bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved initial guess for minimum energy path calculations
Authors: Smidstrup Søren , Pedersen Andreas , Stokbro Kurt , Jónsson Hannes
Published: June 2014

A method is presented for generating a good initial guess of a transition path between given initial and final states of a system without evaluation of the energy. An objective function surface is constructed using an interpolation of pairwise distances at each discretization point along the path and the nudged elastic band method then used to find an optimal path on this image dependent pair potential (IDPP) surface. This provides an initial path for the more computationally intensive calculations of a minimum energy path on an energy surface obtained, for example, by ab initio or density functional theory. The optimal path on the IDPP surface is significantly closer to a minimum energy path than a linear interpolation of the Cartesian coordinates and, therefore, reduces the number of iterations needed to reach convergence and averts divergence in the electronic structure calculations when atoms are brought too close to each other in the initial path. The method is illustrated with three examples: (1) rotation of a methyl group in an ethane molecule, (2) an exchange of atoms in an island on a crystal surface, and (3) an exchange of two Si-atoms in amorphous silicon. In all three cases, the computational effort in finding the minimum energy path with DFT was reduced by a factor ranging from 50% to an order of magnitude by using an IDPP path as the initial path. The time required for parallel computations was reduced even more because of load imbalance when linear interpolation of Cartesian coordinates was used.
General coalescence conditions for the exact wave functions. II. Higher-order relations for many-particle systems
Authors: Kurokawa Yusaku I. , Nakashima Hiroyuki , Nakatsuji Hiroshi
Published: June 2014

We derived the necessary conditions that must be satisfied by the non-relativistic time-independent exact wave functions for many-particle systems at a two-particle coalescence (or cusp) point. Some simple conditions are known to be Kato's cusp condition (CC) and Rassolov and Chipman's CC. In a previous study, we derived an infinite number of necessary conditions that two-particle wave functions must satisfy at a coalescence point. In the present study, we extend these conditions to many-particle systems. They are called general coalescence conditions (GCCs), and Kato's CC and Rassolov and Chipman's CC are included as special conditions. GCCs can be applied not only to Coulombic systems but also to any system in which the interaction between two particles is represented in a power series of inter-particle distances. We confirmed the correctness of our derivation of the GCCs by applying the exact wave function of a harmonium in electron-electron and electron-nucleus coalescence situations. In addition, we applied the free complement (FC) wave functions of a helium atom to the GCCs to examine the accuracy of the FC wave function in the context of a coalescence situation.
Temporal change in the electromechanical properties of dielectric elastomer minimum energy structures
Authors: Buchberger G. , Hauser B. , Schoeftner J. , Bauer S. , Jakoby B. , Hilber W.
Published: June 2014

Dielectric elastomer minimum energy structures (DEMES) are soft electronic transducers and energy harvesters with potential for consumer goods. The temporal change in their electromechanical properties is of major importance for engineering tasks. Therefore, we study acrylic DEMES by impedance spectroscopy and by optical methods for a total time period of approx. 4.5 months. We apply either compliant electrodes from carbon black particles only or fluid electrodes from a mixture of carbon black particles and silicone oil. From the measurement data, the equivalent series capacitances and resistances as well as the bending angles of the transducers are obtained. We find that the equivalent series capacitances change in average between −12 %/1000 h and −4.0 %/1000 h, while the bending angles decrease linearly with slopes ranging from −15 %/1000 h to −7 %/1000 h. Transducers with high initial bending angles and electrodes from carbon black particles show the smallest changes of the electromechanical characteristics. The capacitances decrease faster for DEMES with fluid electrodes. Some DEMES of this type reveal huge and unpredictable fluctuations of the resistances over time due to the ageing of the contacts. Design guidelines for DEMES follow directly from the observed transient changes of their electromechanical performance.
Measurement of neutron spectra generated from bombardment of 4 to 24 MeV protons on a thick 9Be target and estimation of neutron yields
Authors: Paul Sabyasachi , Sahoo G. S. , Tripathy S. P. , Sharma S. C. , Ramjilal  , Ninawe N. G. , Sunil C. , Gupta A. K. , Bandyopadhyay T.
Published: June 2014

A systematic study on the measurement of neutron spectra emitted from the interaction of protons of various energies with a thick beryllium target has been carried out. The measurements were carried out in the forward direction (at 0° with respect to the direction of protons) using CR-39 detectors. The doses were estimated using the in-house image analyzing program autoTRAK_n, which works on the principle of luminosity variation in and around the track boundaries. A total of six different proton energies starting from 4 MeV to 24 MeV with an energy gap of 4 MeV were chosen for the study of the neutron yields and the estimation of doses. Nearly, 92% of the recoil tracks developed after chemical etching were circular in nature, but the size distributions of the recoil tracks were not found to be linearly dependent on the projectile energy. The neutron yield and dose values were found to be increasing linearly with increasing projectile energies. The response of CR-39 detector was also investigated at different beam currents at two different proton energies. A linear increase of neutron yield with beam current was observed.
Dynamical (e,2e) studies of tetrahydropyran and 1,4-dioxane
Authors: Builth-Williams J. D. , da Silva G. B. , Chiari L. , Jones D. B. , Chaluvadi Hari , Madison D. H. , Brunger M. J.
Published: June 2014

We present experimental and theoretical results for the electron-impact ionization of the highest occupied molecular orbitals of tetrahydropyran and 1,4-dioxane. Using an (e,2e) technique in asymmetric coplanar kinematics, angular distributions of the slow ejected electron, with an energy of 20 eV, are measured when incident electrons at 250 eV ionize the target and scatter through an angle of either −10° or −15°. The data are compared with calculations performed at the molecular 3-body distorted wave level. Fair agreement between the theoretical model and the experimental measurements was observed. The similar structures for these targets provide key insights for assessing the limitations of the theoretical calculations. This study in turn facilitates an improved understanding of the dynamics in the ionization process.
Local oscillator phase noise limitation on the resolution of acoustic delay line wireless passive sensor measurement
Authors: Chrétien N. , Friedt J.-M. , Martin G.
Published: June 2014

The role of the phase noise of a local oscillator driving a pulsed-mode RADAR used for probing surface acoustic wave sensors is investigated. The echo delay, representative of the acoustic velocity, and hence the physical quantity probed by the sensor, is finely measured as a phase. Considering that the intrinsic oscillator phase fluctuation defines the phase noise measurement resolution, we experimentally and theoretically assess the relation between phase noise, measurement range, and measurand resolution.
Gradient index collimator lens for high pressure applications
Authors: Piechal Bernard , Bercha Artem , Dybala Filip , Trzeciakowski Witold
Published: June 2014

A modified gradient index (GRIN) lens is optimised for use in a liquid-type high pressure cell. It was found that high pressure changes the optical power of the gradient-index lenses by changing the index profile of the glass. In this paper, we present a modified GRIN lens in which these changes are compensated by the pressure-induced changes of the refraction index of the liquid used as a pressure medium. New lens was used for the collimation of the pressure tuned tapered laser working in external resonator. The lens proved to have the optical power almost independent of the pressure up to 1.6 GPa, as it allowed to obtain tuning range almost independent on pressure without the need of any modification of the optical setup.
An experimental set-up to apply polarization modulation to infrared reflection absorption spectroscopy for improved in situ studies of atmospheric corrosion processes
Authors: Wiesinger R. , Schade U. , Kleber Ch. , Schreiner M.
Published: June 2014

A new set-up for improved monitoring of atmospheric corrosion processes in situ and in real-time is presented. To characterize chemical structures of thin films on metal surfaces surface sensitive analytical techniques are required. One possible technique is Infrared Reflection Absorption Spectroscopy (IRRAS) which has become an established method to investigate surface corrosion films of thicknesses less than 200 nm. However, there are limitations related to the sensitivity of these measurements, in case of investigating ultrathin films or absorption bands of interest, surface species are superimposed by atmospheric background absorption, which changes during in situ measurements in ambient atmospheres. These difficulties of in situ surface reflection measurements can be eliminated by availing the polarization selectivity of adsorbed surface species. At grazing angles of incidence the absorption of p-polarized infrared radiation by thin surface films on metals is enhanced, while the absorption of s-polarized light by this film is nearly zero. This different behavior of the polarization properties leads to strong selection rules at the surface and can therefore be used to identify molecules adsorbed on metal surfaces. Polarization Modulation (PM) of the infrared (IR) light takes advantage of this disparity of polarization on sample surfaces and in combination with IRRAS yielding a very sensitive and surface-selective method for obtaining IR spectra of ultra-thin films on metal surfaces. An already existing in situ IRRAS/Quartz Crystal Microbalance weathering cell was combined with PM and evaluated according to its applicability to study in situ atmospheric corrosion processes. First real-time measurements on silver samples exposed to different atmospheres were performed showing the advantage of PM-IRRAS compared to conventional IRRAS for such investigations.
Exciton dynamics at the heteromolecular interface between N,N′-dioctyl-3,4,9,10-perylenedicarboximide and quaterrylene, studied using time-resolved photoluminescence
Authors: Hiroshiba Nobuya , Morimoto Kenta , Hayakawa Ryoma , Wakayama Yutaka , Mori Tatsuo , Matsuishi Kiyoto
Published: June 2014

To elucidate the exciton dynamics at the heteromolecular interface, the temperature dependence of time-resolved photoluminescence (TRPL) spectra of neat-N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) and PTCDI-C8/Quaterrylene (QT) heteromolecular thin films was investigated. The lifetimes of excitons were evaluated to identify the Frenkel (FE), high energy charge-transfer (CTEhigh), low energy charge-transfer (CTElow), and excimer exciton states. The thermal activation energy (Δact) of CTElow in PTCDI-C8 thin film was evaluated as 25 meV, which is 1/5 of that of FE, indicating that CTElow is more thermally sensitive than FE in PTCDI-C8 thin film. We investigated the exciton transport length (l) along the vertical direction against the substrate surface in PTCDI-C8/QT thin film at 30 K, and demonstrated that lFE = 9.9 nm, lCTElow = 4.2 nm, lCTEhigh = 4.3 nm, and lexcimer = 11.9 nm. To elucidate the difference in l among these excitons, the activation energies (Ea) for quenching at the heteromolecular interface were investigated. Ea values were estimated to be 13.1 meV for CTElow and 18.6 meV for CTEhigh. These values agree with the thermal sensitivity of CTEs as reported in a previous static PL study. This latter situation is different from the case of FE and excimer excitons, which are transported via a resonant process and have no temperature dependence. The small Ea values of CTEs suggest that exciton transport takes place via a thermal hopping process in CTEs. The present experimental study provides information on nano-scaled exciton dynamics in a well-defined PTCDI-C8 (2 ML)/QT (2 ML) system.
Radiation transport and energetics of laser-driven half-hohlraums at the National Ignition Facility
Authors: Moore A. S. , Cooper A. B. R. , Schneider M. B. , MacLaren S. , Graham P. , Lu K. , Seugling R. , Satcher J. , Klingmann J. , Comley A. J. , Marrs R. , May M. , Widmann K. , Glendinning G. , Castor J. , Sain J. , Back C. A. , Hund J. , Baker K. , Hsing W. W. , Foster J. , Young B. , Young P.
Published: June 2014

Experiments that characterize and develop a high energy-density half-hohlraum platform for use in benchmarking radiation hydrodynamics models have been conducted at the National Ignition Facility (NIF). Results from the experiments are used to quantitatively compare with simulations of the radiation transported through an evolving plasma density structure, colloquially known as an N-wave. A half-hohlraum is heated by 80 NIF beams to a temperature of 240 eV. This creates a subsonic diffusive Marshak wave, which propagates into a high atomic number Ta2O5 aerogel. The subsequent radiation transport through the aerogel and through slots cut into the aerogel layer is investigated. We describe a set of experiments that test the hohlraum performance and report on a range of x-ray measurements that absolutely quantify the energetics and radiation partition inside the target.
Mechanism of coercivity enhancement by Ag addition in FePt-C granular films for heat assisted magnetic recording media
Authors: Varaprasad B. S. D. Ch. S. , Takahashi Y. K. , Wang J. , Ina T. , Nakamura T. , Ueno W. , Nitta K. , Uruga T. , Hono K.
Published: June 2014

We investigated the Ag distribution in a FePtAg-C granular film that is under consideration for a heat assisted magnetic recording medium by aberration-corrected scanning transmission electron microscope-energy dispersive X-ray spectroscopy and X-ray absorption fine structure. Ag is rejected from the core of FePt grains during the deposition, forming Ag-enriched shell surrounding L10-ordered FePt grains. Since Ag has no solubility in both Fe and Pt, the rejection of Ag induces atomic diffusions thereby enhancing the kinetics of the L10-order in the FePt grains.
Cavitation in a metallic liquid: Homogeneous nucleation and growth of nanovoids
Authors: Cai Y. , Wu H. A. , Luo S. N.
Published: June 2014

Large-scale molecular dynamics (MD) simulations are performed to investigate homogeneous nucleation and growth of nanovoids during cavitation in liquid Cu. We characterize in detail the atomistic cavitation processes by following the temporal evolution of cavities or voids, analyze the nucleation behavior with the mean first-passage time (MFPT) and survival probability (SP) methods, and discuss the results against classical nucleation theory (CNT), the Tolman equation for surface energy, independent calculation of surface tension via integrating the stress profiles, the Johnson-Mehl-Avrami (JMA) growth law, and the power law for nucleus size distributions. Cavitation in this representative metallic liquid is a high energy barrier Poisson processes, and the steady-state nucleation rates obtained from statistical runs with the MFPT and SP methods are in agreement. The MFPT method also yields the critical nucleus size and the Zeldovich factor. Fitting with the Tolman's equation to the MD simulations yields the surface energy of a planar interface (∼0.9 J \documentclass[12pt]{minimal}\begin{document}$\rm {m}^{-2}$\end{document}m−2) and the Tolman length (0.4–0.5 Å), and those values are in accord with those from integrating the stress profiles of a planar interface. Independent CNT predictions of the nucleation rate (1033 − 34 s−1 m−3) and critical size (3–4 Å in radius) are in agreement with the MFPT and SP results. The JMA law can reasonably describe the nucleation and growth process. The size distribution of subcritical nuclei appears to follow a power law with an exponent decreasing with increasing tension owing to coupled nucleation and growth, and that of the supercritical nuclei becomes flattened during further stress relaxation due to void coalescence.
Automotion of domain walls for spintronic interconnects
Authors: Nikonov Dmitri E. , Manipatruni Sasikanth , Young Ian A.
Published: June 2014

We simulate “automotion,” the transport of a magnetic domain wall under the influence of demagnetization and magnetic anisotropy, in nanoscale spintronic interconnects. In contrast to spin transfer driven magnetic domain wall motion, the proposed interconnects operate without longitudinal charge current transfer, with only a transient current pulse at domain wall creation and have favorable scaling down to the 20 nm dimension. Cases of both in-plane and out-of-plane magnetization are considered. Analytical dependence of the velocity of domain walls on the angle of magnetization are compared with full micromagnetic simulations. Deceleration, attenuation and disappearance, and reflection of domain walls are demonstrated through simulation. Dependences of the magnetization angle on the current pulse parameters are studied. The energy and delay analysis suggests that automotion is an attractive option for spintronic logic interconnects.
Derivation of a continuum model and the energy law for moving contact lines with insoluble surfactants
Authors: Zhang Zhen , Xu Shixin , Ren Weiqing
Published: June 2014

A continuous model is derived for the dynamics of two immiscible fluids with moving contact lines and insoluble surfactants based on thermodynamic principles. The continuum model consists of the Navier-Stokes equations for the dynamics of the two fluids and a convection-diffusion equation for the evolution of the surfactant on the fluid interface. The interface condition, the boundary condition for the slip velocity, and the condition for the dynamic contact angle are derived from the consideration of energy dissipations. Different types of energy dissipations, including the viscous dissipation, the dissipations on the solid wall and at the contact line, as well as the dissipation due to the diffusion of surfactant, are identified from the analysis. A finite element method is developed for the continuum model. Numerical experiments are performed to demonstrate the influence of surfactant on the contact line dynamics. The different types of energy dissipations are compared numerically.
Carrier concentration dependence of ferroelectric transition in multiferroic Li doped and Li-Co co-doped ZnO nanoparticles
Authors: Ullah Awan Saif , Hasanain S. K. , Hassnain Jaffari G. , Mehmood Zahid
Published: June 2014

Dielectric measurements on both Li doped and Li-Co co-doped multiferroic nanoparticles are presented and correlated with the hole carrier concentrations measured by the Hall effect. The ferroelectric Curie temperatures lay in the range 443–512 K with the dielectric constant increasing monotonically with Li concentration. However, we find that both for these p-type systems, the Curie temperature varies non-monotonically with Li concentration, being larger for compositions with higher hole concentrations and vice versa. We find a similar trend in the variation of the magnetic moment with hole concentration. Hence, the multiferroic behavior in this system is strongly correlated with the hole concentration. The ferroelectric behavior is explained in terms of the model of electric dipoles, formed by Li off-centre impurities, interacting indirectly via the free hole carriers. The variation of the ferroelectric critical temperature with hole concentration is explained within this model in terms of the dependence of the indirect interaction strength on the Fermi wave vector.
The magnetic flywheel flow meter: Theoretical and experimental contributions
Authors: Buchenau D. , Galindo V. , Eckert S.
Published: June 2014

The development of contactless flow meters is an important issue for monitoring and controlling of processes in different application fields, like metallurgy, liquid metal casting, or cooling systems for nuclear reactors and transmutation machines. Shercliff described in his book “The Theory of Electromagnetic Flow Measurement, Cambridge University Press, 1962” a simple and robust device for contact-less measurements of liquid metal flow rates which is known as magnetic flywheel. The sensor consists of several permanent magnets attached on a rotatable soft iron plate. This arrangement will be placed closely to the liquid metal flow to be measured, so that the field of the permanent magnets penetrates into the fluid volume. The flywheel will be accelerated by a Lorentz force arising from the interaction between the magnetic field and the moving liquid. Steady rotation rates of the flywheel can be taken as a measure for the mean flow rate inside the fluid channel. The present paper provides a detailed theoretical description of the sensor in order to gain a better insight into the functional principle of the magnetic flywheel. Theoretical predictions are confirmed by corresponding laboratory experiments. For that purpose, a laboratory model of such a flow meter was built and tested on a GaInSn-loop under various test conditions.
Cryogenic ultrahigh strain rate deformation induced hybrid nanotwinned microstructure for high strength and high ductility
Authors: Ye Chang , Suslov Sergey , Lin Dong , Liao Yiliang , Cheng Gary J.
Published: June 2014

Nanocrystalline metallic materials prepared by severe plastic deformation often possess high strength but low ductility due to the low dislocation accumulation capacity of the nanograins. Here, we report a unique process, namely, cryogenic laser shock peening (CLSP), to generate gradient nanotwinned microstructure that leads to high strength while preserving the ductility. It was observed that gradient structure was generated in copper. Near the top surface, nanocrystalline with high dense nanotwins have been observed; with the depth increasing, the fraction of the twin boundaries reduces and more heavily dislocated subgrains are observed. It has been demonstrated that CLSP can significantly improve material strength while preserving the ductility. The mechanism of the formation of gradient microstructure and high dense nanotwins near the surface was discussed. The reason behind the improvement in strength and ductility was investigated.
Fast, low-power manipulation of spin ensembles in superconducting microresonators
Authors: Sigillito A. J. , Malissa H. , Tyryshkin A. M. , Riemann H. , Abrosimov N. V. , Becker P. , Pohl H.-J. , Thewalt M. L. W. , Itoh K. M. , Morton J. J. L. , Houck A. A. , Schuster D. I. , Lyon S. A.
Published: June 2014

We demonstrate the use of high-Q superconducting coplanar waveguide (CPW) microresonators to perform rapid manipulations on a randomly distributed spin ensemble using very low microwave power (400 nW). This power is compatible with dilution refrigerators, making microwave manipulation of spin ensembles feasible for quantum computing applications. We also describe the use of adiabatic microwave pulses to overcome microwave magnetic field (B1) inhomogeneities inherent to CPW resonators. This allows for uniform control over a randomly distributed spin ensemble. Sensitivity data are reported showing a single shot (no signal averaging) sensitivity to 107 spins or 3×104spins/Hz with averaging.
Field emission characteristics from graphene on hexagonal boron nitride
Authors: Yamada Takatoshi , Masuzawa Tomoaki , Ebisudani Taishi , Okano Ken , Taniguchi Takashi
Published: June 2014

An attempt has been made to utilize uniquely high electron mobility of graphene on hexagonal boron nitride (h-BN) to electron emitter. The field emission property of graphene/h-BN/Si structure has shown enhanced threshold voltage and emission current, both of which are key to develop novel vacuum nanoelectronics devices. The field emission property was discussed along with the electronic structure of graphene investigated by Fowler-Nordheim plot and ultraviolet photoelectron spectroscopy. The result suggested that transferring graphene on h-BN modified its work function, which changed field emission mechanism. Our report opens up a possibility of graphene-based vacuum nanoelectronics devices with tuned work function.
Converse magnetoelectric effect in laminated composite of Metglas and Pb(Zr,Ti)O3 with screen-printed interdigitated electrodes
Authors: Zhang Yuan , Liu Guoxi , Shi Huaduo , Li Meiya , Dong Shuxiang
Published: June 2014

In this study, we investigate the converse magnetoelectric (CME) effect in a laminated composite consisting of Metglas ribbons and Pb(Zr,Ti)O3 (PZT) plate with screen-printed interdigitated electrodes and operating in longitudinal magnetization and longitudinal polarization (L-L) mode. Large CME coefficients of 0.134 G·cm/V at frequency of 1 kHz and 2.75 G·cm/V at resonance frequency of 43.5 kHz under a small bias magnetic field of 7 Oe are achieved. The large CME effect can be attributed to the L-L mode and low mechanical loss of the Metglas/PZT laminated composite.
Current-driven dynamics of Dzyaloshinskii domain walls in the presence of in-plane fields: Full micromagnetic and one-dimensional analysis
Authors: Martinez Eduardo , Emori Satoru , Perez Noel , Torres Luis , Beach Geoffrey S. D.
Published: June 2014

Current-induced domain wall motion along high perpendicular magnetocrystalline anisotropy multilayers is studied by means of full micromagnetic simulations and a one-dimensional model in the presence of in-plane fields. We consider domain wall motion driven by the spin Hall effect in the presence of the Dzyaloshinskii-Moriya interaction (DMI). In the case of relatively weak DMI, the wall propagates without significant tilting of the wall plane, and the full micromagnetic results are quantitatively reproduced by a simple rigid one-dimensional model. By contrast, significant wall-plane tilting is observed in the case of strong DMI, and a one-dimensional description including the wall tilting is required to qualitatively describe the micromagnetic results. However, in this strong-DMI case, the one-dimensional model exhibits significant quantitative discrepancies from the full micromagnetic results, in particular, when high longitudinal fields are applied in the direction of the internal domain wall magnetization. It is also shown that, even under thermal fluctuations and edge roughness, the domain wall develops a net tilting angle during its current-induced motion along samples with strong DMI.
Spin-on-doping for output power improvement of silicon nanowire array based thermoelectric power generators
Authors: Xu B. , Fobelets K.
Published: June 2014

The output power of a silicon nanowire array (NWA)-bulk thermoelectric power generator (TEG) with Cu contacts is improved by spin-on-doping (SOD). The Si NWAs used in this work are fabricated via metal assisted chemical etching (MACE) of 0.01–0.02 Ω cm resistivity n- and p-type bulk, converting ∼4% of the bulk thickness into NWs. The MACE process is adapted to ensure crystalline NWs. Current-voltage and Seebeck voltage-temperature measurements show that while SOD mainly influences the contact resistance in bulk, it influences both contact resistance and power factor in NWA-bulk based TEGs. According to our experiments, using Si NWAs in combination with SOD increases the output power by an order of 3 under the same heating power due to an increased power factor, decreased thermal conductivity of the NWA and reduced Si-Cu contact resistance.
Effect of Ce doping on the electrocaloric effect of SrxBa1−xNb2O6 single crystals
Authors: Le Goupil Florian , Axelsson Anna-Karin , Valant Matjaz , Lukasiewicz Tadeusz , Dec Jan , Berenov Andrey , Alford Neil McN.
Published: June 2014

The electrocaloric effect (ECE) of SrxBa(1−x)Nb2O6 (SBN100x) single crystals, with a tetragonal tungsten bronze structure and a high ECE near room temperature, is studied by direct measurements. It is shown that although the onset of the ECE peak is closer to room temperature in SBN80 than in SBN75, the effect of the increase of the strontium content is very detrimental to the ECE performances with a decrease to ΔTEC = 0.23 K for SBN80 from the reported value of ΔTEC = 0.42 K under 10 kV/cm for SBN75 [F. Le Goupil et al., “Anisotropy of the electrocaloric effect in lead-free relaxor ferroelectrics,” Adv. Energy Mater. (published online)]. However, when 1.40% of cerium is introduced in SBN61, the temperature of depolarisation is shifted below 30 °C, while an ECE above 0.6 K is maintained over more than 70 K for a low electric field of 28 kV/cm. The maximum ECE ΔTEC = 0.85 K is measured at 61 °C. In addition to having an ECE peak close to room temperature, the ECE measured in Ce-doped SBN61 is comparable with the best reported values for lead-free materials [Y. Bai et al., J. Appl. Phys. 110, 094103 (2011); X.-S. Qian et al., Adv. Funct. Mater. 24, 1300 (2014)], when linearly extrapolated to higher electric fields.
Phonon lifetime in SiSn and its suitability for hot-carrier solar cells
Authors: Levard Hugo , Laribi Sana , Guillemoles Jean-François
Published: June 2014

We present a phononic and electronic study of SiSn in the zinc-blende phase. A detailed description of the longitudinal optical (LO) phonon decay in a three-phonon process is presented together with the corresponding lifetime. The necessity to go beyond the zone center phonon approximation in this case is highlighted as it reveals a steep dependence of the lifetime on the initial phonon wavenumber, which differs from usual semiconductors. The electronic band structure is calculated within the GW formalism and shows a small direct band gap. It is shown that the LO-phonon resulting from electron cooling has a lifetime four to eight orders of magnitude above all the known value in semiconductors for this process. We finally show the suitability of SiSn for hot-carrier solar cells, as it is endowed with ultra-slow cooling of hot carriers.
A comparative transport study of Bi2Se3 and Bi2Se3/yttrium iron garnet
Authors: Jiang Zilong , Katmis Ferhat , Tang Chi , Wei Peng , Moodera Jagadeesh S. , Shi Jing
Published: June 2014

Bilayers of 20 quintuple layer Bi2Se3 on 30 nm thick yttrium iron garnet (YIG) have been grown with molecular beam epitaxy in conjunction with pulsed laser deposition. The presence of the ferri-magnetic insulator YIG causes additional scattering to the surface states of the Bi2Se3 topological insulator layer, as indicated by the temperature dependence of the resistivity. From the two-channel analysis of the Hall data, we find that the surface contribution in the bilayer samples is greatly reduced. Furthermore, the weak antilocalization effect from the surface states is clearly suppressed due to the presence of the YIG layer.
The effects of wetting layer on electronic and optical properties of intersubband P-to-S transitions in strained dome-shaped InAs/GaAs quantum dots
Authors: Shahzadeh Mohammadreza , Sabaeian Mohammad
Published: June 2014

The authors report on the impact of wetting layer thickness and quantum dot size on the electronic and optical properties of dome-shaped InAs/GaAs quantum dots (QDs) with strained potential. Two wetting layer thicknesses of 0.5 and 2.0 nm were compared. A strong size dependence of P-to-S transition energy, transition dipole moment, oscillator strength, and linear and third-order nonlinear susceptibilities were concluded. The P-to-S transition dipole moment was shown to be purely in-plane polarization. The linear and nonlinear absorption and dispersion showed a red shift when the wetting layer thickness was increased. Our results revealed that the nonlinear susceptibility is much more sensitive to QD size compared to the linear susceptibility. An interpretation of the results was presented based on the probability density of finding the electron inside the dot and wetting layer. The results are in good agreement with previously reported experimental data.
Frame Divergence in Climate Change Adaptation Policy: Insights from Australian Local Government Planning
Authors: Fünfgeld Hartmut , McEvoy Darryn
Published: June 2014

Complex policy issues such as climate change adaptation can be interpreted in many different ways, resulting in different assumptions about their purpose and goals. Using material from a qualitative study in the Australian local government sector, this research shows that stakeholders involved in local adaptation policy formulation often do not have a shared view about the meaning and purposes of adaptation, although such shared understanding is commonly assumed in adaptation processes. Drawing on the frame-research literature and current conceptualisations of climate change adaptation, we argue that subconscious frame divergence can present a major challenge for effective organisational-level adaptation. Conversely, making frames and framing processes explicit is a first step towards clarifying adaptation goals and generating shared ownership of adaptation processes. While frames have been shown to be intrinsically subjective, we discuss three dominant frames that emerged from the study: avoiding disasters, community resilience, and averting organisational risk. We evaluate these in light of their theoretical origin and recent application towards climate change adaptation. Our research suggest that the ‘averting organisational risks' frame is by far the most commonly activated frame. Individuals working in the community services sector frequently referred to the ‘community resilience’ frame, while the ‘avoiding disasters frame’ was used in public and policy discourse to circumvent the arguments of those sceptical about the existence and causes of climate change. We suggest that, by incorporating frame reflexivity into existing adaptation planning processes, a more diverse range of policy options can be explored, delivering more effective adaptation policies.
Keeping Our Eyes on the Eyes: The Case of Arcimboldo
Authors: Bubic Andreja , Susac Ana , Palmovic Marijan
Published: June 2014

While contemporaries often viewed his reversible composite heads as scherzi (jokes) and modern art connoisseurs as creative masterpieces, Giuseppe Arcimboldo's ingenious paintings served as inspiring stimuli for the present eye-tracking experiment. One group of participants viewed three chosen paintings in an upright, and another in an upside-down, orientation. We compared how participants viewed three selected areas of interest (AOIs) within the painting when these could, and could not, be identified as a face or distinct facial element (eyes and mouth). The obtained results indicate that the participants fixated the parts of the painting which represent faces more in the upright than in the inverted orientation. Furthermore, in the upright orientation the participants focused more on the upper AOIs (eyes) than the lower AOIs (mouth). This was not the case for the inverted orientation of two paintings. In conclusion, the face inversion effect occurs even in this artistic context, and the gaze often goes where the eyes are.
The Time Course of Contrast Adaptation Measured with a New Method: Detection of Ramped Contrast
Authors: Dong Xue , Engel Stephen A , Bao Min
Published: June 2014

The present study introduces a new method to measure contrast detection thresholds before and after adaptation to contrast. A sinusoidal testing grating increased contrast at a constant rate from an initial subthreshold level. Subjects indicated when the grating was just visible, which terminated its presentation. The stimulus contrast at the time of response was taken as a measure of relative threshold. We used the method to measure the time courses of changes in threshold following adaptation, for several adapting contrasts (9, 19, 29, or 39 dB, ref. 1%) and adapting durations (10, 100, or 1000 s). The buildup and decay of adaptation to contrast was described well by a power function of time. These results agree with previous findings, but are more efficient in terms of subject time. This method promises to be a useful tool for studying the dynamics of adaptation to spatial contrast.
Visual Word Expertise: A Study of Inversion and the Word-Length Effect, with Perceptual Transforms
Authors: Björnström Laura Eklinder , Hills Charlotte , Hanif Hashim , Barton Jason J S
Published: June 2014

The word-length effect may indicate whether reading is proceeding in an efficient whole-word fashion or by serial letter processing. If it is an index of an orientation-dependent expert reading mechanism, then it should show an inversion effect, with a large difference between upright and upside-down text that is specific for normally configured text. We measured response time of healthy subjects reading 3- to 9-letter words presented in normal configuration, in mirror reflection or spelt backward, in either upright or inverted orientation. The word-length effect showed an inversion effect specific for normal text, as it was not seen for either backward or mirrored text, a result that differed from that for simple mean response times. Also, the word-length effect was smaller for backward than for mirrored text, suggesting that reading of transformed text uses primarily local letters rather than global word forms. We conclude that the word-length effect is a suitable index of expert reading, and reveals that reading under perceptually difficult conditions relies on a sublexical letter-based strategy.
[18F]Fluorination Optimisation and the Fully Automated Production of [18F]MEL050 Using a Microfluidic System
Authors: Matesic Lidia , Kallinen Annukka , Wyatt Naomi A. , Pham Tien Q. , Greguric Ivan , Pascali Giancarlo
Published: June 2014

The [18F]radiolabelling of the melanin-targeting positron-emission tomography radiotracer [18F]MEL050 was rapidly optimised using a commercial continuous-flow microfluidic system. The optimal [18F]fluorination incorporation conditions were then translated to production-scale experiments (35–150 GBq) suitable for preclinical imaging, complete with automated HPLC–solid phase extraction purification and formulation. [18F]MEL050 was obtained in 43 ± 10 % radiochemical yield in ~50 min.
The degradation of arsenoribosides from Ecklonia radiata tissues decomposed in natural and microbially manipulated microcosms
Authors: Duncan Elliott G. , Maher William A. , Foster Simon D. , Krikowa Frank , Mikac Katarina M.
Published: June 2014

Environmental context
Arsenoribosides are the major arsenic species in marine macro-algae, yet inorganic arsenic is the major arsenic species found in seawater. We investigated the degradation of arsenoribosides associated with Ecklonia radiata by the use of microcosms containing both natural and autoclaved seawater and sand. The decomposition and persistence of arsenic species was linked to the use of autoclaved seawater and sand, which suggests that arsenoriboside degradation is governed by the microbial composition of microenvironments within marine systems.

Abstract
We investigated the influence of microbial communities on the degradation of arsenoribosides from E. radiata tissues decomposing in sand and seawater-based microcosms. During the first 30 days, arsenic was released from decomposing E. radiata tissues into seawater and sand porewaters in all microcosms. In microcosms containing autoclaved seawater and autoclaved sand, arsenic was shown to persist in soluble forms at concentrations (9–18µg per microcosm) far higher than those present initially (~3µg per microcosm). Arsenoribosides were lost from decomposing E. radiata tissues in all microcosms with previously established arsenoriboside degradation products, such as thio-arsenic species, dimethylarsinoylethanol (DMAE), dimethylarsenate (DMA) and arsenate (AsV) observed in all microcosms. DMAE and DMA persisted in the seawater and sand porewaters of microcosms containing autoclaved seawater and autoclaved sand. This suggests that the degradation step from arsenoribosides → DMAE occurs on algal surfaces, whereas the step from DMAE → AsV occurs predominantly in the water-column or sand–sediments. This study also demonstrates that disruptions to microbial connectivity (defined as the ability of microbes to recolonise vacant habitats) result in alterations to arsenic cycling. Thus, the re-cycling of arsenoribosides released from marine macro-algae is driven by microbial complexity plus microbial connectivity rather than species diversity as such, as previously assumed.
TM6SF2 is a regulator of liver fat metabolism influencing triglyceride secretion and hepatic lipid droplet content
Authors: Mahdessian Hovsep , Taxiarchis Apostolos , Popov Sergej , Silveira Angela , Franco-Cereceda Anders , Hamsten Anders , Eriksson Per , van't Hooft Ferdinand
Published: June 2014

Significance

Genome-wide association studies have uncovered a genetic locus in chromosome 19 associated with the plasma triglyceride (TG) concentration, a risk factor for coronary heart disease. The identity and functional role of the gene responsible for this association is unknown. Gene expression analysis of 206 human liver samples led to the identification of transmembrane 6 superfamily member 2 (
TM6SF2
), a gene with hitherto unknown function, as the putative causal gene. Functional studies in human liver cells demonstrated that inhibition of
TM6SF2
was associated with reduced secretion of TG-rich lipoproteins (TRLs) and increased cellular TG concentration, while
TM6SF2
overexpression reduced cellular TG concentration. We conclude that TM6SF2 is a novel regulator of liver fat metabolism with opposing effects on the secretion of TRLs and hepatic TG content.
Sexual Segregation of Spiny Dogfish in Fishery‐Dependent Surveys in Cape Cod, Massachusetts: Potential Management Benefits
Authors: Dell'Apa Andrea , Cudney‐Burch Jennifer , Kimmel David G. , Rulifson Roger A.
Published: June 2014

Commercial gill‐net and longline surveys were conducted in the Cape Cod, Massachusetts, area to assess whether the proportion of male Spiny Dogfish Squalus acanthias in the catch changes throughout a normal fishing day (an event frequently observed by local commercial longliners) and to identify the associated potential benefits for fishery management in the study area. Sex ratio changes were examined with respect to location (north and south of 42°N), environment (depth, surface and bottom temperatures, and salinity) and fishing (type of gear and time of activity). Spiny Dogfish showed differences in sex ratios (the proportion of males in the catch [PM]) that were related to location and type of fishing gear as well as to depth and time. Higher numbers of fish were caught with longlines, and higher numbers of males were caught in the southern area in inshore shallower waters early in the day. In the northern area, the sex distribution found within sets indicated a higher presence of females and a lower presence of males in shallower inshore waters. Changes in environmental parameters (depth and bottom temperature) were correlated with PM only in the south. A consistent seasonal (summer and early fall) diurnal shift in the sex ratio was found within 10 mi (16.1 km) of the east coast of the Cape Cod peninsula. This shift suggests that the implementation of a seasonal, male‐only directed longline fishery be considered for this location. Such a fishery would enhance the sustainability of the U.S. Atlantic Spiny Dogfish stock by reducing fishing pressure on adult females. The sex ratios observed suggest that sexual segregation in Spiny Dogfish in the Cape Cod area corresponds to female avoidance of males coupled with specific mating and/or feeding behavior by males.

Received March 19, 2013; accepted November 20, 2013
A Field Test of Eugenol‐Based Anesthesia versus Fish Restraint in Migrating Adult Chinook Salmon and Steelhead
Authors: Caudill Christopher C. , Jepson Michael A. , Lee Steven R. , Dick Travis L. , Naughton George P. , Keefer Matthew L.
Published: June 2014

Many studies require the collection and handling of fish, which may have short‐ and long‐term effects on their behavior and survival. We evaluated the effects of AQUI‐S 20E, a eugenol‐based anesthetic, on adult spring Chinook Salmon Oncorhynchus tshawytscha and winter steelhead O. mykiss in the Willamette River, Oregon. We experimentally compared the postrelease behaviors and movement into spawning tributaries of fish radio‐tagged under anesthesia with those of fish radio‐tagged while being manually held in a restraint device. Anesthetized Chinook Salmon were less likely than restrained Chinook Salmon to swim downstream (20% versus 47%), more likely to reascend the fishway at which they were collected (89% versus 60%), and more likely to escape to tributaries (82% versus 47%). The treatment effect persisted after statistically controlling for tag date, release time, and fish size. In contrast to Chinook Salmon, the percentages of anesthetized and restrained steelhead that moved downstream (17%), passed the dam (88–90%), and escaped to tributaries (79–83%) did not differ by handling treatment. Our results highlight that the effects of handling and tagging need to be evaluated, that such effects may be species specific and occur at multiple scales, and that eugenol‐based anesthetic should be used instead of restraining devices for Chinook Salmon.

Received July 8, 2013; accepted January 29, 2014
Lipid and Moisture Content Modeling of Amphidromous Dolly Varden Using Bioelectrical Impedance Analysis
Authors: Stolarski J. T. , Margraf F. J. , Carlson J. G. , Sutton T. M.
Published: June 2014

The physiological well-being or condition of fish is most commonly estimated from aspects of individual morphology. However, these metrics may be only weakly correlated with nutritional reserves stored as lipid, the primary form of accumulated energy in fish. We constructed and evaluated bioelectrical impedance analysis (BIA) models as an alternative method of assessing condition in amphidromous Dolly Varden Salvelinus malma collected from nearshore estuarine and lotic habitats of the Alaskan Arctic. Data on electrical resistance and reactance were collected from the lateral and ventral surfaces of 192 fish, and whole-body percent lipid and moisture content were determined using standard laboratory methods. Significant inverse relationships between temperature and resistance and reactance prompted the standardization of these data to a constant temperature using corrective equations developed herein. No significant differences in resistance or reactance were detected among spawning and nonspawning females after accounting for covariates, suggesting that electrical pathways do not intersect the gonads. Best-fit BIA models incorporating electrical variables calculated from the lateral and ventral surfaces produced the strongest associations between observed and model-predicted estimates of proximate content. These models explained between 6% and 20% more of the variability in laboratory-derived estimates of proximate content than models developed from single-surface BIA data and 32% more than models containing only length and weight data. While additional research is required to address the potential effects of methodological variation, bioelectrical impedance analysis shows promise as a way to provide high-quality, minimally invasive estimates of Dolly Varden lipid or moisture content in the field with only small increases in handling time.

Received June 17, 2013; accepted December 3, 2013