Showing papers by "University of Ljubljana published in 1997"
TL;DR: This work reimplemented Assistant, a system for top down induction of decision trees, using RELIEFF, an extension of RELIEF, as an estimator of attributes at each selection step for heuristic guidance of inductive learning algorithms.
Abstract: Current inductive machine learning algorithms typically use greedy search with limited lookahead. This prevents them to detect significant conditional dependencies between the attributes that describe training objects. Instead of myopic impurity functions and lookahead, we propose to use RELIEFF, an extension of RELIEF developed by Kira and Rendell l10, 11r, for heuristic guidance of inductive learning algorithms. We have reimplemented Assistant, a system for top down induction of decision trees, using RELIEFF as an estimator of attributes at each selection step. The algorithm is tested on several artificial and several real world problems and the results are compared with some other well known machine learning algorithms. Excellent results on artificial data sets and two real world problems show the advantage of the presented approach to inductive learning.
722 citations
01 Jan 1997
TL;DR: In the last decade important relations between Laplace eigenvalues and eigenvectors of graphs and several other graph parameters were discovered as discussed by the authors, and their consequences are discussed in detail.
Abstract: In the last decade important relations between Laplace eigenvalues and eigenvectors of graphs and several other graph parameters were discovered. In these notes we present some of these results and discuss their consequences. Attention is given to the partition and the isoperimetric properties of graphs, the max-cut problem and its relation to semidefinite programming, rapid mixing of Markov chains, and to extensions of the results to infinite graphs.
510 citations
TL;DR: In this article, the effect of conservation laws on the finite-temperature transport properties in one-dimensional integrable quantum many-body systems was studied and the energy current is closely related to the first conservation law in these systems and therefore the thermal transport coefficients are anomalous.
Abstract: We study the effect of conservation laws on the finite-temperature transport properties in one-dimensional integrable quantum many-body systems. We show that the energy current is closely related to the first conservation law in these systems and therefore the thermal transport coefficients are anomalous. Using an inequality on the time decay of current correlations we show how the existence of conserved quantities implies a finite charge stiffness (weight of the zero-frequency component of the conductivity) and so ideal conductivity at finite temperatures.
440 citations
TL;DR: Weak isosinglet neutral heavy leptons (m) have been searched for using data collected by the DELPHI detector corresponding to 3:3 106 hadronic Z0 decays at LEP1.
Abstract: Weak isosinglet Neutral Heavy Leptons (m) have been searched for using data collected by the DELPHI detector corresponding to 3:3 106 hadronic Z0 decays at LEP1. Four separate searches have been performed, for short-lived m production giving monojet or acollinear jet topologies, and for long-lived m giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(Z0 ! m) of about 1:310−6 at 95% confidence level for m masses between 3.5 and 50 GeV/c2. Outside this range the limit weakens rapidly with the m mass. The results are also interpreted in terms of limits for the single production of excited neutrinos.
337 citations
TL;DR: European physicians need to be aware that HGE exists in Europe and that the diagnosis should be considered in febrile patients with tick bites in areas where Lyme disease is endemic.
Abstract: Human granulocytic ehrlichiosis (HGE) was recently described in North America. It is caused by an Ehrlichia species closely related to Ehrlichia phagocytophila and Ehrlichia equi, recognized to infect mostly ruminants and horses, respectively. The vector in North America is the tick Ixodes scapularis, which is also the vector of the Lyme disease agent, Borrelia burgdorferi. Previous serologic studies in patients with a diagnosis of Lyme borreliosis indicate that HGE may exist in Europe. We report the first documented case of HGE in Europe. The diagnosis was established by seroconversion to E. equi and the HGE agent and by PCR with sequence analysis of the gene encoding the HGE agent 16S rRNA. Interestingly, the patient presented with a self-limited but moderately severe illness. Thus, European physicians need to be aware that HGE exists in Europe and that the diagnosis should be considered in febrile patients with tick bites in areas where Lyme disease is endemic.
308 citations
TL;DR: The study showed that variations of membrane conductivity, cytoplasmic conductivity and cell radius within the ranges of their physiological values do not influence induced transmembrane voltage substantially, provided that extracellular conductivity also corresponds to the physiological conditions, and duration of the electric pulse is in range of 10μ s or longer.
244 citations
TL;DR: In this article, the authors present a basic control system which enables the UPFC to follow the changes in reference values of the active and reactive power supplied from the outer system controller, based on the transformation of the three-phase power system to the rotating reference frame.
Abstract: A unified power flow controller (UPFC) is a typical FACTS device capable of instantaneous control of three power system parameters. This paper presents a basic control system which enables the UPFC to follow the changes in reference values of the active and reactive power supplied from the outer system controller. The analysis is based on the transformation of the three-phase power system to the rotating reference frame. As a step closer to a practical application of the UPFC, a modified control structure with a predictive control loop and precontrol signal for a DC-voltage control was designed. The new control system offers better stability and transient performance in comparison with the classical decoupled strategy, especially considering the harmonic distortion of the current being controlled. The derived basic control of the UPFC was tested with the NETOMAC program system.
203 citations
TL;DR: The phenotypic differences among the newly defined species suggest that they may occupy distinct niches within the rumen ecosystem.
Abstract: Selected phenotypic characteristics of isolates of Prevotella ruminicola (formerly Bacteroides ruminicola) were studied in order to establish whether the characteristics of genotypic strain groups established previously on the basis of 16S ribosomal DNA sequences differed systematically. Among strains formerly considered P. ruminicola subsp. brevis, strains related to strain GA33T (T = type strain) typically failed to produce carboxymethyl cellulase (CMCase) activity detectable by plate assays and failed to ferment xylose, while strains related to strain B14T produced abundant CMCase and fermented xylose. We propose that strains related to GA33T, which have DNA G+C contents between 45 and 51 mol%, should be assigned to a new species, Prevotella brevis, and that strains related to B14T, which have DNA G+C contents between 39 and 43 mol%, should be assigned to another new species, Prevotella bryantii. Most of the isolates formerly classified as P. ruminicola subsp. ruminicola strains produced CMCase and had DNA G+C contents between 45 and 51 mol%, and we propose that these organisms should be placed in the redefined species P. ruminicola. A small group of isolates that have lower G+C contents are assigned to another new species, Prevotella albensis. Most P. brevis and P. bryantii strains produced abundant extracellular DNase activity. Proteinase activities (as determined by [14C] casein hydrolysis) varied widely between strains, and P. brevis strains exhibited the highest mean activity. All strains produced dipeptidyl peptidase activity, but the relative activities against different peptide substrates exhibited by P. bryantii, P. albensis, and P. brevis differed systematically. The phenotypic differences among the newly defined species suggest that they may occupy distinct niches within the rumen ecosystem.
200 citations
TL;DR: It is shown that superquadrics can directly be recovered from unsegmented data, thus avoiding any presegmentation steps (e.g. in terms of surfaces), and the approach is based on the recover-and-select paradigm.
Abstract: We present an approach to reliable and efficient recovery of part-descriptions in terms of superquadric models from range data. We show that superquadrics can directly be recovered from unsegmented data, thus avoiding any presegmentation steps (e.g. in terms of surfaces). The approach is based on the recover-and-select paradigm. We present several experiments on real and synthetic range images, where we demonstrate the stability of the results with respect to viewpoint and noise.
170 citations
TL;DR: The cloning of a rat AChE-associated collagen subunit, Q, is reported and it is found that the same ColQ subunits are incorporated, in vivo, in asymmetric forms of both A ChE and butyrylcholinesterase.
167 citations
TL;DR: Freshly harvested whole cells from cultures of P. bryantii B(1)4 shown less than 25% of the enzyme activity against oat spelt xylan (OSX) as an energy source showed that much of this hydrolytic activity is either periplasmic, membrane-associated or intracellular and may be concerned with the processing of transported oligosaccharides.
TL;DR: It can be concluded that after rehydration of dried crude gastric porcine mucin, a model mucus system with rheological properties equivalent to natural mucus cannot be obtained.
TL;DR: In this article, an analytical approach to voltage collapse proximity determination is proposed for radial networks under corresponding assumptions, and an analytical expression is derived for calculation of active and reactive power reserve margins for a radial network equivalent.
Abstract: Analytical approach to voltage collapse proximity determination is proposed for radial networks. Under corresponding assumptions, a radial network with arbitrary bus loads is transformed into a two bus equivalent. The voltage phasors at the generator bus and at the last load bus of the radial network are transformed to form the voltage phasors of the two bus equivalent. The latter are further used for assessment of voltage collapse proximity. Exact stability limit relations for a two bus system derived from Jacobian matrix can be exploited. Moreover, an analytical expression is derived for calculation of active and reactive power reserve margins for a radial network equivalent. The proposed procedure has been tested for practical examples of radial networks with inductive and capacitive loads.
TL;DR: This proposed measuring method contributes to a better understanding of skeletal muscles' dynamic properties and offers a possible way of studying the muscle structure from the muscle's response to electrical stimulation in a simple noninvasive way.
Abstract: Many studies have been completed to determine how muscles work. One of the aspects to study is the muscle response and how to measure it. The main aim of this study was to build a noninvasive measuring system that would be simple to use and would measure the muscle response as close to the muscle as possible. The measuring method was based on a magnetic displacement sensor measuring the muscle belly response. The sensor was placed adjacent to the skin over the muscle and measured radial movements of the muscle belly. The muscle response to single twitch electrical stimulation was measured. Different skeletal muscles or muscle groups have different biomechanical characteristics. The rise time of the muscle belly response was the characteristic parameter for this study. The comparison of muscles' responses in terms of the values of their normalized rise time parameters confirmed their identities as slow or fast muscles. The value of the normalized rise time parameter of a slow muscle was four times less than the value of the parameter of a fast muscle. Although the question remains as to how the available measuring techniques provide estimation of skeletal muscles' dynamic properties, this proposed measuring method contributes to a better understanding of skeletal muscles' dynamic properties. It offers a possible way of studying the muscle structure from the muscle's response to electrical stimulation in a simple noninvasive way.
TL;DR: Thermal denaturation of equinatoxin II in glycine buffer solutions and in triple distilled water was examined to find a stable acid-denatured compact state which shows all the characteristics of a molten globule, which even at 95 degrees C is not completely denatured.
Abstract: Thermal denaturation of equinatoxin II (EqTxII) in glycine buffer solutions (pH 1.1, 2.0, 3.0, and 3.5) and in triple distilled water (pH 5.5-6.0) was examined by differential scanning calorimetry, UV and CD spectroscopy and fluorescence emission spectroscopy of the added hydrophobic fluorescent probe ANS. At pH 5.5-6.0 and at temperatures below 60 degrees C, the protein exists in a native state characterized by a pronounced tertiary structure, a beta-rich secondary structure and a low degree of ANS-binding. At higher temperatures, it undergoes a two-state conformational transition, (delta H degree)VH = (delta H degree)DSC, into an unfolded state, which is characterized by a complete collapse of its tertiary structure and an incomplete denaturation of its secondary structure. At acidic pH, the EqTxII temperature-induced conformational transition appears at lower temperatures as non-two-state transition accompanied by the formation of an intermediate state which shows characteristics of molten globules, i.e., absence of defined tertiary structure, increase in alpha-rich secondary structure, and high affinity for ANS. At pH 2.0, the low-temperature initial state of EqTxII is already partially denatured; the tertiary structure is partially disrupted, and a pronounced inequality (delta H degree)VH > (delta H degree)DSC is observed. At pH value of 1.1 and below 60 degrees C, EqTxII exists in a stable acid-denatured compact state which shows all the characteristics of a molten globule, which even at 95 degrees C is not completely denatured. According to numerous studies on the pore forming toxins, such acid-denatured compact states may contribute to the protein's ability to penetrate into biological membranes.
TL;DR: Ciprofloxacin hexahydrate has been prepared and its crystal structure has been determined by X-ray crystallography as mentioned in this paper, the molecule is in the zwitterionic form in solid state, the carboxylic proton being present at terminal piperazine nitrogen atom (N(74)).
TL;DR: In this article, surface ozone data from 25 Europeanlow-altitude sites and mountain sites located between 79°N and 28°N were studied for the time period March 1989-February 1993.
Abstract: Surface ozone data from 25 Europeanlow-altitude sites and mountain sites located between79°N and 28°N were studied. The analysiscovered the time period March 1989–February 1993.Average summer and winter O3 concentrations inthe boundary layer over the continent gave rise togradients that were strongest in the north-west tosouth-east direction and west-east direction, respectively. WintertimeO3 ranged from 19 to 27 ppbover the continent, compared to about 32 ppb at thewestern border, while for summer the continentalO3 values ranged between 39 and 56 ppb and theoceanic mixing ratios were around 37 ppb. In the lowerfree troposphere average wintertime O3 mixingratios were around 38 ppb, with only an 8 ppbdifference between 28°N and 79°N. For summerthe average O3 levels decreased from about 55 ppbover Central Europe to 32 ppb at 79°N. Inaddition, O3 and Ox(= O3 + NO2)in polluted and clean air were compared. Theamplitudes of the seasonal ozone variations increasedin the north-west to south-east direction, while thetime of the annual maximum was shifted from spring (atthe northerly sites) to late summer (at sites inAustria and Hungary), which reflected the contributionof photochemical ozone production in the lower partsof the troposphere.
TL;DR: A new approach to automatic derivation of formulas needed in nonlinear finite element analysis is presented, combining several techniques: symbolic capabilities of Mathematica, automatic differentiation technique, simultaneous optimization of expressions and a stochastic evaluation of the formulas instead of a conventional pattern matching technique.
TL;DR: Two bismuth(III) compounds of ciprofloxacin (cf) were synthesized and the crystal structure of one--(cfH2) (cfH) [BiCl6]--is presented and discussed and antimicrobial activity of this compound was tested against different microorganisms.
TL;DR: Toxicity testing with terrestrial isopods is a very promising method for fast, routine, and inexpensive laboratory determination of the relative toxicities of chemicals in the terrestrial environment.
Abstract: Terrestrial isopods are suitable invertebrates for testing the relative toxicities of chemicals present in the terrestrial environment. Terrestrial isopods respond in numerous ways to elevated concentrations of chemicals in their food, but only a few of these responses can be used as toxicological endpoints. The most suitable are changes in reproduction, food consumption, moult cycle duration, and structure of the digestive glands. These responses are able to provide accurate indications of sublethal toxicity. Toxicity tests with terrestrial isopods could be much more reliable through the use of positive controls. A positive control with a reference toxicant could also be supplemented by a reference endpoint. The most suitable reference endpoint is change of food consumption rate. Toxicity testing with terrestrial isopods is a very promising method for fast, routine, and inexpensive laboratory determination of the relative toxicities of chemicals in the terrestrial environment.
TL;DR: Six independent polymerase chain reactions are used for amplification of the entire sequence of the two toxin genes tcdA and tcdB of several Clostridium difficile strains and detected restriction site polymorphisms which are distributed all over the genes.
Abstract: We have used six independent polymerase chain reactions (A1–A3 and B1–B3) for amplification of the entire sequence of the two toxin genes tcdA and tcdB of several Clostridium difficile strains. With this approach we have detected (1) restriction site polymorphisms which are distributed all over the genes, and (2) deletions that could be found only in tcdA. Characteristic differences between strains were mainly focused to the 5′ third of tcdB (B1 fragment) and/or the 3′ third of tcdA (A3 fragment). The possible use of our approach for typing of C. difficile toxin genes is discussed.
TL;DR: The paleogeographical and paleoclimatological data, in combination with the physiological requirements of Proteus, strongly suggest that these animals invaded the caves, at least in the NW parts of their ranges, only after the last glaciations within the last 10,000 years.
Abstract: Approximately 250 localities of the nominal species Proteus anguinus Laurenti 1768 have been evaluated and listed. The species is limited to the Dinaric Karst; it ranges from the Isonzo-Soĉa River in southeastern Venezia Giulia, Italy, through the southern half of Slovenia, southern Croatia, and parts of Bosnia and Hercegovina, to the Trebisnica River in eastern Hercegovina. In some regions, populations have been extinguished or endangered by pollution or human-induced hydrographical changes. The distribution of Proteus is compared with those of some cave Crustacea: Troglocaris (Crustacea: Decapoda), Monolistra, and Titanethes (Crustacea: Isopoda). The similarity of distribution patterns within this ecologically diverse assemblage supports their paleogeographic rather than ecological foundation. The paleogeographical and paleoclimatological data, in combination with the physiological requirements of Proteus, strongly suggest that these animals invaded the caves, at least in the NW parts of their ranges, only after the last glaciations, within the last 10,000 years. It is suggested that the high heterozygosity of populations can best be explained by fusion of some locally restricted immigration waves. The close morpho- logical similarity of nearly all populations of Proteus is probably due to the convergent evolution of previously differentiated populations (or even species) after their withdrawal underground.
Nastetih je približno 250 nahajalisĉ moĉerila ali ĉloveske ribice (Proteus anguinus Laurenti 1768), vse so v Dinarskem krasu med Soĉo-Isonzo v severovzhodni Julijski Beneĉiji (Venezia Giulia) in Trebinjem v Hercegovini. Areal zajema majhen kosĉek sverovzhodne Italije, južno Slovenijo, južno Hrvasko, dele Bosne in Hercegovine. Ponekod so bile populacije uniĉene ali vsaj moĉno ogrožene zaradi onesnaženja ali umetnih hidrografskih sprememb. Razsirjenost moĉerila primerjam z nekaterimi jamskimi raki: jamsko kozico (Troglocaris Dormitzer; Crustacea: Decapoda), jamskimi ježki (Monolistra Gerstaecker) in jamskimi mokricami (Titanethes Schioedte; Crustacea: Isopoda). Podobni vzorci razsirjenosti znotraj te ekolosko raznolike skupine kažejo, da so pogojeni paleogeografsko in ne ekolosko. Paleogeografski in paleoklimatoloski podatki, skupaj z moĉerilovimi fizioloskimi zahtevami, kažejo, da so se te živali vselile v podzemlje, vsaj v severozahodnih delih svojih arealov, sele po zadnjih poledenitvah, torej v zadnjih 10.000 letih. Domnevam, da visoko heterozigotnost populacij zlahka razložimo z zlivanjem veĉ vselitvenih valov. Velika morfoloska podobnost med skoraj vsemi moĉerilovimi populacijami je najbrž posledica konvergentne evolucije zaradi prilagajanja na podzemlje; te so bile poprej lahko že morfolosko razliĉne, morda pa so celo diferencirane v veĉ vrst.
TL;DR: In this article, the authors compared the effectiveness of two abatement compounds, clinoptilolite and De-Odorase®, when used in broiler production and found no statistically significant reduction in odour concentration or odour emission rate for either of the additives used.
TL;DR: In this paper, a simple method for the non-linear static analysis of complex building structures subjected to monotonically increasing horizontal loading (push-over analysis) is presented, which is designed to be a part of new methodologies for the seismic design and evaluation of structures.
Abstract: A simple method for the non-linear static analysis of complex building structures subjected to monotonically increasing horizontal loading (push-over analysis) is presented. The method is designed to be a part of new methodologies for the seismic design and evaluation of structures. It is based on the extension of a pseudo-three-dimensional mathematical model of a building structure into the non-linear range. The structure consists of planar macroelements. For each planar macroelement, a simple bilinear or multilinear base shear%top displacement relationship is assumed. By a step-by-step analysis an approximate relationship between the global base shear and top displacement is computed. During the analysis the development of plastic hinges throughout the building can be monitored. The method has been implemented into a prototype computer program. In the paper the mathematical model, the base shear%top displacement relationships for different types of macroelements, and the step-by-step computational procedure are described. The method has been applied for the analysis of a symmetric and an asymmetric variant of a seven-storey reinforced concrete frame-wall building, as well as for the analysis of a complex asymmetric 21-storey reinforced concrete wall building. The influence of torsion on structural behaviour is discussed.
TL;DR: In this paper, the Particles from Gas Saturated Solutions (PGSS) was used to improve technological characteristics of the poorly water soluble calcium antagonist nifedipine and coprecipitates of PEG 4000 were prepared and evaluated.
TL;DR: The toxicity of industrial wastewater to the mixed bacterial culture, algae, and crustacea was caused mainly by formaldehyde, but for fish the presence of phenol in the wastewater proved to be the significant reason for toxicity.
Abstract: The toxicity of pure phenol, formaldehyde, and industrial wastewater, containing phenol and formaldehyde, from a resin production plant was evaluated using aquatic organisms from different taxonomic groups Test organisms included mixed bacterial culture, unicellular green algae Scenedesmus quadricauda (Turp) Breb, crustacea Daphnia pulex de Geer (daphnids), and fish Oncorhynchus mykiss Call, 1990 (rainbow trout)
TL;DR: In this paper, the authors study perturbed Brownian motions, which behave exactly as linear Brownian motion except when they hit their past maximum or/and maximum where they get an extra push.
Abstract: We study `perturbed Brownian motions', that can be, loosely speaking, described as follows: they behave exactly as linear Brownian motion except when they hit their past maximum or/and maximum where they get an extra `push'. We define with no restrictions on the perturbation parameters a process which has this property and show that its law is unique within a certain `natural class' of processes. In the case where both perturbations (at the maximum and at the minimum) are self-repelling, we show that in fact, more is true: Such a process can almost surely be constructed from Brownian paths by a one-to-one measurable transformation. This generalizes some results of Carmona-Petit-Yor and Davis. We also derive some fine properties of perturbed Brownian motions (Hausdorff dimension of points of monotonicity for example).
TL;DR: It is demonstrated that the host immune system is essential for obtaining cures after electrochemotherapy with cis-platin, and a high percentage of tumor cures was achieved in immunocompetent mice, but none in immunodeficient mice.
TL;DR: In this paper, the role of ribbon thermal properties and thickness in critical heat flux (CHF) was investigated using 50 data sets and data sets available in the literature, and a practical criterion was proposed for sizing noninsulated ribbon heaters without significant conductance/capacitance effects.