Agroforests are man-made ecosystems in which crops are associated with a main perennial species like Robusta Coffee Agroforests (RCAs), which is counted among the main modes of perennial crops production in Cameroon. ...Agroforests are man-made ecosystems in which crops are associated with a main perennial species like Robusta Coffee Agroforests (RCAs), which is counted among the main modes of perennial crops production in Cameroon. Despite the rich ecosystem services provided, the diversity of Associated Species (AS) found in these RCAs and the structure of the landscapes they form remain little known in Cameroon. The current study aimed to inventory AS and characterize the structure of RCAs in four sites (Ayos, Malantouen, Melong and Nkongsamba) belonging to three robusta coffee production basins in Cameroon. A systematic inventory with dendrometric measurements of the wood AS and coffee trees was carried out on 120 one-hectare plot unit, i.e. 30 plots per site. The results showed that 102 AS belonging to 83 genera and 41 families were identified in these RCAs. The RCAs of Ayos in the dense rainforest zone with bimodal rainfall pattern were the most diverse with 71 species, followed by those of Melong and Nkongsamba with respectively 39 and 33 species respectively in the dense rainforest zone with monomodal rainfall pattern, and Malantouen with 33 species in the high savannahs of the west. Structurally, average coffee tree and AS densities founded ranged from 1208 - 1456 plants/ha and 71 - 214 stems/ha and those of basal area from 7.29 - 17.40 m<sup>2</sup>/ha for coffee trees and 7.97 - 16.14 m<sup>2</sup>/ha for AS in function of site. Basis on the vertical stratification, the proportion of the 3 - 6 m stratum, which is mainly represented by introduced AS, varied from 38% - 62% depending on the site. The results of this study showed that RCAs contribute to the conservation of plant biodiversity, given the specific richness identified in these ecosystems.展开更多
The control of organ size growth is one of the most fundamental aspects of life.In the past two decades,a highly conserved Hippo signaling pathway has been identified as a key molecular mechanism for governing organ s...The control of organ size growth is one of the most fundamental aspects of life.In the past two decades,a highly conserved Hippo signaling pathway has been identified as a key molecular mechanism for governing organ size regulation.In the middle of this pathway is a kinase cascade that negatively regulates the downstream component Yes-associated protein(YAP)/transcriptional coactivator with PDZ-binding motif(TAZ)/Yorkie through phosphorylation.Phosphorylation of YAP/TAZ/Yorkie promotes its cytoplasmic localization,leads to cell apoptosis and restricts organ size overgrowth.When the Hippo pathway is inactivated,YAP/TAZ/Yorkie translocates into the nucleus to bind to the transcription enhancer factor(TEAD/TEF)family of transcriptional factors to promote cell growth and proliferation.In this review,we will focus on the structural and functional studies on the downstream transcription factor TEAD and its coactivator YAP.展开更多
The precipitation behavior in Inconel 718 and modified alloys has been studied by means of TEM.The structure of associated precipitation and compact morphology of γ″+γ′ were ob- tained by modifying the contents of...The precipitation behavior in Inconel 718 and modified alloys has been studied by means of TEM.The structure of associated precipitation and compact morphology of γ″+γ′ were ob- tained by modifying the contents of Al,Ti and Nb.Experimental results show that the com- pact morphology of γ″+γ′ has the best structure stability at higher temperatures.Instead of the transformation γ″→δ in alloy 718 the dissolution of strengthening phases in modified alloy leads material degradation.展开更多
Using a 3D lightning radiation source locating system （LLS）, three pairs of associated lightning discharges （two or more adjacent lightning discharges following an arbitrary rule that their space-gap was less than ...Using a 3D lightning radiation source locating system （LLS）, three pairs of associated lightning discharges （two or more adjacent lightning discharges following an arbitrary rule that their space-gap was less than 10 km and their time-gap was less than 800 ms） were observed, and the interaction between associated lightning discharges was analyzed. All these three pairs of associated lightning discharges were found to involve three or more charge regions （the ground was considered as a special charge region）. Moreover, at least one charge region involved two lightning discharges per pair of associated lightning discharges. Identified fl＇om electric field changes, the subsequent lightning discharges were suppressed by the prior lightning discharges. However, it is possible that the prior lightning discharge provided a remaining discharge channel to facilitate the subsequent lightning discharge. The third case provided evidence of this possibility. Together, the results suggested that, if the charges in the main negative charge region can be consumed using artificial lightning above the main negative charge regions, lightning accidents on the ground could be greatly reduced, on the condition that the height of the main negative charge region and the charge intensity of the lower positive charge region are suitable.展开更多
Under the conditions on covariances of the original random variables, a Glivenko-Cantelli theorem for associated sequences and weak convergence for empirical processes of stationary associated sequences are obtained, ...Under the conditions on covariances of the original random variables, a Glivenko-Cantelli theorem for associated sequences and weak convergence for empirical processes of stationary associated sequences are obtained, assuming the random variables to be discrete.展开更多
Biowaste compost can influence soil organic matter accumulation directly or indirectly. A 5-year experiment was conducted to assess the influence of biowaste compost on the process of soil aggregation and soil organic...Biowaste compost can influence soil organic matter accumulation directly or indirectly. A 5-year experiment was conducted to assess the influence of biowaste compost on the process of soil aggregation and soil organic carbon （SOC） accumulation in a Mediterranean vegetable cropping system. The study involved four treatments： biowaste compost （COM）, mineral NPK fertilizers （MIN）, biowaste compost with half-dose N fertilizer （COMN）, and unfertilized control （CK）. The SOC stocks were increased in COM, COMN, and MIN by 20.2, 14.9, and 2.4 Mg ha-1 over CK, respectively. The SOC concentration was significantly related to mean weight diameter of aggregates （MWD） （P 〈 0.05, R^2 = 0.798 4） when CK was excluded from regression analysis. Compared to CK, COM and COMN increased the SOC amount in macroaggregates （〉 250 μm） by 2.7 and 0.6 g kg-1 soil, respectively, while MIN showed a loss of 0.4 g kg-1 soil. The SOC amount in free microaggregates （53-250 ttm） increased by 0.9, 1.6, and 1.0 g kg-1 soil for COM, COMN, and MIN, respectively, while those in the free silt plus clay aggregates （~ 53 ~m） did not vary significantly. However, when separating SOC in particle-size fractions, we found that more stable organic carbon associated with mineral fraction 〈 53 μm （MOM-C） increased significantly by 3.4, 2.2, and 0.7 g kg-1 soil for COM, COMN, and MIN, respectively, over CK, while SOC amount in fine particulate organic matter （POM） fraction （53-250 μm） increased only by 0.3 g kg-1 soil for both COM and COMN, with no difference in coarse POM 〉 250 μm. Therefore, we consider that biowaste compost could be effective in improving soil structure and long-term C sequestration as more stable MOM-C.展开更多
Nascent polypeptide associated complex(NAC)and its two isolated subunits,αNAC and βNAC,play important roles in nascent peptide targeting.We determined a 1.9Åresolution crystal structure of the interaction core ...Nascent polypeptide associated complex(NAC)and its two isolated subunits,αNAC and βNAC,play important roles in nascent peptide targeting.We determined a 1.9Åresolution crystal structure of the interaction core of NAC heterodimer and a 2.4Åresolution crystal structure ofαNAC NAC domain homodimer.These structures provide detailed information of NAC heterodimerization and αNAC homodimerization.We found that the NAC domains of αNAC and βNAC share very similar folding despite of their relative low identity of amino acid sequences.Furthermore,different electric charge distributions of the two subunits at the NAC interface provide an explanation to the observation that the heterodimer of NAC complex is more stable than the single subunit homodimer.In addition,we successfully built a βNAC NAC domain homodimer model based on homologous modeling,suggesting that NAC domain dimerization is a general property of the NAC family.These 3D structures allow further studies on structurefunction relationship of NAC.展开更多
文摘Agroforests are man-made ecosystems in which crops are associated with a main perennial species like Robusta Coffee Agroforests (RCAs), which is counted among the main modes of perennial crops production in Cameroon. Despite the rich ecosystem services provided, the diversity of Associated Species (AS) found in these RCAs and the structure of the landscapes they form remain little known in Cameroon. The current study aimed to inventory AS and characterize the structure of RCAs in four sites (Ayos, Malantouen, Melong and Nkongsamba) belonging to three robusta coffee production basins in Cameroon. A systematic inventory with dendrometric measurements of the wood AS and coffee trees was carried out on 120 one-hectare plot unit, i.e. 30 plots per site. The results showed that 102 AS belonging to 83 genera and 41 families were identified in these RCAs. The RCAs of Ayos in the dense rainforest zone with bimodal rainfall pattern were the most diverse with 71 species, followed by those of Melong and Nkongsamba with respectively 39 and 33 species respectively in the dense rainforest zone with monomodal rainfall pattern, and Malantouen with 33 species in the high savannahs of the west. Structurally, average coffee tree and AS densities founded ranged from 1208 - 1456 plants/ha and 71 - 214 stems/ha and those of basal area from 7.29 - 17.40 m<sup>2</sup>/ha for coffee trees and 7.97 - 16.14 m<sup>2</sup>/ha for AS in function of site. Basis on the vertical stratification, the proportion of the 3 - 6 m stratum, which is mainly represented by introduced AS, varied from 38% - 62% depending on the site. The results of this study showed that RCAs contribute to the conservation of plant biodiversity, given the specific richness identified in these ecosystems.
文摘The control of organ size growth is one of the most fundamental aspects of life.In the past two decades,a highly conserved Hippo signaling pathway has been identified as a key molecular mechanism for governing organ size regulation.In the middle of this pathway is a kinase cascade that negatively regulates the downstream component Yes-associated protein(YAP)/transcriptional coactivator with PDZ-binding motif(TAZ)/Yorkie through phosphorylation.Phosphorylation of YAP/TAZ/Yorkie promotes its cytoplasmic localization,leads to cell apoptosis and restricts organ size overgrowth.When the Hippo pathway is inactivated,YAP/TAZ/Yorkie translocates into the nucleus to bind to the transcription enhancer factor(TEAD/TEF)family of transcriptional factors to promote cell growth and proliferation.In this review,we will focus on the structural and functional studies on the downstream transcription factor TEAD and its coactivator YAP.
文摘The precipitation behavior in Inconel 718 and modified alloys has been studied by means of TEM.The structure of associated precipitation and compact morphology of γ″+γ′ were ob- tained by modifying the contents of Al,Ti and Nb.Experimental results show that the com- pact morphology of γ″+γ′ has the best structure stability at higher temperatures.Instead of the transformation γ″→δ in alloy 718 the dissolution of strengthening phases in modified alloy leads material degradation.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41075002, 41005022, and 40775004)
文摘Using a 3D lightning radiation source locating system （LLS）, three pairs of associated lightning discharges （two or more adjacent lightning discharges following an arbitrary rule that their space-gap was less than 10 km and their time-gap was less than 800 ms） were observed, and the interaction between associated lightning discharges was analyzed. All these three pairs of associated lightning discharges were found to involve three or more charge regions （the ground was considered as a special charge region）. Moreover, at least one charge region involved two lightning discharges per pair of associated lightning discharges. Identified fl＇om electric field changes, the subsequent lightning discharges were suppressed by the prior lightning discharges. However, it is possible that the prior lightning discharge provided a remaining discharge channel to facilitate the subsequent lightning discharge. The third case provided evidence of this possibility. Together, the results suggested that, if the charges in the main negative charge region can be consumed using artificial lightning above the main negative charge regions, lightning accidents on the ground could be greatly reduced, on the condition that the height of the main negative charge region and the charge intensity of the lower positive charge region are suitable.
文摘Under the conditions on covariances of the original random variables, a Glivenko-Cantelli theorem for associated sequences and weak convergence for empirical processes of stationary associated sequences are obtained, assuming the random variables to be discrete.
文摘Biowaste compost can influence soil organic matter accumulation directly or indirectly. A 5-year experiment was conducted to assess the influence of biowaste compost on the process of soil aggregation and soil organic carbon （SOC） accumulation in a Mediterranean vegetable cropping system. The study involved four treatments： biowaste compost （COM）, mineral NPK fertilizers （MIN）, biowaste compost with half-dose N fertilizer （COMN）, and unfertilized control （CK）. The SOC stocks were increased in COM, COMN, and MIN by 20.2, 14.9, and 2.4 Mg ha-1 over CK, respectively. The SOC concentration was significantly related to mean weight diameter of aggregates （MWD） （P 〈 0.05, R^2 = 0.798 4） when CK was excluded from regression analysis. Compared to CK, COM and COMN increased the SOC amount in macroaggregates （〉 250 μm） by 2.7 and 0.6 g kg-1 soil, respectively, while MIN showed a loss of 0.4 g kg-1 soil. The SOC amount in free microaggregates （53-250 ttm） increased by 0.9, 1.6, and 1.0 g kg-1 soil for COM, COMN, and MIN, respectively, while those in the free silt plus clay aggregates （~ 53 ~m） did not vary significantly. However, when separating SOC in particle-size fractions, we found that more stable organic carbon associated with mineral fraction 〈 53 μm （MOM-C） increased significantly by 3.4, 2.2, and 0.7 g kg-1 soil for COM, COMN, and MIN, respectively, over CK, while SOC amount in fine particulate organic matter （POM） fraction （53-250 μm） increased only by 0.3 g kg-1 soil for both COM and COMN, with no difference in coarse POM 〉 250 μm. Therefore, we consider that biowaste compost could be effective in improving soil structure and long-term C sequestration as more stable MOM-C.
基金This work was supported by the National Natural Science Foundation of China(grant No.30730022)the National Basic Research Program(973 Program)(grant Nos.2006CB806503 and 2007CB914304)+1 种基金the National Programs for High Technology Research and Development Program(863 Program)(grant Nos.2006AA02A322 and 2006AA020502)the CAS(China)grant KSCX2-YW-R-05 to Z.R.
文摘Nascent polypeptide associated complex(NAC)and its two isolated subunits,αNAC and βNAC,play important roles in nascent peptide targeting.We determined a 1.9Åresolution crystal structure of the interaction core of NAC heterodimer and a 2.4Åresolution crystal structure ofαNAC NAC domain homodimer.These structures provide detailed information of NAC heterodimerization and αNAC homodimerization.We found that the NAC domains of αNAC and βNAC share very similar folding despite of their relative low identity of amino acid sequences.Furthermore,different electric charge distributions of the two subunits at the NAC interface provide an explanation to the observation that the heterodimer of NAC complex is more stable than the single subunit homodimer.In addition,we successfully built a βNAC NAC domain homodimer model based on homologous modeling,suggesting that NAC domain dimerization is a general property of the NAC family.These 3D structures allow further studies on structurefunction relationship of NAC.
