bluuebunny/crossref_metadata_2025 huggingface dataset:
Goldfishing: A new solvable many-body problem
Authors: Bruschi M. , Calogero F.
Published: October 2006

A recent technique allows one to identify and investigate solvable dynamical systems naturally interpretable as classical many-body problems, being characterized by equations of motion of Newtonian type (generally in two-dimensional space). In this paper we tersely review results previously obtained in this manner and present novel findings of this kind: mainly solvable variants of the goldfish many-body model, including models that feature isochronous classes of completely periodic solutions. Different formulations of these models are presented. The behavior of one of these isochronous dynamical systems in the neighborhood of its equilibrium configuration is investigated, and in this manner some remarkable Diophantine findings are obtained.
Electronic frequency modulation for the increase of maximum measurable velocity in a heterodyne laser interferometer
Authors: Choi Hyunseung , La Jongpil , Park Kyihwan
Published: October 2006

A Zeeman-type He–Ne laser is frequently used as a heterodyne laser due to the simple construction and the small loss of a light. However, the low beat frequency of the Zeeman-type laser limits the maximum measurable velocity. In this article, an electronic frequency modulation algorithm is proposed to overcome the drawback of the low velocity measurement capability by increasing the beat frequency electronically. The brief analysis, the measurement scheme of the proposed algorithm, and the experimental results are presented. It is demonstrated that the proposed algorithm is proven to enhance the maximum measurable velocity.
Time-resolved soft x-ray imaging diagnostic for use at the NIF and OMEGA lasers
Authors: Schneider M. B. , Holder J. P. , James D. L. , Bruns H. C. , Celeste J. R. , Compton S. , Costa R. L. , Ellis A. D. , Emig J. A. , Hargrove D. , Kalantar D. H. , MacGowan B. J. , Power G. D. , Sorce C. , Rekow V. , Widmann K. , Young B. K. , Young P. E. , Garcia O. F. , McKenney J. , Haugh M. , Goldin F. , MacNeil L. P. , Cone K.
Published: October 2006

The soft x-ray imager (SXRI) built for the first experiments at the National Ignition Facility (NIF) has four soft x-ray channels and one hard x-ray channel. The SXRI is a snout that mounts to a four strip gated imager. This produces four soft x-ray images per strip, which can be separated in time by ∼60ps. Each soft x-ray channel consists of a mirror plus a filter. The diagnostic was used to study x-ray burnthrough of hot Hohlraum targets at the NIF and OMEGA lasers. The SXRI snout design and issues involved in selecting the desired soft x-ray channels are discussed.
Bernstein mode generated anomalous resistivity in a current carrying plasma focusing cell
Authors: Welch D. R. , Genoni T. C. , Rose D. V. , Oliver B. V. , Hahn K. D. , Schamiloglu E.
Published: October 2006

The influence of microinstabilities and turbulence on the resistivity of plasma filled electron beam focusing cells is presented. Using a particle-in-cell simulation code, we have observed the onset of anomalous resistivity for low plasma densities and large embedded magnetic fields. The enhanced resistivity results from wave-particle interactions due to the saturation of the ion Bernstein mode instability in the current-carrying plasma. The growth rate of the mode scales with the relative drift speed between the electrons and ions. Here the scaling of the instability derived from simulation and theory and its impact on the operation of a plasma focusing cell for electron beam driven radiography are discussed. Enhanced resistivity up to 70 times larger than the classical Spitzer value is calculated for relevant plasma parameters.
Photoelectrochemical water splitting at titanium dioxide nanotubes coated with tungsten trioxide
Authors: Park Jong Hyeok , Park O Ok , Kim Sungwook
Published: October 2006

The photocatalytic splitting of water into hydrogen and oxygen using solar light is a potentially clean and renewable source for hydrogen fuel. Titanium oxide nanotubes coated with tungsten oxide were prepared to harvest more solar light for the first time and characterized their water splitting efficiency. The tungsten trioxide coatings significantly enhanced the visible spectrum absorption of the titanium dioxide nanotube array, as well as their solar-spectrum induced photocurrents. For the sample, upon white light illumination at 150mW∕cm2, hydrogen gas generated at the overall conversion efficiency of 0.87%.
On the effect of image charges and ion-wall dispersion forces on electric double layer interactions
Authors: Wernersson Erik , Kjellander Roland
Published: October 2006

Two effects of interactions between polarizable ions and polarizable walls in electric double layers are investigated: ionic image charge forces and ion-wall dispersion forces. The first must be included for a consistent treatment of the wall-wall van der Waals (vdW) interaction, since it contains the effect of screening of the static part of the vdW interaction. The second has been suggested to give rise to ion specificity in double layer interactions. The strength of the ion-wall dispersion forces are estimated from quantum mechanical calculations of ionic polarizability and from experimental data for the dielectric functions of the media. The ion density profiles and the anisotropic ion-ion distribution functions in the double layer are calculated in the highly accurate anisotropic hypernetted chain approximation, which allows the correct treatment of the image charge forces. The double layer interactions are evaluated from these distribution functions. It is found that it is important to include both kinds of ion-wall forces. Quantitative and sometimes even qualitative differences occur in the double layer interactions depending on the ionic species of the electrolyte due to different strengths of the ion-wall dispersion interactions.
Uncertainty relation for Fisher information of D-dimensional single-particle systems with central potentials
Authors: Romera Elvira , Sánchez-Moreno P. , Dehesa J. S.
Published: October 2006

An uncertainty Fisher information relation in quantum mechanics is derived for multidimensional single-particle systems with central potentials. It is based on the concept of Fisher information in the two complementary position and momentum spaces, which is a gradient functional of the corresponding probability distributions. The lower bound of the product of position and momentum Fisher informations is shown to depend on the orbital and magnetic quantum numbers of the physical state and the space dimensionality. Applications to various elementary systems is discussed.
The emergence of collective vibrations in cluster models: Quantum chemical study of the methyl-terminated Si(111) surface
Authors: Ferguson Glen Allen , Raghavachari Krishnan
Published: October 2006

In this paper we present structures and harmonic vibrational frequencies for the methylated silicon (111) surface from quantum chemical calculations using both cluster models and periodic boundary conditions. The results from both calculations are in very good agreement with experimentally determined frequencies. We demonstrate that relatively small cluster models already show the emergence of collective vibrational modes and provide a general method for the assignment of vibrational frequencies for extended surfaces from cluster models. Finally, we discuss a vibrational mode that results from the coupling between near-surface phonons and the silicon-carbon bending modes.
Nonlinear growth of a line-tied g mode near marginal stability
Authors: Zhu P. , Hegna C. C. , Sovinec C. R.
Published: October 2006

A theoretical framework is developed for the study of the nonlinear gravitational (g) mode of a line-tied flux tube near marginal stability. The theory is based on an expansion using two small parameters, ϵ∼∣ξ∣∕Leq⪡1 and n−1∼k‖∕k⊥⪡1, with ξ denoting the plasma displacement, Leq the characteristic equilibrium length scale, and k‖ and k⊥ the dominant wavenumbers parallel and perpendicular to the equilibrium magnetic field, respectively. A particular nonlinear regime is described through the imposition of the ordering ϵ∼n−1. This regime corresponds to the nonlinear phase previously described by S. C. Cowley and M. Artun [Phys. Rep. 283, 185 (1997)], where the plasma is to lowest order incompressible and the lowest-order Lagrangian compression ∇0∙ξ is zero. In this regime, nonlinearity modifies the envelope equation of the linear global mode. The detonation regime, where the nonlinear growth of the mode dominates the linear response and becomes finite-time singular, is a narrower subset of the Cowley-Artun regime. However, at sufficient amplitude the validity of this regime breaks down and subsequently transitions to an intermediate nonlinear regime where the ordering ϵ∼n−1∕2 holds. In this regime, the lowest-order Lagrangian compression is nonzero [∇0∙ξ∼O(1)]. Direct magnetohydrodynamic simulations with both a finite difference code and NIMROD code indicate that the mode remains bounded in magnitude with a slightly reduced growth in the nonlinear phase relative to the linear growth rate. During the intermediate nonlinear phase, nonlinearity directly modifies the growth of linear local modes. The corresponding governing equations for the intermediate nonlinear phase are derived.
Remote bond breaking by interacting temporary anion states
Authors: Burrow P. D. , Gallup G. A.
Published: October 2006

The cross section for bond breaking at the site of a dissociative temporary negative ion state through the dissociative electron attachment process can be considerably enhanced by the presence of a second longer-lived temporary negative ion state elsewhere in the molecule, even one quite remote from the first. In a series of chloroalkenes possessing both C–Cl and CC bonds separated by various distances, we show that the cross sections are determined by the lifetime of the lower anion state created by the mixing of the anion states of these two moieties, with the wave function’s coefficients giving the probability that the electron is located at the dissociative site. Furthermore, the lifetime of the composite anion state can be expressed in terms of these same coefficients and the lifetimes of the unmixed resonances. We also discuss how these results may give insight into the means by which strand breaks are induced in DNA by the attachment of slow electrons.
Analytical electron microscopy study of growth mechanism for smoothing of metallic multilayer thin films
Authors: Ozatay O. , Mkhoyan K. A. , Thomas M. G. , Fuchs G. D. , Silcox J. , Buhrman R. A.
Published: October 2006

We have used scanning transmission electron microscopy and electron energy-loss spectroscopy techniques to study the nature of interfacial interactions in a Ta∕CuOx stack that give rise to a smooth surface morphology, which can be utilized for seeding thin magnetic multilayer devices. Our measurements reveal that the interfacial smoothing is mainly due to the preferential reaction of Ta with O at the Ta∕CuOx interface assisted by grain boundary diffusion of oxygen which thereby acts to smooth out the surface roughness created by the large crystalline grains of Cu.
Electromagnetic interchange-like mode and zonal flow in electron-magnetohydrodynamic plasma
Authors: Chakrabarti Nikhil , Horiuchi Ritoku
Published: October 2006

A numerical simulation of the nonlinear state of interchange instability associated with electron inertia in an unmagnetized plasma is studied. It is shown that a self-consistent sheared transverse electron current flow is generated due to nonlinear mechanisms. This zonal flow can reduce the growth rate of the magnetic interchange-like instability and reach a steady state. The zonal flow generation mechanisms are discussed by truncated Fourier mode representation. In the truncated model, three mode equations are considered that have an exact analytic solution that matches well with the numerical solution. The effect of different boundary conditions in such investigations is also discussed.
Comment on “Kinetic theory of the stability of the inhomogeneous plasmas with transverse inhomogeneous electric field” [Phys. Plasmas 13, 012108 (2006)]
Authors: Ganguli Gurudas
Published: October 2006

It is shown that the conclusion of Mikhailenko and Mikhailenko that the inhomogeneous energy density driven instability does not exist is a consequence of the local approximation that they employ. The instability is nonlocal in character and requires a nonlocal treatment as shown in our earlier works.
Monodomain dynamics for rigid rod and platelet suspensions in strongly coupled coplanar linear flow and magnetic fields. II. Kinetic theory
Authors: Forest M. Gregory , Sircar Sarthok , Wang Qi , Zhou Ruhai
Published: October 2006

We establish reciprocity relations of the Doi-Hess kinetic theory for rigid rod macromolecular suspensions governed by the strong coupling among an excluded volume potential, linear flow, and a magnetic field. The relation provides a reduction of the flow and field driven Smoluchowski equation: from five parameters for coplanar linear flows and magnetic field, to two field parameters. The reduced model distinguishes flows with a rotational component, which map to simple shear (with rate parameter) subject to a transverse magnetic field (with strength parameter), and irrotational flows, for which the reduced model consists of a triaxial extensional flow (with two extensional rate parameters). We solve the Smoluchowski equation of the reduced model to explore: (i) the effect of introducing a coplanar magnetic field on each sheared monodomain attractor of the Doi-Hess kinetic theory and (ii) the coupling of coplanar extensional flow and magnetic fields. For (i), we show each sheared attractor (steady and unsteady, with peak axis in and out of the shearing plane, periodic and chaotic orbits) undergoes its own transition sequence versus magnetic field strength. Nonetheless, robust predictions emerge: out-of-plane degrees of freedom are arrested with increasing field strength, and a unique flow-aligning or tumbling/wagging limit cycle emerges above a threshold magnetic field strength or modified geometry parameter value. For (ii), irrotational flows coupled with a coplanar magnetic field yield only steady states. We characterize all (generically biaxial) equilibria in terms of an explicit Boltzmann distribution, providing a natural generalization of analytical results on pure nematic equilibria [P. Constantin, I. Kevrekidis, and E. S. Titi, Arch. Rat. Mech. Anal. 174, 365 (2004); P. Constantin, I. Kevrekidis, and E. S. Titi, Discrete and Continuous Dynamical Systems 11, 101 (2004); P. Constantin and J. Vukadinovic, Nonlinearity 18, 441 (2005); H. Liu, H. Zhang, and P. Zhang, Comm. Math. Sci. 3, 201 (2005); C. Luo, H. Zhang, and P. Zhang, Nonlinearity 18, 379 (2005); I. Fatkullin and V. Slastikov, Nonlinearity 18, 2565 (2005); H. Zhou, H. Wang, Q. Wang, and M. G. Forest, Nonlinearity 18, 2815 (2005)] and extensional flow-induced equilibria [Q. Wang, S. Sircar, and H. Zhou, Comm. Math. Sci. 4, 605 (2005)]. We predict large parameter regions of bi-stable equilibria; the lowest energy state always has principal axis aligned in the flow plane, while another minimum energy state often exists, with primary alignment transverse to the coplanar field.
Gain curves for direct-drive fast ignition at densities around 300g∕cc
Authors: Betti R. , Solodov A. A. , Delettrez J. A. , Zhou C.
Published: October 2006

The maximum gain attainable from fast-ignited direct-drive implosions is derived based on realistic target designs and laser pulses, one-dimensional simulations of the implosion, and two-dimensional simulations of ignition by a collimated electron beam and burn propagation. Since the implosion characteristics are set by the optimized target design, the ratio of the thermonuclear energy to the compression laser energy is a unique function of the driver energy on target. It is shown that, if ignited, the fuel assembled by a 100-kJ UV laser can yield close to 6MJ of thermonuclear energy.
Convective heat transfer in unsteady laminar parallel flows
Authors: Brereton G. J. , Jiang Y.
Published: October 2006

In laminar, fully developed pipe and channel flows that undergo transients from a known initial state, exact analytical solutions for the momentary velocity field as functionals of the flow rate can be determined from the Navier-Stokes equations, for arbitrary flow unsteadiness [Phys. Fluids 12, 518 (2000)]. For laminar, fully developed duct flows with uniform wall heating that undergo large flow transients, the companion thermal energy equation can be approximated in a form that may also be solved analytically, yielding solutions for the instantaneous temperature field for arbitrary time unsteadiness in both the flow and the wall heat flux. Expressions for Nusselt numbers in convective heat transfer in duct flows with arbitrary temporal flow and heat flux unsteadiness can then be found, which illustrate how the flow and heat flux transient histories determine whether the unsteadiness enhances or reduces the overall heat-transfer effectiveness. These expressions are used to show how significant enhancements or reductions in the average Nusselt number can be achieved in duct flow by applying appropriate temporal flow control.
Fabrication of sub-50nm (La,Ba)MnO3 ferromagnetic nanochannels by atomic force microscopy lithography and their electrical properties
Authors: Hirooka Motoyuki , Yanagisawa Yoshihiko , Kanki Teruo , Tanaka Hidekazu , Kawai Tomoji
Published: October 2006

The technique of atomic force microscope nanolithography was used to construct robust nano-structures with atomically flat surface of ferromagnetic perovskite manganites down to 30nm in size over 5μm long. The resulting (La,Ba)MnO3 nanochannel possessed no lithographic damage and exhibited bulklike room temperature ferromagnetism down to 30nm beyond electrical phase separation picture. High-quality ferromagnetic oxide nanostructures allow to instigate intrinsic nanoscale electrical transport properties of these materials and to construct high-performance and novel spin electronics devices.
Modeling real dynamics in the coarse-grained representation of condensed phase systems
Authors: Izvekov Sergei , Voth Gregory A.
Published: October 2006

This work presents a systematic multiscale methodology to provide a more faithful representation of real dynamics in coarse-grained molecular simulation models. The theoretical formalism is based on the recently developed multiscale coarse-graining (MS-CG) method [S. Izvekov and G. A. Voth, J. Phys. Chem. B. 109, 2469 (2005); J. Chem. Phys. 123, 134105 (2005)] and relies on the generalized Langevin equation approach and its simpler Langevin equation limit. The friction coefficients are determined in multiscale fashion from the underlying all-atom molecular dynamics simulations using force-velocity and velocity-velocity correlation functions for the coarse-grained sites. The diffusion properties in the resulting CG Brownian dynamics simulations are shown to be quite accurate. The time dependence of the velocity autocorrelation function is also well-reproduced relative to the all-atom model if sufficient resolution of the CG sites is implemented.
Using an electroconductive carbon nanotube probe tip in scanning nonlinear dielectric microscopy
Authors: Ishikawa K. , Cho Y.
Published: October 2006

A scanning nonlinear dielectric microscope (SNDM), which can be used for detecting the surface and subsurface of ferroelectric polarization with high resolution, has been developed. Contact-mode atomic force microscopy typically uses a metal-coated conductive cantilever tip; however, SNDM imaging resolution declines upon repeated scanning because of the abrasion of the tip in the contact mode. To improve the lateral resolution of the tip, we used an electroconductive carbon nanotube (CNT) probe tip. Using the SNDM with the CNT probe, the ferroelectric domain boundary of stoichiometric lithium tantalate (LiTaO3) is observed in air at room temperature and the results compared with those obtained using a platinum-coated tip.
An experimental investigation of hydrodynamic cavitation in micro-Venturis
Authors: Mishra Chandan , Peles Yoav
Published: October 2006

The existence of hydrodynamic cavitation in the flow of de-ionized water through micro-Venturis has been witnessed in the form of traveling bubble cavitation and fully developed streamer bubble/supercavitation, and their mechanisms have been discussed. High-speed photography and flow visualization disclose inchoate cavitation bubbles emerging downstream from the micro-Venturi throat and the presence of a single streamer bubble/supercavity, which is equidistant from the micro device walls. The supercavity initiates inside the diffuser section and extends until the microchannel exit and proceeds to bifurcate the incoming flow. This article strives to provide numerical data and experimental details of hydrodynamic cavitation taking place within micro-Venturis.
Response to “Comment on ‘Variational approach to the volume viscosity of fluids’” [Phys. Fluids 18, 109101 (2006)]
Authors: Zuckerwar Allan J. , Ash Robert L.
Published: October 2006

We respond to the Comment of Markus Scholle and therewith revise our material entropy constraint to account for the production of entropy.
Antiferroelectricity in multiferroic BiCrO3 epitaxial films
Authors: Kim Dae Ho , Lee Ho Nyung , Varela Maria , Christen Hans M.
Published: October 2006

Multiferroic BiCrO3 epitaxial films were grown by pulsed laser deposition on SrTiO3 (001) substrates with SrRuO3 bottom electrodes. The authors found that the films exhibit antiferroelectricity with a characteristic electric field induced ferroelectric phase, as evidenced by double hysteretic behaviors in the electric field dependence of dielectric constants and polarization. The antiferroelectricity is consistent with theoretical predictions that the Bi lone pair induces polarization in bismuth-based perovskites, such as ferroelectric BiMnO3 and BiFeO3. Magnetic measurements revealed weak parasitic ferromagnetism resulting from antiferromagnetic ordering below 140K. This magnetic transition coincides with a local maximum in the dielectric constants’ temperature dependence.
Influence of annealing on the bias voltage dependence of tunneling magnetoresistance in MgO double-barrier magnetic tunnel junctions with CoFeB electrodes
Authors: Feng Gen , van Dijken Sebastiaan , Coey J. M. D.
Published: October 2006

Double-barrier magnetic tunnel junctions with two MgO barriers and three CoFeB layers exhibiting tunneling magnetoresistance (TMR) values of more than 100% were fabricated. The bias voltage dependence of the TMR ratio is highly asymmetric after annealing at low temperatures, indicating dissimilar CoFeB∕MgO interfaces. The TMR effect decays very slowly for positive bias and is only reduced to half of its maximum value at V1∕2=1.88V when the junctions are processed at 200°C. The largest output voltage, 0.62V, is obtained after annealing at 300°C, a temperature that combines high TMR ratios with a considerable asymmetric bias dependence.
Separate domain formation in Ge2Sb2Te5–SiOx mixed layer
Authors: Lee Tae-Yon , Yim Sung-Soo , Lee Dongbok , Lee Min-Hyun , Ahn Dong-Ho , Kim Ki-Bum
Published: October 2006

We report separate domain formation in cosputtered Ge2Sb2Te5–SiOx mixed layer, with SiOx amount less than 10mol%. As-prepared Ge2Sb2Te5–SiOx layer exhibits amorphous phase with separate domains smaller than 20nm. The separation maintains after thermal annealing, which results in crystallization into fcc phase. The crystallization activation energies of Ge2Sb2Te5–SiOx are obtained as 4.99 and 6.44eV for mixed layers containing 5.3 and 8.4mol% SiOx, respectively. Those are larger than 2.75eV of pure Ge2Sb2Te5. Furthermore, the mixed layer exhibits sublimation at increased temperature. These are interpreted as formation of Ge2Sb2Te5-rich domains separated from each other by SiOx-rich domains.
Characteristics of radio-frequency, atmospheric-pressure glow discharges with air using bare metal electrodes
Authors: Wang Hua-Bo , Sun Wen-Ting , Li He-Ping , Bao Cheng-Yu , Zhang Xiao-Zhang
Published: October 2006

In this letter, an induced gas discharge approach is proposed and described in detail for obtaining a uniform atmospheric-pressure glow discharge with air in a γ mode using water-cooled, bare metal electrodes driven by radio-frequency (13.56MHz) power supply. A preliminary study on the discharge characteristics of the air glow discharge is also presented in this study. With this induced gas discharge approach, radio-frequency, atmospheric-pressure glow discharges using bare metal electrodes with other gases which cannot be ignited directly as the plasma working gas, such as nitrogen, oxygen, etc., can also be obtained.
Second inflection point of water surface tension
Authors: Lü Y. J. , Wei B.
Published: October 2006

The classical molecular dynamics method is applied to simulate the surface tension of water over the wide temperature range from 193to398K. The results show that the temperature dependence of surface tension obviously increases in supercooled region, and there exists a second inflection point in the surface tension-temperature curve at about 303K similar to the first one at 525K, which confirms the conjecture based on the experimental measurements. When the temperature approaches 180K, the simulated surface tension displays a sharp rise like the anomalies of some bulk thermodynamic properties.
Internanotube friction
Authors: Syue Sen-Hong , Lu Sheng-Yi , Hsu Wen-Kuang , Shih Han-Chang
Published: October 2006

Field induced displacement of carbon nanotubes is detected within a bundle and intertube friction is calculated via cohesive energy and electromagnetic formula. Tube-tube friction is found to be 1.4×10−4N which is five orders of magnitude greater than value obtained between adjacent layers within a nanotube.
Magnetic field sensing scheme using CoFeB∕MgO∕CoFeB tunneling junction with superparamagnetic CoFeB layer
Authors: Jang Youngman , Nam Chunghee , Kim J. Y. , Cho B. K. , Cho Y. J. , Kim T. W.
Published: October 2006

The authors investigated the tunneling magnetoresistance (TMR) of CoFeB∕MgO∕CoFeB tunnel junctions by varying the thickness (tCoFeB) of the top CoFeB layer. Linear and hysteresis-free switching was observed in junctions with tCoFeB⩽10Å, while normal tunneling behavior occurred for tCoFeB>10Å. The field sensitivity and the sensing field range were found to be controlled by varying the thickness of the sensing layer. This finding means that the magnetic tunneling junction (MTJ) provides a scheme for magnetic field sensing, which has a simple sensor design and low power consumption. The magnetic properties of the sensing layer with tCoFeB⩽10Å were found to show the characteristics of superparamagnetism. Although the detailed mechanism of TMR in MTJs with a superparamagnetic layer is not fully understood at present, this phenomenon is observed repeatedly. Therefore, this sensing scheme would be an alternative method for overcoming the problems in magnetic sensors with a crossed magnetization pattern.
Variation within Prostanthera spinosa (Lamiaceae): evidence from morphological and molecular studies
Authors: Williams Mark L. , Drinnan Andrew N. , Walsh Neville G.
Published: October 2006

Specimens of Prostanthera spinosa F. Muell. representing the geographic range of the taxon were examined for morphological and genetic variation within the species. Patterns of morphological variation were documented and the amplified fragment length polymorphism (AFLP) DNA fingerprinting technique was used to assess the genetic relationships among plants from different populations. Morphological and molecular results were in broad agreement and supported distinct groups in both analyses. The differences detected warrant taxonomic recognition and three species are described representing geographically disjunct regions. Plants from the Grampians in Victoria, Eyre Peninsula, Flinders Ranges and Kangaroo Island in South Australia, group together and retain the name P. spinosa; plants from Mt Arapiles in Victoria are distinct and are recognised as a new species P. arapilensis; plants from the Fortis Creek National Park and adjacent areas in northern New South Wales are distinct and are identified as a new species, P. sejuncta.
Universality of color names
Authors: Lindsey Delwin T. , Brown Angela M.
Published: October 2006

We analyzed the World Color Survey (WCS) color-naming data set by using
k
-means cluster and concordance analyses. Cluster analysis relied on a similarity metric based on pairwise Pearson correlation of the complete chromatic color-naming patterns obtained from individual WCS informants. When
K
, the number of
k
-means clusters, varied from 2 to 10, we found that (
i
) the average color-naming patterns of the clusters all glossed easily to single or composite English patterns, and (
ii
) the structures of the
k
-means clusters unfolded in a hierarchical way that was reminiscent of the Berlin and Kay sequence of color category evolution. Gap statistical analysis showed that 8 was the optimal number of WCS chromatic categories: RED, GREEN, YELLOW-OR-ORANGE, BLUE, PURPLE, BROWN, PINK, and GRUE (GREEN-OR-BLUE). Analysis of concordance in color naming within WCS languages revealed small regions in color space that exhibited statistically significantly high concordance across languages. These regions agreed well with five of six primary focal colors of English. Concordance analysis also revealed boundary regions of statistically significantly low concordance. These boundary regions coincided with the boundaries associated with English WARM and COOL. Our results provide compelling evidence for similarities in the mechanisms that guide the lexical partitioning of color space among WCS languages and English.
Estimation of false discovery proportion under general dependence
Authors: Pawitan Yudi , Calza Stefano , Ploner Alexander
Published: October 2006

Motivation: Wide-scale correlations between genes are commonly observed in gene expression data, due to both biological and technical reasons. These correlations increase the variability of the standard estimate of the false discovery rate (FDR). We highlight the false discovery proportion (FDP, instead of the FDR) as the suitable quantity for assessing differential expression in microarray data, demonstrate the deleterious effects of correlation on FDP estimation and propose an improved estimation method that accounts for the correlations.

Methods: We analyse the variation pattern of the distribution of test statistics under permutation using the singular value decomposition. The results suggest a latent FDR model that accounts for the effects of correlation, and is statistically closer to the FDP. We develop a procedure for estimating the latent FDR (ELF) based on a Poisson regression model.

Results: For simulated data based on the correlation structure of real datasets, we find that ELF performs substantially better than the standard FDR approach in estimating the FDP. We illustrate the use of ELF in the analysis of breast cancer and lymphoma data.

Availability: R code to perform ELF is available in .

Contact:  yudi.pawitan@ki.se

Supplementary information: Supplementary data are available at Bioinformatics online.
Ossified soft tissue leiomyoma in a patient with sickle cell anemia
Authors: Xu Yaohui , Lacouture Mario , Petronic‐Rosic Vesna , Soltani Keyoumars , Shea Christopher R.
Published: October 2006

Abstract:  Osseous metaplasia in leiomyomas is extremely rare. Here, we report the case of an ossified subcutaneous leiomyoma in a 34‐year‐old African American man with sickle cell thalassemia who presented with a painful nodule of the scapular region, which appeared as a heavily mineralized soft tissue mass on chest radiographs. Histopathologic and immunohistochemical examination of the resected nodule revealed a benign soft tissue leiomyoma composed of intersecting fascicles of spindle cells that strongly expressed smooth muscle actin and caldesmon. Extensive intratumoral calcification and ossification were noticed. Only eight cases of ossified leiomyoma have been reported, of which two arose in the deep soft tissue. Those cases are briefly reviewed and discussed.
Potentiation of erythroid abnormalities following macrophage depletion in aged rats
Authors: Lisa Giuliani Anna , Graldi Giuseppe , Veronesi Massimo , Lorenzini Franco , Gandini Gloria , Unis Lorenza , Previato Antonio , Wiener Edith , Wickramasinghe Sunitha N. , Berti Gilberto
Published: October 2006

Objectives: The effects of prolonged macrophage depletion on haematological parameters were investigated in aged rats and compared with those in young ones. Methods: Four weekly i.v. injections of dichloromethylene diphosphonate‐containing liposomes (Cl2MDP‐CL) were employed to achieve a prolonged depletion of bone marrow (BM) and spleen macrophages. The number of BM macrophages was then assessed by flow cytometry, whereas the spleen clearance function was judged by the elimination of oxidised red blood cells (RBC). Haematological parameters and signs of RBC ageing (reduced MCV, increased density and augmented 4.1a/4.1b membrane protein ratio) were determined. Finally, the recovery from phlebotomy‐induced acute anaemia was investigated. Results: Following the Cl2MDP‐CL treatment, in comparison with young rats, the aged animals showed: (i) reduced numbers of BM macrophages; (ii) greater impairment of spleen clearance function; (iii) similar anaemic condition and signs of RBC ageing; (iv) greater increase in white blood cell (WBC) numbers (mainly neutrophils). In addition, whereas aged control rats showed a recovery from phlebotomy‐induced acute anaemia which was similar to that of the untreated young animals, in the aged‐treated rats, a significantly diminished/delayed restoration of RBC, Hb and reticulocyte to normal values was observed, accompanied by a significantly higher increase in WBC numbers than in the other groups of animals. Conclusion: Haematological abnormalities because of Cl2MDP‐CL‐induced macrophage depletion are potentiated in aged rats in which the BM regenerative potential of the erythroid lineage as well as the clearance function of the spleen appear compromised. Thus, in aged rats, macrophage dysfunction is likely to interfere with erythroid homeostasis particularly during haemopoietic stress.
Drug eruption caused by the nonionic contrast medium iohexol. “Recall‐like phenomenon” appearing on an area previously affected by herpes zoster
Authors: MATSUMURA Takumi , WATANABE Hideaki , BATCHELOR Jonathan , SUEKI Hirohiko , IIJIMA Masafumi
Published: October 2006

We report a case of “recall‐like phenomenon” caused by nonionic contrast medium. A 62‐year‐old woman suffering from postherpetic neuralgia developed erythematous plaques 12 h after an intercostal nerve block under X‐ray guidance using iohexol (Omnipaque) as contrast medium. The erythematous plaques were preferentially located in the sites where she had experienced herpes zoster 4 months previously. The lesions cleared spontaneously leaving no pigmentation. Both patch testing and intradermal testing with iohexol and ioversol were positive. We postulate that local immunological changes in the skin, such as an increased number and/or accelerated activity of Langerhans cells and mast cells in the herpes zoster lesions, were responsible for this phenomenon. This “recall‐like phenomenon”, occurring preferentially in skin previously affected by herpes zoster, could facilitate understanding of the pathology of drug eruptions.
Generalized morphea and primary biliary cirrhosis coexisting in a male patient
Authors: GONZÁLEZ‐LÓPEZ Marcos A. , DRAKE Marta , GONZÁLEZ‐VELA M. Carmen , ARMESTO Susana , LLACA Héctor F. , VAL‐BERNAL J. Fernando
Published: October 2006

We present further evidence that generalized morphea (GM) and primary biliary cirrhosis (PBC) may be associated. As far as we know, only six cases with this association have been previously reported in the published work, all of which were observed in women. We describe the case of a 62‐year‐old man diagnosed with M2‐antibody‐positive PBC who developed multiple generalized indurated plaques on the trunk and extremities 3 years later. Clinical history, laboratory data and histopathological examination were consistent with the diagnosis of GM. The coexistence in a male of these two entities that predominantly affect females reinforces the hypothesis that a pathogenic link exists between GM and PBC. Consequently, PBC should be looked for in all patients with GM.
Granuloma caused by subcutaneous injection of leuprorelin acetate product: Case report and histopathological findings
Authors: OUCHI Takeshi , KOYAMA Tetushi , MIYATA Naho , SUGIURA Makoto
Published: October 2006

Leuprorelin acetate is a luteinizing hormone‐releasing hormone (LH‐RH) analog, which is used for chemical castration. Chemical castration treatment has an especially important role for prostate cancer. To ensure ongoing chemical castration, a novel sustained‐action injection system using spherical microcapsules has been developed. We report a patient who had granuloma caused by administration of the 11.25 mg leuprorelin acetate product. Histological examination revealed many giant cells with vacuoles. On the basis of reported cases, these vacuoles are characteristic for the granuloma caused by leuprorelin acetate product. The vacuoles in the granuloma are the same size as the microcapsules, and their shape is almost spherical. We assume that the vacuoles in the granuloma are actually the microcapsules. We expect that there will be investigations regarding the procatarctic cause of granuloma formation.
Cost–utility analysis of different peg‐interferon alpha‐2b plus ribavirin treatment strategies as initial therapy for naïve Chinese patients with chronic hepatitis C
Authors: LIN W.‐A. , TARN Y.‐H. , TANG S.‐L.
Published: October 2006

Background

Different peg‐interferon alpha‐2b plus ribavirin treatment strategies are more effective in treating hepatitis C. However, no cost‐effectiveness data have been published using the clinical data from the peg‐interferon alpha‐2b and ribavirin in the treatment of patients with hepatitis C in Taiwan.

Aim

To estimate the cost‐effectiveness of different treatments with peg‐interferon alpha‐2b plus ribavirin for the initial treatment of patients with different genotype chronic hepatitis C.

Methods

Individual patient level data from a randomized clinical trial with peg‐interferon plus ribavirin were applied to a Markov model to project lifelong clinical outcomes. Economic estimates and quality of life were based on published data and Taiwan patient data. We used a societal perspective and applied a 3% annual discount rate.

Results

Compared with different combination therapy strategies, peg‐interferon alpha‐2b plus weight‐based dosing of ribavirin in all patients for 24 weeks is the most cost‐effective treatment strategy. If the sustained virological response of peg‐interferon plus ribavirin treatment for 48 weeks therapy in genotype 1 patients was higher than 67.8%, the best strategy of treating patients will be the peg‐interferon plus weight‐based dosing of ribavirin therapy for 48 weeks in genotype 1 patients and for 24 weeks in non‐genotype 1 patients.

Conclusions

Peg‐interferon alpha‐2b plus ribavirin combination for 24 weeks therapy in all genotype patients should reduce the incidence of liver complications, prolong life, improve quality of life and be cost‐effective for the initial treatment of chronic hepatitis C.
Systematic review: cyclo‐oxygenase‐2 in human oesophageal adenocarcinogenesis
Authors: MEHTA S. , BODDY A. , JOHNSON I. T. , RHODES M.
Published: October 2006

Background

Published in vitro and animal in vivo studies have demonstrated that cyclo‐oxygenase‐2 plays an important role during oesophageal adenocarcinogenesis. However, the extent to which these studies are directly relevant to events in the human lower oesophagus is questionable.

Aim

To perform a systematic review of all available human studies that have evaluated levels of cyclo‐oxygenase‐2 expression during the progression from Barrett's metaplasia to oesophageal adenocarcinoma.

Methods

A literature search was performed to identify all studies which qualitatively or quantitatively assessed cyclo‐oxygenase‐2 protein or gene expression in either Barrett's, dysplastic or adenocarcinoma tissue in humans.

Results

A total of 27 studies met the inclusion criteria. There was general agreement that cyclo‐oxygenase‐2 was either absent or very weakly expressed in normal oesophageal squamous mucosa, but considerable disagreement regarding the presence of cyclo‐oxygenase‐2 in Barrett's and low‐grade dysplasia. All studies agreed that high‐grade dysplasia and adenocarcinoma expressed cyclo‐oxygenase‐2 to some extent although levels varied considerably between tissue samples.

Conclusions

There is conflicting evidence in the literature for cyclo‐oxygenase‐2 playing an important role in early oesophageal adenocarcinogenesis. Other non‐cyclo‐oxygenase‐2 targets may account for the epidemiological data supporting the use of non‐steroidal anti‐inflammatory drugs in the chemoprevention of oesophageal adenocarcinoma.
Review article: from 1906 to 2006 – a century of major evolution of understanding of gastro‐oesophageal reflux disease
Authors: DENT J.
Published: October 2006

Background

Our understanding of gastro‐oesophageal reflux disease has undergone significant changes over the last century.

Aim

To trace the rise in understanding of gastro‐oesophageal reflux disease and highlight remaining areas of uncertainty.

Methods

Literature review.

Results

In 1906, Tileston published his observations on ‘peptic ulcer of the oesophagus’. Winkelstein, in 1934, first correlated symptoms of heartburn with acid regurgitation and reflux oesophagitis. In 1946, Allison described hiatus hernia as a causal factor in the development of gastro‐oesophageal reflux disease. In 1958, Bernstein and Baker showed a direct relationship between oesophageal acidification and heartburn in patients with gastro‐oesophageal reflux disease, irrespective of endoscopic findings, leading to the recognition of non‐erosive gastro‐oesophageal reflux disease. In the 1980s, continuous recordings of the lower oesophageal sphincter showed that episodes of reflux were related to transient relaxations of lower oesophageal sphincter tone. There is now increasing recognition that gastro‐oesophageal reflux disease arises from the interaction of several anatomical and physiological factors. A turning point in the medical treatment of gastro‐oesophageal reflux disease came with the introduction of the first proton pump inhibitor, omeprazole, in 1989.

Conclusions

Future efforts need to identify the multifactorial interactions of gastro‐oesophageal junction anatomy and physiology in patients with gastro‐oesophageal reflux disease. Increased understanding of the disease will guide development of new therapies.
Review article: pathogenesis and management of gastric carcinoid tumours
Authors: BURKITT M. D. , PRITCHARD D. M.
Published: October 2006

Background

Gastric carcinoid tumours are rare, but are increasing in incidence.

Aim

To discuss tumour pathogenesis and outline current approaches to patient management.

Methods

Review of published articles following a Pubmed search.

Results

Although interest in gastric carcinoids has increased since it was recognized that they are associated with achlorhydria, to date there is no definite evidence that humans taking long‐term acid suppressing medication are at increased risk. Type I tumours are associated with autoimmune atrophic gastritis and hypergastrinaemia, type II are associated with Zollinger–Ellison syndrome, multiple endocrine neoplasia‐1 and hypergastrinaemia and sporadic type III carcinoids are gastrin‐independent and carry the worst prognosis. Careful investigation of these patients is required, particularly to identify the tumour type, the source of hypergastrinaemia and the presence of metastases. Treatment can be directed at the source of hypergastrinaemia if type I or II tumours are still gastrin responsive and not growing autonomously. Type III tumours should be treated surgically.

Conclusions

Advances in our understanding of the pathogenesis of gastric carcinoids have led to recent improvements in investigation and management. Challenges remain in identifying the genetic and environmental factors, in addition to hypergastrinaemia, that are responsible for tumour development in susceptible patients.
Acquired C1 esterase inhibitor deficiency: an atypical first presentation intra‐operatively
Authors: Hendron D. , Reid M.
Published: October 2006

We report a case of airway difficulties encountered as a result of blistering, oedema and bleeding from the oropharyngeal mucosa of an 85‐year‐old female undergoing an elective excision of a submandibular neck lump. This led to a delay in extubation by several hours. The patient was subsequently found to have an acquired form of C1 esterase inhibitor deficiency considered to be consequent of haematological malignancy.
The management of severe emergence agitation using droperidol
Authors: Hatzakorzian R. , Shan W. Li Pi , Côté A. V. , Schricker T. , Backman S. B.
Published: October 2006

Emergence agitation can occur following recovery from general anaesthesia. The patient may exhibit aggressive behaviour, disorientation, agitation and restlessness. Untreated, this complication may result in significant morbidity. We report two cases where droperidol was successfully used in the management of severe emergence agitation. In the first case, droperidol was administered to prevent the occurrence of postoperative agitation in a patient known to suffer from this condition following previous general anaesthetics. In the second case, droperidol was used to treat emergence agitation in a morbidly obese patient with a difficult airway who was aggressive and difficult to restrain. Both of these patients remained calm and co‐operative, with stable cardio‐respiratory parameters, following the administration of droperidol and showed no further signs of agitation. We suggest that droperidol is an effective medication that may be used to prevent and treat severe emergence agitation due to its rapid sedative effect and minimal cardio‐respiratory depression.
A comparison of cyclizine and granisetron alone and in combination for the prevention of postoperative nausea and vomiting
Authors: Johns R. A. , Hanousek J. , Montgomery J. E.
Published: October 2006

We conducted a randomised double‐blinded study of 960 women undergoing day‐case surgery to determine whether combination anti‐emetic therapy of granisetron and cyclizine was more effective at decreasing the incidence of postoperative nausea and vomiting than these agents used alone. The women were randomly allocated to three groups to receive intravenous granisetron 1 mg, cyclizine 50 mg or both before induction of general anaesthesia. The incidence of postoperative nausea and vomiting was 77/322 (24%) in the granisetron group, 73/316 (23%) in the cyclizine group and 53/322 (17%) in those women given both drugs (p = 0.04). There was no difference in the requirement for rescue anti‐emetic drugs. There were no differences in the anaesthetic techniques used in the three groups. We conclude that the risk of postoperative nausea and vomiting is less with cyclizine and granisetron given together than with either given alone.