The relationship between network structure and dynamics is one of the most extensively investigated problems in the theory of complex systems of recent years. Understanding this relationship is of relevance to a range of disciplines-from neuroscience to geomorphology. A major strategy of investigating this relationship is the quantitative comparison of a representation of network architecture (structural connectivity, SC) with a (network) representation of the dynamics (functional connectivity, FC). Here, we show that one can distinguish two classes of functional connectivity-one based on simultaneous activity (co-activity) of nodes, the other based on sequential activity of nodes. We delineate these two classes in different categories of dynamical processes-excitations, regular and chaotic oscillators-and provide examples for SC/FC correlations of both classes in each of these models. We expand the theoretical view of the SC/FC relationships, with conceptual instances of the SC and the two classes of FC for various application scenarios in geomorphology, ecology, systems biology, neuroscience and socio-ecological systems. Seeing the organisation of dynamical processes in a network either as governed by co-activity or by sequential activity allows us to bring some order in the myriad of observations relating structure and function of complex networks.

• MeSH
• ekologie * MeSH
• ekosystém * MeSH
• mozek MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Due to known information processing capabilities of the brain, neurons are modeled at many different levels. Circuit theory is also often used to describe the function of neurons, especially in complex multi-compartment models, but when used for simple models, there is no subsequent biological justification of used parts. We propose a new single-compartment model of excitatory and inhibitory neuron, the capacitor-switch model of excitatory and inhibitory neuron, as an extension of the existing integrate-and-fire model, preserving the signal properties of more complex multi-compartment models. The correspondence to existing structures in the neuronal cell is then discussed for each part of the model. We demonstrate that a few such inter-connected model units are capable of acting as a chaotic oscillator dependent on fire patterns of the input signal providing a complex deterministic and specific response through the output signal. The well-known necessary conditions for constructing a chaotic oscillator are met for our presented model. The capacitor-switch model provides a biologically-plausible concept of chaotic oscillator based on neuronal cells.

• MeSH
• akční potenciály fyziologie   MeSH
• modely neurologické MeSH
• mozek metabolismus   MeSH
• neurony metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

OBJECTIVES: Resonance tube phonation with tube end in water is a voice therapy method in which the patient phonates through a glass tube, keeping the free end of the tube submerged in water, creating bubbles. The purpose of this experimental study was to determine flow-pressure relationship, flow thresholds between bubble types, and bubble frequency as a function of flow and back volume. METHODS: A flow-driven vocal tract simulator was used for recording the back pressure produced by resonance tubes with inner diameters of 8 and 9 mm submerged at water depths of 0-7 cm. Visual inspection of bubble types through video recording was also performed. RESULTS: The static back pressure was largely determined by the water depth. The narrower tube provided a slightly higher back pressure for a given flow and depth. The amplitude of the pressure oscillations increased with flow and depth. Depending on flow, the bubbles were emitted from the tube in three distinct types with increasing flow: one by one, pairwise, and in a chaotic manner. The bubble frequency was slightly higher for the narrower tube. An increase in back volume led to a decrease in bubble frequency. CONCLUSIONS: This study provides data on the physical properties of resonance tube phonation with the tube end in water. This information will be useful in future research when looking into the possible effects of this type of voice training.

• MeSH
• fonace * MeSH
• hlasový trénink * MeSH
• lidé MeSH
• řečová terapie přístrojové vybavení   MeSH
• tlak MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Tick-borne encephalitis (TBE) is peculiar due to its unstable dynamics with profound inter-annual fluctuations in case numbers - a phenomenon not well understood to date. Possible reasons - apart from variable human contact with TBE foci - include external factors, e.g. climatic forcing, autonomous oscillations of the disease system itself, or a combined action of both. Spectral analysis of TBE data from six regions of central Europe (CE) revealed that the ostensibly chaotic dynamics can be explained in terms of four superposed (quasi-)periodical oscillations: a quasi-biennial, triennial, pentennial, and a decadal cycle. These oscillations exhibit a high degree of regularity and synchrony across CE. Nevertheless, some amplitude and phase variations are responsible for regional differences in incidence patterns. In addition, periodic changes occur in the degree of synchrony in the regions: marked in-phase periods alternate with rather off-phase periods. Such a feature in the disease dynamics implies that it arises as basically diverging self-oscillations of local disease systems which, at intervals, receive synchronizing impulses, such as periodic variations in food availability for key hosts driven by external factors. This makes the disease dynamics synchronized over a large area during peaks in the synchronization signal, shifting to asynchrony in the time in between.

• MeSH
• incidence MeSH
• klíšťata růst a vývoj   MeSH
• klíšťová encefalitida epidemiologie   MeSH
• lidé MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

This contribution brings a deep and detailed study of the dynamical behavior associated with nonlinear oscillator described by a single third-order differential equation with scalar jump nonlinearity. The relative primitive geometry of the vector field allows making an exhaustive numerical analysis of its possible solutions, visualizations of the invariant manifolds, and basins of attraction as well as proving the existence of chaotic motion by using the concept of both Shilnikov theorems. The aim of this paper is also to complete, carry out and link the previous works on simple Newtonian dynamics, and answer the question how individual types of the phenomenon evolve with time via understandable notes.

• MeSH
• teoretické modely * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• Klíčová slova
• Vědy aplikované matematické, Chování chaotické,

• Konspekt
• Statistika
• NLK Obory
• statistika, zdravotnická statistika

Teorie nelineárních dynamických systémů aplikovaná na biologické neuronové sítě, u nichž je prokázáno deterministicky chaotické chování, vysvětluje překvapivým způsobem ukládání a rychlé vybavovaní paměťových stop. Pomocí fázových přechodů a synchronizace oscilací lze interpretovat epileptickou aktivitu jako projev univerzálních vlastností deterministicky chaotických systémů. Modely mozkové aktivity založené na chaotických neuronech lépe vystihují skutečné chování biologických neuronů.

The theory of non-linear dynamic systems applied to biological neurone networks where a determinist chaotic behaviour was proved explains in a surprising way the deposition and rapid recollection of memory traces. By means of phasic transition and synchronization of oscillations it is possible to interpret the epileptic activity as a manifestation of universal properties of determinist chaotic systems. Models of cerebral activity based on chaotic neurones give a better idea of the actual behaviour of biological neurones.

• MeSH
• epilepsie patologie   MeSH
• lidé MeSH
• nelineární dynamika MeSH
• neuronové sítě MeSH
• paměť MeSH
• Check Tag
• lidé MeSH