Showing papers by "University of Warsaw published in 1998"

Evidence for oscillation of atmospheric neutrinos

Abstract: We present an analysis of atmospheric neutrino data from a 33.0 kton yr (535-day) exposure of the Super-Kamiokande detector. The data exhibit a zenith angle dependent deficit of muon neutrinos which is inconsistent with expectations based on calculations of the atmospheric neutrino flux. Experimental biases and uncertainties in the prediction of neutrino fluxes and cross sections are unable to explain our observation. The data are consistent, however, with two-flavor ${\ensuremath{ u}}_{\ensuremath{\mu}}\ensuremath{\leftrightarrow}{\ensuremath{ u}}_{\ensuremath{\tau}}$ oscillations with ${sin}^{2}2\ensuremath{\theta}g0.82$ and $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}l\ensuremath{\Delta}{m}^{2}l6\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}3}\mathrm{eV}{}^{2}$ at 90% confidence level.

Continuum Solvent Studies of the Stability of DNA, RNA, and Phosphoramidate−DNA Helices

Abstract: We apply continuum solvent models to investigate the relative stability of A- and B-form helices for three DNA sequences, d(CCAACGTTGG)2, d(ACCCGCGGGT)2, and d(CGCGAATTCGCG)2, a phosphoramidate-mod...

Measurements of the solar neutrino flux from Super-Kamiokande's first 300 days

Abstract: The first results of the solar neutrino flux measurement from Super-Kamiokande are presented. The results shown here are obtained from data taken between 31 May 1996, and 23 June 1997. Using our measurement of recoil electrons with energies above 6.5 MeV, we infer the total flux of ${}^{8}\mathrm{B}$ solar neutrinos to be $2.42\ifmmode\pm\else\textpm\fi{}0.06(\mathrm{stat}{)}_{\ensuremath{-}0.07}^{+0.10}(\mathrm{syst})\ifmmode\times\else\texttimes\fi{}{10}^{6}\mathrm{cm}{}^{\ensuremath{-}2}{\mathrm{s}}^{\ensuremath{-}1}$. This result is consistent with the Kamiokande measurement and is 36% of the flux predicted by the BP95 solar model. The flux is also measured in 1.5 month subsets and shown to be consistent with a constant rate.

Introduction to Quantum Groups

Abstract: We give an elementary introduction to the theory of algebraic and topological quantum groups (in the spirit of S. L. Woronowicz). In particular, we recall the basic facts from Hopf (*-) algebra theory, theory of compact (matrix) quantum groups and the theory of their actions on compact quantum spaces. We also provide the most important examples, including the classification of quantum SL(2)-groups, their real forms and quantum spheres. We also consider quantum SLq(N)-groups and quantum Lorentz groups.

The plant cDNA LCT1 mediates the uptake of calcium and cadmium in yeast

Abstract: Nonessential metal ions such as cadmium are most likely transported across plant membranes via transporters for essential cations. To identify possible pathways for Cd2+ transport we tested putative plant cation transporters for Cd2+ uptake activity by expressing cDNAs in Saccharomyces cerevisiae and found that expression of one clone, LCT1, renders the growth of yeast more sensitive to cadmium. Ion flux assays showed that Cd2+ sensitivity is correlated with an increase in Cd2+ uptake. LCT1-dependent Cd2+ uptake is saturable, lies in the high-affinity range (apparent KM for Cd2+ = 33 μM) and is sensitive to block by La3+ and Ca2+. Growth assays demonstrated a sensitivity of LCT1-expressing yeast cells to extracellular millimolar Ca2+ concentrations. LCT1-dependent increase in Ca2+ uptake correlated with the observed phenotype. Furthermore, LCT1 complements a yeast disruption mutant in the MID1 gene, a non-LCT1-homologous yeast gene encoding a membrane Ca2+ influx system required for recovery from the mating response. We conclude that LCT1 mediates the uptake of Ca2+ and Cd2+ in yeast and may therefore represent a first plant cDNA encoding a plant Ca2+ uptake or an organellar Ca2+ transport pathway in plants and may contribute to transport of the toxic metal Cd2+ across plant membranes.

Structure and Spectra of Three-Dimensional ( H 2 O ) n Clusters, n = 8 , 9 , 10

Abstract: The vibrational OH stretch spectra have been measured for size-selected pure water clusters $({\mathrm{H}}_{2}\mathrm{O}{)}_{n}$, in the size range $n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}8--10$. Comparison between experiment and calculations suggests that the spectra originate from a small number of ``microcrystalline'' structures, based on the cubic octamer. The $n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}8$ spectra are caused by two isomers of ${D}_{2d}$ and ${S}_{4}$ symmetry. The proposed lowest energy nonamer and decamer structures are derived from the octamer by insertion of one and two two-coordinated molecules, respectively, into the cube edges.

Simulations of H2O Solid, Liquid, and Clusters, with an Emphasis on Ferroelectric Ordering Transition in Hexagonal Ice

Abstract: Simulations are presented of H2O ice, liquid, and clusters (H2O)n n ≤ 7. The first part is devoted to orientational energetics of ice. Ordinary hexagonal ice is orientationally disordered; a transi...

Common Phase Diagram for Antiferromagnetism in La 2 − x Sr x CuO 4 and Y 1 − x Ca x Ba 2 Cu 3 O 6 as Seen by Muon Spin Rotation

Abstract: By zero field muon spin rotation we studied the antiferromagnetic correlations in the single layer system La{sub 2{minus}x}Sr {sub x}CuO{sub 4} and the bilayer system Y{sub 1{minus}x}Ca {sub x}Ba{sub 2}Cu{sub 3}O{sub 6} . We observe a common phase diagram as a function of hole doping per plane with two distinct transitions in the magnetic ground state. The first transition marks the border between the 3D antiferromagnetic state and a disordered state with short ranged correlations. The second transition marks a distinct change in the magnetic correlations at the onset of superconductivity. {copyright} {ital 1998} {ital The American Physical Society}

Nonlocality of the Einstein-Podolsky-Rosen state in the Wigner representation

Abstract: We demonstrate that the Wigner function of the Einstein-Podolsky-Rosen state, though positive definite, provides direct evidence of the nonlocal character of this state. The proof is based on an observation that the Wigner function describes correlations in the joint measurement of the phase-space displaced parity operator.

Spin asymmetries A1 and structure functions g1 of the proton and the deuteron from polarized high energy muon scattering

Abstract: We present the final results of the spin asymmetries A1 and the spin structure functions g1 of the proton and the deuteron in the kinematic range 0.0008

Minkowski functionals used in the morphological analysis of cosmic microwave background anisotropy maps

Abstract: We present a novel approach to quantifying the morphology of cosmic microwave background (CMB) anisotropy maps. As morphological descriptors, we use shape parameters known as Minkowski functionals. Using the mathematical framework provided by the theory of integral geometry on arbitrary curved supports, we point out the differences in their characterization and interpretation in the case of flat space. With the restrictions of real data — such as pixelization and incomplete sky coverage, to mention just a few — in mind, we derive and test unbiased estimators for all Minkowski functionals. Various examples, among them the analysis of the four-year COBE DMR data, illustrate the application of our method.

Global and Local Aromaticity in Porphyrins: An Analysis Based on Molecular Geometries and Nucleus‐Independent Chemical Shifts

Abstract: Two pyrrole rings participate in the aromatic structure of porphyrin. Hence, a 22 π-electron description is better than the usual [18]annulene representation. The dianion and the metal complex system favor different electronic structures.

SERS spectra of poly(3‐hexylthiophene) in oxidized and unoxidized states

Abstract: Surface enhanced Raman scattering (SERS) is being increasingly used for the study of the structural properties of conducting polymer thin films. It is generally accepted that the enhancement process has an electromagnetic origin, arising from the excitation of surface plasmons in the metal support on which the polymer film is deposited. However, the electromagnetic enhancement is also accompanied by a chemical process, for which available experimental data are scarce. The chemical process originates from the increase in the polarizability of the molecules at the metal surface under the action of the incident radiation, which leads to the formation of new chemical bonds with the atoms of the metal support. The present work was devoted to the study of the SERS spectra of poly(3-hexylthiophene) deposited on rough Ag and Au supports by evaporating the solvent from a solution of known concentration. The experiments revealed the existence of a chemical surface effect. The results obtained show that the SERS spectra depend on the oxidizing properties of the metal surface and on the nature of the solvent. This dependence is explained by the existence of some interfacial reactions that lead to the formation of interface compounds of the type MeX (Me=Ag or Au, X=Cl or O). The SERS measurements reported here reveal an increase in the intensities of the Raman lines, accompanied by a modification of the corresponding intensity ratios, when the degree of doping is increased. It was observed for the first time by SERS spectroscopy that the doping of 3-PHT with FeCl3 leads to the appearance of a state of disorder in the structure of the macromolecular chain, as a result of steric hindrance effects. © 1998 John Wiley & Sons, Ltd.

Odd-even staggering of nuclear masses : pairing or shape effect?

Abstract: The odd-even staggering of nuclear masses was recognized in the early days of nuclear physics. Recently, a similar effect was discovered in other finite fermion systems, such as ultrasmall metallic grains and metal clusters. It is believed that the staggering in nuclei and grains is primarily due to pairing correlations (superconductivity), while in clusters it is caused by the Jahn-Teller effect. We find that, for light- and medium-mass nuclei, the staggering has two components. The first originates from pairing while the second, comparable in magnitude, has its roots in the deformed mean field.

Towards adaptive calculus of granules

Abstract: An importance of the idea of granularity of knowledge for approximate reasoning has been stressed in Pawlak (1997) and Zadeh (1966, 1997). We address here the problem of synthesis of adaptive decision algorithms and we propose an approach to this problem based on the notion of a granule which we develop in the framework of rough mereology. This framework does encompass both rough and fuzzy set theories. Our approach may be applied in the problems of approximate synthesis of complex objects (solutions) in distributed systems of intelligent agents.

Properties of the YAP : Ce scintillator

Abstract: Light yield, light pulse shape due to γ-rays and α-particles, energy and time resolutions for a 10 × 10 × 5 mm 3 YAB crystal coupled to the XP2020Q photomultiplier were studied. The measured light output of 17000 ± 850 photons/MeV includes a correction for the calibrated quantum efficiency of the XP2020Q. The fast component of the light pulse with the decay time constant of 26.7 ± 0.12 ns also shows a finite rise time described approximately by the time constant of 380 ± 45 ps. The YAP crystal which was studied exhibited an energy resolution of 5.7% for 662 keV γ-rays fron a 137 Cs source. This very good energy resolution is due to a low intrinsic energy resolution of 3.4%. These characteristics, together with a good time resolution for 60 Co γ-rays of 160 ps measured at the threshold of 1 MeV, suggest a broad range of applications for the YAP scintillator.

Evidence for Non-Gaussianity in the COBE DMR 4 Year Sky Maps

Abstract: We introduce and study the distribution of an estimator for the normalized bispectrum of the cosmic microwave background (CMB) anisotropy. We use it to construct a goodness-of-fit statistic to test the co-added 53 and 90 GHz COBE Diffuse Microwave Radiometer 4 year maps for non-Gaussianity. Our results indicate that Gaussianity is ruled out at the confidence level in excess of 98%. This value is a lower bound, given all the investigated systematics. The dominant non-Gaussian contribution is found near the multipole of order l=16. Our attempts to explain this effect as caused by the diffuse foreground emission from the Galaxy have failed. We conclude that unless there exists a microwave foreground emission that spatially correlates with neither the DIRBE nor Haslam maps, the cosmological CMB anisotropy is genuinely non-Gaussian.

Effects of inflation on the subjective value of delayed and probabilistic rewards

Abstract: In the years prior to 1994, there were very high rates of inflation in Poland, and the zloty depreciated relative to the U.S. dollar. However, the new zloty, introduced in 1995, was associated with greatly decreased rates of inflation and provided a more stable currency. We report a series of three experiments that take advantage of these changes to examine the effects of inflation on the subjective value of delayed and probabilistic rewards. Subjects were Polish citizens familiar with both zlotys and dollars. The first two experiments, conducted in 1994, used dollars and old zlotys, and the third experiment, conducted in 1996, used dollars and new zlotys. In all three experiments, the dollar and zloty rewards were of equivalent worth, according to the then current exchange rates. In Experiment 1, subjects chose between immediate and delayed rewards and, in Experiment 2, chose between certain and probabilistic rewards. The subjective value of a delayed reward was greater when its amount was specified in dollars than when it was specified in old zlotys. In contrast, the currency in which a reward was specified had no effect on the subjective value of probabilistic rewards. The results of these two experiments suggest a selective effect of inflation on decisions involving delayed rewards. This was verified in the third experiment, in which, using new zlotys, no differences in discounting were observed between the two currencies with either probabilistic or delayed rewards. Importantly, in all three experiments, the discounting of both delayed and probabilistic rewards was well described by the same simple mathematical model, suggesting that similar decision-making processes underlie both phenomena. However, the present results argue against a single-process theory in which the discounting of probabilistic rewards is derived from the discounting of delayed rewards.

DIRECT Distances to Nearby Galaxies Using Detached Eclipsing Binaries and Cepheids. I. Variables in the Field M31B

Abstract: We have undertaken a long-term project, DIRECT, to obtain the direct distances to two important galaxies in the cosmological distance ladder—M31 and M33—using detached eclipsing binaries (DEBs) and Cepheids. While rare and difficult to detect, DEBs provide us with the potential to determine these distances with an accuracy better than 5%. The extensive photometry obtained in order to detect DEBs provides us with good light curves for the Cepheid variables. These are essential to the parallel project to derive direct Baade-Wesselink distances to Cepheids in M31 and M33. For both Cepheids and eclipsing binaries, the distance estimates will be free of any intermediate steps. As a first step in the DIRECT project, between 1996 September and 1997 January we obtained 36 full nights on the Michigan-Dartmouth-MIT Observatory 1.3 m telescope and 45 full/partial nights on the F. L. Whipple Observatory 1.2 m telescope to search for DEBs and new Cepheids in the M31 and M33 galaxies. In this paper, first in a series, we present the catalog of variable stars, most of them newly detected, found in the field M31B [(α, δ) = (1120, 4159), J2000.0]. We have found 85 variable stars: 12 eclipsing binaries, 38 Cepheids, and 35 other periodic, possible long-period or nonperiodic variables. The catalog of variables, as well as their photometry and finding charts, is available via anonymous ftp and the World Wide Web.

Asymptotic Completeness in Quantum Field Theory. A Class of Galilei-Covariant Models

Abstract: 0. Introduction 192 1. General Definitions 195 1.1. Hilbert spaces 195 1.2. Homomorphisms of commutative C∗and W ∗-algebras 196 1.3. Permutations 197 1.4. Clusters 197 1.5. Cartesian and tensor products associated with a cluster 198 1.6. Clusterings 198 1.7. Cartesian and tensor products associated with a clustering 199 2. Distinguishable Particles 199 2.1. Elementary particles 199 2.2. Clusters of elementary particles 199 2.3. Asymptotic particles 201 2.4. Clusters of asymptotic particles 201 2.5. Identification operator 202 2.6. Existence of the asymptotic velocity 202 2.7. Short-range case 202 2.8. Long-range case – free region 203 2.9. Long-range case – asymptotic interacting Hamiltonian 204 2.10. Long-range case – modified wave operators 205 3. Second Quantization in the Category of Sets 206 3.1. Second quantization of a set 206 3.2. “Third quantization” of a set 207 3.3. Permutations that preserve species 207 3.4. Clusters with composition n ∈ Γ(E) 208 3.5. Permutations that preserve species and a clustering 208 3.6. Clusterings associated with k ∈ Γ(E) 210 3.7. Identification operators 210 4. Second Quantization in the Category of Z2-Hilbert Spaces 211 4.1. Fock spaces 211