BackgroundAn advantage of randomised response and non-randomised models investigating sensitive issues arises from the characteristic that individual answers about discriminating behaviour cannot be linked to the individuals. This study proposed a new fuzzy response model coined 'Single Sample Count' (SSC) to estimate prevalence of discriminating or embarrassing behaviour in epidemiologic studies.MethodsThe SSC was tested and compared to the established Forced Response (FR) model estimating Mephedrone use. Estimations from both SSC and FR were then corroborated with qualitative hair screening data. Volunteers (n = 318, mean age = 22.69 ± 5.87, 59.1% male) in a rural area in north Wales and a metropolitan area in England completed a questionnaire containing the SSC and FR in alternating order, and four questions canvassing opinions and beliefs regarding Mephedrone. Hair samples were screened for Mephedrone using a qualitative Liquid Chromatography-Mass Spectrometry method.ResultsThe SSC algorithm improves upon the existing item count techniques by utilizing known population distributions and embeds the sensitive question among four unrelated innocuous questions with binomial distribution. Respondents are only asked to indicate how many without revealing which ones are true. The two probability models yielded similar estimates with the FR being between 2.6% - 15.0%; whereas the new SSC ranged between 0% - 10%. The six positive hair samples indicated that the prevalence rate in the sample was at least 4%. The close proximity of these estimates provides evidence to support the validity of the new SSC model. Using simulations, the recommended sample sizes as the function of the statistical power and expected prevalence rate were calculated.ConclusionThe main advantages of the SSC over other indirect methods are: simple administration, completion and calculation, maximum use of the data and good face validity for all respondents. Owing to the key feature that respondents are not required to answer the sensitive question directly, coupled with the absence of forced response or obvious self-protective response strategy, the SSC has the potential to cut across self-protective barriers more effectively than other estimation models. This elegantly simple, quick and effective method can be successfully employed in public health research investigating compromising behaviours.

We review the risk of norovirus (NoV) infection to the human population from consumption of contaminated shellfish. From a UK perspective, risk is apportioned for different vectors of NoV infection within the population. NoV spreads mainly by person-to-person contact or via unsanitary food handling. NoV also enters the coastal zone via wastewater discharges resulting in contamination of shellfish waters. Typically, NoV persists in the marine environment for several days, with its presence strongly linked to human population density, wastewater discharge rate, and efficacy of wastewater treatment. Shellfish bioaccumulate NoV and current post-harvest depuration is inefficient in its removal. While NoV can be inactivated by cooking (e.g. mussels), consumption of contaminated raw shellfish (e.g. oysters) represents a risk to human health. Consumption of contaminated food accounts for 3–11% of NoV cases in the UK (~74,000 cases/year), of which 16% are attributable to oyster consumption (11,800 cases/year). However, environmental and human factors influencing NoV infectivity remain poorly understood. Lack of standard methods for accurate quantification of infective and non-infective (damaged) NoV particles represent a major barrier, hampering identification of an appropriate lower NoV contamination limit for shellfish. Future management strategies may include shellfish quality assessment (at point of harvest or at point of supply) or harvesting controls. However, poor understanding of NoV inactivation in shellfish and the environment currently limits accurate apportionment and risk assessment for NoV and hence the identification of appropriate shellfish or environmental quality standards.

We monitored annual CO 2 , N 2 O and CH 4 emissions from arable peat soils.  Emissions were dominated by CO 2 from SOM mineralization.  Cumulative N 2 O emissions were important, and CH 4 emissions negligible.  Total emissions generally increased with an increase in SOM content.  Intensive cultivation promotes loss of SOM and depletes the soil resource.

Livestock agriculture is a significant global emitter of greenhouse gases (GHG) and the sector is under pressure to reduce its environmental footprint. Dairy, sheep and beef production are major contributors to emissions. Here, a study of the barriers to implementing GHG mitigation measures on sheep, beef and dairy farms in Wales provides insights into challenges for these sectors globally. Data were gathered from 18 stakeholder organisations and farmers using semi-structured interviews and facilitated workshops. Participants were asked about the challenges to implementing measures associated with different parts of the farming system. Data were analysed using a grounded theory approach. Identified themes covered the range of challenges to the implementation of climatefriendly agricultural practice described in a global review. A conceptual model linking categories of challenge (Practical limitations, Knowledge limitations, Cognitive limitations and Interests) was developed from the data. Comparing the findings with existing work on behavioural change revealed two major differences: i) The concept of Cognitive limitations highlighted the importance of 2 cognitive processes recognised in social psychology to the implementation of change in livestock agriculture. It differentiated specific cognitive biases incorporated in behavioural models from constraints affecting the thought processes in which these biases develop and which they affect, ii) Critical elements such as power relationships and conflicting stakeholder interests were highlighted as important factors outside the scope of behavioural change models. The conceptual model developed can support policymakers in understanding and tackling challenges to change in livestock agricultural systems.

Drained and cultivated fen peats represent some of the world's most productive soils, however, they are susceptible to degradation and typically exhibit high rates of greenhouse gas (GHG) emission. We hypothesised that GHG losses from these soils could be reduced by manipulating water table depth, tillage regime, crop residue application or horticultural fleece cover. Using intact soil columns from a horticultural peatland, emissions of CO 2 , N 2 O and CH 4 were monitored over a six-month period, using a closed-chamber method. Concurrent measurements of soil properties allowed identification of the key controls on GHG emissions. Raising the water table to the soil surface provided the strongest reduction in global warming potential (GWP 100 ; 26 ± 6 kg CO 2-e ha-1 d-1), compared to a free-draining control (81 ± 1 kg CO 2-e ha-1 d-1), but this effect was partially negated by an emission pulse when the water table was subsequently lowered. The highest emissions occurred when the water table was maintained 15 cm below the surface (172 ± 12 kg CO 2-e ha-1 d-1), as this stimulated N 2 O loss. Placement of horticultural fleece over the soil surface during spring had no significant effect on GWP 100 , but prolonged fleece application exacerbated GHG emissions. Leaving lettuce crop residues on the surface increased soil GWP 100 (106 ± 4 kg CO 2-e ha-1 d-1) in comparison to when residues were incorporated into the soil (85 ± 4 kg CO 2-e ha-1 d-1), however, there was no evidence that this promoted positive priming of native soil organic matter (SOM). For maximum abatement potential, mitigation measures should be applied during the growing season, when GHG emissions are greatest. Our results also suggest that introduction of zeroor minimum-till practices may not reduce GHG emissions. Maintaining a high water table was the only option that reliably reduced GHG emissions, however, this option is impractical to implement within current horticultural systems. We conclude that alternative strategies or a major change in land use (e.g., conversion from horticulture/arable to wetland) should be explored as a means of preserving these soils for future generations.