Spring snowmelt peak flow （SSPF） can cause serious damage. Precipitation as rainfall directly contributes to the SSPF and influences the characteristics of the SSPF, while temperature indirectly impacts the SSPF by ...Spring snowmelt peak flow （SSPF） can cause serious damage. Precipitation as rainfall directly contributes to the SSPF and influences the characteristics of the SSPF, while temperature indirectly impacts the SSPF by shaping snowmelt rate and determining the soil frozen state which partitions snowmelt water into surface runoff and soil infiltration water in spring. It is necessary to identify the important and significant paths of climatic factors influencing the SSPF and provide estimates of the magnitude and significance of hypothesized causal connections between climatic factors and the SSPF. This study used path analysis with a selection of five factors - the antecedent precipitation index （API）, spring precipitation （SP）, winter precipitation as snowfall （WS）, 〈0℃ temperature accumulation in winter （[ATNI）, and average 〉0℃temperature accumulation in spring （AT） - to analyze their influences on the SSPF in the Kaidu River in Xinjiang, China. The results show that {ATN}, AT and WS have a significant correlation with the SSPF, while API and SP do not show a significant correlation. AT and WS directly influence the SSPF, while as the influence of[ATN] on SSPF is indirect through WS and AT. The indirect influence of [ATN[ on SSPF through WS accounts for 69% of the total influence of [ATN] on SSPF. Compared to the multiple linear regression method, path analysis provides additional valuable information, including influencing paths from independent variables to the dependent variable as well as direct and indirect impacts of external variables on the internal variable. This information can help improve the description of snow melt and spring runoff in hydrologic models as well as the planning and management of water resources.展开更多
Water scarcity is a challenge in many arid and semi-arid regions; this may lead to a series of environmental problems and could be stressed even further by the effects from climate change. This study focused on the wa...Water scarcity is a challenge in many arid and semi-arid regions; this may lead to a series of environmental problems and could be stressed even further by the effects from climate change. This study focused on the water resource management in Shanshan County, an inland arid region located in northwestern China with a long history of groundwater overexploitation. A model of the supply and demand system in the study area from 2006 to2030, including effects from global climate change,was developed using a system dynamics(SD)modeling tool. This SD model was used to 1) explore the best water-resource management options by testing system responses under various scenarios and2) identify the principal factors affecting the responses, aiming for a balance of the groundwater system and sustainable socio-economic development.Three causes were identified as primarily responsible for water issues in Shanshan: low water-use efficiency low water reuse, and increase in industrial waterdemand. To address these causes, a combined scenario was designed and simulated, which was able to keep the water deficiency under 5% by 2030. The model provided some insights into the dynamic interrelations that generate system behavior and the key factors in the system that govern water demand and supply. The model as well as the study results may be useful in water resources management in Shanshan and may be applied, with appropriate modifications, to other regions facing similar water management challenges.展开更多
Gamma secretase(GS)is an intramembranous enzyme that acts on the amyloid precursor protein and Notch inside lipid membranes.The enzyme is responsible for amyloid-β propagation,one of the well-known causes of Alzheime...Gamma secretase(GS)is an intramembranous enzyme that acts on the amyloid precursor protein and Notch inside lipid membranes.The enzyme is responsible for amyloid-β propagation,one of the well-known causes of Alzheimer’s disease.However,the effects of lipids on GS activity and structural dynamics are unknown.Therefore,in this study,we performed coarse-grained molecular dynamics simulations to probe the effects of five individual lipids on GS.These lipids included 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine(POPE),1-palmitoyl2-oleoyl-sn-glycero-3-phosphocholine(POPC),1,2-dipalmitoyl-sn-phosphatidylcholine(DOPC),2-dimyristoyl-snglycero-3-phosphocholine(DMPC),and 1,2-dilauroyl-sn-glycero-3-phosphocholine(DLPC).These lipids are structurally characterized by different heads(i.e.,NH_(3)[PE]for POPE vs.NC_(3)[PC]for POPC),number of double bonds(one for POPC vs.two for DOPC),and alkyl tail chain lengths(16:1/18:1 for DOPC vs.14:0/14:0 for DMPC vs.12:0/12:0 for DLPC).This indicates distinct microenvironments and adjustable structural elements for catalytic function when GS is embedded.Our results revealed that the presence of more unsaturated bonds in DOPC than in POPC resulted in greater GS stability.Moreover,lipids with short alkyl tail chains or with PC heads instead of PE heads had improved mobility of the sixth transmembrane helix of GS,which is responsible for the considerable active site flexibility and presenilin 1 subunit plasticity.The length of the DMPC alkyl tail chain was between that of DOPC and DLPC because the up-down and cross-correlation motions of GS in DMPC was the lowest among the three lipids,and GS mobility in DMPC was the lowest among all five lipids.This may be because the alkyl tail chain length(i.e.,3.8 nm thickness of the DMPC bilayer)was suitable for GS embedding,thereby restraining more GS motions than that of the long(DOPC)or short lipids(DLPC).Collectively,these results indicated that GS activity can be modulated through changes in conformational fluctuations,structural perturbations,molecular motion,and cross-correlation motion when embedded in different lipids.Exploration of such fundamental information can reveal the possible mechanisms by which GS is affected by individual lipid species.展开更多
基金financially supported by the Project of State Key Basic R & D Program of China (973 Program, Grant No. 2010CB951002)the key deployment project of Chinese Academy of Sciences (Grant No. KZZD-EW-12-2)Chinese Academy of Sciences Visiting Professorship for Senior International Scientists (Grant No. 2011T2Z40)
文摘Spring snowmelt peak flow （SSPF） can cause serious damage. Precipitation as rainfall directly contributes to the SSPF and influences the characteristics of the SSPF, while temperature indirectly impacts the SSPF by shaping snowmelt rate and determining the soil frozen state which partitions snowmelt water into surface runoff and soil infiltration water in spring. It is necessary to identify the important and significant paths of climatic factors influencing the SSPF and provide estimates of the magnitude and significance of hypothesized causal connections between climatic factors and the SSPF. This study used path analysis with a selection of five factors - the antecedent precipitation index （API）, spring precipitation （SP）, winter precipitation as snowfall （WS）, 〈0℃ temperature accumulation in winter （[ATNI）, and average 〉0℃temperature accumulation in spring （AT） - to analyze their influences on the SSPF in the Kaidu River in Xinjiang, China. The results show that {ATN}, AT and WS have a significant correlation with the SSPF, while API and SP do not show a significant correlation. AT and WS directly influence the SSPF, while as the influence of[ATN] on SSPF is indirect through WS and AT. The indirect influence of [ATN[ on SSPF through WS accounts for 69% of the total influence of [ATN] on SSPF. Compared to the multiple linear regression method, path analysis provides additional valuable information, including influencing paths from independent variables to the dependent variable as well as direct and indirect impacts of external variables on the internal variable. This information can help improve the description of snow melt and spring runoff in hydrologic models as well as the planning and management of water resources.
文摘Water scarcity is a challenge in many arid and semi-arid regions; this may lead to a series of environmental problems and could be stressed even further by the effects from climate change. This study focused on the water resource management in Shanshan County, an inland arid region located in northwestern China with a long history of groundwater overexploitation. A model of the supply and demand system in the study area from 2006 to2030, including effects from global climate change,was developed using a system dynamics(SD)modeling tool. This SD model was used to 1) explore the best water-resource management options by testing system responses under various scenarios and2) identify the principal factors affecting the responses, aiming for a balance of the groundwater system and sustainable socio-economic development.Three causes were identified as primarily responsible for water issues in Shanshan: low water-use efficiency low water reuse, and increase in industrial waterdemand. To address these causes, a combined scenario was designed and simulated, which was able to keep the water deficiency under 5% by 2030. The model provided some insights into the dynamic interrelations that generate system behavior and the key factors in the system that govern water demand and supply. The model as well as the study results may be useful in water resources management in Shanshan and may be applied, with appropriate modifications, to other regions facing similar water management challenges.
基金supported by Shandong Provincial Natural Science Foundation of China(ZR2022MB073).
文摘Gamma secretase(GS)is an intramembranous enzyme that acts on the amyloid precursor protein and Notch inside lipid membranes.The enzyme is responsible for amyloid-β propagation,one of the well-known causes of Alzheimer’s disease.However,the effects of lipids on GS activity and structural dynamics are unknown.Therefore,in this study,we performed coarse-grained molecular dynamics simulations to probe the effects of five individual lipids on GS.These lipids included 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine(POPE),1-palmitoyl2-oleoyl-sn-glycero-3-phosphocholine(POPC),1,2-dipalmitoyl-sn-phosphatidylcholine(DOPC),2-dimyristoyl-snglycero-3-phosphocholine(DMPC),and 1,2-dilauroyl-sn-glycero-3-phosphocholine(DLPC).These lipids are structurally characterized by different heads(i.e.,NH_(3)[PE]for POPE vs.NC_(3)[PC]for POPC),number of double bonds(one for POPC vs.two for DOPC),and alkyl tail chain lengths(16:1/18:1 for DOPC vs.14:0/14:0 for DMPC vs.12:0/12:0 for DLPC).This indicates distinct microenvironments and adjustable structural elements for catalytic function when GS is embedded.Our results revealed that the presence of more unsaturated bonds in DOPC than in POPC resulted in greater GS stability.Moreover,lipids with short alkyl tail chains or with PC heads instead of PE heads had improved mobility of the sixth transmembrane helix of GS,which is responsible for the considerable active site flexibility and presenilin 1 subunit plasticity.The length of the DMPC alkyl tail chain was between that of DOPC and DLPC because the up-down and cross-correlation motions of GS in DMPC was the lowest among the three lipids,and GS mobility in DMPC was the lowest among all five lipids.This may be because the alkyl tail chain length(i.e.,3.8 nm thickness of the DMPC bilayer)was suitable for GS embedding,thereby restraining more GS motions than that of the long(DOPC)or short lipids(DLPC).Collectively,these results indicated that GS activity can be modulated through changes in conformational fluctuations,structural perturbations,molecular motion,and cross-correlation motion when embedded in different lipids.Exploration of such fundamental information can reveal the possible mechanisms by which GS is affected by individual lipid species.
