bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Geometrical Aspects of Classical Coulomb Scattering
Authors: Adolph John W. , Garcia A. Leon , Harter William G. , McLaughlin G. C. , Shiffman Richard R. , Surkus Victor G.
Published: August 2005

We derive a number of seemingly forgotten facts concerning Coulomb orbits that make the subject simpler than it is as found in the texts.
Comparison of Rayleigh-Schrödinger and Brillouin-Wigner Perturbation Theories
Authors: Silvert William
Published: August 2005

Parallel derivations of Rayleigh-Schrödinger and Brillouin-Wigner perturbation theory are presented, using the Dirac formalism. The relative advantages and disadvantages of the two are compared with the goal of smoothing the transition between elementary quantum mechanics and advanced approximation theory.
A Laboratory Investigation of Light-Emitting Diodes
Authors: Kwasnoski John B.
Published: August 2005

An undergraduate study of the operating parameters of inexpensive gallium-arsenide-phosphide light-emitting diodes is described. The experiment includes measurements of the dependences of threshold current, peak emission wavelength, energy gap, minority carrier lifetime, relative luminous output, and external efficiency on temperature and diode current. In 6–8 h of laboratory time a student is able to collect enough data to verify many of the basic concepts of solid state physics.
Z Dependence of External Bremsstrahlung: A Laboratory Experiment
Authors: Mudhole T. S. , Umakantha N.
Published: August 2005

A simple laboratory experiment to establish the Z dependence of external bremsstrahlung production in thin foils using a beta source and a NaI(Tl) scintillation detector, is described. Experimentally it is observed that the external bremsstrahlung intensity is proportional to Z1.97±0.06 in close agreement with the Z2 dependence expected by theory.
Derivation of a Statistical Mechanical Distribution Function by a Method of Inequalities
Authors: Clinton W. L. , Massa L. J.
Published: August 2005

The derivation of the most probable distribution in statistical mechanics is discussed from the view point of subtle inadequacies in the use of the calculus for continuous variables. It is demonstrated how a method of inequalities may be utilized to obtain the ordinary result while avoiding these difficulties.
William Harley Barber, Recipient of the 1947 Oersted Medal for Notable Contributions to the Teaching of Physics
Authors: Gibbs R. C.
Published: August 2005

The American Association of Physics Teachers has made to William Harley Barber, Emeritus Professor of Physics, Ripon College, the twelfth of its annual awards for notable contributions to the teaching of physics. The addresses of recommendation and presentation were made by Dr. R. C. Gibbs, Chairman of the Committee on Awards, Professor Paul Kirkpatrick, President of the Association, and Professor J. W. Buchta, Vice President of the Association, in a ceremony held in the Kent Theater, University of Chicago, on December 30, 1947, during the seventeenth annual meeting.
Quarter Century of Progress in the College Physics Laboratory
Authors: Overbeck C. J.
Published: August 2005

The task of revitalizing the laboratory of the introductory physics course becomes more imperative because of the impending growth of enrollment during the next decade. This problem can be solved by critical re-examination of existing methods of instruction, and by more concentrated attention to the training of graduate student teaching assistants.
Forgotten Magneto-Optical Effect
Authors: Lamarsh John R.
Published: August 2005

An interesting magneto-optical effect discovered at the close of the last century has gone unnoticed. The experimental evidence for the phenomenon is reviewed, and a qualitative explanation is presented. New experiments are required to obtain a complete understanding of the effect, and such an undertaking is strongly urged.
Term Papers in Senior Courses in Physics
Authors: Muldawer L.
Published: August 2005

Term papers on wisely chosen topics take the senior student out of the narrow textbook problem and give him an opportunity to use all his background training. Properly pursued, such assignments may stimulate and reinforce his interest in physics by demonstrating the vast extent of the unknown in physical science. Criteria for proper topics are listed and an actual assignment, “Neutrino Density in the Universe,” is discussed.
Hatchet or Hacksaw Blade Planimeter
Authors: Barnes George
Published: August 2005

The hatchet or hacksaw blade planimeter, consists only of a sharpened pointer, a rigid arm, and a knife edge. Its theory was first given by F. W. Hill in the Philosophical Magazine in 1894 and was later simplified by Satterly. Hill and Satterly showed that the numerical value of the area within a closed curve traversed in the proper manner by the pointer is equal to the product of the length of the planimeter arm and the net displacement suffered by the knife-edge as measured along an arc with the pointer at the center of curvature. The present paper gives a relatively simple derivation yielding essentially the same result but using an entirely different method of approach. It is also shown that the procedure for operating this planimeter can be simplified when determining areas within certain types of closed curves. The accuracy of the planimeter is discussed.
Procedures for Obtaining Surplus Government Property of Interest to Physics Teachers
Authors: Kelly W. C.
Published: August 2005

This report reviews procedures by which physics teachers can obtain surplus government property for use in lecture rooms and laboratories. Surplus property is a potentially valuable source of apparatus at low cost. Directors of state agencies for surplus property wish to be kept informed of the needs of physics teachers in their states. The report contains information about the procedures followed in the surplus property agencies of the United States and its territories and a typical list of surplus items of use to physics teachers.
Classification of Collisions; Elastic Collisions on a Macroscopic Scale
Authors: Barnes George , Patmore J. W. , Fountain S. J.
Published: August 2005

A number of well-known physics textbooks imply and some state definitely that perfectly elastic collisions never occur. It is pointed out that collisions between atoms and molecules are frequently elastic. A classification of collisions into three groups, depending upon the nature of the interaction forces, indicates that certain kinds of collisions between macroscopic objects may be perfectly elastic. Simple laboratory experiments illustrating two of these cases are described.
Rotation of Elongated Atomic Nuclei
Authors: Inglis David R.
Published: August 2005

Many nuclei exhibit rotational spectra much as molecules do. A rotational spectrum is recognized by the ratios of the successive spacings between the levels. The magnitude of this spacing is inversely proportional to the moment of inertia of the rotating object. For a molecule, the moment of inertia is quite simply determined by the fairly definite positions of the atomic nuclei where practically all the mass is concentrated. In nuclei there are no fixed masses and the very possibility of rotation depends on the nuclear shape being out-of-round. The moment of inertia is determined by the way the internal motions of the nucleons are influenced by the rotation. The hydrodynamic calculation based on treating the nuclear “fluid” like water with no friction gives too small a moment of inertia, which means calculated levels are more widely spaced than observed, by about a factor five. Among all the complicated aspects of nuclear structure, one aspect of the motion of nucleons that can be described in simple graphic terms is the influence of rotation. It is shown that this leads to large contributions to the moment of inertia by the few nucleons not in closed shells. Thus it is possible to understand in fairly simple terms how the moment of inertia can be greater than that calculated for a distorted droplet of “nuclear fluid,” though one manner of estimating the effect somewhat overshoots the experimental result.
Phase-Plane Graphics—A New Approach to Teaching Dynamics
Authors: Packer Leo S. , Eiss Norman S.
Published: August 2005

The theory of the phase plane is briefly presented in Part I, and three basic phase-plane trajectories are derived to acquaint the reader with the techniques of phase-plane plotting. Graphical analysis on the phase plane is proposed as a teaching aid for undergraduate courses in mechanics and vibration. In Part II the laws of elementary impact are reviewed and a concise phase-plane representation of impact is derived from the impact equations. The phase-plane method is used to study the motion resulting from the impact between two equal period pendulums of 3-to-1 mass ratio. Advantages of the phase-plane representation of impact are cited. In Part III the basic phase-plane trajectories derived in Part I are used as components of exact phase-plane representations of various discontinuous motions, such as dissipative impact of two mass particles and dissipative bouncing.
Untapped Source of Potential Scientists
Authors: Barnes George
Published: August 2005

At this time there is a critical shortage of scientific personnel in our country and a limited yearly crop of able young people on which to draw. In the past, fewer high school graduates with potential ability in science have chosen science as a profession than the number who have entered other fields. The present paper suggests that it is possible to utilize a part of this backlog of persons who could be trained as scientists in order to help relieve the scientific manpower shortage.
On Teaching Thermophysics
Authors: Seeger Raymond J.
Published: August 2005

The objectives of all thermodynamics courses, both graduate and undergraduate, need to be clarified. There is a need to treat introductory thermodynamics as physics in relation to other branches of physics, and not just to heat. It should be taught (1) from an operational point of view with respect to the world of physical phenomena, (2) with an emphasis upon the use of mathematics with respect to the world of physical concepts, and (3) with a concern for philosophical interpretations with respect to the world of physical theory.
Two Improved Methods for Determining Young's Modulus
Authors: Green Ralph E.
Published: August 2005

Two methods are described for determining Young's modulus. The apparatus used in both cases utilizes a compensating device which eliminates the error caused by slippage or movement of the anchored end of the wire. The simplicity of the design of the apparatus described is such that it may be constructed in any school shop at a fraction of the cost of commercially available apparatus.
International Cooperation in Physics
Authors: Osgood Thomas H.
Published: August 2005

A factual account is given of the origin and current status of the international organization of science, with special emphasis on physics in the U. S. A. The relationships between, and the roles played by the following bodies are stated: International Council of Scientific Unions (ICSU), United Nations Educational, Scientific and Cultural Organization (UNESCO), International Union of Pure and Applied Physics (IUPAP), Commissions of various types, National Academies, and National Committees.
Basic Experiment in Radiological Physics
Authors: Bartlett Albert A.
Published: August 2005

The relationship between source strengths in millicuries and gamma-ray exposures in roentgens is discussed in terms of the definitions of these and of other basic quantities of interest in radiological physics. An experiment is discussed which serves to introduce students to these concepts and in which they can be made aware of some of the hazards of radiation exposure.
Statics and Dynamics of a Helical Spring
Authors: Geballe Ronald
Published: August 2005

The theory of the extension and twisting of a helical spring has been given quite completely in a recent paper by Krebs and Weidlich. This theory is reviewed and its applicability as an experiment in advanced mechanics is described. From measurements of extension and twisting under static load, and also from simple observation of the coupled oscillations of these degrees of freedom it is possible to calculate Poisson's ratio and the shear modulus. The two independent procedures give consistent results. The experiment provides an excellent demonstration of the geometry and elastic deformation of a helix, its static equilibrium and its coupled oscillations.
Physics and the Premedical Student
Authors: Lagemann Robert
Published: August 2005

It is suggested that the traditional physics course, with the inclusion of topics from modern physics, is probably satisfactory for premedical students. However, when possible, a separate course should be available, as is done for engineering students. The content of such a course is discussed and the need for biophysics in medical school is explored.
Study of Apparatus for the Teaching of Physics. Report of the AAPT Committee on Apparatus for Educational Institutions
Authors: Kelly W. C.
Published: August 2005

This report contains a summary of the results obtained in a study of apparatus used in the teaching of physics at ninety-eight representative colleges and universities. The study yielded information about apparatus budgets, about the need for new items of apparatus, about the availability of prototype equipment, and about the problems involved in providing physics departments with apparatus from commercial sources.
Distribution of Scores in Examinations of Finite Length
Authors: Christy R. W.
Published: August 2005

A mathematical relation between the distribution of scores in an examination and the distribution of the students' knowledge, dependent on the difficulty of the examination questions, is obtained from some simple definitions and assumptions. A few examples are worked out to show the kinds of distortion which can be introduced by the choice of questions.
High School Physics Enrollments in the Chesapeake Area
Authors: Watson Bernard B.
Published: August 2005

Data on enrollments in high school physics during the 1955–1956 and 1956–1957 academic years were obtained from replies to questionnaires sent to all secondary schools in Delaware, Maryland, Virginia, and the District of Columbia. The survey indicated that physics is offered every year or in alternate years in approximately 50% of the secondary schools in this region. Between 75 and 80% of all secondary school students in the region are enrolled in schools which offer physics.
Magnifying Powers of Optical Instruments
Authors: Richards D. A.
Published: August 2005

A device consisting of two partially silvered mirrors is described. The device gives, by multiple reflections, a number of beams at a fixed angle apart. The application of the device in some optical measurements involving virtual images is discussed.
Presentation of J. W. Buchta as the Oersted Medalist for 1957
Authors: Michels Walter C.
Published: August 2005

Remarks made by the Chairman of the Committee on Awards in presenting J. W. Buchta for award of the 1957 Oersted Medal in recognition of his notable contributions to the teaching of physics.
Minimum Satellite Detection Equipment
Authors: Hilton Wallace A. , Crawford Roger C.
Published: August 2005

Minimum-cost equipment for detecting meridian passages of the Vanguard satellite is described.
Physics for Secondary Schools
Authors: Knauss Harold P.
Published: August 2005

A modernized course in physics for secondary schools being prepared by the Physical Science Study Committee is undergoing classroom development in eight schools during 1957–1958. This paper describes the collaboration of university physicists, secondary school teachers, and others in working out details of the course, and reports on developments and convictions growing out of classroom experience.
Versatile Magnetic Resonance Spectrometer
Authors: Cowen J. A. , Tanttila W. H.
Published: August 2005

A Pound-Knight-Watkins marginal oscillator has been modified by the addition of a vibrating capacitor in parallel with the tuning capacitor to produce a simple circuit which may be used to observe paramagnetic resonance at low fields, nuclear magnetic resonance, and nuclear quadrupole resonance. Suggestions are made as to the type of information which may be obtained in an undergraduate laboratory experiment. Research that can be done in smaller colleges with the instrument is discussed.
Graphic Aids for Teaching Coriolis Force
Authors: Walker Marshall J.
Published: August 2005

Graphical “paper experiments” are described which facilitate the study of Coriolis force and other forces which arise from the use of accelerated axes of reference. The development emphasizes the operational definition that an inertial frame of reference is a coordinate system in which a free body moves at constant velocity in a straight line. It is pointed out that the tangential component of Coriolis force is just that force needed to produce the torque which conserves angular momentum.
Physics for the First Grade
Authors: Seeger Raymond J.
Published: August 2005

This paper deals with a proposed program for the education of the citizen in science, which would start at the kindergarten level. It deals particularly with the writer's occasional experiences in teaching physics in grades one through five. In the first three grades, particular attention has been paid to the combination of physics with arithmetic. The paper concludes with several suggested principles for curricula construction: genetic selection, cultural integration, and wholesome meaning.
Quantum Mechanical Treatment of Systems with a Damping Force Proportional to the Velocity
Authors: Myers Vernon W.
Published: August 2005

It is possible to construct a Hamiltonian that leads to a velocity dependent damping force. The resulting Hamiltonian can also be applied as an operator in the time-dependent Schroedinger equation. The quantum mechanical treatment of systems with V(x) = 0 and V(x) = mgx is presented, and the results are compared with the classical formulation.
Energy Moment Method in Quantum Mechanics
Authors: Parker Paul M. , Brown L. Carlton
Published: August 2005

An approach different from the conventional ones to certain nondiagonal quantum mechanical eigenvalue problems is presented. The procedure described relates the physical parameters associated with the description of a quantum mechanical system to energy eigenvalues of the wave equation of the system in such a manner that for relatively simple systems the physical parameters can be evaluated from experimental data without effecting a detailed solution for the roots of the secular equation. Thus the energy moment method serves as an additional tool in data analysis. Results of the application of the energy moment method to two particular physical systems are included.
Reproductions of Prints, Drawings, and Paintings of Interest in the History of Physics. 56. Four Plates from A Compleat System of Opticks by Robert Smith
Authors: Watson E. C.
Published: August 2005

The first application of the method of constructing the image of a point object by means of an unrefracted central ray and a ray which is parallel to the axis and is refracted through the focus was made by Robert Smith. A section of his A Compleat System of Opticks is here reproduced.
Radiation Pressure Against Perfect Reflectors
Authors: Rhodes J. Elmer
Published: August 2005

The concept of radiation pressure exerted against a reflecting surface by electromagnetic waves and by sound waves in gases is a familiar one. The absence of radiation pressure for sound waves in a “linear medium” is becoming well known. The equations are somewhat different for the radiation pressure for these two cases where the radiation pressure is not zero. The mechanisms usually called on to explain them (nonlinearity of the equation of state of the gas, acceleration of charges in the reflector by the electromagnetic waves) are widely removed from each other. Consequently, it is not evident on the surface whether radiation pressure is a general property of waves or the capricious result of isolated physical phenomena associated with some waves.

A generalized concept of radiation pressure is here developed and then applied to several kinds of waves: sound waves in various media, waves on strings and springs, electromagnetic waves. Also, a simple demonstration of radiation pressure (for waves in a ripple tray) is described.
Kinesthetic Transverse Wave Demonstration
Authors: Pantidos Panagiotis , Patapis Stamatis
Published: August 2005

This is a variation on the String and Sticky Tape demonstration “The Wave Game,” suggested by Ron Edge.1 A group of students stand side by side, each one holding a card chest high with both hands. The teacher cues the first student to begin raising and lowering his card. When he starts lowering his card, the next student begins to raise his. As succeeding students move their cards up and down, a wave such as that shown in the figure is produced. To facilitate the process, students' motions were synchronized with the ticks of a metronome (without such synchronization it was nearly impossible to generate a satisfactory wave). Our waves typically had a frequency of about 1 Hz and a wavelength of around 3 m. We videotaped the activity so that the students could analyze the motions. The (17-year-old) students had not received any prior instruction regarding wave motion and did not know beforehand the nature of the exercise they were about to carry out. During the activity they were asked what a transverse wave is. Most of them quickly realized, without teacher input, that while the wave propagated horizontally, the only motion of the transmitting medium (them) was vertical. They located the equilibrium points of the oscillations, the crests and troughs of the waves, and identified the wavelength. The teacher defined for them the period of the oscillations of the motion of a card to be the total time for one cycle. The students measured this time and then several asserted that it was the same as the wave period. Knowing the length of the waves and the number of waves per second, the next step can easily be to find the wave speed.
Adding Resistances and Capacitances in Introductory Electricity
Authors: Efthimiou C. J. , Llewellyn R. A.
Published: August 2005

All introductory physics textbooks, with or without calculus, cover the addition of both resistances and capacitances in series and in parallel as discrete summations. However, none includes problems that involve continuous versions of resistors in parallel or capacitors in series. This paper introduces a method for solving the continuous problems that is logical, straightforward, and within the mathematical preparation of students at the introductory level.
Physics the Google Way
Authors: Ward David W.
Published: August 2005

Are we smarter now than Socrates was in his time? Society as a whole certainly enjoys a higher degree of education, but humans as a species probably don't get intrinsically smarter with time. Our knowledge base, however, continues to grow at an unprecedented rate, so how then do we keep up? The printing press was one of the earliest technological advances that expanded our memory and made possible our present intellectual capacity. We are now faced with a new technological advance of the same magnitude, the Internet, but how do we use it effectively? A new tool is available on Google™ (http://www.google.com)that allows a user not only to numerically evaluate equations but also to automatically perform unit analysis and conversion, with most of the fundamental physical constants built in. This paper describes some of its capabilities.
Using a Force Plate to Correct Student Misconceptions
Authors: Wyrembeck Edward P.
Published: August 2005

Each year during the unit on collisions I ask my physics students this conceptual question: If you want to close a door but you have too much inertia at the moment to get up and do it yourself, should you throw a ball that rebounds well, like a basketball, or a ball that rebounds poorly, like a ball of modeling dough, at the door?1 I also impose the condition that the two balls must have the same momenta when they strike the door. I give my students some time to discuss the problem in small groups and then make a prediction. I find that most students predict incorrectly that the dough ball will be more effective at closing the door because it is solid throughout and denser than the hollow, air-filled basketball. The students do not focus on the better-rebounding basketball and the greater change in velocity that it experiences than the modeling dough ball when they strike a solid object like a door. To correct this misconception I use a Vernier2 force plate to measure the impulse of a size 3 basketball and a ball of modeling dough of equal mass (0.3213 ± 0.0002 kg) dropped from the same height of 0.200 ± 0.002 m, to ensure equal velocities, onto the force plate. While I realize that a collision between a ball and a force plate is not exactly the same as a collision between a ball and a door, a more complex system, I believe it offers some very useful insights into the problem. I also include in this paper an extension on validating the impulse-momentum theorem.
THE KINETIC INTERPRETATION OF THE DGLAP EQUATION, ITS KRAMERS–MOYAL EXPANSION AND POSITIVITY OF HELICITY DISTRIBUTIONS
Authors: CAFARELLA ALESSANDRO , CORIANÓ CLAUDIO
Published: August 2005

According to a rederivation — due to Collins and Qiu — the DGLAP equation can be reinterpreted (in leading order) in a probabilistic way. This form of the equation has been used indirectly to prove the bound |Δ f(x, Q)| < f(x, Q) between polarized and unpolarized distributions, or positivity of the helicity distributions, for any Q. We reanalyze this issue by performing a detailed numerical study of the positivity bounds of the helicity distributions. To obtain the numerical solution we implement an x-space based algorithm for polarized and unpolarized distributions to next-to-leading order in αs, which we illustrate. We also elaborate on some of the formal properties of the Collins–Qiu form and comment on the underlying regularization, introduce a Kramers–Moyal expansion of the equation and briefly analyze its Fokker–Planck approximation. These follow quite naturally once the master version is given. We illustrate this expansion both for the valence quark distribution qV and for the transverse spin distribution h1.
PROPER-TIME FORMALISM IN A CONSTANT MAGNETIC FIELD AT FINITE TEMPERATURE AND CHEMICAL POTENTIAL
Authors: INAGAKI TOMOHIRO , KIMURA DAIJI , MURATA TSUKASA
Published: August 2005

We investigate scalar and spinor field theories in a constant magnetic field at finite temperature and chemical potential. In an external constant magnetic field the exact solution of the two-point Green functions are obtained by using the Fock–Schwinger proper-time formalism. We extend it to the thermal field theory and find the expressions of the Green functions exactly for the temperature, the chemical potential and the magnetic field. For practical calculations the contour of the proper-time integral is carefully selected. The physical contour is discussed in a constant magnetic field at finite temperature and chemical potential. As an example, behavior of the vacuum self-energy is numerically evaluated for the free scalar and spinor fields.
THE COLOR–FLAVOR TRANSFORMATION OF INDUCED QCD
Authors: SHNIR YASHA
Published: August 2005

The color–flavor transformation is applied to the U (Nc) lattice gauge model, in which the gauge theory is induced by a heavy chiral scalar field sitting on lattice sites. The flavor degrees of freedom can encompass several "generations" of the auxiliary field, and for each generation, remaining indices are associated with the elementary plaquettes touching the lattice site. The effective, color–flavor transformed theory is expressed in terms of gauge singlet matrix fields carried by lattice links. The effective action is analyzed for a hypercubic lattice in arbitrary dimension. The saddle points equations of the model in the large-Nc limit are discussed.
REMOTE INTERACTIONS ON DISTRIBUTED QUANTUM SYSTEMS: NON-LOCAL CONDITIONAL OPERATIONS AND PRODUCTION OF MULTIPARTICLE ENTANGLED STATE
Authors: CHEN LIBING , LU HONG , CHEN WEICHENG
Published: August 2005

We present a systematic simple method for constructing non-local quantum conditional rotation with single target and multiple targets operations. We firstly show how a non-local conditional rotation with single target operation can be implemented with unit fidelity and unit probability by using a maximally entangled pair as quantum channel. We also put forward a scheme for probabilistically implementing the operation with unit fidelity by employing a partially entangled pair as quantum channel. The required physical resources for implementation of the non-local operation in these two cases are discussed. We further consider non-local conditional rotation with multiple targets operations on N spatially distributed systems, and show that the number of possible distinct operations increases here exponentially, with the available number of entangled pairs that are initially distributed between systems. We also point out that the non-local conditional rotation operation can be used to generate multiparticle entanglement between particles belonging to distant users in a communication network and distributed quantum computer.
THERMAL INVESTIGATION OF SiO2-Bi2O3 HEAVY METAL GLASSES
Authors: SIMON V. , TODEA M. , SIMON S.
Published: August 2005

Structural changes induced by temperature rising in binary silico-bismuthate glasses are investigated by differential thermal analysis. Several exothermic peaks are recorded for all samples. Progressive substitution of Bi 2 O 3 by SiO 2 contributes to the structural relaxation of vitreous network and leads to diminishing of the melting temperature, even as SiO 2 content reaches 40 mol%. Glass stability is enhanced by addition of silicon dioxide.
SYNCHRONIZATION OF CROSS-WELL CHAOS IN COUPLED DUFFING OSCILLATORS
Authors: VINCENT U. E. , NJAH A. N. , AKINLADE O. , SOLARIN A. R. T.
Published: August 2005

Numerical simulations have been used to investigate the synchronization behavior of a unidirectionally coupled pair of double-well duffing oscillators (DDOs). The DDOs were simulated in their structurally stable chaotic zone and their state variables were found to completely synchronized. The essential feature of the transition to the synchronous state is shown to correspond to a boundary crisis in which the cross-well chaotic attractor is destroyed.
TUBE GEOMETRY EFFECTS ON QUANTUM TRANSPORT IN CARBON NANOTUBE ELECTRON RESONATORS
Authors: DING J. W. , LIU C. P.
Published: August 2005

The effect of tube geometry on quantum transport in carbon nanotube electron resonators is studied analytically by developing a transfer matrix method. The conductance of metallic chiral nanotubes not only shows oscillating variations as a function of gate voltage with rapid and slow periods, but also exhibits a conductance gap and some resonance conductance peaks in the gap region. These features depend on to a high degree on both tube diameter and chirality and thus provide an experimental means for structure appraisal of the nanotube devices.
CHAOTIC DYNAMICS AND SYNCHRONIZATION OF FRACTIONAL-ORDER CHUA'S CIRCUITS WITH A PIECEWISE-LINEAR NONLINEARITY
Authors: LU JUN GUO
Published: August 2005

In this paper, we numerically investigate the chaotic behaviors of the fractional-order Chua's circuit with a piecewise-linear nonlinearity. We find that chaos exists in the fractional-order Chua's circuit with order less than 3. The lowest order we find to have chaos is 2.7 in the homogeneous fractional-order Chua's circuit and 2.8 in the unhomogeneous fractional-order Chua's circuit. Our results are validated by the existence of a positive Lyapunov exponent. A chaos synchronization method is also presented for synchronizing the homogeneous fractional-order chaotic Chua's systems. The approach, based on stability theory of fractional-order linear systems, is simple and theoretically rigorous. It does not require the computation of the conditional Lyapunov exponents. Simulation results are used to visualize and illustrate the effectiveness of the proposed synchronization method.
OPTIMAL ADAPTIVE ALGORITHMS FOR FINDING THE NEAREST AND FARTHEST POINT ON A PARAMETRIC BLACK-BOX CURVE
Authors: BARAN ILYA , DEMAINE ERIK D.
Published: August 2005

We consider a general model for representing and manipulating parametric curves, in which a curve is specified by a black box mapping a parameter value between 0 and 1 to a point in Euclidean d-space. In this model, we consider the nearest-point-on-curve and farthest-point-on-curve problems: given a curve C and a point p, find a point on C nearest to p or farthest from p. In the general black-box model, no algorithm can solve these problems. Assuming a known bound on the speed of the curve (a Lipschitz condition), the answer can be estimated up to an additive error of ε using O(1/ε) samples, and this bound is tight in the worst case. However, many instances can be solved with substantially fewer samples, and we give algorithms that adapt to the inherent difficulty of the particular instance, up to a logarithmic factor. More precisely, if OPT (C,p,ε) is the minimum number of samples of C that every correct algorithm must perform to achieve tolerance ε, then our algorithm performs O( OPT (C,p,ε) log (ε-1/ OPT (C,p,ε))) samples. Furthermore, any algorithm requires Ω(k log (ε-1/k)) samples for some instance C′ with OPT (C′,p,ε) = k; except that, for the nearest-point-on-curve problem when the distance between C and p is less than ε, OPT is 1 but the upper and lower bounds on the number of samples are both Θ(1/ε). When bounds on relative error are desired, we give algorithms that perform O( OPT · log (2+(1+ε-1) · m-1/ OPT )) samples (where m is the exact minimum or maximum distance from p to C) and prove that Ω( OPT · log (1/ε)) samples are necessary on some problem instances.
SEPARATING POINT SETS IN POLYGONAL ENVIRONMENTS
Authors: DEMAINE ERIK D. , ERICKSON JEFF , HURTADO FERRAN , IACONO JOHN , LANGERMAN STEFAN , MEIJER HENK , OVERMARS MARK , WHITESIDES SUE
Published: August 2005

We consider the separability of two point sets inside a polygon by means of chords or geodesic lines. Specifically, given a set of red points and a set of blue points in the interior of a polygon, we provide necessary and sufficient conditions for the existence of a chord and for the existence of a geodesic path that separate the two sets; when they exist we also derive efficient algorithms for their obtention. We also study the separation of the two sets using the minimum number of pairwise non-crossing chords.
A HYBRID ALGORITHM FOR THE SOLUTION OF THE INVERSE PROBLEM IN FRACTAL INTERPOLATION
Authors: BRINKS RALPH
Published: August 2005

A new algorithm for the solution of the inverse problem concerning interpolatory iterated functions systems (IFS) is presented. It combines the advantages of the greedy least squares approach of Mazel and Hayes, and the self-affinity in the wavelet scalogram. Thus, the algorithm is computationally cheap and yields results with high accuracy.
STUDY OF FRACTALS DERIVED FROM IFS-FRACTALS BY METRIC PROCEDURES
Authors: DE MOL LIESBETH
Published: August 2005

It is a well-known fact that when visualizing an IFS-attractor through the chaos game, it is possible that the first points mapped will come closer to but stay visibly different from the attractor. This simple fact will be analyzed in more detail, through visualizations of different aspects of this convergence process. It will be shown that, in applying on every point in a 2D-plane the same sequence of mappings and coloring each point according to convergence distance, neighboring points form structures which resemble the attractor itself. Further, it is in this way possible to generate boundaries of the attractor that vary between small and coarse-grained. Using these results, it will be shown that it is possible to, starting with an IFS-attractor, construct fractals of which this IFS-attractor is a subset.
IRRATIONAL POINTS IN THE MANDELBROT SET
Authors: KUMAR P. B. VINOD , JOSEPH K. BABU
Published: August 2005

The continuity of the map φ : c → dim H(Jc) where Jc is the Julia set of the map fc(z) = z2 + c is discussed in this paper. Using the Hausdorff dimension, a partial order is defined on the Mandelbrot set M. Some properties of irrational points defined by this order are also studied.
An Investigation of Conditional Autocorrelation and Cross-Autocorrelation in Emerging Markets
Authors: Faff Robert W. , Hillier David , McKenzie Michael D.
Published: August 2005

We extend the feedback trader model by including a cross-market feedback trader. Our analysis of eighteen emerging markets suggests that there exists both positive and negative feedback traders in the markets and their activity is related to stock index return volatility. For cross-market feedback traders however, we show that, although cross-market autocorrelation among emerging markets is high and variable, the hypothesized negative relationship between cross-market autocorrelation and volatility is much weaker than its domestic counterpart.
The Effect of the Degree of Internationalization on Capital Structure for Listed Multinational Corporations in Taiwan during the Asian Financial Crisis
Authors: Kuo Hsien-Chang , Wang Lie-Huey
Published: August 2005

This paper examines the effect of the degree of internationalization on capital structure for multinational corporations (MNCs) in Taiwan during the Asian financial crisis in 1997 by using dummy variables in a multiple regression analysis. The results show that: (1) For the IT industry, the higher the internationalization is, the higher the leverage will be, but it is the reverse for the NIT industry. (2) There is an industry effect on tangible assets, sales size, return on total assets, current ratio, and the times of interest earned, while the collateral value of assets is more significant for the NIT industry than the IT industry when MNCs make capital structure decisions. (3) There is an internationalization effect on the collateral value of assets, profitability, and liability payment ability. For low-internationalized MNCs, firm size and profitability are the important capital structure determinants, but for high-internationalized MNCs, the collateral value of assets is a key element of leverage decisions. (4) The liquidity risk caused by the Asian financial crisis allows the collateral value of assets and liability payment ability be the important determinants when MNCs make capital structure decisions. Finally, the results also express that international outsourcing and international financing play a somewhat important role for the IT industry during successive industry development.
Returns and Investor Behavior in Taiwan: Does Overconfidence Explain this Relationship?
Authors: Lin Mei-Chen
Published: August 2005

This paper examines whether overconfidence can explain the relationship between performance and behavior of investors in Taiwan. Different from prior research that used a specific sample of individuals trading records, this work focuses on aggregate investor behavior to know whether overconfidence is a market-wide phenomenon. It is found that overconfident investors will trade more aggressively, and the excessive trading of overconfident investors results in the observed excessive market volatility. However, overconfidence effect exists only following bull markets. After a period of stock gains, overconfident traders tend to title their investment toward smaller-cap and growth stocks, consistent with the prediction of overconfident hypothesis that as investors become overconfident, they underestimate risk and thereby trade in riskier stocks.
Comparison of Linear and Nonlinear Models for Panel Data Forecasting: Debt Policy in Taiwan
Authors: Pao Hsiao-Tien , Chih Yao-Yu
Published: August 2005

This paper discusses the time-series cross-sectional (TSCS) regression and the prediction ability of the artificial neural network (ANN) by examining the panel data of debt ratios of the high tech industry in Taiwan. We build models with these two methods and eight determinants of debt ratio and compare the forecast performances of five models, two ANN nonlinear models and three traditional TSCS linear models. The results show that the sign of each determinant in linear models is the same as that in ANN models. In addition, the insignificant determinants in linear models have low relative sensitivities in ANN models. It seems that these two methods show consistent results for the capital structure determinants. Researchers and practitioners can employ either ANN or traditional statistical model to analyze the important determinants of the capital structure of their firms. The results of comparing the out-of-sample forecasting capabilities of the two methods indicate that: (1) the proposed ANN with 1-year lag model shows better forecast performance than the other three linear models in spite of high or low debt ratio; (2) the debt ratios of the present year are highly related to those of the previous year; and (3) the ANN model is capable of catching sophisticated nonlinear integration effects. Consequently, the ANN method is the more appropriate one between the two methods to be applied to build a forecasting model for the high tech industry in Taiwan.
On the Maintenance Costs and Exit Costs of the Peg in Hong Kong
Authors: Yip Paul S. L.
Published: August 2005

This paper attempts to pioneer a discussion on the exit and maintenance costs of the Currency Board System (CBS) in Hong Kong, and hopes to invite more debate on the issue. It suggests that the exit costs will depend on the timing of an exit, whether there are supplementary packages to mitigate the exit costs, and the choice of an alternative exchange rate system. In particular, it suggests that the monitoring band system favored by Williamson (2000) could help to reduce the exit costs. In addition, the paper points out that there are ways to reduce both the exit and maintenance costs. It then proposes a reform that could benefit the economy regardless of whether the policy maker eventually chooses to continue with or abandon the peg. The study is not only crucial to Hong Kong, but also important to other economies with a CBS as well as to the debate on the choice of exchange rate system.
ANALYSIS OF HEARTBEAT DATA WITH SPECTRAL AND FRACTAL TECHNIQUES
Authors: PÁZSIT IMRE
Published: August 2005

ECG signals from mice, and simultaneous ECG and blood pressure signals from rats are analyzed for a small number of cases. The data were obtained from four mice and two rats with one animal having health problems in each group, the rest being control cases. For the rats, the phase of the cross-spectra between the ECG and blood pressure, and for the mice the fractal properties of the interbeat series (RR-interval fluctuations) are found to be suitable as an indicator of health anomaly.
PERSISTENCE IN A SIMPLE MODEL FOR THE EARTH'S ATMOSPHERE TEMPERATURE FLUCTUATIONS
Authors: BERRONES ARTURO
Published: August 2005

The effect caused by the presence of a number of distinct time scales in a simple stochastic model for the Earth's atmosphere temperature fluctuations is studied. The model is described by a dissipative dynamics consisting of a set of coupled stochastic evolution equations. The system shows features that resemble recent observations. In contrast to other approaches, like autoregressive models, the fluctuations of the atmosphere's temperature depend on parameters with clear physical meaning. A reduced version of the model is constructed and its temporal autocovariance function is explicitly written.
REFINABLE SHIFT INVARIANT SPACES IN ℝd
Authors: CABRELLI CARLOS A. , HEINEKEN SIGRID B. , MOLTER URSULA M.
Published: August 2005

Let φ : ℝd → ℂ be a compactly supported function which satisfies a refinement equation of the form [Formula: see text] where Γ ⊂ ℝd is a lattice, Λ is a finite subset of Γ, and A is a dilation matrix. We prove, under the hypothesis of linear independence of the Γ-translates of φ, that there exists a correspondence between the vectors of the Jordan basis of a finite submatrix of L = [cAi-j]i,j∈Γ and a finite-dimensional subspace [Formula: see text] in the shift-invariant space generated by φ. We provide a basis of [Formula: see text] and show that its elements satisfy a property of homogeneity associated to the eigenvalues of L. If the function φ has accuracy κ, this basis can be chosen to contain a basis for all the multivariate polynomials of degree less than κ. These latter functions are associated to eigenvalues that are powers of the eigenvalues of A-1. Furthermore we show that the dimension of [Formula: see text] coincides with the local dimension of φ, and hence, every function in the shift-invariant space generated by φ can be written locally as a linear combination of translates of the homogeneous functions.
A DISCRETE QUEUE, FOURIER SAMPLING ON SZEGÖ CURVES AND SPITZER FORMULAS
Authors: JANSSEN A. J. E. M. , VAN LEEUWAARDEN J. S. H.
Published: August 2005

We consider a discrete-time multi-server queue for which the moments of the stationary queue length can be expressed in terms of series over the zeros in the closed unit disk of a queue-specific characteristic function. In many important cases these zeros can be considered to be located on a queue-specific curve, called generalized Szegö curve. By adopting a special parametrization of these Szegö curves, the relevant zeros occur as equidistant samples of a 2π-periodic function whose Fourier coefficients can be determined analytically. Thus the series occurring in the expressions for the moments can be written as Fourier aliasing series with terms given in analytic form. This gives rise to formulas for e.g. the mean and variance of the queue length that are reminiscent of Spitzer's identity for the moment generating function of the steady-state waiting time for a G/G/1 queue. Indeed, by considering the queue under investigation as a G/G/1 queue, the new formulas for the mean and variance also follow from Spitzer's identity. The approach in this paper can also be used to compute the probability distribution function of the queue length in analytic form.
Precise spectral asymptotics for nonautonomous logistic equations of population dynamics in a ball
Authors: Shibata Tetsutaro
Published: August 2005

We consider the semilinear elliptic eigenvalue problem −Δu + k(|x|)up = λu, u > 0 in BR, u = 0 on ∂BR, where p > 1 is a constant, BR : = {x ∈ RN : |x| < R}(N ≥ 1), and λ > 0 is a parameter. We investigate the global structure of the branch of (λ, uλ) of bifurcation diagram from a point of view of L2‐theory. To do this, we establish a precise asymptotic formula for λ = λ(α) as α → ∞, where .
An extension of the topological degree in Hilbert space
Authors: Berkovits J. , Fabry C.
Published: August 2005

We define classes of mappings of monotone type with respect to a given direct sum decomposition of the underlying Hilbert space H. The new classes are extensions of classes of mappings of monotone type familiar in the study of partial differential equations, for example, the class (S+) and the class of pseudomonotone mappings. We then construct an extension of the Leray‐Schauder degree for mappings involving the above classes. As shown by (semi‐abstract) examples, this extension of the degree should be useful in the study of semilinear equations, when the linear part has an infinite‐dimensional kernel.
Cauchy‐Dirichlet problem for the nonlinear degenerate parabolic equations
Authors: Kombe Ismail
Published: August 2005

We will investigate the nonexistence of positive solutions for the following nonlinear parabolic partial differential equation: ∂u/∂t = ℒu + V(w)up−1 in Ω × (0, T), 1 < p < 2, u(w, 0) = u0(w) ≥ 0 in Ω, u(w, t) = 0 on ∂Ω × (0, T) where ℒ is the subelliptic p‐Laplacian and .
Exact controllability for a semilinear wave equation with both interior and boundary controls
Authors: Ton Bui An
Published: August 2005

The exact controllability of a semilinear wave equation in a bounded open domain of Rn, with controls on a part of the boundary and in the interior, is shown. Feedback laws are established.