bluuebunny/crossref_metadata_2025 huggingface dataset:
A new scenario framework for Climate Change Research: scenario matrix architecture
Authors: van Vuuren Detlef P. , Kriegler Elmar , O’Neill Brian C. , Ebi Kristie L. , Riahi Keywan , Carter Timothy R. , Edmonds Jae , Hallegatte Stephane , Kram Tom , Mathur Ritu , Winkler Harald
Published: October 2013

This paper describes the scenario matrix architecture that underlies a framework for developing new scenarios for climate change research. The matrix architecture facilitates addressing key questions related to current climate research and policy-making: identifying the effectiveness of different adaptation and mitigation strategies (in terms of their costs, risks and other consequences) and the possible trade-offs and synergies. The two main axes of the matrix are: 1) the level of radiative forcing of the climate system (as characterised by the representative concentration pathways) and 2) a set of alternative plausible trajectories of future global development (described as shared socio-economic pathways). The matrix can be used to guide scenario development at different scales. It can also be used as a heuristic tool for classifying new and existing scenarios for assessment. Key elements of the architecture, in particular the shared socio-economic pathways and shared policy assumptions (devices for incorporating explicit mitigation and adaptation policies), are elaborated in other papers in this special issue.
Vasile Tonoiu et l'esprit scientifique moderne: une approche roumaine de Gaston Bachelard
Authors: Buse Ionel
Published: October 2013

L’un des chercheurs roumains ayant Je plus travaillé sur l’œuvre de Bachelard en Roumanie fut le professeur Vasile Tonoiu de l’université de Bucarest. Dans cet article, nous analysons quelques-unes de ses réflexions au sujet de l’épistémologie du philosophe français. Même si la compréhension historique des travaux de Bachelard lui faisait défaut, cet auteur roumain a très bien saisi l’esprit du néorationalisme français, qu’il a mis en regard des recherches de l’épistémologie anglo-saxonne.
Stroke-Induced Brain Parenchymal Injury Drives Blood–Brain Barrier Early Leakage Kinetics: A Combined in Vivo/in Vitro Study
Authors: Kuntz Mélanie , Mysiorek Caroline , Pétrault Olivier , Pétrault Maud , Uzbekov Rustem , Bordet Régis , Fenart Laurence , Cecchelli Roméo , Bérézowski Vincent
Published: October 2013

The disappointing clinical outcomes of neuroprotectants challenge the relevance of preclinical stroke models and data in defining early cerebrovascular events as potential therapeutic targets. The kinetics of blood–brain barrier (BBB) leakage after reperfusion and the link with parenchymal lesion remain debated. By using in vivo and in vitro approaches, we conducted a kinetic analysis of BBB dysfunction during early reperfusion. After 60 minutes of middle cerebral artery occlusion followed by reperfusion times up to 24 hours in mice, a non-invasive magnetic resonance imaging method, through an original sequence of diffusion-weighted imaging, determined brain water mobility in microvascular compartments ( D∗) apart from parenchymal compartments (apparent diffusion coefficient). An increase in D∗ found at 4 hours post reperfusion concurred with the onset of both Evans blue/Dextran extravasations and in vitro BBB opening under oxygen-glucose deprivation and reoxygenation ( R). The BBB leakage coincided with an emerging cell death in brain tissue as well as in activated glial cells in vitro. The co-culture of BBB endothelial and glial cells evidenced a recovery of endothelium tightness when glial cells were absent or non-injured during R. Preserving the ischemic brain parenchymal cells within 4 hours of reperfusion may improve therapeutic strategies for cerebrovascular protection against stroke.
Surrogate safety measures as aid to driver assistance system design of the cognitive vehicle
Authors: Khan Ata , Bacchus Ataur , Erwin Stephen
Published: October 2013

The driver assistance system part of the cognitive vehicle design can prevent rear, lateral and other collisions by using a collision warning system that integrates intelligent technology and human factors. To be effective, such a system should be able to analyse driving states including driver distraction and driver intent, assess the likelihood of collisions by working with surrogate safety measures and issue warnings to the driver. This study presents a longitudinal and lateral collision warning model that allows the inclusion of key surrogate safety measures such as distance between vehicles in longitudinal vehicle‐following mode or envelopes of vehicles in the lateral direction during lane migration/change/merge movements. The model can take into account values of driver distraction and driver intent variables obtained on‐line or from off‐line devices. The formulation is also applicable to time‐to‐crash surrogate safety measure. A pattern recognition method is used for the identification of pre‐crash condition while minimising false alarms. The surrogate safety model is presented and illustrative examples are provided. The surrogate safety measure‐based warning system is mainly intended for on‐line use in actual driving conditions. In addition, it can be used in driving simulators or for off‐line safety studies in association with microsimulators of traffic.
TiO2/Fe2O3/CNTs magnetic photocatalyst: a fast and convenient synthesis and visible‐light‐driven photocatalytic degradation of tetracycline
Authors: Lu Changyu , Guan Weisheng , Zhang Gehong , Ye Linjing , Zhou Ya , Zhang Xian
Published: October 2013

The effective visible‐light‐driven photocatalysis of tetracycline still remains a big challenge for scientists. In this reported work, TiO2/Fe2O3/CNTs (carbon nanotubes) have been successfully synthesised by a fast and convenient method for the first time. A wide range of techniques, such as X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, magnetic measurements and UV–vis absorption spectroscopy were applied to characterise the obtained TiO2/Fe2O3/CNTs. Moreover, the photocatalytic properties of the TiO2/Fe2O3/CNTs in the degradation of tetracycline have been studied. In addition, it was found that TiO2/Fe2O3/CNTs have a better reusable photocatalyst than other traditional photocatalysts by the magnetic separation recycling method.
Time-resolved photoelectron imaging spectra from non-adiabatic molecular dynamics simulations
Authors: Humeniuk Alexander , Wohlgemuth Matthias , Suzuki Toshinori , Mitrić Roland
Published: October 2013

We present an efficient method for the simulation of time-resolved photoelectron imaging (TRPEI) spectra in polyatomic molecules. Our approach combines trajectory-based molecular dynamics that account for non-adiabatic effects using surface hopping, with an approximate treatment of the photoionization process using Dyson orbitals as initial and Coulomb waves as final electron states. The method has been implemented in the frame of linear response time-dependent density functional theory. As an illustration, we simulate time- and energy-resolved anisotropy maps for the furan molecule and compare them with recent experimental data [T. Fuji, Y.-I. Suzuki, T. Horio, T. Suzuki, R. Mitrić, U. Werner, and V. Bonačić-Koutecký, J. Chem. Phys. 133, 234303 (2010)]. Our method can be generally used for the interpretation of TRPEI experiments allowing to shed light into the fundamental photochemical processes in complex molecules.
Bipolar resistive switching characteristics in CuO/ZnO bilayer structure
Authors: Yang F. , Wei M. , Deng H.
Published: October 2013

Resistive switching characteristics in Cu/ZnO/AZO (Al-doped ZnO) were investigated. Reproducible bipolar resistance switching properties were observed in the single oxide layer (SL)-based device. To improve the switching performance, a CuO–ZnO bilayer (BL) was used to form a Cu/CuO/ZnO/AZO structure. RS characteristics such as retention time, endurance, variations of threshold voltage as well as distribution of resistance were investigated. The results demonstrated that the BL devices exhibit more excellent switching performance than SL devices. The conduction mechanisms of high and low resistance states can be explained by trap-controlled space charge limited current (SCLC) and Ohmic's Law, respectively. The CuO layer is proposed as a “reservoir” of oxygen ions in set process and acting as an oxygen ions “supplier” in reset process, which plays a critical role in recovery/rupture of filament paths and greatly improves the switching characteristics of the device.
A hybrid stochastic hierarchy equations of motion approach to treat the low temperature dynamics of non-Markovian open quantum systems
Authors: Moix Jeremy M. , Cao Jianshu
Published: October 2013

The hierarchical equations of motion technique has found widespread success as a tool to generate the numerically exact dynamics of non-Markovian open quantum systems. However, its application to low temperature environments remains a serious challenge due to the need for a deep hierarchy that arises from the Matsubara expansion of the bath correlation function. Here we present a hybrid stochastic hierarchical equation of motion (sHEOM) approach that alleviates this bottleneck and leads to a numerical cost that is nearly independent of temperature. Additionally, the sHEOM method generally converges with fewer hierarchy tiers allowing for the treatment of larger systems. Benchmark calculations are presented on the dynamics of two level systems at both high and low temperatures to demonstrate the efficacy of the approach. Then the hybrid method is used to generate the exact dynamics of systems that are nearly impossible to treat by the standard hierarchy. First, exact energy transfer rates are calculated across a broad range of temperatures revealing the deviations from the Förster rates. This is followed by computations of the entanglement dynamics in a system of two qubits at low temperature spanning the weak to strong system-bath coupling regimes.
Disordering and grain boundaries of (Ni,Fe)Cr2O4 spinels from atomistic calculations
Authors: Chartier Alain , Golovchuk Bogdan , Gossé Stéphane , Van Brutzel Laurent
Published: October 2013

A novel empirical potential has been developed to evaluate the thermodynamic stability of Ni1−xFexCr2O4 spinels. The simulations confirm the hypothesis that the NiCr2O4–FeCr2O4 pseudo-binary has normal structure spinel up to 1000 K and stabilizes as a solid solution. However, the disordering energy (normal to inverse spinel) is found higher for FeCr2O4 than for NiCr2O4 spinel. The formation energies of tilt, twist, and random grain boundaries have been calculated in pure NiCr2O4 and FeCr2O4. The same behavior has been found for both spinels. Detail analysis of the grain boundaries structure shows that the cation coordination number is a key parameter for the stability of the grain boundaries. With this criterion, we evidenced that the structural and energetic differences are caused only by nickel and iron cations.
Numerical investigation of frequency spectrum in the Hasegawa-Wakatani model
Authors: Kim Juhyung , Terry P. W.
Published: October 2013

The wavenumber-frequency spectrum of the two-dimensional Hasegawa-Wakatani model is investigated in the hydrodynamic, intermediate, and adiabatic regimes. A nonlinear frequency and a line width related to energy transfer properties provide a measure of the average frequency and spectral broadening, respectively. In the adiabatic regime, narrow spectra, typical of wave turbulence, are observed with a nonlinear frequency shift in the electron drift direction. In the hydrodynamic regime, broad spectra with almost zero nonlinear frequencies are observed. Nonlinear frequency shifts are shown to be related to nonlinear energy transfer by vorticity advection through the high frequency region of the spectrum. In the intermediate regime, the nonlinear frequency shift for density fluctuations is observed to be weaker than that of electrostatic potential fluctuations. The weaker frequency shift of the density fluctuations is due to nonlinear density advection, which favors energy transfer in the low frequency range. Both the nonlinear frequency and the spectral width increase with poloidal wavenumber ky. In addition, in the adiabatic regime where the nonlinear interactions manifest themselves in the nonlinear frequency shift, the cross-phase between the density and potential fluctuations is observed to match a linear relation, but only if the linear response of the linearly stable eigenmode branch is included. Implications of these numerical observations are discussed.
Numerical simulation of cross section electron-beam induced current in thin-film solar-cells for low and high injection conditions
Authors: Nichterwitz Melanie , Unold Thomas
Published: October 2013

Electron-beam induced current measurements (EBIC) in the cross-section configuration can be used to characterize electronic properties of thin-film solar-cells with a spatial resolution in the submicrometer range. Assuming low injection conditions and complete charge carrier collection in the depletion region, the minority charge-carrier diffusion length and width of the space charge region can be extracted from EBIC data using an analytical expression. In the present work, we evaluate the validity of the assumptions underlying the analytical description by using numerical device simulation to describe EBIC profiles perpendicular to the pn-junction of thin-film solar cells. We find that under low injection conditions, the analytical description provides good results if the minority charge-carrier diffusion length in the absorber layer is significantly larger than the width of the space charge region. On the other hand, the analytical description of the EBIC profiles deviates significantly from the numerical simulation for short diffusion lengths and also for high injection conditions. Experimental EBIC profiles of Cu(In,Ga)Se2 solar cells are evaluated to obtain local minority carrier diffusion-lengths and to illustrate high-injection and low-injection effects in the measurements.
Small plasma focus as neutron pulsed source for nuclides identification
Authors: Milanese M. , Niedbalski J. , Moroso R. , Barbaglia M. , Mayer R. , Castillo F. , Guichón S.
Published: October 2013

In this paper, we present preliminary results on the feasibility of employing a low energy (2 kJ, 31 kV) plasma focus device as a portable source of pulsed neutron beams (2.45 MeV) generated by nuclear fusion reactions D-D, for the “in situ” analysis of substances by nuclear activation. This source has the relevant advantage of being pulsed at requirement, transportable, not permanently radioactive, without radioactive waste, cheap, among others. We prove the feasibility of using this source showing several spectra of the characteristic emission line for manganese, gold, lead, and silver.
Development of very small-diameter, inductively coupled magnetized plasma device
Authors: Kuwahara D. , Mishio A. , Nakagawa T. , Shinohara S.
Published: October 2013

In order to miniaturize a high-density, inductively coupled magnetized plasma or helicon plasma to be applied to, e.g., an industrial application and an electric propulsion field, small helicon device has been developed. The specifications of this device along with the experimental results are described. We have succeeded in generating high-density (∼1019 m−3) plasmas using quartz tubes with very small diameters of 10 and 20 mm, with a radio frequency power ∼1200 and 700 W, respectively, in the presence of the magnetic field less than 1 kG.
Mechanism of activation of TiFe intermetallics for hydrogen storage by severe plastic deformation using high-pressure torsion
Authors: Edalati Kaveh , Matsuda Junko , Arita Makoto , Daio Takeshi , Akiba Etsuo , Horita Zenji
Published: October 2013

TiFe, a potential candidate for solid-state hydrogen storage, does not absorb hydrogen without a sophisticated activation process because of severe oxidation. This study shows that nanostructured TiFe becomes active by high-pressure torsion (HPT) and is not deactivated even after storage for several hundred days in the air. Surface segregation and formation of Fe-rich islands and cracks occur after HPT. The Fe-rich islands are suggested to act as catalysts for hydrogen dissociation and cracks and nanograin boundaries act as pathways to transport hydrogen through the oxide layer. Rapid atomic diffusion by HPT is responsible for enhanced surface segregation and hydrogen transportation.
Amplitude death and synchronized states in nonlinear time-delay systems coupled through mean-field diffusion
Authors: Banerjee Tanmoy , Biswas Debabrata
Published: October 2013

We explore and experimentally demonstrate the phenomena of amplitude death (AD) and the corresponding transitions through synchronized states that lead to AD in coupled intrinsic time-delayed hyperchaotic oscillators interacting through mean-field diffusion. We identify a novel synchronization transition scenario leading to AD, namely transitions among AD, generalized anticipatory synchronization (GAS), complete synchronization (CS), and generalized lag synchronization (GLS). This transition is mediated by variation of the difference of intrinsic time-delays associated with the individual systems and has no analogue in non-delayed systems or coupled oscillators with coupling time-delay. We further show that, for equal intrinsic time-delays, increasing coupling strength results in a transition from the unsynchronized state to AD state via in-phase (complete) synchronized states. Using Krasovskii–Lyapunov theory, we derive the stability conditions that predict the parametric region of occurrence of GAS, GLS, and CS; also, using a linear stability analysis, we derive the condition of occurrence of AD. We use the error function of proper synchronization manifold and a modified form of the similarity function to provide the quantitative support to GLS and GAS. We demonstrate all the scenarios in an electronic circuit experiment; the experimental time-series, phase-plane plots, and generalized autocorrelation function computed from the experimental time series data are used to confirm the occurrence of all the phenomena in the coupled oscillators.
The observation of scintillation in a hydrated inorganic compound: CeCl3·6H2O
Authors: Boatner L. A. , Neal J. S. , Ramey J. O. , Chakoumakos B. C. , Custelcean R.
Published: October 2013

We have recently reported the discovery of a family of rare-earth metal-organic single-crystal scintillators based on Ce3+ as the activator ion. Starting with the CeCl3(CH3OH)4 prototype, this family of scintillators has recently been extended to include complex metal-organic adducts produced by reacting CeCl3 with heavier organics (e.g., isomers of propanol and butanol). Some of these rare-earth metal-organic materials incorporated waters of hydration in their structures, and the observation of scintillation in these hydrated compounds was an original finding for any solid scintillator. In the present work, we report the observation of gamma-ray-excited scintillation in an inorganic hydrated material, namely, single-crystal monoclinic CeCl3·6H2O. This observation shows that the mechanisms of the various scintillation energy-transfer processes are not seriously inhibited by the presence of waters of hydration in an inorganic material and that the observation of scintillation in other hydrated inorganic compounds is not precluded.
Buoyancy effects on the integral lengthscales and mean velocity profile in atmospheric surface layer flows
Authors: Salesky Scott T. , Katul Gabriel G. , Chamecki Marcelo
Published: October 2013

Within the diabatic atmospheric surface layer (ASL) under quasi-stationary and horizontal homogeneous conditions, the mean velocity profile deviates from its conventional logarithmic shape by a height-dependent universal stability correction function ϕm(ζ) that varies with the stability parameter ζ. The ζ parameter measures the relative importance of mechanical to buoyant production or destruction of turbulent kinetic energy (TKE) within the ASL. A link between ϕm(ζ) and the spectrum of turbulence in the ASL was recently proposed by Katul et al. [“Mean velocity profile in a sheared and thermally stratified atmospheric boundary layer,” Phys. Rev. Lett. 107, 268502 (2011)]. By accounting for the stability-dependence of TKE production, Katul et al. were able to recover scalings for ϕm with the anticipated power-law exponents for free convective, slightly unstable, and stable conditions. To obtain coefficients for the ϕm(ζ) curve in good agreement with empirical formulas, they introduced a correction for the variation of the integral lengthscale of vertical velocity with ζ estimated from the Kansas experiment. In the current work, the link between the coefficients in empirical curves for ϕm(ζ) and stability-dependent properties of turbulence in the ASL, including the variation with ζ of the integral lengthscale and the anisotropy of momentum transporting eddies is investigated using data from the Advection Horizontal Array Turbulence Study. The theoretical framework presented by Katul et al. is revised to account explicitly for these effects. It is found that the coefficients in the ϕm(ζ) curve for unstable and near-neutral conditions can be explained by accounting for the stability-dependence of the integral lengthscale and anisotropy of momentum-transporting eddies; however, an explanation for the observed ϕm(ζ) curve for stable conditions remains elusive. The effect of buoyancy on the horizontal and vertical integral lengthscales is also analyzed in detail.
Crossover of spin glass characteristics as a function of field in an NiMnSnAl alloy
Authors: Agarwal Sandeep , Banerjee S. , Mukhopadhyay P. K.
Published: October 2013

The magnetic state in martensitic phase of Ni50Mn34Sn6Al10 shows interesting glassy behaviour. The irreversibility was observed in d.c. magnetization measurement below martensitic transformation temperature. Further measurements at lower temperature showed the presence of exchange bias field in sample. H-T phase diagram of the irreversibility showed that the system was in Heisenberg like spin glass state at low field, which changed its type when the external field was above the exchange bias field. In order to determine the cause of cross over, a.c. susceptibility measurements were performed in zero and d.c. biasing fields. This switching of glassy nature of the system is a novel phenomenon.
Influence of solvent contribution on nonlinearities of near infra-red absorbing croconate and squaraine dyes with ultrafast laser excitation
Authors: Bala Murali Krishna M. , Narayana Rao D.
Published: October 2013

Third order optical nonlinearities of various solvents such as Dimethylformamide (DMF), ethanol, chloroform, CCl4, acetone, toluene, Tetrahydrofuran (THF), and CS2 are studied in picosecond (ps) and femtosecond (fs) time scales using Z-scan technique. All the solvents show reverse saturable absorption behavior which is attributed to significant two-photon absorption and three-photon absorption processes in ps and fs time scale regimes, respectively. Nonlinear refraction studies reveal the positive signature of nonlinearity of solvents in both pulse regimes. We have investigated the effect of solvents on observed nonlinearities of near infra-red absorbing squaraine and croconate dye samples. Interestingly, a change in the sign of nonlinearity of molecules (phe cro, ptbu cro, phe squ, and ptbu squ) is observed in the ps regime when the solvent contribution is removed. Further, we also observed a change in magnitude of the nonlinearity for all the molecules under both pulse regimes. This gives clear evidence on the role of the solvents in the measurement of optical nonlinearities and that the true nonlinearities of the solute in fs/ps time domain can only be obtained when the measurements account for the solvent.
Dynamic electromechanical performance of viscoelastic dielectric elastomers
Authors: Sheng Junjie , Chen Hualing , Liu Lei , Zhang Junshi , Wang Yongquan , Jia Shuhai
Published: October 2013

Because of their viscoelasticity, dielectric elastomers (DEs) are able to produce a large time-dependent electromechanical deformation. In the current study, we use the Euler-Lagrange equation to characterize the influence of temperature, excitation frequency, and viscoelasticity on the dynamic electromechanical deformation and stability of viscoelastic dielectrics. We investigate the time-dependent dynamic performance, hysteresis, phase diagram, and Poincaré map associated with the viscoelastic dissipative process. The results show that the dynamic response has strong temperature and frequency dependencies. It is observed that the natural frequency of the DE decreases with increasing temperature and the maximal amplitude increases at higher temperatures. At relative low frequencies, the amplitude is very small and the viscoelasticity has a significant effect on the oscillation of the system. Furthermore, the results show that the viscoelasticity has a relatively major influence on the dynamic performance for DEs that have very low relaxation times.
Simulation of electrical conduction in thin polycrystalline metallic films: Impact of microstructure
Authors: Rickman J. M. , Barmak K.
Published: October 2013

We examine the impact of microstructural features on the electrical conductivity of a thin metallic film using Monte Carlo simulation. In particular, we obtain the dependence of the conductivity (in the absence of surface scattering) on average grain size and electron scattering mechanisms, the latter parametrized by a transmission coefficient, for a model polycrystal generated by a Voronoi tessellation. We find that the conductivity can be described in limiting cases in terms of either a simplified hopping model or a trapping model. Finally, we compare our results with the Mayadas-Shatzkes model of grain-boundary scattering and with experimental resistivity measurements for polycrystalline copper thin films.
Low-resistive monocrystalline Mg-Al-O barrier magnetic tunnel junctions for spin-transfer magnetization switching
Authors: Sukegawa Hiroaki , Mitani Seiji , Ohkubo Tadakatsu , Inomata Koichiro , Hono Kazuhiro
Published: October 2013

Monocrystalline Mg-Al-O barriers for magnetic tunnel junctions (MTJs) were fabricated by natural oxidation of Mg-Al thin films. The naturally oxidized Mg-Al-O barrier had a cation-disorder MgAl2O4 structure, and Fe/Mg-Al-O/Fe(001) MTJs showed a tunnel magnetoresistance (TMR) ratio of over 180% at room temperature. In addition, the natural oxidation process resulted in tunnel barriers with a resistance area product (RA) of less than 5 Ω·μm2. We observed clear magnetization switching in a CoFe/Mg-Al-O/CoFe MTJ by spin-transfer torque. These results indicate that the natural oxidation of Mg-Al alloy is an effective method for processing cation-disorder MgAl2O4 barrier for coherent TMR with low RA.
Enhanced flexoelectric effect in a non-ferroelectric composite
Authors: Li Yong , Shu Longlong , Zhou Yongcun , Guo Jing , Xiang Feng , He Li , Wang Hong
Published: October 2013

Direct flexoelectric effect was investigated in a non-ferroelectric composite (Bi1.5Zn0.5)(Zn0.5Nb1.5)O7/Ag (BZN/Ag) where the structure symmetry permits no macro-piezoelectricity. The flexoelectric coefficient of the BZN/Ag composite approaches 0.17 μC/m at room temperature. This value is 3–4 orders of magnitude higher than those of common dielectrics. Our research confirms the existence of flexoelectric effect in insulated non-ferroelectric materials except for ferroelectric relaxors.
Transient behavior in Pt/Nb-doped SrTiO3 Schottky junctions
Authors: Kan Daisuke , Shimakawa Yuichi
Published: October 2013

We investigated the transient behavior of Pt/Nb-doped SrTiO3 Schottky junctions that exhibit rectifying and hysteric I-V characteristics. We found that regardless of the junction resistance state, the junction under the bias shows the relaxation behavior over 104 s while the behavior is strongly dependent on the junction resistance state. Detailed investigation of the time dependence of the current and the capacitance of the junctions indicates that the junctions have the inhomogeneous Schottky barrier heights and depletion layer widths while the mean junction profile remains unchanged regardless of the junction resistance state. Given the experimental results, we attribute the observed transient behavior to time-dependent changes in the population of electrons trapped in the local conduction regions under the bias, which play an important role in determining the resistance state of Pt/Nb-doped SrTiO3 junction.
Aluminum doped core-shell ZnO/ZnS nanowires: Doping and shell layer induced modification on structural and photoluminescence properties
Authors: Dhara Soumen , Imakita Kenji , Giri P. K. , Mizuhata Minoru , Fujii Minoru
Published: October 2013

In this work, we investigated the combined effects of Al doping and surface modification on the fabrication of a core–shell type ZnO/ZnS nanowires (NWs) and its structural, electrical, and photoluminescence (PL) properties. A systematic investigation for different concentrations of Al doping followed by surface modification with different thicknesses of ZnS layer was performed. Significant changes in the nature of PL spectra and electronic conductivity are observed and insight discussions are present. Structural characterization on the core-shell NWs reveals the successful fabrication of Al doped highly single crystalline ZnO core and polycrystalline ZnS shell with both ZnO and ZnS are of hexagonal wurtzite structure. Compared with the bare undoped ZnO NWs, Al doped core-shell ZnO/ZnS NWs exhibit two orders of magnitude improvement in the electronic conductivity and fivefold enhancement in the UV PL intensity. The Al doped core-shell ZnO/ZnS NWs shows an efficient improvement in the UV PL intensity than the undoped core-shell ZnO NWs. The obtained improvement in the PL result is explained on the basis of interfacial transfer of photogenerated charge carriers and modification of defects.
Assignment of Fermi-level pinning and optical transitions to the (AsGa)2-OAs center in oxygen-doped GaAs
Authors: Colleoni Davide , Pasquarello Alfredo
Published: October 2013

The (AsGa)2-OAs defect in oxygen-doped GaAs, consisting of two As antisites neighboring an O center substitutional to As, is addressed through hybrid functional calculations. This defect not only accounts for the nearest neighbor environment of the O atom and the observed charge states but also yields a Fermi-level pinning position and optical transition energies between charge states in excellent agreement with experiment. The present assignment strongly supports the (AsGa)2-OAs center as origin of the Fermi-level pinning in oxygen-doped GaAs.
Paracrystalline property of high-entropy alloys
Authors: Wang Shaoqing
Published: October 2013

Atomic structure models of six-component high-entropy alloys with body-centered cubic structure are successfully built according to the principle of maximum entropy for the first time. The lattice distortion parameters g of seven typical high-entropy alloys are calculated. From the optimized lattice configuration of high-entropy alloys, we show that these alloys are ideal three-dimensional paracrystals. The formation mechanism, structural feature, mechanical property, and application prospect of high-entropy alloys are discussed in comparison with the traditional alloys. The novel properties of body-centered cubic high-entropy alloys are attributed to the failure of dislocation deformation mechanism and the difficulty of directed particle diffusion.
How allosteric control of
Staphylococcus aureus
penicillin binding protein 2a enables methicillin resistance and physiological function
Authors: Otero Lisandro H. , Rojas-Altuve Alzoray , Llarrull Leticia I. , Carrasco-López Cesar , Kumarasiri Malika , Lastochkin Elena , Fishovitz Jennifer , Dawley Matthew , Hesek Dusan , Lee Mijoon , Johnson Jarrod W. , Fisher Jed F. , Chang Mayland , Mobashery Shahriar , Hermoso Juan A.
Published: October 2013

Significance

Penicillin binding protein 2a imparts to the human pathogen Staphylococcus aureus resistance to β-lactam antibiotics. Our structural characterization of the allosteric basis governing its resistance mechanism identifies a basis for the design of new antibacterials that can both activate and inhibit this key resistance enzyme.
Insights into insect wing origin provided by functional analysis of
vestigial
in the red flour beetle,
Tribolium castaneum
Authors: Clark-Hachtel Courtney M. , Linz David M. , Tomoyasu Yoshinori
Published: October 2013

Significance

Insect wings are a core example of morphological novelty, yet their acquisition remains a biological conundrum. More than a century of debates and observations has culminated in two prominent hypotheses on the origin of insect wings. Here, we show that there are two separate wing serial homologs in the wingless first thoracic segment of a beetle,
Tribolium
. These two tissues are merged to form an ectopic wing structure in homeotic transformation. Intriguingly, the two wing serial homologs may actually be homologous to the two previously proposed wing origins, hence supporting the dual origin of insect wings. The merger of two unrelated tissues may have been a key step in developing this morphologically novel structure during evolution.
Convergence in feeding posture occurs through different genetic loci in independently evolved cave populations of
Astyanax mexicanus
Authors: Kowalko Johanna E. , Rohner Nicolas , Linden Tess A. , Rompani Santiago B. , Warren Wesley C. , Borowsky Richard , Tabin Clifford J. , Jeffery William R. , Yoshizawa Masato
Published: October 2013

Significance

Relatively little is known about the genetic basis of behavioral evolution, in particular for behaviors without any obvious related morphological changes. We have focused on changes in feeding posture that evolved in the small tetra
Astyanax mexicanus
as it adapted from life in the rivers to the very different ecological conditions found in caves. Using comparative quantitative genetics/genomics, we find that behavioral differences in feeding posture between surface and cave populations arose independently, through different polygenic genetic mechanisms in multiple, independent cave populations. This work provides insights into the genetic architecture of this behavioral trait and shows that this hard-wired behavior can arise through multiple genetic routes.
The Effects of Reading Comprehension and Launch Site on Frequency–Predictability Interactions during Paragraph Reading
Authors: Whitford Veronica , Titone Debra
Published: October 2013

We used eye movement measures of paragraph reading to examine whether word frequency and predictability interact during the earliest stages of lexical processing, with a specific focus on whether these effects are modulated by individual differences in reading comprehension or launch site (i.e., saccade length between the prior and currently fixated word—a proxy for the amount of parafoveal word processing). The joint impact of frequency and predictability on reading will elucidate whether these variables additively or multiplicatively affect the earliest stages of lexical access, which, in turn, has implications for computational models of eye movements during reading. Linear mixed effects models revealed additive effects during both early- and late-stage reading, where predictability effects were comparable for low- and high-frequency words. Moreover, less cautious readers (e.g., readers who engaged in skimming, scanning, mindless reading) demonstrated smaller frequency effects than more cautious readers. Taken together, our findings suggest that during extended reading, frequency and predictability exert additive influences on lexical and postlexical processing, and that individual differences in reading comprehension modulate sensitivity to the effects of word frequency.
Understanding Green Occupations from a Task‐Based Approach
Authors: Peters David J.
Published: October 2013

Green occupations are identified using the diversity, use, and relevance of green tasks in the United States. Results find 176, of nearly 1,000, occupations use at least one green task, but only 70 intensively use green tasks. Green‐intensive jobs are quality jobs that are full‐time, pay above average wages, and have health insurance. The employment outlook for all green jobs is positive, but new job growth lags behind other sectors. Green jobs are accessible to disadvantaged workers with limited education and experience, but most are not well paid. The majority of green jobs are male dominated, yet are racially and ethnically diverse. Implications for green jobs policies are discussed.
Compound cis-regulatory elements with both boundary and enhancer sequences in the human genome
Authors: Jjingo Daudi , Wang Jianrong , Conley Andrew B. , Lunyak Victoria V. , Jordan I. King
Published: October 2013

Motivation: It has been suggested that presumably distinct classes of genomic regulatory elements may actually share common sets of features and mechanisms. However, there has been no genome-wide assessment of the prevalence of this phenomenon.

Results: To evaluate this possibility, we performed a bioinformatic screen for the existence of compound regulatory elements in the human genome. We identified numerous such colocated boundary and enhancer elements from human CD4+ T cells. We report evidence that such compound regulatory elements possess unique chromatin features and facilitate cell type-specific functions related to inflammation and immune response in CD4+ T cells.

Contact:  king.jordan@biology.gatech.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.
Infanticide as a male reproductive strategy has a nutritive risk effect in brown bears
Authors: Steyaert S. M. J. G. , Reusch C. , Brunberg S. , Swenson J. E. , Hackländer K. , Zedrosser A.
Published: October 2013

Behavioural strategies to reduce predation risk can incur costs, which are often referred to as risk effects. A common strategy to avoid predation is spatio-temporal avoidance of predators, in which prey typically trade optimal resources for safety. Analogous with predator–prey theory, risk effects should also arise in species with sexually selected infanticide (SSI), in which females with dependent offspring avoid infanticidal males. SSI can be common in brown bear (
Ursus arctos
) populations and explains spatio-temporal segregation among reproductive classes. Here, we show that in a population with SSI, females with cubs-of-the-year had lower quality diets than conspecifics during the SSI high-risk period, the mating season. After the mating season, their diets were of similar quality to diets of their conspecifics. Our results suggest a nutritive risk effect of SSI, in which females with cubs-of-the-year alter their resource selection and trade optimal resources for offspring safety. Such risk effects can add to female costs of reproduction and may be widespread among species with SSI.
Predictive systems ecology
Authors: Evans Matthew R. , Bithell Mike , Cornell Stephen J. , Dall Sasha R. X. , Díaz Sandra , Emmott Stephen , Ernande Bruno , Grimm Volker , Hodgson David J. , Lewis Simon L. , Mace Georgina M. , Morecroft Michael , Moustakas Aristides , Murphy Eugene , Newbold Tim , Norris K. J. , Petchey Owen , Smith Matthew , Travis Justin M. J. , Benton Tim G.
Published: October 2013

Human societies, and their well-being, depend to a significant extent on the state of the ecosystems that surround them. These ecosystems are changing rapidly usually in response to anthropogenic changes in the environment. To determine the likely impact of environmental change on ecosystems and the best ways to manage them, it would be desirable to be able to predict their future states. We present a proposal to develop the paradigm of predictive systems ecology, explicitly to understand and predict the properties and behaviour of ecological systems. We discuss the necessary and desirable features of predictive systems ecology models. There are places where predictive systems ecology is already being practised and we summarize a range of terrestrial and marine examples. Significant challenges remain but we suggest that ecology would benefit both as a scientific discipline and increase its impact in society if it were to embrace the need to become more predictive.
A comparative collision-based analysis of human gait
Authors: Lee David V. , Comanescu Tudor N. , Butcher Michael T. , Bertram John E. A.
Published: October 2013

This study compares human walking and running, and places them within the context of other mammalian gaits. We use a collision-based approach to analyse the fundamental dynamics of the centre of mass (CoM) according to three angles derived from the instantaneous force and velocity vectors. These dimensionless angles permit comparisons across gait, species and size. The collision angleΦ, which is equivalent to the dimensionless mechanical cost of transport CoTmech, is found to be three times greater during running than walking of humans. This threefold difference is consistent with previous studies of walking versus trotting of quadrupeds, albeittends to be greater in the gaits of humans and hopping bipeds than in quadrupeds. Plotting the collision angleΦtogether with the angles of the CoM force vectorΘand velocity vectorΛresults in the functional grouping of bipedal and quadrupedal gaits according to their CoM dynamics—walking, galloping and ambling are distinguished as separate gaits that employ collision reduction, whereas trotting, running and hopping employ little collision reduction and represent more of a continuum that is influenced by dimensionless speed. Comparable with quadrupedal mammals, collision fraction (the ratio of actual to potential collision) is 0.51 during walking and 0.89 during running, indicating substantial collision reduction during walking, but not running, of humans.
Short-term disturbance by a commercial two-dimensional seismic survey does not lead to long-term displacement of harbour porpoises
Authors: Thompson Paul M. , Brookes Kate L. , Graham Isla M. , Barton Tim R. , Needham Keith , Bradbury Gareth , Merchant Nathan D.
Published: October 2013

Assessments of the impact of offshore energy developments are constrained because it is not known whether fine-scale behavioural responses to noise lead to broader-scale displacement of protected small cetaceans. We used passive acoustic monitoring and digital aerial surveys to study changes in the occurrence of harbour porpoises across a 2000 km2study area during a commercial two-dimensional seismic survey in the North Sea. Acoustic and visual data provided evidence of group responses to airgun noise from the 470 cu inch array over ranges of 5–10 km, at received peak-to-peak sound pressure levels of 165–172 dB re 1 µPa and sound exposure levels (SELs) of 145–151 dB re 1 µPa2s−1. However, animals were typically detected again at affected sites within a few hours, and the level of response declined through the 10 day survey. Overall, acoustic detections decreased significantly during the survey period in the impact area compared with a control area, but this effect was small in relation to natural variation. These results demonstrate that prolonged seismic survey noise did not lead to broader-scale displacement into suboptimal or higher-risk habitats, and suggest that impact assessments should focus on sublethal effects resulting from changes in foraging performance of animals within affected sites.
Improving Electricity Market Price Forecasting with Factor Models for the Optimal Generation Bid
Authors: Muñoz M. Pilar , Corchero Cristina , Heredia F.‐Javier
Published: October 2013

Dans les marchés libéralisés de l'électricité, la façon dont les producteurs d'électricité gérent leur production est base sur une offre horaire qui est transmise vers le marché day‐ahead. Malgré l'objectif des producteurs d'électricité est de maximiser leurs profits, le spot price auquel l'énergie sera payée n'est pas connu au cours du processus d'appel d'offres. Cette situation rend la prévision du spot price un point essentiel dans les stratégies de gestion économique de l'électricité. Dans ce travail, nous appliquons des modéles de prévision des facteurs pour l'estimation du spot price en étudiant sa pertinence. Les résultats obtenus en termes de qualité de l'ajustement sont équivalents á ceux obtenus avec les modéles ARIMA, mais leur application est plus facile. Ce modèle de prévision du spot price est utilisé pour générer les scénarios des prix d'un modèle de programmation stochastique qui trouve l'offre optimale de génération dans le marché Espagnol de l'électricité day‐ahead Les courbes d'offres optimales de génération sont présentées et analysées.
Cell‐mediated immune responses in oral disease: A review
Authors: Lehner T.
Published: October 2013

Abstract. A review of cell‐mediated immunity in oral disease suggests that Gram‐negative bacteria, fungi, viruses and oral mucosa may give rise to 4 groups of immune responses. In gingival and periodontal disease (Group I), lymphocyte transformation is stimulated with dental plaque, Veillonella alcalescens, Fusobacterium fusiforme and Bacteroides melaninogenicus. Cytotoxicity against unrelated target cells and migration inhibition of macrophages also results from lymphocyte activation. The functions of lymphocytes are affected by serum factors which might prove to be antibodies or immune complexes. These data suggest that cell‐mediated immunity against a number of oral microorganisms may be involved in the pathogenesis of periodontal disease. Immunological studies in recurrent aphthous ulceration (Group II) suggest that oral epithelium or some antigenically cross‐reacting microorganism stimulates cell‐mediated and antibody responses. Autoimmune damage of oral mucosa, resulting in ulceration, can be accounted for by the immunological competence and cytotoxic potential of sensitized lymphocytes. Susceptibility to recurrent Herpes virus hominis type 1 infections (Group IIIA) may be accounted for by a selective and specific impairment of production of migration inhibitory factor and cytotoxicity in the presence of intact lymphocyte sensitization and antibody formation. Chronic muco‐cutaneous candidosis (Group IIIB) shows spectral immunodeficiencies with cell‐mediated and antibody defects which have been broadly related to the severity of clinical manifestations. Thus, in chronic oral hyperplastic candidosis the cellular immune defect may be limited to cytotoxicity, migration inhibition and sometimes impaired delayed hypersensitivity skin reaction to Candida albicans. Serum IgG and IgM antibodies are depressed also, but salivary IgA antibodies are raised and lymphocyte transformation is also intact. In the various histological stages of leukoplakia and in carcinoma (Group IV) there is a significant increase, mostly in lymphocytes and plasma cells. This is associated with a corresponding decrease in transformation of lymphocytes stimulated with autologous leukoplakic tissue. Cell‐mediated immune studies may show whether there is an impaired tumor surveillance in the leukoplakia‐carcinoma relationship.
A Review on Dimension Reduction
Authors: Ma Yanyuan , Zhu Liping
Published: October 2013

Résumer l'impact d'un nombre élevé de variables explicatives à celui d'un nombre réduit de combinaisons linéaires bien choisies constitue une façon efficace de réduire la dimension d'un problème. Cette réduction à un petit nombre de combinaisons linéaires est réalisée à partir d'hypothèses minimales sur la forme de la dépendance et jouit, par rapport à une approche fondée sur la sélection de variables, de propriétés particulièrement attractives. Nous passons en revue la littérature existante sur ce sujet, en mettant l'accent sur les modèles les plus courants, dans lesquels la réduction de dimension affecte l'espérance conditionnelle de la réponse ou sa loi conditionnelle tout entière. Nous discutons plusieurs méthodes d'estimation et d'inférence, en insistant sur les idées sous‐jacentes plutôt que sur les aspects techniques. Nous présentons également quelques problèmes non résolus et thèmes de recherches futures dans ce domaine.