bluuebunny/crossref_metadata_2025 huggingface dataset:
Hyperemesis gravidarum: current concepts and management
Authors: Kuşcu N K , Koyuncu F
Published: July 2002

Hyperemesis gravidarum is a common problem for an obstetrician. Though nausea and vomiting are quite common in pregnancy, hyperemesis is found in only 1–20 patients per 1000. In this practical review, a general outline of the syndrome, its relation to the gastrointestinal system and thyroid, mild and rare severe complications, and conventional treatment versus newer options are discussed.
Smoking in correctional facilities: a survey of employees
Authors: Carpenter Matthew J , Hughes John R , Solomon Laura J , Powell Thomas A
Published: July 2002

OBJECTIVE

To assess level of endorsement and expected consequences of worksite smoking restriction policies among correctional employees.

DESIGN

Mailed survey to Vermont state correctional employees.

MAIN OUTCOME MEASURES

Support for various policy alternatives for both staff and inmate smoking; expected consequences of restrictive smoking policies and smoking behaviour.

PARTICIPANTS

321 of 640 (50%) state correctional employees responded.

RESULTS

Employees were somewhat receptive to smoking restrictions for inmates, but less supportive of staff smoking restrictions. A complete ban on inmate smoking both indoors and outdoors was supported by 56% and 49% of never and ex-smokers, respectively, but only 15% of current smokers (p < 0.01). A similar ban on employee smoking was supported by 38% of never and ex-smokers, but only 3% of current smokers (p < 0.01). Overall, employees were most supportive (52%) of a policy for themselves that banned indoor smoking and restricted it to certain areas outdoors. Current smokers were more likely to expect negative consequences as a result of further restrictions than were never or ex-smokers.

CONCLUSIONS

Although our findings are limited by a low response rate, most employees support an indoor ban, but not a total ban on smoking. Employees generally favoured a policy that was slightly more restrictive than the current policy, but were less supportive of tighter smoking restrictions for themselves. However, a more restrictive smoking policy is likely to result in some degree of resistance among current smoking employees, who may require specific attention to address their opposition.
Tobacco commerce on the internet: a threat to comprehensive tobacco control
Authors: COHEN JOANNA E , SARABIA VIVIAN , ASHLEY MARY JANE
Published: July 2002

Although internet use continues to increase and e-commerce sales are expected to exceed US$1 trillion by the end of 2001, there have been few assessments in the literature regarding the implications of this medium for tobacco control efforts. This commentary explores the challenges that the internet may pose to the key components of a comprehensive tobacco control strategy, and pinpoints potential approaches for addressing these challenges. Four key challenges that the internet presents for tobacco control are identified: unrestricted sales to minors; cheaper cigarettes through tax avoidance and smuggling; unfettered advertising, marketing and promotion; and continued normalisation of the tobacco industry and its products. Potential strategies for addressing these challenges include international tobacco control agreements, national and state regulation, and legal remedies.
Cigarette nicotine yields and nicotine intake among Japanese male workers
Authors: Ueda K , Kawachi I , Nakamura M , Nogami H , Shirokawa N , Masui S , Okayama A , Oshima A
Published: July 2002

Objectives: To analyse brand nicotine yield including “ultra low” brands (that is, cigarettes yielding ≤ 0.1 mg of nicotine by Federal Trade Commission (FTC) methods) in relation to nicotine intake (urinary nicotine, cotinine and trans-3'-hydroxycotinine) among 246 Japanese male smokers.

Design: Cross sectional study.

Setting: Two companies in Osaka, Japan.

Subjects: 130 Japanese male workers selected randomly during their annual regular health check up and 116 Japanese male volunteers taking part in a smoking cessation programme.

Main outcome measurements: Subjects answered a questionnaire about smoking habits. Following the interview, each participant was asked to smoke his own cigarette and, after extinguishing it, to blow expired air into an apparatus for measuring carbon monoxide concentration. Urine was also collected for the assays of nicotine metabolites.

Results: We found wide variation in urinary nicotine metabolite concentrations at any given nicotine yield. Based on one way analysis of variance (ANOVA), the urinary nicotine metabolite concentrations of ultra low yield cigarette smokers were significantly lower compared to smokers of high (p = 0.002) and medium yield cigarettes (p = 0.017). On the other hand, the estimated nicotine intake per ultra low yield cigarette smoked (0.59 mg) was much higher than the 0.1 mg indicated by machine.

Conclusions: In this study of Japanese male smokers, actual levels of nicotine intake bore little relation to advertised nicotine yield levels. Our study reinforces the need to warn consumers of inappropriate advertisements of nicotine yields, especially low yield brands.
Pollination ecology ofPhilodendron squamiferum(Araceae)
Authors: Gibernau Marc , Barabé Denis
Published: July 2002

In French Guiana, inflorescences of Philodendron squamiferum Poepp. (Araceae) were regularly visited by the scarab beetle Cyclocephala simulatrix Hölne and (Scarabaeidae, Coleoptera) occasionally by Cyclocephala tylifera Hölne. The flowering cycle lasted 2 days, and the protogynous inflorescence exhibited features typical of beetle pollination (floral chamber, food rewards, flower heating). The spadix temperature was measured during the entire flowering cycle in French Guiana and at the Montreal Botanical Garden. Both sets of measurements gave a similar temperature pattern. The spadix warmed up twice at the beginning of each evening with no notable heat production between the two peaks. These two temperature peaks were well synchronized with the arrival and departure of beetles.Key words: beetle pollination, Cyclocephala, Dynastidae, floral traits, thermogenesis, French Guiana.
Organic substances in cave drip waters: studies from Marengo Cave, Indiana
Authors: van Beynen Philip E , Schwarcz Henry P , Ford Derek C , Timmins G T
Published: July 2002

This paper focuses on the flux and characterization of organic substances in cave drip waters for a continental climate. At Marengo Cave in southern Indiana, there is seasonal variations in organic matter concentration in the cave drip water. High levels are introduced during the spring thaw, and lower levels occur during the rest of the year. The fluorescence spectra and ultrafiltration analysis suggest the majority of the organics contained in percolating waters were fulvic acids, with most being less than 1 kDa in size. The seasonal flush of organics from the soil could produce two different types of calcite in the speleothem deposited from these drip waters, a stronger fluorescing calcite during the spring and the less fluorescent calcite during the rest of the year. This is the first study of its type for this particular climatic region.
Effectiveness of sealers in counteracting alkali-silica reaction in plain and air-entrained laboratory concretes exposed to wetting and drying, freezing and thawing, and salt water
Authors: Bérubé Marc-André , Chouinard Dominique , Pigeon Michel , Frenette Jean , Boisvert Luc , Rivest Michel
Published: July 2002

Low- and high-alkali, plain and air-entrained large concrete cylinders, 255 mm in diameter by 310 mm in length, were made with a highly alkalisilica reactive limestone. After curing, a number of cylinders were sealed with silane, oligosiloxane, polysiloxane, linseed oil, or epoxy, with others subjected to 179 freezing and thawing cycles in humid air (one cycle per day). All cylinders were then subjected to 14-day exposure cycles, including in the most severe case periods of humid storage in air, drying, wetting in salt water, and freezing and thawing cycles. All low-alkali specimens did not either expand or develop surface cracking, even those with a deficient air void system and exposed to freezing and thawing cycles. All unsealed high-alkali cylinders subjected early to a series of freezing and thawing cycles did not significantly expand during these cycles, but presented high expansion afterwards. Wetting and drying significantly reduced alkalisilica reaction (ASR) expansion compared with constant humid storage; however, it promoted map-cracking. Regardless of the air content, freezing and thawing increased greatly the concrete expansion in the presence of ASR, even after ASR was almost complete; freezing and thawing also greatly promoted surface cracking. On the other hand, all cylinders early sealed with silane, oligosilixane, or polysiloxane did not either significantly expand or show map-cracking, whatever the exposure conditions and the air content; these cylinders progressively lost mass with time. On the other hand, the epoxy resin was not effective. The linseed oil prevented map-cracking while significantly reducing expansion, however not sufficiently. After one or 1.5 years, some expanding cylinders were sealed with silane, oligosiloxane, or polysiloxane; they started to loose mass and contracted immediately after being sealed, whatever the exposure conditions. The results obtained thus indicate that a good sealer may greatly improve the aesthetic appearance (e.g., map-cracking) and stop expansion of ASR-affected concrete elements of 255 mm or less in thickness, made with a water-to-cement ratio in the range of 0.50, and exposed to wetting and drying, freezing and thawing, and salt water.Key words: air entrained, alkalisilica reaction, concrete, cracking, expansion, freezing and thawing, sealer, silane, siloxane, wetting and drying.
Insulin sensitivity regulated by feeding in the conscious unrestrained rat
Authors: Latour Martin G , Lautt W Wayne
Published: July 2002

Hepatic insulin sensitizing substance (HISS), a putative hormone released from the liver in response to insulin in fed animals, accounts for 5060% of insulin action. HISS release is regulated by permissive control of the hepatic parasympathetic nerves. The objectives were to develop the rapid insulin sensitivity test (RIST) in conscious rats, and to assess the effects of anesthesia, atropine, feeding, and fasting on insulin action. The RIST index, expressed as milligrams glucose per kilogram body weight required to maintain euglycemia after a 50 mU/kg bolus of insulin, was similar in conscious and anesthetized rats (238.6 ± 42.5 vs. 225.3 ± 30.4 mg/kg). Atropine produced a 56% inhibition of insulin action in fed rats. After a 24 h fast, full HISS-dependent insulin resistance had developed as shown by a low RIST index that was not reduced further by atropine. Fasting caused a 10.5% decrease in insulin action per hour over six hours. HISS-dependent insulin resistance in 24-h fasted rats was reversed 4 h after re-feeding (90.9 ± 12.3 vs. 204.5 ± 30.5 mg/kg). We conclude that HISS-dependent and HISS-independent insulin action, as assessed by the RIST, is similar in conscious and pentobarbital-anesthetized rats. Pharmacological blockade of HISS-dependent insulin action and physiological regulation of HISS action by feedingfasting is confirmed. Re-feeding fasted rats reversed HISS-dependent insulin resistance. Merits of use of the RIST in conscious versus anesthetized rats are discussed.Key words: insulin action, insulin resistance, anesthetic effect, glucose, fasting, HISS.
Formation of the gut in the first two naupliar stages of Acartia clausi and Hemidiaptomus roubaui (Copepoda, Calanoida): comparative structural and ultrastructural aspects
Authors: Baud A , Barthélémy R -M , Nival S , Brunet M
Published: July 2002

In this study, the structure and ultrastructure of the digestive system are compared in the early larval stages (nauplii I and II) of two copepod calanoid species, Acartia clausi Giesbrecht, 1889 and Hemidiaptomus roubaui Richard, 1888. The nauplii I of both species have no functional digestive tract, which is represented initially only by a blind esophageal slit and yolky endodermal cells, which fill the most part of the naupliar body, whereas at the nauplius II stage the differentiated digestive tract becomes functional. The resorption cavity corresponding to the future midgut is progressively formed in the endodermal mass during the premolt phase; it is surrounded by differentiating epithelial cells. In the ecdysial phase the foregut has associated labral glands, the midgut young R-, B-, and R'-cells of epithelium, and there is a short open hindgut.
PARALLEL COMMUNICATING PUSHDOWN AUTOMATA SYSTEMS
Authors: CSUHAJ-VARJÚ ERZSÉBET , MARTÍN-VIDE CARLOS , MITRANA VICTOR , VASZIL GYÖRGY
Published: July 2002

We consider automata systems consisting of several pushdown automata working in parallel and communicating the contents of their stacks by request, using a communication strategy borrowed from grammar system theory. We investigate the computational power of these mechanisms. We prove that non-centralized parallel communicating pushdown automata systems with a bounded number of components, where each automaton is allowed to issue a query, are able to recognize all recursively enumerable languages. We also present homomorphical characterizations of the class of recursively enumerable languages for the centralized variants, where only a distinguished automaton issues queries. Moreover, we show that these centralized variants are at least as powerful as one-way multihead pushdown automata. Finally, some open problems and further directions of research are discussed.
BORN–OPPENHEIMER APPROXIMATION FOR THE BROWN–RAVENHALL EQUATION
Authors: SORDONI VANIA
Published: July 2002

In this paper we study the pseudo-relativistic Hamiltonian proposed by Brown and Ravenhall in the semiclassical limit when the mass ratio h2 of electronic to nuclear mass tends to zero. We show that the relativistic contribution of the nuclei on WKB-type expansions of the first energy levels are of order o(h2), as h→0.
HEAT KERNEL ASYMPTOTICS OF OPERATORS WITH NON-LAPLACE PRINCIPAL PART
Authors: AVRAMIDI IVAN G. , BRANSON THOMAS
Published: July 2002

We consider second-order elliptic partial differential operators acting on sections of vector bundles over a compact Riemannian manifold without boundary, working without the assumption of Laplace-like principal part -∇μ∇μ. Our objective is to obtain information on the asymptotic expansions of the corresponding resolvent and the heat kernel. The heat kernel and the Green's function are constructed explicitly in the leading order. The first two coefficients of the heat kernel asymptotic expansion are computed explicitly. A new semi-classical ansatz as well as the complete recursion system for the heat kernel of non-Laplace type operators is constructed. Some particular cases are studied in more detail.
A DETAILED ACCOUNT OF ALAIN CONNES’ VERSION OF THE STANDARD MODEL IN NON-COMMUTATIVE DIFFERENTIAL GEOMETRY III
Authors: KASTLER DANIEL
Published: July 2002

We describe in detail Alain Connes’ last presentation of the (classical level of the) standard model in noncommutative differential geometry, now free of the cumbersome adynamical fields which parasited the initial treatment. Accessorily, the theory is presented in a more transparent way by systematic use of the skew tensor-product structure, and of 2×2 matrices with 2×2 matrix-entries instead of the previous 4×4 matrices.
A NOTE ON QUATERNION–KÄHLER MANIFOLDS
Authors: PODESTÁ F. , VERDIANI L.
Published: July 2002

The aim of this paper is to show that a compact quaternion–Kähler manifolds which is acted on isometrically by a compact Lie group G with a hypersurface orbit is a symmetric space. This result, already proved by A. Dancer and A. Swann for G semisimple, is now completed in the reductive case.
MULTICANONICAL SIMULATION OF SPIN SYSTEMS WITH BOND RANDOMNESS
Authors: YAŞAR FATİH
Published: July 2002

In order to test the multicanonical approach in simulations of the spin systems with quenched bond randomness, I simulated the q = 8 state Potts model in two dimensions with various degrees of randomness. It appears quite feasible to simulate spin systems with quenched bond randomness by multicanonical algorithm, but extra care is needed with increasing randomness.
EXACT SOLUTIONS OF THE SELF-DUALITY EQUATIONS ON THE MINKOWSKI SPACE-TIME
Authors: MANTA V. , ZET G.
Published: July 2002

A SU(2) Gauge Theory with spherical symmetry over the Minkowski space-time is considered. The self-duality equation of the gauge fields are written and their solutions are obtained. Two exact solutions, one of which is statical and another of dynamical type are given. All the calculations are performed using an analytical program written in GRTensor computer algebra package, which runs on the MapleV platform.
A CLASSICAL KINETIC THEORY APPROACH TO LATTICE BOLTZMANN SIMULATION
Authors: MARTYS NICOS S.
Published: July 2002

An approach to lattice Boltzmann simulation is described, which makes a direct connection between classical kinetic theory and contemporary lattice Boltzmann modeling methods. This approach can lead to greater accuracy, improved numerical stability and significant reductions in computational needs, while giving a new philosophical point of view to lattice Boltzmann calculations for a large range of applications.
MARKET APPLICATION OF THE PERCOLATION MODEL: RELATIVE PRICE DISTRIBUTION
Authors: CHAKRABORTI ANIRBAN
Published: July 2002

We study a variant of the Cont–Bouchaud model, which utilizes the percolation approach of multi-agent simulations of the stock market fluctuations. Here, instead of considering the relative price change as the difference of the total demand and total supply, we consider the relative price change to be proportional to the "relative" difference of demand and supply (the ratio of the difference in total demand and total supply to the sum of the total demand and total supply). We then study the probability distribution of the price changes.
DYNAMICS OF A DISLOCATION SET IN MOTION BY AN EXTERNAL STRESS
Authors: ROBLES M. , PERONDI L. , KASKI K.
Published: July 2002

The relation between dislocation velocity and resolved shear stress is studied computationally at the atomic scale using Molecular Dynamics simulations in a two-dimensional Lennard–Jones system. Mimicking a well known experimental technique, we apply a calibrated stress pulse to a system with a single dislocation and follow with a run-time graphics tool and displacement-field based tracking method, the dislocation motion caused by momentum transfer from an externally generated stress pulse. The empirically suggested power law relation between dislocation velocity and resolved shear stress seems to hold also in the atomic scale.
REMARKS ON WEYL INVARIANT p-BRANES AND Dp-BRANES
Authors: NIETO J. A.
Published: July 2002

A mechanism to find different Weyl invariant p-branes and Dp-branes actions is explained. Our procedure clarifies the Weyl invariance for such systems. Besides, by considering gravity–dilaton effective action in higher dimensions, we also derive a Weyl invariant action for p-branes. We argue that this derivation provides a geometrical scenario for the Weyl invariance of p-branes. Our considerations can be extended to the case of super-p-branes.
SOME IDENTITIES FOR THE QUANTUM MEASURE AND ITS GENERALIZATIONS
Authors: SALGADO ROBERTO B.
Published: July 2002

After a brief review of classical probability theory (measure theory), we present an observation (due to Sorkin) concerning an aspect of probability in quantum mechanics. Following Sorkin, we introduce a generalized measure theory based on a hierarchy of "sum-rules". The first sum-rule yields classical probability theory, and the second yields a generalized probability theory that includes quantum mechanics as a special case. We present some algebraic relations involving these sum-rules. This may be useful for the study of the higher-order sum-rules and possible generalizations of quantum mechanics. We conclude with some open questions and suggestions for further work.
FUZZY ACTIONS AND THEIR CONTINUUM LIMITS
Authors: BALACHANDRAN A. P. , MARTIN X. , O'CONNOR DENJOE
Published: July 2002

Previously matrix model actions for "fuzzy" fields have been proposed using noncommutative geometry. They retained "topological" properties extremely well, being capable of describing instantons, θ-states, the chiral anomaly, and even chiral fermions with no "doubling." Here, we demonstrate that the standard scalar and spinor actions on a d-dimensional manifold are recovered from such actions in the limit of large matrices if their normalizations are correctly scaled as the limit is taken.
THE PROBLEM OF NEUTRINO MASSES IN EXTENSIONS OF THE STANDARD MODEL
Authors: MASINA ISABELLA
Published: July 2002

We review the problem of neutrino masses and mixings in the context of grand unified theories. After a brief summary of the present experimental status of neutrino physics, we describe how the see-saw mechanism can automatically account for the large atmospheric mixing angle. We provide two specific examples where this possibility is realized by means of a flavor symmetry. We then review in some detail the various severe problems which plague minimal GUT models (like the doublet–triplet splitting and proton-decay) and which force us to investigate the possibility of constructing more elaborate but realistic models. We then show an example of a quasirealistic SUSY SU(5) model which, by exploiting the crucial presence of an Abelian flavor symmetry, does not require any fine-tuning and predicts a satisfactory phenomenology with respect to coupling unification, fermion masses and mixings and bounds from proton decay.
ELECTRON–ELECTRON ATTRACTIVE INTERACTION IN MAXWELL–CHERN–SIMONS QED3 AT ZERO TEMPERATURE
Authors: BELICH H. , CIMA O. M. DEL , FERREIRA M. M. , HELAYËL-NETO J. A.
Published: July 2002

One discusses the issue of low-energy electron–electron bound states in the Maxwell–Chern–Simons model coupled to QED 3 with spontaneous breaking of a local U(1)-symmetry. The scattering potential, in the nonrelativistic limit, stemming from the electron–electron Møller scattering, mediated by the Maxwell–Chern–Simons–Proca gauge field and the Higgs scalar, might be attractive by properly fine-tuning the physical parameters of the model.
THE JACOBI IDENTITY FOR DIRAC-LIKE BRACKETS
Authors: ABREU E. M. C. , DALMAZI D. , SILVA E. A.
Published: July 2002

For redundant second-class constraints the Dirac brackets cannot be defined and new brackets must be introduced. We prove here that the Jacobi identity for the new brackets must hold on the surface of the second-class constraints. In order to illustrate our proof we work out explicitly the cases of a fractional spin particle in 2+1 dimensions and the original Brink–Schwarz massless superparticle in D=10 dimensions in a Lorentz-covariant constraints separation.
CONSTRUCTION OF A NON-STANDARD QUANTUM FIELD THEORY USING GENERALIZED HEISENBERG ALGEBRA
Authors: REGO-MONTEIRO M. A. , CURADO E. M. F.
Published: July 2002

We herein construct a Heisenberg-like algebra for the one-dimensional quantum free Klein–Gordon equation defined on the interval of the real line of length L. Using the realization of the ladder operators of this Heisenberg-type algebra in terms of physical operators we build a (3+1)-dimensional free quantum field theory based on this algebra. We introduce fields written in terms of the ladder operators of this Heisenberg-type algebra and a free quantum Hamiltonian in terms of these fields. The mass spectrum of the physical excitations of this quantum field theory is given by [Formula: see text], where n=1,2,… and mq is the mass of a particle in a relativistic infinite square-well potential of width L.
DARBOUX TRANSFORMATIONS FOR QUASI-EXACTLY SOLVABLE HAMILTONIANS
Authors: DEBERGH N. , VAN DEN BOSSCHE B. , SAMSONOV BORIS F.
Published: July 2002

We construct new quasi-exactly solvable one-dimensional potentials through Darboux transformations. Three directions are investigated: Reducible and two types of irreducible second-order transformations. The irreducible transformations of the first type give singular intermediate potentials and the ones of the second type give complex-valued intermediate potentials while final potentials are meaningful in all cases. These developments are illustrated on the so-called radial sextic oscillator.
GRAVITATIONAL EFFECTS ON A RIGID CASIMIR CAVITY
Authors: CALLONI E. , DI FIORE L. , ESPOSITO G. , MILANO L. , ROSA L.
Published: July 2002

Vacuum fluctuations produce a force acting on a rigid Casimir cavity in a weak gravitational field. Such a force is here evaluated and is found to have opposite direction with respect to the gravitational acceleration; the order of magnitude for a multi-layer cavity configuration is analyzed and experimental detection is discussed, bearing in mind the current technological resources.
TOWARDS A THEORY OF QUANTUM BLACK HOLES
Authors: BEREZIN VICTOR
Published: July 2002

We describe some specific quantum black hole model. It is pointed out that the origin of a black hole entropy is the very process of quantum gravitational collapse. The quantum black hole mass spectrum is extracted from the mass spectrum of the gravitating source. The classical analog of quantum black hole is constructed.
THE CASE AGAINST CUPRATE-PLANE SUPERCONDUCTIVITY
Authors: DOW JOHN D. , BLACKSTEAD HOWARD A. , HARSHMAN DALE R.
Published: July 2002

Significant elements in the case for high-temperature superconductivity originating in the charge-reservoir layers are presented, including: (i) the successful predictions that PrBa 2 Cu 3 O 7, Gd 1.6 Ce 0.4 Sr 2 Cu 2 TiO 10, Pr 1.5 Ce 0.5 Sr 2 Cu 2 NbO 10, and Eu 1.5 Ce 0.5 Sr 2 Cu 2 TiO 10 all superconduct; (ii) the fact that muons stopped in the SrO layers of Sr 2 YRu 1-u Cu u O 6 detected flux expulsion, (iii) the observed superconductivity of PrBa 2 Cu 3 O 7 when its c-axis lattice constant is longer than 11.77 Å, and (iv) the failure of Gd 2-z Ce z CuO 4, Cm 2-z Th z CuO 4, and Ba 2 GdRu 1-u Cu u O 6 to superconduct.
ANALYTICAL OPERATOR SOLUTION OF MASTER EQUATIONS DESCRIBING PHASE-SENSITIVE PROCESSES
Authors: VIDIELLA-BARRANCO A. , ARÉVALO-AGUILAR LUIS M. , MOYA-CESSA HECTOR
Published: July 2002

We present a method of solving master equations which may describe, in their most general form, phase sensitive processes such as decay and amplification. We make use of the superoperator technique.
BOSONIZATION OF TWO-FERMION COMPOSITES WITH AN ARBITRARY INTERNAL MOTION: APPLICATION TO CORRELATED 1s EXCITON SYSTEMS
Authors: OGAWA TETSUO , OKUMURA SATORU
Published: July 2002

We propose an exact bosonization scheme for two two-fermion composites with identical internal structures, that is, a mapping of the two-exciton (four-fermion) subspace to a two-boson subspace. We obtain analytical, exact expressions of the boson-boson interactions and the boson-photon ones taking into full account that the commutation relation of the composite bosons deviates from the ideal-boson commutation due to internal motions of the composite. We can distinguish the "composite-particle effects' from the Coulomb interactions among the fermions in the interactions. With this method, origins of optical nonlinearity in a system with two 1s excitons are studied in terms of the mutual excitonic correlations and exciton-photon interactions.
EXCITON DYNAMICS AND LATTICE RELAXATION IN OLIGOSILANES
Authors: SUTO S. , SUZUKI H. , ONO R. , SHIMIZU M. , GOTO T. , WATANABE A. , MATSUDA M.
Published: July 2002

We have measured the absorption, photoluminescence, photoluminescence excitation spectra and the time response of luminescence intensity of the permethyl-hexasilane ( Si 6( CH 3)14) glass and permethyldodecasilane ( Si 12( CH 3)26) in 3-methylpentane solution. The Si 6( CH 3)14 oligomer shows a strong lattice relaxation in the photo-excited state and we have determined the parameters in configuration coordinate of Si 6( CH 3)14 oligomer. The luminescence is attributed to the self-trapped exciton state. The Si 12( CH 3)26 oligomer has several conformers at room temperature and only one conformer at 77 K. The Si 12( CH 3)26 shows a weak lattice relaxation at room temperature and form free excitons at 77 K.
STRUCTURAL CHARACTERIZATION OF CO-PRECIPITATED Cd1-xZnxS:Cu CRYSTALS
Authors: NAYEEM ABDUL , YADAIAH K. , VAJRALINGAM G. , MAHESH P. , NAGABHOOSHANAM M.
Published: July 2002

Structural characterization of Cd 1-x Zn x S : Cu solid solutions were carried out with 0≤x≤1. XRD studies have revealed that the compounds are polycrystalline in nature having either Hexagonal (wurtzite) or Cubic (Zincblende) structure irrespective of their composition. Also the compounds have shown the most preferred reflections due to the plane [101] of CdS(H) and [111] of ZnS(C) in addition to other prominent reflections. The various structural parameters such as lattice constant, average internal stress, micro strain, dislocaion density, grain size, and preferred orientation were correlated with the composition. The lattice constant decreased linearly with the increase in Zn concentration. The sign of internal stress indicated elongational and compressional natures corresponding to hexagonal and cubic phases of CdS respectively. The variation of micro strain appeared to be conjugate when compared to grain size variation, and the variation of dislocation density with the composition showed a higher dislocation density till x=0.4 and then decreased till x=0.8 and then increased. The degree of preferred orientation in mixed Cd 1-x Zn x S : Cu crystals as observed by the maximum peak intensity of CdS(H) and ZnS(C) reflection showed that the degree of preferred orientation remained almost constant till x=0.6 and then increased. The results were explained on the basis of different phases of the compound and the defects related to Zn atoms.
NBCO MICRO BRIDGE JUNCTIONS FABRICATED BY EXCIMER LASER PATTERNING
Authors: MORI ZON , BIN ZULKIFLI ZULHAIRI , DOI TOSHIYA , KOBA SHINICHIRO , HAKURAKU YOSHINORI
Published: July 2002

Micro bridge junctions of NdBa 2 Cu 3 O 7-δ (NBCO) thin films have been fabricated by using a pulsed KrF excimer laser. A 1 μm bridge with nonliner flux-flow like current-voltage characteristics was obtained by optimizing the laser patterning process. The superconducting current (Ic0) across the micro bridge at zero bias was 900 nA and suppressed by the radiation of microwave (10 GHz) at 77 K.
X-RAY SCATTERING STUDIES OF CHARGE STRIPES IN La2-xSrxNiO4 (x=0.20-0.33)
Authors: HATTON P. D. , GHAZI M. E. , WILKINS S. B. , SPENCER P. D. , MANNIX D. , D'ALMEIDA T. , PRABHAKARAN P. , BOOTHROYD A.
Published: July 2002

The La 2-x Sr x NiO 4 system is isostructural with the high T C superconducting cuprate La 2-x Sr x CuO 4 and is a prototypical system for the understanding of strongly correlated electron-phonon coupling, and the resultant effects on material properties. X-ray scattering studies have been performed on La5/3Sr1/3NiO4 that demonstrate the two-dimensional nature of these charge stripes. Such studies, demonstrate the very high correlation length of the stripes (~ 2000 Å) at low temperatures. We have undertaken a series of experiments measuring the wavevector and charge stripe correlation length on a variety of crystals with the compositions La 2-x Sr x NiO 4 (x=0.20, 0.25, 0.275, 0.30 and 0.33) using ~10 keV X-rays. The results demonstrate that for x=0.275, and above, the charge stripes are highly correlated in a well-ordered crystalline lattice. Measurements of the incommensurability, ε, as a function of temperature for the series revealed that it is commensurate and temperature independent for the x=0.33 sample. For other compositions it is incommensurate and also temperature dependent. However for the x=0.20 and 0.25 crystals a much reduced correlation length was observed suggestive of a charge stripe glass. However, such experiments are sensitive to such charge ordering only in the near (top few micron) surface region. High energy X-rays however can probe the charge stripe ordering within the bulk of the single crystal by utilising the dramatic increase in penetration depth. We have used 130 keV X-rays and demonstrate that in La5/3Sr1/3NiO4 the charge stripes are far less correlated in the bulk than in the near surface region. This reduced correlation length (~300 Å), consistent with neutron scattering measurements, is indicative of a charge stripe glass, reminiscent of that observed below x=0.25, in the near surface region.
THE ROTOR MODEL AND COMBINATORICS
Authors: BATCHELOR M. T. , de GIER J. , NIENHUIS B.
Published: July 2002

We examine the groundstate wavefunction of the rotor model for different boundary conditions. Three conjectures are made on the appearance of numbers enumerating alternating sign matrices. In addition to those occurring in the O (n = 1) model we find the number A V (2m + 1;3), which 3-enumerates vertically symmetric alternating sign matrices.
SKYRMIONS IN QUANTUM HALL FERROMAGNETS
Authors: FERTIG H. A.
Published: July 2002

Properties of skyrmions in quantum Hall systems are reviewed. It is shown that, using a Hartree-Fock technique, the size of skyrmions near filling factor ν=1 may be computed, yielding a result in close agreement with experiment. Finite densities of skyrmions are shown to lead to a crystal state with square symmetry due to the spin-dependent nature of their mutual interactions. The square lattice state has an unusual spin ordering which leads to a new gapless mode, analogous to spin waves in a two-dimensional XY antiferromagnet. The stability of the ordered spin state is assessed using a time-dependent Hartree-Fock approach, and a phase diagram is derived which shows the parameter range for which long-range spin ordering is destroyed by quantum fluctuations.
TIME-DEPENDENT CALCULATION FOR THE TRANSMISSION COEFFICIENT OF TWO-DIMENSIONAL QUANTUM WIRE STRUCTURES IN THE PRESENCE OF MAGNETIC FIELD
Authors: YIU CHINGHONG , WANG JIAN
Published: July 2002

We present a simple and efficient method for calculating transmission coefficient of two-dimensional quantum wire structures in the presence of magnetic field. The time evolution of a wave packet is first obtained by solving the time dependent Schrödinger equation. Transmission coefficient is then extracted from the wave function by an intergal transform. This method is easier to implement than traditional time-independent methods such as mode matching method and it can be used to study the time evolution of wave functions for systems with arbitrary shape.
Investigations on Zeolite-Based ER Fluids Supported by Experimental Design
Authors: Böse H.
Published: July 2002

The application of experimental design for determining the influence of various parameters on rheological properties of electrorheological (ER) fluids is demonstrated. Such statistical methods allow the quantitative determination of parameter effects even in the presence of considerable property fluctuations of the ER fluid as well as the calculation of interactions between the parameter effects. They thus provide a powerful optimization tool. Investigations have been performed on ER fluids containing particles of zeolite A in silicone oil. The influence of zeolite content, oil viscosity, particle size, cation composition and ER fluid temperature on the viscosity of ER fluids with and without electric field has been studied. In addition to the main effects of the parameters interactions between them also play a considerable role. The ratio of ER fluid viscosities with and without field, respectively, decreases with rising oil viscosity and increases with temperature. The larger value of the ratio for ER fluids with smaller particles is referred to different particle structures. Results of parameter effects on viscosity of the ER fluid in electric fields depend on the shear rate. Cation exchange of sodium to potassium has only a minor influence on ER activity. This result is compared with cation exchange with calcium, by which ER activity is drastically diminished. The loss of activity can be related to the occupation of different cation sites in zeolite A.
Electrorheological Effect in the Nematic and the Smectic A Phases of Low Molecular Weight Liquid Crystal
Authors: Negita Keishi
Published: July 2002

Electrorheological (ER) effects in the nematic (Ne), the smectic A (SmA) and the isotropic (Is) phases of octyloxy cyanobiphenyl (8OCB) are studied. When an electric field is applied, a large decrease of the viscosity is observed in the Sm A phase, while in the Ne phase an increase of the viscosity is recognized with an anomalous ER effect near the SmA-Ne phase transition. These behaviors are suggested to be general properties of the liquid crystal exhibiting the phase sequence of SmA-Ne-Is.
THE MODIFIED YOUNG'S EQUATION FOR THE CONTACT ANGLE OF A SMALL SESSILE DROP FROM AN INTERFACE DISPLACEMENT MODEL
Authors: DOBBS HARVEY
Published: July 2002

We derive the modified Young's equation for the contact angle of a fluid droplet on a rigid substrate using an interface displacement model and identify the line tension with the excess free energy per unit length calculated previously for a straight three-phase contact line.
MAGNETIC FIELD AND CURRENT DEPENDENCE OF AVERAGE ACTIVATION ENERGY IN YBCO HIGH-Tc GRANULAR SUPERCONDUCTORS
Authors: POPESCU V. A. , STEPANESCU A.
Published: July 2002

The temperature dependence of the electrical resistance noise in the presence of a magnetic field in polycrystalline YBCO samples was fitted with an average activation energy which decreases with magnetic field and with bias electrical current.
MICROSCOPIC THEORY OF THE QUANTUM HALL EFFECT
Authors: FUJITA SHIGEJI , TAMURA YOSHIYASU , SUZUKI AKIRA
Published: July 2002

The phonon exchange between the electron and the elementary magnetic flux (fluxon) induces an attractive transition in the degenerate Landau states. This attraction bounds an electron–fluxon complex. The center-of-mass of the complex moves as a boson with a linear dispersion relation (∊ = cp). The 2D system of free massless bosons undergoes a Bose–Einstein condensation at k B T c = 1.954ℏcn1/2, where n is the boson density. For GaAs/AlGaAs, T c ~ 1 K at the principal Landau-level occupation ratio ν = 1, where the electron number equals the fluxon number. Below T c , there is an energy gap, which stabilizes the Hall resistivity plateau. The plateau value (j/N)(h/e2) at the fractional occupation ratio ν = N/j, for odd j, indicates that the composite boson containing an electron and j fluxons carries the fractional charge (magnitude) e/j due to the magnetic confinement.
AN ORTHONORMAL–SHELL–FOURIER DESCRIPTOR FOR RAPID MATCHING OF PATTERNS IN IMAGE DATABASE
Authors: BUI T. D. , CHEN G. Y. , FENG L.
Published: July 2002

Invariance and low dimension of features are of crucial significance in pattern recognition. This paper proposes a novel orthonormal shell Fourier descriptor that satisfies all of these demands. This method first performs orthonormal shell decomposition on the line moment that is obtained from the 2-D pattern, then applies Fourier transform on each scale of the shell coefficients. Unlike other existing wavelet-based methods, our method allows applying common orthonormal wavelets, such as Daubechies, Symmlet and Coiflet, therefore it is simple to implement. We study the structure of the filter used and develop a fast algorithm to rapidly compute the spectra of orthonormal shell coefficients. The complexity of the proposed descriptor is O(n log n). We apply a coarse-to-fine strategy to search the image database; the matching is very quick because of the multiscale feature structure. The effectiveness of this new descriptor is demonstrated by a series of experiments as well as the comparison with other descriptors. The proposed descriptor is robust to white noise.
A MODEL OF STUDENT MIGRATION
Authors: SCHEURLE J. , SEYDEL R.
Published: July 2002

Recently, along with diminishing numbers of students, it has been observed that some graduate programs still have lots of students, whereas other fields of study suffer from a great loss of students. Apparently, students do not distribute evenly over the fields that a university offers. The relations among the number of students in different fields of concentration are not constant. In particular, the harder subjects appear to suffer more from a diminishing number of students than the fields with a reputation of being somewhat "softer."

The reasons for such trends must be expected to be related to the size of the market, and to psychological effects. Our study has been motivated by attempts to model economic mechanisms that are related to advertising [Feichtinger, 1992]. We have constructed a mathematical model that is able to explain trends such as reported above.
GLOBAL BIFURCATION AND LONG TIME BEHAVIOR OF THE VOLTERRA–LOTKA ECOLOGICAL MODEL
Authors: LI KAITAI , WANG LIZHOU
Published: July 2002

The structure of the positive steady-state solutions for the Volterra–Lotka ecological model of two cooperating species is investigated. Some new results of existence, nonexistence and uniqueness are presented. The existence of a global attractor which is contained in an order interval is shown and the bounds of various dimensions of the attractor are given.
BIFURCATION FROM AN EQUILIBRIUM OF THE STEADY STATE KURAMOTO–SIVASHINSKY EQUATION IN TWO SPATIAL DIMENSIONS
Authors: LI CHANGPIN , CHEN GUANRONG
Published: July 2002

The paper deals with the steady state bifurcations of the Kuramoto–Sivashinsky (K–S) equation in two spatial dimensions with zero mean and periodic boundary value conditions. Applying the perturbation method, asymptotic expressions of the steady state solution branches that have bifurcated from the equilibrium are obtained. Furthermore, stability of the bifurcated solution branches is discussed.
ANALYSIS AND STRUCTURE OF A NEW CHAOTIC SYSTEM
Authors: BANKS S. P.
Published: July 2002

A new chaotic system introduced in a recent paper [Banks & McCaffrey, 1998] is analyzed in detail. It is based on the theory of Lie algebras and is inspired by the well-known systems of Lorenz and Chua. The dynamics of an invariant semisimple part is first studied and then the full system is considered to be a perturbation of this invariant part.
BIFURCATION AND HUNTING PHENOMENA OF ROTATING SPEED IN A FLEXIBLE ROTOR SYSTEM CAUSED BY WHIRLING MOTION
Authors: INOUE KAORU , USHIO TOSHIMITSU , HIKIHARA TAKASHI
Published: July 2002

This paper presents the discussion of experimental results and numerical simulation of nonlinear phenomena in a flexible rotor system under mechanical resonance. The whirling motion of the first flexural mode of the rotor causes the hunting of its rotating speed. Hysteretic jump phenomena exist between the charge and the discharge of the rotation. It is shown that the quasi-periodicity of the whirling motion is closely related to the hunting of the rotating speed. When the rotor is coupled to a generator, a continuous change of output power cannot be achieved under mechanical resonance. These results show the necessity to stabilize the whirling motion and the hunting, for example in a flywheel energy storage system.
ON THE STRUCTURE OF THE ω-LIMIT SETS FOR CONTINUOUS MAPS OF THE INTERVAL
Authors: ALSEDÀ LLUÍS , CHAS MOIRA , SMÍTAL JAROSLAV
Published: July 2002

We introduce the notion of the center of a point for discrete dynamical systems and we study its properties for continuous interval maps. It is known that the Birkhoff center of any such map has depth at most 2. Contrary to this, we show that if a map has positive topological entropy then, for any countable ordinal α, there is a point xα∈I such that its center has depth at least α. This improves a result by [Sharkovskii, 1966].
CLASSICAL-LIKE RESONANCE INDUCED BY NOISE IN A FITZHUGH–NAGUMO NEURON MODEL
Authors: MASSANÉS S. RIPOLL , VICENTE C. J. PÉREZ
Published: July 2002

We have studied the stochastic behavior of Fitzhugh–Nagumo neuron-like model (FN) induced by subthreshold external stimuli. Our analysis based on three standard measures: the power spectrum, interspike interval distribution (ISI) and autocorrelation function shows that it is possible to define a characteristic time scale which can be identified in the response of the system for a wide range of frequencies. In contrast to previous studies we have focused our attention on high frequency signals which could be of interest for real systems such as nervous fibers in the auditory system. We report behaviors which resemble those of classical deterministic oscillators but never the stochastic resonance phenomenon typical of low frequency signals.
ANOMALOUS RELATIONSHIP BETWEEN SPATIAL AND TEMPORAL PATTERNS OF DYNAMICAL BEHAVIOR
Authors: RUBCHINSKY LEONID , SUSHCHIK MIKHAIL
Published: July 2002

The relationship between spatial and temporal patterns of dynamical behavior is studied in the nonequilibrium, extended homogeneous system. We present an example of "anomalous" relationship between spatial and temporal patterns of behavior and discuss possible mechanisms of this phenomenon. By anomalous relationship we mean a situation when only chaotic temporal dynamics is possible in the spatially homogeneous regime, while in the spatially inhomogeneous regime temporal dynamics can be regular at the same value of parameters. We studied this phenomenon in the array of identical coupled Chua's circuits.
BINARY ENCODING OF DISCERNIBILITY PATTERNS TO FIND MINIMAL COVERINGS
Authors: FÉLIX R. , USHIO T.
Published: July 2002

Rough set based methods have been applied successfully in many real world applications such as data mining, knowledge discovery, machine learning, and control. The rough set theory is used to deal with imperfect data and to eliminate dispensable, superfluous and redundant information as to obtain a simplified set of decision rules. Thus, several approaches and methods have been proposed to find minimal coverings, from which the decision rules can be induced. In many of these approaches, an improvement in the utilization of computational resources is encouraged.

In this paper, a binary encoding for attribute sets and a discernibility matrix is proposed. Such a binary representation of sets and sets operations in the implementation of algorithms provides a machine-oriented approach to the utilization of computational memory and allow parallel processing among groups of attributes. The discernibility matrix is reduced to its minimal size through the identification of main patterns in order to eliminate redundancies. Bit-wise operations replace sets operations, thus the search for minimal coverings is performed in an efficient way. Resulting improvement is shown in the analysis of medium-sized data sets using two generic methods to obtain minimal coverings.
ON THE GENERATING SET'S GROWTH FUNCTION FOR SUBGROUPS OF FREE GROUPS
Authors: OSIN D. V.
Published: July 2002

The asymptotic behavior of generating set's growth function is discussed. In terms of such functions we formulate one extension of Howson's theorem.
Abelian quantum invariants indeed classify linking pairings
Authors: Deloup Florian , Gille Catherine
Published: July 2002

We show that the topological invariants of a 3-manifold M, derived from a quadratic form q : G → ℚ/ℤ on a finite abelian group, introduced by the first author in [De1], classify linking pairings on M up to isomorphism.
THE GORDIAN COMPLEX OF KNOTS
Authors: HIRASAWA MIKAMI , UCHIDA YOSHIAKI
Published: July 2002

In this paper, we define the Gordian complex of knots, which is a simplicial complex whose vertices consist of all oriented knot types in the 3-sphere. We show that for any knot K, there exists an infinite family of distinct knots containing K such that any pair (Ki, Kj) of the member of the family, the Gordian distance dG(Ki, Kj) = 1.
SCALE FACTOR DUALITY IN STRING BIANCHI COSMOLOGIES
Authors: DI PIETRO ELISA , DEMARET JACQUES
Published: July 2002

We apply the scale factor duality transformations introduced in the context of the effective string theory to the anisotropic Bianchi-type models. We find dual models for all the Bianchi-types [except for types VIII and IX] and construct for each of them its explicit form starting from the exact original solution of the field equations. It is emphasized that the dual Bianchi class B models require the loss of the initial homogeneity symmetry of the dilatonic scalar field.