bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of smoking on asthmatic symptoms and allergen sensitisation in early childhood
Authors: Tariq S M , Hakim E A , Matthews S M , Arshad S H
Published: July 2002

Background

Apart from heredity, several early life environmental factors are implicated in the development of childhood asthma. Maternal smoking is believed to increase asthmatic symptoms but its influence on the development of allergen sensitisation is debatable.

Study design

A whole population birth cohort was reviewed at ages 1, 2, and 4 years. Of 1218 children seen at 4 years, 981 (80.5%) were skin prick tested with a battery of common food and aeroallergens. Smoking history was recorded at birth and updated at each follow up and its impact on the development of asthma and allergen sensitisation in the children was assessed.

Results

Two hundred and fifty mothers smoked during pregnancy (20.5%) and 307 (25.2%) after childbirth. Maternal smoking in pregnancy was associated with low birth weight (mean (SD): 3.3 (0.5) v 3.5 (0.5) kg; p<0.001). Smoking mothers were more often from lower social classes (31.8% v 16%, p<0.001) and they breast fed their babies for a shorter duration (8.5 (11.4)v 16.6 (15.2) weeks; p<0.001). The difference in breast feeding duration was partly due to a higher proportion of smoking mothers who never breast fed their babies. Although at age 2 years asthmatic symptoms were associated with exposure to maternal tobacco smoke (odds ratio 2.2, 95% confidence interval 1.5 to 3.4; p<0.001), this association was lost by 4 years. However, maternal smoking was a significant risk factor in a subgroup of children with asthmatic symptoms but negative skin prick test. Maternal smoking did not increase allergen sensitisation at age 4 years. No effect of paternal smoking on asthma was observed in the children.
Prevention of venous thromboembolism in Wales: results of a survey among general surgeons
Authors: Williams E V , Williams R S , Hughes J L , Williams K L , Foster M E , Lewis M H
Published: July 2002

Objective

To examine the current attitudes towards the prevention of venous thromboembolism among a cohort of surgeons.

Design

A postal survey, comprising a questionnaire covering various aspects of venous thromboembolism prophylaxis was sent to all (n=84) consultant general surgeons in Wales.

Results

Replies were received from 57 surgeons (68%), all of whom routinely used prophylaxis, the most frequent modalities used being heparin (100%) and graded compression stockings (79%). A combination of physical and pharmacological methods was used by over 89% of surgeons, with 60% starting prophylaxis more than two hours before operation. All surgeons continued prophylaxis after surgery, 53% until patients were mobile, 45% until they were discharged, and one surgeon continued prophylaxis for seven days after discharge. The thrombosis risk factors considered most important by surgeons when deciding about prophylaxis were (i) a previous history of venous thromboembolism, (ii) hypercoagulability, and (iii) malignancy.

Conclusions

This study confirms that Welsh surgeons conform to standard methods, but also highlights some uncertainties that are present in current surgical practice. Those who responded all routinely used prophylaxis, the timing of which was variable. The main risk factors identified when considering prophylaxis were previous history of deep vein thrombosis/pulmonary embolism, hypercoagulability, and the presence of malignancy. Suggestions for future practice are made.
The Florida “truth” anti-tobacco media evaluation: design, first year results, and implications for planning future state media evaluations
Authors: Sly David F , Heald Gary R , Ray Sarah
Published: July 2002

OBJECTIVES

To outline the design and present selected findings from the evaluation of a state counter-advertising, anti-tobacco media campaign. The appropriateness of the design for states developing media evaluations is discussed.

DESIGN

Four cross sectional, telephone surveys of the 12–17 year old population were used to track and monitor advertising and campaign awareness, confirmed awareness, and receptivity. The Florida baseline and one year surveys were used with two parallel national surveys in a quasi-experimental design to assess attitude and smoking related behaviour change attributable to the campaign.

MEASURES

Awareness was measured by self report, confirmed awareness by unaided description, and receptivity by self reports of how well advertisements were liked, talked to friends about, and made one think about whether or not to smoke. Eleven attitude and three smoking behaviour items for Florida (treatment) and a national (control) population were compared at baseline and after 12 months.

RESULTS

Significant increases in ad specific awareness, confirmed, receptivity, and campaign awareness, and confirmed awareness were reached by the sixth week. They continued to rise through the first year. No attitude and only minor behaviour differences were noted between the treatment and comparison populations at baseline. By the end of the first year, Florida youth had stronger anti-tobacco attitudes and better behaviour patterns than the comparison population.

CONCLUSIONS

The industry manipulation strategy used in the Florida campaign resulted in high rates of recall, significant changes in attitudes/beliefs, and reduced rates of smoking behaviour among youth.
Mapping epigenetic quantitative trait loci (QTL) altering a developmental trajectory
Authors: Wu Rongling , Ma Chang-Xing , Zhu Jun , Casella George
Published: July 2002

Genetic variation in a quantitative trait that changes with age is important to both evolutionary biologists and breeders. A traditional analysis of the dynamics of genetic variation is based on the genetic variancecovariance matrix among different ages estimated from a quantitative genetic model. Such an analysis, however, cannot reveal the mechanistic basis of the genetic variation for a growth trait during ontogeny. Age-specific genetic variance at time t conditional on the causal genetic effect at time t  1 implies the generation of episodes of new genetic variation arising during the interval t  1 to t. In the present paper, the conditional genetic variance estimated from Zhu's (1995) conditional model was partitioned into its underlying individual quantitative trait loci (QTL) using molecular markers in an F2progeny of poplars (Populus trichocarpa and Populus deltoides). These QTL, defined as epigenetic QTL, govern the alterations of growth trajectory in a population. Three epigenetic QTL were detected to contribute significantly to variation in growth trajectory during the period from the establishment year to the subsequent year in the field. It is suggested that the activation and expression of epigenetic QTL are influenced by the developmental status of trees and the environment in which they are grown.Key words: epigenetic modification, development, marker, poplar, QTL.
The effect of sharp-crested weir shape on air entrainment
Authors: Baylar Ahmet , Emiroglu M Emin
Published: July 2002

Aeration in the waters of rivers and streams is very important to the quality and existence of aquatic life. If the overfall jets downstream of weir structures plunges into a plunge pool, entrained air bubbles will contribute to aeration. This paper investigates sharp-crested weirs having different cross-sectional geometry and their effect on the air entrainment rate. It is demonstrated that the air entrainment rate of a 30° triangular sharp-crested weir is better than that of the other sharp-crested weirs tested. Moreover, variation in the number of V-notches over the width of the weir plate was studied for 30° triangular sharp-crested weirs. The 30° triangular sharp-crested weir with two V-notches was found to have higher values of air entrainment rate.Key words: aeration, air entrainment rate, plunging overfall jet, sharp-crested weir.
NOTE TO THE PAPER BY P. D. HISLOP AND S. NAKAMURA: STARK HAMILTONIAN WITH UNBOUNDED RANDOM POTENTIALS
Authors: STOLZ GÜNTER
Published: July 2002

A physically non-satisfactory assumption in a result of Hislop and Nakamura [3] on the absence of absolutely continuous spectrum for one-dimensional Schrödinger operators is shown to be removable.
BRAID GROUP STATISTICS IN TWO-DIMENSIONAL QUANTUM FIELD THEORY
Authors: ADLER C.
Published: July 2002

Within the framework of algebraic quantum field theory, we construct explicitly localized morphisms of a Haag-Kastler net in 1+1-dimensional Minkowski space showing abelian braid group statistics. Moreover, we investigate the scattering theory of the corresponding quantum fields.
On the Continuous Limit of Integrable Lattices II. Volterra Systems and SP(N) Theories
Authors: Morosi Carlo , Pizzocchero Livio
Published: July 2002

A connection is suggested between the zero-spacing limit of a generalized N-fields Volterra (VN) lattice and the KdV-type theory which is associated, in the Drinfeld–Sokolov classification, to the simple Lie algebra sp(N). As a preliminary step, the results of the previous paper [1] are suitably reformulated and identified as the realization for N=1 of the general scheme proposed here. Subsequently, the case N=2 is analyzed in full detail; the infinitely many commuting vector fields of the V2 system (with their Hamiltonian structure and Lax formulation) are shown to give in the continuous limit the homologous sp(2) KdV objects, through conveniently specified operations of field rescaling and recombination. Finally, the case of arbitrary N is attacked, showing how to obtain the sp(N) Lax operator from the continuous limit of the VN system.
DIFFEOMORPHISM GROUPS AND CURRENT ALGEBRAS: CONFIGURATION SPACE ANALYSIS IN QUANTUM THEORY
Authors: ALBEVERIO S. , KONDRATIEV YU. G. , RÖCKNER M.
Published: July 2002

The constuction of models of non-relativistic quantum fields via current algebra representations is presented using a natural differential geometry of the configuration space Γ of particles, the corresponding classical Dirichlet operator associated with a Poisson measure on Γ, being the free Hamiltonian. The case with interactions is also discussed together with its relation to the problem of unitary representations of the diffeomorphism group on ℝd.
CONNECTIVITY VIA NONGENERIC PENCILS
Authors: TIBĂR MIHAI
Published: July 2002

We use slicing by nongeneric pencils of hypersurfaces and prove a new theorem of Lefschetz type for singular non-compact spaces, at the homotopy level. As applications, we derive results on the topology of the fibres of polynomial functions or the topology of complements of hypersurfaces in [Formula: see text].
COMPLEX BEHAVIOR OF A PREDATOR-PREY MODEL WITH DISCRETE GENOTYPE
Authors: MARTINS S. G. F. , COSTA A. T. , FILHO JÚLIO S. S. BUENO , PENNA T. J. P.
Published: July 2002

Inspired by the work of Ray et al., we study a model of predator-prey dynamics that incorporates the effects of a discrete genotype. We thoroughly analyze the many features of the model, and show that the system seems to reach a critical state in the genotype space, with some evidence of self-organization. Our results present the effects of natural selection at work in genotype space. The presence of the discrete genotype seems to make the model more robust to small variations of the main parameters, when compared to the bare Lotka–Volterra dynamics.
COMPARATIVE PERFORMANCE STUDY OF PARALLEL PROGRAMMING MODELS IN A NEURAL NETWORK TRAINING CODE
Authors: VITELA JAVIER E. , HANEBUTTE ULF R. , GORDILLO JOSE L. , CORTINA LUCILA M.
Published: July 2002

This paper discusses the performance studies of a coarse grained parallel neural network training code for control of nonlinear dynamical systems, implemented in the shared memory and message passing parallel programming environments OpenMP and MPI, respectively. In addition, these codes are compared to an implementation utilizing SHMEM the native data passing SGI/Cray environment for parallel programming. The multiprocessor platform used in the study is a SGI/Cray Origin 2000 with up to 32 processors, which supports all these programming models efficiently. The dynamical system used in this study is a nonlinear 0D model of a thermonuclear fusion reactor with the EDA-ITER design parameters. The results show that OpenMP outperforms the other two environments when large number of processors are involved, while yielding a similar or a slightly poorer behavior for small number of processors. As expected the native SGI/Cray environment outperforms MPI for the entire range of processors used. Reasons for the observed performance are given. The parallel efficiency of the code is always greater than 60% regardless of the parallel environment for the range of processors used in this study.
Antidiabetic Effect of Nitobegiku in KK-Ay Diabetic Mice
Authors: Miura Toshihiro , Furuta Ko , Yasuda Akiyo , Iwamoto Naoki , Kato Motoshi , Ishihara Eriko , Ishida Torao , Tanigawa Keiichiro
Published: July 2002

In the past, Nitobegiku (the herb of Tithonia diversifolia (Hemsl) A. Gray) has been used as a medicinal plant for diabetes. Antidiabetic effect of the water extract of Nitobegiku (NG) was investigated in KK-Ay-mice — one of the animal models of type 2 diabetes. NG (1500 mg/kg body weight) reduced the blood glucose of KK-Ay mice from 509 ± 22 mg/dl to 340 ± 14 mg/dl (p < 0.001) and also lowered the plasma insulin (p < 0.05) 7 hours after single oral administration. No change in blood glucose of NG-treated normal mice (ddY) was seen. These results support that NG improve glucose metabolism by reducing insulin resistance. Therefore, NG may be useful for treatment of type 2 diabetes.
Effect of Acupuncture in the Treatment of Seasonal Allergic Rhinitis: A Randomized Controlled Clinical Trial
Authors: Xue Charlie Changli , English Robert , Zhang Jerry Jiansheng , Da Costa Cliff , Li Chun Guang
Published: July 2002

The clinical efficacy and safety of acupuncture in the treatment of Seasonal Allergic Rhinitis (SAR) was evaluated by employing a two-phase crossover single-blind clinical trial. Thirty subjects were randomly assigned to two groups with 17 and 13 subjects respectively and treated with real or sham acupuncture (three times per week) for four consecutive weeks and then a crossover for treatments for a further four weeks without a washout period. The administration of real acupuncture treatment was guided by a syndrome differentiation according to Chinese Medicine Theory. Subjects were assessed by various criteria before, during and after the treatments. Outcome measures included subjective symptom scores using a five-point scale (FPS), relief medication scores (RMS) and adverse effect records. Twenty-six (26) subjects completed the study. There was a significant improvement in FPS (nasal and non-nasal symptoms) between the two types of acupuncture treatments. No significant differences were shown in RMS between the real acupuncture treatment group and the sham acupuncture treatment group. No side effects were observed for both groups. The results indicate that acupuncture is an effective and safe alternative treatment for the management of SAR.
MODEL FOR SMALL NEUTRINO MASSES AT THE TeV SCALE
Authors: NASRI SALAH , MOUSSA SHERIF
Published: July 2002

We propose a model for neutrino mass generation in which no physics beyond a TeV is required. We extend the standard model by adding two charged singlet fields with lepton number two. Dirac neutrino masses mνD ≤ MeV are generated at the one-loop level. Small left-handed Majorana neutrino masses can be generated via the seesaw mechanism with right-handed neutrino masses MR of order TeV scale.
RENORMALIZATION GROUP AND DYNAMICS OF SUPERSYMMETRIC GAUGE THEORIES
Authors: KONISHI K.
Published: July 2002

We discuss questions related to renormalization group and to nonperturbative aspects of non-Abelian gauge theories with N=2 and/or N=1 supersymmetry. Results on perturbative and nonperturbative β functions of these theories are reviewed, and new mechanisms of confinement and dynamical symmetry breaking recently found in a class of SU(nc), USp(2nc) and SO(nc) theories are discussed.
THE DISPERSIVE APPROACH TO ELECTROWEAK PROCESSES IN THE BACKGROUND MAGNETIC FIELD
Authors: LIN GUEY-LIN
Published: July 2002

We propose a new method to compute amplitudes of electroweak processes in the strong background magnetic field, using γ → e+ e- as an example. We show that the moments of γ → e+e- width are proportional to the derivatives of photon polarization function at the zero energy. Hence, the pair-production width can be easily calculated from the latter by the inverse Mellin transform. The prospects of our approach are commented.
NON-NEWTONIAN MECHANICS
Authors: SALESI GIOVANNI
Published: July 2002

The classical motion of spinning particles can be described without recourse to particular models or special formalisms, and without employing Grassmann variables or Clifford algebras, but simply by generalizing the usual spinless theory. We only assume the invariance with respect to the Poincaré group; and only requiring the conservation of the linear and angular momenta, we derive the zitterbewegung, namely the decomposition of the four-velocity in the usual Newtonian constant term pμ/m and in a non-Newtonian time-oscillating spacelike term. Consequently, free classical particles do not obey, in general, the Principle of Inertia. Superluminal motions are also allowed, without violating special relativity, provided that the energy–momentum moves along the worldline of the center-of-mass. Moreover, a nonlinear, nonconstant relation holds between the time durations measured in different reference frames. Newtonian mechanics is reobtained as a particular case of the present theory: namely for spinless systems with no zitterbewegung. Then we analyze the strict analogy between the classical zitterbewegung equation and the quantum Gordon-decomposition of the Dirac current. It is possible a variational formulation of the theory, through a Lagrangian containing also derivatives of the four-velocity: we get an equation of the motion, actually a generalization of the Newton law a=F/m, where non-Newtonian zitterbewegung-terms appear. Requiring the rotational symmetry and the reparametrization invariance we derive the classical spin vector and the conserved scalar Hamiltonian, respectively. We derive also the classical Dirac spin (a×v)/4m and analyze the general solution of the Eulero–Lagrange equation oscillating with the Compton frequency ω=2m. The interesting case of spinning systems with zero intrinsic angular momentum is also studied.
LARGE N MATRIX MECHANICS ON THE LIGHT-CONE
Authors: HALPERN M. B. , THORN CHARLES B.
Published: July 2002

We report a simplification in the large N matrix mechanics of light-cone matrix field theories. The absence of pure creation or pure annihilation terms in the Hamiltonian formulation of these theories allows us to find their reduced large N Hamiltonians as explicit functions of the generators of the Cuntz algebra. This opens up a free-algebraic playground of new reduced models — all of which exhibit new hidden conserved quantities at large N and all of whose eigenvalue problems are surprisingly simple. The basic tool we develop for the study of these models is the infinite dimensional algebra of all normal-ordered products of Cuntz operators, and this algebra also leads us to a special number-conserving subset of these models, each of which exhibits an infinite number of new hidden conserved quantities at large N.
ET0L SYSTEMS FOR COMPOSITE DODECAGONAL QUASICRYSTAL PATTERNS
Authors: ESCUDERO JUAN GARCÍA
Published: July 2002

Two types of deterministic substitution tilings with 12-fold symmetry and a Pisot number as inflation factor are generated and described in terms of bracketed L-systems. Composition of the inflation rules allows to construct other types of dodecagonal patterns which can be described with the help of ET0L-systems and may be used in order to derive nondeterministic models of quasicrystal structures.
FINE STRUCTURE OF EXCITON IN A QUANTUM DOT: EFFECT OF ELECTRON-HOLE NONANALYTIC EXCHANGE INTERACTION
Authors: AJIKI H. , CHO K.
Published: July 2002

The nonanalytic part of the electron-hole exchange interaction, is studied theoretically in the strong confinement regime. The nonanalytic part raises some energy levels dramatically, and changes the oscillator strength of each level significantly.
THE ROLE OF STRUCTURAL DEFECTS AND INTERFACIAL INSTABILITIES IN THE GROWTH BEHAVIOUR OF PARACETAMOL
Authors: RISTIC R. I.
Published: July 2002

The role of structural defects and interfacial instabilities in the growth behaviour of small paracetamol crystals grown from pure aqueous solution and in the presence of p-acetoxy acetanalide (PAA) were investigated. The average growth rates obtained from growth rate distributions were used to predict morphological behaviour of an assembly of small crystals versus supersaturation. It was shown that columnar shape was formed in regions of low supersaturation while a plate like form prevailed at high supersaturations. An addition of PAA led to the development of columnar crystals with an aspect ratio which varied with impurity level. Using modern optical microscopy and X-ray topography it was shown that phenomena such as interfacial instabilities accompanied by formation of inclusions and dislocations in the {110} growth sectors are the key issues for defining particle morphology, size distribution and crystal purity.
INVESTIGATION ON OXIDE GROWTH MECHANISM OF PECVD SILICON CARBIDE FILMS
Authors: CHOI W. K. , LEOY C. C. , LEE L. P.
Published: July 2002

The effect of the Si-C , Si-CH3 , C-Hn , Si-H and Si dangling bonds on the oxidation process was investigated by monitoring the changes of these bands as a function of oxidation temperature or duration using the infrared spectroscopy technique. We concluded that the activation energy obtained from the linear regime of the oxide growth is related to the C-Hn bonds. We suggested that most of the C-Hn bonds were bonded to Si with n = 3 , that gave rise to voids to facilitate the oxidation of amorphous silicon carbide films.
PROPERTIES OF AMORPHOUS GAN GROWN ON SILICON
Authors: HASSAN Z. , IBRAHIM K. , KORDESCH M. E. , HALVERSON W. , COLTER P. C.
Published: July 2002

The success of crystalline GaN as an optical and electronic material has motivated an enormous effort to explore all aspects of the material. Little is known and reported about the amorphous phase of this semiconducting wide band gap material. In this paper, we report on the properties of amorphous GaN (a-GaN) grown on p-Si at 443K using electron cyclotron resonance (ECR) plasma-assisted metalorganic chemical vapor deposition (MOCVD). Silicon is a potential alternative to sapphire due to its high quality and readily available as a large diameter and low cost substrates. The film was analyzed by a variety of methods, including scanning electron microscopy (SEM), atomic force microscopy (AFM) and x-ray diffraction (XRD). The current-voltage characteristics of a-GaN/Si heterojunction were measured from room temperature to 363K. Rectification behavior and photovoltaic effect were observed for this anisotype heterojunction. The electrical characteristics of Ni Schottky barriers on a-GaN were also investigated.
DISORDER TO ORDER-LIKE TRANSITION IN La2CuO4.1 SUPERCONDUCTOR INDUCED BY HIGH INTENSITY X-RAYS
Authors: DI CASTRO D. , CAMPI G. , BIANCONI G.
Published: July 2002

We have studied effect of X-ray illumination on charge ordering superstructures in oxygen doped La 2 CuO 4+δ superconducting system. Formation of long range crystalline phase of polarons is favored in this system by mobile counter-ions (interstitial oxygen ions in the La 2 O 2 layer) in the temperature range 200–350 K. We find a clear signature of disorder to order like X-ray induced phase transition. This transition appears to show up beyond a threshold dose of about 1016 photons/cm2, the value which increases with decreasing temperature.
PROXIMITY EFFECT OF Pb ON CeCu6 AND La0.05Ce0.95Cu6
Authors: CHEN TAR-PIN , TIPPARACHI UDOM , YANG H. D. , WANG J. T. , CHEN BENJAMIN , CHEN JEAN C. J.
Published: July 2002

Heavy fermion materials have attracted a great deal of attention since 1979. These materials which contain a rare earth (U, or Ce, etc.) element exhibit unusual behavior at low temperature. The effective mass m* of the Landau quasiparticles is found to be orders of magnitude higher than that of a bare electron. Some of the Heavy Fermion materials become superconductors at low temperature. The pairing of electrons in these superconductors may not be of s symmetry like those in BCS type superconductors. The mismatch in electronic mass and the difference in pairing state between the light conventional superconducting electrons and the heavy fermion electrons have brought the coupling between light electrons (BCS type) and the heavy fermion electrons into question. Proximity effect of Pb on CeCu 6, Pb on La 0.05 Ce 0.95 Cu 6, and Pb on Cu was used to investigate the coupling between the conventional superconducting electrons of Pb and the heavy electrons in CeCu 6 or La 0.05 Ce 0.95 Cu 6. In this experiment proximity effect was found between Pb and CeCu 6, as well as between Pb and La 0.05 Ce 0.95 Cu 6. However, the proximity effect is small when compare with that between Pb and Cu. This indicates a much shorter extrapolation length in the heavy fermion materials than in Cu. Such a phenomenon can be explained by the mismatch in effective mass between the superconducting Pb electrons and the heavy fermion electrons.
Vortex dynamics in YNi2B2C single crystal by 11B NMR
Authors: Lee K. H. , Mean B. J. , Seo S. W. , Han K. S. , Kim D. H. , Lee Moohee , Lee S. I. , Cho B. K.
Published: July 2002

11 B pulsed nuclear magnetic resonance (NMR) measurements have been performed on a single crystal of YNi 2 B 2 C superconductor to investigate the vortex structure and dynamics. As temperature decreases, 11 B NMR spectrum, shift, linewidth, and [Formula: see text], exhibit distinct features, from which we are able to identify three vortex phases, namely, vortex liquid, vortex glass, and vortex lattice at 1.8T parallel to the c-axis. Also we has observed thermal hysteresis of saddle-point field, motional narrowing of linewidth and the double peak structures of [Formula: see text], all of which indicate unexpectedly significant thermal motion of vortices in this low Tc and nealy isotropic 3D superconductor.
CRITICAL FIELD AND MAGNETORESISTANCE OF SINGLE CRYSTAL TmNi2B2C
Authors: NAUGLE D. G. , RATHNAYAKA K. D. D. , CLARK K. , CANFIELD P. C.
Published: July 2002

In-plane resistance as a function of magnitude and direction of the magnetic field and the temperature has been measured for TmNi2B2C from above the superconducting transition temperature at 10.7 K to below the magnetic transition TN=1.5 K. The superconducting upper critical field HC2(T) exhibits a large anisotropy and structure in the vicinity of TN. The magnetoresistance above TC is large and changes sign as the direction of the magnetic field is rotated from in-plane to parallel with the c-axis.
QUANTUM MONTE CARLO SIMULATION STUDY OF ONE-DIMENSIONAL PERIODIC ANDERSON MODEL
Authors: SHARMA MEENAKSHI , KUMARI KAMLESH , SINGH ISHWAR
Published: July 2002

Many rare earth and actinide intermetallics, known as Heavy Fermion Systems, have recently been successfully described by the Periodic Anderson Model. We investigate, in this work, various electronic and magnetic properties of the one-dimensional Periodic Anderson model using path integral formulation along with the quantum Monte Carlo simulation technique. We have studied the singlet and triplet pairing correlation functions, nearest neighbor charge-density correlations, spin density correlations, local squared magnetic moment and probability of double occupancy of f-electrons, as a function of intra-atomic Coulomb interaction for various values of hybridization parameter and the temperatures.
HYDROGEN CO-DOPING IN III-V SEMICONDUCTORS: DOPANT PASSIVATION AND CARBON REACTIVATION KINETICS IN C-GaAs
Authors: MIMILA-ARROYO J. , BLAND S. W.
Published: July 2002

Hydrogen in semiconductors is an electrically active impurity whose interaction with lattice point defects and impurities, might produce a strong modification on their physical behavior, changing some material properties, influencing as well, device performance. In this work we will review the main effects of hydrogen co-doping on the properties crystalline semiconductors, discuss on the driving force on the process of hydrogen incorporation in carbon doped GaAs, growth in the presence of hydrogen. A detailed model on the carbon reactivation kinetics, carbon doping efficiency and carbon-hydrogen complexes behavior in MOCVD-GaAs epitaxial layers will be presented. Finally, we will discuss the probable relation between the beta evolution of the high frequency and high power n-GaInP/p-GaAs/n-GaAs hetero-junction bipolar transistor (HBT), and the hydrogen co-doping of the C:GaAs, constituting its base.
QUANTUM ELLIPTIC STATES OF ALKALINE ATOMS
Authors: HUANG YUNG-SHENG , LIAW SY-SANG
Published: July 2002

We generate the Hartree–Fock Rydberg wavefunctions of alkaline atoms using the/break B-spline finite basis method and then construct the coherent elliptic states from these spherical wavefunctions. We calculate the lifetimes of the elliptic states as a function of the eccentricities. The results are consistent with previous calculation using the quantum defect theory. The core effects play an important role for the elliptic states of high eccentricities.
APPLICATION OF ESR TO HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS III: CRYSTAL GROWTH RATES OF Y2BaCuO5 IN THE MELTS OF Y1+2nBa2+nCu3+nOx (n=0–0.4) SUBJECTED TO HIGH TEMPERATURES
Authors: YAMAMOTO K. , ARAI N. , HOTTA K. , SUGAWARA K. , HIROSE H.
Published: July 2002

Form the ESR measurements of Cu 2+ in Y 2 BaCuCuO 5, the growth rates of Y 2 BaCuCO 5 generated in the melts of Y 1+2n Ba 2+n Cu 3+n O x (n=0–0.4) have been quantitatively obtained as functions of heat-treatment temperature (1000–1400°C) and heat-treatment period (10–120 minutes). All the melted samples have been prepared by heating them in an atmospheric condition, and room-temperature quenching.
FACE-DEPENDENT WORK FUNCTION DERIVED FROM THE LOCAL POLARIZATION OF PLASMA AND THE IMAGE FORCE ACTION NEAR A METAL SURFACE
Authors: WOJCIECHOWSKI K. F. , KIEJNA A. , BOGDANÓW H.
Published: July 2002

The concepts of the spontaneous polarization of plasma near the metal surface and of the image force are used to propose a simple method of calculation of the face-dependent work function. The calculated work functions for low index planes of aluminium and sodium are in good agreement with experiment.
RECOGNITION OF 3D THIN-PLATE OBJECTS USING ORTHOGONAL AR MODEL
Authors: TSANG K. M.
Published: July 2002

A three-dimensional (3D) autoregressive model is introduced for modeling, invariant feature extraction and recognition of arbitrary 3D thin-plate objects. An orthogonal estimation algorithm is derived for the estimation of the coefficient matrices associated with the object boundary and error reduction ratio is used to determine the sufficient order of the model to describe the boundary. It is shown that the eigenvalues, traceand the determinant of the orthogonal coefficient matrices are invariant to rotation around the origin, to the choice of starting point in tracing the boundary and to scale and translation, and classification based on orthogonal parameters is shown to be less susceptible to incorrect model order specification.
COMPARATIVE ANALYSIS OF A HEURISTIC CONTROL OF CHAOS ALGORITHM IN SOME MODEL SYSTEMS
Authors: ANIL KUMAR C. V. , DASAN J. , RAMAMOHAN T. R.
Published: July 2002

In this work we propose a Heuristic algorithm based on parametric perturbation for control of chaos in systems of ODEs. This method appears to be the first to apply a perturbation to a parameter in a system of ODEs that is active over a finite length of time only. The method proposed is comparatively easy to implement and needs almost no information about the system beyond the existence of a system-wide controllable parameter. We demonstrate certain advantages of this technique over two well-known algorithms, namely, control by periodic parametric perturbation and control by addition of a second weak periodic force, such as the possibility of switching behavior, pretargetting the period of the controlled orbit, stabilizing high period orbits etc. We also demonstrate the applicability of the technique in certain numerical models of physical systems and also in a rather difficult model problem, viz. the control of the rheological parameters of periodically forced suspensions of slender rods in simple shear flow.
STRANGE NONCHAOTIC ATTRACTORS FROM PERIODICALLY EXCITED CHUA'S CIRCUIT
Authors: LIU ZHONG
Published: July 2002

In this paper, we discuss the existence of strange nonchaotic attractors for the Chua's circuit with periodical excitation. We have studied the Lyapunov exponents, Poincaré maps, singular continuous spectra of characterizing the attractors. The results show that the excited Chua's circuit does indeed have the strange nonchaotic behaviors.
GENERATION OF CHAOTIC BEATS
Authors: GRYGIEL K. , SZLACHETKA P.
Published: July 2002

We show that coupled Kerr and Duffing oscillators with small nonlinearities and strong external pumping can generate chaotic and hyperchaotic beats. The appearance of chaos within beats depends strongly on the type of interactions between the nonlinear oscillators. To indicate chaotic behavior of the system we make use of the Lyapunov exponents. The structure of chaotic beats can be qualitatively different — the envelope function can be smooth if the system is undamped or can give the impression of noise structure in the presence of strong damping and nonlinear interactions between the individual oscillators. The systems considered can be used, in practice, as generators of chaotic beats with chaotically modulated envelopes and frequencies.
ON–OFF INTERMITTENCY IN SMALL NEURAL NETWORKS WITH TIME-DEPENDENT SYNAPTIC NOISE
Authors: KRAWIECKI A. , KOSIŃSKI R. A.
Published: July 2002

Numerical evidence is presented for the occurence of on–off intermittency and attractor bubbling in the time series of synaptic potentials of analog neurons with time-dependent synaptic noise. The cases of continuous noise with uniform distribution of values and (physiologically motivated) quantal noise with binomial distribution are considered. The results were obtained for a single neuron with synaptic self-connection and a network of two neurons with various weights of synaptic connections. In the latter case coexistence of a neuron showing on–off intermittency with another one, showing attractor bubbling, is possible.
ON THE HYPERDECIDABILITY OF PSEUDOVARIETIES OF GROUPS
Authors: DELGADO MANUEL
Published: July 2002

Clarifying the relation between Ash's (algebraic-combinatorial) proof and Ribes and Zalesski[Formula: see text]'s (topological) proof of the Rhodes Type II conjecture is an intriguing and interesting question which arose when both proofs appeared in the beginning of the 1990s. Attempting to contribute to this clarification, we observe that two sets, each playing a crucial role in one of the proofs, are in fact equal. The equality of these sets allows us to give an alternative proof of part of the main theorem of Ash's paper where the hyperdecidability of the pseudovariety of all finite groups is established.
ELECTRONS AS QUASI-BOSONS IN MAGNETIC WHITE DWARFS
Authors: DRYZEK JERZY , KATO AKIRA , MUÑOZ GERARDO , SINGLETON DOUGLAS
Published: July 2002

A white dwarf star achieves its equilibrium from the balancing of the gravitational compression against the Fermi degeneracy pressure of the electron gas. In field theory there are examples (e.g. the monopole-charge system) where a strong magnetic field can transform a boson into a fermion or a fermion into a boson. In some condensed matter systems (e.g. fractional quantum Hall systems) a strong magnetic field can transform electrons into effective fermions, or effective anyons. Based on these examples we investigate the possibility that the strong magnetic fields of some white dwarfs may transform some fraction of the electrons into effective bosons. This could have consequences for the structure of highly magnetized white dwarfs. It would alter the mass-radius relationship, and in certain instances one could envision a scenario where a white dwarf below the Chandrasekhar limit could nevertheless collapse into a neutron star due to a weakening of the electron degeneracy pressure. In addition the transformation of electrons into effective bosons could result in the electrons Bose condensing, which could speed up the cooling rate of white dwarfs.
SIMPLEST COSMOLOGICAL MODEL WITH THE SCALAR FIELD II.
Authors: KAMENSHCHIK A. YU. , KHALATNIKOV I. M. , TOPORENSKY A. V.
Published: July 2002

Continuing the investigation of the simplest cosmological model with the massive real scalar noninteracting inflaton field minimally coupled to gravity, we study an influence of the cosmological constant on the behavior of trajectories in closed minisuperspace Friedmann–Robertson–Walker model. Combining numerical calculations with qualitative analysis both in configuration and phase space we present a convenient classification of trajectories.
CONVENIENT LINKS BETWEEN TIME VARYING INCIDENCE RATES AND CURRENT STATUS INFORMATION FOR EPIDEMIOLOGICAL MODELS WITH HETEROGENEITY
Authors: BRUNET ROBERT C.
Published: July 2002

Many compartment based epidemiological models are written as differential equation systems for various status subpopulation sizes with per person-time transfer rates between compartments. However, field data obtained by sampling at chosen times is usually provided in terms of status proportions from the total observable population (e.g., relative prevalence). Relationships between per person-time transfer rates (incidence, mortality, intervention rates) and proportions are not obvious when heterogeneity is at work because the various subpopulation sizes undergo different attrition rates and are not evolving in synchrony with the corresponding proportions. Rules are proposed to write sets of differential equations for compartment models, directly in terms of the proportions of the total observable at any time. To facilitate the writing of relationships between per person-time transfer rates and proportions, the systems are cast in network equivalent forms satisfying rules analogous to those of electrical networks (Kirchhoff's law for currents). The method is also extended to variability in the rates within a status subpopulation, considering either a fixed set of compartmental subdivisions or an inner continuum of differences in rates.
ANOMALOUS FEATURES ARISING FROM RANDOM MULTIFRACTALS
Authors: ZHOU WEI-XING , LIU HAI-FENG , YU ZUN-HONG
Published: July 2002

Under the formalism of annealed averaging of the partition function, two types of random multifractal measures with their probability of multipliers satisfying power law distribution and triangular distribution are investigated mathematically. In these two illustrations, branching emerges in the curve of generalized dimensions, and more abnormally, negative values of generalized dimensions arise. Therefore, we classify the random multifractal measures into three classes based on the properties of generalized dimensions. Other equivalent classifications are also presented by investigating the location of the zero-point of τ(q) or the relative position either between the f(α) curve and the diagonal f(α) = α or between the f(q) curve and the α(q) curve. We consequently propose phase diagrams to characterize the classification procedure and distinguish the scaling properties between different classes. The branching phenomenon emerging is due to the extreme value condition and the convergency of the generalized dimensions at point q = 1. We conjecture that the branching condition exists and that the classification is universal for any random multifractals. Moreover, the asymptotic behaviors of the scaling properties are studied. We apply the cascade processes studied in this paper to characterizing two stochastic processes, i.e. the energy dissipation field in fully developed turbulence and the droplet breakup in atomization. The agreement between the proposed model and experiments are remarkable.
COMPARISON OF SAMPLING TECHNIQUES FOR A PARAMETRIC YIELD OPTIMIZATION ALGORITHM
Authors: PALVANNAN K. , IBRAHIM YAACOB
Published: July 2002

Tolerances in component values will affect a product manufacturing yield. The yield can be maximized by selecting component nominal values judiciously. Several yield optimization routines have been developed. A simple algorithm known as the center of gravity (CoG) method makes use of a simple Monte Carlo sampling to estimate the yield and to generate a search direction for the optimal nominal values. This technique is known to be able to identify the region of high yield in a small number of iterations. The use of the importance sampling technique is investigated. The objective is to reduce the number of samples needed to reach the optimal region. A uniform distribution centered at the mean is studied as the importance sampling density. The results show that a savings of about 40% as compared to Monte Carlo sampling can be achieved using importance sampling when the starting yield is low. The importance sampling density also helped the search process to identify the high yield region quickly and the region identified is generally better than that of Monte Carlo sampling.
THE CORRELATION OF LOCAL STRUCTURE AND MAGNETISM IN THIN FERROMAGNETIC FILMS
Authors: BABERSCHKE K.
Published: July 2002

The most important quantity in magnetism is the magnetic anisotropy energy (MAE). Small MAE corresponds to soft magnets, good for transformers; large MAE corresponds to hard magnets, good for storage media. On a surface and nanometer scale LEED, MEED, X-ray and photoelectron diffraction, surface EXAFS and other techniques have recently made enormous progress in the determination of the real nearest neighbor distances and interlayer spacings within a tenth of an angstrom. These parameters serve as input for ab initio calculations of the MAE. Recent experiments on ultrathin Ni and Co films on Cu and W substrates will be discussed. We show that small displacements from ideal the fcc structure by only 2% may change the MAE by orders of magnitude! Thus for the first time the origin of the MAE in thin films can be understood on the basis of first-principles calculations taking into account the real local, i.e. noncubic perturbed, structure. This will result in an intimate contact between surface structure determination and magnetic properties.
A NEW CLASS OF COMMODITY HEDGING STRATEGIES: A PASSPORT OPTIONS APPROACH
Authors: HENDERSON VICKY , HOBSON DAVID , KENTWELL GLENN
Published: July 2002

We provide a new way of hedging a commodity exposure which eliminates downside risk without sacrificing upside potential. The tool used is a variant on the equity passport option and can be used with both futures and forwards contracts as the underlying hedge instrument. Results are given for popular commodity price models such as Gibson-Schwartz and Black with convenience yield. Two different scenarios are considered, one where the producer places his usual hedge and undertakes additional trading, and the other where the usual hedge is not held. In addition, a comparison result is derived showing that one scenario is always more expensive than the other. The cost of these methods are compared to buying a put option on the commodity.
ON THE EPR–CHAMELEON EXPERIMENT
Authors: ACCARDI LUIGI , IMAFUKU KENTARO , REGOLI MASSIMO
Published: July 2002

We construct a family of classical deterministic dynamical systems (triples formed by a state space, an initial distribution, a dynamics) parametrized by pairs of vectors (a,b) in the unit circle in ℝ2. The systems describe pairs of particles and the dynamics is strictly local, i.e. the dynamics [Formula: see text] of particle j=1,2 depends only on one of the two unit vectors, but not the other. To each particle one associates a family of ± 1-valued observables [Formula: see text](j = 1,2), also parametrized by vectors a in the unit circle in ℝ2. Moreover we assume that, if observable [Formula: see text] is measured on particle j=1,2, then the dynamics of this particle will be [Formula: see text] (chameleon effect).

Using these ingredients we prove that the dynamics and the initial distributions of the given systems can be chosen in such a way that, if the observable [Formula: see text] is measured on particle j=1,2, then the EPR correlations - cos (a1-a2) are reproduced.

This theoretical construction is then used to realize the following experiment: a central computer S (source) sends the same signal to two local computers A and B. After receiving the signal A (resp. B), chooses one vector a (resp. b) in the unit circle in ℝ2 and computes the value of the corresponding observable [Formula: see text] (resp. [Formula: see text]). These values are uniquely defined by the deterministic dynamics and the choices are independent of one another.

The local computers send back to the central one the results of the evaluation of these ±1-valued functions and the central computer evaluates the empirical correlations according to the usual statistical rules.

As a result the EPR correlations are reproduced with very good approximation and the Bell inequality is violated by a classical, macroscopic deterministic system performing purely local choices.

The program to run the experiment is available from http://volterra.mat.uniroma2.it
A FULLY DISTRIBUTED LOCATION MANAGEMENT SCHEME FOR LARGE PCS NETWORKS
Authors: RATNAM KARUNAHARAN , MATTA IBRAHIM , RANGARAJAN SAMPATH
Published: July 2002

This paper studies the effectiveness of a fully distributed location management scheme for PCS networks. Using analytical modeling and numerical simulation, we show that fully replicating lacation information is both appropriate and efficient for small PCS networks. Then, we extend the scheme in a hierarchical environment so as to reduce overhead and scale to large PCS networks. Through extensive numerical results, we show the superiority of our scheme compared to the current IS-41 standard.
ON CONTROL PERFORMANCE OF MULTI-D.O.F. ELASTIC-PLASTIC STRUCTURES UNDER EARTHQUAKES
Authors: BARATTA A. , CORBI O.
Published: July 2002

In this paper, a control algorithm developed for a single-d.o.f. elastic-plastic structural system subjected to a dynamic excitation is presented. The algorithm is based on evaluation of the bounds for plastic displacement occurring during the motion1–7and it can be regarded as an extension of the optimal norm control8,9which works for structures with no plastic excursion. Analytical foundations and numerical tests are carried out, providing some general conclusions on the advantage of adopting an ad hoc non-linear control model and on its applicability to elastic-plastic structures.
CALCULATION OF THE NATURAL FREQUENCY OF VIBRATION OF AN ORTHOPEDIC SCREW IN CANCELLOUS BONE OF VARIOUS ORIENTATIONS USING THE FINITE ELEMENT METHOD
Authors: WILLIAMS K. R. , YOUNG F. A.
Published: July 2002

The assessment of the stability of implants in cancellous bone remains a clinical problem. It has been shown that orthopaedic screw fixation depends on the microstructure and orientation of the trabeculae. In the current study we have investigated the possibility of using natural frequency analysis as a means of ranking screw fixation in cancellous bone. A dynamic modal analysis has been completed using the finite element method as a means of measuring implant frequency in a simple description of cancellous bone. A range of impulse excitation values have been examined which lead to implant resonance in different cancellous bone architectures. These values are reported in order that the eventual provision of a clinical diagnostic tool may correctly assess frequency values from the applied impulse.