Birth order, gestational age, and risk of delivery related perinatal death in twins: retrospective cohort study

Objective: To determine whether twins born second are at increased risk of perinatal death because of complications during labour and delivery. Design: Retrospective cohort study. Setting: Scotland, 1992 and 1997. Participants: All twin births at or after 24 weeks' gestation, excluding twin pairs in which either twin died before labour or delivery or died during or after labour and delivery because of congenital abnormality, non-immune hydrops, or twin to twin transfusion syndrome. Main outcome measure: Delivery related perinatal deaths (deaths during labour or the neonatal period). Results: Overall, delivery related perinatal deaths were recorded for 23 first twins only and 23 second twins only of 1438 twin pairs born before 36 weeks (preterm) by means other than planned caesarean section (P>0.99). No deaths of first twins and nine deaths of second twins (P=0.004) were recorded among the 2436 twin pairs born at or after 36 weeks (term). Discordance between first and second twins differed significantly in preterm and term births (P=0.007). Seven of nine deaths of second twins at term were due to anoxia during the birth (2.9 (95% confidence interval 1.2 to 5.9) per 1000); five of these deaths were associated with mechanical problems with the second delivery following vaginal delivery of the first twin. No deaths were recorded among 454 second twins delivered at term by planned caesarean section. Conclusions: Second twins born at term are at higher risk than first twins of death due to complications of delivery. Previous studies may not have shown an increased risk because of inadequate categorisation of deaths, lack of statistical power, inappropriate analyses, and pooling of data about preterm births and term births

A Study of Evaporation Heat Transfer Coefficient Correlations at Low Heat and Mass Fluxes for Pure Refrigerants and Refrigerant Mixtures

An average R12 refrigerant correlation has been developed for the mass flux range of 25-100 kg/m2-s and the heat flux range of 2-10 kW/m2. Refrigerant mixtures of 80% R22/lO% R141b and 65% R22/35% R123 have also been tested over asjrniJar range of conditions. Mixture heat transfer coefficients have been detennined and correlations for each mixture pair are presented. The R221R141b average correlation may have a strong dependence on changes in surface tension. The heat transfer coefficient of R22JR141b compares well with that of R12. The heat transfer coefficient of R22/R123 severely under performs R12.Air Conditioning and Refrigeration Center Project 0

Wealth portfolios in the US and the UK

In this paper, we attempt to explain differences between the US and UK household wealth distributions, with an emphasis on the quite different porfolios held in stock and housing equities in the two countries. As a proportion of their total wealth, British households hold relatively small amounts of financial assets - including equities in stock - compared to American households. In contrast, British households appear to move into home ownership at relatively young ages and a large fraction of their household wealth is concentrated in houseing. Finally, the age gradient in home equity appears to be much steeper in the UK while US households exhibit a steeper age gradient in stock equity. We argue that the higher price housing price volatility in the UK combined with much younger entry into home ownership there are important factors accounting for the relatively small participation of young British householders in the stock market. We show it is important to acknowledge the dual role of housing - providing both wealth and consumption services - in understanding wealth accumulation differences between the US and the UK. Institutional differences, particularly in housing markets, that affect the demand and supply of housing services, turn out to be important in generating portfolio differences between the two countries. In particular, these differences in housing price risk imply steeper life-cycle accumulations in housing and less steep accumulation in stock equity over the life cycle in the UK

The SES health gradient on both sides of the Atlantic

In this paper we investigate the size of health differences that exist among men in England and the United States and how those differences vary by Socio-Economic Status (SES) in both countries. Three SES measures are emphasized - education, household income, and household wealth - and the health outcomes investigated span multiple dimensions as well. International comparisons have played a central part of the recent debate involving the 'SES health gradient' with some authors citing cross-country differences in levels of income equality and mortality as among the most compelling evidence that unequal societies have negative impacts on individual health outcomes. In spite of the analytical advantages of making such international comparisons, until recently good micro data measuring both SES and health in comparable ways have not been available for both countries. Fortunately, that problem has been remedied with the fielding of two surveys - the Health and Retirement Survey (HRS) and the English Longitudinal Survey of Aging (ELSA). In order to facilitate the type of research represented in this paper, both the health and SES measures in ELSA and HRS were purposely constructed to be as directly comparable as possible. Our analysis presents data on some of the most salient issues regarding the social health gradient in health and the manner in which this health gradient differs for men across the two countries in question. There are a several key findings. First, looking across a wide variety of diagnosed diseases, average health status among mature men is much worse in America compared to England, confirming non-gender specific findings we reported in earlier research. Second, there exists a steep negative health gradient for men in both countries where men at the bottom of the economic hierarchy are in much worse health than those at the top. This social health gradient exists whether education, income, or financial wealth is used as the marker of SES. While the negative social gradient in male health characterizes men in both countries, it appears to be steeper in the United States. These central conclusions are maintained even after controlling for a standard set of behavioral risk factors such as smoking, drinking, and obesity and are equally true using either biological measures of disease or individual self-reports. In contrast to these disease based measures of health, the health of American men appears to be superior to the health of English men when self-reported subjective general health status is used as the measure of health status. This apparent contradiction does not result from differences in co-morbidity, emotional health, or ability to function all of which still point to mature American men being less healthy than their English counterparts. The contradiction most likely stems instead from different thresholds used by Americans and English when evaluation their health status on subjective scales. For the same 'objective' health status, Americans are much more likely to say that their health is good than are the English. Finally, we present preliminary data that indicates that feedbacks from new health events to household income are also one of the reasons that underlie the strength of the income gradient with health in England. Previous research has demonstrated its importance as one of the underlying causes in the United States and these results suggest that that conclusion should most likely be extended to England as well although further research is required on this topic

Suicide in Scottish military veterans: a 30-year retrospective cohort study

Background: Although reassuring data on suicide risk in UK veterans of the 1982 Falklands conflict and 1991 Gulf conflict have been published, there have been few studies on long-term overall suicide risk in UK veterans. Aims: To examine the risk of suicide in a broad population-based cohort of veterans in Scotland, irrespect ive of length of service or exposure to conflict, in comparison with people having no record of military service. Methods: A retrospective 30-year cohort study of 56205 veterans born 1945–85 and 172741 matched non-veterans, using Cox proportional hazard models to compare the risk of suicide and fatal self-harm overall, by sex, birth cohort, length of service and year of recruitment. Results: There were 267 (0.48%) suicides in the veterans compared with 918 (0.53%) in non-veterans. The difference was not statistically significant overall [adjusted hazard ratio (HR) 0.99; 95% confidence interval (CI) 0.86–1.13]. The incidence was lower in younger veterans and higher in veterans aged over 40. Early service leavers were at non-significantly increased risk (adjusted HR 1.13; 95% CI 0.91–1.40) but only in the older age groups. Women veterans had a significantly higher risk of suicide than non-veteran women (adjusted HR 2.44; 95% CI 1.32–4.51, P < 0.01) and comparable risk to veteran men. Methods of suicide did not differ significantly between veterans and non-veterans, for either sex. Conclusions: The Scottish Veterans Health Study adds to the emerging body of evidence that there is no overall difference in long-term risk of suicide between veterans and non-veterans in the UK. However, female veterans merit further study

Predicting cesarean section and uterine rupture among women attempting vaginal birth after prior cesarean section

<p><b>Background:</b> There is currently no validated method for antepartum prediction of the risk of failed vaginal birth after cesarean section and no information on the relationship between the risk of emergency cesarean delivery and the risk of uterine rupture.</p> <p><b>Methods and Findings:</b> We linked a national maternity hospital discharge database and a national registry of perinatal deaths. We studied 23,286 women with one prior cesarean delivery who attempted vaginal birth at or after 40-wk gestation. The population was randomly split into model development and validation groups. The factors associated with emergency cesarean section were maternal age (adjusted odds ratio [OR] = 1.22 per 5-y increase, 95% confidence interval [CI]: 1.16 to 1.28), maternal height (adjusted OR = 0.75 per 5-cm increase, 95% CI: 0.73 to 0.78), male fetus (adjusted OR = 1.18, 95% CI: 1.08 to 1.29), no previous vaginal birth (adjusted OR = 5.08, 95% CI: 4.52 to 5.72), prostaglandin induction of labor (adjusted OR = 1.42, 95% CI: 1.26 to 1.60), and birth at 41-wk (adjusted OR = 1.30, 95% CI: 1.18 to 1.42) or 42-wk (adjusted OR = 1.38, 95% CI: 1.17 to 1.62) gestation compared with 40-wk. In the validation group, 36% of the women had a low predicted risk of caesarean section (<20%) and 16.5% of women had a high predicted risk (>40%); 10.9% and 47.7% of these women, respectively, actually had deliveries by caesarean section. The predicted risk of caesarean section was also associated with the risk of all uterine rupture (OR for a 5% increase in predicted risk = 1.22, 95% CI: 1.14 to 1.31) and uterine rupture associated with perinatal death (OR for a 5% increase in predicted risk = 1.32, 95% CI: 1.02 to 1.73). The observed incidence of uterine rupture was 2.0 per 1,000 among women at low risk of cesarean section and 9.1 per 1,000 among those at high risk (relative risk = 4.5, 95% CI: 2.6 to 8.1). We present the model in a simple-to-use format.</p> <p><b>Conclusions:</b> We present, to our knowledge, the first validated model for antepartum prediction of the risk of failed vaginal birth after prior cesarean section. Women at increased risk of emergency caesarean section are also at increased risk of uterine rupture, including catastrophic rupture leading to perinatal death.</p&gt

Determining military expenditures: arms races and spill-over effects in cross-section and panel data

This paper considers the determinants of military spending, building on an emerging literature that estimates military expenditure demand functions in cross-section and panel data, incorporating ‘arms-race’ type effects. It updates Dunne and Perlo-Freeman (2003b) using the SIPRI military expenditure database for the period 1988-2003, finding broadly similar results. It also shows differences in results across panel methods, particularly the within and between estimates and illustrates the importance of recognising and modelling dynamic processes within panel data. Heterogeneity is also found to be an important issue and when countries are broken up into groups on the basis of per capita income there is no obvious systematic pattern in the results. This is seen to imply that the demand for military spending, even between two mutually hostile powers, may depend on the whole nature of the relationship between them (and other countries and events in the region), and not simply Richardsonian action-reaction patterns

Housing price volatility and downsizing in later life

In this paper, we modeled several types of housing transitions of the elderly in two countries -- Britain and the United States. One important form of these transitions involves downsizing of housing consumption, the importance of which among older households is still debated. This downsizing takes multiple forms, including reductions in the number of rooms per dwelling and the value of the home. There is also evidence that this downsizing is greater when house price volatility is greater and that American households try to escape housing price volatility by moving to places that are experience significantly less housing price volatility. Our comparative evidence in suggests that there is less evidence of downsizing in Britain. Our results indicate that housing consumption appears to decline with age in the US, even after controlling for the other demographic and work transitions associated with age that would normally produce such a decline. No such fall in housing consumption is found in Britain, largely because British households are much more likely to stay in their original residence

Are Americans Really Less Happy With Their Incomes?

Recent economic research on international comparisons of subjective well-being suffers from several important biases due to the potential incomparability of response scales within and across countries. In this paper we concentrate on self-reported satisfaction with income in two countries: The Netherlands and the U.S. The comparability problem is addressed by using anchoring vignettes. We find that in the raw data, Americans appear decidedly less satisfied with their income than the Dutch. It turns out however that after response scale adjustment based on vignettes the distribution of satisfaction in the two countries is essentially identical. In addition, we find that the within-country cross-sectional effect of income on satisfaction- a key parameter in the recent debate in the economic literature- is significantly under-estimated especially in the US- when differences in response scales are not taken into account.happiness;life satisfaction;vignettes;reporting bias

Dynamics of Work Disability and Pain

This paper investigates the role of pain in affecting self-reported work disability and employment of elderly workers in the US.We investigate pain and its relationship to work disability and work in a dynamic panel data model, using six biennial waves from the Health and Retirement Study.We find the dynamics of the presence of pain is central to understanding the dynamics of self-reported work disability.By affecting work disability pain also has important implications for the dynamic patterns of employment.Work limiting disability;health