We developed a novel method for real-time monitoring of alteration of the local epithelium vessel/capillary and blood oxygenation spatial pattern in epithelium exploiting a compact fibre sensor system based on spatial...We developed a novel method for real-time monitoring of alteration of the local epithelium vessel/capillary and blood oxygenation spatial pattern in epithelium exploiting a compact fibre sensor system based on spatially and spectrally resolved diffuse reflectance.The method is based on collection of spatially resolved diffuse reflectance Re(λ)by fiber sensors.The spatial resolution is provided as a dependence of Re(λ)on a set of distancesρbetween the source and detector(attenuation curve).It is expected that the new method can reasonably extract the minor spatial deviations of oxygenation and local blood volume fraction-parameters,directly related to the local vessel density and capillary spatial patterns in the epithelium.Light scattering in visible range is naturally taken into account in the proposed method.展开更多
A competitive LotkaVolterra reactiondiffusion system with two delays subject to Neumann boundary conditions is considered. It is well known that the positive con stant steady state of the system is globally asymptotic...A competitive LotkaVolterra reactiondiffusion system with two delays subject to Neumann boundary conditions is considered. It is well known that the positive con stant steady state of the system is globally asymptotically stable if the interspecies competition is weaker than the intraspecies one and is unstable if the interspecies com petition dominates over the intraspecies one. If the latter holds, then we show that Hopf bifurcation can occur as the parameters （delays） in the system cross some critical val ues. In particular, we prove that these Hopf bifurcations are all spatially homogeneous if the diffusive rates are suitably large, which has the same properties as Hopf bifur cation of the corresponding delayed system without diffusion. However, if the diffusive rates are suitably small, then the system generates the spatially nonhomogeneous Hopf bifurcation. Furthermore, we derive conditions for determining the direction of spatially nonhomogeneous Hopf bifurcations and the stability of bifurcating periodic solutions. These results indicate that the diffusion plays an important role for deriving the complex spatiotemporal dynamics.展开更多
Background:The ongoing transmission of the Middle East respiratory syndrome coronavirus(MERS-CoV)in the Middle East and its expansion to other regions are raising concerns of a potential pandemic.An in-depth analysis ...Background:The ongoing transmission of the Middle East respiratory syndrome coronavirus(MERS-CoV)in the Middle East and its expansion to other regions are raising concerns of a potential pandemic.An in-depth analysis about both population and molecular epidemiology of this pathogen is needed.Methods:MERS cases reported globally as of June 2020 were collected mainly from World Health Organization official reports,supplemented by other reliable sources.Determinants for case fatality and spatial diffusion of MERS were assessed with Logistic regressions and Cox proportional hazard models,respectively.Phylogenetic and phylogeographic analyses were performed to examine the evolution and migration history of MERS-CoV.Results:A total of 2562 confirmed MERS cases with 150 case clusters were reported with a case fatality rate of 32.7%(95%Cl:30.9-34.6%).Saudi Arabia accounted for 83.6%of the cases.Age of>65 years old,underlying conditions and>5 days delay in diagnosis were independent risk factors for death.However,a history of animal contact was associated with a higher risk(adjusted OR=297,95%Cl:1」0-7.98)among female cases<65 years but with a lower risk(adjusted OR=0.31,95%Cl:0.18-0.51)among male cases>65 years old.Diffusion of the disease was fastest from its origin in Saudi Arabia to the east,and was primarily driven by the transportation network.The most recent subclade C5.1(since 2013)was associated with non-synonymous mutations and a higher mortality rate.Phylogeographic analyses pointed to Riyadh of Saudi Arabia and Abu Dhabi of the United Arab Emirates as the hubs for both local and international spread of MERS-CoV.Conclusions:MERS-CoV remains primarily locally transmitted in the Middle East,with opportunistic exportation to other continents and a potential of causing transmission clusters of human cases.Animal contact is associated with a higher risk of death,but the association differs by age and sex.Transportation network is the leading driver for the spatial diffusion ofthe disease.These findings how this pathogen spread are helpful for targeting public health surveillance and interventions to control endemics and to prevent a potential pandemic.展开更多
Weibo,China’s largest microblogging platform,has become one of the key information-sharing platforms in modern society.This study examines topic propagation in relation to microblogging from the perspective of the“p...Weibo,China’s largest microblogging platform,has become one of the key information-sharing platforms in modern society.This study examines topic propagation in relation to microblogging from the perspective of the“peer effect.”Using data of hot topics from Weibo,we analyze how the social effect and propagation pathway influence the topic propagation process.We propose a spatial and temporal heterogeneity diffusion model that includes endogenous and exogenous social effects and is based on but different from the Bass diffusion model.We find that most propagation pathways end after a single level of propagation.The endogenous social effect in microblogs primarily influences the inflow of topics.Such endogenous social effect,combined with the multiplier effect,motivates most users to share a microblog topic in a short period of time.The exogenous social effect primarily influences the outflow of topics,and therefore,the microblog topics of a small number of popular users’account for most of the share volume.Our results are robust to potential serial correlation,reflection problem,and potential self-selection due to user status.The findings reveal that group characteristics affect individuals’behaviors and choices in relation to the topic propagation process on microblogging platforms.The use of a spatial and temporal heterogeneity diffusion model and the robustness of the analysis process provide new information for scholars in this field.展开更多
基金The authors gratefully acknowledge funding of the Erlangen Graduate School in Advanced Optical Technologies(SAOT)by the German National Science Foundation(DFG)in the framework of the excellence initiative for support of this study.
文摘We developed a novel method for real-time monitoring of alteration of the local epithelium vessel/capillary and blood oxygenation spatial pattern in epithelium exploiting a compact fibre sensor system based on spatially and spectrally resolved diffuse reflectance.The method is based on collection of spatially resolved diffuse reflectance Re(λ)by fiber sensors.The spatial resolution is provided as a dependence of Re(λ)on a set of distancesρbetween the source and detector(attenuation curve).It is expected that the new method can reasonably extract the minor spatial deviations of oxygenation and local blood volume fraction-parameters,directly related to the local vessel density and capillary spatial patterns in the epithelium.Light scattering in visible range is naturally taken into account in the proposed method.
文摘A competitive LotkaVolterra reactiondiffusion system with two delays subject to Neumann boundary conditions is considered. It is well known that the positive con stant steady state of the system is globally asymptotically stable if the interspecies competition is weaker than the intraspecies one and is unstable if the interspecies com petition dominates over the intraspecies one. If the latter holds, then we show that Hopf bifurcation can occur as the parameters （delays） in the system cross some critical val ues. In particular, we prove that these Hopf bifurcations are all spatially homogeneous if the diffusive rates are suitably large, which has the same properties as Hopf bifur cation of the corresponding delayed system without diffusion. However, if the diffusive rates are suitably small, then the system generates the spatially nonhomogeneous Hopf bifurcation. Furthermore, we derive conditions for determining the direction of spatially nonhomogeneous Hopf bifurcations and the stability of bifurcating periodic solutions. These results indicate that the diffusion plays an important role for deriving the complex spatiotemporal dynamics.
基金supported by China Mega-Project on Infectious Disease Prevention(No.2017ZX10303401,2018ZX10713002,2018ZX10101003 and 2018ZX10201001)National Natural Science Foundation of China(No.81825019),and the National Institutes of Health of United States(R01 All 39761 and R01 AI116770)YY was supported by US National Institutes of Health grants R01 Al 139761 and R56 Al 148284.
文摘Background:The ongoing transmission of the Middle East respiratory syndrome coronavirus(MERS-CoV)in the Middle East and its expansion to other regions are raising concerns of a potential pandemic.An in-depth analysis about both population and molecular epidemiology of this pathogen is needed.Methods:MERS cases reported globally as of June 2020 were collected mainly from World Health Organization official reports,supplemented by other reliable sources.Determinants for case fatality and spatial diffusion of MERS were assessed with Logistic regressions and Cox proportional hazard models,respectively.Phylogenetic and phylogeographic analyses were performed to examine the evolution and migration history of MERS-CoV.Results:A total of 2562 confirmed MERS cases with 150 case clusters were reported with a case fatality rate of 32.7%(95%Cl:30.9-34.6%).Saudi Arabia accounted for 83.6%of the cases.Age of>65 years old,underlying conditions and>5 days delay in diagnosis were independent risk factors for death.However,a history of animal contact was associated with a higher risk(adjusted OR=297,95%Cl:1」0-7.98)among female cases<65 years but with a lower risk(adjusted OR=0.31,95%Cl:0.18-0.51)among male cases>65 years old.Diffusion of the disease was fastest from its origin in Saudi Arabia to the east,and was primarily driven by the transportation network.The most recent subclade C5.1(since 2013)was associated with non-synonymous mutations and a higher mortality rate.Phylogeographic analyses pointed to Riyadh of Saudi Arabia and Abu Dhabi of the United Arab Emirates as the hubs for both local and international spread of MERS-CoV.Conclusions:MERS-CoV remains primarily locally transmitted in the Middle East,with opportunistic exportation to other continents and a potential of causing transmission clusters of human cases.Animal contact is associated with a higher risk of death,but the association differs by age and sex.Transportation network is the leading driver for the spatial diffusion ofthe disease.These findings how this pathogen spread are helpful for targeting public health surveillance and interventions to control endemics and to prevent a potential pandemic.
基金the National Natural Science Foundation of China(Grant Nos.70801066,71071167,7107168,71371200)Sun Yat-sen University Basic Research Funding(Grant Nos.1009028,1109115,16wkjc13)。
文摘Weibo,China’s largest microblogging platform,has become one of the key information-sharing platforms in modern society.This study examines topic propagation in relation to microblogging from the perspective of the“peer effect.”Using data of hot topics from Weibo,we analyze how the social effect and propagation pathway influence the topic propagation process.We propose a spatial and temporal heterogeneity diffusion model that includes endogenous and exogenous social effects and is based on but different from the Bass diffusion model.We find that most propagation pathways end after a single level of propagation.The endogenous social effect in microblogs primarily influences the inflow of topics.Such endogenous social effect,combined with the multiplier effect,motivates most users to share a microblog topic in a short period of time.The exogenous social effect primarily influences the outflow of topics,and therefore,the microblog topics of a small number of popular users’account for most of the share volume.Our results are robust to potential serial correlation,reflection problem,and potential self-selection due to user status.The findings reveal that group characteristics affect individuals’behaviors and choices in relation to the topic propagation process on microblogging platforms.The use of a spatial and temporal heterogeneity diffusion model and the robustness of the analysis process provide new information for scholars in this field.
