In rapid socio-economic developme nt,the process of concentration and dispersal of various elements tends to be more dramatic,tremendously in fluencing the shaping and transform ation of the space in metropolitan area...In rapid socio-economic developme nt,the process of concentration and dispersal of various elements tends to be more dramatic,tremendously in fluencing the shaping and transform ation of the space in metropolitan area.Survey of spatial concentration and decent ralization has thus become a basic me thod in examining metropolitan spatial evolution.In this research,three elements were selected as the essential indicato rs of the process:demographic density distribu-tion,employment density distribut ion and business office location.Performance of these elements in Nanji ng City was exam-ined historically.As Nanjing City c ould be regarded as a representative of metropolitan areas in China,its s ituation large-ly suggestes the general characteristics in similar areas of China.Hence based on the investigation of Nanji ng City,four general implications were highligh ted.First,metropolitan areas inChina are in a violentprocess and shift of spatialconcentra-tion and decentralization.Second,from now to at least the near future,c oncentration will continue to be the central fea-ture.Third,the landscape of metrop olitan areas basically exhibits a dual structure character.The gap in en vironmental and ecological qualities among different districts will continue for a l ong time.Fourth,Central Business District(CBD)is playing an important role in helpi ng to convert the traditionally single-centered city structure into a polycentric one.展开更多
The effects of algal concentration and initial density on the population growth of the estuarine cladocera, Diaphanosoma celebensis Stingelin, were evaluated in an indoor experiment. A 2 × 4 layout that included ...The effects of algal concentration and initial density on the population growth of the estuarine cladocera, Diaphanosoma celebensis Stingelin, were evaluated in an indoor experiment. A 2 × 4 layout that included two algal concentrations （Chlorella pyrenoidosa, 1 × 10^6 and 3 ×10^6 cell/mL） and four inoculation densities （100, 200, 300 and 400 ind./L） were established. Diaphanosoma celebensis were reared in 150 mL flasks containing 50 mL of algal medium at 22℃, under salinity of 10 and a photoperiod of 12 h L： 12 h D. The lag phase required to initiate continuous population growth following inoculation was shorter for D. celebensis fed 1 × 10^6 cell/mL and inoculated at 300 or 400 ind./L than that for D. celebensis fed 3 × 10^6 cell/mL and inoculated at 100 or 200 ind./L. However, D. celebensis fed 3 × 10^6 cell/mL and inoculated at 100 or 200 ind./L exhibited longer periods of positive population growth The maximum population densities were 5 875 ± 324, 6 690 ± 691, 7 735 ± 1,121 and 6 365 ± 691 ind./L for D. celebensis fed 1 × 10^6 cell/mL and inoculated at 100, 200, 300 and 400 ind./L, respectively, and 15 070 ± 379, 12 215 ± 648, 11 960±2,551 and 16 130 ± 880 ind./L for D. celebensis fed 3 ×10^6 cell/mL and inoculated at 100, 200, 300 and 400 ind./L, respectively. The average daily increasing rates of population were 0.076 ± 0.001, 0.065 ± 0.002, 0.055 ±0.002 and 0.048 ± 0.003 for D. celebensis fed 1×10^6 cell/mL and inoculated at 100, 200, 300 and 400 ind./L, respectively, and 0.098± 0.001, 0.078 ± 0.002, 0.072 ± 0.003 and 0.067 ± 0.003 forD. celebensis fed 3 × 10^6 cell/mL and inoculated at 100, 200, 300 and 400 ind./L, respectively. The maximum population density and average daily increasing rate of population increased as the algal concentration increased, whereas an increase in the inoculation density led to a linear decrease in the daily increasing rate of population under both algal concentrations. The results of the present experiment indicate that the algal concentration and inoculation density significantly affect population growth of D. celebensis, Furthermore, the results suggest that the optimal algal concentration and inoculation density for the mass culture ofD. celebensis should be 3 × 10^6 cell/mL and 100 ind./L.展开更多
A distributed feedback laser with a wavelength of 2.8μm was used to measure the species produced by water vapor glow discharge.Only the absorption spectra of OH radicals and transient H2O molecules were observed usin...A distributed feedback laser with a wavelength of 2.8μm was used to measure the species produced by water vapor glow discharge.Only the absorption spectra of OH radicals and transient H2O molecules were observed using concentration modulation(CM)spectroscopy.The intensities and orientations of the absorption peaks change with the demodulation phase,but the direction of one absorption peak of H2O is always opposite to the other peaks.The different spectral orientations of OH and H2O reflect the increase or the decrease of the number of particles in the energy levels.If more transient species can be detected in the discharge process,the dynamics of excitation,ionization,and decomposition of H2O can be better studied.This study shows that the demodulation phase relationship of CM spectrum can be used to study the population change of molecular energy levels.展开更多
Within savanna environments, movements of elephant are influenced by changes in climate especially seasonal rainfall. In this study, we investigated the possible changes in elephant population based on projected rainf...Within savanna environments, movements of elephant are influenced by changes in climate especially seasonal rainfall. In this study, we investigated the possible changes in elephant population based on projected rainfall changes using regional climate models (RCM) and Representative Concentration Pathways (RCPs). The relationship between elephant and rainfall was modelled against annual, wet season, dry season rainfall based on various time lags. Future relation between elephant and rainfall was projected based on three RCPs;2.6, 4.5 and 8.5. There was a strong linear relationship between elephant and October-November-December (OND) rains with time lag of 13 years (Y = −4016.43 + 19.11x, r2 = 0.459, P = 0.006). The rainfall trends for RCP 2.6 and 4.5 showed a slight increase in annual rainfall for the period 2006-2100 but driven by OND increases. Rainfall increase for RCP 8.5 was significant and was driven by increase in both March-April-May (MAM) and OND. These rainfall dynamics had influence on the projected elephant population in the Amboseli ecosystem. For RCP 2.6 and 4.5 the elephant population increase was 2455 and 2814 respectively. RCP 8.5 elephant population doubled to an average of 3348 elephants. In all the RCPs there are seasonal and yearly variations and absolute number varies from the average. The range of variation is small in RCPs 2.6 and 4.5 compared to RCP 8.5. Evidently, elephant population will increase based on projected rainfall projections surpassing park capacity. It therefore, requires that the Park authority put in place measures that could contain these numbers including opening of blocked wildlife corridors, maintain the cross border movement of Amboseli elephant with Tanzania in that case ensure there is no poaching. Lastly, work with local communities so that they can benefit from tourism through setting up conservancies through which they could minimize the human elephant conflicts based on the projected elephant population.展开更多
Mean hemoglobin(Hb) concentration of about 3 500 subjects derived from 17 studies of Himalayan highlanders(Tibetans, Sherpas, and Ladakhis) was compared with lowlanders(Chinese Han, Indian Tamils) lived in the Himalay...Mean hemoglobin(Hb) concentration of about 3 500 subjects derived from 17 studies of Himalayan highlanders(Tibetans, Sherpas, and Ladakhis) was compared with lowlanders(Chinese Han, Indian Tamils) lived in the Himalayas, and European climbers during Everest expeditions as well as Andean natives. The results found that Hb concentration in Himalayan highlanders was systemically lower than those reported for Andean natives and lowland immigrants. These comparative data demonstrated that a healthy native population may successfully reside at high altitude without a significant elevation in Hb, and the lower Hb levels of Himalayan highlanders than those of migrated lowlanders and Andean natives are an example of favourable adaptation over the generations. In addition, excessive polycythemia has frequently been used as a marker of chronic mountain sickness(CMS). Altitude populations who have a higher Hb concentration also have a higher incidence of CMS. The low Hb in Himalayans suggested as showing adaptation over many generations in Tibetan stock. Recent work in Tibet, suggested that Tibetans there may have adapted to high altitude as a result of evolutionary pressure selecting for genes which give an advantage at altitude. All of the population genomic and statistical analysis indicated that EPAS1 and EGLN1 are mostly likely responsible for high altitude adaptation and closely related to low Hb concentration in Tibetans. These data supported the hypothesis that Himalayan highlanders have evolved a genetically different erythropoietic response to chronic hypoxia by virtue of their much longer exposure to high altitude.展开更多
This paper investigates the impact of China's city size and urban population concentration on city productivity by developing a distinctive index based on global nighttime light data.Using the panel data of 280 pr...This paper investigates the impact of China's city size and urban population concentration on city productivity by developing a distinctive index based on global nighttime light data.Using the panel data of 280 prefecture cities from 2004 to 2013 and employing dynamic system generalized method of moments and panel threshold model regression techniques,our results show that city size has a positive impact on city productivity;therefore,cities in China still have the potential to expand.While moderate urban population concentration can benefit city productivity,excessively concentrated urban population distribution may impede the growth of city productivity.We also find that the level of labor income significantly affects the impacts of urban agglomeration on labor productivity.Therefore,our results imply that city development policies should focus more on how to appropriately allocate economic activities and adjust population distribution in urban areas according to different stages of economic development.展开更多
Decentralized solid-waste incinerators(DSWIs)have certain advantages for waste disposal from villages and towns.However,the incineration condition is always affected by the distribution of temperature and oxygen conce...Decentralized solid-waste incinerators(DSWIs)have certain advantages for waste disposal from villages and towns.However,the incineration condition is always affected by the distribution of temperature and oxygen concentration,which causes difficulties in operation and maintenance.In this study,the temperature and oxygen concentration distribution of DSWI were characterized using different air flow rates and bottom ash volumes.The results showed that the adjustment of air flow has no significant influence on the heating process of the DSWI,while the retention of bottom ash did affect the temperature and oxygen concentration fields in the furnace.When the air flow rate was increased without the retention of bottom ash,99%of the furnace volume temperature was observed between 780℃ and 800℃.However,once the bottom ash was retained,the whole furnace temperature was steadily maintained between 800℃ and 850℃.When the air flow rate was increased without bottom ash,the highest furnace volume percentage of oxygen concentrations higher than 3%maxed out at 11%volume,while it could reach 100%when bottom ash remained.The distribution of the temperature and oxygen concentration in the DSWI characterized by this research provides strong support for the operation and management of such systems.展开更多
文摘In rapid socio-economic developme nt,the process of concentration and dispersal of various elements tends to be more dramatic,tremendously in fluencing the shaping and transform ation of the space in metropolitan area.Survey of spatial concentration and decent ralization has thus become a basic me thod in examining metropolitan spatial evolution.In this research,three elements were selected as the essential indicato rs of the process:demographic density distribu-tion,employment density distribut ion and business office location.Performance of these elements in Nanji ng City was exam-ined historically.As Nanjing City c ould be regarded as a representative of metropolitan areas in China,its s ituation large-ly suggestes the general characteristics in similar areas of China.Hence based on the investigation of Nanji ng City,four general implications were highligh ted.First,metropolitan areas inChina are in a violentprocess and shift of spatialconcentra-tion and decentralization.Second,from now to at least the near future,c oncentration will continue to be the central fea-ture.Third,the landscape of metrop olitan areas basically exhibits a dual structure character.The gap in en vironmental and ecological qualities among different districts will continue for a l ong time.Fourth,Central Business District(CBD)is playing an important role in helpi ng to convert the traditionally single-centered city structure into a polycentric one.
基金Supported by the National Natural Science Foundation of China (No 30471340)
文摘The effects of algal concentration and initial density on the population growth of the estuarine cladocera, Diaphanosoma celebensis Stingelin, were evaluated in an indoor experiment. A 2 × 4 layout that included two algal concentrations （Chlorella pyrenoidosa, 1 × 10^6 and 3 ×10^6 cell/mL） and four inoculation densities （100, 200, 300 and 400 ind./L） were established. Diaphanosoma celebensis were reared in 150 mL flasks containing 50 mL of algal medium at 22℃, under salinity of 10 and a photoperiod of 12 h L： 12 h D. The lag phase required to initiate continuous population growth following inoculation was shorter for D. celebensis fed 1 × 10^6 cell/mL and inoculated at 300 or 400 ind./L than that for D. celebensis fed 3 × 10^6 cell/mL and inoculated at 100 or 200 ind./L. However, D. celebensis fed 3 × 10^6 cell/mL and inoculated at 100 or 200 ind./L exhibited longer periods of positive population growth The maximum population densities were 5 875 ± 324, 6 690 ± 691, 7 735 ± 1,121 and 6 365 ± 691 ind./L for D. celebensis fed 1 × 10^6 cell/mL and inoculated at 100, 200, 300 and 400 ind./L, respectively, and 15 070 ± 379, 12 215 ± 648, 11 960±2,551 and 16 130 ± 880 ind./L for D. celebensis fed 3 ×10^6 cell/mL and inoculated at 100, 200, 300 and 400 ind./L, respectively. The average daily increasing rates of population were 0.076 ± 0.001, 0.065 ± 0.002, 0.055 ±0.002 and 0.048 ± 0.003 for D. celebensis fed 1×10^6 cell/mL and inoculated at 100, 200, 300 and 400 ind./L, respectively, and 0.098± 0.001, 0.078 ± 0.002, 0.072 ± 0.003 and 0.067 ± 0.003 forD. celebensis fed 3 × 10^6 cell/mL and inoculated at 100, 200, 300 and 400 ind./L, respectively. The maximum population density and average daily increasing rate of population increased as the algal concentration increased, whereas an increase in the inoculation density led to a linear decrease in the daily increasing rate of population under both algal concentrations. The results of the present experiment indicate that the algal concentration and inoculation density significantly affect population growth of D. celebensis, Furthermore, the results suggest that the optimal algal concentration and inoculation density for the mass culture ofD. celebensis should be 3 × 10^6 cell/mL and 100 ind./L.
基金the National Natural Science Foundation of China(No.61625501,No.61427816)the Open Fund of the State Key Laboratory of High Field Laser Physics(SIOM)the Open Fund of the State Key Laboratory of Precision Spectroscopy。
文摘A distributed feedback laser with a wavelength of 2.8μm was used to measure the species produced by water vapor glow discharge.Only the absorption spectra of OH radicals and transient H2O molecules were observed using concentration modulation(CM)spectroscopy.The intensities and orientations of the absorption peaks change with the demodulation phase,but the direction of one absorption peak of H2O is always opposite to the other peaks.The different spectral orientations of OH and H2O reflect the increase or the decrease of the number of particles in the energy levels.If more transient species can be detected in the discharge process,the dynamics of excitation,ionization,and decomposition of H2O can be better studied.This study shows that the demodulation phase relationship of CM spectrum can be used to study the population change of molecular energy levels.
文摘Within savanna environments, movements of elephant are influenced by changes in climate especially seasonal rainfall. In this study, we investigated the possible changes in elephant population based on projected rainfall changes using regional climate models (RCM) and Representative Concentration Pathways (RCPs). The relationship between elephant and rainfall was modelled against annual, wet season, dry season rainfall based on various time lags. Future relation between elephant and rainfall was projected based on three RCPs;2.6, 4.5 and 8.5. There was a strong linear relationship between elephant and October-November-December (OND) rains with time lag of 13 years (Y = −4016.43 + 19.11x, r2 = 0.459, P = 0.006). The rainfall trends for RCP 2.6 and 4.5 showed a slight increase in annual rainfall for the period 2006-2100 but driven by OND increases. Rainfall increase for RCP 8.5 was significant and was driven by increase in both March-April-May (MAM) and OND. These rainfall dynamics had influence on the projected elephant population in the Amboseli ecosystem. For RCP 2.6 and 4.5 the elephant population increase was 2455 and 2814 respectively. RCP 8.5 elephant population doubled to an average of 3348 elephants. In all the RCPs there are seasonal and yearly variations and absolute number varies from the average. The range of variation is small in RCPs 2.6 and 4.5 compared to RCP 8.5. Evidently, elephant population will increase based on projected rainfall projections surpassing park capacity. It therefore, requires that the Park authority put in place measures that could contain these numbers including opening of blocked wildlife corridors, maintain the cross border movement of Amboseli elephant with Tanzania in that case ensure there is no poaching. Lastly, work with local communities so that they can benefit from tourism through setting up conservancies through which they could minimize the human elephant conflicts based on the projected elephant population.
基金supported by the"973"National Basic Research Program(2012 CB 518202,and"Pre-973"National Basic Research Program(2012 CB 722506),PRC
文摘Mean hemoglobin(Hb) concentration of about 3 500 subjects derived from 17 studies of Himalayan highlanders(Tibetans, Sherpas, and Ladakhis) was compared with lowlanders(Chinese Han, Indian Tamils) lived in the Himalayas, and European climbers during Everest expeditions as well as Andean natives. The results found that Hb concentration in Himalayan highlanders was systemically lower than those reported for Andean natives and lowland immigrants. These comparative data demonstrated that a healthy native population may successfully reside at high altitude without a significant elevation in Hb, and the lower Hb levels of Himalayan highlanders than those of migrated lowlanders and Andean natives are an example of favourable adaptation over the generations. In addition, excessive polycythemia has frequently been used as a marker of chronic mountain sickness(CMS). Altitude populations who have a higher Hb concentration also have a higher incidence of CMS. The low Hb in Himalayans suggested as showing adaptation over many generations in Tibetan stock. Recent work in Tibet, suggested that Tibetans there may have adapted to high altitude as a result of evolutionary pressure selecting for genes which give an advantage at altitude. All of the population genomic and statistical analysis indicated that EPAS1 and EGLN1 are mostly likely responsible for high altitude adaptation and closely related to low Hb concentration in Tibetans. These data supported the hypothesis that Himalayan highlanders have evolved a genetically different erythropoietic response to chronic hypoxia by virtue of their much longer exposure to high altitude.
文摘This paper investigates the impact of China's city size and urban population concentration on city productivity by developing a distinctive index based on global nighttime light data.Using the panel data of 280 prefecture cities from 2004 to 2013 and employing dynamic system generalized method of moments and panel threshold model regression techniques,our results show that city size has a positive impact on city productivity;therefore,cities in China still have the potential to expand.While moderate urban population concentration can benefit city productivity,excessively concentrated urban population distribution may impede the growth of city productivity.We also find that the level of labor income significantly affects the impacts of urban agglomeration on labor productivity.Therefore,our results imply that city development policies should focus more on how to appropriately allocate economic activities and adjust population distribution in urban areas according to different stages of economic development.
基金The authors would like to acknowledge the support from National Key R&D Program of China,Key Technologies Research and Development Program(2018YFD1100600).
文摘Decentralized solid-waste incinerators(DSWIs)have certain advantages for waste disposal from villages and towns.However,the incineration condition is always affected by the distribution of temperature and oxygen concentration,which causes difficulties in operation and maintenance.In this study,the temperature and oxygen concentration distribution of DSWI were characterized using different air flow rates and bottom ash volumes.The results showed that the adjustment of air flow has no significant influence on the heating process of the DSWI,while the retention of bottom ash did affect the temperature and oxygen concentration fields in the furnace.When the air flow rate was increased without the retention of bottom ash,99%of the furnace volume temperature was observed between 780℃ and 800℃.However,once the bottom ash was retained,the whole furnace temperature was steadily maintained between 800℃ and 850℃.When the air flow rate was increased without bottom ash,the highest furnace volume percentage of oxygen concentrations higher than 3%maxed out at 11%volume,while it could reach 100%when bottom ash remained.The distribution of the temperature and oxygen concentration in the DSWI characterized by this research provides strong support for the operation and management of such systems.
