bluuebunny/crossref_metadata_2025 huggingface dataset:
Why diamond dimensions and electrode geometry are crucial for small photon beam dosimetry
Authors: Marsolat F. , Tromson D. , Tranchant N. , Pomorski M. , Bassinet C. , Huet C. , Derreumaux S. , Chea M. , Cristina K. , Boisserie G. , Buchheit I. , Marchesi V. , Gaudaire-Josset S. , Lisbona A. , Lazaro D. , Hugon R. , Bergonzo P.
Published: December 2015

Recent use of very small photon beams (down to 4 mm) in stereotactic radiotherapy requires new detectors to accurately determine the delivered dose. Diamond detectors have been presented in the literature as an attractive candidate for this application, due to their small detection volume and the diamond atomic number (Z = 6) which is close to water effective atomic number (Zeff ∼ 7.42). However, diamond exhibits a density 3.51 times greater than that of water and recent studies using Monte Carlo simulations have demonstrated the drawback of a high-density detector on small beam output factors. The current study focuses on geometrical parameters of diamond detector, namely, the diamond dimensions and the electrode geometry, in order to solve the dosimetric issues still observed in small photon beams with diamond detectors. To give better insights to these open questions, we have used both computational method and experimental analysis. This study highlighted that reducing diamond dimensions is crucial for small beam output factor measurements and to limit the influence of its high density. Furthermore, electrodes covering the whole diamond surface were essential for a dose rate independence of the diamond detector. The optimal dosimeter derived from this work presented small diamond dimensions of approximately 1 × 1 × 0.15 mm3, with diamond-like-carbon electrodes covering the whole diamond surface. A dose rate independence of this diamond detector (better than 0.5% over a wide range of dose rates available on a stereotactic dedicated facility) was obtained due to the electrode geometry. Concerning the output factor measurements, a good agreement (better than 1.1%) was observed between this carbon material detector and two types of passive dosimeters (LiF microcubes and EBT2 radiochromic films) for all beam sizes except the smallest field of 0.6 × 0.6 cm2 with a deviation of 2.6%. This new study showed the high performance of this diamond detector in small photon beams, in comparison with various commercially available passive and active dosimeters.
Radiative and non-radiative recombinations in tensile strained Ge microstrips: Photoluminescence experiments and modeling
Authors: Virgilio M. , Schroeder T. , Yamamoto Y. , Capellini G.
Published: December 2015

Tensile germanium microstrips are candidate as gain material in Si-based light emitting devices due to the beneficial effect of the strain field on the radiative recombination rate. In this work, we thoroughly investigate their radiative recombination spectra by means of micro-photoluminescence experiments at different temperatures and excitation powers carried out on samples featuring different tensile strain values. For sake of comparison, bulk Ge(001) photoluminescence is also discussed. The experimental findings are interpreted in light of a numerical modeling based on a multi-valley effective mass approach, taking in to account the depth dependence of the photo-induced carrier density and of the self-absorption effect. The theoretical modeling allowed us to quantitatively describe the observed increase of the photoluminescence intensity for increasing values of strain, excitation power, and temperature. The temperature dependence of the non-radiative recombination time in this material has been inferred thanks to the model calibration procedure.
Classical calculation of the equilibrium constants for true bound dimers using complete potential energy surface
Authors: Buryak Ilya , Vigasin Andrey A.
Published: December 2015

The present paper aims at deriving classical expressions which permit calculation of the equilibrium constant for weakly interacting molecular pairs using a complete multidimensional potential energy surface. The latter is often available nowadays as a result of the more and more sophisticated and accurate ab initio calculations. The water dimer formation is considered as an example. It is shown that even in case of a rather strongly bound dimer the suggested expression permits obtaining quite reliable estimate for the equilibrium constant. The reliability of our obtained water dimer equilibrium constant is briefly discussed by comparison with the available data based on experimental observations, quantum calculations, and the use of RRHO approximation, provided the latter is restricted to formation of true bound states only.
Schottky barrier modulation of metal/4H-SiC junction with thin interface spacer driven by surface polarization charge on 4H-SiC substrate
Authors: Choi Gahyun , Yoon Hoon Hahn , Jung Sungchul , Jeon Youngeun , Lee Jung Yong , Bahng Wook , Park Kibog
Published: December 2015

The Au/Ni/Al2O3/4H-SiC junction with the Al2O3 film as a thin spacer layer was found to show the electrical characteristics of a typical rectifying Schottky contact, which is considered to be due to the leakiness of the spacer layer. The Schottky barrier of the junction was measured to be higher than an Au/Ni/4H-SiC junction with no spacer layer. It is believed that the negative surface bound charge originating from the spontaneous polarization of 4H-SiC causes the Schottky barrier increase. The use of a thin spacer layer can be an efficient experimental method to modulate Schottky barriers of metal/4H-SiC junctions.
Gate tuneable beamsplitter in ballistic graphene
Authors: Rickhaus Peter , Makk Péter , Liu Ming-Hao , Richter Klaus , Schönenberger Christian
Published: December 2015

We present a beam splitter in a suspended, ballistic, multiterminal, bilayer graphene device. By using local bottomgates, a p-n interface tilted with respect to the current direction can be formed. We show that the p-n interface acts as a semi-transparent mirror in the bipolar regime and that the reflectance and transmittance of the p-n interface can be tuned by the gate voltages. Moreover, by studying the conductance features appearing in magnetic field, we demonstrate that the position of the p-n interface can be moved by 1 μm. The herein presented beamsplitter device can form the basis of electron-optic interferometers in graphene.
Novel tubular switched reluctance motor with double excitation windings: Design, modeling, and experiments
Authors: Yan Liang , Li Wei , Jiao Zongxia , Chen I-Ming
Published: December 2015

The space utilization of linear switched reluctance machine is relatively low, which unavoidably constrains the improvement of system output performance. The objective of this paper is to propose a novel tubular linear switched reluctance motor with double excitation windings. The employment of double excitation helps to increase the electromagnetic force of the system. Furthermore, the installation of windings on both stator and mover can make the structure more compact and increase the system force density. The design concept and operating principle are presented. Following that, the major structure parameters of the system are determined. Subsequently, electromagnetic force and reluctance are formulated analytically based on equivalent magnetic circuits, and the result is validated with numerical computation. Then, a research prototype is developed, and experiments are conducted on the system output performance. It shows that the proposed design of electric linear machine can achieve higher thrust force compared with conventional linear switched reluctance machines.
Cracks and blisters formed close to a silicon wafer surface by He-H co-implantation at low energy
Authors: Cherkashin N. , Daghbouj N. , Darras F.-X. , Fnaiech M. , Claverie A.
Published: December 2015

We have studied the effect of reducing the implantation energy towards low keV values on the areal density of He and H atoms stored within populations of blister cavities formed by co-implantation of the same fluence of He then H ions into Si(001) wafers and annealing. Using a variety of experimental techniques, we have measured blister heights and depth from the surface, diameter, areal density of the cracks from which they originate as functions of implantation energy and fluence. We show that there is a direct correlation between the diameters of the cracks and the heights of the associated blisters. This correlation only depends on the implantation energy, i.e., only on the depth at which the cracks are located. Using finite element method modeling, we infer the pressure inside the blister cavities from the elastic deformations they generate, i.e., from the height of the blisters. From this, we demonstrate that the gas pressure within a blister only depends on the diameter of the associated crack and not on its depth position and derive an analytical expression relating these parameters. Relating the pressure inside a blister to the respective concentrations of gas molecules it contains, we deduce the areal densities of He and H atoms contained within the populations of blisters. After low-energy implantations (8 keV He+, 3 keV H+), all the implanted He and H atoms contribute to the formation of the blisters. There is no measurable exo-diffusion of any of the implanted gases, in contrast to what was assumed at the state of the art to explain the failure of the Smart-Cut technology when using very low energy ion implantation for the fabrication of ultra-thin layers. Alternative explanations must be investigated.
Dynamic failure in two-phase materials
Authors: Fensin S. J. , Walker E. K. , Cerreta E. K. , Trujillo C. P. , Martinez D. T. , Gray G. T.
Published: December 2015

Previous experimental research has shown that microstructural features such as interfaces, inclusions, vacancies, and heterogeneities can all act as void nucleation sites. However, it is not well understood how important these interfaces are to damage evolution and failure as a function of the surrounding parent materials. In this work, we present results on three different polycrystalline materials: (1) Cu, (2) Cu-24 wt. %Ag, and (3) Cu-15 wt. %Nb which were studied to probe the influence of bi-metal interfaces on void nucleation and growth. These materials were chosen due to the range of difference in structure and bulk properties between the two phases. The initial results suggest that when there are significant differences between the bulk properties (for example: stacking fault energy, melting temperature, etc.) the type of interface between the two parent materials does not principally control the damage nucleation and growth process. Rather, it is the “weaker” material that dictates the dynamic spall strength of the overall two-phase material.
Large-signal model of the bilayer graphene field-effect transistor targeting radio-frequency applications: Theory versus experiment
Authors: Pasadas Francisco , Jiménez David
Published: December 2015

Bilayer graphene is a promising material for radio-frequency transistors because its energy gap might result in a better current saturation than the monolayer graphene. Because the great deal of interest in this technology, especially for flexible radio-frequency applications, gaining control of it requires the formulation of appropriate models for the drain current, charge, and capacitance. In this work, we have developed them for a dual-gated bilayer graphene field-effect transistor. A drift-diffusion mechanism for the carrier transport has been considered coupled with an appropriate field-effect model taking into account the electronic properties of the bilayer graphene. Extrinsic resistances have been included considering the formation of a Schottky barrier at the metal-bilayer graphene interface. The proposed model has been benchmarked against experimental prototype transistors, discussing the main figures of merit targeting radio-frequency applications.
Structural phase diagram and pyroelectric properties of free-standing ferroelectric/non-ferroelectric multilayer heterostructures
Authors: Zhang Jialan , Agar Josh C. , Martin Lane W.
Published: December 2015

Ginzburg-Landau-Devonshire models are used to explore ferroelectric phases and pyroelectric coefficients of symmetric free-standing, thin-film trilayer heterostructures composed of a ferroelectric and two identical non-ferroelectric layers. Using BaTiO3 as a model ferroelectric, we explore the influence of temperature, in-plane misfit strain, and the non-ferroelectric layer (including effects of elastic compliance and volume fraction) on the phase evolution in the ferroelectric. The resulting phase diagram reveals six stable phases, two of which are not observed for thin films on semi-infinite cubic substrates. From there, we focus on heterostructures with non-ferroelectric layers of commonly available scandate materials which are widely used as substrates for epitaxial growth. Again, six phases with volatile phase boundaries are found in the phase diagram for the NdScO3/BaTiO3/NdScO3 trilayerheterostructures. The evolution of polarization and pyroelectric coefficients in the free-standing NdScO3 trilayer heterostructures is discussed with particular attention to the role that heterostructure design plays in influencing the phase evolution and temperature-dependence with a goal of creating enhanced pyroelectric response and advantages over traditional thin-film heterostructures.
Optical polarization characteristics of c-plane InGaN/GaN asymmetric nanostructures
Authors: Zhuang Zhe , Li Yi , Liu Bin , Guo Xu , Dai Jiangping , Zhang Guogang , Tao Tao , Zhi Ting , Xie Zili , Ge Haixiong , Shi Yi , Zheng Youdou , Zhang Rong
Published: December 2015

Highly ordered c-plane InGaN/GaN elliptic nanorod (NR) and nano-grating (NG) arrays were fabricated by our developed soft UV-curing nanoimprint lithography on a wafer. The polarized photoluminescence emission from these elliptic NR and NG arrays has been investigated both theoretically and experimentally. Considerable in-plane optical anisotropy, with a polarization ratio of 15% and 71% and a peak shift of 5.2 meV and 28.1 meV, was discovered from these c-plane InGaN/GaN elliptic NR and NG arrays, respectively. The k·p perturbation theory was adopted to explore this situation, simulating the transitions from conduction subbands to valence subbands and their corresponding optical momentum matrix elements at/around Γ point under the in-plane asymmetric strain. The good agreements of observed and simulated results demonstrate that the in-plane strain asymmetry is the essential cause of the optical polarization in this case, revealing the great potential to utilize strain effect to control the polarization of InGaN/GaN nanostructures.
A simple structure of all circular-air-holes photonic crystal fiber for achieving high birefringence and low confinement loss
Authors: Chou Chau Yuan-Fong , Lim Chee Ming , Yoong Voo Nyuk , Syafi'ie Idris Muhammad Nur
Published: December 2015

We propose a simple structure of photonic crystal fibers (PCFs) with high birefringence and low confinement loss based on one rectangular centric ring of smaller circular air holes (CAHs) in the fiber core, and three rings of larger CAHs in the fiber cladding. This simple geometry (using all CAHs with two different air hole sizes) is capable of achieving a flexible control of the birefringence, B = 5.501 × 10−3, and ultra-low confinement loss, 7.30 × 10−5 dB/km, at an excitation wavelength of λ = 1550 nm. The birefringence value is ∼5.0 times greater than that obtained for conventional CAH PCF. This simple structure has the added advantage from the view point of easy fabrication, robustness, and cost. A full-vector finite element method combined with anisotropic perfectly matched layers was used to analyze the various fiber structures. We have analyzed four cases of CAH PCFs, focusing on the core asymmetry design as opposed to the conventional approach of CAHs or elliptical air holes on the cladding and core. The robustness against manufacturing inaccuracies of the proposed structure has also been further investigated in this work.
Spoof localized surface plasmons and Fano resonances excited by flared slot line
Authors: Xiao Qian Xun , Yang Bao Jia , Zhou Yong Jin
Published: December 2015

We have investigated spoof localized surface plasmons in the planar textured metallic disk incorporating an efficient and ease-of-integration method. It has been demonstrated that multipolar resonances can be effectively excited and enhanced by flared slot line, which are sensitive to the change of surrounding environment. Experiments at microwave frequencies have been conducted to verify these resonances, showing good agreements to numerical simulations. Multiple Fano resonances have been numerically and experimentally exploited, and it has been shown that strong Fano resonances occur when the corrugated bi-disk structure is vertically excited by flared slot line. Such integrated spoof plasmonic structures could find more applications, such as planar integrated sensing and biological detection at the microwave and terahertz frequencies.
Revealing the global map of protein folding space by large-scale simulations
Authors: Sinner Claude , Lutz Benjamin , Verma Abhinav , Schug Alexander
Published: December 2015

The full characterization of protein folding is a remarkable long-standing challenge both for experiment and simulation. Working towards a complete understanding of this process, one needs to cover the full diversity of existing folds and identify the general principles driving the process. Here, we want to understand and quantify the diversity in folding routes for a large and representative set of protein topologies covering the full range from all alpha helical topologies towards beta barrels guided by the key question: Does the majority of the observed routes contribute to the folding process or only a particular route? We identified a set of two-state folders among non-homologous proteins with a sequence length of 40–120 residues. For each of these proteins, we ran native-structure based simulations both with homogeneous and heterogeneous contact potentials. For each protein, we simulated dozens of folding transitions in continuous uninterrupted simulations and constructed a large database of kinetic parameters. We investigate folding routes by tracking the formation of tertiary structure interfaces and discuss whether a single specific route exists for a topology or if all routes are equiprobable. These results permit us to characterize the complete folding space for small proteins in terms of folding barrier ΔG‡, number of routes, and the route specificity RT.
Three-dimensional evolution of large-scale vortices in supersonic flow
Authors: Feng Jun-hong , Shen Chi-bing , Wang Qian-cheng
Published: December 2015

The supersonic large-scale vortices generated by a streamwise vortex generator were investigated experimentally using the nanoparticle-based planar laser scattering method, with the emphasis on the entrainment and mixing characteristics in supersonic mixing layer. The spanwise coherent structures originated from the K-H instability grew up along with the vortex pairing process, which are able to exist in far field downstream of trailing edge. The large-scale streamwise vortex shed from the generator plays a major role in entraining the surrounding fluid from both sides of interface into mixing zone. Meanwhile, through the interaction with spanwise vortices, the streamwise vortex breaks up into the small-scale structures for molecular mixing. Moreover, the T-shaped structures and secondary K-H vortices are shown to be the usual topological structures in small-scale turbulence transport.
Magnetoelectric coupling in Pb(Zr,Ti)O3—Galfenol thin film heterostructures
Authors: More-Chevalier J. , Lüders U. , Cibert C. , Nosov A. , Domengès B. , Bouregba R. , Poullain G.
Published: December 2015

Heterostructures of piezoelectric Pb(Zr,Ti)O3 and magnetostrictive Galfenol were fabricated by sputtering and pulsed laser deposition on platinized Si substrates with the aim to induce a magnetoelectric coupling between the layers of the two materials. In this study, no intermediate layer was introduced between Pb(Zr0.56Ti0.44)O3 and Galfenol in contrast to most of the previous thin films studies. The obtained magnetoelectric coupling constant is in the range of 6–7 V/(cm Oe), indicating that an undisturbed piezoelectric-magnetostrictive interface can outbalance small deteriorations of the ferroic properties of the active materials.
Topological constraints of network chains in telechelic associative polymer gels
Authors: Li Sijia , Chen Jizhong , Xu Donghua , Shi Tongfei
Published: December 2015

We present an analysis of topological constraints of network chains, in particular entanglements, in ABA telechelic associative polymer gels generated by Brownian dynamics technique with a B selective solvent. We find two fundamental types of entanglements formed by bridge chains: first, two or more bridge chains linking different micelles impose topological constraints on each other because they cannot cross, denoted as type-I entanglement; second, two or more bridge chains linking a pair of micelles are twisted together, denoted as type-II entanglement. More complex constraints are composed of both types. There is no difference between type-I and type-II entanglements in polymer melts, but in gels, only type-I entanglement provides extra junctions that can significantly affect the modulus. The dependences of entanglement on chain length and concentration are investigated. The simulations reveal that even at low concentrations where only parts of long chains are entangled, they can provide a considerable number of junctions.
Band structure of topological insulators from noise measurements in tunnel junctions
Authors: Cascales Juan Pedro , Martínez Isidoro , Katmis Ferhat , Chang Cui-Zu , Guerrero Rubén , Moodera Jagadeesh S. , Aliev Farkhad G.
Published: December 2015

The unique properties of spin-polarized surface or edge states in topological insulators (TIs) make these quantum coherent systems interesting from the point of view of both fundamental physics and their implementation in low power spintronic devices. Here we present such a study in TIs, through tunneling and noise spectroscopy utilizing TI/Al2O3/Co tunnel junctions with bottom TI electrodes of either Bi2Te3 or Bi2Se3. We demonstrate that features related to the band structure of the TI materials show up in the tunneling conductance and even more clearly through low frequency noise measurements. The bias dependence of 1/f noise reveals peaks at specific energies corresponding to band structure features of the TI. TI tunnel junctions could thus simplify the study of the properties of such quantum coherent systems that can further lead to the manipulation of their spin-polarized properties for technological purposes.
Effect of native oxide layers on copper thin-film tensile properties: A reactive molecular dynamics study
Authors: Skarlinski Michael D. , Quesnel David J.
Published: December 2015

Metal-oxide layers are likely to be present on metallic nano-structures due to either environmental exposure during use, or high temperature processing techniques such as annealing. It is well known that nano-structured metals have vastly different mechanical properties from bulk metals; however, difficulties in modeling the transition between metallic and ionic bonding have prevented the computational investigation of the effects of oxide surface layers. Newly developed charge-optimized many body [Liang et al., Mater. Sci. Eng., R 74, 255 (2013)] potentials are used to perform fully reactive molecular dynamics simulations which elucidate the effects that metal-oxide layers have on the mechanical properties of a copper thin-film. Simulated tensile tests are performed on thin-films while using different strain-rates, temperatures, and oxide thicknesses to evaluate changes in yield stress, modulus, and failure mechanisms. Findings indicate that copper-thin film mechanical properties are strongly affected by native oxide layers. The formed oxide layers have an amorphous structure with lower Cu-O bond-densities than bulk CuO, and a mixture of Cu2O and CuO charge character. It is found that oxidation will cause modifications to the strain response of the elastic modulii, producing a stiffened modulii at low temperatures (<75 K) and low strain values (<5%), and a softened modulii at higher temperatures. While under strain, structural reorganization within the oxide layers facilitates brittle yielding through nucleation of defects across the oxide/metal interface. The oxide-free copper thin-film yielding mechanism is found to be a tensile-axis reorientation and grain creation. The oxide layers change the observed yielding mechanism, allowing for the inner copper thin-film to sustain an FCC-to-BCC transition during yielding. The mechanical properties are fit to a thermodynamic model based on classical nucleation theory. The fit implies that the oxidation of the films reduces the activation volume for yielding.
Traveling surface spin-wave resonance spectroscopy using surface acoustic waves
Authors: Gowtham P. G. , Moriyama T. , Ralph D. C. , Buhrman R. A.
Published: December 2015

Coherent gigahertz-frequency surface acoustic waves (SAWs) traveling on the surface of a piezoelectric crystal can, via the magnetoelastic interaction, resonantly excite traveling surface spin waves in an adjacent thin-film ferromagnet. These excited surface spin waves, traveling with a definite in-plane wave-vector q∥ enforced by the SAW, can be detected by measuring changes in the electro-acoustical transmission of a SAW delay line. Here, we provide a demonstration that such measurements constitute a precise and quantitative technique for spin-wave spectroscopy, providing a means to determine both isotropic and anisotropic contributions to the spin-wave dispersion and damping. We demonstrate the effectiveness of this spectroscopic technique by measuring the spin-wave properties of a Ni thin film for a large range of wave vectors, |q∥| = 2.5 × 104–8 × 104 cm−1, over which anisotropic dipolar interactions vary from being negligible to quite significant.
Ferroelastic twin structures in epitaxial WO3 thin films
Authors: Yun Shinhee , Woo Chang-Su , Kim Gi-Yeop , Sharma Pankaj , Lee Jin Hong , Chu Kanghyun , Song Jong Hyun , Chung Sung-Yoon , Seidel Jan , Choi Si-Young , Yang Chan-Ho
Published: December 2015

Tungsten trioxide is a binary oxide that has potential applications in electrochromic windows, gas sensors, photo-catalysts, and superconductivity. Here, we analyze the crystal structure of atomically flat epitaxial layers on YAlO3 single crystal substrates and perform nanoscale investigations of the ferroelastic twins revealing a hierarchical structure at multiple length scales. We have found that the finest stripe ferroelastic twin walls along pseudocubic 〈100〉 axes are associated with cooperative mosaic rotations of the monoclinic films and the larger stripe domains along pseudocubic 〈110〉 axes are created to reduce the misfit strain through a commensurate matching of an effective in-plane lattice parameter between film and substrate. The typical widths of the two fine and larger stripe domains increase with film thickness following a power law with scaling exponents of ∼0.6 and ∼0.4, respectively. We have also found that the twin structure can be readily influenced by illumination with an electron beam or a tip-based mechanical compression.
Determination of shape anisotropy in embedded low contrast submonolayer quantum dot structures
Authors: Dhomkar S. , Vaxelaire N. , Ji H. , Shuvayev V. , Tamargo M. C. , Kuskovsky I. L. , Noyan I. C.
Published: December 2015

We describe a procedure for the morphological characterization of hard-to-image submonolayer quantum dot structures. This procedure employs high resolution x-ray diffraction based reciprocal space mapping, accompanied by rigorous diffraction modeling for precise determination of the morphology of submonolayer quantum dots. Our modelling results and experimental data clearly show that the investigated quantum dots are anisotropically elongated along the [110] orientation. Complementary polarization dependent photoluminescence measurements, combined with our previously reported magneto-photoluminescence data, confirm this conclusion. Our formalism enables direct extraction of structural information of complex embedded three-dimensional structures, which, due to their low electron density contrast with respect to the surrounding host matrix, cannot be readily investigated by traditional electron diffraction techniques.
Deep ultraviolet Raman spectroscopy: A resonance-absorption trade-off illustrated by diluted liquid benzene
Authors: Chadwick C. T. , Willitsford A. H. , Philbrick C. R. , Hallen H. D.
Published: December 2015

The magnitude of resonance Raman intensity, in terms of the real signal level measured on-resonance compared to the signal level measured off-resonance for the same sample, is investigated using a tunable laser source. Resonance Raman enhancements, occurring as the excitation energy is tuned through ultraviolet absorption lines, are used to examine the 1332 cm−1 vibrational mode of diamond and the 992 cm−1 ring-breathing mode of benzene. Competition between the wavelength dependent optical absorption and the magnitude of the resonance enhancement is studied using measured signal levels as a function of wavelength. Two system applications are identified where the resonance Raman significantly increases the real signal levels despite the presence of strong absorption: characterization of trace species in laser remote sensing and spectroscopy of the few molecules in the tiny working volumes of near-field optical microscopy.
Electromagnetic cloak to restore the antenna radiation patterns affected by nearby scatter
Authors: Teperik Tatiana V. , de Lustrac André
Published: December 2015

We have theoretically verified the feasibility of the concept of mantle cloak for very high frequency (VHF) antenna communications. While the applicability of the concept has been demonstrated for an infinitely long cylindrical obstacle and infinitely long electric source [Y.R. Padooru, A.B. Yakovlev, and P.-Y. Chen and Andrea Alù, J. Appl. Phys., 112, 104902, (2012)], the use of this cloak in realistic conditions is not straightforward. In this paper as an electric source we consider a typical VHF monopole antenna mounted on ground plane together with a metallic cylindrical obstacle. The both ground plane and obstacle affect the antenna radiation scattering. Nevertheless, we could show that the mantle cloak can bee successfully applied to restore the radiation patterns of antenna even when the source, the cylindrical metallic obstacle, and the ground plane have finite length. We have studied the antenna adaptation in the presence of the cloaked obstacle and found that the complete radiation system is still functional in the bandwidth that is reduced only by 11%.
A rare, new species of Atriplex (Chenopodiaceae) comprising two genetically distinct but morphologically cryptic populations in arid Western Australia: implications for taxonomy and conservation
Authors: Shepherd Kelly A. , Thiele Kevin. R. , Sampson Jane , Coates David , Byrne Margaret
Published: December 2015

A rare, new tetraploid Atriplex, restricted to two populations ~30km apart in arid Western Australia, is supported as a distinct species by morphological and molecular evidence. Genetic analyses using amplified fragment length polymorphisms (AFLPs) showed significant genetic divergence between the two populations. In contrast, an ordination based on elliptic Fourier descriptors for leaf and bracteole shape did not identify any consistent morphological differentiation. Although the level of genetic differentiation is similar to that previously reported between subspecies in other Atriplex, the populations of the new taxon are described herein as A. yeelirrie K.A.Sheph. & K.R.Thiele, without taxonomic recognition at the intraspecific level. We outline our reasoning for this decision and discuss the implications for appropriate conservation management of the species, structured into two genetically distinct populations.
Measuring radiant emissions from entire prescribed fires with ground, airborne and satellite sensors – RxCADRE 2012
Authors: Dickinson Matthew B. , Hudak Andrew T. , Zajkowski Thomas , Loudermilk E. Louise , Schroeder Wilfrid , Ellison Luke , Kremens Robert L. , Holley William , Martinez Otto , Paxton Alexander , Bright Benjamin C. , O'Brien Joseph J. , Hornsby Benjamin , Ichoku Charles , Faulring Jason , Gerace Aaron , Peterson David , Mauceri Joseph
Published: December 2015

Characterising radiation from wildland fires is an important focus of fire science because radiation relates directly to the combustion process and can be measured across a wide range of spatial extents and resolutions. As part of a more comprehensive set of measurements collected during the 2012 Prescribed Fire Combustion and Atmospheric Dynamics Research (RxCADRE) field campaign, we used ground, airborne and spaceborne sensors to measure fire radiative power (FRP) from whole fires, applying different methods to small (2 ha) and large (>100 ha) burn blocks. For small blocks (n = 6), FRP estimated from an obliquely oriented long-wave infrared (LWIR) camera mounted on a boom lift were compared with FRP derived from combined data from tower-mounted radiometers and remotely piloted aircraft systems (RPAS). For large burn blocks (n = 3), satellite FRP measurements from the Moderate-resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) sensors were compared with near-coincident FRP measurements derived from a LWIR imaging system aboard a piloted aircraft. We describe measurements and consider their strengths and weaknesses. Until quantitative sensors exist for small RPAS, their use in fire research will remain limited. For oblique, airborne and satellite sensors, further FRP measurement development is needed along with greater replication of coincident measurements, which we show to be feasible.
Three-spheres theorems for subelliptic quasilinear equations in Carnot groups of Heisenberg-type
Authors: Adamowicz Tomasz , Warhurst Ben
Published: December 2015

We study the arithmetic three-spheres theorems for subsolutions of subelliptic PDEs of

p
p

-harmonic type in Carnot groups of Heisenberg type for

1
>
p
>
∞

1>p>\infty

. In the presentation we exhibit the special cases of sub-Laplace equations (

p
=
2

p=2

) and the case

p
p

is equal to the homogeneous dimension of a Carnot group. Corollaries include asymptotic behavior of subsolutions for small and large radii and the Liouville-type theorems.
Symmetry of positive solutions for equations involving higher order fractional Laplacian
Authors: Li Yan , Zhuo Ran
Published: December 2015

In this paper, we consider problems associated with the higher order fractional Laplacian. Through the method of moving planes, we derive rotational symmetry of positive solutions and show their dependence on the

x
n

x_n

variable only. We also establish the equivalence between a semilinear higher order fractional Laplacian equation and its corresponding integral equation, so as to further deduce a Liouville type theorem and obtain a priori estimates for positive solutions.
Around supersymmetry for semiclassical second order differential operators
Authors: Michel Laurent
Published: December 2015

Let

P
(
h
)
,
h
∈
]
0
,
1
]

P(h),h\in ]0,1]

be a semiclassical scalar differential operator of order

2
2

. The existence of a supersymmetric structure given by a matrix

G
(
x
;
h
)

G(x;h)

was exhibited by Hérau, Hitrik, and Sjöstrand (2011) under rather general assumptions. In this paper we give a sufficient condition on the coefficients of

P
(
h
)

P(h)

so that the matrix

G
(
x
;
h
)

G(x;h)

enjoys some nice estimates with respect to the semiclassical parameter.
On the universal central extension of hyperelliptic current algebras
Authors: Cox Ben
Published: December 2015

Let

p
(
t
)
∈

C

[
t
]

p(t)\in \mathbb C[t]

be a polynomial with distinct roots and nonzero constant term. We describe, using Faà de Bruno’s formula and Bell polynomials, the universal central extension in terms of generators and relations for the hyperelliptic current Lie algebras

g

⊗
R

\mathfrak g\otimes R

whose coordinate ring is of the form

R
=

C

[
t
,

t

−
1

,
u

|

u
2

=
p
(
t
)
]

R=\mathbb C[t,t^{-1},u\,|\, u^2=p(t)]

.
Vapnik-Chervonenkis density in some theories without the independence property, I
Authors: Aschenbrenner Matthias , Dolich Alf , Haskell Deirdre , Macpherson Dugald , Starchenko Sergei
Published: December 2015

We recast the problem of calculating Vapnik-Chervonenkis (VC) density into one of counting types, and thereby calculate bounds (often optimal) on the VC density for some weakly o-minimal, weakly quasi-o-minimal, and

P
P

-minimal theories.
Gene expression profiling of lung adenocarcinoma in Xuanwei, China
Authors: Wu Huifei , Meng Shuangshuang , Xu Qiuyue , Wang Xiao , Wang Juan , Gong Rong , Song Yu , Duan Yong , Zhang Yanliang
Published: December 2015

The morbidity and mortality of lung cancer in Xuanwei, China, are the highest in the world. This study attempts to identify differentially expressed genes (DEGs) related to lung adenocarcinoma in Xuanwei. The expression profiles of eight paired lung adenocarcinoma tissues and corresponding nontumor tissues were acquired by microarrays. Functional annotations of DEGs were carried out by bioinformatics analysis. The results of the microarrays were further verified by real-time quantitative PCR (RTq-PCR). A total of 5290 genes were classified as DEGs in lung adenocarcinoma in Xuanwei; 3325 genes were upregulated and 1965 genes were downregulated, whereas the expression of the other 11 970 genes did not change. These DEGs are involved in a wide range of cancer-related processes, which include cell division, cell adhesion, cell proliferation, and DNA replication, and in many pathways such as the p53 signaling pathway, the MAPK pathway, the Jak-STAT signaling pathway, the hedgehog signaling pathway, and the non-small-cell lung cancer pathway. The tendency of changes in the expression of 12 selected DEGs (five downregulated genes, PIK3R1, RARB, HGF, MAPK11, and SESN1, and seven upregulated genes, PAK1, E2F1, CCNE1, EGF, CDC25A, PTTG1, and UHRF1) in RTq-PCR was consistent with the expression profiling data. Expression of PAK1 was significantly increased in the low differentiation group (P=0.031), whereas expression of HGF was significantly decreased in the low differentiation group (P=0.045). RARB and MAPK11 were significantly increased in the nonsmoker group (P=0.033 and 0.040, respectively). A large number of DEGs in lung adenocarcinoma in Xuanwei have been detected, which may enable us to understand the pathogenesis and lay an important foundation for the prevention and treatment of lung adenocarcinoma in Xuanwei.
Creating value for participants in multistakeholder alliances
Authors: D’Aunno Thomas , Alexander Jeffrey A. , Jiang Lan
Published: December 2015

Background:

Multistakeholder alliances that bring together diverse organizations to work on health-related issues are playing an increasingly prominent role in the U.S. health care system. Prior research shows that collaborative decision-making and effective leadership are related to members’ perceptions of value for their participation in alliances. Yet, we know little about how collaborative decision-making and leadership might matter over time in multistakeholder alliances.

Purpose:

The aim of this study was to advance understanding of the role of collaborative decision-making and leadership in individuals’ assessments of the benefits and costs of their participation in multistakeholder alliances over time.

Methods:

We draw on data collected from three rounds of surveys of alliance members (2007–2012) who participated in the Robert Wood Johnson Foundation’s Aligning Forces for Quality program.

Findings:

Results from regression analyses indicate that individuals’ perceptions of value for their participation in alliances shift over time: Perceived value is higher with collaborative decision-making when alliances are first formed and higher with more effective leadership as time passes after alliance formation.

Practice Implications:

Leaders of multistakeholder alliances may need to vary their behavior over time, shifting their emphasis from inclusive decision-making to task achievement.
Unusual rash accompanied by enterovirus infection and human bocavirus co-infection in a 9-week-old infant in Cologne, Germany
Authors: Korsch Eckhard , Pieper Monika , Schildgen Verena , Schildgen Oliver , Brockmann Michael
Published: December 2015

Introduction:

The family Picornaviridae is divided into several genera, including the genus Enterovirus, which includes the species Human enterovirus A to -C and Human rhinovirus A to −C. These viruses are frequently associated with respiratory and gastrointestinal diseases. Coxsackie virus and echoviruses can induce a rash in children, such as hand-foot-and-mouth disease caused by coxsackie virus A16, while rhinoviruses are associated mainly with respiratory infections.

Case presentation:

We describe a clinical case of mild rhinitis in a 9-week-old female infant with HBoV and enterovirus co-infection accompanied by an unusual rash that strongly resembled granuloma annulare, having plaques with raised non-scaly erythematous borders. The child was afebrile, displayed a garland-like rash that within minutes changed its pattern and had moderately elevated expression of tryptase. No other pathogens were detected.

Conclusion:

It was concluded that the rash originated from the double infection with enterovirus and HBoV, as no further rash-associated pathogens were detected. The case is important as it is the first description, to the best of our knowledge, of this unusual rash seen with enterovirus/HBoV co-infection, and as this condition should be taken into account in future.
The at-wavelength metrology facility for UV- and XUV-reflection and diffraction optics at BESSY-II
Authors: Schäfers F. , Bischoff P. , Eggenstein F. , Erko A. , Gaupp A. , Künstner S. , Mast M. , Schmidt J.-S. , Senf F. , Siewert F. , Sokolov A. , Zeschke Th.
Published: December 2015

A technology center for the production of high-precision reflection gratings has been established. Within this project a new optics beamline and a versatile reflectometer for at-wavelength characterization of UV- and XUV-reflection gratings and other (nano-) optical elements has been set up at BESSY-II. The Plane Grating Monochromator beamline operated in collimated light (c-PGM) is equipped with an SX700 monochromator, of which the blazed gratings (600 and 1200 lines mm−1) have been recently exchanged for new ones of improved performance produced in-house. Over the operating range from 10 to 2000 eV this beamline has very high spectral purity achieved by (i) a four-mirror arrangement of different coatings which can be inserted into the beam at different angles and (ii) by absorber filters for high-order suppression. Stray light and scattered radiation is removed efficiently by double sets ofin situexchangeable apertures and slits. By use of in- and off-plane bending-magnet radiation the beamline can be adjusted to either linear or elliptical polarization. One of the main features of a novel 11-axes reflectometer is the possibility to incorporate real life-sized gratings. The samples are adjustable within six degrees of freedom by a newly developed UHV-tripod system carrying a load up to 4 kg, and the reflectivity can be measured between 0 and 90° incidence angle for boths- andp-polarization geometry. This novel powerful metrology facility has gone into operation recently and is now open for external users. First results on optical performance and measurements on multilayer gratings will be presented here.
Eighteenth-century forms of quasicrystals
Authors: Pina Carlos M. , López-Acevedo Victoria
Published: December 2015

A careful inspection of the drawings and baked clay models created by the mineralogist Romé de L'Isle in the 18th century has revealed the existence of a number of intriguing forms with pentagonal symmetries. These forms cannot be classified in any of the 32 crystal classes. They can thus be considered the first crystallographic descriptions of polyhedral forms found in quasicrystals two centuries later. This paper presents a symmetry analysis of the fascinating drawings and clay models with pentagonal symmetries described in the bookCristallographiepublished in 1783 by Romé de L'Isle, as well as a comparison with quasicrystals recently synthesized. The paper also briefly discusses what could induce Romé de L'Isle to consider forms with pentagonal symmetries as plausible crystal forms.
Role of experience and luck in management success: an interview with R.V. Kanoria, Managing Director of Kanoria Chemicals
&
Industries Ltd.
Authors: Prabhakar Guru Prakash , Saran Pankaj
Published: December 2015

Purpose

– This paper aims to review the latest management developments across the globe and pinpoint practical implications from cutting-edge research and case studies.

Design/methodology/approach

– This briefing is prepared by independent writers who add their own impartial comments and place the articles in context.

Findings

– The role of luck in a leader’s success is not scientifically proven. But many leaders do advocate the efficacy of the luck factor behind a leader’s success.

Practical implications

– The paper provides strategic insights and practical thinking that have influenced some of the world’s leading organizations.

Originality/value

– The briefing saves busy executives and researchers hours of reading time by selecting only the very best, most pertinent information and presenting it in a condensed and easy-to-digest format.
Flying with the winds: differential migration strategies in relation to winds in moth and songbirds
Authors: Åkesson Susanne
Published: December 2015

The gamma Y moth selects to migrate in stronger winds compared to songbirds, enabling fast transport to distant breeding sites, but a
lower precision in orientation as the moth allows itself to be drifted by the winds. Photo: Ian Woiwod.

In Focus: Chapman, J.R., Nilsson, C., Lim, K.S., Bäckman, J., Reynolds, D.R. & Alerstam, T. (2015) Adaptive strategies in nocturnally migrating insects and songbirds: contrasting responses to winds. Journal of Animal Ecology, 85, 115–124

Insects and songbirds regularly migrate long distances across continents and seas. During these nocturnal migrations, they are exposed to a fluid medium, the air, in which they transport themselves by flight at similar speeds as the winds may carry them. It is crucial for an animal to select the most favourable flight conditions relative to winds to minimize the distance flown on a given amount of fuel and to avoid hazardous situations. Chapman et al. (2015a) showed contrasting strategies in how moths initiate migration predominantly under tailwind conditions, allowing themselves to drift to a larger extent and gain ground speed as compared to nocturnal songbird migrants. The songbirds use more variable flight strategies in relation to winds, where they sometimes allow themselves to drift, and at other occasions compensate for wind drift. This study shows how insects and birds have differentially adapted to migration in relation to winds, which is strongly dependent on their own flight capability, with higher flexibility enabling fine‐tuned responses to keep a time programme and reach a goal in songbirds compared to in insects.