Neural field models with threshold noise

The original neural field model of Wilson and Cowan is often interpreted as the averaged behaviour of a network of switch like neural elements with a distribution of switch thresholds, giving rise to the classic sigmoidal population firing-rate function so prevalent in large scale neuronal modelling. In this paper we explore the effects of such threshold noise without recourse to averaging and show that spatial correlations can have a strong effect on the behaviour of waves and patterns in continuum models. Moreover, for a prescribed spatial covariance function we explore the differences in behaviour that can emerge when the underlying stationary distribution is changed from Gaussian to non-Gaussian. For travelling front solutions, in a system with exponentially decaying spatial interactions, we make use of an interface approach to calculate the instantaneous wave speed analytically as a series expansion in the noise strength. From this we find that, for weak noise, the spatially averaged speed depends only on the choice of covariance function and not on the shape of the stationary distribution. For a system with a Mexican-hat spatial connectivity we further find that noise can induce localised bump solutions, and using an interface stability argument show that there can be multiple stable solution branches

Stochastic Dominance Analysis of CTA Funds

In this paper, we employ the stochastic dominance approach to rank the performance of commodity trading advisors (CTA) funds. An advantage of this approach is that it alleviates the problems that can arise if CTA returns are not normally distributed by utilizing the entire returns distribution. We find both first-order and higher-order stochastic dominance relationships amongst the CTA funds and conclude that investors would be better off investing in the first-order dominant funds to maximize their expected utilities and expected wealth. However, for higher-order dominant CTA, riskaverse investors can maximize their expected utilities but not their expected wealth. We conclude that the stochastic dominance approach is more appropriate compared with traditional approaches as a filter in the CTA selection process given that a meaningful economic interpretation of the results is possible as the entire return distribution is utilized when returns are non-normal

Survey of acute pesticide poisoning among agricultural workers in four Asian countries*

The study investigated the extent of acute pesticide poisoning in selected agricultural communities in Indonesia, Malaysia, Sri Lanka and Thailand, as well as the contributing factors, because it is believed that this type of poisoning is a major problem in developing countries, but not in the industrialized countries, despite their extensive use of pesticides. The study confirmed the existence of this problem, which was found to be due to inadequate knowledge of the safe practices in the use of pesticides among users and to the lack of suitable protective clothing for use by agricultural workers in hot and humid climates

History of blood transfusion, tattooing, acupuncture and risk of hepatitis B surface antigenaemia among Chinese men in Singapore.

To determine whether a history of blood transfusion, tattooing, and acupuncture is associated with an increased risk of hepatitis B surface antigenaemia, a study of 6,328 Chinese men between 35 and 65 years of age was undertaken in Singapore. The age-adjusted odds ratios were 1.44 (95% CI: 1.14, 1.83) for blood transfusion, 1.14 (95% CI: 0.80, 1.63) for tattooing, and 0.88 (95% CI: 0.71, 1.11) for acupuncture. Using no history of any of the three percutaneous procedures as reference, the age-adjusted odds ratio for blood transfusion only was 1.40, 95% CI: 1.07, 1.84, and for blood transfusion plus tattooing was 2.59, 95% CI: 1.18, 5.70. The proportion of HBsAg positive cases attributable to blood transfusion and tattooing, as measured by the population attributable risk, are 4.1 and 0.7 per cent, respectively

Atomic absorption spectrophotometric microdetermination of total mercury in undigested biological samples

Journal of Analytical Toxicology123132-135JATO

Atomic absorption spectrophotometric determination of mercury in undigested biological samples

Industrial Health263173-178INHE