On the wear rate of an Sn11Sb5.5Cu Babbitt

The microstructure of β-phase of Sn11Sb5.5Cu Babbitt produced by casting and liquid forging has been analyzed by optical and scanning electron microscopy using EBSD analysis. It has been established that a significant decrease in the wear rate of Babbitt produced by liquid forging is caused by generation of fine grain structure in the particles of the β phase.     

Temporal aggregation and spurious instantaneous causality in multiple time series models

Large aggregation interval asymptotics are used to investigate the relation between Granger causality in disaggregated vector autoregressions (VARs) and associated contemporaneous correlation among innovations of the aggregated system. One of our main contributions is that we outline various conditions under which the informational content of error covariance matrices yields insight into the causal structure of the VAR. Monte Carlo results suggest that our asymptotic findings are applicable even when the aggregation interval is small, as long as the time series are not characterized by high levels of persistence.     

Beta-lactamase inhibitors: agents to overcome bacterial resistance

Parental illness can have a profound impact on family relationships and children's behaviour. The amount and nature of communication between parents and children about the illness can play an important role, both positively and negatively, in mediating the outcomes. When children have a disability, families can be reluctant to communicate with them about family difficulties. They are often concerned about the impact that parental unavailability may have on their child's life. This paper reports on three families in which the mother was diagnosed with breast cancer and one child in the family had a disability. The extent and specific characteristics of their communication about the maternal illness with their children, behavioural changes in the children, explanations of communication strategies and attributions of behavioural changes are described. Family coping strategies are examined with reference to Lazarus's process model of stress and coping and the use of either problem-focused or emotion-focused strategies. Implications for possible clinical interventions are proposed. In particular it is suggested that families be offered consultation about: what children might understand; ways in which to communicate effectively; and strategies for coping with the long-term implications of serious parental illness.     

The distribution of lead within ancient and modern human teeth: implications for long-term and historical exposure monitoring

The preservation of lead within human tissue makes it possible to monitor long-term exposure to the element and to model changing sources of lead pollution throughout the lifetime of an individual. Dental tissues have recently been shown to be particularly useful for this purpose. Enamel, for instance, forms at known stages of life and is chemically stable in vivo whereas dentine is remodelled in a predictable fashion. The relative stability of enamel is reflected in its excellent post-mortem preservation. This raises the possibility of using historical or archaeological material to reconstruct long-term trends and establish baseline data relating to exposure among pre-industrial or even prehistoric populations. The use of archaeological material is currently problematic, however, because of the site-specific nature of diagenesis and incomplete understanding of its chemistry, particularly in respect of lead uptake into dental tissue from the burial environment. A detailed study of lead distribution within both ancient and modern human teeth is presented. Conclusions are drawn on the pattern of lead distribution resulting from tissue formation and the manner of its alteration in the burial environment. In particular, attention is drawn to a consistent enrichment of lead within the outer 30 microns of the enamel of both ancient and modern teeth which appears to be unrelated to diagenesis. The implications for current approaches to long-term monitoring and for the reconstruction of historical and archaeological exposure patterns are discussed.     

Amplified enzyme-linked-immunofilter assays enable detection of 50-10(5) bacterial cells within 1 hour

1. The hydrolysis of organophosphate pesticides (OP) and nerve gases by serum paraoxonase (PON1) is an important factor determining their toxicity to mammals including man. The PON1 gene contains 2 polymorphic sites at amino acid positions 55 (L-->M) and 192 (G-->A, classically defined as the A and B genotypes) which result in several alloenzymes of PON1 in human serum. 2. The 192 polymorphism has previously been shown to affect PON1 activity. We have investigated the effect of both polymorphisms on the hydrolysis of paraoxon by serum from 279 healthy human subjects. 3. The 55 polymorphism significantly influenced PON1 activity. MM homozygotes had over 50% less activity towards paraoxon compared to the LL and LM genotypes regardless of the 192 genotype (P < 0.001). 4. Multiple regression analysis indicated that the 192 polymorphism, 55 polymorphism and serum PON1 concentration were responsible for 46, 16 and 13% of the variation in PON1 activity, respectively (all P < 0.001). None of the other parameters investigated significantly affected PON1 activity. 5. Therefore both PON1 polymorphisms affect the hydrolysis of paraoxon. AA/MM and AB/MM individuals may be potentially more susceptible to OP intoxication. 6. Genotyping individuals for both PON1 polymorphisms may provide a method for identifying those individuals at most risk of OP poisoning. The effect of PON1 polymorphisms on activity may also explain why some Gulf War Veterans have developed Gulf War Syndrome and some have not.