bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuroprotective Signaling Pathways are Modulated by Adenosine in the Anoxia Tolerant Turtle
Authors: Nayak Gauri H , Prentice Howard M , Milton Sarah L
Published: July 2010

Cumulative evidence shows a protective role for adenosine A1 receptors (A1R) in hypoxia/ischemia; A1R stimulation reduces neuronal damage, whereas blockade exacerbates damage. The signal transduction pathways may involve the mitogen-activated protein kinase (MAPK) pathways and serine/threonine kinase (AKT), with cell survival depending on the timing and degree of upregulation of these cascades as well as the balance between pro-survival and pro-death pathways. Here, we show in vitro that extracellular signal-regulated kinase (ERK1/2) and phosphatidylinositol 3-kinase (PI3-K/AKT) activation is dependent on A1R stimulation, with further downstream effects that promote neuronal survival. Phosphorylated ERK1/2 (p-ERK) and AKT (p-AKT) as well as Bcl-2 are upregulated in anoxic neuronally enriched primary cultures from turtle brain. This native upregulation is further increased by the selective A1R agonist 2-chloro- N-cyclopentyladenosine (CCPA), whereas the selective antagonist 8-cyclopentyl-1,3-dihydropylxanthine (DPCPX) decreases p-ERK and p-AKT expression. Conversely, A1R antagonism resulted in increases in phosphorylated JNK (p-JNK), p38 (p-p38), and Bax. As pathological and adaptive changes occur simultaneously during anoxia/ischemia in mammalian neurons, the turtle provides an alternative model to analyze protective mechanisms in the absence of evident pathologies.
Factors Affecting the Apparent Efficacy and Safety of Tissue Plasminogen Activator in Thrombotic Occlusion Models of Stroke: Systematic Review and Meta-Analysis
Authors: Sena Emily S , Briscoe Catherine L , Howells David W , Donnan Geoffrey A , Sandercock Peter AG , Macleod Malcolm R
Published: July 2010

Thrombolysis with recombinant tissue plasminogen activator (rtPA) improves outcome in animal models of stroke and in clinical trial, but is associated with increased intracranial hemorrhage. Here, we explore the impact of biologic and experimental design factors on efficacy and bleeding. We conducted a systematic review of studies describing the effect of tPA in thrombotic occlusion models of ischemic stroke followed by random effects meta-analysis, meta-regression, and trim and fill. We identified 202, 66, 128, and 54 comparisons reporting infarct volume, neurobehavioral score, hemorrhage, and mortality, respectively. The rtPA reduced infarct volume by 25.2% (95% confidence interval=21.8 to 28.6, 3388 animals), improved neurobehavioral score by 18.0% (12.6% to 23.3%, n=1243), increased the risk of hemorrhage (odds ratio=1.71, 1.42 to 2.07, n=2833) and had no significant effect on mortality (odds ratio=0.82, 0.62 to 1.08, n=1274). There was an absolute reduction in efficacy of 1.1% (0.7% to 1.4%) for every 10 minutes delay to treatment. Cumulative meta-analysis showed that the estimate of efficacy fell as more data became available. Publication bias inflated efficacy by 5.1% (infarct volume) and 8.1% (neurobehavioral score). This data set was large enough to be adequately powered to estimate with precision the impact of biologic and experimental factors on the efficacy and safety of rtPA.
Reactive-site mutants of N-TIMP-3 that selectively inhibit ADAMTS-4 and ADAMTS-5: biological and structural implications
Authors: Lim Ngee H. , Kashiwagi Masahide , Visse Robert , Jones Jonathan , Enghild Jan J. , Brew Keith , Nagase Hideaki
Published: July 2010

We have reported previously that reactive-site mutants of N-TIMP-3 [N-terminal inhibitory domain of TIMP-3 (tissue inhibitor of metalloproteinases 3)] modified at the N-terminus, selectively inhibited ADAM17 (a disintegrin and metalloproteinase 17) over the MMPs (matrix metalloproteinases). The primary aggrecanases ADAMTS (ADAM with thrombospondin motifs) -4 and -5 are ADAM17-related metalloproteinases which are similarly inhibited by TIMP-3, but are poorly inhibited by other TIMPs. Using a newly developed recombinant protein substrate based on the IGD (interglobular domain) of aggrecan, gst-IGD-flag, these reactive-site mutants were found to similarly inhibit ADAMTS-4 and ADAMTS-5. Further mutations of N-TIMP-3 indicated that up to two extra alanine residues can be attached to the N-terminus before the Ki (app) for ADAMTS-4 and ADAMTS-5 increased to over 100 nM. No other residues tested at the [−1] position produced inhibitors as potent as the alanine mutant. The mutants N-TIMP-3(T2G), [−1A]N-TIMP-3 and [−2A]N-TIMP-3 were effective inhibitors of aggrecan degradation, but not of collagen degradation in both IL-1α (interleukin-1α)-stimulated porcine articular cartilage explants and IL-1α with oncostatin M-stimulated human cartilage explants. Molecular modelling studies indicated that the [−1A]N-TIMP-3 mutant has additional stabilizing interactions with the catalytic domains of ADAM17, ADAMTS-4 and ADAMTS-5 that are absent from complexes with MMPs. These observations suggest that further mutation of the residues of N-TIMP-3 which make unique contacts with these metalloproteinases may allow discrimination between them.
The Home, the Veil and the World: Reading Ismat Chughtai towards a ‘Progressive’ History of the Indian Women's Movement
Authors: Batra Kanika
Published: July 2010

This paper discusses the work of Ismat Chughtai (1911–1991), a controversial writer whose long literary career extending over four decades roughly corresponds to the formative stages of the Indian women's movement. It interprets Chughtai's novella The Heart Breaks Free (1966) to forward an anti-teleological enquiry of the women's movement in India. This progressive teleology often suggested by a discussion of the ‘waves’, ‘stages’ or ‘phases’ of the Euro-American women's movement and adopted to postcolonial women's movements, such as those in India, Jamaica and South Africa, is belied by the piecemeal legislative gains won by activist efforts. Some of the questions governing my enquiry are: What lessons can a questioning of teleology teach us about the gains and losses of postcolonial women's movements? If the alternative to teleology is, as I suggest, a genealogy, then what constitutes a genealogical enquiry into the women's movement in India? In face of apparent and self-acknowledged losses and ineffectiveness in recent times, would the movement's apparent unity across religious differences be a way of initiating such an inquiry or is another mode of analysis required? The paper directs attention to the Indian women's movement's attempts at bringing together women of different religious persuasions, legislative, and religious edicts related to Muslim women's right to co-habitation and divorce, and ‘cases’ that serve as testing points of the movement's struggle against religious and state authority. It also points to the neglected factor of economic security for women as a way in which a genealogical inquiry can proceed so as to strengthen the legislation and the movement itself.
Feminist Publishing in a Cold Climate?: Australian Feminist Studies and the new ERA of Research
Authors: Spongberg Mary
Published: July 2010

This article explores the implications for feminist research and publishing in Australia in the new ‘ERA’ of research excellence. Excellence in Research for Australia (ERA) is an initiative of the Australian Federal government to assess research quality within Australia's higher education institutions using a combination of indicators and expert review by committees comprising experienced, internationally recognised experts (Australian Research Council, 2008).
Determination of band offsets, chemical bonding, and microstructure of the (TbxSc1−x)2O3/Si system
Authors: Geppert I. , Eizenberg M. , Bojarczuk N. A. , Edge L. F. , Copel M. , Guha S.
Published: July 2010

The energy band gap, the band alignment with Si, and the chemical bonding of 4–5 nm thick (TbxSc1−x)2O3 dielectric films were investigated as a function of composition. Films with x=0, 0.5, and 1 were prepared by a molecular beam deposition technique on silicon substrates. The structure of the dielectric films was characterized by high resolution transmission electron microscopy. We found that upon deposition, a silicate and a silicon oxide layer were formed at the dielectric/silicon interface for all compositions. X-ray photoelectron spectroscopy was used to determine the band gap, as well as the energy band alignment with Si and the chemical structure of the films. Energy gap values of 6.0±0.2 and 7.5±0.2 eV were obtained for pure Sc2O3 and Tb2O3, respectively, while for the mixed layer (x=0.5) a value of 6.8±0.2 eV was extracted. It was found that the valence band offset does not change with Sc addition to Tb2O3, while the conduction band offset increases with x, from a value of 2.9±0.2 eV for the x=0 (pure Sc2O3) to a value of 5.7±0.2 eV for x=1 (pure Tb2O3).
Unbiased diffusion in tubes with corrugated walls
Authors: Dagdug Leonardo , Vazquez Marco-Vinicio , Berezhkovskii Alexander M. , Bezrukov Sergey M.
Published: July 2010

This study is devoted to unbiased motion of a point Brownian particle in a tube with corrugated walls made of conical sections of a varying length. Effective one-dimensional description in terms of the generalized Fick-Jacobs equation is used to derive a formula which gives the effective diffusion coefficient of the particle as a function of the geometric parameters of the tube. Comparison with the results of Brownian dynamics simulations allows us to establish the domain of applicability of both the one-dimensional description and the formula for the effective diffusion coefficient.
Spin wave resonance excitation in ferromagnetic films using planar waveguide structures
Authors: Khivintsev Y. V. , Reisman L. , Lovejoy J. , Adam R. , Schneider C. M. , Camley R. E. , Celinski Z. J.
Published: July 2010

We explore a new geometry allowing effective excitation of the lowest antisymmetric standing spin wave mode in ferromagnetic metallic films with symmetrical boundary conditions. The approach is based on the use of a coplanar waveguide with the ferromagnetic film, Permalloy (Py), playing the role of the signal line. In addition, we study a signal line which is a sandwich of Py inside two nonmagnetic metallic films. We find that the thickness and conductivity of the metal films can significantly alter the amount of absorption, at ferromagnetic resonance, between the symmetric and antisymmetric spin wave modes. The experimental results are supported by numerical calculations indicating the origin of the strength of the absorption.
Exponential error rates in multiple state discrimination on a quantum spin chain
Authors: Nussbaum Michael , Szkoła Arleta
Published: July 2010

We consider decision problems on finite sets of hypotheses represented by pairwise different shift-invariant states on a quantum spin chain. The decision in favor of one of the hypotheses is based on outcomes of generalized measurements performed on local states on blocks of finite size. We assume the existence of the mean quantum Chernoff distances of any pair of states from the given set and refer to the minimum of them as the mean generalized quantum Chernoff distance. We establish that this minimum specifies an asymptotic bound on the exponential rate of decay of the averaged probability of rejecting the true state in increasing block size, if the mean quantum Chernoff distance of any pair of the hypothetic states is achievable as an asymptotic error exponent in the corresponding binary problem. This assumption is, in particular, fulfilled by shift-invariant product states (independent and identically distributed states). Further, we provide a constructive proof for the existence of a sequence of quantum tests in increasing block length with an error exponent which equals, up to a factor, the mean generalized quantum Chernoff distance. The factor depends on the configuration of the hypothetic states with respect to the binary quantum Chernoff distances. It can be arbitrary close to 1 and is never less than 1/m for m being the number of different pairs of states.
Householder factorizations of unitary matrices
Authors: Urías Jesús
Published: July 2010

A method to construct all representations of finite dimensional unitary matrices as the product of Householder reflections is given. By arbitrarily severing the state space into orthogonal subspaces, the method may, e.g., identify the entangling and single-component quantum operations that are required in the engineering of quantum states of composite (multipartite) systems. Earlier constructions are shown to be extreme cases of the unifying scheme that is presented here.
Active low temperature oxidation as a route to minimize electrode–oxide interface reactions in nanoscale capacitors
Authors: Podpirka Adrian , Viswanath B. , Ramanathan Shriram
Published: July 2010

The electrical characteristics of reactive metal–oxide interfaces are largely dependent on the thermodynamics and kinetics of interfacial reactions that may occur during synthesis and further processing conditions. Such reactions may lead to undesirable properties such as increased loss tangent, frequency dispersion, or asymmetric capacitance. Metals such as Ni are being explored as electrodes in various electronic packaging as well as on-chip decoupling capacitors and this presents a challenge to advance processing routes that render utilization of high-dielectric constant oxide thin films. In this work, we demonstrate that photon-assisted oxidation enables a unique low temperature processing route to synthesize reduced loss (Ba,Sr)TiO3 thin film based capacitors with Ni bottom electrodes. Our results show a decrease in the dielectric loss tangent in photon-assisted oxidized films compared to conventionally re-oxidized at an applied field of 0.33 MV/cm, tan δ of 0.08 versus 0.63, respectively. Leakage currents showed a significant decrease, 7.8 A/cm2 for conventional re-oxidation versus 0.046 A/cm2 for photon assisted, at an applied field of 0.33 MV/cm. The results are of relevance to processing reactive materials wherein athermal routes are necessary to avoid interfacial reactions.
Migration and fractionation of deformable particles in microchannel
Authors: Hsu Chia Wei , Chen Yeng-Long
Published: July 2010

The complexity of the coupling between soft particle deformation and fluid perturbation has limited studies of soft particle hydrodynamics to dilute suspensions. A hybrid Brownian dynamics-lattice Boltzmann method is presented that models nondilute soft spherical deformable particle (DP) suspensions in flow. Dependences on particle size and density are investigated for suspensions with over 100 DP. Multi-DP interactions lead to complex dependence of particle distributions on concentration and flow rate. Flow-induced DP migration toward channel center for DP in narrow channels is found. In wide channels, off-center peaks in the center of mass distribution for DP are found. The migration of DP leads to faster average speed of DP than the flow, which can be exploited for fractionating DPs of different sizes.
Global isomorphism between the Lennard-Jones fluids and the Ising model
Authors: Kulinskii V. L.
Published: July 2010

The interpretation of the linear character of the observable classic rectilinear diameter law and the linear character of the Zeno-line (unit compressibility line Z=1) on the basis of global isomorphism between Ising model (lattice gas) and simple fluid is proposed. The correct definition of the limiting nontrivial Zeno state is given and its relation to the locus of the critical point is derived within this approach. We show that the liquid-vapor part of the phase diagram of the molecular fluids can be described as the isomorphic image of the phase diagram of the lattice gas. It is shown how the position of the critical points of the fluids of the Lennard-Jones type can be determined based on the scaling symmetry. As a sequence, the explanation of the well-known fact about “global” cubic character of the coexistence curve of the molecular fluids is proposed.
Observation of a barium xenon exciplex within a large argon cluster
Authors: Briant M. , Gaveau M.-A. , Mestdagh J.-M.
Published: July 2010

Spectroscopic measurements provide fluorescence and excitation spectra of a single barium atom codeposited with xenon atoms on argon clusters of average size ≈2000. The spectra are studied as a function of the number of xenon atoms per cluster. The excitation spectrum with ∼10 xenon atoms per cluster is qualitatively similar to that observed when no xenon atom is present on the cluster. It consists of two bands located on each side of the 6s6p P1−6s2 S1 resonance line of the free barium. In contrast, the fluorescence spectrum differs qualitatively since a barium-xenon exciplex is observed, which has no counterpart in xenon free clusters. In particular an emission is observed, which is redshifted by 729 cm−1 with respect to the Ba(6s6p P1−6s2 S1) resonance line.
A high resolution, broad energy acceptance spectrometer for laser wakefield acceleration experiments
Authors: Sears Christopher M. S. , Cuevas Sofia Benavides , Schramm Ulrich , Schmid Karl , Buck Alexander , Habs Dieter , Krausz Ferenc , Veisz Laszlo
Published: July 2010

Laser wakefield experiments present a unique challenge in measuring the resulting electron energy properties due to the large energy range of interest, typically several 100 MeV, and the large electron beam divergence and pointing jitter >1 mrad. In many experiments the energy resolution and accuracy are limited by the convolved transverse spot size and pointing jitter of the beam. In this paper we present an electron energy spectrometer consisting of two magnets designed specifically for laser wakefield experiments. In the primary magnet the field is produced by permanent magnets. A second optional electromagnet can be used to obtain better resolution for electron energies above 75 MeV. The spectrometer has an acceptance of 2.5–400 MeV (Emax/Emin>100) with a resolution of better than 1% rms for electron energies above 25 MeV. This high resolution is achieved by refocusing electrons in the energy plane and without any postprocessing image deconvolution. Finally, the spectrometer employs two complimentary detection mechanisms: (1) absolutely calibrated scintillation screens imaged by cameras outside the vacuum chamber and (2) an array of scintillating fibers coupled to a low-noise charge-coupled device.
Stress generation in silicon particles during lithium insertion
Authors: Golmon Stephanie , Maute Kurt , Lee Se-Hee , Dunn Martin L.
Published: July 2010

Using a fully-coupled diffusion-elasticity model with Butler–Volmer surface kinetics, we simulate the insertion of lithium into spherical silicon particles. Simulations predict the evolution of concentration, displacements, and stresses in the particles during the first insertion of Li. The particle response depends strongly on the reaction kinetics and the resulting stresses can be above the tensile failure stress of silicon depending on the particle size and discharge rate.
A homogeneous nonequilibrium molecular dynamics method for calculating the heat transport coefficient of mixtures and alloys
Authors: Mandadapu Kranthi K. , Jones Reese E. , Papadopoulos Panayiotis
Published: July 2010

This work generalizes Evans’ homogeneous nonequilibrium method for estimating heat transport coefficient to multispecies molecular systems described by general multibody potentials. The proposed method, in addition to being compatible with periodic boundary conditions, is shown to satisfy all the requirements of Evans’ original method, namely, adiabatic incompressibility of phase space, equivalence of the dissipative and heat fluxes, and momentum preservation. The difference between the new equations of motion, suitable for mixtures and alloys, and those of Evans’ original work are quantified by means of simulations for fluid Ar–Kr and solid GaN test systems.
Electron cyclotron emission reconstruction image and m/n=3/2 mode in HT-7 tokamak
Authors: Li Erzhong , Hu Liqun , Ling Bili , Liu Yong , Ti Ang , Chen Kaiyun , Shen Biao , Gao Xiang
Published: July 2010

Electron cyclotron emission reconstruction image has been used for flux surface reconstruction. The reconstruction image is based on plasma rigid rotation which is obtained from Mirnov diagnostic. From the reconstructed two-dimensional flux surface, the classical m/n=3/2 mode is visualized, which is of similar spatial structure as neoclassical 3/2 mode observed in some other tokamaks [B. Esposito et al., Phys. Rev. Lett. 100, 045006 (2008)].
Cylindrically symmetric vacuum solutions in higher dimensional Brans–Dicke theory
Authors: Baykal Ahmet , Çiftci Dilek K. , Delice Özgür
Published: July 2010

Higher dimensional, static, cylindrically symmetric vacuum solutions with and without a cosmological constant in the Brans–Dicke theory are presented. We show that for a negative cosmological constant and for specific values of the parameters, a particular subclass of these solutions includes higher dimensional topological black hole-type solutions with a flat horizon topology. We briefly extend our discussion to stationary vacuum and Λ-vacuum solutions.
Epitaxial growth and structure of (La1−xLux)2O3 alloys on Si(111)
Authors: Watahiki T. , Grosse F. , Braun W. , Kaganer V. M. , Proessdorf A. , Trampert A. , Riechert H.
Published: July 2010

LaLuO 3 layers are epitaxially grown on Si(111) by molecular beam epitaxy using high temperature effusion sources. Samples are prepared by simultaneous as well as alternating growth of La2O3 and Lu2O3. Grazing incidence x-ray diffraction indicates that the resulting crystal structure of the alloys is cubic. Simultaneous and alternating growth with a monolayer period lead to the same distribution of La and Lu with no preferential ordering. In all cases the lattice mismatch to Si is less than 0.6%. The experimental results are analyzed by studying the energetics of hexagonal, bixbyite, and perovskite (La1−xLux)2O3 crystal structures employing density functional theory.
Water filling of hydrophilic nanopores
Authors: de la Llave Ezequiel , Molinero Valeria , Scherlis Damián A.
Published: July 2010

Molecular dynamics simulations of water in cylindrical hydrophilic pores with diameters of 1.5 and 3 nm were performed to explore the phase behavior and the nucleation dynamics of the confined fluid as a function of the percentage of volume filled f. The interactions of water with the pore wall were considered to be identical to the interactions between water molecules. At low water contents, all the water is adsorbed to the surface of the pore. A second phase consisting of a liquid plug appears at the onset filling for capillary condensation, fonset=27% and 34% for the narrow and wide pores, respectively. In agreement with experimental results for silica pores, the liquid phase appears close to the equilibrium filling feq in the 1.5 nm pore and under conditions of strong surface supersaturations for the 3 nm pore. After condensation, two phases, a liquid plug and a surface-adsorbed phase, coexist in equilibrium. Under conditions of phase coexistence, the water surface density Γcoex was found to be independent of the water content and the diameter of the pore. The value of Γcoex found in the simulations (∼3 nm−2) is in good agreement with experimental results for silica pores, suggesting that the interactions of water with silica and with itself are comparable. The surface-adsorbed phase at coexistence is a sparse monolayer with a structure dominated by small water clusters. We characterize the density and structure of the liquid and surface phases, the nucleation mechanism of the water plug, and the effect of surface hydrophilicity on the two-phase equilibrium and hysteresis. The results are discussed in light of experiments and previous simulations.
Influence of aluminum ions on fluorescent spectra and upconversion in codoped CaF2–Al2O3–P2O5–SiO2:Ho3+ and Er3+ glass system
Authors: Gandhi Y. , Rao M. V. Ramachandra , Rao Ch. Srinvasa , Srikumar T. , Kityk I. V. , Veeraiah N.
Published: July 2010

The glasses of the composition 20CaF2–xAl2O3–(59−x)P2O5–20SiO2:1.0Ho2O3/1.0Er2O3 and 20CaF2–xAl2O3–(59−x)P2O5–20SiO2:(0.6Ho2O3+0.4Er2O3) with x varying from 2 to 10 mol % have been synthesized. Optical absorption and fluorescence spectra (in the spectral range 350–2100 nm were studied at ambient temperature. The Judd–Ofelt theory was applied to characterize the absorption and luminescence spectra of Ho3+ and Er3+ ions in these glasses. Following the luminescence spectra, various radiative properties like transition probability A, branching ratio β, and the radiative life time τ for blue (B), green (G), and red (R) emission levels of these glasses have been evaluated. The radiative life times for these transitions of Ho3+ and Er3+ have also been measured. The variations observed in these parameters were discussed in the light of varying coordinations (tetrahedral and octahedral positions) of Al3+ ions in the glass network. The energy transfer between the two rare earth ions (Ho3+ and Er3+) in codoped CaF2–Al2O3–P2O5–SiO2 glass system in the visible and near infrared (NIR) regions has also been investigated as a function of varying concentration of Al2O3. A significant enhancement in the intensities of B, G, and R lines has been observed due to codoping. The quantitative analysis of these results (with the aid of the data on IR and Raman spectral studies) has indicated that the glasses mixed with around 6.0 mol % of Al2O3 is the optimum concentration for yielding the highest quantum efficiency and for maximum energy transfer with low phonon losses.
Number of graphene layers as a modulator of the open-circuit voltage of graphene-based solar cell
Authors: Ihm Kyuwook , Lim Jong Tae , Lee Kyoung-Jae , Kwon Jae Wook , Kang Tai-Hee , Chung Sukmin , Bae Sukang , Kim Jin Ho , Hong Byung Hee , Yeom Geun Young
Published: July 2010

Impressive optical properties of graphene have been attracting the interest of researchers, and, recently, the photovoltaic effects of a heterojunction structure embedded with few layer graphene (FLG) have been demonstrated. Here, we show the direct dependence of open-circuit voltage (Voc) on numbers of graphene layers. After unavoidably adsorbed contaminants were removed from the FLGs, by means of in situ annealing, prepared by layer-by-layer transfer of the chemically grown graphene layer, the work functions of FLGs showed a sequential increase as the graphene layers increase, despite of random interlayer-stacking, resulting in the modulation of photovoltaic behaviors of FLGs/Si interfaces.
Energy and exergy analysis of hybrid photovoltaic/thermal solar water heater considering with and without withdrawal from tank
Authors: Dubey Swapnil , Tiwari G. N.
Published: July 2010

In this paper, an attempt has been made for evaluating the overall thermal energy and exergy provided in the form of heat and electricity from hybrid photovoltaic/thermal (PV/T) solar water heating system considering five different cases with and without withdrawals. The annual heat and electricity are evaluated by considering the four types of weather conditions for five different cities of India (New Delhi, Bangalore, Mumbai, Srinagar, and Jodhpur). It is found that the annual maximum heat and electricity are obtained in case (ii) (energy: 4263.2 kW h and exergy: 529.7 kW h) and minimum in case (v) (energy: 1038.8 kW h and exergy: 196.9 kW h) as compared to all other cases for New Delhi condition. Annual maximum and minimum energy gains and efficiency are obtained for Jodhpur and Srinagar City, respectively. This type of configuration (hybrid PV/T) is very useful in the remote and urban areas, where the electricity and hot water can be obtained simultaneously.
Relaxor-like behavior of BaTiO3 crystals from acoustic emission study
Authors: Dul'kin E. , Petzelt J. , Kamba S. , Mojaev E. , Roth M.
Published: July 2010

BaTiO 3 crystals were studied by means of the acoustic emission during thermal cycling through 300–700 K range. In addition to pronounced acoustic emission at the ferroelectric phase transition temperature Tc≈400 K, also nucleation of nanoclusters was detected at somewhat smeared Burns temperature Td≈530–570 K and their local freezing at T∗≈506 K. Bias electric field shifts the T∗ and Tc linearly up, T∗ more steeply than Tc. Except for its much faster cluster dynamics than that of classical relaxor materials, BaTiO3 shows many relaxor-like features in its paraelectric phase.
Numerical analysis of efficiency droop induced by piezoelectric polarization in InGaN/GaN light-emitting diodes
Authors: Son Jun Ho , Lee Jong-Lam
Published: July 2010

The effects of piezoelectric polarization on efficiency droop in InGaN/GaN light-emitting diodes (LEDs) have been investigated using numerical analysis. The simulation results showed that the severe band bending in InGaN quantum-well was improved as the piezoelectric polarization is reduced, resulting in the improved overlap of electron and hole wave functions. As a results, the internal quantum efficiency increases and efficiency droop significantly reduces. The reduction in piezoelectric polarization could be derived by applying a tensile stress to relax compressive stress in GaN epilayer, improving the efficiency droop of vertical-structure LEDs, agree well with simulation ones.
Impact of nonequilibrium phonons on the electron dynamics in terahertz quantum cascade lasers
Authors: Iotti Rita Claudia , Rossi Fausto , Vitiello Miriam Serena , Scamarcio Gaetano , Mahler Lukas , Tredicucci Alessandro
Published: July 2010

In this paper we investigate, both theoretically and experimentally, nonequilibrium electron and phonon effects in quantum-cascade devices. In particular, we have developed a Monte Carlo-based global kinetic approach describing the complete interacting electronic subsystem (i.e., the full set of active-region and injector subbands) coupled to out-of-equilibrium longitudinal polar-optical (LO) phonons, which in turn will decay anharmonically into thermalized acoustic modes. Simulated results obtained for a prototypical terahertz emitting device show a very good agreement with measured data, evidencing how the nonequilibrium LO phonon population affects the electro-optical device performances. The latter may be qualitatively reproduced in terms of a global effective temperature of the heated phononic system.
Note: A thermally stable tension meter for atmospheric soundings using kites
Authors: Walesby K. T. , Harrison R. G.
Published: July 2010

Kites offer considerable potential as wind speed sensors—a role distinct from their traditional use as instrument-carrying platforms. In the sensor role, wind speed is measured by kite-line tension. A kite tether line tension meter is described here, using strain gauges mounted on an aluminum ring in a Wheatstone bridge electronic circuit. It exhibits a linear response to tension (19.5 mV N−1) with good thermal stability (mean drift of −0.18 N °C−1 over 5–45 °C temperature range) and a rapid time response (0.2 s or better). Field comparisons of tether line tension for a Rokkaku kite with a fixed tower sonic anemometer show an approximately linear tension-wind speed relationship over the range 1–6 ms−1.
Indefinite permittivity in uniaxial single crystal at infrared frequency
Authors: Wang Rui , Sun Jingbo , Zhou Ji
Published: July 2010

We propose a kind of indefinite media at infrared frequency without artificial structures. Natural existing indefinite media are realized based on strong anisotropy in polar lattice vibrations in different directions, parallel or perpendicular to the crystal axis. As an example, the dielectric dispersions of α-Al2O3 single crystal with different polarizations of electric field are measured, the regions of indefinite permittivity are demonstrated and an all-angle negative refraction is also shown based on the simulated results. This mechanism to realize indefinite medium will supply a promising way to explore natural existing negative refraction materials.
Terahertz complex conductivities of carriers with partial localization in doped polythiophenes
Authors: Unuma Takeya , Fujii Kenji , Kishida Hideo , Nakamura Arao
Published: July 2010

We have investigated the complex conductivity spectra σ̃(ω) of two p-doped polythiophenes—poly(3-hexylthiophene) and poly(3,4-ethylenedioxythiophene)—with various carrier densities by using terahertz time-domain spectroscopy. The real part of σ̃(ω) is found to gradually decrease with decreasing frequency ω and to approach a finite value for ω→0 unlike the Drude conductivity behavior, suggesting that carriers in polythiophenes have a partially localized nature. By reproducing both the measured real and imaginary parts of σ̃(ω) with the Drude–Smith model, we show that carriers become less localized with increasing carrier density up to ∼1.8×1020 cm−3.
Direct experimental measurement of phase-amplitude coupling in spin torque oscillators
Authors: Bianchini L. , Cornelissen S. , Kim Joo-Von , Devolder T. , van Roy W. , Lagae L. , Chappert C.
Published: July 2010

We study spin-torque induced oscillations of MgO magnetic tunnel junctions in the time domain. By using the Hilbert transform on the time traces, we obtain for the first time a direct experimental measure of the coupling between the power and the phase fluctuations. We deduce the power restoration rate and we obtain low values for the coupling strength, which is consistent with the weak frequency dependence on the applied voltage.
Observation of bias-dependent low field positive magneto-resistance in Co-doped amorphous carbon films
Authors: Hsu H. S. , Chung P. Y. , Zhang J. H. , Sun S. J. , Chou H. , Su H. C. , Lee C. H. , Chen J. , Huang J. C. A.
Published: July 2010

We report a considerable intrinsic positive magnetoresistance (PMR) effect in Co-doped amorphous carbon films by radio frequency magnetron sputtering. The kind of PMR effect is bias dependence and its ratio reaches a peak at a particular voltage. At room temperature, the maximum PMR ratio is about 10% among these samples. The x-ray absorption spectroscopy and Raman spectra results support the appearance of the bias-dependent PMR effect strongly depends on the sp2 states and Co dopants. A phenomenological model related to orbital Zeeman splitting has been proposed to describe the resistance, which is controlled by voltage and magnetic field.
Domain wall creep in (Ga,Mn)As
Authors: Kanda A. , Suzuki A. , Matsukura F. , Ohno H.
Published: July 2010

We have compared the scaling exponents in scaling formula for magnetic domain wall creep by measuring the magnetic-field induced domain wall velocity of (Ga,Mn)As layers grown on (In,Al)As semistep-graded buffer layer and (In,Ga)As buffer layer. The different critical exponents for the two (Ga,Mn)As layers indicate that the observed creep motions belong to different universality classes, which are found to be governed by the degree of surface roughness due to crosshatch dislocation introduced during epitaxial growth. Domain wall creep motion in (Ga,Mn)As layer grown on (In,Al)As with flatter surface belongs to random-field disorder, whereas that in (In,Ga)As to random-bond disorder.
AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors with ZnO gate layer and (NH4)2Sx surface treatment
Authors: Chiou Ya-Lan , Lee Chi-Sen , Lee Ching-Ting
Published: July 2010

The AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) with ZnO gate insulator deposited using a vapor cooling condensation system were fabricated. The AlGaN surface treatment using (NH4)2Sx was performed to improve the quality of the interface between the ZnO layer and AlGaN layer. The (NH4)2Sx-treated MOS-HEMTs exhibited a higher saturation drain-source current of 0.74 A/mm, a maximum extrinsic transconductance of 200 mS/mm, an unit gain cutoff frequency of 9.1 GHz, a maximum frequency of oscillation of 17.1 GHz, and the Hooge’s coefficient of 8.28×10−6. The improved performances of the (NH4)2Sx-treated MOS-HEMTs were attributed to the reduction in surface states.
Nutrient responses differ between node and organogenic cultures of Corymbia torelliana×C. citriodora (Myrtaceae)
Authors: Hung Cao Dinh , Trueman Stephen J.
Published: July 2010

Hybrids between Corymbia torelliana (F.Muell.) K.D.Hill & L.A.S.Johnson and C. citriodora subsp. variegata (F.Muell.) A.R.Bean & M.W.McDonald are used extensively for plantation forestry in subtropical eastern Australia; however, plantation establishment has been hampered by inadequate seed supply and variable amenability to propagation as rooted cuttings. The present study investigated node-culture and organogenic-culture methods for in vitro propagation of two families of juvenile Corymbia hybrids. The effects of nutrient and auxin concentrations on root formation, shoot elongation and shoot proliferation, and subsequent conversion to plantlets in an in vitro soil-less system, were assessed. The response to the nutrient concentration differed between organogenic and node cultures. Half-strength, compared with full-strength, medium with auxin increased shoot proliferation by 58% for one family in the node culture, in which many shoots form roots and elongate rapidly in the absence of cytokinin. However, full-strength medium increased shoot proliferation by 213% over that in the half-strength medium for the other family in the organogenic culture, in which shoots do not form roots in the presence of cytokinin, and nutrient uptake occurs via callus and stem tissue rather than roots. The auxin, naphthalene acetic acid, sometimes stimulated root formation and shoot elongation in the node culture, although it had no effect on the final number of shoots. Most shoots (57–100%) subsequently formed roots in the in vitro soil-less medium. The high rates of proliferation and plantlet conversion in the present study provide the means, not only for simultaneous laboratory storage and field-testing of Corymbia clones before selection of desired genotypes, but also for en masse plantlet production of selected clones or families for plantation establishment.
Ageing mallee eucalypt vegetation after fire: insights for successional trajectories in semi-arid mallee ecosystems
Authors: Clarke Michael F. , Avitabile Sarah C. , Brown Lauren , Callister Kate E. , Haslem Angie , Holland Greg J. , Kelly Luke T. , Kenny Sally A. , Nimmo Dale G. , Spence-Bailey Lisa M. , Taylor Rick S. , Watson Simon J. , Bennett Andrew F.
Published: July 2010

A critical requirement in the ecological management of fire is knowledge of the age-class distribution of the vegetation. Such knowledge is important because it underpins the distribution of ecological features important to plants and animals including retreat sites, food sources and foraging microhabitats. However, in many regions, knowledge of the age-class distribution of vegetation is severely constrained by the limited data available on fire history. Much fire-history mapping is restricted to post-1972 fires, following satellite imagery becoming widely available. To investigate fire history in the semi-arid Murray Mallee region in southern Australia, we developed regression models for six species of mallee eucalypt (Eucalyptus oleosa F.Muell. ex. Miq. subsp. oleosa, E. leptophylla F.Muell. ex. Miq., E. dumosa J. Oxley, E. costata subsp. murrayana L. A. S. Johnson & K. D. Hill, E. gracilis F.Muell. and E. socialis F.Muell. ex. Miq.) to quantify the relationship between mean stem diameter and stem age (indicated by fire-year) at sites of known time since fire. We then used these models to predict mean stem age, and thus infer fire-year, for sites where the time since fire was not known. Validation of the models with independent data revealed a highly significant correlation between the actual and predicted time since fire (r = 0.71, P < 0.001, n = 88), confirming the utility of this method for ageing stands of mallee eucalypt vegetation. Validation data suggest the models provide a conservative estimate of the age of a site (i.e. they may under-estimate the minimum age of sites >35 years since fire). Nevertheless, this approach enables examination of post-fire chronosequences in semi-arid mallee ecosystems to be extended from 35 years post-fire to over 100 years. The predicted ages identified for mallee stands imply a need for redefining what is meant by ‘old-growth’ mallee, and challenges current perceptions of an over-abundance of ‘long-unburnt’ mallee vegetation. Given the strong influence of fire on semi-arid mallee vegetation, this approach offers the potential for a better understanding of long-term successional dynamics and the status of biota in an ecosystem that encompasses more than 250 000 km2 of southern Australia.
Leaf anatomy and histochemistry of Lippia citriodora (Verbenaceae)
Authors: Argyropoulou Catherine , Akoumianaki-Ioannidou Anastasia , Christodoulakis Nikolaos S. , Fasseas Costas
Published: July 2010

Lippia citriodora H.B.K. is an aromatic plant indigenous to South America. It is cultivated and commercialised as an ornamental for its lemon-like scent emitted from its leaves and flowers. The present morphoanatomical and histochemical study revealed that leaves of L. citriodora possess one type of setae (non-glandular) and at least five types of glandular trichomes, with the latter differing anatomically and in the composition of their secondary metabolites. Scanning electron microscopy revealed that the same types of trichomes exist also on the calyces. Histochemical tests indicate that the glandular trichomes contain a combination of terpenoids, flavonoids, carbohydrates, phenolics and alkaloids. However, within the vacuoles of the mesophyll cells, terpenoids, phenolics, flavonoids and tannins are stored. The presence of lamellar cytoplasmic inclusions in the mesophyll cells, possibly precursors of tannins stored in the vacuoles, is reported for the first time.
Representativeness of the Surveillance Data in the Intensive Care Unit Component of the German Nosocomial Infections Surveillance System
Authors: Zuschneid Irina , Rücker Gerta , Schoop Rotraut , Beyersmann Jan , Schumacher Martin , Geffers Christine , Rüden Henning , Gastmeier Petra
Published: July 2010

Objective.

To assess the representativeness of the data in the Krankenhaus Infektions Surveillance System (KISS), which is a nosocomial infections surveillance system for intensive care units (ICUs) in Germany.

Design.

Prospective and retrospective surveillance study.

Setting.

Medical-surgical ICUs in Germany.

Methods.

A sample of medical-surgical ICUs from all over Germany, stratified according to hospital size, was randomly selected. Surveillance personnel from the hospitals were trained in surveillance of nosocomial infections, and they subsequently conducted a 2-month surveillance in their ICUs. Data were compared with KISS data for medical-surgical ICUs.

Results.

During the period from 2004 through 2005, a total of 50 medical-surgical ICUs agreed to participate in our study: 21,832 patient-days were surveyed, and 262 cases of nosocomial infection were registered, 176 of which were cases of device-associated nosocomial infection (100 cases of lower respiratory tract infection, 47 cases of urinary tract infection, and 29 cases of bloodstream infection). The overall incidence density of all types of nosocomial infections was estimated to be 10.65 cases per 1,000 patient-days. Device utilization rates in the study ICUs and in the KISS medical-surgical ICUs were similar. The pooled mean device-associated infection rates were higher in the study ICUs than in the KISS medical-surgical ICUs (10.2 vs 5.1 cases of pneumonia; 2.0 vs 1.2 cases of bloodstream infection; and 2.7 vs 1.2 cases of urinary tract infection), but the pooled mean device-associated infection rates in the study ICUs were comparable to those of the KISS ICUs during their first year of participation in KISS. The incidence density for nosocomial infections in the study ICUs varied according hospital size, with ICUs in larger hospitals having a higher incidence density than those in smaller hospitals.

Conclusions.

KISS ICUs started with nosocomial infection rates comparable to those found in our study ICUs. Over the years of participation, however, a decrease in nosocomial infections is seen. Thus, rates of nosocomial infection from KISS should be used as benchmarks, but estimations for Germany that are based on KISS data may underestimate the real burden of nosocomial infections.
Young Practitioners Group
Authors: Edara Ramesh Babu , Vaziri Roya
Published: July 2010

We currently have an excellent GP specialty training programme where trainees are very well supported in all aspects. Once qualified, however, many GPs not only feel isolated but also have to face challenges such as looking for a job, organizing locum work, understanding quality and outcomes framework, etc, while also dealing with the real, exciting and rewarding work that is general practice. Additionally, this often involves a move to a new area, where there is a need to get to know the local services and medical community. These problems together with the new and important revalidation and relicensing hoops to jump through can induce great uncertainty, vulnerability and sense of isolation in the initial stages of your life as an independent practitioner. This is a far cry from the regular educational and supportive peer group meetings that most of you have in your training.
Understanding the Physicochemical and Functional Properties of Wheat Starch in Various Foods
Authors: Maningat Clodualdo C. , Seib Paul A.
Published: July 2010

This report highlights the structure and myriad properties of wheat starch in various food systems. Granule shape, size, and color, plus the proportion of A‐ and B‐granules, amylose content, and molecular structure largely determine its functionality in food. The role of wheat starch is portrayed in three categories of flour‐based foods that differ in water content. Wheat starch influences the appearance, cooking characteristics, eating quality, and texture of pasta and noodles, and its role is more than a filler in yeast‐leavened bread products. Recent developments in the properties and applications of commercially important wheat pyrodextrins and RS4‐type resistant wheat starches are reported, along with their use to produce fiber‐fortified foods. Gluten‐free foods are also discussed.
REVIEW: Cereal Carbohydrates and Colon Health
Authors: Zhang Genyi , Hamaker Bruce R.
Published: July 2010

Providing balanced energy and nutrients for microbiota growth is essential for the maintenance of the colon ecosystem, and dietary fiber (DF) fermentation, particularly butyrogenic fermentation, augments colon health. Cereal DF, which are the complex carbohydrates of cereal grains that escape small intestine digestion and function either as substrate for colonic fermentation or as bulking material, are a dietary measure to mitigate the occurrence of certain colonic diseases, and perhaps to some degree act as therapeutic agents. In developed Western countries, as well as in many developing countries, colon cancer is one of the major causes for premature death and disability, and inflammatory bowel disease and other colonic disorders have become serious health issues. The function of DF in colon health is mediated through its physicochemical properties (e.g., water‐holding for laxative effect) or effect on colon microbiota (e.g., leading to immune regulation), as well as through colonic fermentation products, principally the short chain fatty acids (SCFA) of acetate, propionate, and butyrate. Due to the chemical diversity and complexity of DF and because not all DF materials function equally, new developments in DF fermentation behavior (pattern and end product profile) will be reviewed from a structure‐function viewpoint. The effect of cereal DF, mainly nonstarch cereal polysaccharides and resistant starch on colonic microbiota, fermentation products of SCFA, microbiota modulation, as well as on colon health will be summarized.