This paper aims to estimate the soil organic carbon （SOC） storage in Northeast of China, identify its balance situation and changing trends under current cropping systems, and finally put forward some strategies to ...This paper aims to estimate the soil organic carbon （SOC） storage in Northeast of China, identify its balance situation and changing trends under current cropping systems, and finally put forward some strategies to keep the SOC in balance. A biogeochemical model （DNDC） for agro-ecosystem was employed to predict SOC dynamics in agricultural ecosystems at regional scale. Data on climate, soil properties, cropping systems, acreage, and management practices at county scale were collected from various sources and integrated into a GIS database to support the model runs at the regional scale. The model predicted results revealed that （1） Total SOC storage in agricultural lands in Heilongjiang, Jilin and Liaoning provinces in Northeast of China is about 1 243.48 × 10^6 t （0-30cm soil layer）, respectively occupying 58.4, 25.5 and 16.1%; （2） Under the current cultivation systems, SOC is in a situation of net loss with carbon losing at a high rate of 31.22 × 10^6 t a^-1 （respectively 59.3, 25.9 and 14.8% in Heilongjiang, Jilin and Liaoning provinces） and 2.05 t ha^-1 a^-1, the situation is more serious in Heilongjiang and Jilin provinces; and （3） Protective cultivations, such as manuring, returning more residue of crop to the field, adopting no-till, are very useful for the accumulation of SOC in these regions.展开更多
A number of process-based models have been developed for quantifying carbon(C)sequestration in agro-ecosystems.The DeNitrification-DeComposition(DNDC)model was used to simulate and quantify long-term(1980-2008)soil or...A number of process-based models have been developed for quantifying carbon(C)sequestration in agro-ecosystems.The DeNitrification-DeComposition(DNDC)model was used to simulate and quantify long-term(1980-2008)soil organic carbon(SOC)dynamics in the important rice-producing province,Jiangsu,China.Changes in SOC storages were estimated from two soil databases differing in spatial resolution:a county database consisting of 68 polygons and a soil patch-based database of 701 polygons for all 3.7 Mha of rice fields in Jiangsu.The simulated SOC storage with the coarse resolution county database ranged between 131.0-320.6 Tg C in 1980 and 170.3-305.1 Tg C in 2008,respectively,while that estimated with the fine resolution database was 201.6 and 216.2 Tg C in 1980 and 2008,respectively.The results modeled with the soil databases differing in spatial resolution indicated that using the soil input data with higher resolution substantially increased the accuracy of the modeled results;and when lacking detailed soil datasets,the DNDC model,parameterized with the most sensitive factor(MSF) method to cope with attribute uncertainty,could still produce acceptable results although with deviations of up to 60% for the case study reported in this paper.展开更多
Foot-and-mouth disease is one of the major contagious zoonotic diseases in the world.It is caused by various species of the genus Aphthovirus of the family Picornavirus,and it always brings a large number of infection...Foot-and-mouth disease is one of the major contagious zoonotic diseases in the world.It is caused by various species of the genus Aphthovirus of the family Picornavirus,and it always brings a large number of infections and heavy financial losses.The disease has become a major public health concern.In this paper,we propose a nonlocal foot-and-mouth disease model in a spatially heterogeneous environment,which couples virus-to-animals and animals-to-animals transmission pathways,and investigate the dynamics of the disperal.The basic reproduction number R_(0)is defined as the spectral radius of the next generation operator R(x)by a renewal equation.The relationship between R_(0)and a principal eigenvalue of an operator L_(0)is built.Moreover,the proposed system exhibits threshold dynamics in terms of R_(0),in the sense that R_(0)determines whether or not foot-and-mouth disease invades the hosts.Through numerical simulations,we have found that increasing animals'movements is an effective control measure for preventing prevalence of the disease.展开更多
Inositol 1,4,5-trisphosphate receptors(IP_(3)R)-mediated calcium ion(Ca^(2+))release plays a central role in the regulation of cell survival and death.Bcl-2 limits the Ca^(2+)release function of the IP3R through a dir...Inositol 1,4,5-trisphosphate receptors(IP_(3)R)-mediated calcium ion(Ca^(2+))release plays a central role in the regulation of cell survival and death.Bcl-2 limits the Ca^(2+)release function of the IP3R through a direct or indirect mechanism.However,the two mechanisms are overwhelmingly complex and not completely understood.Here,we convert the mechanisms into a set of ordinary differential equations.We firstly simulate the time evolution of Ca^(2+)concentration under two different levels of Bcl-2 for the direct and indirect mechanism models and compare them with experimental results available in the literature.Secondly,we employ one-and two-parameter bifurcation analysis to demonstrate that Bcl-2 can suppress Ca^(2+)signal from a global point of view both in the direct and indirect mechanism models.We then use mathematical analysis to clarify that the indirect mechanism is more efficient than the direct mechanism in repressing Ca^(2+)signal.Lastly,we predict that the two mechanisms restrict Ca^(2+)signal synergistically.Together,our study provides theoretical insights into Bcl-2 regulation in IP_(3)R-mediated Ca^(2+)release,which may be instrumental for the successful development of therapies to target Bcl-2 for cancer treatment.展开更多
Over the last few years,the interplay between contagion dynamics of social influences(e.g.,human awareness,risk perception,and information dissemination)and biological infections has been extensively investigated with...Over the last few years,the interplay between contagion dynamics of social influences(e.g.,human awareness,risk perception,and information dissemination)and biological infections has been extensively investigated within the framework of multiplex networks.The vast majority of existing multiplex network spreading models typically resort to heterogeneous mean-field approximation and microscopic Markov chain approaches.Such approaches usually manifest richer dynamical properties on multiplex networks than those on simplex networks;however,they fall short of a subtle analysis of the variations in connections between nodes of the network and fail to account for the adaptive behavioral changes among individuals in response to epidemic outbreaks.To transcend these limitations,in this paper we develop a highly integrated effective degree approach to modeling epidemic and awareness spreading processes on multiplex networks coupled with awareness-dependent adaptive rewiring.This approach keeps track of the number of nearest neighbors in each state of an individual;consequently,it allows for the integration of changes in local contacts into the multiplex network model.We derive a formula for the threshold condition of contagion outbreak.Also,we provide a lower bound for the threshold parameter to indicate the effect of adaptive rewiring.The threshold analysis is confirmed by extensive simulations.Our results show that awareness-dependent link rewiring plays an important role in enhancing the transmission threshold as well as lowering the epidemic prevalence.Moreover,it is revealed that intensified awareness diffusion in conjunction with enhanced link rewiring makes a greater contribution to disease prevention and control.In addition,the critical phenomenon is observed in the dependence of the epidemic threshold on the awareness diffusion rate,supporting the metacritical point previously reported in literature.This work may shed light on understanding of the interplay between epidemic dynamics and social contagion on adaptive networks.展开更多
In this paper,an eco-epidemiological model with Beddington-DeAngelis functional response and a time delay representing the gestation period of the predator is studied.By means of Lyapunov functionals and Laselle’s i...In this paper,an eco-epidemiological model with Beddington-DeAngelis functional response and a time delay representing the gestation period of the predator is studied.By means of Lyapunov functionals and Laselle’s invariance principle,sufficient conditions are obtained for the global stability of the interior equilibrium and the disease-free equilibrium of the system,respectively.展开更多
Quorum sensing (QS) refers to the cell communication through signaling molecules that regulate many important biological functions of bacteria by monitoring their population density. Although a wide spectrum of studie...Quorum sensing (QS) refers to the cell communication through signaling molecules that regulate many important biological functions of bacteria by monitoring their population density. Although a wide spectrum of studies on the QS system mechanisms have been carried out in experiments, mathematical modeling to explore the QS system has become a powerful approach as well. In this paper, we review the research progress of network modeling in bacterial QS to capture the system's underlying mechanisms. There are four types of QS system models for bacteria: the Gram-negative QS system model, the Gram-positive QS system model, the model for both Gram-negative and Gram-positive QS system, and the synthetic QS system model. These QS system models are mostly described by the ordinary differential equations (ODE) or partial differential equations (PDE) to study the changes of signaling molecule dynamics in time and space and the cell population density variations. Besides the deterministic simulations, the stochastic modeling approaches have also been introduced to discuss the noise effects on kinetics in QS systems. Taken together, these current modeling efforts advance our understanding of the QS system by providing systematic and quantitative dynamics description, which can hardly be obtained in experiments.展开更多
Foot-and-mouth disease(FMD)is an acute,highly infectious and pathogenic animal disease.In recent years,with the rapid development of the swine breeding industry in China,pig farms have shown a trend of larger-scale de...Foot-and-mouth disease(FMD)is an acute,highly infectious and pathogenic animal disease.In recent years,with the rapid development of the swine breeding industry in China,pig farms have shown a trend of larger-scale development.Large-scale pig farms employ standardized management,a high level of automation,and a strict_system.However,these farms have a large trading volume,and increased transmission intensity of FMD is noted inside the farm.At present,the main control measure against FMD is pig vaccination.However,a standard for immunization procedures is not available,and currently adopted immunization procedures have not been effectively and systematically evaluated.Taking a typical large-scale pig farm in China as the research subject and considering the breeding pattern,piggery structure,age structure and immunization procedures,an individual-based state probability model is established to evaluate the effectiveness of the immune procedure.Based on numerical simulation,it is concluded that the optimal immunization program involves primary immunization at 40 days of age and secondary immunization at 80 days of age for commercial pigs.Breeding boars and breeding sows are immunized 4 times a year,and reserve pigs are immunized at 169 and 259 days of age.According to the theoretical analysis,the average control reproduction number of individuals under the optimal immunization procedure in the farm is 0.4927.In the absence of immunization,the average is 1.7498,indicating that the epidemic cannot be controlled without immunization procedures.展开更多
The dissemination of cattle brucellosis in Zhejiang province of China can be attributed to the transport of cattle between cities within the province. In this paper,an n-patch dynamical model is proposed to study the ...The dissemination of cattle brucellosis in Zhejiang province of China can be attributed to the transport of cattle between cities within the province. In this paper,an n-patch dynamical model is proposed to study the effect of cattle dispersal on brucellosis spread. Theoretically,we analyze the dynamical behavior of the muti-patch model. For the 2-patch submodel,sensitivity analyses of the basic reproduction number R0 and the number of the infectious cattle in term of model parameters are carried out. By numerical analysis,it is obtained that the dispersal of susceptible cattle between patches and the centralization of infected cattle to the large scale patch can alleviate the epidemic and are in favor of the control of disease in the whole region.展开更多
In this paper, we propose four new classes of structured tensors: QDB(QDB_0)-tensors and SQDB(SQDB_0)-tensors, and prove that even order symmetric QDB-tensors and SQDB-tensors are positive definite, even order symmetr...In this paper, we propose four new classes of structured tensors: QDB(QDB_0)-tensors and SQDB(SQDB_0)-tensors, and prove that even order symmetric QDB-tensors and SQDB-tensors are positive definite, even order symmetric QDB_0-tensors and SQDB_0-tensors are positive semi-definite.展开更多
In this paper,we generalize the growing network model with preferential attachment for new links to simultaneously include aging and initial attractiveness of nodes.The network evolves with the addition of a new node ...In this paper,we generalize the growing network model with preferential attachment for new links to simultaneously include aging and initial attractiveness of nodes.The network evolves with the addition of a new node per unit time,and each new node has m new links that with probability Π_(i) are connected to nodes i already present in the network.In our model,the preferential attachment probability Π_(i) is proportional not only to k_(i)+A,the sum of the old node i's degree ki and its initial attractiveness A,but also to the aging factor τ_(i)^(−α),whereτi is the age of the old node i.That is,Π_(i)∝(k_(i)+A)τ_(i)^(−α).Based on the continuum approximation,we present a mean-field analysis that predicts the degree dynamics of the network structure.We show that depending on the aging parameter α two different network topologies can emerge.For α<1,the network exhibits scaling behavior with a power-law degree distribution P(k)∝k^(−γ) for large k where the scaling exponent γ increases with the aging parameter α and is linearly correlated with the ratio A/m.Moreover,the average degree k(ti,t)at time t for any node i that is added into the network at time ti scales as k(t_(i),t)∝t_(i)^(−β) where 1/β is a linear function of A/m.For α>1,such scaling behavior disappears and the degree distribution is exponential.展开更多
Motivated by the fascinating progresses in the cold atom experiments and theories,especially the artificial gauge field induced spin–orbit coupling of neutral atoms,we present a novel dispersion of neutral atoms carr...Motivated by the fascinating progresses in the cold atom experiments and theories,especially the artificial gauge field induced spin–orbit coupling of neutral atoms,we present a novel dispersion of neutral atoms carrying a non-vanishing magnetic moment in a special gauge field,an external electric field of dark-soliton shaped profile.By means of WKB approximation,we obtain discrete quantized landau-like energy levels,which is instructive for the quantum Hall effect of neutral particles.The observability of the results is also discussed.展开更多
The biexponential distributions of open times are observed in various types of ion channels. In this paper, by discussing a simple channel model, we show that there are two different schemes to understand the biexpone...The biexponential distributions of open times are observed in various types of ion channels. In this paper, by discussing a simple channel model, we show that there are two different schemes to understand the biexponential distribution of open times. One scheme is mathematically strict based on generator matrix theory, while the other one has a clear physical explanation according to an approximation process with numerical simulation of Markovian channel dynamics. Our comparison results suggest that even for biologically complex channels, in addition to carrying out a stochastic simulation, the strict theoretical analysis should be considered to understand the multiple exponential distributions of open times.展开更多
Due to the heterogeneity of contact structure,it is more reasonable to model on networks for epidemics.Because of the stochastic nature of events and the discrete number of individuals,the spread of epidemics is more ...Due to the heterogeneity of contact structure,it is more reasonable to model on networks for epidemics.Because of the stochastic nature of events and the discrete number of individuals,the spread of epidemics is more appropriately viewed as a Markov chain.Therefore,we establish stochastic SIRS models with vaccination on networks to study the mean and variance of the number of susceptible and infected individuals for large-scale populations.Using van Kampen's system-size expansion,we derive a high-dimensional deterministic system which describes the mean behaviour and a Fokker-Planck equation which characterizes the variance around deterministic trajectories.Utilizing the qualitative analysis technique and Lyapunov function,we demonstrate that the disease-free equilibrium of the deterministic system is globally asymptotically stable if the basic reproduction number R_(0)<1;and the endemic equilibrium is globally asymptotically stable if R_(0)>1.Through the analysis of the Fokker-Planck equation,we obtain the asymptotic expression for the variance of the number of susceptible and infected individuals around the endemic equilibrium,which can be approximated by the elements of principal diagonal of the solution of the corresponding Lyapunov equation.Here,the solution of Lyapunov equation is expressed by vectorization operator of matrices and Kronecker product.Finally,numerical simulations illustrate that vaccination can reduce infections and increase fluctuations of the number of infected individuals and show that individuals with greater degree are more easily infected.展开更多
In the early stage of an infectious disease outbreak,public health strategies tend to gravitate towards non-pharmaceutical interventions(NPIs)given the time required to develop targeted treatments and vaccines.One of ...In the early stage of an infectious disease outbreak,public health strategies tend to gravitate towards non-pharmaceutical interventions(NPIs)given the time required to develop targeted treatments and vaccines.One of the most common NPIs is Test-Trace-Isolate(TTI).One of the factors determining the effectiveness of TTI is the ability to identify contacts of infected individuals.In this study,we propose a multi-layer temporal contact network to model transmission dynamics and assess the impact of different TTI implementations,using SARS-CoV-2 as a case study.The model was used to evaluate TTI effectiveness both in containing an outbreak and mitigating the impact of an epidemic.We estimated that a TTI strategy based on home isolation and testing of both primary and secondary contacts can contain outbreaks only when the reproduction number is up to 1.3,at which the epidemic prevention potential is 88.2%(95%CI:87.9%e88.5%).On the other hand,for higher value of the reproduction number,TTI is estimated to noticeably mitigate disease burden but at high social costs(e.g.,over a month in isolation/quarantine per person for reproduction numbers of 1.7 or higher).We estimated that strategies considering quarantine of contacts have a larger epidemic prevention potential than strategies that either avoid tracing contacts or require contacts to be tested before isolation.Combining TTI with other social distancing measures can improve the likelihood of successfully containing an outbreak but the estimated epidemic prevention potential remains lower than 50%for reproduction numbers higher than 2.1.In conclusion,our model-based evaluation highlights the challenges of relying on TTIs to contain an outbreak of a novel pathogen with characteristics similar to SARS-CoV-2,and that the estimated effectiveness of TTI depends on the way contact patterns are modeled,supporting the relevance of obtaining comprehensive data on human social interactions to improve preparedness.展开更多
In this paper, we propose a susceptible-infected-susceptible （SIS） model on complex networks, small-world （WS） networks and scale-free （SF） networks, to study the epidemic spreading behavior with time delay whic...In this paper, we propose a susceptible-infected-susceptible （SIS） model on complex networks, small-world （WS） networks and scale-free （SF） networks, to study the epidemic spreading behavior with time delay which is added into the infected phase. Considering the uniform delay, the basic reproduction number R0 on WS networks and ~ on SF networks are obtained respectively. On WS networks, if R0 〈 1, there is a disease-free equilibrium and it is locally asymptotically stable; if R0 〉 1, there is an epidemic equilibrium and it is locally asymptotically stable. On SF networks, if R0 〈_4 1, there is a disease-free equilibrium; if -R0 〉 1, there is an epidemic equilibrium. Finally, we carry out simulations to verify the conclusions and analyze the effect of the time delay T, the effective rate A, average connectivity 〈k） and the minimum connectivity m on the epidemic spreading.展开更多
Dengue is a mosquito-borne disease that is rampant worldwide,with up to 70%of cases reported to be asymptomatic during epidemics.In this paper,a reaction-diffusion dengue model with asymptomatic carrier transmission i...Dengue is a mosquito-borne disease that is rampant worldwide,with up to 70%of cases reported to be asymptomatic during epidemics.In this paper,a reaction-diffusion dengue model with asymptomatic carrier transmission is investigated.We aim to study the existence,nonexistence and minimum wave speed of traveling wave solutions to the model.The results show that the existence and nonexistence of traveling wave solutions are fully determined by the threshold values,which are,the basic reproduction number R0 and critical wave speed c^(*)>0.Specifically,when R0>1 and the wave speed c≥c^(*),the existence of the traveling wave solution is obtained by using Schauder's fixed point theorem and Lyapunov functional.It is proven that the model has no nontrivial traveling wave solutions for R0≤1 or R0>1 and 0<c<c^(*)by employing comparison principle and limit theory.As a consequence,we conclude that the critical wave speed c^(*)is the minimum wave speed of the model.Finally,numerical simulations are carried out to illustrate the effects of several important parameters on the minimum wave speed.展开更多
The epidemiological characteristics and distributions of two epidemics in Fujian Province of Southeast China were attributed to the complex interactions among variant,host,and non-pharmaceutical interventions(NPIs).Al...The epidemiological characteristics and distributions of two epidemics in Fujian Province of Southeast China were attributed to the complex interactions among variant,host,and non-pharmaceutical interventions(NPIs).All reported cases in the Putian epidemic(September 8–October 2,2021,Delta variant B.1.617.2)and Fuzhou epidemic(October 22–November 18,2022,Omicron variant BA.5.2)were classified by sex,age group,occupation,and location in this study.Using surveillance data from the Fujian Provincial Center for Disease Control and Prevention,we established a virus-oriented SVEIR(Susceptible–Vaccinated–Exposed–Infected–Recovered)model to investigate the dynamic evolution features of these two variants and the effects of NPIs.The optimal simulations were carried out with variants and scenario investigations.The scenario investigations showed that NPIs significantly reduced the transmission risk and infection scales of COVID-19,and that the Omicron variant was more infectious than the Delta variant.Moreover,the dynamic investigations revealed the increasing tendencies from Delta to Omicron,such as the basic reproduction number,infection rate,percentage of high-risk cases,and the growth rate.Decreasing tendencies were also identified,such as the average recovery period,the awareness delay,and the percentage of symptomatic cases.This study highlighted that NPIs played critical roles in successfully containing the two epidemics.Such interventions are strongly recommended to public health policymakers.展开更多
文摘This paper aims to estimate the soil organic carbon （SOC） storage in Northeast of China, identify its balance situation and changing trends under current cropping systems, and finally put forward some strategies to keep the SOC in balance. A biogeochemical model （DNDC） for agro-ecosystem was employed to predict SOC dynamics in agricultural ecosystems at regional scale. Data on climate, soil properties, cropping systems, acreage, and management practices at county scale were collected from various sources and integrated into a GIS database to support the model runs at the regional scale. The model predicted results revealed that （1） Total SOC storage in agricultural lands in Heilongjiang, Jilin and Liaoning provinces in Northeast of China is about 1 243.48 × 10^6 t （0-30cm soil layer）, respectively occupying 58.4, 25.5 and 16.1%; （2） Under the current cultivation systems, SOC is in a situation of net loss with carbon losing at a high rate of 31.22 × 10^6 t a^-1 （respectively 59.3, 25.9 and 14.8% in Heilongjiang, Jilin and Liaoning provinces） and 2.05 t ha^-1 a^-1, the situation is more serious in Heilongjiang and Jilin provinces; and （3） Protective cultivations, such as manuring, returning more residue of crop to the field, adopting no-till, are very useful for the accumulation of SOC in these regions.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences(Nos.KZCX2-YW-Q1-07 and KZCX2-YW-Q1-15)the National Basic Research Program(973 Program)of China(No.2010CB950702)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA05050509)
文摘A number of process-based models have been developed for quantifying carbon(C)sequestration in agro-ecosystems.The DeNitrification-DeComposition(DNDC)model was used to simulate and quantify long-term(1980-2008)soil organic carbon(SOC)dynamics in the important rice-producing province,Jiangsu,China.Changes in SOC storages were estimated from two soil databases differing in spatial resolution:a county database consisting of 68 polygons and a soil patch-based database of 701 polygons for all 3.7 Mha of rice fields in Jiangsu.The simulated SOC storage with the coarse resolution county database ranged between 131.0-320.6 Tg C in 1980 and 170.3-305.1 Tg C in 2008,respectively,while that estimated with the fine resolution database was 201.6 and 216.2 Tg C in 1980 and 2008,respectively.The results modeled with the soil databases differing in spatial resolution indicated that using the soil input data with higher resolution substantially increased the accuracy of the modeled results;and when lacking detailed soil datasets,the DNDC model,parameterized with the most sensitive factor(MSF) method to cope with attribute uncertainty,could still produce acceptable results although with deviations of up to 60% for the case study reported in this paper.
基金supported by the National Natural Science Foundation of China(12001339,61573016,11871316)Shanxi Scholarship Council of China(2015-094)+1 种基金the Natural Science Foundation of Shanxi(201801D121006)the Shanxi Province Science Foundation for Youths(201901D211413).
文摘Foot-and-mouth disease is one of the major contagious zoonotic diseases in the world.It is caused by various species of the genus Aphthovirus of the family Picornavirus,and it always brings a large number of infections and heavy financial losses.The disease has become a major public health concern.In this paper,we propose a nonlocal foot-and-mouth disease model in a spatially heterogeneous environment,which couples virus-to-animals and animals-to-animals transmission pathways,and investigate the dynamics of the disperal.The basic reproduction number R_(0)is defined as the spectral radius of the next generation operator R(x)by a renewal equation.The relationship between R_(0)and a principal eigenvalue of an operator L_(0)is built.Moreover,the proposed system exhibits threshold dynamics in terms of R_(0),in the sense that R_(0)determines whether or not foot-and-mouth disease invades the hosts.Through numerical simulations,we have found that increasing animals'movements is an effective control measure for preventing prevalence of the disease.
基金supported by Shanxi Province Science Foundation for Youths(Grant No.201901D211159)the National Natural Science Foundation of China(Grant Nos.11504214,11874310,and 12090052).
文摘Inositol 1,4,5-trisphosphate receptors(IP_(3)R)-mediated calcium ion(Ca^(2+))release plays a central role in the regulation of cell survival and death.Bcl-2 limits the Ca^(2+)release function of the IP3R through a direct or indirect mechanism.However,the two mechanisms are overwhelmingly complex and not completely understood.Here,we convert the mechanisms into a set of ordinary differential equations.We firstly simulate the time evolution of Ca^(2+)concentration under two different levels of Bcl-2 for the direct and indirect mechanism models and compare them with experimental results available in the literature.Secondly,we employ one-and two-parameter bifurcation analysis to demonstrate that Bcl-2 can suppress Ca^(2+)signal from a global point of view both in the direct and indirect mechanism models.We then use mathematical analysis to clarify that the indirect mechanism is more efficient than the direct mechanism in repressing Ca^(2+)signal.Lastly,we predict that the two mechanisms restrict Ca^(2+)signal synergistically.Together,our study provides theoretical insights into Bcl-2 regulation in IP_(3)R-mediated Ca^(2+)release,which may be instrumental for the successful development of therapies to target Bcl-2 for cancer treatment.
基金the National Natural Science Foundation of China(Grant Nos.11601294 and 61873154),Shanxi Scholarship Council of China(Grant No.2016-011)the Shanxi Province Science Foundation for Youths(Grant Nos.201601D021012,201801D221011,201901D211159,201801D221007 and 201801D221003)the 1331 Engineering Project of Shanxi Province,China.
文摘Over the last few years,the interplay between contagion dynamics of social influences(e.g.,human awareness,risk perception,and information dissemination)and biological infections has been extensively investigated within the framework of multiplex networks.The vast majority of existing multiplex network spreading models typically resort to heterogeneous mean-field approximation and microscopic Markov chain approaches.Such approaches usually manifest richer dynamical properties on multiplex networks than those on simplex networks;however,they fall short of a subtle analysis of the variations in connections between nodes of the network and fail to account for the adaptive behavioral changes among individuals in response to epidemic outbreaks.To transcend these limitations,in this paper we develop a highly integrated effective degree approach to modeling epidemic and awareness spreading processes on multiplex networks coupled with awareness-dependent adaptive rewiring.This approach keeps track of the number of nearest neighbors in each state of an individual;consequently,it allows for the integration of changes in local contacts into the multiplex network model.We derive a formula for the threshold condition of contagion outbreak.Also,we provide a lower bound for the threshold parameter to indicate the effect of adaptive rewiring.The threshold analysis is confirmed by extensive simulations.Our results show that awareness-dependent link rewiring plays an important role in enhancing the transmission threshold as well as lowering the epidemic prevalence.Moreover,it is revealed that intensified awareness diffusion in conjunction with enhanced link rewiring makes a greater contribution to disease prevention and control.In addition,the critical phenomenon is observed in the dependence of the epidemic threshold on the awareness diffusion rate,supporting the metacritical point previously reported in literature.This work may shed light on understanding of the interplay between epidemic dynamics and social contagion on adaptive networks.
基金This work was supported by the National Natural Science Foundation of China(No.11371368)and(No.11871316)。
文摘In this paper,an eco-epidemiological model with Beddington-DeAngelis functional response and a time delay representing the gestation period of the predator is studied.By means of Lyapunov functionals and Laselle’s invariance principle,sufficient conditions are obtained for the global stability of the interior equilibrium and the disease-free equilibrium of the system,respectively.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11704318,11675134,and 11874310)the China Postdoctoral Science Foundation(Grant No.2016M602071).
文摘Quorum sensing (QS) refers to the cell communication through signaling molecules that regulate many important biological functions of bacteria by monitoring their population density. Although a wide spectrum of studies on the QS system mechanisms have been carried out in experiments, mathematical modeling to explore the QS system has become a powerful approach as well. In this paper, we review the research progress of network modeling in bacterial QS to capture the system's underlying mechanisms. There are four types of QS system models for bacteria: the Gram-negative QS system model, the Gram-positive QS system model, the model for both Gram-negative and Gram-positive QS system, and the synthetic QS system model. These QS system models are mostly described by the ordinary differential equations (ODE) or partial differential equations (PDE) to study the changes of signaling molecule dynamics in time and space and the cell population density variations. Besides the deterministic simulations, the stochastic modeling approaches have also been introduced to discuss the noise effects on kinetics in QS systems. Taken together, these current modeling efforts advance our understanding of the QS system by providing systematic and quantitative dynamics description, which can hardly be obtained in experiments.
基金supported by the National Key Research and Development Program of China(2016YFD0501501)the National Natural Science Foundation of China under Grant(11601292,61873154,11801398)+4 种基金Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(20210009)General Youth Fund project in Shanxi Province(201901D211158)the 1331 Engineering Project of Shanxi Province,Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province(2019L0114)Key Projects of Health Commission of Shanxi Province(No.2020XM18)the Key Research and Development Project in Shanxi Province(202003D31011/GZ).
文摘Foot-and-mouth disease(FMD)is an acute,highly infectious and pathogenic animal disease.In recent years,with the rapid development of the swine breeding industry in China,pig farms have shown a trend of larger-scale development.Large-scale pig farms employ standardized management,a high level of automation,and a strict_system.However,these farms have a large trading volume,and increased transmission intensity of FMD is noted inside the farm.At present,the main control measure against FMD is pig vaccination.However,a standard for immunization procedures is not available,and currently adopted immunization procedures have not been effectively and systematically evaluated.Taking a typical large-scale pig farm in China as the research subject and considering the breeding pattern,piggery structure,age structure and immunization procedures,an individual-based state probability model is established to evaluate the effectiveness of the immune procedure.Based on numerical simulation,it is concluded that the optimal immunization program involves primary immunization at 40 days of age and secondary immunization at 80 days of age for commercial pigs.Breeding boars and breeding sows are immunized 4 times a year,and reserve pigs are immunized at 169 and 259 days of age.According to the theoretical analysis,the average control reproduction number of individuals under the optimal immunization procedure in the farm is 0.4927.In the absence of immunization,the average is 1.7498,indicating that the epidemic cannot be controlled without immunization procedures.
基金supported by the National Natural Science Foundation of China under Grant（11331009,11171314,11147015,11301490） the National Youth Natural Science Foundation（11201434）+1 种基金 the Specialized Research Fund for the Doctoral Program of Higher Education（20121420130001） the Research Project Supported by Shanxi Scholarship Council of China（2013-3）
文摘The dissemination of cattle brucellosis in Zhejiang province of China can be attributed to the transport of cattle between cities within the province. In this paper,an n-patch dynamical model is proposed to study the effect of cattle dispersal on brucellosis spread. Theoretically,we analyze the dynamical behavior of the muti-patch model. For the 2-patch submodel,sensitivity analyses of the basic reproduction number R0 and the number of the infectious cattle in term of model parameters are carried out. By numerical analysis,it is obtained that the dispersal of susceptible cattle between patches and the centralization of infected cattle to the large scale patch can alleviate the epidemic and are in favor of the control of disease in the whole region.
基金Supported by the National Natural Science Foundation of China(Grant Nos.61573016 11361074+4 种基金 1150114111601473 11861077)CAS' Light of West China’ ProgramScience and Technology Top-notch Talents Support Project of Education Department of Guizhou Province 154(Grant No.QJHKYZ[2016]066)
文摘In this paper, we propose four new classes of structured tensors: QDB(QDB_0)-tensors and SQDB(SQDB_0)-tensors, and prove that even order symmetric QDB-tensors and SQDB-tensors are positive definite, even order symmetric QDB_0-tensors and SQDB_0-tensors are positive semi-definite.
基金funded by the National Natural Science Foundation of China(Grant No.11601294)the Research Project Supported by Shanxi Scholarship Council of China(Grant No.2021-002)+1 种基金the Shanxi Province Science Foundation(Grant No.20210302123466)the 1331 Engineering Project of Shanxi Province。
文摘In this paper,we generalize the growing network model with preferential attachment for new links to simultaneously include aging and initial attractiveness of nodes.The network evolves with the addition of a new node per unit time,and each new node has m new links that with probability Π_(i) are connected to nodes i already present in the network.In our model,the preferential attachment probability Π_(i) is proportional not only to k_(i)+A,the sum of the old node i's degree ki and its initial attractiveness A,but also to the aging factor τ_(i)^(−α),whereτi is the age of the old node i.That is,Π_(i)∝(k_(i)+A)τ_(i)^(−α).Based on the continuum approximation,we present a mean-field analysis that predicts the degree dynamics of the network structure.We show that depending on the aging parameter α two different network topologies can emerge.For α<1,the network exhibits scaling behavior with a power-law degree distribution P(k)∝k^(−γ) for large k where the scaling exponent γ increases with the aging parameter α and is linearly correlated with the ratio A/m.Moreover,the average degree k(ti,t)at time t for any node i that is added into the network at time ti scales as k(t_(i),t)∝t_(i)^(−β) where 1/β is a linear function of A/m.For α>1,such scaling behavior disappears and the degree distribution is exponential.
基金Project supported by China Scholarship Council,Shanxi Province Natural Science Foundation,China(Grant No.201601D011009)the Enterprise Project(Grant No.01110116100051)+1 种基金Shanxi 1331KSC and 111 Project(Grant No.D18001)the National Natural Science Foundation of China(Grant Nos.11404415 and 61873154)
文摘Motivated by the fascinating progresses in the cold atom experiments and theories,especially the artificial gauge field induced spin–orbit coupling of neutral atoms,we present a novel dispersion of neutral atoms carrying a non-vanishing magnetic moment in a special gauge field,an external electric field of dark-soliton shaped profile.By means of WKB approximation,we obtain discrete quantized landau-like energy levels,which is instructive for the quantum Hall effect of neutral particles.The observability of the results is also discussed.
基金Project supported by the National Natural Science Foundations of China(Grant Nos.11504214,31370830,and 11675134)the 111 Project,China(Grant No.B16029)the China Postdoctoral Science Foundation(Grant No.2016M602071)
文摘The biexponential distributions of open times are observed in various types of ion channels. In this paper, by discussing a simple channel model, we show that there are two different schemes to understand the biexponential distribution of open times. One scheme is mathematically strict based on generator matrix theory, while the other one has a clear physical explanation according to an approximation process with numerical simulation of Markovian channel dynamics. Our comparison results suggest that even for biologically complex channels, in addition to carrying out a stochastic simulation, the strict theoretical analysis should be considered to understand the multiple exponential distributions of open times.
基金supported by National Natural Science Foundation of China(Nos.12371494,12231012,11971279)Shanxi Provincial Key Research and Development Project(No.202202020101010).
文摘Due to the heterogeneity of contact structure,it is more reasonable to model on networks for epidemics.Because of the stochastic nature of events and the discrete number of individuals,the spread of epidemics is more appropriately viewed as a Markov chain.Therefore,we establish stochastic SIRS models with vaccination on networks to study the mean and variance of the number of susceptible and infected individuals for large-scale populations.Using van Kampen's system-size expansion,we derive a high-dimensional deterministic system which describes the mean behaviour and a Fokker-Planck equation which characterizes the variance around deterministic trajectories.Utilizing the qualitative analysis technique and Lyapunov function,we demonstrate that the disease-free equilibrium of the deterministic system is globally asymptotically stable if the basic reproduction number R_(0)<1;and the endemic equilibrium is globally asymptotically stable if R_(0)>1.Through the analysis of the Fokker-Planck equation,we obtain the asymptotic expression for the variance of the number of susceptible and infected individuals around the endemic equilibrium,which can be approximated by the elements of principal diagonal of the solution of the corresponding Lyapunov equation.Here,the solution of Lyapunov equation is expressed by vectorization operator of matrices and Kronecker product.Finally,numerical simulations illustrate that vaccination can reduce infections and increase fluctuations of the number of infected individuals and show that individuals with greater degree are more easily infected.
基金supported by the National Natural Science Foundation of China(No.62373264)the Major Program of National Fund of Philosophy and Social Science of China(No.20&ZD112)the 111 Project under grant agreement B21044.
文摘In the early stage of an infectious disease outbreak,public health strategies tend to gravitate towards non-pharmaceutical interventions(NPIs)given the time required to develop targeted treatments and vaccines.One of the most common NPIs is Test-Trace-Isolate(TTI).One of the factors determining the effectiveness of TTI is the ability to identify contacts of infected individuals.In this study,we propose a multi-layer temporal contact network to model transmission dynamics and assess the impact of different TTI implementations,using SARS-CoV-2 as a case study.The model was used to evaluate TTI effectiveness both in containing an outbreak and mitigating the impact of an epidemic.We estimated that a TTI strategy based on home isolation and testing of both primary and secondary contacts can contain outbreaks only when the reproduction number is up to 1.3,at which the epidemic prevention potential is 88.2%(95%CI:87.9%e88.5%).On the other hand,for higher value of the reproduction number,TTI is estimated to noticeably mitigate disease burden but at high social costs(e.g.,over a month in isolation/quarantine per person for reproduction numbers of 1.7 or higher).We estimated that strategies considering quarantine of contacts have a larger epidemic prevention potential than strategies that either avoid tracing contacts or require contacts to be tested before isolation.Combining TTI with other social distancing measures can improve the likelihood of successfully containing an outbreak but the estimated epidemic prevention potential remains lower than 50%for reproduction numbers higher than 2.1.In conclusion,our model-based evaluation highlights the challenges of relying on TTIs to contain an outbreak of a novel pathogen with characteristics similar to SARS-CoV-2,and that the estimated effectiveness of TTI depends on the way contact patterns are modeled,supporting the relevance of obtaining comprehensive data on human social interactions to improve preparedness.
基金supported by the National Natural Sciences Foundation of China(Nos.11331009,61272095,61175067,61573231,61432011,U1435212,11471197,11401541)Shanxi Scholarship Council of China(2013-014)Shanxi Science and Technology Infrastructure(2015091001-0102)
文摘In this paper, we propose a susceptible-infected-susceptible （SIS） model on complex networks, small-world （WS） networks and scale-free （SF） networks, to study the epidemic spreading behavior with time delay which is added into the infected phase. Considering the uniform delay, the basic reproduction number R0 on WS networks and ~ on SF networks are obtained respectively. On WS networks, if R0 〈 1, there is a disease-free equilibrium and it is locally asymptotically stable; if R0 〉 1, there is an epidemic equilibrium and it is locally asymptotically stable. On SF networks, if R0 〈_4 1, there is a disease-free equilibrium; if -R0 〉 1, there is an epidemic equilibrium. Finally, we carry out simulations to verify the conclusions and analyze the effect of the time delay T, the effective rate A, average connectivity 〈k） and the minimum connectivity m on the epidemic spreading.
基金supported by the National Natural Science Foundation of China(12271317,11871316)。
文摘Dengue is a mosquito-borne disease that is rampant worldwide,with up to 70%of cases reported to be asymptomatic during epidemics.In this paper,a reaction-diffusion dengue model with asymptomatic carrier transmission is investigated.We aim to study the existence,nonexistence and minimum wave speed of traveling wave solutions to the model.The results show that the existence and nonexistence of traveling wave solutions are fully determined by the threshold values,which are,the basic reproduction number R0 and critical wave speed c^(*)>0.Specifically,when R0>1 and the wave speed c≥c^(*),the existence of the traveling wave solution is obtained by using Schauder's fixed point theorem and Lyapunov functional.It is proven that the model has no nontrivial traveling wave solutions for R0≤1 or R0>1 and 0<c<c^(*)by employing comparison principle and limit theory.As a consequence,we conclude that the critical wave speed c^(*)is the minimum wave speed of the model.Finally,numerical simulations are carried out to illustrate the effects of several important parameters on the minimum wave speed.
基金supported by Consultancy Project by the Chinese Academy of Engineering(2022-JB-06)supported by Special Projects of the Central Government Guiding Local Science and Technology Development(2021L3018)+2 种基金supported by the Natural Science Foundation of Fujian ProvinceProvince of China(2021J01621)supported by Fujian Science and Technology Innovation Platform Construction Project(2019Y2001)Health Science and Technology Project of Fujian Province(2020GGB019).
文摘The epidemiological characteristics and distributions of two epidemics in Fujian Province of Southeast China were attributed to the complex interactions among variant,host,and non-pharmaceutical interventions(NPIs).All reported cases in the Putian epidemic(September 8–October 2,2021,Delta variant B.1.617.2)and Fuzhou epidemic(October 22–November 18,2022,Omicron variant BA.5.2)were classified by sex,age group,occupation,and location in this study.Using surveillance data from the Fujian Provincial Center for Disease Control and Prevention,we established a virus-oriented SVEIR(Susceptible–Vaccinated–Exposed–Infected–Recovered)model to investigate the dynamic evolution features of these two variants and the effects of NPIs.The optimal simulations were carried out with variants and scenario investigations.The scenario investigations showed that NPIs significantly reduced the transmission risk and infection scales of COVID-19,and that the Omicron variant was more infectious than the Delta variant.Moreover,the dynamic investigations revealed the increasing tendencies from Delta to Omicron,such as the basic reproduction number,infection rate,percentage of high-risk cases,and the growth rate.Decreasing tendencies were also identified,such as the average recovery period,the awareness delay,and the percentage of symptomatic cases.This study highlighted that NPIs played critical roles in successfully containing the two epidemics.Such interventions are strongly recommended to public health policymakers.
