bluuebunny/crossref_metadata_2025 huggingface dataset:
Location of micropyles and early embryonic development of the two‐spotted cricket Gryllus bimaculatus (Insecta, Orthoptera)
Authors: Sarashina Isao , Mito Taro , Saito Michiko , Uneme Hiroyuki , Miyawaki Katsuyuki , Shinmyo Yohei , Ohuchi Hideyo , Noji Sumihare
Published: March 2005

Early embryogenesis of the two‐spotted cricket Gryllus bimaculatus was examined by scanning electron microscopy and several fluorescence staining methods, with special reference to these four issues: (i) the location of micropyles; (ii) the transfer of the female pronucleus following meiosis; (iii) the timing of cellularization; and (iv) the process of the germ primordium formation. Between two and four micropyles lie in the mid‐ventral region of the egg. The egg nucleus is at the mid‐dorsal periphery of the new laid egg, and meiosis resumes and is completed there. The female pronucleus moves to the mid‐ventral side, and fertilization occurs there. Energid starts to proliferate and migrates to the periphery of the egg, initiating blastoderm formation. Actin caps surround each superficial nucleus. Cellularization occurs during the blastoderm stage. At a late blastoderm stage, nuclei aggregate in both the posterolateral patch‐like regions of the egg to form a germ primordium. The germ primordium looks like a pair of dumbbells. Both the patches shift towards the ventral side and fuse into a germ primordium. The germ primordium contracts to produce a clearly delineated germ band. Observations on distribution patterns of F‐actin indicate that, all through the process, the germ primordium retains that unity, and is not separated into two parts.
Time, Money and Job Spillover: How Parents’ Jobs Affect Young People
Authors: Pocock Barbara , Clarke Jane
Published: March 2005

This paper examines the perspectives of young people about their parents’ paid and unpaid work, their preferences for time or money through more parental work, and their views about how their parents’ jobs affect them. It analyses qualitative empirical data collected in Australia in late 2003, by means of focus groups among 10-12 and 16-18- year-old males and females in urban and rural locations in two Australian states, in both high and low socioeconomic areas. It finds that more Australian children are looking for more time from parents than more money from more parental work, though this varies by income level, location and parental hours. This preference for ‘time over more money’ is consistent in single- and dual-earner couple households as well as sole parent/earner households. Children are acute observers of parents and their jobs. Both positive and negative spillovers are widely observed. Negative spillovers from long or unsocial hours are especially marked, reinforcing other findings in support of policy interventions to contain long or unsocial hours.
The United States and the Control of World Oil
Authors: Bromley Simon
Published: March 2005

To what extent is a drive to appropriate the world's oil a driving force behind American foreign policy? This paper argues that rather than viewing US foreign policy as driven by the expansionary forces of US oil companies seeking new reserves and markets, or by rising concern about levels of import dependence, it is more illuminating to ask how the broader nature of American geopolitics shapes policies towards international oil. The United States does seek to exercise a degree of influence over world oil second to none, but the form of that influence is very ambiguous and very different from the kinds of control over raw materials traditionally associated with imperial powers.
The Fate of Firms: Explaining Mergers and Bankruptcies
Authors: Bergström Clas , Eisenberg Theodore , Sundgren Stefan , Wells Martin T.
Published: March 2005

Using a uniquely complete data set of more than 50,000 observations of approximately 16,000 corporations, we test theories that seek to explain which firms become merger targets and which firms go bankrupt. We find that merger activity is much greater during prosperous periods than during recessions. In bad economic times, firms in industries with high bankruptcy rates are less likely to file for bankruptcy than they are in better years, supporting the market illiquidity arguments made by Shleifer and Vishny (1992). At the firm level, we find that, among poorly performing firms, the likelihood of merger increases with poorer performance, but among better performing firms, the relation is reversed and chances of merger increase with better performance. Such a changing relation has not been detected in prior merger studies. We also find that low‐growth, resource‐rich firms are prime acquisition targets and that firms’ debt capacity relates negatively to the likelihood of a merger. Debt‐related variables, leverage and secured debt, play an especially prominent role in distinguishing between which firms merge and which firms go bankrupt.
Polymorphisms of the upstream regulatory region of the major histocompatibility complex DRB genes in domestic horses
Authors: Díaz S. , Giovambattista G. , Peral‐García P.
Published: March 2005

Sequence information was obtained on the variation of the ELA‐DRB upstream regulatory region (URR) after polymerase chain reaction‐single strand conformation polymorphism (PCR‐SSCP) cloning and sequencing of ≈ 220 bp upstream of the first exon of horse DRB genes. The sequence of the proximal URR of equine DRB is composed of highly conserved sequence motifs, showing the presence of the W, X, Y, CAAT and TATA conserved boxes of major histocompatibility complex (MHC) class II promoters. Five different polymorphic horse DRB promoter sequences were detected in five horse breeds. The results demonstrate the existence of polymorphism in the nucleotide sequences of the ELA‐DRB URR, located in the functionally important conserved consensus sequences, the X2 box, the Y box and the TATA box, while conservation were observed in X1 and CAAT boxes. The nucleotide diversity among horse URRs was intermediate between that seen within human and mouse DRB promoters, suggesting the existence of another important source of variability in ELA‐DRB genes. In addition, phylogenetic comparisons, identity analysis and sequence organization suggested that the reported sequences would correspond to an expressed ELA‐DRB locus. However, further information about the functional significance of these promoter polymorphisms will probably be acquired through expression studies on the different sequences.
Elliptical orbits in quantum mechanics
Authors: Snider Dale R.
Published: March 2005

Solutions are found to Schrödinger’s equation with an inverse-r potential which well approximate the classical solution, an elliptical orbit.
A criterion for stationary states in quantum mechanics
Authors: Aub Martin R. , Niederreiter Harald
Published: March 2005

We show a criterion for a vector φ in a complex inner product space V to be an eigenvector of a Hermitian operator A in V in terms of the values of inner products 〈Xφ,Aφ〉 for Hermitian operators X. This result can be applied to the characterization of stationary states in quantum mechanics.
Pseudowork and real work
Authors: Sherwood Bruce Arne
Published: March 2005

In teaching mechanics, we should more clearly distinguish between an integral of Newton’s second law and the energy equation. This leads to greater clarity in the notions of system, work, and energy. A reorientation of the treatment of work and energy would not only provide benefits in the mechanics course but would also produce better connections between the mechanics and thermodynamics courses.
The Stark effect on an excited hydrogen atom
Authors: Barratt C.
Published: March 2005

The method of degenerate perturbation theory is used to study the dipolar nature of an excited hydrogen atom in an external electric field. The dependence of the atoms perturbed energy levels on the principal and magnetic quantum numbers, n and m, is investigated, along with the perturbed wave functions.
Time-dependent shifts in the Schrödinger equation
Authors: Venanzi Thomas J.
Published: March 2005

A formalism incorporating a time-dependent shift is presented as a means of solving time-dependent problems. When perturbation techniques are applied in order to extract the various nth-order components of the wave function, equations result in which the time-dependent shifts play the role of ‘‘energy terms.’’ When the static limit is taken, the resulting perturbation equations reduce to the time-independent equations with the appropriate energy terms.
Local stability: An elementary demonstration and discussion
Authors: Gomes M. A. F. , Savage Wm. R. , Gomes Anderson S. L.
Published: March 2005

We discuss the behavior of a simple, easy to construct, mechanical oscillator subject to local stability. The analysis stresses the physical and intuitive aspects of the problem introducing the concepts of soft modes, order parameter, exchange of stability, and response function used in condensed matter physics.
Running backwards the Mermin device: Causality in EPR correlations
Authors: De Beauregard O. Costa
Published: March 2005

Time reversal of Mermin’s reasoning is exemplified in the case of spin-0 photon pairs issuing from cascade transitions, or converging to produce an ‘‘anticascade’’ or ‘‘echelon absorption.’’ Nonseparability of the two distant measurements (respectively, preparations), as tied by propagation of the two particles, is thus relayed either in the common past preparation or future measurement, so that the causality concept turns out to be arrowless at the quantal level. When expressed in the relativistic S matrix formalism, it is CPT invariant.
Rutherford scattering in two dimensions
Authors: Barton G.
Published: March 2005

Parabolic coordinates allow Schrödinger’s equation to be solved analytically for a particle confined to the xy plane and incident with velocity v on a potential C/r. In sharp contrast to the three-dimensional case, the cross section assumes its classical value only in the rationally foreseeable classical regime ‖C‖/ℏv≫1, but not otherwise; and in this low-velocity regime the enhancement factor (probability density at the origin) for an attractive potential tends to 2 (independently of the value of ‖C‖), instead of diverging as in three dimensions like some inverse power of v.
The Si photodiode: An inexpensive though high-performing α detector
Authors: Dousse J.-C. , Rhême Ch.
Published: March 2005

A common photodiode can be used as a good performing α detector. The energy response is quite linear. A good resolution and efficiency can be obtained. The main advantage, however, is the very low price. The useful area is limited to a few mm2. A charge sensitive preamplifier has been especially designed.
A constant force generator for the demonstration of Newton’s second law
Authors: Herrmann F. , Mühlbayer T.
Published: March 2005

A constant force generator is very helpful in demonstrating Newton’s second law in the classroom. A device is described which avoids the disadvantages of setups currently used. It is based upon the induction of eddy currents. It is easy to handle and can be self-made.
Dynamics of nonlinear dissipative oscillators
Authors: Hanggi Peter , Riseborough Peter
Published: March 2005

In this paper we review some of the important concepts and theorems dealing with nonlinear dissipative oscillators in the presence of random and deterministic periodic forces, with particular reference to the Van der Pol oscillator. We display simple techniques such as the Krylov–Bogoliubov averaging method and generalize this method to random oscillator systems exhibiting new noise-induced phenomena
Illustrative examples of the symplectic group
Authors: Kim Y. S. , Noz Marilyn E.
Published: March 2005

Simple illustrative examples are given for understanding the symplectic group. Transformation properties of the Sp(2) group are discussed in terms of the two-dimensional geometry of circles and ellipses, two-by-two matrices, and in terms of a group-theoretical language similar to that of the Pauli spin matrices. The isomorphism between the Sp(2) and SO(2,1) groups is discussed in detail. It is noted that this isomorphism is similar to that between the SU(2) and rotation groups. Simple illustrative physcial examples are given also for using the symplectic group in nuclear physics, statistical mechanics, and in high-energy physics.
Generating functions in physics
Authors: Schwalm William A. , Schwalm Mizuho K.
Published: March 2005

The generating function concept is one which underlies several of the methods of theoretical physics including partition functions, Green functions, and Fourier series expansions. We illustrate both the essential operational properties which characterize the method and its utility as a problem-solving procedure with three examples from undergraduate physics. The first is a dynamical problem concerning a linear lattice of springs and weights while the other two are stochastic problems from nuclear physics.
A simple, accurate alternative to the minimum deviation method of determining the refractive index of liquids
Authors: Chandra B. P. , Bhaiya S. C.
Published: March 2005

A fixed angle of incidence method, which is an alternative to the minimum deviation method of determining the refractive index of liquid, is used. This method is very simple as compared to others. The value of refractive index determined by this method is nearly the same as that determined by other methods.
Relativistic addition of velocities directly from the constancy of the velocity of light
Authors: Mermin N. David
Published: March 2005

The relativistic addition law for parallel velocities is derived as an immediate consequence of the constancy of the velocity of light, without making use of Lorentz transformations, and without appealing to the phenomena of length contraction, time dilation, or the relativity of simultaneity.
Generalized prism dispersion theory
Authors: Duarte F. J. , Piper J. A.
Published: March 2005

The case of dispersion in multiple-prism arrays is considered. A general expression is derived, using geometrical optics, for the dispersion of multiple-prism assemblies arranged either in the additive or the compensating-pair configurations.
Bound states and scattering from a one-dimensional hydrogen atom at a boundary
Authors: Lapidus I.Richard
Published: March 2005

The bound-state energy of a one-dimensional hydrogen atom with a δ-function potential is modified by the presence of a nearby boundary. The distortion of the wave function raises the energy of the atom. If the atom is sufficiently close to a high barrier the system does not have a bound state. Scattering from a δ-function potential is also modified by the presence of the boundary. This simple example, which can be solved exactly, may help to provide insight into more realistic interactions between single atoms and surfaces.
A derivation of the classical monopole energy loss from angular momentum conservation
Authors: Trefil J. S.
Published: March 2005

It is shown that the classical energy loss for a magnetic monopole in matter can be derived completely from considerations of angular momentum conservation, without recourse to the usual dynamical calculations. This derivation provides insight into the role of the angular momentum of the electromagnetic field in problems involving magnetic monopoles.
Correct use of Maxwell stress equations for electric and magnetic fields
Authors: Jefimenko Oleg D.
Published: March 2005

By neglecting edge or end effects in electric or magnetic systems and by using certain other conventional approximation techniques one may inadvertently create conditions that contradict some of the assumptions upon which Maxwell stress tensors and stress integrals are derived. Correction terms must then be added to the stress equations to make them usable. The nature of these correction terms is discussed and several illustrative examples are given.
Comment on ‘‘quark confinement and the Dirac equation’’
Authors: Olsson M. G.
Published: March 2005

The effect of the ‘‘Klein paradox’’ on the quarkonium energy levels is discussed. (AIP)
Experiments on magnetic repulsion
Authors: Defrancesco S. , Zanetti V.
Published: March 2005

Three different experiments on magnetic repulsion are discussed. Elementary theory and a very simple and low-cost setup are needed. The experiments can be used by students as a project or by the teacher as a class demonstration.
Refraction through a prism
Authors: Feldman Albert
Published: March 2005

A simple formula is derived which describes the refraction of light through a prism for an arbitrary angle of incidence. This formula can be represented by an ellipse whereby the minimum deviation condition and the transmission cutoff due to total internal reflection have a simple geometrical interpretation.
Diffraction pattern intensity measurements in the introductory college physics laboratory using microcomputers
Authors: Soundranayagam R. , Ramayya A. V. , Cleeman L. , Riecken Mark , Fuson Nelson , Springer John
Published: March 2005

Measurement of the intensity variations in a single slit diffraction pattern formed by a laser beam is made by means of a photoresistor detector interfaced with an Apple II-plus microcomputer through the paddle (game controller) connection. The computer programs, written in BASIC and assembly language, enable the student to (1) determine quantitatively the intensity of the maxima and minima; (2) see the intensity pattern as the data is acquired; (3) obtain a hard copy of the intensity plot observed on the screen monitor; and (4) compare the experimental and theoretical intensity patterns.
Harmonically forced Cavendish balance
Authors: Shaw Glenn E.
Published: March 2005

The Cavendish balance, when driven into resonance by swinging the external mass, provides an interesting corridor demonstration of gravity. It is, moreover, a suitable means of demonstrating properties of driven harmonic systems.
Inexpensive sources and detectors for microwave demonstrations
Authors: Beers Yardley
Published: March 2005

This report describes microwave apparatus that has been constructed from materials available from local stores for about $25, using simple hand tools. The source consists of an MRF 901 transistor in an ‘‘ultra audion’’ circuit at 13-cm wavelength, and it includes a modulator for audio frequency tone. The detector consists of a hot carrier diode, an audio frequency amplifier, and a loudspeaker. The construction is simplified by using direct coupling to the antenna. Experiments using inexpensive accessory apparatus for measuring the wavelength and for demonstrating various phenomena in microwave optics are described also.
Comments on virial theorems for bounded systems
Authors: Swenson Robert J.
Published: March 2005

A generalization of a virial theorem for a bounded system is given. Also a detailed discussion starting from a virial theorem of the derivation of a microscopic expression of the stress tensor is presented. Two applications are briefly indicated.
Neutron propagation in moving matter
Authors: Peres Asher
Published: March 2005

Contrary to photons, slow neutrons are not dragged by moving matter (there is no Fresnel–Fizeau effect). This is proved in two different ways: (a) from the Lorentz transformation formulas, which have different limits for relativistic and nonrelativistic particles, and (b) by directly calculating the coherent scattering of slow neutrons by moving nuclei.
Resonant growth in simple systems
Authors: Gordon R. A.
Published: March 2005

It is shown that a simple extension of the usual sinusoidal trial solution in elementary textbooks to include a time-dependent amplitude of oscillation—a special case of the general Kryloff–Bogoliuboff solution—makes it possible to give a simple unified treatment of resonant growth in simple systems at a level readily accessible to beginning physics students.
Chemical clocks: Experimental and theoretical models of nonlinear behavior
Authors: Mielczarek Eugenie V. , Turner Jack S. , Leiter Darryl , Davis Linda
Published: March 2005

The phenomena of limit cycles, bifurcation, and hard and soft excitation arise from solutions to nonlinear differential equations. This paper summarizes the properties of nonlinear differential equations and these related observable phenomena. Current related research in biological and biochemical systems are surveyed. Easily duplicated chemical systems, variations of the Zhabotinskii reagent, are described which experimentally demonstrate the phenomena.
Work and heat in the light of (thermal and laser) light
Authors: Laufer Gabriel
Published: March 2005

The definitions of work and heat and the relation between these quantities and energy is reviewed. Three expositions are considered and their validity for thermodynamical nonequilibrium processes is examined by applying them to hypothetical experiments where light is made to interact with absorbing systems. The Carathéodory exposition in contrast to the other expositions properly classifies laser interaction with absorbing matter as a work interaction.
The Crane Foucault pendulum: An exercise in action-angle variable perturbation theory
Authors: Hecht K. T.
Published: March 2005

The short Foucault pendulum recently constructed by H. R. Crane, with a magnetic force field to compensate the intrinsic precession associated with small ellipticity, makes a natural exercise for the classical Poincaré perturbation theory.
An analysis of the rotational stability of the layout back somersault
Authors: Lightsey Paul A.
Published: March 2005

A numerical solution of Euler’s equations for a freely rotating asymmetrical top is applied to an analysis of the relative stability of rotation of a gymnast performing a layout back somersault with and without a full twist. The results suggest that successful performance of the stunt without a full twist has less tolerance for error in the initial rotational velocity than does the stunt with a full twist. This analysis provides an interesting illustration that can be used in advanced undergraduate mechanics courses. The analysis also demonstrates the potential for increased utilization of computers and numerical techniques in the undergraduate curriculum.
The computer in lab—A/D and D/A conversion
Authors: Nicklin R. C. , Rafert Bruce
Published: March 2005

This article gives a brief introduction to analog-to-digital and digital, to-analog conversion. Circuit details and programs are presented for using the AD7574 and AD558 converters with the KIM-1 computer. The resulting interface is easy to build, easy to use, and inexpensive. One application, which converts any triggered scope into a storage scope, is to capture and digitize a waveform and then display the waveform on an oscilloscope.
Elementary particle resonances from a semiclassical perspective
Authors: Arndt R. A. , Roper L. D.
Published: March 2005

The motion of a particle in a short-range attractive potential, when treated classically but with quantized angular momentum l, can give rise to a finite series of particle ‘‘resonances.’’ When this picture is applied to the π–N P33 resonance it is discovered that a physically reasonable Yukawa potential could produce the effect and that no resonances of higher l value would exist.
Coriolis acceleration: A laboratory experiment
Authors: Martin Adriana M. , Mariani D. F.
Published: March 2005

Using a common laboratory apparatus and a spark timer, consecutive positions of a moving object with respect to time in a rotating frame of reference can be obtained. Experimental data are analyzed by means of a simple graphic method, directly based on the vectorial definitions of mean velocity and acceleration. Thus the Coriolis acceleration vector can be directly obtained on every point of the trajectory and the relation for the Coriolis acceleration can be clearly verified.
Self-catalysis in solid hydrogen—A computer simulation
Authors: Perrell L. R. , Haase D. G.
Published: March 2005

We describe a Monte Carlo simulation of self-catalysis of orthohydrogen molecules in solid hydrogen in one- and two-dimensional lattices at low temperatures in the absence of molecular diffusion. The problem is useful for illustrating the importance of lattice geometry and near neighbor relationships in such calculations. The simulations were performed on a small computer and may be of use in teaching Monte Carlo techniques.
Temperature measured by a uniformly accelerated observer
Authors: Donoghue John F. , Holstein Barry R.
Published: March 2005

By use of elementary quantum-mechanical arguments we demonstrate how an observer with uniform acceleration a perceives himself as immersed in a heat bath of temperature kT=aℏ/2πc.
Small black holes: Ionization tracks and range
Authors: Greenstein George , Burns Jack O.
Published: March 2005

The interaction of black holes of very low mass with matter is better described by methods borrowed from cosmic-ray physics than conventional astrophysics. We discuss their ionization tracks and range in terms which emphasize both the similarities and the differences between the electrostatic and gravitational interactions.
Simplified derivation of the Hamilton–Jacobi equation
Authors: Yan C. C.
Published: March 2005

A simple method based on equations of motion is proposed to derive the Hamilton–Jacobi equation for some simple classical mechanical systems.
Dispersion relations for waves on liquid surfaces
Authors: Klemens P. G.
Published: March 2005

The dispersion relations for waves on liquid surfaces are derived in terms of the Lagrange equations of an oscillator, with gravity and surface tension as restoring mechanisms. This derivation only requires the continuity equation and the assumption of irrotational flow, but not the Bernoulli equation.
Compton scattering and Heisenberg’s microscope revisited
Authors: Williams Brian G.
Published: March 2005

Compton scattering figures prominently in the introductory chapters of textbooks on quantum mechanics as providing evidence for the ‘‘particulate’’ nature of light. It also arises in discussions of ‘‘Heisenberg’s microscope,’’ in which it is shown that attempts to measure the position and the momentum of an electron simultaneously are governed by the uncertainty principle. However, recent developments in Compton scattering have not yet found their way into the textbooks. In this paper we review the history of the Compton effect and describe briefly some of the modern developments in x-ray and electron Compton scattering and their application to the study of electron momentum densities which we believe to have a pedagogical value. Finally, we return to Heisenberg’s microscope, and show how it has now become a reality. A complete analysis for all scattering angles depends crucially on the different expressions for the resolution and the depth of focus of the microscope.
Electrostatic images by multipole expansion
Authors: Marin J. L. , Rosas R.
Published: March 2005

We propose a simple method for solving some electrostatic problems normally treated by images. The method is based on the multipole expansion of the electrostatic potential due to both real and image charges. The magnitude and the location of the image charges are found by imposing the proper boundary conditions. Some typical problems with spherical and with spheroidal symmetries are worked out explicitly.
An electrical model for the Korteweg–de Vries equation
Authors: Giambò S. , Pantano P. , Tucci P.
Published: March 2005

In this paper we describe an electrical network, whose current evolution does agree with a Korteweg–de Vries equation. Our aim is to prepare pupils to understand the analytical aspects of nonlinear and dispersive phenomena, which very often are neglected in high-school and graduate textbooks. Some historical remarks introduce the topic and a bibliography is provided.
The role of induced emf’s in simple circuits
Authors: Peters P. C.
Published: March 2005

The role of induced emf’s in circuits is explored using batteries and bulbs. This technique both uncovers students’ misconceptions about emf’s and provides a route towards better understanding of the nature of induced emf’s. The examples illustrate, at a more elementary level, the effects discussed in recent articles by Reif and Romer.
Incoherent radiation in an n-dimensional space
Authors: Giddings Steven
Published: March 2005

The standard freshman kinetic theory of pressure would indicate the equation of state p=μ/n for incoherent radiation in an n-dimensional space. The validity of this can be demonstrated by two different methods—one using Maxwell’s equations to show the vanishing of the averaged trace of the stress energy tensor, the other following a statistical mechanical derivation. One use of the result is in the study of cosmological solutions to Einstein’s equations in n dimensions.
On the function and the probable origin of Ptolemy’s equant
Authors: Evans James
Published: March 2005

We examine the roles of the equant point and the eccentric deferent circle in Ptolemy’s planetary theory. The necessity of these features of the model is demonstrated empirically by a study of the retrograde arcs of Mars. Finally, these results are used, together with available historical evidence, to suggest the line of investigation that probably led Ptolemy to his discovery of the equant.
Three perspectives on Schrödinger’s cat
Authors: Loeser J. G.
Published: March 2005

The resolutions to the paradox of Schrödinger’s cat engendered by three major perspectives on quantum mechanics—quantum logic, the many worlds interpretation, and the Copenhagen interpretation—are discussed. The core of each perspective is revealed in the process. Each resolution to Schrödinger’s cat has a counterpart which solves the logical paradox known as the unexpected hanging. The rather striking parallels serve to emphasize several points. First, the quantum paradox is an epistemological and not a physical one. Second, the three interpretations mentioned, unlike some others, are faithful to this understanding. And third, the pitfalls in these two paradoxes have a somewhat universal character.
Static method for determining the R value of thermal insulation
Authors: Budzinski Walter V. , Neeson John F.
Published: March 2005

A steady-state technique for finding the thermal resistance of rigid thermal insulation is discussed. The method, which is suitable for use in the general physics laboratory, can be understood in terms of a simple electrical analogy.
An upper division student laboratory experiment which measures the velocity dispersion and nonlinear properties of gravitational surface waves in water
Authors: Wu Junru , Rudnick Isadore
Published: March 2005

An undergraduate experiment designed to study the dispersion relation and nonlinearity of surface water waves in a trough is discussed. For small amplitudes a resonance technique is used to determine the wave velocity at the frequencies of the lowest modes of the trough. For the finite amplitude case, there is subharmonic nonlinear response for the plane wave mode propagating along the trough’s length as well as waves which reflect from the trough’s sides.
Fluctuations in a non-Maxwellian gas
Authors: McFee Richard
Published: March 2005

The velocity distribution of a noble gas in a very strong magnetic field has been shown to be non-Maxwellian. It is assumed here that a torsional suspension is immersed in such a gas. The average potential and kinetic energies of the resultant fluctuation are computed using Langevin’s method. They are found to be (kT/2), notwithstanding the reduced population of molecules at higher speeds.
Physics of the critical magnetic field in type-II superconductors
Authors: Dalven Richard
Published: March 2005

This paper is an introductory tutorial discussion of the physics of the critical magnetic field in type-II superconductors. The emphasis is on the solid-state physics factors affecting the magnitude of the critical field. Examples are given from current research.
Excitation of a composite structure by collisions
Authors: Newby Neal D.
Published: March 2005

A simple model is employed to study the excitation of a composite structure by collisions. The composite structure is a diatomic ‘‘molecule’’ composed of two equal point masses joined by a Hooke’s law spring of constant, k1. This structure, in an unexcited state, makes a one-dimensional head-on collision with a fixed wall. The interaction with the wall is mediated by a second Hooke’s law spring of constant, k2. After rebounding from the wall the diatom may be in an excited state. The excitation energy is calculated as a function of the hardness of the wall. An eigenvalue problem is solved which yields an infinite number of β’s (β=k1/k2) which leave the diatom unexcited. The phenomenon of ‘‘double hitting’’ — when a soft structure strikes a hard wall—is discussed. The maximum energy transfer into the internal mode is 23%. An air-track experiment is suggested to check the theoretical predictions.
Study of longitudinal mode structure of laser by optical spectrum analyzer
Authors: Bhatia K. S.
Published: March 2005

A senior level undergraduate experiment to study the axial modes of a laser using an optical spectrum analyzer is described. A brief introduction to the principle of Fabry–Perot interferometer and cavity resonances is given. Experimental arrangement to use the analyzer for display of modes, and as a narrow-band filter is discussed. The mode structure of a 0.3-m He–Ne laser is compared with a 1.85-m-long laser.
Outdoor demonstration experiment on the effect of soil albedo on soil surface temperature
Authors: Stigter C. J. , Mjungu Y. B. , Waryoba J. M.
Published: March 2005

An outdoor demonstration experiment is described that shows with simple means the influence of soil albedo on soil surface temperature. For that purpose a gradual but quasiconstant release of heat, generated by sudden exposure to solar radiation, is used at the surface.
Instability in automobile braking
Authors: Unruh W. G.
Published: March 2005

It is shown that the simplest theory for the behavior of automobile tires under braking leads to an instability which causes the car to spin around in cars whose rear wheels lock before the front.
Quantum mechanics in curved space
Authors: Donoghue John F. , Holstein Barry R.
Published: March 2005

The quantum mechanical wave equation for a particle in a Schwarzschild metric is derived using general relativity in the linearized approximation. The significance of the various terms in the effective Hamiltonian is discussed and shown to be associated with the post-Newtonian terms for the corresponding classical motion.
Assessing uncertainty in physical constants
Authors: Henrion Max , Fischhoff Baruch
Published: March 2005

Assessing the uncertainty due to possible systematic errors in a physical measurement unavoidably involves an element of subjective judgment. Examination of historical measurements and recommended values for the fundamental physical constants shows that the reported uncertainties have a consistent bias towards underestimating the actual errors. These findings are comparable to findings of persistent overconfidence in psychological research on the assessment of subjective probability distributions. Awareness of these biases could help in interpreting the precision of measurements, as well as provide a basis for improving the assessment of uncertainty in measurements.
An alternate derivation of relativistic momentum
Authors: Peters P. C.
Published: March 2005

An alternate derivation of the expression for relativistic momentum is given which does not rely on the symmetric glancing collision first introduced by Lewis and Tolman in 1909 and used by most authors today. The collision in the alternate derivation involves a non-head-on elastic collision of one body with an identical one initially at rest, in which the two bodies after the collision move symmetrically with respect to the initial axis of the collision. Newtonian momentum is found not to be conserved in this collision and the expression for relativistic momentum emerges when momentum conservation is imposed. In addition, kinetic energy conservation can be verified in the collision. Alternatively, the collision can be used to derive the expression for relativistic kinetic energy without resorting to a work-energy calculation. Some consequences of a totally inelastic collision between these two bodies are also explored.
Photons, neutrinos, and gauge transformations
Authors: Han D. , Kim Y. S. , Son D.
Published: March 2005

A unified description is presented for internal space-time symmetries of photons and neutrinos. Lorentz-boosted Dirac equation for a massive spin-1/2 particle is discussed in the Weyl representation. In the large-momentum/small-mass limit, the resulting large component of the Dirac spinor becomes invariant under transformations of the E(2)-like little group, and the small component is not invariant under the E(2)-like transformation. The gauge dependence of the photon four-potential can thus be derived from a direct product of the gauge-independent large component and the gauge-dependent small component.
A study of the phase transition of a ferromagnetic material
Authors: Fox J. N. , Gaggini N. , Eddy J. K.
Published: March 2005

The Curie temperature is determined from a resistivity measurement of a nickel sample, and the result is compared to that obtained from a method previously described in this Journal. In addition, the Curie temperature is determined for nickel and Monel 400 using a tunnel diode oscillator. Data analysis includes a method to calculate a critical point exponent.
Expediting the spinning top problem with a small amount of Clifford algebra
Authors: Snygg John
Published: March 2005

It is a argued that the problem of the spinning top is a good place to introduce some of the tools of Clifford algebra. Clifford algebra enables one to use a set of coordinates which are more intrinsic to the motion of the top than Euler angles. Furthermore today’s physics students are likely to encounter applications of Clifford algebra in a wide range of areas in the near future. No previous knowledge of Clifford algebra is required for the reader of this paper.
Experiment on fluid drag and viscosity with an oscillating sphere
Authors: Gupta V. K. , Shanker Gauri , Sharma N. K.
Published: March 2005

The fluid drag on a spherical ball performing oscillatory motion is studied by measuring the decay of amplitude of its free oscillations. For small amplitude of oscillations, the drag force is found to be a linear function of the instantaneous velocity of the ball. This is in agreement with theory. The linear relationship is used to determine the coefficient of viscosity of air. For oscillations involving large amplitude, the relationship between the drag force and the instantaneous velocity is nonlinear. An empirical relationship between the two, consistent with the experimental data, is established.
Microcomputers as digital electronics
Authors: Spencer C. D. , Seligmann P. F.
Published: March 2005

An instructional unit in which students build a microcomputer out of individual integrated circuits has been developed. It introduces the basic operations and design principles of computers, demonstrates the sequential cycles through which computers interface with external circuits, and provides, through machine code, insight into software at the most fundamental level. The computer consists of a Z-80 microprocessor plus memory, I/O, load/test, and applications circuits. A special breadboard system is used to facilitate construction and testing.
Extending special relativity via the perplex numbers
Authors: Fjelstad Paul
Published: March 2005

In analogy to the complex numbers z=x+iy, where the ‘‘imaginary’’ i is such that i2=−1, a system of perplex numbers z=x+hy is introduced, where the ‘‘hallucinatory’’ h is such that ‖h‖=−1. This system, invented by four freshmen at St. Olaf College, appears to have relevance in physics. In particular, it provides a natural way to extend the usual formalism of special relativity to the case ‖v‖>c. This is done by means of a velocity parameter φ, such that v=c tanh φ, where tanh is an extension of the ordinary hyperbolic tangent function. The fact that this extension has two different angles φ for each velocity v accounts for the different approaches in the literature to superluminal phenomena.
An experiment with two air tracks
Authors: Mita K. , Shirley W. , Chang C. R.
Published: March 2005

The analysis of a mechanical system with two air tracks is presented. The theoretical results are compared with the experimental data.
A variational principle and the classical and quantum mechanics of the damped harmonic oscillator
Authors: Herrera L. , Núñez L. , Patiño A. , Rago H.
Published: March 2005

A variational principle is presented, by means of which the equation of motion of the damped harmonic oscillator is found. Starting from this variational principle a systematic reformulation of the classical mechanics leads us to a Hamilton–Jacobi equation with an additional term, which is proportional to the action. The quantization of this Hamilton–Jacobi equation, following a method originally due to Schrödinger, gives the Langevin–Schrödinger equation.
An electric dipole in self-accelerated transverse motion
Authors: Cornish F. H. J.
Published: March 2005

It is shown that the equations of classical electrodynamics for an electric dipole possess a solution in which the dipole moves in self-sustained motion with constant proper acceleration in a direction perpendicular to its moment.
Brownian motion by light scattering revisited
Authors: Schumacher R. T.
Published: March 2005

This paper describes a modern implementation of a previously described student laboratory experiment that uses the time dependence of the intensity of light scattered from polystyrene spheres to obtain a value for Boltzmann’s constant. The experiment uses a single-board personal computer and a commercial microcomputer to do the experiment in the time domain by signal averaging. The theory of the experiment in the time domain, presented here, is relatively simple and direct, appropriate for an undergraduate laboratory experiment.
Solving classical mechanics problems by numerical integration of Hamilton’s equations
Authors: Stump Daniel R.
Published: March 2005

The numerical solution of classical mechanics problems is described. The method of solution is by application of a Runge–Kutta formula to Hamilton’s equations. Two problems, the elastic pendulum and the compound pendulum, are considered as examples. The use of numerical solutions in teaching mechanics is discussed.
The compressed hydrogen atom
Authors: Yngve Staffan
Published: March 2005

A simple model of a compressed hydrogen atom and an approximate formula for the energy shift due to compression are presented. The model is used in a theoretical lab, where the numerical energy shifts obtained from the approximate formula are compared with the results of an independent numerical calculation starting from the radial Schrödinger equation with boundary conditions.
Rolling and sliding resistive forces on balls moving on a flat surface
Authors: Witters J. , Duymelinck D.
Published: March 2005

A simple theory of rolling resistance is compared to experimental results on rolling billiard balls. The resistive force is shown to be independent of velocity for velocities smaller than 0.5 m/s. The sliding friction coefficient is determined by measuring the force needed to immobilize a skidding ball. The coefficient increases with increasing sliding velocity and approaches asymptotically the value of 0.21 which is quoted in the literature.
Classical and semiclassical diamagnetism: A critique of treatment in elementary texts
Authors: O’Dell S. L. , Zia R. K. P.
Published: March 2005

Diamagnetism does not exist as a classical phenomenon. Yet many elementary physics texts attempt to give ‘‘insight’’ into this subject using purely classical physics. We believe that these approaches mislead rather than help the students. On the other hand, just as semiclassical methods are employed in the chapters on quantum mechanics, these methods may be used to give an acceptable ‘‘explanation’’ of diamagnetism.
Using the Atwood machine to study Stokes’ law
Authors: Greenwood Margaret Stautberg , Fazio Frances , Russotto Marie , Wilkosz Aaron
Published: March 2005

A sphere, on one side of an Atwood machine, is immersed in glycerin and permitted to fall. We timed the descent and measured the terminal speed. We varied the mass m2 on the other side of the Atwood machine and plotted a graph of the terminal speed versus mass m2. Both the slope and the intercept yield the viscosity.
One-dimensional multiple scattering in quantum mechanics
Authors: Lessie Douglas , Spadaro Joseph
Published: March 2005

The formal theory of multiple scattering in quantum mechanics is adapted to one dimension and applied to the basic problem of scattering by a double delta-function potential. The multiple scattering method is shown to provide a much more powerful analysis than is obtained by either the one-dimensional partial wave approach or by the standard differential solution to the Schrödinger equation.
Why the classical–quantal dualism is still with us
Authors: Woo C. H.
Published: March 2005

Through a series of short steps we try to make clear why the classical–quantal dualism is still indispensable, despite the advances in our understanding of quantum physics.
On traveling round without feeling it and uncurving curves
Authors: Abramowicz M. A. , Lasota J. P.
Published: March 2005

We discuss an elementary example of how, in a strong gravitational field, the basic kinematical concepts of acceleration and circular motion seem to have paradoxical properties. This allows an insight into the physical significance of space-time curvature without the use of difficult mathematical formalism.
On the origin of magnetic dynamics
Authors: Bedford Donald , Krumm Peter
Published: March 2005

An examination of the origin of the torque on a magnetic dipole suspended above a line charge, as viewed from different frames of reference, provides insight into the nature of the dynamics of the magnetic interaction. In addition, it illustrates the remarkable unity of relativistic electromagnetic theory and points toward an intriguing interplay between geometry and dynamics.
Ultrasonic ranging module interface and air-track kinematics for the Apple IIe
Authors: Western Arthur B. , Crummett William P.
Published: March 2005

The polaroid ultrasound ranging system has been interfaced to an Apple IIe computer. Sufficient resolution is achieved to permit calculation of velocity and acceleration derivatives. The interface is described and the graphical results of several air-track experiments are presented.
Electromagnetic screening by metals
Authors: Fahy S. , Kittel Charles , Louie Steven G.
Published: March 2005

To dispel a widespread but erroneous belief among physicists that the penetration of ac magnetic fields into normal metals is determined by the usual skin depth δ alone, a simple analysis is presented of two problems in each of which a different length scale determines the effective screening. For a cylindrical can of thickness d≪δ and radius R≪λ, where λ is the wavelength, it is shown that the critical thickness for effective screening is dc =δ2/R. For a planar film with thickness d≪δ, dc =c/2πσ, where σ is the conductivity. An exact analysis is also presented of the screening for a cylinder of arbitrary thickness, as well as an analogy between screening by normal metals and screening by superconductors.
Optoelectronic seismograph using a Michelson interferometer with a sliding mirror
Authors: Da Costa Germán , Kiedansky Gerardo , Siri Ricardo
Published: March 2005

An optoelectronic system allowing real-time measurement and recording of 1-D mechanical vibrations is presented. The essential element is a Michelson interferometer, one of whose mirrors is mounted on a freely sliding carrier. In that way, oscillations of the interferometer base (which is fixed to a vibrating structure) produce light-intensity variations at the interferometer output. Light-intensity variations are detected by a phototransistor and stored in a microcomputer memory. The stored signal is numerically processed to obtain the amplitude and frequency of mechanical oscillations.