We consider an epidemical model within soclally interacting mobile individuals to study the behaviors of steady states of epidemic propagation in 2D networks. Using mean-field approximation and large scale simulations...We consider an epidemical model within soclally interacting mobile individuals to study the behaviors of steady states of epidemic propagation in 2D networks. Using mean-field approximation and large scale simulations, we recover the usual epidemic behavior with critical thresholds δc and pc below which infectious disease dies out. For the population density δ far above δc it is found that there is linear relationship between contact rate λ and the population density δ in the main. At the same time, the result obtained from mean-field approximation is compared with our numerical result, and it is found that these two results are similar by and large but not completely the same.展开更多
Discocephalids and pseudoamphisiellids are possibly two of the most confused groups among hypotrichous/euplotid ciliates regarding their systematic position and phylogenetic relationships.The former were often regarde...Discocephalids and pseudoamphisiellids are possibly two of the most confused groups among hypotrichous/euplotid ciliates regarding their systematic position and phylogenetic relationships.The former were often regarded as related to euplotids while the latter,in the absence of molecular data,were mostly assigned to the urostylid-like hypotrichs.In the present work,the small subunit rRNA genes of several rarely observed discocephalid and pseudoamphisiellid genera were analyzed to obtain insights into the phylogenetic relationships of these highly ambiguous Spirotrichea.Four different tree reconstruction algorithms yielded nearly identical topologies,which indicated both groups belong to the same assemblage.This assemblage is clearly isolated as a deep-branching clade and invariably positioned between Euplotida and Hypotricha.The sister group relationship of the Pseudoamphisiellidae and Discocephalidae supports the previous suggestion that they might represent an ordinal taxon,the Discocephalida.Both morphological and morphogenetic features indicate that the pseudoamphisiellids should be placed in the order Discocephalida but as a sister group to other typical discocephalids.Thus we propose establishing a new suborder,Pseudoamphisiellina subord.n.The new taxon is diagnosed by the following characteristics:(i) two distantly separated midventral rows that are morphogenetically formed with an urostylid mode;(ii) absence of the "frontoterminal row",which is formed from the posterior-most frontoventral-transverse cirral anlage in all other typical urostylids;(iii) numerous caudal cirri that derive from each of the dorsal kinety anlagen;(iv) right marginal row that has a unique de novo origin;and (v) inhabiting periphytic communities.The validity of the suborder Pseudoamphisiellina is firmly supported by molecular data.展开更多
基金The project supported by National Natural Science Foundation of China under Grant No. 50272022 and the Sunshine Foundation of Wuhan City under Grant No. 20045006071-40
文摘We consider an epidemical model within soclally interacting mobile individuals to study the behaviors of steady states of epidemic propagation in 2D networks. Using mean-field approximation and large scale simulations, we recover the usual epidemic behavior with critical thresholds δc and pc below which infectious disease dies out. For the population density δ far above δc it is found that there is linear relationship between contact rate λ and the population density δ in the main. At the same time, the result obtained from mean-field approximation is compared with our numerical result, and it is found that these two results are similar by and large but not completely the same.
基金supported by the National Natural Science Foundation of China (Grant Nos. 40906065 and 31030059)
文摘Discocephalids and pseudoamphisiellids are possibly two of the most confused groups among hypotrichous/euplotid ciliates regarding their systematic position and phylogenetic relationships.The former were often regarded as related to euplotids while the latter,in the absence of molecular data,were mostly assigned to the urostylid-like hypotrichs.In the present work,the small subunit rRNA genes of several rarely observed discocephalid and pseudoamphisiellid genera were analyzed to obtain insights into the phylogenetic relationships of these highly ambiguous Spirotrichea.Four different tree reconstruction algorithms yielded nearly identical topologies,which indicated both groups belong to the same assemblage.This assemblage is clearly isolated as a deep-branching clade and invariably positioned between Euplotida and Hypotricha.The sister group relationship of the Pseudoamphisiellidae and Discocephalidae supports the previous suggestion that they might represent an ordinal taxon,the Discocephalida.Both morphological and morphogenetic features indicate that the pseudoamphisiellids should be placed in the order Discocephalida but as a sister group to other typical discocephalids.Thus we propose establishing a new suborder,Pseudoamphisiellina subord.n.The new taxon is diagnosed by the following characteristics:(i) two distantly separated midventral rows that are morphogenetically formed with an urostylid mode;(ii) absence of the "frontoterminal row",which is formed from the posterior-most frontoventral-transverse cirral anlage in all other typical urostylids;(iii) numerous caudal cirri that derive from each of the dorsal kinety anlagen;(iv) right marginal row that has a unique de novo origin;and (v) inhabiting periphytic communities.The validity of the suborder Pseudoamphisiellina is firmly supported by molecular data.
