bluuebunny/crossref_metadata_2025 huggingface dataset:
The Cognitive Basis for Sentence Planning Difficulties in Discourse After Traumatic Brain Injury
Authors: Peach Richard K.
Published: May 2013

Purpose

Analyses of language production of individuals with traumatic brain injury (TBI) place increasing emphasis on microlinguistic (i.e., within-sentence) patterns. It is unknown whether the observed problems involve implementation of well-formed sentence frames or represent a fundamental linguistic disturbance in computing sentence structure. This study investigated the cognitive basis for microlinguistic deficits in individuals with TBI.

Method

Fifteen nonaphasic individuals with severe TBI and 6 age- and education-matched non brain–injured adults participated in this study. Monologic discourse samples were analyzed for pausing patterns, mazes, errors, and abandoned utterances. Measures of cognitive abilities were correlated with the sentence measures.

Results

The speakers with TBI produced more pauses between clauses (but not within clauses) as well as more mazes than did the non brain–injured speakers. Significant regression models were built. Raven's Coloured Progressive Matrices (Raven, 1965), a measure associated with working memory, predicted pause behavior, and Likenesses–Differences (Baker & Leland, 1967), a measure of executive function, predicted maze behavior.

Conclusions

Sentence planning impairments following TBI are associated with deficient organization and monitoring of language representations in working memory. These findings suggest that the deficits are due to problems in the recruitment and control of attention for sentence planning. These findings bear on sentence processing models that emphasize the activation, organization, and maintenance of language representations for accurate sentence production.
Measuring Lexical Diversity in Narrative Discourse of People With Aphasia
Authors: Fergadiotis Gerasimos , Wright Heather H. , West Thomas M.
Published: May 2013

Purpose

A microlinguistic content analysis for assessing lexical semantics in people with aphasia (PWA) is lexical diversity (LD). Sophisticated techniques have been developed to measure LD. However, validity evidence for these methodologies when applied to the discourse of PWA is lacking. The purpose of this study was to evaluate four measures of LD to determine how effective they were at measuring LD in PWA.

Method

Four measures of LD were applied to short discourse samples produced by 101 PWA: (a) the Measure of Textual Lexical Diversity (MTLD; McCarthy, 2005), (b) the Moving-Average Type-Token Ratio (MATTR; Covington, 2007), (c) D (McKee, Malvern, & Richards, 2000), and (d) the Hypergeometric Distribution (HD-D; McCarthy & Jarvis, 2007). LD was estimated using each method, and the scores were subjected to a series of analyses (e.g., curve-fitting, analysis of variance, confirmatory factor analysis).

Results

Results from the confirmatory factor analysis suggested that MTLD and MATTR reflect LD and little of anything else. Further, two indices (HD-D and D) were found to be equivalent, suggesting that either one can be used when samples are >50 tokens.

Conclusion

MTLD and MATTR yielded the strongest evidence for producing unbiased LD scores, suggesting that they may be the best measures for capturing LD in PWA.
Speech Motor Programming in Apraxia of Speech: Evidence From a Delayed Picture-Word Interference Task
Authors: Mailend Marja-Liisa , Maas Edwin
Published: May 2013

Purpose

Apraxia of speech (AOS) is considered a speech motor programming impairment, but the specific nature of the impairment remains a matter of debate. This study investigated 2 hypotheses about the underlying impairment in AOS framed within the Directions Into Velocities of Articulators (DIVA; Guenther, Ghosh, & Tourville, 2006) model: The retrieval hypothesis states that access to the motor programs is impaired, and the damaged programs hypothesis states that the motor programs themselves are damaged.

Method

The experiment used a delayed picture-word interference paradigm in which participants prepare their response and auditory distracters are presented with the go signal. The overlap between target and distracter words was manipulated (i.e., shared sounds or no shared sounds), and participants' reaction times (RTs) were measured. Participants included 5 speakers with AOS (4 with concomitant aphasia), 2 speakers with aphasia without AOS, and 9 age-matched control speakers.

Results

The control speakers showed no effects of distracter type or presence. The speakers with AOS had longer RTs in the distracter condition compared to the no-distracter condition. The speakers with aphasia without AOS were comparable to the control group in their overall RTs and RT pattern.

Conclusion

Results provide preliminary support for the retrieval hypothesis, suggesting that access to motor programs may be impaired in speakers with AOS. However, the possibility that the motor programs may also be damaged cannot be ruled out.
Modular stator switched reluctance motor for fault tolerant drive systems
Authors: Ruba Mircea , Viorel Ioan‐Adrian , Szabó Loránd
Published: May 2013

A modular stator switched reluctance motor (SRM) for fault tolerant drive systems is proposed. Owing to the particular construction of the stator there is no mutual coupling between adjacent phases. Hence, the motor can work also when a part of the coils is faulted and the faulted modules can be replaced without uncoupling the machine from the load or gearbox. The sizing particularities are presented and the mathematical model of the motor is developed. The results obtained via finite element analysis are compared with the analytical ones, and with that resulting after testing the constructed laboratory model. All these prove that the proposed SRM can be used in safety–critical drives.
Computational fluid dynamics modelling of an entire synchronous generator for improved thermal management
Authors: Connor Peter H. , Pickering Steve J. , Gerada Chris , Eastwick Carol N. , Micallef Chris , Tighe Chris
Published: May 2013

This study is the first in a series dedicated to investigating the airflow and thermal management of electrical machines. Owing to the temperature dependent resistive losses in the machine's windings, any improvement in cooling provides a direct reduction in losses and an increase in efficiency. This study focuses on the airflow which is intrinsically linked to the thermal behaviour of the machine as well as the windage power consumed to drive the air through the machine. A full computational fluid dynamics (CFD) model has been used to analyse the airflow around all major components of the machine. Results have been experimentally validated and investigated. At synchronous speed the experimentally tested mass flow rate and windage torque were under predicted by 4% and 7%, respectively, by the CFD. A break‐down of torque by component shows that the fan consumes approximately 87% of the windage torque.
Mechanisms of Intervertebral Disk Degeneration/Injury and Pain: A Review
Authors: Ito Keita , Creemers Laura
Published: May 2013

Degeneration of the intervertebral disk and its treatments are currently intensely investigated topics. Back pain is a condition whose chronic and debilitating nature combined with its prevalence make it a major health issue of substantial socioeconomic importance. Although researchers, and even sometimes clinicians, focus on the degenerated disk as the problem, to most patients, pain is the factor that limits their function and impacts their well-being. The purpose of this review is to delineate the changes associated with disk degeneration and to outline mechanisms by which they could be the source of back pain. Although the healthy disk is only innervated in the external layer of its annulus fibrosus, adjacent structures are plentiful with nociceptive receptors. Stimulation of such structures as a consequence of processes initiated by disk degeneration is explored. The concept of discogenic pain and possible mechanisms such as neoinnervation and solute transport are discussed. Finally, how such pain mechanisms may relate to current and proposed treatment strategies is discussed.
A 100 kV, 60 A solid state 4 kHz switching modulator for high power klystron driving
Authors: Cortázar O. D. , Ganuza D. , De La Fuente J. M. , Zulaika M. , Pérez A. , Anderson D. E.
Published: May 2013

A solid state high power modulator capable of delivering 120 kV and 60 A developed in collaboration with the JEMA Corporation, ESS Bilbao, and the SNS (ORNL) for driving high power klystrons is presented. Pulses with less than 10 μs risetime and flatness under 0.1% are obtained with programmable frequency pulses between 2 and 50 Hz. Eight solid state switches combined with custom air-insulated high voltage transformers working at a switching frequency of 4 kHz produce high quality pulses by phase shifting the transformer drives. Each relative high frequency stage pumps a double stage high voltage Marx generator that supplies the output pulse shape and frequency. This merged topology between a Marx generator and direct modulator takes advantage of the strengths of both approaches. Low energy storage in the output stages assures safe operation in case of a load arc discharge. Real time voltage correction during the pulse is also provided to compensate for the droop inherent with the use of low energy storage in the output stages. Data at full power with a dummy resistive load are presented.
Vibrational overtone spectroscopy and intramolecular dynamics of C–H stretches in pyrrole
Authors: Portnov Alexander , Epshtein Michael , Rosenwaks Salman , Bar Ilana
Published: May 2013

Room-temperature photoacoustic spectra and jet-cooled action spectra of the regions of the first and second C–H stretch overtones of pyrrole were measured with the goal of gaining new insight on the vibrational patterns and the intramolecular energy flow out of the initially excited vibrational states. The rotational cooling of the action spectra helped in observing hitherto unresolved features, assisting determination of the existing multiple bands and their positions in each region. These bands were analyzed by building vibrational Hamiltonian matrices related to a simplified joint local-mode/normal-mode (LM/NM) model, accounting for two types of C–H stretches and their Fermi resonances with the CCH deformation modes. The diagonalization of the LM/NM vibrational Hamiltonians and the fitting of the eigenvalues to the band positions revealed model parameters, enabling assignment of the observed bands. The time dependences of the survival probabilities of the C–H stretches in the region of the first and second overtones, deduced from the vibrational Hamiltonian, show quantum beats due to the couplings to the deformations and decays driven by weaker interactions to the bath states. The C–H stretches, although somewhat lower in energy, show stronger coupling than the N–H stretches.
Solid state nuclear magnetic resonance investigation of polymer backbone dynamics in poly(ethylene oxide) based lithium and sodium polyether-ester-sulfonate ionomers
Authors: Roach David J. , Dou Shichen , Colby Ralph H. , Mueller Karl T.
Published: May 2013

Polymer backbone dynamics of single ion conducting poly(ethylene oxide) (PEO)-based ionomer samples with low glass transition temperatures (Tg) have been investigated using solid-state nuclear magnetic resonance. Experiments detecting 13C with 1H decoupling under magic angle spinning (MAS) conditions identified the different components of the polymer backbone (PEO spacer and isophthalate groups) and their relative mobilities for a suite of lithium- and sodium-containing ionomer samples with varying cation contents. Variable temperature (203–373 K) 1H-13C cross-polarization MAS (CP-MAS) experiments also provided qualitative assessment of the differences in the motions of the polymer backbone components as a function of cation content and identity. Each of the main backbone components exhibit distinct motions, following the trends expected for motional characteristics based on earlier Quasi Elastic Neutron Scattering and 1H spin-lattice relaxation rate measurements. Previous 1H and 7Li spin-lattice relaxation measurements focused on both the polymer backbone and cation motion on the nanosecond timescale. The studies presented here assess the slower timescale motion of the polymer backbone allowing for a more comprehensive understanding of the polymer dynamics. The temperature dependences of 13C linewidths were used to both qualitatively and quantitatively examine the effects of cation content and identity on PEO spacer mobility. Variable contact time 1H-13C CP-MAS experiments were used to further assess the motions of the polymer backbone on the microsecond timescale. The motion of the PEO spacer, reported via the rate of magnetization transfer from 1H to 13C nuclei, becomes similar for ${\rm T} \mathbin{\lower.3ex\hbox{\buildrel>\over{\smash{\scriptstyle\sim}\vphantom{_x}}}} {\rm 1}{\rm.1}$T≳1.1 Tg in all ionic samples, indicating that at similar elevated reduced temperatures the motions of the polymer backbones on the microsecond timescale become insensitive to ion interactions. These results present an improved picture, beyond those of previous findings, for the dependence of backbone dynamics on cation density (and here, cation identity as well) in these amorphous PEO-based ionomer systems.
Vapor nucleation on a wettable nanoparticle carrying a non-central discrete electric charge
Authors: Warshavsky V. B. , Podguzova T. S. , Tatyanenko D. V. , Shchekin A. K.
Published: May 2013

We have studied thermodynamics of vapor nucleation on a spherical wettable dielectric nanoparticle carrying a discrete electric charge located at a certain distance from the particle center. New general equations for the chemical potential of a condensate molecule in the droplet around the particle, the work of the droplet formation and the droplet shape as functions of the effective radius of condensate film, and the value of an electric charge and its location with respect to the particle center have been derived analytically. These equations take into account both the effects of the non-central electric field and the disjoining pressure in the thin liquid film forming the droplet. Under the assumption of small distortion of the droplet shape in the axisymmetric electric field of non-central discrete charge from the spherical one, these equations have been simultaneously solved analytically. The obtained explicit formulas for the condensate chemical potential, the work of droplet formation, and the droplet shape have been numerically investigated for the case of the charge adsorbed below and above the surface of the particle. It has been shown that the effect of the electric field of non-central charge reveals itself in decreasing the maximum value of the condensate chemical potential in the droplet and shifting it away from the particle surface. As a result, the threshold value of the vapor supersaturation for barrierless nucleation and the activation barrier for barrier nucleation on the charged nanosized nuclei diminish in comparison with nucleation on nuclei with central charge. The effect is larger for smaller nuclei. It decreases with increase in the dielectric constant of the nuclei in the case of charge location below the particle surface.
Theoretical and experimental investigation of Raman modes, ferroelectric and dielectric properties of relaxor Na0.5Bi0.5TiO3
Authors: Niranjan Manish K. , Karthik T. , Asthana Saket , Pan Jaysree , Waghmare Umesh V.
Published: May 2013

We use a combination of first-principles density functional theoretical analysis and experimental characterization to understand the lattice dynamics, dielectric and ferroelectric properties of lead-free relaxor ferroelectric Na0.5Bi0.5TiO3 (NBT) system. Vibrational spectrum determined through our calculations agrees well with the observed Raman spectrum, and allows assignment of symmetry labels to modes. The calculated Born effective charges reveal (a) two distinct types of Ti ions at the B-site with anomalous dynamical charges differing by up 1.6e, and (b) Na and Bi ions at the A-site exhibit disparate dynamical charges of about 1 and 5.5e, respectively. Thus, there exist hetero-polar activity at both A and B-sites in NBT, and disorder associated with these hetero-polar ions is responsible for its relaxor behaviour. Large dielectric response of NBT arises primarily from phonons, and specifically the modes involving Bi-O (109 cm−1) and Ti-O (246, 276 cm−1) vibrations, respectively.
Spontaneous penetration of a non-wetting drop into an exposed pore
Authors: Yue Pengtao , Renardy Yuriko
Published: May 2013

We consider the penetration process of a liquid drop approaching an exposed pore along the axis of symmetry, which is intended to model the penetration of non-wetting drops into a porous medium. Inertia and gravity are neglected at the current stage. In addition to the penetration into a capillary tube in the literature, the drop may spread on the outer surface of the porous medium. Based on the mechanical equilibrium states, we find the critical drop radius, below which the drop penetration is spontaneous. We further identify five penetration regimes based on the drop radius and the static contact angle, all of which are exemplified by phase-field simulations. The free energy as a function of penetration depth reveals only two stable equilibrium states: the drop either enters the pore completely (maximum penetration) or stays at the pore inlet (zero penetration). For a non-penetrating drop radius, the free energy has a local maximum which constitutes an energy barrier that prevents spontaneous penetration. Finally, we modify the Lucas-Washburn equation to describe the dynamic process of penetration. Due to the neglect of dissipation from moving contact lines and entry flow, the modified Lucas-Washburn equation greatly overestimates the penetration rate, especially at the initial stage.
Spinors and the Weyl tensor classification in six dimensions
Authors: Batista Carlos , Carneiro da Cunha Bruno
Published: May 2013

A spinorial approach to six-dimensional differential geometry is constructed and used to analyze tensor fields of low rank, with special attention to the Weyl tensor. We perform a study similar to the four-dimensional case, making full use of the SO(6) symmetry to uncover results not easily seen in the tensorial approach. Using spinors, we propose a classification of the Weyl tensor by reinterpreting it as a map from 3-vectors to 3-vectors. This classification is shown to be intimately related to the integrability of maximally isotropic subspaces, establishing a natural framework to generalize the Goldberg-Sachs theorem. We work in complexified spaces, showing that the results for any signature can be obtained by taking the desired real slice.
A generalized any-particle propagator theory: Prediction of proton affinities and acidity properties with the proton propagator
Authors: Díaz-Tinoco Manuel , Romero Jonathan , Ortiz J. V. , Reyes Andrés , Flores-Moreno Roberto
Published: May 2013

We have recently extended the electron propagator theory to the treatment of any type of particle using an Any-Particle Molecular Orbital (APMO) wavefunction as reference state. This approach, called APMO/PT, has been implemented in the LOWDIN code to calculate correlated binding energies, for any type of particle in molecular systems. In this work, we present the application of the APMO/PT approach to study proton detachment processes. We employed this method to calculate proton binding energies and proton affinities for a set of inorganic and organic molecules. Our results reveal that the second-order proton propagator (APMO/PP2) quantitatively reproduces experimental trends with an average deviation of less than 0.41 eV. We also estimated proton affinities with an average deviation of 0.14 eV and the proton hydration free energy using APMO/PP2 with a resulting value of −270.2 kcal/mol, in agreement with other results reported in the literature. Results presented in this work suggest that the APMO/PP2 approach is a promising tool for studying proton acid/base properties.
Modification of tokamak edge plasma turbulence and transport by biasing and resonant helical magnetic field
Authors: Lafouti Mansoureh , Ghoranneviss Mahmood , Meshkani Sakineh , Salar Elahi Ahmad
Published: May 2013

In this paper, both Resonant Helical magnetic Field (RHF) and limiter biasing have been applied to the tokamak. We have investigated their effects on the turbulence and transport of the particles at the edge of the plasma. The biased limiter voltage has been fixed at 200 V and RHF has L = 2 and L = 3. Also, the effects of the time order of the application of RHF and biasing to the tokamak have been explored. The experiment has been performed under three conditions. At first, the biasing and RHF were applied at t = 15 ms and at t = 20 ms. In the next step, RHF and biasing were applied at t = 15 ms and t = 20 ms, respectively. Finally, both of them were turned on at t = 15 ms until the end of the shot. For this purpose, the ion saturation current (Isat) and the floating potential (Vf) have been measured by the Langmuir probe at r/a = 0.9. Moreover, the power spectra of Isat and floating potential gradient (∇Vf), the coherency, the phase between them, and the particle diffusion coefficient have been calculated. The density fluctuations of the particles have been measured by the Rake probe and they have been analyzed with the Probability Distribution Function (PDF) technique. Also the particle diffusion coefficient has been determined by the Fick's law. The results show that, when RHF and biasing were applied at the same time to the plasma (during flatness region of plasma current), the radial particle density gradient, the radial particle flux, and the particle diffusion coefficient decrease about 50%, 60%, and 55%, respectively, compared to the other conditions. For more precision, the average values of the particle flux and the particle density gradient were calculated in the work. When the time is less than 15 ms, the average values of the particle flux and the particle density gradient are identical under all conditions, but in the other time interval they change. They reduce with the simultaneous application of biasing and RHF. The same results obtain from the histogram of the particle flux and the gradient of the particle density and the particle diffusion coefficient. Consequently, the simultaneous application of biasing and RHF is more effective for the plasma confinement.
The fastest drop climbing on a wet conical fibre
Authors: Li Er Qiang , Thoroddsen Sigurdur T.
Published: May 2013

We use high-speed video imaging to study the capillary-driven motion of a micro-droplet along the outside of a pre-wetted conical fiber. The cones are fabricated on a glass-puller with tip diameters as small as 1 μm, an order of magnitude smaller than in previous studies. The liquid is fed through the hollow fiber accumulating at the fiber tip to form droplets. The droplets are initially attached to the opening as they grow in size before detaching and traveling up the cone. This detachment can produce a transient oscillation of high frequency. The spatial variation of the capillary pressure drives the droplets towards the wider side of the cone. Various liquids were used to change the surface tension by a factor of 3.5 and viscosity by a factor of 1500. Within each droplet size and viscous-dissipation regime, the data for climbing speeds collapse on a single curve. Droplets traveling with and against gravity allow us to pinpoint the absolute strength of the driving capillary pressure and viscous stresses and thereby determine the prefactors in the dimensionless relationships. The motions are consistent with earlier results obtained from much larger cones. Translation velocities up to 270 mm/s were observed and overall the velocities follow capillary-viscous scaling, whereas the speed of the fastest droplets is limited by inertia following their emergence at the cone tip.
Enhanced nonlinear interaction of powerful electromagnetic waves with ionospheric plasma near the second electron gyroharmonic
Authors: Istomin Ya. N. , Leyser T. B.
Published: May 2013

Plasma experiments in which a powerful electromagnetic pump wave is transmitted into the ionosphere from the ground give access to a rich range of phenomena, including gyroharmonic effects when the pump frequency is near an harmonic of the ionospheric electron gyrofrequency. For pump frequencies close to the second gyroharmonic, experiments show a strong enhancement, as observed in radar scatter from pump-induced geomagnetic field-aligned density striations and optical emissions. This is in contrast to the case at the third harmonic and higher at which most of the effects are instead suppressed. We show theoretically that electrostatic oscillations can be localized in density inhomogeneities associated with small scale striations. The localized field is a mixture of the electron Bernstein and upper hybrid modes when the pump frequency is near the second gyroharmonic. The coupling of the modes is enabled by a symmetry feature of the linear electron Bernstein and upper hybrid dispersion properties that occur only near the second gyroharmonic. Electron acceleration inside the density inhomogeneities by localized azimuthal electrostatic oscillations is more efficient near the second gyroharmonic than at higher frequencies, consistent with the observed enhancements.
Influence of fluorine on the fiber resistance studied through the nonbridging oxygen hole center related luminescence
Authors: Vaccaro L. , Cannas M. , Girard S. , Alessi A. , Morana A. , Boukenter A. , Ouerdane Y. , Boscaino R.
Published: May 2013

The distribution of Non-Bridging Oxygen Hole Centers (NBOHCs) in fluorine doped optical fibers was investigated by confocal microluminescence spectroscopy, monitoring their characteristic 1.9 eV luminescence band. The results show that these defects are generated by the fiber drawing and their concentration further increases after γ irradiation. The NBOHC concentration profile along the fiber provides evidence for an exponential decay with the fluorine content. This finding agrees with the role of fluorine in the fiber resistance and is discussed, from the microscopic point of view, by looking at the conversion mechanisms from strained bonds acting as precursors.
Conductive atomic force microscopy study of single molecule electron transport through the Azurin-gold nanoparticle system
Authors: Raccosta Samuele , Baldacchini Chiara , Rita Bizzarri Anna , Cannistraro Salvatore
Published: May 2013

Transduction of biorecognition events into electrical signals through integration of single redox metalloproteins in bioelectronic nanodevices requires both a reliable electrical contact between the biomolecule and the metallic electrode and an efficient overall conduction mechanism. These conditions have been met in the hybrid system obtained by linking gold nanoparticles on top of Azurin proteins, in turn assembled on gold surfaces. Such an assembling strategy, combined with a conductive atomic force microscopy investigation, has allowed us to put into evidence an unprecedented matching between current and topography features and to attribute the intramolecular charge transport to a non-resonant tunnelling mechanism.
Alumina reduction by laser sustained plasma for aluminum-based renewable energy cycling
Authors: Matsui Makoto , Fukuji Naohiro , Nakano Masakatsu , Komurasaki Kimiya , Arakawa Yoshihiro , Goto Tetsuya , Shirakata Hirofumi
Published: May 2013

A novel alumina (Al2O3) reduction technique for a renewable energy cycling system based on aluminum is proposed. Al2O3 powder was fed into laser-sustained plasma and thermally dissociated. The produced Al was expanded to supersonic speeds through a nozzle. From the Al and argon line distributions in the flow direction, it was found that Al remained in the dissociated state. A water-cooled copper tube was inserted in the flow to collect Al. X-ray analysis indicated that elemental Al was observed on the surface of the tube. The maximum value of the estimated reduction efficiency was 5%.
Plasmonic enhancement of photocurrent in MoS2 field-effect-transistor
Authors: Lin Jiadan , Li Hai , Zhang Hua , Chen Wei
Published: May 2013

The two-dimensional material, molybdenum disulfide (MoS2), has attracted considerable attention for numerous applications in optoelectronics. Here, we demonstrate a plasmonic enhancement of photocurrent in MoS2 field-effect-transistor decorated with gold nanoparticles, with significantly enhanced photocurrent peaked at the plasmon resonant wavelength around 540 nm. Our findings offer a possibility to realize wavelength selectable photodetection in MoS2 based phototransistors.
Two-photon nanolithography of positive photoresist thin film with ultrafast laser direct writing
Authors: Cao Hong-Zhong , Zheng Mei-Ling , Dong Xian-Zi , Jin Feng , Zhao Zhen-Sheng , Duan Xuan-Ming
Published: May 2013

The authors investigate two-photon nanolithography of a positive photoresist thin film and the influence factor of spatial resolution. A spatial resolution of 85 nm, about one-ninth of the laser wavelength at 780 nm, has been realized by using commercial positive AZ P4620 photoresist. Theoretical analysis based on the exposure kinetics of photoactive compound of diazonaphthoquinone is consistent with experimental results. The trench's cross-section shape and spatial resolution are influenced by the standing wave interference caused by the incident and reflected light. This study would provide a protocol for fabricating micro/nanodevices by femtosecond laser direct writing of positive photoresists.
A micro-structured ion-implanted magnonic crystal
Authors: Obry Björn , Pirro Philipp , Brächer Thomas , Chumak Andrii V. , Osten Julia , Ciubotaru Florin , Serga Alexander A. , Fassbender Jürgen , Hillebrands Burkard
Published: May 2013

We investigate spin-wave propagation in a microstructured magnonic-crystal waveguide fabricated by localized ion implantation. The irradiation caused a periodic variation in the saturation magnetization along the waveguide. As a consequence, the spin-wave transmission spectrum exhibits a set of frequency bands, where spin-wave propagation is suppressed. A weak modification of the saturation magnetization by 7% is sufficient to decrease the spin-wave transmission in the band gaps by a factor of 10. These results evidence the applicability of localized ion implantation for the fabrication of efficient micron- and nano-sized magnonic crystals for magnon spintronic applications.
Modeling of trap assisted interfacial charge transfer in dye sensitized solar cells
Authors: Nepal Jeevan , Sadegh Mottaghian Seyyed , Biesecker Matt , Farrokh Baroughi Mahdi
Published: May 2013

This paper presents a model for charge transport in dye sensitized solar cells based on the physics of electron capture, electron emission, oxidation, and reduction processes mediated by deep interfacial trap states at TiO2/dye/electrolyte interfaces. This model suggests that electron back injection from the conduction band of TiO2 to electrolyte is due to trapping of conduction band electrons by deep states followed by reduction processes at the interface. The simulated dark IV, illuminated IV, and quantum efficiency characteristics of dye sensitized solar cells based on this model are consistent with experimental results.
Interfacial chemistry and valence band offset between GaN and Al2O3 studied by X-ray photoelectron spectroscopy
Authors: Duan T. L. , Pan J. S. , Ang D. S.
Published: May 2013

The interface region between Ga-face n-type GaN and Al2O3 dielectric (achieved via atomic-layer deposition or ALD) is investigated by X-ray photoelectron spectroscopy (XPS). An increase in the Ga-O to Ga-N bond intensity ratio following Al2O3 deposition implies that the growth of an interfacial gallium sub-oxide (GaOx) layer occurred during the ALD process. This finding may be ascribed to GaN oxidation, which may still happen following the reduction of a thin native GaOx by trimethylaluminum (TMA) in the initial TMA-only cycles. The valence band offset between GaN and Al2O3, obtained using both core-level and valence band spectra, is found to vary with the thickness of the deposited Al2O3. This observation may be explained by an upward energy band bending at the GaN surface (due to the spontaneous polarization induced negative bound charge on the Ga-face GaN) and the intrinsic limitation of the XPS method for band offset determination.
Overexpression of GsCBRLK from Glycine soja enhances tolerance to salt stress in transgenic alfalfa (Medicago sativa)
Authors: Bai Xi , Liu Jing , Tang Lili , Cai Hua , Chen Ming , Ji Wei , Liu Ying , Zhu Yanming
Published: May 2013

GsCBRLK encodes a novel plant-specific calcium-dependent calmodulin-binding receptor-like kinase from Glycine soja Siebold & Zucc. In our previous study, GsCBRLK was found to be a positive regulator of plant tolerance to salt and abscisic acid (ABA) stress. In this study we transformed alfalfa (Medicago sativa L.) with GsCBRLK to assess whether forage legumes overexpressing GsCBRLK adapt to saline soils. Results showed that transgenic alfalfa plants overexpressing GsCBRLK exhibited enhanced salt tolerance. Transgenic alfalfa grew well in the presence of 300 mM NaCl for 15 days, whereas wild-type (WT) plants exhibited severe chlorosis and growth retardation. Although transgenic alfalfa grew slowly and even had yellow leaves under the 400 mM NaCl treatment, most of the WT plants exhibited more severe chlorosis and did not survive. In addition, samples from transgenic and WT plants treated with 300 mM NaCl for 0, 3, 6, 9, 12, and 15 days were selected for physiological analysis. Lower membrane leakage and malondialdehyde (MDA) content were observed in transgenic alfalfa compared with WT plants during salt treatment. The reduction of chlorophyll content in transgenic alfalfa was less than that in WT plants. Furthermore, the plants that overexpressed GsCBRLK showed enhanced superoxide dismutase (SOD) activity, less of a Na+ increase, and a greater K+ decrease than WT plants. These results indicated that the overexpression of GsCBRLK confers enhanced tolerance to salt stress in transgenic alfalfa.
Interdisciplinarity in biodiversity project evaluation: a work in progress
Authors: Cullen Ross , White Piran C. L.
Published: May 2013

A range of methodological frameworks is available to assist decision-makers with evaluations of projects concerned with biodiversity conservation (the protection, management or restoration of biodiversity), but their uptake has been relatively limited. Some researchers suggest a lack of research interest to be one contributory factor, in particular in relation to the application of interdisciplinary approaches that integrate methods from the natural and social sciences, despite the insights that such approaches can bring. We evaluated this assertion by examining the provenance of some examples of current research in this area. Specifically, we compared two exemplar papers published in a conservation journal and one in an interdisciplinary ecological economics journal. We scored the cited references in each paper according to standard subject categories. These scores were then weighted and aggregated to give an overall quantified subject category distribution for each of the three focal papers. Comparison of the three papers revealed an expected dominance of subject categories most closely aligned with ecological science. However, there were different patterns of provenance in the three papers. One paper from the conservation journal was dominated by citations of other papers in the biodiversity conservation literature. The second paper from the conservation journal and the paper from the ecological economics journal displayed similar overall patterns of disciplinary provenance, although they diverged in disciplinary provenance for the less commonly cited disciplines, such as the social sciences. Our results suggest that research in biodiversity project evaluation may be developing along at least three, relatively distinct, pathways rather than as a genuinely interconnected research theme. This is likely to hinder progress in research but also in practical application of the techniques, in terms of reducing the likelihood of identifying inadequate, inappropriate or inefficient conservation investments. There is still considerable opportunity for further collaboration in the areas of biodiversity evaluation among researchers in a range of disciplines, including ecology, economics, statistics, forestry and wildlife management. Biodiversity conservation evaluation is a growing field, but its potential is unlikely to be fulfilled unless biodiversity researchers seek to develop a more integrated community, and particularly, to learn from researchers in other disciplines where evaluation has a longer history.
Towards an understanding of the genetic basis behind 1080 (sodium fluoroacetate) tolerance and an investigation of the candidate gene ACO2
Authors: Deakin Janine E. , Cooper Desmond W. , Sinclair Jennifer J. , Herbert Catherine A. , Renfree Marilyn B. , Wakefield Matthew
Published: May 2013

Sodium fluoroacetate, commonly referred to as 1080, is a pesticide heavily used to control vertebrate pests. The development of tolerance to this poison by target species is a critical concern raised by its intensive use. Tolerance to 1080 is common amongst many native vertebrates in south-west Western Australia and is thought to be the result of a long period of coevolution with plant species that produce 1080 in their seeds and flowers. Among those vertebrate species tolerant to 1080 exposure is a subspecies of the tammar wallaby (Macropus eugenii). Tammars from Western Australia are tolerant while the subspecies present on Kangaroo Island is susceptible to 1080 exposure. The availability of genetic and genomic information, combined with a distinct difference in tolerance to 1080 between subspecies, makes the tammar wallaby an ideal species in which to study the genetic basis behind 1080 resistance. To date, research in this area has focussed on a candidate gene approach. Since 1080 inhibits the action of the mitochondrial aconitase enzyme, the aconitase gene ACO2 was considered a prime candidate for involvement in 1080 tolerance. However, sequencing of the full-length ACO2 transcript failed to identify a sequence variant between the two subspecies that would result in an amino acid change in the active site of the enzyme. Future studies will need to take a genome-wide approach to identify the gene(s) responsible for 1080 tolerance.
Foraging activity by the southern brown bandicoot (Isoodon obesulus) as a mechanism for soil turnover
Authors: Valentine Leonie E. , Anderson Hannah , Hardy Giles E. StJ. , Fleming Patricia A.
Published: May 2013

Mammals that forage for food by biopedturbation can alter the biotic and abiotic characteristics of their habitat, influencing ecosystem structure and function. Bandicoots, bilbies, bettongs and potoroos are the primary digging marsupials in Australia, although most of these species have declined throughout their range. This study used a snapshot approach to estimate the soil turnover capacity of the southern brown bandicoot (Isoodon obesulus, Shaw 1797), a persisting digging Australian marsupial, at Yalgorup National Park, Western Australia. The number of southern brown bandicoots was estimated using mark–recapture techniques. To provide an index of digging activity per animal, we quantified the number of new foraging pits and bandicoot nose pokes across 18 plots within the same area. The amount of soil displaced and physical structure of foraging pits were examined from moulds of 47 fresh foraging pits. We estimated that an individual southern brown bandicoot could create ~45 foraging pits per day, displacing ~10.74 kg of soil, which extrapolates to ~3.9 tonnes of soil each year. The digging activities of the southern brown bandicoots are likely to be a critical component of soil ecosystem processes.
Bundling ecosystem services in the Panama Canal watershed
Authors: Simonit Silvio , Perrings Charles
Published: May 2013

Land cover change in watersheds affects the supply of a number of ecosystem services, including water supply, the production of timber and nontimber forest products, the provision of habitat for forest species, and climate regulation through carbon sequestration. The Panama Canal watershed is currently being reforested to protect the dry-season flows needed for Canal operations. Whether reforestation of the watershed is desirable depends on its impacts on all services. We develop a spatially explicit model to evaluate the implications of reforestation both for water flows and for other services. We find that reforestation does not necessarily increase water supply, but does increase carbon sequestration and timber production.
Local circadian clock gates cell cycle progression of transient amplifying cells during regenerative hair cycling
Authors: Plikus Maksim V. , Vollmers Christopher , de la Cruz Damon , Chaix Amandine , Ramos Raul , Panda Satchidananda , Chuong Cheng-Ming
Published: May 2013

Significance

Here, we show that cell autonomous circadian clock optimizes physiological regeneration of hair follicles by synchronizing mitotic progression in transient amplifying hair-matrix cells. The daily mitotic rhythm makes hairs grow faster in the morning than in the evening. Also, because of high sensitivity of mitotic cells to radiation, significantly greater hair loss occurs in the morning than in the evening following exposure to the same dose of γ-radiation. These results provide a roadmap for developing new radiation therapy protocols, when radiation cytotoxicity can be either minimized or maximized by timing its delivery throughout the course of the day.
Impairing existing declarative memory in humans by disrupting reconsolidation
Authors: Chan Jason C. K. , LaPaglia Jessica A.
Published: May 2013

During the past decade, a large body of research has shown that memory traces can become labile upon retrieval and must be restabilized. Critically, interrupting this reconsolidation process can abolish a previously stable memory. Although a large number of studies have demonstrated this reconsolidation associated amnesia in nonhuman animals, the evidence for its occurrence in humans is far less compelling, especially with regard to declarative memory. In fact, reactivating a declarative memory often makes it more robust and less susceptible to subsequent disruptions. Here we show that existing declarative memories can be selectively impaired by using a noninvasive retrieval–relearning technique. In six experiments, we show that this reconsolidation-associated amnesia can be achieved 48 h after formation of the original memory, but only if relearning occurred soon after retrieval. Furthermore, the amnesic effect persists for at least 24 h, cannot be attributed solely to source confusion and is attainable only when relearning targets specific existing memories for impairment. These results demonstrate that human declarative memory can be selectively rewritten during reconsolidation.
GPR37 and GPR37L1 are receptors for the neuroprotective and glioprotective factors prosaptide and prosaposin
Authors: Meyer Rebecca C. , Giddens Michelle M. , Schaefer Stacy A. , Hall Randy A.
Published: May 2013

GPR37 (also known as Pael-R) and GPR37L1 are orphan G protein-coupled receptors that are almost exclusively expressed in the nervous system. We screened these receptors for potential activation by various orphan neuropeptides, and these screens yielded a single positive hit: prosaptide, which promoted the endocytosis of GPR37 and GPR37L1, bound to both receptors and activated signaling in a GPR37- and GPR37L1-dependent manner. Prosaptide stimulation of cells transfected with GPR37 or GPR37L1 induced the phosphorylation of ERK in a pertussis toxin-sensitive manner, stimulated
35
S-GTPγS binding, and promoted the inhibition of forskolin-stimulated cAMP production. Because prosaptide is the active fragment of the secreted neuroprotective and glioprotective factor prosaposin (also known as sulfated glycoprotein-1), we purified full-length prosaposin and found that it also stimulated GPR37 and GPR37L1 signaling. Moreover, both prosaptide and prosaposin were found to protect primary astrocytes against oxidative stress, with these protective effects being attenuated by siRNA-mediated knockdown of endogenous astrocytic GPR37 or GPR37L1. These data reveal that GPR37 and GPR37L1 are receptors for the neuroprotective and glioprotective factors prosaptide and prosaposin.
Space can substitute for time in predicting climate-change effects on biodiversity
Authors: Blois Jessica L. , Williams John W. , Fitzpatrick Matthew C. , Jackson Stephen T. , Ferrier Simon
Published: May 2013

“Space-for-time” substitution is widely used in biodiversity modeling to infer past or future trajectories of ecological systems from contemporary spatial patterns. However, the foundational assumption—that drivers of spatial gradients of species composition also drive temporal changes in diversity—rarely is tested. Here, we empirically test the space-for-time assumption by constructing orthogonal datasets of compositional turnover of plant taxa and climatic dissimilarity through time and across space from Late Quaternary pollen records in eastern North America, then modeling climate-driven compositional turnover. Predictions relying on space-for-time substitution were ∼72% as accurate as “time-for-time” predictions. However, space-for-time substitution performed poorly during the Holocene when temporal variation in climate was small relative to spatial variation and required subsampling to match the extent of spatial and temporal climatic gradients. Despite this caution, our results generally support the judicious use of space-for-time substitution in modeling community responses to climate change.
Dietary choice affects Shiga toxin-producing
Escherichia coli
(STEC) O157:H7 colonization and disease
Authors: Zumbrun Steven D. , Melton-Celsa Angela R. , Smith Mark A. , Gilbreath Jeremy J. , Merrell D. Scott , O’Brien Alison D.
Published: May 2013

Significance

We demonstrated that dietary fiber content affects susceptibility to Shiga toxin (Stx)-producing
Escherichia coli
(STEC) infection in mice. We showed that high fiber diet (HFD)-fed mice had elevated levels of butyrate, a beneficial gut metabolite that paradoxically enhances the cell-killing capacity of Stx. We also found that the amount of gut bacteria in HFD-fed mice increased whereas the percent of commensal
Escherichia
species (spp) decreased compared with animals fed a low fiber diet (LFD). These changes led to higher
E. coli
O157:H7 colonization levels, more weight loss, and greater rates of death in HFD-fed than in LFD-fed STEC-infected animals.