bluuebunny/crossref_metadata_2025 huggingface dataset:
Judge‐Jury Agreement in Criminal Cases: A Partial Replication of Kalven and Zeisel's The American Jury
Authors: Eisenberg Theodore , Hannaford‐Agor Paula L. , Hans Valerie P. , Waters Nicole L. , Munsterman G. Thomas , Schwab Stewart J. , Wells Martin T.
Published: March 2005

This study uses a new criminal case data set to partially replicate Kalven and Zeisel's classic study of judge‐jury agreement. The data show essentially the same rate of judge‐jury agreement as did Kalven and Zeisel for cases tried almost 50 years ago. This study also explores judge‐jury agreement as a function of evidentiary strength (as reported by both judges and juries), evidentiary complexity (as reported by both judges and juries), legal complexity (as reported by judges), and locale. Regardless of which adjudicator's view of evidentiary strength is used, judges tend to convict more than juries in cases of “middle” evidentiary strength. Judges tend to acquit more than juries in cases in which judges regard the evidence favoring the prosecution as weak. Judges tend to convict more than juries in cases in which judges regard the evidence favoring the prosecution as strong. Rates of adjudicator agreement are thus partly a function of which adjudicator's view of evidentiary strength is used, a result not available to Kalven and Zeisel, who were limited to judges’ views of the evidence. We find little evidence that evidentiary complexity or legal complexity help explain rates of judge‐jury disagreement. Rather, the data support the view that judges have a lower conviction threshold than juries. Local variation exists among the sites studied. The influences of juror race, sex, and education are also considered.
A comparison of methods for determining genotypes at the tumour necrosis factor‐α−308, interleukin (IL)‐1β+3953, IL‐6 −174 and IL‐10 −1082/−819/−592 polymorphic loci
Authors: Bown M. J. , Weston S. , Horsburgh T. , Nicholson M. L. , Bell P. R. F. , Sayers R. D.
Published: March 2005

Induced heteroduplex genotyping (IHG) is one of many methods that can be used to determine single nucleotide polymorphisms (SNPs). It is relatively new in comparison to other polymerase chain reaction (PCR)‐based techniques. The aim of this study was to compare the results of genotyping using IHG with the results of genotyping using either polymerase chain reaction–sequence‐specific primers (PCR‐SSP) or polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) for SNPs in the tumour necrosis factor (TNF)‐α, interleukin (IL)‐1β, IL‐6 and IL‐10 genes. Ninety patients who consented to participate in the study had their genotypes determined by IHG and either PCR‐SSP (TNF‐α−308 and IL‐10 −1082/−819/−592) or PCR‐RFLP (IL‐1β+3953 and IL‐6 −174). Results for each locus were compared between techniques by calculating the Kappa statistic as a measure of agreement. The IHG and more traditional genotyping methods produced very similar results at all loci. The Kappa statistics for each locus were as follows: TNF‐α−308, K = 0.727; IL‐1β+3953, K = 0.886; IL‐6 −174, K = 0.909; IL‐10 −1082, K = 0.876; IL‐10 −592, K = 0.920. IHG is a valid method for the determination of genotypes at the loci examined in this study and produces comparable results to those of more traditional methods of genotyping.
Photon mass experiment
Authors: Crandall R. E.
Published: March 2005

A Coulomb null experiment is described that enables physics students to obtain rigorous upper bounds on photon mass. The experimenter searches for subnanovolt signals that would escape a closed shell were photon mass to be positive. The approach can be adapted for several college levels. At the simplest level, a ‘‘miniature’’ low-cost experiment allows a student to verify the exponent ‘‘−2’’ in Coulomb’s law to eight or more decimal places. An advanced student given a full-size apparatus (at greater cost) can obtain mass bounds very close to the established laboratory limit.
Universal variables in the two-body problem
Authors: Everhart Edgar , Pitkin Edward T.
Published: March 2005

Universal variables offer a considerable improvement on classical methods of solving the two-body problem. The method has the same structure regardless of whether the orbit is an ellipse, parabola, or hyperbola. The near-parabolic orbit is handled with ease. Universal variables are particularly useful when starting with a position–velocity vector at time zero and finding this vector at any other time. This paper is tutorial, written in the belief that this method should be better known. A laboratory exercise is described which uses universal variables in plotting orbits in the solar system. The Appendix contains a concise derivation of the equations for universal variables.
Spinning objects on horizontal planes
Authors: Whitehead Lorne A. , Curzon Frank L.
Published: March 2005

We present a simple theoretical analysis, of a common form of motion of a rotationally symmetric object (or symmetric top). The object, with its center of mass stationary, spins about its symmetry axis and rolls without slipping on a horizontal surface. The motion, which is referred to in the paper as ‘‘wobbling,’’ is long-lasting and stable and is exhibited by common objects (coins, bottles, plates, etc.) when they are spun on horizontal, flat surfaces. An apparatus is described for maintaining the ‘‘wobbling’’ motion of a metal cylinder, which can be observed in slow motion by means of stroboscopic illumination.
Second quantization in nonrelativistic quantum mechanics
Authors: Kobe Donald H.
Published: March 2005

Second quantization in nonrelativistic quantum mechanics is given in a simplified way using eigenstates of the number operator. The field creation operator is shown to be the operator which adds a particle with a delta-function wave function to the system, while the field annihilation operator removes a particle with a delta-function wave function from the system. The field creation operator is proved to be the Hermitian conjugate of the annihilation operator. The commutation (anticommutation) relations for boson (fermion) field operators are proved from the symmetry (antisymmetry) of the many-particle wave function. The second quantized form of one- and two-particle operators is obtained from their form in wave mechanics using the definition of the field creation and annihilation operators.
A real ‘‘thought’’ experiment for the hydrogen atom
Authors: McCarthy I. E. , Weigold E.
Published: March 2005

The absolute square of the normalized position-space wave function of the electron in a hydrogen atom is interpreted as the probability distribution for observations of the position of the electron. This is only a thought experiment, since the electron’s position cannot be observed. The first observation of the momentum distribution of the electron directly verifies the probability interpretation of the momentum-space wave function.
Differential forms as a basis for vector analysis—with applications to electrodynamics
Authors: Schleifer Nathan
Published: March 2005

I give a concise and self-contained presentation of the theory of differential forms and how it subsumes all of classical vector analysis when applied to a three-dimensional space. The differential form analog of all vector operators, identities, and theorems are given (many of which are proved), all in the context of classical electrodynamics.
Elastic electron-atom collision effects in the Franck–Hertz experiment
Authors: McMahon D. R. A.
Published: March 2005

In the Franck–Hertz experiment one observes the effect of inelastic collisions in which fixed quanta of energy are exchanged between electrons and atoms. It is shown here that one can also readily demonstrate with a Franck–Hertz apparatus energy-dependent features of the elastic collision cross section. For mercury vapor of sufficiently high pressure, elastic electron–atom collisions between the grid and the anode are able to energy analyze the electrons so that the characteristic peaks and troughs in the anode current are still observed without the traditional retarding field to separate off the lowest-energy electrons. This is because in mercury vapor the most energetic electrons have the longest mean free path, are more penetrating through the gas, and are the most likely electrons to reach the anode. The electron transport theory for this effect is developed and applied to a crude determination of the electron energy distribution. Not surprisingly, the electron energy distribution in this experiment consists of two electron groups separated in energy by 4–5 eV consistent with the known 61S-63P energy-level separation in mercury of 4.9 eV.
Laser spectroscopy on a ‘‘shoestring’’
Authors: Camparo J. C. , Klimcak C. M.
Published: March 2005

The advent of tunable lasers has had a profound influence on both experimental and theoretical physics. Unfortunately, since these laser systems are typically hazardous and expensive, the physics student at the undergraduate or first-year graduate level has no real familiarity with their application in modern physics; and thus cannot fully appreciate their significance. Tunable single mode laser diodes, however, may offer a remedy to this situation. To demonstrate their applicability, we have designed a relatively simple and inexpensive experiment of laser diode spectroscopy in an atomic beam which illustrates the effect of hyperfine structure and the isotope shift in the rubidium D1 transition (52S1/2−52P1/2). Furthermore, this experiment demonstrates the possibility of investigating basic physics without major expenditures for laser systems and laboratory facilities.
Measuring the speed of light by independent frequency and wavelength determination
Authors: Bates Harry E.
Published: March 2005

The most recent measurements of the speed of light have been based on a separate determination of the frequency and wavelength of laser radiation. As a result of the increased precision and the imbalance in precision between frequency and wavelength measurements, the speed of light in a vacuum c (299,792,458 m/s) has been proposed as a defined standard constant connecting time and length measurements. This paper reports on a student experiment at the intermediate undergraduate level that contains the fundamental elements found in the most recent determination of c. Harmonic mixing is utilized for the frequency determination and interferometry for the wavelength determination of a 9-GHz electromagnetic source.
Abstract matrix band theory for one-dimensional lattices: Canonical representations and functions: A wave vector addition theorem
Authors: Strandberg M. W. P.
Published: March 2005

The matrix representations for the space translations appropriate to Schrödinger’s equation for a one-dimensional periodic potential are developed. From these matrices the canonical form for the dispersion function relating the energy and the Bloch wave vector is derived. The Lie algebra of the group of the Schrödinger equation is used to identify the corrections made to semiclassical band theory by the noncommutivity of the quantum-mechanical representations. As an example of the usefulness of the representational approach, the Saxon–Hutner–Luttinger theorem for bands in composite lattices is proved in general, and extended to the whole dispersion function, and for any number of inequivalent atoms. The proof is based on an addition theorem for Bloch wave vectors of inequivalent lattices.
Holographic detection of defects under the surface of solid objects
Authors: Hemmick Thomas K. , Huang Jacob W. , Song Yu Dong
Published: March 2005

In this paper we introduce a simple, low-cost experimental system designed to demonstrate the effectiveness and sensitivity of optical testing to undergraduate students. The technique used involves generating stress by heating a material locally and detecting by holographic interferometry.
Classical approach to the problem of an electron in a periodic potential
Authors: Nawrocki M. , Gaj J. A.
Published: March 2005

Motion of an electron in a periodic potential is analyzed with use of a simple classical model. A calculation and a demonstration experiment described show the usefulness of the model in the teaching of solid-state physics.
An up-to-date approach to physics
Authors: Schmid G. Bruno
Published: March 2005

A unified approach to science teaching based upon a certain class of quantities which play fundamental roles in classical and modern physics is introduced. These quantities share the property of being substance-like, that is, each can be pictured to be contained in bodies and to flow from one body to another like a kind of ‘‘stuff.’’ Such quantities include, for example, energy (=mass), momentum, angular momentum, electric charge, particle number (=amount of substance), and entropy. When emphasizing substance-like quantities, the breakup of physics into sub-branches is nothing more than a classification of natural processes according to the substance-like quantity playing the dominant role in each case. The method of presentation, however, remains the same from one sub-branch to another: different natural processes can be simply visualized and quantitatively described according to the same formal rules in terms of the increasing, decreasing, and flowing of the respective substance-like quantities in each case. Thus knowledge of a single branch of physics already provides an analogy for the ways and means by which processes are described in other branches (including chemistry and biology) as well. These claims are illustrated with the help of a few simple examples.
The new definition of the meter
Authors: Giacomo P.
Published: March 2005

An overview is given of the past definitions of the meter, with emphasis on the guidelines which governed the choice of the new definition. Preliminary laboratory work, discussions, and consequences with regard to future research are sketched.
Internal energy in the first law of thermodynamics
Authors: Erlichson Herman
Published: March 2005

The definition of the internal energy of a thermodynamic system in most introductory texts usually states or implies that the c.m. kinetic energy of the system is not part of the internal energy. This is inconsistent with their statement of the first law of thermodynamics as ΔU=Q−W. If the c.m. kinetic energy is not considered part of U, the first law should be stated as ΔU+ΔKc.m.=Q−W. Several examples are given. Clarification of this point is needed in many widely used texts.
An exactly soluble one-dimensional, two-particle problem
Authors: Gersch H. A.
Published: March 2005

We examine a one-dimensional problem involving two interacting particles in an external field for which the Schrödinger equation can be solved analytically for the ground state. The Hartree approximation for this system also has a simple analytic solution of the form previously derived by Foldy. Comparison of exact and Hartree solutions leads to precise estimates of the effect of correlations on the binding energy and on the two-particle probability distribution.
Bifurcations, propagating solutions, and phase transitions in a nonlinear chemical reaction with diffusion
Authors: Albano A. M. , Abraham N. B. , Chyba D. E. , Martelli M.
Published: March 2005

The Schlögl model of a nonlinear chemical reaction with diffusion is presented as an example of a reaction-diffusion system displaying a nonequilibrium phase transition. It is described by a scalar diffusion equation with a cubic nonlinearity and is used here to show such features of nonlinear systems as bifurcations and spatial dissipative structures, as well as to illustrate some of the simpler mathematical techniques used in their analysis. The model contains analogs of the critical isotherm and of Maxwell’s construction. It shows hysteresis and a limiting behavior interpretable in terms of the thermodynamic limit. More importantly, it provides a description of the dynamics of a phase transition, showing a fluctuation-induced nucleation process and the evolution of a phase transition by the motion of phase boundaries.
Coefficient of friction for a sphere
Authors: Chaplin R. L. , Miller M. G.
Published: March 2005

A ball that rolls on parallel tracks, whose width is less than the diameter of the ball, experiences both translational and rotational motions. The linear accelerations of the ball for cases of rolling and slipping are derived theoretically, and these accelerations have also been determined by performing experiments when the width and the angular elevation of the tracks are controlled. Data show when slipping occurs for the rolling motion, and the onset of slipping is used to compute the coefficient of kinetic friction for a sphere. A second method of determining the coefficient of friction, for the sphere slipping without rolling, provides confirmation for this analysis.
Reversibility and step processes: An experiment for the undergraduate laboratory
Authors: Gupta V. K. , Shanker Gauri , Sharma N. K.
Published: March 2005

An experiment with a spring is described to illustrate the fact that the irreversibility involved in a physical process in transforming the system from an initial state to a terminal state bears an inverse relationship to the number of discrete steps in which it is carried out, leading to the conclusion that the process becomes reversible as the number of steps tends to infinity. A similar relationship is shown to hold for processes like charging of a capacitor and compression of a perfect gas.
Pauli spinors and Hestenes’ geometric algebra
Authors: Hamilton J. Dwayne
Published: March 2005

Hestenes’ geometric algebra and Pauli’s two-component spinors are reviewed and are united into a simple mathematical system. The resulting formalism is used to develop a new method for spin 1/2 projection calculations and is also applied to a spin 1/2 electron magnetic resonance problem.
Two-dimensional time-dependent quantum-mechanical scattering event
Authors: Galbraith Ian , Ching Yin Sing , Abraham Eitan
Published: March 2005

Nonrelativistic quantum-mechanical scattering in two dimensions is studied numerically by integrating the time-dependent Schrödinger equation. A partial-wave analysis is used to discuss the numerical results. A potential barrier, a square well and a single slit are considered as the scattering potentials.
A better least-squares method when both variables have uncertainties
Authors: Lybanon Matthew
Published: March 2005

The generalized least-squares problem, in which an observation vector satisfies a set of equations that may be nonlinear and implicit, and all components may be subject to errors, can be solved as a constrained minimization problem. When the analysis is specialized to the important case of one-dimensional curve fitting to measurements where both variables contain errors, it becomes similar to the effective variance method. A standard least-squares computer program can be used to apply the new method; the results are superior to these of the effective variance technique. A simple geometrical construction illustrates the principles of the new method.
Mechanical model for 2-state Markov chains
Authors: Leong Y. K.
Published: March 2005

We show that a 2-state Markov chain can be described by a simple mechanical model in which the transition probabilities of the chain are generated according to the laws of Newtonian dynamics and the stationary probability distribution corresponds to a dynamical steady state. This mechanical system can conversely be described by a probabilistic (random-walk) model which is completely adequate in some cases. Our analogy also gives rise to a class of homogeneous quadratic functions of the n-step transition probabilities which may be considered as ‘‘transition energies’’ of the Markov chain. There is also a physical interpretation of the eigenvalues of the transition probability matrix.
Normal matrices for physicists
Authors: Macklin Philip A.
Published: March 2005

Normal matrices are the largest class of matrices which can be diagonalized by unitary transformations. They include Hermitian, anti-Hermitian, unitary, real symmetric, and real orthogonal matrices, the primary types of interest to physicists. An aesthetically and practically satisfying synthesis as well as a significant saving of effort is achieved by studying normal matrices first and then deducing results for the various particular types subsequently. A simple constructive proof of the fundamental result that every normal matrix can be diagonalized by a unitary matrix is given.
Alpha-particle-induced, inner-shell ionization measurements for the undergraduate laboratory
Authors: Desmarais D. , Duggan J. L.
Published: March 2005

The interaction of α particles with low atomic number elements has been studied in an attempt to determine the inner-shell ionization cross section. These cross sections were determined by measuring the characteristic x rays that were produced when a thin aluminum target was bombarded by α particles from a 48-MBq 224Cm α source. The x rays were detected with a Si(Li) x-ray detector whose resolution was 190 eV at 5.9 keV. The efficiency of the detector was determined from standard radioactive sources. The energies of the α particles were varied by placing thin Mylar absorbers between the α source and the target. The results are favorably compared to a current ionization theory given in such a form that an undergraduate physics major can do the calculations. This experiment is intended as an undergraduate laboratory experiment in the atomic or nuclear area.
Maxima and minima without calculus
Authors: Thomsen John S.
Published: March 2005

Many physical systems are described by quadratic equations. In such cases the requirement for a real solution is that the discriminant be non-negative. This requirement can often lead, directly or indirectly, to maximizing or minimizing some system variable of interest. Three examples suitable for a noncalculus physics course are given : (1) projectile motion, (2) hydrostatic equilibrium (Archimedes’ principle), and (3) resistance matching.
Radiation reaction revisited
Authors: Cook Richard J.
Published: March 2005

The Abraham-Lorentz equation of motion for a charged particle admits ‘‘runaway’’ solutions which violate the law of inertia. The integrodifferential form of the Abraham–Lorentz equation eliminates the runaway solutions, but in so doing introduces ‘‘preacceleration’’ which violates the principle of causality. Here it is shown that there exists a form of the equation of motion for a nonrelativistic charged particle which is in accord with both the law of inertia and the principle of causality.
Inverse sprinklers: A lesson in the use of a conservation principle
Authors: Forrester A. Theodore
Published: March 2005

When a common lawn sprinkler is hooked to a suction, rather than a pressure source the conservation of angular momentum can be invoked to show that no rotation will result. A recently reported experiment leading to a different conclusion is not the equivalent of simply changing from a fluid exhaust to a fluid intake.
When is a quantum measurement?
Authors: Peres Asher
Published: March 2005

The measurement of a quantum system is not consummated until irreversible processes have destroyed all phase coherence between different possible outcomes of that measurement. It is inconsistent to assume that the wavefunction ‘‘collapses’’ before irreversibility sets in.
Evaluating the effectiveness of an elementary undergraduate laboratory
Authors: Buckmaster H. A.
Published: March 2005

This article describes an examination problem which has been found useful in evaluating the global effectiveness of introductory undergraduate laboratory experiments.
Frustrated total internal reflection: A demonstration and review
Authors: Zhu S. , Yu A. W. , Hawley D. , Roy R.
Published: March 2005

Frustrated total internal reflection (FTIR) has been studied since the time of Newton and Fresnel. We review its history and applications in modern optics. A simple theoretical description of the phenomenon is presented using Maxwell’s equations. The analogy (often made in textbooks) between FTIR and quantum mechanical tunneling in one dimension is discussed. A simple experimental apparatus, suitable for a laboratory demonstration, is described and a quantitative comparison of the theory with experiment is made at optical wavelengths. A He–Ne laser, power meter, and a simply constructed double-prism arrangement are used for the demonstration.
Experimental determination of the coefficient of drag of a tennis ball
Authors: Zayas Joseph M.
Published: March 2005

The standard projectile motion experiment in the general physics laboratory using a spring gun and metal projectile is not sufficiently sensitive to detect air resistance effects of the ball’s motion. These effects may be successfully studied by using a commercial tennis ball pitching machine which is capable of launching balls with speeds up to about 27 m/ s with negligible spin. Assuming an air resistance force of the form f=−bv2, the coefficient b may be shown by direct solution of the equations of motion to be dependent on the muzzle velocity, the horizontal speed of the ball as it strikes the ground, and its landing angle. By measuring these quantities, b may be obtained and its value then used to compute the drag coefficient CD for the ball. Experimental values of CD compare well with similar values obtained for smooth spheres by other methods.
More on the concentration dependence of Fick’s laws
Authors: Ghez R. , Langlois W. E.
Published: March 2005

We show that concentration-dependent diffusivities that enter Fick’s laws can be derived from random-walk models of diffusion. In particular, Darken’s phenomenological expression for that dependence results if the transition frequencies depend on the occupation of final states. We develop the one-dimensional discrete-to-continuum passage with some care, and, in particular, we show that fluxes must be defined at the midpoint between lattice sites, even for nonlinear problems.
The dielectrophoresis force
Authors: Benguigui L. , Lin I. J.
Published: March 2005

We present a simple and physically transparent calculation of the dielectrophoresis force, i.e., a force acting on neutral bodies in nonuniform electric fields in the cases of dc and ac fields.
Mercury’s precession according to special relativity
Authors: Phipps Thomas E.
Published: March 2005

It is shown that special relativistic mechanics, when augmented by a particular version of the equivalence principle, predicts essentially the same numerical value as does the general theory for the precession anomaly of the planet Mercury. A possible laboratory experiment to test this version of the equivalence principle is discussed.
A basic acoustic diffraction experiment for demonstrating the geometrical theory of diffraction
Authors: Narod B. Barry , Yedlin Matthew J.
Published: March 2005

An apparatus is described in which acoustic diffractions are generated. Such diffractions are recorded in the field when seismic data is collected over a geological area that has many faults and truncated geological structures. The design of the experiment is considered from the point of view of theoretical feasibility and practical implementation. A computer-controlled transceiver is guided on a traverse perpendicular to a model of a rigid half-plane. At each transceiver location an acoustic pulse is emitted, and the scattered acoustic pulse is recorded. Results of this experiment are presented and analyzed from the perspective of Keller’s geometric theory of diffraction. The predicted asymmetry of the diffraction hyperbola is observed in the model data collected.
Repulsive gravitation and inflationary universe models
Authors: Gro/n O/.
Published: March 2005

The phenomenon of gravitational repulsion is described within the context of the general theory of relativity. The theory implies that if a vacuum has a nonvanishing energy, then its gravitational mass density will be negative. In particular, this implies that the universe will expand exponentially during the vacuum dominated inflationary era. It is suggested that the observed expansion of the universe may be explained as a result of repulsive gravitation.
Probability theory in quantum mechanics
Authors: Ballentine L. E.
Published: March 2005

The abstract theory of probability and its interpretation are briefly reviewed, and it is explicitly demonstrated that the formalism of quantum mechanics satisfies the axioms of probability theory. This refutes the suggestions which have occasionally been made that ‘‘classical’’ probability theory does not apply to quantum mechanics. Several erroneous applications of probability theory to quantum mechanics are examined, and the nature of the errors are exposed. It is urged that more attention be given to probability theory in the physics curriculum.
‘‘F=m
a’’ optics
Authors: Evans James , Rosenquist Mark
Published: March 2005

Fermat’s principle may be used to derive an equation, of the form F=ma, governing the shape of a light ray in a medium of varying refractive index. Many interesting problems in gradient-index optics that ordinarily require considerable computation may therefore be solved very simply by analogy to familiar mechanical problems. This approach also provides the means of thoroughly exploring the optical-mechanical analogy at a much more elementary level than is usual.
Threshold anomalies in one-dimensional scattering
Authors: Senn Peter
Published: March 2005

In one-dimensional scattering, the portion of particles that is transmitted in general vanishes as the kinetic energy of the incident particles approaches zero. Based upon published results from the literature, the present work shows that for a potential consisting of two Dirac δ functions of arbitrary strength, a finite portion of the incident particles is transmitted at threshold for certain choices of the set of parameters defining the potential. The underlying reasons are shown to be related to the structure of the bound levels of the potential. It is shown that for a potential with a finite range but of general shape the reflection coefficient in general tends to unity near threshold, which is what is usually observed. However, in the presence of a bound level at the onset of the continuum, a finite portion of the incident particles is transmitted at threshold for a potential with a general shape and, furthermore, it can be shown that if the potential V is symmetric with V(x)=V(−x) then resonance transmission is observed, i.e., the reflection coefficient vanishes at threshold.
Are dilute solutions always dilute?
Authors: Gitterman M.
Published: March 2005

Near the critical points of a binary mixture a solution is never ‘‘dilute.’’ The correct formula for the solvent’s chemical potential requires the fulfillment of some thermodynamic relations near the liquid–gas critical point, which have been proven experimentally. The enhanced solubility of solids in supercritical fluid is analyzed.
Rainbow dust
Authors: Crawford Frank S.
Published: March 2005

Beautiful ‘‘rainbows’’ produced by tiny glass spheres are described.
Minimally relativistic Newtonian gravity
Authors: Biswas T.
Published: March 2005

Special relativity is introduced into the theory of Newtonian gravity in a systematic manner. The modifications of Newtonian gravity that are made can be seen to be minimal for special relativistic covariance. Space is assumed to be flat. Particle trajectories are determined from a Hamiltonian formulation with a tensor potential hμν. The tensor nature of the potential is justified by requiring Lorentz covariance alone. Nongeneral relativistic field equations for the hμν are obtained. The static, spherically symmetric solutions of these equations are shown to produce the correct values for the precession of the orbit of Mercury and the bending of light near the Sun.
E=m
c2
Authors: Feigenbaum Mitchell J. , Mermin N. David
Published: March 2005

A purely mechanical version is given of Einstein’s 1905 argument that the mass of a body depends on its energy content. The Gedankenexperiment described here is the same as Einstein’s, except that the body loses energy not through electromagnetic radiation, but through the emission of massive particles. The concept of mass is not assumed, but is extracted as one of two constants of integration. Viewing mass in this way emphasizes a sometimes obscured distinction between mass as a proportionality constant in the kinetic energy (for which E=mc2 has profound physical content), and mass as it appears in the conventional relativistic rest energy (for which E=mc2 is merely a convenient convention).
Analysis of billiard ball collisions in two dimensions
Authors: Wallace R. Evan , Schroeder Michael C.
Published: March 2005

An analysis of billiard ball collisions in two dimensions with a full account of frictional effects is presented. An experiment designed to test the predictions of the analysis is described. Data are presented showing that the angle between the directions of travel of billiard balls after a collision in which one ball is initially stationary depends on the impact parameter in a rather complicated way, and is not 90 deg as is commonly claimed.
Professors as physics students: What can they teach us?
Authors: Tobias Sheila , Hake R. R.
Published: March 2005

Ten nonphysical-science professors studied Newton’s laws for a 3-week period along with 323 students in a noncalculus-based introductory physics course for science majors. The course contained innovations described in an earlier article [R. R. Hake, Am. J. Phys. 55, 878 (1987)]. Pre- and post-course mechanics exams indicated substantial increase in conceptual understanding for both professors and students over that obtained by students subjected to conventional instruction. The perspectives of the professorial peers on the innovations and various other aspects of the course are quoted at some length. Their major suggestions for instructional improvement of introductory physics courses are: (1) slow the pace at which topics are covered; (2) relate all educational activities to precisely stated course objectives; (3) devote some lecture time to setup and solution of problems with emphasis on models and strategy; (4) use a pedagogically advanced textbook; (5) relate abstract concepts to everyday concrete phenomena as achieved in demonstrations, ‘‘The Mechanical Universe’’ videotapes, and labs of the Socratic dialogue-inducing (SDI) type; (6) teach the course with much smaller lecture sections and with greatly increased faculty–student interaction.
Comment on Cohen’s article on the Chernobyl disaster
Authors: Franta Jaroslav
Published: March 2005

The amount of uranium enrichment needed to make a reactor critical is discussed. (AIP)
Experiment in time-average holographic interferometry for the undergraduate laboratory
Authors: Bahuguna R. D. , Western Arthur B. , Lee Sean
Published: March 2005

An experiment suitable for an undergraduate laboratory on time-average holography is described. The object analyzed is a rectangular bar driven at one end and supported at its geometric center by means of a vertical rod. The nodal point, as indicated by the brightest fringe, is found to be away from the geometric center. A simple analysis explains the observed results.
The apparent shape of a rapidly moving sphere
Authors: Suffern Kevin G.
Published: March 2005

Several articles have considered the apparent shape of a relativistic sphere. One interesting finding showed that, under certain conditions, the surface of the sphere may appear concave. This article concentrates on the case where the observer is at the origin and the sphere moves in the positive x direction with its center on the x axis. The sphere actually hits the observer, and one of the findings presented here is that for any speed v, 0<v≤c, part of the surface appears concave for some part of the motion along the x axis.
Resource Letter: GI-1 Gauge invariance
Authors: Cheng T. P. , Li Ling-Fong
Published: March 2005

Gauge symmetry has become one of the most basic concepts in the theoretical framework for understanding fundamental interactions: The quantum field theories of the strong, weak, and electromagnetic interactions are all gauge invariant; general relativity can also be viewed as a classical gauge theory. This Resource Letter is intended for nonspecialists who wish to study gauge theories and their applications to elementary particle physics. About half of our discussion is devoted to the general properties of gauge-invariant quantum field theories and half to their applications, from QED, QCD, and the Weinberg–Salam model to grand unification. The letter E after an item indicates elementary level or material of general interest to persons becoming informed in the field. The letter I, for intermediate level, indicates material of somewhat more specialized nature; and the letter A indicates rather specialized or advanced material. An asterisk (*) indicates those articles to be included in an accompanying Reprint Book.
Wormholes in spacetime and their use for interstellar travel: A tool for teaching general relativity
Authors: Morris Michael S. , Thorne Kip S.
Published: March 2005

Rapid interstellar travel by means of spacetime wormholes is described in a way that is useful for teaching elementary general relativity. The description touches base with Carl Sagan’s novel Contact, which, unlike most science fiction novels, treats such travel in a manner that accords with the best 1986 knowledge of the laws of physics. Many objections are given against the use of black holes or Schwarzschild wormholes for rapid interstellar travel. A new class of solutions of the Einstein field equations is presented, which describe wormholes that, in principle, could be traversed by human beings. It is essential in these solutions that the wormhole possess a throat at which there is no horizon; and this property, together with the Einstein field equations, places an extreme constraint on the material that generates the wormhole’s spacetime curvature: In the wormhole’s throat that material must possess a radial tension τ0 with the enormous magnitude τ0∼ (pressure at the center of the most massive of neutron stars)×(20 km)2/(circumference of throat)2. Moreover, this tension must exceed the material’s density of mass-energy, ρ0c2. No known material has this τ0>ρ0c2 property, and such material would violate all the ‘‘energy conditions’’ that underlie some deeply cherished theorems in general relativity. However, it is not possible today to rule out firmly the existence of such material; and quantum field theory gives tantalizing hints that such material might, in fact, be possible.
A squeezed-state primer
Authors: Henry Richard W. , Glotzer Sharon C.
Published: March 2005

Using only elementary quantum-mechanical concepts, the statistical properties of various harmonic oscillator states that are linear superpositions of its energy eigenfunctions are described. These superpositions include coherent states and squeezed (or two-photon coherent) states. The resulting Gaussian, minimum-uncertainty wave packets are shown to oscillate back and forth for both coherent and squeezed states, but with an oscillating ‘‘width’’ for the squeezed states. Also examined are the principles underlying the production of squeezed electromagnetic waves via parametric amplification or four-wave mixing, their measurement by homodyne detection, and the connection between squeezing and non-Poissonian counting statistics.
Supersymmetry, shape invariance, and exactly solvable potentials
Authors: Dutt Ranabir , Khare Avinash , Sukhatme Uday P.
Published: March 2005

It is well known that the harmonic oscillator potential can be solved by using raising and lowering operators. This operator method can be generalized with the help of supersymmetry and the concept of ‘‘shape-invariant’’ potentials. This generalization allows one to calculate the energy eigenvalues and eigenfunctions of essentially all known exactly solvable potentials in a simple and elegant manner.
The politics of the meter stick
Authors: Heilbron J. L.
Published: March 2005

The reform of weights and measures during the French Revolution corrected one of the heaviest abuses of the Ancien Régime. The form of the reform—the metric system—derived in part from the rhetoric of Enlightenment philosophers and in part from the agenda of Parisian academicians. The system did not appeal to the people for whom it was supposedly designed. This article outlines this story and draws a brief lesson for our times.
On combining the Bernoulli and Poiseuille equation—A plea to authors of college physics texts
Authors: Synolakis Costas Emmanuel , Badeer Henry S.
Published: March 2005

A generalized form of the Bernoulli equation is presented. The assumptions involved in the derivation and its limitations are identified. The usual form of the Bernoulli and Poiseuille equations is shown to be a special case of this generalized equation. Various implications in the teaching of college physics are discussed.
Evolution of the modern photon
Authors: Kidd Richard , Ardini James , Anton Anatol
Published: March 2005

The term ‘‘photon’’ represents at least four distinct models and carries different connotations for students and for practicing physicists. This reflects the long and complex historical evolution of the concept and its association with the largely misinterpreted principle of duality. The unsatisfactory nature of the corpuscular and wave packet models is discussed, and the pedagogical desirability urged of replacing them with a semiclassical approach in elementary presentations. Derivations of the photoelectric (PE) effect without photons are cited and a vector analysis is given, demonstrating that the PE effect cannot be considered as simply the interaction of a photon and electron.
Baseball–bat collisions and the resulting trajectories of spinning balls
Authors: Watts Robert G. , Baroni Steven
Published: March 2005

The collision between a baseball and a bat has been analyzed using the classical theory of rigid body collisions. Also computed are the ranges of batted balls for a variety of launch angles and rotation rates, accounting for both drag and lift forces. If the coefficient of friction is not too small, the batter can give the ball fairly large backspin without fouling it off by swinging under the ball by as much as 1 to 2.5 cm. The increased range resulting from backspin is large, of the order of several tens of meters. The effect of the weather on the ranges has been analyzed briefly and it is found that under extreme conditions it can be surprisingly large.
Relativistic buoyancy
Authors: Supplee James M.
Published: March 2005

Because of relativistic length concentration, the buoyant force on a submerged projectile depends on its velocity. How this affects the motion of a submerged projectile is considered here. The case considered is highly idealized, yielding a tractable conceptual problem in relativity.
Eastern mysticism and the alleged parallels with physics
Authors: Scerri Eric R.
Published: March 2005

The claims for parallels between modern physics and Eastern mysticism are critically examined in view of their possible educational impact. The overall nature, as well as specific examples of parallelism, are considered in order to emphasize the problems faced in trying to maintain the validity of such claims. The role of analogies within physics is briefly discussed.
The Feynman inverse sprinkler problem: A demonstration and quantitative analysis
Authors: Berg Richard E. , Collier Michael R.
Published: March 2005

The results of an experiment designed to illustrate the effects of hooking a common lawn sprinkler to a suction, rather than to a pressure, source are presented. The inverse sprinkler moves in a direction opposite to that of the normal sprinkler with an angular momentum opposite to and approximately equal to that of the fluid in the sprinkler arms. Recent experiments designed to test this effect may have produced a null result because of friction associated with the systems. A demonstration constructed at the University of Maryland, College Park, that avoids this problem is discussed.
A wave-packet description of the motion of a charged particle in a uniform magnetic field
Authors: Zimmermann W.
Published: March 2005

A discussion is given of the construction of wave packets to describe the motion of a charged particle in a uniform magnetic field. Examples are given of the construction of wave packets from eigenstates of the Hamiltonian for both the Landau gauge in Cartesian coordinates and the cylindrically symmetric gauge in cylindrical coordinates.
Spatial geometry in a uniformly accelerating reference frame
Authors: Desloge Edward A.
Published: March 2005

The meaning of spatial geometry in a reference frame is carefully analyzed. It is shown that in a uniformly accelerating reference frame spatial geometry is Euclidean if distance is measured with measuring rods and non-Euclidean if distance is measured with light signals. The distance function and the square of the line element associated with each mode of measurement are obtained.
Relativity and aberration
Authors: Phipps Thomas E.
Published: March 2005

Certain physics textbooks convey a false impression that the stellar aberration angle depends on the relative velocity of the light source and observer. Counterfactual consequences are deduced from such an assumption and a more acceptable alternative, consistent with the relativity principle and with some other textbooks, is discussed.
Footnote to the quantum mechanical virial theorem
Authors: Crawford Frank S.
Published: March 2005

The quantum mechanical virial theorem is extended to a time dependent superposition of stationary bound states. (AIP)
Sticks and stones: A guide to structurally dynamic cellular automata
Authors: Halpern Paul
Published: March 2005

A nontraditional cellular automaton model has been proposed in which the lattice of the automaton is a dynamical element. This model will be illustrated, and applications will be discussed.
Maximum power point characteristics of heat engines as a general thermodynamic problem
Authors: Gordon J. M.
Published: March 2005

The average power versus efficiency characteristics of common selected engine cycles and a few irreversibility mechanisms are analyzed toward assessing the universal nature of assorted equations that have been derived recently for efficiency at maximum power point. Most results derived to date are shown to be special cases of one general thermodynamic problem of linearly irreversible heat engines, which explains the unifying basis for seemingly fortuitous similarities in their maximum power point characteristics.
The Terrell effect
Authors: Terrell James
Published: March 2005

The author clarifys his work on the appearance of objects in special relativity. (AIP)
Analysis of Genes Induced by Sendai Virus Infection of Mutant Cell Lines Reveals Essential Roles of Interferon Regulatory Factor 3, NF-κB, and Interferon but Not Toll-Like Receptor 3
Authors: Elco Christopher P. , Guenther Jeanna M. , Williams Bryan R. G. , Sen Ganes C.
Published: March 2005

Sendai virus (SeV) infection causes the transcriptional induction of many cellular genes that are also induced by interferon (IFN) or double-stranded RNA (dsRNA). We took advantage of various mutant cell lines to investigate the putative roles of the components of the IFN and dsRNA signaling pathways in the induction of those genes by SeV. Profiling the patterns of gene expression in SeV-infected cells demonstrated that Toll-like receptor 3, although essential for gene induction by dsRNA, was dispensable for gene induction by SeV. In contrast, Jak1, which mediates IFN signaling, was required for the induction of a small subset of genes by SeV. NF-κB and interferon regulatory factor 3 (IRF-3), the two major transcription factors activated by virus infection, were essential for the induction of two sets of genes by SeV. As expected, some of the IRF-3-dependent genes, such as ISG56, were more strongly induced by SeV in IRF-3-overexpressing cells. Surprisingly, in those cells, a number of NF-κB-dependent genes, such as the A20 gene, were induced poorly. Using a series of cell lines expressing increasing levels of IRF-3, we demonstrated that the degree of induction of A20 mRNA, upon SeV infection, was inversely proportional to the cellular level of IRF-3, whereas that of ISG56 mRNA was directly proportional. Thus, IRF-3 can suppress the expression of NF-κB-dependent genes in SeV-infected cells.