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Adding 1%Si to binary Al-5Mg alloy slightly increases the yield stress in comparison with the Si free alloy but dramatically reduces the ductility and tensile strength due to the formation of brittle eutectic Mg2Si and pi-Al8FeMg3Si6 particles. Adding 3%Si slightly reduces the yield stress, presumably due to some of the Mg being tied up in the Mg2Si, and further reduces the ductility due to the increased volume fraction of intermetallics. Solution heat treatment at 436degreesC decreases the yield stress of both Si containing alloys, and slightly increases the ductility in the alloy with 3%Si. Subsequent ageing at 180degreesC has no further effects on the strength or ductility. The loss in strength of the heat treated alloys seems to be due to overageing Of Mg2Si precipitates dispersed in the bulk of the alloy. (C) 2004 W. S. Maney Son Ltd.

The analytical expression for the average S tensor in Eshelby's equivalent inclusion method of internal stress determination in composite materials is derived for any transversely isotropic fiber orientation distribution function specified by a generic histogram. The analytical average provides a basis for direct application of experimentally measured fiber ODFs in the modelling of internal stresses and effective properties of thermomechanical fiber composites. Upper and lower bound estimates utilizing the analytical expression for the average S tensor are presented and discussed.

The ovoviviparous Littorina saxatilis (Olivi) can be found in many intertidal habitats. Winkles from different habitats have different morphologies and behaviours, which are usually argued to reflect adaptations. Whether the different forms are caused by genetic differentiation or due to phenotypic plasticity is, however, less discussed. Our aim was to document morphological and behavioural differences among one exposed rock poulation, one sheltered boulder population, and one mud flat population, and we reared offspring in a common laboratory environment to see if the differences persisted. We used principal component analysis (PCA), based on 19 measurements, to compare size and shape differences. We also used PCA and linear regression to study allometry and compare growth trajectories. Behavioural differences were studied in three laboratory trials. Littorina saxatillis from the rock were relatively small, had small aperture lips, thin shells, blunt spires, and wide columellae. They preferred to stay in cracks and to be above the water surface, and they quickly emerged out of their shells after disturbance. L. saxatillis from the boulder shore were relatively large, had large lips, thick shells, pointed spires, and narrow columellae. They preferred open surfaces, submergence, and after disturbance they slowly emerged out of the shell. L. Saxatilis from the mud flat were relatively small, had small lips, think shells, pointed spires, and narrow columellae and most behaved similarly to the boulder shore snails. Although less pronounced, most of these morphological and behavioural differences persisted in the snails that we reared in the common environment. This indicates some genetic differentiation. All groups grew allometrically, and most groups differed in growth trajectories, Despite similar ages, the reared females were generally larger than the reared males, indicating higher growth rate in females. Sexual maturation seemed to be reached at a certain size rather than at a certain age. Theories predict genetic diferentiation in intertidal snail species with low dispersal, but some investigations show results that contradict the theories, while others agree with them. Our study confirms the prediction that L. saxatilis should be genetically differentiated.

The concept of self-management in healthcare includes disease prevention, self-diagnosis, self-treatment and appropriate consultation with health care practitioners. Within the context of childrens' ailments the decision-maker will usually be a carer. The aim of this study was to examine carers' management of minor childhood ailments within urban and rural settings. The subjects were primary schoolchildren (4-12 years of age) and the respondents were their parents or carers. Data were gathered using a pre-piloted structured questionnaire. The questionnaires were distributed through and collected by the head teachers of the 13 participating schools. Of the 491 questionnaires distributed, 306 (62%) were returned and suitable for analysis. In total, 96 (31%) children had experienced a minor ailment in the preceding 2 weeks; the most commonly reported were cold, headache and gastrointestinal disturbance. Ninety-five respondents indicated how they managed this episode; the most common response was to treat the child with a medicine which they already had in the house (41%). A further 24 obtained a medicine specifically to manage the episode; 12 on prescription and 12 purchased an over-the-counter (OTC) medicine. The majority of respondents (86%) felt that they based their management decision on their own experience, only 10 felt their action was influenced by the advice of a pharmacist or doctor. Fifty children (16%) were reported to have a chronic illness. Several respondents volunteered comments suggesting that they would be cautious in their use of OTC medicines. This study indicates that in the majority of cases, carers manage children's minor ailments without recourse to professional advice.

The hardening rate of the matrix mean stress in planar random fibre aluminium composites with a range of fibre volume fractions is measured in cyclic Bauschinger experiments at room temperature and 77 K. A particular problem with predicting the mean stress hardening rate in these composites is that the plastic strain is not isotropic in the transverse directions. A method for quantifying the experimentally determined plastic flow in a form useful for this analysis is proposed. The difference between the predicted and measured mean stress hardening rates is smallest for low fibre volume fractions at 77 K. A model for relaxation of the plastic mean stress in the matrix is developed. It is based on the assumption that the rate controlling mechanism in these composites is cross slip of screw dislocations. The measured activation energy is independent of fibre volume fraction but the activation volume decreases with increasing fibre content. The magnitudes of activation energy and activation volume support the assumptions of the model.

Internal stresses in planar random alumina fibre reinforced aluminium with a range of fibre volume fractions have been studied theoretically and in tensile tests and cyclic Bauschinger experiments at room temperature and 77 K. The Eshelby S tensor for a planar random array of fibres is calculated, which allows the mean field model to be used to predict the internal stresses. The conventional Orowan-Wilson method of analysing cyclic Bauschinger experiments is modified, enabling the plastically and thermally induced matrix mean stresses to be separated. This analysis is applied to experimental results and the plastic mean stress and the initial magnitude of the thermal mean stress in the matrix are measured. The results for the thermal matrix mean stress are compared with measurements from monotonic flow curves and generally good agreement is observed. The measured thermal matrix mean stress in these composites is approximately independent of fibre volume fraction.

Background: Giant pulmonary bullae (GPB) are rare and there is little information on incidence, long-term prognosis, and outcome of treatment. Objectives: To assess the incidence of GPB in the Icelandic population and to evaluate the outcome of surgical treatment. Methods: Twelve consecutive patients (11 males; mean age 60 ± 15.7 years) underwent resection for GPBin Iceland between 1992 and 2009. All were heavy smokers and had bullae occupying > 30% of the involved lung. There were 8 bilateral and 3 unilateral bullectomies and one lobectomy. Pulmonary function tests were performed preoperatively, and at one month and 5.4 years postoperatively. Age-standardized incidence rate (ASR) was calculated, complications and operative mortality were registered, and overall survival was estimated. Mean follow-up time was 8.2 years. Results: The ASR for GPB was 0.40 and 0.03 per 100,000 per year for men and women, respectively. There was no operative mortality, but prolonged air leakage (75%) and pneumonia (17%) were the most common postoperative complications. One month postoperatively, mean FEV1 increased from 1.0 ± 0.48 L (33% predicted) to 1.75 ± 0.75 L (57.5% predicted) (p < 0.01), but FVC remained unchanged. RV decreased from 3.9 ± 0.8 L (177% predicted) to 3.0 ± 1.0 L (128% predicted) (p < 0.05), but TLC and DLCO did not change after operation. At long-term follow-up the FEV1 and FVC had declined to near-baseline values. Five-year and 10-year survival were 100% and 60%, respectively. Conclusions: The ASR of GPB in Iceland was 0.21 per 100,000 per year. In this small series, bullectomy was found to be a safe procedure that significantly improved pulmonary function. The functional improvement then declined over time. Prolonged air leakage was a common postoperative complication that prolonged hospital stay.

The concept of self-management in healthcare includes disease prevention, self-diagnosis, self-treatment and appropriate consultation with health care practitioners. Within the context of childrens' ailments the decision-maker will usually be a carer. The aim of this study was to examine carers' management of minor childhood ailments within urban and rural settings. The subjects were primary schoolchildren (4-12 years of age) and the respondents were their parents or carers. Data were gathered using a pre-piloted structured questionnaire. The questionnaires were distributed through and collected by the head teachers of the 13 participating schools. Of the 491 questionnaires distributed, 306 (62%) were returned and suitable for analysis. In total, 96 (31%) children had experienced a minor ailment in the preceding 2 weeks; the most commonly reported were cold, headache and gastrointestinal disturbance. Ninety-five respondents indicated how they managed this episode; the most common response was to treat the child with a medicine which they already had in the house (41%). A further 24 obtained a medicine specifically to manage the episode; 12 on prescription and 12 purchased an over-the-counter (OTC) medicine. The majority of respondents (86%) felt that they based their management decision on their own experience, only 10 felt their action was influenced by the advice of a pharmacist or doctor. Fifty children (16%) were reported to have a chronic illness. Several respondents volunteered comments suggesting that they would be cautious in their use of OTC medicines. This study indicates that in the majority of cases, carers manage children's minor ailments without recourse to professional advice.

In a short communication Grahame et al. (1992) argue against our finding that Littorina neglecta Bean is an ecotype of Littorina saxatilis (Olivi) rather than a separate species (Johannesson & Johannesson, 1990b). Unfortunately, Grahame et al. (1992) have miss-represented our earlier paper, and we feel the need to refute their arguments.In populations from north-western Europe we studied morphological characters used to separate Littorina neglecta from L. saxatilis. We found that intermediate shapes were common and, furthermore, we found no close coupling among characters used to define L. neglecta (Johannesson & Johannesson, 1990a). We further analysed the genetic variation in five strongly polymorphic allozyme loci. In four loci we found a pattern that indicated that L. neglecta is not reproductively isolated from L. saxatilis. In the fifth locus, Aat-1, we found consistent differences between populations of L. neglecta (from the low shore) and L. saxatilis (from the high shore). Similar differences were observed between low and high shore populations in Sweden where, however, no snails of neglecta-type were present.

Difficultes rencontrees dans la mesure de KIC des materiaux durs lors de la production de la prefissure. Rappel de la methode appelee «de l'indentation en pont» pour eviter ces difficultes appliquee a des composites WC-6% en poids Co. Extension a des materiaux de KIC>15 MN m −3/2 , tels que les carbures frittes a haute resistance (WC-15% Co a gros grains)

A356 aluminium matrix composites reinforced with continuous Altex alumina fibres were made with the squeeze infiltration process. Stage II hardening is measured and found to be equal to or slightly higher than the fibre contribution. These results and comparison with literature data indicates that in-situ matrix hardening, if any, is caused by the matrix microstructure rather than by the constraint of the fibres.