Patients with mild traumatic brain injury have a diverse clinical presentation,and the underlying pathophysiology remains poorly understood.Magnetic resonance imaging is a non-invasive technique that has been widely u...Patients with mild traumatic brain injury have a diverse clinical presentation,and the underlying pathophysiology remains poorly understood.Magnetic resonance imaging is a non-invasive technique that has been widely utilized to investigate neuro biological markers after mild traumatic brain injury.This approach has emerged as a promising tool for investigating the pathogenesis of mild traumatic brain injury.G raph theory is a quantitative method of analyzing complex networks that has been widely used to study changes in brain structure and function.However,most previous mild traumatic brain injury studies using graph theory have focused on specific populations,with limited exploration of simultaneous abnormalities in structural and functional connectivity.Given that mild traumatic brain injury is the most common type of traumatic brain injury encounte red in clinical practice,further investigation of the patient characteristics and evolution of structural and functional connectivity is critical.In the present study,we explored whether abnormal structural and functional connectivity in the acute phase could serve as indicators of longitudinal changes in imaging data and cognitive function in patients with mild traumatic brain injury.In this longitudinal study,we enrolled 46 patients with mild traumatic brain injury who were assessed within 2 wee ks of injury,as well as 36 healthy controls.Resting-state functional magnetic resonance imaging and diffusion-weighted imaging data were acquired for graph theoretical network analysis.In the acute phase,patients with mild traumatic brain injury demonstrated reduced structural connectivity in the dorsal attention network.More than 3 months of followup data revealed signs of recovery in structural and functional connectivity,as well as cognitive function,in 22 out of the 46 patients.Furthermore,better cognitive function was associated with more efficient networks.Finally,our data indicated that small-worldness in the acute stage could serve as a predictor of longitudinal ch展开更多
As the means for communication of users in different communication networks and network resource sharing, communication network interconnection has been paid great attention to in recent years. The performance analysi...As the means for communication of users in different communication networks and network resource sharing, communication network interconnection has been paid great attention to in recent years. The performance analysis of internetworks is very important in communication network interconnection, for it is the basis for the study of other problems concerned. The main contribution of this paper is a wide and deep study of performance of internetwork, the construction of systematic performance analysis method for arbitrary internetworks, and of queuing model for gateways. In this paper, the performance analysis of internetwork with arbitrary topology is studied for the first time, and a new method - Node Equivalence of Subnetworks (NES) is proposed. The key step of this method is the node equivalence of subnetworks of all kinds, so we first deeply study the node equivalence, and develop two models for node equivalence. Then we study the node equivalence of CSMA/CD and SLOTTED ALOHA systems by using these models. The results show that the NES method is a systematic method which is suitable for performance analysis of any type of internetworks. The proposed equivalence models is usable with good approximation. The queuing model of gateway is first widely studied in this paper. The queuing model for gateways with packet fragmentation and reassembly is studied for the first time and the analysis method, proposed. In the analysis, two modeling tools, Reversed Switched Poisson Process (RSPP) and Switched Determined Process (SDP), are proposed and RSPP/M/1 queue and SDP/D/1 queue, analyzed. A new method-minislot method is proposed and used for the study of SDP/D/1 queue and performance of ATM multiplexer. In this paper, the interdeparture time distribution of ATM network under some input traffic models is studied and the expression, derived. These results can be used for both performance evaluation of ATM network and the performance of ATM networks interconnected with other networks. We also propos展开更多
In this paper, we proposed an algorithm to estimate the reliability of a hybrid computer communication network. A hybrid computer network is a network that consists of wire and wireless sub networks. The proposed algo...In this paper, we proposed an algorithm to estimate the reliability of a hybrid computer communication network. A hybrid computer network is a network that consists of wire and wireless sub networks. The proposed algorithm is built upon using a simulation model due to the complexity of the network topology. We tested the proposed algorithm, and the results show consistency in the reliability estimates.展开更多
Time delay and coupling strength are important factors that affect the synchronization of neural networks.In this study,a modular neural network containing subnetworks of different scales was constructed using the Hod...Time delay and coupling strength are important factors that affect the synchronization of neural networks.In this study,a modular neural network containing subnetworks of different scales was constructed using the Hodgkin–Huxley(HH)neural model;i.e.,a small-scale random network was unidirectionally connected to a large-scale small-world network through chemical synapses.Time delays were found to induce multiple synchronization transitions in the network.An increase in coupling strength also promoted synchronization of the network when the time delay was an integer multiple of the firing period of a single neuron.Considering that time delays at different locations in a modular network may have different effects,we explored the influence of time delays within each subnetwork and between two subnetworks on the synchronization of modular networks.We found that when the subnetworks were well synchronized internally,an increase in the time delay within both subnetworks induced multiple synchronization transitions of their own.In addition,the synchronization state of the small-scale network affected the synchronization of the large-scale network.It was surprising to find that an increase in the time delay between the two subnetworks caused the synchronization factor of the modular network to vary periodically,but it had essentially no effect on the synchronization within the receiving subnetwork.By analyzing the phase difference between the two subnetworks,we found that the mechanism of the periodic variation of the synchronization factor of the modular network was the periodic variation of the phase difference.Finally,the generality of the results was demonstrated by investigating modular networks at different scales.展开更多
The active-subnetwork-extraction theorem and the passive-subnetwork-extraction theorem are derived from one of the author’s previous work. Using them to find the fully symbolic network functions, the multilevel-teari...The active-subnetwork-extraction theorem and the passive-subnetwork-extraction theorem are derived from one of the author’s previous work. Using them to find the fully symbolic network functions, the multilevel-tearing topological analysis for active networks can be substantially simplified so that it can be conducted conveniently on a computer. Using them to find partially symbolic network functions, one finds it possible to extend not only the electrical network that can be analysed on a computer to the order that can be processed by an ordinary numerical analysis program, but also the symbolic subnetwork to the order that can be processed by an ordinary topological analysis program. So far the latter cannot be achieved with the current conventional methods, i. e. the parameter-extraction method and interpolative approach.展开更多
The problem for the solvability of pseudo-tearing subnetwork is one of the essentialinvestigations of network theory.The results presented would be not only mathematical conditionsbut also topological conditions for s...The problem for the solvability of pseudo-tearing subnetwork is one of the essentialinvestigations of network theory.The results presented would be not only mathematical conditionsbut also topological conditions for subnetwork solvability.These conditions are necessary andalmost sufficient.It should guide one intuitively to the design of accessible nodes.展开更多
基金supported by the National Natural Science Foundation of China,Nos.81671671(to JL),61971451(to JL),U22A2034(to XK),62177047(to XK)the National Defense Science and Technology Collaborative Innovation Major Project of Central South University,No.2021gfcx05(to JL)+6 种基金Clinical Research Cen terfor Medical Imaging of Hunan Province,No.2020SK4001(to JL)Key Emergency Project of Pneumonia Epidemic of Novel Coronavirus Infection of Hu nan Province,No.2020SK3006(to JL)Innovative Special Construction Foundation of Hunan Province,No.2019SK2131(to JL)the Science and Technology lnnovation Program of Hunan Province,Nos.2021RC4016(to JL),2021SK53503(to ML)Scientific Research Program of Hunan Commission of Health,No.202209044797(to JL)Central South University Research Program of Advanced Interdisciplinary Studies,No.2023Q YJC020(to XK)the Natural Science Foundation of Hunan Province,No.2022JJ30814(to ML)。
文摘Patients with mild traumatic brain injury have a diverse clinical presentation,and the underlying pathophysiology remains poorly understood.Magnetic resonance imaging is a non-invasive technique that has been widely utilized to investigate neuro biological markers after mild traumatic brain injury.This approach has emerged as a promising tool for investigating the pathogenesis of mild traumatic brain injury.G raph theory is a quantitative method of analyzing complex networks that has been widely used to study changes in brain structure and function.However,most previous mild traumatic brain injury studies using graph theory have focused on specific populations,with limited exploration of simultaneous abnormalities in structural and functional connectivity.Given that mild traumatic brain injury is the most common type of traumatic brain injury encounte red in clinical practice,further investigation of the patient characteristics and evolution of structural and functional connectivity is critical.In the present study,we explored whether abnormal structural and functional connectivity in the acute phase could serve as indicators of longitudinal changes in imaging data and cognitive function in patients with mild traumatic brain injury.In this longitudinal study,we enrolled 46 patients with mild traumatic brain injury who were assessed within 2 wee ks of injury,as well as 36 healthy controls.Resting-state functional magnetic resonance imaging and diffusion-weighted imaging data were acquired for graph theoretical network analysis.In the acute phase,patients with mild traumatic brain injury demonstrated reduced structural connectivity in the dorsal attention network.More than 3 months of followup data revealed signs of recovery in structural and functional connectivity,as well as cognitive function,in 22 out of the 46 patients.Furthermore,better cognitive function was associated with more efficient networks.Finally,our data indicated that small-worldness in the acute stage could serve as a predictor of longitudinal ch
文摘As the means for communication of users in different communication networks and network resource sharing, communication network interconnection has been paid great attention to in recent years. The performance analysis of internetworks is very important in communication network interconnection, for it is the basis for the study of other problems concerned. The main contribution of this paper is a wide and deep study of performance of internetwork, the construction of systematic performance analysis method for arbitrary internetworks, and of queuing model for gateways. In this paper, the performance analysis of internetwork with arbitrary topology is studied for the first time, and a new method - Node Equivalence of Subnetworks (NES) is proposed. The key step of this method is the node equivalence of subnetworks of all kinds, so we first deeply study the node equivalence, and develop two models for node equivalence. Then we study the node equivalence of CSMA/CD and SLOTTED ALOHA systems by using these models. The results show that the NES method is a systematic method which is suitable for performance analysis of any type of internetworks. The proposed equivalence models is usable with good approximation. The queuing model of gateway is first widely studied in this paper. The queuing model for gateways with packet fragmentation and reassembly is studied for the first time and the analysis method, proposed. In the analysis, two modeling tools, Reversed Switched Poisson Process (RSPP) and Switched Determined Process (SDP), are proposed and RSPP/M/1 queue and SDP/D/1 queue, analyzed. A new method-minislot method is proposed and used for the study of SDP/D/1 queue and performance of ATM multiplexer. In this paper, the interdeparture time distribution of ATM network under some input traffic models is studied and the expression, derived. These results can be used for both performance evaluation of ATM network and the performance of ATM networks interconnected with other networks. We also propos
文摘In this paper, we proposed an algorithm to estimate the reliability of a hybrid computer communication network. A hybrid computer network is a network that consists of wire and wireless sub networks. The proposed algorithm is built upon using a simulation model due to the complexity of the network topology. We tested the proposed algorithm, and the results show consistency in the reliability estimates.
基金supported by the National Natural Science Foundation of China(No.12175080)the Fundamental Research Funds for the Central Universities,China(No.CCNU22JC009)。
文摘Time delay and coupling strength are important factors that affect the synchronization of neural networks.In this study,a modular neural network containing subnetworks of different scales was constructed using the Hodgkin–Huxley(HH)neural model;i.e.,a small-scale random network was unidirectionally connected to a large-scale small-world network through chemical synapses.Time delays were found to induce multiple synchronization transitions in the network.An increase in coupling strength also promoted synchronization of the network when the time delay was an integer multiple of the firing period of a single neuron.Considering that time delays at different locations in a modular network may have different effects,we explored the influence of time delays within each subnetwork and between two subnetworks on the synchronization of modular networks.We found that when the subnetworks were well synchronized internally,an increase in the time delay within both subnetworks induced multiple synchronization transitions of their own.In addition,the synchronization state of the small-scale network affected the synchronization of the large-scale network.It was surprising to find that an increase in the time delay between the two subnetworks caused the synchronization factor of the modular network to vary periodically,but it had essentially no effect on the synchronization within the receiving subnetwork.By analyzing the phase difference between the two subnetworks,we found that the mechanism of the periodic variation of the synchronization factor of the modular network was the periodic variation of the phase difference.Finally,the generality of the results was demonstrated by investigating modular networks at different scales.
文摘The active-subnetwork-extraction theorem and the passive-subnetwork-extraction theorem are derived from one of the author’s previous work. Using them to find the fully symbolic network functions, the multilevel-tearing topological analysis for active networks can be substantially simplified so that it can be conducted conveniently on a computer. Using them to find partially symbolic network functions, one finds it possible to extend not only the electrical network that can be analysed on a computer to the order that can be processed by an ordinary numerical analysis program, but also the symbolic subnetwork to the order that can be processed by an ordinary topological analysis program. So far the latter cannot be achieved with the current conventional methods, i. e. the parameter-extraction method and interpolative approach.
基金This project supported by National Natural Science Foundation of China
文摘The problem for the solvability of pseudo-tearing subnetwork is one of the essentialinvestigations of network theory.The results presented would be not only mathematical conditionsbut also topological conditions for subnetwork solvability.These conditions are necessary andalmost sufficient.It should guide one intuitively to the design of accessible nodes.
