The Phosphorus Indicators Tool: a simple model of diffuse P loss from agricultural land to water

The Phosphorus Indicators Tool provides a catchment-scale estimation of diffuse phosphorus (P) loss from agricultural land to surface waters using the most appropriate indicators of P loss. The Tool provides a framework that may be applied across the UK to estimate P loss, which is sensitive not only to land use and management but also to environmental factors such as climate, soil type and topography. The model complexity incorporated in the P Indicators Tool has been adapted to the level of detail in the available data and the need to reflect the impact of changes in agriculture. Currently, the Tool runs on an annual timestep and at a 1 km(2) grid scale. We demonstrate that the P Indicators Tool works in principle and that its modular structure provides a means of accounting for P loss from one layer to the next, and ultimately to receiving waters. Trial runs of the Tool suggest that modelled P delivery to water approximates measured water quality records. The transparency of the structure of the P Indicators Tool means that identification of poorly performing coefficients is possible, and further refinements of the Tool can be made to ensure it is better calibrated and subsequently validated against empirical data, as it becomes available.

Exploring the spatial relations between soil physical properties and apparent electrical conductivity

Relations between the apparent electrical conductivity of the soil (ECa) and top- and sub-soil physical properties were examined for two arable fields in southern England (Crowmarsh Battle Farms and the Yattendon Estate). The spatial variation of ECa and the soil properties was explored geostatistically. The variogram ranges showed that ECa varied on a similar spatial scale to many of the soil physical properties in both fields. Several features in the map of kriged predictions of ECa were also evident in maps of the soil properties. In addition, the correlation coefficients showed a strong relation between ECa and several soil properties. A moving correlation analysis enabled differences in the relations between ECa and the soil properties to be examined within the fields. The results indicated that relations were inconsistent; they were stronger in some areas than others. A regression of ECa on the principal component scores of the leading components for both fields showed that the first two components accounted for a large proportion of the variance in ECa, whereas the others accounted for little or none. For Crowmarsh topsoil sand and clay, loss on ignition and volumetric water measured in the autumn had large correlations on the first component, and for Yattendon they were large for topsoil sand and clay, and autumn and spring volumetric water. The cross-variograms suggested strong coregionalization between ECa and several soil physical properties; in particular subsoil sand and silt at Crowmarsh, and subsoil sand and clay at Yattendon. The structural correlations from the linear model of coregionalization confirmed the strength of the relations between ECa and the subsoil properties. Nevertheless, no one property was consistently important for both fields. Although a map of ECa can indicate the general patterns of spatial variation in the soil, it is not a substitute for information on soil properties obtained by sampling and analysing the soil. Nevertheless, it could be used to guide further sampling. (c) 2005 Elsevier B.V. All rights reserved.

The effects of difficulty and gain versus loss on vocal physiology and acoustics

To examine the basis of emotional changes to the voice, physiological and electroglottal measures were combined with acoustic speech analysis of 30 men performing a computer task in which they lost or gained points under two levels of difficulty. Predictions of the main effects of difficulty and reward on the voice were not borne out by the data. Instead, vocal changes depended largely on interactions between gain versus loss and difficulty. The rate at which the vocal folds open and close (fundamental frequency; f0) was higher for loss than for gain when difficulty was high, but not when difficulty was low. Electroglottal measures revealed that f0 changes corresponded to shorter glottal open times for the loss conditions. Longer closed and shorter open phases were consistent with raised laryngeal tension in difficult loss conditions. Similarly, skin conductance indicated higher sympathetic arousal in loss than gain conditions, particularly when difficulty was high. The results provide evidence of the physiological basis of affective vocal responses, confirming the utility of measuring physiology and voice in the study of emotion.

The imminent availability of a potent weight-loss medicine in pharmacies: public perception of effectiveness

Orlistat is an effective weight-loss medicine, which will soon be available for purchase in pharmacies. We used a factorial experiment and found that informing people about the availability for purchase of this medicinal product previously only available on prescription resulted in higher ratings of perceived value and effectiveness compared to a natural health supplement even though we used the same statement about effectiveness. This positive perception of orlistat was not impaired by the provision of side-effect information. Orlistat will soon be available in pharmacies. Health professionals must act to prevent its misuse by those not overweight.

Dispersal capacity and diet breadth modify the response of wild bees to habitat loss

Habitat loss poses a major threat to biodiversity, and species-specific extinction risks are inextricably linked to life-history characteristics. This relationship is still poorly documented for many functionally important taxa, and at larger continental scales. With data from five replicated field studies from three countries, we examined how species richness of wild bees varies with habitat patch size. We hypothesized that the form of this relationship is affected by body size, degree of host plant specialization and sociality. Across all species, we found a positive species–area slope (z ¼ 0.19), and species traits modified this relationship. Large-bodied generalists had a lower z value than small generalists. Contrary to predictions, small specialists had similar or slightly lower z value compared with large specialists, and small generalists also tended to be more strongly affected by habitat loss as compared with small specialists. Social bees were negatively affected by habitat loss (z ¼ 0.11) irrespective of body size. We conclude that habitat loss leads to clear shifts in the species composition of wild bee communities.

Reactive uptake coefficients for heterogeneous reaction of N2O5 with submicron aerosols of NaCl and natural sea salt

The kinetics of uptake of gaseous N2O5 on submicron aerosols containing NaCl and natural sea salt have been investigated in a flow reactor as a function of relative humidity (RH) in the range 30-80% at 295±2K and a total pressure of 1bar. The measured uptake coefficients, γ, were larger on the aerosols containing sea salt compared to those of pure NaCl, and in both cases increased with increasing RH. These observations are explained in terms of the variation in the size of the salt droplets, which leads to a limitation in the uptake rate into small particles. After correction for this effect the uptake coefficients are independent of relative humidity, and agree with those measured previously on larger droplets. A value of γ=0.025 is recommended for the reactive uptake coefficient for N2O5 on deliquesced sea salt droplets at 298K and RH>40%.

Parameter estimation using a particle method: inferring mixing coefficients from sea level observations

This paper presents a first attempt to estimate mixing parameters from sea level observations using a particle method based on importance sampling. The method is applied to an ensemble of 128 members of model simulations with a global ocean general circulation model of high complexity. Idealized twin experiments demonstrate that the method is able to accurately reconstruct mixing parameters from an observed mean sea level field when mixing is assumed to be spatially homogeneous. An experiment with inhomogeneous eddy coefficients fails because of the limited ensemble size. This is overcome by the introduction of local weighting, which is able to capture spatial variations in mixing qualitatively. As the sensitivity of sea level for variations in mixing is higher for low values of mixing coefficients, the method works relatively well in regions of low eddy activity.

Formulation of a live bacterial vaccine for stable room temperature storage results in loss of acid, bile and bile salt resistance

Live bacterial vaccines have great promise both as vaccines against enteric pathogens and as heterologous antigen vectors against diverse diseases. Ideally, room temperature stable dry formulations of live bacterial vaccines will allow oral vaccination without cold-chain storage or injections. Attenuated Salmonella can cross the intestinal wall and deliver replicating antigen plus innate immune activation signals directly to the intestinal immune tissues, however the ingested bacteria must survive firstly gastric acid and secondly the antimicrobial defences of the small intestine. We found that the way in which cells are grown prior to formulation markedly affects sensitivity to acid and bile. Using a previously published stable storage formulation that maintained over 10% viability after 56 days storage at room temperature, we found dried samples of an attenuated S. typhimurium vaccine lost acid and bile resistance compared to the same bacteria taken from fresh culture. The stable formulation utilised osmotic preconditioning in defined medium plus elevated salt concentration to induce intracellular trehalose accumulation before drying. Dried bacteria grown in rich media without osmotic preconditioning showed more resistance to bile, but less stability during storage, suggesting a trade-off between bile resistance and stability. Further optimization is needed to produce the ultimate room-temperature stable oral live bacterial vaccine formulation.

Mitigation options for sediment and phosphorus loss from winter-sown arable crops

Sediment and P inputs to freshwaters from agriculture are a major problem in the United Kingdom (UK). This study investigated mitigation options for diffuse pollution losses from arable land. Field trials were undertaken at the hillslope scale over three winters at three UK sites with silt (Oxyaquic Hapludalf), sand (Udic Haplustept), and clay (Typic Haplaquept) soils. None of the mitigation treatments was effective in every year trialled, but each showed overall average reductions in losses. Over five site years, breaking up the compaction in tramlines (tractor wheel tracks) using a tine reduced losses of sediment and P to losses similar to those observed from areas without tramlines, with an average reduction in P loss of 1.06 kg TP ha(-1) Compared to traditional plowing, TP losses under minimum tillage were reduced by 0.30 kg TT ha(-1) over five site years, TP losses under contour cultivation were reduced by 0.30 kg TP ha(-1) over two site years, and TP losses using in-field barriers were reduced by 0.24 kg TP ha(-1) over two site years. In one site year, reductions in losses due to crop residue incorporation were nor significant. Each of the mitigation options trialled. is associated with a small cost at the farm-scale of up to 5 pound ha(-1), or with cost savings. The results indicate that each of the treatments his the potential to be a cost-effective mitigation option, but that tramline management is the most promising treatment, because tramlines dominate sediment and P transfer in surface runoff from arable hillslopes.

Inbreeding and loss of genetic variation in a reintroduced population of Mauritius Kestrel

Many populations have recovered from severe bottlenecks either naturally or through intensive conservation management. In the past, however, few conservation programs have monitored the genetic health of recovering populations. We conducted a conservation genetic assessment of a small, reintroduced population of Mauritius Kestrel (Falco punctatus) to determine whether genetic deterioration has occurred since its reintroduction. We used pedigree analysis that partially accounted for individuals of unknown origin to document that (1) inbreeding occurred frequently (2.6% increase per generation; N-el = 18.9), (2) 25% of breeding pairs were composed of either closely or moderately related individuals, (3) genetic diversity has been lost from the population (1,6% loss per generation; N-ev = 32.1) less rapidly than the corresponding increase in inbreeding, and (4) ignoring the contribution of unknown individuals to a pedigree will bias the metrics derived from that pedigree, ultimately obscuring the prevailing genetic dynamics. The rates of inbreeding and loss of genetic variation in the subpopulation of Mauritius Kestrel we examined were extreme and among the highest yet documented in a wild vertebrate population. Thus, genetic deterioration may affect this population's long-term viability. Remedial conservation strategies are needed to reduce the impact of inbreeding and loss of genetic variation in this species, We suggest that schemes to monitor genetic variation after reintroduction should be an integral component of endangered species recovery programs

Time-varying coefficients in the almost ideal demand system: An empirical appraisal

This paper provides a generalisation of the structural time series version of the Almost Ideal Demand System (AIDS) that allows for time-varying coefficients (TVC/AIDS) in the presence of cross-equation constraints. An empirical appraisal of the TVC/AIDS is made using a dynamic AIDS with trending intercept as the baseline model with a data set from the Italian Household Budget Survey (1986-2001). The assessment is based on four criteria: adherence to theoretical constraints, statistical diagnostics on residuals, forecasting performance and economic meaningfulness. No clear evidence is found for superior performance of the TVC/AIDS, apart from improved short-term forecasts.

Consumer welfare and the loss induced by withholding information: The case of BSE in Italy

The paper develops a measure of consumer welfare losses associated with withholding it formation about a possible link between BSE and vCJD. The Cost of Ignorance (COI) is measured by comparing the utility of the informed choice with the utility of the uninformed choice, under conditions of improved information. Unlike previous work that is largely based on a single equation demand model, the measure is obtained retrieving a cost,function from a dynamic Almost Ideal Demand System. The estimated perceived loss for Italian consumers due to delayed information ranges from 12 percent to 54 percent of total meat expenditure, depending on the month assumed to embody correct beliefs about the safety level of beef.