Purpose： In age-restricted youth sport, the over-selection of athletes born in the first quarter of the year and under-selection of athletes born in the last quarter of the year has been called the relative age effe...Purpose： In age-restricted youth sport, the over-selection of athletes born in the first quarter of the year and under-selection of athletes born in the last quarter of the year has been called the relative age effect （RAE）. Its existence in youth sports like soccer is well established. Why it occurs has not been identified, however, one thought is that older players, generally taller and heavier, are thought to improve the team＇s chances of winning. To test this assumption, birth dates and match outcome were correlated to see if teams with the oldest mean age had a systematic advantage against teams with younger mean ages. Methods： Player birth dates and team records （n = 5943 players on 371 teams; both genders; U11-U16） were obtained from the North Carolina Youth Soccer Association for the highest level of statewide youth competition. Results： The presence of an RAE was demonstrated with significant oversampling from players born in the I st vs. the 4th quarter （overall： 29.6% vs. 20.9% respectively, p 〈 0.0001）. Mean team age was regressed on match outcomes （winning %, points/match, points/goal, and goals for, against, and goal difference）, but there was no evidence of any systematic influence of mean team age and match outcomes, except possibly in U11 males. Conclusion： Selecting players based on physical maturity （and subsequently, on age） does not appear to have any systematic influence on match outcome or season record in youth soccer suggesting that the selection process should be focused on player ability and not on physical maturation.展开更多
Estimation of fire cycle has been conducted by using the negative exponential function as an approximation of time-since-fire distribution of a landscape assumed to be homogeneous with respect to fire spread processes...Estimation of fire cycle has been conducted by using the negative exponential function as an approximation of time-since-fire distribution of a landscape assumed to be homogeneous with respect to fire spread processes. The authors imposed predefined fire cycles on a virtual landscape of 100 cell×100 cell, and obtained a mosaic composing of patches with different stand ages （i.e. time since fire）. Graphical and statistical methods （Van Wagner 1978; Reed et al. 1998） were employed to derive fire cycle from the virtual landscape. By comparing the predefined and the derived fire cycles, the two methods and tested the effects of sample size and hazard of burning （i.e., stand＇s susceptibility to fire in relation to its stand age） were evaluated on fire cycle deviation. The simulation results indicated a minimum sample size of l0 times of the annual burnt area would be required for.partitioning time-since-fire distribution into homogeneous epochs indicating temporal change in fire cycle. Statistically, there was significant difference among the imposed and the derived fire cycle, regardless of sample sizes with or without consideration of hazard of burning. Both methods underestimated the more recent fire cycle without significant difference between them. The results imply that deviation of fire cycle based on time-since-fire distribution warrants cautious interpretation, especially when a landscape is spatially partitioned into small units and temporal changes in fire cycle are involved.展开更多
This research intends to study the relationship between faith, media exposure, and national identity construction of youth in Pakistan. The purpose is to ascertain the level of influence of foreign and local media con...This research intends to study the relationship between faith, media exposure, and national identity construction of youth in Pakistan. The purpose is to ascertain the level of influence of foreign and local media consumption on national identity formation in terms of collective self-esteem and self-image of youth with high and low level of religiosity. A survey has been conducted from students （n = 321） between the age group of 16-19 living in Lahore. The results of this study revealed that respondents with high religiosity did not prefer to consume foreign media （r = -0.435＊＊ p 〈 0.01） whereas they did not show much preference to consume Pakistani media, either （r = 0.138＊, p 〈 0.05）. The level of religiosity and positive national identity had a strong and significant positive correlation （r = 0.619＊＊, p 〈 0.01）. This study also found that those respondents who preferred to consume foreign media texts demonstrated lower self-esteem and negative self-image as Pakistanis as compared to those who did not prefer foreign media consumption （r = -0.427＊＊, p 〈 0.01）. The researcher assumed that being Pakistani, a respondent would prefer to consume more national media texts over foreign and would have more positive national identity. However, results did not support this premise （r = 0.159＊＊, p 〈 0.01） due to the fact that the respondents did not show preference to consume Pakistani media at first hand. The study also connects theoretical understanding of faith and identity in Pakistani perspective along with an additional factor of media consumption. Thus, it strengthens the argument that strong faith positively contributes towards consolidating an individual＇s identity construction process. However, the results demonstrate that media tend to play a limited role in the process of identity construction compared to family and peers among Pakistani youth.展开更多
Fluid flow and mixing phenomenon have a significant impact on coagulation and flocculation processes. Particles dissipating the turbulent kinetic energy increase the efficiency of collision, grow in size and incorpora...Fluid flow and mixing phenomenon have a significant impact on coagulation and flocculation processes. Particles dissipating the turbulent kinetic energy increase the efficiency of collision, grow in size and incorporate phosphate from the wastewater Only certain flocks can be separated depending on their stability, size, density, etc.. According to the literature the velocity gradient of the flow （G-value） is the main design parameter of the flocculators, but there is a need to take into account at least the flocks age, too. In this paper, it presents a novel approach to determine the efficiency of flocculators using local mean age theory, residence time distribution and dimensional analysis. Calculations were performed for two constructions of cascade reactors---one with small baffles and one without these; hydraulical performance and the achievable conversion were compared. As a result, the flocculator with small baffles proved to be more efficient than the traditional construction.展开更多
In this study,we investigated(i)the differences in flower colour composition among growth forms of woody plants in China and(ii)the influences of biogeographic regions,evolutionary age and climatic conditions on geogr...In this study,we investigated(i)the differences in flower colour composition among growth forms of woody plants in China and(ii)the influences of biogeographic regions,evolutionary age and climatic conditions on geographic variation in the proportions of different flower colours.Using distribution maps and flower colour information(white,red,yellow,yellow-green,green and blue-purple)of 7673 Chinese woody plant species and a dated genus-level phylogenetic tree,we compared flower colour composition among different growth forms(shrubs,trees and lianas).We further estimated the relationships of geographical patterns in the proportions of different flower colours with seven different biogeographic regions,evolutionary age and different contemporary climatic variables.Compared with trees or lianas,shrubs showed a higher proportion of species with anthocyanin-based red and blue-purple flowers.The geographic patterns of flower colour composition of woody plants in China were strongly influenced by regional effects and contemporary climate,especially precipitation and ultraviolet B irradiance.The proportion of species with presumably bee-pollinated yellow and blue-purple flowers and stress tolerant anthocyanin-based red and blue-purple flower colours tended to be high in the northwestern part of China.Green flowers tended to evolve earlier than others,but evolutionary age had quite weak influences on the geographic pattern of flower colours.Our results reflect both evolutionary and environmental constraints on the distribution of flower colours of woody plants in China.展开更多
The present paper proposes a new scheme for identifying free surface particles in an improved SPH (Smoothed Particle Hydrodynamics). With the development of the SPH, free surface identification becomes a key challenge...The present paper proposes a new scheme for identifying free surface particles in an improved SPH (Smoothed Particle Hydrodynamics). With the development of the SPH, free surface identification becomes a key challenge in free surface flow simulations, especially for violent breaking water waves. According to numerical tests, existing free surface identified schemes are not reliable for weakly compressible SPH when violent waves are modeled. The new free surface identification scheme suggested here considers changes in density ratio and three auxiliary functions. Although this new scheme originates from a scheme for another meshfree method (MLPG_R method), it includes several improvements, especially developed for the improved SPH. The limited numerical tests have indicated that the scheme does not significantly increase CPU time required, but it considerably improves the identification of free surface particles.展开更多
Immunosenescence is described as a decline in the normal functioning of the immune system associated with physiologic ageing.Immunosenescence contributes to reduced efficacy to vaccination and increased susceptibility...Immunosenescence is described as a decline in the normal functioning of the immune system associated with physiologic ageing.Immunosenescence contributes to reduced efficacy to vaccination and increased susceptibility to infectious diseases in the elderly.Extensive studies of laboratory animal models of ageing or donor lymphocyte analysis have identified changes in immunity caused by the ageing process.Most of these studies have identified phenotypic and functional changes in innate and adaptive immunity.However,it is unclear which of these defects are critical for impaired immune defense against infection.This review describes the changes that occur in innate and adaptive immunity with ageing and some age-related viral diseases where defects in a key component of immunity contribute to the high mortality rate in mouse models of ageing.展开更多
To better understand the Pan-African-early Paleozoic tectonothermal events of the Nyainrong microcontinent and the con- straints on its tectonic evolution, here we report the results of zircon LA-ICP-MS U-Pb dating an...To better understand the Pan-African-early Paleozoic tectonothermal events of the Nyainrong microcontinent and the con- straints on its tectonic evolution, here we report the results of zircon LA-ICP-MS U-Pb dating and geochemical features of Amdo gneiss in the Nyainrong microcontinent. The outcrops of Amdo gneiss is about 30 km south of Amdo County in north- ern Tibet. The field occurrence, mineral composition, textural characteristics, and whole-rock geochemical features of the four gneiss samples indicate the protolith of the gneisses is intermediate-acid intrusive rock. Gneiss zircon trace element tracing and genetic analysis shows that zircon has typical characteristics of magmatic zircon. The 2~6pbF38U concordant age of zircon is 505-517 Ma, corresponding to the Middle-Late Cambrian, which is the formation age of the protolith. The samples have char- acteristics of high silicon, alkali-rich, alkalic rate AR =1.73-3.7, the differentiation index DI = 70.78-90.28; rock aluminum saturation index ranges from 1.02 to 1.05, FeO / MgO ranges from 2.63 to 4.50, 10000 x Ga/AI ranges from 2.12 to 2.41, and P205 and A1203 content decreased with SiO2 increasing. Th and Y contents have a good positive correlation with Rb content; the genetic type of protolith of the gneiss is the differentiation of subalkaline over aluminum I-type granite. Combined with re- gional data, the tectonic setting of the Amdo gneiss protolith is closely related to the collision orogenic process. The prelimi- nary view is that the Middle-Late Cambrian magmatic events developed on the microcontinent could be the result of Andean- type orogeny along the Gondwana super-continental margin after the end of the Pan-African orogeny.展开更多
During migration, birds can show different responses to wind in relation to distance to the goal, experience, ecologi- cal barriers and visibility of landmarks. We analysed the effect of wind （tailwinds and crosswind...During migration, birds can show different responses to wind in relation to distance to the goal, experience, ecologi- cal barriers and visibility of landmarks. We analysed the effect of wind （tailwinds and crosswinds） on daily movement rates （for- ward and perpendicular） of Eleonora＇s falcons using ARGOS satellite telemetry, during their trans-continental autumn migration to Madagascar, in relation to the different crossed regions and individuals＇ age class. Our results showed that the effect of wind on daily movement rates was not uniform, being stronger in the farthest region from the migration goal, the Sahara desert, with adults being more affected than juveniles in this region. In the Sahel, the results were more conflicting, perhaps because daily movements were more shaped by the distribution of food resources. In Equatorial Africa, daily movement rates were mainly af- fected by crosswinds. Still, it remains unclear which orientation mechanism allows Eleonora＇s falcons to reach such a narrow wintering area compensating also for wind displacement展开更多
文摘Purpose： In age-restricted youth sport, the over-selection of athletes born in the first quarter of the year and under-selection of athletes born in the last quarter of the year has been called the relative age effect （RAE）. Its existence in youth sports like soccer is well established. Why it occurs has not been identified, however, one thought is that older players, generally taller and heavier, are thought to improve the team＇s chances of winning. To test this assumption, birth dates and match outcome were correlated to see if teams with the oldest mean age had a systematic advantage against teams with younger mean ages. Methods： Player birth dates and team records （n = 5943 players on 371 teams; both genders; U11-U16） were obtained from the North Carolina Youth Soccer Association for the highest level of statewide youth competition. Results： The presence of an RAE was demonstrated with significant oversampling from players born in the I st vs. the 4th quarter （overall： 29.6% vs. 20.9% respectively, p 〈 0.0001）. Mean team age was regressed on match outcomes （winning %, points/match, points/goal, and goals for, against, and goal difference）, but there was no evidence of any systematic influence of mean team age and match outcomes, except possibly in U11 males. Conclusion： Selecting players based on physical maturity （and subsequently, on age） does not appear to have any systematic influence on match outcome or season record in youth soccer suggesting that the selection process should be focused on player ability and not on physical maturation.
文摘Estimation of fire cycle has been conducted by using the negative exponential function as an approximation of time-since-fire distribution of a landscape assumed to be homogeneous with respect to fire spread processes. The authors imposed predefined fire cycles on a virtual landscape of 100 cell×100 cell, and obtained a mosaic composing of patches with different stand ages （i.e. time since fire）. Graphical and statistical methods （Van Wagner 1978; Reed et al. 1998） were employed to derive fire cycle from the virtual landscape. By comparing the predefined and the derived fire cycles, the two methods and tested the effects of sample size and hazard of burning （i.e., stand＇s susceptibility to fire in relation to its stand age） were evaluated on fire cycle deviation. The simulation results indicated a minimum sample size of l0 times of the annual burnt area would be required for.partitioning time-since-fire distribution into homogeneous epochs indicating temporal change in fire cycle. Statistically, there was significant difference among the imposed and the derived fire cycle, regardless of sample sizes with or without consideration of hazard of burning. Both methods underestimated the more recent fire cycle without significant difference between them. The results imply that deviation of fire cycle based on time-since-fire distribution warrants cautious interpretation, especially when a landscape is spatially partitioned into small units and temporal changes in fire cycle are involved.
文摘This research intends to study the relationship between faith, media exposure, and national identity construction of youth in Pakistan. The purpose is to ascertain the level of influence of foreign and local media consumption on national identity formation in terms of collective self-esteem and self-image of youth with high and low level of religiosity. A survey has been conducted from students （n = 321） between the age group of 16-19 living in Lahore. The results of this study revealed that respondents with high religiosity did not prefer to consume foreign media （r = -0.435＊＊ p 〈 0.01） whereas they did not show much preference to consume Pakistani media, either （r = 0.138＊, p 〈 0.05）. The level of religiosity and positive national identity had a strong and significant positive correlation （r = 0.619＊＊, p 〈 0.01）. This study also found that those respondents who preferred to consume foreign media texts demonstrated lower self-esteem and negative self-image as Pakistanis as compared to those who did not prefer foreign media consumption （r = -0.427＊＊, p 〈 0.01）. The researcher assumed that being Pakistani, a respondent would prefer to consume more national media texts over foreign and would have more positive national identity. However, results did not support this premise （r = 0.159＊＊, p 〈 0.01） due to the fact that the respondents did not show preference to consume Pakistani media at first hand. The study also connects theoretical understanding of faith and identity in Pakistani perspective along with an additional factor of media consumption. Thus, it strengthens the argument that strong faith positively contributes towards consolidating an individual＇s identity construction process. However, the results demonstrate that media tend to play a limited role in the process of identity construction compared to family and peers among Pakistani youth.
文摘Fluid flow and mixing phenomenon have a significant impact on coagulation and flocculation processes. Particles dissipating the turbulent kinetic energy increase the efficiency of collision, grow in size and incorporate phosphate from the wastewater Only certain flocks can be separated depending on their stability, size, density, etc.. According to the literature the velocity gradient of the flow （G-value） is the main design parameter of the flocculators, but there is a need to take into account at least the flocks age, too. In this paper, it presents a novel approach to determine the efficiency of flocculators using local mean age theory, residence time distribution and dimensional analysis. Calculations were performed for two constructions of cascade reactors---one with small baffles and one without these; hydraulical performance and the achievable conversion were compared. As a result, the flocculator with small baffles proved to be more efficient than the traditional construction.
基金supported by the National Key Research Develop Program of China(2019YFC0507501,2017YFA0605101)National Natural Science Foundation of China(32025025,31988102).
文摘In this study,we investigated(i)the differences in flower colour composition among growth forms of woody plants in China and(ii)the influences of biogeographic regions,evolutionary age and climatic conditions on geographic variation in the proportions of different flower colours.Using distribution maps and flower colour information(white,red,yellow,yellow-green,green and blue-purple)of 7673 Chinese woody plant species and a dated genus-level phylogenetic tree,we compared flower colour composition among different growth forms(shrubs,trees and lianas).We further estimated the relationships of geographical patterns in the proportions of different flower colours with seven different biogeographic regions,evolutionary age and different contemporary climatic variables.Compared with trees or lianas,shrubs showed a higher proportion of species with anthocyanin-based red and blue-purple flowers.The geographic patterns of flower colour composition of woody plants in China were strongly influenced by regional effects and contemporary climate,especially precipitation and ultraviolet B irradiance.The proportion of species with presumably bee-pollinated yellow and blue-purple flowers and stress tolerant anthocyanin-based red and blue-purple flower colours tended to be high in the northwestern part of China.Green flowers tended to evolve earlier than others,but evolutionary age had quite weak influences on the geographic pattern of flower colours.Our results reflect both evolutionary and environmental constraints on the distribution of flower colours of woody plants in China.
基金supported by the National Natural Science Foundation of China (Grant No. 51009034)Foundational Research Funds for the Central Universities (Grant No. HEUCF100102)111 Program (Grant No.B07019)
文摘The present paper proposes a new scheme for identifying free surface particles in an improved SPH (Smoothed Particle Hydrodynamics). With the development of the SPH, free surface identification becomes a key challenge in free surface flow simulations, especially for violent breaking water waves. According to numerical tests, existing free surface identified schemes are not reliable for weakly compressible SPH when violent waves are modeled. The new free surface identification scheme suggested here considers changes in density ratio and three auxiliary functions. Although this new scheme originates from a scheme for another meshfree method (MLPG_R method), it includes several improvements, especially developed for the improved SPH. The limited numerical tests have indicated that the scheme does not significantly increase CPU time required, but it considerably improves the identification of free surface particles.
文摘Immunosenescence is described as a decline in the normal functioning of the immune system associated with physiologic ageing.Immunosenescence contributes to reduced efficacy to vaccination and increased susceptibility to infectious diseases in the elderly.Extensive studies of laboratory animal models of ageing or donor lymphocyte analysis have identified changes in immunity caused by the ageing process.Most of these studies have identified phenotypic and functional changes in innate and adaptive immunity.However,it is unclear which of these defects are critical for impaired immune defense against infection.This review describes the changes that occur in innate and adaptive immunity with ageing and some age-related viral diseases where defects in a key component of immunity contribute to the high mortality rate in mouse models of ageing.
基金supported by National Natural Science Foundation of China(Grant Nos.41072166 and 41272240)Program of China Geological Survey(Grant Nos.1212011121248,1212011221093)
文摘To better understand the Pan-African-early Paleozoic tectonothermal events of the Nyainrong microcontinent and the con- straints on its tectonic evolution, here we report the results of zircon LA-ICP-MS U-Pb dating and geochemical features of Amdo gneiss in the Nyainrong microcontinent. The outcrops of Amdo gneiss is about 30 km south of Amdo County in north- ern Tibet. The field occurrence, mineral composition, textural characteristics, and whole-rock geochemical features of the four gneiss samples indicate the protolith of the gneisses is intermediate-acid intrusive rock. Gneiss zircon trace element tracing and genetic analysis shows that zircon has typical characteristics of magmatic zircon. The 2~6pbF38U concordant age of zircon is 505-517 Ma, corresponding to the Middle-Late Cambrian, which is the formation age of the protolith. The samples have char- acteristics of high silicon, alkali-rich, alkalic rate AR =1.73-3.7, the differentiation index DI = 70.78-90.28; rock aluminum saturation index ranges from 1.02 to 1.05, FeO / MgO ranges from 2.63 to 4.50, 10000 x Ga/AI ranges from 2.12 to 2.41, and P205 and A1203 content decreased with SiO2 increasing. Th and Y contents have a good positive correlation with Rb content; the genetic type of protolith of the gneiss is the differentiation of subalkaline over aluminum I-type granite. Combined with re- gional data, the tectonic setting of the Amdo gneiss protolith is closely related to the collision orogenic process. The prelimi- nary view is that the Middle-Late Cambrian magmatic events developed on the microcontinent could be the result of Andean- type orogeny along the Gondwana super-continental margin after the end of the Pan-African orogeny.
文摘During migration, birds can show different responses to wind in relation to distance to the goal, experience, ecologi- cal barriers and visibility of landmarks. We analysed the effect of wind （tailwinds and crosswinds） on daily movement rates （for- ward and perpendicular） of Eleonora＇s falcons using ARGOS satellite telemetry, during their trans-continental autumn migration to Madagascar, in relation to the different crossed regions and individuals＇ age class. Our results showed that the effect of wind on daily movement rates was not uniform, being stronger in the farthest region from the migration goal, the Sahara desert, with adults being more affected than juveniles in this region. In the Sahel, the results were more conflicting, perhaps because daily movements were more shaped by the distribution of food resources. In Equatorial Africa, daily movement rates were mainly af- fected by crosswinds. Still, it remains unclear which orientation mechanism allows Eleonora＇s falcons to reach such a narrow wintering area compensating also for wind displacement
