bluuebunny/crossref_metadata_2025 huggingface dataset:
Robust global synchronization of two complex dynamical networks
Authors: Mostafa Asheghan Mohammad , Míguez Joaquín
Published: May 2013

We investigate the synchronization of two coupled complex dynamical networks, a problem that has been termed outer synchronization in the literature. Our approach relies on (a) a basic lemma on the eigendecomposition of matrices resulting from Kronecker products and (b) a suitable choice of Lyapunov function related to the synchronization error dynamics. Starting from these two ingredients, a theorem that provides a sufficient condition for outer synchronization of the networks is proved. The condition in the theorem is expressed as a linear matrix inequality. When satisfied, synchronization is guaranteed to occur globally, i.e., independently of the initial conditions of the networks. The argument of the proof includes the design of the gain of the synchronizer, which is a constant square matrix with dimension dependent on the number of dynamic variables in a single network node, but independent of the size of the overall network, which can be much larger. This basic result is subsequently elaborated to simplify the design of the synchronizer, to avoid unnecessarily restrictive assumptions (e.g., diffusivity) on the coupling matrix that defines the topology of the networks and, finally, to obtain synchronizers that are robust to model errors in the parameters of the coupled networks. An illustrative numerical example for the outer synchronization of two networks of classical Lorenz nodes with perturbed parameters is presented.
Eigenstates and instabilities of chains with embedded defects
Authors: D'Ambroise J. , Kevrekidis P. G. , Lepri S.
Published: May 2013

We consider the eigenvalue problem for one-dimensional linear Schrödinger lattices (tight-binding) with an embedded few-sites linear or nonlinear, Hamiltonian or non-conservative defect (an oligomer). Such a problem arises when considering scattering states in the presence of (generally complex) impurities as well as in the stability analysis of nonlinear waves. We describe a general approach based on a matching of solutions of the linear portions of the lattice at the location of the oligomer defect. As specific examples, we discuss both linear and nonlinear, Hamiltonian and PT-symmetric dimers and trimers. In the linear case, this approach provides us a handle for semi-analytically computing the spectrum [this amounts to the solution of a polynomial equation]. In the nonlinear case, it enables the computation of the linearization spectrum around the stationary solutions. The calculations showcase the oscillatory instabilities that strongly nonlinear states typically manifest.
An analytical solution for Dean flow in curved ducts with rectangular cross section
Authors: Norouzi M. , Biglari N.
Published: May 2013

In this paper, a full analytical solution for incompressible flow inside the curved ducts with rectangular cross-section is presented for the first time. The perturbation method is applied to solve the governing equations and curvature ratio is considered as the perturbation parameter. The previous perturbation solutions are usually restricted to the flow in curved circular or annular pipes related to the overly complex form of solutions or singularity situation for flow in curved ducts with non-circular shapes of cross section. This issue specifies the importance of analytical studies in the field of Dean flow inside the non-circular ducts. In this study, the main flow velocity, stream function of lateral velocities (secondary flows), and flow resistance ratio in rectangular curved ducts are obtained analytically. The effect of duct curvature and aspect ratio on flow field is investigated as well. Moreover, it is important to mention that the current analytical solution is able to simulate the Taylor-Görtler and Dean vortices (vortices in stable and unstable situations) in curved channels.
Linear and nonlinear dynamics of electron temperature gradient mode in non-Maxwellian plasmas
Authors: Zakir U. , Haque Q. , Qamar A.
Published: May 2013

The effect of non-Maxwellian distributed ions on electron temperature gradient mode is investigated. The linear dispersion relation of ηe−mode is obtained which shows that the behavior of this mode changes in the presence of superthermal ions. The growth rate of ηe−mode driven linear instability is found and is observed to modify due to nonthermal ions. However, it is found that this leaves the electron energy transport coefficient unchanged. In the nonlinear regime, a dipolar vortex solution is derived which indicates that the dynamic behavior of the vortices changes with the inclusion of kappa distributed ions. The importance of present study with respect to space and laboratory plasmas is also pointed out.
Generation of first hard X-ray pulse at Tsinghua Thomson Scattering X-ray Source
Authors: Du Yingchao , Yan Lixin , Hua Jianfei , Du Qiang , Zhang Zhen , Li Renkai , Qian Houjun , Huang Wenhui , Chen Huaibi , Tang Chuanxiang
Published: May 2013

Tsinghua Thomson Scattering X-ray Source (TTX) is the first-of-its-kind dedicated hard X-ray source in China based on the Thomson scattering between a terawatt ultrashort laser and relativistic electron beams. In this paper, we report the experimental generation and characterization of the first hard X-ray pulses (51.7 keV) via head-on collision of an 800 nm laser and 46.7 MeV electron beams. The measured yield is 1.0 × 106 per pulse with an electron bunch charge of 200 pC and laser pulse energy of 300 mJ. The angular intensity distribution and energy spectra of the X-ray pulse are measured with an electron-multiplying charge-coupled device using a CsI scintillator and silicon attenuators. These measurements agree well with theoretical and simulation predictions. An imaging test using the X-ray pulse at the TTX is also presented.
Temporal and spatial effects of ablation plume on number density distribution of droplets in an aerosol measured by laser-induced breakdown
Authors: Yashiro H. , Kakehata M.
Published: May 2013

We proposed and experimentally demonstrated a novel method of evaluating the number density of droplets in an aerosol by laser-induced breakdown. The number density of droplets is evaluated from the volume in which the laser intensity exceeds the breakdown threshold intensity for droplets, and the number of droplets in this volume, which is evaluated by the experimentally observed breakdown probability. This measurement method requires a large number of laser shots for not only precise measurement but also highly temporally and spatially resolved density distribution in aerosol. Laser ablation plumes ejected from liquid droplets generated by breakdown disturb the density around the measurement points. Therefore, the recovery time of the density determines the maximum repetition rate of the probe laser irradiating a fixed point. The expansion range of the ablation plume determines the minimum distance at which the measurement points are unaffected by a neighboring breakdown when multiple laser beams are simultaneously irradiated. These laser irradiation procedures enable the measurement of the number density distribution of droplets in an aerosol at a large number of points within a short measurement time.
Strain-induced phase transformations under compression, unloading, and reloading in a diamond anvil cell
Authors: Feng Biao , Zarechnyy Oleg M. , Levitas Valery I.
Published: May 2013

Strain-induced phase transformations (PTs) in a sample under compression, unloading, and reloading in a diamond anvil cell are investigated in detail, by applying finite element method. In contrast to previous studies, the kinetic equation includes the pressure range in which both direct and reverse PTs occur simultaneously. Results are compared to the case when “no transformation” region in the pressure range exists instead, for various values of the kinetic parameters and ratios of the yield strengths of low and high pressure phases. Under unloading (which has never been studied before), surprising plastic flow and reverse PT are found, which were neglected in experiments and change interpretation of experimental results. They are caused both by heterogeneous stress redistribution and transformation-induced plasticity. After reloading, the reverse PT continues followed by intense direct PT. However, PT is less pronounced than after initial compression and geometry of transformed zone changes. In particular, a localized transformed band of a weaker high pressure phase does not reappear in comparison with the initial compression. A number of experimental phenomena are reproduced and interpreted.
Tuning the magnetocaloric properties of the Ni2+xMn1−xSn Heusler alloys
Authors: Mukadam M. D. , Yusuf S. M. , Bhatt Pramod
Published: May 2013

We report the effect of Ni substitution on the magnetic properties of polycrystalline Ni2+xMn1−xSn (x = 0, 0.05, and 0.1) Heusler alloys using the magnetization and neutron diffraction measurement techniques. The paramagnetic to ferromagnetic transition temperature (Curie temperature, TC) has been tuned with the substitution of Ni at the Mn sites (TC≈ 349, 337, and 317 K for x = 0, 0.05, and 0.1 samples, respectively) without a significant reduction in the magnetic entropy change −ΔSM. For a magnetic field change from 0 to 5 T, −ΔSM of 2.9, 2.5, and 2.2 J kg−1 K−1 have been observed for x = 0, 0.05, and 0.1 samples, respectively. From the neutron diffraction study, it has been found that with increasing x, the Mn site ordered moment decreases. −ΔSM as a function of changing magnetic field and Curie temperature follows the molecular mean field model. The studied Ni2+xMn1−xSn alloys, with their nontoxic constituent elements and low-cost, can be used for magnetic cooling over a wide temperature range of 278–379 K covering room temperature.
Chemo-mechanical softening during in situ nanoindentation of anodic porous alumina with anodization processing
Authors: Cheng Chuan , Ngan A. H. W.
Published: May 2013

Simultaneous application of mechanical stresses on a material as it undergoes an electrochemical reaction can result in interesting coupling effects between the chemical and mechanical responses of the material. In this work, anodic porous alumina supported on Al is found to exhibit significant softening during in situ nanoindentation with anodization processing. Compared with ex situ nanoindentation without anodization processing, the in situ hardness measured on the alumina is found to be much lower, when the estimated maximum stress underneath the indenter is exerted on the metal/oxide (m/o) interface at the bottom of the oxide. Numerical calculation reveals that a high electric field exists across the nanometrically thin barrier layer where the electrochemical reactions mainly take place. In microindentation with a flat punch, in situ softening is also observed, but no significant difference in the deformation of the oxide and the Al substrate between in situ and ex situ cases can be observed from cross-sectional transmission electron microscopy examination. The evidence, therefore, indicates that the observed in situ softening is due to a combination of high compression stress and electric field acting near the m/o interface, and it is likely that such conditions enhance Al ionization at the m/o interface, thus causing the m/o interface to move faster into the Al substrate under the in situ condition.
Mg-doped TlBa2(Ca2-xMgx)(Cu2.2Ti0.8)O10-δ (x = 0, 0.05, 0.15, 0.25, 0.35) superconductors
Authors: Khan Nawazish A. , Qamar Salman
Published: May 2013

Ti-doped TlBa2(Ca2-xMgx)(Cu2.2Ti0.8)O10-δ (x = 0, 0.05, 0.15, 0.25, 0.35) samples are synthesized at 860 °C by two step solid state reaction method. All these samples have shown metallic variations of resistivity from room temperature down to onset of superconductivity. The room temperature resistivity systematically increases with increased Mg contents in the final compound. The onset temperature of superconductivity [Tc(onset)], as observed in the resistivity and susceptibility measurements, and the zero resistivity critical temperature are found to increase for Mg-doping of x = 0.05 and 0.15; however, the values of these parameters are suppressed for Mg-doping of x = 0.25 and 0.35. Magnitude of the superconductivity also increases for Mg-doping of x = 0.05 and 0.15, whereas its values decrease for Mg-doping of x = 0.25 and 0.35. All TlBa2(Ca2-xMgx)(Cu2.2Ti0.8)O10-δ (x = 0, 0.05, 0.15, 0.25, 0.35) samples have shown orthorhombic crystal structure and the c-axis lattice parameter is systematically suppressed with the increase of Mg-doping. In the phonon modes assignment as observed from Fourier transform infrared spectrometer absorption measurements, the planar oxygen mode is softened, whereas the apical oxygen mode of type Tl-OA-Cu(2)/Ti is hardened with increased Mg-doping. The Oδ mode of oxygen atoms increases in intensity with increased Mg incorporation in the final compound. It is most likely that the density of phonon modes increases till mg-doping of x = 0.15, but for x = 0.25 and 0.35 the c-axis length decreases further, which may enhance the population of an-harmonic modes of oscillations. Such competitive modes of oscillations are most likely produced due to the presence of two different masses existing in the conducting CuO2/TiO2 planes, i.e., Ti (47.90 amu) and Cu (63.54 amu). Since the distance between the planes decreases with increased Mg-doping, the equilibrium population of the phonon modes in CuO2/TiO2 planes may also change and hence the Tc and magnitude of superconductivity. These observations strongly suggest the existence of electron-phonon interactions essential for the mechanism of high Tc superconductivity.
Vortex dynamics and second magnetization peak in PrFeAsO0.60F0.12 superconductor
Authors: Bhoi D. , Mandal P. , Choudhury P.
Published: May 2013

We have studied the vortex dynamics in the PrFeAsO0.60F0.12 superconducting sample by dc magnetization and dynamic magnetization-relaxation rate (Q) measurements. The field dependence of the superconducting irreversible magnetization Ms reveals a second magnetization peak or fishtail effect. The large value of Q is an indication of moderate vortex motion and relatively weak pinning energy. Data analysis based on the generalized inversion scheme suggests that the vortex dynamics can be described by the collective pinning model. The temperature dependence of the critical current is consistent with the pinning due to the spatial variation in the mean free path near a lattice defect (δl-pinning). The temperature and field dependence of Q indicate a crossover from elastic to plastic vortex creep with increasing temperature and magnetic field. Finally, we have constructed the vortex phase diagram based on the present data.
Step dynamics in the homoepitaxial growth of 6H-SiC by chemical vapor deposition on 1° offcut substrate using dichlorosilane as Si precursor
Authors: Omar Sabih U. , Chandrashekhar M. V. S. , Chowdhury Iftekhar A. , Rana Tawhid A. , Sudarshan Tangali S.
Published: May 2013

Step flow epitaxial growth was achieved on 1° offcut 6H-SiC substrate using dichlorosilane (DCS) as the Si precursor. High crystal quality and polytype uniformity were verified by XRD and Raman spectroscopy. Mirror-like surfaces with very few triangular and carrot defects were obtained over a wide range of C/Si ratios. Surface step bunching and step crossover were observed and rms roughness values were measured to be 2–4 nm. N-type doping was achieved by site-competition epitaxy at low C/Si ratios. Growth rates of 0.5−4 μm/h was obtained over a temperature range of 1470–1550 °C. The surface diffusion length of the adatoms on the step terraces was calculated using a model based on the Burton-Cabrera-Frank theory of epigrowth on stepped surfaces. In the experimental temperature range, the surface diffusion length varied from 5 to 13 nm, which is significantly shorter than those reported in literature for epigrowth using the conventional silane precursor. The short diffusion lengths for DCS imply a strong desorption process at the growth front, which is ideal for polytype-matched step-flow growth on low offcut substrates. The understanding of these step dynamics issues is critical for crystal growers using chlorinated gas precursors.
Formation mechanism of femtosecond laser-induced high spatial frequency ripples on semiconductors at low fluence and high repetition rate
Authors: Le Harzic R. , Stracke F. , Zimmermann H.
Published: May 2013

Periodic high spatial frequency ripples structures (HSFL) have been generated in silicon (Si) and in germanium (Ge) at very low fluence below or close to the melting fluence threshold, at different wavelengths and at high repetition rate femtosecond laser pulses (80 MHz, 700–950 nm, 170 fs). HSFL initiation, formation, and arrangement combine structural modification of the surface initiated by heat accumulation of successive pulses with second harmonic generation. HSFL are wavelength dependent and the refractive index plays a central role on their periodicities. HSFL spacing follows quite well a law of Λ=λ/2nλ*, where nλ* is the modified femtosecond laser excited refractive index as a function of the wavelength for Si and Ge.
Energetic ion transport by microturbulence is insignificant in tokamaks
Authors: Pace D. C. , Austin M. E. , Bass E. M. , Budny R. V. , Heidbrink W. W. , Hillesheim J. C. , Holcomb C. T. , Gorelenkova M. , Grierson B. A. , McCune D. C. , McKee G. R. , Muscatello C. M. , Park J. M. , Petty C. C. , Rhodes T. L. , Staebler G. M. , Suzuki T. , Van Zeeland M. A. , Waltz R. E. , Wang G. , White A. E. , Yan Z. , Yuan X. , Zhu Y. B.
Published: May 2013

Energetic ion transport due to microturbulence is investigated in magnetohydrodynamic-quiescent plasmas by way of neutral beam injection in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)]. A range of on-axis and off-axis beam injection scenarios are employed to vary relevant parameters such as the character of the background microturbulence and the value of Eb/Te, where Eb is the energetic ion energy and Te the electron temperature. In all cases, it is found that any transport enhancement due to microturbulence is too small to observe experimentally. These transport effects are modeled using numerical and analytic expectations that calculate the energetic ion diffusivity due to microturbulence. It is determined that energetic ion transport due to coherent fluctuations (e.g., Alfvén eigenmodes) is a considerably larger effect and should therefore be considered more important for ITER.
Pulse-electron paramagnetic resonance of Cr3+ centers in SrTiO3
Authors: Azamat D. V. , Dejneka A. , Lančok J. , Trepakov V. A. , Jastrabik L. , Badalyan A. G.
Published: May 2013

Electron paramagnetic resonance on chromium doped SrTiO3 samples grown using the Verneuil technique shows the presence of charge-compensated Cr3+-VO as one of the dominant chromium centers. The spin-lattice relaxation processes have been investigated in samples with both isotropic Cr3+ and Cr3+-VO centers in heavily doped SrTiO3. The relaxation of longitudinal magnetization was dominated by the sum of two exponentials with two time constants (i.e., a slow and a fast constant) at liquid-helium temperatures. The results of fitting the temperature variation of T1 suggest that the dominant exponential contribution is related to the spin-phonon relaxation time arising from the local phonon mode.
Deterministic assembly of releasable single crystal silicon-metal oxide field-effect devices formed from bulk wafers
Authors: Kim Tae-il , Hwan Jung Yei , Chung Hyun-Joong , Jun Yu Ki , Ahmed Numair , Corcoran Christopher J. , Suk Park Jae , Hun Jin Sung , Rogers John A.
Published: May 2013

Deterministic assembly of ultrathin metal oxide-semiconductor field-effect transistors released from the surfaces of bulk wafers with (111) orientation provides a route to high quality electronics on nearly any type of substrate. Device parameters and bias stability characteristics from transistors on sheets of plastic confirm the effectiveness of the approach and the critical roles of thermally grown layers of silicon dioxide for the gate dielectrics and passivation layers. Systematic studies of the anisotropic etching processes used to release the devices illustrate capabilities into the sub-micron thickness regime, with beneficial effects on the bending stiffness and degree of bendability.
Dielectric properties of lead lanthanum zirconate titanate thin films with and without ZrO2 insertion layers
Authors: Liu Shanshan , Ma Beihai , Narayanan Manoj , Tong Sheng , Koritala Rachel E. , Hu Zhongqiang , Balachandran Uthamalingam
Published: May 2013

The dielectric properties of lead lanthanum zirconate titanate (PLZT) thin films on platinized silicon (Pt/Si) with and without ZrO2 insertion layers were investigated in the temperature range from 20 °C to 300 °C. Permittivity, dielectric loss tangent, and tunability were reduced for the samples with ZrO2 insertion layers compared to those without the layers. Additionally, the permittivity was less dependent on frequency over the broad temperature range studied (20–300 °C). The leakage current behavior of the PLZT films with and without ZrO2 insertion layers was also investigated, and on the basis of those results, a probable conduction mechanism has been suggested. The improved electrical properties in the PLZT with ZrO2 layers are attributed to the ZrO2 layer blocking the mobile ionic defects and reducing free charge carriers to transport.
Droplets on liquid surfaces: Dual equilibrium states and their energy barrier
Authors: Shabani Roxana , Kumar Ranganathan , Cho Hyoung J.
Published: May 2013

Floating aqueous droplets were formed at oil-air interface, and two stable configurations of (i) non-coalescent droplet and (ii) cap/bead droplet were observed. General solutions for energy and force analysis were obtained for both configurations and were shown to be in good agreement with the experimental observations. The energy barrier obtained for transition from configuration (i) to configuration (ii) was correlated to the droplet release height and the probability of non-coalescent droplet formation.
A hybrid microfluidic platform for cell-based assays via diffusive and convective trans-membrane perfusion
Authors: Vereshchagina Elizaveta , Mc Glade Declan , Glynn Macdara , Ducrée Jens
Published: May 2013

We present a novel 3D hybrid assembly of a polymer microfluidic chip with polycarbonate track-etched membrane (PCTEM) enabling membrane-supported cell culture. Two chip designs have been developed to establish either diffusive or convective reagent delivery using the integrated PCTEM. While it is well suited to a range of cell-based assays, we specifically employ this platform for the screening of a common antitumor chemotoxic agent (mitomycin C – MMC) on the HL60 myeloid leukemia cell line. The toxic activity of MMC is based on the generation of severe DNA damage in the cells. Using either mode of operation, the HL60 cells were cultured on-chip before, during, and after exposure to MMC at concentrations ranging from 0 to 50 μM. Cell viability was analysed off-chip by the trypan blue dye exclusion assay. The results of the on-chip viability assay were found to be consistent with those obtained off-chip and indicated ca. 40% cell survival at MMC concentration of 50 μM. The catalogue of capabilities of the here described cell assay platform comprises of (i) the culturing of cells either under shear-free conditions or under induced through-membrane flows, (ii) the tight time control of the reagent exposure, (iii) the straightforward assembly of devices, (iv) the flexibility on the choice of the membrane, and, prospectively, (v) the amenability for large-scale parallelization.
Global two-fluid simulations of geodesic acoustic modes in strongly shaped tight aspect ratio tokamak plasmas
Authors: Robinson J. R. , Hnat B. , Thyagaraja A. , McClements K. G. , Knight P. J. , Kirk A. ,   MAST Team
Published: May 2013

Following recent observations suggesting the presence of the geodesic acoustic mode (GAM) in ohmically heated discharges in the Mega Amp Spherical Tokamak (MAST) [J. R. Robinson et al., Plasma Phys. Controlled Fusion 54, 105007 (2012)], the behaviour of the GAM is studied numerically using the two fluid, global code CENTORI [P. J. Knight et al. Comput. Phys. Commun. 183, 2346 (2012)]. We examine mode localisation and effects of magnetic geometry, given by aspect ratio, elongation, and safety factor, on the observed frequency of the mode. An excellent agreement between simulations and experimental data is found for simulation plasma parameters matched to those of MAST. Increasing aspect ratio yields good agreement between the GAM frequency found in the simulations and an analytical result obtained for elongated large aspect ratio plasmas.
Graphene mobility enhancement by organosilane interface engineering
Authors: Lv Hongming , Wu Huaqiang , Xiao Ke , Zhu Weinan , Xu Huilong , Zhang Zhiyong , Qian He
Published: May 2013

In this study, SiO2 substrates engineered with three different types of organosilane self-assembled monolayers (SAM) have been proven to assist graphene transfer process. Bottom gate graphene field effect transistors with organosilane interface engineering are fabricated and tested. Improvement of carrier mobility is observed, which is attributed to organosilane SAMs' screening effect to charge impurity and surface polarized phonon scatterings and SAM molecules' π-π stacking interaction with graphene. In particular, graphene on phenyl-terminated organosilane SAM shows the best extrinsic field effect mobility of 2500 cm2 v−1 s−1, three times of its counterpart on SiO2.
The mechanism of the surface morphology transformation for the carbon nanotube thin film irradiated via excimer laser
Authors: Chien Yun-Shan , Lee I-Che , Yang Po-Yu , Wang Chao-Lung , Tsai Wan-Lin , Wang Kuang-Yu , Chou Chia-Hsin , Cheng Huang-Chung
Published: May 2013

In this paper, the surface morphology transformation of the sprayed carbon nanotube (CNT) thin film irradiated with the excimer laser has been systematically investigated. Under the excimer-laser irradiation, two phenomena, including the annealing and ablation effects, were found to be dependent on the incident laser energy and overlapping ratios. Moreover, the extremely high protrusions would be produced in the interface between the annealing and ablation regions. The mechanism of the CNT thin film under the excimer laser irradiation was, therefore, proposed to derive the surface morphology modifications and the further reinforced crystallinity with proper laser energy densities and overlapping ratios.
Nanopatterns induced by pulsed laser irradiation on the surface of an Fe-Al alloy and their magnetic properties
Authors: Yoshida Yutaka , Oosawa Kazuya , Watanabe Seiichi , Kaiju Hideo , Kondo Kenji , Ishibashi Akira , Yoshimi Kyosuke
Published: May 2013

We have studied nanopatterns induced by nanosecond pulsed laser irradiation on (111) plane surfaces of a polycrystalline iron-aluminum alloy and evaluated their magnetic properties. Multiple nanosecond pulsed laser irradiation induces a wavelength-dependent surface transformation of the lattice structure from a B2-type to a supersaturated body centered cubic lattice. The selective formation of surface nanopatterns consisting of holes, stripes, polygonal networks, and dot-like nanoprotrusions can be observed. Furthermore, focused magneto-optical Kerr effect measurements reveal that the magnetic properties of the resultant nanostructured region changes from a paramagnetic to a ferromagnetic phase in accordance with the number of laser pulses.
Molecular beam epitaxy of n-Zn(Mg)O as a low-damping plasmonic material at telecommunication wavelengths
Authors: Sadofev Sergey , Kalusniak Sascha , Schäfer Peter , Henneberger Fritz
Published: May 2013

We demonstrate that Zn(Mg)O:Ga layers can be grown by molecular beam epitaxy in a two-dimensional mode with high structural perfection up to Ga mole fractions of about 6.5%. The doping efficiency is practically 100% so that free-carrier concentrations of almost 1021 cm−3 can be realized providing a zero-crossover wavelength of the real part of the dielectric function as short as 1.36 μm, while the plasmonic damping does not exceed 50 meV. Structural, electrical, and optical data consistently demonstrate a profound change of the Ga incorporation mode beyond concentrations of 1021 cm−3 attended by deterioration of the plasmonic features.
Detailed consideration of the electron-phonon thermal conductance at metal-dielectric interfaces
Authors: Singh Piyush , Seong Myunghoon , Sinha Sanjiv
Published: May 2013

The effect of electron-phonon coupling on thermal conductance across metal-dielectric interfaces remains inconclusive. The leading model employs the phonon thermal conductivity of the metal that is difficult to estimate. We remove this difficulty by obtaining the conductance directly from the Bloch-Boltzmann-Peierls formula, describing the matrix element using a deformation potential that can be estimated from the electrical resistivity data. We report calculations up to 500 K to show that electron-phonon coupling is not a major contributor to the thermal resistance across metal-dielectric interfaces. Our method advances understanding of the role of electron-phonon coupling in limiting thermal transport near metal interfaces.
Saturation of the junction voltage in GaN-based laser diodes
Authors: Feng M. X. , Liu J. P. , Zhang S. M. , Liu Z. S. , Jiang D. S. , Li Z. C. , Wang F. , Li D. Y. , Zhang L. Q. , Wang H. , Yang H.
Published: May 2013

Saturation of the junction voltage in GaN-based laser diodes (LDs) is studied. It is found that there is a bump above the lasing transition in the I(dV/dI)-I curve, instead of a dip as that for GaAs-based LDs. The bump in I(dV/dI)-I curve moves to higher currents along with the lasing threshold. A model considering ambipolar conduction and electron overflow into p-AlGaN cladding layer due to poor carrier confinement in active region is used to explain the anomaly. The characteristic temperature of GaN-based LD is obtained by fitting threshold currents determined from I(dV/dI)-I curves. Moreover, it is found that GaN-based LDs show characteristics with a nonlinear series resistance, which may be due to the electron overflow into p-AlGaN cladding layer and the enhanced activation of Mg acceptors.
Growth and characterization of cooperative quantum dot chains in quaternary InAsSbP material system
Authors: Gambaryan K. M. , Aroutiounian V. M.
Published: May 2013

The cooperative quantum dot chains (CQDCs) are grown from In-As-Sb-P quaternary liquid phase on InAs(100) substrate with a deviation of surface orientation from (100) of about 0.3° along [010] direction. The wet chemical etching is utilized to create an additional artificial disorientation of the substrate. AFM investigations show that CQDCs mainly consist of central coupled InAsSb quantum dot (QD) sub-chains surrounded by InAsP-leaf chains. Cooperative chains have a ∼120 nm total width, over 5 μm length and directed along [010]. The separation between QDs within sub-chains is about 40 nm. The red shift of CQDCs’ absorption edge is detected.
Polymer embedded silicon nitride thermally tunable Bragg grating filters
Authors: Zhang Ziyang , Liu Dongliang , de Felipe David , Liu Anjin , Keil Norbert , Grote Norbert
Published: May 2013

Optical waveguides have been fabricated and investigated that employ silicon nitride as core and polymer as surrounding cladding material. Buried single-mode waveguides showed a propagation loss of ∼0.7 dB/cm at 1550 nm. Depending on the thickness of the silicon nitride core, the optical mode can be designed to expand largely into the polymer cladding. Using such a low-confinement structure and a metal strip heater embedded in the polymer cladding material beneath the core region, efficient thermally tunable waveguide Bragg grating filters were demonstrated. Wavelength tuning >57 nm was achieved at ∼220 mW of electrical heating power.
Broadband photonic control for dual-mode terahertz laser emission
Authors: Marshall Owen P. , Khairuzzaman Md. , Beere Harvey E. , Ritchie David A. , Chakraborty Subhasish
Published: May 2013

Short, holographically designed, aperiodic distributed feedback (ADFB) gratings are able to provide multi-band spectral filtering over arbitrarily wide bandwidths, offering a complimentary photonic technology to ultra-broadband terahertz quantum cascade lasers (THz QCLs). Using an ADFB grating, ion milled directly into the laser waveguide, high resolution spectral filtering is achieved in THz QCLs with heterogeneous active regions producing two distinct spectral gain peaks centred around 2.65 and 2.9 THz. Simultaneous dual-mode emission is achieved from a single section laser, with up to 20-dB side-mode suppression. Discrete electronic mode tuning occurs between ADFB bands, giving a switchable mode separation ranging from 163 to 267 GHz, along with continuous electronic and thermal tuning of up to ∼2 GHz.
Rate Constants for Reactions of Inorganic Radicals in Aqueous Solution
Authors: Neta P. , Huie Robert E. , Ross Alberta B.
Published: May 2013

Rate constants have been compiled for reactions of various inorganic radicals produced by radiolysis or photolysis, as well as by other chemical means in aqueous solutions. Data are included for the reactions of ⋅CO2 −, CO3⋅−, O3, ⋅N3, ⋅NH2, ⋅NO2, NO3⋅, ⋅PO32−, PO4⋅2−, SO2⋅ −, ⋅SO3 −, SO4⋅−, SO5⋅−, SeO3⋅ −, (SCN)2⋅ −, CL2⋅−, Br2⋅ −, I2⋅ −, ClO2⋅, BrO2⋅, and miscellaneous related radicals, with inorganic and organic compounds.
Evaluated Chemical Kinetic Data for the Reactions of Atomic Oxygen O(3P) with Saturated Organic Compounds in the Gas Phase
Authors: Herron John T.
Published: May 2013

Rate constants and mechanisms for the gas phase reactions of atomic oxygen O(3P) with organic compounds having only saturated C–C bonds are compiled and critically evaluated. Data are given for the alkanes, cycloalkanes, haloalkanes, oxygen and nitrogen containing organic compounds, and free radicals. In addition, data are given for some miscellaneous compounds containing boron, silicon, germane, and mercury. From a critical examination of the data, recommended values for rate constants are given over specified temperature intervals or at specified temperatures. Error limits are assigned to all recommended values.
In-hospital cardiac arrests: effect of amended Australian Resuscitation Council 2006 guidelines
Authors: Boyde Mary S. , Padget Michelle , Burmeister Elizabeth , Aitken Leanne M.
Published: May 2013

Objective
To evaluate cardiac arrest outcomes following the introduction of the Australian Resuscitation Council (ARC) 2006 amended guidelines for basic and advanced life support.

Methods
A retrospective study of all consecutive cardiac arrests during a 3-year phase pre-implementation (2004–06) and a 3-year phase post-implementation (2007–09) of the ARC 2006 guidelines was conducted at a tertiary referral hospital in Brisbane, Australia.

Results
Over the 6-year study phase 690 cardiac arrests were reported. Resuscitation was attempted in 248 patients pre-implementation and 271 patients post-implementation of the ARC 2006 guidelines. After adjusting for significant prognostic factors we found no significant change in return of spontaneous circulation (ROSC) (odds ratio 1.21, 95% confidence interval 0.80–1.85, P = 0.37) or survival to discharge (odds ratio 1.49, 95% confidence interval 0.94–2.37, P = 0.09) after the implementation of the ARC 2006 guidelines. Factors that remained significant in the final model for both outcomes included having an initial shockable rhythm, a shorter length of time from collapse to arrival of cardiac arrest team, location of the patient in a critical-care area, shorter length of resuscitation and a day-time arrest (0700–2259 hours). In addition the arrest being witnessed was significant for ROSC and younger age was significant for survival to discharge.

Conclusions
There are multiple factors that influence clinical outcomes following an in-hospital cardiac arrest and further research to refine these significant variables will assist in the future management of cardiac arrests.

What is known about this topic?
The evaluation of outcomes from in-hospital cardiac arrests focuses on immediate survival expressed as ROSC and survival to hospital discharge. These clinical outcomes have not improved substantially over the last two decades.

What does this paper add?
This paper identifies the factors that are related to ROSC and survival to discharge following the implementation of the ARC 2006 guidelines, which included a refocus on providing quality cardiopulmonary resuscitation with minimal interruptions.

What are the implications for practitioners?
Given that multiple factors can influence clinical outcomes following an in-hospital cardiac arrest, focusing on maximising a range of factors surrounding cardiopulmonary resuscitation is essential to improve outcomes.
An evaluation of New Zealand’s iterative Workforce Service Reviews: a new way of thinking about health workforce planning
Authors: Naccarella Lucio , Greenstock Louise , Wraight Brenda
Published: May 2013

Objective.
To ensure New Zealand’s health workforce was fit for purpose, Health Workforce New Zealand (HWNZ) funded Workforce Service Reviews (WSRs) to develop visions for service reconfiguration and workforce for 2020. This paper describes what makes the WSR processes work, for whom, and in what circumstances.

Method.
Semi-structured interviews informed by a realist evaluation approach were conducted to obtain perceptions and experiences of WSR participants from four WSRs: eye health, palliative care, anaesthesia and aged care.

Results.
The WSR process was a successful means of bringing together professionals from across the health disciplines and building sector capacity to develop new ways of thinking about service and workforce planning. WSRs were constrained by: mixed signals about process and outcomes; being challenged not milestone focussed; lacking clarity about ownership of visions; and variable clarity about next steps. WSRs were optimised by having: a lead clinician with policy know-how, ability to inspire, bring people together, distil ideas into coherent frameworks; and a project manager with project enablement skill sets and expertise in complex systems, implementation, change management.

Conclusions.
Evidence now exists at a point in time about what makes the WSR processes work. Implications for HWNZ are presented using a capacity-building framework to inform future decision making regarding WSRs.

What is known about the topic?
More appropriate workforce planning is required to meet the challenges facing the health workforce, from both the demand and the workforce side. To ensure New Zealand’s healthcare workforce was fit for purpose, HWNZ initiated an iterative WSR process in topic specific areas. The WSRs process was designed to develop a vision of the relevant health service and workforce for 2020, and models of care that were patient-centred and team-based.

What does this paper add?
The paper provides evidence that the WSR process was a successful means for bringing together professionals from across the health disciplines and building sector capacity to develop new ways of thinking about service and workforce planning. The paper presents key enablers of, and barriers to, the WSR iterative process.

What are the implications for practitioners?
The evaluation revealed that a multitude of factors can influence the capacity of the WSR process at the individual (workforce skills and abilities), organisational (leadership and interactions) and systems (infrastructure) levels. Implications for HWNZ on ways to build the capacity of the WSRs according to three capacity-building dimensions are presented to inform future decision making.
Feeding behaviour of the squirrel glider in remnant habitat in Brisbane.
Authors: Dobson M , Goldingay RL , Sharpe DJ
Published: May 2013

The diet of the squirrel glider (Petaurus norfolcensis) was studied in a 45 ha forest remnant
within an urban area close to Brisbane in south-east Queensland. Qualitative observations of
feeding behaviour were conducted during each of 10 months between May 2002 and April
2003, on over 27 P. norfolcensis from at least 10 social groups. Four different feeding
behaviours were recorded from 750 observations. Feeding from flowers accounted for 48% of
the diet. Nectar and pollen were derived from 10 overstorey tree species, though forest red gum
(Eucalyptus tereticornis) dominated because of its high abundance and protracted flowering
period. Honeydew and lerp feeding accounted for 15% and 2% of all observations,
respectively. Searching for arthropods accounted for 35% overall and occurred in 20 different
tree species, where a range of substrates was used. Brushbox (Lophostemon confertus) was the
most important; it was used in all seasons and accounted for 49% of these observations. These
results contrast with assessment of the diet of P. norfolcensis at other sites where a greater
range of broad food types was used. This may reflect the disturbed quality of the habitat at our
site. However, these observations confirm the importance of eucalypt nectar in the diet of this
species.
An early Pleistocene record of a giant koala (Phascolarctidae: Marsupialia) from western Victoria.
Authors: Piper KJ
Published: May 2013

THE pre Holocene-Late Pleistocene record of
Phascolarctos in Australia is extremely meagre.
There are at least two, possibly three extinct species
of Phascolarctos in addition to the extant
Phascolarctos cinereus (Black 1999). P. yorkensis
(syn. Cundokoala yorkensis; Black and Archer 1997)
is known from the Early Pliocene Curramulka Local
Fauna, South Australia (SA), and the Late
Pleistocene Wellington Caves Local Fauna, New
South Wales (Archer et al. 1997; Pledge 1992). P.
stirtoni occurs in the Late Pleistocene Cement Mills
Local Fauna, Queensland, and is known only from a
partial maxilla containing P3-M2 (Bartholomai 1968,
1977). Phascolarctos material from the mid-
Pleistocene Victoria Fossil Cave and Spring Cave,
Naracoorte, SA, have also been referred to P. cf.
stirtoni but remain undescribed (Reed and Bourne
2000; Moriarty et al. 2000). P. maris is known from a
single lower molar from the Early Pliocene Sunlands
Local Fauna, SA (Pledge 1987). Black (1999) cast
doubt on its validity, suggesting its features may fall
within the intraspecific variation of P. stirtoni. If P.
maris is referable to P. stirtoni it is another South
Australian instance of this species, and extends its
range back to the Early Pliocene. The new
phascolarctid material documented here is from the
early Pleistocene Nelson Bay Local Fauna, Portland,
Victoria (141o 35? E; 38o 36? S). It is therefore an
important additional southern occurrence of a species
larger than the living P. cinereus, and is the only pre-
Late Pleistocene record of the Phascolarctidae in
Victoria.
Intraspecific variation in biology and ecology of deer: magnitude and causation
Authors: Putman Rory , Flueck Werner T.
Published: May 2013

It has been noted that the search for patterns in biology to assist our understanding, often leads to over-simplification. That is, we are satisfied with statements that ‘the species as a rule does this’ or, ‘males of this species do that’. But within such generalisations are masked what are often important variations from that supposed norm and in practice there is tremendous variation in morphology, physiology, social organisation and behaviour of any one species. The focus on a supposedly mean optimal phenotype has diverted attention away from variation around that mean, which is regularly regarded as a kind of ‘noise’ stemming merely from stochastic effects, and thus irrelevant to evolution. Yet it is becoming increasingly clear that this variation is by converse extremely significant and of tremendous importance both to evolutionary biologists and to managers. Such intraspecific variation (IV) may be directly due to underlying genetic differences between individuals or populations within a species, but equally may include a degree of phenotypic plasticity whether as ‘non-labile’, traits which are expressed once in an individual’s lifetime, as fixed characteristics inherited from the parents or as more labile traits which are expressed repeatedly and reversibly in a mature individual according to prevailing conditions.
Recognition of the extraordinary degree of IV which may be recorded within species has important consequences for management of cervids and conservation of threatened species. We review the extent of IV in diet, in morphology, mature bodyweight, reproductive physiology, in population demography and structure (sex ratio, fecundity, frequency of reproduction) before also reviewing the striking variation to be observed in behaviour: differences between individuals or populations in ranging behaviour, migratory tendency, differences in social and sexual organisation. In each case we explore the factors which may underlie the variation observed, considering the extent to which variation described has a primarily genetic basis or is a more plastic response to more immediate social and ecological cues.
Assessing rarity and threat in an arid-zone flora
Authors: Silcock J. L. , Fensham R. J. , Martin T. G.
Published: May 2013

An understanding of rarity and how it relates to extinction risk is a central concern of conservation biology. Classic conceptions of rarity revolve around spatial rarity, based on distribution and abundance, rather than temporal rarity, where species may be common following certain conditions but rare for most of the time. This form of rarity is likely to be especially prevalent in highly variable arid systems. Rarity in the arid zone is also characterised by poorly understood threats, such as grazing, and may also reflect low collection effort given the vast and inaccessible areas involved. This study explores rarity and threat in the arid zone, based on the flora of a large region of western Queensland. The status of all species known to occur in the study area was systematically assessed, and the current list of threatened species was examined for bias in forms of rarity, life forms and habitats. Five threat syndromes were identified, arising from the interaction of plant biology and threatening processes. Over 60 potentially threatened species have been overlooked in the listing process. The list is dominated by narrow endemics from residual and spring habitats and the species from springs at least are genuinely threatened. Widespread but sparsely occurring species are under-represented in the current list, as are grasses. With the exception of spring-dependent species, plant conservation in western Queensland is currently constrained by lack of basic data on distribution, abundance, population dynamics and realistic threat syndromes for nearly all species. Separating the influence of genuine rarity, temporal rarity and low collection effort, as well as a more detailed understanding of threatening processes are needed to address plant conservation in the arid zone.
Fluorescence Quenching of Quantum Dots by DNA Nucleotides and Amino Acids
Authors: Siegberg Daniel , Herten Dirk-Peter
Published: May 2013

Quantum dots found widespread application in the biosciences as bright and highly photo-stable fluorescent probes, i.e. for single-particle tracking. In this work we used ensemble spectroscopy and single-molecule techniques to study the quenching of quantum dots by various biochemical compounds that are usually present in living cells and might thus influence the experiments. We found not only nucleotides such as cytosine, guanine, and thymine can significantly influence the fluorescence emission of CdSe and CdTe quantum dots, but also amino acids, like asparagine and tryptophan. Bulk studies on fluorescence quenching indicated a static quenching mechanism. Interestingly, we could also show by single-molecule fluorescence spectroscopy that quenching of the quantum dots can be irreversible, suggesting either a redox-reaction between quantum dot and quencher or strong binding of the quencher to the surface of the bio-conjugated quantum dots.