bluuebunny/crossref_metadata_2025 huggingface dataset:
SO(2) and the study of the infinite-well potential
Authors: Aebersold Dennis , Langerman Andrew
Published: March 2005

We identify the symmetry group of the one-dimensional infinite-well potential problem as SO(2). By studying the irreducible representations of the SO(2) group we obtain the eigenvalues and eigenkets for the problem.
Semiclassical description of coherence effects in spontaneous emission and superradiance
Authors: Durrant A. V.
Published: March 2005

A semiclassical radiation theory is developed in which the spontaneous emission field of a two-level atom is a quantum entity represented by atomic operators acting in the Hilbert space of the atomic states. The theory is applied to an investigation of the coherence properties of spontaneous emission. It is found that incoherent and coherent components can be identified in the emission field, the former dominating in the early stages of the decay from the excited state and the latter dominating in the later stages or in the emission from a weakly excited atom. The single-atom coherence properties are shown to lead to well-known superradiance phenomena in the spontaneous emission from an assembly of similar atoms. The paper does not use the theory of quantum electrodynamics; it builds on knowledge at the undergraduate level of classical radiation theory and the quantum mechanics of atoms.
Self-adjointness and spontaneously broken symmetry
Authors: Capri Anton Z.
Published: March 2005

The notion of self-adjointness as distinct from Hermiticity is usually avoided in elementary quantum mechanics courses due to a feeling that it has nothing to do with physics or else is too mathematical. This is definitely not the case, and we use the model of a free particle restricted to motion on a line over a finite interval, to demonstrate this. For such a particle, there is one-parameter infinity of self-adjoint extensions of the momentum operator. We use one of these, corresponding to ’’antiperiodic’’ boundary conditions, to show that physical phenomena different from the usual case (periodic boundary conditions) occur. In fact, in this case, we have a model displaying many of the properties of spontaneously broken symmetry.
Quasiclassical quantization of the magnetic charge
Authors: Hraskó P.
Published: March 2005

Quasiclassical quantization of a spherical pendulum in which the moving point mass and the center have electric and magnetic charge, respectively, is discussed. It is shown that for this system quantum conditions do not simply select between classical orbits. The requirement of spherical symmetry leads to the quantization condition of Dirac for the product of the charges and the total angular momentum may be either an integer or a half-integer multiple of h/.
The luminosity distance equation in Friedmann cosmology
Authors: Terrell James
Published: March 2005

We propove a new form of the luminosity distance equation and of the apparent distance equation, for Friedmann cosmological models which appear tot have advantages once the vual equation in clarity convenience, and computation accuracy.
Optics in laser-produced plasmas
Authors: Giovanielli D. V. , Godwin R. P.
Published: March 2005

The concepts of linear optics are applied to the physics of energy coupling into laser-produced plasmas currently of interest in laser-initiated fusion research. The effects of polarization and angle of incidence upon reflection and refraction are recalled. Singular behavior occurs in the region of the plasma where the real part of the dielectric constant vanishes, the so-called ’’critical density’’ region. The effective generation of Langmuir waves at the surfaces of bounded plasmas through the optical resonance of obliquely incident electromagnetic radiation is heuristically discussed. Enhanced electric fields, enhanced ’’collisionless’’ damping, harmonic generation, the presence of energetic electrons, and density profile modifications which result near the critical density from the excitation of these plasma waves are described. While more complex plasma processes may occur, they are not within the scope of this review.
Fourier spectroscopy: A simple analysis technique
Authors: Oelfke William C.
Published: March 2005

Recently, Fourier spectroscopy has been discussed as a promising project to introduce into undergraduate physics laboratories. Such a project can have great educational value if the student who conducts the experiment and takes the data can conduct and observe every step of the analysis procedure as well. Fast Fourier analysis computer programs, although they provide great speed and flexibility, prevent the student from participating in the analysis of the experimental data and therefore make little contribution to the student’s understanding of the Fourier integral theorem. This paper presents a simple method of analysis whereby the student experimenter can integrate, point by point, any interferogram to obtain its Fourier transform. The manual technique requires no special equipment and is based on relationships that most undergraduate physics students can derive from the Fourier integral equations.
Materials science undergraduate course laboratory in which students perform original research
Authors: Milstein Frederick , Smith Paul W.
Published: March 2005

A materials science course laboratory, in which undergraduate students perform original experimental research studies of properties of materials which evidently have not been studied elsewhere, has been implemented at the University of California, Santa Barbara, in the College of Engineering. It is suggested that a materials science course laboratory is a uniquely well-suited place in an undergraduate curriculum for allowing students to participate in an original research experience while they continue to acquire basic knowledge and skills. The motivations for planning such a student laboratory are discussed, and the manner in which this laboratory was implemented is described. The students carried out experimental measurements, reduced data, did literature surveys, and presented their results in the form of original research papers. The class was divided into a number of small groups. Each group was given a different rare earth alloy or metal to study. Measurements were made of electrical and mechanical properties. Data taken by each group were made available to the whole class. The laboratory is subjectively evaluated as a teaching/learning experience.
Quantum fact and fiction. IV
Authors: Landé Alfred
Published: March 2005

Niels Bohr has often pointed out that already the simplest quantum rule, ΔE = hν, is irrational insofar as ΔE stands for a timeless energy jump, whereas a frequency ν is defined only over a long time span. However, when this irrational relation is accepted as a mainstay of the quantum theory, one cannot reject a corresponding irrationality for momentum jumps Δp connected with periodicities in space, the less so as it yields a unitary mechanical explanation of all wavelike-looking phenomena of matter, in particular those of the diffraction of electrons, without resorting to any wave interference in space. (This has nothing to do with the complex–imaginary wave function ψ, which has a purely statistical significance.) We therefore propose to regard matter particles as real physical entities as always, in contrast to the matter waves with λ = h/p as a suggestive yet expendable fiction, permitting a return from dualism to unity, a simplification of the customary interpretation of standard quantum effects, also suggesting a long overdue reform in the teaching of the elements of quantum mechanics.

Editor’s note: This is the fourth and last in a series of articles begun ten years ago in this Journal. Earlier parts in the series may be found in American Journal of Physics 33, 123 (1965); 34, 1160 (1966); and 37, 541 (1969).
Microwave Faraday rotation
Authors: Yan Kam L. , Lonc W. P.
Published: March 2005

By utilizing only commonly available microwave components and instruments, construction and performance details are given for a system capable of demonstrating the Faraday rotation effect at microwave frequencies with satisfactory quantitative results.
Graphical approach to dispersion
Authors: York Derek
Published: March 2005

The elementary, graphical technique of Cornu is systematically applied to the problem of the dispersion of waves. A number of classical results are obtained in a manner which helps to clarify the concepts of dispersion and group velocity.
Quantum solution for the biharmonic oscillator
Authors: Gettys W. Edward , Graben H. W.
Published: March 2005

The quantum-mechanical solution for the biharmonic oscillator is presented. This one-dimensional asymmetric oscillator is described by the potential energy function V(x)  = mω12x2/2, x ≳ 0, and V(x)  = mω22x2/2, x < 0. One of the more interesting features of the solution is that the energy levels are very nearly equally spaced. The biharmonic oscillator provides a relatively simple model for systems which lack the symmetry of the harmonic oscillator.
Parallels between relativistic and classical dynamics for introductory courses
Authors: Fahnline Donald E.
Published: March 2005

Rewriting the usual equation KE =  (m − m0)c2 for relativistic kinetic energy in the form KE = [m/m + m0)]mv2 helps students recognize its relation to classical kinetic energy; similar parallels between the equations for relativistic one-dimensional constant force motion and the equations for classical uniformly accelerated motion are equally helpful. In particular, these parallels facilitate the derivation of the relativistic equations for constant force motion and kinetic energy by means of simple algebraic generalizations of proofs often used in teaching their classical analogs to students who have not studied calculus.
Sinota: A concise scientific notation
Authors: Butler Crispin O.
Published: March 2005

Sinota, a complete, convenient notation for physical quantity, is presented in this article. Application of this notation in problem solving is demonstrated with emphasis on pedagogy. Specific advantages of Sinota are seen to derive from both its simplicity and its structure. Useful modifications of Sinota are presented.
Improving tests in basic physics
Authors: Coulter Byron L.
Published: March 2005

Simple procedures for improving the reliability and the validity of tests in basic physics are discussed.
Displacement current and Maxwell’s equations
Authors: Rosser W. G. V.
Published: March 2005

The roles of the displacement and conduction currents in Maxwell’s equations are interpreted in a way consistent with the retarded potentials, according to which the displacement current in empty space should not be included as one of the sources of the magnetic field when the vector potential is calculated.
Electrets and electrostatic measurement
Authors: Varney R. N. , Hahn H. T.
Published: March 2005

Electrets, the electrical counterparts of magnets, have been known for a full 50 years but have not found their way into undergraduate physics. In simplest form, they are polarized dielectrics that are permanent on a scale of months. Procedures are described for making electrets out of plastic sheets like Mylar, for testing them and measuring their pole strength, and for establishing necessary and sufficient demonstrations that they are not simply surface charged.
Fields of moving charges
Authors: Arista N. , Lopez A.
Published: March 2005

It is shown that one can view the magnetic interaction between a moving charged particle and a current-carrying wire, as originating in the electric force between charges, by performing a Lorentz transformation to a system in which the charge carriers are at rest. This is suggested as an alternative to the discussion in Vol. II of the Berkeley Physics Course. The fields of the wire as seen by an observer moving with the test particle are used to discuss Faraday’s law in differential form for a nonstationary case.
Experimental search for anisotropy in the speed of light
Authors: Newburgh Ronald G. , de Beauregard Olivier Costa
Published: March 2005

It is shown on the basis of a forgotten nineteenth century principle of Potier and Veltmann that an interferometric experiment cannot demonstrate a first-order ether wind. The relation of the Fresnel drag law to the Einstein velocity composition law is reviewed.
Completeness of the energy eigenstates for a delta function potential
Authors: Damert William C.
Published: March 2005

By explicit calculation it is shown that the eigenfunctions of a particular Hamiltonian are complete. The Hamiltonian considered is that for a particle moving in one dimension with a Dirac delta function potential.
Lifetimes of the A2Π state of CO+ and the A2Δ state of CH
Authors: Anderson Richard , Jursich Mark
Published: March 2005

The simple apparatus described in this article has been used to measure the lifetime of the A2Π state of CO+ and the A2Δ state of CH. The results of this experiment give results consistent with previous studies for lifetimes. Collisional quenching slopes are given for the CO+ (2,0) band for the A2Π–X2Σ transition and the CH (0,0), (1,1), and (2,2) bands for the A2Δ–X2Π transition. This is an excellent experiment, demonstrating the exponential decay of excited molecular systems.
Some experiments with biological applications for the elementary laboratory
Authors: Kammer D. W. , Williams J. A.
Published: March 2005

Many departments are attempting to modify the elementary physics course to include applications of physics in areas of interest to the students. This paper gives summaries of laboratory experiments with applications in the biological sciences. The topics summarized are the mechanics of the human arm, fluid flow in tubes, physics of hearing, and the electrocardiograph. Also, mention is made of other suitable experiments: nerve impulse conduction and corrective lenses for eye defects.
On the theory of an electrostatic pendulum oscillator
Authors: Asano Kazutoshi
Published: March 2005

An electrostatic pendulum oscillator was theoretically analyzed. In this theory, infinitely large electrodes are assumed, so that the electric force can be approximated by a constant for small angles of pendulum motion. The charge acquired by a sphere was calculated by both approximation and numerical method. Then the relationship between applied voltage and frequency was obtained, which might be approximated by a linear relation at higher voltage. The theory was compared with the experimental results of Martin and Longbrake. Even though the electrode configuration is different, the theory agreed reasonably well with the experimental data. Further improvement of the theory is suggested.
Phase shifts of the three-dimensional spherically symmetric square well potential
Authors: Meijer Paul H. E. , Repace James L.
Published: March 2005

Although the general properties of the phase shift of the three-dimensional spherically symmetrical square well potential are described in most textbooks on quantum mechanics, specific graphical representations of this function are rare. In this paper we present a number of phase shifts, as a function of energy, for the various values of the angular momentum quantum number. We discuss the general features of these curves. In particular, we consider what happens to the phase shifts if one varies the depth of the well, not only for near-zero energy, but for the entire range of energies. We describe how the bound levels of a deep well are related to the virtual levels of the shallow well. We find points of triple coincidence for curves belonging to three successive l values for given well depth. A proof of this phenomenon is given.
Use of loci in ac circuits
Authors: Douglas D. G.
Published: March 2005

This paper discusses and illustrates the use of loci in the complex plane to illuminate the behavior of steady-state ac circuits. Phase and amplitude dependence on a chosen parameter are illustrated with twelve examples.
Simple iterative procedures for solving transcendental equations with the ’’electronic slide rule’’
Authors: McKelvey J. P.
Published: March 2005

It is shown that very simple iteration routines for solving a very broad class of transcendental equations, including many of great importance in physical applications, can be developed and used quite conveniently with pocket calculators such as the Hewlett−Packard HP−35 and others of similar capability. Questions of convergence and methods of extending domains of convergence are discussed. While the methods considered are not new to mathematicians and computer scientists, it does not seem to be generally appreciated that they may be so easily and systematically used with machines of this class. While it is true that some repetitive key punching is required, this is not usually very tedious; the solution of most equations is accomplished with the ease (and within the time span) of typing a three or four line paragraph on a typewriter, once the routine is developed. Some of the procedures considered can also be used for the solution of systems of simultaneous transcendental equations. The methods which are used are extremely convenient and practical when a few or even a few dozen transcendental equations are to be solved. If there are a few hundred, however, it is probably best to use the IBM 360!
An exact treatment of the Dirac delta function potential in the Schrödinger equation
Authors: Atkinson Daniel A. , Crater Horace W.
Published: March 2005

This paper presents several cases in which the effects of the addition of a delta function potential on bound states can be computed exactly. In the case of the one dimensional Schrödinger equation, a Green’s function technique is used to compute an exact implicit expression that gives the effect of the one−dimensional delta function potential on the bound states eigenvalues. It is also shown that the weak coupling limit of the implicit expression agrees with the perturbative treatment of the delta function. It is pointed out that this technique cannot be applied to obtain an exact treatment of the delta function potential δ3(r) in the three−dimensional Schrödinger equation. Instead, an alternate definition of the delta function in three dimensions as a limit of a sequence of square well potentials is used. Unlike the one dimensional case, the exact effect on the eigenvalue does not agree in the limit of weak coupling with the perturbative results. This indicates that the three−dimensional delta function potential should not be used to approximate strongly coupled short range potentials for which perturbation theory is inadequate.
The Debye model in n dimensions
Authors: Valladares Ariel A.
Published: March 2005

An n−dimensional Debye model is analyzed and solved obtaining the phonon density of states, the phonon energy and the lattice specific heat, thus providing a unified approach to the teaching of this model. Cases with n=1, 2, and 3 are explicitly considered.
An electronics course emphasizing circuit design
Authors: Bergeson Haven E.
Published: March 2005

Through the use of a variety of inexpensive integrated circuits, students in a one−quarter introductory electronics course are able to design a large number of different types of useful circuits. Students design from very simple models of circuit behavior with complications treated as perturbations. The general approach is described and then its use is shown in a number of analog and digital applications.
Instant replay and the graduate teaching assistant
Authors: Mozer Forrest S. , Napell Sondra M.
Published: March 2005

An innovative course for graduate teaching assistants at the University of California at Berkeley aims to familiarize %TAs with techniques besides lecturing (i.e., question−and−answer; discussion; small−group problem−solving) and to demonstrate how teachers’ classroom behaviors affect students’ learning. The format is threefold: (1) Each TA is videotaped while teaching; (2) each analyzes his videotape privately and with the instructor; (3) weekly seminars are held. The authors concluded that, as a result of this course: (1) TAs felt freer to experiment with a variety of techniques; (2) verbal interaction between students and TAs and among students increased; (3) TAs’ behavior changes were noted and appreciated by students.
Conservation of angular and linear momentum on an air table
Authors: Rockefeller Roger R.
Published: March 2005

A laboratory experiment that demonstrates the simultaneous conservation of angular and linear momentum is described. A disk is positioned on an air table, and pellets from an air pistol are fired at a target on the disk. The resulting motion of the disk validates the conservation of momentum laws but violates the expectations of the observer.
Two new graphic computer dialogs for teachers
Authors: Arons Arnold , Bork Alfred
Published: March 2005

We describe a pair of interactive computer–student dialogs developed for use primarily with elementary and high school teachers. The dialogs use graphic facilities for teaching about the sky as seen from the earth and about the phases of the moon. The primary aim is for the teachers to understand the nature of a scientific model, in this case the model of the phases of the moon, through a Socratic interaction with the computer. The dialogs are also being used by other university students.
Student field mill
Authors: Layton R. G. , O’Dell K. D.
Published: March 2005

Field mills have been used for years to measure atmospheric electric fields. Inexpensive operational amplifiers have made possible an inexpensive and simple version of this device that is suitable for use in the classroom and instructional laboratory. The field mill allows new and exciting electrostatics experiments to be performed, in addition to breathing new life into many standard ones. [The apparatus described in this article was second prize winner in the College Instructional Laboratory category of the 1975 AAPT Apparatus Competition—Editor]
Blackbody radiation from a single-mode source: A demonstration
Authors: Dahm A. J. , Langenberg D. N.
Published: March 2005

Blackbody radiation emitted or absorbed by a single microwave cavity mode is detected and the signal displayed on an oscilloscope using a relatively straightforward technique.
A course in physics of human motion
Authors: Halley J. W. , Eaton B.
Published: March 2005

A course in elementary mechanics especially designed for students of athletics and dance is described. The course has been taught for two years at the University of Minnesota. Innovative features include a gymnasium laboratory utilizing an inexpensive photographic technique for analysis of human motion. The order of presentation and the selection of topics, as well as the illustrative examples, are all unconventional in an elementary mechanics course. Student response is described.
Multipurpose physics learning center: A working model
Authors: Prigo R. B. , Korda A. , Walker W. C.
Published: March 2005

A recently instituted Physics Learning Center is described and evaluated. Innovations in the use of the facility include self-paced student observation of phenomena, ’’PLC homework problems,’’ and extracurricular use by off-campus groups.
On the integral equations for electromagnetic scattering
Authors: Ström Staffan
Published: March 2005

In the present article we discuss several volume and surface integral expressions for an electromagnetic field in the presence of a scatterer of finite extension, with special emphasis on a description of the scattering by means of a transition matrix.
Relativistic description of a rotating disk
Authors: Gro/n O/.
Published: March 2005

A consistent relativistic kinematic description of a rotating disk is given. The disk is described from the point of view of an inertial observer momentarily at rest relative to a point on the periphery of the disk, and as observed in a coordinate system SS′ rotating with the disk. The kinematic resolution of Ehrenfest’s paradox is stated. Also the following elements of the description are analyzed: (a) the transformation of time from an inertial system, where the axis of the disk is at rest, to SS′; (b) the spatial geometry in SS′; and (c) the velocity of light in SS′. The procedure for synchronization of the coordinate clocks on the disk is stated explicitly.
On a curiosity arising from Fizeau’s experiment
Authors: Lerche I.
Published: March 2005

We show that for a cold plasma moving at velocity v there is no change in the velocity of light to first order in v over that obtaining if the plasma is at rest. We also give the general dependence of refractive index on frequency in order that there be no Fizeau effect [to O(v)] for a medium in motion, and we show that this implies that the product of the phase velocity and the group velocity must equal c2. We also give the physical reason for the absence of the first-order Fizeau effect in terms of the local dipole polarization and the different wave frequency seen by the moving dipoles compared to the incident wave frequency.
Extracting a Climate Signal from 169 Glacier Records
Authors: Oerlemans J.
Published: March 2005

I constructed a temperature history for different parts of the world from 169 glacier length records. Using a first-order theory of glacier dynamics, I related changes in glacier length to changes in temperature. The derived temperature histories are fully independent of proxy and instrumental data used in earlier reconstructions. Moderate global warming started in the middle of the 19th century. The reconstructed warming in the first half of the 20th century is 0.5 kelvin. This warming was notably coherent over the globe. The warming signals from glaciers at low and high elevations appear to be very similar.
Use of Diagnostic Microarrays for Determination of Virulence Gene Patterns of
Escherichia coli
K1, a Major Cause of Neonatal Meningitis
Authors: Korczak Bożena , Frey Joachim , Schrenzel Jacques , Pluschke Gerd , Pfister Riccardo , Ehricht Ralf , Kuhnert Peter
Published: March 2005

Forty
Escherichia coli
strains isolated primarily from neonatal meningitis, urinary tract infections and feces were screened for the presence of virulence genes with a newly developed microarray on the array tube format. A total of 32 gene probes specific for extraintestinal as well as intestinal
E. coli
pathotypes were included. Eighty-eight percent of the analyzed strains were positive for the K1-specific probe on the microarray and could be confirmed with a specific antiserum against the K1 capsular polysaccharide. The gene for the hemin receptor ChuA was predominantly found in 95% of strains. Other virulence genes associated with K1 and related strains were P, S, and F1C fimbriae specific for extraintestinal
E. coli
, the genes for aerobactin, the α-hemolysin and the cytotoxic necrotizing factor. In two strains, the O157-specific catalase gene and the gene for the low-molecular-weight heat-stable toxin AstA were detected, respectively. A total of 19 different virulence gene patterns were observed. No correlation was observed between specific virulence gene patterns and a clinical outcome. The data indicate that virulence genes typical of extraintestinal
E. coli
are predominantly present in K1 strains. Nevertheless, some of them can carry virulence genes known to be characteristic of intestinal
E. coli
. The distribution and combination of virulence genes show that K1 isolates constitute a heterogeneous group of
E. coli.
First Description ofCurtobacteriumspp. Isolated from Human Clinical Specimens
Authors: Funke Guido , Aravena-Roman Max , Frodl Reinhard
Published: March 2005

During a 4-year period, five strains (three of which were doubtless clinically significant) of yellow- or orange-pigmented, oxidative, slowly acid-producing coryneform bacteria were recovered from human clinical specimens in two reference laboratories or referred to them. The strains were motile, catalase positive, nitrate reductase negative, and urease negative, but strongly hydrolyzed esculin. In all reference and clinical strains described in the present study, anteisopentadecanoic (C15:0ai) and anteisoheptadecanoic (C17:0ai) acids represented more than 75% of all cellular fatty acids except in one clinical strain and inCurtobacterium pusillum, in which both the unusual ω-cyclohexyl fatty acid (identified as C18:1ω7cis/ω9cis/ω12transby the Sherlock system) represented more than 50% of all cellular fatty acids. In all clinical strains, ornithine was the diamino acid of the cell wall, the interpeptide bridge consisted of ornithine, and acetyl was the acyl type of the peptidoglycan. Therefore, the five clinical strains were unambiguously identified asCurtobacteriumspp. Analyses of the complete 16S rRNA genes of the five clinical strains with homologies to the establishedCurtobacteriumspecies ranging from 99.2 to 100% confirmed the identifications asCurtobacteriumspp. Data on the antimicrobial susceptibility pattern of curtobacteria are reported, with macrolides and rifampin showing very low MICs for all strains tested. This report is the first on the isolation ofCurtobacteriumstrains from human clinical specimens.
Multiplex PCR Assay for Rapid Identification of Oculopathogenic Adenoviruses by Amplification of the Fiber and Hexon Genes
Authors: Banik Urmila , Adhikary Arun Kumar , Suzuki Eiko , Inada Toshiki , Okabe Nobuhiko
Published: March 2005

Eye infections caused by adenovirus (Ad) often result in nosocomial infections and community epidemics with significant rates of morbidity. No antiviral agent effective against Ad is yet available for clinical use. Therefore, early diagnosis is still the mainstay for patient management and the prevention of epidemics. A multiplex PCR assay based on amplification of a combination of the fiber and hexon genes which can identify the six important oculopathogenic serotypes of Ads (Ad serotype 3[Ad3], Ad4, Ad7, Ad8, Ad19, and Ad37) in a single-tube amplification reaction was developed. Ad serotypes could be distinguished by the different amplicon sizes. The assay correctly identified prototype strains as well as isolates in clinical specimens. In comparison with a previously described PCR-restriction fragment polymorphism method, our assay gave unequivocal results for clinical specimens. Our multiplex PCR has the potential to serve as a rapid and cost-effective tool for the typing of important ocular Ads.
Sensitive and Specific Detection of Staphylococcal Epidermolysins A and B in Broth Cultures by Flow Cytometry-Assisted Multiplex Immunoassay
Authors: Joubert Olivier , Keller Daniel , Pinck Anne , Monteil Henri , Prévost Gilles
Published: March 2005

Two of the most common bacterial skin infections of young infants and children are bullous impetigo due to
Staphylococcus aureus
and its more acute form, staphylococcal scalded skin syndrome. Epidermolysin A (ETA), ETB and, possibly, ETD are responsible for these diseases, which may appear as epidemics in pediatric patients. We tested the reliability of a flow cytometry-assisted multiplex immunoassay (Bio-Plex system) for the detection of ETA and ETB. The Bio-Plex system was found to be highly specific and highly sensitive for toxin concentrations of between 2 and 80,000 pg/ml. The results of this assay were 100% identical to the results of a PCR-based method. We demonstrated that this test did not generate any cross-reactions with ETD-producing isolates. The level of detection of ETB by this test differed according to culture conditions and from isolate to isolate; these results must be taken into account for diagnostic purposes.
Evaluation of Four Commercially Available Extended-Spectrum Beta-Lactamase Phenotypic Confirmation Tests
Authors: Linscott Andrea J. , Brown William J.
Published: March 2005

Extended-spectrum beta-lactamase (ESBL) production in members of the
Enterobacteriaceae
can confer resistance to extended-spectrum cephalosporins, aztreonam, and penicillin. As such, the accurate detection of ESBL producers is essential for the appropriate selection of antibiotic therapy. Twenty previously characterized isolates and 49 clinical isolates suspected of ESBL production were tested by four ESBL phenotypic confirmatory methods for accuracy and ease of use. The four ESBL phenotypic confirmation tests included Dried MicroScan ESBL
plus
ESBL Confirmation panels (Dade Behring, Inc., West Sacramento, Calif.), Etest ESBL (AB BIODISK, Piscataway, N.J.), Vitek GNS-120 (bioMérieux, Inc., Hazelwood, Mo.), and BD BBL Sensi-Disk ESBL Confirmatory Test disks (BD Biosciences, Sparks, Md.). Results were compared to frozen microdilution panels prepared according to NCCLS specifications, and discrepant isolates were sent for molecular testing. The test sensitivities for the ESBL phenotypic confirmatory test methods used in this study were as follows: MicroScan ESBL
plus
ESBL confirmation panel, 100%; VITEK 1 GNS-120, 99%; Etest ESBL, 97%; and BD BBL Sensi-Disk ESBL Confirmatory Test disks, 96%. The test specificities were as follows: BD BBL Sensi-Disk ESBL Confirmatory Test disks, 100%; MicroScan ESBL
plus
ESBL confirmation panel and VITEK 1 GNS-120, 98%; and Etest ESBL, 94%. All methods were easy to perform; however, the Etest method required more expertise to interpret the results. All tests offer a feasible solution for confirming ESBL production in the clinical laboratory.
Multiplex Real-Time PCR Assay Using Scorpion Probes and DNA Capture for Genotype-Specific Detection of
Giardia lamblia
on Fecal Samples
Authors: Ng Cherie T. , Gilchrist Carol A. , Lane Ariel , Roy Shantanu , Haque Rashidul , Houpt Eric R.
Published: March 2005

Two major genotypic assemblages of
Giardia lamblia
infect humans; the epidemiologic significance of this phenomenon is poorly understood. We developed a single-vessel multiplex real-time PCR (qPCR) assay that genotypes
Giardia
infections into assemblages A and/or B directly from fecal samples. The assay utilized Scorpion probes that combined genotype-specific primers and probes for the 18S rRNA gene into the same molecule. The protocol was capable of detecting as few as 20 trophozoites per PCR on fecal DNA isolated using a commercial method or 1.25 trophozoites per PCR on fecal DNA isolated using a
G. lamblia
-specific oligonucleotide capture technique. The assay was specific for fecal specimens, with no amplification of the discordant genotype with the opposite Scorpion probe. When 97 clinical specimens from Bangladesh were used, the multiplex PCR assay detected 95% (21 of 22) of
Giardia
microscopy-positive specimens and 18% (13 of 74) of microscopy-negative specimens. Microscopy-negative and qPCR-positive specimens had higher average cycle threshold values than microscopy-positive and qPCR-positive specimens, suggesting that they represented true low-burden infections. Most (32 of 35) infections were assemblage B infections. This single-reaction multiplex qPCR assay distinguishes assemblage A
Giardia
infections from assemblage B infections directly on fecal samples and may aid epidemiologic investigation.
LeishmaniaPromastigote Membrane Antigen-Based Enzyme-Linked Immunosorbent Assay and Immunoblotting for Differential Diagnosis of Indian Post-Kala-Azar Dermal Leishmaniasis
Authors: Saha Samiran , Mazumdar Tuhina , Anam Khairul , Ravindran Rajesh , Bairagi Bibhas , Saha Bibhuti , Goswami Ramapada , Pramanik Netai , Guha Subhashis K. , Kar Sourjya , Banerjee Dwijadas , Ali Nahid
Published: March 2005

Diagnosis of post-kala-azar dermal leishmaniasis (PKDL), caused byLeishmania donovani, is difficult, as the dermal lesions are of several types and resemble those caused by other skin diseases, especially leprosy. Since the disease generally appears very late after the clinical cure of kala-azar in India, it is also difficult to correlate PKDL with a previous exposure toL. donovani. Very few attempts have been made so far to diagnose PKDL serologically, and the diagnostic methods vary in their sensitivities and specificities. Diagnosis of PKDL through sophisticated PCR methods, although highly sensitive, has limited practical use. We have developed a serodiagnostic method using an enzyme-linked immunosorbent assay to detect specific immunoglobulin (Ig) isotypes and IgG subclass antibodies in the sera of Indian PKDL patients. Our assay, which usesL. donovanipromastigote membrane antigens, was 100% sensitive for the detection of IgG and 96.7% specific for the detection of IgG and IgG1. Optical density values for individual patients, however, demonstrated wide variations. Western blot analysis based on IgG reactivity could differentiate patients with PKDL from control subjects, which included patients with leprosy, patients from areas where kala-azar is endemic, and healthy subjects, by the detection of polypeptides of 67, 72, and 120 kDa. The recognition patterns of the majority of serum samples from patients with PKDL were also distinct from those of the serum samples from patients with visceral leishmaniasis (VL), at least for a 31-kDa polypeptide. To further differentiate patients with PKDL from those with active and cured VL, we analyzed the specific titers of the Ig isotypes and IgG subclasses. High levels of IgG, IgG1, IgG2, and IgG3 antibodies significantly differentiated patients with PKDL from patients cured of VL. The absence of antileishmanial IgE and IgG4 in patients with PKDL differentiated these patients from those with active VL. These results imply intrinsic differences in the antibodies generated in the sera from patients with PKDL and VL.
Cytotoxin and Pyrogenic Toxin Superantigen Gene Profiles of
Staphylococcus aureus
Associated with Subclinical Mastitis in Dairy Cows and Relationships with Macrorestriction Genomic Profiles
Authors: Fueyo J. M. , Mendoza M. C. , Rodicio M. R. , Muñiz J. , Alvarez M. A. , Martín M. C.
Published: March 2005

A set of 84
Staphylococcus aureus
isolates collected from the milk of cows with subclinical mastitis in Asturias (a cattle region of Spain) and six control strains were tested for sequences of genes encoding hemolysins (
hla
,
hlb
,
hld
,
hlg
, and
hlg-2
), leukotoxins (
lukPV
,
lukM
, and
lukED
), toxic shock syndrome toxin (
tst
), and enterotoxins (
sea
to
see
,
seg
to
ser
, and
seu
) by conventional and multiplex PCR. It was found that 84, 83, 11, and 39 isolates carried some type of
hl
,
luk
,
tst
, or
se
gene, respectively, which were arranged in 14 exotoxin genotypes. All of the isolates were negative for
lukPV
,
hlg
,
sea
,
sed
,
see
,
sej
,
sek
,
sep
,
seq
, and
ser
. Two gene groupings could be related with pathogenicity islands—[
lukED
,
seg
,
sei
,
sem
,
sen
,
seo ± seu
] with Saβ-1 and [
tst
,
sec
,
sel
] with SaPIbov, present in 45 and 13.1% of the isolates, respectively—while 11.9% of them carried both islands. Only one contained
seb
(together with υSaβ-1), and another contained
seh
(together with
lukED)
. The isolates were also analyzed by pulsed-field gel electrophoresis performed with SmaI. Thirty-nine SmaI profiles (similarity coefficient [
S
] = 0.94 to 0.21) were differentiated; 12, 1, and 10 of these, respectively, were generated by isolates presumptively carrying Saβ-1, SaPIbov, or both. Five SmaI profiles (
S
≥ 0.8) formed a cluster, which contained 20 and 10 isolates carrying one (υSaβ-1) or both islands. These data show the high frequency of genes encoding cytotoxins and pyrogenic toxin superantigens, their relationship with pathogenicity islands, and their distribution among a diversity of genetic types of
S. aureus
related to subclinical mastitis.
External Quality Assessment for Detection of
Chlamydia trachomatis
Authors: Chalker V. J. , Vaughan H. , Patel P. , Rossouw A. , Seyedzadeh H. , Gerrard K. , James V. L. A.
Published: March 2005

The use of molecular methods for detection of
Chlamydia trachomatis
is increasing in clinical laboratories. External quality assessment enables unbiased monitoring of the performance of laboratories in the detection of specific pathogens. This study details the results of molecular and enzyme immunosorbent assay (EIA) testing for
C. trachomatis
detection in simulated endocervical swab specimens recently distributed internationally by United Kingdom National External Quality Assessment Scheme for Microbiology (UK NEQAS for Microbiology) external quality assessment panels. The frequency of accurate detection of
C. trachomatis
in the panels ranged from 32 to 100%. Participants using molecular methods were significantly more likely to detect
C. trachomatis
in specimens than those using an EIA. Two strains were distributed with the panels: an L2 laboratory-adapted strain and an uncharacterized primary isolate. Further analysis indicated a difference in detection of
C. trachomatis
between specific methods only with the L2 strain at lower concentrations. In addition, eight negative specimens were distributed, and false positives were found to be rare by all methods included in the study.
Molecular Epidemiology ofShigella flexneriin a Long-Stay Psychiatric Nursing Center during 2001 to 2003
Authors: Lee Yeong-Sheng , Liu Ming-Ching , Ko Ching-Fen , Lu Cheng-Hsiung , Tseng Yi-Hsiung
Published: March 2005

With six separate wards accommodating more than 1,600 patients, V Nursing Center (VNC) is a long-stay psychiatric nursing center in eastern Taiwan. During 2001 to 2003, 39 shigellosis cases occurred in VNC. Different from the notion that most cases of shigellosis are caused byShigella sonnei, all except one of these cases were caused byS. flexneri, with the remaining one caused by anS. sonneiisolate. O-antigen serotyping showed that the 38S. flexneristrains were of either type 1a (n= 20) or 4a (n= 18), two less prevalent serotypes in Taiwan. NotI-based pulsed-field gel electrophoresis analyses performed with 8 type 1a non-VNC strains and 9 type 4a non-VNC strains isolated from 1996 to 2003 for comparison divided the 28 type 1a strains and the 27 type 4a strains into 7 and 10 subtypes, designated subtypes P1A to P1G and subtypes P4A to P4J, respectively. Subtypes P1A and P4A, which appeared in three consecutive years in VNC as well as outside of VNC, are the most prevalent subtypes. Analyses of the relatedness of the VNC strains on the basis of the banding patterns grouped the type 1a and 4a strains into four and five clusters, respectively. All except one of the type 1a strains had 95% similarity, indicating that they had a common parent, whereas the type 4a strains had similarities that ranged from 77 to 93%, suggesting that they were of diverse origins. In two of the outbreaks, less related subtypes of the type 4a strains were found in the same VNC wards in consecutive years, suggesting the possible existence of different subtypes in VNC all the time. Antibiotic susceptibility testing showed that all except one of theS. flexneristrains were sensitive to at least seven antibiotics; the remaining isolate was sensitive to three antibiotics. The data from the latter tests should be helpful for selection of proper treatments forS. flexneriinfections in Taiwan.
Loss of themecAGene during Storage of Methicillin-ResistantStaphylococcus aureusStrains
Authors: van Griethuysen Arjanne , van Loo Inge , van Belkum Alex , Vandenbroucke-Grauls Christina , Wannet Wim , van Keulen Peter , Kluytmans Jan
Published: March 2005

ThemecAgene was lost in 36 (14.4%) of 250 methicillin-resistantStaphylococcus aureusisolates after 2 years of storage at −80°C with the Microbank system (Pro-lab Diagnostics, Austin, Tex.). Further analysis of 35 of these isolates confirmed loss of themecAgene in 32 isolates. This finding has important implications for the management of strain collections.
BK and JC Polyomaviruses Are Not Associated with Idiopathic Pulmonary Fibrosis
Authors: Procop G. W. , Kohn D. J. , Johnson J. E. , Li H. J. , Loyd J. E. , Yen-Lieberman B. , Tang Y. W.
Published: March 2005

We sought to determine if the BK and JC polyomaviruses were associated with idiopathic pulmonary fibrosis (IPF). We did not detect the BK or JC polyomaviruses in lung tissue extracts from 33 patients with IPF by using real-time PCR, which suggests that an etiologic association is unlikely.
Presence of DNA of Human Papillomavirus 16 but No Other Types in Tumor-Free Tonsillar Tissue
Authors: Chen Renwei , Sehr Peter , Waterboer Tim , Leivo Ilmo , Pawlita Michael , Vaheri Antti , Aaltonen Leena-Maija
Published: March 2005

According to PCR, the prevalences of human papillomavirus (HPV) DNA were 6.3% (13 of 206) in tonsillitis or hypertrophic tonsillar tissues and 0.6% (1 of 174) in exfoliated cells from normal tonsils. HPV-16 was the only type detected in tonsillar tissues, but it did not appear to lead to L1 antibody production.
The
pls
Gene Found in Methicillin-Resistant
Staphylococcus aureus
Strains Is Common in Clinical Isolates of
Staphylococcus sciuri
Authors: Juuti Katri , Ibrahem Salha , Virolainen-Julkunen Anni , Vuopio-Varkila Jaana , Kuusela Pentti
Published: March 2005

pls
, a gene found in type I staphylococcal cassette chromosome
mec
(SCC
mec
) regions of methicillin-resistant
Staphylococcus aureus
strains, was present in 12 of the 15 human clinical
Staphylococcus sciuri
isolates studied. Pls was expressed in the
S. sciuri
isolates, although at a lower level than in
S. aureus
. Other parts of SCC
mec
could also be found in the
S. sciuri
genome.
Genetic Variability among Serotype G4 Italian Human Rotaviruses
Authors: Arista S. , Giammanco G. M. , De Grazia S. , Colomba C. , Martella V.
Published: March 2005

A total of 254 serotype GH rotavirus strains were detected in Palermo, Italy, from 1985 to 2003. Out of 38 serotype G4 strains selected for genetic analysis, 14 were recognized by genotyping as type G9. Strains confirmed to belong to the G4 type showed temporal patterns of genetic evolution in their VP7 and VP4 gene sequences, and the latest Italian G4 strains were distantly related to the reference vaccinal ST3 strain.
Sugars Inhibit Expression of the Rugose Phenotype of
Vibrio cholerae
Authors: Ali Afsar , Morris J. Glenn , Johnson Judith A.
Published: March 2005

Vibrio cholerae
can shift to a rugose colony phenotype, reflecting expression of an exopolysaccharide that provides protection against a variety of environmental stresses. Our data indicate that expression of the rugose phenotype is inhibited by a variety of sugars, including sucrose, dextrose, arabinose, fructose, and maltose. Inhibition by sucrose may be one factor in explaining the failure of rugose strains to grow on thiosulfate citrate bile salts sucrose agar, the primary selective medium for
V. cholerae
.
Differentiation between Atypical Isolates of
Candida lusitaniae
and
Candida pulcherrima
by Determination of Mating Type
Authors: Noël Thierry , Favel Anne , Michel-Nguyen Annie , Goumar Abdelhak , Fallague Karim , Chastin Christiane , Leclerc Florence , Villard Jean
Published: March 2005

We report on five clinical isolates routinely identified as
Candida lusitaniae
that the ID 32C system was unable to discriminate from the closely related species
Candida pulcherrima
. When additional tests did not allow accurate identification, the less usual mating type test identified all of them as
Clavispora lusitaniae
. Mating type testing appears to be a valuable tool for assessing the true incidence of this emerging non-
albicans Candida
species.
Dihydropteroate Synthase and Novel Dihydrofolate Reductase Gene Mutations in Strains of
Pneumocystis jirovecii
from South Africa
Authors: Robberts F. J. L. , Chalkley L. J. , Weyer K. , Goussard P. , Liebowitz L. D.
Published: March 2005

Dihydropteroate synthase (DHPS) gene mutations have raised concerns about emerging sulfonamide resistance in
Pneumocystis jirovecii
. DHPS and dihydrofolate reductase (DHFR) gene products were amplified in clinical specimens from South African patients. One of 53 DHPS genes sequenced contained the double mutation Thr55Ala Pro57Ser. DHFR gene mutations detected were Ala67Val and the new mutations Arg59Gly and C278T.