bluuebunny/crossref_metadata_2025 huggingface dataset:
Viscosity Studies of Some Electrolytes in Dimethyl Sulfoxide and N,N-Dimethylformamide at Different Temperatures
Authors: Chauhan Mohinder S. , Sharma Manita , Sharma Kishore C. , Ashwini K. , Chauhan Suvarcha
Published: July 2002

The limiting molar conductivity Λ0 and the Jones-Dole viscosity coefficients A and B were measured for Ph4PBPh4, Bu4NBPh4, Bu4NClO4, Ph4PBr, Bu4NBr, NaBPh4, NaClO4, KClO4, LiClO4 and AgClO4 in pure DMF and DMSO at 20, 30 and 40 °C. The experimental coefficients A are compared with the coefficients A calculated from the Falkenhagen-Vernon equation. The ionic viscosity coefficients B, which were obtained using Ph4PBPh4 as the reference electrolyte, are discussed in terms of the contributions in the expression: Bion = Bw + Bsolv + Bord + Bdisord + Bshape.
Partial Characterization of the Active Site of Carrot Poly(galacturonate) Hydrolase and Degradation of Oligo(D-galactosiduronates)
Authors: Heinrichová Kveta , Heinrich Július , Dzúrová Mária
Published: July 2002

The dimension and arrangement of the active center in carrot poly(1→4-α-D-galacturonide)galacturonohydrolase (E.C.3.2.1.67) is studied. Molecular activities k0 and parameters k0/Km were calculated from the experimentally determined Michaelis constants Km and maximum rates of catalytic hydrolysis of linear oligo(D-galactosiduronates) (polymerization degree n = 2 to 7) at pH 5.0 and 30 °C. From the dependence of log k0 and log k0/Km on n we derived that the active center consists of six subsites, the catalytic site being situated between the first and second subsite. In accord with the theory of Hiromi [Hiromi K.: Biochem. Biophys. Res. Commun. 40, 1 (1970)], the kinetic data were used for calculation of affinities (Ai) of the third (A3) to the sixth (A6) subsite. Two possible models were studied for the action of carrot poly(galacturonate)hydrolase which catalyzes the gradual terminal hydrolytic cleavage of oligo(D-galactosiduronates) from the non-reducing end of the molecule. The distribution of products in monomolecular hydrolysis of penta(D-galactosiduronate) under optimal conditions (pH and temperature) indicates a multi-chain enzymatic attack with predominant single collision. The kinetic results of the enzyme degradation are in good accord with the above-mentioned assumption.
Peak Capacity Calculation in Capillary Gas Liquid Chromatography
Authors: Krupčík Ján , Hevesi Tibor , Sandra Pat
Published: July 2002

A method is suggested for the determination of the peak capacity in isothermal and temperature-programmed high resolution gas chromatography (HRGC). The calculation is based on the integral by Grushka and Giddings, requiring that the dependence of the peak width on the retention time be known. Regression analysis of experimental data gave evidence that in isothermal and linear temperature-programmed HRGC where the temperature rate is the single variable parameter, the dependence of the peak width on retention time can be approximated by a linear equation. Substitution of this linear dependence in the integrand gives an integral which can be solved analytically. For temperature-programmed HRGC with two variable parameters, viz. the time of initial isothermal period and the temperature rate, the above dependence can be fitted with a cubic equation. The resulting integral is more complex and has to be solved numerically. The peak capacities calculated by the procedure suggested and by the use of the separation number (TZ) are in a good agreement.
A Monte Carlo Study of Copolymer Chain Conformations in Dilute Solutions in Good and Selective Solvents
Authors: Vrbová Tereza , Limpouchová Zuzana , Procházka Karel
Published: July 2002

Conformations of symmetric diblock copolymers AB in dilute solutions in good and selective solvents were studied by Monte Carlo simulations on a simple cubic lattice. Individual chain conformations were created by the self-avoiding walk algorithm. A modified thermal equilibration of the system based on the Metropolis acceptance criteria for energies of the system and the Rosenbluth weights of chain conformations was applied. Interactions of the nearest neighbours (r = l), where l is the lattice distance, and interactions for r = sqrt(2l) and r = sqrt(3l) were considered. Various structural characteristics of the whole copolymer chain and individual blocks A, B were obtained in the course of computer simulations. It was found that a moderate contraction of the worse soluble block B and a certain segregation of blocks occurs in dilute solutions in selective solvents for the block A, however neither that contraction, nor the segregation of blocks are extensive.
Polarographic Determination of 7-Diethylamino-4-methylcoumarin
Authors: Barek Jiří , Hrnčíř Roman , Moreira Josino C.
Published: July 2002

The polarographic behaviour of the title optical whitening agent was studied in aqueous-methanolic solutions. Conditions for its quantitation were found within the concentration regions of 10 to 100 μmol l-1 by tast polarography, 1 to 100 μmol l-1 by differential pulse polarography on the conventional dropping mercury electrode, and 0.1 to 10 μmol l-1 by differential pulse polarography on a static mercury drop electrode. The analytical procedures developed were applied to the determination of the compound in technical products.
Effect of Fluidized Bed on Permeate Flux in Ceramic Membrane Cross-Flow Microfiltration
Authors: Mikulášek Petr
Published: July 2002

The microfiltration of a model fluid on an α-alumina microfiltration tubular membrane in the presence of a fluidized bed has been examined. Following the description of the basic characteristic of alumina tubular membranes, model dispersion and spherical particles used, some comments on the experimental system and experimental results for different microfiltration systems are presented. From the analysis of experimental results it may be concluded that the use of turbulence-promoting agents resulted in a significant increase of permeate flux through the membrane. It was found out that the optimum porosity of fluidized bed for which the maximum values of permeate flux were reached is approximately 0.8.
Certain Problems with the Application of Stochastic Diffusion Processes for the Description of Chemical Engineering Phenomena. Stochastic Model of Non-Isothermal Flow Chemical Reactor
Authors: Kudrna Vladimír , Vejmola Libor , Hasal Pavel
Published: July 2002

Recently developed stochastic model of a one-dimensional flow-through chemical reactor is extended in this paper also to the non-isothermal case. The model enables the evaluation of concentration and temperature profiles along the reactor. The results are compared with the commonly used one-dimensional dispersion model with Danckwerts' boundary conditions. The stochastic model also enables to evaluate a value of the segregation index.
Analysis of 1H NMR Data for Arene-Metal Complexes Using Extended Huckel Calculations
Authors: Galvão Adelino M. , Ferreira da Silva João L.
Published: July 2002

This work reports the use of extended Hückel molecular orbital (EHMO) calculations to correlate pz electronic densities of aromatic carbons in group VI metal-bis(η6-arene) complexes with the respective 1H NMR chemical shifts. The effect of delocalization on the acceptor properties and stabilization of ligand orbitals is analyzed comparing complexes of naphthalene, biphenyle and fluorene.
Acetylation and Formylation of 3-Ferrocenylpyrroles
Authors: Gotov Battsengel , Toma Štefan , Solčániová Eva
Published: July 2002

Acetylations of 3-ferrocenyl-1-methylpyrrole as well as 3-cyano-4-ferrocenylpyrrole and 3-cyano-4-ferrocenyl-1-methylpyrrole were performed. The course of the acylation is highly dependent on the acylation agent, that is acetyl chloride/aluminum chloride (method A), trifluoroacetic anhydride-acetic acid mixture (method B) or acetic anhydride/Sc(OTf)3 (method C). Method A gives the acetylation on ferrocene moiety, method B affords the trifluoroacetylation on pyrrole moiety and method C affords pyrrole moiety acetylation. Vielsmeier-Haack formylation gives the products of substitution on pyrrole moiety.
Metal Ion Chelates of Lipophilic Alkyl Diazinyl Ketoximes as Hydrolytic Catalysts
Authors: Cibulka Radek , Hampl František , Martinů Tomáš , Mazáč Jiří , Totevová Sonja , Liška František
Published: July 2002

A series of lipophilic dodecyl hetaryl ketoximes (hetaryl = pyridin-2-yl, pyridazin-3-yl, pyrimidin-2-yl, pyrimidin-4-yl, pyrazin-2-yl as well as their methyl hetaryl homologues was synthesized and hydrolytic activity of their chelates with Co2+, Ni2+, Cu2+ and Zn2+ in a micellar matrix of hexadecyltrimethylammonium bromide or in homogeneous aqueous solutions was investigated using 4-nitrophenyl acetate, 4-nitrophenyl hexanoate and 4-nitrophenyl diphenyl phosphate as model substrates. While Co2+ and Cu2+ chelates are almost inactive, those of Ni2+ and Zn2+ exhibit considerable activity. None of the studied chelates promotes hydrolysis of the used phosphate. The effective species are chelates of the metal : ligand stoichiometry 1 : 3 and 1 : 1 with Ni2+ and Zn2+, respectively, when the ester cleavage proceeds in the micellar matrix. The 1 : 2 stoichiometry was found in aqueous solutions of Ni2+ and Zn2+ chelates of methyl ketoximes.
Asthma admissions and weather conditions in Costa Rica
Authors: Chavarría J F
Published: July 2002

In Costa Rica there is little information about asthma admissions. In this report the monthly asthma admissions and weather data for a seven year period were reviewed. The hospital asthma admissions showed notable seasonal variation associated with variations in the rainfall and the relative humidity.
Bioenergetic constraints on tactical decision making in middle distance running
Authors: Jones A M , Whipp B J
Published: July 2002

Background: The highest velocity that a runner can sustain during middle distance races is defined by the intersection of the runner's individual velocity-time curve and the distance-time curve. The velocity-time curve is presumably fixed at the onset of a race; however, whereas the race distance is ostensibly fixed, the actual distance-time curve is not. That is, it is possible for a runner to run further than the race distance if he or she runs wide on bends in track races. In this instance, the point of intersection of the individual velocity-time curve and the distance-time curve will move downwards and to the right, reducing the best average velocity that can be sustained for the distance.

Methods: To illustrate this point, the race tactics used by the gold and silver medallists at 800 m and 5000 m in the Sydney Olympics were analysed. The paths taken by the runners were carefully tracked and the total distance they covered during the races and the average velocity they sustained over the distances they actually covered were calculated.

Results: In both the Olympic 800 m and 5000 m finals, for example, the winner was not the runner who ran at the highest average velocity in the race. Rather, the winners of these races were able to husband their metabolic resources to better effect by running closer to the actual race distance.

Conclusions: Race results in middle distance running events are dependent not just on the energetic potential of the runners at the start of the race and their strategy for pace allocation, but also on the effect of their tactical approach to positioning on the total distance covered in the race. Middle distance runners should be conscious of minimising the distance covered in races if they wish to optimise their performance.
The influence of body mass on daily movement patterns and home ranges of the collared lemming (Dicrostonyx groenlandicus)
Authors: Schmidt Niels M , Berg Thomas B , Jensen Thomas S
Published: July 2002

While the determinants of animals' space use have been addressed in a large number of studies, its intrasexual variability has received only limited attention. By means of radiotelemetry we found body mass to influence home-range size and distance moved by adult collared lemmings (Dicrostonyx groenlandicus) in northeast Greenland. Male body mass was positively correlated with home-range size. Distance moved by both males and females was also correlated with body mass, but with opposite trends: male movement distances increased with body mass, while female movement distances decreased. This may reflect the fact that larger females occupy the most favourable habitats, i.e., the habitats that minimize the need for movement, and thus exposure to predators, without limiting the food supply. The variability in male home range size and distance moved resulted in variability in the number of females accessible to each male. Larger males had access to more females, and hence, body mass was indirectly important for individual mating opportunities. However, increasing access to females was associated with higher costs in terms of mass loss, probably as a consequence of increased energy requirements and exposure to predators.
MULTIPLICITY FORMULAS FOR A CLASS OF REPRESENTATIONS OF AFFINE KAC–MOODY ALGEBRAS
Authors: CAPPS RICHARD H. , LYONS MICHAEL A.
Published: July 2002

The dominant weight of any highest weight irreducible representation (irrep) of an indecomposable affine algebra may be written in the form Λi – qδ, where the integral index i runs from 1 to some finite number (called the width of the representation), q is any non-negative integer, and δ is a vector called the null vector. All the width-two irreps of all the affine algebras are enumerated. Techniques used in an earlier paper on the width-one irreps are generalized and used to compute simple recursion formulas for the multiplicities of all these dominant weights. These formulas are suitable for rapid calculations. Numerical tables of the multiplicities of the highest 33 dominant weights are given for all the width-two irreps of twisted algebras.
SQUARED EIGENFUNCTIONS OF THE (MODIFIED) KP HIERARCHY AND SCATTERING PROBLEMS OF LOEWNER TYPE
Authors: OEVEL W. , SCHIEF W.
Published: July 2002

It is shown that products of eigenfunctions and (integrated) adjoint eigenfunctions associated with the (modified) Kadomtsev-Petviashvili (KP) hierarchy form generators of a symmetry transformation. Linear integro-differential representations for these symmetries are found. For special cases the corresponding nonlinear equations are the compatibility conditions of linear scattering problems of Loewner type. The examples include the 2+1-dimensional sine-Gordon equation with space variables occuring on an equal footing introduced recently by Konopelchenko and Rogers. This equation represents a special squared eigenfunction symmetry of the Ishimori hierarchy.
Theory of Connections on Graded Principal Bundles
Authors: Stavracou T.
Published: July 2002

The geometry of graded principal bundles is discussed in the framework of graded manifold theory of Kostant–Berezin–Leites. We first review the basic elements of this theory establishing at the same time supplementary properties of graded Lie groups and their actions. Particular emphasis is given in introducing and studying free actions in the graded context. Next, we investigate the geometry of graded principal bundles; we prove that they have several properties analogous to those of ordinary principal bundles. In particular, we show that the sheaf of vertical derivations on a graded principal bundle coincides with the graded distribution induced by the action of the structure graded Lie group. This result leads to a natural definition of the graded connection in terms of graded distributions; its relation with Lie superalgebra-valued graded differential forms is also exhibited. Finally, we define the curvature for the graded connection and we prove that the curvature controls the involutivity of the horizontal graded distribution corresponding to the graded connection.
REDUCTION OF PRESYMPLECTIC MANIFOLDS WITH SYMMETRY
Authors: ECHEVERRÍA-ENRÍQUEZ A. , MUÑOZ-LECANDA M. C. , ROMÁN-ROY N.
Published: July 2002

Actions of Lie groups on presymplectic manifolds are analyzed, introducing the suitable comomentum and momentum maps. The subsequent theory of reduction of presymplectic dynamical systems with symmetry is studied. In this way, we give a method of reduction which enables us to remove gauge symmetries as well as non-gauge "rigid" symmetries at once. This method is compared with other step-by-step reduction procedures. As particular examples in this framework, we discuss the reduction of time-dependent dynamical systems with symmetry, the reduction of a mechanical model of field theories with gauge and non-gauge symmetries, and the gauge reduction of the system made of a conformal particle.
METRICALLY THIN SINGULARITIES OF INTEGRABLE CR FUNCTIONS
Authors: MERKER JOËL , PORTEN EGMONT
Published: July 2002

In this article, we consider metrically thin singularities E of the solutions of the tangential Cauchy–Riemann operators on a smoothly embedded Cauchy–Riemann manifold M (CR functions on M\E). Our main result establishes the removability of E within the space of locally integrable functions on M, which are CR on M\E, under the hypothesis that the (dim M-2)-dimensional Hausdorff volume of E is zero and that the CR-orbits of M and of M\E are comparable.
AN ITERATIVE NONUNIFORMLY SPACED FINITE DIFFERENCE SCHEME FOR COMPUTATIONAL FLUID DYNAMICS
Authors: HORRAS ANDREAS , RISTOW GERALD H.
Published: July 2002

The settling dynamics of cylinders in a viscous Newtonian fluid are investigated numerically using an iterative finite difference scheme, which uses a nonuniformly spaced staggered grid. Special attention is given to the details of the spatial discretization and how they influence the physical results. The terminal velocity is calculated for different system sizes and cylinder diameters and the extrapolated values for an infinite system size are compared with the Oseen approximation.
A GEOMETRIC APPROACH TO THE PHASE TRANSITIONS
Authors: DEMIRTÜRK SEMRA , GÜNDÜÇ YIĞIT
Published: July 2002

In this work, we have proposed a new geometrical method for calculating the critical temperature and critical exponents by introducing a set of bond breaking probability values. The probability value Pc corresponding to the Coniglio–Klein probability for the transition temperature is obtained among this set of trial probabilities. Critical temperature, thermal and magnetic exponents are presented for d = 2 and d = 3, q = 2 Potts model and for the application of the method to the system with first order phase transition, q = 7 Potts model on different size lattices are employed.

The advantage of this method can be that the bond breaking probability can be applied, where the clusters are defined on a set of dynamic variables, which are different from the dynamic quantities of the actual Hamiltonian or the action of the full system. An immediate application can be to use the method on finite temperature lattice gauge theories.
DYNAMICAL COGNITIVE MODELS OF SOCIAL ISSUES IN RUSSIA
Authors: MITINA OLGA , ABRAHAM FRED , PETRENKO VICTOR
Published: July 2002

We examine and model dynamics in three areas of social cognition: (1) political transformations within Russia, (2) evaluation of political trends in other countries by Russians, and (3) evaluation of Russian stereotypes concerning women. We try to represent consciousness as vectorfields and trajectories in a cognitive state space. We use psychosemantic techniques that allow definition of the state space and the systematic construction of these vectorfields and trajectories and their portrait from research data. Then we construct models to fit them, using multiple regression methods to obtain linear differential equations. These dynamical models of social cognition fit the data quite well. (1) The political transformations were modeled by a spiral repellor in a two-dimensional space of a democratic–totalitarian factor and social depression–optimism factor. (2) The evaluation of alien political trends included a flow away from a saddle toward more stable and moderate political regimes in a 2D space, of democratic–totalitarian and unstable–stable cognitive dimensions. (3) The gender study showed expectations (attractors) for more liberated, emancipated roles for women in the future.
EXCHANGE RATE PASS-THROUGH FOR SELECTED ASIAN ECONOMIES
Authors: TOH MUN-HENG , HO HWEI-JING
Published: July 2002

This paper investigates the degree of exchange rate pass-through for the selected Asian countries namely Malaysia, Thailand, Taiwan, and Singapore. Unlike past studies, this paper focuses on small open economies and includes exports of primary commodities in the investigation. We utilize cointegration techniques based on Engle and Granger (1987) and Johansen and Juselius (1990), and error correction modeling, to provide a more robust and rigorous investigation of the long run and short run pass-through of exchange rates. It is found that, in general, the degree of pass-through is high, although there is a small extent of pricing to market found for all countries. For Malaysia, the degree of pricing to market found suggests that there is intense competition in the export industries. In the case of Thailand, there is almost complete pass-through and this conforms to our a priori expectations. In the case of Singapore and Taiwan, we detect a higher degree of pass-through compared to past studies. For a country, the high degree of pass-through will support the adoption of more flexible exchange rate oriented monetary policies, and for firms it will reveal the limits of their price setting behavior amidst international competition.
CP1 MODEL WITH HOPF TERM AND FRACTIONAL SPIN STATISTICS
Authors: HONG SOON-TAE , LEE BUM-HOON , PARK YOUNG-JAI
Published: July 2002

We reconsider the CP 1 model with the Hopf term by using the Batalin–Fradkin–Tyutin (BFT) scheme, which is an improved version of the Dirac quantization method. We also perform a semiclassical quantization of the topological charge Q sector by exploiting the collective coordinates to explicitly show the fractional spin statistics.
THE HIGGS MASSES AND EXPLICIT CP VIOLATION IN THE GLUINO–AXION MODEL
Authors: BOZ MÜGE
Published: July 2002

In this work, we address the phenomenological consequences of explicit CP violation on direct Higgs–boson searches at high energy colliders. Having a restricted parameter space, we concentrate on the recently proposed gluino–axion model, and investigate the CP violation capability of the model subject to the recent experimental data. It is shown that the Higgs masses as well as their CP compositions are quite sensitive to the supersymmetric CP phases. The lightest Higgs is found to be nearly CP even to a good approximation whilst the remaining two heavy scalars do not have definite CP parities.
IMPLICATIONS OF THE RENORMALIZATION GROUP EQUATIONS IN THREE-NEUTRINO MODELS WITH TWO-FOLD DEGENERACY
Authors: CHEN MU-CHUN , MAHANTHAPPA K. T.
Published: July 2002

We obtain a complete set of one-loop RGE's for a set of combinations of neutrino parameters for the case of two-fold degenerate hierarchical three-neutrino models. The requirement of consistency of exact solutions to these RGE's with the two-fold degeneracy yields conditions which have previously been obtained perturbatively/numerically. These conditions, in the limit |Ueν3| = 0, are shown to lead to a strong cancellation in the matrix element of neutrinoless double beta decay.
HADAMARD STATES AND TWO-DIMENSIONAL GRAVITY
Authors: SALEHI H. , BISABR Y.
Published: July 2002

We have used a two-dimensional analog of the Hadamard state-condition to study the local constraints on the two-point function of a linear quantum field conformally coupled to a two-dimensional gravitational background. We develop a dynamical model in which the determination of the state of the quantum field is essentially related to the determination of a conformal frame. A particular conformal frame is then introduced in which a two-dimensional gravitational equation is established.
LAGRANGIAN NOETHER SYMMETRIES AS CANONICAL TRANSFORMATIONS
Authors: GARCÍA J. ANTONIO , PONS J. M.
Published: July 2002

We prove that, given a time-independent Lagrangian defined in the first tangent bundle of configuration space, every infinitesimal Noether symmetry that is defined in the n-tangent bundle and is not vanishing on-shell, can be written as a canonical symmetry in an enlarged phase space, up to constraints that vanish on-shell. The proof is performed by the implementation of a change of variables from the n-tangent bundle of the Lagrangian theory to an extension of the Hamiltonian formalism which is particularly suited for the case when the Lagrangian is singular. This result proves the assertion that any Noether symmetry can be canonically realized in an enlarged phase space. Then we work out the regular case as a particular application of this ideas and rederive the Noether identities in this framework. Finally we present an example to illustrate our results.
ν-K0 ANALOGY, DIRAC–MAJORANA NEUTRINO DUALITY AND THE NEUTRINO OSCILLATIONS
Authors: LIPMANOV E. M.
Published: July 2002

The intent of this paper is to convey a new primary physical idea of a Dirac–Majorana neutrino duality in relation to the topical problem of neutrino oscillations. In view of the new atmospheric, solar and the LSND neutrino oscillation data, the Pontecorvo ν - K0 oscillation analogy is generalized to the notion of neutrino duality with substantially different physical meaning ascribed to the long-baseline and the short-baseline neutrino oscillations. At the level of CP-invariance, the suggestion of dual neutrino properties defines the symmetric two-mixing-angle form of the widely discussed four-neutrino (2 +2)-mixing scheme, as a result of the lepton charge conservation selection rule and a minimum of two Dirac neutrino fields. With neutrino duality, the two-doublet structure of the Majorana neutrino mass spectrum is a vestige of the two-Dirac-neutrino origin. The fine neutrino mass doublet structure is natural because it is produced by a lepton charge symmetry violating perturbation on a zero-approximation system of two twofold mass-degenerate Dirac neutrino–antineutrino pairs. A set of inferences related to the neutrino oscillation phenomenology in vacuum is considered.
PHASE SPACE PATH INTEGRAL IN CURVED SPACE
Authors: FERRARO RAFAEL , LESTON MAURICIO
Published: July 2002

Phase space path integral is worked out in a Riemannian geometry, by employing a prescription for the infinitesimal propagator that takes Riemann normal coordinates and momenta on an equal footing. The operator ordering induced by this prescription leads to the DeWitt curvature coupling in the Schrödinger equation.
A LOT OF FLAVOR PHYSICS FROM A LITTLE SYMMETRY
Authors: ARANDA ALFREDO , CARONE CHRISTOPHER D. , LEBED RICHARD F.
Published: July 2002

Recent neutrino parameter measurements place increasingly stringent on acceptable supersymmetric theories of flavor. A very fruitful approach is the application of non-Abelian discrete gauged flavor symmetries Gf. We discuss a highly successful model using Gf = T′ × Z3 where T′ is a non-Abelian group based on the symmetries of a tetrahedron. This model reproduces the basic features of the U(2) model, and also predicts neutrino masses and mixing angles consistent with either the SMA or LMA scenarios.
PHOTONS FROM COSMIC PSEUDO NAMBU-GOLDSTONE BOSONS
Authors: NG KIN-WANG
Published: July 2002

We formulate the photon production from coherently oscillating pseudo Nambu-Goldstone bosonic fields in expanding space–time. It is then applied to calculate the photon production from axionic cold dark matter.
THE MAIN INJECTOR FACILITY: A NEW TOOL FOR HIGH ENERGY PHYSICS AT FERMILAB
Authors: BHAT C. M.
Published: July 2002

The Main Injector(MI) and the Recycler Ring (RR) are newly built synchrotrons in the Fermilab Accelerator complex. Many new features have been incorporated in their design and are tested. MI has already served as a 150 GeV proton injector to the Tevatron during the final stages of 1998-1999 800 GeV fixed target HEP experiments. Presently, MI is in use for collider Run-II commissioning. The MI and the RR will play major roles in the future HEP programs at Fermilab.
FORMATION OF TOPOLOGICAL DEFECTS IN GAUGE FIELD THEORIES
Authors: RAJANTIE ARTTU
Published: July 2002

When a symmetry gets spontaneously broken in a phase transition, topological defects are typically formed. The theoretical picture of how this happens in a breakdown of a global symmetry, the Kibble–Zurek mechanism, is well established and has been tested in various condensed matter experiments. However, from the viewpoint of particle physics and cosmology, gauge field theories are more relevant than global theories. In recent years, there have been significant advances in the theory of defect formation in gauge field theories, which make precise predictions possible, and in experimental techniques that can be used to test these predictions in superconductor experiments. This opens up the possibility of carrying out relatively simple and controlled experiments, in which the nonequilibrium phase transition dynamics of gauge field theories can be studied. This will have a significant impact on our understanding of phase transitions in the early universe and in heavy ion collider experiments. In this paper, I review the current status of the theory and the experiments in which it can be tested.
FERMIONS IN TAUB-NUT BACKGROUND
Authors: VISINESCU MIHAI
Published: July 2002

We discuss the relativistic spin-[Formula: see text] particles in pseudo-classical models involving anticommuting Grassmann variables for the spin degrees of freedom. The constants of motion are expressed in terms of Killing vectors and Killing-Yano tensors. Passing from the spinning spaces to the Dirac equation in curved backgrounds we point out the role of the Killing-Yano tensors in the construction of the Dirac-type operators. The general results are applied to the case of the four-dimensional Euclidean Taub-NUT space.
LOCALIZED ELECTRONIC STATES IN A TERNARY QUASIPERIODIC MODEL
Authors: ZHOU PEIQIN , FU XIUJUN , LIU YOUYAN
Published: July 2002

The one-dimensional ternary sequence generated by the substitutions S→M,M→L,L→LS is generally called SML quasiperiodic model [Phys. Rev.B43, 13240 (1991)], the electronic localization of which is studied. For this model, the Fourier transform, the b and -width dependence on site number, the second moment and multifractal behaviors of wavefunctions are investigated. It is found that the lattice structure is quasiperiodic, but the energy spectrum is of pure point and the electronic states are all localized, which exhibits the characteristic of disordered systems.
CRYSTALLOGRAPHIC FEATURES OF THE TRANSITIONAL STATE IN La1-xSrxTiO3
Authors: ARAO M. , KOYAMA Y. , INOUE Y.
Published: July 2002

Crystallographic features of the transitional state in La 1-x Sr x TiO 3 around x=0.05 have been examined by transmission electron microscopy. In the transitional state, the insulating O′ regions with the size of about 3nm are distributed in the metallic O* matrix. Note that the O′ and O* phases have the Pbnm structures with the Jahn-Teller distortion and without it, respectively. Because the hole concentration of the O* phase is higher than that of the O′ phase, the transitional state is therefore characterized by the static electronic phase separation. In addition, it was also found that the crystal structure of the O′ phase should involve not only the (3z2-r2)-type Jahn-Teller displacement with q=0 but also the (x2-y2)-type one with q=<1/2 1/2 0 >c in the cubic Brillouin zone.
PROXIMITY OF THE METAL-INSULATOR/MAGNETIC TRANSITION AND ITS IMPACT ON THE ONE-ELECTRON SPECTRAL FUNCTION: A DOPING-DEPENDENT ARPES STUDY
Authors: MESOT J. , KAMINSKI A. , FRETWELL H. M. , ROSENKRANZ S. , CAMPUZANO J. C. , NORMAN M. R. , DING H. , RANDERIA M. , KADOWAKI K.
Published: July 2002

The doping dependence of the low-temperature spectral function is precisely determined from angle resolved photoemision (ARPES) measurements. It is found that, as the doping decreases, the maximum of the superconducting gap increases, but the slope of the gap near the nodes decreases. Though consistent with d-wave symmetry, the gap with underdoping cannot be fit by the simple cos(kx)-cos(ky) form. We suggest that this arises due to the increasing importance of long range interactions as one approaches the insulator. It is also shown that the shape of the spectral function at the (π, 0) point below T c can be explained by the interaction of the electrons with a collective mode whose energy matches that of the magnetic resonance as obtained by inelastic neutron scattering data, and points to the intimate relation of magnetic correlatins to high Tc superconductivity.
DYNAMICAL LOCALIZATION IN MESOSCOPIC JOSEPHSON JUNCTIONS
Authors: YU KAI-ZHI , ZOU JIAN , SHAO BIN
Published: July 2002

We consider a circular superconducting ring with a mesoscopic Josephson junction driven by periodically external electromagnetic field, and discuss a novel quantum effect, dynamical localization. In this paper we find that the charge is localized effectively for the cases when the ratio of the field magnitude and the field frequency equal some critical values.
THE UNIVERSALITY OF PSEUDOGAP PHENOMENON IN THE NORMAL STATE OF HIGH TEMPERATURE CUPRATE SUPERCONDUCTORS
Authors: LAM C. C. , VYAS ANAND
Published: July 2002

The pseudogap phenomenon in the normal state of Sn-, Mg- and Cd-doped Hg-1223 ceramic superconductors was studied based on the results of resistivity versus temperature measurement. By using the data obtained in the resistivity measurement a logarithmic deviation of the conductivity versus inverse temperature, i.e. ln [σ(T)-σ N (T)] versus 1/T was constructed to study the pseudogap which is opened at T* far above the critical temperature T C of the superconductors. The magnitude of the pseudogap was measured through the slope of the linear part in these plots. It is surprising that the differentiation of these plots with respect to the inverse temperature shows a constant within very wide temperature range. Similar as in the energy gap measurement in the semiconductors, this constant should represent the pseudogap of the normal state for the materials interested. The occurrence of the characteristic temperatures T*, T S and T F can be interpreted by our microscopic theory. The physical significances of the variation in the magnitude of the pseudogap Δ PG with respect to temperature are related to the kinetic energy of the quasiparticles involved in the system. The plot of T* against the molar fraction of the Sn-doping x is linear. However, the data of T* for the other doping elements Mg and Cd are scattered from the linear relationship for the Sn-doped ( Hg 1-x, Sn x)-1223 system. However, when we plot the relationship between T* against T C , the data of T* for different doping elements fall on the same curve of bend finger-like shape. This indicates that the intrinsic parameters T* and T C satisfy a universal relationship. The ratio Δ PG /(k B T F ) is expressible as a linear function of T C when the critical temperature is below ~ 129 K; while for samples that have critical temperature greater than 129 K this ratio is expressible as a quadratic polynomial function of T C . The universality relationship is also hold for this ratio against T C .
ACCELERATING THROUGH A POTENTIAL LANDSCAPE: A FRACTIONAL DYNAMICS APPROACH TO ENHANCED MOTION IN AN EXTERNAL FORCE FIELD?
Authors: METZLER RALF
Published: July 2002

We address the question of describing enhanced transport in an external force field close to thermal equilibrium, within the framework of fractional dynamics. We demonstrate that in the overdamped regime inconsistencies arise, in the existence of negative regions of the propagator. Despite of this observation, we claim that this approach might be useful for the long time description of such systems.
MAGNETO-OPTIC IMAGING OF PROTON-IRRADIATED HIGH Tc SUPERCONDUCTING THIN FILMS: A REVISIT OF Jc(T) FUNCTIONAL AND FLUX PINNING ENHANCEMENT
Authors: Wang Chong , Seo Hye-Won , Su Chun-Jung , Wang Yuh-Huah , Chen Q. Y. , Lu Xinming , Liu J. R. , Johansen Tom , Chu W. K.
Published: July 2002

We have performed systematic quantitative measurements of the critical current density Jc(B, T) for YBCO thin films proton-irradiated to various dosages using the MOI technique. Results for external magnetic fields up to 400Oe and temperature ranging from 5 to 80K are presented for a 600nm thick YBCO film irradiated by proton up to a dosage of 1016 cm -2 at 500 keV. While no significant differences were observed for T>50K, the Jc values consistently increased with the increasing external field for T<50K.
THEORY OF EXCITATION-ENERGY TRANSFER PROCESSES INVOLVING OPTICALLY FORBIDDEN EXCITON STATES IN ANTENNA SYSTEMS OF PHOTOSYNTHESIS
Authors: MUKAI KOICHIRO , ABE SHUJI , SUMI HITOSHI
Published: July 2002

The rate of excitation-energy transfer (EET) within the light-harvesting complex (LH) and from LH to the reaction center (RC) of photosynthetic purple bacteria is calculated, based on a formula for EET between molecular aggregates. We show that optically forbidden exciton states participate in EET processes through mulitpole EET interactions with the help of disorder. In the antenna systems of photosynthesis, high efficiency of energy transfer is implemented by these EET processes involving optically forbidden exciton states.
ULTRAFAST ATOMIC DISPLACEMENT IN OPTICAL AND SOFT X-RAY SPECTROSCOPIES
Authors: KAYANUMA YOSUKE , TANAKA SATOSHI
Published: July 2002

Recent advances in the spectroscopies of the second order processes both in the optical region and in the soft x-ray region are reviewed from a theoretical standpoint. A peculiar role of the breathing and oscillating spectral hole in the femtosecond pump-probe experiments is pointed out. The resonant x-ray emission spectrum in diamonds at the core-exciton excitation is analyzed by a simple model, and it is shown that a ultrafast off-center displacement occurs in the core-excited state.
SCINTILLATION MECHANISM OF Ce3+ DOPED Gd2SiO5
Authors: MORI K. , YOKOYA M. , NISHIMURA H. , NAKAYAMA M. , ISHIBASHI H.
Published: July 2002

Measuring the spectra of absorption, luminescence and excitation, and the decay times of the luminescence, at various temperatures, we investigate the scintillation mechanism of Ce 3+ doped Gd 2 SiO 5 (GSO:Ce). We conclude that the excitation energy created by gamma-ray irradiation relaxes to the core exciton states formed by the 4f-4f transitions of Gd 3+, and the core exciton migrates to collide with Ce 3+, and transfers the energy to Ce 3+ to emit the luminescence. We also conclude that the decay time of the Ce 3+ luminescence in GSO:Ce (70 ns for the case of 0.5 mol% of Ce concentration) is decided by the diffusion time of the core exciton. A very small value for the diffusion coefficient of the core exciton is estimated to be 7× 10-7 cm2/s.
Photoluminescence of Two-Dimensional Electron System in Modulation-Doped GaAs Quantum Well
Authors: Nakata H. , Fujii K. , Saitoh M. , Ohyama T.
Published: July 2002

We have carried out the photoluminescence measurements of two-dimensional electron system (2DES) in modulation-doped GaAs quantum well. It was found that the H band caused by radiative recombination between 2DES and holes shows a high energy tail below 4.2 K. We explain that the tail originates in the apparent breaking of the momentum conservation law, and that its reason is the electron scattering by neutral donors with the Bohr radius of ~10 nm. The distance between the adjacent donors, 80nm, is obtained from the coupling of the Landau levels in the different 2DES's. Excitonic effect is suggested by nonlinear dependence of the peak energy of the H band on magnetic fields and the lineshape analysis of the H band.
HALL MOBILITY IN n-TYPE 4H-SiC: CALCULATION USING HYDRODYNAMIC BALANCE EQUATIONS
Authors: QUAN HONG-JUN , WANG BING-HONG , LUO XIAO-SHU
Published: July 2002

The Hall mobility in n-type 4H-SiC has been calculated by hydrodynamic balance equations for temperatures ranging from 30 to 1000 K. We employ a compensation model to analyze the carrier concentration versus temperature data. The results show that the neutral impurity scattering and the piezoelectric scattering do not make significant contribution to the electron mobility. The low-temperature value of the mobility is mainly due to the ionized impurity while the high-temperature tail is limited by acoustic, polar optical and intervalley optical lattice scatterings. These results are in good agreement with the experimental data.
INTERFACIAL MASS TRANSPORT IN OXIDE CRYSTAL GROWTH
Authors: JIN WEI QING , LIANG XIN AN , CAI LI XIA , PAN ZHI LEI , TSUKAMOTO KATSUO
Published: July 2002

A space high temperature in situ observation instrument (SHITISOI) is dedicated to visualize and record the whole growth process of oxide crystal in high temperature melts and solutions. Model experiments using transparent liquids such as KNbO 3, Li 2 B 4 O 7+ KNbO 3 were chosen to investigate effects of interfacial mass transport in oxide crystal growth. For the scaling of the coupled velocity, heat and concentration fields in KNbO 3 crystal growth, a rotating growth process was performed and the widths of interfacial concentration, heat and momentum transition zones (The "boundary layers") are obtained, which are 7.5 × 10-3, and 8.6 × 10-2 and 4.4 × 10-1 cm , respectively. Hence one can expect that interfacial concentration gradient will be confined to a narrow layer and in region of major concentration change at the interface. In order to study a mechanism based on the interfacial mass transport resulting from hydrodynamics, the growth of KNbO 3 grain in high temperature Li 2 B 4 O 7 and KNbO 3 solution was studied. The result shows that the pivotal feature in the KNbO 3 crystal growth is the initiated by KNbO 3 solute surface tension gradient which is caused by the slow diffusion of KNbO 3solutes. Direct comparison of the model predictions and experimental observed phenomena demonstratre the predicitive capability of this model.
ANNEALING EFFECTS ON CONTACT PROPERTIES OF ALUMINUM DOPED ZINC OXIDE THIN FILMS
Authors: LOW KE BIN , GONG HAO , CHOR ENG FONG
Published: July 2002

Aluminum Zinc Oxide (AZO) thin films are grown on glass substrates by RF Magnetron Sputtering using a single target of zinc oxide (99 wt%) and aluminum oxide (1 wt%) with argon as the plasma. Photolithographic process is then performed on the films in order to obtain a Transmission Line Model structure (TLM) of the metal contact system, namely aluminum and gold. The specific contact resistivity, ρc, of these two metal-semiconductor systems, which will undergo different rapid thermal annealing (RTA) environment, are determined. X-Ray diffraction patterns for these samples are obtained to investigate phase formations or micro-structural changes so as to justify for the differences in specific contact resistivity obtained for these contact systems. The different RTA environment are simulated by purging either nitrogen or argon gas, with a pressure of 40 psi at a temperature of 400°C for 60 s; and annealing in vacuum (10-6 Torr) also at the same temperature and duration. One-dimensional TLM (1D-TLM) measurements are performed on the TLM structures to obtain the specific contact resistivity, ρc. Results show that aluminum contacts on AZO without RTA give the lowest ρc as compared to those in other environment, while gold contacts on AZO annealed in vacuum yield the lowest ρc. Adhesion of aluminum contacts on AZO is good even when subjected to ultrasonic bath test but not true for the case of gold contact, which adheres poorly on AZO films.
ESCAPE RATES IN THE PRESENCE OF HIGH FREQUENCY PERTURBATIONS
Authors: SARKAR SUBIR K. , DATTAGUPTA SUSHANTA
Published: July 2002

We study the problem of activated escape of a particle from a potential well when it is subjected to a periodic force of high frequency. We focus on the result that on time scales larger than the period of perturbation, the dynamics is equivalent to one in which the periodic perturbation is replaced by a time independent effective potential. A derivation of this result from the Langevin dynamics point of view is provided. Finally, predictions of the theory are tested against numerical results and excellent agreement is found.
MULTIPLY-TWISTED HELICES OF VARIOUS INTER-ROUND COUPLINGS
Authors: UGAJIN R. , WATANABE Y. , MORI Y.
Published: July 2002

Multiply-twisted helices in which a helical chain of components, i.e. atoms or nanoclusters, is twisted, producing a doubly-twisted helix, which if itself is twisted produces a triply-twisted helix, and so on, are characterized by inter-round couplings, through which electrons in the structure transit between adjacent rounds. The multiply-twisted helix of inter-round couplings via a chain of sites and that of inter-round couplings through a single site are compared with that of the direct inter-round couplings previously reported by R. Ugajin [J. Nanosci. Nanotechnol.1, 227 (2001)]. Monte Carlo simulations of classical spins suggest that the multiply-twisted helix of inter-round couplings through a single site, in which the Curie temperature of ferromagnetic transition is robust against the change of a basal helix, might be critical among these three types.
CRITICAL TEMPERATURE OF AN INTERACTING BOSE GAS IN A GENERIC POWER-LAW POTENTIAL
Authors: SALASNICH LUCA
Published: July 2002

We investigate the critical temperature of an interacting Bose gas confined in a trap described by a generic isotropic power-law potential. We compare the results with respect to the non-interacting case. In particular, we derive an analytical formula for the shift of the critical temperature holding to first order in the scattering length. We show that this shift scales as Nn/3(n+2), where N is the number of Bosons and n is the exponent of the power-law potential. Moreover, the sign of the shift critically depends on the power-law exponent n. Finally, we find that the shift of the critical temperature due to finite-size effects vanishes as N-2n/3(n+2).
THE PEIERLS SUBSTITUTION AND THE VANISHING MAGNETIC FIELD LIMIT
Authors: OUVRY STÉPHANE
Published: July 2002

In order to achieve in configuration space a dimensional reduction from dimension two to dimension one, the lowest Landau level (LLL) projection, also called the Peierls substitution, is not sufficient. One has also, once in the LLL, to take the vanishing magnetic field limit.
THE TRANSVERSE ISING MODEL UNDER A TIME OSCILLATING FIELD
Authors: SANTOS M. , de OLIVEIRA M. J.
Published: July 2002

We have studied an Ising spin system in a transverse field, at zero temperature, under a time oscillating longitudinal field by means of a mean-field approximation and a Monte Carlo algorithm, appropriate to study the ground-state properties of quantum spin chains. For large values of the transverse field Γ or large amplitude h0 of the oscillating field, the magnetization oscillates around a zero value with the same frequency but delayed. Decreasing Γ, at small a h0, the system undergoes a phase transition to a state in which the magnetization oscillates around a nonzero value. We have also obtained the behavior of the hysteresis loop area near the Curie point.