bluuebunny/crossref_metadata_2025 huggingface dataset:
Classical gauge theory in Riem
Authors: Gomes Henrique de A.
Published: August 2011

In the geometrodynamical setting of general relativity in Lagrangian form, the objects of study are the Riemannian metrics (and their time derivatives) over a given 3-manifold M. It is our aim in this paper to study some geometrical aspects of the space \documentclass[12pt]{minimal}\begin{document}$\mathcal {M}:=$\end{document}M:=Riem(M) of all metrics over M. For instance, the Hamiltonian constraints by themselves do not generate a group, and thus its action on Riem(M) cannot be viewed in a geometrical gauge setting. It is possible to do so for the momentum constraints however. Furthermore, in view of the recent results representing GR as a dual theory, invariant under foliation preserving 3–diffeomorphisms and 3D conformal transformations, but not under refoliations, we are justified in considering the gauge structure pertaining only to the groups \documentclass[12pt]{minimal}\begin{document}$\mathcal {D}$\end{document}D of diffeomorphisms of M, and \documentclass[12pt]{minimal}\begin{document}$\mathcal {C}$\end{document}C, of conformal diffeomorphisms on M. For these infinite-dimensional symmetry groups, \documentclass[12pt]{minimal}\begin{document}$\mathcal {M}$\end{document}M has a natural principal fiber bundle structure, which renders the gravitational field amenable to the full range of gauge-theoretic treatment. The aim of the paper is to use the geometrical structure present in the configuration space of general relativity to build gauge connection forms. The interpretation of the gauge connection form for the 3-diffeomorphism group is that it yields parallel translation of coordinates. For the conformal group, it yields parallel translation of scale. We focus on the concept of a gauge connection forms for these structures and construct explicit formulae for supermetric-induced gauge connections. To apply the formalism, we compute general properties for a specific connection bearing strong resemblance to the one naturally induced by the deWitt supermetric, showing it has desirable relationalist properties.
Order parameters for the multistep crystallization of clathrate hydrates
Authors: Jacobson Liam C. , Matsumoto Masakazu , Molinero Valeria
Published: August 2011

Recent reports indicate that the crystallization of clathrate hydrates occurs in multiple steps that involve amorphous intermediates and metastable clathrate crystals. The elucidation of the reaction coordinate for clathrate crystallization requires the use of order parameters able to identify the reactants, products, and intermediates in the crystallization pathway. Nevertheless, existing order parameters cannot distinguish between amorphous and crystalline clathrates or between different clathrate crystals. In this work, we present the first set of order parameters that discern between the sI and sII clathrate crystals, the amorphous clathrates, the blob of solvent-separated guests and the liquid solution. These order parameters can be used to monitor the advance of the crystallization and for the efficient implementation of methods to sample the rare clathrate nucleation events in molecular simulations. We illustrate the use of these order parameters in the analysis of the growth and the dissolution of clathrate crystals and the spontaneous nucleation and growth of clathrates under conditions of high supercooling.
On the structure of ${\rm End}_{u_k(2)}(\Omega _k^{\otimes r})$ End uk(2)(Ωk⊗r)
Authors: Fu Qiang , Yang Qunguang
Published: August 2011

Let uk(2) be the infinitesimal quantum \documentclass[12pt]{minimal}\begin{document}$\mathfrak {gl}_2$\end{document}gl2 over k, where k is a field containing an lth primitive root ε of 1 with l ⩾ 3 odd. We will determine the basic algebra for \documentclass[12pt]{minimal}\begin{document}${\rm End}_{u_k(2)}(\Omega _k^{\otimes r})$\end{document} End uk(2)(Ωk⊗r), where Ωk is the natural module for uk(2).
Biosensing in a microelectrofluidic system using optical whispering-gallery mode spectroscopy
Authors: Huang Lei , Guo Zhixiong
Published: August 2011

Label-free detection of biomolecules using an optical whispering-gallery mode sensor in a microelectrofluidic channel is simulated. Negatively charged bovine serum albumin is considered as the model protein analyte. The analyte transport in aqueous solution is controlled by an externally applied electrical field. The finite element method is employed for solving the equations of the charged species transport, the Poisson equation of electric potential, the equations of conservation of momentum and energy, and the Helmholtz equations of electromagnetic waves. The adsorption process of the protein molecules on the microsensor head surface is monitored by the resonance frequency shifts. Frequency shift caused by temperature variation due to Joule heating is analyzed and found to be negligible. The induced shifts behave in a manner similar to Langmuir-like adsorption kinetics; but the time constant increases due to the presence of the external electrical field. A correlation of the frequency shift, the analyte feed concentration in the solution, and the applied voltage gradient is obtained, in which an excellent linear relationship between the frequency shift and the analyte concentration is revealed. The applied voltage gradient enhances significantly the analyte concentration in the vicinity of the sensor surface; thus, the sensor sensitivity which has a power function of the voltage gradient with exponent 2.85 in the controlled voltage range. Simulated detection of extremely low protein concentration to the pico-molar level is carried out.
Structural and photoluminescence properties of Gd implanted ZnO single crystals
Authors: Murmu P. P. , Mendelsberg R. J. , Kennedy J. , Carder D. A. , Ruck B. J. , Markwitz A. , Reeves R. J. , Malar P. , Osipowicz T.
Published: August 2011

We present the structural and photoluminescence properties of 30 keV gadolinium implanted and subsequently annealed zinc oxide (ZnO) single crystals. Rutherford backscattering and channeling results reveal a low surface region defect density which was reduced further upon annealing. For low implantation fluence, around 85% of the Gd atoms are estimated to be in sites aligned with the ZnO lattice, while for higher fluences the Gd is largely disordered and likely forms precipitates. The Raman spectra of the implanted samples show defect-induced modes, which match the one-phonon density of states for the most heavily implanted samples. Annealing eliminates these features implying the removal of Gd-associated lattice disorder. Low temperature photoluminescence spectra revealed a red-shift in the defect emission, from green to orange/yellow, indicating the suppression of a deep level, which is thought to be due to oxygen vacancies. It is suggested that the orange/yellow emission is unmasked when the green emission is quenched by the presence of the implanted Gd atoms.
Thermal properties of mid-infrared colloidal quantum dot detectors
Authors: Lhuillier Emmanuel , Keuleyan Sean , Rekemeyer Paul , Guyot-Sionnest Philippe
Published: August 2011

HgTe colloidal quantum dot films are studied for photodetection over the 3–5 μm atmospheric transparency window. The temperature dependence of the conductivity indicates that the material behaves approximately as an intrinsic semiconductor. In photoconduction, the responsivity can be as high as several hundred mA W−1 at room temperature. The dark current presents 1/f noise which is larger than that for homogeneous conductors, and this noise decreases with temperature. A specific detectivity of 2 × 109 Jones is obtained for a sample with a 6 μm cut-off wavelength at 130 K. These values are obtained for the thickest films studied (∼400 nm) and whose thicknesses are still much less than the optical absorption length. The time response can be faster than 100 ns.
Ion acoustic solitary waves and double layers with nonextensive electrons and thermal positrons
Authors: Sahu Biswajit
Published: August 2011

By using Sagdeev’s pseudopotential technique, the problem of arbitrary amplitude ion acoustic solitary waves (IASWs) is discussed for a plasma comprising nonextensive electrons and thermal positrons. The standard normal-mode analysis is used to study the dispersion relation for linear waves. It is found that the present plasma model supports IASWs having positive as well as negative potential well. The influence of nonextensive electrons on the present plasma model is investigated for the existence of solitary waves. The investigation shows that the solitary structure ceases to exist when the parameter q crosses a certain limit. It is also found that both the small amplitude compressive and rarefactive double layer solution can exist in such a plasma system in some parametric region. It is shown that solitary structures and double layers are affected by nonextensivity, as well as by relevant plasma parameters.
Glass composition and excitation wavelength dependence of the luminescence of Eu3+ doped lead borate glass
Authors: Wen Hongli , Duan Chang-Kui , Jia Guohua , Tanner Peter A. , Brik Mikhail G.
Published: August 2011

This work explores the relationship between the bandwidth of luminescence spectral features and their relative intensities, using glasses doped with europium, Eu3+, over a wide composition range. Glasses of composition (B2O3)70(PbO)29(0.5Eu2O3)1 and (B2O3)z(PbO)99.6-z(0.5Eu2O3)0.4, (z = 20, 30, 40, 60, 70), were prepared by the melting-quenching technique. Variable-wavelength measurements by the prism-coupling method enabled interpolation of refractive index at selected wavelengths. Diffuse reflectance spectra confirmed the incorporation of Eu3+ into the glass, and scanning electron microscopy displayed that this was in a homogeneous manner. Vibrational spectra showed a change in boron coordination from BO3 to BO4 units with increase of PbO content in the glass. Multi-wavelength excited luminescence spectra were recorded for the glasses at temperatures down to 10 K and qualitative interpretations of spectral differences with change of B2O3 content are given. The quantitative analysis of 5D0 luminescence intensity-bandwidth relations showed that although samples with higher boron content closely exhibit a simple proportional relationship with band intensity ratios, as expected from theory, the expression needs to be slightly modified for those with low boron content. The Judd-Ofelt intensity analysis of the 5D0 emission spectra under laser excitations at low temperature gives Ω2 values within the range from (3.9–6.5) × 10−20 cm2, and Ω4 in the range from (4.1–7.0) × 10−20 cm2, for different values of z. However, no clear monotonic relation was found between the parameter values and composition. The Judd-Ofelt parameters are compared with those from other systems doped with Eu3+ and are found to lie in the normal ranges for Eu3+-doped glasses. The comparison of parameter values derived from the 10 K spectra with those from room temperature spectra for our glasses, which are fairly constant for different compositions, shows that site selection occurs at low temperature.
The hierarchical architecture effect on the microwave absorption properties of cobalt composites
Authors: Liu T. , Zhou P. H. , Xie J. L. , Deng L. J.
Published: August 2011

The effect of hierarchical architecture on the electromagnetic properties of microwave absorber candidates is important for absorption design. This work prepares dendritic cobalt powders by a simple hydrothermal reduction method. The study of microwave electromagnetic properties reveals that dielectric polarization relaxation dominates over the power loss owing to the superstructure with a large volume of branches. Compared with the conventional spherical filler, a composite consisting of dendritic filler shows an improved electromagnetic absorption performance in low frequencies due to the enhancement of both the impedance match to free air and the loss induced by interfacial polarization and Ohmic resistance.
The elimination of interface charge density singularity in single layer organic semiconductor structures
Authors: Cvikl B.
Published: August 2011

The arguments are presented that the assumption of a zero electric field at the charge carrier injection electrode/organic interface, as assumed by the current-voltage model of shallow traps occupying a single energy level within the organic semiconductor charge transport band as well as by the model of traps exponentially distributed in energy, is invalid in principle. In consequence of this fact, it is shown that the value of material parameters is strongly related to the bias dependent non-zero electric field at the charge-injecting interface. A set of published room temperature current-voltage data of a single layer, electron-only, metal/organic semiconductor structure is used in order to show explicitly that the singularity of free (or total) electron charge carriers at the injecting interface and the associated space charge limited current characteristics reflects an unrealistic assumption of the above two models. For the model of traps exponentially distributed in energy, the charge traps density and the associated non-zero interfacial electric field are uniquely determined under a subsidiary condition of minimal energy of charges in an external electric field. The resulting (bias dependent) spatial distribution of the internal electric field and the spatial dependence of the electron density turns out to be practically uniform throughout the organic sample in agreement with the predictions of the model of shallow traps occupying a single energy level. The internal electric field and the charge density within the narrow midway region of the organic are, at each bias, invariant to the variation of the trap density and the associated interfacial electric field. It is also shown that the drift-diffusion electron transport interpreted in terms of the model of shallow traps occupying a single energy level is incompatible with the published measurements.
Extended light scattering model incorporating coherence for thin-film silicon solar cells
Authors: Lanz Thomas , Ruhstaller Beat , Battaglia Corsin , Ballif Christophe
Published: August 2011

We present a comprehensive scalar light-scattering model for the optical simulation of silicon thin film solar cells. The model integrates coherent light propagation in thin layers with a direct, non-iterative treatment of light scattered at rough layer interfaces. The direct solution approach ensures computational efficiency, which is a key advantage for extensive calculations in the context of evaluation of different cell designs and parameter extraction. We validate the model with experimental external quantum efficiency spectra of state-of-the-art microcrystalline silicon solar cells. The simulations agree very well with measurements for cells deposited on both rough and flat substrates. The model is then applied to study the influence of the absorber layer thickness on the maximum achievable photocurrent for the two cell types. This efficient numerical framework will enable a quantitative model-based assessment of the optimization potential for light trapping in textured thin film silicon solar cells.
Optimization of out-of-plane magnetized Co/Pt multilayers with resistive buffer layers
Authors: Emori Satoru , Beach Geoffrey S. D.
Published: August 2011

Ta oxide (TaOx) is investigated as a resistive buffer layer for the growth of high-quality Co/Pt multilayers with perpendicular magnetic anisotropy (PMA). The Pt/(Co/Pt)3 films grown on TaOx buffer layers exhibit stronger PMA than those grown on Pt buffer layers, and are of comparable quality to films grown on metallic Ta. The optimized multilayers with TaOx buffer layers remain out-of-plane magnetized for Co layer thicknesses up to 10 Å without introducing a metallic current-shunting path, making these films attractive for spintronic devices using spin-polarized current.
An ultra-low energy (30–200 eV) ion-atomic beam source for ion-beam-assisted deposition in ultrahigh vacuum
Authors: Mach Jindřich , Šamořil Tomáš , Voborný Stanislav , Kolíbal Miroslav , Zlámal Jakub , Spousta Jiří , Dittrichová Libuše , Šikola Tomáš
Published: August 2011

The paper describes the design and construction of an ion-atomic beam source with an optimized generation of ions for ion-beam-assisted deposition under ultrahigh vacuum (UHV) conditions. The source combines an effusion cell and an electron impact ion source and produces ion beams with ultra-low energies in the range from 30 eV to 200 eV. Decreasing ion beam energy to hyperthermal values (≈101 eV) without loosing optimum ionization conditions has been mainly achieved by the incorporation of an ionization chamber with a grid transparent enough for electron and ion beams. In this way the energy and current density of nitrogen ion beams in the order of 101 eV and 101 nA/cm2, respectively, have been achieved. The source is capable of growing ultrathin layers or nanostructures at ultra-low energies with a growth rate of several MLs/h. The ion-atomic beam source will be preferentially applied for the synthesis of GaN under UHV conditions.
Modulated amplitude waves with nonzero phases in Bose-Einstein condensates
Authors: Liu Qihuai , Qian Dingbian
Published: August 2011

In this paper we give a frame for application of the averaging method to Bose-Einstein condensates (BECs) and obtain an abstract result upon the dynamics of BECs. Using the averaging method, we determine the location where the modulated amplitude waves (periodic or quasi-periodic) exist and obtain that all these modulated amplitude waves (periodic or quasi-periodic) form a foliation by varying the integration constant continuously. Compared with the previous work, modulated amplitude waves studied in this paper have nontrivial phases and this makes the problem become more difficult, since it involves some singularities.
Nonlinear wave evolution and runup in an inclined channel of a parabolic cross-section
Authors: Didenkulova Ira , Pelinovsky Efim
Published: August 2011

Nonlinear wave dynamics of long water waves is studied in an inclined channel of a parabolic cross-section. Such situation occurs when sea waves enter and propagate in a narrow bay or a fjord. Nonlinear shallow water equations can in this case be written in 1D form and solved analytically with the use of the hodograph transformation. This approach generalizes the well-known Carrier-Greenspan transformation for long wave runup on a plane beach. In the case of an inclined channel of a parabolic cross-section, it leads to the associated spherical symmetrical linear wave equation. As a result, the solution of the Cauchy problem can be expressed in terms of elementary functions and has a simple form (with respect to analysis) for any kind of initial conditions. Wave regimes associated with various localized initial conditions, corresponding to problems of evolution and runup of N-waves and wind set-down and set-up relaxation, are considered and analyzed. Special attention is paid to the wave breaking criterion for waves at the coast, which appears to provide a condition of applicability for the hodograph transformation. The wave breaking condition is obtained and discussed for each of the studied problems.
Second-order nonadiabatic couplings from time-dependent density functional theory: Evaluation in the immediate vicinity of Jahn-Teller/Renner-Teller intersections
Authors: Hu Chunping , Sugino Osamu , Watanabe Kazuyuki
Published: August 2011

For a rigorous quantum simulation of nonadiabatic dynamics of electrons and nuclei, knowledge of not only the first-order but also the second-order nonadiabatic couplings (NACs) is required. Here, we propose a method to efficiently calculate the second-order NAC from time-dependent density functional theory (TDDFT), on the basis of the Casida ansatz adapted for the computation of first-order NAC, which has been justified in our previous work and can be shown to be valid for calculating second-order NAC between ground state and singly excited states within the Tamm-Dancoff approximation. Test calculations of the second-order NAC in the immediate vicinity of Jahn-Teller and Renner-Teller intersections show that calculation results from TDDFT, combined with modified linear response theory, agree well with the prediction from the Jahn-Teller/Renner-Teller models. Contrary to the diverging behavior of the first-order NAC near all types of intersection points, the Cartesian components of the second-order NAC are shown to be negligibly small near Renner-Teller glancing intersections, while they are significantly large near the Jahn-Teller conical intersections. Nevertheless, the components of the second-order NAC can cancel each other to a large extent in Jahn-Teller systems, indicating the background of neglecting the second-order NAC in practical dynamics simulations. On the other hand, it is shown that such a cancellation becomes less effective in an elliptic Jahn-Teller system and thus the role of second-order NAC needs to be evaluated in the rigorous framework. Our study shows that TDDFT is promising to provide accurate data of NAC for full quantum mechanical simulation of nonadiabatic processes.
Enhanced gas-flow-induced voltage in graphene
Authors: Yin Jun , Zhou Jianxin , Li Xuemei , Chen Yaqing , Tai Guoan , Guo Wanlin
Published: August 2011

We find experimentally that gas-flow-induced voltage in monolayer graphene is more than twenty times of that in bulk graphite. Examination over samples with sheet resistances ranging from 307 to 1600 Ω/sq shows that the induced voltage increases with the electric resistance and can be further improved by controlling the quality and doping level of graphene. The induced voltage is nearly independent of the substrate materials and can be well explained by the interplay of Bernoulli’s principle and the carrier density dependent Seebeck coefficient. The results demonstrate that graphene has great potential for flow sensors and energy conversion devices.
Wave front-ray synthesis for solving the multidimensional quantum Hamilton-Jacobi equation
Authors: Wyatt Robert E. , Chou Chia-Chun
Published: August 2011

A Cauchy initial-value approach to the complex-valued quantum Hamilton-Jacobi equation (QHJE) is investigated for multidimensional systems. In this approach, ray segments foliate configuration space which is laminated by surfaces of constant action. The QHJE incorporates all quantum effects through a term involving the divergence of the quantum momentum function (QMF). The divergence term may be expressed as a sum of two terms, one involving displacement along the ray and the other incorporating the local curvature of the action surface. It is shown that curvature of the wave front may be computed from coefficients of the first and second fundamental forms from differential geometry that are associated with the surface. Using the expression for the divergence, the QHJE becomes a Riccati-type ordinary differential equation (ODE) for the complex-valued QMF, which is parametrized by the arc length along the ray. In order to integrate over possible singularities in the QMF, a stable and accurate Möbius propagator is introduced. This method is then used to evolve rays and wave fronts for four systems in two and three dimensions. From the QMF along each ray, the wave function can be easily computed. Computational difficulties that may arise are described and some ways to circumvent them are presented.
Floating electrode microelectromechanical system capacitive switches: A different actuation mechanism
Authors: Papaioannou G. , Giacomozzi F. , Papandreou E. , Margesin B.
Published: August 2011

The paper investigates the actuation mechanism in floating electrode microelectromechanical system capacitive switches. It is demonstrated that in the pull-in state, the device operation turns from voltage to current controlled actuation. The current arises from Poole-Frenkel mechanism in the dielectric film and Fowler-Nordheim in the bridge-floating electrode air gap. The pull-out voltage seems to arise from the abrupt decrease of Fowler-Nordheim electric field intensity. This mechanism seems to be responsible for the very small difference with respect to the pull-in voltage.
Generation of high power tunable multicycle teraherz pulses
Authors: Chen Zhao , Zhou Xibin , Werley Christopher A. , Nelson Keith A.
Published: August 2011

We demonstrate generation of high-power, multicycle, and frequency-tunable terahertz pulses with microjoule energies by tilting the intensity front of a quasi-sinusoidal intensity-modulated optical waveform. The spatiotemporally shaped waveform undergoes difference-frequency mixing in lithium niobate, generating a THz phonon-polariton wave whose electromagnetic component is coupled out to free space. The narrowband THz spectrum is tunable between 0.3–1.3 THz, with adjustable bandwidths generally less than 0.1 THz. At 10 Hz and 1 kHz repetition rates, 10 μJ and 1 μJ THz pulse energies are achieved, respectively, over a broad frequency range.
Extracting 2D IR frequency-frequency correlation functions from two component systems
Authors: Fenn Emily E. , Fayer M. D.
Published: August 2011

The center line slope (CLS) method is often used to extract the frequency-frequency correlation function (FFCF) from 2D IR spectra to delineate dynamics and to identify homogeneous and inhomogeneous contributions to the absorption line shape of a system. While the CLS method is extremely efficient, quite accurate, and immune to many experimental artifacts, it has only been developed and properly applied to systems that have a single vibrational band, or to systems of two species that have spectrally resolved absorption bands. In many cases, the constituent spectra of multiple component systems overlap and cannot be distinguished from each other. This situation creates ambiguity when analyzing 2D IR spectra because dynamics for different species cannot be separated. Here a mathematical formulation is presented that extends the CLS method for a system consisting of two components (chemically distinct uncoupled oscillators). In a single component system, the CLS corresponds to the time-dependent portion of the normalized FFCF. This is not the case for a two component system, as a much more complicated expression arises. The CLS method yields a series of peak locations originating from slices taken through the 2D spectra. The slope through these peak locations yields the CLS value for the 2D spectra at a given Tw. We derive analytically that for two component systems, the peak location of the system can be decomposed into a weighted combination of the peak locations of the constituent spectra. The weighting depends upon the fractional contribution of each species at each wavelength and also on the vibrational lifetimes of both components. It is found that an unknown FFCF for one species can be determined as long as the peak locations (referred to as center line data) of one of the components are known, as well as the vibrational lifetimes, absorption spectra, and other spectral information for both components. This situation can arise when a second species is introduced into a well characterized single species system. An example is a system in which water exists in bulk form and also as water interacting with an interface. An algorithm is presented for back-calculating the unknown FFCF of the second component. The accuracy of the algorithm is tested with a variety of model cases in which all components are initially known. The algorithm successfully reproduces the FFCF for the second component within a reasonable degree of error.
Charge storage characteristics of ultra-small Pt nanoparticle embedded GaAs based non-volatile memory
Authors: Jeff R. C. , Yun M. , Ramalingam B. , Lee B. , Misra V. , Triplett G. , Gangopadhyay S.
Published: August 2011

Charge storage characteristics of ultra-small Pt nanoparticle embedded devices were characterized by capacitance-voltage measurements. A unique tilt target sputtering configuration was employed to produce highly homogenous nanoparticle arrays. Pt nanoparticle devices with sizes ranging from ∼0.7 to 1.34 nm and particle densities of ∼3.3–5.9 × 1012 cm−2 were embedded between atomic layer deposited and e-beam evaporated tunneling and blocking Al2O3 layers. These GaAs-based non-volatile memory devices demonstrate maximum memory windows equivalent to 6.5 V. Retention characteristics show that over 80% charged electrons were retained after 105 s, which is promising for device applications.
Influence of tetragonal distortion on the topological electronic structure of the half-Heusler compound LaPtBi from first principles
Authors: Zhang X. M. , Wang W. H. , Liu E. K. , Liu G. D. , Liu Z. Y. , Wu G. H.
Published: August 2011

The electronic structures of tetragonally distorted half-Heusler compound LaPtBi in the C1b structure are investigated in the framework of density functional theory using the full potential linearized augmented plane with local spin density approximation method. The calculation results show that both the band structures and the Fermi level can be tuned by using either compressive or tensile in-plane strain. A large bulk band gap of 0.3 eV can be induced through the application of a compressive in-pane strain in LaPtBi with the assumption of a relaxed volume of the unit cell. Our results could serve as a guidance to realize topological insulators in half-Heusler compounds by strain engineering.
One-dimensional photonic crystal nanobeam lasers on a flexible substrate
Authors: Lu Tsan-Wen , Chiu Li-Hsun , Lin Pin-Tso , Lee Po-Tsung
Published: August 2011

We demonstrate a one-dimensional (1D) photonic crystal (PhC) nanocavity laser composed of hybrid PhC mirrors on a suspended nanobeam (NB) with very small device footprint of 8.5 × 0.57 μm2. The 0th-order mode lasing action with low threshold of 280 μW is observed. Via the optical glue stamping process, the devices are directly transferred onto a flexible polypropylene substrate. Single mode lasing action with effective threshold of 17 μW is achieved. The robust lasing properties of the device with different bending radii R from ∞ to 2.5 mm are obtained. Via finite-element method, we also theoretically address that the lasing wavelength is almost invariant when R > 1.0 mm. This flexible 1D PhC NB laser will be a good candidate for efficient nanolaser in future flexible photonic integrated circuits with ultrahigh component density.
Strain analysis of multiferroic BiFeO3-CoFe2O4 nanostructures by Raman scattering
Authors: Chaix-Pluchery O. , Cochard C. , Jadhav P. , Kreisel J. , Dix N. , Sánchez F. , Fontcuberta J.
Published: August 2011

We report a Raman scattering investigation of columnar BiFeO3-CoFe2O4 (BFO-CFO) epitaxial thin film nanostructures, where BFO pillars are embedded in a CFO matrix. The feasibility of a strain analysis is illustrated through an investigation of two nanostructures with different BFO-CFO ratios. We show that the CFO matrix presents the same strain state in both nanostructures, while the strain state of the BFO pillars depends on the BFO/CFO ratio with an increasing tensile strain along the out-of-plane direction with decreasing BFO content. Our results demonstrate that Raman scattering allows monitoring strain states in complex 3D multiferroic pillar/matrix composites.
Direct measurement of the impulse in a magnetic thrust chamber system for laser fusion rocket
Authors: Maeno Akihiro , Yamamoto Naoji , Nakashima Hideki , Fujioka Shinsuke , Johzaki Tomoyuki , Mori Yoshitaka , Sunahara Atsushi
Published: August 2011

An experiment is conducted to measure an impulse for demonstrating a magnetic thrust chamber system for laser fusion rocket. The impulse is produced by the interaction between plasma and magnetic field. In the experiment, the system consists of plasma and neodymium permanent magnets. The plasma is created by a single-beam laser aiming at a polystyrene spherical target. The impulse is 1.5 to 2.2 μNs by means of a pendulum thrust stand, when the laser energy is 0.7 J. Without magnetic field, the measured impulse is found to be zero. These results indicate that the system for generating impulse is working.
Pressure dependence of dissociation fraction and optical emission characteristics in low-pressure inductively coupled N2-Ar plasmas
Authors: Chung T. H. , Lee Y. W. , Joh H. M. , Song M. A.
Published: August 2011

A diagnostics study of low-pressure inductively coupled N2-Ar plasmas was performed by using optical emission spectroscopy (OES) and an rf-compensated Langmuir probe under the conditions of pressures of 1 - 30 mTorr and powers of 300 - 600 W. In the OES experiments, the argon was used as an actinometer and as an adding gas. The effect of the argon content in the gas mixture was examined in the range of 5 - 30%. The investigation of the effects of pressure on the dissociation fraction of nitrogen molecules and on the optical emission characteristics were carried out. The correction factors for estimating the dissociation fraction by OES actinometry accounting for argon effect were formulated and calculated. It was found that the dissociation fraction increased with increasing power and Ar content, while it decreased with increasing pressure. In addition, the electron energy probability function (EEPF), the electron density, and the electron temperature were obtained by using a Langmuir probe to investigate the effects of the plasma parameters on the optical emission characteristics and the dissociation fraction.
Fecundity, pouch young survivorship and breeding season of the northern bettong (Bettongia tropica) in the wild.
Authors: Vernes K , Pope LC
Published: August 2011

Reproduction in a wild population of northern bettongs (Bettongia tropica) was studied
at Davies Creek in northeastern Queensland between November 1994 and February 1997. Using
mark-recapture, we recorded 88 individual pouch young (PY) during the study (34 male, 45
female, 9 unknown sex). Using captive-derived growth equations we estimated that 90 % of PY
survived to permanent emergence from the pouch (PEP). Birth of a new PY coincided with PEP
of the previous young 78 % of the time; 12 % of births occurred within 2 - 8 weeks of PEP
while the remaining 10 % probably died before PEP. 96 % of adult females carried PY at the
time of capture. B. tropica bred continuously, with no significant differences in numbers of
births recorded in different months. Few young that were marked in the pouch were captured as
sub-adults, and none were captured as adults. Limited data on longevity indicated that B. tropica
can live to at least 5 years. Our data suggest that B. tropica has a high reproductive potential;
however, the fate of PY after PEP remains poorly known; and this may represent the period of
greatest bettong mortality.
Long distance movements and the use of fire mosaics by small mammals in the Simpson Desert, central Australia..
Authors: Letnic M
Published: August 2011

Using recapture data and radio-telemetry, the movement patterns of small mammals occupying
burned and unburned habitats in the Simpson Desert, western Queensland were investigated.
Long-term, between trap sessions, recapture rates of small mammals ranged from 7.3 % for
Sminthopsis youngsoni to less than 1 % for Pseudomys desertor. Seventeen individuals including
Pseudomys hermannsburgensis, S. youngsoni and Notomys alexis were observed to make longdistance
movements (> 500 m). The longest recorded movement in this study was 5.7 km by a
male S. youngsoni. Telemetry and recapture data indicate that individual P. hermannsburgensis,
S. youngsoni and N. alexis can move more than 700 m and up to 2 km in a single night. Radiotracked
P. hermannsburgensis and N. alexis utilised a mosaic of burned and unburned habitats in
a single night of foraging. Low rates of recapture for small mammals in the Australian arid zone
suggest that the populations of many species consist largely of transient individuals. Some
species of small mammals appear to have sufficient mobility to locate resource rich patches and
utilise habitat mosaics along a continuum of scales. These range from long-distance and
presumably unidirectional migrations of 10 km or more, through to nightly movements in the
order of several hundred metres to 1 - 2 km.
A taxonomic review of the genus Pteralopex (Chiroptera: Pteropodidae), the monkey-faced bats of the south-western Pacific.
Authors: Parnaby HE
Published: August 2011

Morphological variation in the genus Pteralopex is reviewed to evaluate species limits and diagnostic
criteria. Five species are recognised: P. atrata and P. pulchra from Guadalcanal, Solomon Islands; P.
anceps from Bougainville and Buka Islands, Papua New Guinea, and Choiseul and Isabel Islands,
Solomon Islands; and P. acrodonta from Taveuni, Fiji. A new species is described from New
Georgia and Vangunu Islands, Solomon Islands. It resembles P. pulchra but differs in dental, cranial
and pelage characters. A number of criteria previously considered diagnostic for P. anceps are
shown to be invalid. The new species faces a high extinction risk from logging operations and
pressure from expanding human populations, and an IUCN threat category of ?Critically
Endangered? is proposed. All Pteralopex species face a high risk of extinction and conservation
measures such as habitat protection are urgently required.
Broad-toothed rat, Mastacomys fuscus (Rodentia, Muridae), found in alpine heathland in Tasmania.
Authors: Driessen MM
Published: August 2011

THE broad-toothed rat Mastacomys fuscus is a
native, herbivorous rodent that occurs in New South
Wales, Victoria and Tasmania. On the Australian
mainland the species has been recorded in several
habitats at altitudes ranging from sea level to 1800 m.
In alpine and sub-alpine areas of New South Wales
and Victoria it has been recorded in heathlands, open
eucalypt woodlands and wet sedgelands (Calaby and
Wimbush 1964; Dixon 1971; Seebeck 1971; Bubela
et al. 1991). At lower altitudes in Victoria, it has
been recorded in wet sclerophyll forests with a dense
undergrowth, coastal heathland, coastal grassland and
in a pine plantation (Seebeck 1971; Wallis et al.
1982; Warneke 1960). In Tasmania, M. fuscus has
been previously recorded only in buttongrass
moorlands of western Tasmania at altitudes ranging
from sea level to 900 m (Finlayson 1933; Andrews
1968; Green 1968, 1984; Hocking and Guiler 1983;
Driessen and Comfort 1991; Slater 1992; Driessen
1998). Buttongrass moorland (also referred to as
sedgeland) is a treeless vegetation typically
dominated by Gymnoschoenus sphaerocephalus
(buttongrass) that covers more than a million hectares
in Tasmania, predominantly in the western part of the
State (Jarman et al. 1988). Buttongrass moorland is a
very variable vegetation group and not all
communities recognised within buttongrass moorland
provide habitat for M. fuscus (Driessen and Comfort
1991; Slater 1992; Driessen 1998).
The purpose of this note is to report the results of
a survey for M. fuscus in alpine heathland, a habitat
in which the species has not been previously recorded
in Tasmania. This finding has significant
implications for the conservation status of this
species.
Koala feeding and roosting trees in the Campbelltown area of New South Wales.
Authors: Sluiter AF , Close RL , Ward SJ
Published: August 2011

IN assessing habitat quality for koalas (Phascolarctos
cinereus), the relative importance of trees used for
food and for roosting must be established. Robbins
and Russell (1978) and Hindell et al. (1985)
suggested that trees in which P. cinereus roosted by
day reliably predicted the trees they browsed. Tun
(1993) and Hasegawa (1995), however, using leaf
cuticle analysis of P. cinereus faecal pellets,
questioned that suggestion .
Phillips and Callaghan (2000) investigated
preferences of P. cinereus in the Campbelltown area,
40 km southwest of Sydney, by recording the
presence of faecal pellets beneath trees in survey
quadrats. They concluded that Eucalyptus punctata
(grey gum) and E. agglomerata (blue-leaved stringy
bark) were preferred species on shale-based soils.
However, this method still does not distinguish
between trees used for roosting and those used for
feeding. Cuticle analysis was therefore used at
Campbelltown as a test of dietary preference (Table
1). These data on species use were compared with
sightings from a radio-tracking study of the same
individuals (Table 2), in a separate study (Ward
2002).
An historical attempt to control flying foxes in Samoa with an introduced disease.
Authors: Spennemann DHR , Gary J Wiles GJ
Published: August 2011

SEVERE disease epidemics are a rare but widely
distributed phenomenon among flying foxes (genus
Pteropus) in the Pacific islands (Flannery 1989;
Pierson and Rainey 1992; Rainey 1998). The few
documented outbreaks have produced extensive
mortality and steep population declines, and are often
followed by periods of slow population recovery.
The diseases involved have never been identified, but
have sometimes been preceded by local epidemics
among humans or domestic animals. The high
mortality rates of the bats support the theory of a
novel introduced pathogen to which populations
lacked previous exposure (Flannery 1989).
Observations of the 'Critically Endangered' bare-rumped sheathtail bat Saccolaimus saccolaimus Temminck (Chiroptera: Emballonuridae) on Cape York Peninsula, Queensland.
Authors: Murphy S
Published: August 2011

THE bare-rumped sheathtailed bat Saccolaimus
saccolaimus is a poorly understood species that has a
wide distribution covering parts of India, Sri Lanka,
Thailand, Myanmar, Malaya, Indonesia, New
Guinea, the Solomon Islands and Northern Australia
(Bonaccorso 1998). First collected in Australia by De
Vis near Cardwell, the current known distribution in
Queensland (Qld) extends from Bowen to Cooktown
with one isolated specimen collected near Coen on
Cape York Peninsula (Hall 1995; Duncan et al. 1999).
It has also been recorded in the Alligator River area in
the Northern Territory (McKean et al. 1981). The
conservation status of S. saccolaimus in Qld has
recently been defined as ?Critically Endangered?, and
the species has not been recorded anywhere in
Australia for at least 18 years (Duncan et al. 1999;
Menkhorst and Knight 2001). The likely reasons for
the apparent decline are unclear, but may involve
land-clearing and changed fire regimes in the coastal
zone where it is thought to occur (Duncan et al.
1999). In contrast, Bonaccorso (1998) considers S.
saccolaimus to be secure, albeit also poorly known in
Papua New Guinea.
Common Dolphins (Delphinus Delphis) In Southern Australia: A Morphometric Study
Authors: Bell CH , Kemper CM , Conran JG
Published: August 2011

Examination of 211 Delphinus specimens from the coasts of Western Australia to New South
Wales, including Tasmania, was conducted using 62 quantitative and 11 qualitative variables.
After refining the dataset, multivariate analyses were performed on 130 cranially mature
specimens using 21 cranial variables. MANOVA showed males to be slightly larger than
females, but with substantial overlap, allowing analyses to combine genders. UPGMA Cluster
Analysis and MDS Ordination showed three largely overlapping groups based on a size
gradient. K-means analysis of these groups found no significant differences and confirmed a
size gradient. Discriminant analysis of specimens grouped by geography and water depth
showed a tendency for large skulls to be from coasts adjacent to deep water and small skulls
from shallow water coasts. Cranial measurements were significant, postcranial measurements
and features were not. Tooth counts were within the range for D. delphis for all specimens
examined. This study confirms genetic evidence for a single continuously variable species
(Delphinus delphis Linnaeus, 1758) in southern Australian waters. Compared with either D.
delphis or D. capensis from the eastern North Pacific, the skulls of D. delphis in southern
Australia were more variable for many characters.
Management Of Marine Mammal Tours On The Great Barrier Reef
Authors: Stokes T , Dobbs K , Recchia C
Published: August 2011

Of the more than 30 species of marine mammal occurring within the Great Barrier Reef Marine
Park (GBRMP), three are the focus of wildlife-based tours: humpback whales (Megaptera
novaeangliae), dwarf minke whales (Balaenoptera acutorostrata) and dugongs (Dugong
dugon). Currently (April 2001), 19 permits, comprising 31 ships and two aircraft, allow whalewatching
in the GBRMP. The combined passenger capacity of these craft is 3,238 at any one
time (e.g., per day). However, fewer than 15,000 persons were recorded in ?dedicated? whalewatching
tours each month during the May - October ?whale-watching? season between 1998
and 2000. Watching M. novaeangliae occurs primarily in the Central and Cairns Sections of the
GBRMP, with most activity focused in the Whitsundays. Permitted levels of whale-watching
are capped at eight permits in the Cairns Area, and at 11 permits in the Whitsundays. Other
tours include: a specialised form of whale-watching involving swimming with B. acutorostrata
which is being brought within a limited-entry management regime; one dolphin-watching tour
in the Central Section of the GBRMP north of the Whitsundays; and one dugong-watching tour
in the Hinchinbrook Region. Because of reported declines in the number of D. dugon on the
Great Barrier Reef, this activity is being monitored closely before further permits are granted.
Marine mammal watching activities in the GBRMP are managed through a combination of best
practices guidelines, codes of conduct, regulations, zoning, wildlife protection areas and
permits. The potential for the commercial whale-watching industry to become self-regulating is
acknowledged.
Tourist Disturbance On New Zealand Fur Seals (Arctophalus Forsteri)
Authors: Boren LJ , Gemmell NJ , Barton KJ
Published: August 2011

Marine mammals are significant tourist attractions around New Zealand, however, the impact
of eco-tourism on these species is poorly documented. Effective management to mitigate any
negative effects requires an understanding of target species? reactions to tourist activities. We
have studied the effects of tourist activities on New Zealand fur seals (Arctocephalus forsteri)
using a novel combination of observations and controlled approaches. Three study areas were
selected reflecting a range of visitor density, type of tourism, and the anticipated sensitivity of
fur seals to disturbance. Behaviour was observed using instantaneous scan sampling and
attributes of tourist approaches were tested experimentally by controlled approaches.
Approaches were made on land, by kayak, and motorboat. Fur seal responses and the distance
at which the seal responded were recorded. Our results indicate that A. forsteri behaviour was
being modified by tourist activities. Habituation was occurring at study areas with high levels
of tourist activity. Approachers following current minimum approach distances still caused
some animals to modify their behaviour and new minimum approach distances are
recommended based on controlled approaches to seals at all study areas. Our work
demonstrated that controlled approaches can be a useful tool to develop effective management
guidelines to lessen impacts from eco-tourism activities.
The status of mammals in the North Kimberley, Western Australia
Authors: Start A.N. , Burbidge A.A.. , McKenzie N.L. , Palmer C.
Published: August 2011

The mammalian fauna of the North Kimberley bioregion has been cited as ?intact? because 1970s and 1980s surveys showed that all terrestrial mammal species known at European settlement were extant. This assumption was tested in 2003/4 by re-surveying 16 of the most diverse sites sampled in earlier surveys of three mainland areas and four islands. Most Critical Weight Range species were re-located at many sites and some were found at sites where they were previously unknown. Most differences between early surveys and this survey are probably artifacts of limited survey intensity. However, the region is not exempt from processes associated with decline elsewhere, particularly effects of changed fire regimes and invasion by exotic species, and species of non-rocky habitats may be more vulnerable. Small granivorous rodents were notably scarce.