Showing papers by "University of Warsaw published in 1992"

The Discernibility Matrices and Functions in Information Systems

Abstract: We introduce two notions related to any information system, namely the discernibility matrix and discernibility function. We present some properties of these notions and as corollaries we obtain several algorithms for solving problems related among other things to the rough definability, reducts, core and dependencies generation.

Electron- and muon-neutrino content of the atmospheric flux.

Abstract: Neutrino interactions from a 7.7 kton yr exposure of the IMB-3 detector are analyzed. A total of 935 contained events radiating over {similar to}50 MeV of {hacek C}erenkov-equivalent energy and consistent with atmospheric neutrino interactions are identified. Of these, 610 have a single {hacek C}erenkov ring. Single-ring interactions are efficiently separated into those containing a showering particle (produced mainly by {nu}{sub {ital e}}) and those containing a nonshowering particle (produced mainly by {nu}{sub {mu}}). In the momentum range 100{lt}{ital p}{sub {ital e}}{lt}1500 MeV/{ital c} and 300{lt}{ital p}{sub {mu}}{lt}1500 MeV/{ital c}, the fraction of nonshowering events is 0.36{plus minus}0.02(stat){plus minus}0.02(syst). Based on detailed models of neutrino production and interaction, a fraction of 0.51{plus minus}0.01(stat){plus minus}0.05(syst) is expected. This deficit of nonshowering, or excess of showering, events relative to the total is supported by an independent analysis of muon decay signals. In the same sample 33{plus minus}2(stat)% of events are accompanied by one or more muon decays, while 43{plus minus}1(stat)% are expected. Further studies that could reduce systematic errors and discover the cause of these discrepancies are suggested.

The Optical Gravitational Lensing Experiment

Abstract: The technical features are described of the Optical Gravitational Lensing Experiment, which aims to detect a statistically significant number of microlensing events toward the Galactic bulge. Clusters of galaxies observed during the 1992 season are listed and discussed and the reduction methods are described. Future plans are addressed.

Spectral Theory, Zeta Functions and the Distribution of Periodic Points for Collet-Eckmann Maps

Abstract: We study unimodal interval mapsT with negative Schwarzian derivative satisfying the Collet-Eckmann condition |DTn(Tc)|≧Kλcn for some constantsK>0 and λc>1 (c is the critical point ofT). We prove exponential mixing properties of the unique invariant probability density ofT, describe the long term behaviour of typical (in the sense of Lebesgue measure) trajectories by Central Limit and Large Deviations Theorems for partial sum processes of the form\(S_n = \Sigma _{i = 0}^{n - 1} f(T^i x)\), and study the distribution of “typical” periodic orbits, also in the sense of a Central Limit Theorem and a Large Deviations Theorem.

Matrix isolation IR spectroscopy of tautomeric systems and its theoretical interpretation: 2-hydroxypyridine/2(1H)-pyridinone

Abstract: Prototropic tautomerism of a model system of 2-hydroxypyridine/2(1H)-pyridinone has been investigated in low-temperature inert matrices and in the gas phase. The ratio of tautomer concentrations, [hydroxy]:[oxo], for the 2-pyridinone sample deposited in Ar or N 2 matrices was estimated as 2.80:1 and 2.99:1, respectively. A similar ratio of tautomers was observed in the gas phase. The matrix and gas-phase infrared spectra of2-hydroxypyridine and 2(1H)-pyridinone are reported

Nonparaxial design of generalized axicons

Abstract: The geometric law of energy conservation is utilized in evaluating the phase transmittance function for axicons with arbitrary distribution of the on-axis intensity. Several simple analytical solutions are presented, and a computer-generated holographic version of the uniform-intensity axicon is examined.

Homotopy classification of self-maps of BG via G-actions

Abstract: To complete the classification of self-maps of BG (Theorem 4.2), it remains to prove Theorem 4.1, i.e., to show that the higher limits of certain functors n 1H 2: f p(G) Z(p-Wall vanish and that H0(Mp(G); f i) has the expected value. In this section, these limits H*(Mp(G); Hi) will be calculated in the "easy" cases, when G is a simply connected classical group (i.e., one of the groups SU(n), Sp(n), or Spin(n)), or when i = 2. The computation of H*(Mp(G); Hi) for the simply connected exceptional Lie groups will be put off until Section 6. We begin with some general properties of higher limits. Let 6 be any small discrete category. It is convenient, when dealing with higher limits of functors on -, to let 4-moldenote the category of contravariant functors from v to Ad. Then for any F e W-muok, we can identify

Single evoked potential reconstruction by means of wavelet transform

Abstract: We would like to propose a method of single evoked potential (EP) extraction free from assumptions and based on a novel approach -- the wavelet representation of the signal Wavelets were introduced by Grossman and Morlet in 1984 The method is based on the multiresolution signal decomposition Wavelets are already used for speech recognition, geophysics investigations and fractal analysis This method seems to be a useful improvement upon Fourier Transform analysis, since it provides simultaneous information on frequency and time localization of the signal We would like to introduce wavelet formalism for the first time to brain signal analysis One of the most important problems in this field is the analysis of evoked potentials This signal has an amplitude several times smaller than EEG, therefore stimulus-synchronized averaging is commonly used This method is based on several assumptions Namely it is postulated that: 1) EP are characterized by a deterministic repeatable pattern, 2) EEG has purely stochastic character, 3) EEG and EP are independent These assumptions have been challenged eg the variability of the EP pattern was demonstrated by John (1973) by means of factor analysis In view of the works of Sayers et al (1974) and Basar (1988) EP reflects the reorganization of the spontaneous activity under the influence of a stimulus and it is connected with the redistribution of EEG phases Several attempts to overcome the limitation of the averaging method have been made Heintze and Kunkel (1984) used an autoregressive moving average (ARMA) model to extract evoked potentials from 2 segments This was possible under two condiitons: high signal to noise ratio and clear separation of the EEG and EP spectra These assumptions are not easy to fulfill, though Cerutti et al (1987) modeled background EEG activity by means of an AR process and event related brain activity by ARMA In this way they were able to find a filter extracting single EP Nevertheless, their method was not quite free of assumptions, since they since they used averaged EP to define their ARMA filter In the following we shall briefly describe the method of the multiresolution decomposition and we will apply it to the analysis and reconstruction of single evoked potentials

Investigation of the unusual magnetic spiral arrangement in BiFeO3

Abstract: In the ferroelectric-antiferromagnet, BiFeO3, the cycloidal spiral arrangement of the magnetic moments of the Fe3+ ions whose length is 620 A was confirmed. This magnetic ordering remains up to the Neel temperature (643K).

Turonian through Santonian deposits of the Central Polish Uplands; their facies development, inoceramid paleontology and stratigraphy

Abstract: Stratigraphy, inoceramid paleontology and facies characteristics of the Turonian through Santonian deposits of the Central Polish Uplands are presented, on the basis of which 17 inoceramid zones are recognized and their position against the ammonite standard division is discussed. Apart from the Middle/Upper Santonian and Santonian/Campanian boundary all other stage and substage boundaries are well recognizable with the inoceramid fauna. Most of the inoceramids, comprising about 40 species, assigned to six genera, are monographed. Two species from the Turonian-Coniacian boundary interval are described as new: Mytiloides turonicus sp. n. and Inoceramus vistulensis sp. n. The Mytiloides labiatus group is thoroughly treated and particular members are discussed, to show that M. suhmytiloides (SEITZ) and M. subhercynicus (SEITZ), the widely cited species of this group, are invalid and thus should be rejected. The names Mytiloides opalensis sensu SEITZ (non BšSE) and M. duplicostatus sensu KAUFFMAN (non ANDERSON) are younger synonyms of M. kossmati (HElNZ). A revision of the whole genus Cremnoceramus is also presented. The stratigraphic scheme applied to the Turonian through Santonian deposits of the Central Polish Uplands allows to solve some regional problems, and to construct a unified chronostratigraphic facies scheme for the southern part of the epicontinental areas in Poland. The facies characteristics combined with the paleotectonic setting of the studied area is the base of the distinguishing of the four geotectonic-facies regions: the Circum-Sudetic Trap Basins, the Cracow Swell, the Danish Polish Trough, and the Russian Chalk Sea. The evolution of the studied areas during Turonian through Santonian time is assembled to indicate the primary role of tectonic movements of the Subhercynian phase of the Alpine orogeny.

On Weighted T-Systems

Abstract: Structure theory is a branch of net theory devoted to investigate the relationship between the structure and the behaviour of net system models. Many of its powerful results have been derived for some subclasses of ordinary net systems. The aim of this contribution is to draw a general perspective of the structure theory for a subclass with Marked Graph-like underlying graph but allowing weights: weighted T-graphs (WTG). Weights are convenient to properly model systems with bulk services and arrivals. Properties of WTG and the corresponding weighted T-systems (WTS) are presented at three different levels: purely structural (e.g. in consistent WTG conservativeness is equivalent to strong connectedness), inter-relationships between the structure and the behaviour (e.g. structural liveness and boundedness is equivalent to consistency and strong connectedness) and liveness and reachability characterizations (e.g. deciding liveness is linear wrt. the 1-norm of the unique minimal T-semiflow of a consistent, even unbounded, WTS). Classical results for Marked Graphs can be derived as corollaries. Nevertheless, even in live and consistent WTS, important properties of Marked Graphs do not hold (e.g. P-semiflows based characterization of reachability).

A method to study ``equilibration'' in nucleus-nucleus collisions

Abstract: A method to study “equilibration level” of a system created in high energy nucleus-nucleus collisions is proposed. The method is based on the fact that the correlation between momentum distribution and particle multiplicity observed in nucleon-nucleon interactions can be also measured in nucleus-nucleus collisions. It is argued that the magnitude of the residual correlation can be used as a measure of the system “equilibration level”. The method is effective even when changes of the “equilibration level” do not modify the inclusive distribution. The quantitative estimate of the effect to be measured is given. Finally, questions arising in practical application of the method are discussed.

Domain Decomposition Algorithms with Small Overlap

Abstract: Numerical experiments have shown that two-level Schwarz methods often perform very well even if the overlap between neighboring subregions is quite small. This is true to an even greater extent for a related algorithm, due to Barry Smith, where a Schwarz algorithm is applied to the reduced linear system of equations that remains after the variables interior to the subregions have been eliminated. In this paper, a supporting theory is developed.

Phase retardation of the uniform-intensity axilens.

Abstract: A method for determining the phase-retardation function of the uniform-intensity axilens is discussed and compared with that of an earlier publication [Opt. Lett. 16, 523 (1991)]. Within the presented formulation good agreement is achieved between the geometrical-optics prediction and the numerically evaluated diffraction integral.

The effect of phosphate deficiency on mitochondrial activity and adenylate levels in bean roots

Abstract: Bean plants (Phaseolus vulgaris) were grown for 16–20 days with or without phosphate in Knop nutrient medium. It was found in previous experiments that for roots grown on a Pi-deficient medium respiration is mainly carried out by the cyanide-insensitive pathway. Mitochondria isolated from—Pi, roots had poor respiratory control and their respiration exhibited 62% inhibition by cyanide and was inhibited (30%) by salicylhydroxamic acid (SHAM). In contrast, mitochondria obtained with control (+Pi) roots had respiratory control and ADP/O ratios typical for succinate as the substrate; their respiration was inhibited to 95% by cyanide and insensitive to SHAM. The integrity of mitochondrial membranes was similar in both types of mitochondria. Cytochrome oxidase activity, however, was about 20% lower in -Pi mitochondria, but the cytochrome composition was the same in both types of mitochondria. The cytochrorae pathway was not operating at full capacity in mitochondria isolated from—Pi roots but the alternative oxidation pathway participated in a great part in mitochondrial respiration, similar to in vivo whole roots. The participation of the non-phosphorylating., alternative pathway decreased the respiratory control ratio in mitochondria and had an effect on the total adenine nucleotide pool and energy charge values which were lower (16 and 13% respectively) in -Pi roots. About 50% lower ADP and 20% lower ATP levels were observed whereas AMP levels were several times higher.

Search for muon neutrino oscillations with the Irvine-Michigan-Brookhaven detector.

Abstract: Muon neutrinos produced as a result of cosmic-ray interactions with the atmosphere are used to search for {nu}{sub {mu}} oscillations into {nu}{sub {tau}} by comparing the measured rate of upward-going muons in the Irvine-Michigan-Brookhaven detector with the expected rate. In addition, the ratio of upward-going muons which stop in the detector to those which exist is used to search for deviations from the expected energy spectrum. This latter technique is free of flux and cross-section normalization uncertainties. No evidence for oscillations is found. 90% C.L. limits on {delta}{ital m}{sup 2} are derived in the range (1--2){times}10{sup {minus}4} eV{sup 2} for sin{sup 2}2{theta}{gt}0.5.

Coherent states and geometric quantization

Abstract: Based on the concept of generalized coherent states, a theory of mechanical systems is formulated in a way which naturally exhibits the mutual relation of classical and quantum aspects of physical phenomena.

Significance of bacterial ectoenzymes in aquatic environments

Abstract: The report presents studies on temporal and spatial variations of kinetics (Vmax and Km) of bacterial ectoenzyme activity (β-glucosidase - βGlc, leucine aminopeptidase - Leu-amp) in the naturally eutrophic Pluβsee βGlc and Leu-amp activity were positively correlated with the flux of polymeric materials (polysaccharides, proteins) in the lake βGlc activity was low when algal populations grew actively, but during the algal bloom breakdown βGlc activity increased rapidly Leu-amp displayed the highest rates of activity in the epilimnion and was tightly coupled to bacterial production The synthesis of studied ectoenzymes was under control of a repression/derepression mechanism The significance of ectoenzymes for the transformation and bacterial utilization of organic matter, and their role in the microbial loop in aquatic environments is discussed

Some remarks on the daugavet equation

Abstract: We show that direct sums in /( and /oo sense of Banach spaces that satisfy the Daugavet Equation ( 1 ) also satisfy it. We also show that most uniform algebras satisfy ( 1 ) for weakly compact operators.

Dynamical symmetries, multiclustering, and octupole susceptibility in superdeformed and hyperdeformed nuclei

Abstract: Spectroscopy of superdeformed nuclear states opens up an exciting possibility to probe new properties of the nuclear mean field. In particular, the unusually deformed atomic nucleus can serve as a microscopic laboratory of quantum-mechanical symmetries of a three-dimensional harmonic oscillator. The quantum numbers and coupling schemes characteristic of weakly deformed systems are expected to be modified in the superdeformed world. New classification schemes can be directly related to certain geometrical properties of the nuclear shape.