bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlation of changes in laser tube temperature, cavity length, and beam polarization for an internal-mirror helium–neon laser
Authors: Woolsey G. A. , Sulaiman M. Yusof , Mokhsin Maarof
Published: March 2005

This experiment involves a study of those changes which occur in an internal-mirror helium–neon laser, during the warm-up period after switch-on. Increase in the tube temperature is measured using an array of thermocouples. Longitudinal expansion of the laser cavity is measured using one or two Michelson interferometers. Switching between axial modes is analyzed by measuring the laser output after transmission through a polarizer. The data from the three sets of measurements are compared by using them to calculate changes in tube length, and good correlation results.
Microcomputers in the laboratory
Authors: Rafert Bruce , Nicklin R. C.
Published: March 2005

A one-semester hour laboratory course introduced junior and senior physics majors to assembly language programming and to interfacing the KIM-1 microcomputer to experiments. A general purpose interface to a standard breadboard was developed. Details of the course, apparatus, and some interfacing projects are given. The simplified approach used produced gratifying results.
Experimental investigation of the transverse vibrational frequency ratio for identical loaded and unloaded rubber strings
Authors: Beatty M. F. , Lienhard J. H.
Published: March 2005

The elementary problems of small transverse vibrations of loaded and unloaded strings are briefly reviewed, and an example that shows the effect on the vibrational frequency of the amount of stretch of different kinds of materials is presented. A detailed review of the problem of the transverse vibration of a loaded string when the inertia of string is not neglected is presented, and certain exact and approximate results are examined graphically. A universal formula for the ratio of the fundamental transverse vibrational frequencies of identical loaded and unloaded strings is derived; and new experimental results describing the response of loaded rubber cords for a wide range of attached loads are compared with the universal formula.
Simulation of the Boltzmann process:  An energy space model
Authors: Eger Martin , Kress Michael
Published: March 2005

A model is introduced for the simulation of Boltzmann-like binary interactions. Because the model refers explicitly to energy states only, it is possible to follow on the computer a gas of the order of 104 molecules over 100 interactions/molecule, observing the evolution of Boltzmann’s H, the energy distribution, and other functions. Several assumptions characteristic of the Boltzmann process are imposed one by one, and their effect observed—including momentum conservation and molecular chaos. The model may be extended to exhibit also the effect of angular dependence in the scattering cross section and other dynamical aspects of two-body interactions.
Simple model of the arms race
Authors: Zane L. I.
Published: March 2005

A simple model of a two-party arms race is developed based on the principle that the race will continue so long as either side can unleash an effective first strike against the other side. The model is used to examine how secrecy, the ABM, MIRV-ing, and an MX system affect the arms race.
Determination of kinetic and thermodynamic parameters that describe isothermal seed germination: A student research project
Authors: Hageseth Gaylord T.
Published: March 2005

Students under the supervision of a faculty member can collect data and fit the data to the theoretical mathematical model that describes the rate of isothermal seed germination. The best-fit parameters are interpreted as an initial substrate concentration, product concentration, and the autocatalytic reaction rate. The thermodynamic model enables one to calculate the activation energy for the substrate and product, the activation energy for the autocatalytic reaction, and changes in enthalpy, entropy, and the Gibb’s free energy. Turnip, lettuce, soybean, and radish seeds have been investigated. All data fit the proposed model.
Graveyard shift, Hanford, 28 September 1944—Henry W. Newson
Authors: Snell Arthur H.
Published: March 2005

An account is given of the surprise effects of 135Xe fission product poisoning in the initial operation of the first Hanford plutonium production reactor.
Fundamental resonant frequency of a loudspeaker
Authors: Tan B. T. G.
Published: March 2005

The fundamental resonant frequency of a loudspeaker marks its useful low-frequency limit. Its values may be determined by plotting the electrical impedance of the loudspeaker against frequency. This was done for a loudspeaker under various loading conditons. The graphs obtained yield useful information about the loudspeaker’s mass, compliance, and other parameters.
Simple universal logic state checker
Authors: Rudmin J. W.
Published: March 2005

Effects of digital logic probes on circuits being tested are discussed. An extremely simple digital logic state checker is described, which is a significant improvement over those previously published, and which functions properly on nearly all logic families.
Quantum solutions for a symmetric double square well
Authors: Johnson Edward A. , Williams H. Thomas
Published: March 2005

The quantum behavior of a wave packet in a one-dimensional infinite square well with a finite barrier in the center is considered. Computer generated plots are presented that lead to useful analytic approximations for finding eigenvalues of the Schrödinger equation and for explaining the time dependence of wave packets.
Didactic remarks on the Sears–Kestin statement of the second law of thermodynamics
Authors: Lu Pau-Chang
Published: March 2005

Examples, counterexamples, clarifying remarks, and developmental background are presented in relation to the following new statement of the second law: As a result of an irreversible (or reversible) process, a system will always have a larger (or same) final internal energy than (or as) the initial if (i) the system is adiabatic, (ii) the process returns all the generalized displacements to their initial values, (iii) the system exhibits one temperature whenever in equilibrium, and (iv) the process connects equilibrium end states.
Relativistic time dilatation of bound muons and the Lorentz invariance of charge
Authors: Silverman Mark P.
Published: March 2005

The relativistic lengthening of the lifetime of a decaying elementary particle bound in a stationary state of an exotic atom provides evidence that the particle is actually in motion even though such motion cannot be visualized classically. This application of special relativity to the particles within an atom helps illuminate an argument frequently used for the Lorentz invariance of electric charge.
Gyrotron or electron cyclotron resonance maser: An introduction
Authors: Brand G. F.
Published: March 2005

The gyrotron or electron cyclotron resonance maser is a high-power microwave source in which the microwave fields gain energy from a beam of relativistic electrons. In this article, an elementary account of the gain mechanism based on a linear, small-signal analysis is presented.
Observable perihelion precession in central field simulators
Authors: Snider Arthur D.
Published: March 2005

The equations of motion are derived for a ball rolling without slipping on a surface designed to simulate Keplerian orbits. Perturbation analysis shows that the trajectories are conic sections that precess slowly but noticeably, in agreement with observation.
Caution: Approximation of the nonrelativistic but high-energy continuum state of a photoelectron by a plane wave can be dangerous in the evaluation of the matrix element
Authors: Au C. K.
Published: March 2005

Most quantum mechanics textbooks approximate the nonrelativistic but high-energy continuum-state wave function by a plane wave in the evaluation of photoelectric effect matrix element. This approximation leads to very wrong results if the gauge is chosen so that the EM interaction Hamiltonian is −(e/m)A⋅p and the matrix element is evaluated directly for the momentum operator. On the other hand, the same approximation is a fair one if the interaction Hamiltonian is written in the −eE⋅r gauge, or when p is replaced by the commutator −im[H,r], where H is the atomic Hamiltonian. This is explicitly demonstrated for the photoelectric effect for the hydrogen atom in the ground state.
Resource letter SH-1: superfluid helium
Authors: Hallock Robert B.
Published: March 2005

The resource letter covers the general subject of superfluid helium and treats 3He and 3He–4He mixtures as well as 4He. No effort has been made to include the fascinating experiments on either solid helium or the equally fascinating work on adsorbed helium where the helium coverage is below that necessary for superfluidity. An earlier resource letter by C. T. Lane [Am. J. Phys. 35, 367 (1967)] may be consulted for additional comments on some of the cited earlier manuscripts, but the present work is self-contained and may be used independently. Many high-quality research reports have not been cited here. Rather, the author has tried in most cases to include works particularly readable or relevant. There is a relatively heavy emphasis on experimental references. The primary reason is that these works tend to be more generally readable. No doubt some works that might have been included, have not, and for this the author takes responsibility with apology. Articles selected for incorporation in a reprint volume (to be published separately by the American Association of Physics Teachers) are marked with an asterisk(*). Following each referenced work the general level of difficulty is indicated by E, I, or A for elementary, intermediate, or advanced.
Ionization energies and electron affinities of atoms up to neon
Authors: Kregar Mitja , Weisskopf Victor F.
Published: March 2005

An elementary method is presented for the determination of the binding energies of electrons in the L shell.
Kepler’s laws and universal gravitation in Newton’s P
r
i
n
c
i
p
i
a
Authors: Cushing James T.
Published: March 2005

An outline is presented of the line of reasoning which Newton used in his Principia to obtain Kepler’s three laws of planetary motion from his own laws of motion and of universal gravitation. His combination of deductive and retroductive reasoning is related to his general philosophical outlook on the nature of science. The actual structure of the argument differs significantly from that often found in physics texts. A straightforward presentation is developed which allows the modern reader to see the type of derivation Newton employed to deduce Kepler’s three laws. The discussion preserves the essentially geometric character of Newton’s constructions in the Principia. It can even be presented to students in a noncalculus-based introductory physics course as a case study showing how one of the great achievements of modern science was produced.
Electrodynamics for undergraduates
Authors: Jappa Yu. A. , Novozhilov Yu. V.
Published: March 2005

We describe a lecture course in electrodynamics as part of a theoretical physics cycle for undergraduates. Our aim is, firstly, to present the subject briefly in a unified manner and, secondly, to examine those applications that could be useful as an introduction to optional specialized courses in modern physics.
Use of interactive exhibits in college physics teaching
Authors: Semper Rob , Diamond Judy , St. John Mark
Published: March 2005

One of the main joys in learning physics comes from an enhanced ability to understand and explain natural phenomena in the everyday world. Yet, in formal physics instruction, students encounter natural phenomena only in the laboratory and through lecture demonstrations. In this paper we examine the use of interactive exhibits as another pedagogical means for presenting phenomena and relating these phenomena to everyday experience. Along with the discussion of the nature of such exhibits, we describe an internship program that was designed to train academic faculty in the construction and use of interactive exhibits, and we illustrate some of the ways these faculty use exhibits in their teaching. Finally, we point out some of the constraints and issues that arise when the notion of exhibit-based learning is introduced into the university setting.
Dynamical stability and potential energy
Authors: Blitzer Leon
Published: March 2005

The relationship between stability and potential energy of stable mechanical systems is examined by means of specific diverse examples. In the case of statically stable systems the equilibrium configurations are always associated with potential minima. On the other hand, dynamic stability may occur at potential minima, at potential maxima, at fixed potentials other than extrema, with continuously varying potential, or even without any potential dependence.
Transformation of directions between laboratory and center-of-mass reference frames
Authors: Margulies S.
Published: March 2005

The need to relate the direction of motion of a particle in the center-of-mass frame to its direction in the laboratory frame occurs frequently in high-energy physics. As a result, a standard procedure, involving the Lorentz transformation of momentum, was developed in 1950 to answer this question. A form of the question arose recently in connection with a research program. Specifically, the problem involved finding the angular aperture of a detector in the center-of-mass frame when the aperture in the lab frame was known. In solving this problem, a particularly simple and physical way of viewing the situation was encountered. This viewpoint, presented in this paper, requires only high school mathematics and the Lorentz–Fitzgerald contraction, and is suitable for an elementary course in special relativity. For convenience, a brief review of the standard approach to the general question is also included.
Spreading of a free wave packet
Authors: Lee Hai-Woong
Published: March 2005

The spreading of a free wave packet and its relation to classical and quantum dynamics are examined. The phase-space formulation using the Wigner distribution function provides a convenient representation in which each phase point of the distribution follows a classical trajectory and the spreading occurs as a result of classical dynamics. A different formulation using a different phase-space distribution function, however, does not allow this simple interpretation of the spreading.
Study of eddy currents in a cylindrical wire: an undergraduate laboratory experiment
Authors: Gosselin J. R. , Rochon P. , Gauthier N.
Published: March 2005

The availability of lock-in amplifiers makes an experimental study of the skin effect in a metal interesting. The present note discusses the skin effect in a round wire. In particular, it shows how the voltage drop across the wire is to be calculated in a situation where the electric field inside the wire is not homogenous. An experimental setup is described that permits us to measure separately the voltage components that are in-phase and out-of-phase with the current. Results are presented and compared to theory; the agreement is excellent.
Did Millikan observe fractional charges on oil drops?
Authors: Fairbank William M. , Franklin Allan
Published: March 2005

We have reanalyzed Millikan’s 1913 data on oil drops to examine the evidence for charge quantization and for fractional residual charge. We find strong evidence in favor of charge quantization and no convincing evidence for fractional residual charges on the oil drops.
The hot chocolate effect
Authors: Crawford Frank S.
Published: March 2005

The ’’hot chocolate effect’’ was investigated quantitatively, using water. If a tall glass cylinder is filled nearly completely with water and tapped on the bottom with a softened mallet one can detect the lowest longitudinal mode of the water column, for which the height of the water column is one-quarter wavelength. If the cylinder is rapidly filled with hot tap water containing dissolved air the pitch of that mode may descend by nearly three octaves during the first few seconds as the air comes out of solution and forms bubbles. Then the pitch gradually rises as the bubbles float to the top. A simple theoretical expression for the pitch ratio is derived and compared with experiment. The agreement is good to within the 10% accuracy of the experiments.
The population structure of an ideal boson gas
Authors: Hynne F.
Published: March 2005

We derive simple expressions for the average value and fluctuation of the total number of particles in oribitals of given occupancy.
Is quantum theory universally valid?
Authors: Peres A. , Zurek W. H.
Published: March 2005

Quantum theory has been criticized for not being deterministic and therefore not universal: it cannot completely describe a measurement aimed at verifying its predictions (although any given apparatus can be considered as a quantum system). We investigate the possible alternatives. Theories where the observed world is deterministic but the observer is not (whatever the reason for that) lead to Bell’s nonseparability theorem. If, on the other hand, the observer too is deterministic, the theory is not verifiable. It follows that quantum theory must be the logically preferred option. Its inability to completely describe the measurement process appears to be not a flaw of the theory but a logical necessity which is analogous to Gödel’s undecidability theorem.
Bell’s inequality and quantum correlations
Authors: Harrison David
Published: March 2005

The conflict between quantum predictions and some ’’common sense’’ assumptions is explored at a level suitable for undergraduates with an elementary knowledge of quantum mechanics. The current status of experimental tests of the conflict is reviewed, and the implications are briefly discussed.
How far away is the horizon?
Authors: French A. P.
Published: March 2005

An analysis is presented for calculating the distance of the visible horizon as a function of the altitude of the observer, taking account of the variation of atmospheric refractive index with height. The results are applied to the specific case (valid up to about 10 km in the Earth’s atmosphere) in which the atmospheric density falls off exponentially with altitude.
Absolute synchronization by light beacons: A paradox
Authors: Martins Roberto de A.
Published: March 2005

The light pencil emitted by a rotating beacon may produce at great distances a spot of light moving with superluminal speed. This light spot may be used for synchronization of distant clocks, and this method would seem to provide an absolute criterion for simultaneity due to an invariant feature of rotation. This conjecture is explored and then contrasted with another argument that denies that such synchronization is absolute. The shortcomings of the first argument are discussed, and it is shown that this process is equivalent to the usual synchronization by light signals.
The ideal gas and the second law of thermodynamics
Authors: Fox Ronald F.
Published: March 2005

Explicit solutions are used to show that the second law of thermodynamics is not in conflict with the time-reversal invariance of Liouville’s equation. The solutions are generated for a contracted, exact description of an ideal gas.
Placental Malaria Diminishes Development of Antibody Responses toPlasmodium falciparumEpitopes in Infants Residing in an Area of Western Kenya WhereP. falciparumIs Endemic
Authors: Bonner Phillip Cullison , Zhou Zhiyong , Mirel Lisa B. , Ayisi John G. , Shi Ya Ping , van Eijk Anna M. , Otieno Juliana A. , Nahlen Bernard L. , Steketee Richard W. , Udhayakumar Venkatachalam
Published: March 2005

To determine the effect of placental malaria (PM) infection on the development of antibody responses to malaria in infants, we measured immunoglobulin G levels to seven differentPlasmodium falciparumepitopes by using plasma samples collected at monthly intervals from infants born to mothers with and without PM. Overall, PM was associated with diminished antibody levels to all of the epitopes tested, especially with infants aged ≥4 to 12 months, and the difference was statistically significant for four of the seven epitopes (P< 0.0035). These findings suggest that PM can negatively influence the development of immune responses to malaria in infants.
Characterization of Virus-Responsive Plasmacytoid Dendritic Cells in the Rhesus Macaque
Authors: Chung Eugene , Amrute Sheela B. , Abel Kristina , Gupta Gunjan , Wang Yichuan , Miller Christopher J. , Fitzgerald-Bocarsly Patricia
Published: March 2005

Plasmacytoid dendritic cells (PDC) are potent producers of alpha interferon (IFN-α) in response to enveloped viruses and provide a critical link between the innate and adaptive immune responses. Although the loss of peripheral blood PDC function and numbers has been linked to human immunodeficiency virus (HIV) progression in humans, a suitable animal model is needed to study the effects of immunodeficiency virus infection on PDC function. The rhesus macaque SIV model closely mimics human HIV infection, and recent studies have identified macaque PDC, potentially making the macaque a good model to study PDC regulation. In this study, we demonstrate that peripheral blood PDC from healthy macaques are both phenotypically and functionally similar to human PDC and that reagents used for human studies can be used to study macaque PDC. Both human and macaque PBMC expressed IFN-α in response to herpes simplex virus (HSV), the prototypical activator of PDC, as measured by using an IFN bioassay and IFN-α-specific enzyme-linked immunospot assays. Similar to human PDC, macaque PDC were identified by using flow cytometry as CD123+HLA-DR+lineage−cells. In addition, like human PDC, macaque PDC expressed intracellular IFN-α, tumor necrosis factor alpha, macrophage inflammatory protein 1β/CCL4, and IFN-inducible protein 10/CXCL10 upon stimulation with HSV, all as determined by intracellular flow cytometry. We found that IFN regulatory factor 7, which is required for the expression of IFN-α genes, was, similar to human PDC, expressed at high levels in macaque PDC compared to monocytes and CD8+T cells. These findings establish the phenotypic and functional similarity of human and macaque PDC and confirm the utility of tools developed for studying human PDC in this animal model.
Glycolipids of
Mycobacterium tuberculosis
Strain H37Rv Are Potential Serological Markers for Diagnosis of Active Tuberculosis
Authors: Tiwari R. P. , Tiwari Dileep , Garg Sanjay K. , Chandra Ramesh , Bisen Prakash S.
Published: March 2005

A simple and cost-effective diagnostic tool (TB Screen Test) for the screening of patients with pulmonary and extrapulmonary tuberculosis and for differentiation of those individuals from individuals without tuberculosis, other common infections, and healthy controls has been developed. The serological responses of purified mycobacterial glycolipid antigens were examined by a liposome agglutination assay. The assay was able to detect very low antiglycolipid antibody concentrations in the infected individuals. The sera from the tuberculosis patient group had significantly higher concentrations of antiglycolipid antibody than the sera from uninfected control subjects, with 94% sensitivity and 98.3% specificity. Glycolipids of
Mycobacterium tuberculosis
H37Rv antigens were isolated, purified, and characterized. After interchelation with liposome particles, these purified antigens specifically bound to the antiglycolipid antibodies present in the sera of patients with tuberculosis, resulting in the formation of a blue agglutination. This protocol clearly differentiates healthy controls and
M. bovis
BCG-vaccinated subjects from those with active tuberculosis. The resultant diagnostic tool, the TB Screen Test, is more economical and rapid (4 min) than other currently available products and can be used for the mass screening of a heavily afflicted population.
The influence of wing morphology and echolocation on the gleaning ability of the insectivorous bat Myotis tricolor
Authors: Stoffberg Samantha , Jacobs David S
Published: March 2005

On the basis of its external morphology, Myotis tricolor (Temminck, 1832) should be able to both aerial-feed and glean. Furthermore, this bat is known to use broadband calls of short duration, reinforcing the prediction that it gleans. However, results from this study indicate that M. tricolor does not commonly glean. This conclusion was reached after studying the foraging behaviour of M. tricolor in a flight room. We presented M. tricolor with mealworms, moths, mole crickets, beetles, and cicadas in a variety of ways that required either gleaning and (or) aerial feeding. Although M. tricolor readily took tethered prey, it did not take any of the variety of insects presented to it in a manner that required gleaning. We therefore compared its wing morphology and echolocation calls with those of several known gleaners, Nycteris thebaica E. Geoffroy, 1818, Myotis lucifugus (Le Conte, 1831), and Myotis septentrionalis (Trouessart, 1897), and an aerial forager, Neoromicia capensis (A. Smith, 1829). In a discriminant analysis wing-tip shape was the only variable to provide some degree of discrimination between species, with M. tricolor having more pointed wing tips than the known gleaners. Discriminant analysis of echolocation-call parameters grouped M. tricolor with the other Myotis species and separated it from N. capensis and N. thebaica. However, M. tricolor did not use harmonics as did the other Myotis species. The apparent failure of M. tricolor to glean might therefore be due to its relatively pointed wings and narrow-bandwidth echolocation calls, owing to the absence of harmonics in its calls.
Maternal aggression in lactating female Japanese macaques: time course and interindividual variation
Authors: Schino Gabriele , D'Amato Francesca R , Troisi Alfonso
Published: March 2005

This study investigated the aggressive behavior of female Japanese macaques (Macaca fuscata (Blyth, 1875)) during lactation. Following parturition, the frequency of aggression showed an initial decline during weeks 1–2 of infant life, then increased to peak during weeks 7–8 post partum, and finally declined again to prepartum levels. Neither the initial decline nor the subsequent increase in aggression rate post partum was related to sociodemographic characteristics of the mother–infant dyad or to measures of maternal style. These results suggest that variation in postpartum aggression may be influenced less by the quality of the mother–infant relationship than by the mother's relationships the mother has with group mates.
Agonism and shelter competition between invasive and indigenous crayfish species
Authors: Gherardi Francesca , Daniels William H
Published: March 2005

Several crayfish species behave as biological invaders. Their establishment in an area has frequently been accompanied by the reduction or elimination of indigenous species. A laboratory study was designed to investigate whether the invasive crayfish Procambarus clarkii (Girard, 1852) is dominant over the indigenous (to Delaware) crayfish Procambarus acutus acutus (Girard, 1852) in either the absence or the presence of a shelter as a limited resource. As expected, we found that P. clarkii is more aggressive than the similarly sized P. a. acutus, thus confirming previous studies that demonstrated an inherent dominance of the invasive over the indigenous crayfish. We then hypothesized that species showing a lower preference for an offered shelter (P. clarkii) should be less motivated to defend it. To the contrary, in a competitive context P. clarkii excluded P. a. acutus from the shelter but did not use the resource. Caution must be used in extrapolating these laboratory studies to the field, and future studies should analyze multiple factors, including the autoecology of the two species and their reproductive potential and recruitment patterns. However, our results might help in highlighting the risks for freshwater biodiversity created by the uncontrolled translocations of P. clarkii and other similar invasive species.
DNA content and genome composition of diploid and triploid water frogs belonging to the Rana esculenta complex (Amphibia, Anura)
Authors: Ogielska Maria , Kierzkowski Piotr , Rybacki Mariusz
Published: March 2005

The Central European water frog Rana esculenta L., 1758 is a natural hybrid between Rana lessonae Camerano, 1882 (LL) and Rana ridibunda Pallas, 1771 (RR). Hybrids are usually diploid (RL) or triploid (LLR or RRL). Distinguishing LL from RL, RR from RL, and LLR from RRL according to external morphology is ambiguous. In this study we checked whether the DNA content in erythrocyte nuclei measured by image cytometry is useful in determination of the taxonomic status of diploids (LL, RR, and RL) and the genome composition of triploids (LLR and RRL). For exact and direct identification of parental species, as well as for determination of genome composition in hybrids, we applied actinomycin D – 4',6-diamidino-2-phenylindole chromosome staining to metaphase plates. We analyzed 43 LL, 12 RR, and 32 RL diploids, and 37 LLR and 19 RRL triploids. All diploid hybrids had 2n = 26 chromosomes, and all triploid hybrids had 3n = 39 chromosomes. Neither aneuploid nor mosaic hybrids were detected. The expected numbers of 13 R. lessonae (L) and 13 R. ridibunda (R) chromosomes in RL hybrids were recorded in about 31% of individuals. In the rest of the sample the composition was variable, ranging from 9 to 14 R chromosomes and the corresponding number of L chromosomes. The expected composition of 26 L and 13 R chromosomes was detected in about 32% of LLR triploids, whereas in the rest of the sample the composition of chromosomes ranged from 8 to 15 R chromosomes and the corresponding number of L chromosomes. The expected numbers of 26 R and 13 L chromosomes were detected in about 26% of RRL triploids, whereas in the rest of the sample the composition of chromosomes ranged from 19 to 28 R chromosomes and the corresponding number of L chromosomes. The DNA content densitometry showed that RR and RL diploids had 9.5% and 3.8% more DNA, respectively, than LL diploids. These differences, although statistically significant, were not sufficient to unequivocally discriminate LL from RL and RR from RL. Triploids had about 50% more DNA than LL diploids (49% in LLR and 51% in RRL), but these differences were too small for unequivocal determination of their genome composition.
Developmental mode in benthic opisthobranch molluscs from the northeast Pacific Ocean: feeding in a sea of plenty
Authors: Goddard Jeffrey H.R
Published: March 2005

Mode of development was determined for 130 of the nearly 250 species of shallow-water, benthic opisthobranchs known from the northeast Pacific Ocean. Excluding four introduced or cryptogenic species, 91% of the species have planktotrophic development, 5% have lecithotrophic development, and 5% have direct development. Of the 12 native species with non-feeding (i.e., lecithotrophic or direct) modes of development, 5 occur largely or entirely south of Point Conception, California, where surface waters are warmer, lower in nutrients, and less productive than those to the north; 4 are known from habitats, mainly estuaries, that are small and sparsely distributed along the Pacific coast of North America; and 1 is Arctic and circumboreal in distribution. The nudibranchs Doto amyra Marcus, 1961 and Phidiana hiltoni (O'Donoghue, 1927) were the only species with non-feeding development that were widespread along the outer coast. This pattern of distribution of developmental mode is consistent with the prediction that planktotrophy should be maintained at high prevalence in regions safe for larval feeding and growth and should tend to be selected against where the risks of larval mortality (from low- or poor-quality food, predation, and transport away from favorable adult habitat) are higher. However, direct development, which includes the most derived mode of non-feeding development, was also correlated with small adult size, reflecting an association common in marine invertebrates. Planktotrophic development also predominates in decapod Crustacea from the northeast Pacific, but is less common in echinoderms and prosobranch gastropods from this region owing to the presence of lineages constrained by phylogeny to non-feeding modes of development.
Contrasting Mechanisms of Defense Against Biotrophic and Necrotrophic Pathogens
Authors: Glazebrook Jane
Published: March 2005

It has been suggested that effective defense against biotrophic pathogens is largely due to programmed cell death in the host, and to associated activation of defense responses regulated by the salicylic acid–dependent pathway. In contrast, necrotrophic pathogens benefit from host cell death, so they are not limited by cell death and salicylic acid–dependent defenses, but rather by a different set of defense responses activated by jasmonic acid and ethylene signaling. This review summarizes results from Arabidopsis-pathogen systems regarding the contributions of various defense responses to resistance to several biotrophic and necrotrophic pathogens. While the model above seems generally correct, there are exceptions and additional complexities.
THE POLITICAL EVOLUTION OF PRINCIPAL-AGENT MODELS
Authors: Miller Gary J.
Published: March 2005

▪ Abstract  With tools borrowed from the economic analysis of insurance, principal-agency theory has allowed political scientists new insights into the role of information asymmetry and incentives in political relationships. It has given us a way to think formally about power as the modification of incentives to induce actions in the interests of the principal. Principal-agency theory has evolved significantly as political scientists have sought to make it more applicable to peculiarly political institutions. In congressional oversight of the bureaucracy, increasing emphasis has been placed on negotiation of administrative procedures, rather than the imposition of outcome-based incentives, as originally conceived. Awareness of the problem of credible commitment has impelled more dramatic reformulations, in which agents perform their function only when their interests conflict with those of the principal, and they are guaranteed some degree of autonomy.

The ‘political master’ finds himself in the position of the ‘dilettante’ who stands opposite the ‘expert,’ facing the trained official who stands within the management of administration.

( Weber 1958 )
THEORIZING THE EUROPEAN UNION: International Organization, Domestic Polity, or Experiment in New Governance?
Authors: Pollack Mark A.
Published: March 2005

▪ Abstract  The study of the European Union (EU) has been transformed during the past decade, and three distinct theoretical approaches have emerged. The first approach, which seeks to explain the process of European integration, has largely abandoned the long-standing neofunctionalist-intergovernmentalist debate in favor of a rationalist-constructivist debate reflecting broader developments in international relations theory. A second approach, however, has rejected the application of international relations theory in favor of comparative politics approaches which analyze the EU using off-the-shelf models of legislative, executive, and judicial politics in domestic politics. A third and final approach sees the EU as an emerging system of multi-level governance in which national governments are losing influence in favor of supranational and subnational actors, raising important normative questions about the future of democracy within the EU.
CONSTITUTIONAL REFORM IN BRITAIN: The Quiet Revolution
Authors: Bogdanor Vernon
Published: March 2005

▪ Abstract  Since 1997, Britain has been undergoing a period of constitutional reform. This reform has been radical and yet piecemeal. The process has been unique in the democratic world, in that it has been converting an uncodified constitution into a codified one, but by stages, there being neither the political will nor the consensus to do more. Some of the contours of the new constitution will be familiar to Americans, for Britain now enjoys a quasi-federal system of government, and, in effect, a Bill of Rights. The creation of a more representative upper house is also part of the ongoing process of reform. In consequence, Britain no longer lives under an organic “historic” constitution but is in the process of fashioning one that is being created by deliberate human agency.
Nitric oxide inhibition unmasks ischemic myocardium-derived vasoconstrictor signals activating endothelin type A receptor of coronary microvessels
Authors: Takahashi Katsuaki , Komaru Tatsuya , Takeda Satoru , Sato Kouichi , Kanatsuka Hiroshi , Shirato Kunio
Published: March 2005

NO plays an important role in the compensatory increase in coronary flow conductance against myocardial ischemia, and NO bioavailability is impaired in various diseases. We tested the hypothesis that, when NO production is inhibited, vasoconstrictor signals from the ischemic myocardium are unmasked. We investigated the involvement of endothelin type A (ETA) receptors in the transduction of the constrictor signal. To detect coronary vasoactive signals derived from ischemic myocardium, we used a bioassay system in which an isolated rabbit coronary microvessel (detector vessel, DV) was placed on beating myocardium perfused by the left anterior descending coronary artery (LAD) of an anesthetized open-chest dog ( n = 38). The DV was pressurized to 60 cmH2O throughout the experiment and observed with an intravital microscope equipped with a floating objective. After the intrinsic tone of the DV was established, vehicle ( n = 7), Nω-nitro-l-arginine (l-NNA, 100 μmol/l; n = 13), l-NNA + BQ-123 (a selective ETAreceptor blocker, 1 μmol/l; n = 7), or BQ-123 alone (1 μmol/l; n = 7) was superfused onto the DV. Thereafter, the LAD of the beating heart was occluded. Coronary occlusion produced significant dilation of the DV by 10 ± 4%. When l-NNA was applied, the DV significantly constricted by 12 ± 5% in response to LAD occlusion, and BQ-123 abolished the vasoconstriction. Pretreatment with BQ-123 alone produced an enhancement of the ischemia-induced dilation. We conclude that ischemic myocardium releases transferable vasomotor signals that produce coronary microvascular constriction during the blockade of NO production and the constrictor signal is mediated by ETAreceptors.
Leptin receptors are expressed in coronary arteries, and hyperleptinemia causes significant coronary endothelial dysfunction
Authors: Knudson Jarrod D. , Dincer Ü. Deniz , Zhang Cuihua , Swafford Albert N. , Koshida Ryoji , Picchi Andrea , Focardi Marta , Dick Gregory M. , Tune Johnathan D.
Published: March 2005

Obesity is associated with marked increases in plasma leptin concentration, and hyperleptinemia is an independent risk factor for coronary artery disease. As a result, the purpose of this investigation was to test the following hypotheses: 1) leptin receptors are expressed in coronary endothelial cells; and 2) hyperleptinemia induces coronary endothelial dysfunction. RT-PCR analysis revealed that the leptin receptor gene is expressed in canine coronary arteries and human coronary endothelium. Furthermore, immunocytochemistry demonstrated that the long-form leptin receptor protein (ObRb) is present in human coronary endothelium. The functional effects of leptin were determined using pressurized coronary arterioles (<130 μm) isolated from Wistar rats, Zucker rats, and mongrel dogs. Leptin induced pharmacological vasodilation that was abolished by denudation and the nitric oxide synthase inhibitor Nω-nitro-l-arginine methyl ester and was absent in obese Zucker rats. Intracoronary leptin dose-response experiments were conducted in anesthetized dogs. Normal and obese concentrations of leptin (0.1–3.0 μg/min ic) did not significantly change coronary blood flow or myocardial oxygen consumption; however, obese concentrations of leptin significantly attenuated the dilation to graded intracoronary doses of acetylcholine (0.3–30.0 μg/min). Additional experiments were performed in canine coronary rings, and relaxation to acetylcholine (6.25 nmol/l-6.25 μmol/l) was significantly attenuated by obese concentrations of leptin (625 pmol/l) but not by physiological concentrations of leptin (250 pmol/l). The major findings of this investigation were as follows: 1) the ObRb is present in coronary arteries and coupled to pharmacological, nitric oxide-dependent vasodilation; and 2) hyperleptinemia produces significant coronary endothelial dysfunction.
Function curve of the membranes that regulate amniotic fluid volume in sheep
Authors: Faber Job , Anderson Debra , Hohimer Roger , Yang Qin , Giraud George , Davis Lowell
Published: March 2005

Seven singleton 120-day fetal lambs were prepared with a shunt from the lung to the gastric end of the esophagus, a bladder catheter, and multiple amniotic fluid and vascular catheters. The urachus was ligated. Beginning 7 days later, amniotic fluid volumes were determined by drainage, followed by replacement with 1 liter of lactated Ringer (LR) solution. Urine flow into the amnion was measured continuously. In 14 of 27 experiments, amniotic fluid volumes were determined again 2 days after the inflow into the amnion had consisted of urine only and in 13 experiments after the inflow of urine had been supplemented by an intraamniotic infusion of LR solution. Intramembranous absorption was calculated from the inflows and the changes in volume between the beginning and end of each experiment. The relations between absorption rate and amniotic fluid volume, the “function curves,” were highly individual. Urine production during the infusion of LR solution did not decrease, fetal plasma renin activity decreased ( P < 0.001), and amniotic fluid volume increased by 140% [SE (27%), P < 0.005], but the increase in the amniochorionic absorption rate of 411% [SE (48%), P < 0.001] was greater ( P < 0.005) than the increase in volume. Each of the seven fetuses was proven capable of an average intramembranous absorption rate that exceeded 4.5 liters of amniotic fluid per day. During the infusion of LR solution, the increase in the rate of absorption matched the rate of infusion (both in ml/h), with a regression coefficient of 0.75 ( P < 0.001). Thus, even for large amniotic fluid volumes, volume is not limited by the absorptive capacity of the amniochorion, and, at least in these preparations, the position of the function curve and not the natural rate of inflow was the major determinant of resting amniotic fluid volume.
Diesel exhaust activates redox-sensitive transcription factors and kinases in human airways
Authors: Pourazar Jamshid , Mudway Ian S. , Samet James M. , Helleday Ragnberth , Blomberg Anders , Wilson Susan J. , Frew Anthony J. , Kelly Frank J. , Sandström Thomas
Published: March 2005

Diesel exhaust (DE) is a major component of airborne particulate matter. In previous studies we have described the acute inflammatory response of the human airway to inhaled DE. This was characterized by neutrophil, mast cell, and lymphocyte infiltration into the bronchial mucosa with enhanced epithelial expression of IL-8, Gro-α, and IL-13. In the present study, we investigated whether redox-sensitive transcription factors were activated as a consequence of DE exposure, consistent with oxidative stress triggering airway inflammation. In archived biopsies from 15 healthy subjects exposed to DE [particulates with a mass median diameter of <10 μm, 300 μg/m3] and air, immunohistochemical staining was used to quantify the expression of the transcription factors NF-κB (p65) and AP-1 (c-jun and c-fos), as well their upstream MAPKs, p38 and JNK, in the bronchial epithelium. In addition, phosphorylation of tyrosine residues was examined. DE induced a significant increase in the nuclear translocation of NF-κB ( P = 0.02), AP-1 ( P = 0.02), phosphorylated JNK ( P = 0.04), and phosphorylated p38 ( P = 0.01), as well as an increase in total (cytoplasmic + nuclear) immunostaining of phosphorylated p38 ( P = 0.03). A significant increase in nuclear phosphorylated tyrosine was also observed ( P <0.05). These observations demonstrate that DE activates redox-sensitive transcription factors in vivo consistent with oxidative stress triggering the increased synthesis of proinflammatory cytokines.
TNF, IFN-γ, and endotoxin increase expression of DMT1 in bronchial epithelial cells
Authors: Wang Xinchao , Garrick Michael D. , Yang Funmei , Dailey Lisa A. , Piantadosi Claude A. , Ghio Andrew J.
Published: March 2005

Regulation of the metal transport protein divalent metal transporter-1 (DMT1) may contribute to the uptake and detoxification of iron by cells resident in the respiratory tract. Inflammation has been associated with an increased availability of this metal resulting in an oxidative stress. Because proinflammatory cytokines and LPS have been demonstrated to affect an elevated expression of DMT1 in a macrophage cell line, we tested the hypothesis that tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and LPS increase DMT1 expression in airway epithelial cells. We used RT-PCR to detect mRNA for both −IRE DMT1 and +IRE DMT1 in BEAS-2B cells. Treatment with TNF-α, IFN-γ, or LPS increased both forms. Western blot analysis also demonstrated an increase in the expression of both isoforms of DMT1 after these treatments. Twenty-four hours after exposure of an animal model to TNF-α, IFN-γ, or LPS, a significant increase in pulmonary expression of −IRE DMT1 was seen by immunohistochemistry; the level of +IRE DMT1 was too low in the lung to be visualized using this methodology. Finally, iron transport into BEAS-2B cells was increased after inclusion of TNF-α, IFN-γ, or LPS in the media. We conclude that proinflammatory cytokines and LPS increase mRNA and protein expression of DMT1 in airway cells in vitro and in vivo. Furthermore, both −IRE and +IRE isoforms are elevated after exposures. Increased expression of this protein appears to be included in a coordinated response of the cell and tissue where the function might be to diminish availability of metal.
Apical location of ferroportin 1 in airway epithelia and its role in iron detoxification in the lung
Authors: Yang Funmei , Haile David J. , Wang Xinchao , Dailey Lisa A. , Stonehuerner Jacqueline G. , Ghio Andrew J.
Published: March 2005

Ferroportin 1 (FPN1; aka MTP1, IREG1, and SLC40A1), which was originally identified as a basolateral iron transporter crucial for nutritional iron absorption in the intestine, is expressed in airway epithelia and upregulated when these cells are exposed to iron. Using immunofluorescence labeling and confocal microscopic imaging techniques, we demonstrate that in human and rodent lungs, FPN1 localizes subcellularly to the apical but not basolateral membrane of the airway epithelial cells. The role of airway epithelial cells in iron mobilization in the lung was studied in an in vitro model of the polarized airway epithelium. Normal human bronchial epithelial cells, grown on membrane supports until differentiated, were exposed to iron, and the efficiency and direction of iron transportation were studied. We found that these cells can efficiently take up iron across the apical but not basolateral surface in a concentration-dependent manner. Most of the iron taken up by the cells is then released into the medium within 8 h in the form of less reactive protein-bound complexes including ferritin and transferrin. Interestingly, iron release also occurred across the apical but not basolateral membrane. Our findings indicate that FPN1, depending on its subcellular location, could have distinct functions in iron homeostasis in different cells and tissues. Although it is responsible for exporting nutrient iron from enterocytes to the circulation in the intestine, it could play a role in iron detoxification in airway epithelial cells in the lung.