Showing papers by "University of Ljubljana published in 2005"

Exploratory Social Network Analysis with Pajek

Abstract: This is an extensively revised and expanded second edition of the successful textbook on social network analysis integrating theory, applications, and network analysis using Pajek. The main structural concepts and their applications in social research are introduced with exercises. Pajek software and data sets are available so readers can learn network analysis through application and case studies. Readers will have the knowledge, skill, and tools to apply social network analysis across the social sciences, from anthropology and sociology to business administration and history. This second edition has a new chapter on random network models, for example, scale-free and small-world networks and Monte Carlo simulation; discussion of multiple relations, islands, and matrix multiplication; new structural indices such as eigenvector centrality, degree distribution, and clustering coefficients; new visualization options that include circular layout for partitions and drawing a network geographically as a 3D surface; and using Unicode labels. This new edition also includes instructions on exporting data from Pajek to R software. It offers updated descriptions and screen shots for working with Pajek (version 2.03).

A Computational Guide to Physics of Eclipsing Binaries. I. Demonstrations and Perspectives

Abstract: PHOEBE (PHysics Of Eclipsing BinariEs) is a modeling package for eclipsing binary stars, built on top of the widely used WD program of Wilson & Devinney. This introductory paper gives an overview of the most important scientific extensions (incorporating observational spectra of eclipsing binaries into the solution-seeking process, extracting individual temperatures from observed color indices, main-sequence constraining, and proper treatment of the reddening), numerical innovations (suggested improvements to WD's differential corrections method, the new Nelder & Mead downhill simplex method), and technical aspects (back-end scripter structure, graphical user interface). While PHOEBE retains 100% WD compatibility, its add-ons are a powerful way to enhance WD by encompassing even more physics and solution reliability. The operability of all these extensions is demonstrated on a synthetic main-sequence test binary; applications to real data will be published in follow-up papers. PHOEBE is released under the GNU General Public License, which guarantees it to be free and open to anyone interested in joining in on future development.

Impact of the Carbon Coating Thickness on the Electrochemical Performance of LiFePO4 / C Composites

Abstract: Porous, well crystalline LiFePO 4 /C composites with different amounts of carbon have been prepared by a sol-gel technique. The thickness of carbon coatings (paintings) has been determined by high-resolution transmission electron microscopy. It is shown that carbon coating thickness can be controlled by the amount of carbon and it has an impact on the obtained reversible capacity. Furthermore, it is shown that atomic ratio of nonactive Fe(III) phase (presumably Fe 3 P) in as-synthesized LiFePO 4 /C composites depends on the amount of carbon in the composite. Using Mossbauer spectroscopy, we have confirmed that the nonactive Fe(III) remains nearly unchanged in the composite during cycling. The lowest amount of carbon in LiFePO 4 /C composites obtained from citrate anion as a gelling agent was 3.2 wt % and this particular amount corresponds to the carbon coating thickness of about 1-2 nm. The reversible capacity obtained from the above-mentioned composite delivers close to 80% of the theoretical capacity at room temperature with a current density of 170 mA/g (C/1 rate).

National character does not reflect mean personality trait levels in 49 cultures

Abstract: Most people hold beliefs about personality characteristics typical of members of their own and others' cultures. These perceptions of national character may be generalizations from personal experience, stereotypes with a "kernel of truth," or inaccurate stereotypes. We obtained national character ratings of 3989 people from 49 cultures and compared them with the average personality scores of culture members assessed by observer ratings and self-reports. National character ratings were reliable but did not converge with assessed traits. Perceptions of national character thus appear to be unfounded stereotypes that may serve the function of maintaining a national identity.

An extensive library of 2500–10 500 Å synthetic spectra

Abstract: We present a complete library of synthetic spectra based on Kurucz’s codes that covers the 2500–10 500 A wavelength range at resolving powers RP = 20 000, 11 500 (≡GAIA), 8500 (≡RAVE), 2000 (≡SLOAN) and uniform dispersions of 1 and 10 A/pix. The library maps the whole HR diagram, exploring 51 288 combinations of atmospheric parameters spanning the ranges: 3500 ≤ Teff ≤ 47 500 K, 0.0 ≤ log g ≤ 5.0, −2.5 ≤ [M/H] ≤ 0.5, [α/Fe] = 0.0,+0.4, ξ = 1, 2, 4 km s −1 ,0 ≤ Vrot ≤ 500 km s −1 . The spectra are available both as absolute fluxes as well as continuum normalized. Performance tests and spectroscopic applications of the library are discussed, including automatic classification of data from spectroscopic surveys like RAVE, SLOAN, GAIA. The entire library of synthetic spectra is accessible via the web.

Observation of a Near-Threshold ωJ/ψ Mass Enhancement in Exclusive B→KωJ/ψ Decays

Abstract: Reference EPFL-ARTICLE-154584doi:10.1103/PhysRevLett.94.182002View record in Web of Science Record created on 2010-11-05, modified on 2017-12-10

Efficient generation of large random networks.

Abstract: Random networks are frequently generated, for example, to investigate the effects of model parameters on network properties or to test the performance of algorithms. Recent interest in the statistics of large-scale networks sparked a growing demand for network generators that can generate large numbers of large networks quickly. We here present simple and efficient algorithms to randomly generate networks according to the most commonly used models. Their running time and space requirement is linear in the size of the network generated, and they are easily implemented.

Sequential finite element model of tissue electropermeabilization

Abstract: Permeabilization, when observed on a tissue level, is a dynamic process resulting from changes in membrane permeability when exposing biological cells to external electric field (E). In this paper we present a sequential finite element model of E distribution in tissue which considers local changes in tissue conductivity due to permeabilization. These changes affect the pattern of the field distribution during the high voltage pulse application. The presented model consists of a sequence of static models (steps), which describe E distribution at discrete time intervals during tissue permeabilization and in this way present the dynamics of electropermeabilization. The tissue conductivity for each static model in a sequence is determined based on E distribution from the previous step by considering a sigmoid dependency between specific conductivity and E intensity. Such a dependency was determined by parameter estimation on a set of current measurements, obtained by in vivo experiments. Another set of measurements was used for model validation. All experiments were performed on rabbit liver tissue with inserted needle electrodes. Model validation was carried out in four different ways: 1) by comparing reversibly permeabilized tissue computed by the model and the reversibly permeabilized area of tissue as obtained in the experiments; 2) by comparing the area of irreversibly permeabilized tissue computed by the model and the area where tissue necrosis was observed in experiments; 3) through the comparison of total current at the end of pulse and computed current in the last step of sequential electropermeabilization model; 4) by comparing total current during the first pulse and current computed in consecutive steps of a modeling sequence. The presented permeabilization model presents the first approach of describing the course of permeabilization on tissue level. Despite some approximations (ohmic tissue behavior) the model can predict the permeabilized volume of tissue, when exposed to electrical treatment. Therefore, the most important contribution and novelty of the model is its potentiality to be used as a tool for determining parameters for effective tissue permeabilization.

Observation of B+ ---> K(1)(1270)+ gamma

Abstract: We report the observation of the radiative decay B+-->K1(1270)(+) gamma using a data sample of 140 fb(-1) taken at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- collider. We find the branching fraction to be B(B+-->K1(1270)(+)gamma)=(4.3+/-0.9(stat.)+/-0.9(syst.))x10(-5) with a significance of 7.3sigma. We find no significant signal for B+-->K1(1400)(+)gamma and set an upper limit B(B+-->K1(1400)(+)gamma) K+pi+pi-gamma and B0-->K0pi+pi-gamma in the mass range 1 GeV/c(2)

Phenolic acids, syringaldehyde, and juglone in fruits of different cultivars of Juglans regia L.

Abstract: Phenolic acids (chlorogenic, caffeic, p-coumaric, ferulic, sinapic, ellagic, and syringic acid) as well as syringaldehyde and juglone were identified in ripe fruits of 10 walnut cultivars: Adams, Cisco, Chandler, Franquette, Lara, Fernor, Fernette, Alsoszentivani 117 (A-117), Rasna, and Elit. Analyses were done using a high-performance liquid chromatograph equipped with a diode array detector. Significant differences in the contents of identified phenolics were observed among cultivars. Phenolics were determined separately in the kernel and in the thin skin of the walnut, termed the pellicle. Not only in the kernel but also in the pellicle did syringic acid, juglone, and ellagic acid predominate (average values of 33.83, 11.75, and 5.90 mg/100 g of kernel; and 1003.24, 317.90, and 128.98 mg/100 g of pellicle, respectively), and the contents of ferulic and sinapic acid (average values of 0.06 and 0.05 mg/100 g of kernel and 2.93 and 2.17 mg/100 g of pellicle, respectively) were the lowest in all cultivars. The highest differences in the sum of all identified phenolics were observed between Rasna and Fernette fruits; in Rasna there were >2-fold higher contents of identified phenolics in both kernel and pellicle. It was found that the walnut pellicle is the most important source of walnut phenolics. The ratio between the contents in pellicle and kernel varied by at least 14.8-fold for caffeic acid (cv. Adams) and by up to 752.0-fold for p-coumaric acid (cv. Elit).

Characterization of phenol-formaldehyde prepolymer resins by in line FT-IR spectroscopy

Abstract: Different resol phenol-formaldehyde prepolymer resins have been synthesized with different formaldehyde / phenol ratios. The phenolic resin composition depends on monomer ratio, catalyst, reaction conditions, and residual free monomers. Temperature and pH conditions under which reactions of phenols with formaldehyde are carried out have a profound effect on the characteristics of the resulting products. Three reaction sequences must be considered: formaldehyde addition to phenol, chain growth or prepolymer formation and finally the crosslinking or curing reaction. Two prepolymer types are obtained depending on pH, novolacs in an acidic pH region whereas resols by alkaline reaction. Resol resins are synthesized with a molar excess of formaldehyde (1

Yeast diversity in hypersaline habitats

Abstract: Thus far it has been considered that hypersaline natural brines which are subjected to extreme solar heating, do not contain nonmelanized yeast populations. Nevertheless we have isolated yeasts in eight different salterns worldwide, as well as from the Dead Sea, Enriquillo Lake (Dominican Republic) and the Great Salt Lake (Utah). Among the isolates obtained from hypersaline waters, Pichia guilliermondii, Debaryomyces hansenii, Yarrowia lipolytica and Candida parapsilosis are known contaminants of low water activity food, whereas Rhodosporidium sphaerocarpum, R. babjevae, Rhodotorula laryngis, Trichosporon mucoides, and a new species resembling C. glabrata were not known for their halotolerance and were identified for the first time in hypersaline habitats. Moreover, the ascomycetous yeast Metschnikowia bicuspidata, known to be a parasite of the brine shrimp, was isolated as a free-living form from the Great Salt Lake brine. In water rich in magnesium chloride (bitterns) from the La Trinitat salterns (Spain), two new species provisionally named C. atmosphaerica – like and P. philogaea – like were discovered. 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.

Torsional effects in the pushover-based seismic analysis of buildings

Abstract: The general trends of the inelastic behaviour of plan-asymmetric structures have been studied. Systems with structural elements in both orthogonal directions and bi-axial eccentricity were subjected to bi-directional excitation. Test examples include idealised single-storey and multi-storey models, and a three-storey building, for which test results are available. The response in terms of displacements was determined by nonlinear dynamic analyses. The main findings, limited to fairly regular and simple investigated buildings, are: (a) The amplification of displacements determined by elastic dynamic analysis can be used as a rough, and in the majority of cases conservative estimate in the inelastic range. (b) Any favourable torsional effect on the stiff side, which may arise from elastic analysis, may disappear in the inelastic range. These findings can be utilised in the approximate pushover-based seismic analysis of asymmetric buildings, e.g. in the N2 method. It is proposed that the results obtained by pushover analysis of a 3D structural model be combined with the results of a linear dynamic (spectral) analysis. The former results control the target displacements and the distribution of deformations along the height of the building, whereas the latter results define the torsional amplifications. The proposed approach is partly illustrated and evaluated by test examples.

On stability prediction for milling

Abstract: Stability of 2-dof milling is investigated. Stability boundaries are predicted by the zeroth order approximation (ZOA) and the semi-discretization (SD) methods. While similar for high radial immersions, predictions of the two methods grow considerably different as radial immersion is decreased. The most prominent difference is an additional type of instability causing periodic chatter which is predicted only by the SD method. Experiments confirm predictions of the SD method, revealing three principal types of tool motion: periodic chatter-free, quasi-periodic chatter and periodic chatter, as well as some special chatter cases. Tool deflections recorded during each of these motion types are studied in detail.

Public perception of flood risks, flood forecasting and mitigation

Abstract: . A multidisciplinary and integrated approach to the flood mitigation decision making process should provide the best response of society in a flood hazard situation including preparation works and post hazard mitigation. In Slovenia, there is a great lack of data on social aspects and public response to flood mitigation measures and information management. In this paper, two studies of flood perception in the Slovenian town Celje are represented. During its history, Celje was often exposed to floods, the most recent serious floods being in 1990 and in 1998, with a hundred and fifty return period and more than ten year return period, respectively. Two surveys were conducted in 1997 and 2003, with 157 participants from different areas of the town in the first, and 208 in the second study, aiming at finding the general attitude toward the floods. The surveys revealed that floods present a serious threat in the eyes of the inhabitants, and that the perception of threat depends, to a certain degree, on the place of residence. The surveys also highlighted, among the other measures, solidarity and the importance of insurance against floods.

The frequency and potential causes of dispensing errors in a hospital pharmacy.

Abstract: Objectives: To determine the frequency and types of dispensing errors identified both at the final check stage and outside of a UK hospital pharmacy, to explore the reasons why they occurred, and to make recommendations for their prevention.

Phenolic compounds in some apple (Malus domestica Borkh) cultivars of organic and integrated production

Abstract: Eleven organically grown apple cultivars and 11 apple cultivars of integrated production from Austria and Slovenia were analyzed by HPLC for the content of phenolic compounds in peel and pulp. We identified chlorogenic acid, p-coumaric acid, procyanidin B3, protocatechuic acid, (−)-epicatechin, phloridzin, rutin and quercetin-3-rhamnoside in apple peel. In apple pulp, (+)-catechin was also identified in all the cultivars. Some other phenols (procyanidin B3, rutin and quercetin-3-rhamnoside) could not be identified or were not properly separated. With regard to the phenolic content in the apple peel, there were no differences between organically grown apple cultivars and apple cultivars of integrated production. Organically grown apples, however, exhibited a higher content of phenolic substances in the apple pulp compared with the apple cultivars of integrated production. This may be due either to the different genotype source or to the growing technology. Higher concentrations of phenolic compounds in organically grown cultivars could be a result of plant response to stress. The apple peel contained higher concentrations of identified phenols than the pulp. The apple peel represents up to 10% of the whole fruit; therefore the phenolsic compounds in the pulp are of greater importance to the consumer than the phenolic compounds in the peel. Copyright © 2005 Society of Chemical Industry

Evaluation of peach and nectarine fruit quality and correlations between sensory and chemical attributes

Abstract: Sensory attributes and chemical composition in peach and nectarine fruits of nine different cultivars were evaluated and compared The cultivars investigated in the research were: 'Maria Marta', 'Romestar', '325 x A/8', '224 x A/13', 'V x S/4', 'Bea', 'Maria Aurelia', 'Venus' and 'Spring Red' In sensory evaluation the 'Maria Aurelia' was the highest rated, and the '224 x A/13' was the lowest The cultivars '325 x A/8', '224 x A/13', 'V x S/4' and 'Spring Red' were poor in sugars; however, the 'Spring Red' was rich in organic acids Similarly, the 'Maria Aurelia' and 'Venus' fruits had higher contents of organic acids and were also rich in sugars Furthermore, the relationships among sensory and chemical attributes of fruit quality were studied The sensory evaluations of sweetness, taste, and aroma were well correlated with some chemically measured attributes of peach and nectarine quality: sweetness was influenced by citric acid, shikimic acid and sugars/organic acids ratio; aroma was correlated with total organic acids, sucrose, sorbitol and malic acid; taste was related to malic/citric acid ratio, total sugars, sucrose, sorbitol and malic acid The results of the research indicate that sensory evaluation provides a good tool in the quick assessment of peach and nectarine fruit quality

Photon events with missing energy in e(+)e(-) collisions at root s=130 to 209 GeV

Abstract: The production of single- and multi-photon events has been studied in the reaction e+e- -> gamma (gamma) + invisible particles. The data collected with the DELPHI detector during the years 1999 and 2000 at centre-of-mass energies between 191 GeV and 209 GeV was combined with earlier data to search for phenomena beyond the Standard Model. The measured number of light neutrino families was consistent with three and the absence of an excess of events beyond that predicted by the Standard Model processes was used to set limits on new physics. Both model-independent searches and searches for new processes predicted by supersymmetric and extra-dimensional models have been made. Limits on new non-standard model interactions between neutrinos and electrons were also determined.

Taxonomy and phylogeny of the xerophilic genus Wallemia (Wallemiomycetes and Wallemiales, cl. et ord. nov.)

Abstract: The genus Wallemia comprises xerophilic species. Based on parenthesome ultrastructure it has been linked to the Filobasidiales (basidiomycetes). Species show a unique type of conidiogenesis, including basauxic development of fertile hyphae, segregation of conidial units more or less basipetally, and disarticulation of conidial units into mostly four arthrospore-like conidia. Wallemia is known from air, soil, dried food (causing spoilage), and salt. It can be isolated from hypersaline water of man-made salterns on different continents. Based on analyses of the nuclear small subunit ribosomal DNA (SSU rDNA) Wallemia has been placed into a highly supported clade together with Ustilaginomycetes and Hymenomycetes (Basidiomycota). Within this clade, it possesses an isolated position distantly related to the Filobasidiales and was characterized by numerous nucleotide substitutions not shared by any other fungus. Tests on xerotolerance indicated that Wallemia presents one of the most xerophilic fungal taxa. Xerotolerance is otherwise rare in the Basidiomycota. To acknowledge its unique morphology, evolution, and xerotolerance, a new basidiomycetous class Wallemiomycetes covering an order Wallemiales, is proposed. Based on differences in conidial size, xerotolerance, and sequence data of the rDNA internal transcribed spacer regions (ITS rDNA), at least three Wallemia species are segregated, identified as Wallemia ichthyophaga, Wallemia sebi, and Torula epizoa var. muriae, for which the combination Wallemia muriae is proposed. The three species are neotypified. Wallemia ichthyophaga differs from W. sebi and W. muriae in numerous nucleotides of the SSU and ITS rDNA. This high variation within Wallemia indicates existence of at least two cryptic genera not distinguishable by morphological characters.