bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency‐agile Butler matrix with good interference suppression for multiple radio wireless platforms
Authors: Cheng Yu Jian , He Wen Bin , Weng Cheng Xiang , Fan Yong
Published: July 2013

In this study, a frequency‐agile Butler matrix is proposed and designed to operate from 1.92 to 2.7 GHz, which can therefore be used in several different wireless applications, including the universal mobile telecommunications system, the wireless fidelity (WiFi) and the world interoperability for microwave access. Measured results show that the amplitude imbalance of this Butler matrix is less than 2 dB, while the average insertion loss is less than 2.7 dB. Meantime, the return loss is better than 15 dB, together with the isolation between input ports better than 17 dB. In addition, an antenna array fed by this frequency‐agile Butler matrix is investigated. It exhibits good out‐of‐band suppression especially at the lower band, showing the advantages over other multiband and wideband counterparts. For example, when the multiple beam antenna operates at 1.95 GHz, the received power levels of 2.14, 2.35, 2.44 and 2.6 GHz are only 0.02, 0.46, 0.19 and 0.87%, respectively, compared with the reference received power level of 1.95 GHz.
Clutter suppression for multichannel wide‐area surveillance systems via Kalman filtering
Authors: Yan He , Zheng MingJie , Wang Robert , Gao CanGuan , Deng YunKai , Wang ChunLe
Published: July 2013

Reduced‐dimension space‐time adaptive processing (STAP) techniques are often used in multichannel wide‐area surveillance airborne systems to suppress ground clutter. However, it is well known that their performance degrades to some extent in non‐homogeneous environments because of inaccurate estimation of the interference covariance matrix from secondary data. In this study, the authors propose an algorithm which applies Kalman filtering to suppress ground clutter based on the data model of radar echoes from multichannel wide‐area surveillance systems. Since the proposed algorithm does not need to estimate the interference covariance matrix, it has a major advantage when processing the data from non‐homogeneous environments. Simulated data from phased‐array multifunctional imaging radar (PAMIR) system and real data from an X‐band wide‐area surveillance system are used to validate the proposed algorithm. The results show that the new algorithm works well in both radar systems.
Spectrally interleaved multi‐carrier signals for radar network applications and multi‐input multi‐output radar
Authors: Sturm Christian , Sit Yoke Leen , Braun Martin , Zwick Thomas
Published: July 2013

A modification of the classical orthogonal frequency division multiplexing signals is discussed that allows for the creation of a set of perfectly orthogonal transmit signals sharing the same bandwidth. These signals can be employed for performing radar measurements with multiple transmitters being simultaneously active, for example, in radar networks or multi‐input multi‐output radar applications. Since all the signals of the individual transmitters occupy the full available bandwidth, no deterioration of the achievable range resolution occurs. This study comprises both the theoretical considerations as well as the verification simulations and measurements. A particular focus is on the requirements regarding the frequency and time synchronisation of the individual signals and their impact on the achievable performance. The influence of possible Doppler shifts is also considered. Finally, a performance comparison with classical code‐based multiple user access techniques is provided. The achieved results demonstrate that the proposed multi‐carrier waveforms clearly outperform the classical code‐based approach under realistic assumptions of synchronisation accuracy.
Tracking spawning objects
Authors: Mahler Ronald P.S. , Maroulas Vasileios
Published: July 2013

Many multi‐object tracking scenarios are complicated by the fact that an object of interest may spawn additional objects which, for some period of time, follow roughly the same trajectory as the original object and then fall away. The challenge is then to discriminate the original object from the spawned ancillaries in a timely fashion. This study proposes a solution to this problem based on the increasingly well‐known multi‐object track‐before‐detect algorithm called the cardinalised probability hypothesis density (CPHD) filter. Precisely, the authors assume zero false alarms (ZFA) in the CPHD filter, and apply the proposed scheme to linear and non‐linear simulation scenarios based on widely used object‐trajectory and sensor models. The authors have also demonstrated that a Gaussian mixture implementation of the ZFA‐CPHD filter (i) establishes stable estimates of object number, (ii) rapidly eliminates the ancillary objects and (iii) detects and accurately estimates the trajectory of the original object of interest.
Performance analysis for interference and noise canceller based on hypercomplex and spatio‐temporal‐polarisation processes
Authors: Tao Jian‐Wu
Published: July 2013

In this study, the problem of spatio‐temporal‐polarisation filtering based on hypercomplex processes is considered for an electromagnetic (EM) vector‐sensor array. The quaternion domain facilitates modelling and processing of four‐dimensional real signals (or two‐dimensional complex signals). Based on the quaternion model of linear symmetric array with two‐components EM vector‐sensors, an interference and noise canceller (INC) is presented for polarised signals. Then, the output signal to interference‐plus‐noise ratio (SINR) expression of INC is derived and its performance is analysed. The performance analysis reveal explicitly the fact that even though no separation between the direction of arrival (DOAs) of the desired signal and interference, the maximum value of output SINR can be obtained employing the orthogonality between the polarisations of the desired signal and interference. Simulation results show that if sample size N is large enough, the INC has larger output SINR and better robustness against the DOA mismatch.
Object identification based on filtering
Authors: Carroll Thomas L. , Rachford Frederic J.
Published: July 2013

The authors use an acoustic experiment to test a method for identifying radar or sonar targets based on information from the target's impulse response function. The new algorithm uses a long modulated pulse of relatively low resolution. Using concepts from the field of dynamics, the algorithm measures the similarity between a signal reflected from a target and a previously recorded reference. The authors conducted acoustic experiments with some simple objects to validate the algorithm, although the actual target identification method could be used for radar or sonar.
Theoretical approach for target detection and interference cancellation in passive radars
Authors: Masjedi Maryam , Moddares‐Hashemi Mahmood , Sadri Saeed
Published: July 2013

Many studies have been done so far based on the detection theory for target detection in active radars, but not for passive radars. Owing to some substantial differences, detection methods used in active radars do not lead to accurate results if applied to passive radars. So, in the current study, cancellation, detection and target parameter extraction are investigated for passive radar based on the detection theory. To do this, the passive radar hypothesis test is written in the form of a multiple composite test. Unknown parameters are estimated using maximum likelihood (ML) criterion for the achievement of generalised likelihood ratio test detection statistic and elimination of direct path and clutter that contain nuisance parameters. The required threshold is set so that the false alarm probability in each cell and each step would become a constant value. Also, since this method requires heavy computations, a method for the reduction of computational complexity is proposed. Finally, various detection methods in passive radars are compared using simulation to show the effectiveness of the suggested method.
Unsupervised classification of scattering behaviour using hybrid‐polarimetry
Authors: Panigrahi Rajib Kumar , Mishra Amit Kumar
Published: July 2013

This study presents an unsupervised algorithm for classification of scattering behaviour using hybrid‐polarimetric (hybrid‐Pol) data. The authors present a maximum likelihood estimation‐based unsupervised land cover classification algorithms for hybrid‐PolSAR image. This classification technique follows from the m − δ decomposition of hybrid‐Pol images. Introduction of a statistical treatment is the major contribution of the current algorithm. Performance of the hybrid‐Pol algorithms have been assessed with respect to Freeman–Durden decomposition of fully polarimetric SAR data. The authors have demonstrated, using two different datasets, that proposed algorithm not only gives better overall classification performance, it is also able to classify all the three major types of scattering mechanisms, whereas the existing hybrid‐PolSAR classification algorithms mostly fail to classify one of the scattering types.
Stereo‐synthetic aperture radar technique with bias correction to estimate terrain height
Authors: Lu Kung‐Yu , Kiang Jean‐Fu
Published: July 2013

A stereo‐synthetic aperture radar technique is proposed to estimate the terrain height of a target area. A systematic bias is observed to be in proportional to the height difference between the target area and the reference area. The estimated height error can be reduced to 1 m or less by correcting such bias.
Groenewold-Moyal product, α*-cohomology, and classification of translation-invariant non-commutative structures
Authors: Varshovi Amir Abbass
Published: July 2013

The theory of α*-cohomology is studied thoroughly and it is shown that in each cohomology class there exists a unique 2-cocycle, the harmonic form, which generates a particular Groenewold-Moyal star product. This leads to an algebraic classification of translation-invariant non-commutative structures and shows that any general translation-invariant non-commutative quantum field theory is physically equivalent to a Groenewold-Moyal non-commutative quantum field theory.
Bistable optical response of a nanoparticle heterodimer: Mechanism, phase diagram, and switching time
Authors: Nugroho Bintoro S. , Iskandar Alexander A. , Malyshev Victor A. , Knoester Jasper
Published: July 2013

We conduct a theoretical study of the bistable optical response of a nanoparticle heterodimer comprised of a closely spaced semiconductor quantum dot and a metal nanoparticle. The bistable nature of the response results from the interplay between the quantum dot's optical nonlinearity and its self-action (feedback) originating from the presence of the metal nanoparticle. The feedback is governed by a complex valued coupling parameter G = GR + iGI. We calculate the bistability phase diagram within the system's parameter space: spanned by GR, GI, and Δ, the latter being the detuning between the driving frequency and the transition frequency of the quantum dot. Additionally, switching times from the lower stable branch to the upper one (and vice versa) are calculated as a function of the intensity of the driving field. The conditions for bistability to occur can be realized, for example, for a heterodimer comprised of a closely spaced CdSe (or CdSe/ZnSe) quantum dot and a gold nanosphere.
Scanning tunneling microscopy investigation of self-assembled poly(3-hexylthiophene) monolayer
Authors: Ma Xiaojing , Guo Yan , Wang Tian , Su Zhaohui
Published: July 2013

Poly(3-hexylthiophene) (P3HT) monolayer has been investigated by scanning tunneling microscopy (STM). The monolayer was dominated by three kinds of ordered structure (I, II, and III), where the thiophene main chains lied parallel to one another, but high resolution STM images revealed that the arrangement of the hexyl side chains was different. In structure I, the hexyl side chains tilted at ∼60° with respect to the main chain, and the interchain distance (distance between two parallel neighboring backbones) was ∼1.41 nm. In structure II, the interchain distance was significantly larger at ∼1.52 nm, and the hexyl side chains were liquid-like. Structure III exhibited similar interchain distance as structure II, but the hexyl side chains were perpendicular to the main chain and were interdigitated. In addition to these ordered domains, individual poly(3-hexylthiophene) chains in various special configurations were observed, and their unfolding into more stable structures was tracked by dynamic STM, which provides evidence that P3HT is a relatively flexible polymer.
Structure formation of surfactant membranes under shear flow
Authors: Shiba Hayato , Noguchi Hiroshi , Gompper Gerhard
Published: July 2013

Shear-flow-induced structure formation in surfactant-water mixtures is investigated numerically using a meshless-membrane model in combination with a particle-based hydrodynamics simulation approach for the solvent. At low shear rates, uni-lamellar vesicles and planar lamellae structures are formed at small and large membrane volume fractions, respectively. At high shear rates, lamellar states exhibit an undulation instability, leading to rolled or cylindrical membrane shapes oriented in the flow direction. The spatial symmetry and structure factor of this rolled state agree with those of intermediate states during lamellar-to-onion transition measured by time-resolved scatting experiments. Structural evolution in time exhibits a moderate dependence on the initial condition.
Pseudopotentials for correlated electron systems
Authors: Trail J. R. , Needs R. J.
Published: July 2013

A scheme is developed for creating pseudopotentials for use in correlated-electron calculations. Pseudopotentials for the light elements H, Li, Be, B, C, N, O, and F, are reported, based on data from high-level quantum chemical calculations. Results obtained with these correlated electron pseudopotentials (CEPPs) are compared with data for atomic energy levels and the dissociation energies, molecular geometries, and zero-point vibrational energies of small molecules obtained from coupled cluster single double triple calculations with large basis sets. The CEPPs give better results in correlated-electron calculations than Hartree-Fock-based pseudopotentials available in the literature.
Thickness dependence of the growth of magnetron-sputtered TiO2 films studied by Raman and optical transmittance spectroscopy
Authors: Mukherjee S. K. , Mergel D.
Published: July 2013

Thin sputtered films of TiO2 of various thicknesses are characterized by their strain along the crystalline c−axis. The Raman B1g 519 cm−1 mode experiences a strong blue shift, whereas the Eg 144 cm−1 peak is at the standard position for all samples. The Raman intensity of the prominent Eg 144 cm−1 peak increases upon annealing at 300 °C, contrary to the integral intensity of XRD reflexes which remains constant. The half−width of the Eg 144 cm−1 peak is determined by the crystallite size. Dielectric modelling of the optical transmittance spectra indicates, for all samples, the existence of defect states leading to transitions 0.3−0.5 eV lower than the band gap. The growth process becomes stationary for a film thickness above 100 nm for rf−sputtered and above 200 nm for dc−sputtered films.
Shock adhesion test for composite bonded assembly using a high pulsed power generator
Authors: Gay E. , Berthe L. , Buzaud E. , Boustie M. , Arrigoni M.
Published: July 2013

In a context of the rising use of composite assemblies in aeronautic or defense fields, the assessment of their strength is a key issue. The method developed in this study attempts to provide solutions. A shock adhesion test based on short compressive loads, obtained by a high pulsed power generator, is proposed as a proof test to ensure the quality of composite bonded assemblies. A calibrated load induces a local tensile stress able to damage the bond interface. The high pulsed power source is the GEnerateur de Pression Isentropique device (Isentropic Pressure Generator), used to generate the required stresses, with a 450 ns pulse duration to test assemblies above the mm thickness range. The understanding of the mechanisms of wave propagation and tensile stress generation within these multilayer assemblies are scientific challenges. The ability of the technique to induce a tensile stress able to disbond the laminates and the assemblies is demonstrated. This paper details the response of carbon epoxy laminates and their bonded assemblies to a shock loading near the damage threshold.
Adiabatic measurements of magneto-caloric effects in pulsed high magnetic fields up to 55 T
Authors: Kihara T. , Kohama Y. , Hashimoto Y. , Katsumoto S. , Tokunaga M.
Published: July 2013

Magneto-caloric effects (MCEs) measurement system in adiabatic condition is proposed to investigate the thermodynamic properties in pulsed magnetic fields up to 55 T. With taking the advantage of the fast field-sweep rate in pulsed field, adiabatic measurements of MCEs were carried out at various temperatures. To obtain the prompt response of the thermometer in the pulsed field, a thin film thermometer is grown directly on the sample surfaces. The validity of the present setup was demonstrated in the wide temperature range through the measurements on Gd at about room temperature and on Gd3Ga5O12 at low temperatures. The both results show reasonable agreement with the data reported earlier. By comparing the MCE data with the specific heat data, we could estimate the entropy as functions of magnetic field and temperature. The results demonstrate the possibility that our approach can trace the change in transition temperature caused by the external field.
On a solution of the Schrödinger equation with a hyperbolic double-well potential
Authors: Downing C. A.
Published: July 2013

We report a solution of the one-dimensional Schrödinger equation with a hyperbolic double-well confining potential via a transformation to the so-called confluent Heun equation. We discuss the requirements on the parameters of the system in which a reduction to confluent Heun polynomials is possible, representing the wavefunctions of bound states.
Broadband absorption enhancement via light trapping in periodically patterned polymeric solar cells
Authors: Rumbak Ma'ayan , Visoly-Fisher Iris , Shikler Rafi
Published: July 2013

Improved absorption is needed for thin-film organic solar cells to increase charge generation and/or reduce the thickness of the organic active film. Absorption enhancement by light trapping in a photonic crystal (PC) can be used to enhance the absorption in a patterned photo-active polymer blend. We used the finite difference time domain (FDTD) method to study the effect of combining the PC with different vertical layer configurations, including a hole transporting flash layer, used for charge separation and for increasing the photo-voltage, and a reflective metallic back electrode. The model was applied to P3HT:PCBM and pBBTDPP2:PCBM blends as the active materials, to examine the effect of different absorption spectra on the results. We found that the combination of PC and a reflector electrode is synergistic for enhancing the absorption in such devices, while the effect of the flash layer is minor. The combination of lateral and vertical reflections by the PC and the reflector, respectively, results in significant light scattering and enhancement of the absorption in a wide range of wavelengths. An increase of 30% to 60% (depending on the active material) in the number of absorbed photons of the solar spectrum was calculated compared to un-patterned blends. Broadband absorption enhancement in a realistic cell configuration is expressed as absorption enhancement of solar photons in a wide range of PC periods, i.e., the presence of periodic structuring is more important for absorption enhancement of the solar irradiation than the dimension of its period.
Domain walls in ring-shaped nanowires under rotating applied fields
Authors: Negoita Madalina , Hayward Thomas J. , Miller James A , Allwood Dan A.
Published: July 2013

We present a study of the motion of domain walls confined to 1D propagating energy minima in ferromagnetic nanowires. The energy minima are defined by the combination of the geometry of a ring-shaped planar nanowire and the influence of an external magnetic field, and may be controllably propagated via rotation of this field. Focused magneto-optic Kerr effect measurements are used to characterize the walls' behavior at a range of field amplitudes and frequencies. Combining these measurements with simple models allows us to demonstrate that the domain walls propagate by thermally assisted “hopping” between defect sites and that the relative smoothness of their motion can be controlled by variation of the applied field strength. Frequency-domain analysis indicates that the nanowires retain domain wall structure, rather than form quasi-saturated states, over a large range of applied magnetic fields and including fields that result in smooth wall motion. Our results are important to applications where tight control of domain wall position takes precedent over speed, for example, where domain walls are used to trap and transport magnetized particles.
Transient bow shock around a cylinder in a supersonic dusty plasma
Authors: Meyer John K. , Merlino Robert L.
Published: July 2013

Visual observations of the formation of a bow shock in the transient supersonic flow of a dusty plasma incident on a biased cylinder are presented. The bow shock formed when the advancing front of a streaming dust cloud was reflected by the obstacle. After its formation, the density jump of the bow shock increased as it moved upstream of the obstacle. A physical picture for the formation of the electrohydrodynamic bow shock is discussed.
Effects of strain on the electrical properties of silicon carbide
Authors: Steel Fiona M. , Tuttle Blair R. , Shen Xiao , Pantelides Sokrates T.
Published: July 2013

We use density functional calculations to elucidate the effects of strain on the electronic properties of 4H-SiC. Both compressive and tensile uniaxial strain result in a smaller energy gap and splitting of the conduction band valleys. Compared to compressive strain, tensile strain results in larger valley splitting and larger changes to the electron effective masses. For strain larger than 1.5%, in one hexagonal direction, the important conductivity mass can be reduced by more than 50%. For biaxial tensile strain, we also observe effective mass changes similar to the uniaxial results.
Role of non-collinear polarizer layer in spin transfer torque switching processes
Authors: You Chun-Yeol , Jung Myung-Hwa
Published: July 2013

We recently reported that spin transfer torque switching current density is very sensitive to the junction sizes and the exchange stiffness constants of the free layer, based on micromagnetic simulations. The results are very complicated and far from the simple macro-spin model because of the non-coherent spin switching processes. The dependence of switching current density on junction sizes and the exchange stiffness constants becomes systematic when we employ the non-collinear polarizer layer. We found that the non-collinear polarizer layer enhances the coherency of the spin dynamics by breaking symmetric spin configurations and causes noticeable reductions in the switching current density.
Characterization of reactively sputtered molybdenum oxide films for solar cell application
Authors: Simchi H. , McCandless B. E. , Meng T. , Boyle J. H. , Shafarman W. N.
Published: July 2013

Molybdenum oxide (MoO3) thin films were prepared via Radio Frequency (RF) sputtering at different ambient composition and post-deposition annealing. The effects on the structural, optical, and surface properties of the deposited films were investigated. The ambient oxygen concentration O2/(O2 + Ar) was varied from 10% to 100% at 10 mTorr. Post deposition anneals were performed in Ar at 300–500 °C. The films were analyzed using glancing incidence x-ray diffraction (GIXRD), UV/Vis/NIR spectrophotometry, and x-ray photoelectron spectroscopy (XPS). As-deposited films have amorphous structures, independent of the oxygen partial pressure. Annealing at 300 °C in air resulted in crystallization of the molybdenum oxide films to the monoclinic β-MoO3 phase. Samples annealed at 400 and 500 °C were identified as pure orthorhombic α-MoO3 phase with (020) preferred orientation. High resolution XPS studies showed the presence of Mo6+ (MoO3) and Mo5+ (Mo4O11) oxidation states at the surface of as deposited and low temperature (300 °C) annealed films, and the Mo6+ to Mo5+ did not change much with deposition oxygen partial pressure. Annealing at 400–500 °C suppressed the oxygen deficiency at the surface, resulting in films with composition close to stoichiometric phases. UV/Vis/NIR spectrophotometry revealed that all films have a high optical transmittance (>80%) in the visible range, followed by a steep drop at λ ≈ 400 nm indicating a strong absorption due to band-to-band transition. Increasing the oxygen partial pressure had no significant effect on optical transmittance of the films, and the bandgaps in the range of 2.6 eV to 2.9 eV were obtained. Annealing at 300 °C had a negligible effect on the optical properties of the MoO3 films, but samples annealed at 400 °C and 500 °C exhibited wider bandgaps within the range of 3.1–3.4 eV.
Design of solar pond for water preheating used in the copper cathodes washing at a mining operation at Sierra Gorda, Chile
Authors: Garrido F. , Vergara J.
Published: July 2013

The Chilean copper industry is increasingly dependent on coal-generated electricity and diesel fuel for high altitude mining operations. The associated greenhouse gas emission expansion needs to be moderated, moving away from polluting imported energy sources. As an option, solar thermal energy is breaking through in mining processes, and several companies plan to evaluate the application of ponds among potential technologies. In this work, we propose the studied the performance of solar ponds to preheat water to wash the copper cathodes in a mine located in Sierra Gorda aiming to reduce fuel consumption and combustion emissions. The outcome was a dual array of solar ponds with an effective collecting area of 23 240 m2 and a 1.8 m thick density gradient to prevent heat convection. The ponds could deliver up to 12 300 MW h/year on site, reducing the annual diesel demand by 77% with a collecting efficiency of 24%, avoiding 3300 tonnes of CO2, thus reducing the cost of the thermal kilowatt-hour by 37%. Future work may include the construction of an instrumented pilot pond and three-dimensional modeling.
Modal “self-coupling” as a sensitive probe for nanomechanical detection
Authors: Defoort M. , Lulla K. J. , Blanc C. , Bourgeois O. , Collin E. , Armour A. D.
Published: July 2013

We present a high-sensitivity measurement technique for mechanical nanoresonators. Due to intrinsic nonlinear effects, different flexural modes of a nanobeam can be coupled while driving each of them on resonance. This mode-coupling scheme is dispersive and one mode resonance shifts with respect to the motional amplitude of the other. The same idea can be implemented on a single mode, exciting it with two slightly detuned signals. This two-tone scheme is used here to measure the resonance lineshape of one mode through a frequency shift in the response of the device. The method acts as an amplitude-to-frequency transduction which ultimately suffers only from phase noise of the local oscillator used and of the nanomechanical device itself. We also present a theory which reproduces the data without free parameters.
Tunnel magnetoresistance effect and interface study in magnetic tunnel junctions using epitaxial Fe2CrSi Heusler alloy electrode
Authors: Wang Yu-Pu , Han Gu-Chang , Lu Hui , Qiu Jinjun , Yap Qi-Jia , Ji Rong , Teo Kie-Leong
Published: July 2013

We report the studies of magnetic tunnel junctions (MTJs) using epitaxially grown Fe2CrSi (FCS) as a bottom electrode. A tunnel magnetoresistance (TMR) ratio of 2.5% was obtained for MTJ at room temperature. The low TMR ratio is attributed to the oxidation of FCS at the interface with MgO barrier. With the insertion of 0.3 nm Mg layer between the FCS and MgO barrier layers, the TMR ratio increases to 8.1%. X-ray Photoelectron Spectroscopy results show that the FCS film is most likely terminated at Fe and Si atomic layers, which is found to be bonded to oxygen at the interface, while Cr remains at metallic state. Post-annealing effect shows that TMR first increases with annealing temperature (Ta) due to improvement in crystalline structure of MgO and top electrode and then decreases due to oxidation of the bottom electrode. The TMR finally disappears due to the depinning of top electrode induced by Mn diffusion at high Ta.
Growth and electrical properties of spin coated ultrathin ZrO2 films on silicon
Authors: Dutta Shankar , Pandey Akhilesh , Yadav Isha , Thakur O. P. , Kumar A. , Pal Ramjay , Chatterjee Ratnamala
Published: July 2013

Ultrathin (<50 nm) zirconium oxide (ZrO2) films are being intensively studied as high-k dielectrics for future metal-oxide-semiconductor (MOS) technology. In this paper, ultrathin ZrO2 films are deposited on silicon substrates by spin on deposition technique and annealed at 700 °C for different duration. The phase formation and morphological study have been performed by x-ray diffraction and scanning electron microscopy, respectively. Electrical properties of the films are investigated. The threshold voltages of the MOS structure were found to vary from −1.5 V to −2.5 V as the annealing time increases. The dielectric constants of the films are found to be 7.2–7.67 at 1 KHz. Leakage current of the films is found to increase with the annealing time. The dielectric breakdown field of the film is found to be 6.29–8.15 MV/cm.
Room temperature terahertz quantum cascade laser sources with 215 μW output power through epilayer-down mounting
Authors: Lu Q. Y. , Bandyopadhyay N. , Slivken S. , Bai Y. , Razeghi M.
Published: July 2013

We report room temperature terahertz (THz) quantum cascade laser sources with high power based on difference frequency generation. The device is Čerenkov phase matched and spectrally purified with an integrated dual-period distributed-feedback grating. Symmetric current injection and epilayer-down mounting of the device onto a patterned submount are used to improve the electrical uniformity and heat removal, respectively. The epilayer-down mounting also allows for THz anti-reflective coating to enhance the THz outcoupling efficiency. Single mode emission at 3.5 THz with a side-mode suppression ratio and output power up to 30 dB and 215 μW are obtained, respectively.
Kinase detection with gallium nitride based high electron mobility transistors
Authors: Makowski Matthew S. , Bryan Isaac , Sitar Zlatko , Arellano Consuelo , Xie Jinqiao , Collazo Ramon , Ivanisevic Albena
Published: July 2013

A label-free kinase detection system was fabricated by the adsorption of gold nanoparticles functionalized with kinase inhibitor onto AlGaN/GaN high electron mobility transistors (HEMTs). The HEMTs were operated near threshold voltage due to the greatest sensitivity in this operational region. The Au NP/HEMT biosensor system electrically detected 1 pM SRC kinase in ionic solutions. These results are pertinent to drug development applications associated with kinase sensing.
Tunable metamaterials based on split ring resonators and doped graphene
Authors: Vasić Borislav , Jakovljević Milka M. , Isić Goran , Gajić Radoš
Published: July 2013

We investigate electrically tunable split ring resonators (SRRs) obtained by coupling the SRRs with graphene in terahertz and near-infrared frequency range. Two different geometries are considered: SRRs on homogeneous graphene and SRRs with graphene patches inserted only in SRRs' gap. Graphene conductivity is tuned by changing its Fermi level. This gives tunable absorption in the graphene, which is strongly enhanced by large electric field in the vicinity of SRR resonances. As a result, SRR-graphene systems could be used as deeply subwavelength modulators with amplitude and phase tuning of the reflected field.
The impact of best practice health and husbandry interventions on smallholder cattle productivity in southern Cambodia
Authors: Young J. R. , Rast L. , Suon S. , Bush R. D. , Henry L. A. , Windsor P. A.
Published: July 2013

Future food security has become a major global concern and is particularly important in the Greater Mekong Subregion where several countries have seen rapid urban economic development and increasing demand for red meat. In Cambodia, the majority of livestock producers are subsistence or semi-subsistence rural smallholder farmers using cattle as a source of protein, fertiliser, draught power, and asset storage. Potential income from smallholder cattle is limited by a range of factors that compromise productivity, including endemic diseases, poor nutrition, and lack of knowledge of husbandry techniques and marketing practices. To address the developing opportunities to improve rural incomes from cattle production in Cambodia, a 4-year longitudinal study was conducted to examine ‘best practice’ interventions that could improve productivity and profitability of cattle within smallholder farming systems. The study involved six villages from three provinces, with two villages in each of the provinces of Takeo, Kandal and Kampong Cham paired and designated as either high intervention (HI) or low intervention (LI). A best practice intervention program was introduced to the HI villages to develop the husbandry skills of farmers, including implementation of forage technology, disease prevention through vaccination for foot-and-mouth disease and haemorrhagic septicaemia, deworming, and education in nutrition, biosecurity, disease control, and marketing. Between April 2008 and February 2012, eight repeat-measures capturing data on animal health and production, including cattle weights used to evaluate the impact of interventions on average daily gains, were completed. Cattle in HI villages had significantly (P < 0.01) higher mean liveweight during the last three sampling periods, and average daily gains were 2.4 times higher than in cattle of the LI villages. This study provides evidence that best practice interventions resulted in improved cattle productivity, farmer knowledge and positive impacts on household income over time, offering a pathway that can address food security concerns and more rapidly alleviate rural poverty in the GMS.
Vulnerability to sexual violence and participation in sex work among high-end entertainment centre workers in Hunan Province, China
Authors: Kelvin Elizabeth A. , Sun Xiaoming , Mantell Joanne E. , Zhou Jianfang , Mao Jingshu , Peng Yanhui
Published: July 2013

Background
China has seen a proliferation of entertainment centres that are frequented by business people. Employees at these centres often are young, female rural-to-urban migrants who may be vulnerable to sexual violence and exploitation. Methods: Data for this study were collected using a self-administered survey among male and female employees in two high-end entertainment centres in Changsha, Hunan Province, China. We used logistic regression to examine predictors of violent and potentially exploitative experiences (partner violence, forced sex and transactional sex). Predictors included gender, ever having a same-sex partner, migration variables and employment characteristics. Results: Participants reported high levels of partner violence (16.0% ever and 9.0% in the past 3 months) and forced sex (13.9% ever and 5.5% in the past 3 months). Nineteen percent reported sex work in the past 3 months. In the multivariate regressions, ever having had a same-sex partner was associated with higher odds of ever having experienced partner violence (odds ratio (OR) = 7.8, P < 0.001), partner violence in the past 3 months (OR = 9.0, P < 0.001), ever having had transactional sex (OR = 6.0, P < 0.001) and transactional sex in the past 3 months (OR = 5.2, P = 0.001). After adjusting for transactional sex, the association between having had a same-sex partner and partner violence remained significant. Neither gender nor migration status was associated with any of the outcomes. Conclusion: High-end entertainment centre workers in China are at risk for sexual violence and should be targeted with employment-based interventions.
Recurrent and periodic points in dendritic Julia sets
Authors: Blokh Alexander
Published: July 2013

We relate periodic and recurrent points in dendritic Julia sets. This generalizes well-known results for interval dynamics.
On the Hausdorff dimension of Julia sets of some real polynomials
Authors: Levin Genadi , Zinsmeister Michel
Published: July 2013

We show that the supremum for

c
c

real of the Hausdorff dimension of the Julia set of the polynomial

z
↦

z
d

+
c

z\mapsto z^d+c

(

d
d

is an even natural number) is greater than

2
d

/

(
d
+
1
)

2d/(d+1)

.
Global 𝑊^{2,𝑝} estimates for the Monge-Ampère equation
Authors: Savin O.
Published: July 2013

We use a localization property of boundary sections for solutions to the Monge-Ampère equation and obtain global

W

2
,
p

W^{2,p}

estimates under natural assumptions on the domain and boundary data.
Induction and Suppression of PEN3 Focal Accumulation During Pseudomonas syringae pv. tomato DC3000 Infection of Arabidopsis
Authors: Xin Xiu-Fang , Nomura Kinya , Underwood William , He Sheng Yang
Published: July 2013

The pleiotropic drug resistance (PDR) proteins belong to the super-family of ATP-binding cassette (ABC) transporters. AtPDR8, also called PEN3, is required for penetration resistance of Arabidopsis to nonadapted powdery mildew fungi. During fungal infection, plasma-membrane-localized PEN3 is concentrated at fungal entry sites, as part of the plant's focal immune response. Here, we show that the pen3 mutant is compromised in resistance to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000. P. syringae pv. tomato DC3000 infection or treatment with a flagellin-derived peptide, flg22, induced strong focal accumulation of PEN3-green fluorescent protein. Interestingly, after an initial induction of PEN3 accumulation, P. syringae pv. tomato DC3000 but not the type-III-secretion-deficient mutant hrcC could suppress PEN3 accumulation. Moreover, transgenic overexpression of the P. syringae pv. tomato DC3000 effector AvrPto was sufficient to suppress PEN3 focal accumulation in response to flg22. Analyses of P. syringae pv. tomato DC3000 effector deletion mutants showed that individual effectors, including AvrPto, appear to be insufficient to suppress PEN3 accumulation when delivered by bacteria, suggesting a requirement for a combined action of multiple effectors. Collectively, our results indicate that PEN3 plays a positive role in plant resistance to a bacterial pathogen and show that focal accumulation of PEN3 protein may be a useful cellular response marker for the Arabidopsis–P. syringae interaction.
From human genome to cancer genome: The first decade
Authors: Wheeler David A. , Wang Linghua
Published: July 2013

The realization that cancer progression required the participation of cellular genes provided one of several key rationales, in 1986, for embarking on the human genome project. Only with a reference genome sequence could the full spectrum of somatic changes leading to cancer be understood. Since its completion in 2003, the human reference genome sequence has fulfilled its promise as a foundational tool to illuminate the pathogenesis of cancer. Herein, we review the key historical milestones in cancer genomics since the completion of the genome, and some of the novel discoveries that are shaping our current understanding of cancer.
Hypothesis-generating research and predictive medicine
Authors: Biesecker Leslie G.
Published: July 2013

Genomics has profoundly changed biology by scaling data acquisition, which has provided researchers with the opportunity to interrogate biology in novel and creative ways. No longer constrained by low-throughput assays, researchers have developed hypothesis-generating approaches to understand the molecular basis of nature—both normal and pathological. The paradigm of hypothesis-generating research does not replace or undermine hypothesis-testing modes of research; instead, it complements them and has facilitated discoveries that may not have been possible with hypothesis-testing research. The hypothesis-generating mode of research has been primarily practiced in basic science but has recently been extended to clinical-translational work as well. Just as in basic science, this approach to research can facilitate insights into human health and disease mechanisms and provide the crucially needed data set of the full spectrum of genotype–phenotype correlations. Finally, the paradigm of hypothesis-generating research is conceptually similar to the underpinning of predictive genomic medicine, which has the potential to shift medicine from a primarily population- or cohort-based activity to one that instead uses individual susceptibility, prognostic, and pharmacogenetic profiles to maximize the efficacy and minimize the iatrogenic effects of medical interventions.
High-Resolution Imaging of Cytoplasmic Ca2+ Dynamics in Arabidopsis Roots
Authors: Behera Smrutisanjita , Kudla Jörg
Published: July 2013

This protocol describes a method for imaging cytoplasmic Ca2+ dynamics in roots with high resolution using confocal laser scanning microscopy (CLSM). The Förster (fluorescence) resonance energy transfer (FRET)-based genetically modified Ca2+ indicator Yellow Cameleon YC3.6, stably expressed in plants under the control of the ubiquitin promoter UBQ10, is used for Ca2+ measurements. This protocol enables imaging of 5- to 7-d-old seedlings with high-magnification objectives (25×, 40×, and 63×).
Purification and Culture of Retinal Ganglion Cells from Rodents
Authors: Winzeler Alissa , Wang Jack T.
Published: July 2013

Here we describe methods for acute purification of retinal ganglion cells (RGCs) from rodent retina by immunopanning, followed by culture in serum-free medium. Though the method was initially established and verified with rats, we have included modifications for the purification of mouse RGCs. This protocol is written for isolation of cells from one litter of pups. All of the volumes and numbers of panning plates should be scaled according to the number of litters used, particularly for rat RGCs.
Creating an miR30-Based shRNA Vector
Authors: Chang Kenneth , Marran Krista , Valentine Amy , Hannon Gregory J.
Published: July 2013

Generating expression constructs for artificial microRNAs (miRNAs) is relatively straightforward. This protocol describes the creation of miR-30-based short hairpin RNA (shRNA) cassettes that are compatible with a number of standard vector systems. The principles outlined here can also be easily applied to other miRNA scaffolds or to simple snapback shRNAs. It is important to note that one must understand the processing of the artificial scaffold and be able to predict precisely the small RNAs that will be generated. Otherwise, no design principles can be effectively applied and the probability that any individual shRNA clone will work effectively will be greatly reduced.
Modelling interactions of toxicants and density dependence in wildlife populations
Authors: Schipper Aafke M. , Hendriks Harrie W. M. , Kauffman Matthew J. , Hendriks A. Jan , Huijbregts Mark A. J.
Published: July 2013

A major challenge in the conservation of threatened and endangered species is to predict population decline and design appropriate recovery measures. However, anthropogenic impacts on wildlife populations are notoriously difficult to predict due to potentially nonlinear responses and interactions with natural ecological processes like density dependence.

Here, we incorporated both density dependence and anthropogenic stressors in a stage‐based matrix population model and parameterized it for a density‐dependent population of peregrine falcons Falco peregrinus exposed to two anthropogenic toxicants [dichlorodiphenyldichloroethylene (DDE) and polybrominated diphenyl ethers (PBDEs)]. Log‐logistic exposure–response relationships were used to translate toxicant concentrations in peregrine falcon eggs to effects on fecundity. Density dependence was modelled as the probability of a nonbreeding bird acquiring a breeding territory as a function of the current number of breeders.

The equilibrium size of the population, as represented by the number of breeders, responded nonlinearly to increasing toxicant concentrations, showing a gradual decrease followed by a relatively steep decline. Initially, toxicant‐induced reductions in population size were mitigated by an alleviation of the density limitation, that is, an increasing probability of territory acquisition. Once population density was no longer limiting, the toxicant impacts were no longer buffered by an increasing proportion of nonbreeders shifting to the breeding stage, resulting in a strong decrease in the equilibrium number of breeders.

Median critical exposure concentrations, that is, median toxicant concentrations in eggs corresponding with an equilibrium population size of zero, were 33 and 46 μg g−1 fresh weight for DDE and PBDEs, respectively.

Synthesis and applications. Our modelling results showed that particular life stages of a density‐limited population may be relatively insensitive to toxicant impacts until a critical threshold is crossed. In our study population, toxicant‐induced changes were observed in the equilibrium number of nonbreeding rather than breeding birds, suggesting that monitoring efforts including both life stages are needed to timely detect population declines. Further, by combining quantitative exposure–response relationships with a wildlife demographic model, we provided a method to quantify critical toxicant thresholds for wildlife population persistence.
A Riddle Whose Answer is ‘Tort’: A Reassessment ofInternationalNewsServicevAssociatedPress
Authors: Wadlow Christopher
Published: July 2013

The decision of theUS SupremeCourt inInternationalNewsServicevAssociatedPress(1918) has variously been interpreted as recognising a ‘quasi‐property’ right in ‘valuable intangibles’, such as hot news; as turning on unjust enrichment; or as creating a novel tort of unfair competition by misappropriation. It is suggested that the case is more authentically understood as an incidental result of a process by which theSupremeCourt extended the boundaries of tort liability, and the corresponding scope of property protection, in a series of decisions against organised labour. The argument is pursued with reference to the prima facie tort theory ofOliverWendellHolmes, theAmerican ‘labour injunction’, and the labour law record of the author of the majority opinion inInternationalNews,JusticeMahlonPitney.
Criminal Labels, the European Convention on Human Rights and the Presumption of Innocence
Authors: Campbell Liz
Published: July 2013

This article explores whether the presumption of innocence is compromised by state declarations that a person is other than innocent, but which are neither predicated on nor equivalent to a criminal conviction. The task ultimately is threefold: in a descriptive sense, to establish the existing parameters of the presumption, in particular tracing its incremental expansion by the European Court of Human Rights; secondly, to present a normative argument as to what I believe the presumption should further entail, drawing on its recent doctrinal extension but moving beyond this in certain respects; and then finally to ascertain whether any labels or declarations by the state either before or absent a finding of criminal liability are problematic as regards the presumption of innocence as I propose it should be construed, and what ought to be done about this.