bluuebunny/crossref_metadata_2025 huggingface dataset:
Remarks on the brachistochrone with viscous friction
Authors: Jones S. E. , Antanackovic T. M. , Dehn M.
Published: March 2005

The classical brachistochrone with viscous friction is discussed within the context of some recent observations. It is pointed out that in certain instances the end-point conditions cannot be used directly to find the constants of integration. Additional formulae are provided which account for these exceptional cases.
Making ‘‘The Mechanical Universe’’
Authors: Goodstein David L. , Olenick Richard P.
Published: March 2005

‘‘The Mechanical Universe and Beyond’’ is an introductory college-level physics telecourse, including calculus, made for broadcast television and classroom use. This article describes the inception and history of the project and the techniques and strategies that were used in producing it. A project to adapt the series for use in high schools is also discussed.
Perfect disturbing measurements
Authors: Ohira Toru , Pearle Philip
Published: March 2005

The Wigner–Araki–Yanase theorem is often interpreted as meaning that there must be an error in measurement under certain conditions (when the commutator C between an additive conserved quantity and the discrete-spectrumed measured quantity does not vanish), and that the error may only be reduced by increasing the size of the apparatus. By explicit example, it is shown that it is possible to have a perfectly accurate measurement if the system being measured is disturbed, regardless of the size of the apparatus. Also illustrated is how the error in an imperfectly accurate measurement may be reduced by decreasing the magnitude of C, without affecting the size of the apparatus.
Dimensions of relativistic quantum mechanical paths
Authors: Cannata F. , Ferrari L.
Published: March 2005

The notion of the dimension of a relativistic quantum mechanical path is illustrated. An elementary introduction to the concept of a fractal curve allows the discussion of the evolution of the quantum mechanical wave packet for free particles in terms of Hausdorff dimensions of quantum ‘‘trajectories.’’ The results of a previous work by Abbott and Wise can be generalized to relativistic quantum mechanics of spin-1/2 particles in the Foldy–Wouthuysen representation. A further extension to spin-zero particles is briefly outlined. By simple considerations, an understanding of the notion of a Hausdorff dimension and its values can be introduced.
Thomson scattering and plasma oscillations
Authors: Lippmann B. A.
Published: March 2005

A direct calculation shows that Thomson scattering—on the microscopic level—manifests itself as plasma oscillations—on the macroscopic level.
A gauge in which the Hamiltonian of a nonrelativistic charged particle is kinetic energy
Authors: Kobe Donald H. , Yang Kuo-Ho
Published: March 2005

Gauge freedom is used to reduce the Hamiltonian of a nonrelativistic charged particle with conservative potential energy that is in a time-dependent external electromagnetic field to kinetic energy only. Nevertheless, the energy of the particle is shown to be kinetic energy plus conservative potential energy. Besides simplifying the Hamiltonian, this gauge dramatically illustrates the conceptual differences between the Hamiltonian and energy for a particle in a time-dependent external electromagnetic field.
An evaluation of classroom teaching practices one year after a workshop for high-school physics teachers
Authors: Lippert Renate C. , Heller Patricia A. , Jones Roger S. , Hobbie Russell K.
Published: March 2005

One year after a summer program for high-school physics teachers, its impact on the teaching practices of the participants was evaluated. Large changes in high-school teachers’ classroom techniques and attitudes have been identified and ascribed to the unique interplay of the structure and content of the workshop.
Magnetic braking: Improved theory
Authors: Heald Mark A.
Published: March 2005

An alternative analysis is presented for the magnetic braking experiment of Wiederick et al., taking into account the fringing streamlines of eddy currents for a rectangular ‘‘footprint’’ of the magnetic field.
A particle sliding down a movable incline: An experiment
Authors: Vermillion R. E. , Cook G. O.
Published: March 2005

A traditional problem has a particle sliding down an incline on a movable wedge. An airtrack glider was modified to serve as such a system; the measured results for the acceleration were compared to predictions based on a model (a) neglecting friction and (b) including friction. Some experimental considerations are discussed. The system exhibits interesting features, including an angle of maximum acceleration that has a value dependent on the coefficient of friction on the incline.
Matrix representation of vectors and operators in nonorthogonal basis vectors
Authors: Deshpande S. D. , Pode R. B.
Published: March 2005

The bases used in quantum mechanics, in general, are orthonormal. The relations in orthonormal basis vectors are simpler than those in nonorthogonal basis vectors. Also, the operators that represent different physical quantities are Hermitian and the eigenvectors of these operators belonging to different eigenvalues are orthonormal to each other. But, in many cases, such as sets of screened hydrogenic wavefunctions, nonorthogonal sets of basis vectors occur. It is, therefore, necessary to consider the representation of vectors and operators in nonorthogonal bases. Making use of the set of vectors reciprocal to the given set of nonorthogonal base vectors, the expression for the norms of vectors and for the matrix elements has been found. Also, adjoint and Hermitian matrices in nonorthogonal bases have been worked out using a set of reciprocal basis vectors.
Fun and frustration with hydrogen in a 1+1 dimension
Authors: Galić H.
Published: March 2005

The Coulomb potential is derived in ‘‘one space–one time’’ dimension and introduced into Dirac and Klein–Gordon equations. The equations are solved and the somewhat surprising result—nonexistence of bound state solutions in the lower dimension—is discussed and identified as another fine example of the ‘‘Klein paradox.’’
Equilibrium sailing velocities
Authors: Goldenbaum George C.
Published: March 2005

The equations of motion of a sailboat have been analytically solved for motion parallel to the wind velocity. For this point of sailing, the equilibrium velocity and acceleration time have been determined as a function of boat parameters and wind velocity. For other sailing angles, numerical solutions of the equilibrium equations give the conditions for achieving maximum speed while numerical integrations of the equations of motion give the acceleration time.
The electrodynamic tether
Authors: Hite Gerald E. , McCoy James E.
Published: March 2005

The electrodynamic tether project being developed by NASA will use a conducting tether attached to a spacecraft in low Earth orbit to interact with the Earth’s magnetic field. This project represents a novel application of Faraday’s and Lenz’s laws of classical electrodynamics. The dynamics of the tether also provide an elegant application of classical mechanics. To emphasize this point, the dynamics of the tether are considered and solved exactly in a reasonable model. The solution for the tether’s configurations has the rather interesting feature that it bifurcates for a certain range of the electrical current in the tether.
A fluctuation interferometer
Authors: Verovnik I. , Likar A.
Published: March 2005

The possibility of demonstrating interference of light from two independent lasers is presented. Fluctuation of the composite signal from two detectors was observed. The amplitude of the fluctuation is a periodic function of the distance between the detectors. The frequency of the fluctuations could be momentarily quite low so that the experiment can be performed with modest equipment. Further simplification of the experiment can be achieved by collecting light from two broad slits on a detector.
Phase changes on reflection from a metallic surface
Authors: Friedmann G. B. , Sandhu H. S.
Published: March 2005

The polarization of light and the phase changes involved on reflection from a metallic surface are discussed. Appropriate vector diagrams and a coordinate system are needed in order to avoid confusion in explaining the results.
Time-dependent tunneling through thin barriers: A simple analytical solution
Authors: Elberfeld W. , Kleber M.
Published: March 2005

Analytical solutions for the time-dependent tunneling of wave trains and wave packets through delta-function barriers are presented. Tunneling currents and density distributions are calculated with no approximations. A standby mechanism is demonstrated: The particle ‘‘waits’’ some time in front of the barrier before it tunnels through the barrier.
The effect of the mass of the center spring in one-dimensional coupled harmonic oscillators
Authors: Wallach David L. , Beatty William , Beisler Karl , Chronowski Peter , Holloway Matthew , Hutchinson Robert , Kacmarik Diane , Lesko Raymond , Lutz James , Miller Daniel , Sivak Michael
Published: March 2005

The effect of the mass of the center spring in the one-dimensional coupled harmonic oscillator is calculated and shown to have a small but noticeable effect on the periods of the normal modes of oscillation. Sophomore engineering students have developed the experimental technique using only stop watches, an analytic balance, and a standard Ealing■ air track.
The harmonic oscillator at finite temperature using path integrals
Authors: Larsen Å. , Ravndal F.
Published: March 2005

The statistical mechanics of a quantum harmonic oscillator can easily be formulated in terms of Feynman path integrals in imaginary time. By straightforward integrations, the partition function, the internal energy, and correlation functions are found. When time is discretized, the same results can be obtained directly using Monte Carlo methods on a computer. In the zero temperature limit, the usual quantum mechanical results are recovered.
On the harmonic oscillator inside an infinite potential well
Authors: Marin J. L. , Cruz S. A.
Published: March 2005

The exact solution to Schrödinger’s equation for a three-dimensional harmonic oscillator confined by two impenetrable walls is presented. The energy levels of this system are obtained as a function of wall separation as well as distance of the center of the oscillator to the walls. The force exerted by the walls on the oscillator is also evaluated, showing a classical behavior.
The search for gravitational waves
Authors: Tinto Massimo
Published: March 2005

This article serves as an introduction to the sources of gravitational waves and their detection. The types of sources expected to generate signals detectable by instruments currently planned, together with the theory governing these detectors, are considered. Order of magnitude estimates for the characteristic wave amplitudes are calculated and compared to the sensitivities of the currently prototyped and future detectors.
Mapping the weak chirality of atoms
Authors: Hegstrom R. A. , Chamberlain J. P. , Seto K. , Watson R. G.
Published: March 2005

Atoms are chiral due to the parity-violating weak neutral current interaction between the nucleus and the electrons. A simple pictorial representation of the chirality of an atom is obtained by mapping the electron probability current density in the atom. Results are shown for a hydrogenic 2p1/2 stationary state.
The total reflection of a compact wave group: Long-range transmission in a waveguide
Authors: Gragg Robert F.
Published: March 2005

This article presents a unified explanation of the reflection of compact wave groups (e.g., pulses and bounded beams) from plane interfaces with application to signal propagation in waveguides. Expressions are developed for the spatial, temporal, and phase shifts that are experienced by such wave groups but not by plane waves.
The air drag on an accelerating disk: A laboratory experiment
Authors: Basano L. , Ottonello P.
Published: March 2005

A simple laboratory experiment is presented on the air drag encountered by an accelerating disk at high Reynolds numbers. The motion is recorded and analyzed with the help of a common personal computer. It turns out that an equation of motion based on the quadratic damping term, −Bv2, does not provide a satisfactory description and that an improvement based on an ‘‘added mass’’ term is still not sufficient to obtain an acceptable fit. Agreement with experimental data is achieved by introducing an additional term, −K v̇ v2, usually not considered in hydrodynamical problems.
The adiabatic theorem and Berry’s phase
Authors: Holstein Barry R.
Published: March 2005

A study is presented of Berry’s observation that when a quantum-mechanical system is transported on a closed adiabatic journey, a topological phase arises in addition to the usual dynamical phase expected from the adiabatic theorem. Consequences are explored in the case of a simple magnetic moment–magnetic field interaction and are shown to lead, among other things, to Dirac’s famous relation between electric and magnetic charges.
Nonradiating sources: The subtle art of changing light into black
Authors: Meyer-Vernet Nicole
Published: March 2005

When a point charge accelerates or moves faster than light in a dielectric medium, it radiates. However, sources of finite size can be designed whose peculiar structure ensures that they do not radiate under these conditions. The criterion for absence of radiation of a rigid source in free space is generalized to a dielectric medium, and applied to either oscillating or Čerenkov sources.
A one-dimensional realization of a general model for cluster–cluster aggregation
Authors: Titus William J.
Published: March 2005

A one-dimensional realization of a general model for cluster–cluster formation of aggregates is presented and applied to structures with constant geometric growth factors. Such objects exhibit fractal properties, and techniques for analyzing such structures in both direct and reciprocal space are discussed.
The negative proton: Its earliest history
Authors: Kragh Helge
Published: March 2005

After the discovery of the positron in 1932, several physicists, including Bohr and Gamow, speculated that negative protons existed too. Other physicists considered antiprotons in the sense first suggested by Dirac in 1931. This article examines the early history of the concept of the negative proton and its application in nuclear and cosmic ray physics.
The remarkable capabilities of recursive relations
Authors: Ignatovich V. K.
Published: March 2005

The recursive relations method is presented. To illustrate its capability a new way is presented to solve the one-dimensional Schrödinger equation with a stepwise or any periodic potential (semi-infinite or finite). The method is shown to be also applicable to other physical problems, for instance, to molecular gas diffusion in linear and branched guides and to the scattering of a quantum mechanical particle on a spherically symmetric nut-shell potential.
A further canonical study of the damped linear oscillator
Authors: Ares-de-Parga A Gonzalo , Rosales Marco A. , Jiménez J. L.
Published: March 2005

The Hamilton–Jacobi equation for the one-dimensional damped oscillator is analyzed, and different ways of obtaining the solution are shown. The technique of the Poisson brackets is also applied to such a dissipative system.
The stretched harmonic oscillator: An analytical test of semiclassical approximations
Authors: Casas M. , Krivine H. , Martorell J.
Published: March 2005

The stretched harmonic oscillator is a potential that can be varied continuously from the harmonic oscillator to the infinite square well. The corresponding solutions of the one-dimensional Schrödinger equation are almost as simple as those of the usual harmonic oscillator. It is used to study analytically the reliability of semiclassical approximations.
On the equivalence of the laws of Biot–Savart and Ampere
Authors: Weber T. A. , Macomb D. J.
Published: March 2005

Many elementary physics texts do not explicitly state how the laws of Ampere and Biot–Savart are related. This relationship is explored with the help of an interesting example that seems to imply the paradoxical result that displacement currents are not equivalent to conduction currents in the production of magnetic fields. The equivalence of the two laws is then demonstrated by the use of Maxwell’s equations and the paradox is thereby resolved. Although the proof of equivalence is not suitable for introductory courses, the result that these two laws contain the same physics should be emphasized.
Derivation of reciprocity relations for a beam splitter from energy balance
Authors: Ou Z. Y. , Mandel L.
Published: March 2005

It is shown that the usual amplitude and phase relations connecting the reflectance and transmittance of a stratified or continuous, nonabsorbing beam splitter can be derived by a simple energy balance argument relating to a Michelson interferometer.
The case of the identically accelerated twins
Authors: Boughn S. P.
Published: March 2005

A variation on the ‘‘twin paradox’’ of special relativity is presented wherein twins undergo the same acceleration for the same length of time, yet they age differently. Although this problem is simple to solve, it gets to the heart of the behavior of clocks in special relativity and, hopefully, will help to dispel the notion students develop that the acceleration experienced by a relativistic traveler is directly related to the rate at which that traveler ages.
The Compton effect as an experimental approach toward relativistic mass
Authors: Hoffman Matthiam J. H.
Published: March 2005

A way of presenting an experiment on the Compton effect to undergraduate students is suggested. First, a nonrelativistic analysis of this effect accompanied by an excellent approximation to the resulting nonrelativistic scattering formula is made. It is then shown how the discrepancy between the nonrelativistic predictions and the experimental results leads in a fairly plausible way to the relativistic form of the energy conservation law, the relativistic mass–velocity dependence, and even the formula ΔE=Δmc2 .
An elementary introduction to solitons
Authors: Gratton J. , Delellis R.
Published: March 2005

Nonlinear phenomena are a very important topic of modern physics that is usually taught only at an advanced level. An elementary introduction of this subject is presented, considering nonlinear waves in shallow water. The Korteweg–De Vries equation is derived by means of simple physical arguments, and the approximations involved are discussed. Solutions that propagate without changing their shape are studied and their properties are described using an analogy with a mechanical oscillator. The solitary and cnoidal waves are obtained as well as harmonic waves as a limiting case. The mathematics employed is simple and straightforward.
Correlations and squeezing of two-mode oscillations
Authors: Ekert A. K. , Knight P. L.
Published: March 2005

In a squeezed state, the variance in one canonical variable may be suppressed below that normally associated with either the ground state or a coherent state, at the expense of an expansion in the variance of the conjugate variable. Squeezed states are usually discussed in the context of quantized light fields. The principal properties of squeezed states are demonstrated using the motion of quantum mechanical simple harmonic oscillators. The motion of a single oscillator is discussed to introduce the key concepts of squeezing, including quadrature operators, and the error contours of the Wigner function describing the quantum quasiprobability distributions in phase space of the oscillator motion. The main topic of two-mode squeezing is then addressed, in which the fluctuations in a system of two oscillators are tightly correlated. The existence of squeezing is demonstrated in normal mode coordinates representing motion of superpositions of the motion of the two oscillators. The fluctuations within a single oscillator are shown to increase when squeezing increases in the normal modes, generating thermal noise in individual mode subsystems.
A mirror calculus for combining isometries in two-dimensional crystallography
Authors: Aravind P. K.
Published: March 2005

An understanding of two-dimensional crystallography calls for a knowledge of the four basic isometries of the Euclidean plane (reflections, translations, rotations, and glide reflections) and the ability to combine any two of these to obtain a third. After a review of how the other isometries can be expressed in terms of reflections, an algebra and geometry of mirror operations (reflections) is introduced that permits a straightforward evaluation of the product of an arbitrary number of plane isometries.
Applications of the residue theorem to two-dimensional electrostatic and magnetostatic situations
Authors: Comella Mark J.
Published: March 2005

Ampere’s circuital law for magnetostatics and two-dimensional analogs of Gauss’ law for electrostatics and magnetostatics are obtained by constructing appropriate complex functions and applying the residue theorem. The approach is motivated by the formal similarities between the residue theorem and Ampere’s circuital law for magnetostatics.
A direct laboratory approach to the study of capacitors
Authors: Wilson David E.
Published: March 2005

The construction of a device called a charge pump is described. This charge pump can be built for less than $10 and, with the aid of a voltmeter and stopwatch, allows the student of introductory physics to measure the capacitance of a capacitor and the charge on a capacitor. Four typical experiments that utilize the charge pump are outlined. Errors of the order of 1% are obtained by students when the experiments are performed.
On the spring constant of a close-coiled helical spring
Authors: Mohazzabi P. , McCrickard J. P.
Published: March 2005

The relationship between the spring constant of a close-coiled helical spring, its geometry, and the shear modulus of its material is examined in a way suitable for presentation in physics textbooks. Contributions from both torsion and pure shear are considered.
Spinning a pulley with a vibrating cord: A marvel
Authors: Vermillion R. E. , Simpson H. M.
Published: March 2005

A pulley can be caused to rotate by creating longitudinal vibrations in a cord that passes over the pulley. For small amplitudes and high frequencies, the motion of the cord is too small to notice and the pulley seems to be spinning with no cause, creating a striking effect. Pulley rotations were observed for a variety of pulleys and cords; nearly any such system will work. The speed and direction of the rotation depends on the various physical parameters of the system: vibration frequency and amplitude, cord tension, and the radius and moment of inertia of the pulley. An investigation is reported of pulley response versus cord frequency and amplitude for a typical system.
An alternative approach to the teaching of rotational dynamics
Authors: Lock James A.
Published: March 2005

An alternative approach to the stability of torque-free rotations and to top nutation that emphasizes conservation laws and physical reasoning is examined. It is felt that such an approach, which is largely free of sophisticated mathematics, would be useful in teaching these topics in rotational motion at the introductory physics level.
On pressure change occurring during gas mixing
Authors: Chenoweth Donald R. , Paolucci Samuel
Published: March 2005

A pressure change results at thermal equilibrium when ideal gases initially having the same pressure, different temperature, and dissimilar molecular structure are mixed in a constant volume isolated reservoir. This pressure change does not arise from the gas mixing, but rather it results from a redistribution of energy between the translational and internal molecular motion. The conditions for the existence of an extremum in the pressure change are also given.
Frame dependence of the phase of de Broglie waves
Authors: Wignall J. W. G.
Published: March 2005

The fact that the phase of de Broglie waves is not invariant under a change of frame described by a Galilean transformation has sometimes been used as an argument against their existence as physically real waves. It is shown, however, that this phase change is an artifact of the Galilean transformation, and does not occur if one uses instead the low-velocity limit of the Lorentz transformation consistently to order (velocity/c)2.
Timely equations of rocket motion and the surprising power of rockets
Authors: Stephenson R.
Published: March 2005

Current general physics textbooks derive equations for rocket acceleration and rocket velocity as functions of mass. Rocket position is ignored in nearly all textbooks. Using time left till total mass consumption as a variable, simple equations for acceleration, velocity, and position can be easily derived. The flight of a rocket subject to constant gravitational acceleration proves quite simple to analyze. Finally, a power analysis shows that in an inertial reference frame, the power of a rocket can exceed the power of its engine.
A simple method for measurement of the diffusion of vapors
Authors: Abraham Arnold J. , Bean Charles P.
Published: March 2005

A simple method for the measurement of the diffusion of vapors is described. Commercially available microcapillary tubes, a ruler, and a watch, allow measurement of the diffusion constant to a precision of better than 1%. This article describes measurements of the diffusion of water, benzene, and various straight chain alcohol molecules in air. The technique is suitable for the undergraduate laboratory or as a home experiment.
Galilean transformation and the path integral propagator for a crossed electric and magnetic field
Authors: de Souza Carlos Farina , de Souza Dutra Álvaro
Published: March 2005

A Galilean transformation is made in the path integral formalism to obtain the Feynman propagator of a charged particle in the presence of a crossed uniform electromagnetic field in terms of the propagator of a charged particle in the presence of only a magnetic one. Also noted is how the result makes it possible to relate the initial propagator, with E and B, to that of the free particle.
Heuristic methods for counting and sizing of molecules in the liquid state
Authors: Crandall R. E. , Dunne T. G.
Published: March 2005

Though the liquid state is highly complex, there are global classical properties that liquids enjoy. Heuristic liquid-state relations may be derived from the fundamental physics of surface energy and volume energy. It has long been known that the dimensional difference between these two measures can be exploited to yield estimates of molecular count and size. Herein is described an alternative approach in which a key parameter is the temperature coefficient of surface tension. This parameter circumvents the need for awkward volume energy measurements. Here indicated is how simple experiments, or even pretabulated chemical data, may be used to estimate such quantities as Avogadro’s number.
A classroom exercise to determine the Earth–Moon distance
Authors: Cowley E. Roger
Published: March 2005

A simple indoor exercise to obtain the value of the Earth–Moon distance, in terms of the Earth’s radius, is described. The student measures on a photograph the ratio of the diameter of the Moon to the diameter of the shadow of the Earth during a lunar eclipse. A simple but adequate reduction of the measurement is given.
The quantum mechanical few-body problem
Authors: Norbury John W.
Published: March 2005

A solution to quantum mechanical problems of two, three, and four bodies is discussed from the point of view of two-body harmonic oscillator forces. An exact solution to the three- and four-body problems is found for harmonic oscillator forces, assuming equal masses. The aim of the discussion is to make students aware of the real difficulties of the few-body problem.
Molecular beam experiments, the Lamb shift, and the relation between experiments and theory
Authors: Schweber S. S.
Published: March 2005

The Rabi molecular beam experiments and the Lamb shift experiment are analyzed to elucidate the role the nonrelativistic Schrödinger equation plays in their design, analysis, and interpretation.
A note on the fluctuations of noninteracting particles
Authors: Rahal V.
Published: March 2005

The exact expression is derived for the fluctuation in the number of particles of a system of noninteracting fermions or bosons. The result shows in an instructive way the additional fluctuation due to the symmetrization postulate of quantum mechanics.
A simple method of making a one-step rainbow hologram with a beaker of water
Authors: Huang Jacob W. , Zhang Pin-yi
Published: March 2005

In this article, a simple experiment is introduced making astigmatic one-step rainbow holograms. Unlike the normal astigmatic one-step rainbow holography, which uses a cylindrical glass lens, this method uses a beaker or a bottle of water instead of a glass cylindrical lens. When the hologram is reconstructed with a white light point source, a clear and wide view of the holographic image is reconstructed.
Using linear accelerators with high-school students
Authors: Manos Harry
Published: March 2005

Excellent communication between a high school and a local university in Southern California permits advanced placement high-school physics students to use the university’s linear accelerators to promote the teaching of modern physics and the use of modern laboratory technique.
Effective Lagrangians and quantum mechanics: The index of refraction
Authors: Holstein Barry R.
Published: March 2005

Using path integral quantization of a harmonic oscillator–electric field system, it is demonstrated how the familiar expression for the index of refraction of a gas can be obtained by use of the so-called effective Lagrangian.
The dynamics of a falling chain: I
Authors: Calkin M. G. , March R. H.
Published: March 2005

‘‘A chain is suspended, both ends at the same elevation, and then one end is released.’’ This familiar problem is studied and the real dynamical behavior is found to be very different from the textbook answer. Results are presented that show that the real chain is largely an energy-conserving system. This gives rise to acceleration of the free end greater than g, and to very large tension at the fixed end.
Sunlight attenuation in nuclear winter
Authors: Bridgman Charles J.
Published: March 2005

A single algebraic expression is derived for the optical thickness of dust or smoke generated by a large-scale nuclear attack such as envisioned in nuclear winter studies. The formula is proposed as an addition to the set of ‘‘simple formulas’’ for the classroom study of nuclear effects. It may also be of use to analysts for first-order calculations.
Energy balance and the Abraham–Lorentz equation
Authors: Campos I. , Jiménez J. L.
Published: March 2005

It is shown that the energy balance usually assumed for the derivation of the Abraham–Lorentz equation is incomplete because it does not take the change in the energy of the bound self-field into account. Starting from the energy balance implied by Poynting’s theorem, a new derivation of the Abraham–Lorentz equation is presented. The energy balance is applied first to an extended charge distribution and then the point-charge limit is taken. This approach neither requires neglecting the so-called Schott energy term nor any further hypothesis. The calculations point to the dragged self-field as the origin of the ‘‘radiation’’ damping term.
An acoustic Doppler shift experiment with the signal-receiving relay
Authors: Zhong An
Published: March 2005

The following describes measurement of the Doppler shift of sound waves under the less than ideal conditions found in the classroom or in the laboratory. The Doppler shift is produced by a sound receiver that has been fixed on a turning disk in motion relative to the stationary source. A frequency-modulated radio is used as a signal receiver. The frequency shift of the signal is shown by a counter and is displayed by an oscilloscope.
A novel method for determining the K-absorption edge using bremsstrahlung radiation
Authors: Nayak S. V. , Badiger N. M.
Published: March 2005

Here we present a novel method for determining the K-absorption edge of heavy elements using continuous bremsstrahlung radiation produced by a weak beta source. The spectrum of the radiation transmitted through an elemental target is recorded by a HPGe detector. The sharp discontinuity observed in the spectrum is identified as the absorption-edge energy. The experimental technique is easily implemented in undergraduate laboratories because only one source of beta particles and only one target foil for each element are required.
Free energies in the presence of electric and magnetic fields
Authors: Narayan Onuttom , Young A. P.
Published: March 2005

We discuss the different free energies and Hamiltonians for materials in static electric and magnetic fields and which choice is the most appropriate for statistical mechanics calculations. We also discuss the relation between the various free energies and the Landau function which has to be minimized to determine the equilibrium polarization or magnetization.
Diffusion in a half-space: From Lord Kelvin to path integrals
Authors: Slutsky Michael
Published: March 2005

Many important transport phenomena are described by simple mathematical models rooted in the diffusion equation. Geometrical constraints present in such phenomena often have a global influence and manifest themselves in scaling relations and stable distribution functions. I treat a random walk confined to a half-space using several approaches: diffusion equations, lattice walks, and path integrals. Potential generalizations are discussed.
Identification of Adult Mouse Neurovirulence Determinants of the Sindbis Virus Strain AR86
Authors: Suthar Mehul S. , Shabman Reed , Madric Kenya , Lambeth Cassandra , Heise Mark T.
Published: March 2005

Sindbis virus infection of mice has provided valuable insight into viral and host factors that contribute to virus-induced neurologic disease. In an effort to further define the viral genetic elements that contribute to adult mouse neurovirulence, the neurovirulent Sindbis virus strain AR86 was compared to the closely related (22 single amino acid coding changes and the presence or absence of an 18-amino-acid sequence in nsP3 [positions 386 to 403]) but avirulent Girdwood strain. Initial studies using chimeric viruses demonstrated that genetic elements within the nonstructural and structural coding regions contributed to AR86 neurovirulence. Detailed mapping studies identified three major determinants in the nonstructural region, at nsP1 538 (Ile to Thr; avirulent to virulent), an 18-amino-acid deletion in nsP3 (positions 386 to 403), and nsP3 537 (opal to Cys; avirulent to virulent), as well as a single determinant in the structural genes at E2 243 (Leu to Ser; avirulent to virulent), which were essential for AR86 adult mouse neurovirulence. Replacing these codons in AR86 with those found in Girdwood resulted in the attenuation of AR86, while the four corresponding AR86 changes in the Girdwood genetic background increased virulence to the level of wild-type AR86. The attenuating mutations did not adversely affect viral replication in vitro, and the attenuated viruses established infection in the brain and spinal cord as efficiently as the virulent viruses. However, the virus containing the four virulence determinants grew to higher levels in the spinal cord at late times postinfection, suggesting that the virus containing the four attenuating determinants either failed to spread or was cleared more efficiently than the wild-type virus.
Silencing of Integrated Human Papillomavirus Type 18 Oncogene Transcription in Cells Expressing SerpinB2
Authors: Darnell Grant A. , Antalis Toni M. , Rose Barbara R. , Suhrbier Andreas
Published: March 2005

The serine protease inhibitor SerpinB2 (PAI-2), a major product of differentiating squamous epithelial cells, has recently been shown to bind and protect the retinoblastoma protein (Rb) from degradation. In human papillomavirus type 18 (HPV-18)-transformed epithelial cells the expression of the E6 and E7 oncoproteins is controlled by the HPV-18 upstream regulatory region (URR). Here we illustrate that PAI-2 expression in the HPV-18-transformed cervical carcinoma line HeLa resulted in the restoration of Rb expression, which led to the functional silencing of transcription from the HPV-18 URR. This caused loss of E7 protein expression and restoration of multiple E6- and E7-targeted host proteins, including p53, c-Myc, and c-Jun. Rb expression emerged as sufficient for the transcriptional repression of the URR, with repression mediated via the C/EBPβ-YY1 binding site (URR 7709 to 7719). In contrast to HeLa cells, where the C/EBPβ-YY1 dimer binds this site, in PAI-2- and/or Rb-expressing cells the site was occupied by the dominant-negative C/EBPβ isoform liver-enriched transcriptional inhibitory protein (LIP). PAI-2 expression thus has a potent suppressive effect on HPV-18 oncogene transcription mediated by Rb and LIP, a finding with potential implications for prognosis and treatment of HPV-transformed lesions.
Parallel Human Immunodeficiency Virus Type 1-Specific CD8+T-Lymphocyte Responses in Blood and Mucosa during Chronic Infection
Authors: Ibarrondo F. Javier , Anton Peter A. , Fuerst Marie , Ng Hwee L. , Wong Johnson T. , Matud Jose , Elliott Julie , Shih Roger , Hausner Mary Ann , Price Charles , Hultin Lance E. , Hultin Patricia M. , Jamieson Beth D. , Yang Otto O.
Published: March 2005

Gut-associated lymphoid tissue is the major reservoir of lymphocytes and human immunodeficiency virus type 1 (HIV-1) replication in vivo, yet little is known about HIV-1-specific CD8+T-lymphocyte (CTL) responses in this compartment. Here we assessed the breadth and magnitude of HIV-1-specific CTL in the peripheral blood and sigmoid colon mucosa of infected subjects not on antiretroviral therapy by enzyme-linked immunospot analysis with 53 peptide pools spanning all viral proteins. Comparisons of blood and mucosal CTL revealed that the magnitude of pool-specific responses is correlated within each individual (meanr2= 0.82 ± 0.04) and across all individuals (r2= 0.75;P< 0.001). Overall, 85.1% of screened peptide pools yielded concordant negative or positive results between compartments. CTL targeting was also closely related between blood and mucosa, with Nef being the most highly targeted (mean of 2.4 spot-forming cells [SFC[/106CD8+T lymphocytes/amino acid [SFC/CD8/aa]), followed by Gag (1.5 SFC/CD8/aa). Finally, comparisons of peptide pool responses seen in both blood and mucosa (concordant positives) versus those seen only in one but not the other (discordant positives) showed that most discordant results were likely an artifact of responses being near the limit of detection. Overall, these results indicate that HIV-1-specific CTL responses in the blood mirror those seen in the mucosal compartment in natural chronic infection. For protective or immunotherapeutic vaccination, it will be important to determine whether immunity is elicited in the mucosa, which is a key site of initial infection and subsequent HIV-1 replication in vivo.
Internal Point Mutations of the Capsid Modify the Serotype of
Rice Yellow Mottle Virus
Authors: Hébrard Eugénie , Pinel-Galzi Agnès , Catherinot Vincent , Labesse Gilles , Brugidou Christophe , Fargette Denis
Published: March 2005

Rice yellow mottle virus
is classified in five major serotypes; the molecular diversity of the coat protein (CP) is well established, but the amino acids involved in the recognition by discriminant monoclonal antibodies (MAbs) remain unknown. Reconstruction of a phylogenetic tree and sequence alignment of the CP gene of a sample representative of the continental-large diversity were used to identify 10 serospecific amino acids (i.e., conserved in all isolates belonging to the same serotype and distinct in other serotypes). Positions occupied by serospecific residues were localized on the crystal structure of the CP monomer and on modeled capsomers. Structural, molecular, and serological properties of each serotype were analyzed, and subsequently, hypotheses on the potential role of amino acids in discriminating reactions with antibodies were formulated. The residues 114 and 115 (serospecific of Sr1) and 190 (serospecific of Sr2) were localized on the outer surface of the capsid and might be directly involved in the immunoreactivity with MAb D and MAb A, respectively. In contrast, residues 180 (Sr3) and 178 (Sr5) lay within the inner surface of the capsid. To understand the role of these internal positions in the recognition with the antibodies, two substitutions (T180K and G178D) were introduced in the CP of an infectious clone. These mutations modified the antigenicity with MAb G and MAb E discriminating Sr3 and Sr5, respectively, while the reaction with MAb D remained unaffected. This result suggests an indirect effect of these two internal mutations on local immunostructure while the global structure was maintained.
Mechanism of the Antiviral Action of 1-β-
d
-Arabinofuranosylcytosine on Borna Disease Virus
Authors: Volmer Romain , Bajramovic Jeffrey J. , Schneider Urs , Ufano Sandra , Pochet Sylvie , Gonzalez-Dunia Daniel
Published: March 2005

Borna disease virus
(BDV) is a nonsegmented, negative-stranded RNA virus that causes neurological diseases in a variety of warm-blooded animal species. Recently, we showed that the nucleoside analog 1-β-
d
-arabinofuranosylcytosine (Ara-C) was a potent inhibitor of BDV. This finding was surprising for an RNA virus, since Ara-C is a DNA polymerase inhibitor. Thus, we sought to better define the mechanism of action of Ara-C on BDV. Here, we show that (i) this effect is specific for an arabinoside ring carrying a cytosine base, (ii) it requires phosphorylation of the nucleotide, and (iii) it can be reversed by an excess of cytidine. Using the recently described minigenome assay for BDV, we provide evidence suggesting that Ara-C may act as a competitive inhibitor of the BDV replication complex.
DEEPLY BOUND PIONIC ATOMS AND FINITE PION MEAN FIELD IN NUCLEI
Authors: TOKI HIROSHI
Published: March 2005

We discuss first the present status of the deeply bound pionic atoms. The high resolution ( d ,3 He ) reactions on 208,206 Pb and 116,120,124 Sn are used to excite the deeply bound pionic atoms. The behavior of the isovector s-wave optical potential extracted from these data is interpreted as the signature of partial restoration of chiral symmetry in nuclei. We present then the role of the chiral symmetry in the description of finite nuclei with the hope to unify the hadron and nuclear physics. This trial becomes possible by introducing finite pion mean field, which contributes largely to enhance the spin-orbit splitting so as to provide the j-j magic number. We discuss the qualitative consequence of the finite pion mean field for various observables.
BES RESULTS ON J/ψ DECAYS AND CHARMONIUM TRANSITIONS
Authors:   FOR THE BES COLLABORATION., HARRIS FREDERICK A.
Published: March 2005

Results are reported based on samples of 58 million J/ψ and 14 million ψ(2S) decays obtained by the BESII experiment. Improved branching fraction measurements are determined, including branching fractions for J/ψ→π+π-π0, ψ(2S)→π0J/ψ, ηJ/ψ, π0π0J/ψ, anything J/ψ, and ψ(2S)→γχc1, γχc2→γγJ/ψ. The decay J/ψ→ωπ+π- is studied. At low ππ mass, a large, broad peak due to the σ is observed, and its pole position is determined. Results are presented on ψ(2S) and J/ψ hadronic decays to [Formula: see text] and [Formula: see text] final states. No significant Θ(1540) signal, the pentaquark candidate, is observed, and upper limits are set. An enhancement near the mp+MΛ mass threshold is observed in the [Formula: see text] invariant mass spectrum from [Formula: see text] decays. It can be fit with an S-wave Breit-Wigner resonance with a mass m=2075±12 ( stat )±5 ( syst ) MeV and a width of Γ=90±35 ( stat )±9 ( syst ) MeV .
EXPERIMENTS WITH THE WASA DETECTOR AT COSY
Authors:   FOR THE WASA AT COSY PROJECT., RITMAN JAMES
Published: March 2005

Recently the unique possibility to transfer the WASA detector from TSL in Uppsala to COSY in Jülich has appeared. This transfer will be advantageous to both the current WASA collaboration at CELSIUS and the current COSY user group, since it will allow for a continued utilization of the WASA detector and it will enable a much more complete exploitation of the physics potential of COSY. This symbiosis will allow WASA to capitalize on the higher beam energy and polarized beams available and COSY to measure many of the possible final states with more than one photon. This report presents a sketch of the physics program forseen for WASA at COSY and the ongoing activities to prepare the transfer.
SCALAR AND TENSOR MESONS FROM THE COMBINED ANALYSIS OF THE PROCESSES ππ→ππ, $K\overline{K}$, ηη
Authors: SUROVTSEV YU. S. , KAMIŃSKI R. , KRUPA D. , NAGY M.
Published: March 2005

Analysis of the isoscalar S- and D-waves of processes ππ→ππ, [Formula: see text], ηη is carried out aimed at studying the QCD nature of scalar and tensor mesons below 2 GeV. An assignment of the scalar mesons below to lower nonets is proposed.
STUDY OF THE PROCESS e+e-→π+π-π0 IN THE ENERGY RANGE 1.04-1.38 GEV WITH CMD-2 DETECTOR
Authors:   ON BEHALF OF CMD-2 COLLABORATION., GORBACHEV DMITRY A.
Published: March 2005

The data sample of 6 pb -1 collected by Cryogenic Magnetic Detector (CMD-2) at VEPP-2M collider in the c.m. energy range 1.04-1.38 GeV have been used to measure cross section of the process e+e-→π+π-π0 and to study its dynamics. It is shown that for description of the invariant mass spectra of π+π- pairs one should take into account the ωπ0 contribution arising due to ρ-ω - interference.
EXCLUSIVE π+ PRODUCTION AT HERMES
Authors:   ON BEHALF OF THE HERMES COLLABORATION., HADJIDAKIS CYNTHIA
Published: March 2005

Hard exclusive production in deep inelastic lepton scattering provides access to the unknown Generalized Parton Distributions (GPDs) of the nucleon. At HERMES, the unpolarized total cross section for hard exclusive π+ production have been measured with a 27.6 GeV positron beam on an internal hydrogen gas target. First preliminary results for 1.5<Q2<10.5 GeV 2 and for 0.02<x<0.8 are presented and compared to GPD calculations. Forthcoming measurement for the single-spin asymmetry using a transversally polarized target is also reported.
EXACT RENORMALIZATION GROUP AND MANY-FERMION SYSTEMS
Authors: KRIPPA B. , BIRSE M. C. , MCGOVERN J. A. , WALET N. R.
Published: March 2005

The exact renormalization group method is applied to many-fermion systems with short-range attractive forces. The strength of the attractive fermion-fermion interaction is determined from the vacuum scattering length. A set of approximate flow equations is derived including fermionic bosonic fluctations. The numerical solutions show a phase transition to a gapped phase. The inclusion of bosonic fluctuations is found to be significant only in the small-gap regime.
HADRON ATTENUATION AT HERMES BY (PRE)HADRONIC FSI
Authors: GALLMEISTER K. , CASSING W. , FALTER T. , MOSEL U.
Published: March 2005

We investigate hadron formation in high energy electroproduction off complex nuclei in the framework of a BUU transport model. Our approach combines a quantum mechanical treatment of the photon's initial state interactions with a semi-classical coupled channel simulation of the (pre)hadronic final-state interactions (FSI). This allows us to study the hadron attenuation observed at HERMES and to get information on the space-time picture of hadron formation separately for π±, π0, K±, p and [Formula: see text].
RADIATIVE B MESON DECAYS AT BABAR
Authors: BELLINI FABIO
Published: March 2005

Recent BaBar results on rare B decays involving flavor changing neutral currents are presented. New measurements of the CP asymmetries in b→sγ and B→K*γ decays are reported as well as B→K(*)l+l- and b→sl+l- branching ratio measurements. The data sample comprises [Formula: see text] decays collected with the BaBar detector at the PEP-II e+e- storage ring.