established on sugarcane farms between 2004 and 2006 to screen various crops for their suitability as green manures. These ‘trials ’ were not replicated, and they did not pass through the usual research pathway; but most were carried out on working farms, in collaboration with growers. The authors examined these ‘trials ’ to determine whether they have a place in an agricultural research institute’s program of work. The exploratory ‘trials ’ helped to achieve a number of things. A small minimum till planter was field-tested for its suitability for planting trials, and its advantages and limitations were identified. Various green manure crops showed promise in different geographical areas, including irrigated areas where little trial work had previously been conducted. ‘New ’ crops included velvet beans, which had not been available for many years beforehand. Two growers’ days with field visits to the ‘trials ’ helped to transfer the lessons learned. These

Abstract. From 2007 through 2009, The Netherlands faced large outbreaks of human Q fever. Control measures focused primarily on dairy goat farms because these were implicated as the main source of infection for the surrounding population. However, in other countries, outbreaks have mainly been associated with non-dairy sheep and The Netherlands has many more sheep than goats. Therefore, a public discussion arose about the possible role of non-dairy (meat) sheep in the outbreaks. To inform decision makers about the relative importance of different infection sources, we developed accurate and high-resolution incidence maps for detection of Q fever hot spots. In the high incidence area in the south of the country, full postal codes of notified Q fever patients with onset of illness in 2009, were georeferenced. Q fever cases (n = 1,740) were treated as a spatial point process. A 500 x 500 m grid was imposed over the area of interest. The number of cases and the population number were counted in each cell. The number of cases was modelled as an inhomogeneous Poisson process where the underlying incidence was estimated by 2-dimensional P-spline smoothing. Modelling of numbers of Q fever cases based on residential addresses and population size produced smooth incidence maps that clearly showed Q fever hotspots around infected dairy goat farms. No such increased incidence was noted around infected meat sheep farms. We conclude

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outcomes associated with routine, repetitive jobs. The theory offers less guidance for the design of work that will elicit and maintain positive and self-reinforcing work motivation. Socio-technical systems theory. The socio-technical systems approach to work redesign provides significant insight

If a school-age child contracts dengue in rural Thailand, it is difficult to predict whether that child was infected at home, at school, or somewhere else. Therefore it is difficult to know how best to allocate scarce resources towards public health measures to reduce the chance of further infections. However, the potential for transmission at home relative to the potential at school must depend mainly on two features of those settings: (1) the density of effective vectors compared with the human population, and (2) the previous infection history of the human population. Unfortunately, despite the wealth of knowledge that is available on many detailed aspects of the biology of dengue, firm ecological evidence with which to estimate key public health outcomes (such as the relative risk of transmission in different settings) remains surprisingly scarce. A prospective spatial cluster study of dengue transmission in rural Thailand by Mammen P. Mammen and colleagues reported in this issue of PLoS Medicine represents an important step forward in addressing this shortfall [1]. The global impact of dengue grew dramatically over the latter part of the 20th century, with the annual incidence currently estimated to be 50 million cases of dengue fever and 500,000 hospitalizations due to dengue hemorrhagic fever [2]. The pathogen is found throughout the tropics and subtropics (almost everywhere that viable vectors are found), with 2.5 billion people thought to be at risk [3]. No safe effective vaccine is currently available to prevent dengue infections. Therefore, public health strategies to reduce the adverse effects of the virus The Perspective section is for experts to discuss the clinical practice or public health implications of a published article that is freely available online.

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valuable insights.

The study of the web as a graph is not only fascinating in its own right, but also yields valuable insight into web algorithms for crawling, searching and community discovery, and the sociological phenomena which characterize its evolution. We report on experiments on local and global properties

statistical properties of requests and their relationship with video age, and the level of content aliasing or of illegal content in the system. We also provide insights on the potential for more efficient UGC VoD systems (e.g. utilizing P2P techniques or making better use of caching). Finally, we discuss

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