In mountain ecosystems,plants are sensitive to climate changes,and an entire range of species distribution can be observed in a small area.Therefore,mountains are of great interest for climate–growth relationship ana...In mountain ecosystems,plants are sensitive to climate changes,and an entire range of species distribution can be observed in a small area.Therefore,mountains are of great interest for climate–growth relationship analysis.In this study,the Siberian spruce’s(Picea obovata Ledeb.)radial growth and its climatic response were investigated in the Western Sayan Mountains,near the SayanoShushenskoe Reservoir.Sampling was performed at three sites along an elevational gradient:at the lower border of the species range,in the middle,and at the treeline.Divergence of growth trends between individual trees was observed at each site,with microsite landscape-soil conditions as the most probable driver of this phenomenon.Cluster analysis of individual tree-ring width series based on inter-serial correlation was carried out,resulting in two sub-set chronologies being developed for each site.These chronologies appear to have substantial differences in their climatic responses,mainly during the cold season.This response was not constant due to regional climatic change and the local influence of the nearby Sayano-Shushenskoe Reservoir.The main response of spruce to growing season conditions has a typical elevational pattern expected in mountains:impact of temperature shifts with elevation from positive to negative,and impact of precipitation shifts in the opposite direction.Chronologies of trees,growing under more severe micro-conditions,are very sensitive to temperature during September–April and to precipitation during October–December,and they record both inter-annual and long-term climatic variation.Consequently,it would be interesting to test if they indicate the Siberian High anticyclone,which is the main driver of these climatic factors.展开更多
Elaeagnus angustifolia Linn. has various ecological, medicinal and economical uses. An approach was established using RP-HPLC (reversed-phase high-performance liquid chromatography) to classify and analyse the intra...Elaeagnus angustifolia Linn. has various ecological, medicinal and economical uses. An approach was established using RP-HPLC (reversed-phase high-performance liquid chromatography) to classify and analyse the intra-specific genetic relationships of seventeen populations of E. angustifolia, collected from the Xinjiang areas of China. Chromatograms of alcohol-soluble proteins produced by seventeen populations of E. angustifolia, were compared. Each chromatogram of alcohol-soluble proteins came from a single seed of one wild plant only. The results showed that when using a Waters Delta Pak. C 18, 5μm particle size reversed phase column (150 mm×3.9mm), a linear gradient of 25%-60% solvent B with flow rate of 1 ml/min and run time of 67 min, the chromatography yielded optimum separation of E. angustifolia alcohol-soluble proteins. Representative peaks in each population were chosen according to peak area and occurrence in every seed. The converted data on the elution peaks of each population were different and could be used to represent those populations. GSC (genetic similarity coefficients) of 41% to 62% showed a medium degree of genetic diversity among the populations in these eco-areas. Cluster analysis showed that the seventeen populations orE. angustifolia could be divided into six clusters at the GSC=0.535 level and indicated the general and unique biochemical markers of these clusters. We suggest that E. angustifolia distribution in these eco-areas could be classified into six variable species. RP-HPLC was shown to be a rapid, repeatable and reliable method for E. angustifolia classification and identification and for analysis of genetic diversity.展开更多
Although both Astasia longa and Euglena gracilis belong to different genera, they share many morphological characters except that A. longa has no chloroplast. In the 1940’s, on the basis of the finding that in darkne...Although both Astasia longa and Euglena gracilis belong to different genera, they share many morphological characters except that A. longa has no chloroplast. In the 1940’s, on the basis of the finding that in darkness or upon addition of some chemicals, E. gracilis would fade reversibly or irreversibly, some scholars hypothesised that A. longa evolved from E. gracilis by losing chloroplast. The authors’ use of RAPD and cladistic analyses in a study on the evolutionary relationship between A .longa and E. gracilis showed that the A. longa ’s relationship with E. gracilis was closer than that with other green euglenoids. This proves the hypothesis that A. longa evolved from E. gracilis is reasonable. The results of this study suggest that saprophytic colorless euglenoids were transformed from green euglenoids by losing their choroplasts.展开更多
Climate affects Picea crassifolia growth and climate change will lead to changes in the climate–growth relationship(i.e., the "divergence" phenomenon). However, standardization methods can also change the u...Climate affects Picea crassifolia growth and climate change will lead to changes in the climate–growth relationship(i.e., the "divergence" phenomenon). However, standardization methods can also change the understanding of such a relationship. We tested the stability of this relationship by considering several variables: 1) two periods(1952–1980 and 1981–2009), 2) three elevations(2700, 3000, and 3300 m), and 3) chronologies detrended using cubic splines with two different flexibilities. With increasing elevation, the climatic factor limiting the radial growth of Picea crassifolia shifted from precipitation to temperature. At the elevation of 2700 m, the relationship between radial growth and mean temperature of the previous December changed so that the more flexible spline had a greater precipitation signal. At the elevation of 3000 m, positive correlation of radial growth with mean temperature and precipitation in September of the previous year became more significant. At the elevation of 3300 m, positive correlation between radial growth and precipitation of the currentsummer and the previous spring and autumn was no longer significant, whereas the positive correlation between radial growth and temperature of the current spring and summer strengthened. The detrending with the most flexible spline enhanced the precipitation signal at 2700 m, while that with the least flexible spline enhanced the temperature signal at 3300 m. All results indicated that the divergence phenomenon was affected by the climatic signals in the chronologies and that it was most dependent on the detrending method. This suggests it is necessary to select a suitable spline bootstrap for studies of growth divergence phenomena.展开更多
Since the end of the twenty-first century, relationships in the family have been rapidly changing in Lithuania. The changes correspond to changes in the birth-rate. The former model of birth-rate which was characteriz...Since the end of the twenty-first century, relationships in the family have been rapidly changing in Lithuania. The changes correspond to changes in the birth-rate. The former model of birth-rate which was characterized by the prevalence of legitimate children, child-bearing at a younger age and which ensured a change of generations, it was replaced by a new model characterized by having illegitimate children, the postponement of child-bearing, and low birth-rate, which does not ensure a change of generations. Although love relationships, marriage, and children are still considered to be the recognized values, these changes have affected the conception of child's education in the family and the perception of child as a value. It is therefore relevant to evaluate future spouses' preparation for a modern marriage and to constantly improve it. Such preparation is usually understood as young people's readiness far their first marriage. Readiness for the second marriage and child's education in the second family are no less important though still insufficiently explored empirically and theoretically generalized. This paper explores attitudes to child's education in the second marriage. The research was conducted inquiring people who wanted to create a family or establish long-term relationships. They were members of the online dating site "Harmonious Couple".展开更多
In this paper the author will try to discuss the experiences and narratives of three different categories of families living in Merdivenkoy, Fikirtepe, the oldest settlement and suburban area of the Anatolian side of ...In this paper the author will try to discuss the experiences and narratives of three different categories of families living in Merdivenkoy, Fikirtepe, the oldest settlement and suburban area of the Anatolian side of Istanbul, on the backdrop of urban transformation that will change the area soon. In life story narratives, these three examples give us information about the history, economic linkage, and life styles of neighboring families. The first category basically consists of the families that live in the area for a very long time, over some decades or more. Even one of them mentioned that, their family is living there for hundreds of years. The second category, which represents the biggest group living in the area, consists of families migrated from Sivas, a central Anatolian city, in the 1950s. Third category consist of Kurds migrated from eastern Anatolian villages and cities such as Mardin. Each category has different kinds of nostalgia about the past. Interviewees from the first category talk about family narratives related to the small village Merdivenk6y, Fikirtepe and the area. Mostly, they have a story of a "well off" family, structured and detailed narratives about the family history, including relations with the Ottoman Palace such as doing some sort of production for it. They seem very sensitive about the local cultural characteristics and what's going on in the area; realistic about and reconciled with what will happen as a result of slum clearance. Interviewees from the second category mostly emphasize the hardship of settling in a muddy suburban area, where once "muddy lands" now turned out to become valuable urban properties on which new and modem neighborhoods, shopping malls and office buildings will be built. They are expecting to get maximum gain out of the exchange of their small property, since they are desperately in need, because of the financial crisis situation. Although their houses with small gardens near the small industrial area are small, old, and neglected for years, they expect the most. Relatively newcomers, Kurdish people in the area talk about the good old days on the one hand and the painful stories about migration and settling on the other hand. They do not think about going back to their native lands, since here it is easier for them to find jobs in the informal economy as they live very close to central parts of the city. As a part of a larger research study focused on the experience of urban transformation, we made more than 50 interviews, trying to make a general outlook of the area, working on the dynamics of change before and after the urban transformation that had been started in June 2010. By using oral history research techniques and social science methodology, we conducted in-depth interviews with the people living in the neighborhood, made observations in the neighborhood and took photographs. The author's work is about the reflections of nostalgia in their family histories and experiences of different categories of families living in the area referring life story narratives. As far as the author can see in each group he works on, there are different contradictions related to their position in the city and conception of the area. The urban transformation presented and is perceived as a fortune for all of them, but it will have contradictory outcomes in reality for each as indicated in other examples in the world.展开更多
The human gut is the normal habitat of a lot of microorganisms; in the long process of evolution they have developed a symbiotic relationship with the host. Under normal circumstances they do not damage the health, wh...The human gut is the normal habitat of a lot of microorganisms; in the long process of evolution they have developed a symbiotic relationship with the host. Under normal circumstances they do not damage the health, which totally owes to the barrier functions of the integral intestinal mucosa. Intestinal lnucosal barriers are mainly composed of four parts: mechanical barrier, immune barrier, chemical and biological barrier. Each of these functions has corresponding structural basis, an important barrier to prevent harmful substances and pathogens in the gut into the inner environment of the body, and to maintain a stable internal environment.展开更多
The article discusses the payment for ecosystem or environmental services markets in Brazil with a critical review, based on the ecological economics literature and focused on the concept of co-evolution. It is argued...The article discusses the payment for ecosystem or environmental services markets in Brazil with a critical review, based on the ecological economics literature and focused on the concept of co-evolution. It is argued that the mainstream approach which considers ecosystem services as an externality has many shortcomings and fails to consider institutional and political aspects---all very critical for the design and implementation of a PES (Payment for ecosystem services) project or program. The complexity and the diversity of co-evolutionary relations between ecosystem services and socioeconomic activities are spatially or territorially specific. In this sense, different types of PES market have to adapt and coevolve with different ongoing development processes.展开更多
The basic contradiction of socialist society is still a contradiction between the relations of production and productivity, the superstructure and the economic base. This contradiction is concentrated in the productio...The basic contradiction of socialist society is still a contradiction between the relations of production and productivity, the superstructure and the economic base. This contradiction is concentrated in the production relations and a series of interconnected links and aspects in the superstructure that don't match the development of the productivity, these links and they are concentrated in the economic system. Therefore, reforming the economic system is to reform the production relations and a series of interconnected links and aspects in the superstructure that don't match the development of the productivity under the premise of adhering to the basic system of socialism. This re^brm is a self-improvement and development of the socialist system in order to promote the development of the socialist productive forces and the development of socialist modernization greatly.展开更多
The flipped classroom is an emerging teaching mode which is originated from the United States and is now prevalent in many countries. It is helpful to build a more harmonious relationship between the teachers and the ...The flipped classroom is an emerging teaching mode which is originated from the United States and is now prevalent in many countries. It is helpful to build a more harmonious relationship between the teachers and the students, to enhance the students' self-study ability, to create a favorable learning environment, to realize the individualized teaching in class, and to improve the students' English ability. The study focuses on the college English classroom in China. The author tries to prove that the flipped classroom is a helpful way to improve the teaching and learning effect of college English classroom. A teaching procedure for the flipped college English classroom is designed in the hope of changing the current college English teaching condition.展开更多
Power systems in Germany mainly containing intermittently operating renewable sources require load/frequency control which is performed up to now at the AC transmissioh and distribution levels. Frequency control can b...Power systems in Germany mainly containing intermittently operating renewable sources require load/frequency control which is performed up to now at the AC transmissioh and distribution levels. Frequency control can be achieved by employing short-and long-term storage plants buffering and complementing renewable energy sources. A representative grid consists of a natural-gas-fired plant serving as frequency leader, long-term storage plant, wind-power farm with associated short-term storage plantfor energy buffering, and photovoltaic farm with associated short-term storage plant interconnected by a long transmission line to two load circuits. Transient analysis is performed with Mathemafica solving the differential equation system for frequency variation. Powerflow through the AC transmission line is limited by its impedance. The long transmission line must be segmented to achieve stability and voltage control over an 800 km distance. The renewable plants must be operated together with the storage plants in order tominimize frequency variations by smoothing the power output of renewable plants, achieving step-wise control of the transmission-line power. Although to date only AC Iransmission lines in Germany exist, it is anticipated that within the next 10 years these will beaugmented by DC high-voltage lines.展开更多
Aims We aimed to evaluate how climatic fluctuations influence the plasticity of anatomical vessel traits and the width of annual tree-rings of two relict-endemic Mexican Magnolia species.Notwithstanding,few studies ha...Aims We aimed to evaluate how climatic fluctuations influence the plasticity of anatomical vessel traits and the width of annual tree-rings of two relict-endemic Mexican Magnolia species.Notwithstanding,few studies have assessed the drought effect on vessel traits in tropical montane cloud trees of eastern Mexico.Methods Through digital images of growth rings,we assessed the tree radial growth rate,age of the trees and plasticity in vessel traits regarding climatic fluctuations of the Mexican Magnolia species studied.We compared vessel density,hydraulic diameter and percentage of conductive area in drought years(DY)and non-drought years(NDY)in two Mexican Magnolia species.Important Findings For the first time,the plasticity that occurs in porous wood vessel traits to long-term climatic fluctuations was analysed for two endangered Magnolia species(Magnolia vovidesii and M.schiedeana)from two tropical montane cloud forests in Mexico.We found that temperature and precipitation were strongly associated with differences in tree-ring width when DY and NDY were compared.Our analyses revealed that a high plasticity in vessel anatomy of diffuse-porous wood was related to temperature and/or water availability for both Magnolia species studied.We concluded that anatomical adaptations to DY resulted in a substantial reduction in vessel traits when compared with NDY,and that the plastic adaptations played an essential role in water transport and safety for the survival of the studied species during stressful long periods.展开更多
To accelerate the breeding process of cultivated Ophiocordyceps sinensis and increase its yield,it is important to identify molecular fingerprint of dominant O.sinensis.In the present study,we collected 3 batches of i...To accelerate the breeding process of cultivated Ophiocordyceps sinensis and increase its yield,it is important to identify molecular fingerprint of dominant O.sinensis.In the present study,we collected 3 batches of industrially cultivated O.sinensis product with higher yield than the others and compared their internal transcribed spacer(ITS)sequences with the wild and the reported.The ITS sequence was obtained by bidirectional sequencing and analyzed with molecular systematics as a DNA barcode for rapid and accurate identification of wild and cultivated O.sinensis collected.The ITS sequences of O.sinensis with detailed collection loci on NCBI were downloaded to construct a phylogenetic tree together with the sequences obtained from the present study by using neighbor-joining method based on their evolution relationship.The information on collection loci was analyzed with ArcGIS 10.2 to demonstrate the geographic distribution of these samples and thus to determine the origin of the dominant samples.The results showed that all wild and cultivated samples were identified as O.sinensis and all sequences were divided into seven phylogenetic groups in the tree.Those groups were precisely distributed on the map and the process of their system evolution was clearly presented.The three cultivated samples were clustered into two dominant groups,showing the correlation between the industrially cultivated samples and the dominant wild samples,which can provide references for its optimized breeding in the future.展开更多
Precipitation(PPT)is the primary climatic determinant of plant growth and aboveground net primary productivity(ANPP)for many of the world’s major terrestrial ecosystems.Thus,relationships between PPT and productivity...Precipitation(PPT)is the primary climatic determinant of plant growth and aboveground net primary productivity(ANPP)for many of the world’s major terrestrial ecosystems.Thus,relationships between PPT and productivity can provide insight into how changes in climate may alter ecosystem functions globally.Spatial PPT–ANPP relationships for grasslands are found remarkably similar around the world,but whether and how they change during periods of extended climatic anomalies remain unknown.Here,we quantifed how regional-scale PPTANPP relationships vary between an extended wet and a dry period by taking advantage of a 35-year record of PPT and NDVI(as a surrogate for ANPP)at 1700 sites in the temperate grasslands of northern China.We found a sharp decrease in the strength of the spatial PPT–ANPP relationship during an 11-year period of below average PPT.We attributed the collapse of this relationship to asynchrony in the responses of different grassland types to this decadal period of increased aridity.Our results challenge the robustness of regional PPT–productivity if aridity in grasslands is increased globally by climate change.展开更多
基金funded by the Russian Foundation for Basic Research (project no.17-04-00315)
文摘In mountain ecosystems,plants are sensitive to climate changes,and an entire range of species distribution can be observed in a small area.Therefore,mountains are of great interest for climate–growth relationship analysis.In this study,the Siberian spruce’s(Picea obovata Ledeb.)radial growth and its climatic response were investigated in the Western Sayan Mountains,near the SayanoShushenskoe Reservoir.Sampling was performed at three sites along an elevational gradient:at the lower border of the species range,in the middle,and at the treeline.Divergence of growth trends between individual trees was observed at each site,with microsite landscape-soil conditions as the most probable driver of this phenomenon.Cluster analysis of individual tree-ring width series based on inter-serial correlation was carried out,resulting in two sub-set chronologies being developed for each site.These chronologies appear to have substantial differences in their climatic responses,mainly during the cold season.This response was not constant due to regional climatic change and the local influence of the nearby Sayano-Shushenskoe Reservoir.The main response of spruce to growing season conditions has a typical elevational pattern expected in mountains:impact of temperature shifts with elevation from positive to negative,and impact of precipitation shifts in the opposite direction.Chronologies of trees,growing under more severe micro-conditions,are very sensitive to temperature during September–April and to precipitation during October–December,and they record both inter-annual and long-term climatic variation.Consequently,it would be interesting to test if they indicate the Siberian High anticyclone,which is the main driver of these climatic factors.
基金Project (Nos. 30470330 and 30100126) supported by the NationalNatural Science Foundation of China
文摘Elaeagnus angustifolia Linn. has various ecological, medicinal and economical uses. An approach was established using RP-HPLC (reversed-phase high-performance liquid chromatography) to classify and analyse the intra-specific genetic relationships of seventeen populations of E. angustifolia, collected from the Xinjiang areas of China. Chromatograms of alcohol-soluble proteins produced by seventeen populations of E. angustifolia, were compared. Each chromatogram of alcohol-soluble proteins came from a single seed of one wild plant only. The results showed that when using a Waters Delta Pak. C 18, 5μm particle size reversed phase column (150 mm×3.9mm), a linear gradient of 25%-60% solvent B with flow rate of 1 ml/min and run time of 67 min, the chromatography yielded optimum separation of E. angustifolia alcohol-soluble proteins. Representative peaks in each population were chosen according to peak area and occurrence in every seed. The converted data on the elution peaks of each population were different and could be used to represent those populations. GSC (genetic similarity coefficients) of 41% to 62% showed a medium degree of genetic diversity among the populations in these eco-areas. Cluster analysis showed that the seventeen populations orE. angustifolia could be divided into six clusters at the GSC=0.535 level and indicated the general and unique biochemical markers of these clusters. We suggest that E. angustifolia distribution in these eco-areas could be classified into six variable species. RP-HPLC was shown to be a rapid, repeatable and reliable method for E. angustifolia classification and identification and for analysis of genetic diversity.
文摘Although both Astasia longa and Euglena gracilis belong to different genera, they share many morphological characters except that A. longa has no chloroplast. In the 1940’s, on the basis of the finding that in darkness or upon addition of some chemicals, E. gracilis would fade reversibly or irreversibly, some scholars hypothesised that A. longa evolved from E. gracilis by losing chloroplast. The authors’ use of RAPD and cladistic analyses in a study on the evolutionary relationship between A .longa and E. gracilis showed that the A. longa ’s relationship with E. gracilis was closer than that with other green euglenoids. This proves the hypothesis that A. longa evolved from E. gracilis is reasonable. The results of this study suggest that saprophytic colorless euglenoids were transformed from green euglenoids by losing their choroplasts.
基金supported by the "the Fundamental Research Funds for the Central Nonprofit Research Institution of CAF",Forest degradation and restoration mechanisms of the alpine mountains from the western China (contract: CAFYBB2014ZD001)
文摘Climate affects Picea crassifolia growth and climate change will lead to changes in the climate–growth relationship(i.e., the "divergence" phenomenon). However, standardization methods can also change the understanding of such a relationship. We tested the stability of this relationship by considering several variables: 1) two periods(1952–1980 and 1981–2009), 2) three elevations(2700, 3000, and 3300 m), and 3) chronologies detrended using cubic splines with two different flexibilities. With increasing elevation, the climatic factor limiting the radial growth of Picea crassifolia shifted from precipitation to temperature. At the elevation of 2700 m, the relationship between radial growth and mean temperature of the previous December changed so that the more flexible spline had a greater precipitation signal. At the elevation of 3000 m, positive correlation of radial growth with mean temperature and precipitation in September of the previous year became more significant. At the elevation of 3300 m, positive correlation between radial growth and precipitation of the currentsummer and the previous spring and autumn was no longer significant, whereas the positive correlation between radial growth and temperature of the current spring and summer strengthened. The detrending with the most flexible spline enhanced the precipitation signal at 2700 m, while that with the least flexible spline enhanced the temperature signal at 3300 m. All results indicated that the divergence phenomenon was affected by the climatic signals in the chronologies and that it was most dependent on the detrending method. This suggests it is necessary to select a suitable spline bootstrap for studies of growth divergence phenomena.
文摘Since the end of the twenty-first century, relationships in the family have been rapidly changing in Lithuania. The changes correspond to changes in the birth-rate. The former model of birth-rate which was characterized by the prevalence of legitimate children, child-bearing at a younger age and which ensured a change of generations, it was replaced by a new model characterized by having illegitimate children, the postponement of child-bearing, and low birth-rate, which does not ensure a change of generations. Although love relationships, marriage, and children are still considered to be the recognized values, these changes have affected the conception of child's education in the family and the perception of child as a value. It is therefore relevant to evaluate future spouses' preparation for a modern marriage and to constantly improve it. Such preparation is usually understood as young people's readiness far their first marriage. Readiness for the second marriage and child's education in the second family are no less important though still insufficiently explored empirically and theoretically generalized. This paper explores attitudes to child's education in the second marriage. The research was conducted inquiring people who wanted to create a family or establish long-term relationships. They were members of the online dating site "Harmonious Couple".
文摘In this paper the author will try to discuss the experiences and narratives of three different categories of families living in Merdivenkoy, Fikirtepe, the oldest settlement and suburban area of the Anatolian side of Istanbul, on the backdrop of urban transformation that will change the area soon. In life story narratives, these three examples give us information about the history, economic linkage, and life styles of neighboring families. The first category basically consists of the families that live in the area for a very long time, over some decades or more. Even one of them mentioned that, their family is living there for hundreds of years. The second category, which represents the biggest group living in the area, consists of families migrated from Sivas, a central Anatolian city, in the 1950s. Third category consist of Kurds migrated from eastern Anatolian villages and cities such as Mardin. Each category has different kinds of nostalgia about the past. Interviewees from the first category talk about family narratives related to the small village Merdivenk6y, Fikirtepe and the area. Mostly, they have a story of a "well off" family, structured and detailed narratives about the family history, including relations with the Ottoman Palace such as doing some sort of production for it. They seem very sensitive about the local cultural characteristics and what's going on in the area; realistic about and reconciled with what will happen as a result of slum clearance. Interviewees from the second category mostly emphasize the hardship of settling in a muddy suburban area, where once "muddy lands" now turned out to become valuable urban properties on which new and modem neighborhoods, shopping malls and office buildings will be built. They are expecting to get maximum gain out of the exchange of their small property, since they are desperately in need, because of the financial crisis situation. Although their houses with small gardens near the small industrial area are small, old, and neglected for years, they expect the most. Relatively newcomers, Kurdish people in the area talk about the good old days on the one hand and the painful stories about migration and settling on the other hand. They do not think about going back to their native lands, since here it is easier for them to find jobs in the informal economy as they live very close to central parts of the city. As a part of a larger research study focused on the experience of urban transformation, we made more than 50 interviews, trying to make a general outlook of the area, working on the dynamics of change before and after the urban transformation that had been started in June 2010. By using oral history research techniques and social science methodology, we conducted in-depth interviews with the people living in the neighborhood, made observations in the neighborhood and took photographs. The author's work is about the reflections of nostalgia in their family histories and experiences of different categories of families living in the area referring life story narratives. As far as the author can see in each group he works on, there are different contradictions related to their position in the city and conception of the area. The urban transformation presented and is perceived as a fortune for all of them, but it will have contradictory outcomes in reality for each as indicated in other examples in the world.
文摘The human gut is the normal habitat of a lot of microorganisms; in the long process of evolution they have developed a symbiotic relationship with the host. Under normal circumstances they do not damage the health, which totally owes to the barrier functions of the integral intestinal mucosa. Intestinal lnucosal barriers are mainly composed of four parts: mechanical barrier, immune barrier, chemical and biological barrier. Each of these functions has corresponding structural basis, an important barrier to prevent harmful substances and pathogens in the gut into the inner environment of the body, and to maintain a stable internal environment.
文摘The article discusses the payment for ecosystem or environmental services markets in Brazil with a critical review, based on the ecological economics literature and focused on the concept of co-evolution. It is argued that the mainstream approach which considers ecosystem services as an externality has many shortcomings and fails to consider institutional and political aspects---all very critical for the design and implementation of a PES (Payment for ecosystem services) project or program. The complexity and the diversity of co-evolutionary relations between ecosystem services and socioeconomic activities are spatially or territorially specific. In this sense, different types of PES market have to adapt and coevolve with different ongoing development processes.
文摘The basic contradiction of socialist society is still a contradiction between the relations of production and productivity, the superstructure and the economic base. This contradiction is concentrated in the production relations and a series of interconnected links and aspects in the superstructure that don't match the development of the productivity, these links and they are concentrated in the economic system. Therefore, reforming the economic system is to reform the production relations and a series of interconnected links and aspects in the superstructure that don't match the development of the productivity under the premise of adhering to the basic system of socialism. This re^brm is a self-improvement and development of the socialist system in order to promote the development of the socialist productive forces and the development of socialist modernization greatly.
文摘The flipped classroom is an emerging teaching mode which is originated from the United States and is now prevalent in many countries. It is helpful to build a more harmonious relationship between the teachers and the students, to enhance the students' self-study ability, to create a favorable learning environment, to realize the individualized teaching in class, and to improve the students' English ability. The study focuses on the college English classroom in China. The author tries to prove that the flipped classroom is a helpful way to improve the teaching and learning effect of college English classroom. A teaching procedure for the flipped college English classroom is designed in the hope of changing the current college English teaching condition.
文摘Power systems in Germany mainly containing intermittently operating renewable sources require load/frequency control which is performed up to now at the AC transmissioh and distribution levels. Frequency control can be achieved by employing short-and long-term storage plants buffering and complementing renewable energy sources. A representative grid consists of a natural-gas-fired plant serving as frequency leader, long-term storage plant, wind-power farm with associated short-term storage plantfor energy buffering, and photovoltaic farm with associated short-term storage plant interconnected by a long transmission line to two load circuits. Transient analysis is performed with Mathemafica solving the differential equation system for frequency variation. Powerflow through the AC transmission line is limited by its impedance. The long transmission line must be segmented to achieve stability and voltage control over an 800 km distance. The renewable plants must be operated together with the storage plants in order tominimize frequency variations by smoothing the power output of renewable plants, achieving step-wise control of the transmission-line power. Although to date only AC Iransmission lines in Germany exist, it is anticipated that within the next 10 years these will beaugmented by DC high-voltage lines.
文摘Aims We aimed to evaluate how climatic fluctuations influence the plasticity of anatomical vessel traits and the width of annual tree-rings of two relict-endemic Mexican Magnolia species.Notwithstanding,few studies have assessed the drought effect on vessel traits in tropical montane cloud trees of eastern Mexico.Methods Through digital images of growth rings,we assessed the tree radial growth rate,age of the trees and plasticity in vessel traits regarding climatic fluctuations of the Mexican Magnolia species studied.We compared vessel density,hydraulic diameter and percentage of conductive area in drought years(DY)and non-drought years(NDY)in two Mexican Magnolia species.Important Findings For the first time,the plasticity that occurs in porous wood vessel traits to long-term climatic fluctuations was analysed for two endangered Magnolia species(Magnolia vovidesii and M.schiedeana)from two tropical montane cloud forests in Mexico.We found that temperature and precipitation were strongly associated with differences in tree-ring width when DY and NDY were compared.Our analyses revealed that a high plasticity in vessel anatomy of diffuse-porous wood was related to temperature and/or water availability for both Magnolia species studied.We concluded that anatomical adaptations to DY resulted in a substantial reduction in vessel traits when compared with NDY,and that the plastic adaptations played an essential role in water transport and safety for the survival of the studied species during stressful long periods.
基金supported by the Macao Science and Technology Development Fund(No.062/2017/A2)
文摘To accelerate the breeding process of cultivated Ophiocordyceps sinensis and increase its yield,it is important to identify molecular fingerprint of dominant O.sinensis.In the present study,we collected 3 batches of industrially cultivated O.sinensis product with higher yield than the others and compared their internal transcribed spacer(ITS)sequences with the wild and the reported.The ITS sequence was obtained by bidirectional sequencing and analyzed with molecular systematics as a DNA barcode for rapid and accurate identification of wild and cultivated O.sinensis collected.The ITS sequences of O.sinensis with detailed collection loci on NCBI were downloaded to construct a phylogenetic tree together with the sequences obtained from the present study by using neighbor-joining method based on their evolution relationship.The information on collection loci was analyzed with ArcGIS 10.2 to demonstrate the geographic distribution of these samples and thus to determine the origin of the dominant samples.The results showed that all wild and cultivated samples were identified as O.sinensis and all sequences were divided into seven phylogenetic groups in the tree.Those groups were precisely distributed on the map and the process of their system evolution was clearly presented.The three cultivated samples were clustered into two dominant groups,showing the correlation between the industrially cultivated samples and the dominant wild samples,which can provide references for its optimized breeding in the future.
基金supported by the National Natural Science Foundation of China(31922053)the start-up fund of Hainan University(Grant No.KYQD(ZR)21096)the National Key R&D Program of China(2017YFA0604801).
文摘Precipitation(PPT)is the primary climatic determinant of plant growth and aboveground net primary productivity(ANPP)for many of the world’s major terrestrial ecosystems.Thus,relationships between PPT and productivity can provide insight into how changes in climate may alter ecosystem functions globally.Spatial PPT–ANPP relationships for grasslands are found remarkably similar around the world,but whether and how they change during periods of extended climatic anomalies remain unknown.Here,we quantifed how regional-scale PPTANPP relationships vary between an extended wet and a dry period by taking advantage of a 35-year record of PPT and NDVI(as a surrogate for ANPP)at 1700 sites in the temperate grasslands of northern China.We found a sharp decrease in the strength of the spatial PPT–ANPP relationship during an 11-year period of below average PPT.We attributed the collapse of this relationship to asynchrony in the responses of different grassland types to this decadal period of increased aridity.Our results challenge the robustness of regional PPT–productivity if aridity in grasslands is increased globally by climate change.