Deduction in Education: the Case of Serbia

The main goal of the paper is to provide insight into the current state of education in Serbia regarding the use of educational aspects of software re-lated to deduction, geometry and mathematical reasoning. Authors investigate to what extent and for what purposes teachers and students use such software. The consideration of the current state is substantiated by the examples of teaching practices at different school levels, and supplemented by the proposals which tend to contribute to deeper understanding of the topic. The most commonly used automatic deduction and calculation programs in Serbian education are GeoGebra, Photomath, Microsoft Math Solver, Desmos, and Wolfram Alpha. These mathematical software represent an advantageous topic for cross-curricular connection in schools which could be realized in many different ways. It is suggested in the context of connecting mathematics and physics to art, history of science, national history of science, philosophy, logic and psychology

Smoothed particle hydrodynamics for blood flow analysis: development of particle lifecycle algorithm

The aim of this research was to facilitate the application of Smoothed Particle Hydrodynamics (SPH) method to Computational Fluid Dynamics analysis of turbulent flow through complex geometry blood vessels, and to compare it with the state-of-the-art Finite Element Method (FEM). SPH offers the possibility to observe motion of fluid fragment or particle inclusion within the Lagrangian material framework, giving researchers greater insight into the Fluid-Structure interaction such as transportation and distribution of medical particles, or buildup of plaque in atherosclerosis. In order to generate the fluid flow in SPH, the particles are created at inlet, and destroyed at the outlet. In this paper we present a novel lifecycle algorithm for generation and destruction of the particles using particle types, which is more flexible and suitable for the complex geometry models in comparison to the current state of the art commercial solutions, which use boundary planes. Our algorithm features mother and new-born particle types located at inlets used for the particle flow generation, and at the outlets, we have dying and killer particle types, which are used for deletion of particles. Based upon the current neighbors, the type of the particle is updated within the nearest neighbor search method, which is invoked in each time step. The capabilities of the new algorithm are demonstrated using a benchmark example and a realistic patient specific geometry, showing similar results, but the SPH advantages of particle tracking are yet to be utilized in our future work.Ministry of Education, Science and Technological Development of the Republic of SerbiaPublishe

Fractality and Self-organization in the Orthodox Iconography

The authors consider the Orthodox iconography of Byzantine style aimed at examining the existence of complex behavior and fractal patterns. It has been demonstrated that fractality in icons is manifested as two types-descending and ascending, where the former one corresponds to the apparent information and the latter one to the hidden causal information defining the spatiality of icon. Self-organization, recognized as the increase of the causal information in temporal domain, corresponds to contextualization of the observer's personage position. The results presented in the forms of plots and tables confirm the adequacy of the model being the completion of visual perception

SUPPORT TO AGRICULTURE AND RURAL DEVELOPMENT IN FUNCTION OF DECREASING POVERTY IN SERBIA

Around 45% of total population lives in rural areas, which cover almost three quarters of the country. Multiannual migration of population on relation rural-urban areas, followed by not fully appropriate social and rural policy, led to significant depopulation of rural areas. Multiannual practice of not investing in development of rural infrastructure and other aspects of rural living (strengthening of social and educational component of living in rural areas, development of rural economy not necessarily linked to agriculture, environmental protection…) made from rural areas parts of countryside with limited non-agricultural employment possibilities and providing permanent source of descent living, limited educational possibilities, insufficiently developed social aspects of everyday life and by all of these – unattractive areas for living of all residents and especially, young generations as key stakeholders in development of rural areas. Active role of Government and budget, Ministry in charge among other responsible institutions, for programming and financing measures of support to sustainable agricultural and rural development can play most important role in decreasing rural poverty

Memory load effect in auditory-verbal short-term memory task: EEG fractal and spectral analysis

The objective of this preliminary study was to quantify changes in complexity of EEG using fractal dimension (FD) alongside linear methods of spectral power, event-related spectral perturbations, coherence, and source localization of EEG generators for theta (4-7 Hz), alpha (8-12 Hz), and beta (13-23 Hz) frequency bands due to a memory load effect in an auditory-verbal short-term memory (AVSTM) task for words. We examined 20 healthy individuals using the Sternberg's paradigm with increasing memory load (three, five, and seven words). The stimuli were four-letter words. Artifact-free 5-s EEG segments during retention period were analyzed. The most significant finding was the increase in FD with the increase in memory load in temporal regions T3 and T4, and in parietal region Pz, while decrease in FD with increase in memory load was registered in frontal midline region Fz. Results point to increase in frontal midline (Fz) theta spectral power, decrease in alpha spectral power in parietal region-Pz, and increase in beta spectral power in T3 and T4 region with increase in memory load. Decrease in theta coherence within right hemisphere due to memory load was obtained. Alpha coherence increased in posterior regions with anterior decrease. Beta coherence increased in fronto-temporal regions. Source localization delineated theta activity increase in frontal midline region, alpha decrease in superior parietal region, and beta increase in superior temporal gyrus with increase in memory load. In conclusion, FD as a nonlinear measure may serve as a sensitive index for quantifying dynamical changes in EEG signals during AVSTM tasks

Rhamnolipid inspired lipopeptides effective in preventing adhesion and biofilm formation of Candida albicans

Rhamnolipids are biodegradable low toxic biosurfactants which exert antimicrobial and anti-biofilm properties. They have attracted much attention recently due to potential applications in areas of bioremediation, therapeutics, cosmetics and agriculture, however, the full potential of these versatile molecules is yet to be explored. Based on the facts that many naturally occurring lipopeptides are potent antimicrobials, our study aimed to explore the potential of replacing rhamnose in rhamnolipids with amino acids thus creating lipopeptides that would mimic or enhance properties of the parent molecule. This would allow not only for more economical and greener production but also, due to the availability of structurally different amino acids, facile manipulation of physico-chemical and biological properties. Our synthetic efforts produced a library of 43 lipopeptides revealing biologically more potent molecules. The structural changes significantly increased, in particular, anti-biofilm properties against Candida albicans, although surface activity of the parent molecule was almost completely abolished. Our findings show that the most active compounds are leucine derivatives of 3-hydroxy acids containing benzylic ester functionality. The SAR study demonstrated a further increase in activity with aliphatic chain elongation. The most promising lipopeptides 15, 23 and 36 at 12.5 mu g/mL concentration allowed only 14.3%, 5.1% and 11.2% of biofilm formation, respectively after 24 h. These compounds inhibit biofilm formation by preventing adhesion of C. albicans to abiotic and biotic surfaces

Absence of linkage disequilibria between chromosomal arrangements and mtDNA haplotypes in natural populations of Drosophila subobscura from the Balkan Peninsula

The genetic structure of Drosophila subobscura from the Balkan Peninsula was studied with respect to restriction site polymorphism of mitochondrial DNA in populations from the Derventa River Gorge and Sicevo Gorge (Serbia). To investigate the role of cytonuclear interactions in shaping mitochondrial DNA variability in natural populations of this species, the study was complemented with the analysis of linkage disequilibria between mitochondrial haplotypes and chromosomal inversion arrangements. Similar to other populations of D. subobscura, two main haplotypes (I and II) were found, as well as a series of less common ones. The frequencies of haplotypes I and II accounted for 25.8% and 71.0%, respectively, in the population from the Derventa River Gorge, and for 32.4% and 58.1%, respectively, in the population from Sicevo Gorge. One of the haplotypes harbored a large insertion (2.7 kb) in the A+T rich region. The frequency distribution of both haplotypes did not depart from neutrality. Contrary to prior studies, we did not detect any significant linkage disequilibrium between the two most frequent mtDNA haplotypes and any of the chromosomal arrangements in either of the populations. We conclude that linkage disequilibrium is not a general occurrence in natural populations of D. subobscura, and we discuss how transient coadaptations, ecologically specific selective pressures, and demographics could contribute to population-specific patterns of linkage disequilibrium.Ministry of Education and Science of the Republic of Serbia [173012

Absence of linkage disequilibria between chromosomal arrangements and mtDNA haplotypes in natural populations of Drosophila subobscura from the Balkan Peninsula

The genetic structure of Drosophila subobscura from the Balkan Peninsula was studied with respect to restriction site polymorphism of mitochondrial DNA in populations from the Derventa River Gorge and Sicevo Gorge (Serbia). To investigate the role of cytonuclear interactions in shaping mitochondrial DNA variability in natural populations of this species, the study was complemented with the analysis of linkage disequilibria between mitochondrial haplotypes and chromosomal inversion arrangements. Similar to other populations of D. subobscura, two main haplotypes (I and II) were found, as well as a series of less common ones. The frequencies of haplotypes I and II accounted for 25.8% and 71.0%, respectively, in the population from the Derventa River Gorge, and for 32.4% and 58.1%, respectively, in the population from Sicevo Gorge. One of the haplotypes harbored a large insertion (2.7 kb) in the A+T rich region. The frequency distribution of both haplotypes did not depart from neutrality. Contrary to prior studies, we did not detect any significant linkage disequilibrium between the two most frequent mtDNA haplotypes and any of the chromosomal arrangements in either of the populations. We conclude that linkage disequilibrium is not a general occurrence in natural populations of D. subobscura, and we discuss how transient coadaptations, ecologically specific selective pressures, and demographics could contribute to population-specific patterns of linkage disequilibrium.Ministry of Education and Science of the Republic of Serbia [173012