bluuebunny/crossref_metadata_2025 huggingface dataset:
Saddle reef auriferous veins in a conical fold termination (Oldham anticline, Meguma terrane, Nova Scotia, Canada): reconciliation of structural and age data
Authors: Keppie D Fraser , Keppie J Duncan , Murphy J Brendan
Published: July 2002

Many auriferous veins dated at ~370 Ma in the Meguma terrane of Nova Scotia are concentrated in tight domes, and conical fold hinges that are transected by 378 Ma low-pressure and high-temperature metamorphic isograds and 380370 Ma granitoid plutons. Published experiments suggest that such folds are diachronous initiating at inhomogeneities and propagating both in amplitude and along their length. Thus fold terminations are typically conical in geometry and record only the youngest increment of folding. The northeastern termination of the Oldham anticline is characterized by (1) a conical fold, (2) saddle reef auriferous veins, (3) divergent and convergent cleavage fans, (4) a downdip lineation on the slaty cleavage defined by biotitic mineral aggregates inferred to have developed during fold growth. The age of the biotitic mineral aggregates is bracketed between peak metamorphism at > 600°C, defined by a nearly concordant 378 Ma UPb monazite age from a xenolith in lamprophyre dyke, and ~366 Ma 40Ar/39Ar muscovitebiotite ages, recording cooling through ~400300°C. This suggests that the conical termination of the Oldham anticline grew between 378 and 366 Ma, an observation that reconciles the empirical structural control of the saddle reef auriferous veins with the ~370 Ma age dating of vein minerals. Application of this conclusion to saddle reef auriferous veins in domes suggests that mineralization was related to the youngest increment of fold amplification.
FISH-mapping of rDNAs andArabidopsisBACs on pachytene complements of selectedBrassicas
Authors: Ziolkowski Piotr A , Sadowski Jan
Published: July 2002

To improve resolution of physical mapping on Brassica chromosomes, we have chosen the pachytene stage of meiosis where incompletely condensed bivalents are much longer than their counterparts at mitotic metaphase. Mapping with 5S and 45S rDNA sequences demonstrated the advantage of pachytene chromosomes in efficient physical mapping and confirmed the presence of a novel 5S rDNA locus in Brassica oleracea, initially identified by genetic mapping using restriction fragment length polymorphism (RFLP). Fluorescence in situ hybridization (FISH) analysis visualized the presence of the third 5S rDNA locus on the long arm of chromosome C2 and confirmed the earlier reports of two 45S rDNA loci in the B. oleracea genome. FISH mapping of low-copy sequences from the Arabidopsis thaliana bacterial artificial chromosome (BAC) clones on the B. oleracea chromosomes confirmed the expectation of efficient and precise physical mapping of meiotic bivalents based on data available from A. thaliana and indicated conserved organization of these two BAC sequences on two B. oleracea chromosomes. Based on the heterologous in situ hybridization with BACs and their mapping applied to long pachytene bivalents, a new approach in comparative analysis of Brassica and A. thaliana genomes is discussed.Key words: Brassicaceae, pachytene chromosomes, FISH, rDNA, BACs.
Lactoferrin: influences on Langerhans cells, epidermal cytokines, and cutaneous inflammation
Authors: Kimber I , Cumberbatch M , Dearman R J , Headon D R , Bhushan M , Griffiths C EM
Published: July 2002

It has been suggested previously that, in addition to other biological roles, lactoferrin (LF) may display anti-inflammatory properties secondary to the regulation of cytokine expression. To explore this concept further, we have here examined in human volunteers the influence of recombinant homologous LF on the migration of epidermal Langerhans cells (LC), a process that is known to be dependent upon the local availability of certain proinflammatory cytokines including tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β). In common with previous studies in mice, it was found that topical administration of LF prior to exposure at the same site to the contact sensitizer diphenylcyclopropenone resulted in a significant reduction of allergen-induced LC migration from the epidermis (measured as a function of the frequency of CD1a+or HLA-DR+LC found in epidermal sheets prepared from punch biopsies of the treated skin sites). However, under the same conditions of exposure, LF was unable to influence migration of LC induced by the intradermal administration of TNF-α data consistent with the hypothesis that one action of LF in the skin is to regulate the local production of this cytokine. Further support for this hypothesis was derived from experiments conducted with IL-1β. This cytokine is also able to induce the mobilization of LC following intradermal injection, although in this case, migration is known to be dependent upon the de novo production of TNF-α. We observed that prior exposure to LF resulted in a substantial inhibition of IL-1β-induced LC migration, data again consistent with the regulation of TNF-α production by LF. Collectively, these results support the view that LF is able to influence cutaneous immune and inflammatory processes secondary to regulation of the production of TNF-α and possibly other cytokines.Key words: lactoferrin, Langerhans cells, tumor necrosis factor α, interleukin 1β.
An automated and improved laboratory consolidation system
Authors: Blewett J , McCarter W J , Chrisp T M , Starrs G
Published: July 2002

A novel hydraulic consolidation cell has been developed. The cell is designed to simplify sample preparation and test assembly procedures thus minimizing fabric disturbance. A fully automated control and acquisition system has also been developed to work in association with the cell.Key words: consolidation, hydraulic loading, data acquisition and control.
Comparative degradation of oomycete, ascomycete, and basidiomycete cell walls by mycoparasitic and biocontrol fungi
Authors: Inglis G D , Kawchuk L M
Published: July 2002

Fourteen fungi (primarily representing mycoparasitic and biocontrol fungi) were tested for their ability to grow on and degrade cell walls (CWs) of an oomycete (Pythium ultimum), ascomycete (Fusarium equisetii), and basidiomycete (Rhizoctonia solani), and their hydrolytic enzymes were characterized. Protein was detected in the cultural medium of eleven of the test isolates, and these fungi significantly degraded CWs over the 14-day duration of the experiment. In general, a greater level of CW degradation occurred for F. equisetii and P. ultimum than for R. solani. Fungi that degraded F. equisetii CWs were Coniothyrium minitans, Gliocladium roseum, Myrothecium verrucaria, Talaromyces flavus, and Trichoderma harzianum. Taxa degrading P. ultimum CWs included Chaetomium globosum, Coniothyrium minitans, M. verrucaria, Seimatosporium sp., Talaromyces flavus, Trichoderma hamatum, Trichoderma harzianum, and Trichoderma viride. Production of extracellular protein was highly correlated with CW degradation. Considerable variation in the molecular weights of CW-degrading enzymes were detected among the test fungi and the CW substrates in zymogram electrophoresis. Multivariate analysis between CW degradation and hydrolysis of barley β-glucan (β1,3- and β1,4-glucanases), laminarin (β1,3- and β1,6-glucanases), carboxymethyl cellulose (endo-β1,4-glucanases), colloidal chitin (chitinases), and chitosan (chitosanases) was conducted. For F. equisetii CWs, the regression model accounted for 80% of the variability, and carboxymethyl cellulases acting together with β-glucanases contributed an R2of 0.52, whereas chitinases and β-glucanases alone contributed an R2of 0.11 and 0.12, respectively. Only 61% of the variability observed in the degradation of P. ultimum CWs was explained by the enzyme classes tested, and primarily β-glucanases (R2of 0.53) and carboxymethyl cellulases (R2of 0.08) alone contributed to CW break down. Too few of the test fungi degraded R. solani CWs to perform multivariate analysis effectively. This study identified several fungi that degraded ascomyceteous and oomyceteous, and to a lesser extent, basidiomycetous CWs. An array of enzymes were implicated in CW degradation.Key words: enzymes, phytopathogens, hydrolysis, cell wall, CW.
Effects of live crown on vertical patterns of wood density and growth in Douglas-fir
Authors: Gartner Barbara L , North Eric M , Johnson G R , Singleton Ryan
Published: July 2002

It would be valuable economically to know what are the biological triggers for formation of mature wood (currently of high value) and (or) what maintains production of juvenile wood (currently of low value), to develop silvicultural regimes that control the relative production of the two types of wood. Foresters commonly assume the bole of softwoods produces juvenile wood within the crown and mature wood below. We tested that assumption by comparing growth ring areas and widths and wood density components of the outer three growth rings in disks sampled from different vertical positions of 34-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees. The 18 trees were sampled from one site and had a wide range of heights to live crown. Most of the variance (6393%) in wood characteristics (growth ring area: total, earlywood, latewood; growth ring width: total, earlywood, latewood; latewood proportion: by area, width; and ring density: total, earlywood, latewood) was due to within-tree differences (related to age of the disk). Stepwise regression analysis gave us equations to estimate wood characteristics, after which we analyzed the residuals with a linear model that included whether a disk was within or below the crown (defined as the lowest node on the stem with less than three live branches). After adjusting for tree and disk position, only 210% of the residual variation was associated with whether the disk was in or out of the live crown. There were no statistically significant differences at p = 0.05 between a given disk (by node number) in versus out of the crown for any of the factors studied. Moreover, the wood density characteristics were not statistically significant at p = 0.30. This research suggests that there was no effect of the crown position on the transition from juvenile to mature wood as judged by wood density. Therefore, we found no evidence to support the concept that tree spacing and live-branch pruning have a significant effect on the cambial age of transition from juvenile to mature wood in Douglas-fir trees of this age.
UNITARY REPRESENTATIONS OF NONCOMPACT QUANTUM GROUPS AT ROOTS OF UNITY
Authors: STEINACKER H.
Published: July 2002

Noncompact forms of the Drinfeld–Jimbo quantum groups [Formula: see text] with [Formula: see text], [Formula: see text] for si=±1 are studied at roots of unity. This covers [Formula: see text], su(n,p), so*(2l), sp(n,p), sp(l,ℝ), and exceptional cases. Finite dimensional unitary representations are found for all these forms, for even roots of unity. Their classical symmetry induced by the Frobenius map is determined, and the meaning of the extra quasi-classical generators appearing at even roots of unity is clarified. The unitary highest weight modules of the classical case are recovered in the limit q→1.
ANDERSON LOCALIZATION FOR A MULTIDIMENSIONAL MODEL INCLUDING LONG RANGE POTENTIALS AND DISPLACEMENTS
Authors: ZENK HERIBERT
Published: July 2002

We give a short summary on how to combine and extend results of Combes and Hislop [2] (short range Anderson model with additional displacements), Kirsch, Stollmann and Stolz [13] and [14] (long range Anderson model without displacements) to get localization in an energy interval above the infimum of the almost sure spectrum for a continuous multidimensional Anderson model including long range potentials and displacements.
GEOMETRIC STUDY OF HAMILTON'S VARIATIONAL PRINCIPLE
Authors: CARIÑENA JOSÉ F. , LÓPEZ CARLOS
Published: July 2002

Higher order tangent bundle geometry and sections along maps are used in Geometrical Mechanics in order to develop an intrinsic variational calculus. The role of variational derivative as the bundle operator associated to exterior differential on the set of trajectories is remarked. Euler-Lagrange equations and Poincaré-Cartan form are rederived in this way. Helmholtz conditions for the inverse problem of Lagrangian Mechanics are geometrically obtained for the general higher order case.
VERTEX OPERATORS ARE NOT CLOSABLE
Authors: BOENKOST WOLFRAM
Published: July 2002

We prove the unclosability of the free vertex operators used in conformal field theory for the BRST-construction of primary fields. Our proof includes minimal models as well as WZNW-models.
A REMARK ON DIFFERENTIABILITY OF THE PRESSURE FUNCTIONAL
Authors: VAN ENTER AERNOUT , ZEGARLINSKI BOGUSLAW
Published: July 2002

We give a short review of results on equilibrium description and description by stochastic dynamics for spin systems on a lattice. We remark also that some coercive inequalities for the generators of stochastic dynamics, as e.g. the Logarithmic Sobolev inequality, can be used in a direct and natural way to prove strong differentiability properties of the pressure functional for lattice spin systems with multiparticle interactions at high temperatures. Motivated by this, we exhibit also a class of examples of multiparticle interactions which do not belong to the space [Formula: see text] of spin interactions, but for which the Gibbs measures exist and are unique at high temperatures.
A NEW SUPERSYMMETRIC VERSION OF THE ABRAHAM-MOSES METHOD FOR SYMMETRIC POTENTIALS
Authors: CASAHORRÁN J.
Published: July 2002

Starting from the one-dimensional Schrodinger equation with symmetric potential Vs(x), a general method is presented in order to obtain a family of partially isospectral hamiltonians. Arguments concerning supersymmetric transformations, factorization procedures and Riccati equations are invoked along the article. As a result of the appearance of singular superpotentials, the physical meaning of our method can be summarized as follows: only the odd wave-functions of the original potential Vs(x) are transported via supersymmetry into the Hilbert space associated with the partner Vp(x). In such a case the degeneracy of energy levels is partially broken. Supersymmetry is neither exact nor spontaneously broken but realizes itself acting on wave functions vanishing at x=0. While the domain of the original hamiltonian H extends along the whole real axis, the susy partner Hp reduces to the half-line (x≤0 or x≥0). To illustrate how the procedure works in practice we resort to a symmetric potential in the Posch-Teller class containing both discrete and continuous spectra.
TOWARDS THE RIGHT HAMILTONIAN FOR SINGULAR PERTURBATIONS VIA REGULARIZATION AND EXTENSION THEORY
Authors: NEIDHARDT HAGEN , ZAGREBNOV VALENTIN
Published: July 2002

For singular potentials in quantum mechanics it can happen that the Schrödinger operator is not esssentially self-adjoint on a natural domain, i.e., each self-adjoint extension is a candidate for the right physical Hamiltonian. Traditional way to single out this Hamiltonian is the removing cut-offs for regularizing potential. Connecting regularization and extension theory we develop an abstract operator method to treat the problem of the right Hamiltonian. We show that, using the notion of the maximal (with respect to the perturbation) Friedrichs extension of unperturbed operator, one can classify the above problem as wellposed or ill-posed depending on intersection of the quadratic form domain of perturbation and deficiency subspace corresponding to restriction of unperturbed operator to stability domain. If this intersection is trivial, then the right Hamiltonian is unique: it coincides with the form sum of perturbation and the Friedrich extension of the unperturbed operator restricted to the stability domain. Otherwise it is not unique: the family of “right Hamiltonians” can be described in terms of symmetric extensions reducing the ill-posed problem to the well-posed problem.
Poisson Spaces with a Transition Probability
Authors: Landsman N. P.
Published: July 2002

The common structure of the space of pure states ℘ of a classical or a quantum mechanical system is that of a Poisson space with a transition probability. This is a topological space equipped with a Poisson structure, as well as with a function p:℘×℘→[0,1], with certain properties. The Poisson structure is connected with the transition probabilities through unitarity (in a specific formulation intrinsic to the given context).

In classical mechanics, where p(ρ,σ)=δρσ, unitarity poses no restriction on the Poisson structure. Quantum mechanics is characterized by a specific (complex Hilbert space) form of p, and by the property that the irreducible components of ℘ as a transition probability space coincide with the symplectic leaves of ℘ as a Poisson space. In conjunction, these stipulations determine the Poisson structure of quantum mechanics up to a multiplicative constant (identified with Planck's constant).

Motivated by E. M. Alfsen, H. Hanche-Olsen and F. W. Shultz (Acta Math.144 (1980) 267–305) and F.W. Shultz (Commun. Math. Phys.82 (1982) 497–509), we give axioms guaranteeing that ℘ is the space of pure states of a unital C*-algebra. We give an explicit construction of this algebra from ℘.
Improved Power Counting and Fermi Surface Renormalization
Authors: Salmhofer Manfred
Published: July 2002

The naive perturbation expansion for many-fermion systems is infrared divergent. One can remove these divergences by introducing counterterms. To do this without changing the model, one has to solve an inversion equation. We call this procedure Fermi surface renormalization (FSR). Whether or not FSR is possible depends on the regularity properties of the fermion self-energy. When the Fermi surface is nonspherical, this regularity problem is rather nontrivial. Using improved power counting at all orders in perturbation theory, we have shown sufficient differentiability to solve the FSR equation for a class of models with a non-nested, non-spherical Fermi surface. I will first motivate the problem and give a definition of FSR, and then describe the combination of geometric and graphical facts that lead to the improved power counting bounds. These bounds also apply to the four-point function. They imply that only ladder diagrams can give singular contributions to the four-point function.
Bargmann Representations for Deformed Harmonic Oscillators
Authors: Irac-Astaud Michèle , Rideau Guy
Published: July 2002

Generalizing the case of the usual harmonic oscillator, we look for Bargmann representations corresponding to deformed harmonic oscillators. Deformed harmonic oscillator algebras are generated by four operators a, a†, N and the unity 1 such as [a,N]=a,[a†,N]=-a†,a†a=ψ(N) and aa†=ψ(N+1). We discuss the conditions of existence of a scalar product expressed with a true integral on the space spanned by the eigenstates of a (or a†). We give various examples, in particular we consider functions ψ that are linear combinations of qN, q-N and unity and that correspond to q-oscillators with Fock-representations or with non-Fock-representations.
ON GENERALIZED ABELIAN DEFORMATIONS
Authors: DITO GIUSEPPE
Published: July 2002

We study sun-products on ℝn, i.e. generalized Abelian deformations associated with star-products for general Poisson structures on ℝn. We show that their cochains are given by differential operators. As a consequence, the weak triviality of sun-products is established and we show that strong equivalence classes are quite small. When the Poisson structure is linear (i.e. on the dual of a Lie algebra), we show that the differentiability of sun-products implies that covariant starproducts on the dual of any Lie algebra are equivalent each other.
WEIGHT GROUPINGS IN SECOND ORDER TRAINING METHODS FOR RECURRENT NETWORKS
Authors: CHAN Lai-Wan , SZETO Chi-Cheong
Published: July 2002

In this paper, we use block-diagonal matrix to approximate the Hessian matrix in the Levenberg Marquardt method during the training of recurrent neural networks. We analyze the weight updating strategies and the groupings of the weights associated with the approximation. Two weight updating strategies, namely asynchronous and synchronous updating methods are investigated. Asynchronous method updated weights of one block at a time while synchronous method updates all weights at the same time. Variations of these two methods, which involve the determination of two parameters μ and λ, are examined. Four weight grouping methods, correlation blocks, k-unit blocks, layer blocks and arbitrary blocks are investigated and compared. Their computational complexity, approximation ability, and training time is analyzed. Comparing with the original Levenberg Marquardt method, the block-diagonal approximation methods give substantial improvement in training time without degrading the generalization ability.
REMARK ON THE ARTICLE "SINGULAR LOCI IN HOLOMORPHIC FAMILIES"
Authors: HARRIS ADAM
Published: July 2002

To the basic assumptions that the map [Formula: see text] is a proper, flat morphism between complex manifolds should be added the hypothesis that the fibres of π are all generically reduced complex spaces. The existence of a non-empty open neighbourhood in [Formula: see text] plays an essential role in the proof of the main theorem, and does not follow automatically from the hypotheses as they were originally stated.
NUMERICAL SOLUTION OF THE ACOUSTIC WAVE EQUATION AT THE LIMIT BETWEEN NEAR AND FAR FIELD PROPAGATION
Authors: STOLL ERICH , DANGEL STEFAN
Published: July 2002

The acoustic wave equation is solved numerically for two and three-dimensional systems at the limit between near and far field propagation. Our results show that for large sound velocities, corresponding to wavelengths larger than the system, near field properties are dominant. When the near field conditions are no longer satisfied, standing waves close to the sound emitters and interference patterns between the near field and far field solutions appear. Our procedure is applied to sound sources, which broadcast coherent and continuous waves as well as to sources emitting bursts of incoherent and uncorrelated waves. Both cases can be used to simulate the spreading of low frequency seismic waves observed close to volcanoes and hydrocarbon reservoirs.
ON TELEGRAPH COUPLED MAP LATTICE AND ITS APPLICATIONS
Authors: AHMED E. , ABDUSALAM H. A. , FAHMY E. S.
Published: July 2002

In the present paper, we will study the general telegraph coupled map lattice and finite amplitude instability will be discussed. The persistence in telegraph reaction diffusion equation (TRD) will be studied in two dimensional systems and we show the critical size effect where phenomena persist only if the domain is large enough. Some applications are introduced and we made a simulation on the small world network, which is more realistic than the ordinary lattices in many cases.
REDUCED ${\mathcal N} =2$ QUANTUM MECHANICS: DESCENDANTS OF THE KÄHLER GEOMETRIES
Authors: LOSEV A. , SHIFMAN M.
Published: July 2002

We discuss an [Formula: see text] quantum mechanics with or without a central charge. A representation is constructed with the number of bosonic degrees of freedom less than one-half of the fermionic degrees of freedom. We suggest a systematic method of reducing the bosonic degrees of freedom called "dynamical reduction". Our consideration opens a problem of a general classification of nonstandard representations of [Formula: see text] superalgebra.
THE MASS RELATION BETWEEN THE PURE AND PHYSICAL GROUND PSEUDOSCALAR GLUEBALLS
Authors: LI DE-MIN , YU HONG , SHEN QI-XING
Published: July 2002

The experimental information indicates that for the ground pseudoscalar states, the omission of the transition amplitudes between quarkonia can result in the unreasonable result. It is believed that the mass of the pure glueball employed in the general form of the mass matrix is different from the mass predicted by lattice QCD in quenched approximation for the ground pseudoscalar glueball. The mass relation between the pure and physical ground pseudoscalar glueballs is determined from the experimental data.
EXPLICIT DERIVATION OF THE FLUCTUATION-DISSIPATION RELATION OF THE VACUUM NOISE IN THE N-DIMENSIONAL DE SITTER SPACE–TIME
Authors: MURATA T. , TSUNODA K. , YAMAMOTO K.
Published: July 2002

Motivated by a recent work by Terashima (Phys. Rev.D60, 084001), we revisit the fluctuation-dissipation (FD) relation between the dissipative coefficient of a detector and the vacuum noise of fields in curved space–time. In an explicit manner we show that the dissipative coefficient obtained from classical equations of motion of the detector and the scalar (or Dirac) field satisfies the FD relation associated with the vacuum noise of the field, which demonstrates that Terashima's prescription works properly in the N-dimensional de Sitter space–time. This practice is useful not only to reconfirm the validity of the use of the retarded Green function to evaluate the dissipative coefficient from the classical equations of motion but also to understand why the derivation works properly, which is discussed in connection with previous investigations on the basis of the Kubo–Martin–Schwinger (KMS) condition. Possible application to black hole space–time is also briefly discussed.
ON THE ALGEBRAIC K THEORY OF THE MASSIVE D8 AND M9-BRANES
Authors: VANCEA ION V.
Published: July 2002

In this paper we review some basic relations of algebraic K theory and we formulate them in the language of D-branes. Then we study the relation between the D8-branes wrapped on an orientable compact manifold W in a massive Type IIA supergravity background and the M9-branes wrapped on a compact manifold Z in a massive d=11 supergravity background from the K-theoretic point of view. By interpreting the D8-brane charges as elements of K0(C(W)) and the (inequivalent classes of) spaces of gauge fields on the M9-branes as the elements of [Formula: see text] where G is a one-dimensional compact group, a connection between charges and gauge fields is argued to exists. This connection could be realized as a composition map between the corresponding algebraic K theory groups.
QUALITATIVE ANALYSIS OF A SCALAR–TENSOR THEORY WITH EXPONENTIAL POTENTIAL
Authors: BATISTA A. B. , FABRIS J. C. , GONÇALVES S. V. B. , TOSSA J.
Published: July 2002

A qualitative analysis of a scalar–tensor cosmological model, with an exponential potential for the scalar field, is performed. The phase diagram for the flat case is constructed. It is shown that solutions with an initial and final inflationary behavior appear. We discuss the possible existence of realistic scenarios and we generalize the results, adding ordinary matter to the scalar–tensor model.
SECOND ORDER QUANTUM CORRECTIONS TO THE CLASSICAL REFLECTION FACTOR OF THE SINH–GORDON MODEL
Authors: CHENAGHLOU A.
Published: July 2002

The sinh–Gordon model on a half-line with integrable boundary conditions is considered in low order perturbation theory developed in affine Toda field theory. The quantum corrections to the classical reflection factor of the model are studied up to the second order in the difference of the two boundary parameters and to one loop order in the bulk coupling. It is noticed that the general form of the second order quantum corrections are consistent with Ghoshal's formula.
A HIGH-PT TRIGGER FOR THE HERA-B EXPERIMENT
Authors: MOHAPATRA A. K.
Published: July 2002

We have constructed a high-pT trigger for the HERA-B experiment at DESY. The HERA-B experiment produces B mesons by inserting wire targets into the halo of the proton beam circulating in HERA. The high-pt trigger records events that contain tracks that have high transverse momentum with respect to the beam. Such a trigger is efficient for recording B → π+π-, B → K- π+, Bs → K+ K-, [Formula: see text], and other topical hadronic B decays. These decays provide sensitivity to the internal angles alpha and gamma of the CKM unitarity triangle, and they also can be used to measure or constrain the [Formula: see text] mixing parameter xs.
Reorganizing Finite Temperature Field Theory: Part I.: Scalar Field Theory
Authors: Strickland Michael
Published: July 2002

I present a method for self-consistently including the effects of screening in finite-temperature field theory calculations. The method reproduces the perturbative limit in the weak-coupling limit and for intermediate couplings this method has much better convergence than standard perturbation theory. The method relies on a reorganization of perturbation theory accomplished by shifting the expansion point used to calculate quantum loop corrections. I will present results from a three-loop calculation within this formalism for scalar λϕ4.
INTEGRALS OVER PRODUCTS OF DISTRIBUTIONS FROM PERTURBATION EXPANSIONS OF PATH INTEGRALS IN CURVED SPACE
Authors: KLEINERT H. , CHERVYAKOV A.
Published: July 2002

We show that the requirement of coordinate invariance of perturbatively defined quantum-mechanical path integrals in curved space leads to an extension of the theory of distributions by specifying unique rules for integrating products of distributions. The rules are derived by using equations of motion and partial integration, while keeping track of certain minimal features stemming from the unique definition of all singular integrals in 1 - ∊ dimensions. Our rules guarantee complete agreement with much more cumbersome calculations in 1 - ∊ dimensions where the limit ∊ → 0 is taken at the end. In contrast to our previous papers where we solved the same problem for an infinite time interval or zero temperature, we consider here the more involved case of finite-time or temperature amplitudes.
CASIMIR ENERGY OF A DILUTE DISPERSIVE DIELECTRIC BALL: REALISTIC MICROSCOPIC MODEL
Authors: MARACHEVSKY VALERY N.
Published: July 2002

The Casimir energy of a dilute homogeneous nonmagnetic dielectric ball at zero temperature is derived analytically within a microscopic realistic model of dielectrics for an arbitrary physically possible frequency dispersion of dielectric permittivity ε(iω). Divergences are absent in calculations, a minimum interatomic distance λ is a physical cut-off. Casimir surface force is proved to be a attractive. A physical definition of the Casimir energy is discussed.
COLLECTIVE MODES IN COLOR SUPERCONDUCTING MATTER
Authors: SHOVKOVY IGOR A.
Published: July 2002

The properties of plasmons, Nambu-Goldstone bosons and gapless Carlson-Goldman collective modes in color-flavor locked phase of color superconducting dense quark matter at finite temperature are reviewed. A possibility of a kaon condensation with an abnormal number of the NG bosons is also discussed.
TRANSMISSION COEFFICIENTS IN A NARROW CONSTRICTION THREADED BY TWO IMPENETRABLE MAGNETIC FLUX TUBES
Authors: LIANG H. C.
Published: July 2002

The transmission coefficients in a narrow constriction and their dependence on the Fermi energy and on the transverse positions of two impenetrable magnetic flux tubes is studied. An overlapping integral Lmn can qualitatively represent the strength of interaction between incoming subb and m and outgoing subb and n. The conductance G and its components exhibit oscillatory-like behavior as the transverse positions of the tubes change.
MEAN-FIELD TRANSITION TEMPERATURE OF STRONGLY DISORDERED SUPERCONDUCTORS
Authors: HERBUT IGOR F.
Published: July 2002

I discuss the mean-field theory of superconductivity in a strongly disordered system of fermions with short-range attraction. It is argued that in this limit the effective theory at low energies is equivalent to the disordered Bose–Hubbard model, and I consider both the infinite-range and the "nearest-neighbor" hopping of bosons between the localized states. In the infinite-range case the mean-field theory is exact, and the superconducting gap is uniform in space, while in the latter case, the gap becomes highly non-uniform in space, but, surprisingly, is finite everywhere at T < T MF . I find that the mean-field transition temperature T MF > 0 always, and argue that the superconductor–insulator transition at T = 0 in models with net attraction between fermions is in the universality class of "dirty-bosons".
EVIDENCE FOR STRIPE PHASE FORMATION IN HgBa2CuO4+δ SUPERCONDUCTOR
Authors: FARBOD M.
Published: July 2002

Single-phase samples of HgBa 2 CuO 4+δ(Hg1201) are studied by thermoelectric power (TEP) measurements. The results show a dip in T c ( p ) at a hole density p ~1/8, similar to the one seen for the La 1.875 Ba 0.125 CuO 4 and related systems. The observation of this dip could be a signature of stripe phase in Hg1201 superconductor. The data are discussed in terms of 1D versus 2D stripe phases.
WHAT CAN WE LEARN FROM COMPARISON BETWEEN CUPRATES AND HE FILMS?: PHASE SEPARATION AND FLUCTUATING SUPERFLUIDITY
Authors: UEMURA Y. J.
Published: July 2002

In the underdoped, overdoped, Zn-doped or stripe-forming regions of high-Tc cuprate superconductors (HTSC), the superfluid density ns/m* at T→ 0 shows universal correlations with Tc. Similar strong correlations exist between 2-dimensional superfluid density and superfluid transition temperature in thin films of 4 He in non-porous or porous media, and 4 He /3 He film adsorbed on porous media. Based on analogy between HTSC and He film systems, we propose a model for cuprates where: (1) the overdoped region is characterized by a phase separation similar to 4 He /3 He ; and (2) pair (boson) formation and fluctuating superconductivity occur at separate temperatures above Tc in the underdoped region.
PEAK, DIP AND HISTORY EFFECTS OF VORTEX MATTER
Authors: DING S. Y. , WU X. F.
Published: July 2002

We review some recent developments in the study on the peak effect (PE) in critical current, the dip effect (DE) and history effect (HE) in AC susceptibility studied numerically and experimentally. Although a great number of studies on these "hot topics" have been made, their mechanisms are still debating. Therefore we focus here on the results associated with those of our group, including the equivalency of PE and DE, their future caused by different mechanisms.
THE A-C-A PHASE DIAGRAM OF MIXED LIQUID CRYSTALS: A PHOTON TRANSMISSION STUDY
Authors: ÖZBEK HALUK , YILDIZ SEVTAP , PEKCAN ÖNDER , BERKER A. NIHAT
Published: July 2002

Ultraviolet/visible photon transmission technique was applied to study the phase diagram of the BOPDOB-BOPOOB liquid crystal system. It was observed that the nematic-smectic A transition becomes first order, as the weight percentage of BOPDOB in the binary mixture is increased. The smectic A-C-A reentrance disappears when the BOPDOB percentage approaches 100 (pure BOPDOB). We also present the smectic A-C transition temperatures and the critical exponents β of the all samples. The values of the exponent are consistent with mean-field theory.
PROTON SINGLE PARTICLE ENERGY SHIFTS DUE TO COULOMB CORRELATIONS
Authors: BULGAC A. , SHAGINYAN V. R.
Published: July 2002

A theoretically consistent approach to the calculation of the Coulomb energy of nuclei is presented. New contributions to the single-particle energies are taken into account. We show that the interplay between the Coulomb interaction and the strong interaction leads to an upward shift of the proton single-particle levels, affecting the position of the calculated proton drip line. The same contributions are responsible for significant corrections to the mass difference of the mirror nuclei (Nolen-Schiffer anomaly) and to the effective proton mass.
FIELD THEORETIC CALCULATION OF SCALAR TURBULENCE
Authors: VERMA MAHENDRA K.
Published: July 2002

The cascade rate of passive scalar and Bachelor's constant in scalar turbulence are calculated using the flux formula. This calculation is done to first order in perturbation series. Batchelor's constant in three dimension is found to be approximately 1.25. In higher dimension, the constant increases as d1/3.
ELECTRON-ENERGY RELAXATION IN POLAR SEMICONDUCTOR DOUBLE QUANTUM DOTS
Authors: KRÁL K. , KHÁS Z. , ZDENĚK P. , ČERŇANSKÝ M. , LIN C. Y.
Published: July 2002

The zero-dimensional semiconductor nanostructures belong to the candidates for the realization of the quantum bits. They are expected to be scalable for the purpose of tuning their physical properties. In these structures the quantum bit could be realized in the form of a single quantum dot with two electronic energy levels, with only one electron in the dot. As the basic states of the quantum bit, realized in this way, the two orbital states of the electron in the dot could be used. It appears however that usually the relaxation of the energy of the electron from the excited energy level is often rather fast in the polar semiconductor quantum dots. It is the purpose of this paper to present calculations of the relaxation rate of the electron in an asymmetric pair of tunneling coupled quantum dots, in which the two electronic orbitals of the quantum bit are located each in a separate dot. The calculation of the electronic energy relaxation is based on the multiple electron-LO-phonon scattering processes, implemented to the theory via the electronic self-energy taken in the self-consistent Born approximation. The dependence of the relaxation rate on the geometry of the pair of the coupled dots and on the lattice temperature is presented for a realistic model of this nanostructure.
PHASE TRANSTIONS IN THE 3-DIMENSIONAL 16-VERTEX MODEL
Authors: STERN R. ADAM , TUTHILL GEORGE F.
Published: July 2002

A three-dimensional sixteen-vertex model on the diamond lattice describing proton ordering in KDP-type crystals is shown to exhibit both 1 st - and 2 nd -order phase transitions. The model's critical behavior was found, using analyses of series expansions and Monte Carlo simulations. When the transition is 2 nd -order, critical exponents belong to the universality class of the three-dimensional Ising model.
SIZE AND SURFACE STRUCTURE OF DIAMOND NANO-CRYSTALS
Authors: BURSILL L. A. , FULLERTON ANNA L. , BOURGEOIS LAURE N.
Published: July 2002

High-resolution transmission electron microscopy and electron nano-diffraction patterns provide useful information concerning the size distribution and surface condition of nano-crystalline diamond powder produced by shock detonation. Analysis of X-ray powder diffractometer data, using the Debye equation to predict the powder profile, starting with a set of spherical diamond ball models, allows the mean size to be obtained for bulk quantities of the same powders. The electron powder diffraction patterns for some diamond spheres, and also spherical shell, models of the surface structures were calculated using the Debye equation, and compared with experiment. It is suggested that the surface structure may become accessible to diffraction methods, if a single nano-crystal is irradiated and both the single crystal pattern plus the diffuse scattering are recorded, as a function of the orientation of that single crystal.
SUPERCONDUCTIVITY WITH SOFT LATTICE MODES IN LaBaCuO and YBaCuO
Authors: NETTEL STEPHEN
Published: July 2002

The canonical transformation employed in polaron theory at intermediate coupling is generalized to the electron phonon interaction of an entire band of electrons. Interelectron interactions result. The overall lattice-electron correlation is obtained with a variational calculation, balancing the extra elastic energy stored in the lattice against the negative energy arising from BCS pair correlation. The requisite phonon softening to attain any given value of Tc in metallic LaBaCuO and YBaCuO are estimated. The implicit fluctuations in the lattice normal coordinates are compared with results yielded by the EXAFS measurements of Oyanagi et al.
PHOTOPHYSICS OF CONFINED EXCITONS IN CuCl NANOPARTICLES - CONFINEMENT OF EXCITON EXCITED STATES -
Authors: ITOH T. , YAMANAKA K. , EDAMATSU K. , UOZUMI T. , KAYANUMA Y.
Published: July 2002

Exciton excited states of CuCl nanoparticles dispersed in NaCl matrix have been investigated by means of two-photon excitation and two-step IR transient absorption. In the two-photon excitation spectra, there appears a distinct absorption edge. As the particle radius decreases from 6.3nm to 1.6nm, the edge energy increases by about 0.15eV, more than twice as large as that of the lowest 1S state. The fast decay component of the IR transient absorption under pulsed excitation of the lowest 1S exciton shows a broad band which shifts from 0.2 to 0.4eV as the radius decreases from >10nm to 1.4nm. These absorption edge and band are ascribed to the nP-like Rydberg excited states of the confined excitons. The large energy shift indicates that the weak confinement which is typically valid for the lowest 1S exciton state in CuCl nanoparticles is no more applicable to these excited states. Their spectra and confinement effect are discussed in comparison with theoretical prediction.
INNER-SHELL TRANSITIONS AND SECONDARY EXCITONS IN SOLID XE AND KR
Authors: VIELHAUER S. , GMINDER E. , KIRM M. , KISAND V. , NEGODIN E. , STEEG B. , ZIMMERER G.
Published: July 2002

Time-resolved photoluminescence of the exciton emission in rare gas solids has been measured for excitation in the range of inner-shell transitions. The excitons are created both 'promptly' (within the experimental time resolution) and 'delayed' through electron-hole recombination. Excitation spectra at the 4d edge in Xe and the 3d edge in Kr are discussed. An outstanding feature of the time resolved spectra is the strong resonance that appears in a short time window above a threshold energy, which is the sum of the ionisation energy of the core level and the energy of the (valence) free exciton.
High Density Exciton Dynamics of CuBr Nanocrystals Embedded in PMMA
Authors: Oda M. , Shen M. Y. , Goto T.
Published: July 2002

When CuBr nanocrystals (NCs) embedded in poly methyl methacrylate are strongly excited, there appears a new luminescence band at the low energy side of exciton luminescence peak. The luminescence band is associated with biexcitons in the CuBr NCs. As the excitation intensity increases, the biexciton luminescence band shows obvious broadening, while the exciton band does not. Interaction among more than three excitons may cause this broadening effect. Optical gain has also been found by pump-probe measurement around the biexciton luminescence band at 77K. The decay time of the optical gain 15ps coincides with that of the biexciton luminescence band, which means that the lifetime of the biexciton is 15ps.
POLYETHYLENEOXIDE: KINETICS AND POLYMERIZATION HEAT MEASUREMENTS FOR THE PROCESS OF CATALYTIC POLYMERIZATION IN A SOLID-GAS SYSTEM FREE OF SOLVENT
Authors: OSTROVSKII VICTOR E. , KHODZHEMIROV V. A.
Published: July 2002

The process of polymerization of ethylene-oxide (EO) vapor to solid polyethyleneoxide (PEO) at the dry KOH catalyst with no solvent is studied at 298 K and a monomer pressure up to 400 Torr. The maximum rate observed is about 1.5·10-7 mol/s per 1 cm3 of the catalyst at 760 Torr; therewith, potentialities of intensification of the process are not exhausted. It is found that, at any fixed degree of polymerization, the rate of the process is proportional to the monomer pressure. A phenomenon of gradual increasing in the rate of polymerization with the degree of polymerization is observed. The ΔH0298 value measured for the reaction n (EO) (gas) = (-EO-) n(solid) is equal to -140.5 ± 3.8 kJ/mol; by using this value, ΔH (liq. EO Π sol.. PEO) = -109.20 kJ/mol is computed. The calorimetric results and the nature of the phenomenon revealed are discussed.
BROADENING OF FANO RESONANCE IN ELECTRONIC CURRENT THROUGH A QUANTUM DOT BY DEPHASING
Authors: XIONG YONG-JIAN , XIONG SHI-JIE
Published: July 2002

We investigate the Fano line shape in electron transport through a quantum dot in presence of dephasing. The dephasing effect is introduced by the Büttiker model. We derive a generalized Fano formula for the conductance that includes the components of the standard Fano line shape and the Breit–Wigner line shape. According to this formula the Fano parameter |q| decreases when the dephasing strength increases by increasing the temperature. The increase of the half width of the resonance peak by increasing the temperature measured by Zacharia et al. [Phys. Rev.B64, 155311 (2001)] which is more rapid than expected from the ordinary theories is possibly attributed to the dephasing.
HIGH Tc SUPERCONDUCTIVITY IN DIBORIDES BY MICRO-STRAIN AND FERMI LEVEL TUNING
Authors: BIANCONI A.
Published: July 2002

It is shown that the process of T c amplification in diborides occurs in a particular region of the (ρ,ε) phase diagram, where ρ is the charge density and ε is the micro-strain in the metallic boron plane. The T c (ρ,ε) shows that the superconducting phase occurs while the chemical potential is tuned near the "shape resonance" of the diboride superlattice and the micro-strain is in a critical range. The range of the high T c phase is determined by the modulation amplitude Δshape of the shape resonance energy due to the zero-point lattice vibrations Δu rms (ε), pointing towards an electronic or vibronic pairing mechanism. It has been discussed that the McMillan's formula breaks down for the diborides.
THERMODYNAMICS OF TWO COMPONENT BOSONS IN ONE DIMENSION
Authors: GU SHI-JIAN , LI YOU-QUAN , YING ZU-JIAN , ZHAO XUE-AN
Published: July 2002

On the basis of Bethe ansatz solution of two-component bosons with SU(2) symmetry and δ-function interaction in one dimension, we study the thermodynamics of the system at finite temperature by using the strategy of thermodynamic Bethe ansatz (TBA). It is shown that the ground state is an isospin "ferromagnetic" state by the method of TBA, and at high temperature the magnetic property is dominated by Curie's law. We obtain the exact result of specific heat and entropy in strong coupling limit which scales like T at low temperature. While in weak coupling limit, it is found there is still no Bose-Einstein Condensation (BEC) in such 1D system.
R-MATRICES AND THE TENSOR PRODUCT GRAPH METHOD
Authors: GOULD MARK D. , ZHANG YAO-ZHONG
Published: July 2002

A systematic method for constructing trigonometric R-matrices corresponding to the (multiplicity-free) tensor product of any two affinizable representations of a quantum algebra or superalgebra has been developed by the Brisbane group and its collaborators. This method has been referred to as the Tensor Product Graph Method. Here we describe applications of this method to untwisted and twisted quantum affine superalgebras.
RENORMALIZATION ANALYSIS OF INTERMITTENCY IN TWO COUPLED MAPS
Authors: KIM SANG-YOON
Published: July 2002

The critical behavior for intermittency is studied in two coupled one-dimensional (1D) maps. We find two fixed maps of an approximate renormalization operator in the space of coupled maps. Each fixed map has a common relavant eigenvalue associated with the scaling of the control parameter of the uncoupled one-dimensional map. However, the relevant "coupling eigenvalue" associated with coupling perturbation varies depending on the fixed maps. These renormalization results are also confirmed for a linearly-coupled case.
SUPERPOSITIONS OF COHERENT STATES AND SQUEEZING EFFECTS IN A MESOSCOPIC JOSEPHSON JUNCTION
Authors: ZOU JIAN , SHAO BIN
Published: July 2002

We consider a mesoscopic Josephson junction in a circular superconducting ring which encloses a magneto static flux. It is shown that with the junction being initially prepared in its lowest energy level the state of the junction can evolve in a quantum superposition of two coherent states, and squeezing can exist in such system.