Objective To analyze and assess secular change in stature in rural children and adolescents in China from 1985 to 2010. Methods Data were obtained from the 6 rounds of the Chinese National Survey on Student＇s Constit...Objective To analyze and assess secular change in stature in rural children and adolescents in China from 1985 to 2010. Methods Data were obtained from the 6 rounds of the Chinese National Survey on Student＇s Constitution and Health. The subjects enrolled in the study were children and adolescents aged 7-18 years in rural areas of provincial capitals. Results An overall positive secular trend in stature occurred in rural areas of provincial capitals in China from 1985 to 2010. The overall average increase rates were 3.1 and 2.4 cm/decade for boys and girls, respectively. The total body height increases for grown up boys and girls were 3.6 and 2.3 cm and the increase rates were 1.4 and 0.9 cm/decade, respectively. There were differences in body height increase among eastern, central and western regions. The average body height of the children or adolescents in eastern region was highest, followed by central region and western region. The overall increase rates in central region were highest among the three regions. The difference between eastern/central region and western region was obvious. 〈br〉 Conclusion Positive secular trend in stature of children or adolescents has occurred in rural area of China, and rural boys and girls showed a great potential for continuous growth. More attention should be paid to the differences in children＇s body height between western region and eastern/central region.展开更多
Objective To analyze the change in Body Mass Index （BMI） distribution among Chinese children and adolescents for the development of more effective intervention for childhood obesity. Methods Data on the national stu...Objective To analyze the change in Body Mass Index （BMI） distribution among Chinese children and adolescents for the development of more effective intervention for childhood obesity. Methods Data on the national students＇ constitution and health survey between 1985 and 2010 was used for this study. Subjects were students aged 7-18 randomly selected from 30 provinces in China. BMI for-age curves were developed by LMS method, and the trend of BMI distribution was determined by comparing the upper BMI percentiles and analyzing the skew shift of distribution between 2985 and 2010. Results An overall positive swift trend of BMI between 1985 and 2010 was observed among the Chinese school-age children and adolescents. The average median of the BMI increased from 16.8 and 17.0 ks/m2 to 18.2 and 17.9 kg/m2 in 25 years, with increments 0.56 and 0.36 kg/m2 per decade for males and females, respectively. The more obvious increments were found at the high BMI. The total increments of BMI in this period were 4.03 and 2.20 kg/m2 at the 85th, 6.24 and 3.57 kg/m2 at the 95th, and 6.99 and 4.27 kg/m2 at the 97th percentiles, for males and females, respectively. Conclusion Obvious increments were observed at high BMI of the Chinese children and adolescents. More effective interventions should be taken for control and prevention of obesity and its health consequence for these subgroups. It is necessary to establish a risk-complex system consisting of the identification of BMI scope, the screen of the disease risk factors and the assessment of excessive adiposity.展开更多
Objective Research evidence shows a secular trend in Chinese physical growth in recent years.The aim of this study was to analyze and assess changes in stature of children and adolescents during the 25 years from 1985...Objective Research evidence shows a secular trend in Chinese physical growth in recent years.The aim of this study was to analyze and assess changes in stature of children and adolescents during the 25 years from 1985‐2010,using national data.Methods Data came from successive cycles of the Chinese National Survey on Students＇ Constitution and Health（CNSSCH）.Subjects were 7‐ to 18‐year‐old children and adolescents.Results An overall positive secular trend occurred in urban China during 1985‐2010.The overall average rates of increment were 2.4 and 1.7 cm/decade for boys and girls,respectively.Total increases in adult stature for boys and girls were 2.6 and 1.7 cm,yielding rates of 1.0 and 0.7 cm/decade,respectively.Cities with different socioeconomic levels had different characteristic trends.Mean stature increases in big cities were larger than those in moderate and small cities,and boys and girls in moderate and small cities showed greater potential for growth in stature.Conclusion An overall positive secular growth trend was associated with socioeconomic progress and differed with area socioeconomic levels.School policies and strategies should be developed based on increased stature,and should continue narrowing the inequity between different socioeconomic populations.展开更多
Shale and greywacke compositions from the Archean to Phanerozoic record a secular change in the siliciclastic material that comprises much of Earth＇s continental margins, past and present. This study explores the met...Shale and greywacke compositions from the Archean to Phanerozoic record a secular change in the siliciclastic material that comprises much of Earth＇s continental margins, past and present. This study explores the metamorphic consequence of these compositional changes, by comparing phase equilibrium models constructed for average Archean, Proterozoic, and Phanerozoic shale and greywacke compositions equilibrated along two Barrovian-type geotherms： 1330℃/GPa（A） and 800 ℃/GPa（B）. Our models show that Archean siliciclastic rocks can retain up to 4 vol.% water at middle to lower crustal conditions, nearly twice that of Proterozoic and Phanerozoic compositions. The increased ferromagnesium content of Archean siliciclastic rocks stabilizes chlorite to higher temperatures and results in a biotite-rich assemblage at solidus temperatures. Accordingly, water-absent biotite dehydration melting is predicted to play a greater role in the generation of melt in the metamorphism of Archean aged units,and water-absent muscovite dehydration melting is of increasing importance through the Proterozoic and Phanerozoic. This secular variation in predicted mineral assemblages demonstrates the care with which metamorphic facies diagrams should be applied to Archean compositions. Moreover, secular changes in the composition of shale and greywacke is reflected in the evolution of anatectic melt towards an increasingly less viscous, Ca-rich, and Mg-poor monzogranite.展开更多
1.Introduction Uniformitarianism is a traditional approach used in many areas of geoscience that assumes the geologic processes observed today operated similarly throughout all of Earth history（Hutton,1788;Windley,1...1.Introduction Uniformitarianism is a traditional approach used in many areas of geoscience that assumes the geologic processes observed today operated similarly throughout all of Earth history（Hutton,1788;Windley,1993）,with such an ideology commonly encapsulated by the maxim＂the present is the key to the past＂.This concept is closely associated with the philosophical principle of Occam’s razor.展开更多
The global long-term sea level trend is obtained from the analysis of tide gauge data and TOPEX/Poseidon data. The linear trend of global mean sea level is highly non-uniform spatially, with an average rate of 2.2 mmy...The global long-term sea level trend is obtained from the analysis of tide gauge data and TOPEX/Poseidon data. The linear trend of global mean sea level is highly non-uniform spatially, with an average rate of 2.2 mmyear^-1 in T/P sea-level rise from October 1992 to September 2002. Sea level change due to temperature variation （the thermosteric sea level） is discussed. The results are compared with TOPEX/Poseidon altimeter data in the same temporal span at different spatial scales. It is indicated that the thermal effect accounts for 86% and 73% of the observed seasonal variability in the northern and southern hemispheres, respectively. The TOPEX/Poseidon observed sea level lags behind the TSL by 2 months in the zonal band of 40%-60% in both the northern and southern hemispheres. Systematic differences of about 1-2 cm between TOPEX/Poseidon observations and thermosteric sea level data are obtained. The potential causes tbr these differences include water exchange among the atmosphere, land, and oceans, and some possible deviations in thermosteric contribution estimates and geophysical corrections to the TOPEX/Poseidon data.展开更多
The absence of ultrahigh pressure(UHP)orogenic eclogite in the geological record older than c.0.6 Ga is problematic for evidence of subduction having begun on Earth during the Archean(4.0-2.5 Ga).Many eclogites in Pha...The absence of ultrahigh pressure(UHP)orogenic eclogite in the geological record older than c.0.6 Ga is problematic for evidence of subduction having begun on Earth during the Archean(4.0-2.5 Ga).Many eclogites in Phanerozoic and Proterozoic terranes occur as mafic boudins encased within low-density felsic crust,which provides positive buoyancy during subduction;however,recent geochemical proxy analysis shows that Archean continental crust was more mafic than previously thought,having greater proportions of basalt and komatiite than modern-day continents.Here,we show via petrological modelling that secular change in the petrology and bulk composition of upper continental crust would make Archean continental terranes negatively buoyant in the mantle before reaching UHP conditions.Subducted or delaminated Archean continental crust passes a point of no return during metamorphism in the mantle prior to the stabilization of coesite,while Proterozoic and Phanerozoic terranes remain positively buoyant at these depths.UHP orogenic eclogite may thus readily have formed on the Archean Earth,but could not have been exhumed,weakening arguments for a Neoproterozoic onset of subduction and plate tectonics.Further,isostatic balance calculations for more mafic Archean continents indicate that the early Earth was covered by a global ocean over 1 km deep,corroborating independent isotopic evidence for large-scale emergence of the continents no earlier than c.3 Ga.Our findings thus weaken arguments that early life on Earth likely emerged in shallow subaerial ponds,and instead support hypotheses involving development at hydrothermal vents in the deep ocean.展开更多
Background:The 6-minute walking distance(6MWD)is an excellent measure of both functional endurance and health.The primary aim of this study was to estimate temporal trends in 6MWD for older Japanese adults between 199...Background:The 6-minute walking distance(6MWD)is an excellent measure of both functional endurance and health.The primary aim of this study was to estimate temporal trends in 6MWD for older Japanese adults between 1998 and 2017;the secondary aim was to estimate concurrent trends in body size(i.e.,height and mass)and self-reported participation in exercise/sport.Methods:Adults aged 65-79 years were included.Annual nationally representative 6MWD data(n=103,505)for the entire period were obtained from the Japanese Ministry of Education,Culture,Sports,Science and Technology.Temporal trends in means(and relative frequencies)were estimated at the gender-age level by best-fitting sample-weighted linear/polynomial regression models,with national trends estimated by a post-stratified population-weighting procedure.Temporal trends in distributional variability were estimated as the ratio of coefficients of variation.Results:Between 1998 and 2017 there was a steady,moderate improvement in mean 6MWD(absolute=45 m(95%confidence interval(95%CI):43-47);percent=8.0%(95%CI:7.6%-8.4%);effect size=0.51(95%CI:0.48-0.54)).Gender-and age-related temporal differences in means were negligible.Variability in 6MWD declined substantially(ratio of coefficients of variation=0.89,95%CI:0.87-0.92),with declines larger for women compared to men,and for 75-79-year-olds compared to 65-74-year-olds.Correspondingly,there were moderate and negligible increases in mean height and mass,respectively,and negligible increases in the percentage who participated in exercise/sport at least 3 days per week and at least 30 min per session.Conclusion:There has been a steady,moderate improvement in mean 6MWD for older Japanese adults since 1998,which is suggestive of corresponding improvements in both functional endurance and health.The substantial decline in variability indicates that the temporal improvement in mean 6MWD was not uniform across the distribution.Trends in 6MWD are probably influenced by corresponding trends in body size and/or participation in exercise/sport.展开更多
The trace element composition of zircon reveals information about the melt that they are derived from,as such,detrital zircon trace element compositions can be used to interrogate melt compositions,and thus the evolut...The trace element composition of zircon reveals information about the melt that they are derived from,as such,detrital zircon trace element compositions can be used to interrogate melt compositions,and thus the evolution of the continental crust in time and space.Here,we present a global database of detrital zircon compositions and use it to test whether average global trends for five common petrogenetic proxies truly represent secular changes in continental evolution.We demonstrate that the secular trend is broadly comparable across continental regions for Ti-in-zircon temperatures,but for other trace element ratios interrogated,secular trends are highly variable between continental regions.Because trace element ratios result from multiple petrologic variables,we argue that these petrogenetic proxies can be overinterpreted if projected to global geologic processes.In particular,we caution against the interpretation of crustal thickness from trace elements in zircon,and we argue that our results negate current hypotheses concerning secular changes in crustal thickness.展开更多
基金supported by the National Natural Science Foundation of China(81001249,30972495)
文摘Objective To analyze and assess secular change in stature in rural children and adolescents in China from 1985 to 2010. Methods Data were obtained from the 6 rounds of the Chinese National Survey on Student＇s Constitution and Health. The subjects enrolled in the study were children and adolescents aged 7-18 years in rural areas of provincial capitals. Results An overall positive secular trend in stature occurred in rural areas of provincial capitals in China from 1985 to 2010. The overall average increase rates were 3.1 and 2.4 cm/decade for boys and girls, respectively. The total body height increases for grown up boys and girls were 3.6 and 2.3 cm and the increase rates were 1.4 and 0.9 cm/decade, respectively. There were differences in body height increase among eastern, central and western regions. The average body height of the children or adolescents in eastern region was highest, followed by central region and western region. The overall increase rates in central region were highest among the three regions. The difference between eastern/central region and western region was obvious. 〈br〉 Conclusion Positive secular trend in stature of children or adolescents has occurred in rural area of China, and rural boys and girls showed a great potential for continuous growth. More attention should be paid to the differences in children＇s body height between western region and eastern/central region.
基金supported by National Natural Science Foundation of China(30972495,81001249)
文摘Objective To analyze the change in Body Mass Index （BMI） distribution among Chinese children and adolescents for the development of more effective intervention for childhood obesity. Methods Data on the national students＇ constitution and health survey between 1985 and 2010 was used for this study. Subjects were students aged 7-18 randomly selected from 30 provinces in China. BMI for-age curves were developed by LMS method, and the trend of BMI distribution was determined by comparing the upper BMI percentiles and analyzing the skew shift of distribution between 2985 and 2010. Results An overall positive swift trend of BMI between 1985 and 2010 was observed among the Chinese school-age children and adolescents. The average median of the BMI increased from 16.8 and 17.0 ks/m2 to 18.2 and 17.9 kg/m2 in 25 years, with increments 0.56 and 0.36 kg/m2 per decade for males and females, respectively. The more obvious increments were found at the high BMI. The total increments of BMI in this period were 4.03 and 2.20 kg/m2 at the 85th, 6.24 and 3.57 kg/m2 at the 95th, and 6.99 and 4.27 kg/m2 at the 97th percentiles, for males and females, respectively. Conclusion Obvious increments were observed at high BMI of the Chinese children and adolescents. More effective interventions should be taken for control and prevention of obesity and its health consequence for these subgroups. It is necessary to establish a risk-complex system consisting of the identification of BMI scope, the screen of the disease risk factors and the assessment of excessive adiposity.
基金supported by the National Natural Science Foundation of China(30972495,81001249)
文摘Objective Research evidence shows a secular trend in Chinese physical growth in recent years.The aim of this study was to analyze and assess changes in stature of children and adolescents during the 25 years from 1985‐2010,using national data.Methods Data came from successive cycles of the Chinese National Survey on Students＇ Constitution and Health（CNSSCH）.Subjects were 7‐ to 18‐year‐old children and adolescents.Results An overall positive secular trend occurred in urban China during 1985‐2010.The overall average rates of increment were 2.4 and 1.7 cm/decade for boys and girls,respectively.Total increases in adult stature for boys and girls were 2.6 and 1.7 cm,yielding rates of 1.0 and 0.7 cm/decade,respectively.Cities with different socioeconomic levels had different characteristic trends.Mean stature increases in big cities were larger than those in moderate and small cities,and boys and girls in moderate and small cities showed greater potential for growth in stature.Conclusion An overall positive secular growth trend was associated with socioeconomic progress and differed with area socioeconomic levels.School policies and strategies should be developed based on increased stature,and should continue narrowing the inequity between different socioeconomic populations.
文摘Shale and greywacke compositions from the Archean to Phanerozoic record a secular change in the siliciclastic material that comprises much of Earth＇s continental margins, past and present. This study explores the metamorphic consequence of these compositional changes, by comparing phase equilibrium models constructed for average Archean, Proterozoic, and Phanerozoic shale and greywacke compositions equilibrated along two Barrovian-type geotherms： 1330℃/GPa（A） and 800 ℃/GPa（B）. Our models show that Archean siliciclastic rocks can retain up to 4 vol.% water at middle to lower crustal conditions, nearly twice that of Proterozoic and Phanerozoic compositions. The increased ferromagnesium content of Archean siliciclastic rocks stabilizes chlorite to higher temperatures and results in a biotite-rich assemblage at solidus temperatures. Accordingly, water-absent biotite dehydration melting is predicted to play a greater role in the generation of melt in the metamorphism of Archean aged units,and water-absent muscovite dehydration melting is of increasing importance through the Proterozoic and Phanerozoic. This secular variation in predicted mineral assemblages demonstrates the care with which metamorphic facies diagrams should be applied to Archean compositions. Moreover, secular changes in the composition of shale and greywacke is reflected in the evolution of anatectic melt towards an increasingly less viscous, Ca-rich, and Mg-poor monzogranite.
文摘1.Introduction Uniformitarianism is a traditional approach used in many areas of geoscience that assumes the geologic processes observed today operated similarly throughout all of Earth history（Hutton,1788;Windley,1993）,with such an ideology commonly encapsulated by the maxim＂the present is the key to the past＂.This concept is closely associated with the philosophical principle of Occam’s razor.
基金supported by the NSFC projects (Nos. 40376005, 40676013, 40506006 and 40676015)the SRFDP project (No. 20060423014)+1 种基金NCET-04-0646 Key Scientific Research Program (No. 2007CB411807)National Key Technology R&D Program (No. 2007BAC- 03A06-06)
文摘The global long-term sea level trend is obtained from the analysis of tide gauge data and TOPEX/Poseidon data. The linear trend of global mean sea level is highly non-uniform spatially, with an average rate of 2.2 mmyear^-1 in T/P sea-level rise from October 1992 to September 2002. Sea level change due to temperature variation （the thermosteric sea level） is discussed. The results are compared with TOPEX/Poseidon altimeter data in the same temporal span at different spatial scales. It is indicated that the thermal effect accounts for 86% and 73% of the observed seasonal variability in the northern and southern hemispheres, respectively. The TOPEX/Poseidon observed sea level lags behind the TSL by 2 months in the zonal band of 40%-60% in both the northern and southern hemispheres. Systematic differences of about 1-2 cm between TOPEX/Poseidon observations and thermosteric sea level data are obtained. The potential causes tbr these differences include water exchange among the atmosphere, land, and oceans, and some possible deviations in thermosteric contribution estimates and geophysical corrections to the TOPEX/Poseidon data.
文摘The absence of ultrahigh pressure(UHP)orogenic eclogite in the geological record older than c.0.6 Ga is problematic for evidence of subduction having begun on Earth during the Archean(4.0-2.5 Ga).Many eclogites in Phanerozoic and Proterozoic terranes occur as mafic boudins encased within low-density felsic crust,which provides positive buoyancy during subduction;however,recent geochemical proxy analysis shows that Archean continental crust was more mafic than previously thought,having greater proportions of basalt and komatiite than modern-day continents.Here,we show via petrological modelling that secular change in the petrology and bulk composition of upper continental crust would make Archean continental terranes negatively buoyant in the mantle before reaching UHP conditions.Subducted or delaminated Archean continental crust passes a point of no return during metamorphism in the mantle prior to the stabilization of coesite,while Proterozoic and Phanerozoic terranes remain positively buoyant at these depths.UHP orogenic eclogite may thus readily have formed on the Archean Earth,but could not have been exhumed,weakening arguments for a Neoproterozoic onset of subduction and plate tectonics.Further,isostatic balance calculations for more mafic Archean continents indicate that the early Earth was covered by a global ocean over 1 km deep,corroborating independent isotopic evidence for large-scale emergence of the continents no earlier than c.3 Ga.Our findings thus weaken arguments that early life on Earth likely emerged in shallow subaerial ponds,and instead support hypotheses involving development at hydrothermal vents in the deep ocean.
文摘Background:The 6-minute walking distance(6MWD)is an excellent measure of both functional endurance and health.The primary aim of this study was to estimate temporal trends in 6MWD for older Japanese adults between 1998 and 2017;the secondary aim was to estimate concurrent trends in body size(i.e.,height and mass)and self-reported participation in exercise/sport.Methods:Adults aged 65-79 years were included.Annual nationally representative 6MWD data(n=103,505)for the entire period were obtained from the Japanese Ministry of Education,Culture,Sports,Science and Technology.Temporal trends in means(and relative frequencies)were estimated at the gender-age level by best-fitting sample-weighted linear/polynomial regression models,with national trends estimated by a post-stratified population-weighting procedure.Temporal trends in distributional variability were estimated as the ratio of coefficients of variation.Results:Between 1998 and 2017 there was a steady,moderate improvement in mean 6MWD(absolute=45 m(95%confidence interval(95%CI):43-47);percent=8.0%(95%CI:7.6%-8.4%);effect size=0.51(95%CI:0.48-0.54)).Gender-and age-related temporal differences in means were negligible.Variability in 6MWD declined substantially(ratio of coefficients of variation=0.89,95%CI:0.87-0.92),with declines larger for women compared to men,and for 75-79-year-olds compared to 65-74-year-olds.Correspondingly,there were moderate and negligible increases in mean height and mass,respectively,and negligible increases in the percentage who participated in exercise/sport at least 3 days per week and at least 30 min per session.Conclusion:There has been a steady,moderate improvement in mean 6MWD for older Japanese adults since 1998,which is suggestive of corresponding improvements in both functional endurance and health.The substantial decline in variability indicates that the temporal improvement in mean 6MWD was not uniform across the distribution.Trends in 6MWD are probably influenced by corresponding trends in body size and/or participation in exercise/sport.
基金supported by funding from the UK Natural Environment Research Council(NE/Y00549/1)supported by NERC Highlight Topic award"FAMOS"(From arc magmas to ores)NE/P01724X/1(British Geological Survey).
文摘The trace element composition of zircon reveals information about the melt that they are derived from,as such,detrital zircon trace element compositions can be used to interrogate melt compositions,and thus the evolution of the continental crust in time and space.Here,we present a global database of detrital zircon compositions and use it to test whether average global trends for five common petrogenetic proxies truly represent secular changes in continental evolution.We demonstrate that the secular trend is broadly comparable across continental regions for Ti-in-zircon temperatures,but for other trace element ratios interrogated,secular trends are highly variable between continental regions.Because trace element ratios result from multiple petrologic variables,we argue that these petrogenetic proxies can be overinterpreted if projected to global geologic processes.In particular,we caution against the interpretation of crustal thickness from trace elements in zircon,and we argue that our results negate current hypotheses concerning secular changes in crustal thickness.
