The sizes of Astyanax mexicanus blind cavefish populations of North-East Mexico are demographic parameters of great importance for investigating a variety of ecological,evolutionary,and conservation issues.However,few...The sizes of Astyanax mexicanus blind cavefish populations of North-East Mexico are demographic parameters of great importance for investigating a variety of ecological,evolutionary,and conservation issues.However,few estimates have been obtained.For these mobile animals living in an environment difficult to explore as a whole,methods based on capture-mark-recapture are appropriate,but their feasibility and interpretation of results depend on several assumptions that must be carefully examined.Here,we provide evidence that minimally invasive genetic identification from captures at different time intervals(three days and three years)can give insights into cavefish population size dynamics as well as other important demographic parameters of interest.We also provide tools to calibrate sampling and genotyping efforts necessary to reach a given level of precision.Our results suggest that the El Pachón cave population is currently very small,of an order of magnitude of a few hundreds of individuals,and is distributed in a relatively isolated area.The probable decline in population size in the El Pachón cave since the last census in 1971 raises serious conservation issues.展开更多
The plant material used in the study was rice line 162d, a new small grain dwarf mutant. Polymorphic analysis of 221 SSR loci demonstrated that 162d derived from a semidwarf variety Shuhui 162 through mutation, and 16...The plant material used in the study was rice line 162d, a new small grain dwarf mutant. Polymorphic analysis of 221 SSR loci demonstrated that 162d derived from a semidwarf variety Shuhui 162 through mutation, and 162d and Shuhui 162 were just a pair of near isogenic lines. Genetic analysis of F_1 and F_2 populations suggested that dwarfism in 162d was controlled by a single recessive gene. Phenotypic characteristics of the mutant gene were that plant height was about a quarter of normal height, grain size about a quarter of normal size, leaf was short and broad, and seed setting rate was very low, compared with the near isogenic line Shuhui 162. The mutant gene was sensitive to gibberellin (GA_3) treatment and did not located on the region near the centromere of rice chromosome 5, where dl gene located. Therefore, it was concluded that the mutant gene of 162d was a new small grain dwarf gene in rice.展开更多
By applying genetic algorithms (GA) to on-line identification of linear time-varying systems; a number of modifications are made to the Simple Genetic Algorithm to improve the performance of the algorithm in identific...By applying genetic algorithms (GA) to on-line identification of linear time-varying systems; a number of modifications are made to the Simple Genetic Algorithm to improve the performance of the algorithm in identification applications. The simulation results indicate that the method is not only capable of following the changing parameters of the system, but also has improved the identification accuracy compared with that using the least square method.展开更多
Occurrence and abundance of molecular hydrogen in natural geologic reservoirs are enigmatic,due to its various sources,diverse migration pathways and complicated biological and chemical reactions.Natural gas samples c...Occurrence and abundance of molecular hydrogen in natural geologic reservoirs are enigmatic,due to its various sources,diverse migration pathways and complicated biological and chemical reactions.Natural gas samples containing hydrogen from producing wells in several sedimentary basins in China were collected in this study,and gas abundances and isotopic compositions of these gases were compared with those in global petroliferous basins and deep intrusive rocks.Several geochemical indicators were suggested for identifying sources,migration and accumulation mechanisms of hydrogen in the subsurface environment.Hydrogen contents in natural gas deposits have contributions from various sources with the following high-to-low order:microbial degradation>serpentinization>deep mantle volatile release>radiation-induced water decomposition>thermal cracking of organic matter.A hydrogen-rich reservoir in Kansas,USA,is specifically analyzed to determine its formation mechanism.This study suggests that future exploration of geological hydrogen resources may focus on the igneous rock bodies with overlying dense sedimentary rocks in the continental rift systems.展开更多
Based on the research progress of the geological theory of coal-formed gas,the contributions of coal-formed gas to the natural gas reserves and production in China and to the development of natural gas in major gas-pr...Based on the research progress of the geological theory of coal-formed gas,the contributions of coal-formed gas to the natural gas reserves and production in China and to the development of natural gas in major gas-producing basins are analyzed,and the key favorable exploration zones for coal-formed gas in China are comprehensively evaluated.The following results are obtained.First,coal measures are good gas source rocks,and hydrocarbon generation from coal measure was dominated by gas,followed by oil.Second,a natural gas genetic identification index system based on stable isotopes,light hydrocarbon components,and biomarkers is established.Third,the quantitative and semi-quantitative factors controlling the formation of large gas fields,represented by the indicator of gas generation intensity greater than 20×10^(8) m^(3)/km^(2),are identified to guide the discovery of large gas fields in China.Fourth,coal-formed gas is the major contributor to the current natural gas reserves and production of China,both accounting for over 55%.The high proportion of coal-formed gas has enabled the Tarim,Sichuan and Ordos basins to be the major gas production areas in China.Fifth,coal rock gas is an important field for future exploration of coal-formed gas,and key zones include the Carboniferous Benxi Formation(Fm.)in the Wushenqi-Mizhi area of the Ordos Basin,the Permian Longtan Fm.in central-southern Sichuan Basin,the Jurassic Xishanyao Fm.in the southern margin and Luliang uplift of the Junggar Basin.Sixth,tight gas is the main area for increasing reserves and production,and the favorable exploration zones include the Carboniferous-Permian in southern Ordos Basin and the Bohai Bay Basin,and the Triassic Xujiahe Fm.in the transition zone between central and western Sichuan Basin.Seventh,the Jurassic in the southern margin of the Junggar Basin is a key favorable exploration zone for subsequent investigation of conventional coal-formed gas.These insights have valuable theoretical and practical significance for further developing and improving the theory of coal-formed gas,and guiding the exploration of coal-formed gas fields in China.展开更多
基金supported by a CNRS MITI (Mission pour les Initiatives Transverses et Interdisciplinaires) grant “Expérimentation en Milieux Extrêmes” to S.R.collaborative grants from Agence Nationale de la Recherche (BLINDTEST)Institut Diversité Ecologie et Evolution du Vivant to S.R. and D.C
文摘The sizes of Astyanax mexicanus blind cavefish populations of North-East Mexico are demographic parameters of great importance for investigating a variety of ecological,evolutionary,and conservation issues.However,few estimates have been obtained.For these mobile animals living in an environment difficult to explore as a whole,methods based on capture-mark-recapture are appropriate,but their feasibility and interpretation of results depend on several assumptions that must be carefully examined.Here,we provide evidence that minimally invasive genetic identification from captures at different time intervals(three days and three years)can give insights into cavefish population size dynamics as well as other important demographic parameters of interest.We also provide tools to calibrate sampling and genotyping efforts necessary to reach a given level of precision.Our results suggest that the El Pachón cave population is currently very small,of an order of magnitude of a few hundreds of individuals,and is distributed in a relatively isolated area.The probable decline in population size in the El Pachón cave since the last census in 1971 raises serious conservation issues.
文摘The plant material used in the study was rice line 162d, a new small grain dwarf mutant. Polymorphic analysis of 221 SSR loci demonstrated that 162d derived from a semidwarf variety Shuhui 162 through mutation, and 162d and Shuhui 162 were just a pair of near isogenic lines. Genetic analysis of F_1 and F_2 populations suggested that dwarfism in 162d was controlled by a single recessive gene. Phenotypic characteristics of the mutant gene were that plant height was about a quarter of normal height, grain size about a quarter of normal size, leaf was short and broad, and seed setting rate was very low, compared with the near isogenic line Shuhui 162. The mutant gene was sensitive to gibberellin (GA_3) treatment and did not located on the region near the centromere of rice chromosome 5, where dl gene located. Therefore, it was concluded that the mutant gene of 162d was a new small grain dwarf gene in rice.
文摘By applying genetic algorithms (GA) to on-line identification of linear time-varying systems; a number of modifications are made to the Simple Genetic Algorithm to improve the performance of the algorithm in identification applications. The simulation results indicate that the method is not only capable of following the changing parameters of the system, but also has improved the identification accuracy compared with that using the least square method.
基金supported by the National Natural Science Foundation of China(Nos.42488101,42141021,42172149,42172168,U2244209)the Tencent Foundation through the XPLORER PRIZE。
文摘Occurrence and abundance of molecular hydrogen in natural geologic reservoirs are enigmatic,due to its various sources,diverse migration pathways and complicated biological and chemical reactions.Natural gas samples containing hydrogen from producing wells in several sedimentary basins in China were collected in this study,and gas abundances and isotopic compositions of these gases were compared with those in global petroliferous basins and deep intrusive rocks.Several geochemical indicators were suggested for identifying sources,migration and accumulation mechanisms of hydrogen in the subsurface environment.Hydrogen contents in natural gas deposits have contributions from various sources with the following high-to-low order:microbial degradation>serpentinization>deep mantle volatile release>radiation-induced water decomposition>thermal cracking of organic matter.A hydrogen-rich reservoir in Kansas,USA,is specifically analyzed to determine its formation mechanism.This study suggests that future exploration of geological hydrogen resources may focus on the igneous rock bodies with overlying dense sedimentary rocks in the continental rift systems.
基金Supported by the Petro China Science and Technology Project(2023YQX10101)National Natural Science Foundation of China(42372165)。
文摘Based on the research progress of the geological theory of coal-formed gas,the contributions of coal-formed gas to the natural gas reserves and production in China and to the development of natural gas in major gas-producing basins are analyzed,and the key favorable exploration zones for coal-formed gas in China are comprehensively evaluated.The following results are obtained.First,coal measures are good gas source rocks,and hydrocarbon generation from coal measure was dominated by gas,followed by oil.Second,a natural gas genetic identification index system based on stable isotopes,light hydrocarbon components,and biomarkers is established.Third,the quantitative and semi-quantitative factors controlling the formation of large gas fields,represented by the indicator of gas generation intensity greater than 20×10^(8) m^(3)/km^(2),are identified to guide the discovery of large gas fields in China.Fourth,coal-formed gas is the major contributor to the current natural gas reserves and production of China,both accounting for over 55%.The high proportion of coal-formed gas has enabled the Tarim,Sichuan and Ordos basins to be the major gas production areas in China.Fifth,coal rock gas is an important field for future exploration of coal-formed gas,and key zones include the Carboniferous Benxi Formation(Fm.)in the Wushenqi-Mizhi area of the Ordos Basin,the Permian Longtan Fm.in central-southern Sichuan Basin,the Jurassic Xishanyao Fm.in the southern margin and Luliang uplift of the Junggar Basin.Sixth,tight gas is the main area for increasing reserves and production,and the favorable exploration zones include the Carboniferous-Permian in southern Ordos Basin and the Bohai Bay Basin,and the Triassic Xujiahe Fm.in the transition zone between central and western Sichuan Basin.Seventh,the Jurassic in the southern margin of the Junggar Basin is a key favorable exploration zone for subsequent investigation of conventional coal-formed gas.These insights have valuable theoretical and practical significance for further developing and improving the theory of coal-formed gas,and guiding the exploration of coal-formed gas fields in China.
