bluuebunny/crossref_metadata_2025 huggingface dataset:
Uniform magnetic field distribution of a spatially structured resonant coil for wireless power transfer
Authors: Lee Wang-Sang , Lim Lee Han , Oh Kyoung-Sub , Yu Jong-Won
Published: May 2012

A spatially structured resonant coil with uniform magnetic field distribution for wireless power transfer is presented. The characteristics of the proposed resonant coil are verified by the theoretical analysis, simulation results, and experimental measurements. Due to the uniform magnetic field distribution, the overall transfer efficiency between the transmitting and receiving resonant coils can be improved up to 44% compared to the conventional coil regardless of the location of the receiving coil at the transfer distance.
Vacancy clustering and its dissociation process in electroless deposited copper films studied by monoenergetic positron beams
Authors: Uedono A. , Yamashita Y. , Tsutsui T. , Dordi Y. , Li S. , Oshima N. , Suzuki R.
Published: May 2012

Positron annihilation was used to probe vacancy-type defects in electroless deposited copper films. For as-deposited films, two different types of vacancy-type defects were found to coexist; these were identified as vacancy aggregates (V3-V4) and larger vacancy clusters (∼V10). After annealing at about 200 °C, the defects started to diffuse toward the surface and aggregate. The same tendency has been observed for sulfur only, suggesting the formation of complexes between sulfur and vacancies. The defect concentration near the Cu/barrier-metal interface was high even after annealing above 600 °C, and this was attributed to an accumulation of vacancy-impurity complexes. The observed defect reactions were attributed to suppression of the vacancy diffusion to sinks through the formation of impurity-vacancy complexes. It was shown that electroless plating has a high potential to suppress the formation of voids/hillocks caused by defect migration.
First-principles analysis of structural and opto-electronic properties of indium tin oxide
Authors: Tripathi Madhvendra Nath , Shida Kazuhito , Sahara Ryoji , Mizuseki Hiroshi , Kawazoe Yoshiyuki
Published: May 2012

Density functional theory (DFT) and DFT + U (DFT with on-site Coulomb repulsion corrections) calculations have been carried out to study the structural and opto-electronic properties of indium tin oxide (ITO) for both the oxidized and reduced environment conditions. Some of the results obtained by DFT calculations differ from the experimental observations, such as uncertain indication for the site preference of tin atom to replace indium atom at b-site or d-site, underestimation of local inward relaxation in the first oxygen polyhedra around tin atom, and also the improper estimation of electronic density of states and hence resulting in an inappropriate optical spectra of ITO. These discrepancies of theoretical outcomes with experimental observations in ITO arise mainly due to the underestimation of the cationic 4d levels within standard DFT calculations. Henceforth, the inclusion of on-site corrections within DFT + U framework significantly modifies the theoretical results in better agreement to the experimental observations. Within this framework, our calculations show that the indium b-site is preferential site over d-site for tin atom substitution in indium oxide under both the oxidized and reduced conditions. Moreover, the calculated average inward relaxation value of 0.16 Å around tin atom is in good agreement with the experimental value of 0.18 Å. Furthermore, DFT + U significantly modify the electronic structure and consequently induce modifications in the calculated optical spectra of ITO.
Lamb wave near field enhancements for surface breaking defects in plates
Authors: Clough A. R. , Edwards R. S.
Published: May 2012

Near field surface wave ultrasonic enhancements have previously been used to detect surface breaking defects in thick samples using Rayleigh waves. Here, we present analogous surface wave enhancements for Lamb waves propagating in plates. By tracking frequency intensities in selected regions of time-frequency representations, we observe frequency enhancement in the near field, due to constructive interference of the incident wave mode with those reflected and mode converted at the defect. This is explained using two test models; a square based notch and an opening crack, which are used to predict the contribution to the out-of-plane displacement from the reflected and mode converted waves. This method has the potential to provide a reliable method for the near field identification and characterisation of surface breaking defects in plates.
Photophysics and morphology of poly (3-dodecylthienylenevinylene)-[6,6]–phenyl-C61-butyric acid methyl ester composite
Authors: Lafalce E. , Toglia P. , Zhang C. , Jiang X.
Published: May 2012

A series of low band gap poly(3-dodecylthienylenevinylene) (PTV) with controlled morphological order have been synthesized and blended with the electron acceptor [6,6]–phenyl-C61-butyric acid methyl ester (PCBM) for organic photovoltaic devices. Two polymers with the most and least side chain regioregularity were chosen in this work, namely the PTV010 and PTV55, respectively. Using photoluminescence, photo-induced absorption spectroscopy, and atomic force microscopy, we find no direct evidence of photoinduced charge transfer between the two constituents, independent of the bulk-heterojunction morphology of the film, although the possibility of formation of P+/C60− charge transfer complex was not completely ruled out. The large exciton binding energy (Eb = 0.6 eV) in PTV inhibits the photoinduced electron transfer from PTV to PCBM. In addition, excitons formed on polymer chains suffer ultrafast (<ps) intrachain decay to the dark 2Ag state in both PTV010 and PTV55 cases, whereas excitons generated on PCBM molecules undergo energy transfer only to PTV55 in the blend film. Thus, the addition of PCBM increases the photoluminescence yield with respect to neat polymer yield. The efficiency of the energy transfer process is shown to depend on the degree of polymer and PCBM intermixing within the film, which in turn is governed by the polymer chain orders. The effect of such intermixing on the resulting kinetics of photo-induced excitations is also discussed. Our results show limited effect of polymer crystallinity of PTV to its excitonic properties, much the contrary of the case with poly (3-hexylthiophene) which has similar chemical structure with PTV.
Glass polarization induced drift in microelectromechanical capacitor
Authors: Haarahiltunen A. , Varpula A. , Leinvuo J. , Siren E. , Rytkönen V.-P. , Savin H.
Published: May 2012

We present a quantitative physical model for glass substrate polarization and study the glass polarization by measuring the capacitance drift from microelectromechanical capacitor test structure. The model consists of mobile and immobile charge species, which are related to alkali metals and non-bridging oxygen in glass. The model explains consistently our results and the previously observed non-homogeneous charging effect in a radio-frequency switch fabricated on a glass substrate. The results indicate that the bulk properties of the glass layer itself can be a significant source of drift. The modeling allows estimation of the drift behavior of the several kinds of device structures.
Spin and valley dependent electronic transport in strain engineered graphene
Authors: Niu ZhiPing
Published: May 2012

We study the effect of the gauge potential A→S induced by a local strain on electronic transport in a strain engineered graphene junction. For the normal/strained/normal/strained/normal graphene junction, by changing the sign of A→S the K and K' valleys are interchanged, the conductance can change from finite to zero, so we obtain the valley valve effect. For the ferromagnetic/strained/ferromagnetic graphene junction in the parallel magnetization configuration by adjusting the gauge potential strength AS only the incident electrons in the spin-down channel are allowed to transmit, thus we can observe the strain-tunable spin filter effect. The magnetoresistance increases with AS and can reach up to 100%. It is expected these features may be helpful in the design of the strain-tunable spintronic devices.
Local order and electronic structure of Pb1−xLaxZr0.40Ti0.60O3 materials and its relation with ferroelectric properties
Authors: Mesquita A. , Michalowicz A. , Mastelaro V. R.
Published: May 2012

The knowledge of electronic and local structures is a fundamental step towards understanding the properties of ferroelectric ceramics. X-ray absorption near-edge structure (XANES) of Pb1−xLaxZr0.40Ti0.60O3 ferroelectric samples was measured in order to know how the local order and electronic structure are related to their ferroelectric property, which was tailored by the substitution of lead by lanthanum atoms. The analysis of XANES spectra collected at Ti K- and L-edges XANES showed that the substitution of Pb by La leads to a decrement of local distortion around Ti atoms on the TiO6 octahedron. The analysis of O K-edge XANES spectra showed that the hybridization between O 2p and Pb 6sp states is related to the displacement of Ti atoms in the TiO6 octahedra. Based on these results, it is possible to determine that the degree of ferroelectricity in these samples and the manifestation of relaxor behavior are directly related to the weakening of O 2p and Pb 6sp hybridization.
Dynamic relaxation of a liquid cavity under amorphous boundary conditions
Authors: Cavagna Andrea , Grigera Tomás S. , Verrocchio Paolo
Published: May 2012

The growth of cooperatively rearranging regions was invoked long ago by Adam and Gibbs to explain the slowing down of glass-forming liquids. The lack of knowledge about the nature of the growing order, though, complicates the definition of an appropriate correlation function. One option is the point-to-set (PTS) correlation function, which measures the spatial span of the influence of amorphous boundary conditions on a confined system. By using a swap Monte Carlo algorithm we measure the equilibration time of a liquid droplet bounded by amorphous boundary conditions in a model glass-former at low temperature, and we show that the cavity relaxation time increases with the size of the droplet, saturating to the bulk value when the droplet outgrows the point-to-set correlation length. This fact supports the idea that the point-to-set correlation length is the natural size of the cooperatively rearranging regions. On the other hand, the cavity relaxation time computed by a standard, nonswap dynamics, has the opposite behavior, showing a very steep increase when the cavity size is decreased. We try to reconcile this difference by discussing the possible hybridization between mode-coupling theory and activated processes, and by introducing a new kind of amorphous boundary conditions, inspired by the concept of frozen external state as an alternative to the commonly used frozen external configuration.
Organic bulk heterojunction photovoltaic devices with surfactant-free Au nanoparticles embedded in the active layer
Authors: Spyropoulos George D. , Stylianakis Minas M. , Stratakis Emmanuel , Kymakis Emmanuel
Published: May 2012

The effect of embedding uncapped Au nanoparticles, produced by ultrafast laser ablation in liquids, in the active layer of bulk heterojunction organic photovoltaic devices was systematically studied. The nanoparticles incorporation leads to a power conversion efficiency improvement of 40%. This efficiency gain was attributed to enhanced light harvesting and subsequent exciton generation rate into the photoactive layer due to localized surface plasmon resonance and scattering effects. This argument was supported by the combinatorial study of spectroscopic analysis and photon to-electron conversion efficiency measurements of the devices.
Effects of long-range tip-sample interaction on magnetic force imaging: A comparative study between bimorph driven system and electrostatic force modulation
Authors: Kim Byung I.
Published: May 2012

Magnetic force microscopy (MFM) using electrostatic force modulation has been designed and developed to avoid the drawbacks of the bimorph driven system. The bimorph driven system has poor frequency response and overlap of the topographic features on magnetic structures of the MFM images. In the electrostatic force modulation system, the amplitude increases in the noncontact regime as the tip approaches due to the capacitive coupling between tip and sample. MFM using electrostatic force modulation has been applied to observe maze-like stripe domain structures on a CoCr film. The contrast mechanism and imaging stability of MFM using electrostatic force modulation are discussed by investigating the force distance curves obtained in two magnetic domain regions.
Mode characterization of sub-micron equilateral triangular microcavity including material’s dispersion effects
Authors: Lai C.-M. , Yeh P. C. , Peng L.-H.
Published: May 2012

We report the study of resonant modes in an equilateral triangular gallium nitride (GaN) microcavity, with the material’s dispersion taken into account. From the polarization-resolved photo-luminescence measurements, we observed the resonance of GaN bandedge emission with the cavity modes to be transverse magnetic-polarization active and characterized with a quality factor as high as ∼1000 in a GaN cavity of 0.75 µm side length. Using a finite difference time domain technique, we showed that these observations can be ascribed to the material’s dispersion effects. The latter can modify the cavity phase-matching condition, reduce the spectral bandwidth of the corresponding resonant modes and enhance the cavity quality factor by a factor more than three.
Admittance and subthreshold characteristics of atomic-layer-deposition Al2O3 on In0.53Ga0.47As in surface and buried channel flatband metal-oxide-semiconductor field effect transistors
Authors: Paterson G. W. , Bentley S. J. , Holland M. C. , Thayne I. G. , Ahn J. , Long R. D. , McIntyre P. C. , Long A. R.
Published: May 2012

The admittances and subthreshold characteristics of capacitors and MOSFETs on buried and surface In0.53Ga0.47As channel flatband wafers, with a dielectric of Al2O3 deposited on In0.53Ga0.47As, are reported. The admittance characteristics of both wafers indicate the presence of defect states within the oxide, in common with a number of other oxides on In0.53Ga0.47As. The two wafers studied have not been hydrogen annealed, but do show some similar features to FGA treated oxides on n+ substrates. We discuss how the possible presence of residual hydroxyl ions in as-grown Al2O3 may explain these similarities and also account for many of the changes in the properties of FGA treated n+ samples. The issues around the comparison of subthreshold swing (SS) results and the impact of transistor design parameters on the energy portion of the defect state distribution affecting efficient device switching are discussed. The interface state model is applied to low source-drain voltage SS data to extract an effective interface state density (Dit) that includes interface and oxide traps. The logarithmic gate voltage sweep rate dependence of the SS Dit is used to extract an oxide trap density (Dot) and a simple method is used to estimate the Fermi level position within the band gap, Et. The Al2O3 Dit(Et) and Dot(Et) distributions are found to be similar to each other and to the results of our analysis of Gd0.25Ga0.15O0.6/Ga2O3 and HfO2/Al2O3 on In0.53Ga0.47As, adding weight to the suggestion of there being a common defect state distribution and perhaps a common cause of defects states for a number of oxides on In0.53Ga0.47As.
Rotational dynamics in supercooled water from nuclear spin relaxation and molecular simulations
Authors: Qvist Johan , Mattea Carlos , Sunde Erik P. , Halle Bertil
Published: May 2012

Structural dynamics in liquid water slow down dramatically in the supercooled regime. To shed further light on the origin of this super-Arrhenius temperature dependence, we report high-precision 17O and 2H NMR relaxation data for H2O and D2O, respectively, down to 37 K below the equilibrium freezing point. With the aid of molecular dynamics (MD) simulations, we provide a detailed analysis of the rotational motions probed by the NMR experiments. The NMR-derived rotational correlation time τR is the integral of a time correlation function (TCF) that, after a subpicosecond librational decay, can be described as a sum of two exponentials. Using a coarse-graining algorithm to map the MD trajectory on a continuous-time random walk (CTRW) in angular space, we show that the slowest TCF component can be attributed to large-angle molecular jumps. The mean jump angle is ∼48° at all temperatures and the waiting time distribution is non-exponential, implying dynamical heterogeneity. We have previously used an analogous CTRW model to analyze quasielastic neutron scattering data from supercooled water. Although the translational and rotational waiting times are of similar magnitude, most translational jumps are not synchronized with a rotational jump of the same molecule. The rotational waiting time has a stronger temperature dependence than the translation one, consistent with the strong increase of the experimentally derived product τR DT at low temperatures. The present CTRW jump model is related to, but differs in essential ways from the extended jump model proposed by Laage and co-workers. Our analysis traces the super-Arrhenius temperature dependence of τR to the rotational waiting time. We present arguments against interpreting this temperature dependence in terms of mode-coupling theory or in terms of mixture models of water structure.
Effect of Lorentz local field for optical second order nonlinear susceptibility in ZnO nanorod
Authors: Zhuo Guan-Yu , Hsu Kuo-Jen , Su Tung-Yu , Huang Nan-Hsun , Chen Yang-Fang , Chu Shi-Wei
Published: May 2012

Nonlinear optical properties of ZnO nanorods (NRs) are strongly influenced by its dimension and aspect ratio. Size-dependent second harmonic generation (SHG) in ZnO NRs has been investigated with polarized excitations recently. However, detailed description to the SHG dependency with NR dimensions has not yet been given. In this paper, the relationship between rod diameter/length and corresponding χ(2) values based on Lorentz local field is established, both theoretically and experimentally, for the first time. Theoretically, Lorentz local field induced spectral red shift and the consequent dielectric constant modification is used to elucidate the size effect for χ(2) under the condition that both excitation and SHG wavelengths are far from the band gap. Experimentally, χ(2) of ZnO nanorods with various sizes is measured via Maker fringe technique, and the results fit well to our theory.
Anomalous length scaling of carbon nanotube-metal contact resistance: An ab initio study
Authors: Kim Yong-Hoon , Sung Kim Hu
Published: May 2012

Employing open-ended carbon nanotubes (CNTs) with and without hydrogen termination, we study the length scaling of metal-CNT contact resistance and its correlation with chemical bonding from first principles. Both models similarly show a transition from the fast-growing short-length scaling to the slow-growing long-length scaling. However, while the hydrogenated CNTs have much lower short-length resistances than H-free CNTs, Schottky barrier of the former is almost twice thicker and its eventual long-length-limit resistance becomes significantly higher. This demonstrates the critical role of atomistic details in metal-CNT contacts and localized CNT edge states for the Schottky barrier shape and metal-induced gap states.
Determination of excitonic size with sub-nanometer precision via excitonic Aharonov-Bohm effect in type-II quantum dots
Authors: Roy B. , Ji H. , Dhomkar S. , Cadieu F. J. , Peng L. , Moug R. , Tamargo M. C. , Kuskovsky I. L.
Published: May 2012

A spectral analysis of the Aharonov-Bohm (AB) oscillation in magneto-photoluminescence intensity was performed for stacked type-II ZnTe/ZnSe quantum dots (QDs). Very narrow AB oscillations (∼0.3 T) allowed for probing of both the lateral size distribution in the stack ensemble of QDs and the size of type-II excitons as determined by the electronic orbit with sub-nanometer precision. Two sets of stacks with excitonic size of 18.2 and 17.5 nm are determined to be present in the sample.
Extremely high-density GaAs quantum dots grown by droplet epitaxy
Authors: Jo M. , Mano T. , Sakuma Y. , Sakoda K.
Published: May 2012

We report the fabrication of extremely high-density GaAs quantum dots (QDs) by droplet epitaxy. We investigated the dependence of temperature and coverage on the dot density. As a result, an areal density of 7.3 × 1011  cm−2 was achieved at a growth temperature of 30 °C by controlling the amount of Ga. The QDs showed clear luminescence even when grown at a low temperature of 30 °C.
Binary cholesteric/blue-phase liquid crystal textures fabricated using phototunable chirality in azo chiral-doped cholesteric liquid crystals
Authors: Liu Cheng-Kai , Huang Wan-Ling , Ying-Guey Fuh Andy , Cheng Ko-Ting
Published: May 2012

This work demonstrates the binary cholesteric/blue-phase liquid crystal (CLC/BP-LC) textures fabricated using phototunable chirality in azo chiral-doped CLCs (ACdCLCs). The key mechanism is the effective optically controllable chirality of the ACdCLCs, resulting from the competition between the right- and left-hand chirality in ACdCLCs following the illumination by specific types of light. By properly selecting AC materials, the texture can be optically switched between BP-LC platelets and CLCs. Moreover, the AC diffusion behavior is also discussed in detail.
Means to remove electrode contamination effect of Langmuir probe measurement in space
Authors: Oyama K.-I. , Lee C. H. , Fang H. K. , Cheng C. Z.
Published: May 2012

Precaution to remove the serious effect of electrode contamination in Langmuir probe experiments has not been taken in many space measurements because the effect is either not understood or ignored. We stress here that one should pay extra attention to the electrode contamination effect to get accurate and reliable plasma measurements so that the long time effort for sounding rocket/satellite missions does not end in vain or becomes less fruitful. In this paper, we describe two main features of voltage–current characteristic curves associated with the contaminated Langmuir probe, which are predicted from the equivalent circuit model, which we proposed in 1970's. We then show that fast sweeping dc Langmuir probes can give reliable results in the steady state regime. The fast sweeping probe can also give reliable results in transient situations such as satellite moves through plasma bubble in the ionosphere where the electron density drastically changes. This fact was first confirmed in our laboratory experiment.
Threshold voltage shift and drain current degradation by negative bias temperature instability in Si (110) p-channel metal-oxide-semiconductor field-effect transistor
Authors: Ota K. , Saitoh M. , Nakabayashi Y. , Ishihara T. , Uchida K. , Numata T.
Published: May 2012

Negative bias temperature instability in Si (100) and (110) p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) is systematically studied. Threshold voltage shift in (110) pMOSFETs is found to be larger than that in (100) pMOSFETs because of larger amount of the generated interface traps. On the other hand, mechanisms behind the generation of the interface traps are independent of the surface orientations. We newly found that drain current degradation in (110) pMOSFETs is severer than that in (100) pMOSFETs even when the same amount of charges is generated at the interface. This can be explained by larger mobility degradation in (110) pMOSFETs.
Enhancement of inverted polymer solar cells with solution-processed ZnO-TiOX composite as cathode buffer layer
Authors: Liu Jian , Shao Shuyan , Meng Bin , Fang Gang , Xie Zhiyuan , Wang Lixiang , Li Xinglin
Published: May 2012

Solution-processed zinc oxide (ZnO) nanocrystal modified with titanium oxide (TiOX) precursor is introduced as cathode interfacial layer in inverted bulk-heterojunction polymer solar cells. The resultant inverted polymer solar cell exhibits an open-circuit voltage of 0.87 V, a fill factor of 0.67, and an overall power conversion efficiency of 6.53%, respectively, higher than those of the control cells with sole ZnO or TiOX as the cathode interfacial layers. Further studies verify that the improved morphology and electronic structure of ZnO-TiOX composite layer favors reducing shunt loss and interfacial charge recombination and hence enhancing the photovoltaic performance.
Double quantum-well tunnel junctions with high peak tunnel currents and low absorption for InP multi-junction solar cells
Authors: Lumb Matthew P. , Yakes Michael K. , González María , Vurgaftman Igor , Bailey Christopher G. , Hoheisel Raymond , Walters Robert J.
Published: May 2012

Lattice matched InAlGaAs tunnel junctions with a 1.18 eV bandgap have been grown for a triple-junction solar cell on InP. By including two InGaAs quantum wells in the structure, a peak tunnel current density of 113 A/cm2 was observed, 45 times greater than the baseline bulk InAlGaAs tunnel junction. The differential resistance of the quantum well device is 7.52 × 10−4 Ω cm2, a 15-fold improvement over the baseline device. The transmission loss to the bottom cell is estimated to be approximately 1.7% and a network simulation demonstrates that quantum well tunnel junctions play a key role in improving performance at high sun-concentrations.
Monolithically integrated, resonant-cavity-enhanced dual-band mid-infrared photodetector on silicon
Authors: Wang Jianfei , Zens Timothy , Hu Juejun , Becla Piotr , Kimerling Lionel C. , Agarwal Anuradha M.
Published: May 2012

In this paper, we present experimental demonstration of a resonant-cavity-enhanced mid-infrared photodetector monolithically fabricated on a silicon substrate. Dual-band detection at 1.6 μm and 3.7 μm is achieved within a single detector pixel without cryogenic cooling, by using thermally evaporated nanocrystalline PbTe as the photoconductive absorbers. Excellent agreement between theory and experiment is confirmed. The pixel design can potentially be further extended to realizing multispectral detection.
Thin metal oxide films to modify a window layer in CdTe-based solar cells for improved performance
Authors: Lemmon John P. , Polikarpov Evgueni , Bennett Wendy D. , Kovarik Libor
Published: May 2012

We report on CdS/CdTe photovoltaic devices containing a thin Ta2O5 film deposited onto the CdS window layer. For thicknesses below 5 nm, Ta2O5 films between CdS and CdTe improve the solar cell performance despite the insulating nature of the interlayer material. Using the Ta2O5 interlayer, an open circuit voltage (VOC) gain of over 100 mV was demonstrated compared to a CdTe/CdS baseline. A Ta2O5 interlayer enabled the fabrication of CdTe solar cells with extremely thin (less than 30 nm) CdS layers. The efficiency of these cells exceeded that of a base line cell with 95 nm of CdS.
Transmission properties of surface-plasmon-polariton coherence
Authors: Aihara Takuma , Fukuda Mitsuo
Published: May 2012

The transmission properties of the coherent optical signal through surface plasmon polaritons (SPPs) were investigated using a delayed self-heterodyne method. The beat spectra between the light beam through SPPs and the reference beam were observed. As the distance propagated as SPPs increases, the full width at half maximum values of the beat spectra was constant, with only decreasing peak values of the beat spectra. The retention of the coherence is also confirmed by analytical calculations based on a Drude model.
Accumulation mode field-effect transistors for improved sensitivity in nanowire-based biosensors
Authors: Baek David J. , Duarte Juan P. , Moon Dong-Il , Kim Chang-Hoon , Ahn Jae-Hyuk , Choi Yang-Kyu
Published: May 2012

In this work, nanowire field-effect transistors (NW-FETs) constructed from a top-down approach has been utilized for the detection of biomolecules. Here, we demonstrate that the sensitivity of NW-FET sensors can be greatly enhanced when the same dopant type is used for both channel region and source and drain. This type of FET, known as accumulation mode field-effect transistors (AM-FETs), functions under different operating principle compared with conventional inversion mode FETs. The improved sensitivity is attributed to the different conduction mechanism and current components of AM devices. The results have been verified through a direct comparison with a conventional FET.
The future of community-centred health services in Australia - an alternative view
Authors: Cunningham Paul A.
Published: May 2012

Community-centred healthcare works in conjunction with hospital-centred healthcare. Both have strengths and limitations. Community-centred healthcare has been demonstrated to be a more cost-efficient and cost-effective alternative to hospital-centred care at best in a limited fashion. If hospital-centred services dominate healthcare services in Australia, as argued previously in this journal, then this has not extended to maintenance of inpatient bed provision. The author, as a hospital-based emergency specialist, has observed case load and models of care in hospitals and emergency departments for 30 years and is sceptical of promises to substantially further decrease emergency department demand and acute bed requirements. The real benefits of community, primary and preventive care should not be over sold. What is known about the topic? Community-centred healthcare has not been widely demonstrated to be a more cost-efficient and cost-effective alternative to hospital-centred care for acute conditions, even when these conditions are superimposed on a chronic condition. What does this paper add? The author makes a plea for a reasoned and evidence-based approach to the distribution of finite health resources. Experts in the fields of acute, chronic and preventive health measures should present plans that less knowledgeable decision makers can implement appropriately. What are the implications for practitioners? Experienced health experts need to balance the argument, including advocacy for adequate acute care and hospital-based services. Practitioners who require acute hospital beds for the safe and humane management of their patients may need to argue for legislative definition of bed numbers per population size.
Safety of non-medically led primary maternity care models: a critical review of the international literature
Authors: McIntyre Meredith J.
Published: May 2012

The Australian government has announced major reforms with the move to a primary maternity care model. The direction of the reforms remains contentious; with the Australian Medical Association warning that the introduction of non-medically led services will compromise current high standards in maternity services and threaten the safety of mothers and babies. The purpose of this paper is to conduct a critical review of the literature to determine whether there is convincing evidence to support the safety of non-medically led models of primary maternity care. Twenty-two non-randomised international studies were included representing midwifery-led care, birth centre care and home birth. Comparative outcome measurements included: perinatal mortality; perinatal morbidity; rates of medical intervention in labour; and antenatal and intrapartum referral and transfer rates. Findings support those of the three Cochrane reviews, that there is sufficient international evidence to support the conclusion of no difference in outcomes associated with low risk women in midwifery-led, birth centre and home birth models compared with standard hospital or obstetric care. These findings are limited to services involving qualified midwives working within rigorous exclusion, assessment and referral guidelines, limiting the number of urgent intrapartum transfers that come with increased risk of perinatal mortality. What is known about the topic? Systematic reviews of maternal and perinatal outcomes associated with midwifery-led care when compared to conventional intrapartum hospital care concluded that these non-medically led models of care are associated with several benefits for low risk women and their babies with no identified adverse effects. What does this paper add? The finding of no difference in outcomes associated with midwifery-led, birth centre and home birth compared with standard hospital or obstetric care is limited to international studies involving women in the care of qualified midwives working within rigorous guidelines for practice involving inter-professionally agreed exclusion, assessment and referral criteria. What are the implications for practitioners? Midwives caring for women in non-medically led models are urged to be vigilant to the need for early detection and prompt action in the event of unforseen complications to avoid an over emphasis on normality. This decreases the likelihood of urgent intrapartum transfers that come with an increased risk of perinatal mortality.
Workplace abuse among correctional health professionals in New South Wales, Australia
Authors: Cashmore Aaron W. , Indig Devon , Hampton Stephen E. , Hegney Desley G. , Jalaludin Bin
Published: May 2012

Objective. Studies have found that health workers are at elevated risk of being abused while at work. Little is known, however, about workplace abuse among correctional health professionals. We implemented a cross-sectional study to investigate the prevalence, sources and consequences of workplace abuse among correctional health professionals in New South Wales, Australia. Methods. All employees of Justice Health (a statutory health corporation) were invited to complete a self-administered survey, which was delivered via the internet. Among nurses, medical doctors and allied health professionals, 299 usable surveys were returned; a response rate of 42%. Results. In the preceding 3 months, 76% of participants had personally experienced some form of abuse in their workplace, all but one of whom recalled verbal abuse. Only 16% reported physical abuse. Seventy per cent reported feeling safe in their workplace. Patients were identified as the main perpetrators of abuse, followed by fellow health staff. Participants felt that incidents of workplace abuse increased their potential to make errors while providing care to patients and reduced their productivity while at work. Conclusions. Compared with health workers who practise in a community setting, the risk of physical abuse among correctional health professionals appears to be low. What is known about the topic? Health professionals are at a high risk of workplace abuse. Studies have demonstrated that the risk of abuse varies by health profession and the practice environment. There is a paucity of research exploring workplace abuse among correctional health professionals. What does this paper add? A cross-sectional survey found that a relatively small proportion of correctional health professionals in New South Wales had been subjected to physical abuse in their workplace in the preceding 3 months. Verbal abuse, however, was reported by a majority of participants. Although patients were the most commonly reported source of abuse, a worrying level of health worker on health worker abuse (also known as horizontal abuse) was found. What are the implications for practitioners? Preventive strategies should address the temporal, environmental and structural determinants of workplace abuse in correctional and forensic facilities. More research is needed to identify the factors associated with horizontal abuse among correctional health professionals. This would allow the establishment of tailored preventive programs.
Research performance evaluation: the experience of an independent medical research institute
Authors: Schapper Catherine C. , Dwyer Terence , Tregear Geoffrey W. , Aitken MaryAnne , Clay Moira A.
Published: May 2012

Background.
Evaluation of the social and economic outcomes of health research funding is an area of intense interest and debate. Typically, approaches have sought to assess the impact of research funding by medical charities or regional government bodies. Independent research institutes have a similar need for accountability in investment decisions but have different objectives and funding, thus the existing approaches are not appropriate.

Methods.
An evaluation methodology using eight indicators was developed to assess research performance across three broad categories: knowledge creation; inputs to research; and commercial, clinical and public health outcomes. The evaluation approach was designed to provide a balanced assessment across laboratory, clinical and public health research.

Results and discussion.
With a diverse research agenda supported by a large number of researchers, the Research Performance Evaluation process at the Murdoch Childrens Research Institute has, by necessity, been iterative and responsive to the needs of the Institute and its staff. Since its inception 5 years ago, data collection systems have been refined, the methodology has been adjusted to capture appropriate data, staff awareness and participation has increased, and issues regarding the methodology and scoring have been resolved.

Conclusions.
The Research Performance Evaluation methodology described here provides a fair and transparent means of disbursing internal funding. It is also a powerful tool for evaluating the Institute’s progress towards achieving its strategic goals, and is therefore a key driver for research excellence.

What is known about the topic?
Increasingly, research funders are seeking to evaluate the impact and outcomes of research spending in order to inform policy decisions and guide research funding expenditure. However, in most instances, research evaluation activities are not undertaken by the organisation conducting the actual research and may not meet their practical needs.

What does this paper add?
The paper outlines a research performance evaluation methodology specifically tailored to the needs of the medical research institute conducting the research being evaluated, as a way of evaluating research performance to drive strategic goals and disburse internal funds.

What are the implications for practitioners?
This paper provides a clear approach to internal research evaluation using a process that meets the needs of the organisation actually conducting the research, and provides institutional data for strategic planning activities.
In vitro loading of human cohesin on DNA by the human Scc2-Scc4 loader complex
Authors: Bermudez Vladimir P. , Farina Andrea , Higashi Torahiko L. , Du Fang , Tappin Inger , Takahashi Tatsuro S. , Hurwitz Jerard
Published: May 2012

The loading of cohesin onto chromatin requires the heterodimeric complex sister chromatid cohesion (Scc)2 and Scc4 (Scc2/4), which is highly conserved in all species. Here, we describe the purification of the human (h)-Scc2/4 and show that it interacts with h-cohesin and the heterodimeric Smc1-Smc3 complex but not with the Smc1 or Smc3 subunit alone. We demonstrate that both h-Scc2/4 and h-cohesin are loaded onto dsDNA containing the prereplication complex (pre-RC) generated in vitro by
Xenopus
high-speed soluble extracts. The addition of geminin, which blocks pre-RC formation, prevents the loading of Scc2/4 and cohesin.
Xenopus
extracts depleted of endogenous Scc2/4 with specific antibodies, although able to form pre-RCs, did not support cohesin loading unless supplemented with purified h-Scc2/4. The results presented here indicate that the
Xenopus
or h-Scc2/4 complex supports the loading of
Xenopus
and/or h-cohesin onto pre-RCs formed by
Xenopus
high-speed extracts. We show that cohesin loaded onto pre-RCs either by h-Scc2/4 and/or the
Xenopus
complex was dissociated from chromatin by low salt extraction, similar to cohesin loaded onto chromatin in G
1
by HeLa cells in vivo
.
Replication of cohesin-loaded DNA, both in vitro and in vivo, markedly increased the stability of cohesin associated with DNA. Collectively, these in vitro findings partly recapitulate the in vivo pathway by which sister chromatids are linked together, leading to cohesion.
Laboratory Testing of a Modified Electroshocking System Designed for Deepwater Juvenile Lamprey Sampling
Authors: Mueller Robert , Arntzen Evan , Nabelek Marc , Miller Ben , Klett Katherine , Harnish Ryan
Published: May 2012

A submersible sled with the ability to electroshock and detect larval lampreys via an optical camera was developed to sample deepwater rearing habitats (>1 m). Three trials, each with 10 juvenile western brook lampreys Lampetra richardsoni (70–150 mm), were conducted in a laboratory setting to determine the effective shocking area and detection efficiency of the device. Electroshock was delivered for 30 s, and lamprey responses were observed. The detection efficiency ranged from 40% to 70% for the three trials (mean detection efficiency = 60%). Mean postshock emergence time was 4.4 s, and the maximum was 13 s. The device detected juvenile western brook lampreys without the need to transport them to the surface, thereby increasing sampling volume per unit time and reducing the potential for injury caused by handling. The system was developed to determine juvenile lamprey presence in regions where backpack electrofishers are unable to survey due to water depth.
Congruency effects in conceptualizing for speech
Authors: Kuipers Jan-Rouke , La Heij Wido
Published: May 2012

In naming a picture at the basic level, a semantically related distractor word induces interference in comparison to an unrelated word. When the task is changed from basic-level naming to categorization, however, this effect reverses to semantic facilitation. In previous studies, this semantic facilitation effect was attributed to “message congruency” at the conceptual level. The present study examines the nature of this message congruency effect: Is it due to competition between two activated category concepts in the incongruent condition or is it due to convergence of activity on a single category concept in the congruent condition? Two experiments show that neither the strength with which the context stimulus activates an incongruent category concept nor the semantic distance between the category concepts activated by target and distractor affect target categorization speed. We conclude that the message congruency effect is most likely due to convergence on a single category concept in the category-congruent condition.
Orienting Numbers in Mental Space: Horizontal Organization Trumps Vertical
Authors: Holmes Kevin J.
Published: May 2012

While research on the spatial representation of number has provided substantial evidence for a horizontally oriented mental number line, recent studies suggest vertical organization as well. Directly comparing the relative strength of horizontal and vertical organization, however, we found no evidence of spontaneous vertical orientation (upward or downward), and horizontal trumped vertical when pitted against each other (Experiment 1). Only when numbers were conceptualized as magnitudes (as opposed to nonmagnitude ordinal sequences) did reliable vertical organization emerge, with upward orientation preferred (Experiment 2). Altogether, these findings suggest that horizontal representations predominate, and that vertical representations, when elicited, may be relatively inflexible. Implications for spatial organization beyond number, and its ontogenetic basis, are discussed.
When and for whom do frequencies facilitate performance? On the role of numerical literacy
Authors: Hill W. Trey , Brase Gary L.
Published: May 2012

The thesis that the mind is better prepared to process frequencies—as compared to other numerical formats—continues to be debated. A recent aspect of this issue is the role of numeracy (numerical literacy; one's ability to understand and work with numerical information) and specifically the argument that individual differences in numeracy interact with numerical formats. This interaction, either that frequencies improve performance only for those of low numeracy or that frequencies work only for those of high numeracy, would suggest that better performance using frequencies could be due to (nonevolutionary) numeracy effects. The three present studies revisited prior work with cumulative probability, Bayesian reasoning, and scenario risk assessments to study the effects of numeracy on frequency facilitation. Results from these experiments consistently failed to replicate previous findings of interactions; however, a more consistent finding emerged of a straightforward frequency effect. The lack of interactions and observations of frequency main effects lend support to the evolutionary explanation of the frequency effect. In addition, some possible statistical processes are proposed to explain the observation of interactions in past studies.
Fluorescent silicon carbide as an ultraviolet-to-visible light converter by control of donor to acceptor recombinations
Authors: Sun J W , Kamiyama S , Jokubavicius V , Peyre H , Yakimova R , Juillaguet S , Syväjärvi M
Published: May 2012

As an alternative to the conventional phosphors in white LEDs, a donor and acceptor co-doped fluorescent 6H-SiC can be used as an ultraviolet-to-visible light converter without any need of rare-earth metals. From experimental data we provide an explanation to how light can be obtained at room temperature by a balance of the donors and acceptors. A steady-state recombination rate model is used to demonstrate that the luminescence in fluorescent SiC can be enhanced by controlling the donor and acceptor doping levels. A doping criterion for optimization of this luminescence is thus proposed.
Temperature and emissivity determination of liquid steel S235
Authors: Schöpp H , Sperl A , Kozakov R , Gött G , Uhrlandt D , Wilhelm G
Published: May 2012

Temperature determination of liquid metals is difficult but a necessary tool for improving materials and processes such as arc welding in the metal-working industry. A method to determine the surface temperature of the weld pool is described. A TIG welding process and absolute calibrated optical emission spectroscopy are used. This method is combined with high-speed photography. 2D temperature profiles are obtained. The emissivity of the radiating surface has an important influence on the temperature determination. A temperature dependent emissivity for liquid steel is given for the spectral region between 650 and 850 nm.
Fabrication of SiC nanopillars by inductively coupled SF6/O2 plasma etching
Authors: Choi J H , Latu-Romain L , Bano E , Dhalluin F , Chevolleau T , Baron T
Published: May 2012

In this paper, we demonstrate a top-down fabrication technique for nanometre scale silicon carbide (SiC) pillars using inductively coupled plasma etching. A set of experiments in SF6-based plasma was carried out in order to realize high aspect ratio SiC nanopillars. The etched SiC nanopillars using a small circular mask pattern (115 nm diameter) show high aspect ratio (7.4) with a height of 2.2 µm at an optimum bias voltage (300 V) and pressure (6 mTorr). Under the optimal etching conditions using a large circular mask pattern with 370 nm diameter, the obtained SiC nanopillars exhibit high anisotropy features (6.4) with a large etch depth (>7 µm). The etch characteristic of the SiC nanopillars under these conditions shows a high etch rate (550 nm min−1) and a high selectivity (over 60 for Ni). We also studied the etch profile of the SiC nanopillars and mask evolution over the etching time. As the mask pattern size shrinks in nanoscale, vertical and lateral mask erosion plays a crucial role in the etch profile of the SiC nanopillars. Long etching process makes the pillars appear with a hexagonal shape, coming from the crystallographic structure of α-SiC. It is found that the feature of pillars depends not only on the etching process parameters, but also on the crystallographic structure of the SiC phase.