bluuebunny/crossref_metadata_2025 huggingface dataset:
Mobile Assisted Language Learning in university EFL courses in Japan: developing attitudes and skills for self-regulated learning
Authors: Kondo Mutsumi , Ishikawa Yasushige , Smith Craig , Sakamoto Kishio , Shimomura Hidenori , Wada Norihisa
Published: April 2012

This paper reports a project in which researchers at universities in Japan explored the use of Mobile Assisted Language Learning (MALL) practices by developing a learning module intended to help improve students’ scores on the TOEIC Listening and Reading Tests. MALL practices are currently being developed at universities in Japan because almost all students have mobile phones, many of them have had informal learning experiences with mobile devices, and students are integrating the communication and information gathering capabilities of mobile technology into their own lifestyles. The private nature of mobile phone communication may create barriers when students are asked to use personal mobile phones for school-centered learning activities. In this study a Nintendo DS mobile was used because it was affordable and students were familiar with this device for game playing and learning activities. In addition, because this device does not have the same telephone, messaging, and Internet functions that have made mobile phones an integral part of students’ private lives, a device such as the Nintendo DS may be a neutral mobile platform for the development of MALL activities which could later be adapted and transferred for use on private mobile phones. The primary aim of this study was to discover whether certain MALL practices would foster an advanced form of self-study, self-regulated learning (SRL). In SRL students take responsibility for arousing and sustaining their own motivation in order to make, carry out, and evaluate strategic learning plans. It was concluded that the use of the MALL learning module encouraged study without teacher intervention, i.e., self study, in terms of time spent on learning tasks, levels of satisfaction derived from the tasks, and self-measured achievement. Furthermore, SRL was observed in terms of the specificity of the goals, the customized creation of learning tasks and their in-class applications.
Using a stance corpus to learn about effective authorial stance-taking: a textlinguistic approach
Authors: Chang Peichin
Published: April 2012

Presenting a persuasive authorial stance is a major challenge for second language (L2) writers in writing academic research. Failure to present an effective authorial stance often results in poor evaluation, which compromises a writer's research potential. This study proposes a “textlinguistic” approach to advanced academic writing to complement a typical corpus approach that is oriented toward exploring lexico-grammatical patterns at the sentence level. A web-based stance corpus was developed which allowed the users to study both the linguistic realizations of stance at clause/sentence level and how stance meanings are made at the rhetorical move level. The assumptions the study tested included: (1) whether a textlinguistic approach assists L2 writers to polish their research argument particularly as a result of improved stance deployment, and (2) whether the web-based corpus tool affords a constructivist environment which prompts the learners to infer linguistic patterns to attain deeper understanding. Seven L2 doctoral students in the social sciences were recruited. The results indicate a positive relationship between writing performance and more accurate use of stance. However, the application of higher order cognitive skills (e.g., inferring and verifying) was infrequent in the corpus environment. Instead, the writers used more lower-level cognitive skills (e.g., making sense and exploring) to learn. The participants accessed the integrated “context examples” most frequently to guide their learning, followed by rhetorical “move examples” and clause-based “stance examples”. This suggests that the learning of stance is critically contingent on the surrounding contexts. Overall, the study reveals that effective authorial stance-taking plays a critical role in effective academic argument. To better assist L2 academic writers, incorporating more (con)textual examples in computer corpora tools is recommended.
Development and validation of a Meal Index of dietary Quality (Meal IQ) to assess the dietary quality of school lunches
Authors: Sabinsky Marianne S , Toft Ulla , Andersen Klaus K , Tetens Inge
Published: April 2012

Objective

School lunch programmes are one strategy to promote healthier dietary habits in children, but better evaluation tools for assessing the dietary quality of such programmes are needed. The aim of the present study was to develop and validate a simple index to assess the dietary quality of school lunches for children aged 7–13 years.

Design

A Meal Index of dietary Quality (Meal IQ) was developed to consist of seven components (nutrients and food groups) based on dietary issues for children aged 7–13 years, which were identified in a national dietary survey. The Meal IQ was validated against calculated nutrient contents of school lunches both provided by the school and brought from home.

Setting

At eight public schools from all over Denmark, data were collected on 191 individual lunches brought from home (which is most common in Denmark) and thirty-one lunches provided as part of a school food programme. In addition thirty-two lunches provided at eighteen other public schools were included.

Subjects

A total of 254 school lunches.

Results

A higher Meal IQ score was associated with a higher overall dietary quality, including lower contents of fat, saturated fat and added sugars, higher contents of fibre, various vitamins and minerals, and more fruits, vegetables and fish.

Conclusions

The Meal IQ is a valid and useful evaluation tool for assessing the dietary quality of lunches provided by schools or brought to school from home.
Decreased albedo, e‐folding depth and photolytic OH radical and NO2 production with increasing black carbon content in Arctic snow
Authors: Reay H. J. , France J. L. , King M. D.
Published: April 2012

The contribution of snow photochemistry to snow and atmospheric oxidative capacity is controlled, in part, by snow albedo and e‐folding depths in snow. Albedo ande‐folding depths (and thus snow photochemistry) are a function of black carbon concentration in snow. The paper presented here demonstrates the complicated response of albedo, e‐folding depth (wavelengths 300–600 nm) and depth‐integrated production rates of NO2and OH radicals to increasing black carbon concentration in well‐characterized snowpacks of the Barrow OASIS campaign, Alaska. All snowpacks were reworked layered windpacks and were found to have similar responses to changes in black carbon concentration. The radiative‐transfer calculations demonstrate two light absorption regimes: ice‐dominated and black carbon dominated. The ice‐dominated and black carbon dominated behavior of albedo,e‐folding depth and depth‐integrated production rates with increasing black carbon concentrations are presented. For black carbon concentrations greater than 20 ng g−1 (wavelength range of 300–600 nm), e‐folding depth and depth‐integrated production rate have an inverse power law relationship with black carbon concentration. Doubling the black carbon concentration decreases thee‐folding depth to ∼70% of the initial value and for solar zenith angles greater than 60°, doubling the black carbon concentration decreases depth‐integrated production rates of NO2 and OH to ∼70% and ∼65% of their original values respectively.
Flux calculation using CARIBIC DOAS aircraft measurements: SO2 emission of Norilsk
Authors: Walter D. , Heue K.‐P. , Rauthe‐Schöch A. , Brenninkmeijer C. A. M. , Lamsal L. N. , Krotkov N. A. , Platt U.
Published: April 2012

Based on a case‐study of the nickel smelter in Norilsk (Siberia), the retrieval of trace gas fluxes using airborne remote sensing is discussed. A DOAS system onboard an Airbus 340 detected large amounts of SO2 and NO2 near Norilsk during a regular passenger flight within the CARIBIC project. The remote sensing data were combined with ECMWF wind data to estimate the SO2 output of the Norilsk industrial complex to be around 1 Mt per year, which is in agreement with independent estimates. This value is compared to results using data from satellite remote sensing (GOME, OMI). The validity of the assumptions underlying our estimate is discussed, including the adaptation of this method to other gases and sources like the NO2 emissions of large industries or cities.
Isocyanic acid in a global chemistry transport model: Tropospheric distribution, budget, and identification of regions with potential health impacts
Authors: Young Paul. J. , Emmons Louisa K. , Roberts James M. , Lamarque Jean‐François , Wiedinmyer Christine , Veres Patrick , VandenBoer Trevor C.
Published: April 2012

This study uses a global chemical transport model to estimate the distribution of isocyanic acid (HNCO). HNCO is toxic, and concentrations exceeding 1 ppbv have been suggested to have negative health effects. Based on fire studies, HNCO emissions were scaled to those of hydrogen cyanide (30%), resulting in yearly total emissions of 1.5 Tg for 2008, from both anthropogenic and biomass burning sources. Loss processes included heterogeneous uptake (pH dependent), dry deposition (like formic acid), and reaction with the OH radical (k = 1 × 10−15 molecule−1 cm3 s−1). Annual mean surface HNCO concentrations were highest over parts of China (maximum of 470 pptv), but episodic fire emissions gave much higher levels, exceeding 4 ppbv in tropical Africa and the Amazon, and exceeding 10 ppbv in Southeast Asia and Siberia. This suggests that large biomass burning events could result in deleterious health effects for populations in these regions. For the tropospheric budget, using the model‐calculated pH the HNCO lifetime was 37 days, with the split between dry deposition and heterogeneous loss being 95%:5%. Fixing the heterogeneous loss rate at pH = 7 meant that this process dominated, accounting for ∼70% of the total loss, giving a lifetime of 6 days, and resulting in upper tropospheric concentrations that were essentially zero. However, changing the pH does not notably impact the high concentrations found in biomass burning regions. More observational data is needed to evaluate the model, as well as a better representation of the likely underestimated biofuel emissions, which could mean more populations exposed to elevated HNCO concentrations.
P wave anisotropic tomography of the Nankai subduction zone in Southwest Japan
Authors: Wang Jian , Zhao Dapeng
Published: April 2012

The active subduction of the young Philippine Sea (PHS) plate and the old Pacific plate has resulted in significant seismic heterogeneity and anisotropy in Southwest (SW) Japan. In this work we determined a detailed 3‐D P wave anisotropic tomography of the crust and upper mantle beneath SW Japan using ∼540,000 P wave arrival times from 5,249 local earthquakes recorded by 1095 stations. The PHS slab is imaged clearly as a high‐velocity (high‐V) anomaly which exhibits considerable lateral variations. Significant low‐velocity (low‐V) anomalies are revealed above and below the PHS slab. The low‐V anomalies above the PHS slab may reflect the upwelling flow in the mantle wedge and the PHS slab dehydration, and they form the source zone of the arc volcanoes in SW Japan. The low‐V zones under the PHS slab may reflect the upwelling flow in the big mantle wedge above the Pacific slab. The anisotropy in the crust and upper mantle is complex. In Kyushu, the P wave fast velocity direction (FVD) is generally trench‐normal in the mantle wedge under the back‐arc, which is consistent with the corner flow driven by the PHS slab subduction. The FVD is trench‐parallel in the subducting PHS slab under Kyushu. We think that the intraslab seismicity is a potential indicator to the slab anisotropy. That is, the PHS slab with seismicity has kept its original fossil anisotropy formed at the mid‐ocean ridge, while the aseismic PHS slab has reproduced the anisotropy according to its current deformation.
The natural greenhouse effect of atmospheric oxygen (O2) and nitrogen (N2)
Authors: Höpfner M. , Milz M. , Buehler S. , Orphal J. , Stiller G.
Published: April 2012

The effect of collision‐induced absorption by molecular oxygen (O2) and nitrogen (N2) on the outgoing longwave radiation (OLR) of the Earth's atmosphere has been quantified. We have found that on global average under clear‐sky conditions the OLR is reduced due to O2 by 0.11 Wm−2 and due to N2 by 0.17 Wm−2. Together this amounts to 15% of the OLR‐reduction caused by CH4 at present atmospheric concentrations. Over Antarctica the combined effect of O2 and N2 increases on average to about 38% of CH4 with single values reaching up to 80%. This is explained by less interference of H2O spectral bands on the absorption features of O2 and N2 for dry atmospheric conditions.
Regional climate model applications on sub‐regional scales over the Indian monsoon region: The role of domain size on downscaling uncertainty
Authors: Bhaskaran B. , Ramachandran A. , Jones R. , Moufouma‐Okia W.
Published: April 2012

Regional climate models are becoming increasingly popular to provide high resolution climate change information for impacts assessments to inform adaptation options. Many countries and provinces requiring these assessments are as small as 200,000 km2 in size, significantly smaller than an ideal domain needed for successful applications of one‐way nested regional climate models. Therefore assessments on sub‐regional scales (e.g., river basins) are generally carried out using climate change simulations performed for relatively larger regions. Here we show that the seasonal mean hydrological cycle and the day‐to‐day precipitation variations of a sub‐region within the model domain are sensitive to the domain size, even though the large scale circulation features over the region are largely insensitive. On seasonal timescales, the relatively smaller domains intensify the hydrological cycle by increasing the net transport of moisture into the study region and thereby enhancing the precipitation and local recycling of moisture. On daily timescales, the simulations run over smaller domains produce higher number of moderate precipitation days in the sub‐region relative to the corresponding larger domain simulations. An assessment of daily variations of water vapor and the vertical velocity within the sub‐region indicates that the smaller domains may favor more frequent moderate uplifting and subsequent precipitation in the region. The results remained largely insensitive to the horizontal resolution of the model, indicating the robustness of the domain size influence on the regional model solutions. These domain size dependent precipitation characteristics have the potential to add one more level of uncertainty to the downscaled projections.
Multidimensional epistasis and fitness landscapes in enzyme evolution
Authors: Zhang Wei , Dourado Daniel F. A. R. , Fernandes Pedro Alexandrino , Ramos Maria João , Mannervik Bengt
Published: April 2012

The conventional analysis of enzyme evolution is to regard one single salient feature as a measure of fitness, expressed in a milieu exposing the possible selective advantage at a given time and location. Given that a single protein may serve more than one function, fitness should be assessed in several dimensions. In the present study we have explored individual mutational steps leading to a triple-point-mutated human GST (glutathione transferase) A2-2 displaying enhanced activity with azathioprine. A total of eight alternative substrates were used to monitor the diverse evolutionary trajectories. The epistatic effects of the mutations on catalytic activity were variable in sign and magnitude and depended on the substrate used, showing that epistasis is a multidimensional quality. Evidently, the multidimensional fitness landscape can lead to alternative trajectories resulting in enzymes optimized for features other than the selectable markers relevant at the origin of the evolutionary process. In this manner the evolutionary response is robust and can adapt to changing environmental conditions.
Superconducting phase-dependent force in SNS junctions with mobile scatterers
Authors: Parafilo A. V. , Krive I. V. , Bogachek E. N. , Landman U.
Published: April 2012

We calculate the quantum (Casimir-like) superconducting phase-dependent force acting on mobile scatterers in superconductor–normal metal–superconductor (SNS) junctions. Repulsive Casimir forces are predicted in short SNS junctions with nonequilibrium (inverse) Andreev level populations. An anomalous (nonmonotonic) temperature dependence of the quantum force is found in long SNS junctions.
The influence of standing waves on synchronization and self-heating of Josephson junctions in resonant systems
Authors: Grib Alexander , Seidel Paul
Published: April 2012

We investigated numerically synchronization of Josephson junctions inside the transmission line. We have found that due to the resonance behavior of the system there appear the self-induced resonance steps, strong synchronization of junctions on these steps and the inhomogeneous distribution of the Joule heat extraction (the self heating) along the line which can lead to the formation of “hot spots” in the line. The developed model can be applied to explain recent experiments in which these effects were obtained.
dc Josephson current for d-wave superconductors with charge density waves
Authors: Gabovich A. M. , Voitenko A. I.
Published: April 2012

dc Josephson tunnel current Ic between a dx2−y2-wave superconductor and charge density waves (CDWs)—e.g. a high-Tc oxide and a conventional isotropic superconductor—was considered theoretically. Directionality of tunneling was taken into account. It was found that the dependence of Ic on the angle γ between the direction of the superconducting lobe and the plane normal to the junction is significantly altered by CDWs. For certain doping levels it may be nonmonotonic, as can be readily determined experimentally. For comparison, presented here are the corresponding results obtained for the tunnel junction between CDWs in an s-superconductor and a conventional isotropic superconductor.
Microstructure and magnetocaloric effect of melt-spun Ni52Mn26Ga22 ribbon
Authors: Li Z. B. , Sánchez Llamazares J. L. , Sánchez-Valdés C. F. , Zhang Y. D. , Esling C. , Zhao X. , Zuo L.
Published: April 2012

Microstructural features and magnetocaloric properties of Ni52Mn26Ga22 melt-spun ribbons were studied. Results show that there are four types of differently oriented variants of seven-layered modulated (7M) martensite at room temperature, being twin-related one another and clustered in colonies. Due to the coupled magnetic and structural transformations between parent austenite and 7M martensite, the melt-spun ribbons exhibit a significant magnetocaloric effect. At an applied magnetic field of 5 T, an absolute maximum value of the isothermal magnetic entropy change of 11.4 J kg−1 K−1 is achieved with negligible hysteresis losses.
Electronic polarization effects in the photodissociation of Cl2
Authors: Campbell E. K. , Alekseyev A. B. , Balint-Kurti G. G. , Brouard M. , Brown Alex , Buenker R. J. , Cireasa R. , Gilchrist A. J. , Johnsen A. J. , Kokh D. B. , Lucas S. , Ritchie G. A. D. , Sharples T. R. , Winter B.
Published: April 2012

Velocity mapped ion imaging and resonantly enhanced multiphoton ionization time-of-flight methods have been used to investigate the photodissociation dynamics of the diatomic molecule Cl2 following excitation to the first UV absorption band. The experimental results presented here are compared with high level time dependent wavepacket calculations performed on a set of ab initio potential energy curves [D. B. Kokh, A. B. Alekseyev, and R. J. Buenker, J. Chem. Phys. 120, 11549 (2004)10.1063/1.1753554]. The theoretical calculations provide the first determination of all dynamical information regarding the dissociation of a system of this complexity, including angular momentum polarization. Both low rank K = 1, 2 and high rank K = 3 electronic polarization are predicted to be important for dissociation into both asymptotic product channels and, in general, good agreement is found between the recent theory and the measurements made here, which include the first experimental determination of high rank K = 3 orientation.
Two-dimensional imaging velocity interferometry: Data analysis techniques
Authors: Erskine David J. , Smith R. F. , Bolme C. A. , Celliers P. M. , Collins G. W.
Published: April 2012

We describe data analysis procedures for an emerging interferometric technique for measuring target motion across a two-dimensional image at a moment in time, i.e., a snapshot 2D-VISAR. Conventional VISARs (velocity interferometer system for any reflector) are commonly used in shock physics to measure velocity history at a single point or many points across a line on target. These however are not recorded in two-dimensions and cannot be used with ultrashort pulsed illumination because the coherence length is smaller than the interferometer delay, preventing fringe formation. In our scheme, dual matched interferometers allow use of low- or incoherent illumination such as ultrashort laser pulses to freeze motion of target, allowing use of slow CCD imaging detectors. Quadrature phase recording and push-pull data analysis simultaneously produces an ordinary nonfringing reflectivity image and a fringing image. The latter is converted into a 2D-phase map which is proportional to target velocity. Example data on shocked crystalline [111] Si shows incipient features of ∼50 μm scale.
Fundamentals of ionic conductivity relaxation gained from study of procaine hydrochloride and procainamide hydrochloride at ambient and elevated pressure
Authors: Wojnarowska Z. , Swiety-Pospiech A. , Grzybowska K. , Hawelek L. , Paluch M. , Ngai K. L.
Published: April 2012

The pharmaceuticals, procaine hydrochloride and procainamide hydrochloride, are glass-forming as well as ionically conducting materials. We have made dielectric measurements at ambient and elevated pressures to characterize the dynamics of the ion conductivity relaxation in these pharmaceuticals, and calorimetric measurements for the structural relaxation. Perhaps due to their special chemical and physical structures, novel features are found in the ionic conductivity relaxation of these pharmaceuticals. Data of conductivity relaxation in most ionic conductors when represented by the electric loss modulus usually show a single resolved peak in the electric modulus loss M″(f ) spectra. However, in procaine hydrochloride and procainamide hydrochloride we find in addition another resolved loss peak at higher frequencies over a temperature range spanning across Tg. The situation is analogous to many non-ionic glass-formers showing the presence of the structural α-relaxation together with the Johari-Goldstein (JG) β-relaxation. Naturally the analogy leads us to name the slower and faster processes resolved in procaine hydrochloride and procainamide hydrochloride as the primary α-conductivity relaxation and the secondary β-conductivity relaxation, respectively. The analogy of the β-conductivity relaxation in procaine HCl and procainamide HCl with JG β-relaxation in non-ionic glass-formers goes further by the finding that the β-conductivity is strongly related to the α-conductivity relaxation at temperatures above and below Tg. At elevated pressure but compensated by raising temperature to maintain α-conductivity relaxation time constant, the data show invariance of the ratio between the β- and the α-conductivity relaxation times to changes of thermodynamic condition. This property indicates that the β-conductivity relaxation has fundamental importance and is indispensable as the precursor of the α-conductivity relaxation, analogous to the relation found between the Johari-Goldstein β-relaxation and the structural α-relaxation in non-ionic glass-forming systems. The novel features of the ionic conductivity relaxation are brought out by presenting the measurements in terms of the electric modulus or permittivity. If presented in terms of conductivity, the novel features are lost. This warns against insisting that a log-log plot of conductivity vs. frequency is optimal to reveal and interpret the dynamics of ionic conductors.
Raman scattering and anti-Stokes luminescence in poly-paraphenylene vinylene/carbon nanotubes composites
Authors: Baibarac M. , Massuyeau F. , Wery J. , Baltog I. , Lefrant S.
Published: April 2012

In this paper, we present Raman scattering and luminescence of poly-paraphenylene vinylene/single-walled carbon nanotubes composites, focused on data recorded in the anti-Stokes branch. We demonstrate that, when the excitation energy is in the long wavelength tail of the fundamental absorption edge, an anti-Stokes signal is generated, whose origin is a photon absorption accompanied by a phonon process from lower to upper vibronic states. The efficiency of this anti-Stokes photo-luminescence is increased when composites films are deposited onto an Au rough surface acting as a surface enhanced Raman scattering substrate. This mechanism is explained by a coherent anti-Stokes Raman scattering-like process, as observed in other nano-structured materials.
The photoionization cross section of a hydrogenic impurity in a multi-layered spherical quantum dot
Authors: Şahin Mehmet , Tek Firdes , Erdinç Ahmet
Published: April 2012

In this study, we have investigated the photoionization cross section of an on-center hydrogenic impurity in a multi-layered spherical quantum dot. The electronic energy levels and their wave functions have been determined fully numerically by shooting method. Also, we have calculated the binding energy of the impurity by using these energy values. The photoionization cross section has also been computed as a function of the layer thickness and normalized photon energies. We have discussed in detail the possible physical reasons behind the changes in the binding energies and photoionization cross section. It is observed that both the binding energies and the photoionization cross sections depend strongly on the layer thickness and photon energies.
Unbiased line width roughness measurements with critical dimension scanning electron microscopy and critical dimension atomic force microscopy
Authors: Azarnouche L. , Pargon E. , Menguelti K. , Fouchier M. , Fuard D. , Gouraud P. , Verove C. , Joubert O.
Published: April 2012

With the constant decrease of semiconductor device dimensions, line width roughness (LWR) becomes one of the most important sources of device variability and thus needs to be controlled below 2 nm for the future technological nodes of the semiconductor roadmap. The LWR control at the nanometer scale requires accurate measurements, which are inevitably impacted by the noise level of the equipment that causes bias from true LWR values. In this article, we compare the capability of two metrology tools, the critical dimension scanning electron microscopy (CD-SEM) and critical dimension atomic force microscopy (CD-AFM) to measure the true line width roughness of silicon and photoresist lines. For this purpose, we propose several methods based on previous works to estimate the noise level of those two equipments and thus extract the true LWR. One of the developed methods for the CD-SEM technique generalizes the power spectral densities (PSD) fitting method proposed by Hiraiwa and Nishida with a more universal autocorrelation function, which includes both correlation length and roughness exponent. However, PSD fitting method could not be used with CD-AFM due to the time consuming character of this technique. Hence, other experimental protocols have been set up for CD-AFM in order to accurately characterize the LWR. Our study shows that the CD-SEM technique combined with our PSD fitting method is much more powerful than CD-AFM to get all roughness information (true LWR, correlation length, and roughness exponent) with a good accuracy and efficiency on hard materials such as silicon. Concerning materials degradable under electron beam exposure such as photoresist, the choice is more disputable, since ultimately they are impacted by the electrons. Fortunately, our PSD fitting method allows working with low number of integration frames, which limits the resist degradation. Besides, we have highlighted some limitations of the CD-AFM technique due to the tip diameter. This technique can underestimate LWR if the roughness presents significant amount of high frequency components, as it is the case for photoresist patterns. So far, there is no universal technique to accurately estimate the LWR on any materials. Nevertheless, the CD-SEM protocol we propose opens a way for a better characterization of the photoresist LWR after lithography and a better understanding of the LWR transfer during the plasma etching steps involved in gate patterning processes.
Constructive renormalization for $\Phi ^{4}_2$Φ24 theory with loop vertex expansion
Authors: Rivasseau Vincent , Wang Zhituo
Published: April 2012

In this paper, we construct the two-dimensional Euclidean ϕ4 quantum field theory using the method of loop vertex expansion. We reproduce the results of standard constructive theory, for example, the Borel summability of the Schwinger functions in the coupling constant. Our method should be also suitable for the future construction of Grosse-Wulkenhaar models on non-commutative space-time.
Radial-spin-wave-mode-assisted vortex-core magnetization reversals
Authors: Yoo Myoung-Woo , Lee Jehyun , Kim Sang-Koog
Published: April 2012

The dynamic behaviors of vortex-core magnetization reversals in soft magnetic nanodisks driven by oscillating magnetic fields applied perpendicularly to the disk plane were studied by means of micromagnetic numerical simulations. It was found that when the field frequencies are tuned to the eigenfrequencies of radial spin-wave modes, the threshold field amplitudes required for vortex-core switching are an order of magnitude smaller than those of static perpendicular fields. The reversal mechanism and associated underlying physics are completely different from those of vortex-antivortex-pair-mediated core reversals. The results reflect the achievement of an alternative efficient means of ultrafast vortex-core switching.
Preliminary investigation on the modification of electronic properties in surface passivated SnO2 nanowires with Schottky contacts on being exposed to 137Cs γ-radiation
Authors: Kar Ayan , Ahern Ryan , Gopalsami N. , Raptis A. C. , Stroscio Michael A. , Dutta Mitra
Published: April 2012

This paper demonstrates modification of SnO2 nanowire electronic and surface properties at room temperature on being exposed to γ-radiation. Electrons generated by the high energy photons are captured by oxygen sensitized nanowires and result in a change in the nanowire resistance along with an enhancement in the Schottky barrier thereby modulating current flow across the metal-semiconductor (M-S) junction. The time dependent change in device resistance shows a notably short response time to radiation. Further luminescence and transmission data from the irradiated nanowires indicate a change in the nature and density of surface defects after exposure to highly energetic γ-radiation.
Influence of a TiO2 buffer layer on the magnetic properties of anatase Co:TiO2 thin films
Authors: Gabor M. S. , Petrisor T. , Tiusan C. , Hehn M. , Vasile B. S. , Petrisor T.
Published: April 2012

Our study addresses the influence of a TiO2 buffer layer on the morphological, structural, and magnetic properties of Co:TiO2 films grown on (001) SrTiO3 substrates by RF sputtering. We demonstrate that a direct correlation exist between the morphology, the Co heterogeneity, and the magnetic properties measured in the films. Correlated analysis by cross section transmission electron microscopy, energy dispersive x-ray, and x-ray photoemission spectroscopy reveals that the Co is not uniformly distributed in the film but concentrated in the surface clusters. Atomic force microscopy analysis illustrates that the unbuffered films present a large density of surface clusters. These clusters are not metallic Co but Co rich TiO2 anatase phase and they are accompanied by structural defects in the film: dislocations, small angle grain boundaries. Magnetometry analysis shows that the unbuffered films have a net ferromagnetic behavior, while in the buffered ones the ferromagnetism is quenched. Therefore, we conclude that the magnetism in unbuffered samples is related to the surface clusters and seems to have an extrinsic nature.
Vacuum polarization and magnetization effects in ultra-intense laser pulse-pair plasmas
Authors: Hu Qiang-Lin , Xiao Gui-Lan , Yu Xiao-Guang , Peng Ji-Chang , Wu Ai-Jing
Published: April 2012

The nonlinear effects associated with the vacuum polarization and magnetization in the propagation of ultra-intense linearly polarized laser pulse in electron-positron plasmas are investigated. Using the slowly varying envelope approximation, a modified nonlinear Schrödinger equation describing the evolution of the pulse envelope is derived based on the Maxwell equations which include the vacuum polarization and magnetization effects. The analytical and numerical analysis show that the number density of electron-positron plasmas can enhance the vacuum polarization and magnetization effects, and due to the vacuum polarization and magnetization nonlinearity, a one-dimensional laser pulse envelope soliton can be formed. The evolution of an initially Gaussian laser pulse is also discussed by numerical analysis.
Numerical analysis of moving contact line with contact angle hysteresis using feedback deceleration technique
Authors: Park Jun Kwon , Kang Kwan Hyoung
Published: April 2012

Contact angle (CA) hysteresis is important in many natural and engineering wetting processes, but predicting it numerically is difficult. We developed an algorithm that considers CA hysteresis when analyzing the motion of the contact line (CL). This algorithm employs feedback control of CA which decelerates CL speed to make the CL stationary in the hysteretic range of CA, and one control coefficient should be heuristically determined depending on characteristic time of the simulated system. The algorithm requires embedding only a simple additional routine with little modification of a code which considers the dynamic CA. The method is non-iterative and explicit, and also has less computational load than other algorithms. For a drop hanging on a wire, the proposed algorithm accurately predicts the theoretical equilibrium CA. For the drop impacting on a dry surface, the results of the proposed algorithm agree well with experimental results including the intermittent occurrence of the pinning of CL. The proposed algorithm is as accurate as other algorithms, but faster.
High carrier mobility in transparent Ba1−xLaxSnO3 crystals with a wide band gap
Authors: Luo X. , Oh Y. S. , Sirenko A. , Gao P. , Tyson T. A. , Char K. , Cheong S.-W.
Published: April 2012

We discovered that perovskite (Ba,La)SnO3 can have excellent carrier mobility even though its band gap is large. The Hall mobility of Ba0.98La0.02SnO3 crystals with the n-type carrier concentration of ∼8-10 × 1019 cm−3 is found to be ∼103 cm2 V−1 s−1 at room temperature, and the precise measurement of the band gap Δ of a BaSnO3 crystal shows Δ = 4.05 eV, which is significantly larger than those of other transparent conductive oxides. The high mobility with a wide band gap indicates that (Ba,La)SnO3 is a promising candidate for transparent conductor applications and also epitaxial all-perovskite multilayer devices.
Lateral heating of SiO2/Si: Interfacial Si structure change causing tunneling current reduction
Authors: Chen Zhi , Ong Pang-Leen , Wang Yichun , Han Lei
Published: April 2012

Lateral heating processing of SiO2/Si samples can reduce the tunneling current of SiO2 by 5 orders of magnitude with very good reproducibility. There is a strong correlation between the flatband voltage shift of metal-oxide-semiconductor capacitors and the tunneling current reduction. Analysis of the flatband voltage shift suggests that origin of the tunneling current reduction after lateral heating is caused by the structure change of Si, most likely tensor strained Si, near the SiO2/Si interface.
Observation of UV-induced Auger features in catechol adsorbed on anatase TiO2 (101) single crystal surface
Authors: Thomas Andrew G. , Syres Karen L.
Published: April 2012

We have investigated the electronic structure of catechol adsorbed on the anatase TiO2 (101) surface under illumination with ultraviolet (UV) light (4.75 eV) using resonant photoemission spectroscopy. UV illumination results in the appearance of a strong Ti MVV (M refers to photoionization of 3p level and VV the Auger decay process via the valence levels) feature at a kinetic energy of 26.2 eV. This is attributed to the creation of localised states following catechol to Ti-3d excitation by the UV source. A sharp resonance attributed to excitation from Ti 3p states into these localised states is observed in constant final state spectra.
N-channel carbon nanotube enabled vertical field effect transistors with solution deposited ZnO nanoparticle based channel layers
Authors: Wang Po-Hsiang , Liu Bo , Shen Yu , Zheng Ying , McCarthy Mitchell A. , Holloway Paul , Rinzler Andrew G.
Published: April 2012

N-channel carbon nanotube enabled vertical field effect transistors (CN-VFETs) exploiting a solution deposited ZnO nanoparticle thin film as the channel material are demonstrated. Transistor performance benefits from a thermal anneal followed by an oxygen plasma treatment. The devices exhibit on/off ratios approaching 104 with output current densities exceeding 60 mA/cm2. Combined with p-channel organic CN-VFETs, the solution based processing could allow for the development of low-cost complementary circuits.
Tracking a complete voltage-sensor cycle with metal-ion bridges
Authors: Henrion Ulrike , Renhorn Jakob , Börjesson Sara I. , Nelson Erin M. , Schwaiger Christine S. , Bjelkmar Pär , Wallner Björn , Lindahl Erik , Elinder Fredrik
Published: April 2012

Voltage-gated ion channels open and close in response to changes in membrane potential, thereby enabling electrical signaling in excitable cells. The voltage sensitivity is conferred through four voltage-sensor domains (VSDs) where positively charged residues in the fourth transmembrane segment (S4) sense the potential. While an open state is known from the Kv1.2/2.1 X-ray structure, the conformational changes underlying voltage sensing have not been resolved. We present 20 additional interactions in one open and four different closed conformations based on metal-ion bridges between all four segments of the VSD in the voltage-gated Shaker K channel. A subset of the experimental constraints was used to generate Rosetta models of the conformations that were subjected to molecular simulation and tested against the remaining constraints. This achieves a detailed model of intermediate conformations during VSD gating. The results provide molecular insight into the transition, suggesting that S4 slides at least 12 Å along its axis to open the channel with a 3
10
helix region present that moves in sequence in S4 in order to occupy the same position in space opposite F290 from open through the three first closed states.
KLF15 negatively regulates estrogen-induced epithelial cell proliferation by inhibition of DNA replication licensing
Authors: Ray Sanhita , Pollard Jeffrey W.
Published: April 2012

In the epithelial compartment of the uterus, estradiol-17β (E
2
) induces cell proliferation while progesterone (P
4
) inhibits this response and causes differentiation of the cells. In this study, we identified the mechanism whereby E
2
and P
4
reciprocally regulate the expression of minichromosome maintenance (MCM)-2, a protein that is an essential component of the hexameric MCM-2 to 7 complex required for DNA synthesis initiation. We show in the uterine epithelium that Kruppel-like transcription (KLF) factors, KLF 4 and 15, are inversely expressed; most importantly, they bind to the
Mcm2
promoter under the regulation of E
2
and P
4
E
2
, respectively. After P
4
E
2
exposure and in contrast to E
2
treated mice, the
Mcm2
promoter displays increased histone 3 (H3) methylation and the recruitment of histone deacetylase 1 and 3 with the concomitant deacetylation of H3. This increased methylation and decreased acetylation is associated with an inhibition of RNA polymerase II binding, indicating an inactive
Mcm2
promoter following P
4
E
2
treatment. Using transient transfection assays in the Ishikawa endometrial cell line, we demonstrate that
Mcm2
promoter activity is hormonally stimulated by E
2
and that KLF15 inhibits this E
2
enhanced transcription. KLF15 expression also blocks Ishikawa cell proliferation through inhibition of MCM2 protein level. Importantly, in vivo expression of KLF15 in an estrogenized uterus mimics P
4
’s action by inhibiting E
2
-induced uterine epithelial MCM-2 expression and DNA synthesis. KLF15 is therefore a downstream physiological mediator of progesterone’s cell cycle inhibitory action in the uterine epithelium.
Computational adaptive optics for broadband optical interferometric tomography of biological tissue
Authors: Adie Steven G. , Graf Benedikt W. , Ahmad Adeel , Carney P. Scott , Boppart Stephen A.
Published: April 2012

Aberrations in optical microscopy reduce image resolution and contrast, and can limit imaging depth when focusing into biological samples. Static correction of aberrations may be achieved through appropriate lens design, but this approach does not offer the flexibility of simultaneously correcting aberrations for all imaging depths, nor the adaptability to correct for sample-specific aberrations for high-quality tomographic optical imaging. Incorporation of adaptive optics (AO) methods have demonstrated considerable improvement in optical image contrast and resolution in noninterferometric microscopy techniques, as well as in optical coherence tomography. Here we present a method to correct aberrations in a tomogram rather than the beam of a broadband optical interferometry system. Based on Fourier optics principles, we correct aberrations of a virtual pupil using Zernike polynomials. When used in conjunction with the computed imaging method interferometric synthetic aperture microscopy, this computational AO enables object reconstruction (within the single scattering limit) with ideal focal-plane resolution at all depths. Tomographic reconstructions of tissue phantoms containing subresolution titanium-dioxide particles and of ex vivo rat lung tissue demonstrate aberration correction in datasets acquired with a highly astigmatic illumination beam. These results also demonstrate that imaging with an aberrated astigmatic beam provides the advantage of a more uniform depth-dependent signal compared to imaging with a standard Gaussian beam. With further work, computational AO could enable the replacement of complicated and expensive optical hardware components with algorithms implemented on a standard desktop computer, making high-resolution 3D interferometric tomography accessible to a wider group of users and nonspecialists.
Tubulin homolog TubZ in a phage-encoded partition system
Authors: Oliva María A. , Martin-Galiano Antonio J. , Sakaguchi Yoshihiko , Andreu José M.
Published: April 2012

Partition systems are responsible for the process whereby large and essential plasmids are accurately positioned to daughter cells during bacterial division. They are typically made of three components: a centromere-like DNA zone, an adaptor protein, and an assembling protein that is either a Walker-box ATPase (type I) or an actin-like ATPase (type II). A recently described type III segregation system has a tubulin/FtsZ-like protein, called TubZ, for plasmid movement. Here, we present the 2.3 Å structure and dynamic assembly of a TubZ tubulin homolog from a bacteriophage and unravel the
Clostridium botulinum
phage c-st type III partition system. Using biochemical and biophysical approaches, we prove that a gene upstream from
tubZ
encodes the partner TubR and localize the centromeric region (
tubS
), both of which are essential for anchoring phage DNA to the motile TubZ filaments. Finally, we describe a conserved fourth component, TubY, which modulates the TubZ-R-
S
complex interaction.
Janus-faced liposomes enhance antimicrobial innate immune response in
Mycobacterium tuberculosis
infection
Authors: Greco Emanuela , Quintiliani Gianluca , Santucci Marilina B. , Serafino Annalucia , Ciccaglione Anna Rita , Marcantonio Cinzia , Papi Massimiliano , Maulucci Giuseppe , Delogu Giovanni , Martino Angelo , Goletti Delia , Sarmati Loredana , Andreoni Massimo , Altieri Alfonso , Alma Mario , Caccamo Nadia , Di Liberto Diana , De Spirito Marco , Savage Nigel D. , Nisini Roberto , Dieli Francesco , Ottenhoff Tom H. , Fraziano Maurizio
Published: April 2012

We have generated unique asymmetric liposomes with phosphatidylserine (PS) distributed at the outer membrane surface to resemble apoptotic bodies and phosphatidic acid (PA) at the inner layer as a strategy to enhance innate antimycobacterial activity in phagocytes while limiting the inflammatory response. Results show that these apoptotic body-like liposomes carrying PA (ABL/PA) (
i
) are more efficiently internalized by human macrophages than by nonprofessional phagocytes, (
ii
) induce cytosolic Ca
2+
influx, (
iii
) promote Ca
2+
-dependent maturation of phagolysosomes containing
Mycobacterium tuberculosis
(MTB), (
iv
) induce Ca
2+
-dependent reactive oxygen species (ROS) production, (
v
) inhibit intracellular mycobacterial growth in differentiated THP-1 cells as well as in type-1 and -2 human macrophages, and (
vi
) down-regulate tumor necrosis factor (TNF)-α, interleukin (IL)-12, IL-1β, IL-18, and IL-23 and up-regulate transforming growth factor (TGF)-β without altering IL-10, IL-27, and IL-6 mRNA expression. Also, ABL/PA promoted intracellular killing of
M. tuberculosis
in bronchoalveolar lavage cells from patients with active pulmonary tuberculosis. Furthermore, the treatment of MTB-infected mice with ABL/PA, in combination or not with isoniazid (INH), dramatically reduced lung and, to a lesser extent, liver and spleen mycobacterial loads, with a concomitant 10-fold reduction of serum TNF-α, IL-1β, and IFN-γ compared with that in untreated mice. Altogether, these results suggest that apoptotic body-like liposomes may be used as a Janus-faced immunotherapeutic platform to deliver polar secondary lipid messengers, such as PA, into phagocytes to improve and recover phagolysosome biogenesis and pathogen killing while limiting the inflammatory response.
Taxonomy, pod types and genetic resources.
Authors: Bosland P. W. , Votava E. J.
Published: April 2012

This chapter focuses on the taxonomy and morphology of various Capsicum species. Some wild and domesticated species and their pod types are discussed and germplasm collections of the US Department of Agriculture, Asian Vegetable Research and Development Centre in Tainan, Taiwan, Centro Agronomico Tropical de Investigations y Ensenanza in Turrialba, Costa Rica, Centre for Genetic Resources in Wageningen, Netherlands, and Central Institute for Genetics and Germplasm in Gatersleben, Germany are presented. The importance of the recognition of the special nature and distinctive features of agricultural biodiversity, so that the exchange and flow of germplasm are not constrained, and intellectual proprty rights are also highlighted.
Genetics, plant breeding and biotechnology.
Authors: Bosland P. W. , Votava E. J.
Published: April 2012

This paper focuses on the importance of the understanding of the pepper genetics and reproductive behaviour in the genetic improvement of Capsicum spp. The various methods used in pepper breeding for pest and disease resistance and the benefits of the use of some biotechnological methods, such as genetic engineering and tissue culture, are also highlighted.