Gyrotron experiments employing a field emission array cathode

The design and operation of a field emission array (FEA) cathode and the subsequent demonstration of the first FEA gyrotron are presented. Up to 10 mA from 30 000 tips was achieved reproducibly from each of ten chips in a gyrotron environment, namely, a vacuum 1 x 10(-8) mbar, -50 kV potential with multiple chip operation, The design parameters of the FEA gun were similar to those of a magnetron injection gun with an achievable electron beam current of 50-100 mA and measured power 720 W cw. Coherent microwave radiation was detected in both TE(02) at 30.1 GHz and TE(03) at 43.6 GHz, with a starting current of 1 mA

Reducing quality control errors by guiding behavior

It is estimated that human error in the quality control checking of product labels on consumer packaging costs the UK retail industry £50m per annum. Our research program aimed to understand the behavior of individuals when performing label checks on fresh produce in order to inform the development of a software application designed to support quality control. On a simulated label checking task, eye-tracking data showed that individuals used different checking methods. A more systematic method led to higher accuracy. Two computer-assisted approaches, varying in the level of computer support provided, were then designed to push checkers towards systematic checking. Greater improvements in accuracy were found under the computer-assisted approaches than under a control condition. A three-month onsite trial of a software application designed on the basis of these research findings led to a 100% decrease in quality control errors

Studies of the interactions of resin acids with Pigment Yellow 13

The surface interaction between Pigment Yellow 13, a classical diarylide pigment, and abietic acid type resin acids, used commercially to coat pigment products, was investigated by the joint techniques of solid-state ¹³CP/MAS NMR and powder X-ray diffraction. The initial objective of the study was to synthesise ¹³C labelled resin acid analogues to provide a handle for the NMR study. Attempts were made to label the carboxylic acid carbon of abietic acid, via a Barton reaction and subsequent Grignard reaction and carboxylation. Esterification of various resin acid substrates with ¹³C labelled diazomethane was also attempted. These routes proved difficult, due to the sterically hindered nature of the acid substrates. Labelled adducts were formed from ¹³C-malcic anhydride and isomerised abietic acid, but were found to be lost from the pigment during resination. Attempts to form a more stable adduct with N-methylmaleimide were unsuccessful. A series of experiments was carried out to coat Pigment Yellow 13 with incremental amounts of abietic acid, maleopimaric acid and dihydroabietic acid. The maleopimaric acid was lost during processing. The pigment samples resinated with abietic acid and dihydroabietic acid were analysed by the techniques mentioned previously. The presence of resin acids during pigment processing was found to enhance the crystallinity of the pigment particles, as opposed to the heat treatment during processing which promotes particle size. The resin acids were found to be more amorphous than the starting resin when reprecipitated on the pigment particles, ¹³C CP/MAS NMR shows that there is no chemical interaction between the pigment molecule and the carboxylic acid of the resin

Label-checking strategies to adapt behaviour to design

Despite robust quality control procedures, labelling errors on fresh produce are estimated to cost the UK supermarket industry approximately £50million pounds per year in product recalls and wastage. Changing the format of the labels themselves is not a viable option. Instead, the challenge is to change or guide human operatives’ behaviour so that label printing errors do not go undetected during quality control procedures. To this end, a simulated label checking task was presented to naïve participants to compare more systematic and strategic methods of label checking. Two conditions in which behaviour was computer-led were compared with a control condition in which checkers adopted their own idiosyncratic checking method. The data indicate that the two computer-led approaches resulted in improved levels of accuracy. Pushing label checkers towards a more systematic approach would appear to be effective in reducing undetected label errors, and could lead potentially to significant financial savings and reduce

Argumentation in Decision Support for Medical Care Planning for Patients and Clinicians.

Developing a care plan for a patient requires an understanding of interactions and dependencies between procedures, and of their possible outcomes for an individual patient, and it requires the planner to keep track of this information as the proposed plan evolves. This is difficult even for experienced clinicians, but increasingly patients are expected (and expect) to participate. We describe an argumentation-based planning support system designed to ameliorate the cognitive load imposed by the planning and communication elements of such tasks. An initial evaluation study in the field of genetic counseling produced promising results. The approach may provide a general aid for clinicians and patients in visualizing, customizing, evaluating and communicating about care plans

Cognitive predictors of accuracy in quality control checking

Labelling errors on fresh produce are estimated to cost the UK supermarket industry £50m per year in product recalls and wastage. Such errors occur despite robust quality control procedures. Given the financial and environmental impact of these errors, it is important to understand whether label-checking performance can be predicted by individual differences in cognitive abilities. To this end, participants carried out a simulated label-checking task together with a number of measures of information processing speed, attention, short-term/working memory, and mind-wandering. Accuracy of label checking was found to be significantly predicted by three of the measures, with better short-term verbal memory being most strongly associated with performance. Cognitive tests such as these provide a means of identifying how well employees are likely to perform when undertaking such tasks and, if necessary, how they should be supported in that role, possibly forming a screening battery when recruiting new quality control staff. The findings highlight the importance of determining the component processes of cognition which contribute to performance in real-world work environments

Role of widows in the heterosexual transmission of HIV in Manicaland, Zimbabwe, 1998–2003

BACKGROUND: AIDS is the main driver of young widowhood in southern Africa. METHODS: The demographic characteristics of widows, their reported risk behaviours and the prevalence of HIV were examined by analysing a longitudinal population-based cohort of men and women aged 15-54 years in Manicaland, eastern Zimbabwe. The results from statistical analyses were used to construct a mathematical simulation model with the aim of estimating the contribution of widow behaviour to heterosexual HIV transmission. RESULTS: 413 (11.4%) sexually experienced women and 31 (1.2%) sexually experienced men were reported to be widowed at the time of follow-up. The prevalence of HIV was exceptionally high among both widows (61%) and widowers (male widows) (54%). Widows were more likely to have high rates of partner change and engage in a pattern of transactional sex than married women. Widowers took partners who were a median of 10 years younger than themselves. Mathematical model simulations of different scenarios of sexual behaviour of widows suggested that the sexual activity of widow(er)s may underlie 8-17% of new HIV infections over a 20-year period. CONCLUSIONS: This combined statistical analysis and model simulation suggest that widowhood plays an important role in the transmission of HIV in this rural Zimbabwean population. High-risk partnerships may be formed when widowed men and women reconnect to the sexual network

Children's verbal, visual and spatial processing and storage abilities: An analysis of verbal comprehension, reading, counting and mathematics

The importance of working memory (WM) in reading and mathematics performance has been widely studied, with recent research examining the components of WM (i.e., storage and processing) and their roles in these educational outcomes. However, the differing relationships between these abilities and the foundational skills involved in the development of reading and mathematics have received less attention. Additionally, the separation of verbal, visual and spatial storage and processing and subsequent links with foundational skills and downstream reading and mathematics has not been widely examined. The current study investigated the separate contributions of processing and storage from verbal, visual and spatial tasks to reading and mathematics, whilst considering influences on the underlying skills of verbal comprehension and counting respectively. Ninety-two children aged 7- to 8-years were assessed. It was found that verbal comprehension (with some caveats) was predicted by verbal storage and reading was predicted by verbal and spatial storage. Counting was predicted by visual processing and storage, whilst mathematics was related to verbal and spatial storage. We argue that resources for tasks relying on external representations of stimuli related mainly to storage, and were largely verbal and spatial in nature. When a task required internal representation, there was an draw on visual processing and storage abilities. Findings suggest a possible meaningful separability of types of processing. Further investigation of this could lead to the development of an enhanced WM model, which might better inform interventions and reasonable adjustment for children who struggle with reading and mathematics due to WM deficits