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Showing papers by "University of Warsaw published in 1993"


Journal ArticleDOI
TL;DR: A matrix model of an asymptotically free theory with a bound state is solved using a perturbative similarity renormalization group for hamiltonians using a related light-front Fock space operator method.
Abstract: A matrix model of an asymptotically free theory with a bound state is solved using a perturbative similarity renormalization group for hamiltonians. An effective hamiltonian with a small width, calculated including the first three terms in the perturbative expansion, is projected on a small set of effective basis states. The resulting small hamiltonian matrix is diagonalized and the exact bound state energy is obtained with accuracy of order 10%. Then, a brief description and an elementary illustration are given for a related light-front Fock space operator method which aims at carrying out analogous steps for hamiltonians of QCD and other theories.

366 citations


Journal ArticleDOI
Bernardo Adeva1, Shafqat Ahmad2, A. Arvidson3, B. Badelek4  +162 moreInstitutions (22)
TL;DR: In this paper, the spin-dependent structure function g1 p of the proton was measured in deep inelastic scattering of polarized muons off polarized protons, in the kinematic range 0.136±0.011 (stat.)± 0.011(syst.) at Q2 = 10GeV2.

278 citations


Journal ArticleDOI
M. Derrick1, D. Krakauer1, S. Magill1, B. Musgrave1  +459 moreInstitutions (37)
TL;DR: In this article, neutral current scattering of electrons and protons at square-root s = 296 GeV was observed in the ZEUS detector events with a large rapidity gap in the hadronic final state.

211 citations


Journal ArticleDOI
M. Derrick1, D. Krakauer1, S. Magill1, B. Musgrave1  +464 moreInstitutions (37)
TL;DR: In this article, the first measurement of the F 2 structure function in neutral-current, deep inelastic scattering using the ZEUS detector at HERA, the ep colliding beam facility at DESY, was presented.

202 citations


Book ChapterDOI
15 Jun 1993
TL;DR: The paper investigates the generation problem of optimal decision rules with some certainty coefficients based on belief and rough membership functions and shows that the problems of optimal rules generation can be solved by boolean reasoning.
Abstract: In the paper we investigate the generation problem of optimal decision rules with some certainty coefficients based on belief [7] and rough membership functions [6]. We show that the problems of optimal rules generation can be solved by boolean reasoning [2].

194 citations


Journal ArticleDOI
TL;DR: Several domain decomposition methods of Neumann-Neumann type are considered for solving the large linear systems of algebraic equations that arise from discretizations of elliptic problems by finite elements.
Abstract: Several domain decomposition methods of Neumann-Neumann type are considered for solving the large linear systems of algebraic equations that arise from discretizations of elliptic problems by finite elements. We will only consider problems in three dimensions. Several new variants of the basic algorithm are introduced in a Schwarz method framework that provides tools which have already proven very useful in the design and analysis of other domain decomposition and multi-level methods. The Neumann-Neumann algorithms have several advantages over other domain decomposition methods. The subregions, which define the subproblems, only share the boundary degrees of freedom with their neighbors. The subregions can also be of quite arbitrary shape and many of the major components of the preconditioner can be constructed from subprograms available in standard finite element program libraries. In its original form, however, the algorithm lacks a mechanism for global transportation of information and its performance therefore suffers when the number of subregions increases. In the new variants of the algorithms, considered in this paper, the preconditioners include global components, of low rank, to overcome this difficulty. Bounds are established for the condition number of the iteration operator, which are independent of the number of subregions, and depend only polylogarithmically on the number of degrees of freedom of individual local subproblems. Results are also given for problems with arbitrarily large jumps in the coefficients across the interfaces separating the subregions. ©1995 John Wiley & Sons, Inc.

167 citations



Journal ArticleDOI
TL;DR: The results indicated that the type of denitrification carried out by P. denitrificans is not stable and depends on the nutritional composition of the culture medium.
Abstract: The course of denitrification of nitrate in static cultures of Paracoccus denitrificans was studied. Reduction of nitrate to gaseous nitrogen without accumulation of nitrite because of parallel and balanced activities of nitrate and nitrite reductases was observed in nutrient broth. In minimal liquid cultures supplemented with either methanol, acetate, or ethanol as a sole carbon source, substantial amounts of nitrite (up to 70%) accumulated. The reduction in nitrite concentration began just after the transformation of nitrate to nitrite was completed. The addition of some growth factors to minimal media shortened the bacterial biomass doubling time. A correlation coefficient of 0.71 between the doubling time and the amount of accumulated nitrite in cultures was found. My results indicated that the type of denitrification carried out by P. denitrificans is not stable and depends on the nutritional composition of the culture medium.

138 citations


Journal ArticleDOI
TL;DR: In this paper, a psychometric study has been conducted with the aims of revising the structure of temperament as postulated by the Regulative Theory of Temperament (RTT) and constructing an inventory which corresponds to the RTT.
Abstract: A psychometric study has been conducted with the aims of revising the structure of temperament as postulated by the Regulative Theory of Temperament (RTT) and of constructing an inventory which corresponds to the RTT. A starting point for the study was the assumption that temperament refers to formal attributes of behaviour expressed in energetic and temporal characteristics. About 600 items covering 12 characteristics were generated. A study based on linguistic and itemmetric analysis allowed us to reduce the number of items representing the 12 characteristics to a 381-item pool. This set of items served as the basis for distinguishing the temperamental traits and for constructing the inventory: the Formal Characteristics of Behaviour–Temperament Inventory (FCB-TI). A thorough psychometric study and factor analysis of data obtained from over 2000 subjects (both genders, aged from 15 to 80 years) allowed us to distinguish six temperamental traits which have the status of first-order factors. Among them, four–Sensory Sensitivity, Endurance, Emotional Reactivity, and Activity–refer to the energetic aspect of behaviour and two–Briskness and Perseverance–refer to the temporal characteristics. The FCB-TI has satisfactory psychometric characteristics, including Cronbach alpha and stability measures. Studies have shown that the six FCB-TI scales are replica across samples and refer to robust temperament dimensions.

135 citations


Journal Article
TL;DR: In this paper, it was shown that Soboiev functions can be approximated by Cn' functions both in norm and capacity, and a proof of Michael-Ziemer's theorem was given.
Abstract: We get a ciass of pointwise ineq1,ialities for Soboiev functions. As a corollary we obtain a short, proof of Michael-Ziemer's theorem which states that Soboiev functions can be approximated by Cn' functions both in norm and capacity.

115 citations


Journal ArticleDOI
TL;DR: In this article, a high-resolution record of proxy climatic data in central Europe during the final stages of the last deglaciation, derived from the annually laminated sediments of Lake Gościaz (central Poland), was presented.

Journal ArticleDOI
01 Jul 1993-Topology
TL;DR: In this paper, the authors define an s-horseshoe for graphs, in much the same way as for interval maps: there is an interval I and s its subintervals with pairwise disjoint interiors, each of them mapped by fonto the whole I.

Journal ArticleDOI
TL;DR: The FOPI detector as mentioned in this paper is designed for the investigation of central collisions of heavy ions in the energy range up to 2 A GeV at the SIS/ESR accelerator facility at GSI in Darmstadt.
Abstract: At the SIS/ESR accelerator facility at GSI in Darmstadt the 4π-detector system FOPI is under construction at present. It is designed for the investigation of central collisions of heavy ions in the energy range up to 2 A GeV. As phase I of this detector a forward wall has been built and used in various experiments. It comprizes a total number of 764 scintillators with an additional shell of 188 thin ΔE -detectors in front of it and covers the full azimuth of the polar angles from 1° to 30°. The velocity and the nuclear charge of the fragments are determined by a combined time-of-flight and ΔE measurement.

Journal ArticleDOI
TL;DR: In this paper, the authors give an explicit description of certain class of Poisson structures in low dimensions and suggest a possible approach for higher dimensions, which leads to a classification of poisson structures for low dimensions.
Abstract: In the present note we give an explicit description of certain class of Poisson structures. The methods lead to a classification of Poisson structures in low dimensions and suggest a possible approach for higher dimensions.

Journal ArticleDOI
TL;DR: It is shown that the typability problem for each one of these extensions of ML is polynomial-time equivalent to the Semi-Unification Problem and, therefore, undecidable.
Abstract: We study the problem of type-checking functional programs in three extensions of ML. One distinguishing feature of these extensions is that they allow recursive definitions to be polymorphically typed. Although the motivation for these extensions comes from pragmatic considerations of programming language design, we show that the typability problem for each one of these extensions is polynomial-time equivalent to the Semi-Unification Problem and, therefore, undecidable

Journal ArticleDOI
TL;DR: The capacity of Elodea nuttallii (Planch.) St. John and ElodeA canadensis Michx.
Abstract: The capacity of Elodea nuttallii (Planch.) St. John and Elodea canadensis Michx. to remove nitrogen from water was evaluated in laboratory experiment. The growth rate of plants and their effect on the nitrogen level of hypertrophic Lake Zwemlust (the Netherlands) as well as on lake water enriched with nitrogen were investigated. The plants grew best in water enriched with up to 2 mg NH4-Nl−1 and 2 mg NH4-Nl−1 plus 2 mg NO3 Nl−1. During a 14 day experiment, plants absorbed from 75% to 90% of nitrogen. Higher nitrogen concentration than 4 mg l−1 had a negative effect on growth of both species. Elodea nuttallii and E. canadensis prefer NOinf4/p+ over NOinf4/p− when both ions were present in water in equal concentrations.

Journal ArticleDOI
TL;DR: In this paper, it has been found that diesters of phosphoric acid with branched alkyl substituents solubilize polyaniline in its protonated (conducting) state.

Journal ArticleDOI
TL;DR: For a set of helical proteins that have simple native topologies, the native folds of the proteins can be predicted with reasonable accuracy from their sequences alone.

Book ChapterDOI
16 Mar 1993
TL;DR: A new characterization of lambda definability in Henkin models using logical relations defined over ordered sets with varying arity is given, which is simplicity and universality and leads to a decision procedure.
Abstract: We give a new characterization of lambda definability in Henkin models using logical relations defined over ordered sets with varying arity The advantage of this over earlier approaches by Plotkin and Statman is its simplicity and universality Yet, decidability of lambda definability for hereditarily finite Henkin models remains an open problem But if the variable set allowed in terms is also restricted to be finite then our techniques lead to a decision procedure

Journal ArticleDOI
TL;DR: In this paper, the systematics of level energies, as well as dipole, quadrupole and octupole matrix elements are discussed in the framework of models assuming stable octupoles deformation.

Journal ArticleDOI
TL;DR: In this article, a new approach is proposed to the phenomenological study of a generic unified supergravity model, which reduces to the minimal supersymmetric standard model, effectively parametrized in terms of five low energy observables.

Journal ArticleDOI
TL;DR: In this paper, the authors discuss the Higgs scenario in the minimal supersymmetric extension of the Standard Model ate+e− linear colliders operating in the c.m. energy range between 300 and 500 GeV.
Abstract: We discuss the Higgs scenario in the minimal supersymmetric extension of the Standard Model ate+e− linear colliders operating in the c.m. energy range between 300 and 500 GeV. Besides decays of the Higgs particles into ordinary fermions and cascade decays, we analyze also decays into gaugino/Higgsinos and in particular, neutral Higgs decays into the lightest supersymmetric particles which are invisible ifR-parity is conserved. The cross sections for the various production channels of SUSY Higgs particles ine+e− collisions are discussed in detail. The lightest Higgs boson cannot escape detection, and in major parts of the MSSM parameter space all five Higgs particles can be observed.

Journal ArticleDOI
TL;DR: In this paper, an explicitly connected commutator expansion for the average value of an observable in the coupled-cluster theory is derived, which can be used as a basis for size-extensive infinite-order summation techniques.
Abstract: An explicitly connected commutator expansion for the average value of an observable in the coupled-cluster theory is derived. Specifically, it is shown that the expectation value of an operator for the state Ψ, related to the Fermi vacuum Φ by the exponential Ansatz ψ = eT Φ, is expressed as a finite commutator series containing the cluster operator T and an auxiliary operator S, defined by a linear equation involving again a finite commutator series in T. The above result is applied to derive the explicitly connected commutator form of the order-by-order many-body perturbation theory (MBPT) expansion for the expectation values and density matrices. We also show how the commutator expansion derived by us can be used as a basis for size-extensive infinite-order summation techniques. An operator technique of eliminating the nonlocal, “off-energy shell” denominators from MBPT expressions is proposed and applied to obtain compact commutator formulas for the expectation values of one- and two-electron operators through the fourth and third order, respectively, and for the correlation energy through the fifth order of perturbation theory. © 1993 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: Valence band splitting which is reversed relative to the materials with Mn, Co, or Fe indicates a ferromagnetic p-d exchange, observed for the first time in II-VI diluted magnetic semiconductors.
Abstract: We measured free exciton splitting and Faraday rotation of the diluted magnetic semiconductor ${\mathrm{Zn}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Cr}}_{\mathit{x}}$Se (x0.005) and found valence band splitting which is reversed relative to the materials with Mn, Co, or Fe. This fact indicates a ferromagnetic p-d exchange, observed for the first time in II-VI diluted magnetic semiconductors.

Journal ArticleDOI
TL;DR: In this paper, it was shown by measurements of magneto-optical Kerr effect and reflection in magnetic field that unusually large exciton Zeeman splitting plays an essential role in the observed Faraday rotation.

Journal ArticleDOI
TL;DR: In this paper, the ratios of the nucleon structure function in copper to deuterium from two separate experiments were analyzed and it was found that the data are compatible with no integral loss of quark momenta due to nuclear effects.
Abstract: Results are presented on the ratios of the nucleon structure function in copper to deuterium from two separate experiments. The data confirm that the nucleon structure function,F2, is different for bound nucleons than for the quasi-free ones in the deuteron. The redistribution in the fraction of the nucleon's momentum carried by quarks is investigated and it is found that the data are compatible with no integral loss of quark momenta due to nuclear effects.

Journal ArticleDOI
TL;DR: Examination of the relationship between the amount of lead in plant tissues and the level of the root growth inhibition showed that amounts of lead much bigger than those observed in the environment can now easily enter the food chain via plants.

Journal ArticleDOI
TL;DR: In this article, the authors derived coupled-cluster equations for the calculation of the nonexpanded (fully damped) dispersion energy and solved these equations in the ring approximation using the Moller-Plesset expansion in terms of the fluctuation potentials WA and WB for the individual molecules.
Abstract: Coupled-cluster equations for the calculation of the nonexpanded (fully damped) dispersion energy are derived. These equations are solved in the ring approximation using the Moller–Plesset expansion in terms of the fluctuation potentials WA and WB for the individual molecules. Numerical results of high-order perturbative calculations for the He, H2, LiH, H2O, and HF dimers are presented and compared with the converged results computed using the same basis sets. It is found that the convergence of the Moller-Plesset expansion of the dispersion energy in the ring approximation is very fast. The pade approximants still accelerate this already good convergence. For all complexes studied in this paper, the sum of the corrections through the second-order in WA + WB reproduces over 99% of the converged value. The sum of third- and higher-order corrections in the ring approximation is found to be one or two orders of magnitude smaller than the sum of second-order terms not included in the ring approximation and, therefore, may be safely neglected. Thus, it appears that a second-order calculation, which does not require iterating coupled-cluster equations or solving random phase approximation equations, offers the best compromise between accuracy and computational requirements. © 1993 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: A method for constraint region approximation, design centering and yield estimation is introduced by inscribing into the constraint region the largest possible ellipsoid.
Abstract: A method for constraint region approximation, design centering and yield estimation is introduced. Extreme points of the constraint region are identified by inscribing into it the largest possible ellipsoid. Ellipsoid center is the point that centers the design. Ellipsoidal, polytope and second order Taylor series approximation schemes to the constraint region are discussed. Accuracy and implementation of the method are outlined. Two examples testing the method are included and applications to centering, tolerancing and yield estimation are shown. >

Book ChapterDOI
TL;DR: The changes in decomposing material mean thatdetritus in various stages of decomposition differs in its role in trophic dynamics of shore-littoral lake zones, and several types of shore regions as regards detritus sources and retention level are discussed.
Abstract: The importance of detritus varies greatly among shore zones of lakes, but in a large majority of these regions detrital pathways prevail. Aside from a great spatial and seasonal variability, macrophytes and bottom sediments appear to be dominant stores of nutrients in these habitats. Macrophytes hold a central position in nutrient cycling in the shore-littoral lake zones. They are the main source of autochthonous detritus as they prevail in the total biomass of littoral organisms, and they are only rarely available as direct food of consumers. Various processes and interactions determine the role of macrophytes in nutrients dynamics. These are: the intensity of nutrient uptake and translocation, release of nutrients by healthy plants and from decomposing plants, exchange of elements between macrophytes and their periphyton, as well as interception of seston by macrophyte stands. Particular plant species differ in their time of dying and susceptibility to decomposition. The changes in decomposing material (size structure of particles and nutrient content) mean that detritus in various stages of decomposition differs in its role in trophic dynamics of shore-littoral lake zones. Several types of shore regions as regards detritus sources and retention level are discussed.