Strong-Coupling Phases of Trions and Excitons in Electron-Hole Bilayers at Commensurate Densities.

We introduce density imbalanced electron-hole bilayers at a commensurate 2:1 density ratio as a platform for realizing novel phases of electrons, excitons, and trions. Through the independently tunable carrier densities and interlayer spacing, competition between kinetic energy, intralayer repulsion, and interlayer attraction yields a rich phase diagram. By a combination of theoretical analysis and numerical calculation, we find a variety of strong-coupling phases in different parameter regions, including quantum crystals of electrons, excitons, and trions. We also propose an "electron-exciton supersolid" phase that features electron crystallization and exciton superfluidity simultaneously. The material realization and experimental signature of these phases are discussed in the context of semiconductor transition metal dichalcogenide bilayers.

The Association of Breastfeeding Duration and Early Childhood Cardiometabolic Risk.

OBJECTIVE: To evaluate the association between breastfeeding duration and early childhood cardiometabolic risk. STUDY DESIGN: A cross-sectional study of 1539 healthy children, 3-6 years of age, recruited through The Applied Research Group for Kids! practice-based research network between October 2009 and August 2015. Adjusted multivariable linear regression was used to examine the association between breastfeeding duration and cardiometabolic risk z score and individual cardiometabolic risk factors of waist circumference, systolic blood pressure, glucose, high-density lipoprotein cholesterol, and triglycerides. RESULTS: The mean breastfeeding duration was 12.5 months (SD = 8.4). Breastfeeding duration was associated with lower cardiometabolic risk z score (beta = -0.03; 95% CI -0.05, -0.01). In analysis of cardiometabolic risk factors, each additional 3 months of breastfeeding was associated with a 0.13 cm (95% CI -0.20, -0.05) lower waist circumference and 0.16 mm Hg (95% CI -0.30, -0.02) lower systolic blood pressure. Compared with children who breastfed for 6-12 months, those who breastfed for 12-24 months had a lower systolic blood pressure of 1.07 mm Hg (95% CI -2.04, -0.10). There was no association between breastfeeding duration and cardiometabolic risk for those who breastfed beyond 24 months. CONCLUSIONS: Breastfeeding duration is associated with lower cardiometabolic risk, although the magnitude of association is small. Causation cannot be inferred. Breastfeeding beyond 24 months may not have an added benefit for cardiometabolic health.