bluuebunny/crossref_metadata_2025 huggingface dataset:
A first principles study of thiol-capped Au nanoparticles: Structural, electronic, and magnetic properties as a function of thiol coverage
Authors: Cuadrado R. , Puerta J. M. , Soria F. , Cerdá J. I.
Published: July 2013

We have studied the stability of thiolated Au38 nanoparticles (NPs) via density functional theory based calculations varying the coverage from 0 up to 32 molecules. Three different initial core arrangements were considered for the cluster, spherical, tubular, and bi-icosahedral, while thiol groups were attached to the cluster via the sulfur atom either as single molecules or forming more complex staple motifs. After molecular dynamics runs several metastable configurations are found at each coverage thus allowing to analyze the properties of the NPs in the form of ensemble averages. In particular, we address the structural and electronic properties as a function of the number of thiols. The study emphasizes the strong influence of the core structure on the stability of the NPs, and its interplay with the thiol coverage and adsorption geometries. The magnetic properties of the NPs have also been explored via spin-polarized calculations including spin-orbit coupling. No evidence for the existence of a robust intrinsic ferromagnetism is found in any of the structures.
Directional fidelity of nanoscale motors and particles is limited by the 2nd law of thermodynamics—Via a universal equality
Authors: Wang Zhisong , Hou Ruizheng , Efremov Artem
Published: July 2013

Directional motion of nanoscale motors and driven particles in an isothermal environment costs a finite amount of energy despite zero work as decreed by the 2nd law, but quantifying this general limit remains difficult. Here we derive a universal equality linking directional fidelity of an arbitrary nanoscale object to the least possible energy driving it. The fidelity-energy equality depends on the environmental temperature alone; any lower energy would violate the 2nd law in a thought experiment. Real experimental proof for the equality comes from force-induced motion of biological nanomotors by three independent groups – for translational as well as rotational motion. Interestingly, the natural self-propelled motion of a biological nanomotor (F1-ATPase) known to have nearly 100% energy efficiency evidently pays the 2nd law decreed least energy cost for direction production.
Mapping temperatures and temperature gradients during flash heating in a diamond-anvil cell
Authors: Du Zhixue , Amulele George , Robin Benedetti Laura , Lee Kanani K. M.
Published: July 2013

Here, we couple two-dimensional, 4-color multi-wavelength imaging radiometry with laser flash heating to determine temperature profiles and melting temperatures under high pressures in a diamond-anvil cell. This technique combines the attributes of flash heating (e.g., minimal chemical reactions, thermal runaway, and sample instability), with those of multi-wavelength imaging radiometry (e.g., 2D temperature mapping and reduction of chromatic aberrations). Using this new technique in conjunction with electron microscopy makes a powerful tool to determine melting temperatures at high pressures generated by a diamond-anvil cell.
Modeling the purging of dense fluid from a street canyon driven by an interfacial mixing flow and skimming flow
Authors: Baratian-Ghorghi Z. , Kaye N. B.
Published: July 2013

An experimental study is presented to investigate the mechanism of flushing a trapped dense contaminant from a canyon by turbulent boundary layer flow. The results of a series of steady-state experiments are used to parameterize the flushing mechanisms. The steady-state experimental results for a canyon with aspect ratio one indicate that dense fluid is removed from the canyon by two different processes, skimming of dense fluid from the top of the dense layer; and by an interfacial mixing flow that mixes fresh fluid down into the dense lower layer (entrainment) while mixing dense fluid into the flow above the canyon (detrainment). A model is developed for the time varying buoyancy profile within the canyon as a function of the Richardson number which parameterizes both the interfacial mixing and skimming processes observed. The continuous release steady-state experiments allowed for the direct measurement of the skimming and interfacial mixing flow rates for any layer depth and Richardson number. Both the skimming rate and the interfacial mixing rate were found to be power-law functions of the Richardson number of the layer. The model results were compared to the results of previously published finite release experiments [Z. Baratian-Ghorghi and N. B. Kaye, Atmos. Environ. 60, 392–402 (2012)]10.1016/j.atmosenv.2012.06.077. A high degree of consistency was found between the finite release data and the continuous release data. This agreement acts as an excellent check on the measurement techniques used, as the finite release data was based on curve fitting through buoyancy versus time data, while the continuous release data was calculated directly by measuring the rate of addition of volume and buoyancy once a steady-state was established. Finally, a system of ordinary differential equations is presented to model the removal of dense fluid from the canyon based on empirical correlations of the skimming and interfacial mixing taken form the steady-state experiments. The ODE model predicts well the time taken for a finite volume of dense fluid to be flushed from a canyon.
Catalytic micromotor generating self-propelled regular motion through random fluctuation
Authors: Yamamoto Daigo , Mukai Atsushi , Okita Naoaki , Yoshikawa Kenichi , Shioi Akihisa
Published: July 2013

Most of the current studies on nano/microscale motors to generate regular motion have adapted the strategy to fabricate a composite with different materials. In this paper, we report that a simple object solely made of platinum generates regular motion driven by a catalytic chemical reaction with hydrogen peroxide. Depending on the morphological symmetry of the catalytic particles, a rich variety of random and regular motions are observed. The experimental trend is well reproduced by a simple theoretical model by taking into account of the anisotropic viscous effect on the self-propelled active Brownian fluctuation.
In-plane magnetoresistance in a topological insulator ferromagnet/barrier/ferromagnet/superconductor junction
Authors: Vali R. , Vali Mehran
Published: July 2013

Dirac Bogoliubov-de Gennes equation and Blonder-Tinkham-Klapwijk formalism are applied to study the conductance and magnetoresistance of a topological insulator ferromagnet/barrier/ferromagnet/superconductor (F1/B/F2/SC) junction with the in-plane magnetization. We find that the induced in-plane magnetization sets a lower critical incident angle for Andreev reflection and causes a very large magnetoresistance. We find also that both the conductance and magnetoresistance are oscillating functions of the gate voltage exerted on the middle ferromagnetic layer and the thickness of this layer.
Strong dependence of the tetragonal Mn2.1Ga thin film crystallization temperature window on seed layer
Authors: Li Mingyang , Jiang Xin , Samant Mahesh G. , Felser Claudia , Parkin Stuart S. P.
Published: July 2013

For spintronic applications, such as magnetic memory and logic, magnetic thin films with high perpendicular magnetic anisotropy and spin polarization are needed. An attractive candidate material is the Heusler compound Mn3-xGa (x varying from 0 to 2). We show that there is a correlation between the degree of crystallization of thin films of Mn3-xGa (x ∼ 0.9) and the magnitude of the perpendicular magnetic anisotropy. Moreover, we find that the crystallization temperature window varies with the seed layer on which the Mn3-xGa films are deposited. Seed layers of Pt, Cr, Ru, Mo and SrTiO3 were considered and the largest crystallization window was found for Pt(100) layers.
The isotropic-nematic phase transition of tangent hard-sphere chain fluids—Pure components
Authors: van Westen Thijs , Oyarzún Bernardo , Vlugt Thijs J. H. , Gross Joachim
Published: July 2013

An extension of Onsager's second virial theory is developed to describe the isotropic-nematic phase transition of tangent hard-sphere chain fluids. Flexibility is introduced by the rod-coil model. The effect of chain-flexibility on the second virial coefficient is described using an accurate, analytical approximation for the orientation-dependent pair-excluded volume. The use of this approximation allows for an analytical treatment of intramolecular flexibility by using a single pure-component parameter. Two approaches to approximate the effect of the higher virial coefficients are considered, i.e., the Vega-Lago rescaling and Scaled Particle Theory (SPT). The Onsager trial function is employed to describe the orientational distribution function. Theoretical predictions for the equation of state and orientational order parameter are tested against the results from Monte Carlo (MC) simulations. For linear chains of length 9 and longer, theoretical results are in excellent agreement with MC data. For smaller chain lengths, small errors introduced by the approximation of the higher virial coefficients become apparent, leading to a small under- and overestimation of the pressure and density difference at the phase transition, respectively. For rod-coil fluids of reasonable rigidity, a quantitative comparison between theory and MC simulations is obtained. For more flexible chains, however, both the Vega-Lago rescaling and SPT lead to a small underestimation of the location of the phase transition.
Threshold voltage control by gate oxide thickness in fluorinated GaN metal-oxide-semiconductor high-electron-mobility transistors
Authors: Zhang Yuhao , Sun Min , Joglekar Sameer J. , Fujishima Tatsuya , Palacios Tomás
Published: July 2013

This paper demonstrates the compensation of the intrinsic positive charges in Al2O3 gate dielectric by fluorine ions in GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs). Negatively-charged fluorine ions diffused into the oxide from the AlGaN barrier during the 250 °C atomic layer deposition compensate the intrinsic positive charge present in the Al2O3. This compensation is key to control the threshold voltage (Vth) of enhancement-mode (E-mode) transistors. A comprehensive analytical model for the Vth of fluorinated MOS-HEMTs was established and verified by experimental data. This model allows the calculation of the different charge components in order to optimize the transistor structure for E-mode operation. Using the proposed charge compensation, the Vth increases with gate dielectric thickness, exceeding 3.5 V for gate dielectrics 25 nm thick.
Algebraic method for the harmonic oscillator with a minimal length
Authors: Valtancoli P.
Published: July 2013

We show that the algebraic method solving the ordinary harmonic oscillator can be adapted to the non-commutative case.
Temperature dependent dynamics transition of intermittent plastic flow in a metallic glass. I. Experimental investigations
Authors: Liu Z. Y. , Wang G. , Chan K. C. , Ren J. L. , Huang Y. J. , Bian X. L. , Xu X. H. , Zhang D. S. , Gao Y. L. , Zhai Q. J.
Published: July 2013

Cooling shrinkage can increase the atomic packing density of metallic glasses, which can influence their elastic and plastic behaviour. In the present study, the compressive deformation behaviour of a Zr-based metallic glass at temperatures well below the glassy transition temperature, say 123 K to room temperature, is experimentally revealed. The elastic modulus and the shear modulus at different temperatures are measured to elucidate the yield strength changes with temperature according to the model of shear transformation zones. In the plastic regime, based on the SEM observation and the digital scattering correlation method, an enhanced interaction between the elastic shear strain fields initiated by neighbouring shear bands is discussed, which explains the amplitude of serration events decreasing with the temperature decreasing.
Thermal conductivity from approach-to-equilibrium molecular dynamics
Authors: Lampin E. , Palla P. L. , Francioso P.-A. , Cleri F.
Published: July 2013

We use molecular dynamics simulations to study the thermal transport properties of a range of poor to good thermal conductors by a method in which two portions are delimited and heated at two different temperatures before the approach-to-equilibrium in the whole structure is monitored. The numerical results are compared to the corresponding solution of the heat equation. Based on this comparison, the observed exponential decay of the temperature difference is interpreted and used to extract the thermal conductivity of homogeneous materials. The method is first applied to bulk silicon and an excellent agreement with previous calculations is obtained. Finally, we predict the thermal conductivity of germanium and α-quartz.
Finite element simulations of graphene based three-terminal nanojunction rectifiers
Authors: Butti P. , Shorubalko I. , Sennhauser U. , Ensslin K.
Published: July 2013

Electrical rectification in graphene-based three-terminal nanojunctions is simulated using the finite element method. The model is based on diffusive charge carrier transport in a field-effect transistor configuration. The influence of device geometry, temperature, and electric potential disorder on the rectification efficiency is calculated. For a typical realistic device on a Si/SiO2 substrate, the model yields a room temperature efficiency of about 1% at a bias of 100 mV. The calculations are compared to previously published experimental results.
Calculated properties of point native defects and p-type conductivity of ZnRh2O4
Authors: Volnianska O. , Boguslawski P.
Published: July 2013

Energy levels and formation energies of point native defects, i.e., of vacancies, interstitials, and cation antisites, in ZnRh2O4 were analyzed by first principles density-functional theory-generalized gradient approximation calculations. There are two dominant defects, the Zn vacancy and the ZnRh antisite, which are characterized by very low formation energies, particularly in the O-rich conditions. Both defects are shallow acceptors, and they can be responsible for the observed p-type conductivity of ZnRh2O4. They can also compensate intentional donors making n-conductivity difficult to achieve. In p-ZnRh2O4, the dominant native donor is the RhZn antisite. The O sublattice is robust, since the calculated formation energies of relevant defects exceed 2.5 eV, and thus their equilibrium concentrations are negligible.
Turbulent acceleration and heating in toroidal magnetized plasmas
Authors: Garbet X. , Esteve D. , Sarazin Y. , Abiteboul J. , Bourdelle C. , Dif-Pradalier G. , Ghendrih P. , Grandgirard V. , Latu G. , Smolyakov A.
Published: July 2013

It is shown that turbulence is responsible for a source of momentum, which cannot be recast as a divergence of a momentum flux. This process is similar to turbulent heating, with similar properties. The sum over all species vanishes up to polarization contributions. Hence, toroidal momentum is transferred from species to species, mediated by turbulence. As for momentum flux, symmetry breaking is needed. Flow shear is investigated as a source of symmetry breaking, leading to a source of momentum proportional to the shear rate. Turbulent acceleration is significant for ion species. It is found that it is proportional to the charge number Z, while turbulent heating scales as Z2/A, where A is the mass number. It is maximum in the edge, where the E × B flow shear rate and turbulence intensity are maximum. When both are large enough, the turbulent torque may overcome the collisional friction between impurities and main ions, thus leading to different toroidal velocities.
Numerical study on a 0.4 THz second harmonic gyrotron with high power
Authors: Chaojun Lei , Sheng Yu , Hongfu Li , Yinghui Liu , Xinjian Niu , Qixiang Zhao
Published: July 2013

Terahertz and sub-terahertz science and technology are promising topics today. However, it is difficult to obtain high power source of terahertz wave. In this paper, the mode competition and beam-wave interaction in a gradually tapered cavity are studied to achieve high efficiency of a 0.4THz second harmonic gyrotron in practice. In order to attain high power and stable radiation, the TE32,5 mode is selected as the operating mode of the desired gyrotron to realize single mode oscillation. The issues of studying on the high-order mode gyrotrons are solved effectively by transforming the generalized telegraphist's equations. The efficiency and output power of the gyrotron under different conditions have been calculated by the code, which is based on the transformed equations. Consequently, the results show that single mode second harmonic radiation with power of over 150 kW at frequency of 0.4 THz could be achieved.
Development of magnetohydrodynamic modes during sawteeth in tokamak plasmas
Authors: Firpo M.-C. , Ettoumi W. , Farengo R. , Ferrari H. E. , García-Martínez P. L. , Lifschitz A. F.
Published: July 2013

A dynamical analysis applied to a reduced resistive magnetohydrodynamics model is shown to explain the chronology of the nonlinear destabilization of modes observed in tokamak sawteeth. A special emphasis is put on the nonlinear self-consistent perturbation of the axisymmetric m = n = 0 mode that manifests through the q-profile evolution. For the very low fusion-relevant resistivity values, the q-profile is shown to remain almost unchanged on the early nonlinear timescale within the central tokamak region, which supports a partial reconnection scenario. Within the resistive region, indications for a local flattening or even a local reversed-shear of the q-profile are given. The impact of this ingredient in the occurrence of the sawtooth crash is discussed.
Locally resonant periodic structures with low-frequency band gaps
Authors: Cheng Zhibao , Shi Zhifei , Mo Y. L. , Xiang Hongjun
Published: July 2013

Presented in this paper are study results of dispersion relationships of periodic structures composited of concrete and rubber, from which the frequency band gap can be found. Two models with fixed or free boundary conditions are proposed to approximate the bound frequencies of the first band gap. Studies are conducted to investigate the low-frequency and directional frequency band gaps for their application to engineering. The study finds that civil engineering structures can be designed to block harmful waves, such as earthquake disturbance.
High performance In2O3 thin film transistors using chemically derived aluminum oxide dielectric
Authors: Nayak Pradipta K. , Hedhili M. N. , Cha Dongkyu , Alshareef H. N.
Published: July 2013

We report high performance solution-deposited indium oxide thin film transistors with field-effect mobility of 127 cm2/Vs and an Ion/Ioff ratio of 106. This excellent performance is achieved by controlling the hydroxyl group content in chemically derived aluminum oxide (AlOx) thin-film dielectrics. The AlOx films annealed in the temperature range of 250–350 °C showed higher amount of Al-OH groups compared to the films annealed at 500 °C, and correspondingly higher mobility. It is proposed that the presence of Al-OH groups at the AlOx surface facilitates unintentional Al-doping and efficient oxidation of the indium oxide channel layer, leading to improved device performance.
Communication: Nonadiabatic ring-polymer molecular dynamics
Authors: Richardson Jeremy O. , Thoss Michael
Published: July 2013

A new method based on an extension of ring-polymer molecular dynamics is proposed for the calculation of thermal correlation functions in electronically nonadiabatic systems. The ring-polymer dynamics are performed using a continuous-variable representation of the electronic states within the mapping approach, such that the electronic and nuclear degrees of freedom are treated on an equal footing. Illustrative applications of the method show good agreement with exact quantum results for the dynamics over short to moderate times and reveal a systematic improvement over the classical implementation of the mapping approach (single-bead limit). Being based on trajectories, the method scales well with the number of degrees of freedom and will be applicable to simulate certain nonadiabatic processes in complex molecular systems.
Anomalous Fermi level behavior in GaMnAs at the onset of ferromagnetism
Authors: Muneta Iriya , Terada Hiroshi , Ohya Shinobu , Tanaka Masaaki
Published: July 2013

We present the systematic study of the resonant tunneling spectroscopy on a series of ferromagnetic-semiconductor Ga1−xMnxAs with the Mn content x from ∼0.01 to 3.2%. The Fermi level of Ga1−xMnxAs exists in the band gap in the whole x region. The Fermi level is closest to the valence band (VB) at x = 1.0% corresponding to the onset of ferromagnetism near the metal-insulator transition (MIT), but it moves away from the VB as x increases or decreases from 1.0%. This anomalous behavior of the Fermi level indicates that the ferromagnetism and MIT emerge in the Mn-derived impurity band.
Dynamics of hydrogen sensing with Pt/TiO2 Schottky diodes
Authors: Cerchez M. , Langer H. , El Achhab M. , Heinzel T. , Ostermann D. , Lüder H. , Degenhardt J.
Published: July 2013

The dynamics of hydrogen sensing with nanoporous Pt/TiO2 Schottky barriers is studied by time-resolved electronic transport measurements. The development with time of the doping density, the average Schottky barrier height, and the built-in voltage are determined from current-voltage and capacitance-voltage characteristics. The current-voltage characteristics change from exponential towards Ohmic behavior as time proceeds. This is interpreted in terms of local areas that switch from diodic to Ohmic response due to a combination of increasing doping density and decreasing Schottky barrier height.
Determination of band alignment of pulsed-laser-deposited perovskite titanate/III-V semiconductor heterostructure using X-ray and ultraviolet photoelectron spectroscopy
Authors: Yang Zhibin , Huang Wen , Hao Jianhua
Published: July 2013

Techniques of X-ray and ultraviolet photoelectron spectroscopy are performed to investigate the energy band discontinuity of pulsed-laser-deposited SrTiO3 (STO)/GaAs heterostructure. The valence band offset is determined to be 2.6 eV, while the conduction band offset is deduced to be 0.7 eV. As a consequence, an energy band diagram of STO/GaAs with a type II band alignment forming at the interface is precisely constructed. The chemical states across the STO/GaAs interface are investigated by sputter-depth profile, and there are no detectable interfacial reaction and intermediate layer occurring between the epitaxial STO film and GaAs substrate.
Living without Fruit Flies: Biosecuring Horticulture and its Markets
Authors: Phillips Catherine
Published: July 2013

In this paper, informed by more-than-human and biosecurity literatures, I attend a neglected nonhuman considered a serious agricultural pest: the fruit fly. In addressing what it takes to live without fruit flies, biosecurity is theorised as ongoing, enacted achievement sustained (or not) by everyday and eventful interactions of heterogeneous spaces, strategies, and participants—human and nonhuman. Relations of fruits, flies, and people are explored through one vital attempt to biosecure life: Australia's Fruit Fly Exclusion Zone (FFEZ), a tristate pest-free area established to protect commercial horticulture from the fruit fly. Fruit flies become problematised as their appetites and mobilities confound fruit production and marketing, and affiliated biosecurity controls. Making fruit safe enrolls policy and agricultural sectors, but also more dispersed agents (travellers, residents, trees) and management sites (primarily off-farm). Since its introduction, the FFEZ's ongoing biosecuring normalised, with only occasional outbreak events. However, recent unprecedented outbreaks evoke questions about the FFEZ's future status. In such eventful times, it is worth reflecting on what kinds of living are possible in biosecurity zones—for flies, for resident human communities, and for agrifood networks.
Exhibiting the ‘Orient’: Historicising Theory and Curatorial Practice in UK Museums and Galleries
Authors: Bryce Derek , Carnegie Elizabeth
Published: July 2013

This paper examines the extent to which theory emerges in practice within the context of museum curatorship and the public discourses surrounding it. The theoretical context is the legacy of Edward W Said's canonical study, Orientalism and its call for ‘Western’ reflexivity in the politics of representation of the Islamic Near East. We argue that Said's study has, in its own right, engendered a field of professional academic discourse in the areas of cultural studies and postcolonial studies. We, however, begin to ask about the extent to which its arguments and insights explicitly inform the work of representation and interpretation of the material culture of the Near East in ‘Western’ institutions. This exploratory study draws on four cases of exhibitions on Iranian, Turkish, and the broader field of Islamic art in nationally funded or endorsed museums and galleries in the United Kingdom. All of the exhibitions took place after 2001 amongst cultural and political discourses concerning Islam during the so-called ‘War on Terror’. This convergence of an established ‘Saidian’ theoretical legacy and recent geopolitical events that once again raise questions about the relationship between the ‘West’ and ‘Islam’ allows these exhibitions and the discourses surrounding them to be historically emplotted in quite specific ways. Analysis of exhibition catalogues, consultants' impact reports, and interviews with curatorial staff leads us to conclude that, while a specific engagement with Said's work may not be in evidence, institutions and their staff do inhabit and act upon a discursive field that corresponds to that book's priorities and agenda. This invites further investigation into the form and process within which critical theory makes the transition from citation and discussion in strictly academic discourse to actual implementation in historically situated organisational practice.
Determining background levels and defining outbreaks of crustose coralline algae disease on the Great Barrier Reef
Authors: Miller I. R. , Logan M. , Johns K. A. , Jonker M. J. , Osborne K. , Sweatman H. P. A.
Published: July 2013

Crustose coralline algae (CCA) play a vital role in coral-reef ecosystems and, like other marine organisms, they are vulnerable to disease. Between 2006 and 2011, incidence of two types of CCA disease was systematically recorded over a large portion of the Great Barrier Reef (GBR). The two CCA diseases that were recorded, coralline lethal orange disease and coralline white-band syndrome, were ubiquitous on the GBR, but generally at low levels comparable to those found on reefs in other parts of the Indo-Pacific. The present broad-scale study of the distribution and abundance of CCA disease on the GBR provides information on background levels of these diseases and allows regional thresholds for outbreaks to be defined. This will allow managers and researchers to focus attention on areas of high incidence of CCA disease to increase our understanding of causes and the environmental impacts of CCA disease at a time when coral reefs are under growing anthropogenic threats.
A new approach using biomarkers to elucidate the regression state of the invasive alga Caulerpa taxifolia in waters around the Balearic Islands (Western Mediterranean Sea)
Authors: Tejada Silvia , Sureda Antoni
Published: July 2013

Invasive algae alter the structure and function of ecosystems. The green alga Caulerpa taxifolia is an invasive alga introduced in the Mediterranean Sea, whereas Caulerpa prolifera is a native species in Mediterranean waters. The aim of the current work was to determine the oxidative status of both Caulerpa species by means of biomarker measures as a possible indicator of the regression state of C. taxifolia in waters around the Balearic Islands (western Mediterranean Sea). The levels of markers of lipid peroxidation, glutathione concentration, activities of antioxidant enzymes and caulerpenyne production were measured in C. prolifera and C. taxifolia fronds. The concentration of the end product of lipid peroxidation, malondialdehyde, was significantly higher in C. taxifolia than in C. prolifera samples. Antioxidant enzyme activities, namely superoxide dismutase glutathione peroxidase and glutathione reductase, as well as the reduced glutathione : glutathione disulfide ratio were lower in C. taxifolia than in C. prolifera, although the concentrations of malondialdehyde were higher in the alien species. No differences were found in catalase activity or in the concentration of caulerpenyne. In conclusion, the invasive alga C. taxifolia presented a more oxidised status, which could be related to its regression in Mallorcan coastal waters.
NMR paves the way for atomic level descriptions of sparsely populated, transiently formed biomolecular conformers
Authors: Sekhar Ashok , Kay Lewis E.
Published: July 2013

The importance of dynamics to biomolecular function is becoming increasingly clear. A description of the structure–function relationship must, therefore, include the role of motion, requiring a shift in paradigm from focus on a single static 3D picture to one where a given biomolecule is considered in terms of an ensemble of interconverting conformers, each with potentially diverse activities. In this Perspective, we describe how recent developments in solution NMR spectroscopy facilitate atomic resolution studies of sparsely populated, transiently formed biomolecular conformations that exchange with the native state. Examples of how this methodology is applied to protein folding and misfolding, ligand binding, and molecular recognition are provided as a means of illustrating both the power of the new techniques and the significant roles that conformationally excited protein states play in biology.
Transnational Trade Union Action in Europe
Authors: Larsson Bengt
Published: July 2013

Research on European trade unionism has discussed whether the tendency towards ‘union diplomacy’ has meant that that unions are largely disinterested in mobilizing members and pursue contentious action at the European level. Other studies have identified activities that suggest an Europeanization of political mobilization, in demonstrations and strikes and in cooperation with NGOs and social movements. The present paper analyzes attitudes towards transnational action among trade unions in Europe, as well as the degree to which national unions actually partake in more and less contentious action. The study, which is based on a survey to trade unions in Europe carried out in 2010–11 (n 250), focuses particularly on the production of joint statements and petitions, demonstrations and boycotts, and strikes. The aim was to identify the similarities and differences between industrial relations regimes and sectors in Europe and the analyses have revealed that there are in fact significant differences. Trade unions in the continental social partnership regime and the southern polarized/state centered regime tend to approve of and partake in European demonstrations and boycotts to a higher degree than unions in the other regimes, while the Nordic unions in the organized corporatist regime tend to be more skeptical and also participate to a lower degree. In addition, unions in services and organizing professionals tend to partake and approve of such action to a lower degree than unions in other sectors and national peak level unions.
Brainwave entrainment for better sleep and post‐sleep state of young elite soccer players – A pilot study
Authors: Abeln Vera , Kleinert Jens , Strüder Heiko K. , Schneider Stefan
Published: July 2013

The effect of sleep deprivation on psychophysical performance and well‐being is comprehensively investigated. Research investigating the effect of improved sleep is rare. Just as little exists about attempts to support athletic mental state and performance by improving sleep quality. This study aims to investigate whether sleep quality of top athletes can be improved by auditory brainwave entrainment and whether this leads to enhancements of post‐sleep psychophysical states. In a pilot study, 15 young elite soccer players were stimulated for eight weeks during sleep with binaural beats around 2–8 Hz. Once a week after wake‐up, participants completed three different questionnaires: a sleep diary, an adjective list for psychophysical and motivational state, and a self‐assessment questionnaire for sleep and awakening quality. Fifteen sport students executed the same protocol sleeping on the same pillow, but without stimulation. Subjective ratings of sleep and awakening quality, sleepiness and motivational state were significantly improved only in the intervention group, but did not impact their perceived physical state. In summary, eight weeks of auditory stimulation with binaural beats improved perceived sleep quality and the post‐sleep state of athletes, whereas the effect on physical level is assumed to occur in a time‐delayed fashion. It seems to be worthwhile – to further elaborate long‐time effects and consequences on physical and mental performance.
Rap-afadin axis in control of Rho signaling and endothelial barrier recovery
Authors: Birukova Anna A. , Tian Xinyong , Tian Yufeng , Higginbotham Katherine , Birukov Konstantin G.
Published: July 2013

Activation of the Rho GTPase pathway determines endothelial cell (EC) hyperpermeability after injurious stimuli. To date, feedback mechanisms of Rho down-regulation critical for barrier restoration remain poorly understood. We tested a hypothesis that Rho down-regulation and barrier recovery of agonist-stimulated ECs is mediated by the Ras family GTPase Rap1. Thrombin-induced EC permeability driven by rapid activation of the Rho GTPase pathway was followed by Src kinase–dependent phosphorylation of the Rap1-specific guanine nucleotide exchange factor (GEF) C3G, activation of Rap1, and initiation of EC barrier recovery. Knockdown experiments showed that Rap1 activation was essential for down-regulation of Rho signaling and actin stress fiber dissolution. Rap1 activation also enhanced interaction between adherens junction (AJ) proteins VE-cadherin and p120-catenin and stimulated AJ reannealing mediated by the Rap1 effector afadin. This mechanism also included Rap1-dependent membrane translocation of the Rac1-specific GEF Tiam1 and activation of Rac1-dependent peripheral cytoskeletal dynamics, leading to resealing of intercellular gaps. These data demonstrate that activation of the Rap1-afadin axis is a physiological mechanism driving restoration of barrier integrity in agonist-stimulated EC monolayers via negative-feedback regulation of Rho signaling, stimulation of actin peripheral dynamics, and reestablishment of cell–cell adhesive complexes.
The Functioning of Bankruptcy Law and Practices in European Perspective (ca.1880–1913)
Authors: Hautcoeur Pierre-Cyrille , Di Martino Paolo
Published: July 2013

A growing body of research in economics and in business and economic history has shown the key role of bankruptcy and insolvency law on business organization, firms’ governance, and entrepreneurial choices. Most research, however, has focused on the formal aspects of laws, and still little is known on how various systems worked in practices. This paper fills this gap in the literature analyzing the functioning of bankruptcy procedures in four main European economies (Italy, France, England, and Germany) between ca.1880 and 1914. Using an original data set and descriptive statistics on length, organization, and return of procedures, the paper shows how the aim of attracting debtors was more successful in the less regulated English system, but how the protection of creditors’ rights was more efficiently pursued in France and Germany. Italy appears as the absolute worst performer.
A TAF4 coactivator function for E proteins that involves enhanced TFIID binding
Authors: Chen Wei-Yi , Zhang Jinsong , Geng Huimin , Du Zhimei , Nakadai Tomoyoshi , Roeder Robert G.
Published: July 2013

The multisubunit TFIID plays a direct role in transcription initiation by binding to core promoter elements and directing preinitiation complex assembly. Although TFIID may also function as a coactivator through direct interactions with promoter-bound activators, mechanistic aspects of this poorly defined function remain unclear. Here, biochemical studies show a direct TFIID–E-protein interaction that (1) is mediated through interaction of a novel E-protein activation domain (activation domain 3 [AD3]) with the TAF homology (TAFH) domain of TAF4, (2) is critical for activation of a natural target gene by an E protein, and (3) mechanistically acts by enhancing TFIID binding to the core promoter. Complementary assays establish a gene-specific role for the TAFH domain in TFIID recruitment and activation of a large subset of genes in vivo. These results firmly establish TAF4 as a bona fide E-protein coactivator as well as a mechanism involving facilitated TFIID binding through direct interaction with an E-protein activation domain.
Differential Tks5 isoform expression contributes to metastatic invasion of lung adenocarcinoma
Authors: Li Carman Man-Chung , Chen Guoan , Dayton Talya L. , Kim-Kiselak Caroline , Hoersch Sebastian , Whittaker Charles A. , Bronson Roderick T. , Beer David G. , Winslow Monte M. , Jacks Tyler
Published: July 2013

Metastasis accounts for the vast majority of cancer-related deaths, yet the molecular mechanisms that drive metastatic spread remain poorly understood. Here we report that Tks5, which has been linked to the formation of proteolytic cellular protrusions known as invadopodia, undergoes an isoform switch during metastatic progression in a genetically engineered mouse model of lung adenocarcinoma. Nonmetastatic primary tumor-derived cells predominantly expressed a short isoform, Tks5short, while metastatic primary tumor- and metastasis-derived cells acquired increased expression of the full-length isoform Tks5long. This elevation of Tks5long to Tks5short ratio correlated with a commensurate increase in invadopodia activity in metastatic cells compared with nonmetastatic cells. Further characterization of these isoforms by knockdown and overexpression experiments demonstrated that Tks5long promoted invadopodia in vitro and increased metastasis in transplant models and an autochthonous model of lung adenocarcinoma. Conversely, Tks5short decreased invadopodia stability and proteolysis, acting as a natural dominant-negative inhibitor to Tks5long. Importantly, high Tks5long and low Tks5short expressions in human lung adenocarcinomas correlated with metastatic disease and predicted worse survival of early stage patients. These data indicate that tipping the Tks5 isoform balance to a high Tks5long to Tks5short ratio promotes invadopodia-mediated invasion and metastasis.
Recognition errors suggest fast familiarity and slow recollection in rhesus monkeys
Authors: Basile Benjamin M. , Hampton Robert R.
Published: July 2013

One influential model of recognition posits two underlying memory processes: recollection, which is detailed but relatively slow, and familiarity, which is quick but lacks detail. Most of the evidence for this dual-process model in nonhumans has come from analyses of receiver operating characteristic (ROC) curves in rats, but whether ROC analyses can demonstrate dual processes has been repeatedly challenged. Here, we present independent converging evidence for the dual-process model from analyses of recognition errors made by rhesus monkeys. Recognition choices were made in three different ways depending on processing duration. Short-latency errors were disproportionately false alarms to familiar lures, suggesting control by familiarity. Medium-latency responses were less likely to be false alarms and were more accurate, suggesting onset of a recollective process that could correctly reject familiar lures. Long-latency responses were guesses. A response deadline increased false alarms, suggesting that limiting processing time weakened the contribution of recollection and strengthened the contribution of familiarity. Together, these findings suggest fast familiarity and slow recollection in monkeys, that monkeys use a “recollect to reject” strategy to countermand false familiarity, and that primate recognition performance is well-characterized by a dual-process model consisting of recollection and familiarity.
Mechanisms contributing to the induction and storage of Pavlovian fear memories in the lateral amygdala
Authors: Kim Dongbeom , Paré Denis , Nair Satish S.
Published: July 2013

The relative contributions of plasticity in the amygdala vs. its afferent pathways to conditioned fear remain controversial. Some believe that thalamic and cortical neurons transmitting information about the conditioned stimulus (CS) to the lateral amygdala (LA) serve a relay function. Others maintain that thalamic and/or cortical plasticity is critically involved in fear conditioning. To address this question, we developed a large-scale biophysical model of the LA that could reproduce earlier findings regarding the cellular correlates of fear conditioning in LA. We then conducted model experiments that examined whether fear memories depend on (1) training-induced increases in the responsiveness of thalamic and cortical neurons projecting to LA, (2) plasticity at the synapses they form in LA, and/or (3) plasticity at synapses between LA neurons. These tests revealed that training-induced increases in the responsiveness of afferent neurons are required for fear memory formation. However, once the memory has been formed, this factor is no longer required because the efficacy of the synapses that thalamic and cortical neurons form with LA cells has augmented enough to maintain the memory. In contrast, our model experiments suggest that plasticity at synapses between LA neurons plays a minor role in maintaining the fear memory.
Potentiating mGluR5 function with a positive allosteric modulator enhances adaptive learning
Authors: Xu Jian , Zhu Yongling , Kraniotis Stephen , He Qionger , Marshall John J. , Nomura Toshihiro , Stauffer Shaun R. , Lindsley Craig W. , Conn P. Jeffrey , Contractor Anis
Published: July 2013

Metabotropic glutamate receptor 5 (mGluR5) plays important roles in modulating neural activity and plasticity and has been associated with several neuropathological disorders. Previous work has shown that genetic ablation or pharmacological inhibition of mGluR5 disrupts fear extinction and spatial reversal learning, suggesting that mGluR5 signaling is required for different forms of adaptive learning. Here, we tested whether ADX47273, a selective positive allosteric modulator (PAM) of mGluR5, can enhance adaptive learning in mice. We found that systemic administration of the ADX47273 enhanced reversal learning in the Morris Water Maze, an adaptive task. In addition, we found that ADX47273 had no effect on single-session and multi-session extinction, but administration of ADX47273 after a single retrieval trial enhanced subsequent fear extinction learning. Together these results demonstrate a role for mGluR5 signaling in adaptive learning, and suggest that mGluR5 PAMs represent a viable strategy for treatment of maladaptive learning and for improving behavioral flexibility.
Psuedosymmetry and pseudomerodry or nonmerohedral twinning for the known structure of diaquabis(quinolin-8-olato-κ2N,O)zinc(II)
Authors: Varelas Georgios , Salifoglou Athanasios , Psycharis Vassilis
Published: July 2013

The structure of the title centrosymmetric compound, [Zn(C9H6NO)2(H2O)2], has already been solved three times [Merritt, Cady & Mundy (1954).Acta Cryst.7, 473–476; Palenik (1964).Acta Cryst.17, 696–700; Chen, Zhang, Shi, Huang, Liang & Zhou (2003).Acta Cryst.E59, m814–m815]. The authors of the two most recent papers state that they attained lowerR1 values than that obtained in the 1954 paper, but they do not mention that Merrittet al.had derived the structural model from a twinned crystal. Also, from a structural point of view, there are strong indications that the most recent report is in fact the isostructural CuIIcomplex already reported by Okabe & Saishu [Acta Cryst.(2001), E57, m251–m252] and not the ZnIIcomplex. The structure of the title compound is reported here based on data obtained from a twinned crystal.
Decision-contextual and individual influences on scarcity effects
Authors: Ku Hsuan-Hsuan , Kuo Chien-Chih , Yang Yi-Ting , Chung Tzu-Shao
Published: July 2013

Purpose

– This study aims to examine the relative effectiveness of demand-related and supply-related explanations of the scarcity of a product, and specifically the extent to which decision context and individual factors moderate purchase intention in response to those explanations.

Design/methodology/approach

– The first of two formal experiments examines the effects of the two kinds of scarcity on participants
'
purchase intentions with respect to utilitarian and hedonic product types. The second tests for self-monitoring differences in participants
'
relative susceptibility to scenarios characterizing scarcity as either demand-generated or supply-generated, when their decisions are either private or subject to third-party scrutiny.

Findings

– Experiment 1 shows that participants shopping for a utilitarian product are more inclined to respond positively to what they understand to be demand-generated scarcity, and less inclined to do so if the scarcity was attributed to limited supply; whereas the converse holds true for a hedonic product. Experiment 2 shows that for high self-monitors, increased purchase intention was the outcome of matching the alleged reason for scarcity to the demands of the decision context; low self-monitors were ready to consider demand-scarce products regardless of whether they knew that their consumption decisions would be subject to third-party scrutiny or private.

Originality/value

– The paper identifies contextual and individual factors that explain and predict the extent to which one type of scarcity appeal may be more effective than another in influencing consumers
'
purchasing decisions.
A polynomial chaos meta‐model for non‐linear stochastic magnet variations
Authors: Offermann Peter , Hameyer Kay
Published: July 2013

Purpose

Due to the production process, arc segment magnets with radial magnetization for surface‐mounted permanent‐magnet synchronous machines (PMSM) can exhibit a deviation from the intended ideal, radial directed magnetization. In such cases, the resulting air gap field may show spatial variations in angle and absolute value of the flux‐density. For this purpose, this paper aims to create and evaluate a stochastic magnet model.

Design/methodology/approach

In this paper, a polynomial chaos meta‐model approach, extracted from a finite element model, is compared to a direct sampling approach. Both approaches are evaluated using Monte‐Carlo simulation for the calculation of the flux‐density above one sole magnet surface.

Findings

The used approach allows representing the flux‐density's variations in terms of the magnet's stochastic input variations, which is not possible with pure Monte‐Carlo simulation. Furthermore, the resulting polynomial‐chaos meta‐model can be used to accelerate the calculation of error probabilities for a given limit state function by a factor of ten.

Research limitations/implications

Due to epistemic uncertainty magnet variations are assumed to be purely Gaussian distributed.

Originality/value

The comparison of both approaches verifies the assumption that the polynomial chaos meta‐model of the magnets will be applicable for a complete machine simulation.