University of Maribor

About: University of Maribor is a education organization based out in Maribor, Slovenia. It is known for research contribution in the topics: Population & KEKB. The organization has 3987 authors who have published 13077 publications receiving 258339 citations. The organization is also known as: Univerza v Mariboru.

Different types of bursting calcium oscillations in non-excitable cells

Abstract: In the paper different types of bursting Ca 2+ oscillations are presented. We analyse bursting behaviour in four recent mathematical models for Ca 2+ oscillations in non-excitable cells. Separately, regular, quasi-periodic, and chaotic bursting Ca 2+ oscillations are classified into several subtypes. The classification is based on the dynamics of separated fast and slow subsystems, the so-called fast–slow burster analysis. For regular bursting Ca 2+ oscillations two types of bursting are specified: Point–Point and Point–Cycle bursting. In particular, the slow passage effect, important for the Hopf–Hopf and SubHopf–SubHopf bursting subtypes, is explained by local divergence calculated for the fast subsystem. Quasi-periodic bursting Ca 2+ oscillations can be found in only one of the four studied mathematical models and appear via a homoclinic bifurcation with a homoclinic torus structure. For chaotic bursting Ca 2+ oscillations, we found that bursting patterns resulting from the period doubling root to chaos considerably differ from those appearing via intermittency and have to be treated separately. The analysis and classification of different types of bursting Ca 2+ oscillations provides better insight into mechanisms of complex intra- and intercellular Ca 2+ signalling. This improves our understanding of several important biological phenomena in cellular signalling like complex frequency–amplitude signal encoding and synchronisation of intercellular signal transduction between coupled cells in tissue.

Are supercritical fluids solvents for the future

Abstract: High pressure technologies involving sub and supercritical fluids offer the possibility to obtain new products with special characteristics or to design new processes which are environmentally friendly and sustainable. Using high pressure as a processing tool, the legal limitations for solvent residues and restrictions on use of conventional solvents in chemical processes can be avoided. Several sub and supercritical fluid technologies have already been developed to commercial scale. Extraction of valuable compounds from different materials and their “in situ” formulation in products with specific customer designed properties is one of the promising applications of high pressure technology. Particle formation using supercritical fluids overcomes the drawbacks of conventional particle size reduction processes. Unique thermodynamic and fluid-dynamic properties of dense gases can also be used for special impregnation of solid particles and particle coating. Impregnation into aerogels using supercritical carbon dioxide is an excellent way to improve the dissolution and bioavailability of poorly water soluble drugs. Some biochemical and chemical reactions performed in supercritical fluids have already been implemented on an industrial scale to obtain products with high added value. In this paper, some relevant applications and expected future development in the field of sub and supercritical fluids are reviewed.

Stochastic win-stay-lose-shift strategy with dynamic aspirations in evolutionary social dilemmas.

Abstract: In times of plenty expectations rise, just as in times of crisis they fall. This can be mathematically described as a win-stay-lose-shift strategy with dynamic aspiration levels, where individuals aspire to be as wealthy as their average neighbor. Here we investigate this model in the realm of evolutionary social dilemmas on the square lattice and scale-free networks. By using the master equation and Monte Carlo simulations, we find that cooperators coexist with defectors in the whole phase diagram, even at high temptations to defect. We study the microscopic mechanism that is responsible for the striking persistence of cooperative behavior and find that cooperation spreads through second-order neighbors, rather than by means of network reciprocity that dominates in imitation-based models. For the square lattice the master equation can be solved analytically in the large temperature limit of the Fermi function, while for other cases the resulting differential equations must be solved numerically. Either way, we find good qualitative agreement with the Monte Carlo simulation results. Our analysis also reveals that the evolutionary outcomes are to a large degree independent of the network topology, including the number of neighbors that are considered for payoff determination on lattices, which further corroborates the local character of the microscopic dynamics. Unlike large-scale spatial patterns that typically emerge due to network reciprocity, here local checkerboard-like patterns remain virtually unaffected by differences in the macroscopic properties of the interaction network.

Experimental analysis of injection characteristics using biodiesel fuel

Abstract: This paper deals with injection characteristics using different fuels at different fuel temperatures. The fuels under consideration are neat biodiesel from rapeseed oil and some blends with diesel as well as neat mineral diesel D2. The fuel and fuel temperature influences are investigated experimentally in the mechanically controlled diesel fuel injection M system. At first, attention is focused on the injection characteristics, especially on fuelling, mean injection rate, mean injection pressure, injection timing, injection delay, and injection duration, which influence the most important engine characteristics. Furthermore, the influence of fuel temperature is investigated. On the basis of the measurements of pressure drop through the fuel filter, the minimum fuel temperature for safe engine operation is determined.