April 2002 arXiv papers — page 19

Wolfgang Knospe, Ludger Santen, Andreas Schadschneider, Michael Schreckenberg

Empirical observations and theoretical studies indicate that the overall travel-time of vehicles in a traffic network can be optimized by means of ramp metering control systems. Here, we present an analysis of traffic data of the highway network of North-Rhine-Westfalia in order to identify and characterize the sections of the network which limit the perform

S. J. Potashnik, K. C. Ku, R. Mahendiran, S. H. Chun

We examine the Mn concentration dependence of the electronic and magnetic properties of optimally annealed Ga1-xMnxAs epilayers for 1.35% < x < 8.3%. The Curie temperature (Tc), conductivity, and exchange energy increase with Mn concentration up to x ~ 0.05, but are almost constant for larger x, with Tc ~ 110 K. The ferromagnetic moment per Mn ion decreases

Y. -M Choi, D. -S. Lee, R. Czerw, P. -W. Chiu

The temperature dependent thermoelectric power (TEP) of boron and nitrogen doped multi-walled carbon nanotube mats has been measured showing that such dopants can be used to modify the majority conduction from p-type to n-type. The TEP of boron doped nanotubes is positive, indicating hole-like carriers. In contrast, the nitrogen doped material exhibits negat

P. Grassberger, L. Yang

Heat conduction in 1-dimensional anharmonic systems is anomalous in the sense that the conductivity κscales with a positive power of the system size, κ~ L^α. In two dimensions, previous simulations and theoretical arguments gave a logarithmic divergence. For rectangular systems of size L_\| x L_\perp there should be a cross-over from the 2-d to the 1-d behav

A. Santos, S. B. Yuste, M. Lopez de Haro

A simple recipe to derive the compressibility factor of a multicomponent mixture of d-dimensional additive hard spheres in terms of that of the one-component system is proposed. The recipe is based (i) on an exact condition that has to be satisfied in the special limit where one of the components corresponds to point particles; and (ii) on the form of the ra

Takenori Fujii, Ichiro Terasaki, Takao Watanabe, Azusa Matsuda

We investigated the in-plane anisotropy on the resistivity and thermopower of Bi2-xPbxSr2Co2Oy single crystals, which have a misfit structure between the hexagonal CoO2 layer and the rock salt Bi2Sr2O4 layer. The resistivity and thermopower show significantly large anisotropy, which exceeds two at maximum. This anisotropy would come from the anisotropic pseu

David E. Logan, Nigel L. Dickens

The recently introduced local moment approach (LMA) is extended to encompass single-particle dynamics and transport properties of the Anderson impurity model at finite-temperature, T. While applicable to arbitrary interaction strengths, primary emphasis is given to the strongly correlated Kondo regime (characterized by the T=0 Kondo scale $ω_{\rm K}$). In pa

Xiang-Yu Ge, Mark D. Gould, Jon Links, Huan-Qiang Zhou

This is a reply to a comment by P. Schlottmann and A.A. Zvyagin.

A. A. Rovenchak

The calculation of the He4 energy and specific heat is carried out in a wide temperature range within the two-time temperature Green functions approach. The approximation improving the random phase approximation is developed providing the correct behaviour of the calculated specific heat at the temperatures $0 < T/T_c < 0.65$ and $T/T_c> 1.32$ where $T_c$ st

Philip D. Mannheim

In the standard cosmological paradigm cosmic acceleration is to only be a very recent (viz. $z \leq 1$) phenomenon, with the universe being required to be decelerating at all higher redshifts. We suggest that this particular expectation of the standard model is to be viewed as a quite definitive test not only of the model itself but also of the fine-tuning a

Henry C. Ferguson, Mark Dickinson, Casey Papovich

With SIRTF and NGST in the offing, it is interesting to examine what the stellar populations of z~3 galaxies models imply for the existence and nature of Lyman-break galaxies at higher redshift. To this end, we ``turn back the clock&#39;&#39; on the stellar population models that have been fit to optical and infrared data of Lyman-break galaxies at z~3. The

Frederick M. Walter, James Lattimer

New astrometric analysis of four WFPC2 images of the isolated neutron star RX J185635-3754 show that its distance is 117 +/- 12 pc, nearly double the originally published distance. At the revised distance, the star&#39;s age is 5 x 10^5 years, its space velocity is about 185 km/s, and its radiation radius inferred from thermal emission is approximately 15 km

Henry C. Ferguson, Mark Dickinson, Casey Papovich

Near-infrared observations of Lyman-break galaxies at redshifts z~3 are beginning to provide constraints on ages, star-formation histories, dust content, metallicities, and stellar masses. At present, uncertainties of more than an order of magnitude are typical for many of these parameters. It is nonetheless interesting to ask what the stellar-population mod

J. C. B. Papaloizou

We calculate global $m=1$ modes with low pattern speed corresponding to introducing a finite eccentricity into a protoplanetary disc. We consider disc models which are either isolated or contain one or two protoplanets orbiting in an inner cavity. Global modes that are strongly coupled to inner protoplanets are found to have disc orbits which tend to have ap

Robert E. Rutledge, Lars Bildsten, Edward F. Brown, George G. Pavlov

We obtained four Chandra/ACIS-S observations beginning two weeks after the end of the November 2000 outburst of the neutron star (NS) transient Aql X-1. Over the five month span in quiescence, the X-ray spectra are consistent with thermal emission from a NS with a pure hydrogen photosphere and R_{\infty}=15.9+{0.8}-{2.9} (d/5 kpc) km at the optically implied

Jeremy Darling, Riccardo Giovanelli

We present the 1667 MHz OH megamaser luminosity function derived from a single flux-limited survey. The Arecibo Observatory OH megamaser (OHM) survey has doubled the number of known OH megamasers, and we list the complete catalog of OHMs detected by the survey here, including three redetections of known OHMs. OHMs are produced in major galaxy mergers which a

Dipak Munshi

The weak lensing surveys have the potential to probe directly the clustering statistics of dark matter in the universe. Recent studies have shown that it is possible to predict analytically the whole probability distribution function (pdf) and the bias associated with the collapsed objects in the highly non-linear regime using the hierarchical ansatz. We ext

E. Antonello, D. Fugazza, L. Mantegazza

The frequency--period distribution and other properties of Cepheids in IC 1613 are discussed and compared with those of stars in our Galaxy (Milky Way), LMC, SMC, M31 and M33. Taking into account the observational limitations and related incompleteness, it is concluded that the frequency-period distribution of Cepheids in IC 1613 is similar to that of SMC; w

L. R. Yungelson, G. Nelemans, E. P. J. van den Heuvel

We study the formation of neon-enriched donor stars in ultracompact X-ray binaries (orbital periods P<80 min) and show that their progenitors have to be low-mass (0.3 - 0.4 solar mass) ``hybrid&#39;&#39; white dwarfs (with CO cores and thick helium mantles). Stable mass transfer is possible if in the initial stages of mass exchange mass is lost from the syst

Rosemary F. G. Wyse

The large galaxies in the Local Group, while all disk galaxies, have diverse stellar populations. A better understanding of these differences, and a physical understanding of the causes, requires more detailed study of the older populations. This presents a significant challenge to GAIA but the scientific returns are also significant.

S. Howell, B. Gansicke, P. Szkody, E. Sion

We present new HST/STIS observations of the short-period dwarf novae LL And and EF Peg during deep quiescence. We fit stellar models to the UV spectra and use optical and IR observations to determine the physical parameters of the whitedwarfs in the systems, the distances to the binaries, and the properties of thesecondary stars. Both white dwarfs are relati

Dong Lai, Wynn C. G. Ho

We have recently shown that in a highly magnetized neutron star atmospheric plasma, vacuum polarization can induce resonant conversion of photon polarization modes via a mechanism analogous to MSW neutrino oscillation. In a recent paper Ozel has dismissed this mode conversion effect as ``mistakes&#39;&#39;. Here we explain why our arguments/calculations of t

Chien Y. Peng

The double nucleus geometry of M31 is currently best explained by the eccentric disk hypothesis of Tremaine, but whether the eccentric disk resulted from the tidal disruption of an inbounding star cluster by a nuclear black hole, or by an m=1 perturbation of a native nuclear disk, remains debatable. I perform detailed 2-D decomposition of the M31 double nucl

S. J. LaRoque, J. E. Carlstrom, E. D. Reese, G. P. Holder

We present an interferometric measurement of the Sunyaev-Zel&#39;dovich effect (SZE) at 1 cm for the galaxy cluster Abell 2163. We combine this data point with previous measurements at 1.1, 1.4, and 2.1 mm from the SuZIE experiment to construct the most complete SZE spectrum to date. The intensity in four wavelength bands is fit to determine the central Comp

Roni Harnik, Hitoshi Murayama, Aaron Pierce

Anomaly mediation of supersymmetry breaking solves the supersymmetric flavor problem thanks to its ultraviolet-insensitivity. However, it suffers from two problems: sleptons have negative masses-squared, and there are likely bulk moduli that spoil the framework. Here, we present the first fully ultraviolet-insensitive model of anomaly mediation with positive

W. Hofstetter, J. I. Cirac, P. Zoller, E. Demler

The experimental realizations of degenerate Bose and Fermi atomic samples have stimulated a new wave of studies of quantum many-body systems in the dilute and weakly interacting regime. The intriguing prospective of extending these studies into the domain of strongly correlated phenomena is hindered by the apparent relative weakness of atomic interactions. T

Daniel Kabat, Kimyeong Lee, Erick Weinberg

We study the response of the QCD vacuum to strong magnetic fields, using a potential model for the quark-antiquark interaction. We find that production of spin-polarized u-ubar pairs is energetically favorable for fields B > B_crit \sim 10 GeV^2. We contrast the resulting u-ubar condensate with the quark condensate which is present at zero magnetic field, an

D. A. Demir, Keith A. Olive, M. B. Voloshin

We analyze the forward-backward asymmetry of the decays B to (pi,K) l^+ l^- with l = mu or tau in the framework of the constrained minimal supersymmetric standard model. We find that, the asymmetry is enhanced at large tan beta and depends strongly on the sign of the mu parameter. For mu > 0, the asymmetry is typically large and observable whereas for mu < 0

D. V. Khveshchenko, A. G. Yashenkin

We carry out a quantum mechanical analysis of the behavior of nodal quasiparticles in the vortex line liquid phase of planar d-wave superconductors. Applying a novel path integral technique we calculate a number of experimentally relevant observables and demonstrate that in the low-field regime the quasiparticle scattering rates deduced from photoemission an

Andrew J. Tolley, Neil Turok

We consider quantum field theory on a spacetime representing the Big Crunch/Big Bang transition postulated in the ekpyrotic or cyclic cosmologies. We show via several independent methods that an essentially unique matching rule holds connecting the incoming state, in which a single extra dimension shrinks to zero, to the outgoing state in which it re-expands

Joshua J. Friess, Tao Han, Dan Hooper

We construct the open-string scattering amplitudes for neutrino-gluon collisions and evaluate the high energy neutrino-nucleon scattering cross section via string state excitations in the TeV string-scale scenario. We find that the neutrino-gluon scattering is the dominant contribution, 5-10 times larger than neutrino-quark processes, though black hole produ

Clare Dunning

We study the renormalisation group flows between minimal W models by means of a new set of nonlinear integral equations which provide access to the effective central charge of both unitary and nonunitary models. We show that the scaling function associated to the nonunitary models is a nonmonotonic function of the system size.

H. Baer, C. Balazs, A. Belyaev, R. Dermisek

Recently, extra dimensional SUSY GUT models have been proposed in which compactification of the extra dimension(s) leads to a breakdown of the gauge symmetry and/or supersymmetry. We examine a particular class of higher-dimensional models exhibiting supersymmetry and SU(5) or SO(10) GUT symmetry. SUSY breaking occurs on a hidden brane, and is communicated to

Tuson Park, M. B. Salamon, C. U. Jung, Min-Seok Park

The specific heat of polycrystalline Mg$^{11}$B$_{2}$ has been measured with high resolution ac calorimetry from 5 to 45 K at constant magnetic fields. The excess specific heat above T$_{c}$ is discussed in terms of Gaussian fluctuations and suggests that Mg$^{11}$B$_{2}$ is a bulk superconductor with Ginzburg-Landau coherence length $ξ_{0}=26$ Å. The transi

Carlo Angelantonj, Augusto Sagnotti

This review is devoted to open strings, and in particular to the often surprising features of their spectra. It follows and summarizes developments that took place mainly at the University of Rome ``Tor Vergata&#39;&#39; over the last decade, and centred on world-sheet aspects of the constructions now commonly referred to as ``orientifolds&#39;&#39;. Our pre

N. Menci, A. Cavaliere, A. Fontana, E. Giallongo

We develop a semi-analytic model of hierarchical galaxy formation with an improved treatment of the evolution of galaxies inside dark matter haloes. We take into account not only dynamical friction processes building up the central dominant galaxy, but also binary aggregations of satellite galaxies inside a common halo described using the kinetic Smoluchowsk

Dmitri Diakonov, Martin Maul

We calculate the one-loop effective action of the SU(2) Yang-Mills theory for center-vortex configurations, both in 3d and 4d. We find that in both cases there are minima of the effective action, corresponding to vortices of the transverse size approximately 4/g_3^2 and 1.7/Lambda_MS, respectively. The values of the effective actions at the minima are negati

M. Caselle, M. Hasenbusch

We study the finite size corrections for the magnetization and the internal energy of the 2d Ising model in a magnetic field by using transfer matrix techniques. We compare these corrections with the functional form recently proposed by Delfino and LeClair-Mussardo for the finite temperature behaviour of one-point functions in integrable 2d quantum field the

L. G. Softova

The present paper deals with singular integrals with variable Caldero&#39;n-Zygmund type kernels satisfying mixed homogeneity condition. The continuity of these operators in The Lebesgue spaces is well studied by Fabes and Rivie&#39;re. Our goal is to extend their results in generalized Morrey spaces with weight satisfying suitable dabbling and integral cond

KLOE Collaboration

We have measured the branching ratio BR(phi --> pi0 pi0 gamma) with the KLOE detector using a sample of ~5x10^7 phi decays. phi mesons are produced at DAFNE, the Frascati phi-factory. We find BR(phi --> pi0 pi0 gamma) = (1.09 +- 0.03 (stat) +- 0.05 (syst))x10^-4. We fit the two--pion mass spectrum to models to disentangle contributions from various sources.

The KLOE Collaboration

In a sample of 5.3x10^7 phi-decays observed with the KLOE detector at the Frascati phi-factory Dafne we find 605 eta pi0 gamma events with eta --> gammaγand 197 eta pi0 gamma events with eta --> pi+ pi- pi0. The decay phi --> eta pi0 gamma is dominated by the process phi --> a0 gamma. From a fit to the eta pi0 mass spectrum we find BR(phi --> ao(980) gamma)=

J. Eisert, S. Scheel, M. B. Plenio

We show that no distillation protocol for Gaussian quantum states exists that relies on (i) arbitrary local unitary operations that preserve the Gaussian character of the state and (ii) homodyne detection together with classical communication and postprocessing by means of local Gaussian unitary operations on two symmetric identically prepared copies. This i

G. Kaniadakis, A. M. Scarfone

The paper deals with a planar particle system obeying a generalized exclusion principle (EP) and governed, in the mean field approximation, by a nonlinear Schroedinger equation. We show that the EP involves a mathematically simple and physically transparent mechanism, which allows the genesis of quantum vortices in the system. We obtain in a closed form the

A. Krzywicki

We try to explain the apparently &#34;thermal&#34; shape of the inclusive transverse momentum spectrum. We conjecture that prior to the collision, parton-parton interactions generate a kind of a stochastic process driving the one-particle spectrum within a hadron towards the thermal shape it would have in a classical gas. We illustrate this idea, which might

Matthias Schröter, Klaus Kassner, Ingo Rehberg, Josep Claret

In thin-layer electrodeposition the dissipated electrical energy leads to a substantial heating of the ion solution. We measured the resulting temperature field by means of an infrared camera. The properties of the temperature field correspond closely with the development of the concentration field. In particular we find, that the thermal gradients at the el

Mitsuhiro Matsumoto, Koji Hukushima, Hajime Takayama

Spin-glass (SG) and chiral-glass (CG) orderings in three dimensional (3D) Heisenberg spin glass with and without magnetic anisotropy are studied by using large-scale off-equilibrium Monte Carlo simulations. A characteristic time of relaxation, which diverges at a transition temperature in the thermodynamic limit, is obtained as a function of the temperature

Benedicte Ponsot

Three explicit and equivalent representations for the monodromy of the conformal blocks in the SL(2,C)/SU(2) WZNW model are proposed in terms of the same quantity computed in Liouville field theory. We show that there are two possible fusion matrices in this model. This is due to the fact that the conformal blocks, being solutions to the Knizhnik-Zamolodchik

Hideki Maeda, Tomohiro Harada, Hideo Iguchi, Naoya Okuyama

We have investigated spherically symmetric spacetimes which contain a perfect fluid obeying the polytropic equation of state and admit a kinematic self-similar vector of the second kind which is neither parallel nor orthogonal to the fluid flow. We have assumed two kinds of polytropic equations of state and shown in general relativity that such spacetimes mu

Hans C. Fogedby, Vakhtang Poutkaradze

We discuss the influence of white noise on a generic dynamical finite-time-singularity model for a single degree of freedom. We find that the noise effectively resolves the finite-time-singularity and replaces it by a first-passage-time or absorbing state distribution with a peak at the singularity and a long time tail exhibiting power law or stretched expon

The Small x Collaboration, Bo Andersson, S. Baranov, J. Bartels

The aim of this paper is to summarize the general status of our understanding of small x physics. It is based on presentations and discussions at an informal meeting on this topic held in Lund, Sweden, in March 2001. This document also marks the founding of an informal collaboration between experimentalists and theoreticians with a special interest in small

Yuan-Xiu Miao, Hui Zhai, Hong-Yu Yang, Lee Chang

In this paper we investigate the macroscopic quantum tunnelling and the phase coherence property of the rotating Bose-Einstein condensates in both static and dynamic cases by using the mean field theory.

Shinji Mukohyama

Brane cosmology driven by the tachyon rolling down to its ground state is investigated. We adopt an effective field theoretical description for the tachyon and Randall-Sundrum type brane world scenario. After formulating basic equations, we show that the standard cosmology with a usual scalar field can mimic the low energy behavior of the system near the tac

H. W. Lee, Y. S. Myung

We study the dynamical behavior of the dilaton in the background of three-dimensional Kerr-de Sitter space which is inspired from the low-energy string effective action. The perturbation analysis around the cosmological horizon of Kerr-de Sitter space reveals a mixing between the dilaton and other fields. Introducing a gauge (dilaton gauge), we can disentang

Edward R. Abraham, Melissa M. Bowen

The horizontal stirring properties of the flow in a region of the East-Australian Current are calculated. A surface velocity field derived from remotely sensed data, using the Maximum Cross Correlation method, is integrated to derive the distribution of the finite-time Lyapunov exponents. For the region studied (between latitudes 36 S and 41 S and longitudes

Yun Wang, Daniel E. Holz, Dipak Munshi

We present an approximate form for the weak lensing magnification distribution of standard candles, valid for all cosmological models, with arbitrary matter distributions, over all redshifts. Our results are based on a universal probability distribution function (UPDF), $P(η)$, for the reduced convergence, $η$. For a given cosmological model, the magnificati

Matthias Jakob, Yonatan Abranyos, Janos A. Bergou

We suggest a quantum measurement model in an ion trap which specifies the probability distribution of two, distinct internal ground states of a trapped four-level ion. The external degrees of motion of the four-level ion constitute the meter which, in turn, is coupled to the environment by engineered reservoirs. In a previous publication, a similar measureme

M. G. Tashkova, A. M. Miteva, S. G. Donev

We study the influence of the different choice of unit cells on the Bloch solutions of Schrçdinger equation for one-dimensional periodic Kronig- Penney models with rectangular potential barriers or potential wells and partially constant effectiv mass. We obtain generalized Kronig-Penney relations for bulk states and exact expressions for the corresponding pe

Yuki Tokunaga

Lo and Chau showed that an ideal quantum coin flipping protocol is impossible. The proof was simply derived from the impossibility proof of quantum bit commitment. However, the proof still leaves the possibility of a quantum coin flipping protocol with arbitrary small bias. In this paper, we show that a quantum coin flipping protocol with arbitrary small bia

Gerald L. Fitzpatrick

Heretofore unrecognized (i.e., &#34;hidden&#34;) Lorentz-invariant vector observables in the fermion sector (i.e., flavor-defining fermion &#34;coordinates&#34;) are shown to indirectly explain most, if not all, of the so-called &#34;accidental&#34; (internal) symmetries associated with fundamental fermions (quarks and leptons), by explaining quark and lepto

Sidi Cherkawi Benzahra

I added an Imaginary term by hand to the proper time in special theory of relativity, and I wanted to see what will happen to it if I tried to get the time dialation relationship. I found that this added imaginary term of time does not have to be zero.

Danielle Morel

The mass shifts of experimentally well-known baryons due to meson-baryon self-energy loops are calculated, and their impact on the observed splitting of the baryon spectrum is studied. Configuration-mixed wave functions adapted from a `relativized&#39; model are used with the 3P0 model to provide predictions for the strength and analytical momentum dependenc

G. A. Souliotis, M. Veselsky, G. Chubarian, L. Trache

The cross sections and velocity distributions of projectile-like fragments from the reaction of 25 MeV/nucleon 86Kr + 64Ni have been measured using the MARS recoil separator at Texas A&M, with special emphasis on the neutron rich isotopes. Proton-removal and neutron pick-up isotopes have been observed with large cross sections. A model of deep-inelastic tran

R. Festa, A. Mazzino, D. Vincenzi

A novel view for the emergence of chaos in Lorenz-like systems is presented. For such purpose, the Lorenz problem is reformulated in a classical mechanical form and it turns out to be equivalent to the problem of a damped and forced one dimensional motion of a particle in a two-well potential, with a forcing term depending on the ``memory&#39;&#39; of the pa

Kenichiro Aoki, Dimitri Kusnezov

An explicit relation between the dimensional loss ($ΔD$), entropy production and transport is established under thermal gradients, relating the microscopic and macroscopic behaviors of the system. The extensivity of $ΔD$ in systems with bulk behavior follows from the relation. The maximum Lyapunov exponents in thermal equilibrium and $ΔD$ in non-equilibrium

L. Biferale, M. Cencini, A. Lanotte, D. Vergni

We present a numerical study of two-dimensional turbulent flows in the enstrophy cascade regime, with different large-scale forcings and energy sinks. In particular, we study the statistics of more-than-differentiable velocity fluctuations by means of two recently introduced sets of statistical estimators, namely {\it inverse statistics} and {\it second orde

Kunihiko Kaneko

The prevalence of Milnor attractors has recently been reported in a class of high-dimensional dynamical systems. We study how this prevalence depends on the number of degrees of freedom by using a globally coupled map and show that the basin fraction of Milnor attractors increases drastically around 5-10 degrees of freedom, saturating for higher numbers of d

Ramon Huerta, Lev S. Tsimring

A generalization of the standard susceptible-infectious-removed (SIR) stochastic model for epidemics in sparse random networks is introduced which incorporates contact tracing in addition to random screening. We propose a deterministic mean-field description which yields quantitative agreement with stochastic simulations on random graphs. We also analyze the

Daniel D. Ferrante

This work has the purpose of applying the concept of Geometric Calculus (Clifford Algebras) to the Fibre Bundle description of Quantum Mechanics. Thus, it is intended to generalize that formulation to curved spacetimes [the base space of the fibre bundle in question] in a more natural way.

L. Birke, J. Froehlich

A general form of the ``Wick rotation&#39;&#39;, starting from imaginary-time Green functions of quantum-mechanical systems in thermal equilibrium at positive temperature, is established. Extending work of H. Araki, the role of the KMS condition and of an associated anti-unitary symmetry operation, the ``modular conjugation&#39;&#39;, in constructing analyti

Tamas Tasnadi

After investigating by examples the unusual and striking elementary properties of the Penrose tilings and the Arnold cat map, we associate a finite symbolic dynamics with finite grammar rules to each of them. Instead of studying these Markovian systems with the help of set-topology, which would give only pathological results, a noncommutative approximately f

Szymon Zeberski

We prove theorems of the following form: if $A\subseteq {\mathbb R}^2$ is a big set, then there exists a big set $P\subseteq {\mathbb R}$ and a perfect set $Q\subseteq {\mathbb R}$ such that $P\times Q\subseteq A$. We discuss cases where big set means: set of positive Lebesgue measure, set of full Lebesgue measure, Baire measurable set of second Baire catego

Jan van Mill

We answer a question of Juhasz by constructing under CH an example of a locally connected continuum without nontrivial convergent sequences.

Vladimir Uspenskij

Every topological group $G$ has some natural compactifications which can be a useful tool of studying $G$. We discuss the following constructions: (1) the greatest ambit $S(G)$ is the compactification corresponding to the algebra of all right uniformly continuous bounded functions on $G$; (2) the Roelcke compactification $R(G)$ corresponds to the algebra of

Vera Trnkova

We prove that, for every cardinal number $α\geq {\mathfrak c}$, there exists a metrizable space $X$ with $|X|=α$ such that for every pair of quasiorders $\leq_1$, $\leq_2$ on a set $Q$ with $|Q| \leq α$ satisfying the implication $$q \leq_1 q&#39; \implies q \leq_2 q&#39;$$ there exists a system $\{X(q) : q\in Q\}$ of non-homeomorphic clopen subsets of $X$ w

Andrzej Spakowski

Given a cover $\mathcal{B}$ of a quasi-uniform space $Y$ we introduce a concept of lower semicontinuity for multifunctions $F:X\to 2^Y$, called $\mathcal{B}$-lsc. In this way, we get a common description of Vietoris-lsc, Hausdorff-lsc, and bounded-Hausdorff-lsc as well. Further, we examine set-theoretical and vector operations on such multifunctions. We also

Peter Schauenburg

We prove the quasi-Hopf algebra version of the Nichols-Zoeller theorem: A finite-dimensional quasi-Hopf algebra is free over any quasi-Hopf subalgebra.

Lurdes Sousa

In several familiar subcategories of the category ${\mathbb T}$ of topological spaces and continuous maps, embeddings are not pushout-stable. But, an interesting feature, capturable in many categories, namely in categories $\mathcal{B}$ of topological spaces, is the following: For $\mathcal{M}$ the class of all embeddings, the subclass of all pushout-stable

Alexander P. Sostak

We study FTOP(L), a fuzzy category with fuzzy functions in the role of morphisms. This category has the same objects as the category L-TOP of Chang-Goguen L-topological spaces,but an essentially wider class of morphisms - so called fuzzy functions introduced earlier in our joint work with U. Hohle and H. Porst.

Marlon C. Rayburn

This is a survey of compactification extension results and problems for a special class of proximities.

Brian Raines

In this paper we examine the topology of inverse limit spaces generated by maps of finite graphs. In particular we explore the way in which the structure of the orbits of the turning points affects the inverse limit. We show that if $f$ has finitely many turning points each on a finite orbit then the inverse limit of $f$ is determined by the number of elemen

Mila Mrsevic

A Cech closure space $(X,u)$ is a set $X$ with a (Cech) closure operator $u$ which need not be idempotent. Many properties which hold in topological spaces hold in Cech closure spaces as well. The notions of proper (splitting) and admissible (jointly continuous) topologies are introduced on the sets of continuous functions between Cech closure spaces. It is

Mojtaba Moniri, Jafar S. Eivazloo

Given a Dedekind incomplete ordered field, a pair of convergent nets of gaps which are respectively increasing or decreasing to the same point is used to obtain a further equivalent criterion for Dedekind completeness of ordered fields: Every continuous one-to-one function defined on a closed bounded interval maps interior of that interval to the interior of

E. Michael

This note is a survey of $J$-spaces.

Grazyna Kwiecinska

In the paper we investigate Borel classes of multivalued functions of two variables. In particular we generalize a result of Marczewski and Ryll-Nardzewski concerning of real function whose ones of its sections are right-continuous and other ones are of Borel class $α$, into the case of multivalued functions.

Martin Maria Kovar

Problem 540 of J. D. Lawson and M. Mislove in Open Problems in Topology asks whether the process of taking duals terminate after finitely many steps with topologies that are duals of each other. The problem for $T_1$ spaces was already solved by G. E. Strecker in 1966. For certain topologies on hyperspaces (which are not necessarily $T_1$), the main question

A. Iwanik, L. Janos, F. A. Smith

We prove that if $T: X \to X$ is a selfmap of a set $X$ such that $\bigcap \{T^{n}X: n\in N}\}$ is a one-point set, then the set $X$ can be endowed with a compact Hausdorff topology so that $T$ is continuous.

Yasunao Hattori

This is a survey on special metrics. We shall present some results and open questions on special metrics mainly appeared in the last 10 years

Valentin Gutev

The present paper improves a result of V. Gutev and T. Nogura (1999) showing that a space $X$ is topologically well-orderable if and only if there exists a selection for $\mathcal{F}_2(X)$ which is continuous with respect to the Fell topology on $\mathcal{F}_2(X)$. In particular, this implies that $\mathcal{F}(X)$ has a Fell-continuous selection if and only

M. K. Gormley, T. B. M. McMaster

We define a property sub-representability and we give a complete characterisation of sub-representability of posets.

Chris Good, Robin W. Knight, Abdul M. Mohamad

A base $\mathcal{B}$ for a space $X$ is said to be sharp if, whenever $x\in X$ and $(B_n)_{n\inω}$ is a sequence of pairwise distinct elements of $\mathcal{B}$ each containing $x$, the collection $\{\bigcap_{j\le n}B_j:n\inω\}$ is a local base at $x$. We answer questions raised by Alleche et al. and Arhangel$&#39;$ski\uı et al. by showing that a pseudocompac

Eli Glasner

Each topological group $G$ admits a unique universal minimal dynamical system $(M(G),G)$. When $G$ is a non-compact locally compact group the phase space $M(G)$ of this universal system is non-metrizable. There are however topological groups for which $M(G)$ is the trivial one point system (extremely amenable groups), as well as topological groups $G$ for wh

Janos Gerlits, Istvan Juhasz, Lajos Soukup, Zoltan Szentmiklossy

Let us call a function $f$ from a space $X$ into a space $Y$ preserving if the image of every compact subspace of $X$ is compact in $Y$ and the image of every connected subspace of $X$ is connected in $Y$. By elementary theorems a continuous function is always preserving. Evelyn R. McMillan proved in 1970 that if $X$ is Hausdorff, locally connected and Frech

Marton Elekes

We investigate the existence of well-ordered sequences of Baire 1 functions on separable metric spaces.

A. El-Fattah El-Atik, M. E. Abd El-Monsef, E. I. Lashin

Finite topological spaces became much more essential in topology, with the development of computer science. The task of this paper is to study and investigate some properties of such spaces with the existence of an ordered relation between their minimal neighborhoods. We introduce notations and elementary facts known as Alexandroff space. The family of minim

Edwin Duda

This paper is concerned with conditions under which a metric continuum (a compact connected metric space) contains a non-degenerate chainable continuum.

Georgi Dimov, Franco Obersnel, Gino Tironi

In 1975, M. M. Choban introduced a new topology on the set of all closed subsets of a topological space, similar to the Tychonoff topology but weaker than it. In 1998, G. Dimov and D. Vakarelov used a generalized version of this new topology, calling it Tychonoff-type topology. The present paper is devoted to a detailed study of Tychonoff-type topologies on

Dikran Dikranjan

We comment van Douwen&#39;s problems on the Bohr topology of the abelian groups raised in his paper (The maximal totally bounded group topology on G and the biggest minimal G-space for Abelian groups G) as well as the steps in the solution of some of them. New solutions to two of the resolved problems are also given.

Andre de Carvalho

We describe a circle of ideas relating the dynamics of 2-dimensional homeomorphisms to that of 1-dimensional endomorphisms. This is used to introduce a new class of maps generalizing that of Thurston&#39;s pseudo-Anosov homeomorphisms.

V. A. Chatyrko, K. L. Kozlov

An action on a G-space induces uniformities on the phase space. It is shown when the maximal G-compactification of a G-space can be obtained as a completion of the phase space with respect to one of these uniformities. Structure of G-spaces with special actions is investigated.

Bruce S. Burdick

We find some statements in the language of asymmetric topology and continuous partial orders which are equivalent to the statements $κ< \mathfrak m$ or $κ< \mathfrak p$.