bluuebunny/crossref_metadata_2025 huggingface dataset:
Kramers turnover: From energy diffusion to spatial diffusion using metadynamics
Authors: Tiwary Pratyush , Berne B. J.
Published: April 2016

We consider the rate of transition for a particle between two metastable states coupled to a thermal environment for various magnitudes of the coupling strength using the recently proposed infrequent metadynamics approach [P. Tiwary and M. Parrinello, Phys. Rev. Lett. 111, 230602 (2013)]. We are interested in understanding how this approach for obtaining rate constants performs as the dynamics regime changes from energy diffusion to spatial diffusion. Reassuringly, we find that the approach works remarkably well for various coupling strengths in the strong coupling regime, and to some extent even in the weak coupling regime.
The effect of target materials on colliding laser-produced plasmas
Authors: Li Xingwen , Yang Zefeng , Wu Jian , Han Jiaxun , Wei Wenfu , Jia Shenli , Qiu Aici
Published: April 2016

In laser ablation, nanosecond to femtosecond lasers with a wide range of laser power densities are used. During ablation, the result of collisions between two plasmas is of interest to many researchers in inertial confinement fusion and nuclear astrophysics. In this paper, the collisions of two seed plasmas ablated from planar target surfaces of different target materials (Al, Cu, and W) were studied with temporal-spatially resolved imaging and spectroscopy. The initial relative velocities and densities of the seed plasmas were measured, and then the collisional parameters were calculated to evaluate the degree of the collisions. In addition, spatially resolved spectra were analyzed to study the influences of materials on the temporal-spatial distribution of atom or ions. The results indicated that under the same laser intensity, the high atomic number (Z) material had a small value of collisionality parameter, mostly because of its heavy ion mass. Higher laser intensity would increase the initial relative velocity of seed plasmas, resulting in a lower collision frequency. In addition, the distribution of the ions from seed plasmas was influenced by the stagnation layer plasmas.
Perspective: How good is DFT for water?
Authors: Gillan Michael J. , Alfè Dario , Michaelides Angelos
Published: April 2016

Kohn-Sham density functional theory (DFT) has become established as an indispensable tool for investigating aqueous systems of all kinds, including those important in chemistry, surface science, biology, and the earth sciences. Nevertheless, many widely used approximations for the exchange-correlation (XC) functional describe the properties of pure water systems with an accuracy that is not fully satisfactory. The explicit inclusion of dispersion interactions generally improves the description, but there remain large disagreements between the predictions of different dispersion-inclusive methods. We present here a review of DFT work on water clusters, ice structures, and liquid water, with the aim of elucidating how the strengths and weaknesses of different XC approximations manifest themselves across this variety of water systems. Our review highlights the crucial role of dispersion in describing the delicate balance between compact and extended structures of many different water systems, including the liquid. By referring to a wide range of published work, we argue that the correct description of exchange-overlap interactions is also extremely important, so that the choice of semi-local or hybrid functional employed in dispersion-inclusive methods is crucial. The origins and consequences of beyond-2-body errors of approximate XC functionals are noted, and we also discuss the substantial differences between different representations of dispersion. We propose a simple numerical scoring system that rates the performance of different XC functionals in describing water systems, and we suggest possible future developments.
Bending and buckling of wet paper
Authors: Lee Minhee , Kim Seungho , Kim Ho-Young , Mahadevan L.
Published: April 2016

Flat paper stained with water buckles and wrinkles as it swells and deforms out of the original plane. Here we quantify the geometry and mechanics of a strip of paper that swells when it imbibes water from a narrow capillary. Characterizing the hygroexpansive nature of paper shows that thickness-wise swelling is much faster than in-plane water imbibition, leading to a simple picture for the process by which the strip of paper bends out of the plane. We model the out-of-plane deformation using a quasi-static theory and show that our results are consistent with quantitative experiments.
Premixed flame propagation in vertical tubes
Authors: Kazakov Kirill A.
Published: April 2016

Analytical treatment of the premixed flame propagation in vertical tubes with smooth walls is given. Using the on-shell flame description, equations for a quasi-steady flame with a small but finite front thickness are obtained and solved numerically. It is found that near the limits of inflammability, solutions describing upward flame propagation come in pairs having close propagation speeds and that the effect of gravity is to reverse the burnt gas velocity profile generated by the flame. On the basis of these results, a theory of partial flame propagation driven by a strong gravitational field is developed. A complete explanation is given of the intricate observed behavior of limit flames, including dependence of the inflammability range on the size of the combustion domain, the large distances of partial flame propagation, and the progression of flame extinction. The role of the finite front-thickness effects is discussed in detail. Also, various mechanisms governing flame acceleration in smooth tubes are identified. Acceleration of methane-air flames in open tubes is shown to be a combined effect of the hydrostatic pressure difference produced by the ambient cold air and the difference of dynamic gas pressure at the tube ends. On the other hand, a strong spontaneous acceleration of the fast methane-oxygen flames at the initial stage of their evolution in open-closed tubes is conditioned by metastability of the quasi-steady propagation regimes. An extensive comparison of the obtained results with the experimental data is made.
Correlating optical infrared and electronic properties of low tellurium doped GaSb bulk crystals
Authors: Roodenko K. , Liao P.-K. , Lan D. , Clark K. P. , Fraser E. D. , Vargason K. W. , Kuo J.-M. , Kao Y.-C. , Pinsukanjana P. R.
Published: April 2016

Control over the Te doping concentration is especially challenging in the mass-production of optically transparent, high-resistivity Te-doped GaSb crystals. Driven by the necessity to perform fast, robust, and non-destructive quality control of the Te doping homogeneity of the optically transparent large-diameter GaSb wafers, we correlated electronic and optical infrared properties of Te-doped GaSb crystals. The study was based on the experimental Hall and Fourier-Transform Infrared (FTIR) data collected from over 50 samples of the low-doped n-type material (carrier concentration of 6 × 1016 cm−3 to 7 × 1017 cm−3) and the Te-doped p-type GaSb (4.6 × 1015 cm−3 to 1 × 1016 cm−3). For the n-type GaSb, the analysis of the FTIR data was performed using free carrier absorption model, while for the p-type material, the absorption was modeled using inter-valence band absorption mechanism. Using the correlation between the Hall and the IR data, FTIR maps across the wafers allow a fast and reliable way to estimate carrier concentration profile within the wafer.
A high-power microwave circular polarizer and its application on phase shifter
Authors: Shao Hao , Hu Yongmei , Chang Chao , Guo Letian
Published: April 2016

A high-power waveguide dual circular polarizer was theoretically designed and proof-of-principle was experimentally tested. It consists of two incident rectangular waveguides with a perpendicular H-plane junction, one circular waveguide with a pair of trapezoidal grooves coupled in E-plane at the top, a spherical crown located at the bottom, and an iris at the perpendicular junction of two rectangular waveguides. When wave incidents at one of the two separated rectangular waveguides, it, respectively, generates a left-hand circular polarized wave or a right-hand circular polarized wave in the circular waveguide. By adding a dumbbell-like metal plug driven with a high speed servomotor, a movable short circuit is formed along the circular waveguide to adjust the output RF phase of the rectangular port, realizing a high-speed high-power phase shifter. The C-band high power microwave (HPM) experiments were carried out, and the power capacity of the HPM polarizer and phase shifter was demonstrated to reach gigawatt level.
Development of Compton X-ray spectrometer for high energy resolution single-shot high-flux hard X-ray spectroscopy
Authors: Kojima Sadaoki , Ikenouchi Takahito , Arikawa Yasunobu , Sakata Shohei , Zhang Zhe , Abe Yuki , Nakai Mitsuo , Nishimura Hiroaki , Shiraga Hiroyuki , Ozaki Tetsuo , Miyamoto Shuji , Yamaguchi Masashi , Takemoto Akinori , Fujioka Shinsuke , Azechi Hiroshi
Published: April 2016

Hard X-ray spectroscopy is an essential diagnostics used to understand physical processes that take place in high energy density plasmas produced by intense laser-plasma interactions. A bundle of hard X-ray detectors, of which the responses have different energy thresholds, is used as a conventional single-shot spectrometer for high-flux (>1013 photons/shot) hard X-rays. However, high energy resolution (Δhv/hv < 0.1) is not achievable with a differential energy threshold (DET) X-ray spectrometer because its energy resolution is limited by energy differences between the response thresholds. Experimental demonstration of a Compton X-ray spectrometer has already been performed for obtaining higher energy resolution than that of DET spectrometers. In this paper, we describe design details of the Compton X-ray spectrometer, especially dependence of energy resolution and absolute response on photon-electron converter design and its background reduction scheme, and also its application to the laser-plasma interaction experiment. The developed spectrometer was used for spectroscopy of bremsstrahlung X-rays generated by intense laser-plasma interactions using a 200 μm thickness SiO2 converter. The X-ray spectrum obtained with the Compton X-ray spectrometer is consistent with that obtained with a DET X-ray spectrometer, furthermore higher certainly of a spectral intensity is obtained with the Compton X-ray spectrometer than that with the DET X-ray spectrometer in the photon energy range above 5 MeV.
Collisional effects on interaction potential in complex plasma in presence of magnetic field
Authors: Bezbaruah Pratikshya , Das Nilakshi
Published: April 2016

Interaction potential in complex plasma with streaming ions is derived analytically in presence of ion-neutral collision and magnetic field. The linear dielectric response function obtained describes the behavior of charged micron sized dust particles in strong collisional limit. A new type of repulsive potential is found to be operative among the dust grains apart from the normal Debye–Hückel potential. The amplitude and shielding length involved in the potential are substantially affected by the parameters describing ion cyclotron frequency, collision frequency among ions and neutrals, and ion streaming. It is also observed that the usual mechanism of ion focusing surrounding the grain is inhibited due to collision. As a result, the attractive wake potential structure is destroyed in the ion flow direction. The horizontal interaction involves only Debye–Hückel potential.
Scaling studies of H-mode pedestal characteristics on Experimental Advanced Superconducting Tokamak
Authors: Wang Teng Fei , Zang Qing , Han Xiao Feng , Xiao Shu Mei , Tian Bao Gang , Hu Ai Lan , Zhao Jun Yu
Published: April 2016

The characteristics of high-confinement mode (H-mode) pedestal are examined on the Experimental Advanced Superconducting Tokamak. It is found that they are closely dependent on each other between electron pedestal characteristics and global parameters for all types of edge localized mode (ELM). The scaling of pedestal temperature based on thermal conduction and pedestal pressure width is carried out. Based on pedestal pressure gradient and pedestal density, six pedestal pressure width models are applied to predict the pedestal temperature height of type I ELMy H-mode. Compared to experimental results, the normalized poloidal beta model is more consistent than other models.
On the inward drift of runaway electrons during the plateau phase of runaway current
Authors: Hu Di , Qin Hong
Published: April 2016

The well observed inward drift of current carrying runaway electrons during runaway plateau phase after disruption is studied by considering the phase space dynamic of runaways in a large aspect ratio toroidal system. We consider the case where the toroidal field is unperturbed and the toroidal symmetry of the system is preserved. The balance between the change in canonical angular momentum and the input of mechanical angular momentum in such a system requires runaways to drift horizontally in configuration space for any given change in momentum space. The dynamic of this drift can be obtained by integrating the modified Euler-Lagrange equation over one bounce time. It is then found that runaway electrons will always drift inward as long as they are decelerating. This drift motion is essentially non-linear, since the current is carried by runaways themselves, and any runaway drift relative to the magnetic axis will cause further displacement of the axis itself. A simplified analytical model is constructed to describe such inward drift both in the ideal wall case and no wall case, and the runaway current center displacement as a function of parallel momentum variation is obtained. The time scale of such displacement is estimated by considering effective radiation drag, which shows reasonable agreement with the observed displacement time scale. This indicates that the phase space dynamic studied here plays a major role in the horizontal displacement of runaway electrons during plateau phase.
A model of plasma current through a hole of Rogowski probe including sheath effects
Authors: Furui H. , Ejiri A. , Nagashima Y. , Takase Y. , Sonehara M. , Tsujii N. , Yamaguchi T. , Shinya T. , Togashi H. , Homma H. , Nakamura K. , Takeuchi T. , Yajima S. , Yoshida Y. , Toida K. , Takahashi W. , Yamazaki H.
Published: April 2016

In TST-2 Ohmic discharges, local current is measured using a Rogowski probe by changing the angle between the local magnetic field and the direction of the hole of the Rogowski probe. The angular dependence shows a peak when the direction of the hole is almost parallel to the local magnetic field. The obtained width of the peak was broader than that of the theoretical curve expected from the probe geometry. In order to explain this disagreement, we consider the effect of sheath in the vicinity of the Rogowski probe. A sheath model was constructed and electron orbits were numerically calculated. From the calculation, it was found that the electron orbit is affected by E × B drift due to the sheath electric field. Such orbit causes the broadening of the peak in the angular dependence and the dependence agrees with the experimental results. The dependence of the broadening on various plasma parameters was studied numerically and explained qualitatively by a simplified analytical model.
Droplet formation and growth inside a polymer network: A molecular dynamics simulation study
Authors: Jung Jiyun , Jang Eunseon , Shoaib Mahbubul Alam , Jo Kyubong , Kim Jun Soo
Published: April 2016

We present a molecular dynamics simulation study that focuses on the formation and growth of nanoscale droplets inside polymer networks. Droplet formation and growth are investigated by the liquid-vapor phase separation of a dilute Lennard-Jones (LJ) fluid inside regularly crosslinked, polymer networks with varying mesh sizes. In a polymer network with small mesh sizes, droplet formation can be suppressed, the extent of which is dependent on the attraction strength between the LJ particles. When droplets form in a polymer network with intermediate mesh sizes, subsequent growth is significantly slower when compared with that in bulk without a polymer network. Interestingly, droplet growth beyond the initial nucleation stage occurs by different mechanisms depending on the mesh size: droplets grow mainly by diffusion and coalescence inside polymer networks with large mesh sizes (as observed in bulk), whereas Ostwald ripening becomes a more dominant mechanism for droplet growth for small mesh sizes. The analysis of droplet trajectories clearly reveals the obstruction effect of the polymer network on the movement of growing droplets, which leads to Ostwald ripening of droplets. This study suggests how polymer networks can be used to control the growth of nanoscale droplets.
Micro-structural analysis of local damage introduced in subsurface regions of 4H-SiC wafers during chemo-mechanical polishing
Authors: Sako Hideki , Matsuhata Hirofumi , Sasaki Masayuki , Nagaya Masatake , Kido Takanori , Kawata Kenji , Kato Tomohisa , Senzaki Junji , Kitabatake Makoto , Okumura Hajime
Published: April 2016

The surface morphology and lattice defect structures in the subsurface regions of 4H-SiC wafers introduced during chemo-mechanical polishing (CMP) were studied by scanning electron microscopy and transmission electron microscopy. It is known that local damage consisting of high-density lattice defects is introduced in the wafers during the current CMP, however, optical microscopy showed that the surface was very flat and clean without any presence of surface defects. Specifically, this study focused on the detailed analysis of such lattice defect structures. The high-density lattice defects locally introduced in the subsurface regions consisted of nano-scale surface scratches, high-density basal-plane dislocation loops, Shockley-type stacking faults, and Y-shaped defects. Two types of dislocation loops were introduced near the scratches that were selected for further study: nearly perfect basal-plane dislocations, which were accompanied by narrow stacking faults, and apparent partial basal-plane dislocations, which were accompanied by wide stacking faults. A Y-shaped defect was observed in the local damage along the [112¯0] direction, but not in the local damage along the [1¯100] direction. It was also found that the directions of the Burgers vectors for the basal-plane dislocations clearly depended on the directions of the introduced scratch-like defects.
Orientation control and domain structure analysis of {100}-oriented epitaxial ferroelectric orthorhombic HfO2-based thin films
Authors: Katayama Kiliha , Shimizu Takao , Sakata Osami , Shiraishi Takahisa , Nakamura Shogo , Kiguchi Takanori , Akama Akihiro , Konno Toyohiko J. , Uchida Hiroshi , Funakubo Hiroshi
Published: April 2016

Orientation control of {100}-oriented epitaxial orthorhombic 0.07YO1.5-0.93HfO2 films grown by pulsed laser deposition was investigated. To achieve in-plane lattice matching, indium tin oxide (ITO) and yttria-stabilized zirconia (YSZ) were selected as underlying layers. We obtained (100)- and (001)/(010)-oriented films on ITO and YSZ, respectively. Ferroelastic domain formation was confirmed for both films by X-ray diffraction using the superlattice diffraction that appeared only for the orthorhombic symmetry. The formation of ferroelastic domains is believed to be induced by the tetragonal–orthorhombic phase transition upon cooling the films after deposition. The present results demonstrate that the orientation of HfO2-based ferroelectric films can be controlled in the same manner as that of ferroelectric films composed of conventional perovskite-type material such as Pb(Zr, Ti)O3 and BiFeO3.
Interfacial engineering of solution-processed Ni nanochain-SiOx (x < 2) cermets towards thermodynamically stable, anti-oxidation solar selective absorbers
Authors: Yu Xiaobai , Wang Xiaoxin , Zhang Qinglin , Liu Jifeng
Published: April 2016

Cermet solar thermal selective absorber coatings are an important component of high-efficiency concentrated solar power (CSP) receivers. The oxidation of the metal nanoparticles in cermet solar absorbers is a great challenge for vacuum-free operation. Recently, we have demonstrated that oxidation is kinetically retarded in solution processed, high-optical-performance Ni nanochain-SiOx cermet system compared to conventional Ni-Al2O3 system when annealed in air at 450–600 °C for several hours. However, for long-term, high-temperature applications in CSP systems, thermodynamically stable antioxidation behavior is highly desirable, which requires new mechanisms beyond kinetically reducing the oxidation rate. Towards this goal, in this paper, we demonstrate that pre-operation annealing of Ni nanochain-SiOx cermets at 900 °C in N2 forms the thermodynamically stable orthorhombic phase of NiSi at the Ni/SiOx interfaces, leading to self-terminated oxidation at 550 °C in air due to this interfacial engineering. In contrast, pre-operation annealing at a lower temperature of 750 °C in N2 (as conducted in our previous work) cannot achieve interfacial NiSi formation directly, and further annealing in air at 450–600 °C for >4 h only leads to the formation of the less stable (metastable) hexagonal phase of NiSi. Therefore, the high-temperature pre-operation annealing is critical to form the desirable orthorhombic phase of NiSi at Ni/SiOx interfaces towards thermodynamically stable antioxidation behavior. Remarkably, with this improved interfacial engineering, the oxidation of 80-nm-diameter Ni nanochain-SiOx saturates after annealing at 550 °C in air for 12 h. Additional annealing at 550 °C in air for as long as 20 h (i.e., 32 h air annealing at >550 °C in total) has almost no further impact on the structural or optical properties of the coatings, the latter being very sensitive to any interfacial changes due to the localized surface plasmon resonances of the metal nanostructures. This phenomenon holds true for Ni nanoparticle diameter down to 40 nm in Ni-SiOx system, where the optical response remains stable for 53 h at 550 °C in air. The oxidation vs. time curve also shows saturation behavior deviating from the kinetic Deal-Grove oxidation model. These results strongly suggest a promising approach to thermodynamically stable, anti-oxidation Ni/SiOx cermet absorbers via interfacial engineering.
Efficient thermoelectric energy conversion in Pb0.95Mn0.05Te p-n couple
Authors: Dybko K. , Szot M. , Mycielski A. , Szczerbakow A. , Dziawa P. , Guziewicz M. , Knoff W. , Łusakowska E. , Story T.
Published: April 2016

We demonstrate an efficient energy conversion in a p-n thermoelectric couple built of bulk Pb0.95Mn0.05Te crystals grown by the Bridgman method and heavily doped n-type with Bi (n=1.9×1019cm−3) or p-type with Na (p=2.3×1019cm−3). Substitution of Mn2+ ions for Pb2+ ions at the rock-salt lattice cation sites increases the band gap of Pb1−xMnxTe and decreases the energy separation between the light hole L-band and the heavy hole Σ-band. It results in a large increase of thermoelectric power and improved thermoelectric parameters of p-type Pb1−xMnxTe. Applying the Harman method for samples of various lengths, we experimentally determined the radiation correction factors and found the thermoelectric figure of merit parameter ZT=0.75–0.8 at T=650 K for both n- and p-type materials with good thermoelectric matching of the couple. We report on thermoelectric performance of a p-n thermoelectric couple assembled of these materials and tested over the T=300–670 K temperature region.
Near room temperature magnetodielectric consequence in (Li, Ti) doped NiO ceramic
Authors: Mukherjee S. , Chatterjee S. , Rayaprol S. , Kaushik S. D. , Bhattacharya S. , Jana P. K.
Published: April 2016

In the quest for high-k dielectrics with decent magnetodielectric (MD) response, ball-milled processed (Li, Ti) doped NiO ceramics have been evaluated by various experimental techniques. Magnetic properties in these ceramics manifest with a pronounced anomaly appearing at ∼260 K, suggesting ferrimagnetic phase (related to cluster magnetism) and co-existence with a glassy-like antiferromagnetic phase at ∼7 K. Room temperature neutron diffraction pattern shows the existence of short-range magnetic correlations. In the magnetically ordered state below 250 K, the magnetic structure is found to be phase coexistence of G-type antiferromagnet and ferrimagnet. Impedance spectroscopy measurements over a wide temperature range can be perfectly described with appropriate microstructural model (internal barrier layer capacitor), based on domain and domain boundary relaxations, justifying the enhancement of the dielectric response. The low-temperature (T < 100 K) dielectric relaxation is polaronic in nature, associated with the charge ordering of a mixed valence states of Ti ions (co-existence of Ti3+ and Ti4+). Finally, our investigations in external magnetic fields up to 15 T reveal the occurrence of negative MD effect near room temperature. This intriguing intrinsic feature has been understood by the mechanism of charge-hopping-mediated MD effects.
A firefly optimized fast extreme learning machine based maximum power point tracking for stability analysis of microgrid with two stage photovoltaic generation system
Authors: Satapathy Prachitara , Dhar S. , Dash P. K.
Published: April 2016

This paper proposes a new Firefly optimized Ridge Extreme Learning Machine (RELM-FF) algorithm based maximum power point tracking (MPPT) investigation for stability study of photovoltaic (PV) interactive microgrid dynamics. The proposed MPPT study is effective by managing minimum uncertainty limits, during solar uncertainty conditions (i.e., inconsistent irradiation, partial shading, etc.), compared with conventional techniques. A two stage converter dynamics is considered for the proposed grid interactive PV system. To withstand stability during worst grid operating scenario (both PV side and grid side uncertainty), a robust nonlinear Lyapunov based finite time sliding mode (LFSM) control is proposed for PV-VSC (voltage source converter) system. As the proposed multiple distributed energy resources based microgrid is considered as weak (low short circuit ratio), and PV is considered as an active power source, the Q-V based state variables are used for the dynamic control loop. A small signal stability analysis with the two stage PV converters is presented using the proposed RELM-FF algorithm and LFSM control. The performance evaluation of the microgrid operating with the PV array is demonstrated through various case scenarios, in MATLAB/Script environment. A hardware validation with TMS320C DSK board and embedded MATLAB coder is performed to establish effectiveness of the proposed MPPT algorithm, in real time. The superiority of the proposed MPPT over the conventional techniques is validated by comparing the stability improvement performance in grid interactive PV-VSC microgrid.
Phenomenological scattering-rate model for the simulation of the current density and emission power in mid-infrared quantum cascade lasers
Authors: Kurlov S. S. , Flores Y. V. , Elagin M. , Semtsiv M. P. , Schrottke L. , Grahn H. T. , Tarasov G. G. , Masselink W. T.
Published: April 2016

A phenomenological scattering-rate model introduced for terahertz quantum cascade lasers (QCLs) [Schrottke et al., Semicond. Sci. Technol. 25, 045025 (2010)] is extended to mid-infrared (MIR) QCLs by including the energy dependence of the intersubband scattering rates for energies higher than the longitudinal optical phonon energy. This energy dependence is obtained from a phenomenological fit of the intersubband scattering rates based on published lifetimes of a number of MIR QCLs. In our approach, the total intersubband scattering rate is written as the product of the exchange integral for the squared moduli of the envelope functions and a phenomenological factor that depends only on the transition energy. Using the model to calculate scattering rates and imposing periodical boundary conditions on the current density, we find a good agreement with low-temperature data for current-voltage, power-current, and energy-photon flux characteristics for a QCL emitting at 5.2 μm.
ZrO2 and HfO2 dielectrics on (001) n-InAs with atomic-layer-deposited in situ surface treatment
Authors: Babadi Aein S. , Lind Erik , Wernersson Lars-Erik
Published: April 2016

The electrical properties of ZrO2 and HfO2 gate dielectrics on n-InAs were evaluated. Particularly, an in situ surface treatment method including cyclic nitrogen plasma and trimethylaluminum pulses was used to improve the quality of the high-κ oxides. The quality of the InAs-oxide interface was evaluated with a full equivalent circuit model developed for narrow band gap metal-oxide-semiconductor (MOS) capacitors. Capacitance–voltage (C–V) measurements exhibit a total trap density profile with a minimum of 1 × 1012 cm−2 eV−1 and 4 × 1012 cm−2 eV−1 for ZrO2 and HfO2, respectively, both of which are comparable to the best values reported for high-κ/III-V devices. Our simulations showed that the measured capacitance is to a large extent affected by the border trap response suggesting a very low density of interface traps. Charge trapping in MOS structures was also investigated using the hysteresis in the C–V measurements. The experimental results demonstrated that the magnitude of the hysteresis increases with increase in accumulation voltage, indicating an increase in the charge trapping response.
LIGO detects gravitational waves
Authors: Chang Sung
Published: April 2016

The twin laser interferometers nearly simultaneously received the call of two black holes in the violent final instants of their merger.
The difficult birth of NASA’s Pluto mission
Authors: Neufeld Michael J.
Published: April 2016

A history of the patronage, design, and funding of New Horizons offers a glimpse of how US space-science policy was formulated before and after the turn of the 21st century.
What remote labs can do for you
Authors: de la Torre Luis , Sánchez Juan Pedro , Dormido Sebastián
Published: April 2016

Internet technologies are helping physics teachers provide their students with more lab time and expose them to a wider variety of experiments.
Negative effects of stagnation and drought on benthic invertebrate communities in lowland streams
Authors: García Liliana , Pardo Isabel
Published: April 2016

Streams are extremely vulnerable to water abstraction across the world because of increasing water demand from humans, as well as because precipitation is decreasing in many areas. To determine how water abstraction affects water chemistry, hydromorphological variables and invertebrate assemblages, we conducted an experiment in which we mimicked two levels of disturbance: stagnation and drought. The experiment was performed at two lowland streams in Galicia (north-west Spain), which were similar in physical conditions but differed in trophic status (high v. low P). Samples were taken both before and after manipulation at the upstream control and downstream-disturbed stretches. There was a significant overall effect of water abstraction on both disturbed stretches, but invertebrate assemblages responded differently between streams and within stretches. In the low-P stream, invertebrate densities remained unchanged in the drought stretch but declined in the stagnation stretch relative to the control. At the same time, the high-P stream exhibited a strong loss of diversity in both the stagnation and drought stretches. These results suggest that short-term flow reductions driven by increasing water scarcity and abstraction put benthic communities in lowland streams at risk, and that risk would be greater (in terms of biodiversity loss) in streams that are initially impaired by high-P loading.
Identification of tumorigenic cells and therapeutic targets in pancreatic neuroendocrine tumors
Authors: Krampitz Geoffrey Wayne , George Benson M. , Willingham Stephen B. , Volkmer Jens-Peter , Weiskopf Kipp , Jahchan Nadine , Newman Aaron M. , Sahoo Debashis , Zemek Allison J. , Yanovsky Rebecca L. , Nguyen Julia K. , Schnorr Peter J. , Mazur Pawel K. , Sage Julien , Longacre Teri A. , Visser Brendan C. , Poultsides George A. , Norton Jeffrey A. , Weissman Irving L.
Published: April 2016

Significance

This is the first in-depth profiling of pancreatic neuroendocrine tumors (PanNETs), to our knowledge, that illuminates fundamental biological processes for this class of tumors. Beginning with the index case and confirmed with additional patient tumors, we showed the dependence on paracrine signaling through the hepatocyte growth factor (HGF)/receptor tyrosine kinase MET axis. We created a novel cell line derived from a well-differentiated PanNET with autocrine HGF/MET signaling. We also identified the cell-surface protein CD90 as a marker of the tumor-initiating cell population in PanNETs that allows for prospective isolation of this critical cell population. Finally, we demonstrated the efficacy of anti-CD47 therapy in PanNETs. These findings provide a foundation for developing therapeutic strategies that eliminate tumor-initiating cells in PanNETs and show how deep examination of individual cases can lead to potential therapies.
Hearer-oriented processes of strength assignment
Authors: Boulat Kira
Published: April 2016

This relevance-based account of commitment borrows from studies on epistemic vigilance and focuses on the hearer’s perspective. It suggests that commitment determines the strength of the contextual assumptions derived from utterance interpretation. In this contribution, I distinguish four kinds of commitment: speaker commitment, communicated commitment, attributed commitment and hearer commitment. The last two kinds of commitment are influenced by three main factors which will be considered in turn: linguistic markers, the hearer’s appraisal of the speaker and the salience of the communicated assumption in his cognitive environment. These claims translate into four experimentally testable predictions. This proposal echoes the current debate concerned with epistemic evaluation of information and aims to account for individuals’ commitment in terms of the relative strength of stored assumptions in their cognitive environment.
The evidential and doxastic dimensions of the Basque particle bide
Authors: Korta Kepa , Zubeldia Larraitz
Published: April 2016

Two kinds of meanings are usually associated to the Basque particle bide.1 On
the one hand, it has been taken to point to the indirect nature of the speaker’s
evidence for the truth of the proposition put forward. According to this view, it
would be a sort of inferential particle. On the other hand, bide has been associated
to the expression of a certain degree of belief or certainty on the truth of
the proposition. This double dimension of bide resembles various aspects of
the meaning and use of another Basque particle – omen. The morpho-syntactic
behaviour of these two particles is practically identical, and their semantics
and pragmatics invite a close comparison. Thus, starting from our conclusions
regarding omen, we explore the similarities and differences between both particles.
We find two main differences. First, bide encodes a doxastic dimension that
is absent from the semantic meaning of omen. And, second, bide can be taken
to be an illocutionary force indicator that does not contribute to the proposition
expressed, while omen does contribute to the truth-conditions of the utterance.
Metarepresentation and evidentiality in Spanish tense and mood
Authors: Ahern Aoife K. , Amenós-Pons José , Guijarro-Fuentes Pedro
Published: April 2016

This paper sets forth a theoretical framework in relation to metarepresentation and evidentiality in Spanish, supported by an empirical analysis of tense/mood contrast expressions. More specifically, we describe how metarepresentational and evidential content are expressed and interpreted in if‐conditional and although-concessive clauses. We also report original experimental data from a written, multiple choice interpretation task in L2 Spanish; and from an L1 task in Spanish with a set of conditional and concessive utterances in which indicative and subjunctive moods alternate. Our global results show that the ability to efficiently integrate linguistic and non‐linguistic cues is particularly costly for non‐native speakers. Yet native speakers also reveal, to a different degree, effects suggestive of processing difficulties related to syntax/discourse interface.
Evidentiality and epistemic modality in the rumor/journalistic conditional in Spanish
Authors: Vatrican Axelle
Published: April 2016

The aim of this paper is to explore the functions of the so-called rumor / journalistic conditional in Spanish. In order to do this, I will try to account for the fact that rumor conditionals are epistemic as well as evidential whereas conjecture conditionals in Spanish are epistemic but not evidential, as they convey uncertainty and do not encode the source of information. I will claim that the morphological marker -ría is a modal epistemic operator of possibility in both cases. In a rumor conditional, the epistemic operator quantifies over the illocutionary force of an embedded proposition p (enunciation / truth of the information), which means “maybe the information about p is true”. The situation p is anchored in the present or in the future. In a conjecture conditional, the modal epistemic operator quantifies over the realization of an embedded proposition p (fact), which means “maybe the realization of p is true”. The situation p is anchored in the past.
Between evidentiality and epistemic modality
Authors: Oliveira Teresa
Published: April 2016

This paper aims to present an in-depth description of the synthetic and compound forms of the future and the conditional, as both inferential and reportative markers, drawing a framework for the respective distribution in Portuguese journalistic texts. A corpus analysis shows that different categories (evidentiality, modality, tense, and aspect) contribute to the construction of the values in question, defining different sets of properties for each of the verbal forms, in both inferential and reportative uses. Furthermore, it proves that these same values are particularly sensitive to textual genre: the reportative uses emerge in news reports, while the inferential uses appear more frequently in opinion texts. Ultimately, it illustrates how the use of these forms sheds light on the boundary between epistemic modality and evidentiality, demonstrating that the assertion of the information source is distinct from the assessment of the speaker’s attitude toward his/her statement.
The evolution of the marker comme qui dirait ‘as one would say’ in French
Authors: Gómez-Jordana Sonia
Published: April 2016

The topic of this paper is the evolution of the discourse marker comme qui dirait from Old French to Modern French. At the beginning, the marker has the meaning of a hypothetical comparative si comme l’en diroit / comme + qui + diroit meaning comme si l’on disait ‘as if one said’. In a second stage, the marker becomes a reformulative marker with a meaning similar to c’est-à-dire ‘that is to say’. Finally, in a third stage, it becomes a polyphonic mitigation marker. The diachronic study of comme qui dirait explains its contemporary meaning and reveals its semantic features. In addition, a polyphonic analysis will allow us to understand the role of the speaker and of the enunciators in the enunciation of the marker.
On conditions instantiating tip effects of epistemic and evidential meanings in Bulgarian
Authors: Wiemer Björn , Kampf Veronika
Published: April 2016

The article deals with tip effects between evidential and epistemic components in the meaning potential of evidential markers in Bulgarian, the focus being on sentential adverbs with inferential functions. We justify (and start with) the following assumptions: (i) for any unit we should distinguish its stable semantic meaning from its pragmatic potential which can be favored (or disfavored) by appropriate discourse conditions; (ii) there is a “trade off” between evidential and epistemic meaning components that are related to each other on the basis of mutual or one-sided implicatures; (iii) one-sided implicatures occur with certain hearsay markers whose epistemic implicatures can be captured as Generalized Conversational Implicatures (GCIs). On this basis, we show that (iv) GCIs work also with inferential markers; they can be classified depending on which component (the inferential or the epistemic one) can be downgraded more easily. A crucial factor favoring the inferential meaning is a perceptual basis of the inference. In general, (v) the more complicated the reconstruction of the cognitive (or communicative) basis leading to an inference, the clearer the epistemic function emerges while the evidential function remains in the background, and vice versa. The study is corpus-based and also includes an attempt at classifying micro- and macro-contextual conditions that (dis)favor a highlighting of the evidential function.
Stance as participant structure
Authors: Spronck Stef
Published: April 2016

Jakobson (1957) bases the analysis of mood on a three-part structure that crucially involves two participant variables. Although the definition of evidentiality in Jakobson (1957) differs in some fundamental ways, it also allows for the explication of a participant structure inherent in evidential meanings. In this paper I argue that by exploring the interaction between these participant structures in multiple-perspective constructions and in reported speech, the framework proposed in Jakobson (1957) enables us to systematically examine phenomena that are typically assumed to arise in evidential expressions as pragmatic effects, particularly ‘commitment effects’ and evidential interpretations of modals. I propose that this approach present us with a principled account of stance meanings (Du Bois 2007), more particularly, of the semantic and pragmatic interaction between modal and evidential meanings, based on their semantic structure.
Die causa essentialis-Theorie als Grundlage der Sprachtheorie?
Authors: Tsopurashvili Tamar
Published: April 2016

In the article are discussed the semantic theories of Dietrich of Freiberg and Meister
Eckhart in the comparative way. The both Dominicans are known through their
theory of intellect, but for declamation of this theory they are choosing the certain
model of language and of predication. The aim of the article is to outline the specific
aspect of their semantic theories that are influenced by the modi significanditheory
on the one hand and by the causa-essentialis-theory on the other hand.
The causa-essentialis-theory becomes a part of their philosophy of language in the
sense, that both Dominicans are thinking the parts of the sentence – subject and
predicate – in the ontological terms: both of them are considering the predicate
as a cause, and subject as a caused one. Therefore they understand the semantical
and the ontological entities in the reciprocity. Such an ontologization of semantic
results from the inherence-model of language that is the basis for understanding
of sentences expressing the definition according to Dietrich von Freiberg as well
as Meister Eckhart.
Do collocational frameworks have local grammars?
Authors: Warren Martin , Leung Maggie
Published: April 2016

This study extends the theory of local grammars by making the case that local grammars can also be employed to better and more fully describe the patterns of co-selection found in collocational frameworks (Renouf & Sinclair 1991). The term collocational framework was originally used to describe the co-selection of two grammatical words which frame an intervening lexical word. In the present study a more inclusive definition is adopted and the number of intervening words is not limited. While there have been a small number of studies related to collocational frameworks there has been no attempt so far to see whether it is possible to describe their local grammars. To illustrate the feasibility of identifying the local grammars of collocational frameworks, four collocational frameworks are studied here:any … may,may … any,any … shall, andshall … anyand their local grammars are identified and discussed.
What trajectors reveal about TIME metaphors
Authors: Johansson Falck Marlene
Published: April 2016

This paper is an analysis of trajectors (i.e. located entities) in language about fixed durations of TIME. More specifically, trajectors in instances including the English prepositionsinoron, or their Swedish equivalentsiorpå, are analyzed. On the structure of the inverse Moving Observer/Moving Time metaphors (Lakoff & Johnson 1999) instances such as these should be construed relative to a Moving Observer, and trajectors people that move relative to fixed durations of TIME (as reflected in e.g.when we come to launching the 4th edition in early 1990). My analysis, however, suggests that our understanding of TIME through SPACE is more nuanced than suggested by these metaphors. In this specific context, trajectors are not typically people in motion, but rather events or processes located in, or on, unit of time landmarks. My study emphasizes the need to test the systematicity of the mappings proposed by Conceptual Metaphor Theory.
Building a parallel corpus of German/Swiss German Sign Language train announcements
Authors: Ebling Sarah
Published: April 2016

We present a parallel corpus of German/Swiss German Sign Language train announcements. The corpus is used in a statistical machine translation system that translates from German to Swiss German Sign Language. The output of the translation system is then passed on to an animation system, the result being a sign language avatar representation on a mobile phone. Building the parallel corpus consisted of four steps: translating the written German train announcements into Swiss German Sign Language glosses, signing the announcements in front of a camera on the basis of the gloss transcriptions, notating the signs in the video recordings in a form-based sign language notation system, and adding information about non-manual features. The resulting corpus contains 3,241 sentence pairs, which makes it a large parallel corpus involving sign language.