bluuebunny/crossref_metadata_2025 huggingface dataset:
AP2 suppresses osteoblast differentiation and mineralization through down-regulation of Frizzled-1
Authors: Yu Shibing , Yerges-Armstrong Laura M. , Chu Yanxia , Zmuda Joseph M. , Zhang Yingze
Published: November 2014

Transcription factor activating protein 2 (AP2) plays an important role in cellular differentiation. Although profound craniofacial and long bone developmental abnormalities have been observed in AP2-knockout mice, the molecular effects of AP2 on osteoblasts are poorly defined. We demonstrated that AP2 regulates the expression of human Frizzled 1 (FZD1), a co-receptor for the Wnt signalling pathway, in human osteoblast cell lines and primary bone marrow stromal cells (BMSCs). We also identified a putative AP2-binding site in the FZD1 proximal promoter in silico and characterized this binding element further in Saos2 in vitro by ChIP, electrophoretic mobility shift and promoter reporter assays. The transcriptional repression of the FZD1 promoter by AP2 was confirmed in normal human fetal osteoblasts (hFOB). Furthermore, overexpression of AP2 resulted in a significant reduction in both differentiation and mineralization of Saos2 cells. Knockdown of FZD1 expression before AP2 up-regulation diminished the AP2-dependent inhibition of Saos2 cell differentiation and mineralization. Similarly, overexpressing FZD1 before AP2 treatment in both Saos2 and BMSCs diminished the inhibitory effect of AP2 on osteoblast differentiation and mineralization. Taken together, these results demonstrate that AP2 is a negative regulator of osteoblast differentiation and mineralization, and its inhibitory effect may be mediated in part through down-regulation of FZD1 expression.
Lentivirus-mediated knockdown of eukaryotic translation initiation factor 3 subunit D inhibits proliferation of HCT116 colon cancer cells
Authors: Yu Xiaojun , Zheng Bo’an , Chai Rui
Published: November 2014

Dysregulation of protein synthesis is emerging as a major contributory factor in cancer development. eIF3D (eukaryotic translation initiation factor 3 subunit D) is one member of the eIF3 (eukaryotic translation initiation factor 3) family, which is essential for initiation of protein synthesis in eukaryotic cells. Acquaintance with eIF3D is little since it has been identified as a dispensable subunit of eIF3 complex. Recently, eIF3D was found to embed somatic mutations in human colorectal cancers, indicating its importance for tumour progression. To further probe into its action in colon cancer, we utilized lentivirus-mediated RNA interference to knock down eIF3D expression in one colon cancer cell line HCT116. Knockdown of eIF3D in HCT116 cells significantly inhibited cell proliferation and colony formation in vitro. Flow cytometry analysis indicated that depletion of eIF3D led to cell-cycle arrest in the G2/M phase, and induced an excess accumulation of HCT116 cells in the sub-G1 phase representing apoptotic cells. Signalling pathways responsible for cell growth and apoptosis have also been found altered after eIF3D silencing, such as AMPKα (AMP-activated protein kinase alpha), Bad, PRAS40 [proline-rich Akt (PKB) substrate of 40 kDa], SAPK (stress-activated protein kinase)/JNK (c-Jun N-terminal kinase), GSK3β and PARP [poly(ADP-ribose) polymerase]. Taken together, these findings suggest that eIF3D might play an important role in colon cancer progression.
siRNA-mediated knockdown against NUF2 suppresses pancreatic cancer proliferation in vitro and in vivo
Authors: Hu Peng , Chen Xi , Sun Jing , Bie Ping , Zhang Lei-Da
Published: November 2014

NUF2 (NUF2, Ndc80 kinetochore complex component) plays an important role in kinetochore-microtubule attachment. It has been reported that NUF2 is associated with multiple human cancers. However, the functional role of NUF2 in pancreatic cancer remains unclear. In this study, we found that NUF2 expression was stronger in tumour tissues than in normal pancreatic tissues, and its overexpression could be related to poor prognosis. Moreover, NUF2 was highly expressed in several human pancreatic cancer cell lines. We took advantage of lentivirus-mediated siRNA (small interfering RNA) to suppress NUF2 expression in PANC-1 and Sw1990 cell lines aiming to investigate the role of NUF2 in pancreatic cancer. NUF2 silencing by RANi (RNA interference) reduced the proliferation and colony formation ability of pancreatic cancer cells in vitro. Cell cycle analysis showed that NUF2 knockdown induced cell cycle arrest at G0/G1 phase via suppression of Cyclin B1, Cdc2 and Cdc25A. More importantly, NUF2 silencing was able to alleviate in vivo tumourigenesis in pancreatic cancer xenograft nude mice. Collectively, the present study indicates that the siRNA-mediated knockdown against NUF2 may be a promising therapeutic method for the treatment of pancreatic cancer.
Pound the alarm: danger signals in rheumatic diseases
Authors: O’Reilly Steven
Published: November 2014

Damage-associated molecular patterns (DAMPs) are chemically heterogeneous endogenous host molecules rapidly released from damaged or dying cells that incite a sterile inflammatory response mediated via pattern recognition receptors (PRRs). The sources of DAMPs are dead or dying cells or the extracellular matrix and can signal through the PRRs, the Toll-like receptors or cytosolic Nod-like receptors, culminating in nuclear factor κB (NF-κB) activation and pro-inflammatory cytokine secretion. Together, these molecules are involved in sterile inflammation and many are associated with rheumatic autoimmune diseases such as rheumatoid arthritis, systemic lupus erythromatosus, psoriatic arthritis and systemic sclerosis. These diseases are associated with inflammation and many danger signals are found in sites of sterile inflammation and mediate inflammation. The present review examines the role of DAMPs in rheumatic conditions and suggests avenues for their therapeutic modulation.
Interval and continuous exercise regimens suppress neutrophil-derived microparticle formation and neutrophil-promoted thrombin generation under hypoxic stress
Authors: Chen Yi-Ching , Ho Ching-Wen , Tsai Hsing-Hua , Wang Jong-Shyan
Published: November 2014

Acute hypoxic exposure increases vascular thrombotic risk. The release of procoagulant-rich microparticles from neutrophils accelerates the pathogenesis of inflammatory thrombosis. The present study explicates the manner in which interval and continuous exercise regimens affect neutrophil-derived microparticle (NDMP) formation and neutrophil/NDMP-mediated thrombin generation (TG) under hypoxic condition. A total of 60 sedentary males were randomized to perform either aerobic interval training [AIT; 3-min intervals at 40% and 80% V̇O2max (maximal O2 consumption)] or moderate continuous training (MCT; sustained 60% V̇O2max) for 30 min/day, 5 days/week for 5 weeks, or to a control (CTL) group who did not receive any form of training. At rest and immediately after hypoxic exercise test (HE, 100 W under 12% O2 for 30 min), the NDMP characteristics and dynamic TG were measured by flow cytometry and thrombinography respectively. Before the intervention, HE (i) elevated coagulant factor VIII/fibrinogen concentrations and shortened activated partial thromboplastin time (aPTT), (ii) increased total and tissue factor (TF)-rich/phosphatidylserine (PS)-exposed NDMP counts and (iii) enhanced the peak height and rate of TG promoted by neutrophils/NDMPs. Following the 5-week intervention, AIT exhibited higher enhancement of V̇O2max than did MCT. Notably, both MCT and AIT attenuated the extents of HE-induced coagulant factor VIII/fibrinogen elevations and aPTT shortening. Furthermore, the two exercise regimens significantly decreased TF-rich/PS-exposed NDMP formation and depressed neutrophil/NDMP-mediated dynamic TG at rest and following HE. Hence, we conclude that AIT is superior to MCT for enhancing aerobic capacity. Moreover, either AIT or MCT effectively ameliorates neutrophil/NDMP-promoted TG by down-regulating expression of procoagulant factors during HE, which may reduce thrombotic risk evoked by hypoxia. Moreover, either AIT or MCT effectively ameliorates neutrophil/NDMP-promoted TG by down-regulating expression of procoagulant factors during HE, which may reduce thrombotic risk evoked by hypoxia.
Lowering the signal‐to‐noise ratio wall for energy detection using parameter‐induced stochastic resonator
Authors: Liu Jin , Li Zan
Published: November 2014

Energy detection is the most frequently used spectrum sensing technique, however, in uncertain low signal‐to‐noise ratio (SNR) conditions, it generally suffers from the ‘SNR wall’, that is, a minimum SNR below which it is impossible to reliably detect a signal. To address this issue, an improved energy detection (IED) algorithm based on non‐linear parameter‐induced stochastic resonator (PSR) is proposed in this study. By adopting the method which combines classic adiabatic approximation stochastic resonance (SR) theory and non‐classic parameter‐induced SR theory, an analytical expression of SR system parameters is derived. On this basis, a PSR is proposed which is mathematically testified to have the ability to improve the SNR of the received signal. Further, an IED algorithm is proposed by introducing the PSR as the preprocessor of energy detection. Theoretical analyses and simulation results prove that a significantly detection performance and SNR wall improvement can be achieved using the proposed IED algorithm.
Novel grid voltage estimation by means of the Newton–Raphson optimisation for three‐phase grid connected voltage source converters
Authors: Gholami‐Khesht Hosein , Monfared Mohammad
Published: November 2014

This study presents a proportional resonant current control scheme for three‐phase grid connected voltage source converters without any grid voltage sensors. Towards this goal, the grid voltage sensors are replaced by a voltage estimation scheme based on the Newton–Raphson algorithm. In the proposed method, the grid connected converter behaviour is converted to an optimisation problem which relates the instantaneous grid voltage value to the filter parameters, the generated converter voltage and the exchanged powers in each sampling period. The proposed optimisation problem is then solved in each sampling period by means of the Newton–Raphson optimisation technique. Afterwards, the reference current for the current control loop is generated from the estimated grid voltages. Using an estimator instead of the voltage sensors not only reduces the size and cost of the converter system but also improves its reliability and protects it from grid voltage disturbances and noises. The excellent performance of the proposed grid voltage sensorless scheme is confirmed through experimental and simulation results.
Improved Luo converter modifications with increasing voltage ratio
Authors: Berkovich Yefim , Axelrod Boris , Madar Rotem , Twina Avraham
Published: November 2014

The study provides improved modifications of the positive output super‐lift Luo converter that allows significantly increase the voltage transfer gain by the modest means. In the simplest case this increase is provided by replacing the inductor by the switched‐inductor structure consisting of two inductors and three diodes. This allows getting practically double increase in the line‐to‐output voltage ratio at the high values of duty cycle. Analysis of steady‐state and transient conditions shows that the zeros of the transfer function for the converter, as well as for the conventional boost converter, are positive. The study indicates possible ways to further increase the output voltage ratio without additional switches – by the use of magnetically coupled inductors and diode‐capacitor voltage multipliers. Simulation and experimental results confirm the theoretical analysis and the advantages of the proposed converters.
Development of a control strategy for interconnection of islanded direct current microgrids
Authors: Kumar Mahesh , Srivastava Suresh Chandra , Singh Sri Niwas , Ramamoorty Mylavarapu
Published: November 2014

This study presents a control strategy for interconnection of a cluster of direct current (DC) microgrids operating at different grid voltages in islanded mode. In this study, two neighbouring DC microgrids (DCMGs) are interconnected through a bidirectional DC–DC converter (BDC) and DC cable. The BDC has been placed near to the low‐voltage DCMG. The DCMGs consist of wind turbines, solar‐photovoltaic systems, solid oxide fuel cell, micro‐turbine generators, battery energy storage systems and varying DC and three‐phase as well as single‐phase alternating current loads. The proposed control strategy of the BDC is aimed at managing the bidirectional flow of power between the DCMGs to balance the power under various operating scenarios and fault conditions, while maintaining constant DC voltages of both the DCMGs. Simulations are carried out to verify the robustness of the proposed control strategy under different operating conditions including fault scenario.
On the axial vibration of carbon nanotubes with different boundary conditions
Authors: Yayli Mustafa Özgür
Published: November 2014

In this reported work, the free axial vibration response of carbon nanotubes (CNTs) with arbitrary boundary conditions is studied based on the non‐local elasticity theory. Using Fourier sine series together with Stokes’transformation, the general frequency determinant of CNTs is obtained. The main advantage of this method is its capability of dealing with rigid or restrained boundary conditions. Comparisons between the results of the presented method and previous works in the literature have been performed. Good agreement is obtained when enough terms are included in the Fourier series expansion. The effects of spring parameters on the vibration frequencies are discussed in detail. The proposed analytical method can be utilised for dynamic analyses of nanorods (CNTs) with arbitrary boundary conditions.
The behaviour of basic autocatalytic signalling modules in isolation and embedded in networks
Authors: Krishnan J. , Mois Kristina , Suwanmajo Thapanar
Published: November 2014

In this paper, we examine the behaviour of basic autocatalytic feedback modules involving a species catalyzing its own production, either directly or indirectly. We first perform a systematic study of the autocatalytic feedback module in isolation, examining the effect of different factors, showing how this module is capable of exhibiting monostable threshold and bistable switch-like behaviour. We then study the behaviour of this module embedded in different kinds of basic networks including (essentially) irreversible cycles, open and closed reversible chains, and networks with additional feedback. We study the behaviour of the networks deterministically and also stochastically, using simulations, analytical work, and bifurcation analysis. We find that (i) there are significant differences between the behaviour of this module in isolation and in a network: thresholds may be altered or destroyed and bistability may be destroyed or even induced, even when the ambient network is simple. The global characteristics and topology of this network and the position of the module in the ambient network can play important and unexpected roles. (ii) There can be important differences between the deterministic and stochastic dynamics of the module embedded in networks, which may be accentuated by the ambient network. This provides new insights into the functioning of such enzymatic modules individually and as part of networks, with relevance to other enzymatic signalling modules as well.
A coarse-graining approach for molecular simulation that retains the dynamics of the all-atom reference system by implementing hydrodynamic interactions
Authors: Markutsya Sergiy , Lamm Monica H.
Published: November 2014

We report on a new approach for deriving coarse-grained intermolecular forces that retains the frictional contribution that is often discarded by conventional coarse-graining methods. The approach is tested for water and an aqueous glucose solution, and the results from the new implementation for coarse-grained molecular dynamics simulation show remarkable agreement with the dynamics obtained from reference all-atom simulations. The agreement between the structural properties observed in the coarse-grained and all-atom simulations is also preserved. We discuss how this approach may be applied broadly to any existing coarse-graining method where the coarse-grained models are rigorously derived from all-atom reference systems.
Multi-indexed Jacobi polynomials and Maya diagrams
Authors: Takemura Kouichi
Published: November 2014

Multi-indexed Jacobi polynomials are defined by the Wronskian of four types of eigenfunctions of the Pöschl-Teller Hamiltonian. We give a correspondence between multi-indexed Jacobi polynomials and pairs of Maya diagrams, and we show that any multi-indexed Jacobi polynomial is essentially equal to some multi-indexed Jacobi polynomial of two types of eigenfunction. As an application, we show a Wronskian-type formula of some special eigenstates of the deformed Pöschl-Teller Hamiltonian.
Structural behavior and dynamics of an anomalous fluid between attractive and repulsive walls: Templating, molding, and superdiffusion
Authors: Leoni Fabio , Franzese Giancarlo
Published: November 2014

Confinement can modify the dynamics, the thermodynamics, and the structural properties of liquid water, the prototypical anomalous liquid. By considering a generic model for anomalous liquids, suitable for describing solutions of globular proteins, colloids, or liquid metals, we study by molecular dynamics simulations the effect that an attractive wall with structure and a repulsive wall without structure have on the phases, the crystal nucleation, and the dynamics of the fluid. We find that at low temperatures the large density of the attractive wall induces a high-density, high-energy structure in the first layer (“templating” effect). In turn, the first layer induces a “molding” effect on the second layer determining a structure with reduced energy and density, closer to the average density of the system. This low-density, low-energy structure propagates further through the layers by templating effect and can involve all the existing layers at the lowest temperatures investigated. Therefore, although the high-density, high-energy structure does not self-reproduce further than the first layer, the structured wall can have a long-range influence thanks to a sequence of templating, molding, and templating effects through the layers. We find that the walls also have an influence on the dynamics of the liquid, with a stronger effect near the attractive wall. In particular, we observe that the dynamics is largely heterogeneous (i) among the layers, as a consequence of the sequence of structures caused by the walls presence, and (ii) within the same layer, due to superdiffusive liquid veins within a frozen matrix of particles near the walls at low temperature and high density. Hence, the partial freezing of the first layer does not correspond necessarily to an effective reduction of the channel's section in terms of transport properties, as suggested by other authors.
Dynamic mesoscale model of dipolar fluids via fluctuating hydrodynamics
Authors: Persson Rasmus A. X. , Voulgarakis Nikolaos K. , Chu Jhih-Wei
Published: November 2014

Fluctuating hydrodynamics (FHD) is a general framework of mesoscopic modeling and simulation based on conservational laws and constitutive equations of linear and nonlinear responses. However, explicit representation of electrical forces in FHD has yet to appear. In this work, we devised an Ansatz for the dynamics of dipole moment densities that is linked with the Poisson equation of the electrical potential ϕ in coupling to the other equations of FHD. The resulting ϕ-FHD equations then serve as a platform for integrating the essential forces, including electrostatics in addition to hydrodynamics, pressure-volume equation of state, surface tension, and solvent-particle interactions that govern the emergent behaviors of molecular systems at an intermediate scale. This unique merit of ϕ-FHD is illustrated by showing that the water dielectric function and ion hydration free energies in homogeneous and heterogenous systems can be captured accurately via the mesoscopic simulation. Furthermore, we show that the field variables of ϕ-FHD can be mapped from the trajectory of an all-atom molecular dynamics simulation such that model development and parametrization can be based on the information obtained at a finer-grained scale. With the aforementioned multiscale capabilities and a spatial resolution as high as 5 Å, the ϕ-FHD equations represent a useful semi-explicit solvent model for the modeling and simulation of complex systems, such as biomolecular machines and nanofluidics.
Design and implementation of a new autonomous sensor fish to support advanced hydropower development
Authors: Deng Z. D. , Lu J. , Myjak M. J. , Martinez J. J. , Tian C. , Morris S. J. , Carlson T. J. , Zhou D. , Hou H.
Published: November 2014

Acceleration in development of additional conventional hydropower requires tools and methods to perform laboratory and in-field validation of turbine performance and fish passage claims. The new-generation Sensor Fish has been developed with more capabilities to accommodate a wider range of users over a broader range of turbine designs and operating environments. It provides in situ measurements of three-dimensional (3D) linear accelerations, 3D rotational velocities, 3D orientation, pressure, and temperature at a sampling frequency of 2048 Hz. It also has an automatic floatation system and built-in radio-frequency transmitter for recovery. The relative errors of the pressure, acceleration, and rotational velocity were within ±2%, ±5%, and ±5%, respectively. The accuracy of orientation was within ±4° and accuracy of temperature was ±2 °C. The new-generation Sensor Fish is becoming a major technology and being deployed for evaluating the conditions for fish passage of turbines or other hydraulic structures in both the United States and several other countries.
Algorithm for the calculation of the translator position in permanent magnet linear generators
Authors: Castellucci Valeria , Abrahamsson Johan , Svensson Olle , Waters Rafael
Published: November 2014

A permanent magnet linear generator for direct drive wave energy converters is a suitable power take-off system for ocean wave energy extraction, especially when coupled with a point absorbing buoy via a connection line. The performance of the linear generator is affected by the excursion of the translator along the stator. The optimal stroke is achieved when the midpoint of the oscillations coincides with the center of the stator. However, sea level changes due to, e.g., tides will shift these oscillations. This paper proposes a model able to detect the position of the translator from the generator output voltage. The algorithm will be integrated in the control system of a mechanical device that adjusts the length of the connection line in order to center the average position of the translator with the center of the stator. Thereby, the output power from the wave energy converter increases, and the mechanical stresses on the hull of the generator decrease. The results obtained by the model show good agreement with the experimental results from two linear generators, L2 and L3, deployed in the Lysekil wave energy research site, Sweden. The theoretical results differ from the experimental results by −4 mm for L2 and 21 mm for L3 with a standard deviation of 27 mm and 31 mm, respectively.
Comment on “General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation” [Phys. Fluids 26, 065105 (2014)]
Authors: Hietala Niklas , Hänninen Risto
Published: November 2014

Van Gorder considers a formulation of the local induction approximation, which allows the vortex to move in the direction of the reference axis [“General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation,” Phys. Fluids 26, 065105 (2014)]. However, in his analytical and numerical study he does not use it. A mistake in the torsion of a helical vortex is also corrected.
Response to “Comment on ‘General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation’” [Phys. Fluids 26, 119101 (2014)]
Authors: Van Gorder Robert A.
Published: November 2014

In R. A. Van Gorder, “General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation,” Phys. Fluids 26, 065105 (2014) I discussed properties of generalized vortex filaments exhibiting purely rotational motion under the low-temperature Svistunov model of the local induction approximation. Such solutions are stationary in terms of translational motion. In the Comment [N. Hietala, “Comment on ‘General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation’ [Phys. Fluids 26, 065105 (2014)],” Phys. Fluids 26, 119101 (2014)], the author criticizes my paper for not including translational motion (although it was clearly stated that the filament motion was assumed rotational). As it turns out, if one is interested in studying the geometric structure of solutions (which was the point of my paper), one obtains the needed qualitative results on the structure of such solutions by studying the purely rotational case. Nevertheless, in this Response I shall discuss the vortex filaments that have both rotational and translational motions. I then briefly discuss why one might want to study such generalized rotating filament solutions, in contrast to simple the standard helical or planar examples (which are really special cases). I also discuss how one can study the time evolution of filaments which exhibit more complicated dynamics than pure translation and rotation. Doing this, one can study non-stationary solutions which initially appear purely rotational and gradually display other dynamics as the filaments evolve.
Stability of a film flowing down an inclined corrugated plate: The direct Navier-Stokes computations and Floquet theory
Authors: Trifonov Yuri
Published: November 2014

The paper is devoted to a theoretical analysis of the linear stability of the viscous liquid film flowing down an inclined wavy surface. The study is based on the Navier-Stokes equations in their full statement. The developed numerical algorithm allows us to compute both the steady state solution of the nonlinear equations and the rates of growing or damping in time of the arbitrary two-dimensional disturbances of the solution which are bounded in space. The wall corrugations have a great influence on the disturbances behaviour. There is a critical Reynolds number Recr when the steady-state viscous flow over an undulated surface becomes unstable. It is found that the value of Recr depends essentially both on the topography parameters and the liquid's physical properties. In the case of the flat plate, the critical Reynolds number depends only on the value of the inclination angle. For different values of the Kapitza number, the inclination angle, and the Reynolds number we obtained the regions of the corrugation's parameters (amplitude and period) where all two-dimensional disturbances decay in time.
Miscible gravitational instability of initially stable horizontal interface in a porous medium: Non-monotonic density profiles
Authors: Kim Min Chan
Published: November 2014

To simulate a CO2 sequestration process, some researchers employed a water/propylene glycol (PPG) system which shows a non-monotonic density profile. Motivated by this fact, the stability of the diffusion layer of two miscible fluids saturated in a porous medium is analyzed. For a non-monotonic density profile system, linear stability equations are derived in a global domain, and then transformed into a system of ordinary differential equations in an infinite domain. Initial growth rate analysis is conducted without the quasi-steady state approximation (QSSA) and shows that initially the system is unconditionally stable for the least stable disturbance. For the time evolving case, the ordinary differential equations are solved applying the eigen-analysis and numerical shooting scheme with and without the QSSA. To support these theoretical results, direct numerical simulations are conducted using the Fourier spectral method. The results of theoretical linear stability analyses and numerical simulations validate one another. The present linear and nonlinear analyses show that the water/PPG system is more unstable than the CO2/brine one, and the flow characteristics of these two systems are quite different from each other.
Exciton dynamics in WSe2 bilayers
Authors: Wang G. , Marie X. , Bouet L. , Vidal M. , Balocchi A. , Amand T. , Lagarde D. , Urbaszek B.
Published: November 2014

We investigate exciton dynamics in WSe2 bilayers in time-resolved photoluminescence (PL) spectroscopy. Fast PL emission times are recorded for both the direct exciton with τD ≲ 3 ps and the indirect optical transition with τI ≈ 25 ps. For temperatures between 4 to 150 K τI remains constant. Following polarized laser excitation, we observe for the direct exciton transition at the K point of the Brillouin zone efficient optical orientation and alignment during the short emission time τD. The evolution of the direct exciton polarization and intensity as a function of excitation laser energy is monitored in PL excitation experiments.
Theoretical interpretation of the electron mobility behavior in InAs nanowires
Authors: Marin E. G. , Ruiz F. G. , Godoy A. , Tienda-Luna I. M. , Martínez-Blanque C. , Gámiz F.
Published: November 2014

This work studies the electron mobility in InAs nanowires (NWs), by solving the Boltzmann Transport Equation under the Momentum Relaxation Time approximation. The numerical solver takes into account the contribution of the main scattering mechanisms present in III-V compound semiconductors. It is validated against experimental field effect-mobility results, showing a very good agreement. The mobility dependence on the nanowire diameter and carrier density is analyzed. It is found that surface roughness and polar optical phonons are the scattering mechanisms that mainly limit the mobility behavior. Finally, we explain the origin of the oscillations observed in the mobility of small NWs at high electric fields.
Homeotropic alignment and Förster resonance energy transfer: The way to a brighter luminescent solar concentrator
Authors: Tummeltshammer Clemens , Taylor Alaric , Kenyon Anthony J. , Papakonstantinou Ioannis
Published: November 2014

We investigate homeotropically aligned fluorophores and Förster resonance energy transfer (FRET) for luminescent solar concentrators using Monte-Carlo ray tracing. The homeotropic alignment strongly improves the trapping efficiency, while FRET circumvents the low absorption at homeotropic alignment by separating the absorption and emission processes. We predict that this design doped with two organic dye molecules can yield a 82.9% optical efficiency improvement compared to a single, arbitrarily oriented dye molecule. We also show that quantum dots are prime candidates for absorption/donor fluorophores due to their wide absorption band. The potentially strong re-absorption and low quantum yield of quantum dots is not a hindrance for this design.
Composition-optimized TiO2/CdSxSe1-x core/shell nanowire arrays for photoelectrochemical hydrogen generation
Authors: Ai Guanjie , Mo Rong , Xu Hang , Chen Qian , Yang Sui , Li Hongxing , Zhong Jianxin
Published: November 2014

Core/shell heterostructured TiO2/CdSxSe1-x nanowire arrays (NWAs) were prepared via physical vapor deposition of CdSxSe1-x layer onto the hydrothermal pre-grown TiO2 NWAs with FTO as conductive substrate. By change the sulfur content (x) in the TiO2/CdSxSe1-x nano-composites, it was observed that the light absorption edge can be gradually tuned within a broad wavelength from 540 to 710 nm. When used as photoanodes for hydrogen generation, the as-prepared TiO2/CdSxSe1-x NWAs show much higher photoelectroncatalytic activity than the pristine TiO2 NWAs. Moreover, the TiO2/CdSxSe1-x photoelectrode with x = 0.52 exhibited the highest photocurrent level and outstanding stability, which is more suitable for long-time hydrogen generation. This study may be useful in the design of alloy hetrostructure photoelectrodes with optimal chemical composition toward the more efficient solar conversion devices.
Analysis of the nonlinear behavior of shear-Alfvén modes in tokamaks based on Hamiltonian mapping techniques
Authors: Briguglio S. , Wang X. , Zonca F. , Vlad G. , Fogaccia G. , Di Troia C. , Fusco V.
Published: November 2014

We present a series of numerical simulation experiments set up to illustrate the fundamental physics processes underlying the nonlinear dynamics of Alfvénic modes resonantly excited by energetic particles in tokamak plasmas and of the ensuing energetic particle transports. These phenomena are investigated by following the evolution of a test particle population in the electromagnetic fields computed in self-consistent MHD-particle simulation performed by the HMGC code. Hamiltonian mapping techniques are used to extract and illustrate several features of wave-particle dynamics. The universal structure of resonant particle phase space near an isolated resonance is recovered and analyzed, showing that bounded orbits and untrapped trajectories, divided by the instantaneous separatrix, form phase space zonal structures, whose characteristic non-adiabatic evolution time is the same as the nonlinear time of the underlying fluctuations. Bounded orbits correspond to a net outward resonant particle flux, which produces a flattening and/or gradient inversion of the fast ion density profile around the peak of the linear wave-particle resonance. The connection of this phenomenon to the mode saturation is analyzed with reference to two different cases: a Toroidal Alfvén eigenmode in a low shear magnetic equilibrium and a weakly unstable energetic particle mode for stronger magnetic shear. It is shown that, in the former case, saturation is reached because of radial decoupling (resonant particle redistribution matching the mode radial width) and is characterized by a weak dependence of the mode amplitude on the growth rate. In the latter case, saturation is due to resonance detuning (resonant particle redistribution matching the resonance width) with a stronger dependence of the mode amplitude on the growth rate.
An X-band overmoded relativistic klystron
Authors: Xiao Renzhen , Chen Changhua , Deng Yuqun , Li Jiawei , Bai Xianchen
Published: November 2014

An X-band overmoded relativistic klystron is proposed, the operation mode of which is the TM02 mode. The drift tube could not cut off the TM01 mode; isolating the buncher cavity from the input cavity is achieved by introducing a sectional RF lossy material. Microwaves are extracted from the modulated electron beam using a cylindrical waveguide, rather than a coaxial waveguide; thereby, the output structure is significantly simplified. Particle-in-cell simulations show that microwaves with power of 1.28 GW and frequency of 9.30 GHz can be obtained, corresponding to an efficiency of 32% and relative bandwidth of about 8%.
A semi-analytical solver for the Grad-Shafranov equation
Authors: Ciro D. , Caldas I. L.
Published: November 2014

In toroidally confined plasmas, the Grad-Shafranov equation, in general, a non-linear partial differential equation, describes the hydromagnetic equilibrium of the system. This equation becomes linear when the kinetic pressure is proportional to the poloidal magnetic flux and the squared poloidal current is a quadratic function of it. In this work, the eigenvalue of the associated homogeneous equation is related with the safety factor on the magnetic axis, the plasma beta, and the Shafranov shift; then, the adjustable parameters of the particular solution are bounded through physical constrains. The poloidal magnetic flux becomes a linear superposition of independent solutions and its parameters are adjusted with a non-linear fitting algorithm. This method is used to find hydromagnetic equilibria with normal and reversed magnetic shear and defined values of the elongation, triangularity, aspect-ratio, and X-point(s). The resultant toroidal and poloidal beta, the safety factor at the 95% flux surface, and the plasma current are in agreement with usual experimental values for high beta discharges and the model can be used locally to describe reversed magnetic shear equilibria.
Realizing in-plane surface diffraction by x-ray multiple-beam diffraction with large incidence angle
Authors: Huang Xian-Rong , Peng Ru-Wen , Gog Thomas , Siddons D. P. , Assoufid Lahsen
Published: November 2014

Based on rigorous dynamical-theory calculations, we demonstrate the principle of an x-ray multiple-beam diffraction (MBD) scheme that overcomes the long-lasting difficulties of high-resolution in-plane diffraction from crystal surfaces. This scheme only utilizes symmetric reflection geometry with large incident angles but activates the out-of-plane and in-plane diffraction processes simultaneously and separately in the continuous MBD planes. The in-plane diffraction is realized by detoured MBD, where the intermediate diffracted waves propagate parallel to the surface, which corresponds to an absolute Bragg surface diffraction configuration that is extremely sensitive to surface structures. A series of MBD diffraction and imaging techniques may be developed from this principle to study surface/interface (misfit) strains, lateral nanostructures, and phase transitions of a wide range of (pseudo)cubic crystal structures, including ultrathin epitaxial films and multilayers, quantum dots, strain-engineered semiconductor or (multi)ferroic materials, etc.
Important role of the non-uniform Fe distribution for the ferromagnetism in group-IV-based ferromagnetic semiconductor GeFe
Authors: Wakabayashi Yuki K. , Ohya Shinobu , Ban Yoshisuke , Tanaka Masaaki
Published: November 2014

We investigate the growth-temperature dependence of the properties of the group-IV-based ferromagnetic semiconductor Ge1−xFex films (x = 6.5% and 10.5%), and reveal the correlation of the magnetic properties with the lattice constant, Curie temperature (TC), non-uniformity of Fe atoms, stacking-fault defects, and Fe-atom locations. While TC strongly depends on the growth temperature, we find a universal relationship between TC and the lattice constant, which does not depend on the Fe content x. By using the spatially resolved transmission-electron diffractions combined with the energy-dispersive X-ray spectroscopy, we find that the density of the stacking-fault defects and the non-uniformity of the Fe concentration are correlated with TC. Meanwhile, by using the channeling Rutherford backscattering and particle-induced X-ray emission measurements, we clarify that about 15% of the Fe atoms exist on the tetrahedral interstitial sites in the Ge0.935Fe0.065 lattice and that the substitutional Fe concentration is not correlated with TC. Considering these results, we conclude that the non-uniformity of the Fe concentration plays an important role in determining the ferromagnetic properties of GeFe.
Effect of Si substrate on interfacial SiO2 scavenging in HfO2/SiO2/Si stacks
Authors: Li Xiuyan , Yajima Takeaki , Nishimura Tomonori , Nagashio Kosuke , Toriumi Akira
Published: November 2014

The scavenging kinetics of an ultra-thin SiO2 interface layer (SiO2-IL) in an HfO2/SiO2/Si stack is discussed by focusing on the substrate effect in addition to oxygen diffusion. 18O tracing experiments demonstrate that the O-atom moves from the SiO2-IL to the HfO2 layer during scavenging. SiO2-IL scavenging with various substrates (Si, SiC, and sapphire) has been found to be significantly different, which suggests that the Si in the substrate is also necessary to continuously cause the scavenging. Based on these findings and thermodynamic considerations, a kinetic model where oxygen vacancy (VO) transferred from the HfO2 reacts with the SiO2, which is in contact with the Si-substrate, is proposed for the SiO2-IL scavenging.
III-nitride quantum cascade detector grown by metal organic chemical vapor deposition
Authors: Song Yu , Bhat Rajaram , Huang Tzu-Yung , Badami Pranav , Zah Chung-En , Gmachl Claire
Published: November 2014

Quantum cascade (QC) detectors in the GaN/AlxGa1−xN material system grown by metal organic chemical vapor deposition are designed, fabricated, and characterized. Only two material compositions, i.e., GaN as wells and Al0.5Ga0.5N as barriers are used in the active layers. The QC detectors operates around 4 μm, with a peak responsivity of up to ∼100 μA/W and a detectivity of up to 108 Jones at the background limited infrared performance temperature around 140 K.
Profiling the allied health staffing of Queensland Health inpatient general rehabilitation units
Authors: Barrett Catherine , Stephens Catherine , Hulcombe Julie , McEvoy Brian
Published: November 2014

Objective
The purpose of this paper was to profile staffing levels for allied health (AH) professional and support staff in Queensland Health inpatient general rehabilitation services (at a given point-in-time) and compare them against established profession-specific standards and guidelines in order to provide a reference for future workforce planning for these services.

Methods
A statewide analysis of AH staffing in Queensland Health inpatient general rehabilitation services was undertaken during June–August 2011. Reported full-time equivalent positions (FTE) were compared to several established national and international benchmarks. Patient activity data was used to calculate the average length of stay (ALOS) and Functional Independence Measure (FIM) scores on admission.

Results
Sixteen facilities reported 202 FTE for a total of 466 general rehabilitation beds, with a resultant average workforce ratio of 0.43 FTE/bed. While several professional groups within specific services met established benchmarks, the majority failed to reach recommended staffing ratios. More than half the workforce (53%) was entry-level or consolidating clinicians. The FTE/bed ratios were compared against both patient ALOS and FIM scores on admission and showed a poor correlation.

Conclusion
Across all included services statewide, there was significant variance in AH staffing levels and diversity in skill mix for inpatient general rehabilitation services.

What is known about the topic?
The AH workforce faces several challenges to delivering effective, efficient and responsive services including balancing the high and escalating demand for services with managing staff costs. While several different workload capacity measures have been used successfully for medical and nursing professions, there is currently little published evidence about effective workforce allocation for AH professionals (AHPs) in rehabilitation settings.

What does this paper add?
This paper describes AH staffing levels in Queensland Health inpatient general rehabilitation services. It includes the outcome of analysis of data collected from AHPs and allied health assistants (AHAs) and comparison with established benchmarks.

What are the implications for practitioners?
The workforce ratios identified can assist with future workforce planning when introducing new services and reviewing service delivery models. They should be considered in conjunction with other relevant standards and planning tools, and it is recommended that further work be undertaken to investigate links between staffing levels and patient outcomes, as many of the current benchmarks rely heavily on professional opinion.
Use of remote sensing to determine the relationship of early vigour to grain yield in canola (Brassica napus L.) germplasm
Authors: Cowley R. B. , Luckett D. J. , Moroni J. S. , Diffey S.
Published: November 2014

Early crop vigour in canola, as in other crops, is likely to result in greater competition with weeds, more rapid canopy closure, improved nutrient acquisition, improved water-use efficiency, and, potentially, greater final grain yield. Laborious measurements of crop biomass over time can be replaced with newer remote-sensing technology to aid data acquisition. Normalised difference vegetation index (NDVI) is a surrogate for biomass accumulation that can be recorded rapidly and repeatedly with inexpensive equipment. In seven small-plot field experiments conducted over a 4-year period with diverse canola germplasm (n = 105), we have shown that NDVI measures are well correlated with final grain yield. We found NDVI values were most correlated with yield (r >0.7) if readings were taken when the crop had received 210–320 growing degree-days (usually the mid-vegetative phase of growth). It is suggested that canola breeders may use NDVI to objectively select for vigorous genotypes that are more likely to have higher grain yields.
Organic carbon reservoirs in five small rivers across a land-use gradient
Authors: Vyšná V. , Dyer F. , Maher W. , Norris R.
Published: November 2014

Organic carbon (OC) inputs, stores and processing underpin river functioning. We examined patterns in OC reservoirs (total organic carbon, TOC), suspended OC, drifting coarse particulate OC (drift OC), organic debris and the biomass of in-stream primary producers in five geographically proximate small rivers in south-eastern Australia during base-flow conditions. Despite differences in the extent of land-use conversion (native forest-to-pasture) and geomorphology among all sites, we found greater within-river than ‘within-land-use’ similarities in OC reservoirs. Our predictions regarding the relationships between distant v. proximate land-use and the OC reservoirs were mostly not confirmed. Riparian canopy cover was correlated with the mass of organic debris but not with other OC reservoirs. Our predictions regarding longitudinal patterns in rivers were also not confirmed. Rivers draining catchments with conservation land-use only did not show consistent patterns that were different from rivers draining a combination of conservation and grazing land. Variability in the extent of land converted to other uses was not necessarily associated with greater longitudinal variability in OC reservoirs. Our results suggest: (1) strong within-catchment controls of TOC concentration that are maintained despite a certain level of catchment impairment and (2) between-river differences in TOC at a local scale as great as continental scale differences.
Assessing the effects of groundwater extraction on coastal groundwater-dependent ecosystems using satellite imagery
Authors: Adams Matthew , Smith Peter L. , Yang Xihua
Published: November 2014

Terrestrial vegetation that depends on the subsurface presence of water can be severely affected by groundwater extraction. We analysed Landsat imagery to assess the ecological risk posed by groundwater pumping to native vegetation on the Tomago Sandbeds, a coastal sand mass in northern New South Wales. The effect of extraction on each major vegetation community was assessed by comparing rates of evapotranspiration between extraction zones and matched areas outside the influence of extraction. We found a significant long-term change in evapotranspiration close to groundwater extraction points within most forest, woodland and scrub communities, including those not currently regarded as being wholly dependent on groundwater. We therefore suggest that management of groundwater-dependent ecosystems should not be based on degree of dependence but instead on their sensitivity to groundwater management regimes. Our approach can provide policy makers with information needed to evaluate and adjust groundwater management within groundwater-dependent ecosystems.