bluuebunny/crossref_metadata_2025 huggingface dataset:
Duty‐cycle detector based on time‐to‐digital conversion
Authors: Ravezzi L.
Published: February 2013

A duty cycle detector based on time‐to‐digital conversion is presented. It combines the advantages of analogue (high accuracy and simplicity) and digital (digital output) duty cycle correctors in a simple and straightforward topology. Two identical circuits detect the high and low phases of the input clock and deliver two digital words. These two words are then sufficient to accurately estimate the input duty cycle. By using the same topology for both circuits, accuracy is affected only by mismatches between them. Designed in a bulk 28nm CMOS technology the proposed duty cycle detector achieves a maximum linearity error of 4% and a resolution of 0.5% over corners and an input duty cycle range of [20, 80]%.
Investigation of transient photocurrent response of triple pn junction structure
Authors: Schidl S. , Polzer A. , Dong J. , Schneider‐Hornstein K. , Zimmermann H.
Published: February 2013

The transient photocurrent response of a vertically stacked triple pn junction structure, which can detect three different colours simultaneously, is investigated. The triple pn junction structure is designed based on the effect that the penetration depth in silicon depends on light wavelength. To increase the bandwidth of optical sensor systems the transient photocurrent response is a critical parameter. The transient response is measured by applying three different light wavelengths to this triple junction structure. This triple pn junction structure is fabricated in a 0.6 µm BiCMOS technology using a p−p+ epitaxial wafer without any process modification. Based on the measurement results, it can be concluded that this triple pn junction structure can be applied to optical sensors without optical filters and the total data rate of this structure can reach up to 100 Mbit/s.
Colourless operation of short‐cavity VCSELs in C‐minus band for TWDM‐PONs
Authors: Wong E. , Müller M. , Amann M.C.
Published: February 2013

The tunability feature of short‐cavity vertical‐cavity surface‐emitting lasers in the C‐minus band to provide low‐power, cost‐efficient, colourless, and legacy system compliant transmitters for future time and wavelength division multiplexed passive optical networks is investigated. For the first time, a report is presented on error‐free performances across a 800 GHz tuning range with a potential aggregate upstream capacity of 80 Gbit/s over a system reach of at least 40 km and with a 1:64 split ratio.
Design of 825 GHz square helix travelling‐wave tube
Authors: Kotiranta M. , Krozer V.
Published: February 2013

A helix travelling‐wave tube for 825 GHz has been designed and its broadband amplification performance has been demonstrated with 3D particle‐in‐simulations. The design utilises a helix slow‐wave structure with a square form and input/output couplers based on a transition from the helix to a coplanar waveguide and further to a rectangular waveguide with a through‐substrate post coupler. A simulated small‐signal gain of 18.3 dB with an output power of over 25 dBm at 1 dB compression point and a 3 dB instantaneous bandwidth of 8% have been obtained.
Cylindrical high impedance surface aided horizontally polarised omnidirectional antenna
Authors: Sugiura S. , Iizuka H.
Published: February 2013

Cylindrical high impedance surface (HIS) structures and their E‐plane omnidirectional antenna application are presented at the 2.0 GHz band. The diameter of the cylinder is 39.2 mm, when the φ‐direction periodicity is chosen as three. The HIS, when illuminated by plane waves, not only reflects them in the direction of arrival with zero phase, but also transmits them in other directions to a comparable degree, which is caused by half‐wavelength resonance of all of the patches. A dipole antenna element situated close to the HIS, the φ‐direction periodicity of which is three, exhibits VSWR = 1.5 and an omnidirectional E‐plane pattern at 2.14 GHz.
Relativistic Chasles' theorem and the conjugacy classes of the inhomogeneous Lorentz group
Authors: Minguzzi E.
Published: February 2013

This work is devoted to the relativistic generalization of Chasles' theorem, namely, to the proof that every proper orthochronous isometry of Minkowski spacetime, which sends some point to its chronological future, is generated through the frame displacement of an observer which moves with constant acceleration and constant angular velocity. The acceleration and angular velocity can be chosen either aligned or perpendicular, and in the latter case the angular velocity can be chosen equal or smaller than the acceleration. We start reviewing the classical Euler's and Chasles' theorems both in the Lie algebra and group versions. We recall the relativistic generalization of Euler's theorem and observe that every (infinitesimal) transformation can be recovered from information of algebraic and geometric type, the former being identified with the conjugacy class and the latter with some additional geometric ingredients (the screw axis in the usual non-relativistic version). Then the proper orthochronous inhomogeneous Lorentz Lie group is studied in detail. We prove its exponentiality and identify a causal semigroup and the corresponding Lie cone. Through the identification of new Ad-invariants we classify the conjugacy classes, and show that those which admit a causal representative have special physical significance. These results imply a classification of the inequivalent Killing vector fields of Minkowski spacetime which we express through simple representatives. Finally, we arrive at the mentioned generalization of Chasles' theorem.
Damping and pseudo-fermions
Authors: Bagarello F.
Published: February 2013

After a short abstract introduction on the time evolution driven by non-self-adjoint Hamiltonians, we show how the recently introduced concept of pseudo-fermion can be used in the description of damping in finite dimensional quantum systems, and we compare the results deduced adopting the Schrödinger and the Heisenberg representations.
Effect of geometrical orientation on the charge-transfer energetics of supramolecular (tetraphenyl)-porphyrin/C60 dyads
Authors: Olguin Marco , Zope Rajendra R. , Baruah Tunna
Published: February 2013

The charge transfer (CT) excited state energies of donor-acceptor (D/A) pairs determine the achievable open-circuit voltage of D/A-based organic solar cell devices. Changes in the relative orientation of donor-acceptor pairs at the interface influence the frontier orbital energy levels, which impacts the dissociation of bound excitons at the D/A-interface. We examine the effect of relative orientation on CT excited state energies of porphyrin-fullerene dyads. The donors studied are base- and Zn-tetraphenyl porphyrin coupled to C60 as the acceptor molecule in an end-on configuration. We compare the energetics of a few low-lying CT states for the end-on geometry to our previously calculated CT energetics of a co-facial orientation. The calculated CT excitation energies are larger for the end-on orientation in comparison to the co-facial structure by about 0.7 eV, which primarily occurs due to a decrease in exciton binding energy in going from the co-facial to the end-on orientation. Furthermore, changes in relative donor-acceptor orientation have a larger impact on the CT energies than changes in donor-acceptor distance.
A small subset of normal modes mimics the properties of dynamical heterogeneity in a model supercooled liquid
Authors: Hocky Glen M. , Reichman David R.
Published: February 2013

In this work, we study the nature of transitions between inherent structures of a two-dimensional model supercooled liquid. We demonstrate that these transitions occur predominately along a small number of directions on the energy landscape. Moreover, we show that the number of such directions decreases as the temperature of the liquid is decreased in the mildly supercooled regime, in concert with earlier studies on an athermal jamming system. We show that this decrease happens in parallel with a change in character of the transitions as dynamics in the system become more heterogeneous and localized. We investigate the origin of these trends, which suggests interesting connections between jamming and thermal glassy phenomena.
Effect of length on the position of negative differential resistance and realization of multifunction in fused oligothiophenes based molecular device
Authors: Fan Jiaping , Gathitu Nahashon Ndegwa , Chang Yingfei , Zhang Jingping
Published: February 2013

The length modulation of electron transport properties for molecular devices based on fused oligothiophenes has been investigated theoretically using a combination of non-equilibrium Green's functions and first-principles density functional theory. The results show that the lengths of the molecules have a distinct influence on the position of negative differential resistance (NDR) of the molecular devices. By exploring the effect on transmission properties of substituent groups, hexathieno[3,2-b:2′,3′-d]thiophene with –NH2 and –NO2 substituents (model L) can be regard as a good candidate of multifunctional molecular device, which shows excellent rectifying performance (the largest rectification ration is 14.3 at 1.2 V) and clear NDR behavior (at 1.4 V).
Nanodrop impact on solid surfaces
Authors: Koplik Joel , Zhang Rui
Published: February 2013

The impact of nanometer sized drops on solid surfaces is studied using molecular dynamics simulations. Equilibrated floating drops consisting of short chains of Lennard-Jones liquids with adjustable volatility are directed normally onto an atomistic solid surface where they are observed to bounce, stick, splash, or disintegrate, depending on the initial velocity and the nature of the materials involved. Drops impacting at low velocity bounce from non-wetting surfaces but stick and subsequently spread slowly on wetting surfaces. Higher velocity impacts produce an prompt splash followed by disintegration of the drop, while at still higher velocity, drops disintegrate immediately. The disintegration can be understood as either a loss of coherence of the liquid or as the result of a local temperature exceeding the liquid-vapor coexistence value. In contrast to macroscopic drops, the presence of vapor outside the drop does not effect the behavior in any significant way. Nonetheless, the transition between the splashing and bouncing/sticking regimes occurs at Reynolds and Weber numbers similar to those found for larger drops.
On the absence of analytic integrability of the Bianchi Class B cosmological models
Authors: Ferragut Antoni , Llibre Jaume , Pantazi Chara
Published: February 2013

We follow Bogoyavlensky's approach to deal with Bianchi class B cosmological models. We characterize the analytic integrability of such systems.
Vacuum ultraviolet dielectric function of ZnFe2O4 thin films
Authors: Böntgen T. , Brachwitz K. , Schmidt-Grund R. , Lorenz M. , Grundmann M.
Published: February 2013

The dielectric function of ZnFe2O4 thin films has been studied in a wide spectral range from 0.5 eV to 9 eV. The observed optical transitions are identified as charge transfer and ligand field transitions. We propose a parametric model based on known model dielectric functions that fits well to the experimental data. The assignment of optical transitions is justified by a thorough comparison with optical data from other materials exhibiting similar transitions. The main contributions to the optical response are found to arise from charge transfer transitions from the O2p to the metal ion 4s and 3d bands. Furthermore weak crystal field transitions are observed. The evolution of the dielectric function as well as the crystal quality of the thin films with respect to growth temperature is further analyzed. A blue shift of the observed optical transitions is related to a relaxation of the lattice toward the bulk and an increase of the crystal quality with increasing growth temperature.
Study of instabilities and quasi-two-dimensional turbulence in volumetrically heated magnetohydrodynamic flows in a vertical rectangular duct
Authors: Vetcha N. , Smolentsev S. , Abdou M. , Moreau R.
Published: February 2013

We consider magnetohydrodynamic (MHD) rectangular duct flows with volumetric heating. The flows are upward, subject to a strong transverse magnetic field perpendicular to the temperature gradient, such that the flow dynamics is quasi-two-dimensional. The internal volumetric heating imitates conditions of a blanket of a fusion power reactor, where a buoyancy-driven flow is imposed on the forced flow. Studies of this mixed-convection flow include analysis for the basic flow, linear stability analysis and Direct Numerical Simulation (DNS)-type computations. The parameter range covers the Hartmann number (Ha) up to 500, the Reynolds number (Re) from 1000 to 10 000, and the Grashof number (Gr) from 105 to 5 × 108. The linear stability analysis predicts two primary instability modes: (i) bulk instability associated with the inflection point in the velocity profile near the “hot” wall and (ii) side-wall boundary layer instability. A mixed instability mode is also possible. An equation for the critical Hartmann number has been obtained as a function of Re and Gr. Effects of Ha, Re, and Gr on turbulent flows are addressed via nonlinear computations that demonstrate two characteristic turbulence regimes. In the “weak” turbulence regime, the induced vortices are localized near the inflection point of the basic velocity profile, while the boundary layer at the wall parallel to the magnetic field is slightly disturbed. In the “strong” turbulence regime, the bulk vortices interact with the boundary layer causing its destabilization and formation of secondary vortices that may travel across the flow, even reaching the opposite wall. In this regime, the key phenomena are vortex-wall and various vortex-vortex interactions. Flow and magnetic field effects on heat transfer are also analyzed.
Effects of suboxide layers on the electronic properties of Si(100)/SiO2 interfaces: Atomistic multi-scale approach
Authors: Kim Byung-Hyun , Kim Gyubong , Park Kihoon , Shin Mincheol , Chung Yong-Chae , Lee Kwang-Ryeol
Published: February 2013

A multi-scale approach connecting the atomistic process simulations to the device-level simulations has been applied to the Si(100)/SiO2 interface system. The oxidation of Si(100) surface was simulated by the atomic level molecular dynamics, the electronic structure of the resultant Si/suboxide/SiO2 interface was then obtained by the first-principles calculations, and finally, the leakage currents through the SiO2 gate dielectric were evaluated, with the obtained interface model, by the non-equilibrium Green's function method. We have found that the suboxide layers play a significant role for the electronic properties of the interface system and hence the leakage currents through the gate dielectric.
Modular instrument mounting system for variable environment in operando X-ray experiments
Authors: Folkman C. M. , Highland M. J. , Perret E. , Kim S. K. , Fister T. T. , Zhou H. , Baldo P. M. , Seifert S. , Eastman J. A. , Fuoss P. H. , Fong D. D.
Published: February 2013

In the growing field of in operando and in situ X-ray experiments, there exists a large disparity in the types of environments and equipment to control them. This situation makes it challenging to conduct multiple experiments with a single mechanical interface to the diffractometer. Here, we describe the design and implementation of a modular instrument mounting system that can be installed on a standard six-circle diffractometer (e.g., 5021 Huber GmbH). This new system allows for the rapid changeover of different chambers and sample heaters and permits accurate sample positioning (x, y, z, and azimuthal rotation) without rigid coupling to the chamber body. Isolation of the sample motion from the chamber enclosure is accomplished through a combination of custom rotary seals and bellows. Control of the pressure and temperature has been demonstrated in the ranges of 10−6–103 Torr and 25°C–900°C, respectively. We have utilized the system with several different modular instruments. As an example, we provide in situ sputtering results, where the growth dynamics of epitaxial LaGaO3 thin films on (001) SrTiO3 substrates were investigated.
Interstitial oxygen behavior for thermal double donor formation in germanium: Infrared absorption studies
Authors: Inoue K. , Taishi T. , Tokumoto Y. , Murao Y. , Kutsukake K. , Ohno Y. , Suezawa M. , Yonenaga I.
Published: February 2013

The kinetics of the reduction of interstitial oxygen (Oi) due to the formation of thermal double donors (TDDs) upon heat treatment in an oxygen-rich Ge crystal were investigated at various temperatures. Specimens were prepared from a Ge crystal with oxygen at a concentration of 4–5 × 1017 cm−3 grown by a new Czochralski method and were heat-treated in the temperature range 300–500 °C. Shrinkage of a dissolved oxygen absorption peak at 855 cm−1 and simultaneous development of a thermal double donor peak at 780 cm−1 were observed by infrared absorption spectroscopy at room temperature. The formation of TDDs was also detected electrically. Reduction of dissolved oxygen concentration upon the heat treatments was kinetically analyzed. The activation energy of the reduction of Oi concentration was evaluated to be 1.7 and 2.0 eV in the early and prolonged stages of the heat treatment, respectively, close to that of Oi diffusion. From the results, TDD development process was indicated to be the merge reaction of Oi-Oi to form oxygen dimers (Odimer) in the early stage of the heat treatment and further enlargement of Odimer to TDDs by absorbing Oi in the prolonged stage of the heat treatment in accordance with the On-2NN model.
Temperature dependent surface photovoltage spectra of type I GaAs1−xSbx/GaAs multiple quantum well structures
Authors: Sitarek P. , Misiewicz J. , Huang Y. S. , Hsu H. P. , Tiong K. K.
Published: February 2013

We present temperature dependent surface photovoltage spectra of GaAs1−xSbx/GaAs multiple quantum well structures. Our previous studies [Sitarek et al., J. Appl. Phys. 105, 123523 (2009)] have identified all features present in the surface photovoltage spectra and showed weak type-I band alignment in the investigated GaAsSb/GaAs system. By analyzing the changes in the relative intensity of features near the energy of fundamental transitions caused by the temperature variations, we are able to determine the energy difference between electronic states localized in GaAsSb quantum well and conduction band edge in the GaAs barrier. In addition, the Bose-Einstein parameters that describe the temperature dependences of 1hh-1e transitions are evaluated and discussed.
Transport of radial heat flux and second sound in fusion plasmas
Authors: Gürcan Ö. D. , Diamond P. H. , Garbet X. , Berionni V. , Dif-Pradalier G. , Hennequin P. , Morel P. , Kosuga Y. , Vermare L.
Published: February 2013

Simple flux-gradient relations that involve time delay and radial coupling are discussed. Such a formulation leads to a rather simple description of avalanches and may explain breaking of gyroBohm transport scaling. The generalization of the flux-gradient relation (i.e., constitutive relation), which involve both time delay and spatial coupling, is derived from drift-kinetic equation, leading to kinetic definitions of constitutive elements such as the flux of radial heat flux. This allows numerical simulations to compute these cubic quantities directly. The formulation introduced here can be viewed as an extension of turbulence spreading to include the effect of spreading of cross-phase as well as turbulence intensity, combined in such a way to give the flux. The link between turbulence spreading and entropy production is highlighted. An extension of this formulation to general quasi-linear theory for the distribution function in the phase space of radial position and parallel velocity is also discussed.
Optical characterization of free electron concentration in heteroepitaxial InN layers using Fourier transform infrared spectroscopy and a 2 × 2 transfer-matrix algebra
Authors: Katsidis C. C. , Ajagunna A. O. , Georgakilas A.
Published: February 2013

Fourier Transform Infrared (FTIR) reflectance spectroscopy has been implemented as a non-destructive, non-invasive, tool for the optical characterization of a set of c-plane InN single heteroepitaxial layers spanning a wide range of thicknesses (30–2000 nm). The c-plane (0001) InN epilayers were grown by plasma-assisted molecular beam epitaxy (PAMBE) on GaN(0001) buffer layers which had been grown on Al2O3(0001) substrates. It is shown that for arbitrary multilayers with homogeneous anisotropic layers having their principal axes coincident with the laboratory coordinates, a 2 × 2 matrix algebra based on a general transfer-matrix method (GTMM) is adequate to interpret their optical response. Analysis of optical reflectance in the far and mid infrared spectral range has been found capable to discriminate between the bulk, the surface and interface contributions of free carriers in the InN epilayers revealing the existence of electron accumulation layers with carrier concentrations in mid 1019 cm−3 at both the InN surface and the InN/GaN interface. The spectra could be fitted with a three-layer model, determining the different electron concentration and mobility values of the bulk and of the surface and the interface electron accumulation layers in the InN films. The variation of these values with increasing InN thickness could be also sensitively detected by the optical measurements. The comparison between the optically determined drift mobility and the Hall mobility of the thickest sample reveals a value of rH = 1.49 for the Hall factor of InN at a carrier concentration of 1.11 × 1019 cm−3 at 300° Κ.
Kinetic models of two-dimensional plane and axially symmetric current sheets: Group theory approach
Authors: Vasko I. Y. , Artemyev A. V. , Popov V. Y. , Malova H. V.
Published: February 2013

In this paper, we present new class of solutions of Grad-Shafranov-like (GS-like) equations, describing kinetic plane and axially symmetric 2D current sheets. We show that these equations admit symmetry groups only for Maxwellian and κ-distributions of charged particles. The admissible symmetry groups are used to reduce GS-like equations to ordinary differential equations for invariant solutions. We derive asymptotes of invariant solutions, while invariant solutions are found analytically for the κ-distribution with κ=7/2. We discuss the difference of obtained solutions from equilibria widely used in other studies. We show that κ regulates the decrease rate of plasma characteristics along the current sheet and determines the spatial distribution of magnetic field components. The presented class of plane and axially symmetric (disk-like) current sheets includes solutions with the inclined neutral plane.
Optimal conditions for shock ignition of scaled cryogenic deuterium–tritium targets
Authors: Lafon M. , Ribeyre X. , Schurtz G.
Published: February 2013

Within the framework of the shock-ignition (SI) scheme, ignition conditions are reached following the separation of the compression and heating phases. First, the shell is compressed at a sub-ignition implosion velocity; then an intense laser spike is launched at the end of the main drive, leading to the propagation of a strong shock through the precompressed fuel. The minimal laser energy required for ignition of scaled deuterium–tritium (DT) targets is assessed by calculations. A semi-empiric model describing the ignitor shock generation and propagation in the fuel assembly is defined. The minimal power needed in the laser spike pulse to achieve ignition is derived from the hydrodynamic model. Optimal conditions for ignition of scaled targets are explored in terms of laser intensity, shell-implosion velocity, and target scale range for the SI process. Curves of minimal laser requirements for ignition are plotted in the energy–power diagram. The most economic and reliable conditions for ignition of a millimeter DT target are observed in the 240- to 320-km/s implosion velocity range and for the peak laser intensity ranging from ∼2 × 1015 W/cm2 up to 5 × 1015 W/cm2. These optimal conditions correspond to shock-ignited targets for a laser energy of ∼250 kJ and a laser power of 100 to 200 TW. Large, self-ignited targets are particularly attractive by offering ignition at a lower implosion velocity and a reduced laser intensity than for conventional ignition. The SI scheme allows for the compression and heating phases of the high power laser energy research facility target to be performed at a peak laser intensity below 1016 W/cm2. A better control of parametric and hydrodynamic instabilities within the SI scheme sets it as an optimal and reliable approach to attain ignition of large targets.
Co-doping with antimony to control phosphorous diffusion in germanium
Authors: Tahini H. A. , Chroneos A. , Grimes R. W. , Schwingenschlögl U.
Published: February 2013

In germanium, phosphorous and antimony diffuse quickly and as such their transport must be controlled in order to design efficient n-typed doped regions. Here, density functional theory based calculations are used to predict the influence of double donor co-doping on the migration activation energies of vacancy-mediated diffusion processes. The migration energy barriers for phosphorous and antimony were found to be increased significantly when larger clusters involving two donor atoms and a vacancy were formed. These clusters are energetically stable and can lead to the formation of even larger clusters involving a number of donor atoms around a vacancy, thereby affecting the properties of devices.
Excitation intensity- and temperature-dependent photoluminescence in layered structured Tl2GaInSe2S2 crystals
Authors: Gasanly N. M.
Published: February 2013

Photoluminescence spectra of Tl2GaInSe2S2 layered crystals have been registered in the temperature range of 17–62 K and in the wavelength region of 525–690 nm. A broad visible photoluminescence band centered at 590 nm (2.10 eV) was observed at T = 17 K. Variation of emission band has been studied as a function of laser excitation intensity in the 0.1–55.7 mW cm−2 range. The analysis of the spectra reveals that the peak energy position changes with excitation intensity (blue shift). The radiative transitions from moderately deep donor level to shallow acceptor level were suggested to be responsible for the observed band. From X-ray powder diffraction study, the parameters of monoclinic unit cell of Tl2GaInSe2S2 were determined.
Heat-induced damping modification in yttrium iron garnet/platinum hetero-structures
Authors: Jungfleisch M. B. , An T. , Ando K. , Kajiwara Y. , Uchida K. , Vasyuchka V. I. , Chumak A. V. , Serga A. A. , Saitoh E. , Hillebrands B.
Published: February 2013

We experimentally demonstrate the manipulation of magnetization relaxation utilizing a temperature difference across the thickness of an yttrium iron garnet/platinum hetero-structure: the damping is either increased or decreased depending on the sign of the temperature gradient. This effect might be explained by a thermally induced spin torque on the magnetization precession. The heat-induced variation of the damping is detected by microwave techniques as well as by a DC voltage caused by spin pumping into the adjacent Pt layer and the subsequent conversion into a charge current by the inverse spin Hall effect.
Comparative study of tip cross-sections for efficient galloping energy harvesting
Authors: Yang Yaowen , Zhao Liya , Tang Lihua
Published: February 2013

This letter presents a comparative study of different tip cross-sections for small scale wind energy harvesting based on galloping phenomenon. A prototype device is fabricated with a piezoelectric cantilever and a tip body with various cross-section profiles (square, rectangle, triangle, and D-shape) and tested in a wind tunnel. Experimental results demonstrate the superiority of the square-sectioned tip for the low cut-in wind speed of 2.5 m/s and the high peak power of 8.4 mW. An analytical model is established and verified by the experimental results. It is recommended that the square section should be used for small wind galloping energy harvesters.
Highly (001)-oriented thin continuous L1 FePt film by introducing an FeOx cap layer
Authors: Liao Jung-Wei , Huang Kuo-Feng , Wang Liang-Wei , Tsai Wu-Chang , Wen Wei-Chih , Chiang Chao-Chien , Lin Hong-Ji , Chang Fan-Hsiu , Lai Chih-Huang
Published: February 2013

We demonstrate a thin and continuous L10 FePt film with a well-aligned (001) texture directly grown on Si || SiO2 substrates by introducing an FeOx cap layer. The agglomeration of capped FePt films is greatly suppressed by inhibiting the surface diffusion. This, in turn, yields a continuous and smooth film, which significantly promotes the (001) out-of-plane orientation and perpendicular anisotropy. The reduction of Fe oxides occurs during annealing, which not only promotes interdiffusion of Fe and Pt for L10 ordering but also removes the cap layer simultaneously. Therefore, additional etching for the cap layer is not required for further fabricating bit patterned media.
Promoting Private Sector Development in China: The Challenge of Building Institutional Capacity at the Local Level
Authors: Atherton Andrew , Smallbone David
Published: February 2013

China's rapid growth in recent decades can be attributed in large part to the emergence of a vibrant private sector, which now accounts for around three quarters of the economy. Despite government pronouncements in support of private small businesses, public policy and institutions to support private sector development have been slow to emerge and address their needs. However, many privately owned enterprises are in need of assistance, affected by internal capability constraints such as a lack of management and leadership skills and by an external environment that still privileges state-owned enterprises. Although policy makers may have had other policy priorities in the past, and private enterprises have been able to survive and grow without inputs of professional advice and support, we argue that in the future small and medium-sized enterprises in China will require appropriate and effective business support to continue to grow. In this context we consider two interventions designed to build institutional capacity to provide business support at a local level and the barriers to be overcome if an effective framework for state promotion of privately owned small businesses is to be established.
Reduction of nutrient losses with eroded sediments by post-fire soil stabilisation techniques
Authors: Gómez-Rey M. X. , Couto-Vázquez A. , García-Marco S. , Vega J. A. , González-Prieto S. J.
Published: February 2013

After an experimental fire in steep shrubland in a temperate–humid region (north-west Spain), the effects of two post-fire stabilisation treatments (grass seeding and straw mulching) on the chemical properties of eroded sediments, and the amount of nutrients lost with them, were evaluated relative to control burnt soil, over a period of 13 months. Total C and N concentrations, and δ13C, indicated that sediments were mainly contributed by charred plant and litter material. The highest concentrations of extractable base cations in the sediments occurred during the first 3 months following fire, especially for Na and K. As treatments had little or no effect on nutrient concentration in sediments, differences in nutrient losses were due to the 10-fold lower sediment production in mulching compared with other treatments. In control and seeding treatments, the accumulated amounts of nutrients lost with sediments were 989–1028 kg ha–1 (C), 77 kg ha–1 (N), 1.9–2.4 kg ha–1 (Ca), 0.9–1.1 kg ha–1 (Mg), 0.48–0.55 kg ha–1 (NH4+–N), 0.39–0.56 kg ha–1 (K), 0.19–0.34 kg ha–1 (Na) and <0.1 kg ha–1 (P and NO3––N). These values accounted for 22–25% (total C and N) and 5–12% (NH4+–N, Ca, P and Mg) of available nutrients in ash, and 1.0–2.4% of those in ash+topsoil. As nutrient and sediment losses were strongly correlated, the reduction of the latter by mulching application leads to an effective decrease of post-fire nutrient losses.
Intratumor heterogeneity in human glioblastoma reflects cancer evolutionary dynamics
Authors: Sottoriva Andrea , Spiteri Inmaculada , Piccirillo Sara G. M. , Touloumis Anestis , Collins V. Peter , Marioni John C. , Curtis Christina , Watts Colin , Tavaré Simon
Published: February 2013

Glioblastoma (GB) is the most common and aggressive primary brain malignancy, with poor prognosis and a lack of effective therapeutic options. Accumulating evidence suggests that intratumor heterogeneity likely is the key to understanding treatment failure. However, the extent of intratumor heterogeneity as a result of tumor evolution is still poorly understood. To address this, we developed a unique surgical multisampling scheme to collect spatially distinct tumor fragments from 11 GB patients. We present an integrated genomic analysis that uncovers extensive intratumor heterogeneity, with most patients displaying different GB subtypes within the same tumor. Moreover, we reconstructed the phylogeny of the fragments for each patient, identifying copy number alterations in
EGFR
and
CDKN2A/B/p14ARF
as early events, and aberrations in
PDGFRA
and
PTEN
as later events during cancer progression. We also characterized the clonal organization of each tumor fragment at the single-molecule level, detecting multiple coexisting cell lineages. Our results reveal the genome-wide architecture of intratumor variability in GB across multiple spatial scales and patient-specific patterns of cancer evolution, with consequences for treatment design.
Histone H2B ubiquitin ligase RNF20 is required for
MLL
-rearranged leukemia
Authors: Wang Eric , Kawaoka Shinpei , Yu Ming , Shi Junwei , Ni Ting , Yang Wenjing , Zhu Jun , Roeder Robert G. , Vakoc Christopher R.
Published: February 2013

Mixed-lineage leukemia (
MLL
) fusions are potent oncogenes that initiate aggressive forms of acute leukemia. As aberrant transcriptional regulators, MLL-fusion proteins alter gene expression in hematopoietic cells through interactions with the histone H3 lysine 79 (H3K79) methyltransferase DOT1L. Notably, interference with MLL-fusion cofactors like DOT1L is an emerging therapeutic strategy in this disease. Here, we identify the histone H2B E3 ubiquitin ligase ring finger protein 20 (RNF20) as an additional chromatin regulator that is necessary for MLL-fusion–mediated leukemogenesis. Suppressing the expression of Rnf20 in diverse models of
MLL
-rearranged leukemia leads to inhibition of cell proliferation, under tissue culture conditions as well as in vivo. Rnf20 knockdown leads to reduced expression of MLL-fusion target genes, effects resembling Dot1l inhibition. Using ChIP-seq, we found that H2B ubiquitination is enriched in the body of MLL-fusion target genes, correlating with sites of H3K79 methylation and transcription elongation. Furthermore, Rnf20 is required to maintain local levels of H3K79 methylation by Dot1l at
Hoxa9
and
Meis1
. These findings support a model whereby cotranscriptional recruitment of Rnf20 at MLL-fusion target genes leads to amplification of Dot1l-mediated H3K79 methylation, thereby rendering leukemia cells dependent on Rnf20 to maintain their oncogenic transcriptional program.
Introduction.
Authors: Schaffer B. , Wolstenholme B. N. , Whiley A. W.
Published: February 2013

This chapter focuses on the evolutionary aspects and production of avocados around the world. The adaptation of avocados to the demands of modern orchard practices is also discussed.
A new way to protect privacy in large-scale genome-wide association studies
Authors: Kamm Liina , Bogdanov Dan , Laur Sven , Vilo Jaak
Published: February 2013

Motivation: Increased availability of various genotyping techniques has initiated a race for finding genetic markers that can be used in diagnostics and personalized medicine. Although many genetic risk factors are known, key causes of common diseases with complex heritage patterns are still unknown. Identification of such complex traits requires a targeted study over a large collection of data. Ideally, such studies bring together data from many biobanks. However, data aggregation on such a large scale raises many privacy issues.

Results: We show how to conduct such studies without violating privacy of individual donors and without leaking the data to third parties. The presented solution has provable security guarantees.

Contact:  jaak.vilo@ut.ee

Supplementary information:  Supplementary data are available at Bioinformatics online.
GalaxyGemini: a web server for protein homo-oligomer structure prediction based on similarity
Authors: Lee Hasup , Park Hahnbeom , Ko Junsu , Seok Chaok
Published: February 2013

Summary: A large number of proteins function as homo-oligomers; therefore, predicting homo-oligomeric structure of proteins is of primary importance for understanding protein function at the molecular level. Here, we introduce a web server for prediction of protein homo-oligomer structure. The server takes a protein monomer structure as input and predicts its homo-oligomer structure from oligomer templates selected based on sequence and tertiary/quaternary structure similarity. Using protein model structures as input, the server shows clear improvement over the best methods of CASP9 in predicting oligomeric structures from amino acid sequences.

Availability:  http://galaxy.seoklab.org/gemini.

Contact:  chaok@snu.ac.kr

Supplementary information:  Supplementary data are available at Bioinformatics online.
European lobster subpopulations from limited adult movements and larval retention
Authors: Øresland Vidar , Ulmestrand Mats
Published: February 2013

Øresland, V., and Ulmestrand, M. 2013. European lobster subpopulations from limited adult movements and larval retention. – ICES Journal of Marine Science, 70: 532–539. Adults and larvae of the European lobster, Homarus gammarus, were studied within and around the Swedish Kåvra lobster reserve (2.2 km2). Tagging of 4016 lobsters within the reserve showed that the lobsters have limited movement out of the reserve. Only 58 lobsters (1.4% of all tagged lobsters) were recaptured ≥1 km from the reserve and 5658 recaptures were obtained inside the reserve. Light trap catches showed that stage 1 larvae had a peak occurrence during <2 weeks, in early August, 2007–2009. The mean depth distribution of stage 1 larvae was 16 m and very few larvae were found in the low saline surface layer. No later stages were found in horizontal net tows. The lobsters inside the reserve provided stage 1 larvae to the nearby area. A persistent retention of water masses was found at 16-m depth (below the sharp halocline) in the area (16 km2) around the reserve using IMR GPS Current Drifters. In sharp contrast, surface drifters showed strong offshore and inshore movements. The Swedish archipelago might harbour many lobster and other decapod subpopulations, if the larval stages occur in a large proportion below the sharp halocline and if adult movements are limited.
Managing New Oral Anticoagulants in the Perioperative and Intensive Care Unit Setting
Authors: Levy Jerrold H. , Faraoni David , Spring Jenna L. , Douketis James D. , Samama Charles M.
Published: February 2013

Managing patients in the perioperative setting receiving novel oral anticoagulation agents for thromboprophylaxis or stroke prevention with atrial fibrillation is an important consideration for clinicians. The novel oral anticoagulation agents include direct Factor Xa inhibitors rivaroxaban and apixaban, and the direct thrombin inhibitor dabigatran. In elective surgery, discontinuing their use is important, but renal function must also be considered because elimination is highly dependent on renal elimination. If bleeding occurs in patients who have received these agents, common principles of bleeding management as with any anticoagulant (including the known principles for warfarin) should be considered. This review summarizes the available data regarding the management of bleeding with novel oral anticoagulation agents. Hemodialysis is a therapeutic option for dabigatran-related bleeding, while in vitro studies showed that prothrombin complex concentrates are reported to be useful for rivaroxaban-related bleeding. Additional clinical studies are needed to determine the best method for reversal of the novel oral anticoagulation agents when bleeding occurs.
Invasive disease caused by Haemophilus parainfluenzae III in a child with uropathy
Authors: Ariza Jiménez A. B. , Moreno-Perez D. , Núñez Cuadros E. , Urda Cardona A.
Published: February 2013

Urinary tract infections (UTIs) caused by Haemophilus parainfluenzae represent a very small percentage of this kind of pathology in children, and it has scarcely been described in the medical literature. According to previous studies of over 800 urine samples in children under 15 years old, a decrease of 50 % (from 0.13 % to 0.07 %) is estimated in its occurrence over the last two decades. This can be explained by the early detection of UTIs and their early empirical treatment, because this micro-organism shows high sensitivity to antibiotics. Also, the culture media in which this bacterium grows are not included in most current protocols. Here we report a case of a UTI caused by H. parainfluenzae in a 4-year-old boy.
High-throughput single-nucleotide polymorphism-based typing of shared Pseudomonas aeruginosa strains in cystic fibrosis patients using the Sequenom iPLEX platform
Authors: Syrmis Melanie W. , Moser Ralf J. , Kidd Timothy J. , Hunt Priscilla , Ramsay Kay A. , Bell Scott C. , Wainwright Claire E. , Grimwood Keith , Nissen Michael D. , Sloots Theo P. , Whiley David M.
Published: February 2013

Shared strains of Pseudomonas aeruginosa are now well recognized in people with cystic fibrosis (CF), and suitable P. aeruginosa laboratory typing tools are pivotal to understanding their clinical significance and guiding infection control policies in CF clinics. We therefore compared a single-nucleotide polymorphism (SNP)-based typing method using Sequenom iPLEX matrix-assisted laser desorption ionization with time-of-flight mass spectrometry (MALDI-TOF MS) with typing methods used routinely by our laboratory. We analysed 617 P. aeruginosa isolates that included 561 isolates from CF patients collected between 2001 and 2009 in two Brisbane CF clinics and typed previously by enterobacterial repetitive intergenic consensus (ERIC)-PCR, as well as 56 isolates from non-CF patients analysed previously by multilocus sequence typing (MLST). The isolates were tested using a P. aeruginosa Sequenom iPLEX MALDI-TOF (PA iPLEX) method comprising two multiplex reactions, a 13-plex and an 8-plex, to characterize 20 SNPs from the P. aeruginosa housekeeping genes acsA, aroE, guaA, mutL, nuoD, ppsA and trpE. These 20 SNPs were employed previously in a real-time format involving 20 separate assays in our laboratory. The SNP analysis revealed 121 different SNP profiles for the 561 CF isolates. Overall, there was at least 96 % agreement between the ERIC-PCR and SNP analyses for all predominant shared strains among patients attending our CF clinics: AUST-01, AUST-02 and AUST-06. For the less frequently encountered shared strain AUST-07, 6/25 (24 %) ERIC-PCR profiles were misidentified initially as AUST-02 or as unique, illustrating the difficulty of gel-based analyses. SNP results for the 56 non-CF isolates were consistent with previous MLST data. Thus, the PA iPLEX format provides an attractive high-throughput alternative to ERIC-PCR for large-scale investigations of shared P. aeruginosa strains.
Breakpoint profiling of 64 cancer genomes reveals numerous complex rearrangements spawned by homology-independent mechanisms
Authors: Malhotra Ankit , Lindberg Michael , Faust Gregory G. , Leibowitz Mitchell L. , Clark Royden A. , Layer Ryan M. , Quinlan Aaron R. , Hall Ira M.
Published: February 2013

Tumor genomes are generally thought to evolve through a gradual accumulation of mutations, but the observation that extraordinarily complex rearrangements can arise through single mutational events suggests that evolution may be accelerated by punctuated changes in genome architecture. To assess the prevalence and origins of complex genomic rearrangements (CGRs), we mapped 6179 somatic structural variation breakpoints in 64 cancer genomes from seven tumor types and screened for clusters of three or more interconnected breakpoints. We find that complex breakpoint clusters are extremely common: 154 clusters comprise 25% of all somatic breakpoints, and 75% of tumors exhibit at least one complex cluster. Based on copy number state profiling, 63% of breakpoint clusters are consistent with being CGRs that arose through a single mutational event. CGRs have diverse architectures including focal breakpoint clusters, large-scale rearrangements joining clusters from one or more chromosomes, and staggeringly complex chromothripsis events. Notably, chromothripsis has a significantly higher incidence in glioblastoma samples (39%) relative to other tumor types (9%). Chromothripsis breakpoints also show significantly elevated intra-tumor allele frequencies relative to simple SVs, which indicates that they arise early during tumorigenesis or confer selective advantage. Finally, assembly and analysis of 4002 somatic and 6982 germline breakpoint sequences reveal that somatic breakpoints show significantly less microhomology and fewer templated insertions than germline breakpoints, and this effect is stronger at CGRs than at simple variants. These results are inconsistent with replication-based models of CGR genesis and strongly argue that nonhomologous repair of concurrently arising DNA double-strand breaks is the predominant mechanism underlying complex cancer genome rearrangements.
Issues challenging future Thai elder care by women and family
Authors: Narknisorn Boontarika , Kusakabe Kyoko
Published: February 2013

Purpose

This article aims to present the issues that challenge women and family to provide elder care. It also shows weaknesses of policy that strongly attaches to traditional expectation and does not adapt to actual changes by presenting an example of Thailand.

Design/methodology/approach

The review of secondary data.

Findings

Rapid growth of old age population, fewer number of children, changes in women's roles and women's employment, migration, family and societal changes challenge Thai traditional role of women and family as the main elder care providers. Academicians and policy makers are aware of these challenges, but Thai National Policy on Aging still puts responsibilities back to family.

Research limitations/implications

A limitation is that information is based on available literature. Implication is to stimulate an ongoing research to give feedback to policy.

Practical implications

A top‐down approach can create the gap between policy ideology and reality. This article provides argument information to close the gap and improve policy that better corresponds with actual social changes and life condition of older people, women and family.

Social implications

This article urges an understanding that family, women and older people are not homogeneous.

Originality/value

This article gives reasons why policy on aging needs to detach from traditional expectation, seriously prepare elder care that corresponds with social changes and provide elder care by family and non‐family.