Apolipoprotein E ε4 accelerates the longitudinal cerebral atrophy in open access series of imaging studies-3 elders without dementia at enrollment

IntroductionEarly studies have reported that APOE is strongly associated with brain atrophy and cognitive decline among healthy elders and Alzheimer’s disease (AD). However, previous research has not directly outlined the modulation of APOE on the trajectory of cerebral atrophy with aging during the conversion from cognitive normal (CN) to dementia (CN2D).MethodsThis study tried to elucidate this issue from a voxel-wise whole-brain perspective based on 416 qualified participants from a longitudinal OASIS-3 neuroimaging cohort. A voxel-wise linear mixed-effects model was applied for detecting cerebrum regions whose nonlinear atrophic trajectories were driven by AD conversion and to elucidate the effect of APOE variants on the cerebral atrophic trajectories during the process.ResultsWe found that CN2D participants had faster quadratically accelerated atrophy in bilateral hippocampi than persistent CN. Moreover, APOE ε4 carriers had faster-accelerated atrophy in the left hippocampus than ε4 noncarriers in both CN2D and persistent CN, and CN2D ε4 carriers an noncarriers presented a faster atrophic speed than CN ε4 carriers. These findings could be replicated in a sub-sample with a tough match in demographic information.DiscussionOur findings filled the gap that APOE ε4 accelerates hippocampal atrophy and the conversion from normal cognition to dementia

A bibliometric and knowledge-map analysis of the glymphatic system from 2012 to 2022

ObjectiveTo explore the development context, research hotspots and frontiers in the glymphatic system (GS) field from 2012 to 2022 by bibliometric analysis.MethodsThe Web of Science Core Collection (WoSCC) database was searched for articles published between 2012 and 2022. Microsoft Excel was used to manage the data. VOSviewer, CiteSpace, GraphPad Prism, the Web of Science, and an online analysis platform for bibliometrics (http://bibliometric.com/) were used to analyze the countries, institutions, journals, and collaboration networks among authors and the types of articles, developmental directions, references, and top keywords of published articles.ResultsA total of 412 articles were retrieved, including 39 countries/regions, 223 research institutes and 171 academic journals. The subject classifications related to the GS were Neuroscience, Clinical Neuroscience and Radiology/Nuclear Medicine/Medical Imaging. The United States has maintained its dominant and most influential position in GS research. Among research institutions and journals, the Univ Rochester and Journal of Cerebral Blood Flow and Metabolism had the highest number of academic articles, respectively. Nedergaard M had the most published article, and Iliff JJ had the most co-citations. The top two keywords with the highest frequency were “glymphatic system” and “cerebrospinal fluid.”ConclusionThis research provides valuable information for the study of the GS. The bibliometric analysis of this area will encourage potential collaborations among researchers, defining its frontiers and directions for development

Contrôle coopératif distribué pour systèmes multi-agents

This dissertation focuses on distributed cooperative control of multi-agent systems. First, the leader-following consensus for multi-agent systems with nonlinear dynamics is investigated. Three consensus algorithms are proposed and some sufficient conditions are obtained for the states of followers converging to the state of virtual leader globally exponentially. Second, the consensus tracking for multi-agent systems with nonlinear dynamics is investigated. Some consensus tracking algorithms are developed, and some sufficient conditions are obtained. Based on these consensus tracking algorithms and sufficient conditions, it is shown that in first-order multi-agent systems all followers can track the virtual leader in finite time, and in second-order multi-agent systems the consensus tracking can be achieved at least globally exponentially. Third, the path planning and motion control of multi-agent formation is studied, where a practical framework is provided. In order to find a collision-free and deadlock-free feasible path for the whole formation, an optimizing algorithm is given to optimize the path generated by A* search algorithm. In order to realize the cohesive motion of a persistent formation in 3-dimensional space, a set of decentralized control laws is designed. Finally, the formation keeping problem is studied. We mainly focus on the closing ranks problem, which deals with the addition of links to a rigid multi-agent formation that is “damaged" by losing one of its agents, in order to recover rigidity. Some graph theoretical results are obtained, and some systematic ’self-repair’ operations are proposed to recover the rigidity in case of agent removalsCette thèse considère principalement trois problèmes dans le domaine du contrôle distribué coopératif des systèmes multi-agents(SMA): le consensus, la navigation en formation et le maintien en formation d’un groupe d’agents lorsqu’un agent disparait. Nous proposons 3 algorithmes pour résoudre le problème du calcul distribué d’un consensus à partir de l’approche leadeur-suiveur dans le contexte SMA à dynamique non-linéaire. La référence est définie comme un leader virtuel dont on n’obtient, localement, que les données de position et de vitesse. Pour résoudre le problème du suivi par consensus pour les SMA à dynamique non-linéaire, nous considérons le suivi par consensus pour SMA de premier ordre. On propose des résultats permettant aux suiveurs de suivre le leadeur virtuel en temps fini en ne considérant que les positions des agents. Ensuite, nous considérons le suivi par consensus de SMA de second. Dans le cas de la planification de trajectoire et la commande du mouvement de la formation multi-agents. L’idée est d’amener la formation, dont la dynamique est supposée être en 3D, d’une configuration initiale vers une configuration finale (trouver un chemin faisable en position et orientation) en maintenant sa forme tout le long du chemin en évitant les obstacles. La stratégie proposée se décompose en 3 étapes. Le problème du Closing-Rank se traduit par la réparation d’une formation rigide multi-agents "endommagée" par la perte de l'un de ses agents. Nous proposons 2 algorithmes d’autoréparation systématique pour récupérer la rigidité en cas de perte d'un agent. Ces réparations s’effectuent de manière décentralisée et distribuée n’utilisant que des informations de voisinag

Decentralized Closing Ranks in 2-dimensional Rigid Multi-agent Formations

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Dynamical Analysis of the Lorenz-84 Atmospheric Circulation Model

The dynamical behaviors of the Lorenz-84 atmospheric circulation model are investigated based on qualitative theory and numerical simulations. The stability and local bifurcation conditions of the Lorenz-84 atmospheric circulation model are obtained. It is also shown that when the bifurcation parameter exceeds a critical value, the Hopf bifurcation occurs in this model. Then, the conditions of the supercritical and subcritical bifurcation are derived through the normal form theory. Finally, the chaotic behavior of the model is also discussed, the bifurcation diagrams and Lyapunov exponents spectrum for the corresponding parameter are obtained, and the parameter interval ranges of limit cycle and chaotic attractor are calculated in further. Especially, a computer-assisted proof of the chaoticity of the model is presented by a topological horseshoe theory

Consensus Tracking for Multi-Agent Systems with Nonlinear Dynamics under Fixed Communication Topologies

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Leaderless consensus for the fractional-order nonlinear multi-agent systems under directed interaction topology

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Fully distributed time-varying formation-containment control for large-scale nonholonomic vehicles with an unknown real leader

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