Higher Apparent Gas Transfer Velocities for CO2 Compared to CH4 in Small Lakes.

Large greenhouse gas emissions occur via the release of carbon dioxide (CO2) and methane (CH4) from the surface layer of lakes. Such emissions are modeled from the air-water gas concentration gradient and the gas transfer velocity (k). The links between k and the physical properties of the gas and water have led to the development of methods to convert k between gases through Schmidt number normalization. However, recent observations have found that such normalization of apparent k estimates from field measurements can yield different results for CH4 and CO2. We estimated k for CO2 and CH4 from measurements of concentration gradients and fluxes in four contrasting lakes and found consistently higher (on an average 1.7 times) normalized apparent k values for CO2 than CH4. From these results, we infer that several gas-specific factors, including chemical and biological processes within the water surface microlayer, can influence apparent k estimates. We highlight the importance of accurately measuring relevant air-water gas concentration gradients and considering gas-specific processes when estimating k.

Turbulence in a small boreal lake: Consequences for air-water gas exchange.

The hydrodynamics within small boreal lakes have rarely been studied, yet knowing whether turbulence at the air-water interface and in the water column scales with metrics developed elsewhere is essential for computing metabolism and fluxes of climate-forcing trace gases. We instrumented a humic, 4.7 ha, boreal lake with two meteorological stations, three thermistor arrays, an infrared (IR) camera to quantify surface divergence, obtained turbulence as dissipation rate of turbulent kinetic energy (ε) using an acoustic Doppler velocimeter and a temperature-gradient microstructure profiler, and conducted chamber measurements for short periods to obtain fluxes and gas transfer velocities (k). Near-surface ε varied from 10-8 to 10-6 m2 s-3 for the 0-4 m s-1 winds and followed predictions from Monin-Obukhov similarity theory. The coefficient of eddy diffusivity in the mixed layer was up to 10-3 m2 s-1 on the windiest afternoons, an order of magnitude less other afternoons, and near molecular at deeper depths. The upper thermocline upwelled when Lake numbers (L N ) dropped below four facilitating vertical and horizontal exchange. k computed from a surface renewal model using ε agreed with values from chambers and surface divergence and increased linearly with wind speed. Diurnal thermoclines formed on sunny days when winds were < 3 m s-1, a condition that can lead to elevated near-surface ε and k. Results extend scaling approaches developed in the laboratory and for larger water bodies, illustrate turbulence and k are greater than expected in small wind-sheltered lakes, and provide new equations to quantify fluxes.

Does IQ explain socio-economic differentials in total and cardiovascular disease mortality? Comparison with the explanatory power of traditional cardiovascular disease risk factors in the Vietnam Experience Study.

AIMS: The aim of this study was to examine the explanatory power of intelligence (IQ) compared with traditional cardiovascular disease (CVD) risk factors in the relationship of socio-economic disadvantage with total and CVD mortality, that is the extent to which IQ may account for the variance in this well-documented association. METHODS AND RESULTS: Cohort study of 4289 US male former military personnel with data on four widely used markers of socio-economic position (early adulthood and current income, occupational prestige, and education), IQ test scores (early adulthood and middle-age), a range of nine established CVD risk factors (systolic and diastolic blood pressure, total blood cholesterol, HDL cholesterol, body mass index, smoking, blood glucose, resting heart rate, and forced expiratory volume in 1 s), and later mortality. We used the relative index of inequality (RII) to quantify the relation between each index of socio-economic position and mortality. Fifteen years of mortality surveillance gave rise to 237 deaths (62 from CVD and 175 from 'other' causes). In age-adjusted analyses, as expected, each of the four indices of socio-economic position was inversely associated with total, CVD, and 'other' causes of mortality, such that elevated rates were evident in the most socio-economically disadvantaged men. When IQ in middle-age was introduced to the age-adjusted model, there was marked attenuation in the RII across the socio-economic predictors for total mortality (average 50% attenuation in RII), CVD (55%), and 'other' causes of death (49%). When the nine traditional risk factors were added to the age-adjusted model, the comparable reduction in RII was less marked than that seen after IQ adjustment: all-causes (40%), CVD (40%), and 'other' mortality (43%). Adding IQ to the latter model resulted in marked, additional explanatory power for all outcomes in comparison to the age-adjusted analyses: all-causes (63%), CVD (63%), and 'other' mortality (65%). When we utilized IQ in early adulthood rather than middle-age as an explanatory variable, the attenuating effect on the socio-economic gradient was less pronounced although the same pattern was still present. CONCLUSION: In the present analyses of socio-economic gradients in total and CVD mortality, IQ appeared to offer greater explanatory power than that apparent for traditional CVD risk factors.

Deprivation amplification revisited; or, is it always true that poorer places have poorer access to resources for healthy diets and physical activity?

BACKGROUND: It has commonly been suggested (including by this author) that individual or household deprivation (for example, low income) is amplified by area level deprivation (for example, lack of affordable nutritious food or facilities for physical activity in the neighbourhood). DISCUSSION: The idea of deprivation amplification has some intuitive attractiveness and helps divert attention away from purely individual determinants of diet and physical activity, and towards health promoting or health damaging features of the physical and social environment. Such environmental features may be modifiable, and environmental changes may help promote healthier behaviors. However, recent empirical examination of the distribution of facilities and resources shows that location does not always disadvantage poorer neighbourhoods. This suggests that we need: a) to ensure that theories and policies are based on up-to-date empirical evidence on the socio-economic distribution of neighbourhood resources, and b) to engage in further research on the relative importance of, and interactions between, individual and environmental factors in shaping behavior. SUMMARY: In this debate paper I suggest that it may not always be true that poorer neighbourhoods are more likely to lack health promoting resources, and to be exposed to more health damaging resources. The spatial distribution of environmental resources by area socioeconomic status may vary between types of resource, countries, and time periods. It may also be that the presence or absence of resources is less important than their quality, their social meaning, or local perceptions of their accessibility and relevance.

Obstetrician-assessed maternal health at pregnancy predicts offspring future health.

BACKGROUND: We aimed to examine the association between obstetrician assessment of maternal physical health at the time of pregnancy and offspring cardiovascular disease risk. METHODS AND PRINCIPAL FINDINGS: We examined this association in a birth cohort of 11,106 individuals, with 245,000 person years of follow-up. We were concerned that any associations might be explained by residual confounding, particularly by family socioeconomic position. In order to explore this we used multivariable regression models in which we adjusted for a range of indicators of socioeconomic position and we explored the specificity of the association. Specificity of association was explored by examining associations with other health related outcomes. Maternal physical health was associated with cardiovascular disease: adjusted (socioeconomic position, complications of pregnancy, birthweight and childhood growth at mean age 5) hazard ratio comparing those described as having poor or very poor health at the time of pregnancy to those with good or very good health was 1.55 (95%CI: 1.05, 2.28) for coronary heart disease, 1.91 (95%CI: 0.99, 3.67) for stroke and 1.57 (95%CI: 1.13, 2.18) for either coronary heart disease or stroke. However, this association was not specific. There were strong associations for other outcomes that are known to be related to socioeconomic position (3.61 (95%CI: 1.04, 12.55) for lung cancer and 1.28 (95%CI:1.03, 1.58) for unintentional injury), but not for breast cancer (1.10 (95%CI:0.48, 2.53)). CONCLUSIONS AND SIGNIFICANCE: These findings demonstrate that a simple assessment of physical health (based on the appearance of eyes, skin, hair and teeth) of mothers at the time of pregnancy is a strong indicator of the future health risk of their offspring for common conditions that are associated with poor socioeconomic position and unhealthy behaviours. They do not support a specific biological link between maternal health across her life course and future risk of cardiovascular disease in her offspring.

Pathways to obesity: identifying local, modifiable determinants of physical activity and diet.

Many studies document small area inequalities in morbidity and mortality and show associations between area deprivation and health. However, few studies unpack the "black box" of area deprivation to show which specific local social and physical environmental characteristics impact upon health, and might be amenable to modification. We theorised a model of the potential causal pathways to obesity and employed path analysis using a rich data set from national studies in England and Scotland to test the model empirically. Significant associations between obesity and neighbourhood disorder and access to local high street facilities (local shops, financial services and health-related stores found in a typical small UK town) were found. There was a tendency for lower levels of obesity in areas with more swimming pools and supermarkets. In turn, policing levels, physical dereliction and recorded violent crime were associated with neighbourhood disorder. The analysis identifies several factors that are associated with (and are probably determinants of) obesity and which are outside the standard remit of the healthcare sector. They highlight the role that public and private sector organisations have in promoting the nation's health. Public health professionals should seek to work alongside or within these organisations to capitalise on opportunities to improve health.

Childhood IQ in relation to risk factors for premature mortality in middle-aged persons: the Aberdeen Children of the 1950s study.

OBJECTIVE: A series of studies have shown an association between high childhood IQ scores and reduced rates of total mortality in adulthood. Several mechanisms have been advanced to explain these relationships, including mediation via established risk factors. This study examines the association between childhood IQ and a range of established physiological and behavioural risk factors for premature mortality in adulthood. DESIGN, SETTING AND PARTICIPANTS: In 1962, 12,150 children took part in a school-based survey when their IQ scores were extracted from educational records. When re-surveyed forty years later (n = 7183; 63.7% response), they self-reported information on risk factors for premature mortality (smoking, heavy alcohol consumption, obesity, height, hypertension and diabetes). MAIN RESULTS: In sex-adjusted analyses based on an analytical sample of 5340 (2687 women), higher childhood IQ scores were associated with a decreased prevalence of ever having smoked regularly in adulthood (OR(per SD increase in IQ) (95% CI): 0.77 (0.73 to 0.81)), heavy alcohol consumption (0.89 (0.84 to 0.94)), obesity (0.78 (0.72 to 0.83)) and overweight (0.86 (0.81 to 0.91)). Higher IQ scores were similarly related to a reduced prevalence of short stature and higher rates of smoking cessation in smokers; effects that were stronger in women (p value for interaction: < or =0.04). Adjusting for indicators of early and, particularly, later-life socioeconomic circumstances led to heavy attenuation of these gradients with statistical significance at conventional levels lost in most analyses. CONCLUSIONS: The IQ-risk factor gradients reported may offer some insights into the apparent link between high pre-adult IQ and reduced mortality rates.

Does the primary school attended influence self-reported health or its risk factors in later life? Aberdeen Children of the 1950s Study.

BACKGROUND: Adult health and its determinants are influenced by the environment in childhood. The school attended is known to affect the health behaviours of pupils while still at school. Little is known about the long-term influence of school attended on health. METHODS: A total of 7,095 respondents (mean age 47 years) to a follow-up questionnaire who attended primary school in Aberdeen, UK, provided information on self-reported health; self-reported high blood pressure; GHQ-4; smoking status; alcohol intake; and obesity. Variance partition coefficients (VPCs) summarized the variation in adult health outcomes and behaviours across schools. Multilevel logistic regression was used to estimate the contribution of school to variation in the outcomes taking into account individual-level and school-level factors. RESULTS: There was some variation across schools in the proportion of adults reporting poor self-rated health (VPC = 0.020) and smoking (0.019). Higher VPCs were found for factors potentially confounded with school: paternal social classes (I&II) (0.45) and gender (0.44). Age at leaving secondary education (0.28) and income (0.10) varied across schools. The effects of primary school diminished after adjusting for individual-level childhood risk factors. The further addition of adult risk factors attenuated these childhood effects. After full adjustment there was no effect of the primary school attended for high blood pressure, current smoking, alcohol intake, and obesity, and negligible effects for the other outcomes. CONCLUSIONS: Contrary to our expectations, we found little evidence of any relationship between primary school and adult self-reported health or behaviour. This is surprising given the extent to which characteristics known to be associated with adult health were clustered within schools.

Childhood socioeconomic position, educational attainment, and adult cardiovascular risk factors: the Aberdeen children of the 1950s cohort study.

OBJECTIVES: We assessed the associations of childhood socioeconomic position with cardiovascular disease risk factors (smoking, binge alcohol drinking, and being overweight) and examined the roles of educational attainment and cognitive functioning in these associations. METHODS: Data were derived from a cohort study involving 7184 individuals who were born in Aberdeen, Scotland, between 1950 and 1956; had detailed records on perinatal characteristics, childhood anthropometry, and cognitive functioning; and responded to a mailed questionnaire when they were aged 45 to 52 years. RESULTS: Strong graded associations existed between social class at birth and smoking, binge drinking, and being overweight. Adjustment for educational attainment completely attenuated these associations. However, after control for adult social class, adult income and other potential confounding or mediating factors, some association remained. CONCLUSIONS: Educational attainment is an important mediating factor in the relation between socioeconomic adversity in childhood and smoking, binge drinking, and being overweight in adulthood.

Who is more likely to experience common disorders: men, women, or both equally? Lay perceptions in the West of Scotland.

BACKGROUND: Gender differences in health are commonly observed by epidemiologists. Little is known about lay beliefs concerning the gender patterning of common conditions. METHODS: Using the West of Scotland Twenty-07 Study, we analysed responses to a question in a postal questionnaire asking whether respondents thought men or women (or both equally) were more likely to have heart disease, cancer, mental illness, and accidents, to be fit, and to live longer. This question was answered by 466 females and 353 males, then aged 25, 45, and 65 yr. RESULTS: Responses were in general in accord with epidemiological findings, but females had significantly lower odds than males of perceiving men as being at greater risk of accidents and heart disease, and higher odds than males of perceiving women as being at greater risk of mental illness. CONCLUSIONS: There was a tendency for each gender to think risks were higher for their own sex than did the other gender. This observation needs further exploration, particularly in the light of the research showing 'optimistic bias' in relation to health, and research suggesting that socioeconomically disadvantaged people may be least likely to perceive socially structured health inequalities.

Are rich people or poor people more likely to be ill? Lay perceptions, by social class and neighbourhood, of inequalities in health.

Research in the UK has suggested that people in lower social classes or from poorer neighbourhoods are less likely than their more socially advantaged counterparts to agree that health and life expectancy are worse among more deprived population groups. The small body of previous research has either used qualitative approaches or coded open-ended responses to survey questions about causes of health and illness or of inequalities between areas. We examined lay perceptions by asking a direct question and using a quantitative, multivariate approach. Residents in three age groups (25, 45 and 65 years old) living in two socially contrasting localities in Glasgow, Scotland, were asked who were more likely to have accidents, cancer, heart disease, mental illness, to be fitter, and to live longer: rich people, poor people, or both equally. Across all the health categories, those in lower social classes or from poorer neighbourhoods were equally or less likely than their more socially advantaged counterparts to say the poor had worse health. In a model containing age, sex, class and locality, those in lower social classes and in the poorer locality were significantly less likely to say that richer people live longer (OR: 0.5). We have therefore confirmed earlier observations that those most at risk of ill health may be less likely to acknowledge the social gradient in health. We suggest a need to examine this apparent paradox in other contexts and in more detail, using both quantitative and qualitative approaches.

How similar are the smoking and drinking habits of men and women in non-manual jobs?

BACKGROUND: Men used to be more likely to smoke and drink heavily than women. However, as social roles changed, so have gender differences in health-related behaviours. This paper explores whether gender differences in these behaviours persist or disappear among men and women occupying similar social roles: working in the same non-manual jobs in Britain. METHODS: Self-completion questionnaires were distributed to full-time employees in a bank (n = 2,139) and a university (n = 1,611). Response rates were 76% and 67% respectively. Respondents were asked whether they smoked currently. Men who reported drinking more than 21 units of alcohol, and women who reported drinking more than 14 units, in the last week were classed as 'heavy' drinkers. RESULTS: In both organizations there were no significant gender differences in smoking, but men were significantly more likely than women to report drinking 'heavily'. Employees in clerical jobs in the university were more than twice as likely as their more senior colleagues to smoke, but were significantly less likely to report drinking 'heavily' in both organizations. High masculinity scores among both men and women were associated with smoking and 'heavy' drinking. CONCLUSION: Men and women occupying similar social roles are equally likely to smoke but men are significantly more likely to drink 'heavily'. The relationship between paid work variables and these health behaviours are similar for both men and women. The association between high masculinity scores and health-damaging behaviours in both men and women points to the importance of considering gender role orientation, rather than just comparing men and women.