The export of grain from Western Australia depends upon a grain supply network that takes grain from farm to port through Cooperative Bulk Handling receival and storage sites. The ability of the network to deliver pest free grain to the port and onto ship depends upon the quality of grain delivered by farmers and the efficacy of phosphine based fumigation in controlling stored grain pests. Phosphine fumigation is critical to the grain supply network because it is the cheapest effective fumigant. In addition, it is also residue free. Unfortunately, over time, common stored-grain pests have evolved to develop resistance to phosphine and there is a risk that phosphine will become less effective and may need to be replaced with more expensive alternative fumigants. Currently the alternative fumigants will involve substantial capital investment or leave residues in the grain which may restrict grain exports. There is some evidence that phosphine resistance develops on farm due to inadequate biosecurity management. As a first step to analysing this problem, this paper considers the design of farm biosecurity contracts using a principal-agent approach.
The propagation of uncertainties associated with the stable oxygen isotope reference materials through a multi-point normalisation procedure was evaluated in this study using Monte Carlo (MC) simulation. We quantified the normalisation error for a particular selection of reference materials and their number of replicates, when the choice of standards is restricted to either nitrates, sulphates or organic reference materials alone, and in comparison with when this restriction was relaxed. A lower uncertainty in stable oxygen isotope analyses of solid materials performed using High-Temperature Pyrolysis (HTP) can be readily achieved through an optimal selection of reference materials. Among the currently available certified reference materials the best performing pairs minimising the normalisation errors are USGS35 and USGS34 for nitrates; IAEA-SO-6 and IAEA-SO-5 for sulphates; and IAEA-601 and IAEA-602 for organic materials. The normalisation error can be reduced further--by approximately half--if each of these two analysed reference materials is replicated four times. The overall optimal selection among all nine considered reference materials is the IAEA-602 and IAEA-SO-6 pair. If each of these two reference materials is replicated four times the maximum predicted normalisation error will equal 0.22‰, the minimum normalisation error 0.12‰, and the mean normalisation error 0.15‰ over the natural range of δ(18)O variability. We argue that the proposed approach provides useful insights into reference material selection and in assessing the propagation of analytical error through normalisation procedures in stable oxygen isotope studies.
A higher analytical precision of a stable isotope ratio mass spectrometer does not automatically guarantee accurate determination of the true isotope composition (delta-value) of samples, since estimates of true delta-values are obtained from the normalization of raw isotope data. We performed both Monte Carlo simulations and laboratory experiments to investigate aspects of error propagation during the normalization of carbon stable isotope data. We found that increasing both the number of different reference standards and the number of repetitions of each of these standards reduces the normalization error. A 50% reduction in the normalization error can be achieved over the two-point normalization by either analyzing two standards four times each, or four standards two times each. If the true delta-value of a sample is approximately known a priori, the normalization error may then be reduced through a targeted choice of locally optimal standards. However, the difference in improvement is minimal and, therefore, a more practical strategy is to use two or more standards covering the whole stable isotope scale. The selection of different sets of standards by different laboratories or for different batches of samples in the same laboratory may lead to significant differences in the normalized delta-values of the same samples, leading to inconsistent results. Hence, the same set of standards should always be used for a particular element and a particular stable isotope analytical technique.
Increasing volumes and speed of agricultural trade and the opening of new markets for agricultural products create greater challenges to systems established to protect countries from invasive organisms that can be harmful to human and animal health, crops and natural environments. In reaction to the threat of exotic pests and diseases, the World Trade Organization recognises the right of country members to protect themselves from the risks posed by exotic pests and diseases through the application of Sanitary and Phytosanitary (SPS) measures. One possible response from exporting countries facing SPS trade barriers is to obtain pest-free area (PFA) certification. While large benefits can potentially be achieved from greater access to world markets through the establishment and maintenance of a PFA, certification can be expensive. This paper aims to identify a theoretical framework on which to base the cost benefit analysis and the costs and benefits to be measured, from which a methodology for measuring costs and benefits may be developed. The literature relevant to analysing PFAs reveals that cost benefit analysis of the establishment of PFAs incorporate complex links between the economic aspects of this type of pest management and the biological characteristics of the pest or disease targeted and its environment.
Purpose The purpose of this paper is to measure the vulnerability to food insecurity in rural Punjab, Pakistan. Design/methodology/approach Primary data of 1,152 households were collected. The extent of food deficiency was measured using dietary intake assessment method (seven days). Value at Risk (VaR) and conditional Value at Risk (cVaR), a method widely used for risk analysis in financial institutes, were applied to assess the vulnerability to food insecurity. Findings In total, 23 percent of the sample households were measured as food deficient. The VaR and cVaR results identified that the lowest 3 percentiles (up to 30 percent) were at risk to become food deficient without any seasonal shortages. In case of shocks, up till sixth percentiles (60 percent) will be as at risk of food deficiency. This study suggests that multi-period data, at least quarterly, are required to predict vulnerability. It is suggested that a blanket policy is not a good approach. Once the most vulnerable households are identified, a targeted approach must be opted. Originality/value Generalizing the results of one week’s calorie calculations may produce biased results that may mislead the policy process. A multi-period data collection is costly and cumbersome. The application of VaR and cVaR helps overcome this issue. Furthermore, this is one of the initial studies to apply these methods to food security analysis.
Regional management of endemic pests of trade significance typically requires a surveillance system, border controls, eradication protocols and conditions for market closure and reopening. An example is the systems for managing Queensland fruit fly (Qfly) in south east Australia where the preferred approach for intensive production areas is an Area Wide Management (AWM) scheme. An AWM, such as the Greater Sunraysia PFA (GSPFA) in northern Victoria and western New South Wales, depends for its recognition amongst trade partners on an effective and credible surveillance system that identifies outbreaks rapidly, notifies exporters of trade restrictions and initiates eradication. These ‘market rules’ are fundamental to the economics of surveillance: they define an outbreak and thus the probability of market closure, the expected time to eradication, and consequent time to market reopening. This paper uses a spatial and dynamic bioeconomic model of Qfly infestation and spread to determine the expected optimal investment in surveillance and eradication capacity of the AWM.
It has been argued that adding wine to an investment portfolio provides a diversification benefit. There is not, however, agreement on how the return to wine should be estimated. Nor is there agreement on a standard approach to test for a diversification benefit. By considering different approaches to estimating the return to wine and testing for a diversification benefit it is shown that claims wine provides a diversification benefit should be treated with caution.
'/%3e%3c/defs%3e%3cpath fill='%23012169' d='M0 0h10080v5040H0z'/%3e%3cpath stroke='%23fff' stroke-width='.6' d='m0 0 6 3m0-3L0 3' clip-path='url(%23b)' transform='scale(840)'/%3e%3cpath stroke='%23e4002b' stroke-width='.4' d='m0 0 6 3m0-3L0 3' clip-path='url(%23c)' transform='scale(840)'/%3e%3cpath stroke='%23fff' stroke-width='840' d='M2520 0v2520M0 1260h5040'/%3e%3cpath stroke='%23e4002b' stroke-width='504' d='M2520 0v2520M0 1260h5040'/%3e%3cg fill='%23fff'%3e%3cuse xlink:href='%23d' x='2520' y='3780'/%3e%3cuse xlink:href='%23a' x='7560' y='4200'/%3e%3cuse xlink:href='%23a' x='6300' y='2205'/%3e%3cuse xlink:href='%23a' x='7560' y='840'/%3e%3cuse xlink:href='%23a' x='8680' y='1869'/%3e%3cuse xlink:href='%23e' x='8064' y='2730'/%3e%3c/g%3e%3c/svg%3e)