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Efficiency of the coagulation/flocculation method for the treatment of dyebath effluents
Vera Golob, Aleksandra Vinder, Marjana Simonič, 2005, izvirni znanstveni članek

Opis: Textile dyeing processes are among the most environment-unfriendly industrial processes, because they produce coloured wastewaters that are heavily polluted with dyes, textile auxiliaries and chemicals. The coagulation/flocculation method was studied as a wastewater treatment technique for the decolourization of residual dyebath effluents after dyeing cotton/polyamide blends using reactive and acid dyes. It was discovered that acombination of aluminium sulphate and a cationic organic flocculant yields an effective treatment for residual dyebath wastewaters since almost complete decolourization was achieved, TOC, COD, AOX, BOD and the anionic surfactants were reduced and the biodegradability was increased.
Ključne besede: textile industry, reactive dyes, acid dyes, wastewater, čiščenje odpadnih vodwastewater treatment, flocculation, coagulation, ecological analyses, wastewater decoloration, Jar-tests
Objavljeno: 01.06.2012; Ogledov: 1569; Prenosov: 70
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Predicting civil religion at a cross-cultural level
Sergej Flere, Miran Lavrič, 2009, izvirni znanstveni članek

Opis: The concept of civil religion has caught major attention among scholars studying the junction of religion and politics (J.-J. Rousseau, E. Durkheim, R. Bellah). The notion focuses on the phenomenon of cultural contents sacralizing and ritualizing the ruling political institutions of a society, extending support to the integration of the political and social system at a cultural level. The notion of civil religion has recently been operationalized crossculturally, but light has not been shed upon its predictors. In this paper authoritarianism is tested as a predictor of civil religion cross-culturally. Four student samples of Bosnian, Serbian, Slovenian and US students were analyzed. Very strong, significant associations between authoritarianism, as operationalized by a modified Lane scale, and civil religion were found in all cases. Moreover, upon introducing femininity, anxiety and gender into the analysis, a strong, dominant and significant impact on the part of authoritarianism was still found when civil religion was observed crossculturally. When the same predictors were applied to explaining general religiosity, authoritarianism fell short of being a significant predictor in most of the environments observed. Such results suggest an especially close link between civil religion and authoritarianism.
Ključne besede: sociology of religion, civil religion, authoritarianism, religiosity, intercultural differences, religious orientation, Serbian orthodoxy, Slovenian catholicism, Bosnian Islam, cross-cultural analyses, anxiety
Objavljeno: 07.06.2012; Ogledov: 892; Prenosov: 201
.pdf Celotno besedilo (258,08 KB)
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Establishing the stochastic nature of intracellular calcium oscillations from experimental data
Matjaž Perc, Anne K. Green, C. Jane Dixon, Marko Marhl, 2008, izvirni znanstveni članek

Opis: Calcium has been established as a key messenger in both intra- and intercellular signaling. Experimentally observed intracellular calcium responses to different agonists show a variety of behaviors from simple spiking to complex oscillatory regimes. Here we study typical experimental traces of calcium oscillations in hepatocytes obtained in response to phenylephrine and ATP. The traces were analyzed with methods of nonlinear time series analysis in order to determine the stochastic/deterministic nature of the intracellular calcium oscillations. Despite the fact that the oscillations appear, visually, to be deterministic yet perturbed by noise, our analyses provide strong evidence that the measured calcium traces in hepatocytes are prevalently of stochastic nature. In particular, bursting calcium oscillations are temporally correlated Gaussian series distorted by a monotonic, instantaneous, time-independent function, whilst the spiking behavior appears to have a dynamical nonlinear component whereby the overall determinism level is still low. The biological importance of this finding is discussed in relation to the mechanisms incorporated in mathematical models as well as the role of stochasticity and determinism at cellular and tissue levels which resemble typical statistical and thermodynamic effects in physics.
Ključne besede: dynamic systems, stochastic processes, cellular signaling, calcium oscillations, time series analyses, noise, temporal correlation
Objavljeno: 07.06.2012; Ogledov: 1136; Prenosov: 97
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Application of elemental microanalysis to elucidate the role of spherites in the digestive gland of the helicid snail Chilostoma lefeburiana
Saška Lipovšek Delakorda, Ilse Letofsky-Papst, Tone Novak, Manuela Giovannelli, Ferdinand Hofer, Maria Anna Pabst, 2008, izvirni znanstveni članek

Opis: In this case study we present an application of different analytical electron microscopic methods in biology, to elucidate their usefulness in such investigations. Using analytical electron microscopy, spherites in the digestive gland cells of the helicid snail Chilostoma lefeburiana were examined at three stages: just before the non-feeding period of over-wintering in November, in the middle of over-wintering in February and at its end in March. A detailed characterization of changes in the elemental composition of the spherites was characterized by a combination of transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDXS), electron energy-loss spectroscopy (EELS) and energy filtering TEM (EFTEM). During over-wintering, the spherites passed the following changes. Before over-wintering in November, they consisted of striking concentric layers of electron-dense and electron-lucent zones, while in February and March they showed clear empty zones between materials of different electron density. In November spherites, C, O, Ca, P, Cl, Fe, Si, Na, K, Mg and S were detected, whereas in February ones C, O, N, Cl, Si and S were found and only C, O, N, Si and Cl were detected in March spherites. It is suggested that the elements missing in February and March were used in different physiological processes during over-wintering, like (1) the maintenance of the appropriate elemental composition of the internal environment, (2) accumulation of non-toxic waste materials that cannot be metabolized and (3) avoiding potential intoxication by contamination with toxic metals.
Ključne besede: zoology, Chilostoma lefeburiana, snails, digestive gland, over-wintering, spherites, elemental analyses, environmental pollution, chemical structures
Objavljeno: 07.06.2012; Ogledov: 1072; Prenosov: 66
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Review of experimental models for confirmation of mathematical models of gears
Boris Aberšek, Jože Flašker, 2008, izvirni znanstveni članek

Opis: In order to calculate the service life as precisely and reliably as possible we need good mathematical models for describing loading, geometry, properties of materials and fracture mechanics parameters. It can be established whether a mathematical model is precise and reliable only by comparison of results of the method such as analytical methods in case of simple problems and experiment when real complex structure are deal with. Since gears and gearing belong to the second group, by correctly selected and developed test pieces and carefully planned experiments we obtained results with which we confirmed and justified the mathematical model for calculating mentioned parameters. To this end we will show in this paper series of experimental methods and test pieces used on the gears.
Ključne besede: machine elements, gears, mathematical models, testing, experimental methods, numerical analyses
Objavljeno: 07.06.2012; Ogledov: 870; Prenosov: 44
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Singing of Neoconocephalus robustus as an example of deterministic chaos in insects
Tina P. Benko, Matjaž Perc, 2007, izvirni znanstveni članek

Opis: We use nonlinear time series analysis methods to analyse the dynamics of the sound-producing apparatus of the katydid Neoconocephalus robustus. We capture the dynamics by analysing a recording of the singing activity. First, we reconstruct the phase space from the sound recording and test it against determinism and stationarity. After confirming determinism and stationarity, we show that the maximal Lyapunov exponent of the series is positive, which is a strong indicator for the chaotic behaviour of the system. We discuss that methods of nonlinear time series analysis can yield instructive insights and foster the understanding of acoustic communication among insects.
Ključne besede: chaotic systems, chaos, time series, time series analyses, insect sounds, katydid
Objavljeno: 07.06.2012; Ogledov: 1183; Prenosov: 272
.pdf Celotno besedilo (1,05 MB)
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Thoughts out of noise
Matjaž Perc, 2006, izvirni znanstveni članek

Opis: We study the effects of additive Gaussian noise on the behaviour of a simple spatially extended system, which is locally modelled by a nonlinear two-dimensional iterated map describing neuronal dynamics. In particular, we focus on the ability of noise to induce spatially ordered patterns, i. e. the so-called noise-induced pattern formation. For intermediate noise intensities, the spatially extended system exhibits ordered circular waves, thereby clearly manifesting the constructive role of random perturbations. The emergence of observed noise-induced patterns is explained with simple arguments that are obtained by analysing the typical spatial scale of patterns evoked by various diffusion coefficients. Since discrete-time systems are straightforward to implement and require modest computational capabilities, the present study describes one of the most fascinating and visually compelling examples of noise-induced self-organization in nonlinear systems in an accessible way for graduate or even advanced undergraduate students attending a nonlinear dynamics course.
Ključne besede: dynamic systems, chaotic systems, nonlinear dynamics, nonlinear systems, noise, nonlinear analyses
Objavljeno: 07.06.2012; Ogledov: 937; Prenosov: 23
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Introducing nonlinear time series analysis in undergraduate courses
Matjaž Perc, 2006, strokovni članek

Opis: This article is written for undergraduate students and teachers who would like to get familiar with basic nonlinear time series analysis methods. We present a step-by-step study of a simple example and provide user-friendly programs that allow an easy reproduction of presented results. In particular, we study an artificial time series generated by the Lorenz system. The mutual information and false nearest neighbour method are explained in detail, and used to obtain the best possible attractor reconstruction. Subsequently, the times series is tested for stationarity and determinism, which are both important properties that assure correct interpretation of invariant quantities that can be extracted from the data set. Finally, as the most prominent invariant quantity that allows distinguishing between regular and chaotic behaviour, we calculate the maximal Lyapunov exponent. By following the above steps, we are able to convincingly determine that the Lorenz system is chaotic directly from the generated time series, without the need to use the differential equations. Throughout the paper, emphasis on clear-cut guidance and a hands-on approach is given in order to make the reproduction of presented results possible also for undergraduates, and thus encourage them to get familiar with the presented theory.
Ključne besede: nonlinear systems, nonlinear time series analyses, physics education
Objavljeno: 07.06.2012; Ogledov: 866; Prenosov: 22
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