bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantifying spatial classification uncertainties of the historical Wisconsin landscape (USA)
Authors: Bolliger Janine , Mladenoff David J.
Published: March 2005

Landscape feature can be classified by creating categories based on aggregation of spatially explicit information. However, many landscape features appear continuous rather than discrete. The aggregation process likely involves loss of information and introduces a variety of uncertainties whose degree and extent may differ spatially. Since landscape classifications have found wide application in e.g. natural resource policies or ecological research, assessments of spatial classification uncertainties are required.

We present a quantitative framework to identify the degree of landscape continuity (fuzziness) and structure (categorization) based on fuzzy classification and offer measures to quantify uncertainties originating from aggregating features into categories. Fuzzy classification is a non‐hierarchical, quantitative method of assessing class definitions using degrees of association between features and class. This results in classes which are well defined and compositionally distinct, as well as classes which are less clearly defined but which, to various degrees, share characteristics with some or all classes. The spatial variation in the degree of class definition on the landscape is used to assess classification uncertainties. The two aspects of uncertainty investigated are the degree of association of a feature with the overall class definitions (membership diffusion), and the class‐specific degree of association of each pixel on the landscape with each class (membership saturation).

Three classification scenarios, one fuzzy and one discrete, of the historical landscape of Wisconsin (USA) were compared for spatial classification uncertainties. Membership diffusion is highest in topographically heterogeneous environments, or areas characterized by many species occupying similar ecological niches. Classification uncertainties for individual classes show that differentiated species distributions can be identified, not only distribution centers.
SARS: coping with the impact at a community hospital
Authors: Tolomiczenko George S. , Kahan Meldon , Ricci Maria , Strathern Lynne , Jeney Christa , Patterson Karen , Wilson Lynn
Published: March 2005

Aim.  This paper presents the findings of a staff survey conducted at a 350‐bed acute care facility located on the periphery of Toronto, Canada.

Background.  Toronto's severe acute respiratory syndrome (SARS) crisis resulted in trauma‐like effects at hospitals hardest hit by the disease. A systematic examination of the impact on staff working in hospitals that saw relatively few cases, while maintaining the precautions associated with elevated alert levels, has not been undertaken.

Methods.  A questionnaire was distributed for 1 month commencing 17 April 2003 and 300 completed responses were obtained (approximately one in six staff members). The data collected included demographic and occupational information, in addition to perceptions of SARS’ impact on patient care, factors contributing to adverse impacts on patient care, working conditions, decision‐making, communication and relations, sources of support, and the impact on workers’ lives outside work. Items for these sections were developed by a multi‐disciplinary team of health care workers and hospital administrators.

Results.  In the absence of pre‐SARS normative data for the survey, demographic and occupational variables were used to look for patterns of differences between relevant subgroups of respondents. Statistically significant differences were found for gender (73·9% women), nurses (24·7%) vs. others, doctors (20·3%) vs. others, older (40 years or older, 60·0%) vs. younger persons, emergency or intensive care unit workers (8·0%) vs. others, and those employed fewer years at the hospital (less than 5 years: 46·2%) vs. five or more years. These differences varied across the following domains: factors adversely affecting patients, communications, support, working conditions, decision‐making and, to a lesser extent, impact on life outside work. While all groups found SARS stressful, nurses reported a greater impact on morale and job satisfaction. Nurses relied more on peer support than doctors, felt less informed and less involved in decision‐making than doctors felt, and were more likely to report that infection control procedures were not strict enough.

Conclusions.  The between‐group differences and the pattern of these differences clearly illustrate the polarizing and stressful impact SARS had at a hospital with only a small number of probable or suspect cases. The clear differences between groups defined by demographics, professions and clinical roles suggest a subtle and pervasive secondary impact of the SARS outbreak, with repercussions health care facilities must contend with while maintaining increased levels of vigilance in the wake of SARS.
Advancing the clinical perspective: a practice development project to develop the nurse practitioner role in an acute hospital trust
Authors: Walsgrove Hilary , Fulbrook Paul
Published: March 2005

Aims.  The aims of this project were to investigate awareness and foster understanding of the concept of the nurse practitioner and to facilitate and support the development of nurse practitioner roles within an acute hospital trust.

Background.  A limited understanding of and minimal support for the development of the Nurse Practitioner (NP) role were identified within an acute hospital trust in the south of England. This was the impetus for pursuing the project outlined in this paper.

Theoretical perspective.  The project used practice development theory synonymously with action research methodology comprising of four action research cycles.

Method.  Data were collected in a variety of ways within the four overlapping cycles using formal and informal methods, which were analysed concurrently during the project. Techniques included questionnaires, semi‐structured interviews, meetings, discussions and the project leader's field notes’ diary.

Outcomes.  A better understanding of the concept and support for NP posts were enhanced across the trust. A Nurse Practitioner Development Group (NPDG) was established, which helped to facilitate the development of NP posts. An example of such a post was established within a NP‐led gynaecology pre‐operative assessment clinic, which was a pilot project and constituted Action Research cycle 3.

Conclusion.  It is concluded that the development of NP roles, with the support of a NPDG, within an agreed strategy offers a robust process for NP development within an acute hospital setting.

Relevance to clinical practice.  This project demonstrated how practice development and action research might be used together as a systematic process for developing and supporting professional roles that aim to improve the quality of patient care and the effectiveness of health care services.
Beyond tokenistic involvement of older people in research – a framework for future development and understanding
Authors: Dewar Belinda Jane
Published: March 2005

Research and development work in health and social care are increasingly required to involve users at all stages of the research process yet there is scant empirical evidence to support the justification of this laudable aim. Evidence does suggest that at present efforts to achieve this are primarily tokenistic and that more work is needed, both to examine what user involvement in research activity actually means, and how this can best be supported. This paper sets out to describe developments to support involvement of older people through work at the Royal Bank of Scotland Centre for the Older Person's Agenda and to identify a number of challenges that this has raised for researchers. These challenges have arisen out of a number of assumptions that underpin the process of user involvement. The paper discusses some of the benefits of working in partnership with older people and identifies strategic issues for consideration in order to promote future partnership working.
Why Has the UK Corporation Tax Raised So Much Revenue?
Authors: DEVEREUX MICHAEL P. , GRIFFITH RACHEL , KLEMM ALEXANDER
Published: March 2005

We analyse a puzzle in the UK corporation tax: by both historic and international standards, corporation tax revenues have been high while the statutory rate has been reduced. We consider explanations based on changes in the tax law and in economic factors. Changes in the tax law, such as base‐broadening measures through reductions in capital allowances, can explain only part of the puzzle. Among the economic explanations, an increase in the size of the corporate sector, mainly caused by expansion of the service sector and improvements in profitability of the financial sector, seems the most likely. To the extent that higher profits, particularly financial sector profits, may have led to high revenues, there are doubts as to whether revenues will continue to be so strong.
Distribution of human chemokine (C‐X3‐C) receptor 1 (CX3CR1) gene polymorphisms and haplotypes of the CC chemokine receptor 5 (CCR5) promoter in Chinese people, and the effects of CCR5 haplotypes on CCR5 expression
Authors: Li C. , Lu S. C. , Hsieh P. S. , Huang Y. H. , Huang H. I. , Ying T. H. , Shieh B.
Published: March 2005

Two chemokine (C‐X3‐C) receptor 1 (CX3CR1) gene polymorphisms, V249I and T280M, and 10 CC chemokine receptor 5 (CCR5) promoter haplotypes, P1–P10, have recently been reported to influence the progression of acquired immune‐deficiency syndrome (AIDS). As these studies were performed mainly with Caucasian and African‐American subjects, we determined the distribution of these alleles in Chinese people for the purpose of predicting possible clinical responses to the human immunodeficiency virus type 1 (HIV) epidemics in countries with significant Chinese populations, as well as to establish their effects on the expression of surface CCR5. Ninety‐six HIV‐negative Chinese individuals in Taiwan were subjected to genotyping, and we thus determined that the allelic frequencies of CX3CR1V249I and T280M changes were 2.6% and 2.1%, respectively, which were lower than found in Caucasians (25.5% and 14.0%, respectively). Unlike the previous reports, we only detected CCR5P1 and P4 haplotypes in Taiwanese people, and the P1/P1, P1/P4 and P4/P4 genotype frequencies were 21.0%, 41.1% and 37.9%, respectively. The sequencing data confirmed the results of previous studies, showing that CCR5P1 exhibited a complete linkage disequilibrium with a polymorphic allele 59029A present in the CCR5 promoter. Furthermore, fluorescence‐activated cell sorter analysis revealed that, in the absence of the CCR2–64I mutation, individuals carrying CCR5P1 tended to express more surface CCR5 on monocytes and CD4+ cells. Therefore, this study not only reports the frequencies for the CX3CR1 and CCR5 promoter haplotypes in a Chinese population living in Taiwan, but also identifies a statistical link between the P1/P1 haplotype and the elevated CCR5 expression levels in the study group.
Novel variations in the signal peptide region of transforming growth factor β1 gene in patients with hepatitis: a brief report from India
Authors: Gupta V. , Arora R. , Saha A. , Dhir A. , Kar P. , Bamezai R.
Published: March 2005

Genotypic status of the signal peptide region of transforming growth factor β1 (TGF‐β1) showed a significant difference in C/C‐genotype frequency at +29 position (codon 10) between a range of viral hepatitis patients and controls (P = 0.009, OR = 3.15, CI = 1.29–7.678), contributed by those who were infected with hepatitis B virus (HBV) alone or HBV + hepatitis delta virus (HDV) (P = 0.003, OR = 5.0, CI = 1.78–13.97).
The simple pendulum in a rotating frame
Authors: Abdel-Rahman A-M. M.
Published: March 2005

The classical, semiclassical, and quantum aspects of the motion of a simple pendulum rotating in the direction perpendicular to its plane of oscillations and having negative total energy in its rotating frame are considered. The system is studied for angular velocities that barely exceed the value at which spontaneous symmetry breaking sets in, as well as for angular velocities away from this value. In the former case the semiclassical methods give the energy levels and in the latter they indicate that the quantum effects manifest themselves when the velocity of rotation is very high. The solutions of the Schrödinger equation in this limit are discussed and it is noted, in contrast to the plane pendulum system, that both odd- and even-order periodic Mathieu functions are admissible eigenfunctions.
Energy eigenvalues of a quantum anharmonic oscillator
Authors: Fanelli Robert , Struzynski R. E.
Published: March 2005

An adjustable parameter is introduced into the formalism of the Rayleigh–Schrödinger perturbation theory to construct a controllable asymptotic series for the energy eigenvalues of a quantum anharmonic oscillator. Numerical results are presented, to second order in the perturbation expansion, for the ground state and the first eight excited states of the oscillator.
Report on using TIPS (Teaching Information Processing System) in teaching physics and astronomy
Authors: Folland Nathan O. , Marchini Robert R. , Rhyner Charles R. , Zeilik Michael
Published: March 2005

A computer-managed instruction system, TIPS, has been used for over a decade in the teaching of diverse disciplines. This paper describes the recent use of TIPS in physics and astronomy courses at Kansas State University, Memphis State University, University of New Mexico, and University of Wisconsin–Green Bay. Student reactions to TIPS were largely positive, but the degree of success in improving student performance reported in many articles has not been observed.
Quantum logic
Authors: Adler Carl G. , Wirth James F.
Published: March 2005

A discussion of quantum logic is presented. An example, drawn from elementary quantum mechanics, is used to illustrate the failure of the classical distributive law which is quantum logic’s most singular feature. Furthermore, an elaboration and explanation of an existing analog suitable for classroom demonstration is also presented. Finally, some remarks are made on the possible impact of quantum logic.
F-centers: advanced laboratory experiments as a ‘‘research project’’
Authors: Reichert Jonathan F.
Published: March 2005

A sophomore physics laboratory project is described which experimentally and theoretically studies by optical absorption bands of F-centers in alkali halide crystals using a variety of instrumental techniques. The student is challenged to develop a theoretical model to describe the optical absorption data.
Instrumenting an e/m experiment for use in large enrollment courses
Authors: Peterson F. C.
Published: March 2005

In order to better meet the needs of a large enrollment introductory physics laboratory various accessories for a commercially available e/m apparatus have been designed and constructed. The purpose, details, and use of these accessories are described.
Transient electric and magnetic fields associated with establishing a finite electrostatic dipole
Authors: Master M. J. , Uman M. A.
Published: March 2005

We obtain analytical solutions in the time domain for the electric and magnetic fields associated with establishing a finite electrostatic dipole. We assume that a simple source current distribution, a square pulse of current, produces the dipole, and solve for the fields produced by that source current distribution using Maxwell’s equations. Salient features of the fields are discussed from a physical point of view. We outline a technique to determine in the time domain the electric and magnetic fields produced by any arbitrary time-varying current propagating along a straight antenna, given the calculated fields due to a short square pulse of current.
Optical correlations and spectra
Authors: Brown Judith C.
Published: March 2005

The well-known techniques for determining the spectrum and correlation function of a light signal as well as the more recently developed techniques for determining the corresponding functions for the photocurrent produced by the signal are discussed. The fundamental relationships between the four kinds of measurements are emphasized and some of the more specialized differences and interrelations are discussed.
A final-exam comparison involving computer-based instruction
Authors: Jones L. M. , Kane Dennis , Sherwood Bruce Arne , Avner R. A.
Published: March 2005

In an introductory classical mechanics course, the same final exams were given to 540 students taught in the usual way and to 486 students who received computer-based instruction. All students scored better on problems which had been made up by their own lecturer. Students in the computer-based course scored better overall. These statistically significant results are of interest not only for comparing the two forms of instruction but also for their implications on the use of exam scores for such comparisons.
Time-dependent theory of alpha decay
Authors: Fuda Michael G.
Published: March 2005

Using Green’s function techniques a time-dependent theory of α decay in the standard one-body model is developed. Formulas are obtained for the decay rate and α energy. These formulas are combined with experimental information to show that to a good approximation the initial α-particle wave function vanishes on or near the nuclear surface.
Where is the Poynting vector in an ideal transformer?
Authors: Newcomb William A.
Published: March 2005

A simple calculation is presented verifying consistency of the Poynting theorem with the result of elementary circuit theory, in regard to the power flow across an ideal transformer. It is found that a nonzero Poynting vector is inevitably accompanied by certain departures from ideal behavior. Nonetheless, the use of ideal-transformer circuit relations is found to be justified as an asymptotic approximation in the low-frequency limit.
Polarizability of the one-dimensional hydrogen atom with a δ-function interaction
Authors: Postma B. J.
Published: March 2005

A one-dimensional hydrogen atom with a δ-function interaction between proton and electron is considered in an oscillating external electric field. In first-order perturbation theory the frequency-dependent complex polarizability α(ω) is calculated. It is a two-valued function of ω. The domain of values of α(ω) over the chosen Riemann sheet is determined.
The Fermi atomic pseudopotential
Authors: Cohen Marvin L.
Published: March 2005

A discussion of Fermi’s calculation using the pseudopotential approach is given. This is followed by a brief review of some of the principal extensions and applications of atomic pseudopotentials to condensed matter physics in the following 50 years.
What is a state vector?
Authors: Peres Asher
Published: March 2005

A state vector is not a property of a physical system (nor of an ensemble of systems). It does not evolve continuously between measurements, nor suddenly ‘‘collapse’’ into a new state vector whenever a measurement is performed. Rather, a state vector represents a procedure for preparing or testing one or more physical systems. No ‘‘quantum paradoxes’’ ever appear in this interpretation. The formulation of dynamical laws may involve path integrals and/or S-matrix theory.
Conversion of electromagnetic quantities from mksa to Gaussian units (and vice versa) using dimensional analysis
Authors: Leroy Bernard
Published: March 2005

It is shown how matrix methods in dimensional analysis can be used to convert the numerical values and units of electromagnetic quantities from the mksa system to the Gaussian system and vice versa. Examples are given which should convince the reader that the mentioned conversions can be performed with very little tedium.
A fundamental determination of the planetary day and year
Authors: Lightman Alan P.
Published: March 2005

General theoretical considerations and assumptions determine in order of magnitude the length of the day and year on habitable planets. These time scales are expressible in terms of fundamental constants, and their universality may have implications for extraterrestrial life.
The method of characteristics applied to the massive spring problem
Authors: Cushing James T.
Published: March 2005

The method of characteristic curves applied to the wave equation is employed to obtain explicit solutions to the problem of a spring of mass m oscillating with a mass M attached to one end. For the case of the free spring (M=0), the method produces simple solutions expressible in terms of functions which are linear in the displacement and in the time.
Was Thomas Young a wave theorist?
Authors: Cantor G. N.
Published: March 2005

Thomas Young is frequently portrayed as the reviver and main proponent of the wave theory of light in the early nineteenth century. This article shows that Young’s attitude towards the wave theory vascillated considerably owing to the changing fortunes of his ether hypothesis and his law of interference.
Computer-generated problem assignments
Authors: Miner George K. , Lang Joseph E.
Published: March 2005

A system of BASIC and word processor computer programs has been developed to produce physics problem assignments having a different set of individualized numerical data for each student. It enables the giving of credit for homework in large class sections by reducing copying and by minimizing the effort required to grade assignments. The BASIC programs generate data and answers for each student. The word processor is used to produce the raw text of the problems, merge the text with the data, and print the resulting assignments. The system prints the student assignment sheets, instructor data and answer lists, and an instrument for rapid grading. A test of this system in two different components of a general physics course is described.
The wobbling Christmas tree toy
Authors: Prigo R. B.
Published: March 2005

A common but fascinating little toy is analyzed for its unusual oscillatory behavior. A simplified model of the toy lends itself nicely to a Lagrangian-effective potential solution. Some results are obtained. Others are left to the interested classical mechanics student at the intermediate level.
Thermal fluctuations: A generalization of the Langevin equation
Authors: Sobel Michael I.
Published: March 2005

The Langevin equation is a device for showing how thermal fluctuations arise in the trajectory of a classical particle which moves in a medium at nonzero temperature. One assumes a randomly fluctuating force, and a frictional force equal to a constant times the velocity. Here we generalize this approach to allow for a position-dependent friction force, and a smooth conservative force. Instead of explicit values for the widths of the coordinate and velocity distributions (as functions of time), we find first-order time differential equations for these widths. These equations are the same as those derivable from the Fokker-Planck equation, in the case of narrow distributions.
Numerical methods in mechanics
Authors: Stanley Robert W.
Published: March 2005

Elementary numerical methods of integrating an equation of motion are systematically compared, both theoretically and experimentally. It is shown that the half-step approximation and the closely related second-order Taylor approximation are far superior to the other elementary methods, in particular, the various Euler approximations. The idea of a variable stepping interval is discussed and is shown to be highly advantageous when used with the second Taylor approximation.
Resource letter CPE-1: Computers in physics education
Authors: Fuller Robert G.
Published: March 2005

This resource letter provides a source of information for physics teachers who wish to use computers in physics education. The letter ‘‘E’’ after a reference indicates a relatively elementary item useful for people just beginning to develop an interest in using computers; the letter ‘‘I’’ denotes intermediate level references for people who have already mastered the specialized vocabulary of computer uses; and the letter ‘‘A’’ denotes advanced material for people who have experience using computers in physics teaching. This letter code does not refer to the level of the physics concepts discussed in any of the articles. An asterisk (*) indicates those articles to be included in an accompanying Reprint Book.
Generalization of Coulomb’s law to Maxwell’s equations using special relativity
Authors: Kobe Donald H.
Published: March 2005

Maxwell’s equations are obtained by generalizing the laws of electrostatics, which follow from Coulomb’s law and the principle of superposition, so that they are consistent with special relativity. In addition, it is necessary to assume that electric charge is a conserved scalar. The Lorentz force on a charged particle and its energy conservation condition are obtained by making Newton’s second law for the particle in an electrostatic field consistent with special relativity. Magnetic monopoles can be introduced into Maxwell’s theory in a way consistent with special relativity.
The Poynting vector field and the energy flow within a transformer
Authors: Herrmann F. , Schmid G. Bruno
Published: March 2005

The Poynting vector field of a transformer with two separated coils and long, parallel arms has the same distribution as that of a pair of parallel electric conductors. The magnetic field between the arms of a transformer plays the same important role for the energy transport in a transformer as does the electric field for the transport of energy between the conductors of a conductor pair. In the latter case, the energy current (=power) P is given by the familiar expression P=UI, where U  is the electric tension between the conductors and I the electric charge current through them. In the former case, we find an analogous expression P=UmIm for the energy current in a transformer. Here Um is the magnetic tension Um=∫ dr H between the arms of the transformer (H=magnetic field vector) and Im=−∫ dA Ḃ is the Hertz magnetic current (Ḃ=the time derivative of the magnetic induction B) through them. An experiment will be described which shows that the energy loss in a transformer is related to a magnetic potential drop within each of the two arms of the transformer.
A simple formula for combining rotations and Lorentz boosts
Authors: Hirshfeld A. C. , Metzger F.
Published: March 2005

We present a simple formula which is helpful in understanding the result of combining two Lorentz transformations, in particular two rotations or two Lorentz boosts. In the latter case the Wigner little group rotation occurs naturally. The formulas for the resultant angle of rotation and rapidity are generalizations of trigonometric addition theorems and of the relativistic law for adding collinear velocities.
Using perturbed resonant frequencies to study eigenmodes of an acoustic resonator
Authors: Curzon F. L. , Plant D.
Published: March 2005

A simple experiment is described which is based on the notion that the resonant frequency of an eigenmode is shifted if an obstacle is introduced into an acoustic resonator. The shift depends on the shape and volume of the obstacle and on the nature of the acoustic field which previously existed in the space occupied by the obstacle. It is shown that a spherical obstacle made from a set of parallel disks can be used to evaluate both the intensity and direction of motion of the vibrations in the resonator. The relevance of the method to other fields of physics is also indicated.
On the distribution of the nearest neighbor
Authors: Santos M. Berberan
Published: March 2005

The classical derivation of the distance distribution function of the nearest neighbor is discussed, and its limitations outlined. A new derivation, more general, is presented and applied to a random distribution of particles in a sphere.
Effect of sidespin and wind on projectile trajectory, with particular application to golf
Authors: McPhee John J. , Andrews Gordon C.
Published: March 2005

This article describes the computer simulation of the three-dimensional projectile motion of a spinning golf ball subjected to aerodynamic effects. Linear lift and drag forces are employed in the mathematical model and shown to be physically valid for launch conditions typical of a drive with a 1-wood. The effects of sidespin and wind are also included in the model, and an analytical solution of the dynamic equations of motion is obtained. This solution has been encoded in a fortran-77 program to provide rapid computation of trajectories, and graphical plots are presented that clearly illustrate the resulting ‘‘slicing’’ or ‘‘hooking’’ motion. Finally, the effects of various combinations of sidespin and crosswind on the final ball position are presented. Specifically, it is shown that a ball hit with sidespin into a crosswind can fly farther than it could in conditions of no wind.
Transmission of microwaves through layered dielectrics—Theory, experiment, and application
Authors: Rulf Benjamin
Published: March 2005

A simple transmission line analysis is presented for interaction of plane electromagnetic waves with multilayer planar structures of general physical properties. An experimental setup is described that can be used to measure the same effects. The design of radomes (transparent antenna covers) is shown to depend on knowledge gained from such theoretical empirical studies.
Resource Letter RMSL-1: Recent measurements of the speed of light and the redefinition of the meter
Authors: Bates Harry E.
Published: March 2005

This Resource Letter provides a guide to the literature on recent measurements of the speed of light and the redefinition of the meter. The letter E after an item indicates elementary level or material of general interest to persons becoming informed in the field. The letter I, for intermediate level, indicates material of somewhat more specialized nature; and the letter A indicates rather specialized or advanced material. An asterisk (*) indicates those articles to be included in an accompanying Reprint Book.
Inverse sprinklers: Two simple experiments and the resolution of the Feynman–Forrester conflict
Authors: Hsu Leonardo
Published: March 2005

The phenomenon of the inverse sprinkler can be demonstrated simply by using two or three flexible straws. This experiment throws some doubt on Feynman’s observation of a twisting hose in a carboy by confirming Forrester’s conclusion that an inverse sprinkler will exhibit no motion. The Feynman–Forrester conflict of whether or not forcing water into a sprinkler is the same as if the sprinkler were sucking in water is resolved experimentally in Feynman’s favor.
The impossibility of a simple derivation of the Schwarzschild metric
Authors: Gruber Ronald P. , Price Richard H. , Matthews Stephen M. , Cordwell William R. , Wagner Lawrence F.
Published: March 2005

The Schwarzschild metric, the general relativistic description of the space-time outside a spherical mass, has an extremely simple appearance. Because of this many attempts have been made to derive it by combining special relativity with concepts of Newtonian gravitation. It is shown here that such a derivation is impossible. A general discussion is given of the relationship of relativistic gravitation and its Newtonian limit with special emphasis on a particular non-Newtonian effect: spatial curvature.
An easy method for converting equations between SI and Gaussian units
Authors: Lau Yun-tung
Published: March 2005

An easy method for converting equations between SI and Gaussian units is presented. Only a few simple rules need to be remembered in this one-step conversion method. It is shown that each of these rules corresponds to one defining equation in the new unit system.
On the sign of the static susceptibility
Authors: Sanders T. M.
Published: March 2005

The static electric susceptibility of a normal material is positive, and the dc dielectric constant is, correspondingly, greater than unity. The fact is noted without discussion in most books on electricity and magnetism, without remarking explicitly on causes underlying the asymmetry between the electric and magnetic properties of matter. The reason for the absence of the electric analog of diamagnetism is discussed, as well as methods for producing materials with negative static electric susceptibilities. Also demonstrated is the possibility of reversing the sign of the susceptibility of a normally paramagnetic material. Possible applications of such exotic (‘‘inverted’’) materials are considered.
Validating spreadsheet solutions to Laplace’s equation
Authors: Hart Francis X.
Published: March 2005

Finite-difference solutions to Laplace’s equation are obtained on a spreadsheet for a variety of problems. The results are compared to the corresponding analytical solutions. Agreement depends on the ratio of the spreadsheet array size to the characteristic dimensions of the system being studied and on the number of iterations. An interplay between these factors is observed. Detailed applications are made to a rectangular region, a transmission line above a grounded plane, and a conducting cylinder placed in a uniform, low-frequency electric field. The use of overrelaxation and the extension of the method to a conducting sphere in a uniform field are also considered.
A formula for energy displacements for the confined hydrogen atom
Authors: Wilcox Walter
Published: March 2005

A simple approximate formula giving the first deviation from an arbitrary Coulomb energy level due to the presence of a spherical confining boundary is derived. It is shown that the Coulomb degeneracy is broken so that the state of lowest angular momentum is raised the highest in energy.
The elementary plane-wave model for hologram ray tracing
Authors: Olson D. W.
Published: March 2005

A simple ray-tracing method for thin-transmission holograms is introduced. Paraxial image location equations are derived. The thin-grating equation plays a central role analogous to the refraction equation (Snell’s law) for lenses. Advantages include: (1) The working equations can be easily related to elementary wave interference principles; (2) only algebra and trigonometry (and no calculus or complex numbers) are used; (3) the model is relatively concrete, not depending directly on the concept of wave phase; and (4) holography is incorporated into standard optics.
Canonical transformations with time as a coordinate
Authors: Johns Oliver Davis
Published: March 2005

The traditional definition of canonical transformation in classical analytic mechanics does not allow time to transform, and so excludes the Lorentz transformation. To remedy this anachronism, the well-known set of symmetric Lagrangian equations is used, which treat time as just another generalized coordinate and the negative of the traditional Hamiltonian function as just another generalized momentum. Based on this augmented phase space, time-symmetric canonical transformations are defined, which include time as a transformable coordinate. A complete theory is then presented of the invariance of Hamiltonian equations under these time-symmetric canonical transformations. This theory is based on a central fact: the nonexistence of symmetric Hamiltonian equations that would treat all coordinates and momenta equally in the same way that the symmetric Lagrangian theory does. The only available equations of Hamiltonian form are the nonsymmetric Hamiltonian equations, each set of which singles out one particular coordinate and its conjugate momentum for special treatment. It is these nonsymmetric Hamiltonian equations which are form invariant under time-symmetric canonical transformations. Also presented is a new variational principle that varies generalized coordinates and generalized velocities independently and unifies Lagrangian and Hamiltonian mechanics in one principle.
Linear regression analysis in a first physics lab
Authors: Hmurcik Lawrence , Slacik Amy , Miller Hilda , Samoncik Sandy
Published: March 2005

Linear regression analysis (least squares) is used in the first physics lab in order to introduce students to computer-aided analysis and to teach data fitting techniques. Application is made to two experiments: Fletcher’s trolley and Hooke’s law. Least squares will extract information from raw data in a very precise way, and it opens the way for the study of more complicated phenomena than a first lab usually covers. Students who learn least squares in the first semester do much better in future labs, including nonphysics labs.
Interference birefringent filters fabricated with low cost commercial polymers
Authors: Velasquez Pablo , del Mar Sánchez-López Marı́a , Moreno Ignacio , Puerto Daniel , Mateos Felipe
Published: March 2005

We discuss a simple method for fabricating interference birefringent filters using common cellophane tape layers. Cellophane tape layers can be superimposed with different orientations to generate different spectral responses. We demonstrate this behavior with a portable spectrophotometer. This technique is a simple and inexpensive way of investigating the optical properties of birefringent filters.
The mechanical equivalent of heat and the first law
Authors: Canagaratna Sebastian G.
Published: March 2005

It is shown that the determination of the mechanical equivalent of heat and the establishment of the first law are not independent of each other, and equations for the heat absorbed in a general quasi-static process which are developed without the use of the first law allow us to infer the existence of an internal energy function.
Simulation of slow light with electronic circuits
Authors: Nakanishi T. , Sugiyama K. , Kitano M.
Published: March 2005

We discuss an electronic circuit that simulates wave propagation in dispersive media. The circuit is an array of phase shifters composed of operational amplifiers. The envelope of the simulated light pulse can be described by a discretized version of the one-dimensional wave equation. The circuit can be used to change the group velocity both spatially and temporally and emulate slow light or stopped light. The control of the group velocity of optical pulses is expected to be a useful tool for quantum information and communication.
The Protein Encoded by the U
S
3 Orthologue of Marek's Disease Virus Is Required for Efficient De-Envelopment of Perinuclear Virions and Involved in Actin Stress Fiber Breakdown
Authors: Schumacher Daniel , Tischer B. Karsten , Trapp Sascha , Osterrieder Nikolaus
Published: March 2005

Marek's disease virus (MDV) encodes a protein exhibiting high amino acid similarity to the U
S
3 protein of herpes simplex virus type 1 and the gene 66 product of varicella-zoster virus. The MDV U
S
3 orthologue was replaced with a kanamycin resistance gene in the infectious bacterial artificial chromosome clone BAC20. After transfection of U
S
3-negative BAC20 DNA (20ΔU
S
3), the resulting recombinant 20ΔU
S
3 virus exhibited markedly reduced growth kinetics. Virus titers on chicken embryo cells were reduced by approximately 10-fold, and plaque sizes were significantly smaller (65% reduction) compared to parental BAC20 virus. The defect of the U
S
3-negative MDV was completely restored in a revertant virus (20U
S
3*) expressing a U
S
3 protein with a carboxy-terminal FLAG tag. Electron microscopical studies revealed that the defect of the 20ΔU
S
3 mutant to efficiently spread from cell to cell was concomitant with an accumulation in the perinuclear space of primarily enveloped virions in characteristic vesicles containing several virus particles, which resulted in reduced numbers of particles in the cytoplasm. The formation of these vesicles was not observed in cells infected with either parental BAC20 virus or the 20U
S
3* revertant virus. The role of the MDV U
S
3 protein in actin stress fiber breakdown was investigated by visualizing actin with phalloidin-Alexa 488 after infection or transfection of a U
S
3 expression plasmid. Addition of the actin-depolymerizing drug cytochalasin D to cells transfected or infected with BAC20 resulted in complete inhibition of plaque formation with as little as 50 nM of the drug, while concentrations of nocodazole as high as 50 μM only had a relatively minor effect on MDV plaque formation. The results indicated that the MDV U
S
3 serine-threonine protein kinase is transiently involved in MDV-mediated stress fiber breakdown and that polymerization of actin, but not microtubules, plays an important role in MDV cell-to-cell spread.
Tetraspanin CD81 Provides a Costimulatory Signal Resulting in Increased Human Immunodeficiency Virus Type 1 Gene Expression in Primary CD4+T Lymphocytes through NF-κB, NFAT, and AP-1 Transduction Pathways
Authors: Tardif Mélanie R. , Tremblay Michel J.
Published: March 2005

The tetraspanin superfamily member CD81 has been shown to form microdomains in the plasma membrane and to participate in the recruitment of numerous adhesion molecules, receptors, and signaling proteins in the central zone of the immune synapse. Beside its structural role, CD81 also delivers a cosignal for T cells to trigger cytokine production and cellular proliferation, thus suggesting a key role in some fundamental biological functions. It has been shown that signaling events initiated through the T-cell receptor (TCR)/CD3 complex and the coactivator CD28 positively affect human immunodeficiency virus type 1 (HIV-1) gene expression, but no study had investigated the putative costimulatory activity of CD81 on HIV-1 transcriptional activity. We observed that CD81 engagement potentiates TCR/CD3-mediated signaling, resulting in an enhancement of HIV-1 transcription and de novo virus production in both established Jurkat cells and primary CD4+T lymphocytes at a magnitude that approximates that with CD28. These observations were made by using transiently transfected plasmids (i.e., nonintegrated viral DNA) and fully competent viruses (i.e., stably integrated provirus). Moreover, the CD81-mediated enhancement of HIV-1 gene expression is linked with increased nuclear translocation of transcription factors known to positively regulate virus transcription, i.e., NF-κB, NFAT, and AP-1. These findings suggest that engagement of CD81 decreases the signaling threshold required to initiate TCR/CD3-mediated induction of integrated HIV-1 proviral DNA in primary CD4+T cells.
The Conserved Glycine-Rich Segment Linking the N-Terminal Fusion Peptide to the Coiled Coil of Human T-Cell Leukemia Virus Type 1 Transmembrane Glycoprotein gp21 Is a Determinant of Membrane Fusion Function
Authors: Wilson Kirilee A. , Bär Séverine , Maerz Anne L. , Alizon Marc , Poumbourios Pantelis
Published: March 2005

Retroviral transmembrane proteins (TMs) contain an N-terminal fusion peptide that initiates virus-cell membrane fusion. The fusion peptide is linked to the coiled-coil core through a conserved sequence that is often rich in glycines. We investigated the functional role of the glycine-rich segment, Met-326 to Ser-337, of the human T-cell leukemia virus type 1 (HTLV-1) TM, gp21, by alanine and proline scanning mutagenesis. Alanine substitution for the hydrophobic residue Ile-334 caused an ∼90% reduction in cell-cell fusion activity without detectable effects on the lipid-mixing and pore formation phases of fusion. Alanine substitutions at other positions had smaller effects (Gly-329, Val-330, and Gly-332) or no effect on fusion function. Proline substitution for glycine residues inhibited cell-cell fusion function with position-dependent effects on the three phases of fusion. Retroviral glycoprotein fusion function thus appears to require flexibility within the glycine-rich segment and hydrophobic contacts mediated by this segment.
HADRONIC DECAYS OF η AND η′
Authors: BORASOY B. , BEISERT N.
Published: March 2005

The hadronic decays η→πππ, η′→πππ and η′→ηππ are investigated within a U(3) chiral unitary approach. Final state interactions are included by deriving the effective s wave potentials for meson meson scattering from the chiral effective Lagrangian and iterating them in a Bethe-Salpeter equation. With only a small set of parameters we are able to explain both rates and spectral shapes of these decays.
SEARCH FOR BREMSSTRAHLUNG RADIATION IN QUASI-FREE np→npγ REACTIONS
Authors: PRZERWA J. , ADAM H.-H. , BUDZANOWSKI A. , CZYŻYKIEWICZ R. , GRZONKA D. , JANUSZ M. , JARCZYK L. , KAMYS B. , KHOUKAZ A. , KILIAN K. , KLAJA P. , LANG N. , MOSKAL P. , OELERT W. , PISKOR-IGNATOWICZ C. , ROŻEK T. , SANTO R. , SEFZICK T. , SIEMASZKO M. , SMYRSKI J. , TÄSCHNER A. , WINTER P. , WOLKE M. , WÜSTNER P. , ZIPPER W.
Published: March 2005

Due to the high sensitivity of the NN→NNγ reaction to the nucleon–nucleon potential, Bremsstrahlung radiation is used as a tool to investigate details of the nucleon–nucleon interaction. Such investigations can be performed at the cooler synchrotron COSY in the Research Centre Jülich, by dint of the COSY–11 detection system. The results of the identification of Bremsstrahlung radiation emitted via the dp→dpγ reaction in data taken with a proton target and a deuteron beam are presented and discussed.
ANGULAR DISTRIBUTIONS OF η MESON PRODUCTION IN pp REACTIONS
Authors: FRÖHLICH I. , BALESTRA F. , BEDFER Y. , BERTINI R. , BLAND L. C. , BRENSCHEDE A. , BROCHARD F. , BUSSA M. P. , CHOI SEONHO , COLANTONI M. L. , DRESSLER R. , DZEMIDZIC M. , FAIVRE J.-CL. , FERRERO A. , FERRERO L. , FORYCIARZ J. , FROLOV V. , GARFAGNINI R. , GRASSO A. , HEINZ S. , JACOBS W. W. , KÜHN W. , MAGGIORA A. , MAGGIORA M. , MANARA A. , PANZIERI D. , PFAFF H.-W. , PIRAGINO G. , POPOV A. , RITMAN J. , SALABURA P. , TCHALYSHEV V. , TOSELLO F. , VIGDOR S. E. , ZOSI G.
Published: March 2005

With the DISTO spectrometer, exclusive η production in pp collisions have been measured at kinetic energies of T beam =2.15, 2.50 and 2.85 GeV, respectively, via the π+π-π0 decay channel. The resulting angular distributions of the η are important for the interpretation of dilepton spectra obtained in elementary as well as heavy ion reactions.
Powder diffraction data for the three-layer Aurivillius ceramics Bi2Sr2−xAxNb2TiO12(A=Ca,Ba,x=0,0.5,1)
Authors: Haluska M. S. , Speakman S. A. , Misture S. T.
Published: March 2005

Powder diffraction data for five three-layer Aurivillius ceramics of the form Bi2Sr2−xAxNb2TiO12 (A=Ca,Ba,x=0,0.5,1) have been determined from specimens that were characterized using both X-ray and neutron diffraction. Full Rietveld analysis demonstrated that the crystals were all tetragonal (space group I4∕mmm, #139), with highly aniostropic layered structures with lattice parameters on the order of a=3.9 Å and c=33 Å, and densities on the order of 7 g∕cm3
Gender-Selective Interaction Between Aging, Blood Pressure, and Sympathetic Nerve Activity
Authors: Narkiewicz Krzysztof , Phillips Bradley G. , Kato Masahiko , Hering Dagmara , Bieniaszewski Leszek , Somers Virend K.
Published: March 2005

The mechanisms mediating the more striking age related increase in cardiovascular disease in women than in men are poorly understood. We tested the hypothesis that aging has a greater impact on sympathetic traffic in women than in men. Muscle sympathetic nerve activity (MSNA), blood pressure, and heart rate were measured in 120 healthy males and 96 healthy females aged 20 to 72 years. MSNA increased with age in both sexes, but age explained 53% of MSNA variance in female subjects and only 8% of MSNA variance in male subjects. Both the slope and intercept of the regression lines were significantly different between male and female groups (
P
<0.01 and
P
<0.001, respectively). For each decade of life, women showed an increase of 6.5 bursts/min in comparison to an increase of 2.6 bursts/min in males. Menopause did not explain the age-related increase in sympathetic traffic. For every 10-burst/min increment in MSNA in subjects older than 40, mean blood pressure increased by 2.7 mm Hg in men and by 6.1 mm Hg in women. Aging is accompanied by a greater increase in sympathetic traffic in women than in men, independent of menopausal status. Sympathetic neural mechanisms may contribute importantly to the more marked influence of age on blood pressure and cardiovascular disease in women.