[Association between parental socioeconomic status and preschoolers' consumption of sugar-sweetened beverages]

Objective: To explore the association between parental socioeconomic status (SES) and preschoolers' consumption of sugar-sweetened beverages (SSB). Methods: In June 2018, all preschoolers from 15 kindergartens were selected from the jurisdiction of Education Commission in Dongcheng District of Beijing by using an equal-proportion stratified cluster sampling method in the study. A self-designed questionnaire was used to investigate the parents of preschoolers to obtain the basic information of preschoolers and parents, the consumption situation of preschoolers' sugar-sweetened beverages and the perception of parents to SSB. A tatol of 3 217 preschoolers were finally included in the analysis. A generalized structural equation model was used to analyze the relationship between preschoolers' consumption of sugar-sweetened beverages and their parents' socioeconomic status and the mediating effect of their cognition of sugar-sweetened beverages. The size of mediating effect was estimated by using deviation correction non-parameter percentile Bootstrap method. Results: The age of 3 217 preschoolers was (4.23±0.67) years, of which 52.6% (n=1 692) were boys, and 77.62% (n=2 497) were SSB consumers. Among the parents of 3 217 preschoolers, fathers and mothers accounted for 24.90% (n=801) and 75.10% (n=2 416), and the M (P₂₅, P₇₅) scores of SES were 66.7 (62.5, 69.5) and 69.5 (64.6, 71.4), respectively. The proportion of parents who took the initiative to learn about their children's consumption of SSB, lacked confidence in restricting preschooler's consumption of SSB and read nutrition labels before purchasing food was 74.08% (n=2 383), 82.90% (n=2 667) and 36.24% (n=1 166), respectively. The generalized structural equation model showed that after adjusting for preschoolers' gender, age, body mass index (BMI) of preschoolers and their parents, preschoolers' consumption of SSB was negatively associated with their parents' SES score [path coefficient (95%CI):-4.69×10^-2 (-6.56×10^-2,-2.69×10^-2) ]. The mediating effect of parents' perception of SSB consumption could explain 48.71% of the total effect [path coefficient (95%CI):-2.28×10^-2 (-3.54×10^-2, -1.10×10^-2)]. Conclusion: The consumption of SSB in preschoolers is negatively associated with their parent's SES, and this relationship is partially mediated by parent's perception of SSB consumption.

Group delay of electromagnetic pulses through multilayer dielectric mirrors combined with gravitational wave

Group delay of electromagnetic pulses through multilayer dielectric mirrors (MDM) combined with gravitational wave (GW) is investigated. Unlike in traditional quantum tunneling, the group delay of a transmitted wave packet irradiated by a GW increases linearly with MDM length. This peculiar tunneling effect can be attributed to electromagnetic wave leakage in a time-dependent photonic bandgap caused by the GW. In particular, we find that the group delay of the tunneling photons is sensitive to GW. Our study provides insight into the nature of the quantum tunnelling as well as a novel process by which to detect the GW.

Effective mass anisotropy of hot electrons in nonparabolic conduction bands of n-doped InGaAs films using ultrafast terahertz pump-probe techniques

The anisotropic effective mass of energetic electrons in an isotropic, nonparabolic conduction band is revealed using ultrafast THz-pump-THz-probe techniques in a n-doped InGaAs semiconductor thin film. A microscopic theory is applied to identify the origin of the observed anisotropy and to show that the self-consistent light-matter coupling contributes significantly to the THz response.

Terahertz pulse induced intervalley scattering in photoexcited GaAs

Nonlinear transient absorption bleaching of intense few-cycle terahertz (THz) pulses is observed in photoexcited GaAs using opticalpump--THz-probe techniques. A simple model of the electron transport dynamics shows that the observed nonlinear response is due to THz-electric- field-induced intervalley scattering over sub-picosecond time scales as well as an increase in the intravalley scattering rate attributed to carrier heating. Furthermore, the nonlinear nature of the THz pulse transmission at high peak fields leads to a measured terahertz conductivity in the photoexcited GaAs that deviates significantly from the Drude behavior observed at low THz fields, emphasizing the need to explore nonlinear THz pulse interactions with materials in the time domain.

Human apolipoprotein E: correlation of polymorphisms and serum lipid concentrations in Chinese

BACKGROUND

The allelic variation of the apolipoprotein E (apoE) gene affects serum lipid concentrations. This study investigates the correlation of apoE polymorphisms and serum cholesterol and triglyceride concentrations in Chinese subjects.

METHODS

DNA from a random sample of 136 unrelated individuals was used for polymerase chain reaction (PCR) amplification of the three apoE alleles. The amplified products were analyzed by Hha1 restriction fragment length polymorphism (RFLP) and single-strand conformation polymorphism (SSCP).

RESULTS

Identical genotypes were obtained by both methods in all individuals analyzed. The three apoE alleles examined were in Hardy-Weinberg equilibrium (p = 0.417). The allele frequencies in individuals with cholesterol and triglyceride values of below 200 mg/dl were 8.6% for epsilon 2, 82.8% for epsilon 3 and 8.6% for epsilon 4. When allele frequency between individuals with cholesterol values of below and above 200 mg/dl was compared, there appeared little difference in the epsilon 2 and epsilon 4 alleles between the two groups (p = 0.823). Conversely, a statistically significant difference in the epsilon 2 allele was observed (p = 0.048) between individuals with triglyceride values of below and above 200 mg/dl.

CONCLUSIONS

The results demonstrate that neither the epsilon 2 nor epsilon 4 alleles affect cholesterol values in Chinese subjects, whereas the epsilon 2 allele exerts an influence on serum triglyceride concentrations in Chinese.

Effect of central glucagon infusion on macronutrient selection in rats

Compared were the light-dark pattern of absolute energy intake and macronutrient selection of male Wistar rats intracerebroventricularly infused with glucagon (5 ng/h) or saline for 7 days in a three-way selection of macronutrients. Glucagon infusion induced a decrease in 24 h and nocturnal energy intake, whereas no significant change in kcal intake accompanied vehicle infusion. The decrease in kcal intake was due to a suppression of nocturnal ingestion of carbohydrate. This parameter was left unaffected with central vehicle infusion. Glucagon-infused rats had a significantly lower body weight gain than those infused with vehicle. Our study supports the hypothesis of central glucagon's suppressive effect on food intake, but reveals that the latter reflects a lower disposition to eat carbohydrate during the dark phase. The present work emphasizes the role of glucagon in the circadian regulation of carbohydrate intake.