When an emerging acute infectious disease occurs, travel restrictions, one-way or two-way, are of... more When an emerging acute infectious disease occurs, travel restrictions, one-way or two-way, are often taken to prevent its global spread. In order to investigate the impact of two-way travel restrictions in the global spread of infectious diseases, this paper defines a risk indicator according to the relative infection density. Based on this risk indicator and an intervention time on two-way travel restrictions, we define an adaptive metapopulation network. Then a susceptible-infectious-removed (SIR) metapopulation model on this network is proposed. The mathematical analysis shows that the basic reproduction number is independent of human mobility. Furthermore, this essay compares the effects of one-way travel restrictions and two-way travel restrictions on the global spread of infectious diseases. It is shown that the adaptive metapopulation network under two-way travel restrictions can effectively suppress the global spread of infectious diseases. We also obtain a threshold of risk indicator to prevent the global spread of infectious diseases by simulations. The earlier the intervention time on two-way travel restriction is, the better to curb the global spread of the disease. Even if two-way travel restrictions are not implemented, controlling the mobility of infectious persons would help prevent the global spread of the disease. This work will throw lights on the prevention and control of the globally spreading of an emerging infectious disease. INDEX TERMS Emerging infectious diseases, travel restrictions, adaptive metapopulation network, risk indicator.
The demography and infection age play an important role in the spread of slowly progressive disea... more The demography and infection age play an important role in the spread of slowly progressive diseases. To investigate their effects on the disease spreading, we propose a pairwise epidemic model with infection age and demography on dynamic networks. The basic reproduction number of this model is derived. It is proved that there is a disease-free equilibrium which is globally asymptotically stable if the basic reproduction number is less that unity. Besides, sensitivity analysis is performed and shows that increasing the variance in recovery time and decreasing the variance in infection time can effectively control the diseases. The complex interaction between the death rate and equilibrium prevalence suggests that it is imperative to correctly estimate the parameters of demography in order to assess the disease transmission dynamics accurately. Moreover, numerical simulations show that the endemic equilibrium is globally asymptotically stable.
and herbivore outbreak, we present a mathematical model to describe the interaction of them. It w... more and herbivore outbreak, we present a mathematical model to describe the interaction of them. It was found that time delay plays dual effects in the persistence of herbivore populations: (i) large value of time delay may be associated with small density of herbivore populations, and thus causes the populations to run a higher risk of extinction; (ii) moderate value of time delay is beneficial for maintaining herbivore density in a determined range which may promote the persistence of herbivore populations. Additionally, we revealed that interaction of time delay and space promotes the growth of average density of herbivore populations during their outbreak period which implied that time delay may drive the resilience of herbivore populations. Our findings highlight the close relationship between inducible defenses of plants and herbivore outbreak.
Experimental measurements and theoretical analysis of giant magnetoresistive (GMR) thermal magnet... more Experimental measurements and theoretical analysis of giant magnetoresistive (GMR) thermal magnetization fluctuation noise are presented. A new form of tensor damping, characteristic of the anisotropic thin-film geometry, is utilized. Rationalization and experimental confirmation for this expanded form are given as well. In general, this noise is-inversely proportional to the sensor volume and, at frequencies less than the sensor ferromagnetic resonance
The method of predicting BP neural networks is used for SARS epidemic to improve the existing com... more The method of predicting BP neural networks is used for SARS epidemic to improve the existing computational methods, and better accuracy of prediction is achieved. A suitable momentum term is added to BP algorithm to accelerate the convergence speed. An online prediction strategy is applied to monitor the training and predicting process. We have achieved a series of predicting results
Proceedings of The National Academy of Sciences, 2008
Developmental dyslexia is a neurobiologically based disorder that affects Ϸ5-17% of school childr... more Developmental dyslexia is a neurobiologically based disorder that affects Ϸ5-17% of school children and is characterized by a severe impairment in reading skill acquisition. For readers of alphabetic (e.g., English) languages, recent neuroimaging studies have demonstrated that dyslexia is associated with weak reading-related activity in left temporoparietal and occipitotemporal regions, and this activity difference may reflect reductions in gray matter volume in these areas. Here, we find different structural and functional abnormalities in dyslexic readers of Chinese, a nonalphabetic language. Compared with normally developing controls, children with impaired reading in logographic Chinese exhibited reduced gray matter volume in a left middle frontal gyrus region previously shown to be important for Chinese reading and writing. Using functional MRI to study language-related activation of cortical regions in dyslexics, we found reduced activation in this same left middle frontal gyrus region in Chinese dyslexics versus controls, and there was a significant correlation between gray matter volume and activation in the language task in this same area. By contrast, Chinese dyslexics did not show functional or structural (i.e., volumetric gray matter) differences from normal subjects in the more posterior brain systems that have been shown to be abnormal in alphabetic-language dyslexics. The results suggest that the structural and functional basis for dyslexia varies between alphabetic and nonalphabetic languages.
In this paper, we studied the global dynamics of a SEIR epidemic model in which the latent and im... more In this paper, we studied the global dynamics of a SEIR epidemic model in which the latent and immune state were infective. The basic reproductive rate, R0, is derived. If R0⩽1, the disease-free equilibrium is globally stable and the disease always dies out. If R0>1, there exists a unique endemic equilibrium which is locally stable. Furthermore, we proved the global
Filamentation formed by self-focusing of intense laser pulses propagating in air is investigated.... more Filamentation formed by self-focusing of intense laser pulses propagating in air is investigated. It is found that the position of filamentation can be controlled continuously by changing the laser power and divergence angle of the laser beam. An analytical model for the process is given.
Dairy cattle brucellosis is a chronic bacterial disease, which is caused by Brucella abortus and ... more Dairy cattle brucellosis is a chronic bacterial disease, which is caused by Brucella abortus and mainly characterized by abortion in dairy cattle. With the rapid development of breeding industry of milk cows in China, the infectious cases of dairy cattle brucellosis show an increasing trend. Particularly in Jilin province, the annual number of the positive cases of dairy cattle was only 3 cows in 1987, and went up to 168 cows in 2005. Based on the situation of the brucellosis infection in Jilin province, we propose an Susceptible-Exposed-Infected-Virus (SEIV) dynamical model with outside transferred amount to describe the transmission of brucellosis amongst dairy cattle in this paper. We calculate the basic reproduction number R0 and prove that the equilibria are globally stable. Moreover, using the real data of nearly 20 years in Jilin province, we estimate the parameter values in the system. As a result, we can predict the number of infections as time increases. According to the p...
The vast majority of models for spatial dynamics of natural populations assume a homogeneous phys... more The vast majority of models for spatial dynamics of natural populations assume a homogeneous physical environment. However, in practice, dispersing organisms may encounter landscape features that significantly inhibit their movement. And spatial patterns are ubiquitous in nature, which can modify the temporal dynamics and stability properties of population densities at a range of spatial scales. Thus, in this paper, a predator-prey system with Michaelis-Menten-type functional response and self- and cross-diffusion is investigated. Based on the mathematical analysis, we obtain the condition of the emergence of spatial patterns through diffusion instability, i.e., Turing pattern. A series of numerical simulations reveal that the typical dynamics of population density variation is the formation of isolated groups, i.e., stripe-like or spotted or coexistence of both. The obtained results show that the interaction of self-diffusion and cross-diffusion plays an important role on the patte...
Spatial epidemiology is the study of spatial variation in disease risk or incidence, including th... more Spatial epidemiology is the study of spatial variation in disease risk or incidence, including the spatial patterns of the population. Thus, an epidemic model with spatial structure based on the cellular automata method, which is different from deterministic and probabilistic CA models, is investigated. The construction of the cellular automata is based on the work of Bussemaker et al. [Phys. Rev. Lett.78, 5018–5021 (1997)]. For the appropriately chosen parameters, Turing pattern formation can emerge from a randomly perturbed uniform state, which is shown by numerical simulations. The results obtained confirm that diffusion can form the disease being in high density and the population being more stable.
We analyze a spatial susceptible-infected epidemic model using cellular automata and investigate ... more We analyze a spatial susceptible-infected epidemic model using cellular automata and investigate the relations between the power-law distribution of patch sizes and the regime of invasion. The obtained results show that, when the invasion is in the form of coexistence of stable target and spiral wave, power-law will emerge, which may provide a new insight into the control of disease.
In this paper a pulse vaccination SIR model with periodic infection rate β(t) is studied. The bas... more In this paper a pulse vaccination SIR model with periodic infection rate β(t) is studied. The basic reproductive number R0 is defined. The dynamical behavior of the model is analyzed. It is proved that the infection-free periodic solution is globally stable if R0 < 1. The infection-free periodic solution is unstable and the disease will uniform persistence when R0 > 1. We use standard bifurcation theory to show the existence of the positive periodic solution when R0 → 1+. Numerical simulation can give suggestion, the system has a unique positive periodic, and it is globally stable when R0 > 1.
A system of impulsive differential equations describing predator-prey dynamics with impulsive eff... more A system of impulsive differential equations describing predator-prey dynamics with impulsive effect is proposed and analyzed with the assumption that a transmissible disease is spreading among the prey species only. At first, the ''semi-trivial'' periodic solution (S(t), 0, 0) is given. After that, the existence of ''infection-free'' periodic solution (S(t), 0, P(t)) and the ''predator-free'' periodic solution have been obtained via bifurcation.
Spatial patterns have influence on modifying the temporal dynamics and stability properties of po... more Spatial patterns have influence on modifying the temporal dynamics and stability properties of population densities at a range of spatial scales. Thus, in this paper, we have considered a predator-prey model taking into account both diffusion and migration. We present a theoretical analysis of the condition of emerging spatial pattern. The results of numerical simulations reveal that the migration has marked effect on the pattern formation of the population, i.e. changing Turing pattern to be traveling pattern. The obtained results show that the modeling by both migrations and diffusion can account for the dynamic complexity of ecosystems.
How to detect and alleviate intelligent worms with the characteristic of both slow scanning rate ... more How to detect and alleviate intelligent worms with the characteristic of both slow scanning rate and high vulnerability density? Here, we present a scheme to solve the problem. Different from previous schemes, which set a limit on instantaneous scanning rate against each host, the scheme considered in this paper counts the number of unique IP addresses contacted by all hosts of a subnet over a period and sets a threshold to determine whether the subnet is suspicious. Specially, we consider the similarity of information required by users belonging to the same subnet. The result shows that our scheme is effective against slow scanning worms and worms with high vulnerability density.
When an emerging acute infectious disease occurs, travel restrictions, one-way or two-way, are of... more When an emerging acute infectious disease occurs, travel restrictions, one-way or two-way, are often taken to prevent its global spread. In order to investigate the impact of two-way travel restrictions in the global spread of infectious diseases, this paper defines a risk indicator according to the relative infection density. Based on this risk indicator and an intervention time on two-way travel restrictions, we define an adaptive metapopulation network. Then a susceptible-infectious-removed (SIR) metapopulation model on this network is proposed. The mathematical analysis shows that the basic reproduction number is independent of human mobility. Furthermore, this essay compares the effects of one-way travel restrictions and two-way travel restrictions on the global spread of infectious diseases. It is shown that the adaptive metapopulation network under two-way travel restrictions can effectively suppress the global spread of infectious diseases. We also obtain a threshold of risk indicator to prevent the global spread of infectious diseases by simulations. The earlier the intervention time on two-way travel restriction is, the better to curb the global spread of the disease. Even if two-way travel restrictions are not implemented, controlling the mobility of infectious persons would help prevent the global spread of the disease. This work will throw lights on the prevention and control of the globally spreading of an emerging infectious disease. INDEX TERMS Emerging infectious diseases, travel restrictions, adaptive metapopulation network, risk indicator.
The demography and infection age play an important role in the spread of slowly progressive disea... more The demography and infection age play an important role in the spread of slowly progressive diseases. To investigate their effects on the disease spreading, we propose a pairwise epidemic model with infection age and demography on dynamic networks. The basic reproduction number of this model is derived. It is proved that there is a disease-free equilibrium which is globally asymptotically stable if the basic reproduction number is less that unity. Besides, sensitivity analysis is performed and shows that increasing the variance in recovery time and decreasing the variance in infection time can effectively control the diseases. The complex interaction between the death rate and equilibrium prevalence suggests that it is imperative to correctly estimate the parameters of demography in order to assess the disease transmission dynamics accurately. Moreover, numerical simulations show that the endemic equilibrium is globally asymptotically stable.
and herbivore outbreak, we present a mathematical model to describe the interaction of them. It w... more and herbivore outbreak, we present a mathematical model to describe the interaction of them. It was found that time delay plays dual effects in the persistence of herbivore populations: (i) large value of time delay may be associated with small density of herbivore populations, and thus causes the populations to run a higher risk of extinction; (ii) moderate value of time delay is beneficial for maintaining herbivore density in a determined range which may promote the persistence of herbivore populations. Additionally, we revealed that interaction of time delay and space promotes the growth of average density of herbivore populations during their outbreak period which implied that time delay may drive the resilience of herbivore populations. Our findings highlight the close relationship between inducible defenses of plants and herbivore outbreak.
Experimental measurements and theoretical analysis of giant magnetoresistive (GMR) thermal magnet... more Experimental measurements and theoretical analysis of giant magnetoresistive (GMR) thermal magnetization fluctuation noise are presented. A new form of tensor damping, characteristic of the anisotropic thin-film geometry, is utilized. Rationalization and experimental confirmation for this expanded form are given as well. In general, this noise is-inversely proportional to the sensor volume and, at frequencies less than the sensor ferromagnetic resonance
The method of predicting BP neural networks is used for SARS epidemic to improve the existing com... more The method of predicting BP neural networks is used for SARS epidemic to improve the existing computational methods, and better accuracy of prediction is achieved. A suitable momentum term is added to BP algorithm to accelerate the convergence speed. An online prediction strategy is applied to monitor the training and predicting process. We have achieved a series of predicting results
Proceedings of The National Academy of Sciences, 2008
Developmental dyslexia is a neurobiologically based disorder that affects Ϸ5-17% of school childr... more Developmental dyslexia is a neurobiologically based disorder that affects Ϸ5-17% of school children and is characterized by a severe impairment in reading skill acquisition. For readers of alphabetic (e.g., English) languages, recent neuroimaging studies have demonstrated that dyslexia is associated with weak reading-related activity in left temporoparietal and occipitotemporal regions, and this activity difference may reflect reductions in gray matter volume in these areas. Here, we find different structural and functional abnormalities in dyslexic readers of Chinese, a nonalphabetic language. Compared with normally developing controls, children with impaired reading in logographic Chinese exhibited reduced gray matter volume in a left middle frontal gyrus region previously shown to be important for Chinese reading and writing. Using functional MRI to study language-related activation of cortical regions in dyslexics, we found reduced activation in this same left middle frontal gyrus region in Chinese dyslexics versus controls, and there was a significant correlation between gray matter volume and activation in the language task in this same area. By contrast, Chinese dyslexics did not show functional or structural (i.e., volumetric gray matter) differences from normal subjects in the more posterior brain systems that have been shown to be abnormal in alphabetic-language dyslexics. The results suggest that the structural and functional basis for dyslexia varies between alphabetic and nonalphabetic languages.
In this paper, we studied the global dynamics of a SEIR epidemic model in which the latent and im... more In this paper, we studied the global dynamics of a SEIR epidemic model in which the latent and immune state were infective. The basic reproductive rate, R0, is derived. If R0⩽1, the disease-free equilibrium is globally stable and the disease always dies out. If R0>1, there exists a unique endemic equilibrium which is locally stable. Furthermore, we proved the global
Filamentation formed by self-focusing of intense laser pulses propagating in air is investigated.... more Filamentation formed by self-focusing of intense laser pulses propagating in air is investigated. It is found that the position of filamentation can be controlled continuously by changing the laser power and divergence angle of the laser beam. An analytical model for the process is given.
Dairy cattle brucellosis is a chronic bacterial disease, which is caused by Brucella abortus and ... more Dairy cattle brucellosis is a chronic bacterial disease, which is caused by Brucella abortus and mainly characterized by abortion in dairy cattle. With the rapid development of breeding industry of milk cows in China, the infectious cases of dairy cattle brucellosis show an increasing trend. Particularly in Jilin province, the annual number of the positive cases of dairy cattle was only 3 cows in 1987, and went up to 168 cows in 2005. Based on the situation of the brucellosis infection in Jilin province, we propose an Susceptible-Exposed-Infected-Virus (SEIV) dynamical model with outside transferred amount to describe the transmission of brucellosis amongst dairy cattle in this paper. We calculate the basic reproduction number R0 and prove that the equilibria are globally stable. Moreover, using the real data of nearly 20 years in Jilin province, we estimate the parameter values in the system. As a result, we can predict the number of infections as time increases. According to the p...
The vast majority of models for spatial dynamics of natural populations assume a homogeneous phys... more The vast majority of models for spatial dynamics of natural populations assume a homogeneous physical environment. However, in practice, dispersing organisms may encounter landscape features that significantly inhibit their movement. And spatial patterns are ubiquitous in nature, which can modify the temporal dynamics and stability properties of population densities at a range of spatial scales. Thus, in this paper, a predator-prey system with Michaelis-Menten-type functional response and self- and cross-diffusion is investigated. Based on the mathematical analysis, we obtain the condition of the emergence of spatial patterns through diffusion instability, i.e., Turing pattern. A series of numerical simulations reveal that the typical dynamics of population density variation is the formation of isolated groups, i.e., stripe-like or spotted or coexistence of both. The obtained results show that the interaction of self-diffusion and cross-diffusion plays an important role on the patte...
Spatial epidemiology is the study of spatial variation in disease risk or incidence, including th... more Spatial epidemiology is the study of spatial variation in disease risk or incidence, including the spatial patterns of the population. Thus, an epidemic model with spatial structure based on the cellular automata method, which is different from deterministic and probabilistic CA models, is investigated. The construction of the cellular automata is based on the work of Bussemaker et al. [Phys. Rev. Lett.78, 5018–5021 (1997)]. For the appropriately chosen parameters, Turing pattern formation can emerge from a randomly perturbed uniform state, which is shown by numerical simulations. The results obtained confirm that diffusion can form the disease being in high density and the population being more stable.
We analyze a spatial susceptible-infected epidemic model using cellular automata and investigate ... more We analyze a spatial susceptible-infected epidemic model using cellular automata and investigate the relations between the power-law distribution of patch sizes and the regime of invasion. The obtained results show that, when the invasion is in the form of coexistence of stable target and spiral wave, power-law will emerge, which may provide a new insight into the control of disease.
In this paper a pulse vaccination SIR model with periodic infection rate β(t) is studied. The bas... more In this paper a pulse vaccination SIR model with periodic infection rate β(t) is studied. The basic reproductive number R0 is defined. The dynamical behavior of the model is analyzed. It is proved that the infection-free periodic solution is globally stable if R0 < 1. The infection-free periodic solution is unstable and the disease will uniform persistence when R0 > 1. We use standard bifurcation theory to show the existence of the positive periodic solution when R0 → 1+. Numerical simulation can give suggestion, the system has a unique positive periodic, and it is globally stable when R0 > 1.
A system of impulsive differential equations describing predator-prey dynamics with impulsive eff... more A system of impulsive differential equations describing predator-prey dynamics with impulsive effect is proposed and analyzed with the assumption that a transmissible disease is spreading among the prey species only. At first, the ''semi-trivial'' periodic solution (S(t), 0, 0) is given. After that, the existence of ''infection-free'' periodic solution (S(t), 0, P(t)) and the ''predator-free'' periodic solution have been obtained via bifurcation.
Spatial patterns have influence on modifying the temporal dynamics and stability properties of po... more Spatial patterns have influence on modifying the temporal dynamics and stability properties of population densities at a range of spatial scales. Thus, in this paper, we have considered a predator-prey model taking into account both diffusion and migration. We present a theoretical analysis of the condition of emerging spatial pattern. The results of numerical simulations reveal that the migration has marked effect on the pattern formation of the population, i.e. changing Turing pattern to be traveling pattern. The obtained results show that the modeling by both migrations and diffusion can account for the dynamic complexity of ecosystems.
How to detect and alleviate intelligent worms with the characteristic of both slow scanning rate ... more How to detect and alleviate intelligent worms with the characteristic of both slow scanning rate and high vulnerability density? Here, we present a scheme to solve the problem. Different from previous schemes, which set a limit on instantaneous scanning rate against each host, the scheme considered in this paper counts the number of unique IP addresses contacted by all hosts of a subnet over a period and sets a threshold to determine whether the subnet is suspicious. Specially, we consider the similarity of information required by users belonging to the same subnet. The result shows that our scheme is effective against slow scanning worms and worms with high vulnerability density.
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