We have studied the optical transmission of one-dimensional Fibonacci-class quasiperiodic multilayers, which possess a mirror symmetry. We find that the transmission coefficient is unity for all studied sequences at t...We have studied the optical transmission of one-dimensional Fibonacci-class quasiperiodic multilayers, which possess a mirror symmetry. We find that the transmission coefficient is unity for all studied sequences at the central wavelength λ=λ0, where λ0 = (1/4)nA(B)dA(B) with nA(B) and dA(B) being the index of refraction and thickness of twokinds of layers, respectively. Two-cycle or three-cycle has been found around λ = λ0, which is different from the features of the sequences without symmetric structure.展开更多
Background The prevalence of overweight and obesity in Chinese children and adolescents was increasing during the past few decades. The goal of this study was to investigate the effects of after-school exercise with o...Background The prevalence of overweight and obesity in Chinese children and adolescents was increasing during the past few decades. The goal of this study was to investigate the effects of after-school exercise with or without diet restriction on total and central obesity, fitness level, and metabolic profile in overweight Chinese adolescents.Methods A ten-week weight loss trial was performed using a 2×2 block design （exercisexdiet）. Ninety-three overweight adolescents （average age：（13.6±0.7） years; body mass index （BMI）： 22.4-34.1 kg/m2） were randomly assigned to four groups：1） diet （D）; 2） exercise （EX）; 3） diet plus exercise （DEX）; and 4） overweight control （C）. Caloric intake recipes were enacted based on individual age and corresponding ideal body weight. One-hour after-school exercise was performed once per day, four days per week for ten weeks. Changes of anthropometry, body composition, aerobic fitness,and metabolic biomarkers were determined.Results Groups D, EX and DEX had a significant decrease in BMI （P〈0.01） after the intervention. The percentage of body and truncal fat, and waist circumference were independently reduced by exercise （P〈0.05 and P 〈0.01）, but not diet. The decrease in body fat percentage was positively related with the exercise compliance （r=0.34,P=0.01）. Exercise decreased truncal fat percentage and waist circumference, suggesting a reduction of central adiposity, but did not significantly affect body weight and BMI. Exercise significantly reduced serum low-density lipoprotein cholesterol （P=0.037）, which was positively correlated with decreases of truncal fat percentage （r=0.222, P=0.048）. No significant effects of interventions on insulin sensitivity, early insulin release index, and aerobic fitness were observed.Conclusion At least twice a week of one-hour after-school exercise significantly attenuated central adiposity and had a significant impact on lipid profiles in overweight Chinese adolescents.展开更多
In this paper, according to the practical condition of local fixed telecom network, based on the method of the realistic total element long-run incremental cost, the practical methods of dividing the network elements,...In this paper, according to the practical condition of local fixed telecom network, based on the method of the realistic total element long-run incremental cost, the practical methods of dividing the network elements, calculating the cost of network elements and services are given, to provide reference for the cost calculation in telecom industry.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.19874027.
文摘We have studied the optical transmission of one-dimensional Fibonacci-class quasiperiodic multilayers, which possess a mirror symmetry. We find that the transmission coefficient is unity for all studied sequences at the central wavelength λ=λ0, where λ0 = (1/4)nA(B)dA(B) with nA(B) and dA(B) being the index of refraction and thickness of twokinds of layers, respectively. Two-cycle or three-cycle has been found around λ = λ0, which is different from the features of the sequences without symmetric structure.
基金Item：This study was supported by grants from National Social Science Foundation of the Ministry of Education of China （No.BLA060052）, National Basic Research Program of China （No.2006CB 503910）, National Natural Science foundation of China（No. 30572082）, Natural Science foundation of Beijing （No.7092090）.
文摘Background The prevalence of overweight and obesity in Chinese children and adolescents was increasing during the past few decades. The goal of this study was to investigate the effects of after-school exercise with or without diet restriction on total and central obesity, fitness level, and metabolic profile in overweight Chinese adolescents.Methods A ten-week weight loss trial was performed using a 2×2 block design （exercisexdiet）. Ninety-three overweight adolescents （average age：（13.6±0.7） years; body mass index （BMI）： 22.4-34.1 kg/m2） were randomly assigned to four groups：1） diet （D）; 2） exercise （EX）; 3） diet plus exercise （DEX）; and 4） overweight control （C）. Caloric intake recipes were enacted based on individual age and corresponding ideal body weight. One-hour after-school exercise was performed once per day, four days per week for ten weeks. Changes of anthropometry, body composition, aerobic fitness,and metabolic biomarkers were determined.Results Groups D, EX and DEX had a significant decrease in BMI （P〈0.01） after the intervention. The percentage of body and truncal fat, and waist circumference were independently reduced by exercise （P〈0.05 and P 〈0.01）, but not diet. The decrease in body fat percentage was positively related with the exercise compliance （r=0.34,P=0.01）. Exercise decreased truncal fat percentage and waist circumference, suggesting a reduction of central adiposity, but did not significantly affect body weight and BMI. Exercise significantly reduced serum low-density lipoprotein cholesterol （P=0.037）, which was positively correlated with decreases of truncal fat percentage （r=0.222, P=0.048）. No significant effects of interventions on insulin sensitivity, early insulin release index, and aerobic fitness were observed.Conclusion At least twice a week of one-hour after-school exercise significantly attenuated central adiposity and had a significant impact on lipid profiles in overweight Chinese adolescents.
文摘In this paper, according to the practical condition of local fixed telecom network, based on the method of the realistic total element long-run incremental cost, the practical methods of dividing the network elements, calculating the cost of network elements and services are given, to provide reference for the cost calculation in telecom industry.
