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Title:Vpliv topoloških lastnosti kompleksnih mrež in dinamičnih lastnosti sklopljenih celičnih oscilatorjev na kolektivno dinamiko
Authors:ID Markovič, Rene (Author)
ID Marhl, Marko (Mentor) More about this mentor... New window
ID Gosak, Marko (Comentor)
Files:.pdf DOK_Markovic_Rene_2015.pdf (13,27 MB)
MD5: 78ECD635DD459EB48ABFF79C90BD61CE
 
Language:Slovenian
Work type:Doctoral dissertation
Typology:2.08 - Doctoral Dissertation
Organization:FNM - Faculty of Natural Sciences and Mathematics
Abstract:Doktorska disertacija zajema raziskave na področju kolektivne dinamike mrežno sklopljenih oscilatorjev. Razdeljena je na dva dela. V prvem delu analiziramo, kako dinamične lastnosti oscilatorjev in struktura mreže sovisno vplivata na kolektivno dinamiko. Pokažemo, da je kolektivna dinamika fleksibilnih oscilatorjev najbolje koordinirana, ko so oscilatorji povezani v primeru široko skalno mrežo. Oscilatorji z močno disipativno dinamiko, ki implicira rigidnost, pa dosežejo najvišjo raven sinhronizacije v skalno neodvisnih mrežah. Pojav analitično razložimo in rezultate ponazorimo z različnimi matematičnimi modeli, ki vključujejo tako zvezne kakor tudi diskretne oscilatorje, ter izkazujejo različne stopnje dinamične kompleksnosti. Pri analizi kolektivne dinamike upoštevamo tudi hitrost širjenja signalov med vozlišči v mreži. Ugotovimo, da obstaja tako optimalna mrežna topologija kakor tudi optimalna hitrost širjenja signalov med vozlišči mreže, pri kateri je raven kolektivne sinhronizacije najvišja. Ugotovitve in metodologijo iz naših teoretičnih študij v drugem delu disertacije apliciramo na sistem povezanih celic beta v Langerhansovih otočkih trebušne slinavke miši, ki predstavlja z vidika fiziologije metabolnih procesov izredno pomemben predmet preučevanja. Mrežno povezane celice beta, katerih poglavitna naloga je izločanje inzulina in s tem uravnavanje koncentracije glukoze v krvi, analiziramo ob podpori eksperimentalnih podatkov, izmerjenih pri različnih koncentracijah glukoze. Naši rezultati kažejo, da se celice beta povezujejo v lokalne funkcionalne skupnosti. Njihova segregiranost pa se v splošnem manjša z naraščajočo koncentracijo glukoze. S postopnim povečevanjem koncentracije glukoze postanejo v otočku tudi vse bolj izražene lastnosti široko skalnih mrež malega sveta. S tem rezultati doktorske disertacije prispevajo k razlagi fiziološkega pomena učinkovitost mrežne povezanosti celic beta in nakazujejo možnosti patoloških sprememb, ki so posledica sprememb v medcelični komunikaciji.
Keywords:kompleksne mreže, funkcionalne mreže, topološke lastnosti, dinamika, sklopljeni oscilatorji, sinhronizacija, disipativnost, fleksibilnost
Place of publishing:[Maribor
Publisher:R. Markovič]
Year of publishing:2015
PID:20.500.12556/DKUM-47041 New window
UDC:530.182:517.17(043.3)
COBISS.SI-ID:21140488 New window
NUK URN:URN:SI:UM:DK:DLJV1PDV
Publication date in DKUM:16.02.2015
Views:2668
Downloads:343
Metadata:XML DC-XML DC-RDF
Categories:FNM
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Secondary language

Language:English
Title:The influence of topological features of complex networks and dynamical properties of coupled cellular oscillators on collective dynamics
Abstract:This doctor thesis is both theoretical and applicative. In the theoretical part of the thesis, we examine how the interplay of dynamical features of oscillators and structural properties of complex networks affect the collective behavior of the system. We show, that weakly dissipative and flexible oscillators synchronize best in a broad scale network topology, whereas on the other hand strongly dissipative and rigid oscillators exhibit maximal synchronization in a scale-free network topology. We provide an analytical explanation for this phenomenon and validate it by implementing various continuous as well as discrete mathematical models that exhibit different levels of dynamical complexity. In the continuation, we additionally investigate how speed of signal transmission in the network affects the collective dynamic of the system. Our results show that besides an optimal network topology, also an optimal information transmission speed exists, at which the system reaches the highest degree of global synchronization. In the second part we apply the findings and the methodology from our theoretical studies to the examination of the collective pancreatic beta cell activity in the islets of Langerhans, which represents the main mechanism for the regulation of blood glucose homeostasis by the secretion of the hormone insulin. We show that the beta cells dynamics is not synchronized on the global scale of the whole islets. Instead, the cells form local clusters of synchronized activity which tend to get less segregated under higher stimulatory glucose concentrations. Furthermore, higher glucose concentrations also lead to the presence of broad scale small world connectivity patterns in the functional beta cell network. The main findings thereby shed light on the physiology and collective behavior of the islets of Langerhans and point out the possibilities of pathological changes associated with changes in the intercellular communication pathways.
Keywords:complex networks, functional networks, topological features, dynamics, stability analysis, coupled oscillators, synchronization, dissipation, flexibility


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