The effect of alternate heating rates during cure on the structure-property relationships of epoxy/MMT clay nanocomposites

This paper investigates the effect of both the mixing technique and heating rate during cure on the dispersion of montmorillonite (MMT) clay in an epoxy resin. The combination of sonication and using a 10. °C/min heating rate during cure was found to facilitate the dispersion of nanoclay in epoxy resin. These processing conditions provided a synergistic effect, making it possible for polymer chains to penetrate in-between clay galleries and detach platelets from their agglomerates. As the degree of dispersion was enhanced, the flexural modulus and strength properties were found to decrease by 15% and 40%, respectively. This is thought to be due to individual platelets fracturing in the nanocomposite. Complementary techniques including X-ray diffraction (XRD), small angle X-ray scattering (SAXS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM) and optical microscopy were essential to fully characterise localised and spatial regions of the clay morphologies.

Microstructure-property relationship of the high strength low alloy steels during tensile testing at high strain rates

Positive The influence of strain-rate on the room temperature mechanical properties of the Dual-Phase and Transformation Induced Plasticity (TRIP) steels was investigated.The results showed that both the plastic strain, and strength properties increased with increasing strain rates at high strain rates.At strain rates lower than approximateil 1s ~ (-1) the properties no longer have an advantageous proportionality to strain rate and remain strain rate neutral.Possible explanations are offered for trends exhibited, in terms of thermal and athermal considerations, in relation to the respective microstructures of the two steels

Rates of common communicable illnesses in non-anaemic 12-24 month old South Island, New Zealand children

Aims : To describe the incidence of parentally reported illness in otherwise healthy South Island toddlers; characterise the predictors of illness; and determine whether there was a relationship between teething and illness in this population.

Methods : A 20-week randomised controlled trial was conducted on 1-year-old children (n=225) from Otago and Southland between February 2004 and December 2005. Information on symptoms of morbidity, occurrence of teething, and childcare attendance were recorded daily throughout the intervention period. Morbidity symptoms were categorised into respiratory illness (RI), gastrointestinal illness (GII), ear infection, and total illness, and the number and duration of events were determined.

Results : The mean (SD) number of total illnesses was 3.4 (2.3) per 20 weeks, with an average duration of 4.5 days. Episodes of RI were most common (50% of total illness events), and tended to be the longest in duration (mean of 3.7 days). Having siblings aged less than 5 years (23% increase, 95%CI 6%–42%, p=0.007) and attending childcare (72% increase, 95%CI 38%–113%, p<0.001)), were positively associated with the number of total illness events but not duration. In addition, teething was positively associated with total events (OR 1.94, 95%CI 1.45–2.60, p<0.001), RI events (OR 2.03, 95%CI 1.41–2.93, p<0.001) and GII events (OR 1.90, 95%CI 1.36–2.67, p<0.001).

Conclusion : This study has shown that illness (particularly RI) is common in the second year of life. It has also confirmed that attending childcare and having siblings aged under 5 years increases the number of illness events. An association between teething and the occurrence of illness was also seen but the exact nature of this relationship requires verification.

Contribution of climate and air pollution to variation in coronary heart disease mortality rates in England

There are substantial geographic variations in coronary heart disease (CHD) mortality rates in England that may in part be due to differences in climate and air pollution. An ecological cross-sectional multi-level analysis of male and female CHD mortality rates in all wards in England (1999–2004) was conducted to estimate the relative strength of the association between CHD mortality rates and three aspects of the physical environment - temperature, hours of sunshine and air quality. Models were adjusted for deprivation, an index measuring the healthiness of the lifestyle of populations, and urbanicity. In the fully adjusted model, air quality was not significantly associated with CHD mortality rates, but temperature and sunshine were both significantly negatively associated (p<0.05), suggesting that CHD mortality rates were higher in areas with lower average temperature and hours of sunshine. After adjustment for the unhealthy lifestyle of populations and deprivation, the climate variables explained at least 15% of large scale variation in CHD mortality rates. The results suggest that the climate has a small but significant independent association with CHD mortality rates in England.

Some empirical evidence on offender time discount rates

The conventional wisdom is that offenders have very high discount rates not only with respect to income and fines but also with respect to time incarcerated. These rates are difficult to measure objectively and the usual approach is to ask subjects hypothetical questions and infer time preference from their answers. In this article, we propose estimating rates at which offenders discount time incarcerated by specifying their equilibrium plea, defined as the discount rate, which equates the time and expected time spent in jail following a guilty plea and a trial. Offenders are assumed to exhibit positive time preference and discount time spent in jail at a constant rate. Our choice of sample is interesting because the offenders are not on bail, punishment is not delayed and the offences are planned therefore conforming to Becker’s model of the decision to commit a crime. Contrary to the discussion in the literature, we do not find evidence of consistently high time discount rates, and therefore cannot unequivocally infer that the prison experience always results in low levels of specific deterrence.

Age-specific trends in cardiovascular mortality rates in Australia between 1980 and 2005

Aim: Recent analyses suggest the decline in coronary heart disease (CHD) mortality rates is slowing in younger age groups in countries such as the UK and US. We aimed to assess recent mortality rate trends in all circulatory disease and its subtypes in Australia.

Methods: Annual all circulatory, CHD, and cerebrovascular disease mortality rates between 1980 and 2005 for Australia were analysed. Data were stratified by sex and ten-year age group (age 35 to 85+). The annual rate of change and significant changes in trends were identified using joinpoint Poisson regression.

Results: Age standardised all circulatory disease mortality rates continue to decline in Australia, falling from 441 per 100,000 in 1980 to 145 per 100,000 in 2005 for males and from 264 per 100,000 to 96 per 100,000 for females. The rate of decline from both CHD and cerebrovascular disease appears to be stable or accelerating for individuals aged 55 years and over. However, the decline in young men and women aged 35-54 years is slowing for CHD and cerebrovascular disease mortality alike (except cerebrovascular disease mortality in males aged 35-44). For females aged 35-44 and 45-54 there has been no change in the cerebrovascular mortality rate since 1993 and 1999, respectively.

Conclusions: In Australia, whilst in older adults the decline in cardiovascular mortality rates is generally accelerating, in younger adults it appears to be slowing. It will be important to identify the causes of these trends.

Effects of continuity of care by a primary midwife (caseload midwifery) on caesarean section rates in women of low obstetric risk : the COSMOS randomised controlled trial

Objective  To determine whether primary midwife care (caseload midwifery) decreases the caesarean section rate compared with standard maternity care.

Design  Randomised controlled trial.

Setting  Tertiary-care women’s hospital in Melbourne, Australia.

Population  A total of 2314 low-risk pregnant women.

Methods  Women randomised to caseload received antenatal, intrapartum and postpartum care from a primary midwife with some care by ‘back-up’ midwives. Women randomised to standard care received either midwifery or obstetric-trainee care with varying levels of continuity, or community-based general practitioner care.

Main outcome measures  Primary outcome: caesarean birth. Secondary outcomes included instrumental vaginal births, analgesia, perineal trauma, induction of labour, infant admission to special/neonatal intensive care, gestational age, Apgar scores and birthweight.

Results  In total 2314 women were randomised–1156 to caseload and 1158 to standard care. Women allocated to caseload were less likely to have a caesarean section (19.4% versus 24.9%; risk ratio [RR] 0.78; 95% CI 0.67–0.91; P = 0.001); more likely to have a spontaneous vaginal birth (63.0% versus 55.7%; RR 1.13; 95% CI 1.06–1.21; P < 0.001); less likely to have epidural analgesia (30.5% versus 34.6%; RR 0.88; 95% CI 0.79–0.996; P = 0.04) and less likely to have an episiotomy (23.1% versus 29.4%; RR 0.79; 95% CI 0.67–0.92; P = 0.003). Infants of women allocated to caseload were less likely to be admitted to special or neonatal intensive care (4.0% versus 6.4%; RR 0.63; 95% CI 0.44–0.90; P = 0.01). No infant outcomes favoured standard care.

Conclusion  In settings with a relatively high baseline caesarean section rate, caseload midwifery for women at low obstetric risk in early pregnancy shows promise for reducing caesarean births.

Age-specific trends in cardiovascular mortality rates in the Netherlands between 1980 and 2009

Recent analyses suggest the decline in coronary heart disease mortality rates is slowing in younger age groups in countries such as the US and the UK. This work aimed to analyse recent trends in cardiovascular mortality rates in the Netherlands. Analysis was of annual all circulatory, ischaemic heart disease (IHD), and cerebrovascular disease mortality rates between 1980 and 2009 for the Netherlands. Data were stratified by sex and 10-year age group (age 35–85+). The annual rate of change and significant changes in the trend were identified using joinpoint Poisson regression. For almost all age and sex groups examined the rate of IHD and cerebrovascular disease mortality in the Netherlands has more than halved between 1980 and 2009. The decline in mortality from both IHD and cerebrovascular disease is continuing for all ages and sex groups, with anacceleration in the decline apparent from the late 1990s/early 2000s. The decline in age-specific all circulatory, coronary heart disease and cerebrovascular disease mortality rates continues for all age and sex groups in the Netherlands.

The impact of climate variability and change on cryptosporidiosis and giardiasis rates in New Zealand

Aim: To investigate the spatial relationship between climate variability and cryptosporidiosis and giardiasis notifications in New Zealand between 1997 and 2006.

Methods: Negative binomial regression was used to analyse spatial relationships between cryptosporidiosis and giardiasis notifications in New Zealand between 1997 and 2006, and climatological average rainfall and temperature at the Census Area Unit (CAU) level. The quality of domestic water supplies, urban-rural status and deprivation were included as covariates.

Main results: Giardiasis: There was a positive association between rainfall and giardiasis and between temperature and giardiasis.

Cryptosporidiosis: There was a positive association between rainfall and cryptosporidiosis and a negative association between temperature and cryptosporidiosis. The effect of rainfall was modified by the quality of the domestic water supply.

Conclusions: These findings suggest that climate variability affects protozoan disease rates in New Zealand. However, predicting the effect of climate change from this study is difficult, as these results suggest that the projected increases in temperature and rainfall may have opposing effects on cryptosporidiosis rates. Nevertheless, water supply quality appeared to modify the impact of increased rainfall on cryptosporidiosis rates. This finding suggests that improving water supply quality in New Zealand could reduce vulnerability to the impact of climate change on protozoan diseases.