bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating influenza attack rates in the United States using a participatory cohort
Authors: Chunara Rumi , Goldstein Edward , Patterson-Lomba Oscar , Brownstein John S.
Published: April 2015

We considered how participatory syndromic surveillance data can be used to estimate influenza attack rates during the 2012–2013 and 2013–2014 seasons in the United States. Our inference is based on assessing the difference in the rates of self-reported influenza-like illness (ILI, defined as presence of fever and cough/sore throat) among the survey participants during periods of active vs. low influenza circulation as well as estimating the probability of self-reported ILI for influenza cases. Here, we combined Flu Near You data with additional sources (Hong Kong household studies of symptoms of influenza cases and the U.S. Centers for Disease Control and Prevention estimates of vaccine coverage and effectiveness) to estimate influenza attack rates. The estimated influenza attack rate for the early vaccinated Flu Near You members (vaccination reported by week 45) aged 20–64 between calendar weeks 47–12 was 14.7%(95% CI(5.9%,24.1%)) for the 2012–2013 season and 3.6%(−3.3%,10.3%) for the 2013–2014 season. The corresponding rates for the US population aged 20–64 were 30.5% (4.4%, 49.3%) in 2012–2013 and 7.1%(−5.1%, 32.5%) in 2013–2014. The attack rates in women and men were similar each season. Our findings demonstrate that participatory syndromic surveillance data can be used to gauge influenza attack rates during future influenza seasons.
After Dismissal: Examining the Language, Literacy, and Cognitive Skills of Children With Remediated Speech Sound Disorders
Authors: Farquharson Kelly
Published: April 2015

Speech sound disorders are a complex and often persistent disorder in young children. For many children, therapy results in successful remediation of the errored productions as well as age-appropriate literacy and academic progress. However, for some children, while they may attain age-appropriate speech production skills, they later have academic difficulties. For SLPs in the public schools, these children present as challenging in terms of both continuing treatment as well as in terms of caseload management. What happens after dismissal? Have these children truly acquired adequate speech production skills? Do they have lingering language, literacy, and cognitive deficits? The purpose of this article is to describe the language, literacy, and cognitive features of a small group of children with remediated speech sound disorders compared to their typically developing peers.
Nonlinear modelling and control of left ventricular assist device
Authors: Bakouri M.A. , Savkin A.V. , Alomari A.H.
Published: April 2015

A novel integrated approach for modelling and control of a left ventricular assist device (LVAD) to achieve a physiological perfusion in patients with heart failure (HF) is proposed. A sensorless mathematical model of an LVAD has been developed to estimate an average pump flow. An advanced physiological control algorithm using the pole placement sliding mode control (PPSMC) approach was derived based on the estimated flow. The merits of the proposed approach have been evaluated with different physiological conditions using a cardiovascular model that is previously developed and validated using data from two healthy pigs. Simulation results demonstrate that the proposed control algorithm in conjunction with the mathematical model of pump flow is able to robustly track the desired reference pump flow with small error in the presence of disturbance and uncertainties.
Racial embodiment and the affectivity of racism in young people’s film
Authors: Vitus Kathrine
Published: April 2015

This article uses a bodily and affective perspective to explore racial minority young people’s experiences of racism, as enacted (on film) through disgust and enjoyment. Applying Žižek’s ideology critical psychoanalytical perspective and Kristeva’s concept of “abjection”, the article considers race embodied, that is the racial body both partly Real (in the Lacanian sense) and a mean for the projection of ideological meanings and discursive structures, which are sustained by specific fantasies. From this perspective, the film’s affective racism is “symptomatic” of the discrepancies between, on the one hand, Danish social democratic welfare state ideology and a dominating race discourse of “equality-as-sameness”, on the other, the Real of racial embodiment, which makes the encounter with the Other traumatic and obscene. The analysis exposes the bodily and affective underside of race relations (which lead attempts to discursively undo racism to fail) and instead seeks to undermine the fantasies that sustain racial power relations.
Effect of temperature on the coherence time of a parabolic quantum dot qubit
Authors: Xiao Wei , Wang Hong-Wei
Published: April 2015

The effects of the temperature on the coherence time of a parabolic quantum dot (PQD) qubit are investigated by using the variational method of Pekar type. We obtain the ground and the first excited states’ eigenenergies and the corresponding eigenfunctions of an electron strongly coupled to bulk longitudinal optical phonons in the PQD. This two-level PQD system may be employed as a single qubit. The phonon spontaneous emission causes the decoherence of the qubit. We find that the coherence time will decrease with increasing temperature. It is an increasing function of the effective confinement length, whereas it is decreasing one of the polaron radius. We find that by changing the temperature, the effective confinement length and the polaron radius one can adjust the coherence time. Our research results would be useful for the design and implementation of the solid-state quantum computation.
The role of weak interlayer coupling in the spin-reorientation of perpendicular ultrathin Co-Fe-B/MgO-based heterostructures
Authors: Gareev R. R. , Zbarsky V. , Landers J. , Soldatov I. , Schäfer R. , Münzenberg M. , Wende H. , Grünberg P.
Published: April 2015

Ultrathin magnetic tunneling structures implicate fundamental interlayer exchange coupling between magnetic layers. Here, we describe its important role in the spin-reorientation transition of weakly coupled perpendicular ultrathin Ta/Co-Fe-B/MgO/Co-Fe-B/Ta heterostructures. Near the spin-reorientation, the domain structure is quite sensitive to weak interlayer exchange coupling. Antiferromagnetic coupling stabilizes homogeneous perpendicular magnetization at the remanence, whereas ferromagnetic coupling favors in-/out-of-plane stripe domains. Close to the spin-reorientation transition, even the subtle changes of interlayer exchange coupling can lead to reversible switching between stable in- and out-of-plane states. Our results suggest that this multi-stability caused by the interplay of perpendicular anisotropy and weak interlayer coupling can be utilized in perpendicular spin torque devices operating under reduced spin currents.
The critical current reaction on hydrostatic pressure of a superconductor–semimetal composite
Authors: Kononenko V. V. , Tarenkov V. Yu. , Dyachenko A. I. , Varukhin V. N.
Published: April 2015

The transport characteristics of a composite consisting of microparticles of a superconductor MgB2 and nanopowder of a ferromagnetic half-metal La0.7Ca0.3MnO3 (LCMO) were investigated under hydrostatic compression. It was observed that as the concentration of the LCMO manganite is increased above the percolation threshold of MgB2, the superconducting current flows through the superconductor–ferromagnet–superconductor chains with the LCMO thickness exceeding the magnetic coherence length ξM in the half-metal (ξM ≤ 10 Å) by an order of magnitude. This behavior can be attributed to the presence of triplet superconducting correlations in the half-metal, which arise due to the spin-active surface of LCMO nanograins. An increase in pressure led to an increase in the critical current of the MgB2–LCMO composite, while the critical current and the transition temperature of pure MgB2 decreased under pressure.
Low-temperature photoluminescence in NixMg1−xO nanocrystals
Authors: Churmanov V. N. , Gruzdev N. B. , Sokolov V. I. , Pustovarov V. A. , Ivanov V. Yu. , Mironova-Ulmane N. A.
Published: April 2015

A study of the photoluminescence and photoluminescence excitation spectra of NixMg1−xO nanocrystals, at low-temperatures. We examine the processes of concentration quenching and supposed mechanisms of energy migration in NixMg1−xO. It is shown that the edge energies of the charge-transfer transitions in NixMg1−xO (x = 0.008) and NiO are practically identical.
Formation of low-frequency harmonics on the surface of liquid hydrogen and helium in a turbulent regime
Authors: Abdurahimov L. V. , Brazhnikov M. Yu. , Levchenko A. A. , Lihter A. M. , Remizov I. A.
Published: April 2015

The formation of harmonics at frequencies below a monochromatic pump frequency in a system of capillary-gravity waves on surfaces of liquid hydrogen and superfluid helium in a turbulent regime is studied experimentally. By choosing the spectral characteristics of the exciting force and the resolution in the spectrum of the surface oscillations, it is possible to create conditions for low-frequency wave generation by changing the boundaries of the experimental cell. For certain monochromatic pump frequencies, low-frequency harmonics are observed on liquid hydrogen surfaces only in a rectangular cell. Energy transfer to the low-frequency subharmonics, as well as to high-frequency harmonics, is caused by three-wave decay processes. An inverse cascade develops on superfluid helium surfaces in a cylindrical cell as a result of three-wave decay processes, with about 90% of the energy concentrated in the inverse cascade.
Measurement of energy gaps in superconductors by means of quantum interference devices
Authors: Bondarenko S. I. , Koverya V. P. , Krevsun A. V. , Gnezdilova L. V.
Published: April 2015

The effect of temperature on the form of discrete changes in the current in highly inductive (∼10−6 H) doubly-connected superconductors with niobium-niobium clamped point contacts is determined experimentally. The magnitude and duration of the voltage pulse on a doubly-connected superconductor is measured at the time of the discrete change in its current state. The pulse magnitude is close to the energy gap 2Δ/e of the superconductor and its duration (∼10−6 s) corresponds to the minimum possible time (∼10−12 s) for a change in the state of the contact when the depairing current through it is reached. The measurement data are discussed in terms of models of the quantum interference of currents in a doubly-connected superconductor with clamped point contacts in the form of a quantum interferometer.
Shear-driven parametric instability in a precessing sphere
Authors: Lin Yufeng , Marti Philippe , Noir Jerome
Published: April 2015

The present numerical study aims at shedding light on the mechanism underlying the precessional instability in a sphere. Precessional instabilities in the form of parametric resonance due to topographic coupling have been reported in a spheroidal geometry both analytically and numerically. We show that such parametric resonances can also develop in spherical geometry due to the conical shear layers driven by the Ekman pumping singularities at the critical latitudes. Scaling considerations lead to a stability criterion of the form |Po| > O(E4/5), where Po represents the Poincaré number and E represents the Ekman number. The predicted threshold is consistent with our numerical simulations as well as previous experimental results. When the precessional forcing is supercriticial, our simulations show evidence of an inverse cascade, i.e., small scale flows merging into large scale cyclones with a retrograde drift. Finally, it is shown that this instability mechanism may be relevant to precessing celestial bodies such as the earth and earth’s moon.
Comparison among Magnus/Floquet/Fer expansion schemes in solid-state NMR
Authors: Takegoshi K. , Miyazawa Norihiro , Sharma Kshama , Madhu P. K.
Published: April 2015

We here revisit expansion schemes used in nuclear magnetic resonance (NMR) for the calculation of effective Hamiltonians and propagators, namely, Magnus, Floquet, and Fer expansions. While all the expansion schemes are powerful methods there are subtle differences among them. To understand the differences, we performed explicit calculation for heteronuclear dipolar decoupling, cross-polarization, and rotary-resonance experiments in solid-state NMR. As the propagator from the Fer expansion takes the form of a product of sub-propagators, it enables us to appreciate effects of time-evolution under Hamiltonians with different orders separately. While 0th-order average Hamiltonian is the same for the three expansion schemes with the three cases examined, there is a case that the 2nd-order term for the Magnus/Floquet expansion is different from that obtained with the Fer expansion. The difference arises due to the separation of the 0th-order term in the Fer expansion. The separation enables us to appreciate time-evolution under the 0th-order average Hamiltonian, however, for that purpose, we use a so-called left-running Fer expansion. Comparison between the left-running Fer expansion and the Magnus expansion indicates that the sign of the odd orders in Magnus may better be reversed if one would like to consider its effect in order.
Research Update: Atmospheric pressure spatial atomic layer deposition of ZnO thin films: Reactors, doping, and devices
Authors: Hoye Robert L. Z. , Muñoz-Rojas David , Nelson Shelby F. , Illiberi Andrea , Poodt Paul , Roozeboom Fred , MacManus-Driscoll Judith L.
Published: April 2015

Atmospheric pressure spatial atomic layer deposition (AP-SALD) has recently emerged as an appealing technique for rapidly producing high quality oxides. Here, we focus on the use of AP-SALD to deposit functional ZnO thin films, particularly on the reactors used, the film properties, and the dopants that have been studied. We highlight how these films are advantageous for the performance of solar cells, organometal halide perovskite light emitting diodes, and thin-film transistors. Future AP-SALD technology will enable the commercial processing of thin films over large areas on a sheet-to-sheet and roll-to-roll basis, with new reactor designs emerging for flexible plastic and paper electronics.
Measurement and simulation of thermoelectric efficiency for single leg
Authors: Hu Xiaokai , Yamamoto Atsushi , Ohta Michihiro , Nishiate Hirotaka
Published: April 2015

Thermoelectric efficiency measurements were carried out on n-type bismuth telluride legs with the hot-side temperature at 100 and 150ߙ°C. The electric power and heat flow were measured individually. Water coolant was utilized to maintain the cold-side temperature and to measure heat flow out of the cold side. Leg length and vacuum pressure were studied in terms of temperature difference across the leg, open-circuit voltage, internal resistance, and heat flow. Finite-element simulation on thermoelectric generation was performed in COMSOL Multiphysics, by inputting two-side temperatures and thermoelectric material properties. The open-circuit voltage and resistance were in good agreement between the measurement and simulation. Much larger heat flows were found in measurements, since they were comprised of conductive, convective, and radiative contributions. Parasitic heat flow was measured in the absence of bismuth telluride leg, and the conductive heat flow was then available. Finally, the maximum thermoelectric efficiency was derived in accordance with the electric power and the conductive heat flow.
Two-dimensional instability of the bottom boundary layer under a solitary wave
Authors: Sadek Mahmoud M. , Parras Luis , Diamessis Peter J. , Liu Philip L.-F.
Published: April 2015

The objective of this paper is to establish a detailed map for the temporal instability of the bottom boundary layer (BBL) flow driven by a soliton-like wave induced pressure gradient in a U-tube-shaped tunnel, which serves as an approximation to the BBL under surface solitary waves. Both linear stability analysis and fully nonlinear two-dimensional simulations using high-order numerical methods have been carried out. The process of delineation of the stability regions as a function of boundary layer thickness-based Reynolds number of the temporally evolving base flow, Reδ, consists of two parts. In the first part, we assess the lower limit of the Reδ range within which the standard, quasi-steady, linear stability analysis is applicable when considering individual base flow profiles sampled during its transient evolution. Below this limit, transient linear stability analysis serves as a more accurate predictor of the stability properties of the base flow. In the second step, above the Reδ limit where the BBL is determined to be linearly unstable, the base flow is further classified as unconditionally stable, conditionally unstable, or unconditionally unstable in terms of its sensitivity to the amplitude and the insertion time of perturbations. Two distinct modes of instability exist in this case: post- and pre-flow-reversal modes. At a moderate value of Reδ, both modes are first observed in the wave deceleration phase. The post flow reversal mode dominates for relatively low Re and it is the one observed in Sumer et al. [“Coherent structures in wave boundary layers. Part 2. Solitary motion,” J. Fluid Mech. 646, 207 (2010)]. For Re above a threshold value of the base flow in the unconditionally unstable regime, the pre-flow reversal mode, which is longer in wavelength than its post-reversal counterpart, becomes dominant. In the same regime, the threshold Reδ value above which instability is observed in the acceleration phase of the wave is also identified. In this case, the base flow velocity profiles lack any inflection point, suggesting that the origin of such an instability is viscous. Finally, the lower Reδ limit above which quasi-steady linear stability analysis is valid may be independently obtained by adapting to the surface solitary wave BBL, an instability criterion which links the average growth rate and wave event timescale, as previously proposed in studies of the instability of the interior of progressive and solitary internal waves.
Effects of confinement on anomalies and phase transitions of core-softened fluids
Authors: Krott Leandro B. , Bordin José Rafael , Barraz Ney M. , Barbosa Marcia C.
Published: April 2015

We use molecular dynamics simulations to study how the confinement affects the dynamic, thermodynamic, and structural properties of a confined anomalous fluid. The fluid is modeled using an effective pair potential derived from the ST4 atomistic model for water. This system exhibits density, structural, and dynamical anomalies, and the vapor-liquid and liquid-liquid critical points similar to the quantities observed in bulk water. The confinement is modeled both by smooth and structured walls. The temperatures of extreme density and diffusion for the confined fluid show a shift to lower values while the pressures move to higher amounts for both smooth and structured confinements. In the case of smooth walls, the critical points and the limit between fluid and amorphous phases show a non-monotonic change in the temperatures and pressures when the nanopore size is increase. In the case of structured walls, the pressures and temperatures of the critical points varies monotonically with the pore size. Our results are explained on basis of the competition between the different length scales of the fluid and the wall-fluid interaction.
Photon acceleration in plasma wake wave
Authors: Bu Zhigang , Shen Baifei , Yi Longqing , Zhang Hao , Huang Shan , Li Shun
Published: April 2015

The photon acceleration effect in a laser wake field is investigated based on photon Hamiltonian dynamics. A test laser pulse is injected into a plasma wave at an incident angle θi, which could slow down the photon velocity along the propagating direction of the wake wave so as to increase the acceleration distance for the photons. The photon trapping condition is analyzed in detail, and the maximum frequency shift of the trapped photon is obtained. The acceleration gradient and dephasing length are emphatically studied. The compression of the test laser pulse is examined and used to interpret the acceleration process. The limit of finite transverse width of the wake wave on photon acceleration is also discussed.
Plasmon-induced transparency effect in a single circular split-ring core ring resonator side-coupled to a metal-isolator-metal waveguide
Authors: Zhu Youjiang , Wang Tao , Han Xu , Wang Boyun
Published: April 2015

We theoretically and numerically investigated the plasmon-induced transparency (PIT) effect in a single circular split-ring core ring resonator (CSRCRR) side coupled to a metal–isolator–metal waveguide, in which we can realize a single PIT effect window. The transmission line theory and the coupled mode theory are used. The results (transmission peak varies from 10% to 75%) show that the PIT window results from the destructive interference between the resonance modes in the CSRCRR. Then, the limit of wavelength detuning of the two modes in CSRCRR is studied. This work provides a new structure to realize the PIT effect and shows a new way to judge whether the phenomenon is the real PIT effect or not.
Half-metallic antiferromagnetism in double perovskite BiPbCrCuO6
Authors: Weng Ke-Chuan , Wang Y. K.
Published: April 2015

The electronic structure and magnetic properties of BiPbCrCuO6 double perovskite are investigated based on first-principles density functional calculations with generalized gradient approximation (GGA) and GGA incorporated with Coulomb correlation interaction U (GGA + U). The results suggest the half-metallic (HM) and antiferromagnetic (AFM) properties of BiPbCrCuO6 double perovskite. The HM-AFM property of the double perovskite is caused by the double-exchange mechanism between neighboring Cr5+(t2g1↓) and Cu2+(t2g3↑t2g3↓eg2↑eg↓) via the intermediate O2−(2s22p6) ion.
Optimisation of geometrical ratchets for spin-current amplification
Authors: Abdullah Ranjdar M. , Vick Andrew J. , Murphy Benedict A. , Hirohata Atsufumi
Published: April 2015

A two-dimensional model is used to study the geometrical effects of a nonmagnetic (NM) nanowire upon a spin-polarised electron current in a lateral spin-valve structure. We found that the implemented ratchet shapes at the centre of the NM have a crucial effect on the diffusive rate for up- and down-spin electrons along the wire, which leads to the amplification of non-local spin-current signals. By using our simple model, the geometries have been optimised. The calculated spin-current signals are in good qualitative agreement with our recent experimental results [Abdullah et al., J. Phys. D: Appl. Phys. 47, 482001(FTC) (2014)]. Our model may be very useful to evaluate such a geometrical effect on spin-polarised electron transport.
Effect of particle pinch on the fusion performance and profile features of an international thermonuclear experimental reactor-like fusion reactor
Authors: Wang Shijia , Wang Shaojie
Published: April 2015

The evolution of the plasma temperature and density in an international thermonuclear experimental reactor (ITER)-like fusion device has been studied by numerically solving the energy transport equation coupled with the particle transport equation. The effect of particle pinch, which depends on the magnetic curvature and the safety factor, has been taken into account. The plasma is primarily heated by the alpha particles which are produced by the deuterium-tritium fusion reactions. A semi-empirical method, which adopts the ITERH-98P(y,2) scaling law, has been used to evaluate the transport coefficients. The fusion performances (the fusion energy gain factor, Q) similar to the ITER inductive scenario and non-inductive scenario (with reversed magnetic shear) are obtained. It is shown that the particle pinch has significant effects on the fusion performance and profiles of a fusion reactor. When the volume-averaged density is fixed, particle pinch can lower the pedestal density by ∼30%, with the Q value and the central pressure almost unchanged. When the particle source or the pedestal density is fixed, the particle pinch can significantly enhance the Q value by  60%, with the central pressure also significantly raised.
Intrinsic noise induced coherence resonance in a glow discharge plasma
Authors: Shaw Pankaj Kumar , Saha Debajyoti , Ghosh Sabuj , Janaki M. S. , Iyengar A. N. Sekar
Published: April 2015

Experimental evidence of intrinsic noise induced coherence resonance in a glow discharge plasma is being reported. Initially the system is started at a discharge voltage (DV) where it exhibited fixed point dynamics, and then with the subsequent increase in the DV spikes were excited which were few in number and with further increase of DV the number of spikes as well as their regularity increased. The regularity in the interspike interval of the spikes is estimated using normalized variance. Coherence resonance was determined using normalized variance curve and also corroborated by Hurst exponent and power spectrum plots. We show that the regularity of the excitable spikes in the floating potential fluctuation increases with the increase in the DV, up to a particular value of DV. Using a Wiener filter, we separated the noise component which was observed to increase with DV and hence conjectured that noise can play an important role in the generation of the coherence resonance. From an anharmonic oscillator equation describing ion acoustic oscillations, we have been able to obtain a FitzHugh-Nagumo like model which has been used to understand the excitable dynamics of glow discharge plasma in the presence of noise. The numerical results agree quite well with the experimental results.
The universal magnetic tunnel junction logic gates representing 16 binary Boolean logic operations
Authors: Lee Junwoo , Suh Dong Ik , Park Wanjun
Published: April 2015

The novel devices are expected to shift the paradigm of a logic operation by their own nature, replacing the conventional devices. In this study, the nature of our fabricated magnetic tunnel junction (MTJ) that responds to the two external inputs, magnetic field and voltage bias, demonstrated seven basic logic operations. The seven operations were obtained by the electric-field-assisted switching characteristics, where the surface magnetoelectric effect occurs due to a sufficiently thin free layer. The MTJ was transformed as a universal logic gate combined with three supplementary circuits: A multiplexer (MUX), a Wheatstone bridge, and a comparator. With these circuits, the universal logic gates demonstrated 16 binary Boolean logic operations in one logic stage. A possible further approach is parallel computations through a complimentary of MUX and comparator, capable of driving multiple logic gates. A reconfigurable property can also be realized when different logic operations are produced from different level of voltages applying to the same configuration of the logic gate.
Influence of copper substitution on the magnetic and magnetocaloric properties of NiMnInB alloys
Authors: Pandey Sudip , Quetz Abdiel , Aryal Anil , Samanta Tapas , Dubenko Igor , Stadler Shane , Ali Naushad
Published: April 2015

The structural, magnetocaloric, and thermomagnetic properties of Ni50.51Mn34.34−xCuxIn14.14B1.01 with x = (0, 1.26, and 2.02) have been studied using room-temperature x-ray diffraction, differential scanning calorimetry (DSC), and magnetization measurements. The partial substitution of Cu for Mn was found to shift both the martensitic transition temperature (TM) and the Curie temperature (TC) to lower temperatures. The values of the latent heat (L = 9.4 J/g) and corresponding magnetic (ΔSM) and total entropy (ΔST) changes (ΔSM = 22.60 J/kg K for ΔH = 5 T and ΔST = 29.7 J/kg K) have been evaluated using magnetic and DSC measurements, respectively, for the sample with x = 1.26. Large negative values of ΔSM of −7.27 and −5.98 J/kg K for ΔH = 5 T in the vicinity of TC were observed for x = 1.26 and 2.02, respectively. It has been found that the application of hydrostatic pressure changes the magnetic ground state of the martensitic phase and increases the temperature stability of the martensitic phase. The roles of the magnetic and structural changes on the transition temperatures are discussed.
Dynamic degradation of a-InGaZnO thin-film transistors under pulsed gate voltage stress
Authors: Wang Huaisheng , Wang Mingxiang , Shan Qi
Published: April 2015

Instability of amorphous InGaZnO thin-film transistors under pulsed gate voltage (Vg) stress with steep transitions was experimentally investigated. The device threshold voltage (Vth) shifts positively depending on the number of pulse repetitions of the applied Vg pulses. For steeper pulse falling time (tf), more degradation occurs. In addition, for different base voltages of the Vg pulses, the maximum Vth degradation occurs under the condition that Vg pulses are symmetric about the flat band voltage. Such dynamic degradation is attributed to hot-carrier induced charge injection into the gate insulator and/or trapping at the interface near the source/drain regions during the tf transients.
Acoustoelectric photoresponse in graphene
Authors: Poole T. , Bandhu L. , Nash G. R.
Published: April 2015

The acoustoelectric current in graphene has been investigated as a function of illumination, using blue (450 nm) and red (735 nm) light-emitting diodes (LEDs), and surface acoustic wave (SAW) intensity and frequency. The measured acoustoelectric current increases with illumination, more than the measured change in the conductivity of the graphene, whilst retaining a linear dependence on the SAW intensity. The latter is consistent with the interaction between the carriers and SAWs being described by a relatively simple classical relaxation model suggesting that the change in the acoustoelectric current is caused by the effect of the illumination on the electronic properties of the graphene. The increase in the acoustoelectric current is greatest under illumination with the blue LED, consistent with the creation of a hot electron distribution.
Experimental insights on the electron transfer and energy transfer processes between Ce3+-Yb3+ and Ce3+-Tb3+ in borate glass
Authors: Sontakke Atul D. , Ueda Jumpei , Katayama Yumiko , Dorenbos Pieter , Tanabe Setsuhisa
Published: April 2015

A facile method to describe the electron transfer and energy transfer processes among lanthanide ions is presented based on the temperature dependent donor luminescence decay kinetics. The electron transfer process in Ce3+-Yb3+ exhibits a steady rise with temperature, whereas the Ce3+-Tb3+ energy transfer remains nearly unaffected. This feature has been investigated using the rate equation modeling and a methodology for the quantitative estimation of interaction parameters is presented. Moreover, the overall consequences of electron transfer and energy transfer process on donor-acceptor luminescence behavior, quantum efficiency, and donor luminescence decay kinetics are discussed in borate glass host. The results in this study propose a straight forward approach to distinguish the electron transfer and energy transfer processes between lanthanide ions in dielectric hosts, which is highly advantageous in view of the recent developments on lanthanide doped materials for spectral conversion, persistent luminescence, and related applications.
Significant enhancement of photovoltage in artificially designed perovskite oxide structures
Authors: Zhou Wen-jia , Jin Kui-juan , Guo Hai-zhong , He Xu , He Meng , Xu Xiu-lai , Lu Hui-bin , Yang Guo-zhen
Published: April 2015

La0.9Sr0.1MnO3/insulator/SrNb0.007Ti0.993O3 multilayer and La0.9Sr0.1MnO3/SrNb0.007Ti0.993O3/In2O3:SnO2(ITO)/La0.9Sr0.1MnO3/SrNb0.007Ti0.993O3 multilayer structures were designed to enhance the photovoltage. The photovoltages of these two structures under an illumination of 308 nm laser are 410 and 600 mV, respectively. The latter is 20 times larger than that (30 mV) observed in La0.9Sr0.1MnO3/SrNb0.007Ti0.993O3 single junction. The origin of such significant enhancement of photovoltage is discussed in this letter. These results suggest that the photoelectric property of perovskite oxides could be much improved by artificial structure designing. The enhanced photovoltaic effects have potential applications in the ultraviolet photodetection and solar cells.
Effects of electron-phonon interaction on thermal and electrical transport through molecular nano-conductors
Authors: Lü Jing-Tao , Zhou Hangbo , Jiang Jin-Wu , Wang Jian-Sheng
Published: April 2015

The topic of this review is the effects of electron-phonon interaction (EPI) on the transport properties of molecular nano-conductors. A nano-conductor connects to two electron leads and two phonon leads, possibly at different temperatures or chemical potentials. The EPI appears only in the nano-conductor. We focus on its effects on charge and energy transport. We introduce three approaches. For weak EPI, we use the nonequilibrium Green’s function method to treat it perturbatively. We derive the expressions for the charge and heat currents. For weak system-lead couplings, we use the quantum master equation approach. In both cases, we use a simple single level model to study the effects of EPI on the system’s thermoelectric transport properties. It is also interesting to look at the effect of currents on the dynamics of the phonon system. For this, we derive a semi-classical generalized Langevin equation to describe the nano-conductor’s atomic dynamics, taking the nonequilibrium electron system, as well as the rest of the atomic degrees of freedom as effective baths. We show simple applications of this approach to the problem of energy transfer between electrons and phonons.
Synthesis, Structure, and Catalytic Epoxidation Property of a New Phenolato and μ1,1,3-Azido Co-Bridged Polynuclear Manganese(III) Complex Derived from N,N′-Bis(5-methylsalicylidene)ethane-1,2-diamine
Authors: Wang Ning
Published: April 2015

A new phenolato and μ1,1,3-azido co-bridged polynuclear manganese(iii) complex has been synthesised and characterised. The structure of the complex has been confirmed by single crystal X-ray diffraction analyses. The ability of the complex to catalyse the epoxidation of styrene using PhIO or NaOCl as oxidant has been studied. Results show the catalysis to occur efficiently in the presence of PhIO and NaOCl.
Using rap music to promote adolescent health: pilot study of VoxBox
Authors: Paukste Ernesta , Harris Neil
Published: April 2015

Issue addressed

Alcohol, tobacco and other drugs (ATODs) usage among adolescents, particularly those living in lower socioeconomic communities, is a population health problem in Australia that requires innovative health promotion strategies. There is a growing recognition of the potential of arts‐based approaches to engage youth in health promoting activities. This paper presents the process evaluation of the pilot VoxBox intervention that used rap to build adolescents' awareness of risks associated with ATODs.

Methods

The VoxBox intervention was piloted in Logan, Queensland, at five high schools with 18 adolescents completing the intervention. Data collection methods included observation, focus groups, semi‐structured interviews and a survey of adolescent participants.

Results

The intervention was well received by participants and stakeholders. Three factors characterising the project's successful engagement of adolescents were: participate – go with the flow, learning from the real deal and resourced to make some noise.

Conclusion

In VoxBox, the emphasis on engaging adolescents in an activity of real interest that was appropriately resourced and delivered was central to credibility and success.
Evaluation of the pilot phase of the ‘Give up smokes for good’ social marketing campaign
Authors: Maksimovic Lauren , Shen Damien , Bandick Mark , Ettridge Kerry , Eckert Marion
Published: April 2015

Issue addressed

The prevalence of tobacco smoking among Aboriginal and Torres Strait Islander people in Australia is comparatively high. To help combat this, an Aboriginal‐specific social marketing campaign, ‘Give up smokes for good’, was piloted in South Australia in 2011.

Methods

To evaluate the campaign, a face‐to‐face survey was conducted with two samples of convenience through Aboriginal Health services in South Australia (city and regional locations; n = 190). Surveys assessed the cultural appropriateness of the campaign, campaign awareness and recognition, knowledge of the harms of smoking and smoking/quit smoking behaviours.

Results

Campaign awareness was high with 76.3% of participants aware of at least one aspect of the campaign. Participants indicated campaign materials (posters and radio ads) to be culturally appropriate. Knowledge that smoking and passive smoking caused illness was high (85.8% and 86.8%); however, knowledge of specific illnesses was not as high. Large proportions of participants had imposed bans on smoking in homes (73.2%) and in cars (75.9%).

Conclusions

Our findings suggest the ‘Give up smokes for good’ campaign reached the intended audience with high levels of campaign awareness. Results also suggest the pilot campaign made progress in achieving its communication objectives.
Post-wildfire debris flows in southern British Columbia, Canada
Authors: Jordan Peter
Published: April 2015

Several post-wildfire debris flows and other landslides occurred after the extreme wildfire season of 2003 in the southern interior of British Columbia. Such events had not been previously reported in Canada, although they are common in lower latitudes. Severe wildfire seasons also were experienced in 2007 and 2009, and additional events were observed in four fires. Post-wildfire landslides have occurred in spring, summer and fall (autumn); events have been triggered by spring snowmelt, high-intensity summer rainstorms and low-intensity fall rainstorms. Of a total of 36 documented events, 23 were debris flows, and the most common initiating mechanism was high peak flow in channels. Most sediment in these events was derived from the channels, not from erosion in burned areas. Seven of the events were infiltration-triggered debris slides, and six events were debris floods. A variety of hydrologic changes can contribute to the prevalence of post-wildfire landslides and floods, including an increase in snowmelt rate. High-severity burn in catchment headwaters above steep channels is a topographic factor favouring debris flow occurrence. These observations demonstrate that the likelihood of debris flows and other mass-movement events in susceptible terrain is significantly increased following severe wildfire in this snow-dominated environment.
Interactions of fires of neighbouring shrubs in two- and three-shrub arrangements
Authors: Dahale Ambarish , Shotorban Babak , Mahalingam Shankar
Published: April 2015

A physics-based computational model was utilised to better understand the interactions of fires generated by burning of neighbouring shrubs. The model included large-eddy simulation for flow field turbulence and a two-phase approach for the coupling of solid fuel and gas phases. Two different arrangements consisting of two and three identical shrubs placed adjacent to each other were considered. All shrubs were simultaneously ignited from their base with the aid of separate ground fuels. Both crown and ground fuels were modelled as porous media with thermophysical properties of chamise and excelsior respectively. Modelling results indicated that the peak mass-loss rate and the vertical fire spread rate within a shrub decrease when the shrub separation distance increases. At zero separation, heat release rate normalised by the number of shrubs is enhanced by 5 and 15% for the two-shrub and the three-shrub arrangements, respectively. Generation of strong vorticity by higher gravitational torque appeared to be the cause for enhanced burning in the three-shrub arrangement. This effect was seen to be much weaker for the two-shrub arrangement. Interactions between the individual fires cease for a centre-to-centre distance of 1.5 and 2 times the shrub diameter for the two-shrub and the three-shrub arrangement respectively.
Using Maxillae to Estimate Ages of Lake Trout
Authors: Wellenkamp William , He Ji X. , Vercnocke Darren
Published: April 2015

Previous evaluations of calcified structures used to estimate fish ages have not included maxillae. While otoliths are considered the superior structure for assessing the age of Lake Trout Salvelinus namaycush, it can be difficult to collect and analyze sufficient samples for annual stock assessment, particularly from recreational fisheries. We used maxilla sections to estimate ages of 1,145 Lake Trout collected from Lake Huron in 2013, including 83 fish of known age with coded wire tags (CWT). Maxilla removal was 287% faster than extraction of otoliths. Maxilla sections were cut using inexpensive tools commonly used for processing spines and fin rays. Multiple sections could be made easily from each maxilla, allowing for the use of a superior section that exhibited easily identifiable annuli; in contrast, a single cracked otolith yields only two opportunities to assign age since the cut must be made through the otolith focus. From blind estimates by two independent estimators, made without prior knowledge of the true CWT-derived ages and before the decision rules were fully developed, exact match of maxilla-based ages to the CWT-derived ages was 59–67%; agreements with a bias less than or equal to 1 year were 88–89%, and agreements with a bias less than or equal to 2 years were 94–95%. These measures were higher than those obtained using otoliths sampled from Lake Trout of the same CWT-derived ages. After analyzing the sources of errors and finalizing detailed decision rules, we found that all maxilla sections exhibited a full complement of annuli comparable with the true CWT-derived age, except for two samples affected by errors occurring during sample collection rather than during maxilla processing and interpretation.

Received December 16, 2013; accepted December 12, 2014
Combining Split-Beam and Dual-Frequency Identification Sonars to Estimate Abundance of Anadromous Fishes in the Roanoke River, North Carolina
Authors: Hughes Jacob B. , Hightower Joseph E.
Published: April 2015

Riverine hydroacoustic techniques are an effective method for evaluating abundance of upstream migrating anadromous fishes. To use these methods in the Roanoke River, North Carolina, at a wide site with uneven bottom topography, we used a combination of split-beam sonar and dual-frequency identification sonar (DIDSON) deployments. We aimed a split-beam sonar horizontally to monitor midchannel and near-bottom zones continuously over the 3-month spring monitoring periods in 2010 and 2011. The DIDSON was rotated between seven cross-channel locations (using a vertical aim) and nearshore regions (using horizontal aims). Vertical deployment addressed blind spots in split-beam coverage along the bottom and provided reliable information about the cross-channel and vertical distributions of upstream migrants. Using a Bayesian framework, we modeled sonar counts within four cross-channel strata and apportioned counts by species using species proportions from boat electrofishing and gill netting. Modeled estimates (95% credible intervals [CIs]) of total upstream migrants in 2010 and 2011 were 2.5 million (95% CI, 2.4–2.6 million) and 3.6 million (95% CI, 3.4–3.9 million), respectively. Results indicated that upstream migrants are extremely shore- and bottom-oriented, suggesting nearshore DIDSON monitoring improved the accuracy and precision of our estimates. This monitoring protocol and model may be widely applicable to river systems regardless of their cross-sectional width or profile.

Received July 16, 2014; accepted November 21, 2014
Using Larval Fish Community Structure to Guide Long-Term Monitoring of Fish Spawning Activity
Authors: Pritt Jeremy J. , Roseman Edward F. , Ross Jason E. , DeBruyne Robin L.
Published: April 2015

Larval fishes provide a direct indication of spawning activity and may therefore be useful for long-term monitoring efforts in relation to spawning habitat restoration. However, larval fish sampling can be time intensive and costly. We sought to understand the spatial and temporal structure of larval fish communities in the St. Clair–Detroit River system, Michigan–Ontario, to determine whether targeted larval fish sampling can be made more efficient for long-term monitoring. We found that larval fish communities were highly nested, with lower river segments and late-spring samples containing the highest genus richness of larval fish. We created four sampling scenarios for each river system: (1) using all available data, (2) limiting temporal sampling to late spring, (3) limiting spatial sampling to lower river segments only, and (4) limiting both spatial and temporal sampling. By limiting the spatial extent of sampling to lower river sites and/or limiting the temporal extent to the late-spring period, we found that effort could be reduced by more than 50% while maintaining over 75% of the observed and estimated total genus richness. Similarly, limiting the sampling effort to lower river sites and/or the late-spring period maintained between 65% and 93% of the observed richness of lithophilic-spawning genera and invasive genera. In general, community composition remained consistent among sampling scenarios. Targeted sampling offers a lower-cost alternative to exhaustive spatial and temporal sampling and may be more readily incorporated into long-term monitoring.

Received August 14, 2014; accepted November 28, 2014
Measurement Error in Angler Creel Surveys
Authors: Alexiades Alexander V. , Marcy-Quay Benjamin , Sullivan Patrick J. , Kraft Clifford E.
Published: April 2015

Information on fishing effort, catch, harvest, and survival is important for formulating management policies in freshwater fisheries and for understanding the dynamics of aquatic ecosystems. Fisheries managers often use creel surveys to assess fisheries statistics. The mean-of-ratios estimator has been traditionally used for estimating catch rates from incomplete angler trips, whereas the ratio-of-means estimator is preferable for estimating catch rates from completed trips. Recent studies have demonstrated persistent bias when comparing the two estimators based on catch data from incomplete and completed trips from the same sample of anglers; these studies have promoted the use of linear regression models to correct for apparent bias in catch rates based on incomplete trips. However, the reported bias in catch rate estimates may be an artifact of measurement error in incomplete-trip angler surveys rather than bias from the estimates themselves. Furthermore, we contend that ordinary least-squares linear regression is inappropriate to correct for this apparent bias because measurement error is present in both the response variable (e.g., catch rate estimated from completed trips) and the explanatory variable (e.g., catch rate estimated from incomplete trips), leading to low estimates of the slope of the relationship. Alternatively, when both variables contain measurement error, model II regression methods provide less-biased estimates. Using interview data (incomplete trips) from roving creel surveys and a catch card survey (completed trips) conducted on the same sample of anglers, we compared catch rates derived from both estimators. Our results show that linear regression underestimates the slope of the relationship and that model II regression reduces bias and provides a more accurate estimate.

Received April 26, 2014; accepted November 26, 2014