Factors Associated with Changes in Body Mass Trajectories during Infancy: A Longitudinal Analysis in Japan

Maternal behaviour and child birth outcomes have been shown to be associated with the risk of disease in children. However, little is known about their association with the trajectories of physical development. The aim of this study was to identify factors associated with body mass index (BMI) trajectories in Japanese toddlers. All 900 children born in Ibara City between 2006 and 2009 were enrolled in this study with their mothers. Children’s heights and weights were measured, as was BMI (weight [kg]/height [m]2). Multilevel analyses examined the association of maternal behaviour (smoking, using formula milk, and leaving the child in a daytime nursery) and birth outcomes (weight, parity, and gestational age) with standardized BMI trajectories (z-score analysis). Average BMIs ± standard deviations at birth and at 1.5, 2, and 3 years were 12.6 ± 1.3, 16.8 ± 1.2, 16.1 ± 1.2, and 15.7 ± 0.1, respectively. Maternal behaviour was not associated with BMI trajectories. However, BMIs of low birth weight children at 3 years were significantly higher than those of other children (β = 1.799, P β = –0.035, P β = –0.04271, P < 0.001). Other evaluated factors were not associated with BMI trajectories. Our results showed that low birth weight children are more likely to exhibit lower BMIs until 2 years of age;however, BMI rapidly rises afterwards. Longer follow-up periods are warranted to evaluate the consequence of the late-year rapid increases in BMI among low birth weight children.

Generalized flyby trajectories around elongated minor celestial bodies as a rotating mass dipole

The aim of this paper is to understand the common characteristics of the generalized flyby trajectory around natural elongated bodies. Such flyby trajectories provide a short-term mechanism to clear away vicinal objects or temporally capture ejecta into circling orbits. The gravitational potential of elongated bodies is described by a unified approximate model, i.e., the rotating mass dipole which is two point masses connected with a constant massless rod The energy power is used to illustrate the flyby effect in terms of the instantaneous orbital energy. The essential of the single flyby trajectory is studied analytically, and the relationship between the flyby trajectory and its Jacobi integral is also illustrated. Sample trajectories are given to show the variational trend of the energy increment with respect to differen orbital periapsides. The distribution of natural ejecting orbits is presented by varying the parameters of the approximate model.

Associations of prenatal exposure to bisphenols with BMI growth trajectories in offspring within the first two years:evidence from a birth cohort study in China

Background Prenatal bisphenol exposure has been reported to be associated with lower birth weight and obesity-related indicators in early childhood.These findings warrant an investigation of the relationship between prenatal bisphenol exposure and the dynamic growth of offspring.This study aimed to evaluate the relationship of maternal bisphenol concentration in urine with the body mass index(BMI)growth trajectory of children aged up to two years and to identify the critical exposure periods.Methods A total of 826 mother–offspring pairs were recruited from Wuhan Children’s Hospital between November 2013 and March 2015.Maternal urine samples collected during the first,second,and third trimesters were analyzed for bisphenol A(BPA),bisphenol S,and bisphenol F(BPF)concentrations.Measurements of length and weight were taken at 0,1,3,6,8,12,18,and 24 months.Children's BMI was standardized using the World Health Organization reference,and group-based trajectory modeling was used to identify BMI growth trajectories.The associations between prenatal bisphenol exposure and BMI growth trajectory patterns were assessed using multinomial logistic regression models.Results The BMI growth trajectories of the 826 children were categorized into four patterns:low-stable(n=134,16.2%),low-increasing(n=142,17.2%),moderate-stable(n=350,42.4%),and moderate-increasing(n=200,24.2%).After adjusting for potential confounders,we observed that prenatal exposure to BPA during the second trimester[odds ratio(OR)=2.20,95%confidence interval(CI)=1.09–4.43]and BPF during the third trimester(OR=3.28,95%CI=1.55–6.95)at the highest quartile concentration were associated with an increased likelihood of the low-increasing BMI trajectory.Furthermore,in the subgroup analysis by infant sex,the positive association between the highest quartile of prenatal average urinary BPF concentration during the whole pregnancy and the low-increasing BMI trajectory was found only in girls(OR=2.82,95%CI=1.04–7.68).Conclusion Our study findings suggest that prenatal exposure to BPA and BPF(a commonly used substitute for BPA)is associated with BMI growth trajectories in offspring during the first two years,increasing the likelihood of the low-increasing pattern.

Effect of slope inclination on step friction coefficient of human being

Effect of slope inclination on step friction coefficient of human being was studied by gait friction tester developed by Henan University of Science and Technology.It is beneficial to improving the safety of human beings while walking on a ramp.Based on the trajectory of mass center of body(MCOB)and the mechanical analysis of human body while walking,conclusion could be drawn that the required step frictional coefficient(RSFC)exhibited an"M"shaped curve during the foot contacting with the ground and got its maximum and minimum values when MCOB of the subject was at the highest and lowest position respectively.Moreover,the first peak of RSFC decreases firstly and then increases,while the second peak of RSFC increases with the increase of slope inclination at the experimental condition.The position of pivotal point is decided by the relative size of slope inclination and the angle between the plumb line through MCOB and the line from foot to MCOB.