Objective:To develop a prediction model that quantifies the risk of being overweight at 10 years of age.Subjects/Methods:In total, 3121 participants from the GINIplus (German Infant Nutritional Intervention plus environmental and genetic influences on allergy development) and LISAplus (Influences of Lifestyle-Related Factors on the Immune System and the Development of Allergies in Childhood plus Air Pollution and Genetics) German birth cohorts were recruited. We predicted standardized body mass index (BMI) at 10 years of age using standardized BMIs from birth to 5 years. Parental education, family income and maternal smoking during pregnancy were considered as covariates. Linear and logistic regression models were used to evaluate the impact of risk factors on BMI and on being overweight at 10 years of age, respectively.Results:Birth weight, standardized BMI at 5 years (60–64 months) (β=0.77; 95% confidence interval (CI): 0.73–0.81) and maternal smoking during pregnancy were positively associated with standardized BMI at 10 years of age. Standardized BMI and overweight at 5 years were strongest predictors of being overweight at 10 years. Conversely, high parental education conferred a protective effect (β=−0.15; 95% CI: −0.29 to −0.01). Being overweight at 5 years (60–64 months) increased the risk of being overweight at 10 years of age with odds ratios above 10. Among children who were predicted to be overweight at 10 years, cross-validation results showed that 76.8% of female subjects and 68.1% of male subjects would be overweight at 10 years of age.Conclusion:BMI and being overweight at 5 years of age are strong predictors of being overweight at 10 years of age. The effectiveness of targeted interventions in children who are overweight at 5 years of age should be explored.
We present observations of the power spectral anisotropy in wave-vector space of solar wind turbulence, and study how it evolves in interplanetary space with increasing heliocentric distance. For this purpose we use magnetic field measurements made by the Helios-2 spacecraft at three positions between 0.29 and 0.9 AU. To derive the power spectral density (PSD) in (k , k ⊥ )-space based on single-satellite measurements is a challenging task not yet accomplished previously. Here we derive the spectrum PSD 2D (k , k ⊥ ) from the spatial correlation function CF 2D (r , r ⊥ ) by a transformation according to the projection-slice theorem. We find the so constructed PSDs to be distributed in k-space mainly along a ridge that is more inclined toward the k ⊥ than k axis, a new result which probably indicates preferential cascading of turbulent energy along the k ⊥ direction. Furthermore, this ridge of the distribution is found to gradually get closer to the k ⊥ axis, as the outer scale length of the turbulence becomes larger while the solar wind flows further away from the Sun. In the vicinity of the k axis, there appears a minor spectral component that probably corresponds to quasi-parallel Alfvénic fluctuations. Their relative contribution to the total spectral density tends to decrease with radial distance. These findings suggest that solar wind turbulence undergoes an anisotropic cascade transporting most of its magnetic energy towards larger k ⊥ , and that the anisotropy in the inertial range is radially developing further at scales that are relatively far from the ever increasing outer scale.
Magnetohydronamic turbulence is believed to play a crucial role in heating laboratory, space, and astrophysical plasmas. However, the precise connection between the turbulent fluctuations and the particle kinetics has not yet been established. Here we present clear evidence of plasma turbulence heating based on diagnosed wave features and proton velocity distributions from solar wind measurements by the Wind spacecraft. For the first time, we can report the simultaneous observation of counter-propagating magnetohydrodynamic waves in the solar wind turbulence. As opposed to the traditional paradigm with counter-propagating Alfvén waves (AWs), anti-sunward AWs are encountered by sunward slow magnetosonic waves (SMWs) in this new type of solar wind compressible turbulence. The counter-propagating AWs and SWs correspond, respectively, to the dominant and sub-dominant populations of the imbalanced Elsässer variables. Nonlinear interactions between the AWs and SMWs are inferred from the non-orthogonality between the possible oscillation direction of one wave and the possible propagation direction of the other. The associated protons are revealed to exhibit bi-directional asymmetric beams in their velocity distributions: sunward beams appear in short, narrow patterns and anti-sunward in broad extended tails. It is suggested that multiple types of wave-particle interactions, i.e., cyclotron and Landau resonances with AWs and SMWs at kinetic scales, are taking place to jointly heat the protons perpendicular and in parallel.
The break in power spectral density (PSD) around the ion scales indicates the onset of dissipation and/or dispersion of kinetic turbulence. For Alfvén waves in the kinetic regime, the dissipation and dispersion are individually dependent on the propagation angle, θ kB , which has θ RB (the angle between radial direction and local mean magnetic field direction) as a proxy in solar wind measurements. The relation between θ RB and the break position helps us find the role of dissipation and/or dispersion for deforming the PSD profile. In order to locate the spectral break position automatically and quantitatively, we develop a dual-power-law fitting method to fit the PSD profiles in both MHD and kinetic ranges simultaneously. The break position f b is found to change little with θ RB , suggesting an angular independence of the spectral break. Furthermore, f b in our statistical study of fast solar wind near 1 au is consistent with a wavenumber k satisfying k(ρ p +d p)∼1 (ρ p is the thermal proton gyroradius and d p is the proton inertial length), independently of θ RB. To interpret this independence, we incorporate the effects of both dissipation and dispersion in a unified description, which is the breakdown of the magnetic frozen-in condition in wavenumber space (k P , k ⊥). The breakdown of the frozen-in condition is relatively isotropic compared to the strong anisotropy of dispersion and dissipation. Furthermore, the spatial scale for the onset of the breakdown frozen-in condition is estimated to be the sum of ρ p and d p .
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