Showing papers by "University of Ljubljana published in 1991"
TL;DR: In this article, the authors generalized Posner's theorem to arbitrary C*-algebras and extended it to C *-algebraic linear operators on a Banach space (see, e.g., [1], [2], [3] and [4] ).
Abstract: A well-known theorem of E. Posner [10] states that if the composition d1d2 of derivations d1d2 of a prime ring A of characteristic not 2 is a derivation, then either d1 = 0 or d2 = 0. A number of authors have generalized this theorem in several ways (see e.g. [1], [2], and [5], where further references can be found). Under stronger assumptions when A is the algebra of all bounded linear operators on a Banach space (resp. Hilbert space), Posner's theorem was reproved in [3] (resp. [12]). Recently, M. Mathieu [8] extended Posner's theorem to arbitrary C*-algebras.
384 citations
06 Mar 1991
TL;DR: The algorithm of the 'naive' Bayesian classifier (that assumes the independence of attributes) is extended to detect the dependencies between attributes to optimize the tradeoff between the 'non-naivety' and the reliability of approximations of probabilities.
Abstract: In the paper the algorithm of the 'naive' Bayesian classifier (that assumes the independence of attributes) is extended to detect the dependencies between attributes. The idea is to optimize the tradeoff between the 'non-naivety' and the reliability of approximations of probabilities. Experiments in four medical diagnostic problems are described. In two domains where by the experts opinion the attributes are in fact independent the semi- naive Bayesian classifier achieved the same classification accuracy as naive Bayes. In two other domains the semi-naive Bayesian classifier slightly outperformed the naive Bayesian classifier.
363 citations
TL;DR: Upper and lower bounds on the diameter and the mean distance inG in terms ofλ2, the second smallest eigenvalue of the difference Laplacian matrix of a graphG, are derived.
Abstract: It is well-known that the second smallest eigenvalue? 2 of the difference Laplacian matrix of a graphG is related to the expansion properties ofG. A more detailed analysis of this relation is given. Upper and lower bounds on the diameter and the mean distance inG in terms of? 2 are derived.
319 citations
TL;DR: In this article, a method for the determination of total mercury in coal fly ash by gold amalgamation cold vapour atomic absorption spectrometry (CV-AAS) was optimized.
139 citations
TL;DR: In this paper, a modification of the Weiner index which properly takes into account the symmetry of a graph is proposed and the explicit formulae for the modified Wiener index of path, cycle, complete bipartite, cube and lattice graphs are derived and compared with their standard Wiener Index.
Abstract: A modification of the Weiner index which properly takes into account the symmetry of a graph is proposed. The explicit formulae for the modified Wiener index of path, cycle, complete bipartite, cube and lattice graphs are derived and compared with their standard Wiener index.
133 citations
TL;DR: Long-term therapy with (7 alpha,17 alpha)-17-hydroxy-7-methyl-19-norpregn-5(10)-en-20-yn-3-one (Org OD 14; tibolone, Livial) has no influence on the endometrium in post-menopausal women.
114 citations
TL;DR: The data from the first 50 patients undergoing free TRAM flap breast reconstruction in two units were examined, and it was found that 40 percent of patients were chronic smokers, and 26 percent had low abdominal scars.
Abstract: The data from the first 50 patients undergoing free TRAM flap breast reconstruction in two units were examined. Average patient age was 42 years, and average weight was 62 kg. Forty percent of patients were chronic smokers, and 26 percent had low abdominal scars. Twelve percent exercised their abdominal muscles regularly. Eighteen percent had undergone radical mastectomy, whereas 76 percent had undergone modified radical mastectomy and 6 percent had undergone subcutaneous mastectomy. Postoperative radiotherapy had been given in 16 percent of patients, and 54 percent had received postoperative chemotherapy. The average time from mastectomy was 32 months, whereas six breasts were reconstructed immediately. Average operating time was 5.6 hours, and average blood loss was 2.4 units. Average hospital stay was 11.2 days. Complications included three total flap losses (6 percent) and two partial flap losses (4 percent). Abdominal hernia occurred in two patients (4 percent).
110 citations
TL;DR: An overview of current research on hormonal factors produced by plants and fungi in mycorrhizal associations is presented and growth hormones in roots and their exudates influence the metabolism and growth of fungi.
Abstract: An overview of current research on hormonal factors produced by plants and fungi in mycorrhizal associations is presented. On the one hand, growth hormones in roots and their exudates influence the metabolism and growth of fungi. On the other, fungal hormones influence root morphology, metabolic changes and the growth of the entire plant.
104 citations
TL;DR: A three-dimensional phase diagram is presented to demonstrate the effect of the surface interaction strength, droplet radius, and sample temperature on the stability of phases within a droplet.
Abstract: Possible phases in a nematic liquid crystal confined to a spherical submicrometer droplet embedded in a solid polymer are analyzed in terms of a Landau--de Gennes theory. For a droplet with a radial structure we show that the strength of the nematic-polymer interfacial interaction affects the nematic-paranematic (partially ordered isotropic phase) phase transition and may in addition induce a boundary-layer nematic phase. This boundary layer phase exists only in a narrow (\ensuremath{\sim}0.1 K) temperature interval above the nematic phase for a restricted range of interfacial interactions. Also in the radial structure the degree of ordering is suppressed close to the center of the droplet where a defect is located. As the size of the droplet decreases, the relative size of this region of suppressed ordering increases. Below a critical radius ${\mathit{R}}_{\mathit{c}}$ (0.22 \ensuremath{\mu}m for 4-n-pentyl-4'-cyanobiphenyl), if the surface interaction is above a critical value (${\mathit{q}}_{\mathrm{max}}$=1.85\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$), the transition between the nematic phase and the paranematic phase no longer occurs. A three-dimensional phase diagram is presented to demonstrate the effect of the surface interaction strength, droplet radius, and sample temperature on the stability of phases within a droplet.
90 citations
TL;DR: On plants where visual and airborne acoustic communication can be prevented by leaves, substrateborne vibrational signals perceived by receptors in legs would enhance the likelihood of mate location in N. viridula.
Abstract: We observed mate location behavior in Nezara viridulaon the ivy Hedera helix.The female stays motionless on the plant stem, calling with rhythmic repetitions of her calling song. The male walks on the plant, answering with his calling and courtship songs. On encountering petioles or branching points, the male stops and straddles his legs across the fork. Only after another repetition of the female's call does the male proceed to walk again. This behavior may enable the male to compare the vibrations in the two substrates and choose the stronger one to follow. On plants where visual and airborne acoustic communication can be prevented by leaves, substrateborne vibrational signals perceived by receptors in legs would enhance the likelihood of mate location in N. viridula.
89 citations
TL;DR: Purification, biochemical characterization of sea anemone cytolysins and their mechanisms of action are discussed in the following review article.
Abstract: A number of cytolytic toxins are commonly found in sea anemones. They represent a unique class of animal toxins considering their biochemical characteristics and biological activity. Sea anemone cytolysins are lethal polypeptides which act directly at the membrane level and have potent cardiotoxic activity. Cytotoxic, cytocidal and cytostatic activity were also detected. In general they are basic proteins which usually lack Cys or Met residues. Sea anemone cytolysins are slightly hydrophilic molecules which, however, possess large hydrophobic domains which could insert and span across cell membranes and thus form an ion channel. Cytolytic activity of all except one cytolysin can be prevented by sphingomyelin. Purification, biochemical characterization of sea anemone cytolysins and their mechanisms of action are discussed in the following review article.
TL;DR: The polymorphism of piroxicam has been discussed by many authors, but it is still uncertain in how many polymorphic and pseudopolymorphic modifications it can exist.
TL;DR: It was concluded that penetration of the thrombolytic agent into clots by perfusion is much more effective than by diffusion.
Abstract: Magnetic resonance imaging was employed to study the dependence of clot lysing patterns on two different modes of transport of urokinase into whole blood clots. In one group of clots (nonperfused clots, n1 = 10), access of urokinase to the fibrin network was possible by diffusion only, whereas in the other group (perfused clots, n2 = 10) bulk flow of plasma containing urokinase was instituted through occlusive clots by a pressure difference of 3.7 kPa (37 cm H2O) across 3 cm long clots with a diameter of 4 mm. It was determined separately that this pressure difference resulted in a volume flow rate of 5.05 +/- 2.4 x 10(-2) ml/min through occlusive clots. Perfused clots diminished in size significantly in comparison to nonperfused ones already after 20 min (p less than 0.005). Linear regression analysis of two-dimensional clot sizes measured by MRI showed that the rate of lysis was more than 50-times faster in the perfused group in comparison to the nonperfused group. It was concluded that penetration of the thrombolytic agent into clots by perfusion is much more effective than by diffusion. Our results might have some implications for understanding the differences in lysis of arterial and venous thrombi.
TL;DR: Emergency treatment of complex lower leg injuries gives predictably better results than delayed primary treatment in terms of lower free flap failure rate, higher infection rate, lower number of operations required to obtain the final result, shorter time of hospitalization, short time to bone healing and weightbearing, and lower cost of treatment.
TL;DR: The killing activity of microwaves of 2450 MHz frequency and 325 W, 650 W and 1400 W power on some bacterial strains was investigated and bacterial spores adhering to the tube walls after the aqueous suspension was poured out were reduced in number.
TL;DR: A very sensitive radiochemical neutron activation analysis technique was applied to an exploratory study of uranium levels in hair, urine and blood of non-exposed and occupationally exposed persons, and it was found that hair shows some promise as an indicator of exposure.
TL;DR: In this paper, a finite element formulation of finite deformation analysis of an arbitrarily curved, extensible, shear-flexible, elastic planar beam is presented, which is based on a modified Hu-Washizu variational principle in which exact nonlinear kinematic equations of Reissner [J. Appl. Math. (ZAMP)23, 795-804 (1972)] are taken into account.
TL;DR: In this article, the authors used the ARGUS detector at the e+ e− storage ring DORIS II at DESY to search for direct evidence for b→u transitions through reconstruction of complete events.
TL;DR: In this paper, the effect of metal ions on the oxidation of S(IV) in aqueous solution was studied under controlled experimental conditions (T, pH air flow rate, mixing, concentration of reactant, etc.).
Journal Article•
TL;DR: The histopathology is predominantly tubulointerstitial sclerosis without infiltrates, and the remarkable association with papillary transitional cell carcinoma of the renal pelvis and ureters qualifies BEN as a unique disease.
TL;DR: Exposing the large posterior tibial artery down to the distal third of the lower leg facilitates the use of end-to-side anastomosis and makes the transfer of large muscle flaps to that region more predictable, in part by obviating the need for long vein grafts.
Abstract: A posterior approach to the vessels of the lower leg, with particular emphasis on the posterior tibial artery, is presented as the method of choice for microvascular free-tissue transfer to the region. This approach offers wide exposure, better definition of the zone of injury, appropriate selection of the recipient vessel and of the site of anastomosis, and enough room for microsurgical work. Exposing the large posterior tibial artery down to the distal third of the lower leg facilitates the use of end-to-side anastomosis and makes the transfer of large muscle flaps to that region more predictable, in part by obviating the need for long vein grafts. This exposure leaves no functional and few aesthetic deficits.
TL;DR: In this article, spectroscopic observations of the He II line at 4,686 A from which they deduced a new estimate of the orbital speed of the compact object was obtained, together with the mass ratio of the binary components, derived from X-ray observations.
Abstract: THE unusual galactic object SS433 is well known because of the periodic red and blueshifts, corresponding to velocities of 50,000 kms–1, of some of its emission lines1,2. It is now believed to be a binary system that emits two oppositely directed precessing jets moving with a speed of 0.26c. The jets are produced and controlled by an accretion disk, probably geometrically thick, around a compact object whose nature is still controversial. Several arguments have been advanced21–23suggesting that it is a black hole. Here we report spectroscopic observations of the He II line at 4,686 A from which we deduce a new estimate of the orbital speed of the compact object. Together with the mass ratio of the binary components, derived from X-ray observations, we find that the compact object is a neutron star, not a black hole. Analysis of the double-peaked profile of the He II line suggests that it is emitted by the accretion disk (or its corona), which is partly obscured by an opaque wind from the hot-spot region.
TL;DR: In this article, it was shown that a spectrum-preserving surjective additive map Φ from B (X) to B (Y) is either of the form Φ (F )=ATA -1 for a linear isomorphism A of X onto Y or Φ(T)=BT ∗ B ∗ X ∗ onto Y.
TL;DR: In this paper, the authors show that wave packets restricted to a finite region of spacetime are not a nuisance, but just the contrary, and they have the physical interpretation in the fact that an observer perceives a world line event by event, as his experience of "now" proceeds in spacetime.
Abstract: The relativistic quantum mechanics with Lorentz-invariant evolution parameter and indefinite mass is a very elegant theory. But it cannot be derived by quantizing the usual classical relativity in which there is the mass-shell constraint. In this paper the classical theory is modified so that it remains Lorentz invariant, but the constraint disappears; mass is no longer fixed—it is an arbitrary constant of motion. The quantization of this unconstrained theory gives the relativistic quantum mechanics in which wave functions are localized and normalized in spacetime. Though many authors have published good works in support for such a localization in time, the latter has been generally considered as problematic. Here I show that wave packets restricted to a finite region of spacetime are not a nuisance, but just the contrary. They have the physical interpretation in the fact that an observer perceives a world line event by event, as his experience of “now” proceeds in spacetime. Quantum mechanically this means that at a certain value of the evolution parameter τ the event is most probably to occur within the spacetime region around {ie1005-1} occupied by the wave packet; at later value of τ the position {ie1005-2}—and hence the time coordinate t—of the wave packet is changed. This is closely related to the interpretation of quantum mechanics in general.
TL;DR: In this paper, the authors consider the dimension of a space L of nilpotents on F n and give sufficient conditions for triangularizability and give examples of irreducible spaces, and give a necessary and sufficient condition for all linear combinations of a given set of operators to be nilpotent.
TL;DR: In this article, the ARGUS detector at the DESY storage ring was used to measure the production of mesons in B decays and in nonresonante+e− annihilation around 10.6 GeV.
Abstract: Using the ARGUS detector at thee+e− storage ring DORIS II at DESY, we have measured the inclusive production ofD0,D+ andD*(2010)+ mesons inB decays and in nonresonante+e− annihilation around 10.6 GeV. The inclusive branching ratios forB decays toD0,D+ andD*+ mesons are found to be (52.2±8.2±3.5)%, (27.2±6.3±3.5)% and (34.8±6.0±3.5)% respectively. Thus,D0 andD+ production account for about 70% of the charm produced inB decays, neglectingb→u contributions to the total width. The production cross sections and momentum spectra for continuume+e− annihilation are also presented.
TL;DR: For locally finite infinite graphs the following analytic invariants and properties are considered: the spectrum of the transition and difference Laplacian matrix, amenability and the Kazhdan property (T).
TL;DR: The results obtained confirm the fact that the non-Newtonian pseudoplastic behaviour of the fermentation broth was due to the presence of mycelial pellets.
Abstract: A large number of submerged citric acid fermentations in a beet molasses substrate was studied. The development of Aspergillus niger from conidia to pellets was followed. Rheological characteristics of the fermentation broth including the pellets were determined. The results obtained confirm the fact that the non-Newtonian pseudoplastic behaviour of the fermentation broth was due to the presence of mycelial pellets. The most significant changes in rheological properties occurred during the period of maximal citric acid production and increase in biomass.