bluuebunny/crossref_metadata_2025 huggingface dataset:
Omori law for eruption foreshocks and aftershocks
Authors: Schmid A. , Grasso J.‐R.
Published: May 2012

Using the 1973–2009 worldwide catalogs forM≥ 4.8 seismicity andVEI≥ 0 volcano eruptions, we compare the properties of seismic damage patterns contemporary with eruption with the properties of foreshocks and aftershocks of classic tectonic earthquakes. Using superposed epoch analysis, we demonstrated that the seismicity rate after eruption decreases as a power law similar to the Omori law of earthquake aftershocks. We further show that a complete mapping of Omori law of earthquake aftershocks onto eruption aftershocks does exist asRerup(t) = (K0.10β(VEI))/[(t+c)p], volcanic explosivity index (VEI), being an empirical measure that exponentially scales with eruption size.βclose to 0.4 is the value reported for M = 5–6.5 earthquakes from the same catalog. Thepvalues are in the 0.7 range, i.e., robustly smaller than the 0.9–1.0 range for earthquake aftershocks we estimated in the volcanic area.Kvalue for eruptions is 2–10 times smaller than for earthquakes, and it scales with VEI values. All those parameters characterize a slower damage relaxation after eruptions than after earthquakes. When earthquakes' foreshock rates are proposed to be independent of the main shock magnitude, we resolved a strong increase in foreshock rates including an increase of thep′ value of the inverse Omori law prior eruptions with eruption size. These patterns, all emerging from mean field analysis, are evidence of the volcanic eruptions being contemporary with a stochastic brittle damage in the Earth crust. These results suggest a generic damage relaxation within the Earth crust as power law distributed after or before events. The loading and relaxation exponents and the damage rate emerge as being controlled by the loading rate, as reported during lab‐scale experiments. The more impulsive the loading, i.e., km/s for the slip velocity during earthquakes against km/h for dyke propagation, the faster the relaxation (0.9–1.0pvalues for earthquakes' aftershocks against 0.7 for eruptions' aftershocks). Before eruptions, the larger the impending events, the higher thepvalues. All the observations converge toward the amplitude and frequency of the stress step to drive the Omori law parameters as qualitatively reproduced by the rate and state friction law response of brittle crust faults to loading.
Multiphase flow dynamics of pyroclastic density currents during the May 18, 1980 lateral blast of Mount St. Helens
Authors: Esposti Ongaro T. , Clarke A. B. , Voight B. , Neri A. , Widiwijayanti C.
Published: May 2012

The dynamics of the May 18, 1980 lateral blast at Mount St. Helens, Washington (USA), were studied by means of a three‐dimensional multiphase flow model. Numerical simulations describe the blast flow as a high‐velocity pyroclastic density current generated by a rapid expansion (burst phase, lasting less than 20 s) of a pressurized polydisperse mixture of gas and particles and its subsequent gravitational collapse and propagation over a rugged topography. Model results show good agreement with the observed large‐scale behavior of the blast and, in particular, reproduce reasonably well the front advancement velocity and the extent of the inundated area. Detailed analysis of modeled transient and local flow properties supports the view of a blast flow led by a high‐speed front (with velocities between 100 and 170 m/s), with a turbulent head relatively depleted in fine particles, and a trailing, sedimenting body. In valleys and topographic lows, pyroclasts accumulate progressively at the base of the current body after the passage of the head, forming a dense basal flow depleted in fines (less than 5 wt.%) with total particle volume fraction exceeding 10−1 in most of the sampled locations. Blocking and diversion of this basal flow by topographic ridges provides the mechanism for progressive current unloading. On ridges, sedimentation occurs in the flow body just behind the current head, but the sedimenting, basal flow is progressively more dilute and enriched in fine particles (up to 40 wt.% in most of the sampled locations). In the regions of intense sedimentation, topographic blocking triggers the elutriation of fine particles through the rise of convective instabilities. Although the model formulation and the numerical vertical accuracy do not allow the direct simulation of the actual deposit compaction, present results provide a consistent, quantitative model able to interpret the observed stratigraphic sequence.
Venus transit provides viewing and educational opportunities
Authors: Showstack Randy
Published: May 2012

The transit of Venus across the face of the Sun for about 7 hours on 5–6 June is an astronomical spectacle that will not occur again until 2117. To take advantage of the transit, NASA is planning a number of events, including training various instruments on Venus and having several web‐streams about the transit. In addition, NASA has prepared educational materials, is planning events at every NASA field center, and is coordinating and promoting hundreds of other events and activities in more than 140 countries. All told, these outreach activities could reach more than 100 million people, according to NASA.
Simulating a bubbly ocean
Authors: Balcerak Ernie
Published: May 2012

Bubbles, which form on the ocean surface when waves break, are an important part of air‐sea gas transfer. They also affect the optical and acoustical properties of the near‐surface ocean. Observations of oceanic bubbles are limited, and scientists do not yet fully understand subsurface bubble evolution and the role of bubbles in ocean dynamics as well as air‐sea gas transfer. Liang et al., building on their previous study of bubbles in the ocean, used a multisize, multicomponent bubble model embedded in a large‐eddy simulation model for turbulent oceanic boundary flows to study how bubbles evolve in the ocean after they form, what determines the subsurface bubble distribution, how bubbles affect boundary layer turbulence, and what the subsurface bubble distribution means for bubble‐mediated gas transfer. They found that bubbles dissolve while being carried by turbulent flows, and the mean subsurface bubble distribution can be quantified using wind speed and sea state. The model could help improve understanding of bubbles' role in air‐sea gas exchange. (Journal of Geophysical Research‐Oceans, doi:10.1029/2011JC007766, 2012)
Inverted thermocline, circulation patterns found in Lake Erie
Authors: Schultz Colin
Published: May 2012

A series of high‐resolution measurements has shown that Lake Erie, one of the North American Great Lakes, is backward in some respects. In the majority of thermally stratified lakes, the thermocline, a thin subsurface layer of rapid temperature change, is deeper near the coast than near the center of the lake. Lake Erie, however, has an inverted thermocline, which is deeper offshore than along the coast. Beletsky et al. first mapped this bowl‐shaped thermocline during the summer of 2005 with a large network of temperature sensors.
In the Greek isles a volcano has awakened
Authors: Schultz Colin
Published: May 2012

In 1650 B.C.E. a series of massive volcanic eruptions decimated the ancient seafaring Minoan civilization. Over the next 4 millennia, the largely subaquatic Santorini caldera had a series of smaller eruptions, with five such events within the past 600 years, ending most recently in 1950. From the air the Santorini caldera appears as a small cluster within the larger collection of Greek islands in the southern Aegean Sea. Following a 60‐year lull, Santorini woke up on 9 January 2011 with a swarm of low‐magnitude earthquakes.
Imaging hyporheic exchange
Authors: Balcerak Ernie
Published: May 2012

The dynamics of flow through the subterranean area at the base and along the sides of streambeds, known as the hyporheic zone, affect stream ecosystem dynamics, but researchers do not have a solid understanding of what controls the amount of hyporheic exchange.Ward et al. injected tracers into a stream in the H.J. Andrews Experimental Forest in Oregon and used electrical resistivity imaging to quantify the shape and size of the hyporheic zone. Repeated experiments quantify changes from spring high to summer low flows in the stream. The researchers studied how valley morphology and hydraulic gradients between the stream and surrounding landscape affected hyporheic exchange. Contrary to their expectations based on commonly accepted conceptual models, the scientists found that increasing hydraulic gradients from catchment to stream did not always lead to smaller hyporheic zones. They conclude that hydraulic gradients were not the dominant control on hyporheic exchange in the setting they studied. (Water Resources Research, doi:10.1029/2011WR011461, 2012)
Implications of the equipotential field line approximation for equatorial spread F analysis
Authors: Aveiro H. C. , Hysell D. L.
Published: May 2012

Three different approaches to the evaluation of the electrostatic potential in the ionosphere under equatorial spread F(ESF) conditions are considered. First, we calculate the potential using an analytical approach, applying force balance laws to a simplified ionosphere. Second, we compute the potential around a cylinder‐like plasma depletion in an idealized ionosphere using both the equipotential field line (EFL) approach and the full 3‐D solution to the electrostatic potential problem. Our third approach involves an initial boundary value simulation in a realistic ionosphere using both EFL and 3‐D potential solutions. The results show that the equipotential field line assumption does not fully capture the 3‐D structure of the ionospheric current system and leads to an underestimation of the growth rate of ESF irregularities in numerical simulations.
Characteristics of a plasma sheath in a magnetic dipole field: Implications to the solar wind interaction with the lunar magnetic anomalies
Authors: Wang X. , Horányi M. , Robertson S.
Published: May 2012

The solar wind interaction with the lunar surface, especially in regions of crustal magnetic anomalies, remains of great interest for in situ plasma measurements. Small‐ scale laboratory experiments cannot reproduce the conditions near the lunar surface, but provide a unique opportunity to identify and examine several of the physical processes. We study plasma interaction with a magnetic dipole field at an insulating surface in order to understand the effect of crustal magnetic anomalies on the solar wind–lunar surface interaction. In our experiments, electrons are magnetized with gyroradii r smaller than distances from the surface d (r < d) but ions remain unmagnetized with r > d. The measured potential distribution shows a non‐monotonic sheath above the surface and variations on the surface along the axis of the dipole field. The surface near the center of the dipole is charged more positively by ions as the electrons are magnetically shielded away. A potential minimum is found in the shielding region between the surface and the bulk plasma due to collisional and magnetic mirror trapping effects. Potential variations on the surface are the result of the inhomogeneity of the dipolar field, showing an enhancement of the electric field at the cusps. Enhanced electric fields in the regions of magnetic anomalies on the lunar surface may enhance the transport of small‐sized charged dust particles, possibly explaining the formation of the lunar swirls.
Equatorial plasma bubble zonal velocity using 630.0 nm airglow observations and plasma drift modeling over Ascension Island
Authors: Chapagain Narayan P. , Taylor Michael J. , Makela Jonathan J. , Duly Timothy M.
Published: May 2012

We present OI (630.0 nm) airglow image data from Ascension Island (geographic: 7.9°S, 14.4°W; dip latitude: 16°S) in the southern Atlantic Ocean taken with the Utah State University all‐sky CCD camera during 20 March to 7 April 1997 in order to study plasma bubbles occurring in the low‐latitude nighttime ionosphere. The initial plasma bubble onset occurs in the early evening hours at ∼19:15–20:00 LST and is followed by eastward propagation with an average speed of ∼90–120 m/s prior to local midnight, rapidly decreasing around the midnight and postmidnight periods. The Ascension results are compared with similar observations from Christmas Island in order to examine the longitudinal variations of EPB development and propagation. The observed EPB velocities from Ascension Island are also compared with the results of a plasma drift model. In a case study during the night of 4–5 April, the velocity reveals unusual latitudinal shear, up to 0.12 m/s/km, with a reversal to westward flow at low latitudes while eastward flow is maintained at higher latitudes. Consequently, the bubble rotates counterclockwise and tilts eastward, significantly away from alignment with the geomagnetic field lines. The westward reversal of the drift motion near the geomagnetic equator is most likely the result of a reversal in the F region dynamo or from a large increase in the altitude of the shear node in the F region plasma drift at the geomagnetic equator.
Active deformation near the Nicoya Peninsula, northwestern Costa Rica, between 1996 and 2010: Interseismic megathrust coupling
Authors: Feng Lujia , Newman Andrew V. , Protti Marino , González Víctor , Jiang Yan , Dixon Timothy H.
Published: May 2012

We use campaign and continuous GPS measurements at 49 sites between 1996 and 2010 to describe the long‐term active deformation in and near the Nicoya Peninsula, northwestern Costa Rica. The observed deformation reveals partial partitioning of the Cocos‐Caribbean oblique convergence into trench‐parallel forearc sliver motion and less oblique thrusting on the subduction interface. The northern Costa Rican forearc translates northwestward as a whole ridge block at 11 ± 1 mm/yr relative to the stable Caribbean. The transition from the forearc to the stable Caribbean occurs in a narrow deforming zone of ∼16 km wide. Subduction thrust earthquakes take 2/3 of the trench‐parallel component of the plate convergence; however, surface deformation caused by interseismic megathrust coupling is primarily trench‐normal. Two fully coupled patches, one located offshore Nicoya centered at ∼15 km depth and the other located inland centered at ∼24 km depth, are identified in Nicoya with the potential to generate an Mw 7.8 1950‐type earthquake. Another fully coupled patch SE of Nicoya coincides with the rupture region of the 1990 Nicoya Gulf earthquake. Interface microearthquakes, non‐volcanic tremor, low‐frequency earthquakes, and transient slow‐slip events generally occur in the intermediately to weakly coupled regions.
Allosteric modulation of caspase 3 through mutagenesis
Authors: Walters Jad , Schipper Joshua L. , Swartz Paul , Mattos Carla , Clark A. Clay
Published: May 2012

A mutation in the allosteric site of the caspase 3 dimer interface of Val266 to histidine abolishes activity of the enzyme, and models predict that the mutation mimics the action of small molecule allosteric inhibitors by preventing formation of the active site. Mutations were coupled to His266 at two sites in the interface, E124A and Y197C. We present results from X-ray crystallography, enzymatic activity and molecular dynamics simulations for seven proteins, consisting of single, double and triple mutants. The results demonstrate that considering allosteric inhibition of caspase 3 as a shift between discrete ‘off-state’ or ‘on-state’ conformations is insufficient. Although His266 is accommodated in the interface, the structural defects are propagated to the active site through a helix on the protein surface. A more comprehensive view of allosteric regulation of caspase 3 requires the representation of an ensemble of inactive states and shows that subtle structural changes lead to the population of the inactive ensemble.
Oleic acid-enhanced transdermal delivery pathways of fluorescent nanoparticles
Authors: Lo Wen , Ghazaryan Ara , Tso Chien-Hsin , Hu Po-Sheng , Chen Wei-Liang , Kuo Tsung-Rong , Lin Sung-Jan , Chen Shean-Jen , Chen Chia-Chun , Dong Chen-Yuan
Published: May 2012

Transdermal delivery of nanocarriers provides an alternative pathway to transport therapeutic agents, alleviating pain, improving compliance of patients, and increasing overall effectiveness of delivery. In this work, enhancement of transdermal delivery of fluorescent nanoparticles and sulforhodamine B with assistance of oleic acid was visualized utilizing multiphoton microscopy (MPM) and analyzed quantitatively using multi-photon excitation-induced fluorescent signals. Results of MPM imaging and MPM intensity-based spatial depth-dependent analysis showed that oleic acid is effective in facilitating transdermal delivery of nanoparticles.
The structural, dielectric, elastic, and piezoelectric properties of KNbO3 from first-principles methods
Authors: Wan L. F. , Nishimatsu T. , Beckman S. P.
Published: May 2012

The elastic and dielectric properties of the four experimentally known phases of KNbO3 (KNO) are investigated by first-principles methods. The atomic structure is reported along with the Born effective charge tensor to reveal the relation between Nb–O bonds hybridization and ferroelectric structural distortion. The dielectric, elastic, and piezoelectric properties of each phase are presented and compared to results in the literature. The computed structures are found to match experiment to an accuracy of approximately 2%. Although there have been very few experimental studies of single crystal KNO, it is found that the elastic parameters computed for orthorhombic KNO agree with the measured values to better than 25%, which is within the anticipated exchange-correlation error; however, the computed piezoelectric coefficient differ from the experimental values by as much as 50%, which suggests that the disagreement may not be solely due to the theoretical approximations.
Structure and growth mechanism of quasi-aligned GaN layer-built nanotowers
Authors: Xiao Hong-Di , Liu Jian-Qiang , Luan Cai-Na , Ji Zi-Wu , Cui Ji-Shi
Published: May 2012

Quasi-aligned GaN layer-built nanotowers on silicon (111) substrates by employing ultrathin Ni catalyst films have been grown at 800 °C in a metal-organic chemical vapor deposition system. The nanotower size and the degree of alignment were found to be highly sensitive to changes in the Ni catalyst film thickness. The several growth stages of nanotowers were examined by microscopic technique, which indicates the variation in surface morphology from Ni islands to hexagonal prismatic GaN particles, and finally to GaN layer-built nanotowers. For the third stage, the growth may be attributed to an asymmetric and step by step copying process.
Time-resolved photoluminescence, positron annihilation, and Al0.23Ga0.77N/GaN heterostructure growth studies on low defect density polar and nonpolar freestanding GaN substrates grown by hydride vapor phase epitaxy
Authors: Chichibu S. F. , Hazu K. , Ishikawa Y. , Tashiro M. , Namita H. , Nagao S. , Fujito K. , Uedono A.
Published: May 2012

Time-resolved photoluminescence (TRPL) and positron annihilation measurements, as well as Al0.23Ga0.77N/GaN heterostructure growth by metalorganic vapor phase epitaxy were carried out on very low defect density, polar c-plane and nonpolar m-plane freestanding GaN (FS-GaN) substrates grown by hydride vapor phase epitaxy. Room-temperature photoluminescence (PL) lifetime for the near-band-edge (NBE) excitonic emission of the FS-GaN substrates increases with increasing positron diffusion length (L+); i.e., decreasing gross concentration of charged and neutral point defects and complexes. The best undoped c-plane FS-GaN exhibits record-long L+ being 116 nm. The fast component of the PL lifetime for its NBE emission increases with temperature rise up to 100 K and levels off at approximately 1.1 ns. The result implies a saturation in thermal activation of nonradiative recombination centers. The surface and interface roughnesses for a Si-doped Al0.23Ga0.77N/GaN/Al0.18Ga0.82N/GaN heterostructure are improved by the use of FS-GaN substrates, in comparison with the structure fabricated on a standard GaN template. The emission signals related to the recombination of a two-dimensional electron gas and excited holes are recognized for an Al0.23Ga0.77N/GaN single heterostructure grown on the c-plane FS-GaN substrate.
Magnetization and magnetostriction of Terfenol-D near spin reorientation boundary
Authors: Wang Ben L. , Jin Yongmei M.
Published: May 2012

Magnetization and magnetostriction behaviors of quasi-binary TbxDy1−xFe2 alloys (Terfenol-D) near spin reorientation boundary (SRB) between 〈111〉 and 〈100〉 easy axes are studied by computer simulation of magnetic domain rotations under increasing magnetic field and compressive stress along [112] growth direction. The simulation results reveal coexistence of 〈111〉 and 〈100〉 domains near SRB and show that the switching field first decreases then increases when crossing the SRB from the 〈100〉 region into the 〈111〉 region of the quasi-binary phase diagram, while the magnetostriction first increases then saturates, thus providing an optimal combination of large magnetostriction and low switching field near the SRB as desired for actuator application. This finding has general implications for other magnetostrictive quasi-binary alloys that also exhibit spin reorientation phenomenon, allowing material design for improved magnetostrictive property near SRB, in analogy to morphotropic phase boundary ferroelectrics.
Atomic scale observation of phase separation and formation of silicon clusters in Hf higk-κ silicates
Authors: Talbot E. , Roussel M. , Genevois C. , Pareige P. , Khomenkova L. , Portier X. , Gourbilleau F.
Published: May 2012

Hafnium silicate films were fabricated by RF reactive magnetron sputtering technique. Fine microstructural analyses of the films were performed by means of high-resolution transmission electron microscopy and atom probe tomography. A thermal treatment of as-grown homogeneous films leads to a phase separation process. The formation of SiO2 and HfO2 phases as well as pure Si one was revealed. This latter was found to be amorphous Si nanoclusters, distributed uniformly in the film volume. Their mean diameter and density were estimated to be about 2.8 nm and (2.9 ± 0.4) × 1017 Si-ncs/cm3, respectively. The mechanism of the decomposition process was proposed. The obtained results pave the way for future microelectronic and photonic applications of Hf-based high-κ dielectrics with embedded Si nanoclusters.
Influence of Ca-deficiency on the magneto-transport properties in La0.8Ca0.2MnO3 perovskite and estimation of magnetic entropy change
Authors: Khlifi M. , Bejar M. , Dhahri E. , Lachkar P. , Hlil E. K.
Published: May 2012

La0.8Ca0.2 − x□xMnO3 (x = 0.00, 0.10, and 0.20) perovskite was prepared by the conventional solid-state reaction and annealed at 1473 K. X-ray diffraction and scanning electron microscopy shown the existence of a secondary phase attributed to the unreacted Mn3O4 oxide. The magneto transport properties have been investigated based on the temperature dependence of the resistivity ρ(T) measurements under several applied magnetic fields. We note that the La0.8Ca0.2MnO3 (x = 0.00) sample has a classical metal-insulator transition at Tρ. But we have observed that the lacunars samples (x = 0.10 and 0.20) include a metallic and insulator behavior simultaneously below Tρ and the resistivity is dominated by tunneling through the barriers associated with the insulating phase. In other words, the calcium deficiency favors the enhancement of the insulator behavior. The electrical resistivity is fitted with the phenomenological percolation model, which is based on the phase segregation of ferromagnetic metallic clusters and paramagnetic insulating regions. Furthermore, we found that the estimated results are in good agreement with experimental data. Above all, the resistivity dependence on the temperature and magnetic field data is used to deduce the magnetic entropy change. We have found that these magnetic entropy change values are similar to those calculated in our previous work from the magnetic measurements. Finally, we have found an excellent estimation of the magnetic entropy change based on the Landau theory.
Preparation of graphene nanoflakes/polymer composites and their performances for actuation and energy harvesting applications
Authors: Seveyrat L. , Chalkha A. , Guyomar D. , Lebrun L.
Published: May 2012

Composites based on polyurethane (PU) or P(VDF-TrFE-CFE) terpolymer (T30) filled with various amounts of 60-nm thick graphene nanoflakes were prepared. The dielectric properties, including relative permittivity, loss tangent, and conductivity over a broad range of frequencies were presented and discussed according to the percolation theory. The percolation threshold was found to differ for the two systems, respectively, 7.2 and 3.0 vol. % for the PU and the T30 composites. Differential scanning calorimetry demonstrated that there was practically no interaction between the polymeric matrix and the fillers. The increase in permittivity could not be related to this very slight modification of the polymer but rather to the space charges induced by the graphene flakes. Moreover, measurements of the thickness strain under an applied electric field demonstrated a twofold increase of the actuation capability. The optimal value of the M33 electrostriction coefficient was for both systems obtained for a filler content somewhat lower than the percolation threshold. The PU-graphene composite exhibited better performances compared to its T30-graphene counterpart and this was attributed to the good ratio of relative permittivity to the Young modulus in addition to the specific morphology of the used polyurethane. The energy harvesting properties were investigated by monitoring the evolution of the current under a DC electric field and under AC mechanical strain. The T30-graphene composite was found to be the best material for energy harvesting as previously predicted based on its high permittivity.
Improved terahertz quantum cascade laser with variable height barriers
Authors: Matyas Alpar , Chashmahcharagh Reza , Kovacs Istvan , Lugli Paolo , Vijayraghavan Karun , Belkin Mikhail A. , Jirauschek Christian
Published: May 2012

Using an ensemble Monte-Carlo analysis, it is found that relaxing the constraint of identical barrier heights can result in an improved temperature performance. Exploiting this additional design degree of freedom, modified structures with non-uniform barrier heights are developed based on the current record temperature design. For an optimized structure with reduced diagonality, we predict an increase of 31 K for the maximum operating temperature. Furthermore, we develop improved designs with the same oscillator strength as for the reference design. Using a genetic algorithm for optimization, an improvement of the maximum operating temperature by 38 K is obtained. These results aim to show the potential of varying the barrier heigths for the design of high temperature performance terahertz quantum cascade lasers.
High power, continuous wave, room temperature operation of λ ∼ 3.4 μm and λ ∼ 3.55 μm InP-based quantum cascade lasers
Authors: Bandyopadhyay N. , Slivken S. , Bai Y. , Razeghi M.
Published: May 2012

We report two highly strain-balanced InP-based AlInAs/GaInAs quantum cascade lasers emitting near 3.39 and 3.56 μm. A pulsed threshold current density of only 1.1 kA/cm2 has been achieved at room temperature for both lasers with characteristic temperatures (T0) of 166 K and 152 K, respectively. The slope efficiency is also relatively temperature insensitive with characteristic temperatures (T1) of 116 K and 191 K, respectively. Continuous wave powers of 504 mW and 576 mW are obtained at room temperature, respectively. This was accomplished without buried ridge processing.
Magnetization switching of an MgO/Co/Pt layer by in-plane current injection
Authors: Onur Avci Can , Garello Kevin , Mihai Miron Ioan , Gaudin Gilles , Auffret Stéphane , Boulle Olivier , Gambardella Pietro
Published: May 2012

We demonstrate magnetization switching of a perpendicularly magnetized MgO/Co/Pt trilayer by application of an in-plane current and a constant in-plane magnetic field of small amplitude. Switching occurs due to an effective torque generated by spin-orbit coupling intrinsic to the trilayer structure. We investigate the dependence of the critical switching current on the current pulse width, showing that magnetization reversal in the dc limit is assisted by thermal fluctuations.
Tunable magnetoelectric response of dimensionally gradient laminate composites
Authors: Park C.-S. , Avirovik D. , Bichurin M. I. , Petrov V. M. , Priya S.
Published: May 2012

A magnetoelectric (ME) sensor exhibiting wideband behavior as a function of applied magnetic DC bias and frequency was designed by combining the dimensionally gradient piezoelectric layer with Metglas magnetostrictive layers in laminate configuration. The ME coefficient of the band in the DC magnetic range of 52–242 Oe was measured to be 3000 mV/cm Oe under the resonant condition of f = 107 kHz. The wideband in the AC magnetic field frequency range of 41–110 kHz had the ME coefficient in the vicinity of 260 mV/cm Oe under the conditions of HAC = 1 Oe and HDC = 70 Oe. This frequency-dependent ME behavior clearly showed two different states on each side of the resonance peak which could open the possibility of developing new applications such as magnetic field-controlled switches.
Tunable electric properties of PbZrO3 films related to the coexistence of ferroelectricity and antiferroelectricity at room temperature
Authors: Liu Yaoyang , Lu Xiaomei , Jin Yaming , Peng Song , Huang Fengzhen , Kan Yi , Xu Tingting , Min Kangli , Zhu Jinsong
Published: May 2012

Polycrystalline PbZrO3 films with a preferred orientation were fabricated via the metal-organic decomposition method. For heat-treated PbZrO3 films, the P-E hysteresis loops, dielectric spectra, and I-V curves show interesting changes with time, which strongly suggest the coexistence of antiferroelectric and ferroelectric phases at room temperature. Based on the easy transition between these two phases, the electric properties of the films become tunable. A dielectric tunability of about 50.2% below 8.2 V makes it a promising low working-voltage dielectric tunable material, and the significant current change of four orders of magnitude indicates potential application as a voltage-controlled rheostat.
Structural properties of rutile TiO2 nanoparticles accumulated in a model of gastrointestinal epithelium elucidated by micro-beam x-ray absorption fine structure spectroscopy
Authors: Veronesi G. , Brun E. , Fayard B. , Cotte M. , Carrière M.
Published: May 2012

Micro-beam x-ray absorption fine structure spectroscopy was used to investigate rutile TiO2 nanoparticles internalized into gastrointestinal cells during their crossing of a gut model barrier. Nanoparticles diluted in culture medium tend to accumulate in cells after 48 h exposure; however, no spectral differences arise between particles in cellular and in acellular environments, as corroborated by quantitative analysis. This finding establishes that no modification of the lattice properties of the nanoparticles occurs upon interaction with the barrier. These measurements demonstrate the possibility of interrogating nanoparticles in situ within cells, suggesting a way to investigate their fate when incorporated in biological hosts.
Large, uni-directional actuation in dielectric elastomers achieved by fiber stiffening
Authors: Huang Jiangshui , Lu Tongqing , Zhu Jian , Clarke David R. , Suo Zhigang
Published: May 2012

Cylindrical actuators are made with dielectric elastomer sheets stiffened with fibers in the hoop direction. When a voltage is applied through the thickness of the sheets, large actuation strains are achievable in the axial direction, with or without pre-straining and mechanical loading. For example, actuation strains of 35.8% for a cylinder with a prestrain of 40%, and 28.6% for a cylinder without pre-strain have been achieved without any optimization. Furthermore, the actuation strain is independent of the aspect ratio of the cylinder, so that both large strains and large displacements are readily actuated by using long cylinders.
The development of the copula in Child English
Authors: Becker Misha
Published: May 2012

The dissertation summarized here provides an account of the fact that young children acquiring English (around age 2) often produce utterances like (1), in which they omit a form of the copula, be.

(1)I in the kitchen.

Childrens production of forms like (1) is interesting for two main reasons: firstly, utterances like these do not occur in the input (adult English); secondly, childrens omission of the copula conforms to a systematic pattern (it is neither across the board, nor haphazard). In particular, children omit the copula far less frequently in utterances like (2).

(2)Hes a dog.

The difference between the constructions in (1) and (2) can be characterized in terms of the well-known semantic stage-level/individual-level contrast. That is, a location such as in the kitchen denotes a stage-level property of the subject; a predicate such as a dog denotes an individual-level property of the subject. I argue for a syntactic difference between stage- and individual-level predicates: stage-level predicates contain additional functional structure (AspP) that individual-level predicates lack. Cross-linguistic support for this proposal is provided.

As for why children acquiring English omit the copula in main clauses, I link this to the fact that non-finite main clauses are permitted in child English. I define finiteness in terms of a binding relation between an abstract Tense Operator (TOP) (located in CP) and Infl. In certain grammars (among them child English) TOP may bind Asp instead of Infl, if Asp is projected in the particular clause. However, this binding relation does not result in the clause being finite. Since Asp is projected in clauses with stage-level predicates, but not in those with individual-level predicates, it follows that stage-level predicates may occur in non-finite clauses while individual-level predicates occur with a finite clause. Coupled with the hypothesis that an overt copula is finite (in the sample studied here it is inflected over 99% of the time) and an omitted copula indicates non-finiteness, the pattern of copula omission and production in child English is accounted for.
Commitment: The term and the notions
Authors: De Brabanter Philippe , Dendale Patrick
Published: May 2012

This volume brings together thoroughly reworked versions of a selection of papers presented at the conference The Notion of Commitment in Linguistics, held at the University of Antwerp in January 2007. It is the companion volume to a collection of essays in French to be published in Langue Française and devoted to La notion de prise en charge. Commitment is a close counterpart toprise en charge, and two contributors, Celle and Lansari, use it essentially as a translation of the French term. However, commitment and its verbal cognates (to commit NP to and to be committed to) do not cover the exact same range of meanings as prise en charge. For a thorough assessment of the French term, we refer readers to the introduction to the Langue Française volume. In the present article, we focus entirely on commitment.

The term is widely used in at least three major areas of linguistic enquiry:1 studies on illocutionary acts, studies on modality and evidentiality, and the formal modelling of dialogue/argumentation. In spite of its frequent use, the notion has rarely been theorised and has never been the subject of a monograph or a specialised reader. In keeping with this is the fact that none of the many dictionaries and encyclopaedias of linguistics or philosophy that we have consulted devotes a separate entry to it.

Section 1 of this introduction briefly reviews what commitment means in the three fields just mentioned. Now and then, with respect to a particular issue, pointers are given to which articles in this collection have something to say about the issue. In section 2, we take a lexical and syntactic look at the ways in which the contributors to the present volume use the term. In section 3, we outline each of the contributions, with a focus on the role that commitment plays in them.
Tense, modality and commitment in modes of mixed enunciation
Authors: Celle Agnès
Published: May 2012

This paper presents a semantic treatment of the modal uses of the future tense and the conditional in French and a comparison with their English translations. It is argued that the future and the conditional convey the speaker’s commitment and non-commitment respectively, regardless of how information has been obtained and irrespective of whether this information has been verified or not. Commitment and non-commitment are defined as modes of enunciation depending on how the speaker treats and possibly eliminates representations other than her own representation. The modal meaning of the uses under discussion is shown to derive from a mode of mixed enunciation, which either modulates assertion in the case of commitment or suspends it in the case of noncommitment. In English, this difference is not grammaticalised in the verb system. For example, the modal must may be regarded as an equivalent for both the epistemic conditional and the modal future.
Assertoric commitments
Authors: Kissine Mikhail
Published: May 2012

This paper deals with the two kinds of commitment associated with assertive speech acts: the commitment to having justifications for the propositional content and the commitment to the truth of this content. It is argued that the former kind of commitment boils down to the monotonic commitment to the truth of the propositional content, and can be cancelled. The latter, by contrast, is non-monotonic, and is associated with all assertive speech acts, even those containing a reservation marker. These facts can be explained if one (a) endorses the ‘Direct Perception’ view, according to which every piece of communicated information goes, by default, into the hearer’s ‘belief box’; (b) defines the success of assertive speech acts in terms of the possibility to update the common ground with their propositional content.
Explicitness, implicitness and commitment attribution: A cognitive pragmatic approach
Authors: Morency Patrick , Oswald Steve , de Saussure Louis
Published: May 2012

This paper proposes a cognitive-pragmatic alternative to the traditional, speech-acttheoretic, account of the notion of commitment. The perspective adopted here questions the relevance of addressing actual commitment as a speaker category and shifts the focus of the discussion from properties of speaker commitment to processes ofcommitment attribution. Using a relevance-theoretic framework, it will be suggested that inferring commitment in ordinary, cooperative, communication is part of the processes by which hearers derive speaker meaning, and that the degree of reliability that a hearer may expect to attain in attributing commitment to a speaker correlates with the degree of certainty associated to the derivation of explicatures and implicatures from an utterance.
Certamente and sicuramente: Encoding dynamic and discursive aspects of commitment in Italian
Authors: Pietrandrea Paola
Published: May 2012

Commitment should be understood as a dynamic and discursive category. This raises some important questions for the theory of grammar: to what extent do languages encode the dynamic and discursive aspects of commitment? At what level of analysis does this encoding take place? Which markers encode these aspects? In order to answer some of these questions two Italian adverbs expressing strong commitment are analyzed: certamente and sicuramente. Their distribution at the level of macro-syntactic discourse configurations is studied and contrasted. It emerges that the two adverbs select different distributional contexts. Certamente occurs in contexts that reveal its nature as a polyphonic trigger; sicuramente occurs in contexts that reveal its nature as a trigger of a paradigm of strictly internal alternative judgments. The encoding of the more discursive and dynamic aspects of commitment takes place, at least in this case, not at the morphological or at the syntactic level, but at the discourse level. Indeed, it is conveyed by the constructional composition of the lexical meaning of the two adverbs with the meaning of the discourse structures with which they are associated.
All declarative questions are attributive?
Authors: Poschmann Claudia
Published: May 2012

Gunlogson (2007) claims that (i) declaratives used as questions express a propositional commitment just as normal assertions do, but that (ii) this commitment is not attributed to the speaker’s but to the addressee’s commitment-set. Thus, Gunlogson (2007) interprets all declarative questions as “attributive” utterance types involving a commitment-shift from speaker to addressee. By contrast, I will argue that not all declarative questions involve the suggested commitment-shift. I will distinguish two types of declarative questions, (i) echo questions (with declarative sentence type) and (ii) confirmative questions. Whereas echo questions leave the speaker’s commitment-set untouched, confirmative questions involve speaker-commitment. Moreover, echo questions and confirmative questions behave very differently with respect to intonation patterns (rising versus falling), the type of sentence they instantiate and certain meta-linguistic operations.
Logos as the Message from the Gods
Authors: Kirkland Sean D.
Published: May 2012

In the Cratylus, Socrates seems to present the logos essentially as an always already present
yoke binding us to our world. However, this prior and necessary bond does not entail that the world is revealed perfectly and
completely in the terms and structures of our human language. Rather, within this bond, the logos opens up a
distance between being and appearance, insofar as it points to ›what is‹ as the withdrawn possibility
condition for the appearances ordered, gathered and separated according to names. Plato presents the essential ambivalence of
logos not only in Socrates’ elenctic arguments, but also in the etymology of Hermes, where the possession of
language is a cryptic message indicating to humans a divine wisdom. Thus, as essentially the recipient of such a message, as
having been called toward being by the gods, the proper, indeed pious, human response is dialectical question and answer, Socratic
searching and investigating together.
Augustin und die Skepsis
Authors: Kahnert Klaus
Published: May 2012

Skepticism plays an eminent roll in Augustine’s life and thinking. His work Contra Academicos ought to show that scepticism has to be overcome and that truth is cognizable. His early dialog ›Soliloquia‹ is almost ignored in this context; nevertheless particularly this unfinished work tries to define the term ›truth‹ as precisely as possible, but proceeds in a way that seems to characterize its author as Sceptic.
Martinus Anglicus (dictus Bilond?), Tractatus de suppositione. Einleitung und Text von Harald Berger
Authors: Berger Harald
Published: May 2012

L. M. de Rijk supposed in 1982 that two anonymous logical tracts in the Viennese Codex 4698, fol. 18r–27v, may be the work of Martinus Anglicus (14th century) to whom a tract on consequences and one on obligations are ascribed in that codex. The tract on supposition of which the Viennese codex hands down only a fragment of the beginning is contained completely in Hs I 613 of the Stadtbibliothek Mainz, fol. 20vb–21vb. This finding ensures the authorship of Martinus Anglicus and allows to ascribe an Introduction into Logic in some seven parts to him. Martin’s tract on supposition and the more detailed one by Thomas Manlevelt show some resemblances in structure and content, the first being presumably the later one. This paper presents an edition of Martin’s Tractatus de suppositione from the Mainz manuscript and an introduction regarding the author and his work.
The weight of head nouns in noun-modifying constructions in conversational Japanese
Authors: Takara Nobutaka
Published: May 2012

This paper investigates the weight of head nouns in noun-modifying constructions (NMCs) in conversational Japanese. In my data about 70% of head nouns are ‘light’, 20% of the nouns are ‘heavy’, and the remaining is in a ‘gray zone.’ As a close observation of NMCs reveals the issues of two-way light-heavy classification for heads, I establish six parameters according to which I can model the head nouns on a scale from ‘heaviest’ to ‘lightest.’ I argue that in NMCs ‘lighter’ heads are employed instead of ‘heavier’ ones. I also argue that usage of ‘heavy’ heads is further motivated by the factors: (a) pragmatic or referential concerns, and (b) fixed expressions.
A typology of complement insubordination in Dutch
Authors: Verstraete Jean-Christophe , D'Hertefelt Sarah , Van linden An
Published: May 2012

This paper presents an analysis of complement insubordination in Dutch, i.e. structures that are formally marked as subordinate complement clauses but conventionally used as main clauses. We develop a typology of seven distinct construction types (in three semantic domains), none of which have been analyzed in detail before. From a more general perspective, we show that insubordinate constructions provide a fresh perspective on the analysis of modality and evaluation, with semantic parameters that are not found in more typical exponents like modal verbs. In addition, we show that it is difficult to develop a schematic generalization across the different construction types, in spite of their apparent formal similarity as complement structures. We argue that this points to separate developmental trajectories for the different types, with a point of origin in different main-subordinate constructions, and different degrees of conventionalization for the resulting insubordinate constructions.
Epistemic marking in Ika (Arwako)
Authors: Bergqvist Henrik
Published: May 2012

The paper describes epistemic marking in Ika (Arwako-Chibchan, Colombia) and proposes an analysis in terms of a typologically unusual pattern called conjunct/disjunct, which has been attested for a small number of Asian and South American languages. Canonically, conjunct occurs with first person subjects in statements and with second person in questions, as opposed to any other combination of subject and sentence-type, which is disjunct.

The pattern found in Ika both conforms to expectations and, at the same time, contributes to a more nuanced analysis of the functional motivations of the conjunct/disjunct pattern. In Ika, conjunct marking encodes the speaker’s direct access to an event that involves either (or both) of the speech participants. In addition, conjunct/disjunct marking interacts predictably with a second set of epistemic markers that encode asymmetries in the epistemic authority of the speaker and the addressee. The analysis builds on first-hand data but remains tentative, awaiting further investigation.
De pateras o de cómo la embarcación utilizada por la inmigración irregular se convierte en fuente de creación neológica
Authors: Gallardo San Salvador Natividad
Published: May 2012

With this paper we propose to bring the linguistic and cultural reality of the migration phenomenon to the specialized neology within a descriptive, communicative and cognitive context. The vocabulary of migration falls within the framework referred to as the Communicative Theory of Terminology, this is not only because of the terminological units used but also for reasons of function and the fact that this vocabulary can easily be used in informative discourse. We have been able to observe the dynamic nature of this vocabulary and the constant creation of new terms: the birth of new terms, many of which had to survive a period of instability before becoming accepted as correct; the disappearance of a number of terms, words that shortly after gaining acceptance, some not even reaching maturity, fell into disuse of their own accord; and the opposite, terms that regained popularity thanks to their use in high impact news stories in the media: patera.