bluuebunny/crossref_metadata_2025 huggingface dataset:
Orientation of Hexagonal Crystals
Authors: Winder Dale R.
Published: August 2005

Interplanar angles and stereographic projections are described for hexagonal structures. Graphs of the variations of some interplanar angles with c/a are given. The four systems of indexing hexagonal lattices are compared.
A Reformulation of Newtonian Dynamics
Authors: Hood C. Gregory
Published: August 2005

It is postulated that all dynamical laws must be formulated in terms of variables measured relative to interacting particles. This implies that the two-particle system is the fundamental interaction unit. When this postulate is applied to Newtonian mechanics, a radically new conceptual structure is revealed. The two major changes which result are the absence of the law of inertia and a broadening of the space and time invariance to include accelerated observers. Although energy and angular momentum remain conserved in this reformulation, the usual linear momentum theorem does not appear. It is further shown that the theory can be expressed in the Lagrangian and Hamiltonian formalisms in a straightforward manner. Finally, applications are made to several simple two-body and three-body systems which demonstrate that many-particle interactions can be formulated without reference to the dynamics of a single particle.
Teaching Perturbation Theory through Spin Systems
Authors: Radford L. E. , Willis J. S. , Forbes P. W.
Published: August 2005

The spin system provides a relatively simple and compact vehicle for discussion of non-degenerate perturbation theory. In fact in many such systems the terms required to write the electron's energy correct to second order may be read directly from the spin-energy matrix. In this work a hypothetical spin system and three different physical spin systems are treated in order to demonstrate the conciseness of the spin-energy-matrix approach to some perturbation problems. The combination of a perturbation problem which is calculable and which may be related to experimental data provides an approach to perturbation theory which is particularly satisfying to the student.
Mechanical Analogs to the Solution of the Time Independent Schrödinger Wave Equation
Authors: Smith J. Lynn
Published: August 2005

Mechanical systems are described which serve as analogs to phenomena connected with the time independent Schrödinger wave equation. The constraints necessary to effect a correspondence between the solutions of the time independent analog wave equation and those in the Schrödinger case are pointed out. The parameters in the mechanical systems which correspond to energy, mass, etc., in the Schrödinger case are arrived at, and the quantitative limits of these parameters for physical meaningfulness are discussed. The feasibility of selecting real materials for the construction of the analogs is established.
The Lost Arts of Experimental Investigation
Authors: Menzie John C.
Published: August 2005

The introductory physics laboratory is examined historially and philosophically. The rationale for the introductory laboratory is established with criteria for improvements.
Dynamic Polarization and Biology
Authors: Heims Steve P.
Published: August 2005

To gain insight into some biological processes in which a subsystem becomes ordered while gaining energy, an extremely simple physical process having these characteristics is analyzed. Each cycle of the process considered is formally the same as the description of the dynamic polarization of nuclei (Overhauser effect). In the biological process a crucial role is played by an “organizer,” a physical system which puts the subsystem of interest into improbable high-energy states. The role of the organizer, a close relative to the Maxwell demon, is played by the electron spin in the Overhauser effect. The role of feedback is investigated and relaxation times are evaluated in the Appendix.
Analog Computer Simulation in Plasma Physics
Authors: Shen K. , Alton E. D. , Hsuan H. C. S.
Published: August 2005

It is shown in this paper that analog computer simulation can be used as a convenient tool to demonstrate visually some fundamental properties of plasma physics. In this study, it is also observed that a new plasma drift mechanism exists in a nonstatic anisotropic plasma.
Supercooling of Water and Nucleation of Ice (Drop Freezer)
Authors: Vali Gabor
Published: August 2005

The principle and operation of a simple drop-freezing device is described. Such a unit can be effectively used in a teaching laboratory or as a demonstration apparatus to illustrate the general features of nucleation phenomena through the example of the freezing nucleation of water.
An Apparatus to Demonstrate Voltage and Current Waves in an LRC Circuit
Authors: Bartlett Albert A. , Clark Harry , Stoller Robert
Published: August 2005

An apparatus is described which makes it possible to demonstrate the current and voltage relationships in a series LRC circuit when the circuit is driven at 60 cycles per second and is adjusted to be near resonance. The apparatus projects the two waveforms simultaneously on a wall or projection screen with wave amplitudes of two to three feet.
The Classical Electrodynamics of Interacting Particles
Authors: Hamilton J. Dwayne
Published: August 2005

A new action integral describing the interactions among point particles in classical electrodynamics is presented. It is a simple generalization of a method introduced by Rohrlich. The theory is gauge invariant and free of mathematical difficulties. New expressions for the interaction energy-momentum and angular momentum tensors are also given.
Dynamical Applications of Bargmann Space III. Angular Momentum
Authors: Robinson J. M. , Trubatch S. L.
Published: August 2005

The coherent state representation is developed for angular momentum operators. As an example, the one-Boson Lee model is analyzed with its Fermi operators in Bargmann space. Finally, a synthesis is achieved by analyzing the three-level system with all operators in Bargmann space.
Mathieu's Functions and Electrons in a Periodic Lattice
Authors: Carver Thomas R.
Published: August 2005

The motion of an electron in a one-dimensional sinus-oidally varying potential is considered as an illustration of Mathieu's equation. The correspondence between the special periodic Mathieu functions and the electron wave functions at band center and band edge and the symmetries of these special functions are useful in displaying the atomic and lattice periodicities of the solid state problem. This treatment has some advantages over other “model” band calculations because one can see the continuous transition from deep lying bound atomiclike states to weakly bound conduction band states as the periodic perturbation is varied.
Are Resonance Residues Real?
Authors: Henyey Frank
Published: August 2005

It may appear that the real analyticity and unitarity conditions on a scattering amplitude should imply that the residues of resonances are real, just as the residues of bound states are real. We extract the residues in two simple models, a potential U(r) = Aδ(r−r0) and a K-matrix model. The amplitudes in these models are real analytic and unitary, yet the resonances have complex residues, as indeed they should. Based on the latter of these models we estimate the imaginary part of the ρ meson's residue as an interesting case in hadronic physics.
Bound-State Energies of a Particle in a Finite Square Well: An Improved Graphical Solution
Authors: Cantrell C. D.
Published: August 2005

The energy eigenvalues for a particle bound in a finite or semi-infinite square-well potential are shown to be determined by the points of intersection of two straight lines with sine or cosine curves. This construction, which is simple enough for students to remember, can also be used to determine the number of bound states for a given potential strength, and to obtain approximate values for the energies of low-lying states in a deep square well.
Isotope Structure in Tungsten—An Experiment
Authors: George S. , Fredrickson J. E. , Tucker A. W.
Published: August 2005

The arc spectrum of tungsten has been photographed using a 1-m Czerny-Turner plane grating spectrograph crossed with a Fabry-Perot interferometer. The light source used was a commercially available sealed-off hollow-cathode discharge. The isotope structure of the three lines 5015 Å, 5069 Å, and 5225 Å has been studied in detail with reference to the ratio of separations and relative intensities of the hyperfine-structure components. These are compared with published values in research journals. Judging from the enthusiasm shown by the students and their results, this experiment is suitable for an advanced optics and spectroscopy or quantum physics laboratory.
A Computer-Based Dialog for Deriving Energy Conservation for Motion in One Dimension
Authors: Bork Alfred M. , Sherman Noah
Published: August 2005

This paper describes a student-computer dialog for beginning or intermediate physics classes. The dialog enables the student to take some initiative in showing that energy conservation in one dimension is a consequence of the laws of motion.
Labs of Unlimited Scope
Authors: Reid W. M. , Arseneau D. F.
Published: August 2005

A report is given of one open-ended diversified laboratory pattern which capitalizes on three aspects of instruction. In particular, four experiments at the freshman and sophomore levels are described which incorporate prelab viewing of audiovisual aids, open-ended laboratory experiences, and usage, of the low-cost digital computer in both computer assisted instruction and computational modes.
The Relativistic Lagrangian
Authors: Brehme Robert W.
Published: August 2005

A few aspects of the formulation of the relativistic Lagrangian are discussed with the practical view of working problems in analytic relativistic dynamics. A brief discussion of radiation is included as an example of a nonconservative system in which the Lagrangian formulation is not possible.
The Joule-Thomson Coefficient—A Molecular Interpretation
Authors: McClure David W.
Published: August 2005

A discussion of the Joule-Thomson coefficient is presented in terms of its molecular interpretation. Certain aspects of the actual process are then explained in terms of these results. It is also shown how one may use the experimental data to study molecular interactions in gases.
Independent-Study Unit on Universal Gravitation
Authors: Poultney S. K.
Published: August 2005

After studying mechanics, the general science student is allowed to choose a topic in universal gravitation so that he can apply his knowledge in depth to that topic. He must also go to the library for specialized information, write a paper, and give a brief oral report of his investigations. Topics, suggested areas of investigation in each topic, and a small, complete set of references are given. The topics are also set in perspective and details of administration provided.
Mueller-Stokes Matrix Formulation of Fresnel's Equations
Authors: Collett Edward
Published: August 2005

The Mueller-Stokes matrices for Fresnel's reflection and transmission equations at a dielectric surface are derived and the basic properties of these matrices are discussed. A corresponding pair of matrices for Fresnel's reflection and transmission coefficients are also derived. The matrix forms are shown to simplify considerably at the Brewster angle and their special properties are demonstrated. In order to simplify matrix multiplications a diagonal matrix is constructed. The significance of the eigenvalues and the eigenvectors of the Mueller-Stokes polarizing matrix is noted. The relationship between the Mueller-Stokes polarizing matrix and the diagonal polarizing matrix is developed. Finally, Chandrasekhar's phase matrix is shown to be a special case of the diagonal polarizing matrix.
A Laboratory Experiment on the Statistical Theory of Nuclear Reactions
Authors: Loveland Walter
Published: August 2005

An undergraduate laboratory experiment on the statistical theory of nuclear reactions is described. The experiment involves measuring the relative cross sections for formation of a nucleus in its metastable excited state and its ground state by applying γ-ray spectroscopy to an irradiated sample. In 3–4 h of laboratory time and a modest amount of write-up time, students are given practice in γ-ray spectroscopy, growth and decay relationships, and the fundamentals of the statistical theory of nuclear reactions.
An Elementary Proof that the Undetermined Stress in an Incompressible Fluid is of the Form −pI
Authors: Langlois W. E.
Published: August 2005

In modern approaches to the theory of incompressible viscous fluid flow, it is assumed that the stress is kinematically determinate except for a contribution which does no work in divergence-free flow. It can then be established that the undetermined stress is isotropic, i.e., of the form −pI, but the usual proofs required advanced methods. The present paper supplies a short proof requiring only elementary matrix algebra.
The Problem with Average Acceleration Problems
Authors: Sciamanda Robert J.
Published: August 2005

Problems in introductory mechanics concerning the average acceleration of a particle undergoing general rectilinear motion are a source of much confusion to the student. They can be made the source of much light if a clear distinction is made between time averages and space averages. The term “average force” suffers from the same ambiguity and needs similar clarification. This is especially necessary if one wants to express the impulse-momentum and work-energy theorems in terms of an average force.
The Effects of Gravity Decrease on Planetary Orbits
Authors: Kelsey Edward J.
Published: August 2005

The effects of gravity decrease are discussed in connection with three models of planetary motion. These are (i) two bodies in a circular orbit, (ii) two bodies in an elliptical orbit, and (iii) many bodies in a solar system with interactions between the planets. A generalization is made which aids in the understanding of the results. The effect on Bode's law is discussed along with the possibilities of detecting gravity decrease in planetary motion.
Becker Averaging Technique for Obtaining Distribution Functions in Statistical Mechanics
Authors: Burns M. L. , Brown R. A.
Published: August 2005

We discuss a general, basic approach for obtaining the distribution function in introductory statistical mechanics by averaging over the microcanonical ensemble, which is accomplished without the use of Stirling's approximation or Lagrange multipliers.
Cosmological Constant and Fundamental Length
Authors: Anderson James L. , Finkelstein David
Published: August 2005

In usual formulations of general relativity, the cosmological constant λ appears as an inelegant ambiguity in the fundamental action principle. With a slight reformulation, λ appears as an unavoidable Lagrange multiplier, belonging to a constraint. The constraint expresses the existence of a fundamental element of space-time hypervolume at every point. The fundamental scale of length in atomic physics provides such a hypervolume element. In this sense, the presence in relativity of an undetermined cosmological length is a direct consequence of the existence of a fundamental atomic length.
Pilot Experience of Teaching a History of Physics Laboratory
Authors: Hoddeson Lillian Hartmann
Published: August 2005

This report outlines preliminary teaching experiences in the early working phases of a laboratory designed to permit students to re-perform crucial experiments in physics—using, insofar as possible, replicas of original apparatus and copies or translations of original texts. Teaching has so far been limited to nonphysics majors at Barnard and Columbia Colleges, but the laboratory is intended for physics majors as well. Early results are encouraging.
Misinterpretation of the Aharonov-Bohm Effect
Authors: Boyer Timothy H.
Published: August 2005

It is pointed out that accounts in the literature sometimes misinterpret the Aharonov-Bohm effect, involving the shift in interference pattern for electrons passing a long solenoid. The quantum description and experimental verification of the effect are reviewed, and it is emphasized that both theory and experiment indicate that there is no deflection of the average momentum of the electrons passing the solenoid. There is no average force on the electrons due to the solenoid. It is remarked that the Aharonov-Bohm effect involves the shift of double-slit interference fringes which is independent of the quantum unit of action ħ and yet allows a natural classical limit.
Bringing Modern Research Techniques to a Freshman Electricity and Magnetism Laboratory
Authors: Adelberger E. G. , Mischke R. E. , Strovink M.
Published: August 2005

The laboratory portion of a one-semester freshman electricity and magnetism course is described. As the principal feature of the laboratory, the students built multiwire proportional counters and used them to measure the value of e/m for 1-MeV electrons.
Team-Teaching Freshman Physics
Authors: Prescott J. R. , Anger C. D.
Published: August 2005

Team teaching, in which two or more instructors share responsibility for the same class section, is being increasingly adopted in elementary schools and is already familiar to physicists in the film and television presentations of Ivey and Hume. For several years we have been utilizing team teaching as a method of handling large university freshman classes. The system appears to have several advantages, provided that the two professors have a compatible outlook on physics: (1) Since the professors share administrative responsibility for such activities as tutorials and laboratories, these can be well integrated with the lectures; (2) the dialog between the two professors seems to create a sense of participation and rapport with the class; (3) any mistakes or obscurities in one professor's presentation are immediately cleared up (in a diplomatic way) by the other; (4) the change in pace provided by the two lecturers enlivens and lightens the course; (5) the interaction of the two professors tends to generate enthusiasm, fresh viewpoints, and greater care in lecturing, all of which is felt by the class. Student reaction has been highly favorable.
Analog Computer Solution of the Electrodiffusion Equation for a Simple Membrane
Authors: Onega Ronald J.
Published: August 2005

An analog solution was obtained for the Nernst-Planck and Poisson equations which describe the ion concentration across a simple membrane held at a potential difference V. These equations constitute a nonlinear system of differential equations. It was learned that even though electroneutrality was assumed as a boundary condition, it did not hold within the membrane itself. The electric field variation within the membrane was also determined.
Complex Potentials in Classical Mechanics and Geometrical Optics
Authors: Keskinen R.
Published: August 2005

It has been shown that the method of complex potentials widely used in hydrodynamics and electrostatics can be used in two-dimensional problems of particle mechanics and geometrical optics too.
On the Inversion of Noether's Theorem in Classical Dynamical Systems
Authors: Candotti E. , Palmieri C. , Vitale B.
Published: August 2005

A simple and conceptually clear proof of the inverse Noether's theorem is presented, both for classical point mechanics and for classical field theory. We start from an analysis of the time dependence (of the four divergence, respectively), of an arbitrary dynamical quantity, to relate it to the variation of the action integral induced by a suitably defined infinitesimal transformation. When the dynamical quantity is chosen to be a constant of motion (a divergenceless quantity, respectively), this infinitesimal transformation is shown to act as an invariance transformation on the dynamical system.
Quantum Theory In The Classical Limit
Authors: Cohn Jack
Published: August 2005

The problem of the reduction of quantum mechanics to classical mechanics is considered. It is demonstrated that the customary derivation of classical mechanics from the Schrödinger equation via the Hamilton-Jacobi action equation is incomplete. An improved derivation, involving the expectation value of the action, rather than the action itself, is given. Under this formulation the Hamilton-Jacobi description of classical mechanics is obtained from quantum mechanics, for suitable wave packets as h goes to zero.
Symmetries and Invariances of Canonical Theories
Authors: Anderson James L.
Published: August 2005

The concepts of symmetry and invariance within the framework of the canonical formalism as defined in a number of standard texts on classical mechanics are not, in general, equivalent to the definitions of these concepts as used in other areas of physics, e.g., quantum mechanics, relativity, elementary particle theory. In this paper we give definitions of these concepts in terms of infinitesimal canonical transformations that are in agreement with their generally accepted definitions and discuss the relation between them.
A Spark Light Source for Velocity of Light Experiments
Authors: Elmore W. C.
Published: August 2005

The construction and properties of a novel spark light source are described. The intense, brief light pulses make possible a simple velocity-of-light demonstration experiment of 1% accuracy, using an oscilloscope for measuring the separation in time of prompt and delayed light pulses. With suitable precautions, the source can also be used for a more accurate (approaching 0.01%) velocity determination based on the Alford-Gold method, in which a radio receiver is used to measure the nulls in the Fourier transform of the pairs of pulses.
The Relativity Twins in Free Fall
Authors: Holstein Barry R. , Swift Arthur R.
Published: August 2005

The ages of twins who travel along intersecting orbits in a central gravitational field are studied using general relativity. It is shown to order v2 / c2 that even though neither twin experiences acceleration, the aging is asymmetric.
The Reality of the Twin Paradox Effect
Authors: Greenberger Daniel M.
Published: August 2005

We discuss the assumption put forth recently by Sachs, that the proper time of a particle is a single-valued function of the space-time coordinates. We demonstrate that while it eliminates the age difference between the twins in the twin paradox, it also eliminates every other relativistic effect and implies Newtonian physics. We then discuss exactly how the nature of this assumption runs counter to the existence of a geometrical space-time manifold, and point out that the twin paradox is an integral part of relativistic physics, and that to deny its reality is to deny relativity.
The Exploratorium: A Playful Museum Combines Perception and Art in Science Education
Authors: Oppenheimer Frank
Published: August 2005

The role which museums can play in science education is discussed in general and with particular reference to the Exploratorium in San Francisco. We describe how art, an atmosphere of playfulness, and exhibits about the mechanisms of human sensory perception, have figured in the development of our museum. It is suggested that some of the objectives of interdisciplinary survey science courses can best be achieved in museum like settings where students and general public alike can gain firsthand experience with the fabric of natural phenomena.
Conformal Invariance of Maxwell's Equations
Authors: Rosen Gerald
Published: August 2005

A self-contained derivation of the conformal invariance of Maxwell's equations is presented.
War, Peace, Science, and Technology in the Atomic Age—A Physics Course for the General Student
Authors: Uritam R. A.
Published: August 2005

We describe a new physics course that explores the interaction among science, technology, war, and military affairs since the 1980s; topics covered include the Manhattan project, weapons technology, strategic thinking, disarmament and government support of research. The course is part of a new interdepartmental ldquo;Program for the Study of Peace and War.” We emphasize the valid role of general physics courses in studying areas where the results and methods of physics have an important impact on society.
Superradiance Revisited
Authors: Eberly Joseph H.
Published: August 2005

The basic features of coherent spontaneous emission, including its dependence on the square of the number of participating emitters, are reviewed. Analogies with magnetic resonance phenomena are exploited, and we explain the need to go beyond such analogies in order to treat optical emission. Some recent results in the theory of optical superradiance are discussed. The radiative decay process is treated as a quantum-classical interpolation problem, and explicit solutions are given. In addition to its time dependence, we give the angular distribution of radiated power and the expected intensity fluctuations, and we estimate the maximum number of emitters which can cooperate in a superradiant event. Dicke's “coherence brightening” criterion is discussed from the point of view of the present paper. A “failure” of the criterion is exhibited and explained. Two of the purely quantum aspects of superradiance are isolated and discussed briefly.
On the Divergence of the Rutherford Scattering Amplitude in Terms of Coulomb Phase Shifts
Authors: Marquez L.
Published: August 2005

The series of the Rutherford scattering amplitude in terms of Coulomb phase shifts is divergent. This fact was known some time ago. Nevertheless, a misunderstanding has appeared and exists on this question. We try to explain how and why there is such misunderstanding. This divergent series has the property that, if one stops the expansion when the last phase shift is an integer multiple of π, the sum approaches the correct value. We draw some conclusions arising from this situation.
Ambiguities in Stationary Perturbation Theory
Authors: Fujiwara Izuru , Sakurayama Yoshio
Published: August 2005

Ambiguities appearing in the expansion of an eigenvector of the perturbed Hamiltonian in terms of those of the unperturbed Hamiltonian are studied from a new point of view. Ordinary treatments of the stationary perturbation theory are shown to lead to the same conclusion as Epstein's, that the ambiguities are equivalent to those of phase factors which can be fixed arbitrarily in the eigenvectors of the perturbed Hamiltonian.
A Novel Approach to Introductory Mechanics
Authors: Adler Carl G.
Published: August 2005

An approach to introductory mechanics is developed which allows the beginning student who is unfamiliar with ordinary differential equations to solve easily many of the problems of interest to him. This approach uses the Taylor series as a method of projecting into the future based on a knowledge of the accelerations of a system of particles and their initial conditions.
Thermoluminescent Dosimetry in a “Medical Physics” Course Laboratory
Authors: Onn David G. , Gagne Robert M. , Hofmann Michael P.
Published: August 2005

In developing the laboratory section of a new course in “Medical Physics” we have made extensive use of thermoluminescent dosimetry (TLD). This technique makes possible quantitative experiments in radiation physics that cannot easily be performed with other detectors. The experiments described range from an inverse-square-law demonstration to detailed radiation beam profile studies the results of which can be used by students in patient treatment planning in a simulated clinical situation. An outstanding feature of TLD techniques involves the “point detector” nature of the TLD crystals, allowing high-resolution study of spatial-dose variations.
Demonstration of Low-Frequency Electrical Oscillations
Authors: Sharma Bal Krishna , Saraf Babulal
Published: August 2005

An underdamped LCR circuit has been constructed which has an oscillatory period in the region of 0.5 to 5 sec. The current and emf in the circuit are measured by means of a galvanometer. The time behavior of the circuit is studied by means of a light beam chopper and sampling technique. A simple rotating magnet mechanical-electrical power pump is used to study the frequency response of the circuit for different time periods and damping conditions. A low-frequency sinusoidal electrical oscillator is used to study the response curve of the galvanometer and the behavior of the LCR circuit with series coupling. The potential of the galvanometer for quantitative measurements of the time varying systems (T>0.5 sec) has been established. The experiment is instructive and can be used for introductory as well as advanced courses.
A Self-Paced, Independent Study, Introductory Physics Sequence—Description and Evaluation
Authors: Anderson Owen T. , Artman Robert A.
Published: August 2005

The instructional methods and media used to implement a self-paced, independent study, three-semester introductory physics sequence are described. The effectiveness of the first of these three courses was evaluated using experimental and control groups. The results of this experiment, along with the results of less quantitative evaluations, are given and discussed.
Einstein's Interpretation of Quantum Mechanics
Authors: Ballentine L. E.
Published: August 2005

Einstein's arguments concerning the interpretation of quantum mechanics are reviewed and contrasted with certain misconceptions regarding his attitude toward the theory. He considered Born's statistical interpretation to be the only satisfactory one, and he was not a supporter of hidden-variable theories such as that of Bohm. His criticism of the interpretation accepted, at least tacitly, by many physicists was that the quantum state function does not provide a description of an individual system but rather of an ensemble of similar systems. This criticism was not based merely upon his famous remark that God does not play dice, but upon some definite physical arguments which did not assume determinism.
Quantum Treatment of Thomson Scattering in a Magnetic Field
Authors: Gaisser T. K.
Published: August 2005

Quantum theory of radiation is used to calculate Thomson scattering in the presence of a magnetic field. The analysis is relevant to recent experiments on the scattering of laser light from a magnetized plasma, and it provides an entertaining exercise in the use of raising and lowering operator techniques.
Geometric Approach to Relativistic Dynamics
Authors: Rigden John S.
Published: August 2005

Several space-time diagrammatic approaches have been devised for the analysis of questions arising in relativistic kinematics. This general approach is extended to dynamics by the development of the geometric equivalent of the Lorentz energy-momentum transformation equations. The resulting diagrams are called ergmentum diagrams. Following the covariant approach of Brehme (as opposed to the con-travariant approach of Loedel), the ergmentum diagram is applied to several classes of problems.
Two Undergraduate Microwave Experiments Giving Unexpected Data
Authors: Reichert Jonathan F.
Published: August 2005

Two microwave experiments are described in which the data are not anticipated by the student performing the experiments. These experiments give the student the opportunity to use his own skills and imagination to explain the results he has obtained. Very little additional equipment, aside from the standard microwave apparatus, is required.
Wave Vector Technique for the Analysis of Direct Interactions
Authors: Owen George E. , Madansky L.
Published: August 2005

A simple technique is developed by means of which one can compute the various components of the differential cross section for direct interactions. The method for the most part relies upon the identification of the relative motion wave vectors in a wave vector diagram. By assigning a Fourier transform to each relative motion wave vector, the basic functions representing the differential cross section for stripping reactions, pickup reactions, etc., are obtained.
Approximate Nature of Physical Symmetries
Authors: Morrison P.
Published: August 2005

Since Leibniz it has become clearer and clearer that a priori judgment is inadequate to establish the presence of exact symmetries in the physical laws, and the exact conservation laws which flow from them. The latest example has been the Yang-Lee demonstration of the failure of mirror invariance in the weak interactions. It is possible to conjecture that even the kinematical symmetries under continuous transformations which give energy-momentum conservation may be inexact; their failure may be expressed, for example, in the spontaneous creation of nucleons postulated by Bondi and Gold. Still further, one may at least raise the question of the exactness of general relativity, or rather of the principle of equivalence between acceleration and a uniform gravitational field. If this equivalence is regarded as an approximate consequence of the predominance of matter over antimatter in our environment, it is possible to frame a consistent scheme which predicts large-scale symmetry between matter and antimatter, but at the expense of introducing gravitational repulsion. Conceptual experiments are constructed to show the consistency of this picture at least in the Newtonian limit; certain specified conditions on the gravitational behavior of various types of inertial mass must be satisfied.
Sophomore Experiment in Thermoelectricity
Authors: Noon J. H. , O'Brien B. J.
Published: August 2005

A laboratory experiment is described in which the temperature change caused at the junction of two metals is studied for both directions of current through the junction. It extends the usual thermocouple-calibration experiment and encourages consideration of thermoelectric cooling as a possible source of refrigeration.
Graphical Representations of Kinematical Concepts: A Comparison of Teaching Strategies
Authors: Guidugli Silvina , Gauna Cecilia Fernández , Benegas Julio
Published: August 2005

Student difficulties with kinematics concepts and their representations by linear graphs are well known. Several specific learning difficulties have been identified and reported, mainly from studies at the introductory university physics level.1–4 In this paper we investigate the effectiveness of active learning strategies versus traditional instruction on the development of student understanding of kinematical concepts, and their graphical representations, by high school students. We also examine the retention of acquired kinematic concepts and whether it might be affected by subsequent (traditional) instruction.
Soap, Colors, Holes, and Much More
Authors: Gratton L. M. , Oss S.
Published: August 2005

A number of interesting and engaging activities dealing with soap films have appeared in the physics teaching literature.1 In this paper we describe a simple activity that demonstrates some important and intriguing aspects of the physics of thin fluid films.
Muscular development and physical activity as major determinants of femoral bone mass acquisition during growth
Authors: Vicente-Rodriguez G , Ara I , Perez-Gomez J , Dorado C , Calbet J A L
Published: August 2005

Objectives:To investigate to what extent bone mass accrual is determined by physical activity and changes in lean, fat, and total body mass during growth.

Methods:Twenty six physically active and 16 age matched control boys were followed up for three years. All subjects were prepubertal at the start of the survey (mean (SEM) age 9.4 (0.3) years). The weekly physical activity of the active boys included compulsory physical education sessions (80–90 minutes a week), three hours a week of extracurricular sports participation, and occasional sports competitions at weekends. The physical activity of the control group was limited to the compulsory physical education curriculum. Bone mineral content (BMC) and areal density (BMD), lean mass, and fat mass were measured by dual energyxray absorptiometry.

Results:The effect of sports participation on femoral bone mass accrual was remarkable. Femoral BMC and BMD increased twice as much in the active group as in the controls over the three year period (p<0.05). The greatest correlation was found between the increment in femoral bone mass and the increment in lean mass (BMCr =  0.67 and BMDr =  0.69, both p<0.001). Multiple regression analysis revealed enhancement in lean mass as the best predictor of the increment in femoral bone BMC (R =  0.65) and BMD (R =  0.69).

Conclusions:Long term sports participation during early adolescence results in greater accrual of bone mass. Enhancement of lean mass seems to be the best predictor of this bone mass accumulation. However, for a given muscle mass, a greater level of physical activity is associated with greater bone mass and density in peripubertal boys.
Hypermobility and sports injuries in junior netball players
Authors: Smith R , Damodaran A K , Swaminathan S , Campbell R , Barnsley L
Published: August 2005

Objective:To evaluate the incidence of hypermobility in young female netball players and to determine the relation between hypermobility, previous injuries sustained in netball or other sports, and the use of protective equipment.

Methods:Under 16 year old female netball players from a local suburban netball association were assessed for joint hypermobility using the validated Beighton score (0–9, with higher scores indicating increasing hypermobility). Player profiles and details of sporting injuries, both netball and non-netball, and the use of protective equipment were gathered by means of a self completed questionnaire. Parental and child consent was obtained.

Results:Two hundred netball players were recruited for the study. Twenty one percent of the subjects with a Beighton hypermobility score of 0–2 had sustained previous netball injuries compared with 37% with Beighton scores of 3–4, and 43% with scores of 5–9. These differences were significant (p<0.025). Injuries were most common in the ankle (42%), knee (27%), and fingers (15%). Thirty nine players (19%) wore protective equipment, and within this group 30 (77%) had sustained previous injuries. No association was detected between hypermobile joints and non-netball sporting injuries.

Conclusions:In this study hypermobility was significantly associated with an increased prevalence of injuries in junior netball players. A targeted interventional approach may help to reduce injuries in this susceptible group.
The risk of chronic traumatic brain injury in professional boxing: change in exposure variables over the past century
Authors: Clausen H , McCrory P , Anderson V
Published: August 2005

Objectives:To determine if boxing exposure has changed over time and hence if current professional boxers are at the same risk of developing chronic traumatic brain injury (CTBI) as historical controls.

Design:Literature review of published studies and analysis of data of active professional boxers.

Subjects:Professional boxers in the United Kingdom and Australia.

Main outcome measures:Boxing history and participation in sparring and professional bouts.

Results:Since the 1930s, the average duration of a professional boxer’s career has dropped from 19 years to five years, and the mean number of career bouts has reduced from 336 to 13. This is despite no significant decline in participation rates from 1931 until 2002.

Conclusions:The incidence of boxing related CTBI will diminish in the current era of professional boxing because of the reduction in exposure to repetitive head trauma and increasing medical monitoring of boxers, with preparticipation medical and neuroimaging assessments resulting in the detection of early and potentially pre-symptomatic cases of CTBI.
A comparison of physiological and anthropometric characteristics among playing positions in junior rugby league players
Authors: Gabbett T J
Published: August 2005

Objectives:To compare the physiological and anthropometric characteristics of specific playing positions and positional playing groups in junior rugby league players.

Methods:Two hundred and forty junior rugby league players underwent measurements of standard anthropometry (body mass, height, sum of four skinfolds), muscular power (vertical jump), speed (10, 20, and 40 m sprint), agility (L run), and estimated maximal aerobic power (multi-stage fitness test) during the competitive phase of the season, after players had obtained a degree of match fitness.

Results:Props were significantly (p<0.05) taller, heavier, and had greater skinfold thickness than all other positions. The halfback and centre positions were faster than props over 40 m. Halfbacks had significantly (p<0.05) greater estimated maximal aerobic power than props. When data were analysed according to positional similarities, it was found that the props positional group had lower 20 and 40 m speed, agility, and estimated maximal aerobic power than the hookers and halves and outside backs positional groups. Differences in the physiological and anthropometric characteristics of other individual playing positions and positional playing groups were uncommon.

Conclusions:The results of this study demonstrate that few physiological and anthropometric differences exist among individual playing positions in junior rugby league players, although props are taller, heavier, have greater skinfold thickness, lower 20 and 40 m speed, agility, and estimated maximal aerobic power than other positional playing groups. These findings provide normative data and realistic performance standards for junior rugby league players competing in specific individual positions and positional playing groups.
The effectiveness of a squash eyewear promotion strategy
Authors: Eime R , Finch C , Wolfe R , Owen N , McCarty C
Published: August 2005

Objective:To evaluate the protective eyewear promotion (PEP) project, which was a comprehensive educational strategy to increase the use of appropriate protective eyewear by squash players.

Methods:An ecological study design was used. Four squash venues in one playing association were randomly chosen to receive PEP and four in another association maintained usual practice and hence formed a control group. The primary evaluation measurements were surveys of cross sectional samples of players carried out before and after the intervention. The surveys investigated players’ knowledge, behaviours, and attitudes associated with the use of protective eyewear. The survey carried out after the intervention also determined players’ exposure to PEP. Univariate and multivariate analyses were undertaken to describe differences at PEP venues from pre- to post-intervention and to compare these with the control venues.

Results:The PEP players had 2.4 times the odds (95% confidence interval, 1.3 to 4.2) of wearing appropriate eyewear compared with control group players post-intervention, relative to the groups’ pre-intervention baselines. Components of PEP, such as stickers and posters and the availability and prominent positioning of the project eyewear, were found to contribute to players adopting favourable eyewear behaviours.

Conclusions:Components of the PEP intervention were shown to be effective. The true success will be the sustainability and dissemination of the project, favourable eyewear behaviours, and evidence of the prevention of eye injuries long into the future.
THE UNIVERSE AS A NONUNIFORM LATTICE IN THE FINITE-DIMENSIONAL HYPERCUBE. II: SIMPLE CASES OF SYMMETRY BREAKDOWN AND RESTORATION
Authors: SHALYT-MARGOLIN A. E.
Published: August 2005

This paper continues a study of field theories specified for the nonuniform lattice in the finite-dimensional hypercube with the use of the earlier described deformation parameters. The paper is devoted to spontaneous breakdown and restoration of symmetry in simple quantum field theories with scalar fields. It is demonstrated that an appropriate deformation opens up new possibilities for symmetry breakdown and restoration. To illustrate, at low energies (far from the Planck's) it offers high-accuracy reproducibility of the same results as with a nondeformed theory. In the case of transition from low to higher energies and vice versa it gives description for new types of symmetry breakdown and restoration depending on the rate of the deformation parameter variation in time, and indicates the critical points of the previously described lattice associated with a symmetry restoration. Besides, such a deformation enables one to find important constraints on the initial model parameters having an explicit physical meaning.
COLLISION INDUCED FRAGMENTATION OF FULLERENE CLUSTERS (C60)n
Authors: MANIL B. , BODUCH P. , CASSIMI A. , KAMALOU O. , MAUNOURY L. , RANGAMA J. , HUBER B. A. , JENSEN J. , ZETTERGREN H. , CEDERQUIST H.
Published: August 2005

Clusters of C 60 fullerenes are (multi)-ionised in collisions with O 5+ projectiles at a collision energy of 100 keV. The dominant fragmentation channels are analysed by time-of-flight mass spectrometry for different cluster size distributions. Singly charged [Formula: see text], ions are found to be the dominant fragments, in 25% connected with the loss of one or more C 2-units. This result is explained by the large charge mobility in fullerene clusters. Doubly charged fragments, in form of [Formula: see text] and [Formula: see text], contribute to the observed spectrum with less than 5–10% only and are mainly attributed to the fragmentation of dimers. Singly charged small carbon clusters in the size range n = 7 to 19 are formed with low kinetic energies indicating the importance of thermal dissociation processes. The present experiments confirm earlier conclusions on the charge mobility in fullerene clusters.
CHARACTERIZATION OF 3D TRANSITION-METAL DIBORIDES BY X-RAY-ABSORPTION SPECTRA AT THE METAL K EDGE
Authors: CHU W. S. , WU Z. Y. , AGRESTINI S. , BIANCONI A. , MARCELLI A. , LIU W. H.
Published: August 2005

The 3d transition-metal diborides TiB 2, VB 2 and CrB 2 have been characterized by X-ray absorption near-edge-structure (XANES) spectroscopy at the metal K edges. XANES spectra at the Ti , V and Cr K -edges of TiB 2, VB 2 and CrB 2, respectively, show similar spectral features up to an energy of about 70 eV above threshold. These features can be correlated to their specific atomic arrangement and electronic structure via multiple-scattering calculations as a function of the cluster size. Actually the second pre-edge feature is assigned to a transition from the metal 1s core state to the central metal 4p state hybridized with 3d band state of the higher-shell metal atoms. The first weak feature on the rising part of the edge is due to higher-shells multiple scattering contributions, suggesting that the transition features at the metal K -edge XANES of 3d transition-metal diborides are strongly affected by medium or long-range order contributions.
OXYGEN INFLUENCE ON PHOTOINDUCED TRANSFORMATION OF C60 FILM
Authors: LIU X. J. , ZHANG S. Y. , DING D. S.
Published: August 2005

We have investigated the photoinduced transformation of C 60 film in air at 300 K by means of Raman scattering spectroscopy and atomic force microscopy (AFM). In the Raman experiments, we have observed a new Raman band at 1426 cm-1, which is absent in the photoinduced polymerized C 60 phase. Furthermore, we have investigated the surface structure of the C 60 film with variation of the photo-irradiation time in air by using AFM, and have found some lamella-like structures. We have ascribed the 1426 cm-1 band and the lamella-like structures to the formation of fragmentary graphite in the surface of C 60 film.
13C NMR STUDY ON ONE DIMENSIONAL FULLERENE POLYMER
Authors: WANG SUQIN , GU MIN , YU YAO , XU XIAONONG , WU JIAN , YUAN GUOQIU , FENG DUAN
Published: August 2005

We have prepared three C 60 polymers under high-temperature and high-pressure conditions, and confirmed them to be orthorhombic (1D), tetragonal and rhombohedral (2D) polymer by XRD method, respectively. The 13 C MAS NMR spectra of both orthorhombic and rhombohedral polymer have been measured and two resonance peaks observed. One resonance at 73 ppm resulted from the sp3 carbons with an intermolecular bonding, the other at 145 ppm is from the inequivalent sp2 carbons on the C 60 molecule. For 1D polymer, the fine structure of the main peak at 145 ppm has been analyzed. By simulation of the 13 C MAS NMR peak shape of the inequivalent carbons, we propose that there exist nine inequivalent carbons on a C 60 molecule in the orthorhombic (1D) polymer.