bluuebunny/crossref_metadata_2025 huggingface dataset:
The genus Arachnomyces
Authors: Malloch D. , Cain R. F.
Published: September 2008

The genus Arachnomyces is redescribed and placed in the family Onygenaceae. Four species are described and illustrated. A. nitidus Massee & Salmon, the type of the genus, was collected on a hay-dung compost in Ontario and compared with the type specimen. The type of A. sulphureus Massee & Salmon was examined. A. peruvianus is a new combination for Anixiopsis peruviana Cain. A. minimus is a new species isolated in pure culture from decayed wood collected in Ontario. The peridium of the cleistothecial ascocarps of Arachnomyces consists of an outer dark layer and an inner hyaline layer and has long appendages (except in A. peruvianus). The asci are globose to subglobose and irregularly disposed. The ascospores are one-celled, oblate, reddish brown, smooth or roughened, without germ pores.
A petrified bark of Cupressaceae from the Upper Cretaceous of Alberta
Authors: Ramanujam C. G. K.
Published: September 2008

A petrified bark of Cupressaceae is described from the Foremost Formation (Upper Cretaceous) near Redcliff in southern Alberta. The bark is named Cupressinocortex albertaense gen. et sp. nov. It is characterized by secondary phloem composed of tangential bands of sieve cells, axial parenchyma, and fibers, and the possession of conspicuous vertical resin canals.
The biological activities of 26 gibberellins in nine plant bioassays
Authors: Crozier A. , Kuo C. C. , Durley R. C. , Pharis R. P.
Published: September 2008

The activities of gibberellins A1–A15, A17–A27 and A8-glucoside are compared, using original and previously published data, in the barley (Hordeum vulgare L.) aleurone α-amylase, Progress No. 9 dwarf pea (Pisum sativum L.), lettuce (Lactuca sativa L.), 'Tan-ginbozu' dwarf rice (Oryza sativa L.), cucumber (Cucumis sativus L.), and the d-1, d-2, d-3, and d-5 maize (Zea mays L.) mutant bioassays. Gibberellins A3 and A7 show high activity in most bioassays. Gibberellins A9, A10, A23, and A24 are species specific in their activity. Gibberellins A8, A11, A12, A13, A14, A17, A25, A27, and A8-glucoside exhibit low activity. Gibberellin A26 is inactive up to 100 μg in all assays. The cucumber hypocotyl and barley aleurone bioassays respond only to a narrow spectrum of gibberellins while the rice bioassay is sensitive to all the gibberellins except A21, A25, and A26.Activity in the cucumber assay is restricted to gibberellins with a 13-deoxylactonic structure. With the exception of gibberellins A8, A26, and A27, only gibberellins having either an oxygenated C-3 position or a C-2,3 double bond, and a 19,10-lactone function, show more than low activity in the barley aleurone assay. Hydroxylation at the C-2 position may account for the reduced activity of gibberellins A8, A26, and A27. Possible reasons for a lack of correlation between gibberellin structure and biological activity in other bioassays are discussed.
Xylem differentiation in inhibited cotyledonary buds of soybeans
Authors: Ali A. , Fletcher R. A.
Published: September 2008

Inhibited buds in the cotyledonary axils of soybeans were shown to possess xylem strands passing from the main stem into the bud. The degree of xylem strand development was comparable to that of the actively growing apical bud. It is concluded that the inhibition of cotyledonary buds is not related directly to the lack of xylem differentiation.
Photosynthesis and photorespiration rates at the CO2 compensation point
Authors: Bulley N. R. , Tregunna E. B.
Published: September 2008

Attached soybean leaves in a closed system were fed high specific activity 14CO2 at four CO2 compensation points (30, 53, 110, 204 μl/l CO2) which were produced by different O2 concentrations (10, 21, 44, 80% O2). Rates of CO2 uptake and evolution were measured simultaneously using an infrared CO2 gas analyzer and a Geiger tube. The CO2 compensation point was proportional to O2 concentration but did not change for the two light intensities used. The rates of CO2 exchange at the compensation point did increase with light intensity. These rates of CO2 exchange also increased with the increasing CO2 concentration of the compensation point (for increasing O2 concentrations) but tended to saturate for compensation points greater than 110 μl/l CO2.
Changes in protein spectra of bean seed during germination
Authors: Juo Pei-Show , Stotzky G.
Published: September 2008

Globulins, albumins, and basic proteins were extracted from seeds of red kidney bean (Phaseolus vulgaris), and their distribution was in a ratio of about 3:2:1, respectively. The globulin fraction constituted a major portion of the reserve proteins and was hydrolyzed rapidly during germination. More than 90% of the basic proteins, extractable with 0.05 N acetic acid, disappeared 12 days after germination. Although the decrease in total albumin was not as marked as with the other two fractions, a number of components of this fraction disappeared during the early stages of germination, but several new components were detected about 8 days after germination. The apparent synthesis of new globulin components during germination was also observed, but no synthesis of basic protein could be detected.
A canker and foliage disease of yellow birch. II. Artificial infection studies with Diaporthe alleghaniensis
Authors: Arnold Ruth Horner
Published: September 2008

Disease symptoms found in nature on yellow birch (Betula alleghaniensis Britt.) infected by Diaporthe alleghaniensis R. H. Arnold, were induced by inoculation of seedlings and saplings with mycelium or conidia. On vigorously growing yellow birch plants, cankers, dead shoots, blackened necrotic petioles and mid-veins of leaves, and leaf spot developed during the inoculation year, and dieback occurred the next spring. Spore tendrils of the Phomopsis state of the pathogen were found on the most recently killed parts of the plants from May until early July. Initial symptoms were most severe on young tissues, and inoculation of shoots caused more damage to seedlings than inoculation of older tissues. The pathogen persisted in the host for several years without symptom expression, or in healed-over cankers. Initial symptoms were more severe on unshaded than on shaded seedlings, but shading increased the ultimate severity of the disease. Soil temperature and soil moisture did not influence artificial infection and subsequent development of the disease. There was evidence that the fungus produces a wilt-inducing agent. The disease was not found in nature on white birch (Betula papyrifera Marsh.), but seedlings were infected artificially. The probable course and importance of natural infection of yellow birch is discussed.
Studies on sunflower rust. V. Culture of Puccinia helianthi throughout its complete life cycle on detached leaves of sunflower (Helianthus annuus)
Authors: Hennessy C. M. R. , Sackston W. E.
Published: September 2008

Detached leaves of sunflowers on various substrates in petri plates retained some green color for 36 days at day and night temperatures of 22 and 20 °C respectively, and for 55 days at a continuous temperature of 10 °C. Water agar proved best of the substrates tried. Uredia developed in 9 to 10 days after inoculation with urediospores at 22−20 °C, and in 14 to 20 days at 10 °C. Telia developed in 14 to 20 days after inoculation at 22−20 °C, and in 22 days at 10 °C. Teliospores produced at 22−20 °C could not be induced to germinate. Those produced at 10 °C began to germinate 15 days after formation. Several complete cycles from teliospore to teliospore were produced on detached leaves. The time required per cycle averaged about 80 days.
Botryosphaeria laricis and its relationship to Macrophoma sapinea
Authors: Smerlis E.
Published: September 2008

Botryosphaeria laricis (Wehm.) v. Arx & E. Müller is reported from Quebec on tamarack (Larix laricina (Du Roi) K. Koch). Genetical relationship between B. laricis and its imperfect state, a form of Macrophoma sapinea (Fr.) Petr., is established.
Effects of various fungicides in soil on water and amino acid transport in tomato plants
Authors: Thorn G. D. , Richardson L. T.
Published: September 2008

Nabam (I), methylmercury dicyandiamide (II), Dexon (III), nonenylsuccinic acid (IV) and its monomethyl ester (V), benomyl, Vitavax, Plantvax, and Uniroyal F849 and G696 were applied as drenches to the soil of potted tomato plants. Exudate collected for 6 h from the stumps of plants detopped 24 h after application of each chemical was markedly reduced in volume and total amino acid content by I–V but not the others. Relative levels of individual amino acids were little affected except that I induced changes in the relative amounts of several primary amino acids, and II increased alanine concentration in the exudates.
ERRATUM: "FLEXIBLE STRUCTURE MULTIPLE MODELING USING IRREGULAR SELF-ORGANIZING MAPS NEURAL NETWORK"
Authors: FATEHI ALIREZA , ABE KENICHI
Published: September 2008

The MMSOM identification method, which had been presented by the authors, is improved to the multiple modeling by the irregular self-organizing map (MMISOM) using the irregular SOM (ISOM). Inputs to the neural networks are parameters of the instantaneous model computed adaptively at every instant. The neural network learns these models. The reference vectors of its output nodes are estimation of the parameters of the local models. At every instant, the model with closest output to the plant output is selected as the model of the plant. ISOM used in this paper is a graph of all the nodes and some of the weighted links between them to make a minimum spanning tree graph. It is shown in this paper that it is possible to add new models if the number of models is initially less than the appropriate one. The MMISOM shows more flexibility to cover the linear model space of the plant when the space is concave.
AUTOMATED LECTURE TIMETABLING USING A MEMETIC ALGORITHM
Authors: TESFALDET BEREKET T.
Published: September 2008

The lecture timetabling problem is known to be a highly constrained combinatorial optimization problem. There have been many attempts to address this problem using integer programming, graph coloring and several heuristic search methods. However, since each university has its own timetable setting requirements, it is difficult to develop a general solution method. Thus, the work is generally done manually. This paper attempts to solve the lecture timetabling problem of the University of Asmara using a customized memetic algorithm that we have called ALTUMA. It is a hybrid of genetic algorithms with hill-climbing operators. The performance of ALTUMA was evaluated using data obtained from the University. Empirical results show that ALTUMA is capable of producing good results in a reasonable amount of time. Besides, the results demonstrate that incorporating local search operators with a probabilistic scheme and delta method of fitness evaluation into the memetic algorithm significantly improves the search capabilities of the algorithm.
QUANTUM HALL EFFECT ON THE FLAG MANIFOLD F2
Authors: DAOUD MOHAMMED , JELLAL AHMED
Published: September 2008

The Landau problem on the flag manifold F2 = SU (3)/ U (1)× U (1) is analyzed from an algebraic point of view. The involved magnetic background is induced by two U(1) Abelian connections. In quantizing the theory, we show that the wave functions, of a nonrelativistic particle living on F2, are the SU(3) Wigner [Formula: see text]-functions satisfying two constraints. Using the F2 algebraic and geometrical structures, we derive the Landau Hamiltonian as well as its energy levels. The lowest Landau level (LLL) wave functions coincide with the coherent states for the mixed SU(3) representations. We discuss the quantum Hall effect for a filling factor ν = 1, where the obtained particle density is constant and finite for a strong magnetic field. In this limit, we also show that the system behaves like an incompressible fluid. We study the semiclassical properties of the system confined in LLL. These will be used to discuss the edge excitations and construct the corresponding Wess–Zumino–Witten action.
WORMHOLES OF K-ESSENCE IN ARBITRARY SPACE–TIME DIMENSIONS
Authors: ESTEVEZ-DELGADO J. , ZANNIAS T.
Published: September 2008

We consider a K-essence involving a massless scalar field Φ minimally coupled to Einstein gravity in D ≥ 4 space–time dimensions. This theory admits a two-parameter family of spherical wormholes representing two asymptotically-flat universes connected via a (D-2)-dimensional spherical throat. The ADM masses of the two ends are unequal and of opposite sign except for a one-parameter family where both ends possess vanishing ADM masses. By cut and paste techniques, we construct a two-parameter family of wormholes where the ends possess equal and positive ADM masses but the throat is a (D-1)-dimensional thin-shell. The structure of the surface energy–momentum tensor is also analyzed.
GROUND STATE SPECTRA OF THE NUCLEON OCTET IN A RELATIVISTIC LOGARITHMIC POTENTIAL
Authors: JENA S. N. , MUNI M. K. , PATTNAIK H. R.
Published: September 2008

The ground state spectra of the nucleon octet are studied in a relativistic logarithmic potential model taking into account the contributions of the quark–gluon coupling due to one-gluon-exchange interactions and that of Goldstone boson (π, η, K) exchange interactions between the constituent quarks in a baryon. The baryons are assumed here as an assembly of independent quarks confined in a first approximation by an effective logarithmic potential which presumably represents the nonperturbative gluon interactions, including the gluon self-couplings. This model treats the meson degree of freedom in a perturbative manner as is done in the cloudy bag model. The mass spectrum of low-lying baryons so obtained with the quark–gluon coupling constant αc = 0.195 agree reasonably well with the corresponding experimental values.
$\bar KN$ SCATTERING IN CHIRAL CONSTITUENT QUARK MODELS
Authors: HUANG F. , WANG W. L. , ZHANG Z. Y.
Published: September 2008

The chiral SU(3) quark model and the extended chiral SU(3) quark model have proven to be quite successful in reproducing the binding energy of the deuteron, the nucleon–nucleon (NN) scattering phase shifts and the hyperon–nucleon (YN) cross-sections. In the chiral SU(3) quark model, the quark–quark interaction contains one-gluon exchange (OGE), confinement potential and boson exchanges stemming from scalar and pseudoscalar nonets. In the extended chiral SU(3) quark model, the OGE is nearly replaced by vector meson exchange. It was shown in our previous work that these two models give quite similar descriptions for the S, P, D, F wave KN phase shifts, which means that in the KN system the contribution of OGE can be replaced by that of vector meson exchange. In this paper, we use the same models, the same parameters and the same methods to study the [Formula: see text] system with the purpose to test the effects of OGE and vector meson exchange. The cross-sections for K-p scattering into K-p, K0n, π+Σ-, π-Σ+, π0Σ0 and π0Λ channels are dynamically calculated by solving the resonating group method equation. While some channels are well described in one or the other model, a good agreement between the theoretical cross-sections and the experimental data for all channels is not successfully obtained. The present work indicates that both OGE and vector meson exchange are necessary to be included in the quark–quark interactions if one tries to simultaneously describe the KN phase shifts and [Formula: see text] cross-sections using one set of parameters in a constituent quark model.
H2/N2 MIXTURE ATMOSPHERE EFFECTS ON THE BEHAVIOR OF THE DOUBLE PEROVSKITE COMPOUND Sr2CoMoO6
Authors: AZIZI A. , KAHOUL A. , SCHMERBER G. , COLIS S. , DINIA A.
Published: September 2008

Sr 2 CoMoO 6 and Sr 2 CoMoO 6-δ ceramics have been obtained by solid state reaction in air and in a H 2/ N 2 gas mixture. At room temperature, as shown by X-ray diffraction, both compounds have a tetragonal perovskite-like structure with doublet unit-cell parameters, space group I4/m, with a = 5.5575, c = 7.9342 in Sr 2 CoMoO 6 and a = 5.5683 and c = 7.9395 in Sr 2 CoMoO 0.95. The latter contains small traces of Co and SrCoO 2.61, with an almost expansion. The magnetic susceptibility indicates that Sr 2 CoMoO 6 is an antiferromagnet with TN = 37 K. The magnetization was found to be the same in both samples, while the electric properties, originating from the oxygen content, are drastically affected.
TRANSVERSE FIELD AND INHOMOGENEOUS BROADENING EFFECTS ON OPTICAL BISTABILITY IN MIXED SPECIES
Authors: ALI M. F. M. , MAIZE S. M. A. , EL-DEBERKY M. A.
Published: September 2008

The steady state behavior of a bistable system of a homogeneously or inhomogeneously broadened two sorts of two-level atoms placed in a ring cavity and driven by a coherent field is analyzed within the mean field limit where the transverse effect of the radiation field is taken into account within the single-transverse-mode model. Effects on the input–output relation, due to the transverse parameter and the Lorentzian and the Gaussian line widths which measure the inhomogeneous broadening of the atoms, are examined. The enlargement of the optical bistable (tristable) region according to the previously mentioned parameters is explained.
OBSERVATION OF A REVERSIBLE LIQUID–LIQUID STRUCTURAL CHANGE INPb–SnMELTS WITH ELECTRICAL RESISTIVITY METHOD
Authors: ZU FANG-QIU , YI XUN , LI XIAN-FEN , CHENG ZHI-HAO , ZHOU BING , CHENG YI-PING
Published: September 2008

In recent years, a number of studies with different methods dedicated to structures and properties of liquid alloys revealed the occurrence of temperature-induced liquid–liquid structural transformation (TI-LLST). As yet, however, few investigations have concerned the reversibility of TI-LLST. The present paper reports a reversible TI-LLST in Pb – Sn alloys, which was observed with the electrical resistivity method during succeeding cooling and heating runs after the first heating process. The reversible TI-LLST is not the same as the TI-LLST in the first heating run, because the temperature ranges and the patterns are different from those of the latter. It is interesting that the similar phenomenon is also observed in pure tin, which suggests that the reversible TI-LLST in liquid Pb – Sn alloy is related to that in liquid Sn .
INVESTIGATION OF NON-MAGNETIC AND FERROMAGNETIC PHASES OF 3D ELECTRON CRYSTAL WITH NaCl AND CsCl STRUCTURES
Authors: RAJESWARA PALANICHAMY R. , ANANDAJOTHI M. , JAWAHAR A. , IYAKUTTI K.
Published: September 2008

The non-magnetic and ferromagnetic phases of 3D Wigner electron crystal are investigated using a localized representation of the electrons with NaCl and CsCl structures. The ground state energies of ferromagnetic and non-magnetic phases of Wigner electron crystal are computed in the range 10 ≤ rs ≥ 130. The role of correlation energy is suitably taken into account. The low density region favorable for the ferromagnetic phase is found to be 4.8 × 1020 electrons/cm3 and for the non-magnetic phase, it is 2.03 × 1020 electrons/cm3. It is found that the ground state energy of ferromagnetic phase is less than that of the non-magnetic phase of the Wigner electron crystal. The structure-dependent Wannier functions, which give proper localized representation for Wigner electrons, are employed in the calculation.
ELECTRONIC STRUCTURE OF Au ON Si(111) SURFACE
Authors: WANG JIANGUANG , MA LI , WANG GUANGHOU
Published: September 2008

Using the self-consistent tight-binding linear muffin-tin orbital method, we have investigated the electronic structure and adsorption properties of one monolayer Au atoms on a Si (111) surface. The total energies, the layer projected density of states and the charge distributions are calculated in detail. Our calculations show that the most stable position is on the interstitial center site above the Si (111) surface for the adsorbed Au atoms. It is possible for the Au atoms to sit below the Si surface, resulting in a Au – Si mixed layer at the Au/Si interface, which is in good agreement with the experimental results.
NUMERICAL SOLUTION OF NONLINEAR EQUATION TO COMBINED DETERMINISTIC AND NARROW-BAND RANDOM EXCITATION
Authors: CHINVIRIYASIT W. , CHINVIRIYASIT S.
Published: September 2008

The Duffing oscillator to combined deterministic and narrow-band random excitation, which is a nonlinear equation, is studied and solved numerically using three numerical methods based on finite difference schemes. Method 1, the well-known Euler method, is an explicit method; Method 2 is an implicit first-order method which does not bring contrived chaos into the solution; and Method 3 is based on two first-order methods which is second-order method and is chaos-free. In a series of numerical experiments, it is seen that the proposed methods have superior stability properties to those of the well-known Euler and fourth-order Runge-Kutta methods to which they are compared. When extended to the numerical solution of Duffing oscillator to combined deterministic and narrow-band random excitation, the developed methods give the correct steady-state solutions compared with the literature.
RADIATION EFFECTS ON OPTICAL CHARACTERISTICS OF PbWO4
Authors: YEVSEYEV V.
Published: September 2008

The results of a study on the effect of γ- Co 60, fast (1 MeV) reactor neutron and 1 GeV proton irradiation on optical properties of lead tungstate ( PbWO 4) are presented. The peculiarities of optical absorption in PbWO 4 under these three types of irradiation are revealed. It is shown that in the case of irradiation of PbWO 4 with high energy particles 1 GeV protons, an essential role is played by large-scale radiation defects — disordered regions — and, related to it, fluctuating electrostatic potential. It is established that the efficiency of defect formation increases at the transition from gamma to neutron and further to proton irradiation.
AN ELEMENTARY INTRODUCTION TO RECENTLY DEVELOPED ASYMPTOTIC METHODS AND NANOMECHANICS IN TEXTILE ENGINEERING
Authors: HE JI-HUAN
Published: September 2008

This review is an elementary introduction to the concepts of the recently developed asymptotic methods and new developments. Particular attention is paid throughout the paper to giving an intuitive grasp for Lagrange multiplier, calculus of variations, optimization, variational iteration method, parameter-expansion method, exp-function method, homotopy perturbation method, and ancient Chinese mathematics as well. Subsequently, nanomechanics in textile engineering and E-infinity theory in high energy physics, Kleiber's 3/4 law in biology, possible mechanism in spider-spinning process and fractal approach to carbon nanotube are briefly introduced. Bubble-electrospinning for mass production of nanofibers is illustrated. There are in total more than 280 references.
EFFECT OF NOISE AND SOURCE ILLUMINATION ON 3D SHAPE RECOVERY
Authors: MALIK AAMIR SAEED , CHOI TAE-SUN
Published: September 2008

There are many factors affecting the depth estimation for 3D shape recovery using passive optical methods. In this paper, we consider the effects of noise, source illumination and texture reflectance for shape from focus technique. We present a focus measure which shows consistent performance for varying noise levels, source illumination levels and different texture reflectance. The focus measure is based on an optical transfer function implemented in the Fourier domain and its results are compared with four other focus measures. The additive Gaussian noise is considered for noise analysis. Three illumination levels are considered for source illumination and three different textures are studied for reflectance analysis.
COMPLEX DYNAMICS IN MULTISTABLE SYSTEMS
Authors: FEUDEL ULRIKE
Published: September 2008

The coexistence of several stable states for a given set of parameters has been observed in many natural and experimental systems as well as in theoretical models. This paper gives an overview over the wide range of applications in different disciplines of science. Furthermore, different system classes possessing multistability are analyzed in terms of the appearance of coexisting attractors and their basins of attraction. It is shown that multistable systems are very sensitive to perturbations leading to a noise-induced hopping process between attractors. The role of chaotic saddles in the escape from attractors in multistable systems is discussed.
CONTROLLING MULTISTABILITY BY SMALL PERIODIC PERTURBATION
Authors: GOSWAMI B. K. , PISARCHIK A. N.
Published: September 2008

A small perturbation of any system parameters may not in general create any significant qualitative change in dynamics of a multistable system. However, a slow-periodic modulation with properly adjusted amplitude and frequency can do so. In particular, it can control the number of coexisting attractors. The basic idea in this controlling mechanism is to introduce a collision between an attractor with its basin boundary. As a consequence, the attractor is destroyed via boundary crisis, and the chaotic transients settle down to an adjacent attractor. These features have been observed first theoretically with the Hénon map and laser rate equations, and then confirmed experimentally with a cavity-loss modulated CO 2 laser and a pump-modulated fiber laser. The number of coexisting attractors increases as the dissipativity of the system reduces. In the low-dissipative limit, the creation of attractors obeys the predictions of Gavrilov, Shilnikov and Newhouse, when the attractors, referred to as Gavrilov–Shilnikov–Newhouse (GSN) sinks, are created in various period n-tupling processes and remain organized in phase and parameter spaces in a self-similar order. We demonstrate that slow small-amplitude periodic modulation of a system parameter can even destroy these GSN sinks and the system is suitably converted again to a controllable monostable system. Such a control is robust against small noise as well. We also show the applicability of the method to control multistability in coupled oscillators and multistability induced by delayed feedback. In the latter case, it is possible to annihilate coexisting states by modulating either the feedback variable or a system parameter or the feedback strength.
THE NATURE OF ATTRACTOR BASINS IN MULTISTABLE SYSTEMS
Authors: SHRIMALI MANISH DEV , PRASAD AWADHESH , RAMASWAMY RAM , FEUDEL ULRIKE
Published: September 2008

In systems that exhibit multistability, namely those that have more than one coexisting attractor, the basins of attraction evolve in specific ways with the creation of each new attractor. These multiple attractors can be created via different mechanisms. When an attractor is formed via a saddle-node bifurcation, the size of its basin increases as a power-law in the bifurcation parameter. In systems with weak dissipation, the basins of low-order periodic attractors increase linearly, while those of high-order periodic attractors decay exponentially as the dissipation is increased. These general features are illustrated for autonomous as well as driven mappings. In addition, the boundaries of the basins can also change from being smooth to fractal when a new attractor appears. Transitions in the basin boundary morphology are reflected in abrupt changes in the dependence of the uncertainty exponent on the bifurcation parameter.
VIOLATION OF THE FINAL STATES PROBABILITY SYMMETRY FOR EXPERIMENTAL TIME-DELAY SYSTEM AND COUPLED MAPS WITH TIME-VARYING PARAMETERS
Authors: BEZRUCHKO B. P. , PONOMARENKO V. I. , PROKHOROV M. D. , SELEZNEV YE. P.
Published: September 2008

The phenomenon of violation of equal probability of the postbifurcation states under a fast change of the control parameter is studied with an experimental system with continuous time and with a system of coupled maps. It is shown that the choice of one of the possible final states differing only in the phase of oscillations depends on the rate of the control parameter variation and noise level. For the coupled system, the dependence of the final states basin structure on the coupling coefficient is investigated.
ALFVÉN COMPLEXITY
Authors: REMPEL E. L. , CHIAN A. C.-L. , KOGA D. , MIRANDA R. A. , SANTANA W. M.
Published: September 2008

The complex dynamics of Alfvén waves described by the derivative nonlinear Schrödinger equation is investigated. In a region of the parameters space where multistability is observed, this complex system is driven towards an intermittent regime by the addition of noise. The effects of Gaussian and non-Gaussian noise are compared. In the intermittent regime, the Alfvén wave exhibits random qualitative changes in its dynamics as the result of a competition between three attractors and a chaotic saddle embedded in the fractal basin boundary.
MULTISTABILITY, PHASE DIAGRAMS AND STATISTICAL PROPERTIES OF THE KICKED ROTOR: A MAP WITH MANY COEXISTING ATTRACTORS
Authors: MARTINS LUCIANO CAMARGO , GALLAS JASON ALFREDO CARLSON
Published: September 2008

We investigate the prevalence of multistability in the parameter space of the kicked rotor map. We report high-resolution phase diagrams showing how the density of attractors and the density of periods vary as a function of both model parameters. Our diagrams illustrate density variations that exist when moving between the familiar conservative and strongly dissipative limits of the map. We find the kicked rotor to contain multistability regions with more than 400 coexisting attractors. This fact makes the rotor a promising high-complexity local unit to investigate synchronization in networks of chaotic maps, in both regular and complex topologies.
BISTABLE BEHAVIOR OF A KERR LENS MODE LOCKED Ti:SAPPHIRE LASER
Authors: KOVALSKY MARCELO G. , HNILO ALEJANDRO A.
Published: September 2008

Kerr lens mode locked Ti :Sapphire lasers can operate in at least two pulsed modes. Several models were developed with the aim to describe the characteristics of these modes. Those based on iterative maps, can reproduce the structurally stable properties of each mode but are unable to describe the interaction between modes. In this paper, we present a numerical simulation based on a complete map equation that makes possible to accurately describe the bistability experimentally observed in the laser. With the numerical time series we determine that the bistable behavior corresponds to low dimensional deterministic chaos and calculate that the embedding dimension of the attractor is three.
FLUCTUATIONAL ESCAPE FROM CHAOTIC ATTRACTORS IN MULTISTABLE SYSTEMS
Authors: KHOVANOV I. A. , LUCHINSKY D. G. , McCLINTOCK P. V. E. , SILCHENKO A. N.
Published: September 2008

Recent progress towards an understanding of fluctuational escape from chaotic attractors (CAs) is reviewed and discussed in the contexts of both continuous systems and maps. It is shown that, like the simpler case of escape from a regular attractor, a unique most probable escape path (MPEP) is followed from a CA to the boundary of its basin of attraction. This remains true even where the boundary structure is fractal. The importance of the boundary conditions on the attractor is emphasized. It seems that a generic feature of the escape path is that it passes via certain unstable periodic orbits. The problems still remaining to be solved are identified and considered.
DELAY-INDUCED MULTISTABILITY NEAR A GLOBAL BIFURCATION
Authors: HIZANIDIS J. , AUST R. , SCHÖLL E.
Published: September 2008

We study the effect of a time-delayed feedback within a generic model for a saddle-node bifurcation on a limit cycle. Without delay the only attractor below this global bifurcation is a stable node. Delay renders the phase space infinite-dimensional and creates multistability of periodic orbits and the fixed point. Homoclinic bifurcations, period-doubling and saddle-node bifurcations of limit cycles are found in accordance with Shilnikov's theorems.
ANALYTICAL STUDY OF VIBRATIONAL RESONANCE IN AN OVERDAMPED BISTABLE OSCILLATOR
Authors: CHIZHEVSKY V. N.
Published: September 2008

The results of analytical study of vibrational resonance (VR) occurring in overdamped bistable system driven by two periodic signals with very different frequencies are presented. Approximate solutions for responses at the low-frequency as a function of the amplitude, and the frequency of the additional high frequency modulation which describe well the main features of vibrational resonance are obtained. Scaling laws for the gain factor and the switching threshold in VR are also found. Analytical results are compared with results of the numerical simulation, showing a good agreement.
MULTIPLE-ATTRACTOR BIFURCATIONS AND QUASIPERIODICITY IN PIECEWISE-SMOOTH MAPS
Authors: ZHUSUBALIYEV ZHANYBAI T. , MOSEKILDE ERIK , BANERJEE SOUMITRO
Published: September 2008

It is known that border-collision bifurcations in piecewise-smooth maps can lead to situations where several attractors are created simultaneously in so-called "multiple-attractor" or "multiple-choice" bifurcations. It has been shown that such a situation leads to a fundamental source of uncertainty regarding which attractor the system will follow as a parameter is varied through the bifurcation point. Phenomena of this type have been observed in various physical and engineering systems. We have recently demonstrated that piecewise-smooth systems can exhibit a new type of border-collision bifurcation in which a stable invariant curve, associated with a quasiperiodic or a mode-locked periodic orbit, arises from a fixed point. In this paper we consider a particular variant of the multiple-attractor bifurcation in which a stable periodic orbit arises simultaneously with a closed invariant curve. We also show examples of simultaneously appearing stable periodic orbits and of the simultaneous generation of periodic and chaotic attractors.
COEXISTENCE OF NUMEROUS SYNCHRONIZED AND DESYNCHRONIZED STATES IN A MODEL OF TWO PHASE OSCILLATORS COUPLED WITH DELAY
Authors: LYSYANSKY BORYS , MAISTRENKO YURI L. , TASS PETER A.
Published: September 2008

When two phase oscillators interact with a time-delay, new synchronized and desynchronized regimes appear, in this way giving rise to the phenomenon of multistability. The number of coexisting stable states grows with an increase of the delay, and their frequencies quantize. We show that, while the number of synchronized solutions grows linearly with the delay and/or coupling, the set of the desynchronized solutions, i.e. those with different average frequencies of the individual oscillators, raises quadratically with increasing delay. For the synchronized states, we analyze the mutual arrangement of the basins of attraction, and conclude that the structure and size of the basins are apparently the same for each state. We discuss possible implications for desynchronizing brain stimulation techniques.
SYNCHRONIZATION OF MULTISTABLE SYSTEMS
Authors: PISARCHIK A. N. , JAIMES-REÁTEGUI R. , GARCÍA-LÓPEZ J. H.
Published: September 2008

We present the detailed study of synchronization of two unidirectionally coupled identical systems with coexisting chaotic attractors and analyze system dynamics observed on the route from asynchronous behavior to complete synchronization when the coupling strength is increased. We distinguish three stages of synchronization depending on the coupling strength which can be conventionally divided into three intervals. A relatively weak coupling induces asynchronous intermittent jumps between coexisting attractors and anticipating phase synchronization within windows where the systems stay in similar attractors; an intermediate coupling creates combined attractors that give rise to generalized synchronization in the form of subharmonic frequency entrainment; and a strong coupling results in complete synchronization. The results of numerical simulations are in good agreement with experiments carried out with piecewise-linear Rössler-like electronic circuits.
BLACK HOLES AS DARK MATTER ANNIHILATION BOOSTERS
Authors: FORNASA MATTIA , BERTONE GIANFRANCO
Published: September 2008

We review the consequences of the growth and evolution of black holes (BHs) for the distribution of stars and dark matter (DM) around them. We focus in particular on supermassive and intermediate mass black holes (SMBHs and IMBHs, respectively), and discuss under what circumstances they can lead to significant overdensities in the surrounding distribution of DM, thus effectively acting as DM annihilation boosters.
TRAVERSABLE WORMHOLES IN A STRING CLOUD
Authors: RICHARTE MARTÍN G. , SIMEONE CLAUDIO
Published: September 2008

We study spherically symmetric thin shell wormholes in a string cloud background in (3 + 1)-dimensional space–time. The amount of exotic matter required for the construction, the traversability and the stability of such wormholes under radial perturbations are analyzed as functions of the parameters of the model. In addition, in the appendices a nonperturbative approach to the dynamics and a possible extension of the analysis to a related model are briefly discussed.
AN INVESTIGATION OF UNIFORM EXPANSIONS OF LARGE ORDER BESSEL FUNCTIONS IN GRAVITATIONAL WAVE SIGNALS
Authors: CHISHTIE F. A. , RAO K. M. , KOTSIREAS I. S. , VALLURI S. R.
Published: September 2008

In this work, we extend the analytic treatment of Bessel functions of large order and/or argument. We examine uniform asymptotic Bessel function expansions and show their accuracy and range of validity. Such situations arise in a variety of applications, particularly the Fourier transform (FT) of the gravitational wave (GW) signal from a pulsar, global parameter space correlations of a coherent matched filtering search for continuous GWs from isolated neutron stars and tomographic reconstruction of GW LISA sources. The uniform expansion we consider here is found to be valid in the entire range of the argument.
QUANTUM THEORY OF AN ACCELERATING UNIVERSE
Authors: GONZÁLEZ-DÍAZ PEDRO F. , ROBLES-PÉREZ SALVADOR
Published: September 2008

We review some of the well-known features of quantum cosmology, such as the factor ordering problem, the wave function and the density matrix, for a dark-energy-dominated universe, where analytical solutions can be obtained. For the particular case of the phantom universe, we suggest a quantum system in which the usual notion of locality (nonlocality) of quantum information theory has to be extended. In that case, we deal also with a quantum description where the existence of a nonchronal region around the big rip singularity is explicitly accounted for.
CONSTRAINTS ON THE SOUND SPEED OF DYNAMICAL DARK ENERGY
Authors: XIA JUN-QING , CAI YI-FU , QIU TAO-TAO , ZHAO GONG-BO , ZHANG XINMIN
Published: September 2008

In this paper we study in detail the sound speed — [Formula: see text], which is directly related to the classical perturbations — of dynamical dark energy (DE). We consider especially the case with an equation of state crossing the cosmological constant boundary, and show its implications for cosmic microwave background (CMB) anisotropy. With the present observational data on the CMB, the Type Ia supernova (SNIa) and galaxy clustering, we perform a global analysis to constrain the sound speed of DE, using the Markov chain Monte Carlo method. We find that the sound speed of DE is weakly constrained by current observations, and thus futuristic precision measurements of the CMB on a very large angular scale (low multipoles) are necessary.
NONMINIMAL ISOTROPIC COSMOLOGICAL MODEL WITH YANG–MILLS AND HIGGS FIELDS
Authors: BALAKIN ALEXANDER B. , DEHNEN HEINZ , ZAYATS ALEXEI E.
Published: September 2008

We establish a nonminimal Einstein–Yang–Mills–Higgs model, which contains six coupling parameters. The first three parameters relate to the nonminimal coupling of a non-Abelian gauge field and a gravity field, the next two parameters describe the so-called derivative nonminimal coupling of a scalar multiplet with a gravity field, and the sixth parameter introduces the standard coupling of a scalar field with a Ricci scalar. The formulated six-parameter nonminimal Einstein–Yang–Mills–Higgs model is applied to cosmology. We show that there exists a unique exact cosmological solution of the de Sitter type for a special choice of the coupling parameters. The nonminimally extended Yang–Mills and Higgs equations are satisfied for arbitrary gauge and scalar fields, when the coupling parameters are specifically related to the curvature constant of the isotropic space–time. Based on this special exact solution, we discuss the problem of a hidden anisotropy of the Yang–Mills field, and give an explicit example, when the nonminimal coupling effectively screens the anisotropy induced by the Yang–Mills field and thus restores the isotropy of the model.
COLLAPSING INHOMOGENEOUS DUST IN THE BACKGROUND OF PERFECT (OR ANISOTROPIC) FLUID
Authors: CHAKRABORTY SUBENOY , BANDYOPADHYAY TANWI
Published: September 2008

In this work, the gravitational collapse of an inhomogeneous spherical star model, consisting of inhomogeneous dust in the background of perfect fluid or anisotropic fluid, is considered. The process of collapse is first examined separately for the dust and perfect fluid, and then under their combined effect, with or without interaction, for both marginally and nonmarginally bound cases. Finally, collapsing matter in the form of anisotropic fluid is investigated and it is found to be similar to that in the study by Chakraborty et al. (2005).
DISTRIBUTION FUNCTION OF DARK MATTER WITH CONSTANT ANISOTROPY
Authors: MA DING , HE PING
Published: September 2008

N-body simulations of dark matter halos show that the density is cusped near the center of the halo. The density profile behaves as r–γ in the inner parts, where γ ≃ 1 for the NFW model and γ ≃ 1.5 for the Moore model, but in the outer parts the two models agree with each other in the asymptotic behavior of the density profile. The simulations also show information about the anisotropy parameter β(r) of the velocity distribution: β ≈ 0 in the inner part and β ≈ 0.5 (radially anisotropic) in the outer part of the halo. We provide some distribution functions F(E, L) with the constant anisotropy parameter β for the two spherical models of dark matter halos: a new generalized NFW model and a generalized Moore model. There are two parameters α and ∊ for those two generalized models to determine the asymptotic behavior of the density profile. In this paper, we concentrate on the situation of β(r) = 1/2 from the viewpoint of the simulation.
HELIUM PROJECTILE FRAGMENT EMISSION IN INTERACTIONS OF 197Au WITH EMULSION AT 10.7A GeV
Authors: YUAN YING , ZHANG DONG-HAI , LIU FU-HU
Published: September 2008

The total and partial production cross-sections of the multiple helium fragments emitted in 10.7A GeV 197 Au –emulsion interactions are reported and compared with those obtained from different projectiles at high energies. The multiplicity distributions of the helium fragments exhibit a KNO scaling. The dependence of Cq moments and 〈nα〉 on the mass number of the incident beams is plotted.
EXACT SOLUTION OF THE SCHRÖDINGER EQUATION FOR THE MODIFIED KRATZER'S MOLECULAR POTENTIAL WITH POSITION-DEPENDENT MASS
Authors: SEVER RAMAZÀN , TEZCAN CEVDET
Published: September 2008

Exact solutions of Schrödinger equation are obtained for the modified Kratzer and the corrected Morse potentials with the position-dependent effective mass. The bound state energy eigenvalues and the corresponding eigenfunctions are calculated for any angular momentum for target potentials. Various forms of point canonical transformations are applied.
PROPERTIES OF Fe, Ni AND Zn ISOTOPES NEAR THE DRIP-LINES
Authors: TARASOV V. N. , TARASOV D. V. , GRIDNEV K. A. , GRIDNEV D. K. , KARTAVENKO V. G. , GREINER W.
Published: September 2008

The position of the neutron and proton drip-lines as well as properties of the isotopes Fe , Ni and Zn with neutron excess and neutron deficit are studied within the Hartree–Fock approach with the Skyrme interaction (Ska, SkM*, Sly4). The pairing is taken into account on the basis of the BCS approach with the pairing constant G = (19.5/A)[1 ± 0.51(N-Z)/A]. Our calculations predict that for Ni isotopes around N = 62 there appears a sudden increase of the deformation parameter up to β = 0.4. The zone with such big deformation, where Ni isotopes are stable against one neutron emission stretches up to N = 78. The magic numbers effects for the isotopes 48 Ni , 56 Ni , 78 Ni , 110 Ni are discussed. The universality of the reasons standing behind the enhancement of stability of the isotopes 40 O and 110 Ni which are beyond the drip-line is demonstrated. Calculated values of the two-neutron separation energy, and proton and neutron root mean square radii for the chain of Ni isotopes show a good agreement with existing Hartree–Fock–Bogoliubov calculations of these values.
THE EFFECT OF THE SCALAR-ISOVECTOR MESON FIELD ON HYPERON-RICH NEUTRON STAR MATTER
Authors: MI AI-JUN , ZUO WEI , LI ANG
Published: September 2008

We investigate the effect of the scalar-isovector δ-meson field on the equation of state (EOS) and composition of hyperonic neutron star matter, and the properties of hyperonic neutron stars within the framework of the relativistic mean field theory. The influence of the δ-field turns out to be quite different and generally weaker for hyperonic neutron star matter as compared to that for npeμ neutron star matter. We find that inclusion of the δ-field enhances the strangeness content slightly and consequently moderately softens the EOS of neutron star matter in its hyperonic phase. As for the composition of hyperonic star matter, the effect of the δ-field is shown to shift the onset of the negatively-charged (positively-charged) hyperons to slightly lower (higher) densities and to enhance (reduce) their abundances. The influence of the δ-field on the maximum mass of hyperonic neutron stars is found to be fairly weak, whereas inclusion of the δ-field turns out to enhance sizably both the radii and the moments of inertia of neutron stars with given masses. It is also shown that the effects of the δ-field on the properties of hyperonic neutron stars remain similar in the case of switching off the Σ hyperons.
NUMBER PROJECTED TWO-NEUTRON SEPARATION ENERGY IN THE NEUTRON-RICH RARE-EARTH REGION
Authors: BENHAMOUDA N. , ALLAL N. H. , FELLAH M. , OUDIH M. R.
Published: September 2008

The variation of the two-neutron separation energy (S2N), as a function of the neutron number N, is studied using a microscopic model that includes the pairing effects rigorously within the Fixed-Sharp-BCS method. The model was first tested on "ordinary" nuclei and allowed one to suitably reproduce the experimental data and to confirm the results of previous studies. The model was then applied to the even–even neutron-rich isotopes in the rare-earth region and showed, on the one hand, a relatively important variation of S2N, when N = 100, that could lead to the assumption of the existence of a new magic number in this region, and on the other hand, a weak variation of S2N when N > 100. These findings corroborate the previously obtained results for the charge mean square radius and the quadrupole and hexadecapole moments within the same model.