bluuebunny/crossref_metadata_2025 huggingface dataset:
Scattering database in the millimeter and submillimeter wave range of 100–1000 GHz for nonspherical ice particles
Authors: Hong Gang , Yang Ping , Baum Bryan A. , Heymsfield Andrew J. , Weng Fuzhong , Liu Quanhua , Heygster Georg , Buehler Stefan A.
Published: March 2009

The inference of ice cloud properties from spaceborne sensors is sensitive to the retrieval algorithms and satellite sensors used. To approach a better understanding of ice cloud properties, it is necessary to combine satellite measurements from multiple platforms and sensors operating in visible, infrared, and millimeter and submillimeter‐wave regions of the electromagnetic spectrum. The single‐scattering properties of ice particles with consistent ice particle models are the basis for estimating the optical and microphysical properties of ice clouds from multiple satellite sensors. In this study, the single‐scattering properties (extinction efficiency, absorption efficiency, single‐scattering albedo, asymmetry factor, and scattering phase matrix) of nonspherical ice particles, assumed to be hexagonal solid and hollow columns, hexagonal plates, 3D bullet rosettes, aggregates, and droxtals, are computed from the discrete dipole approximation method for 21 millimeter and submillimeter‐wave frequencies ranging from 100 to 1000 GHz. A database of the single‐scattering properties of nonspherical ice particles are developed for 38 particle sizes ranging from 2 to 2000 μm in terms of particle maximum dimension. The bulk scattering properties of ice clouds consisting of various ice particles, which are the fundamental to the radiative transfer in ice clouds, are developed on the basis of a set of 1119 particle size distributions obtained from various field campaigns.
Gravity waves in the upper atmosphere of Venus revealed by CO2 nonlocal thermodynamic equilibrium emissions
Authors: Garcia R. F. , Drossart P. , Piccioni G. , López‐Valverde M. , Occhipinti G.
Published: March 2009

The imaging capabilities of the Visible and Infrared Thermal Imaging Spectrometer‐Mapper (VIRTIS‐M) onboard Venus Express mission are used to analyze perturbations of CO2 nonlocal thermodynamic equilibrium emissions in the thermosphere of Venus. These emissions with a wavelength of 4.3 μm originate from the 110–140 km altitude range and are sensitive to density perturbations. They show wave‐like perturbations of about 0.5% root‐mean‐square amplitude of the background signal with horizontal wavelengths in the 90–400 km range. The horizontal phase velocities are similar in magnitude and direction from one orbit to the next, with averages of 70 m/s westward and 30 m/s northward. The geographical wave distribution and the orientation of wavefronts demonstrate that the polar vortex at work in the cloud layer is the source of these gravity waves. The large westward zonal phase velocity in the 0900–1500 local time range argues in favor of the superrotation dynamics within 30° from the south pole to an altitude of at least 115 km. The gravity wave dispersion relation and the geographical distribution of wavefront amplitudes suggest the presence of a solar to antisolar wind close to the south pole. Because the centroid altitude and the sensitivity of these emissions to gravity wave perturbations are only roughly estimated, it is not possible to make a quantitative estimate of the upward energy transfer. However, this study demonstrates the strong influence of the polar vortex on the circulation in the atmosphere of Venus up to the thermosphere.
RAGE: a novel biological and genetic marker for vascular disease
Authors: Kalea Anastasia Z. , Schmidt Ann Marie , Hudson Barry I.
Published: March 2009

RAGE [receptor for AGEs (advanced glycation end-products)] plays an important role in the development and progression of vascular disease. Studies in cultured cells and small animal models of disease have clearly demonstrated that RAGE is central to the pathogenesis of vascular disease of the macro- and micro-vessels in both the diabetic and non-diabetic state. Emerging results from human clinical studies have revealed that levels of circulating soluble RAGE in the plasma may reflect the presence and/or extent of vascular disease state. Additionally, genetic variants of the RAGE gene (AGER in HUGO nomenclature) have been associated with vascular disease risk. Combining RAGE circulating protein levels and the presence of particular RAGE polymorphisms may be a useful clinical tool for the prediction of individuals at risk for vascular disease. Therapeutic intervention targeted at the RAGE gene may therefore be a useful means of treating pathologies of the vasculature.
The current relaxation behavior of Li doped 0.7(Ba,Sr)TiO3–0.3MgO thick film interdigitated capacitors
Authors: Kim Se-Ho , Koh Jung-Hyuk
Published: March 2009

In this experiment, Li (3 wt %) and MgO (30 wt %) were added to Ba0.5Sr0.5TiO3 powders made by conventional mixed method. BaSrTiO3 materials have high dielectric permittivity (>500 at 1 MHz) and low loss tangent (0.01 at 1 MHz) in epitaxial thin film form. To improve dielectric properties and reduce the sintering temperature, MgO and Li were added to BaSrTiO3, respectively. Li doped 0.7(Ba,Sr)TiO3–0.3MgO thick films were fabricated by screen printing method on the almunia (Al2O3) substrates and then sintered at 1200 °C. interdigitated electrode patterns, which consisted of seven fingers separated by 200 μm gap, were also formed employing the Ag electrode through screen printing methods. I-V (current-voltage) characteristics were measured in the range of ±4.5 kV/cm with an elevated temperature from 30 to 110 °C. To understand the time dependent current relaxation behavior, I-T (current-time) characteristics were also measured in 30, 60, 90, and 100 V by 6517A electrometer/high resistance meter.
A modified scaling law for 180° stripe domains in ferroic thin films
Authors: Zhao G.-P. , Chen Lang , Wang Junling
Published: March 2009

The periodicity of 180° stripe domains has been calculated analytically by assuming a linear change in magnetization/polarization in the domain wall. A modified scaling law was proposed between the domain period and the film thickness for ferroelectric and ferromagnetic thin films. Both the slope and intercept of this scaling line can be used to get domain wall thickness in a consistent manner, which enriches the understanding of domain walls. Theoretical results have been used to compare with recent experimental data and suggest a good agreement.
Leakage current evolution versus dielectric thickness in lead zirconate titanate thin film capacitors
Authors: Chentir Mohamed-Tahar , Bouyssou Emilien , Ventura Laurent , Anceau Christine
Published: March 2009

In this paper, the evolution of lead zirconate titanate (PZT) capacitor leakage current mechanism as a function of dielectric thickness has been investigated. It has been pointed out that PZT leakage current switches from Schottky to Poole–Frenkel conduction mechanisms as PZT thickness decreases. The leakage current evolution seems to be dependant on the presence of a dead layer at metal/PZT interface. The dead layer thickness is estimated at about 40 nm. The switch from an interface limited conduction mode to a bulk limited mode can be attributed to the presence of a higher defect concentration in the dead layer in comparison with PZT bulk.
Properties of p-n heterojunction diode based on Ge2Sb2Te5 and its application for phase change random access memory
Authors: Tang Li , Zhou Peng , Wan Haijun , Jin Gang , Chen B. A. , Tang Ting-ao , Lin Yinyin
Published: March 2009

Heterojunction diodes are fabricated using p-type Ge2Sb2Te5 and low doped n-type silicon wafer. Rectification is observed with a ratio of forward-to-reverse current as high as 104 and 103 for crystal-Ge2Sb2Te5/n-Si junction and amorphous-Ge2Sb2Te5/n-Si junction, respectively. The approximate equilibrium energy-band diagrams for both crystal-Ge2Sb2Te5/n-Si heterojunction diodes and amorphous-Ge2Sb2Te5/n-Si heterojunction diodes are proposed to explain the properties of the p-Ge2Sb2Te5/n-Si heterojunction diode. Properties of a p-n heterojunction diode based on Ge2Sb2Te5 are proposed to apply in 0T1R cross-point structure array for reliable read operation and for decreasing the sneaking current.
Impact of misfit relaxation and a-domain formation on the electrical properties of tetragonal PbZr0.4Ti0.6O3/PbZr0.2Ti0.8O3 thin film heterostructures: Experiment and theoretical approach
Authors: Feigl Ludwig , Misirlioglu I. B. , Vrejoiu Ionela , Alexe Marin , Hesse Dietrich
Published: March 2009

Heterostructures consisting of PbZr0.2Ti0.8O3 and PbZr0.4Ti0.6O3 epitaxial films on a SrTiO3 (100) substrate with a SrRuO3 bottom electrode were prepared by pulsed laser deposition. By using the additional interface provided by the ferroelectric bilayer structure and changing the sequence of the layers, the content of dislocations and elastic domain types was varied in a controlled manner. The resulting microstructure was investigated by transmission electron microscopy. Macroscopic ferroelectric measurements have shown a large impact of the formation of dislocations and 90° domain walls on the ferroelectric polarization and dielectric constant. A thermodynamic analysis using the Landau–Ginzburg–Devonshire approach that takes into account the ratio of the thicknesses of the two ferroelectric layers and electrostatic coupling is used to shed light on the experimental data.
Size dependent microwave properties of ferrite nanoparticles: Application to microwave devices
Authors: Kuanr Bijoy K. , Veerakumar V. , Lingam K. , Mishra S. R. , Kuanr Alka V. , Camley R. E. , Celinski Z.
Published: March 2009

We studied the magnetic field dependence of the resonance frequency (fr) and frequency linewidth (Δf) of iron oxide nanoparticles (Fe3O4) with different particle sizes spin-coated on a coplanar waveguide. Using a vector network analyzer, we find that the resonance frequency increases with an increase in applied field for all particle sizes, while Δf decreases with the increase in the particle size. We have also carried out a theoretical study using the power absorbed by the different regions of the coplanar waveguide and found that the results are in accordance with the experiment.
Magnetoresistance and spin transfer torque in electrodeposited Co/Cu multilayered nanowire arrays with small diameters
Authors: Huang Xiaobo , Tan Liwen , Cho Haeseok , Stadler Bethanie J. H.
Published: March 2009

Multilayered Co/Cu nanowires with 10 nm diameter were fabricated as arrays in anodic aluminum oxide templates. Magnetization hysteresis (MH) loops and current perpendicular to the plane giant magnetoresistance (CPP-GMR) were measured as functions of Cu layer thicknesses. The largest CPP-GMR values (11%, or 19.5% for multilayers alone) were found in nanowire arrays that had identical MH loops whether the field was applied parallel or perpendicular to the wires. Spin transfer torque (STT) switching was measured in the 10 nm diameter nanowires and also in 60 nm diameter wires. For the 10 nm diameter nanowires, these STT curves were overlaid with small jumps (1%–2%) that were attributed to individual layers flipping and larger jumps (6.25%) that were due to collective spin flips between interacting Co layers. For larger diameter nanowires, the individual spin flips were not present, and the curves were similar to typical STT results. The current densities required to switch the Co layers from antiparallel to parallel and back (JAP-P/JP-AP) were 2.7×108/1.3×108 and 3.2×107/−1.6×107 A/cm2, respectively, for the 10 and 60 nm diameter nanowires. The ability to construct large area arrays of 10 nm CPP-GMR and STT structures makes these first results exciting for eventual use in magnetic random access memory.
Improvement of ferroelectric properties of BiFeO3 thin films by postmetallization annealing and electric field application
Authors: Nakamura Yoshitaka , Nakashima Seiji , Okuyama Masanori
Published: March 2009

We have investigated effects of the postmetallization annealing and the electric field application on ferroelectric properties of BiFeO3 thin films prepared by chemical solution deposition. The leakage current is reduced after the postmetallization annealing although the crystallinity of the polycrystalline BiFeO3 is unchanged. In addition, double coercive field is reduced at about 90 kV/cm after the postmetallization annealing, while remanent polarization of 90 μC/cm2 is almost the same at 80 K. The postmetallization annealing is considered to lead the improvement of contact between the BiFeO3 film and the Pt electrode or the reduction in defects near the interface between the BiFeO3 film and the Pt electrode. Moreover, once a high electric field of 2.8 MV/cm is applied, the ferroelectric property of BiFeO3 thin films is dramatically improved. This effect may be due to the relaxation of pinned domains or locked polarizations in the BiFeO3 film. The postmetallization annealing and the electric field application are effective to improve ferroelectric properties of BiFeO3 thin films.
Influence of background gas ionization on oscillations in a virtual cathode with a retarding potential
Authors: Filatov R. A. , Hramov A. E. , Bliokh Y. P. , Koronovskii A. A. , Felsteiner J.
Published: March 2009

The effect of mobile ion background on the dynamics of a planar virtual cathode with retarding field is investigated. The ions appear in the diode gap due to ionization of a neutral gas by the electron beam. Detailed examination of the self-consistent processes of the virtual cathode dynamics, gas ionization, and ions motion is performed using the particle-in-cell simulation. It is shown that the presence of ions leads to the virtual cathode neutralization, its displacement, and subsequent anew formation. The microwave generation has the form of a sequence of pulse packets, whose duration depends on the value of the retarding potential and the kind of gas.
First principles study of the photo-oxidation of water on tungsten trioxide (WO3)
Authors: Valdés Á. , Kroes G.-J.
Published: March 2009

The photo-oxidation of water on the monoclinic P21/nWO3 (200, 020, and 002) surfaces is investigated using density functional theory calculations, employing the PW91-generalized gradient approximation, and the method developed by Nørskov et al. [J. Phys. Chem. B 108, 17886 (2004)] based on the free energy differences between the reaction intermediates. We first relax the bulk material unit cell and then investigate the relative stability of different surface terminations of WO3 and analyze the overpotential needed for the photoelectrolysis of water. We found that the rate limiting step is the transfer of a proton from the surface adsorbed OH to the electrolyte, and that the computed overpotential for O2 evolution (1.04 V) is available upon illumination of the surface with visible light.
Effect of atomic ordering on hydrogen dissociation on Ni3Fe surfaces
Authors: Cheng X. Y. , Chung Yip-Wah , Zhao Bo , Hong B. , Liu C. T.
Published: March 2009

The dissociation of molecular to atomic hydrogen on clean surfaces of Ni3Fe with either an ordered or disordered structure has been directly investigated by thermal desorption studies. Results show that when exposed to an ordered Ni3Fe surface, molecular hydrogen dissociates to produce atomic hydrogen, which desorbs from the surface around 350 K. On the other hand, hydrogen does not dissociate on a disordered Ni3Fe surface. These results indicate that atomic ordering has a marked effect on surface chemical reactivity. Furthermore, our study provides a mechanistic basis to explain the hydrogen-induced embrittlement in ordered Ni3Fe but not in disordered Ni3Fe.
Surface modification of highly ordered TiO2 nanotube arrays for efficient photoelectrocatalytic water splitting
Authors: Lin Chin-Jung , Lu Yen-Tien , Hsieh Chang-Hsun , Chien Shu-Hua
Published: March 2009

An efficient visible-light-sensitive heterostructure photoanode of CdS nanoparticles/ZnO shell/TiO2 nanotube (CdS/ZnO–TiNT) arrays were investigated for solar water splitting. Highly ordered arrays of TiNT were grown vertically on Ti foil by electrochemical anodization. Both aqueous solution routes were used in turn to coat a thin recombination barrier of ZnO shell and narrow band gap CdS nanoparticles to the surface of the TiNT arrays. As a result of strong absorption within solar spectrum and effective suppression of electron-hole pair recombination in CdS/ZnO–TiNT arrays, a significant improvement in solar-to-hydrogen conversion efficiency from 0.39% to 1.30% was obtained.
‘Improving little by little, every day’: the road to Operational Excellence
Authors: VAN CAMPEN Johan , HERTZBERGER Eveline
Published: March 2009

Lean Six Sigma is a business methodology that is rapidly attracting followers across production and service industries. This includes the publishing world, with several companies now implementing the program. The subscription agent Swets is also implementing Lean Six Sigma for its processes. This article describes the challenges and benefits of implementing Lean Six Sigma at Swets, highlighting the applicability of the program to the area of subscription management and illustrating how beneficial the initiative can be for publishers, customers, and Swets alike.
Sexual segregation of pelagic sharks and the potential threat from fisheries
Authors: Mucientes Gonzalo R , Queiroz Nuno , Sousa Lara L , Tarroso Pedro , Sims David W
Published: March 2009

Large pelagic sharks are declining in abundance in many oceans owing to fisheries exploitation. What is not known however is whether within-species geographical segregation of the sexes exacerbates this as a consequence of differential exploitation by spatially focused fisheries. Here we show striking sexual segregation in the fastest swimming shark, the shortfin mako
Isurus oxyrinchus
, across the South Pacific Ocean. The novel finding of a sexual ‘line in the sea’ spans a historical longline-fishing intensity gradient, suggesting that differential exploitation of the sexes is possible, a phenomenon which may underlie changes in the shark populations observed elsewhere.
Scattering of anti-plane shear waves by an interface crack between two bonded dissimilar functionally graded piezoelectric materials
Authors: Singh B.M , Rokne J , Dhaliwal R.S , Vrbik J
Published: March 2009

In the present paper, the dynamic behaviour of a Griffith crack situated at the interface of two bonded dissimilar functionally graded piezoelectric materials (FGPMs) is considered. It is assumed that the elastic stiffness, piezoelectric constant, dielectric permittivity and mass density of the FGPMs vary continuously as an exponential function of the
x
and
y
coordinates, and that the FGPMs are under anti-plane mechanical loading and in-plane electrical loading. By using an integral transform technique the problem is reduced to four pairs of dual integral equations, which are transformed into four simultaneous Fredholm integral equations with four unknown functions. By solving the four simultaneous Fredholm integral equations numerically the effects of the material properties on the stress and electric displacement intensity factors are calculated and displayed graphically.
Vibration analysis of submerged rectangular microplates with distributed mass loading
Authors: Wu Zhangming , Ma Xianghong , Brett Peter N , Xu Jinwu
Published: March 2009

This paper investigates the vibration characteristics of the coupling system of a microscale fluid-loaded rectangular isotropic plate attached to a uniformly distributed mass. Previous literature has, respectively, studied the changes in the plate vibration induced by an acoustic field or by the attached mass loading. This paper investigates the issue of involving these two types of loading simultaneously. Based on Lamb's assumption of the fluid-loaded structure and the Rayleigh–Ritz energy method, this paper presents an analytical solution for the natural frequencies and mode shapes of the coupling system. Numerical results for microplates with different types of boundary conditions have also been obtained and compared with experimental and numerical results from previous literature. The theoretical model and novel analytical solution are of particular interest in the design of microplate-based biosensing devices.
A thermoelastic junction problem in a thin-walled structure: asymptotic analysis
Authors: Zalipaev V.V , Jones I.S , Movchan A.B
Published: March 2009

The two-dimensional model for a thin-walled structure in the plane strain time-harmonic case is discussed. A model of a surface crack defect subjected to oscillatory thermal loading in the middle part of the thin-walled bridges is presented. As a first part of the asymptotic model, the effective transmission condition in the vicinity of a deep surface-breaking crack in a thin-walled bridge is discussed. Then, the two-term boundary layer model determining the asymptotic behaviour of the field near the tip of the crack is constructed.
Modelling the effect of habitat fragmentation on range expansion in a butterfly
Authors: Wilson Robert J , Davies Zoe G , Thomas Chris D
Published: March 2009

There is an increasing need for conservation programmes to make quantitative predictions of biodiversity responses to changed environments. Such predictions will be particularly important to promote species recovery in fragmented landscapes, and to understand and facilitate distribution responses to climate change. Here, we model expansion rates of a test species (a rare butterfly,Hesperia comma) in five landscapes over 18 years (generations), using a metapopulation model (the incidence function model). Expansion rates increased with the area, quality and proximity of habitat patches available for colonization, with predicted expansion rates closely matching observed rates in test landscapes. Habitat fragmentation constrained expansion, but in a predictable way, suggesting that it will prove feasible both to understand variation in expansion rates and to develop conservation programmes to increase rates of range expansion in such species.
Reiterative pattern ofsonic hedgehogexpression in the catshark dentition reveals a phylogenetic template for jawed vertebrates
Authors: Smith Moya M , Fraser Gareth J , Chaplin Natalie , Hobbs Carl , Graham Anthony
Published: March 2009

For a dentition representing the most basal extant gnathostomes, that of the shark can provide us with key insights into the evolution of vertebrate dentitions. To detail the pattern of odontogenesis, we have profiled the expression ofsonic hedgehog, a key regulator of tooth induction. We find in the catshark (Scyliorhinus canicula) that intenseshhexpression first occurs in a bilaterally symmetrical pattern restricted to broad regions in each half of the dentition in the embryo jaw. As in the mouse, there follows a changing temporal pattern ofshhspatial restriction corresponding to epithelial bands of left and right dental fields, but also a subfield for symphyseal teeth. Then, intenseshhexpression is restricted to loci coincident with a temporal series of teeth in iterative jaw positions. The developmental expression ofshhreveals previously undetected timing within epithelial stages of tooth formation. Each locus at alternate, even then odd, jaw positions establishes precise sequential timing for successive replacement within each tooth family.Shhappears first in the central cusp, iteratively along the jaw, then reiteratively within each tooth for secondary cusps. This progressive, sequential restriction ofshhis shared by toothed gnathostomes and conserved through 500 million years of evolution.
Scaling rules for the final decline to extinction
Authors: Griffen Blaine D , Drake John M
Published: March 2009

Space–time scaling rules are ubiquitous in ecological phenomena. Current theory postulates three scaling rules that describe the duration of a population's final decline to extinction, although these predictions have not previously been empirically confirmed. We examine these scaling rules across a broader set of conditions, including a wide range of density-dependent patterns in the underlying population dynamics. We then report on tests of these predictions from experiments using the cladoceranDaphnia magnaas a model. Our results support two predictions that: (i) the duration of population persistence is much greater than the duration of the final decline to extinction and (ii) the duration of the final decline to extinction increases with the logarithm of the population's estimated carrying capacity. However, our results do not support a third prediction that the duration of the final decline scales inversely with population growth rate. These findings not only support the current standard theory of population extinction but also introduce new empirical anomalies awaiting a theoretical explanation.
Dynamics of range margins for metapopulations under climate change
Authors: Anderson B.J , Akçakaya H.R , Araújo M.B , Fordham D.A , Martinez-Meyer E , Thuiller W , Brook B.W
Published: March 2009

We link spatially explicit climate change predictions to a dynamic metapopulation model. Predictions of species' responses to climate change, incorporating metapopulation dynamics and elements of dispersal, allow us to explore the range margin dynamics for two lagomorphs of conservation concern. Although the lagomorphs have very different distribution patterns, shifts at the edge of the range were more pronounced than shifts in the overall metapopulation. For
Romerolagus diazi
(volcano rabbit), the lower elevation range limit shifted upslope by approximately 700 m. This reduced the area occupied by the metapopulation, as the mountain peak currently lacks suitable vegetation. For
Lepus timidus
(European mountain hare), we modelled the British metapopulation. Increasing the dispersive estimate caused the metapopulation to shift faster on the
northern
range margin (leading edge). By contrast, it caused the metapopulation to respond to climate change
slower
, rather than faster, on the
southern
range margin (trailing edge). The differential responses of the leading and trailing range margins and the relative sensitivity of range limits to climate change compared with that of the metapopulation centroid have important implications for where conservation monitoring should be targeted. Our study demonstrates the importance and possibility of moving from simple bioclimatic envelope models to second-generation models that incorporate both dynamic climate change and metapopulation dynamics.
Emission of methane from plants
Authors: Nisbet R.E.R , Fisher R , Nimmo R.H , Bendall D.S , Crill P.M , Gallego-Sala A.V , Hornibrook E.R.C , López-Juez E , Lowry D , Nisbet P.B.R , Shuckburgh E.F , Sriskantharajah S , Howe C.J , Nisbet E.G
Published: March 2009

It has been proposed that plants are capable of producing methane by a novel and unidentified biochemical pathway. Emission of methane with an apparently biological origin was recorded from both whole plants and detached leaves. This was the first report of methanogenesis in an aerobic setting, and was estimated to account for 10–45 per cent of the global methane source. Here, we show that plants do not contain a known biochemical pathway to synthesize methane. However, under high UV stress conditions, there may be spontaneous breakdown of plant material, which releases methane. In addition, plants take up and transpire water containing dissolved methane, leading to the observation that methane is released. Together with a new analysis of global methane levels from satellite retrievals, we conclude that plants are not a major source of the global methane production.
The rise and fall of an arbitrary tradition: an experiment with wild meerkats
Authors: Thornton Alex , Malapert Aurore
Published: March 2009

Humans often follow the choices of others, even when profitable alternatives exist, leading to the maintenance of arbitrary traditions. Arbitrary traditions have also been shown to persist in captive groups of other animals, but it is unclear whether they do so in the wild where there are ample opportunities for exploring alternatives. We conducted the first experiment examining the maintenance of arbitrary traditions in wild mammal groups. We trained ‘demonstrators’ in seven meerkat groups to obtain rewards from one out of the two distinctive landmarks. Two control groups had no trained demonstrators. Naive individuals initially ignored the landmarks, but were more likely to approach them and obtain rewards following encounters with demonstrators. Individuals in control groups were less likely to obtain rewards. While control groups showed no landmark preference, experimental groups initially preferred the landmark chosen by demonstrators, even though an equally rewarding alternative was nearby, leading to the establishment of local traditions. However, individuals that learned that one landmark was profitable began to explore the other rather than conforming to the majority behaviour, so traditions collapsed over time. This suggests that where conformist tendencies are lacking, the maintenance of traditions in natural populations depends on the relative influence of social and individual learning.
Do climate envelope models transfer? A manipulative test using dung beetle introductions
Authors: Duncan Richard P , Cassey Phillip , Blackburn Tim M
Published: March 2009

Climate envelope models (CEMs) are widely used to forecast future shifts in species ranges under climate change, but these models are rarely validated against independent data, and their fundamental assumption that climate limits species distributions is rarely tested. Here, we use the data on the introduction of five South African dung beetle species to Australia to test whether CEMs developed in the native range can predict distribution in the introduced range, where the confounding effects of dispersal limitation, resource limitation and the impact of natural enemies have been removed, leaving climate as the dominant constraint. For two of the five species, models developed in the native range predict distribution in the introduced range about as well as models developed in the introduced range where we know climate limits distribution. For the remaining three species, models developed in the native range perform poorly, implying that non-climatic factors limit the native distribution of these species and need to be accounted for in species distribution models. Quantifying relevant non-climatic factors and their likely interactions with climatic variables for forecasting range shifts under climate change remains a challenging task.
Actuation systems in plants as prototypes for bioinspired devices
Authors: Burgert Ingo , Fratzl Peter
Published: March 2009

Plants have evolved a multitude of mechanisms to actuate organ movement. The osmotic influx and efflux of water in living cells can cause a rapid movement of organs in a predetermined direction. Even dead tissue can be actuated by a swelling or drying of the plant cell walls. The deformation of the organ is controlled at different levels of tissue hierarchy by geometrical constraints at the micrometre level (e.g. cell shape and size) and cell wall polymer composition at the nanoscale (e.g. cellulose fibril orientation). This paper reviews different mechanisms of organ movement in plants and highlights recent research in the field. Particular attention is paid to systems that are activated without any metabolism. The design principles of such systems may be particularly useful for a biomimetic translation into active technical composites and moving devices.
Thermodynamics of surface degradation, self-organization and self-healing for biomimetic surfaces
Authors: Nosonovsky Michael , Bhushan Bharat
Published: March 2009

Friction is a dissipative irreversible process; therefore, entropy is produced during frictional contact. The rate of entropy production can serve as a measure of degradation (e.g. wear). However, in many cases friction leads to self-organization at the surface. This is because the excess entropy is either driven away from the surface, or it is released at the nanoscale, while the mesoscale entropy decreases. As a result, the orderliness at the surface grows. Self-organization leads to surface secondary structures either due to the mutual adjustment of the contacting surfaces (e.g. by wear) or due to the formation of regular deformation patterns, such as friction-induced slip waves caused by dynamic instabilities. The effect has practical applications, since self-organization is usually beneficial because it leads to friction and wear reduction (minimum entropy production rate at the self-organized state). Self-organization is common in biological systems, including self-healing and self-cleaning surfaces. Therefore, designing a successful biomimetic surface requires an understanding of the thermodynamics of frictional self-organization. We suggest a multiscale decomposition of entropy and formulate a thermodynamic framework for irreversible degradation and for self-organization during friction. The criteria for self-organization due to dynamic instabilities are discussed, as well as the principles of biomimetic self-cleaning, self-lubricating and self-repairing surfaces by encapsulation and micro/nanopatterning.
Biomimicry as a route to new materials: what kinds of lessons are useful?
Authors: Reed Emily J , Klumb Lisa , Koobatian Maxwell , Viney Christopher
Published: March 2009

We consider the attributes of a successful engineered material, acknowledging the contributions of composition and processing to properties and performance. We recognize the potential for relevant lessons to be learned from nature, at the same time conceding both the limitations of such lessons and our need to be selective. We then give some detailed attention to the molecular biomimicry of filamentous phage, the process biomimicry of silk and the structure biomimicry of hippopotamus ‘sweat’, in each case noting that the type of lesson now being learned is not the same as the potential lesson that originally motivated the study.
Biomimetics: lessons from nature–an overview
Authors: Bhushan Bharat
Published: March 2009

Nature has developed materials, objects and processes that function from the macroscale to the nanoscale. These have gone through evolution over 3.8 Gyr. The emerging field of biomimetics allows one to mimic biology or nature to develop nanomaterials, nanodevices and processes. Properties of biological materials and surfaces result from a complex interplay between surface morphology and physical and chemical properties. Hierarchical structures with dimensions of features ranging from the macroscale to the nanoscale are extremely common in nature to provide properties of interest. Molecular-scale devices, superhydrophobicity, self-cleaning, drag reduction in fluid flow, energy conversion and conservation, high adhesion, reversible adhesion, aerodynamic lift, materials and fibres with high mechanical strength, biological self-assembly, antireflection, structural coloration, thermal insulation, self-healing and sensory-aid mechanisms are some of the examples found in nature that are of commercial interest. This paper provides a broad overview of the various objects and processes of interest found in nature and applications under development or available in the marketplace.
Human papillomavirus infections among Japanese women: age‐related prevalence and type‐specific risk for cervical cancer
Authors: Onuki Mamiko , Matsumoto Koji , Satoh Toyomi , Oki Akinori , Okada Satoshi , Minaguchi Takeo , Ochi Hiroyuki , Nakao Sari , Someya Katsumi , Yamada Naoki , Hamada Hiromi , Yoshikawa Hiroyuki
Published: March 2009

To obtain baseline data for human papillomavirus (HPV) screening and vaccination in Japan, we analyzed HPV DNA data from 2282 Japanese women (1517 normal cytology, 318 cervical intraepithelial neoplasia [CIN] grade 1, 307 CIN2–3, and 140 invasive cervical cancer [ICC]) that visited the University of Tsukuba Hospital or Ibaraki Seinan Medical Center Hospital for screening or treatment of cervical diseases between 1999 and 2007. An L1‐based PCR method was used for individual HPV genotyping. The most common HPV types in ICC were, in order of decreasing prevalence, HPV16 (40.5%), HPV18 (24.4%), HPV52 (8.4%), HPV58 (3.1%), and HPV33 (3.1%). Based on the comparison of HPV type distributions between normal cytology and CIN2–3 and ICC, estimated risk of disease progression varied considerably by genotype: HPV16, HPV18, HPV31, HPV33, HPV35, HPV52, and HPV58 (prevalence ratio, 1.92; 95% confidence interval 1.58–2.34); other oncogenic types (0.31, 95% confidence interval 0.19–0.50); and non‐oncogenic types (0.09, 95% confidence interval 0.03–0.43). HPV16 and/or HPV18, including coinfections with other types, contributed to 67.1% of ICC and 36.2% of CIN2–3 among Japanese women. More importantly, the overall prevalence of HPV16 and/or HPV18 varied greatly according to the women's age: highest in women aged 20–29 years (ICC, 90.0%; CIN2–3, 53.9%), decreasing with age thereafter, and lowest in women aged 60 years or older (ICC, 56.3%; CIN2–3, 25.0%). In conclusion, type‐specific HPV testing may help identify Japanese women at high risk of progression to CIN2–3 and cancer. In Japan, current HPV vaccines are estimated to provide approximately 70% protection against ICC and may be more useful in reducing the incidence of cervical cancer and precancer in young women of reproductive age. (Cancer Sci 2009; 100: 1312–1316)
Pantoea ananatis: an unconventional plant pathogen
Authors: COUTINHO TERESA A. , VENTER STEPHANUS N.
Published: March 2009

Pantoea ananatis causes disease symptoms in a wide range of economically important agricultural crops and forest tree species worldwide. It is regarded as an emerging pathogen based on the increasing number of reports of diseases occurring on previously unrecorded hosts in different parts of the world. Its unconventional nature lies in the fact that, unlike the majority of plant pathogenic microbes, P. ananatis is capable of infecting humans and occurs in diverse ecological niches, such as part of a bacterial community contaminating aviation jet fuel tanks and contributing to growth promotion in potato and pepper.

Taxonomy: Bacteria; Gammaproteobacteria; family Enterobacteriaceae; genus Pantoea.

Microbiological properties: Gram‐negative; facultatively anaerobic; most strains are motile and produce a yellow pigment in culture; indole positive.

Biology: Pantoea ananatis is a common epiphyte; it also occurs endophytically in hosts where it has been reported to cause disease symptoms and in hosts where no such symptoms have been described. Some strains are ice‐nucleating, a feature which has been used as a biological control mechanism against some insect pests of agricultural crops and by the food industry.

Disease symptoms: Pantoea ananatis infects both monocotyledonous and dicotyledonous plants. The symptoms are diverse depending on the host infected, and include leaf blotches and spots, die‐back, and stalk, fruit and bulb rot.

Biological control agent: Pantoea ananatis has both antifungal and antibacterial properties. These characteristics have the potential of being exploited by biological control specialists.
Management of emergency cardiac surgery in a patient with alloanti‐Ge2
Authors: Selleng S. , Selleng K. , Zawadzinski C. , Wollert H.‐G. , Yürek S. , Greinacher A.
Published: March 2009

summary Transfusion management of patients alloimmunized against high‐prevalence erythrocyte antigens is often problematic in emergency situations. In these patients, incompatible transfusion may be less harmful for the patient than delaying surgery, especially if the antibody is not clinically significant. We report an untransfused 75‐year‐old Caucasian man (blood group O) with an alloantibody against the Gerbich‐2 (Ge2) antigen who required emergency cardiac surgery. Because cross‐match compatible blood was not available in an acceptable timeframe, we performed a ‘biological cross‐match’ with sequential transfusion of 20 and 50 mL and then the entire unit of incompatible red blood cells (RBCs) before surgery. When there were no clinical symptoms of adverse biological effects, we transfused two further incompatible packed RBCs during surgery. Subsequently, there was neither clinical nor laboratory evidence of major intra‐ or extravascular haemolysis, suggesting that this anti‐Ge2 antibody was not clinically significant.
Chagas’ disease: lessons from routine donation testing
Authors: Castro E.
Published: March 2009

summary American Trypanosomiasis, or Chagas’ disease, is a parasitic infection caused by the protozoan Trypanosoma cruzi. It is endemic in a large area of the American continent, extending from Mexico to Argentina. Imported Chagas’ disease is now appearing as a new threat to non‐endemic countries, mostly because of a steady increase of foreign residents from Latin America. Chagas’ disease becomes chronic in the vast majority of infected individuals. This finding gives rise to problems for blood transfusion services. In non‐endemic countries, transfusion is the most likely infection route. Strategies to reduce transmission by transfusion include blood donor selection and deferral, blood donation testing, leukoreduction, filters and pathogen inactivation systems. Policies in endemic and non‐endemic areas are quite different: in endemic countries, universal screening of blood donations for T. cruzi antibody detection is mandatory. However, in non‐endemic countries, there are two different approaches: one is the deferral of people at risk of Chagas’ disease and the second approach is to accept the blood donation if specific laboratory assay results are negative. This second approach is being introduced in countries where there is a substantial Latin American population, such as United States, Spain and France. The assays used for the detection of T. cruzi are mostly immunologic, made with T. cruzi antigen homogenates or with recombinant antigens. Complementary assays, such as indirect immunofluorescence (IIF) or immunoblot, can help ascertain antibody specificity.
Associations of the variation in the porcine myogenin gene with muscle fibre characteristics, lean meat production and meat quality traits
Authors: Kim J.M. , Choi B.D. , Kim B.C. , Park S.S. , Hong K.C.
Published: March 2009

Pig breeding is aimed at improving lean meat production ability as well as meat quality, and muscle fibre characteristics may be important for enhancing these traits. Therefore, new molecular markers have been demanded for selecting lean meat production ability and meat quality in live animals. Myogenin belongs to the MyoD gene family, and is a candidate gene responsible for muscle fibre characteristics. We identified a new single nucleotide polymorphism (SNP) site in the 5′ upstream region of the myogenin gene (nucleotides C and T). A total of 252 pigs of three breeds were genotyped by polymerase chain reaction–restriction fragment length polymorphism using BspCNI. Additionally, they were genotyped for the previously detected MspI site in the 3′‐flanking region (alleles A and B). The CCBB diplotype had the highest frequency over breeds, followed by TCBB and CCAB. The other diplotypes were not found in studied pigs. Association analysis performed for the markers found that the TCBB diplotype has desirable effects on the total number of fibres (p < 0.002), fibre cross‐sectional area (p < 0.06), and loin eye area (p < 0.001) than the other diplotypes. Moreover, the diplotype had the highest muscle pH value (p < 0.07) and all meat quality traits were near the upper limit of the normal range as a reddish pink, firm and non‐exudative (RFN) pork. Therefore, we suggest that selection for the myogenin diplotypes could improve total muscle fibre number, size and lean meat production ability with good meat quality.
Reproduction of the intertidal barnacle Balanus glandula along an estuarine gradient
Authors: Berger Michael S.
Published: March 2009

The barnacle Balanus glandula is predominantly an open coast species in the Northeast Pacific. However, B. glandula densely inhabits estuaries where environmental conditions such as salinity and temperature drastically differ from the open coast. The increased variability of environmental conditions within an estuary can potentially affect spatial patterns of reproduction in B. glandula. I examined gonad maturity, reproductive periodicity and fecundity, and then calculated reproductive output in B. glandula populations distributed along an estuarine gradient. Results indicated that reproductive output of this intertidal barnacle decreased four times over a spatial scale of kilometers, as a transition occurred from a marine to a freshwater habitat along an estuarine gradient. Additionally, a higher proportion of the population had well‐developed gonads in the oceanic end of the estuary compared to the riverine end. These results indicate how reproductive pattern can significantly vary over a spatial scale of kilometers, resulting in site‐specific contributions of offspring to the larval pool.
Comparison of the fatigue behaviour of two different forms of PMMA
Authors: HOEY D. , TAYLOR D.
Published: March 2009

This study investigates the fatigue behaviour of two forms of polymethylmethacrylate (PMMA): pure PMMA in the form of acrylic glass and PMMA‐based bone cement. Acrylic glass demonstrated superior fatigue strength compared to hand‐mixed porous bone cement but was significantly weaker than pore‐free bone cement. The greater fatigue strength of bone cement in comparison to acrylic glass was attributed to its composite‐like microstructure, containing pre‐polymerized beads which are absent in the amorphous structure of acrylic glass. In tests conducted on notched specimens, the porous bone cement demonstrated superior fatigue strength to acrylic glass. The results could be predicted using the theory of critical distances, with errors no larger than 14%. This approach allowed us to show that, although porosity had a negative influence on the fatigue strength of the plain specimens in comparison to acrylic glass, the presence of porosity had no effect when the samples contained a notch or a hole. This finding is interesting when considering the effort put into removing porosity from bone cement during surgical operations, where it is used in situations where there are sharp stress concentrations in the form of protruding bone and the design features of artificial implants.
Do aggressive funds reallocate their portfolios aggressively?
Authors: Chiang Kevin C. H. , Zhou Xiyu (Thomas)
Published: March 2009

This study examines pairs of asset allocation mutual funds that are controlled for all informational attributes, except for the level of risk aversion. Standard mean‐variance models of portfolio choice suggest that the percentage rebalancing of common stocks in aggressive funds would be the same as that in conservative funds. However, this study finds the rebalancing of common stocks in aggressive funds to be disproportionally less intense.
Estimating structural equation models with non‐normal variables by using transformations
Authors: Montfort Kees van , Mooijaart Ab , Meijerink Frits
Published: March 2009

We discuss structural equation models for non‐normal variables. In this situation the maximum likelihood and the generalized least‐squares estimates of the model parameters can give incorrect estimates of the standard errors and the associated goodness‐of‐fit chi‐squared statistics. If the sample size is not large, for instance smaller than about 1000, asymptotic distribution‐free estimation methods are also not applicable. This paper assumes that the observed variables are transformed to normally distributed variables. The non‐normally distributed variables are transformed with a Box–Cox function. Estimation of the model parameters and the transformation parameters is done by the maximum likelihood method. Furthermore, the test statistics (i.e. standard deviations) of these parameters are derived. This makes it possible to show the importance of the transformations. Finally, an empirical example is presented.