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Abstract  

In using positrons as analytical tools the experimenter has two quite different options. The first and more obvious is to duplicate electron methods with positrons and see what differences (if any) result. The second is to exploit a unique characteristic of positrons, such as the formation and decay of the positronium atom, to study chemical composition and surface characteristics. Because positrons do not exist freely in our world, they must be obtained from radioactive sources or nuclear interactions. Source intensity has consequently been a limiting factor in experiments that attempt to duplicate electron applications. Some methods of producing and moderating positrons that have been developed here (and elsewhere) are described as well as results from studies using the sources. Surface measurements require less intense sources and yield useful data on materials such as xeolites, silica gels, graphite and alumina. Experimental apparatus, data and interpretation will be discussed.

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Abstract  

A survey of the mercury content of the diet in the Glasgow area is described. A higher intake of mercury (60 μg/day/person) than that expected is found. However, there does not appear to be any concentration of mercury by man. None of the foodstuffs show any exceptional mercury content. Fish levels are similar to other foods and a preliminary sample of shellfish from the Clyde estuary, a contaminated area, shown no sign of their having concentrated mercury to any significant degree.

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Abstract  

The normal levels of arsenic in human tissue are reported together with the arsenic concentrations found in the investigation of a large number of industrial exposure incidents. These results are useful for establishing that industrial exposure has taken place and for confirming arsenic poisoning but they cannot be used realistically to predict that any person or group will suffer a visible deterioration in health because no correlation between arsenic contamination and symptoms can be made. Industrial workers who are affected by arsenic exposure are often no more exposed than their co-workers.

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Abstract  

We describe the operation of a Local Area Network at Nuclear Chemistry Laboratory involved in surveillance of environmental radioactivity. Detailed consideration is given separately to computer and network hardware, radiation instrument interfacing, software, as well as operations. The application of a Local Area Network offers considerable improvements in the laboratory preformance, quality assurance of radioactivity analyses, and data reporting.

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Journal of Behavioral Addictions
Authors: Eve H. Limbrick-Oldfield, Mariya V. Cherkasova, Dawn Kennedy, Caylee-Britt Goshko, Dale Griffin, Jason J.S. Barton, and Luke Clark

Abstract

Background and aims

Individuals with gambling disorder display increased levels of risk-taking, but it is not known if it is associated with an altered subjective valuation of gains and/or losses, perception of their probabilities, or integration of these sources of information into expected value.

Methods

Participants with gambling disorder (n = 48) were compared with a healthy comparison group (n = 35) on a two-choice lottery task that involved either gains-only or losses-only gambles. On each trial, two lotteries were displayed, showing the associated probability and magnitude of the possible outcome for each. On each trial, participants chose one of the two lotteries, and the outcome was revealed.

Results

Choice behaviour was highly sensitive to the expected value of the two gambles in both the gain and loss domains. This sensitivity to expected value was attenuated in the group with gambling disorder. The group with gambling disorder used both probability and magnitude information less, and this impairment was greater for probability information. By contrast, they used prior feedback (win vs loss) to inform their next choice, despite the independence of each trial. Within the gambling disorder group, problem gambling severity and trait gambling-related cognitions independently predicted reduced sensitivity to expected value. The majority of observed effects were consistent across both gain and loss domains.

Discussion and Conclusions

Our results provide a thorough characterization of decision processes in gain and loss domains in gambling disorder, and place these problems in the context of theoretical constructs from behavioural economics.

Open access
Journal of Behavioral Addictions
Authors: Eve H. Limbrick-Oldfield, Mariya V. Cherkasova, Dawn Kennedy, Caylee-Britt Goshko, Dale Griffin, Jason J.S. Barton, and Luke Clark

Abstract

Background and aims

Individuals with gambling disorder display increased levels of risk-taking, but it is not known if it is associated with an altered subjective valuation of gains and/or losses, perception of their probabilities, or integration of these sources of information into expected value.

Methods

Participants with gambling disorder (n = 48) were compared with a healthy comparison group (n = 35) on a two-choice lottery task that involved either gains-only or losses-only gambles. On each trial, two lotteries were displayed, showing the associated probability and magnitude of the possible outcome for each. On each trial, participants chose one of the two lotteries, and the outcome was revealed.

Results

Choice behaviour was highly sensitive to the expected value of the two gambles in both the gain and loss domains. This sensitivity to expected value was attenuated in the group with gambling disorder. The group with gambling disorder used both probability and magnitude information less, and this impairment was greater for probability information. By contrast, they used prior feedback (win vs loss) to inform their next choice, despite the independence of each trial. Within the gambling disorder group, problem gambling severity and trait gambling-related cognitions independently predicted reduced sensitivity to expected value. The majority of observed effects were consistent across both gain and loss domains.

Discussion and Conclusions

Our results provide a thorough characterization of decision processes in gain and loss domains in gambling disorder, and place these problems in the context of theoretical constructs from behavioural economics.

Open access