Well-preserved specimens of Hamatophyton verticillatum collected from the Upper Devonian （Famennian） Wutong Formation of Chaohu district, Anhui Province, South China, display more complete fertile axes in three orde...Well-preserved specimens of Hamatophyton verticillatum collected from the Upper Devonian （Famennian） Wutong Formation of Chaohu district, Anhui Province, South China, display more complete fertile axes in three orders and multiple divisions. Comparisons indicate that Hamatophyton possibly does not have palmate planate sterile leaves but hook-like linear ones with rare divisions. We propose seven definitive characters of Sphenophyllales： （1） completely whorled lateral organs; （2） sterile leaves; （3） strobili; （4） ＂sporangiophores＂ or stalks with reflexed tips bearing sporangia; （5） three- or four-ribbed primary xylem; （6） exarch maturation of primary xylem; and （7） secondary xylem. The Sphenophyllales probably originated from the Iridopteridales based on similarities in whorled lateral organs, ribbed primary xylem and peripheral protoxylem strands. In transition from Iridopteridales to Sphenophyllales, morphological changes involve partially whorled to completely whorled lateral organs, sterile ultimate appendages to leaves, and fertile ultimate appendages to ＂sporangiophores＂/stalks with bracts; anatomical modifications include configuration and maturation of primary xylem, and presence of secondary xylem.展开更多
This paper investigates the dynamic evolution with limited learning information on a small-world network.In the system, the information among the interaction players is not very lucid, and the players are not allowed ...This paper investigates the dynamic evolution with limited learning information on a small-world network.In the system, the information among the interaction players is not very lucid, and the players are not allowed to inspectthe profit collected by its neighbors, thus the focal player cannot choose randomly a neighbor or the wealthiest one andcompare its payoff to copy its strategy.It is assumed that the information acquainted by the player declines in theform of the exponential with the geographical distance between the players, and a parameter V is introduced to denotethe inspect-ability about the players.It is found that under the hospitable conditions, cooperation increases with therandomness and is inhibited by the large connectivity for the prisoner's dilemma; however, cooperation is maximal atthe moderate rewiring probability and is chaos with the connectivity for the snowdrift game.For the two games, theacuminous sight is in favor of the cooperation under the hospitable conditions; whereas, the myopic eyes are advantageousto cooperation and cooperation increases with the randomness under the hostile condition.展开更多
We present the major results from studies of fire history over the last 11000 years(Holocene) in southern Sweden, on the basis of palaeoecological analyses of peat sequences from three small peat bogs. The main object...We present the major results from studies of fire history over the last 11000 years(Holocene) in southern Sweden, on the basis of palaeoecological analyses of peat sequences from three small peat bogs. The main objective is to emphasize the value of multiple, continuous sedimentary records of macroscopic charcoal(macro-C) for the reconstruction of local to regional past changes in fire regimes, the importance of multi-proxy studies, and the advantage of model-based estimates of plant cover from pollen data to assess the role of tree composition and human impact in fire history. The chronologies at the three study sites are based on a large number of 14 C dates from terrestrial plant remains and age-depth models are achieved using Bayesian statistics. Fire history is inferred from continuous records of macro-C and microscopic charcoal counts on pollen slides. The Landscape Reconstruction Algorithm(LRA) for pollen-based quantitative reconstruction of local vegetation cover is applied on the three pollen records for plant cover reconstruction over the entire Holocene. The results are as follows:(1) the long-term trends in fire regimes are similar between sites, i.e., frequent fires during the early Holocene until ca. 9 ka BP, low fire frequency during the mid-Holocene, and higher fire frequency from ca. 2.5 ka BP;(2) this broad trend agrees with the overall fire history of northwestern and western Europe north of the Mediterranean area, and is due to climate forcing in the early and mid-Holocene, and to anthropogenic land-use in the late Holocene;(3) the LRA estimates of plant cover at the three sites demonstrate that the relative abundance of pine played a primordial role in the early and mid-Holocene fire history; and(4) the between-site differences in the charcoal records and inferred fire history are due to local factors(i.e., relative abundance of pine, geomorphological setting, and anthropogenic land-use) and taphonomy of charcoal deposition in the small peat bogs. It is shown that continuous macro-C records are most useful to disentangle local from regional-subcontinental fire history, and climate-induced from human-induced fire regimes, and that pollen-based LRA estimates of local plant cover are more adequate than pollen percentages for the assessment of the role of plant composition on fire history.展开更多
A new model for three-dimensional processes based on the trinion algebra is introduced for the first time.Compared to the pure quaternion model, the trinion model is more compact and computationally more efficient,whi...A new model for three-dimensional processes based on the trinion algebra is introduced for the first time.Compared to the pure quaternion model, the trinion model is more compact and computationally more efficient,while having similar or comparable performance in terms of adaptive linear filtering. Moreover, the trinion model can effectively represent the general relationship of state evolution in Kalman filtering, where the pure quaternion model fails. Simulations on real-world wind recordings and synthetic data sets are provided to demonstrate the potential of this new modeling method.展开更多
A prisoner's dilemma game model is studied using complex networks with a fixed strategy. The strategy of the player is updated according to not only the payoff differences between players and the neighbors, but al...A prisoner's dilemma game model is studied using complex networks with a fixed strategy. The strategy of the player is updated according to not only the payoff differences between players and the neighbors, but also the majority of neighbors (noted as conformist mentality strategy). According to our results of the simulations we found that the players which select the conformist mentality strategy, the density of cooperators markedly improves. The variation trend is slower on the square lattice and small-world networks, but a different phenomenon is noted for scale-free networks. A range of conformist mentality probability is seen on BA networks which conforms to a higher density of cooperators.展开更多
基金supported by the National Natural ScienceFoundation of China(Grant Nos.40772010,40830211)Program for New Century Excellent Talents in theUniversity of China(NCET-06-0012)
文摘Well-preserved specimens of Hamatophyton verticillatum collected from the Upper Devonian （Famennian） Wutong Formation of Chaohu district, Anhui Province, South China, display more complete fertile axes in three orders and multiple divisions. Comparisons indicate that Hamatophyton possibly does not have palmate planate sterile leaves but hook-like linear ones with rare divisions. We propose seven definitive characters of Sphenophyllales： （1） completely whorled lateral organs; （2） sterile leaves; （3） strobili; （4） ＂sporangiophores＂ or stalks with reflexed tips bearing sporangia; （5） three- or four-ribbed primary xylem; （6） exarch maturation of primary xylem; and （7） secondary xylem. The Sphenophyllales probably originated from the Iridopteridales based on similarities in whorled lateral organs, ribbed primary xylem and peripheral protoxylem strands. In transition from Iridopteridales to Sphenophyllales, morphological changes involve partially whorled to completely whorled lateral organs, sterile ultimate appendages to leaves, and fertile ultimate appendages to ＂sporangiophores＂/stalks with bracts; anatomical modifications include configuration and maturation of primary xylem, and presence of secondary xylem.
基金Supported by Natural Science Foundation of China under Grant No.10974146
文摘This paper investigates the dynamic evolution with limited learning information on a small-world network.In the system, the information among the interaction players is not very lucid, and the players are not allowed to inspectthe profit collected by its neighbors, thus the focal player cannot choose randomly a neighbor or the wealthiest one andcompare its payoff to copy its strategy.It is assumed that the information acquainted by the player declines in theform of the exponential with the geographical distance between the players, and a parameter V is introduced to denotethe inspect-ability about the players.It is found that under the hospitable conditions, cooperation increases with therandomness and is inhibited by the large connectivity for the prisoner's dilemma; however, cooperation is maximal atthe moderate rewiring probability and is chaos with the connectivity for the snowdrift game.For the two games, theacuminous sight is in favor of the cooperation under the hospitable conditions; whereas, the myopic eyes are advantageousto cooperation and cooperation increases with the randomness under the hostile condition.
基金the financial support from the Faculty of Health and Life Sciences of the Linnaeus University (Kalmar, Sweden)
文摘We present the major results from studies of fire history over the last 11000 years(Holocene) in southern Sweden, on the basis of palaeoecological analyses of peat sequences from three small peat bogs. The main objective is to emphasize the value of multiple, continuous sedimentary records of macroscopic charcoal(macro-C) for the reconstruction of local to regional past changes in fire regimes, the importance of multi-proxy studies, and the advantage of model-based estimates of plant cover from pollen data to assess the role of tree composition and human impact in fire history. The chronologies at the three study sites are based on a large number of 14 C dates from terrestrial plant remains and age-depth models are achieved using Bayesian statistics. Fire history is inferred from continuous records of macro-C and microscopic charcoal counts on pollen slides. The Landscape Reconstruction Algorithm(LRA) for pollen-based quantitative reconstruction of local vegetation cover is applied on the three pollen records for plant cover reconstruction over the entire Holocene. The results are as follows:(1) the long-term trends in fire regimes are similar between sites, i.e., frequent fires during the early Holocene until ca. 9 ka BP, low fire frequency during the mid-Holocene, and higher fire frequency from ca. 2.5 ka BP;(2) this broad trend agrees with the overall fire history of northwestern and western Europe north of the Mediterranean area, and is due to climate forcing in the early and mid-Holocene, and to anthropogenic land-use in the late Holocene;(3) the LRA estimates of plant cover at the three sites demonstrate that the relative abundance of pine played a primordial role in the early and mid-Holocene fire history; and(4) the between-site differences in the charcoal records and inferred fire history are due to local factors(i.e., relative abundance of pine, geomorphological setting, and anthropogenic land-use) and taphonomy of charcoal deposition in the small peat bogs. It is shown that continuous macro-C records are most useful to disentangle local from regional-subcontinental fire history, and climate-induced from human-induced fire regimes, and that pollen-based LRA estimates of local plant cover are more adequate than pollen percentages for the assessment of the role of plant composition on fire history.
基金Project supported by the National Natural Science Foundation of China（Nos.61331019 and 61490691） the China Scholarship Council Postgraduate Scholarship Program（2014） the National Grid（UK）
文摘A new model for three-dimensional processes based on the trinion algebra is introduced for the first time.Compared to the pure quaternion model, the trinion model is more compact and computationally more efficient,while having similar or comparable performance in terms of adaptive linear filtering. Moreover, the trinion model can effectively represent the general relationship of state evolution in Kalman filtering, where the pure quaternion model fails. Simulations on real-world wind recordings and synthetic data sets are provided to demonstrate the potential of this new modeling method.
文摘A prisoner's dilemma game model is studied using complex networks with a fixed strategy. The strategy of the player is updated according to not only the payoff differences between players and the neighbors, but also the majority of neighbors (noted as conformist mentality strategy). According to our results of the simulations we found that the players which select the conformist mentality strategy, the density of cooperators markedly improves. The variation trend is slower on the square lattice and small-world networks, but a different phenomenon is noted for scale-free networks. A range of conformist mentality probability is seen on BA networks which conforms to a higher density of cooperators.
