Sinh-Gordon, Cosh-Gordon and Liouville Equations for Strings and Multi-Strings in Constant Curvature Spacetimes

We find that the fundamental quadratic form of classical string propagation in $2+1$ dimensional constant curvature spacetimes solves the Sinh-Gordon equation, the Cosh-Gordon equation or the Liouville equation. We show that in both de Sitter and anti de Sitter spacetimes (as well as in the $2+1$ black hole anti de Sitter spacetime), {\it all} three equations must be included to cover the generic string dynamics. The generic properties of the string dynamics are directly extracted from the properties of these three equations and their associated potentials (irrespective of any solution). These results complete and generalize earlier discussions on this topic (until now, only the Sinh-Gordon sector in de Sitter spacetime was known). We also construct new classes of multi-string solutions, in terms of elliptic functions, to all three equations in both de Sitter and anti de Sitter spacetimes. Our results can be straightforwardly generalized to constant curvature spacetimes of arbitrary dimension, by replacing the Sinh-Gordon equation, the Cosh-Gordon equation and the Liouville equation by higher dimensional generalizations.Comment: Latex, 19 pages + 1 figure (not included

Cross-sectional association between diet quality and cardiometabolic risk by education level in Mexican adults

Objective: Understanding the association between diet quality and cardiometabolic risk by education level is important for preventing increased cardiometabolic risk in the Mexican population, especially considering pre-existing disparities in diet quality. The present study examined the cross-sectional association of overall diet quality with cardiometabolic risk, overall and by education level, among Mexican men and women.Design: Cardiometabolic risk was defined by using biomarkers and diet quality by the Mexican Diet Quality Index. We computed sex-specific multivariable logistic regression models.Setting: Mexico.Participants: Mexican men (n 634) and women (n 875) participating in the Mexican National Health and Nutrition Survey 2012.Results: We did not find associations of diet quality with cardiometabolic risk factors in the total sample or in men by education level. However, we observed that for each 10-unit increase in the dietary quality score, the odds of diabetes risk in women with no reading/writing skills was 0·47 (95 % CI 0·26, 0·85) relative to the odds in women with ≥10 years of school (referent). Similarly, for each 10-unit increase of the dietary quality score, the odds of having three v. no lipid biomarker level beyond the risk threshold in lower-educated women was 0·27 (95 % CI 0·12, 0·63) relative to the odds in higher-educated women.Conclusions: Diet quality has a stronger protective association with some cardiometabolic disease risk factors for lower- than higher-educated Mexican women, but no association with cardiometabolic disease risk factors among men. Future research will be needed to understand what diet factors could be influencing the cardiometabolic disease risk disparities in this population

Accounting for Selectivity Bias and Correlation Across the Sequence from Elevated Blood Pressure to Hypertension Diagnosis and Treatment

BACKGROUND It is unknown whether efforts to reduce hypertension burden in countries with very high prevalence, would be more effective if directed at hypertension diagnosis vs. treatment. Most analyses do not address bias and correlation across the sequence from elevated blood pressure (BP) to hypertension diagnosis and treatment, leading to potentially misleading findings. METHODS Using data spanning 18 years of the China Health and Nutrition Survey (n = 18,926; ages 18-75 years), we used an innovative 3-step, integrated system of equations to predict the sequence from: (i) elevated BP (systolic/diastolic BP ≥ 140/90 mm Hg) to (ii) diagnosed hypertension conditional on elevated BP, and to (iii) treatment (medication use) conditional on diagnosis, accounting for measured and unmeasured individual- and community-level confounders at each of the 3 steps. We compared results to separate traditional logistic regression models without control for unmeasured confounding. RESULTS Using our 3-step model, elevated BP increased from 12.6% and 8.5% (1991) to 36.8% and 29% (2009) in men and women, respectively, but diagnosis remained under 50%. We found widening disparities in hypertension diagnosis (higher hypertension at lower vs. higher education (difference of 2% in 1991 that widened to 5% in 2009)) and narrowing disparities in education (difference of 6% in 1991 to 4% in 2009) and insurance status (difference of 7% in 1991 to 2% in 2009) for treatment. CONCLUSIONS Our 3-step model improved model fit over traditionally used models. Our findings highlight serious barriers to hypertension diagnosis in Chinese adults, particularly among men and individuals of low attained education

Is a Hypertension Diagnosis Associated With Improved Dietary Outcomes Within 2 to 4 Years? A Fixed-Effects Analysis From the China Health and Nutrition Survey

Background: Evidence shows that dietary factors play an important role in blood pressure. However, there is no clear understanding of whether hypertension diagnosis is associated with dietary modifications. The aim of this study is to estimate the longitudinal association between hypertension diagnosis and subsequent changes (within 2–4 years) in dietary sodium, potassium, and sodium-potassium (Na/K) ratio. Methods and Results: We included adults (18–75 years, n=16 264) from up to 9 waves (1991–2015) of the China Health and Nutrition Survey. Diet data were collected using three 24-hour dietary recalls and a household food inventory. We used fixed-effects models to estimate the association between newly self-reported diagnosed hypertension and subsequent within-individual changes in sodium, potassium, and Na/K ratio. We also examined changes among couples and at the household level. Results suggest that on average, men who were diagnosed with hypertension decreased their sodium intake by 251 mg/d and their Na/K ratio by 0.19 within 2 to 4 years after diagnosis (P<0.005). Among spouse pairs, sodium intake and Na/K ratio of women decreased when their husbands were diagnosed (P<0.05). Household average sodium density and Na/K ratio decreased, and household average potassium density increased after a man was diagnosed. In contrast, changes were not statistically significant when women were diagnosed. Conclusions: Our findings suggest that hypertension diagnosis for a man may result in modest dietary improvements for him, his wife, and other household members. Yet, diagnosis for a woman does not seem to result in dietary changes for her or her household members

Associations of 5-year changes in alcoholic beverage intake with 5-year changes in waist circumference and BMI in the Coronary Artery Risk Development in Young Adults (CARDIA) study

Objective This study aimed to shed light on contradictory associations of alcohol intake with waist circumference (WC) and body mass index (BMI) by examining 5-yr changes in alcohol intake in relation to 5-yr WC and BMI changes. Methods This prospective study included 4,355 participants (1,974 men and 2,381 women) enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study at baseline (1985–1986) and followed over 25 years (2010–2011). Longitudinal random effects linear regression models were used to test whether changes in drinking (defined categorically) as starting to drink, increasing, decreasing, stable drinking or stopping drinking (versus stable non-drinking) over a series of 5-yr periods were associated with corresponding 5-yr WC and BMI changes. Associations with 5-yr changes (defined categorically as starting, stable or stopping) in drinking level (i.e., light/moderate and excessive) and 5-yr changes (defined categorically as increasing, no change, or decreasing) by beverage type (i.e., beer, wine and liquor/mixed drinks) were also examined. Results In men, compared to stable non-drinking, decreasing total alcohol intake was associated with lower 5-yr WC (β:-0.62 cm; 95% CI: -1.09, -0.14 cm) and BMI gains (β:-0.20 kg/m2; 95% CI: -0.30, -0.03 kg/m2) and stopping excessive drinking was associated with lower 5-yr WC gains (β:-0.77 cm; 95% CI: -1.51, -0.03 cm). In women, compared to those with stable non-drinking habits, starting light/moderate drinking was associated with lower 5-yr WC (β: -0.78 cm; 95% CI: -1.29, -0.26 cm) and BMI gains (β:-0.42 kg/m2; 95% CI: -0.64, -0.20 kg/ m2). Increasing wine intake was associated with a lower 5-yr BMI gain (β:-0.27 kg/m2; 95% CI: -0.51, -0.03 kg/m2). Decreasing liquor/mixed drink (β:-0.33 kg/m2; 95% CI: -0.56, -0.09 kg/m2) intake was associated with lower 5-yr WC (β:-0.88 cm; 95% CI: -1.43, -0.34 cm) and BMI (β:-0.33 kg/m2; 95% CI: -0.56, -0.09 kg/m2) gains. Conclusions Associations of alcohol intake with obesity measures are complex. In women, wine and liquor/mixed drink intakes had contrasting associations with WC and BMI change. In men, decreasing weekly alcoholic beverage intake with an emphasis on stopping excessive consumption may be beneficial in managing WC and BMI gains

Sociodemographic disparity in the diet quality transition among Chinese adults from 1991 to 2011

Background/objectives:This study investigates secular trends in diet quality distribution and related socioeconomic disparity from 1991 to 2011 in the Chinese adult population.Subjects/methods:The analysis uses the 1991-2011 China Health and Nutrition Survey data on 13 853 participants (6876 men and 6977 women) aged 18-65 with 56 319 responses. Dietary assessment was carried out over a 3-day period with 24-h recalls combined with a household food inventory. We tailored Alternative Healthy Eating Index 2010 (named as tAHEI) to measure diet quality and performed quantile regression to investigate shifts in tAHEI scores at different percentiles and used mixed-effect linear regression to examine average diet quality trend and potential sociodemographic disparity.Results:The energy-adjusted mean tAHEI scores increased from 36.9 (36.7-37.1) points in 1991 to 50.3 (50.1-50.5) in 2011 for men (P<0.001) and from 35.6 (35.4-35.8) to 46.9 (46.7-47.1) for women (P<0.001). The covariate-adjusted score of polyunsaturated fatty acids increased by 6.8 (6.6, 7.0) and 7.0 (6.9, 7.2), and the score of long-chain (ω-3) fats increased by 5.3 (5.2, 5.4) and 5.3 (5.2, 5.5) in men and women, respectively, whereas the cereal fiber and red meat scores decreased slightly. Increasing tAHEI score occurred across the entire distribution, and diet quality transition varied across sociodemographic groups.Conclusions:Chinese diet quality is far from optimal, with moderate improvement over a 21-year period. Findings suggest that nutritional intervention should give priority to low-income, low-urbanized communities and southern provincial adults with low diet quality in China

Diet quality is linked to insulin resistance among adults in China

Background: Little is known about the impact of Chinese diet quality changes on diabetes-related markers. Objective: The present study examined the association of changes in overall diet quality with various biomarkers of diabetes among adults in China. Methods: The current analysis used longitudinal diet data from 1991 to 2006 and fasting blood samples from 2009 for 4734 adults aged 18-65 y from the China Health and Nutrition Survey. Dietary intake was assessed by using 3 consecutive 24-h recalls and household food weighing. The tailored Alternative Healthy Eating Index (tAHEI) was adapted from the 2010 Harvard Alternative Healthy Eating Index to measure overall diet quality. We categorized baseline tAHEI scores into tertiles and annual changes in the scores into 5 levels (high decrease, low decrease, maintain, low increase, and high increase). We performed mixed-effects regressions to assess the associations between baseline scores and changes in the tAHEI scores and diabetes or insulin markers. Results: Adults with high baseline tAHEI scores tended to be male, older, of lower socioeconomic status, and with higher physical activity levels. After adjustment for all of the covariates, insulin and homeostasis model assessment of insulin resistance (HOMA-IR) values were 5.1% (95% CI:-0.100,-20.002) and 5.7% (95% CI:-0.113,-0.001) lower, respectively, for adults with high compared with low baseline tAHEI scores and 8.6% (95% CI:-0.155,-0.017) and 9.8% (95% CI:-0.177,-0.018) lower, respectively, for adults with a high increase in score compared with the ''maintain'' category. Null associations were observed between baseline scores and changes in the scores and fasting blood glucose, glycated hemoglobin (HbA1c), and diabetes prevalence. Conclusions: Baseline and changes in diet quality were independently associated with lower HOMA-IR and plasma insulin but not with fasting blood glucose and HbA1c in Chinese adults. Prospective studies on overall diet quality in relation to diabetes markers and risk of diabetes are needed

Understanding bias in relationships between the food environment and diet quality: The Coronary Artery Risk Development in Young Adults (CARDIA) study

Background The relationship between food environment exposures and diet behaviours is unclear, possibly because the majority of studies ignore potential residual confounding. Methods We used 20 years (1985-1986, 1992-1993 2005-2006) of data from the Coronary Artery Risk Development in Young Adults (CARDIA) study across four US cities (Birmingham, Alabama; Chicago, Illinois; Minneapolis, Minnesota; Oakland, California) and instrumental variables (IV) regression to obtain causal estimates of longitudinal associations between the percentage of neighbourhood food outlets (per total food outlets within 1 km network distance of respondent residence) and an a priori diet quality score, with higher scores indicating higher diet quality. To assess the presence and magnitude of bias related to residual confounding, we compared results from causal models (IV regression) to non-causal models, including ordinary least squares regression, which does not account for residual confounding at all and fixed-effects regression, which only controls for time-invariant unmeasured characteristics. Results The mean diet quality score across follow-up was 63.4 (SD=12.7). A 10% increase in fast food restaurants (relative to full-service restaurants) was associated with a lower diet quality score over time using IV regression (β=-1.01, 95% CI -1.99 to -0.04); estimates were attenuated using non-causal models. The percentage of neighbourhood convenience and grocery stores (relative to supermarkets) was not associated with diet quality in any model, but estimates from non-causal models were similarly attenuated compared with causal models. Conclusion Ignoring residual confounding may generate biased estimated effects of neighbourhood food outlets on diet outcomes and may have contributed to weak findings in the food environment literature

Does unmeasured confounding influence associations between the retail food environment and body mass index over time? The Coronary Artery Risk Development in Young Adults (CARDIA) study

Background: Findings in the observational retail food environment and obesity literature are inconsistent, potentially due to a lack of adjustment for residual confounding. Methods: Using data from the CARDIA study (n ¼ 12 174 person-observations; 6 examinations; 1985-2011) across four US cities (Birmingham, AL; Chicago, IL; Minneapolis, MN; Oakland, CA), we used instrumental-variables (IV) regression to obtain causal estimates of the longitudinal associations between the percentage of neighbourhood food stores or restaurants (per total food outlets within 1 km network distance of respondent residence) with body mass index (BMI), adjusting for individual-level socio-demographics, health behaviours, city, year, total food outlets and market-level prices. To determine the presence and extent of bias, we compared the magnitude and direction of results with ordinary least squares (OLS) and random effects (RE) regression, which do not control for residual confounding, and with fixed effects (FE) regression, which does not control for time-varying residual confounding. Results: Relative to neighbourhood supermarkets (which tend to be larger and have healthier options than grocery stores), a higher percentage of grocery stores [mean-¼ 53.4%; standard deviation (SD) ¼ 31.8%] was positively associated with BMI [b ¼ 0.05; 95% confidence interval (CI) ¼ 0.01, 0.10] using IV regression. However, associations were negligible or null using OLS (b ¼ 0.001; 95% CI ¼ 0.01, 0.01), RE (b ¼ 0.003; 95% CI ¼ 0.01, 0.0001) and FE (b ¼ 0.003; 95% CI ¼ 0.01, 0.0002) regression. Neighbourhood convenience stores and fast-food restaurants were not associated with BMI in any model. Conclusions: Longitudinal associations between neighbourhood food outlets and BMI were greater in magnitude using a causal model, suggesting that weak findings in the literature may be due to residual confounding

Constraining warm dark matter with cosmic shear power spectra

We investigate potential constraints from cosmic shear on the dark matter particle mass, assuming all dark matter is made up of light thermal relic particles. Given the theoretical uncertainties involved in making cosmological predictions in such warm dark matter scenarios we use analytical fits to linear warm dark matter power spectra and compare (i) the halo model using a mass function evaluated from these linear power spectra and (ii) an analytical fit to the non-linear evolution of the linear power spectra. We optimistically ignore the competing effect of baryons for this work. We find approach (ii) to be conservative compared to approach (i). We evaluate cosmological constraints using these methods, marginalising over four other cosmological parameters. Using the more conservative method we find that a Euclid-like weak lensing survey together with constraints from the Planck cosmic microwave background mission primary anisotropies could achieve a lower limit on the particle mass of 2.5 keV.Comment: 26 pages, 9 figures, minor changes to match the version accepted for publication in JCA