Implications of HGV charging for the UK

Road transport taxation in Europe is undergoing a major and radical shift away from fixed charges and fuel duties towards pricing according to distance travelled and externalities produced. Implementation is underway in some states, change being led by national schemes for the freight sector only. The UK is considering such a system for implementation by 2008, to use global positioning system technology. The paper reviews the current developments and considers charging scenarios, including a scenario for covering the full external costs of the UK freight industry. Implications for taxation policy are considered, including whether the doctrine of revenue neutrality is consistent with 'sustainable mobility'. Consideration is given to a transition strategy which could bridge between the current level and structure of prices and a future, more economically efficient approach

Social inclusion implications of park-and-ride

Park and ride (P&R) schemes are often promoted as an efficient means of extending the effective catchment of public transport networks into car-dependent areas with low population densities, such as rural districts. However, using P&R typically requires the traveller to have access to a car. As car ownership is often used as an indicator of social inclusion, providing P&R for motorists is not an obvious means of reducing exclusion from travel opportunities. Nonetheless, the present article argues that policies to promote interchange from cars to bus or rail can act as a force for either greater or less social exclusion, depending on who can access the services and what the alternative options would be in the absence of P&R being provided. The conditions under which inclusion is most likely to be promoted are reviewed. Key findings are that P&R facilities should not be developed at the expense of investment in conventional public transport and that the services should not be exclusively aimed at motorists. A particular situation in which motorists on relatively low incomes might benefit from P&R provision is where they would otherwise face high access charges to urban areas, in the form of road tolls or parking fees

STATISTICAL ISSUES IN STUDIES OF THERMOREGULATION IN FARM ANIMALS

Patterns of tympanic temperature response were identified in ad-lib-fed cattle exposed to constant or cyclic (±7 C) conditions at two levels of air temperature: 10 C and 28 C. Use of time series analysis following the DDS approach of Pandit and Wu indicate the thermoregulatory control dynamics for steers at 28±7 C were markedly different from those at the other conditions. Preliminary evaluations using the ideas of chaos and non-linear dynamics show promise of further characterization of stress responses in farm animals

Scaling up pro-environmental agricultural practice using agglomeration payments: Proof of concept from an agent-based model

Rates of adoption of pro-environmental practices in agriculture in many parts of the world are low. In some cases, this is attributable to the private costs borne by farmers to adopt these practices, often well in advance of any benefits - public or private - that they may bring. Monetary incentives, such as through payments-for-ecosystem services (PES) programs, may be of assistance, and in this study we examine the potential for a recent innovation (the agglomeration payment) to improve adoption of pro-environmental practice in a rural agricultural context. Agglomeration payments include bonus payments for adoption by neighboring farms, which may help to encourage both compliance with the program they promote as well as the overall diffusion of the program across rural contexts. We develop an abstract agent-based model (ABM) of an agglomeration payment program to encourage adoption of the pro-environment practice of conservation agriculture (CA). We find that agglomeration payments have the potential to improve levels of adoption of pro-environmental practice per program dollar, and may help to reduce required spending on project monitoring and enforcement

SPLINE MODELS FOR ESTIMATING HEAT STRESS THRESHOLDS IN CATTLE

Studies of the relationship between animal body temperature and air temperature suggest body temperature is essentially unresponsive until a threshold is reached, then it responds dramatically to increasing air temperature. The goal is to estimate the threshold between the thermoneutral plateau and the beginning of the heat stress challenge. One approach is to fit a polynomial to estimate the knot position and use spline functions to perform linear least squares piecewise polynomial fitting. Another alternative is to use nonlinear regression to estimate the knot or an inflection point of a nonlinear function. In both approaches the cyclic nature of body temperature is ignored. This paper explores the use of nonlinear regression to estimate the knot position and handles the hysteresis effect resulting from the cyclic nature of body temperature. Models are fit to data collected from cattle in chambers subjected to semicontrolled sinusoidal air temperature at the University of Missouri-Columbia Animal Science department and a procedure for estimating the heat stress threshold is proposed

Photo-Enhanced Toxicity in Amphibians: Synergistic Interactions of Solar Ultraviolet Radiation and Aquatic Contaminants

Amphibians experience a broad range of multiple environmental stressors that occur in natural systems. However, the impact of combinations of these stressors on amphibians are rarely examined. The effect of two stressors on amphibians, solar ultraviolet radiation (SUV) and environmental contamination, was investigated. To examine the interactive effects of SUV and environmental contaminants, Hyla venicolor and Rana sphenocephala were exposed in the laboratory to a carbamate insecticide and the water soluble fraction of a weathered petroleum in combination with various intensities of simulated solar radiation (SSR). The contaminants were tested at environmentally relevant concentrations. Synergistic interactions between SSR and these substances were observed during the exposures. Mortality of H. versicolor exposed to 2.51 mg/I carbaryl increased from 5% under control SSR conditions to 100% under low SSR irradiance (4 μ W/cm2). Exposure to a 10% solution of a water soluble fraction of petroleum under control SSR conditions was not lethal to R. sphenocephala; however under high SSR irradiance (17 μ W/cm2) a 5% water soluble fraction of petroleum was lethal. Relatively limited SSR irradiance is necessary to initiate photoenhanced toxicity, thus a range of amphibian habitats may be impacted by SUV. These studies indicate the importance of evaluating the interactive influence of environmental stressors present in amphibian habitats

USING NONLINEAR FIXED AND MIXED MODELS TO STUDY ACCLIMATION TO HEAT STRESS IN CATTLE

Researchers studying acclimation of cattle to heat stress want to know if exposure to heat stress in controlled chambers will help cattle adjust to climatic conditions in the field. The four parameter nonlinear PET model is used to study the relationship between core body temperature and ambient temperature. This model works well when cattle are challenged by heat stress but the model is less useful for thermoneutral conditions. Both proc Nlin and Nlmixed are used to compare and contrast the field parameters between the controlled and the potentially acclimated group. Simulation studies were used to compare the effectiveness of proc Nlin versus proc Nlmixed. The results are helpful, not only for researchers who study acclimation, but also for those who study sensitivity, tolerance and robustness of cattle during heat stress

EVALUATING NONLINEAR CROSSED RANDOM EFFECTS MODELS FOR COMPARING TEMPERATURE OF FEEDING PIGS UNDER DIFFERENT THERMAL ENVIRONMENTS

The thermal environment plays a large role in an animal’s ability to convert feed into weight gain. A better understanding of a pig’s metabolism will help swine producers select environmental specifications for optimizing feed conversion. The objectives of this study are to 1) characterize the thermoregulatory responses of pigs during a feeding event 2) compare those responses for three thermal environmental treatments applied in a Latin Square design 3) investigate different procedures for fitting nonlinear mixed-effect models with crossed random effects (NLME function in R, %NLINMIX macro in SAS, random effects modeling in AD Model Builder: ADMB-RE). We found that the threeparameter first-order compartment model provides a reasonable representation of the tympanic temperatures of feeding pigs during feeding events. The thermal environmental treatments (28ºC + High air speed) and (18ºC + Low air speed) are significantly different from the reference treatment (28ºC + Low air speed), at the 5% level. Both NLME and ADMB-RE successfully fit the nonlinear mixed-effects model and produce similar results. The %NLINMIX macro did not converge unless restrictions were placed on the model. The estimates of fixed and random effects from the restricted model using %NLINMIX macro were generally different from those from NLME and ADMB-RE

ASSESSING REFINEMENTS IN MODELING SINUSOIDAL CONDITIONS USED TO DRIVE CATTLE BODY TEMPERATURES

A model, termed the PET model, is used to estimate body temperature in cattle challenged by hot cyclic chamber temperatures. The model is based on Newton\u27s law of cooling, driven by an estimated sinusoidal function. In practice, it is often difficult to maintain hot sinusoidal fluctuations in chamber temperatures. However, it is possible to model cyclic chamber temperatures using a discrete Fourier series. By increasing the precision in estimating the cyclic temperature driving function, we can more precisely estimate the parameters in the PET model. Simulation studies were performed to investigate the effect of under- and over-parameterization on accuracy of estimates, performance of a number of model selection criteria, and on nonlinear behavior such as intrinsic and parameter-effects curvature, bias, excess variance, and skewness. Our results will help researchers decide how to model ambient temperatures producing heat stress in cattle and improve estimates for evaluating management strategies

USING TIME SERIES TO STUDY DYNAMICS OF SWEAT RATES OF HOLSTEIN COWS EXPOSED TO INITIAL AND PROLONGED SOLAR HEAT STRESS

Sweating is a very important way for cows to cope with heat stress. We are interested in the ability of Holstein cows to sustain high sweat or evaporation rates when exposed to solar radiation. There were two solar heat stress treatments: onset and prolonged. The onset data provided an opportunity to examine the impact of sudden exposure to a solar thermal load. The prolonged data allowed us to examine the impact of exposure to solar heat stress for an expended period (5 hr). Two questions of interest were: Do cows sweat at a constant or cyclic rate? Is there a difference in the dynamics of the two treatments: onset and prolonged solar heat stress? The data were examined for stationarity. In the time domain, we fit ARIMA models and estimated the parameters. In the frequency domain, we used nonparametric spectral estimation to identify cyclic patterns in the sweat rates. The usefulness of each technique for analyzing the dynamics of sweat rates is discussed