The rapid spread of mobile tigecycline resistance presents a significant public health threat,particularly with the increasing prevalence of tet(X4)-positive Enterobacterales across various species.This study aimed to...The rapid spread of mobile tigecycline resistance presents a significant public health threat,particularly with the increasing prevalence of tet(X4)-positive Enterobacterales across various species.This study aimed to inves-tigate the epidemic features and transmission dynamics of tet(X4)-positive Klebsiella pneumoniae(K.pneumo-niae)through the analysis of 206 raw meats,including pork(n=182),beef(n=16),duck(n=5),and chicken(n=3).These samples were collected from schools,markets,and restaurants in Chengdu City,China.A total of 25 isolates were obtained from 13 administrative regions.All isolates exhibited resistance to tetracycline,tigecycline,ampicillin,chloramphenicol,and florfenicol.Over half of the isolates also demon-strated resistance to streptomycin(80%),sulfamethoxazole/trimethoprim(72%),ciprofloxacin(64%),and ampicillin/sulbactam(56%).Among these strains,14 distinct sequence types(STs)were identified,revealing evidence of inter-regional clonal spread,notably among 9 K.pneumoniae ST3393.Phylogenetic analysis revealed the presence of two K.pneumoniae ST5 closely resembling hypervirulent K.pneumoniae from Jiangsu.Importantly,12 isolates were capable of transferring tigecycline resistance to Escherichia coli J53.Further plasmid analysis showed that the tet(X4)-harboring plasmids in K.pneumoniae could be classified into four types,primarily belonging to the IncFIA(HI1)/HI1A/HI1B hybrid plasmid(n=16)and IncFII plasmid(n=7),which significantly contributed to the cross-species dissemination of tet(X4).In summary,this study highlights the prevalence of MDR tet(X4)-positive K.pneumoniae in Chengdu,driven predominantly by clonal expansion and plasmid-mediated horizontal gene transfer.These findings emphasize the importance of contin-uous surveillance of tet(X4)-positive K.pneumoniae in raw meat and the implementation of effective measures to control their spread.展开更多
In this paper,we set up a mixed duopoly competition model between state-owned and private firms in order to compare specific and ad valorem taxes.Assuming that the total output under specific and ad valorem taxation r...In this paper,we set up a mixed duopoly competition model between state-owned and private firms in order to compare specific and ad valorem taxes.Assuming that the total output under specific and ad valorem taxation remains unchanged,we find that if the public firm is completely privatised,the output of the private firm under the two tax schemes will be the same.If the public firm is not completely privatised,the output of the the private firm under specific taxation will be greater than that under ad valorem taxation.If the private firm is a pure local one,the social benefits will be the same under the two tax schemes.However,if the private firm is a joint venture that involves domestic and foreign entities,social welfare under ad valorem taxation will be greater than that under specific taxation.展开更多
We study the existence of standing waves of fractional Schrodinger equations with a potential term and a general nonlinear term:iut-(-Δ)^(s)u-V(x)u+f(u)=0,(t,x)∈R_(+)×R^(N),where s∈(0,1),N>2s is an integer ...We study the existence of standing waves of fractional Schrodinger equations with a potential term and a general nonlinear term:iut-(-Δ)^(s)u-V(x)u+f(u)=0,(t,x)∈R_(+)×R^(N),where s∈(0,1),N>2s is an integer and V(x)≤0 is radial.More precisely,we investigate the minimizing problem with L2-constraint:E(a)=inf{1/2∫_(R_(N))|(-△)^(s/2)u|^(2)+V(x)|u|^(2)-2F(|u|)|u∈H^(s)(R^(N)),||u||_(L^(2))^(2)(R^(N))=α.Under general assumptions on the nonlinearity term f(u)and the potential term V(x),we prove that there exists a constant a00 such that E(a)can be achieved for all a>a_(0),and there is no global minimizer with respect to E(a)for all 0<a<a_(0).Moreover,we propose some criteria determining a0=0 or a_(0)>0.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFD1800400)National Natural Science Foundation of China(No.81991531)+1 种基金Natural Science Foundation of Shandong Province(No.ZR2020MC188)The sequence data of 25 K.pneumoniae isolates have been submitted to NCBI under BioProject accession number PRJNA1011004.
文摘The rapid spread of mobile tigecycline resistance presents a significant public health threat,particularly with the increasing prevalence of tet(X4)-positive Enterobacterales across various species.This study aimed to inves-tigate the epidemic features and transmission dynamics of tet(X4)-positive Klebsiella pneumoniae(K.pneumo-niae)through the analysis of 206 raw meats,including pork(n=182),beef(n=16),duck(n=5),and chicken(n=3).These samples were collected from schools,markets,and restaurants in Chengdu City,China.A total of 25 isolates were obtained from 13 administrative regions.All isolates exhibited resistance to tetracycline,tigecycline,ampicillin,chloramphenicol,and florfenicol.Over half of the isolates also demon-strated resistance to streptomycin(80%),sulfamethoxazole/trimethoprim(72%),ciprofloxacin(64%),and ampicillin/sulbactam(56%).Among these strains,14 distinct sequence types(STs)were identified,revealing evidence of inter-regional clonal spread,notably among 9 K.pneumoniae ST3393.Phylogenetic analysis revealed the presence of two K.pneumoniae ST5 closely resembling hypervirulent K.pneumoniae from Jiangsu.Importantly,12 isolates were capable of transferring tigecycline resistance to Escherichia coli J53.Further plasmid analysis showed that the tet(X4)-harboring plasmids in K.pneumoniae could be classified into four types,primarily belonging to the IncFIA(HI1)/HI1A/HI1B hybrid plasmid(n=16)and IncFII plasmid(n=7),which significantly contributed to the cross-species dissemination of tet(X4).In summary,this study highlights the prevalence of MDR tet(X4)-positive K.pneumoniae in Chengdu,driven predominantly by clonal expansion and plasmid-mediated horizontal gene transfer.These findings emphasize the importance of contin-uous surveillance of tet(X4)-positive K.pneumoniae in raw meat and the implementation of effective measures to control their spread.
基金supported by the Social Science Foundation of Shaanxi Province of China[Grant No.2019D037]the Fundamental Research Funds for the Central Universities of China[Grant No.310823153013].
文摘In this paper,we set up a mixed duopoly competition model between state-owned and private firms in order to compare specific and ad valorem taxes.Assuming that the total output under specific and ad valorem taxation remains unchanged,we find that if the public firm is completely privatised,the output of the private firm under the two tax schemes will be the same.If the public firm is not completely privatised,the output of the the private firm under specific taxation will be greater than that under ad valorem taxation.If the private firm is a pure local one,the social benefits will be the same under the two tax schemes.However,if the private firm is a joint venture that involves domestic and foreign entities,social welfare under ad valorem taxation will be greater than that under specific taxation.
基金funded by Natural Science Foundation of Hebei Province(No.A2022205007)Science and Technology Project of Hebei Education Department(No.QN2022047)+1 种基金Science Foundation of Hebei Normal University(No.L2021B05)supported by National Natural Science Foundation of China(Nos.11771428,12031015 and 12026217).
文摘We study the existence of standing waves of fractional Schrodinger equations with a potential term and a general nonlinear term:iut-(-Δ)^(s)u-V(x)u+f(u)=0,(t,x)∈R_(+)×R^(N),where s∈(0,1),N>2s is an integer and V(x)≤0 is radial.More precisely,we investigate the minimizing problem with L2-constraint:E(a)=inf{1/2∫_(R_(N))|(-△)^(s/2)u|^(2)+V(x)|u|^(2)-2F(|u|)|u∈H^(s)(R^(N)),||u||_(L^(2))^(2)(R^(N))=α.Under general assumptions on the nonlinearity term f(u)and the potential term V(x),we prove that there exists a constant a00 such that E(a)can be achieved for all a>a_(0),and there is no global minimizer with respect to E(a)for all 0<a<a_(0).Moreover,we propose some criteria determining a0=0 or a_(0)>0.
