bluuebunny/crossref_metadata_2025 huggingface dataset:
Size dependent strengthening mechanisms in sputtered Fe/W multilayers
Authors: Li Nan , Yu K. Y. , Lee J. , Wang H. , Zhang X.
Published: May 2010

We investigate size dependent strengthening mechanisms in sputtered Fe/W multilayers with individual layer thickness, h, varying from 1 to 200 nm. Microstructure analyses reveal that Fe/W has incoherent bcc/bcc interface when h is greater than 5 nm. When h decreases to 1–2.5 nm, the interface becomes semicoherent, and Fe and W show significant lattice distortions comparing to their bulk counterpart due to interface constraint. The layer thickness dependent drastic variations in x-ray diffraction profiles are simulated well by using an analytical model. Film hardness increases with decreasing h, and approaches a maximum value of 12.5 GPa when h is 1 nm. The layer thickness dependent film hardnesses are compared with analytical models. Koehler’s image force plays a major role in determining the maximum strength of composites at smaller h.
Multiferroic properties in Ba0.93Bi0.07Ti1−xMnxO3 ceramics
Authors: Wang C. H. , Yuan S. L. , Yin S. Y. , Tian Z. M. , Li P.
Published: May 2010

Nominal composition of Ba0.93Bi0.07Ti1−xMnxO3 (x=0, 0.02, and 0.04) ceramics have been prepared by a modified Pechini method. X-ray diffraction analysis reveals that the samples are pure perovskite BaTiO3 (BTO) structure with no trace of impurity phase. The cell volume of the composites increases monotonously with the increase in Mn content, which indicates that Mn ions have been incorporated into the lattice of Ba0.93Bi0.07TiO3. The samples are experimentally confirmed to show ferromagnetic (FM) and ferroelectric behaviors simultaneously at room temperature. The temperature dependent magnetic behaviors show complex magnetic interactions including FM, antiferromagnetic, and paramagnetic. These results suggest that the dopant Bi and Mn help BTO transit from pure ferroelectric to multiferroic materials and the magnetic behaviors can be explained by the bound magnetic polaron model with inhomogeneity of Mn dopant distribution.
High magnetic field sensitivity in Pb(Zr,Ti)O3–Pb(Mg1/3Nb2/3)O3 single crystal/Terfenol-D/Metglas magnetoelectric laminate composites
Authors: Park Chee-Sung , Cho Kyung-Hoon , Arat Mustafa Ali , Evey Jeff , Priya Shashank
Published: May 2010

We report the magnetic field sensitivity results on five layer structure given as Metglas/Terfenol-D/PMN–PZT/Terfenol-D/Metglas, where PMN and PZT correspond to Pb(Mg1/3Nb2/3)O3 and Pb(Zr,Ti)O3, respectively. The piezoelectric constant (d33) of poled PMN–PZT was found to be 1600 pC/N with dielectric constant of 5380 at 1 kHz. The sensitivity measurements were conducted after attaching individual layers in the laminate clearly delineating the effect occurring in the response. The magnetoelectric response for this five layer structure at 1 kHz was found to be 5 V/cm Oe at dc bias field of 1000 Oe under an ac drive of 1 Oe. At 1 kHz frequency, the sensor was able to deterministically measure step changes of 500 nT while at 10 Hz we can clearly identify the sensitivity of 1 μT. These results are very promising for the cheap room-temperature magnetic field sensing technology.
Dynamics of Li+ dipoles at very low concentration in quantum paraelectric potassium tantalate
Authors: Dec J. , Miga S. , Trybuła Z. , Kaszyńska K. , Kleemann W.
Published: May 2010

The dynamics of Li+ dipoles distributed in the quantum paraelectric matrix of potassium tantalate is investigated via linear and nonlinear dielectric response. It is found that the highly diluted solid solution K0.995Li0.005TaO3, KLT(005), reveals nearly ideal Debye-type dipolar relaxation with conventional frequency dispersion at intermediate temperatures, 30<T<60 K. At lower temperatures a drastic increase in the linear dielectric susceptibility is measured as predicted by computer simulations Su et al. [J. Appl. Phys. 90, 6345 (2001)]. Being accompanied by a negative divergence of the third-order nonlinear susceptibility, a transition into a chiral glass state as T→Tg≈6 K is conjectured.
Bauschinger effect in unpassivated freestanding thin films
Authors: Shishvan Siamak Soleymani , Nicola Lucia , Van der Giessen Erik
Published: May 2010

Two-dimensional (2D) discrete dislocation plasticity simulations are carried out to investigate the Bauschinger effect (BE) in freestanding thin films. The BE in plastic flow of polycrystalline materials is generally understood to be caused by inhomogeneous deformation during loading, leading to residual stress upon unloading. This inhomogeneity can be caused by dislocation pile-ups, variations in texture, grain orientations, and grain size. To study the BE, columnar-grained films as well as films with multiple grains across the thickness are considered. The film is modeled in a 2D framework by a unit cell consisting of an array of grains with different orientation. In order to capture the interaction among grains, we motivate and explore the use of an affine deformation assumption on the grain level to mimic the three-dimensional geometry in this framework. It is shown that the dispersion of grain size in a film together with the size-dependence of yield strength leads to significant BEs in bare films. Quantitative comparison of simulations with experimental data is provided.
Synthesis and properties of porous SiC ceramics
Authors: Kiselov V. S. , Lytvyn P. M. , Yukhymchuk V. O. , Belyaev A. E. , Vitusevich S. A.
Published: May 2010

Porous silicon carbide (SiC) ceramics are produced using carbon matrices derived from natural wood. Such material is especially promising as it is environmentally friendly with attractive physical properties, including a high level of biocompatibility, chemical inertness, and mechanical strength. We have developed a forced impregnation process with further synthesis of SiC using natural wood as well as a variety of industrial carbon materials and compared the properties of these ceramics. The structure and composition of the materials obtained were investigated by Raman scattering spectroscopy. The hardness of the samples was estimated using the Vickers technique. It was shown that the phase composition and mechanical properties of synthesized SiC ceramics can be effectively controlled by the initial Si contents and temperature of the synthesis process. A large variety of options are demonstrated for materials development taking into account an optimal porosity selection for various practical applications.
Universal resistance capacitance crossover in current-voltage characteristics for unshunted array of overdamped Nb–AlOx–Nb Josephson junctions
Authors: Sergeenkov S. , Rivera V. A. G. , Marega E. , Araujo-Moreira F. M.
Published: May 2010

We report on some unusual behavior of the measured current-voltage characteristics (CVC) in artificially prepared two-dimensional unshunted array of overdamped Nb–AlOx–Nb Josephson junctions. The obtained nonlinear CVC are found to exhibit a pronounced (and practically temperature independent) crossover at some current Icr=(1/2βC−1)IC from a resistance R dominated state with VR=RI2−IC2 below Icr to a capacitance C dominated state with VC=ℏ/4eCI−IC above Icr. The origin of the observed behavior is discussed within a single-plaquette approximation assuming the conventional resistively shunted junction model with a finite capacitance and the Ambegaokar–Baratoff relation for the critical current of the single junction.
Accurate acceleration of kinetic Monte Carlo simulations through the modification of rate constants
Authors: Chatterjee Abhijit , Voter Arthur F.
Published: May 2010

We present a novel computational algorithm called the accelerated superbasin kinetic Monte Carlo (AS-KMC) method that enables a more efficient study of rare-event dynamics than the standard KMC method while maintaining control over the error. In AS-KMC, the rate constants for processes that are observed many times are lowered during the course of a simulation. As a result, rare processes are observed more frequently than in KMC and the time progresses faster. We first derive error estimates for AS-KMC when the rate constants are modified. These error estimates are next employed to develop a procedure for lowering process rates with control over the maximum error. Finally, numerical calculations are performed to demonstrate that the AS-KMC method captures the correct dynamics, while providing significant CPU savings over KMC in most cases. We show that the AS-KMC method can be employed with any KMC model, even when no time scale separation is present (although in such cases no computational speed-up is observed), without requiring the knowledge of various time scales present in the system.
Interaction of A-centers with isovalent impurities in silicon
Authors: Chroneos A. , Londos C. A.
Published: May 2010

An A-center is an oxygen interstitial atom near a lattice vacancy and is one of the most common impurity-defect pairs in Czochralski-grown silicon crystals. In the present study, density functional theory calculations have been used to predict the binding energies of A-centers that are at nearest neighbor (NN) and next NN sites to isovalent impurities (carbon, germanium, and tin) in silicon. Interestingly, we predict that the A-center is more bound in isovalent-doped and, in particular, tin-doped silicon. We calculate that most of the binding energy of these A-centers originates from the interaction between the isovalent atoms and the vacancies.
Blocking hillock and whisker growth by intermetallic compound formation in Sn-0.7Cu flip chip solder joints under electromigration
Authors: Liang S. W. , Chen Chih , Han J. K. , Xu Luhua , Tu K. N. , Lai Yi-Shao
Published: May 2010

Mass extrusion occurs in electromigration at the anode in cross-sectioned Sn-0.7Cu flip-chip solder joints. In a pair of joints, the hillock squeezed out at the anode on the board side is more serious than the whisker grown at the anode on the chip side. The difference of mass extrusion has been found to be affected by the amount of intermetallic compound (IMC) formation in the solder bump. It is found that when a large amount of Cu–Sn IMCs form in the grain boundaries of Sn grains, small hillocks are extruded on the anode end. It is proposed that the excessive IMC formation may be able to block the diffusion path of Sn atoms, so the growth of both the Sn whiskers and hillocks are retarded.
Andreev reflection and incoherent spin-polarized transport in ferromagnetic semiconductor/d-wave superconductor/ferromagnetic semiconductor tunnel junctions with {110} interfaces
Authors: Tao Y. C. , Liu H. , Hu J. G.
Published: May 2010

The hole spin accumulation and spin-polarized transport in ferromagnetic semiconductor (FS)/d-wave superconductor (SC)/FS tunnel junctions with {110} interfaces are studied by using four-component Bogoliubov-de Gennes equations, in which the Andreev reflection and four-subband model for the FS are taken into account. It is found that due to the interplay of the d-wave SC and FS, the nonequilibrium hole spin accumulation, differential conductance, and tunneling magnetoresistance exhibit a rich dependence on the Andreev reflection, strengths of potential scattering at the interfaces, mismatches in the effective mass and band between the FS and SC, and types of incident holes, which is much different from that in FS/s-wave SC/FS tunneling junctions. Particularly, it is demonstrated that the differential conductance can be negative in both ferromagnetic and antiferromagnetic alignments for not only incident heavy holes but also incident light holes, and the variations in both the energy gap with temperature and hole spin accumulation with bias voltage can display a twofold behavior due to the Andreev reflection.
Dynamic Monte Carlo versus Brownian dynamics: A comparison for self-diffusion and crystallization in colloidal fluids
Authors: Sanz E. , Marenduzzo D.
Published: May 2010

Here we present a comparative study of dynamic Monte Carlo and Brownian dynamics simulations of colloidal systems with repulsive interactions. We show that if the Monte Carlo time is rescaled with the acceptance probability, the estimates of the self-diffusion coefficient and of the crystallization times are, respectively, in good and fair agreement with the Brownian dynamics simulations. We also analyze the case of a particle in a one-dimensional potential, where we show that the convergence of a Monte Carlo procedure to the Brownian dynamics result is faster when time is rescaled by the acceptance probability, which gives a theoretical basis for this practical recipe.
Tunable middle infrared radiation generation in a GaSe crystal
Authors: Lu Y. Z. , Wang X. B. , Zhu X. W. , Zhang X. L. , Zuo D. L. , Cheng Z. H.
Published: May 2010

Tunable second harmonic generation of pulsed CO2 laser radiation in a GaSe crystal was demonstrated. The nonlinear optical properties of GaSe and phase-matching conditions were investigated, and the best fitted dispersion relationships for this crystal were also determined. External conversion efficiency of 0.1% with unfocused pumped radiation had been achieved and maximum single pulse energy of 0.19 mJ was generated at 5.3 μm.
Thermal saturation in dielectric four-terminal nanostructures
Authors: Yang Ping , Zhong Wei-Rong , He Yafeng , Hu Bambi
Published: May 2010

We propose a theoretical model to investigate the nonlinear thermal properties in dielectric four-terminal nanostructures at low temperatures. In this model, the gate temperature effect on the thermal flow from source to drain is built based on mesoscopic ballistic-phonon transport. Thermal flow versus temperature difference between source and drain is calculated for the fixed gate temperature. Saturation of thermal flow is showed with increasing the temperature difference. A reasonable explanation for the phenomenon is given by the nonlinear variation in temperature dependence of propagating phonon modes in source and drain terminals. The research results suggest the possibility of the nanothermal transistor fabrication.
Spin polarization decay in magnetic tunnel junctions with semimetal-inserted layers
Authors: Lee Kyoung-Il , Roh Jong Wook , Lee Kiyoung , Chang Joonyeon , Shin Kyung-Ho , Johnson Mark , Lee Wooyoung
Published: May 2010

Magnetic tunnel junctions (MTJs) were fabricated with a thin layer of semimetallic bismuth inserted between the tunnel barrier and the top ferromagnetic electrode. The tunneling magnetoresistance (TMR) was measured on a set of samples for which the thickness of the inserted layer varied from 0 to 20 nm. The TMR decreased with an exponential decay length that was found to be ΛBi=4.1 nm=0.48 λF,Bi, where λF,Bi is the Fermi wavelength measured in comparable Bi films. This result is in remarkably good agreement with the decay length previously measured in MTJs with inserted copper layers, λCu=0.58 λF,Cu, even though the values of λF differ by an order of magnitude. It thereby gives a confirmation that the characteristic length scale of the tunneling density of states is the Fermi wavelength. Measurements of TMR as a function of bias voltage show a large asymmetry and the peak TMR is shifted to a nonzero value.
An abnormal dielectric relaxation phenomenon observed in PbZr0.38Ti0.62O3 multilayers
Authors: Hu G. J. , Zhang T. , Bu H. J. , Sun J. L. , Chu J. H. , Dai N. , Zhu D. M. , Wu Y. Zh.
Published: May 2010

We report an unusual dielectric relaxation phenomenon associated with dipolar defect complexes Ti3+-(Vo2−)•• observed in the PbZr0.38Ti0.62O3 multilayers. The dielectric loss aroused by the polarization of defect dipoles varies with time under ac electric fields, and its change can be controlled by an applied dc bias. This abnormally dynamic behavior of dielectric loss can be interpreted by the formation and dissociation of dipolar defect pairs Ti3+-(Vo2−)•• by injection of charged carriers. These investigations may be beneficial to getting further insight into the defect dynamics and the mechanism of ferroelectric polarization fatigue and restoration in ferroelectric materials.
Dark Schrödinger solitons and harmonic generation in left-handed nonlinear transmission line
Authors: Wang Zhengbin , Feng Yijun , Zhu Bo , Zhao Junming , Jiang Tian
Published: May 2010

In this paper, we analyze the wave propagation in a practical left-handed nonlinear transmission line with series nonlinear capacitance composed of two back-to-back connected varactor diodes. Detailed circuit analysis of the transmission line shows that by properly choosing the circuit parameters, the equation governing the wave envelope evolution can be reduced to a one-dimensional nonlinear Schrödinger equation, which supports dark solitons propagation. By transient circuit simulation, the soliton evolution has been demonstrated both in time and frequency domain with input signal of either a continuous wave or a Gaussian modulated pulse. It is also shown that increasing the dissipation in the transmission line metamaterials is helpful to form steady dark solitons in short transmission lines. The establishing of the Schrödinger solitons also results in the third harmonic generation in the transmission line, which may find practical applications in communication systems.
On relation between the free-energy perturbation and Bennett’s acceptance ratio methods: Tracing the influence of the energy gap
Authors: Luzhkov V. B.
Published: May 2010

The “double-end” free-energy perturbation (DEFEP) expression, as the Taylor expansions show, presents an asymptotic solution for Bennett’s acceptance ratio (BAR) method at large energy gaps. Iterative self-consistent calculations for solving the BAR equation oscillate between two energy values in such a case, and only using the DEFEP result as a first-guess yields formal convergence of the self-consistence procedure. The DEFEP estimate also provides a good starting point for the iterative procedure of BAR for the whole range of state overlap. Microscopic force field molecular dynamics simulations of the hydration free energies for transformation O+→O− support these data. The simulations also prove robustness of the multistage perturbation schemes as compared with single-stage calculations. The observed difference between the BAR and DEFEP results has a maximum at intermediate values of energy gaps and is getting smaller for energy gaps less than 10–15 kT.
notRoles of lattice distortion in (1−x)(Bi0.5Na0.5)TiO3-xBaTiO3 ceramics
Authors: Sung Y. S. , Kim J. M. , Cho J. H. , Song T. K. , Kim M. H. , Park T. G.
Published: May 2010

Structure property relations in (1−x)(Bi0.5Na0.5)TiO3-xBaTiO3 ceramics were investigated at x=0–10 mol %. A solid solution with either rhombohedral or tetragonal symmetry was confirmed with a morphotropic phase boundary (MPB) at x=5–7 mol %. Grains became small with increasing x possibly due to grain boundary pinning by BaBi′–BaNa•. Lattice distortion was a key factor affecting piezoelectric coefficient (d33) and depolarization temperature (Td). Both rhombohedral 90−α and tetragonal cT/aT lattice distortion became smaller toward the MPB causing poling by field and depoling by temperature to become easier subsequently resulting in higher d33 but lower Td, and vice versa.
Positive surface and perpendicular magnetic anisotropy in natural nanomorphous Ni/NiO multilayers
Authors: Poulopoulos P. , Kapaklis V. , Jönsson P. E. , Papaioannou E. Th. , Delimitis A. , Pappas S. D. , Trachylis D. , Politis C.
Published: May 2010

Ni/NiO multilayers with excellent sequencing are grown via radiofrequency magnetron sputtering with the use of one Ni target and natural oxidation. Ni layers consist of very small Ni nanocrystals interrupted by amorphous NiO layers. When Ni is deposited at 0.3 Pa Ar-pressure, the hard-magnetization axis is the film normal and saturation field decreases by decreasing Ni layer thickness. Considerable positive surface anisotropy is found, which is remarkable for Ni-based multilayers. If Ni is deposited at 3 Pa Ar-pressure, perpendicular magnetic anisotropy is observed at low temperatures even for 5.4 nm thick Ni layers. This anisotropy results in the formation of stripe magnetic domains.
Photonic crystal nanobeam cavity strongly coupled to the feeding waveguide
Authors: Quan Qimin , Deotare Parag B. , Loncar Marko
Published: May 2010

A deterministic design of an ultrahigh Q-factor, wavelength-scale photonic crystal nanobeam cavity is proposed and experimentally demonstrated. Using this approach, cavities with Q>106 and on-resonance transmission T>90% are designed. The devices, fabricated in silicon and capped with a low refractive index polymer, have experimental Q=80 000 and T=73%. This is, to the best of our knowledge, the highest transmission measured in deterministically designed, wavelength-scale high-Q cavities.
Origin of dynamical heterogeneities in calcium aluminosilicate liquids
Authors: Vargheese K. Deenamma , Tandia Adama , Mauro John C.
Published: May 2010

We investigate the heterogeneous dynamics of calcium aluminosilicate liquids across both the peraluminous and peralkaline regimes. Using the isoconfigurational ensemble method we find a clear correlation between dynamical heterogeneities and concentration fluctuations. Regions of high dynamic propensity have higher concentrations of both calcium and aluminum, whereas low propensity regions are silica rich. The isoconfigurational ensemble is found to be a powerful tool for studying the origin of heterogeneous dynamics of industrially relevant glass-forming liquids.
Theory of capture rate in polymer translocation
Authors: Muthukumar M.
Published: May 2010

The translocation of macromolecules through a nanopore requires the impingement of the molecules at the pore followed by threading through the pore. While most of the discussion on the translocation phenomenon focused so far on the threading process, the phenomenology on the frequency of encounters between the polymer and the pore exhibits diverse features in terms of polymer length, solution conditions, driving force, and pore geometry. We derive a general theory for the capture rate of polyelectrolyte molecules and the probability of successful translocation through a nanopore, under an externally imposed electric field. By considering the roles of entropic barrier at the pore entrance and drift of the polyelectrolyte under the electric field, we delineate two regimes: (a) entropic barrier regime and (b) drift regime. In the first regime dominated by the entropic barrier for the polyelectrolyte, the capture rate is an increasing nonlinear function in the electric field and chain length. In the drift regime, where the electric field dwarfs the role of entropic barriers, the capture rate is independent of chain length and linear in electric field. An analytical formula is derived for the crossover behavior between these regimes, and the general results are consistent with various experimentally observed trends.
Assessment of the accuracy of long-range corrected functionals for describing the electronic and optical properties of silver clusters
Authors: Silverstein Daniel W. , Jensen Lasse
Published: May 2010

The absorption spectra and ionization potentials of silver clusters Agn (n=4–20) are examined in the framework of density-functional theory (DFT) using several different methods of representing the exchange-correlation functional. Three different types of exchange-correlation functionals are used: those including gradient corrections to the density in the generalized gradient approximation, global hybrid functionals mixing in a portion of the Hartree–Fock exchange, and long-range-corrected (LC-) functionals. Comparison of ionization potentials calculated using DFT with those derived from experiments demonstrates that LC-functionals more accurately represent the electronic structure of the silver clusters studied. Absorption spectra are compared with both experimental spectra and those derived using higher level theoretical calculations showing that the LC-functionals appear to correctly describe the optical transitions in the gas phase, particularly when a small redshift in the experimental spectrum is accounted for due to matrix effects. It is also demonstrated that the LC-hybrid functionals significantly reduce the occurrence of spurious states in the optical absorbance spectrum while maintaining the intensity of plasmon like features of the spectra for larger silver clusters.
Improved electroluminescence from n-ZnO/AlN/p-GaN heterojunction light-emitting diodes
Authors: You J. B. , Zhang X. W. , Zhang S. G. , Wang J. X. , Yin Z. G. , Tan H. R. , Zhang W. J. , Chu P. K. , Cui B. , Wowchak A. M. , Dabiran A. M. , Chow P. P.
Published: May 2010

n-ZnO/p-GaN heterojunction light-emitting diodes with and without a sandwiched AlN layer were fabricated. The electroluminescence (EL) spectrum acquired from the n-ZnO/p-GaN displays broad emission at 650 nm originating from ZnO and weak emission at 440 nm from GaN, whereas the n-ZnO/AlN/p-GaN exhibits strong violet emission at 405 nm from ZnO without GaN emission. The EL intensity is greatly enhanced by inserting a thin AlN intermediate layer and it can be attributed to the suppressed formation of the GaOx interfacial layer and confinement effect rendered by the AlN potential barrier layer.
Self-consistent field theory of polymer-ionic molecule complexation
Authors: Nakamura Issei , Shi An-Chang
Published: May 2010

A self-consistent field theory is developed for polymers that are capable of binding small ionic molecules (adsorbates). The polymer-ionic molecule association is described by Ising-like binding variables, Ci(a)(kΔ)(=0 or 1), whose average determines the number of adsorbed molecules, nBI. Polymer gelation can occur through polymer-ionic molecule complexation in our model. For polymer-polymer cross-links through the ionic molecules, three types of solutions for nBI are obtained, depending on the equilibrium constant of single-ion binding. Spinodal lines calculated from the mean-field free energy exhibit closed-loop regions where the homogeneous phase becomes unstable. This phase instability is driven by the excluded-volume interaction due to the single occupancy of ion-binding sites on the polymers. Moreover, sol-gel transitions are examined using a critical degree of conversion. A gel phase is induced when the concentration of adsorbates is increased. At a higher concentration of the adsorbates, however, a re-entrance from a gel phase into a sol phase arises from the correlation between unoccupied and occupied ion-binding sites. The theory is applied to a model system, poly(vinyl alcohol) and borate ion in aqueous solution with sodium chloride. Good agreement between theory and experiment is obtained.
Reversible plasma switching in epitaxial BiFeO3 thin films
Authors: Kim Yunseok , Vrejoiu Ionela , Hesse Dietrich , Alexe Marin
Published: May 2010

Reversible plasma switching in epitaxial multiferroic BiFeO3 thin films was directly observed and analyzed using piezoresponse force microscopy. The polarization could be reversibly switched using oxygen plasma and a subsequent thermal annealing treatment in vacuum, respectively. The domain wall velocity during plasma switching, estimated to about 10−8 m/s, is much slower compared to the normal electrical switching, however a large area of square centimeter scale could be stably switched. The results demonstrate that reversible plasma switching can be achieved by oxygen plasma treatment and it can be a useful tool for an electrode-less control of ferroelectric switching on large area.
Collective Purchase: Moving Local and Organic Foods beyond the Niche Market
Authors: Little Ruth , Maye Damian , Ilbery Brian
Published: May 2010

The authors draw attention to the creative possibilities offered by collective purchase as a mechanism to move local and organic foods beyond the niche market. The food-buying group and cooperative style of food purchasing has received only scant reference in the alternative food and ethical consumption literatures, but it offers much in terms of historical context and future lessons for growth in the sector. ‘We can do it better’ is an experimental ethic of the 1960s and 1970s counterculture, but it resonates strongly with the present-day ‘alternatives’ associated with the local and organic food movement. The authors use Gibson-Graham's notion of ‘diverse economies’ to examine selected buying groups and food cooperatives in North America, Europe, and Japan. The results reveal a highly pixilated and evolving mix of motivations and ethics. The ‘ideology first, practicalities later’ approach appears to be a powerful influence, symbolising the ‘becomingness’ of ethical purchasing in these contexts.
Evaluating the Outcomes of Plans: Theory, Practice, and Methodology
Authors: Laurian Lucie , Crawford Jan , Day Maxine , Kouwenhoven Peter , Mason Greg , Ericksen Neil , Beattie Lee
Published: May 2010

Despite calls for performance-oriented and evidence-based planning, the outcomes of land use and environmental plans are rarely monitored or assessed ex post facto (that is, post implementation). As a result, planners cannot know whether or why plans achieve their goals, or learn from the results of past interventions to improve planning practice. This evaluation gap is caused by a lack of methodology to evaluate the outcomes of plans and the difficulty of attributing changes to planning activities. We address this gap by proposing and testing a plan-outcome evaluation (POE) methodology. We demonstrate its broad applicability and usefulness in the context of local plans in New Zealand. The POE methodology will be useful to practitioners and academics seeking to assess the outcomes of plans in countries with western planning traditions.
Urban and Regional Dynamics from the Global to the Local: Hierarchies, ‘DNA’, and ‘Genetic’ Planning
Authors: Wilson Alan
Published: May 2010

When the known properties of the dynamics of nonlinear systems are reviewed in the context of urban and regional modelling, it is argued that this provides an important new perspective for planners—analogous to the role of DNA in biology. As a preliminary, it is shown that effective modelling of urban and regional dynamics, particularly with a view to policy and planning applications, demands the articulation of a hierarchy of models. It is then possible to identify the structural ‘DNA’ for various layers which determine the dynamics and possible paths of development. This in turn allows the development of a ‘genetic planning’ concept by analogy with ‘genetic medicine’.
Dynamic Phenomenology of Grapheme-Color Synesthesia
Authors: Bridgeman Bruce , Winter Dorina , Tseng Philip
Published: May 2010

In grapheme-color synesthesia, observers perceive colors that are associated with letters and numbers. We tested the dynamic limits of this phenomenon by exposing two synesthetes to characters that rotate smoothly, that morph into other characters, that disappear abruptly, or that have colors either consistent or inconsistent with the corresponding synesthetic color. Rotating letters changed their synesthetic colors abruptly as letter identification changed or failed. Morphing letters also changed color together with a change in letter identification. Abrupt disappearance of a black character on a white background yielded a negative afterimage, but maintenance of the same synesthetic color. Our synesthetes could maintain both physical and synesthetic color in the same character, without conflict. Neon color spreading in one observer occurred for physical but not synesthetic color. These and other results show close linking of synesthetic color with character identity rather than image properties, in contrast to physical color.
Diversification of the greater hydrophilines clade of giant water scavenger beetles dated back to the Middle Eocene (Coleoptera:Hydrophilidae:Hydrophilina)
Authors: Fikáček Martin , Wedmann Sonja , Schmied Heiko
Published: May 2010

Fossil representatives of the hydrophilid genera Hydrochara Berthold, 1827, Hydrobiomorpha Blackburn, 1888 and Hydrophilus Geoffroy, 1762 were recorded at the lower Middle Eocene locality Grube Messel in Germany. Four morphospecies were recognised, including Hydrobiomorpha eopalpalis, sp. nov. showing sexually dimorphic maxillary palpomere 2 unknown in any recent or fossil species of the genus. These fossils are the oldest known records of the mentioned genera and indicate a minimum age of 47 million years for the divergence of the Hydrobiomorpha and Hydrophilus clades. Based on these data, we assume that the diversification of the ‘greater hydrophilines’ clade predated the lower Middle Eocene. The fossil record of the subtribe Hydrophilina is briefly reviewed, the reasons of the scarcity or absence of some genera in the fossil record are discussed, and the paleoenviromental significance of the presented fossils is discussed.
Kinetochores hang on for the ride
Authors: Short Ben
Published: May 2010

Two studies reveal how kinetochores stay attached to dynamic microtubules.
Vertebrate cells genetically deficient for Cdc14A or Cdc14B retain DNA damage checkpoint proficiency but are impaired in DNA repair
Authors: Mocciaro Annamaria , Berdougo Eli , Zeng Kang , Black Elizabeth , Vagnarelli Paola , Earnshaw William , Gillespie David , Jallepalli Prasad , Schiebel Elmar
Published: May 2010

A recent study suggested that human Cdc14B phosphatase has a central function in the G2 DNA damage checkpoint. In this study, we show that chicken DT40, human HCT116, and human telomerase reverse transcription–immortalized retinal pigment epithelial cells deleted for the Cdc14A or Cdc14B gene are DNA damage checkpoint proficient and arrest efficiently in G2 in response to irradiation. Cdc14A knockout (KO) or Cdc14B-KO cells also maintain normal levels of Chk1 and Chk2 activation after irradiation. Surprisingly, however, irradiation-induced γ-H2A.X foci and DNA double-strand breaks persist longer in Cdc14A-KO or Cdc14B-KO cells than controls, suggesting that Cdc14 phosphatases are required for efficient DNA repair.
Quantitative proteomics combined with BAC TransgeneOmics reveals in vivo protein interactions
Authors: Hubner Nina C. , Bird Alexander W. , Cox Jürgen , Splettstoesser Bianca , Bandilla Peter , Poser Ina , Hyman Anthony , Mann Matthias
Published: May 2010

Protein interactions are involved in all cellular processes. Their efficient and reliable characterization is therefore essential for understanding biological mechanisms. In this study, we show that combining bacterial artificial chromosome (BAC) TransgeneOmics with quantitative interaction proteomics, which we call quantitative BAC–green fluorescent protein interactomics (QUBIC), allows specific and highly sensitive detection of interactions using rapid, generic, and quantitative procedures with minimal material. We applied this approach to identify known and novel components of well-studied complexes such as the anaphase-promoting complex. Furthermore, we demonstrate second generation interaction proteomics by incorporating directed mutational transgene modification and drug perturbation into QUBIC. These methods identified domain/isoform-specific interactors of pericentrin- and phosphorylation-specific interactors of TACC3, which are necessary for its recruitment to mitotic spindles. The scalability, simplicity, cost effectiveness, and sensitivity of this method provide a basis for its general use in small-scale experiments and in mapping the human protein interactome.
The Dam1 complex confers microtubule plus end–tracking activity to the Ndc80 kinetochore complex
Authors: Lampert Fabienne , Hornung Peter , Westermann Stefan
Published: May 2010

Kinetochores must remain associated with microtubule ends, as they undergo rapid transitions between growth and shrinkage. The molecular basis for this essential activity that ensures correct chromosome segregation is unclear. In this study, we have used reconstitution of dynamic microtubules and total internal reflection fluorescence microscopy to define the functional relationship between two important budding yeast kinetochore complexes. We find that the Dam1 complex is an autonomous plus end–tracking complex. The Ndc80 complex, despite being structurally related to the general tip tracker EB1, fails to recognize growing ends efficiently. Dam1 oligomers are necessary and sufficient to recruit Ndc80 to dynamic microtubule ends, where both complexes remain continuously associated. The interaction occurs specifically in the presence of microtubules and is subject to regulation by Ipl1 phosphorylation. These findings can explain how the force harvested by Dam1 is transmitted to the rest of the kinetochore via the Ndc80 complex.
Predictive Ability of Positive Clinical Culture Results and International Classification of Diseases, Ninth Revision, to Identify and Classify Noninvasive Staphylococcus aureus Infections: A Validation Study
Authors: Tracy LaRee A. , Furuno Jon P. , Harris Anthony D. , Singer Mary , Langenberg Patricia , Roghmann Mary-Claire
Published: May 2010

Objective.

To develop and validate an algorithm to identify and classify noninvasive infections due to Staphylococcus aureus by using positive clinical culture results and administrative data.

Design.

Retrospective cohort study.

Setting.

Veterans Affairs Maryland Health Care System.

Methods.

Data were collected retrospectively on all S. aureus clinical culture results from samples obtained from nonsterile body sites during October 1998 through September 2008 and associated administrative claims records. An algorithm was developed to identify noninvasive infections on the basis of a unique S. aureus-positive culture result from a nonsterile site sample with a matching International Classification of Diseases, Ninth Revision (ICD-9-CM), code for infection at time of sampling. Medical records of a subset of cases were reviewed to find the proportion of true noninvasive infections (cases that met the Centers for Disease Control and Prevention National Healthcare Safety Network [NHSN] definition of infection). Positive predictive value (PPV) and negative predictive value (NPV) were calculated for all infections and according to body site of infection.

Results.

We identified 4,621 unique S. aureus-positive culture results, of which 2,816 (60.9%) results met our algorithm definition of noninvasive S. aureus infection and 1,805 (39.1%) results lacked a matching ICD-9-CM code. Among 96 cases that met our algorithm criteria for noninvasive S. aureus infection, 76 also met the NHSN criteria (PPV, 79.2% [95% confidence interval, 70.0%–86.1%]). Among 98 cases that failed to meet the algorithm criteria, 80 did not meet the NHSN criteria (NPV, 81.6% [95% confidence interval, 72.8%–88.0%]). The PPV of all culture results was 55.4%. The algorithm was most predictive for skin and soft-tissue infections and bone and joint infections.

Conclusion.

When culture-based surveillance methods are used, the addition of administrative ICD-9-CM codes for infection can increase the PPV of true noninvasive S. aureus infection over the use of positive culture results alone.
GPs in the Workplace: Does Gender Matter?
Authors: Shiner Alice , Simon Chantal , Howe Amanda
Published: May 2010

The differing status of men and women in a society affects their experience both as patients and as providers of health care. This article examines the influence gender issues have upon the role of doctors and the running of health care services in an increasingly feminized workforce. It aims to raise awareness of the medicolegal aspects involved, including opportunities for GPs to improve gender equity in the workplace.
Disability and Discrimination
Authors: Harris Emma , Simon Chantal
Published: May 2010

Despite often having complex and challenging health problems, people with a disability may have difficulty accessing services to meet their health care and other everyday needs. These problems can be further confounded by negative public attitude and potential discrimination.
Health Inequalities
Authors: Hutt Patrick
Published: May 2010

Health inequalities are increasingly discussed within health professional education, provision and policy. This article provides an overview of how GP trainees might think about health inequalities and, perhaps more importantly, what they might do to address them.
Methods for Determining Relative Average Number of Channels per Maize Starch Granule and Digestion of Raw Granules of Mutant Maize Cultivars by Amyloglucosidase
Authors: Widya Yenny , Gunawan Ninik , BeMiller James N.
Published: May 2010

Six methods were investigated for determining the relative average numbers of channels per granule in populations of starch granules. The first method involved digestion of raw starch granules with amyloglucosidase. There were differences in the rates of digestion of starch of the same mutation in two different inbred‐line backgrounds, but we concluded that a better method was needed. Three methods involved measuring either all channel proteins or one specific protein. Extraction of granules using 70% 2‐propanol containing 1% 2‐mercaptoethanol (ME) was successful in removing the majority of external surface proteins (<31 kDa). Further extraction of starch granules using 0.1% SDS containing 0.2% ME, pH 8, removed channel proteins without extracting matrix proteins. By measuring SDS‐PAGE band intensities of protein clusters at 31–97.4 kDa or a marker protein at ≈42 kDa, methods to quantify relative average degrees of channelization (RADC) in different maize backgrounds were developed. Using either method, Oh43 had the highest RADC and B73 had the lowest RADC among the inbred lines examined. Another method involves extraction of total proteins using 2% SDS containing 0.2% ME from granules with the majority of surface proteins removed. The extract is subjected to SDS‐PAGE and Western blotting, followed by location and quantification of the actin band using antibodies to maize pollen actin. These four methods give somewhat different results for six inbred lines of corn with a relatively narrow range of RADC. In an attempt to relate them to the actual number of observed pores (channel openings to the surface), granules were treated with α‐amylase to enlarge the pores, with and without prior treatment with a protease. We concluded that this treatment revealed something about the nature of the granules and the action of α‐amylase on them, but it was not an indication of the number of channels present. The outcome of this research provides evidence that the number of channels in corn starch granules varies with the genetic makeup of the parent plant. We concluded that measuring granule actin is the preferred method.
Adaptation of tobacco etch potyvirus to a susceptible ecotype ofArabidopsis thalianacapacitates it for systemic infection of resistant ecotypes
Authors: Lalić Jasna , Agudelo-Romero Patricia , Carrasco Purificación , Elena Santiago F.
Published: May 2010

Viral pathogens continue to emerge among humans, domesticated animals and cultivated crops. The existence of genetic variance for resistance in the host population is crucial to the spread of an emerging virus. Models predict that rapid spread decreases with the frequency and diversity of resistance alleles in the host population. However, empirical tests of this hypothesis are scarce.Arabiodpsis thaliana—tobacco etch potyvirus (TEV) provides an experimentally suitable pathosystem to explore the interplay between genetic variation in host's susceptibility and virus diversity. Systemic infection ofA. thalianawith TEV is controlled by three dominant loci, with different ecotypes varying in susceptibility depending on the genetic constitution at these three loci. Here, we show that the TEV adaptation to a susceptible ecotype allowed the virus to successfully infect, replicate and induce symptoms in ecotypes that were fully resistant to the ancestral virus. The value of these results is twofold. First, we showed that the existence of partially susceptible individuals allows for the emerging virus to bypass resistance alleles that the virus has never encountered. Second, the concept of resistance genes may only be valid for a well-defined viral genotype but not for polymorphic viral populations.
Lifestyles of plant viruses
Authors: Roossinck Marilyn J.
Published: May 2010

The vast majority of well-characterized eukaryotic viruses are those that cause acute or chronic infections in humans and domestic plants and animals. However, asymptomatic persistent viruses have been described in animals, and are thought to be sources for emerging acute viruses. Although not previously described in these terms, there are also many viruses of plants that maintain a persistent lifestyle. They have been largely ignored because they do not generally cause disease. The persistent viruses in plants belong to the family
Partitiviridae
or the genus
Endornavirus
. These groups also have members that infect fungi. Phylogenetic analysis of the partitivirus RNA-dependent RNA polymerase genes suggests that these viruses have been transmitted between plants and fungi. Additional families of viruses traditionally thought to be fungal viruses are also found frequently in plants, and may represent a similar scenario of persistent lifestyles, and some acute or chronic viruses of crop plants may maintain a persistent lifestyle in wild plants. Persistent, chronic and acute lifestyles of plant viruses are contrasted from both a functional and evolutionary perspective, and the potential role of these lifestyles in host evolution is discussed.
Lethal mutagenesis and evolutionary epidemiology
Authors: Martin Guillaume , Gandon Sylvain
Published: May 2010

The lethal mutagenesis hypothesis states that within-host populations of pathogens can be driven to extinction when the load of deleterious mutations is artificially increased with a mutagen, and becomes too high for the population to be maintained. Although chemical mutagens have been shown to lead to important reductions in viral titres for a wide variety of RNA viruses, the theoretical underpinnings of this process are still not clearly established. A few recent models sought to describe lethal mutagenesis but they often relied on restrictive assumptions. We extend this earlier work in two novel directions. First, we derive the dynamics of the genetic load in a multivariate Gaussian fitness landscape akin to classical quantitative genetics models. This fitness landscape yields a continuous distribution of mutation effects on fitness, ranging from deleterious to beneficial (i.e. compensatory) mutations. We also include an additional class of lethal mutations. Second, we couple this evolutionary model with an epidemiological model accounting for the within-host dynamics of the pathogen. We derive the epidemiological and evolutionary equilibrium of the system. At this equilibrium, the density of the pathogen is expected to decrease linearly with the genomic mutation rateU. We also provide a simple expression for the critical mutation rate leading to extinction. Stochastic simulations show that these predictions are accurate for a broad range of parameter values. As they depend on a small set of measurable epidemiological and evolutionary parameters, we used available information on several viruses to make quantitative and testable predictions on critical mutation rates. In the light of this model, we discuss the feasibility of lethal mutagenesis as an efficient therapeutic strategy.