Study of a gold-foil-based multisphere neutron spectrometer.

Multisphere neutron spectrometers with active thermal neutron detectors cannot be used in high-intensity radiation fields due to pulse pile-up and dead-time effects. Thus, a multisphere spectrometer using a passive detection system, specifically gold foils, has been investigated in this work. The responses of a gold-foil-based Bonner sphere neutron spectrometer were studied for two different gold-foil holder designs; an aluminium-polyethylene holder and a polyethylene holder. The responses of the two designs were calculated for four incident neutron beam directions, namely, parallel, perpendicular and at +/-45 degrees relative to the flat surface of the foil. It was found that the use of polyethylene holder resulted in a more isotropic response to neutrons for the four incident directions considered. The computed responses were verified by measuring the neutron spectrum of a 252Cf source with known strength.

The Aberdeen Trauma Screening Index: an instrument to predict post-accident psychopathology.

BACKGROUND: A key challenge in trauma care is the prevention of psychopathology. However, no definitive method of identifying individuals at risk of developing psychopathology exists. The Aberdeen Trauma Screening Index (ATSI) is a brief screening tool developed for use in a clinical setting by non-mental health professionals to facilitate the early identification of individuals most at risk of psychopathology 3-months post-accident. METHODS: The ATSI derived from a prospective study of a 150 out of an initial pool of 213 consecutive admissions to the Orthopaedic Trauma Unit and the Accident and Emergency Department of Aberdeen Royal Infirmary. Potential predictors were identified by a comprehensive assessment conducted within 1-week post-accident. Outcome at 3-months post-accident was measured using 'caseness' according to the General Health Questionnaire (GHQ-28). RESULTS: The ATSI is based on a final model comprising only seven variables with a sensitivity of 79% and specificity of 65%. A predictive index score (0-100) was produced to ensure the practical utility of the ATSI in a clinical setting. A ROC curve was constructed to illustrate the relationship between sensitivity and the specificity values with their corresponding threshold scores. On the basis of a prevalence rate of 55% 'caseness', as identified in the present study, a cut-off point of 45 provides the optimal outcome with a sensitivity value of 70% and a specificity value of 71%. CONCLUSIONS: The ATSI can accurately identify those most at risk of developing psychopathology 3-months post-accident in a sample of accidentally injured adult subjects recruited as consecutive admissions to an urban hospital in the North East of Scotland. However, to establish the generalizability of these findings, it is important that the ATSI be validated in both similar and diverse populations.

Organochlorines and mercury in pilot whale blubber consumed by Faroe islanders.

Some 22,000 pilot whales (Globicephala melaena) were taken in the Faroe Islands between 1970 and 1992. It is known that tissues from these animals are widely consumed by the islanders. The position of these animals at the apex of a direct marine food chain renders them liable to accumulate toxic chemicals, such as metals and organochlorines. Although the consumption of contaminating metals in pilot whale tissues has been studied, the significance of blubber as a dietary source of organochlorine compounds has not been fully considered. This study reports levels of organochlorine and mercury contamination in the blubber of pilot whales taken in two Faroese kills. Published estimates of pilot whale tissue consumption are used to evaluate dietary organochlorine intake in relation to established national and international guidelines and clinical studies conducted in the North American Great Lakes.

Organochlorine contamination in pinnipeds.

Organochlorines, such as PCBs and DDT, are ubiquitous contaminants. Most studies reporting concentrations of organochlorines in pinnipeds have investigated ringed, grey, and harbour seals. Very few studies have been carried out on pinnipeds from the southern hemisphere. Pre-1980, the highest mean wet-weight blubber concentrations of DDT and related metabolites (911 +/- 582 micrograms g-1) were recorded in sea lions from California. The highest pre-1980 blubber concentrations of PCBs (1470 +/- 922 micrograms g-1) were recorded in harbour seals from the Netherlands. In later studies, the highest blubber concentrations of PCBs have been recorded from grey seals of the Dee estuary, UK [46.79 (10.17-116.68) micrograms g-1]. The highest DDT concentrations measured in individual pinnipeds appear to be in the 1-15 micrograms g-1 range, and such levels have been recorded from ringed, grey, and harbour seals and Australian fur seals. There are problems in identifying trends based on different studies. These include the improvement in analytical methods with time and the lack of uniformity in analytical methodology between laboratories as well as in the biological material analyzed. Insufficient standardized studies have been undertaken for a clear picture of temporal trends in DDT and PCB concentrations in pinniped tissues to be identified. Reported results show variations in contaminant concentrations between pinniped colonies from different sites, and special reference has been made to comparison of contaminant burdens between the UK colonies. Insufficient standardized information is currently available for patterns of contamination in pinnipeds to be assessed on a global scale. Many, although not all, studies have shown evidence for age and sex correlation for organochlorine concentrations in pinnipeds; male seals continuing to accumulate certain organochlorines throughout their lives; female seals accumulating these compounds until maturity when they lose part of their body burdens to their offspring via transplancental transfer and, more importantly, via lactation. The ability of pinnipeds to metabolize organochlorine compounds appears to be less well developed than in terrestrial mammals and seems to vary between seal species. Reported effects on pinnipeds, which have been suggested to result from organochlorine contamination, include skeletal deformities and impacts on reproduction, such as uterine blockages. The evidence of a relationship between recent epizootics in marine mammal populations and organochlorine pollution suggests that viruses and pollution are potential significant contributors to mortalities, but other factors, such as unseasonably warm temperatures and high seal densities, cannot be precluded.(ABSTRACT TRUNCATED AT 400 WORDS)

Full face protection in orthopaedics: a practical appliance for use in high risk cases.

A clear plastic, full-face visor is described which gives face, eye and neck protection during surgery. It has proved comfortable and light to wear, providing excellent, unobstructed vision and, unlike protective goggles and spectacles, it is not prone to condensation.