bluuebunny/crossref_metadata_2025 huggingface dataset:
Non‐volatile memory operation in normally‐off GaN MOS heterostructure field effect transistors with thin AlGaN barrier
Authors: Keum D. , Cho K. , Kim H.
Published: February 2016

Normally‐off AlGaN/GaN metal‐oxide‐semiconductor heterostructure field effect transistors have been fabricated and characterised for non‐volatile memory operation. 2 nm‐thickness AlGaN barrier layer was obtained by gate recess process using inductively‐coupled‐plasma etching. The device was set to a program state by applying positive gate bias which induced the positive shift of threshold voltage and this shift was switched back to the original value by applying negative gate bias. The threshold voltage shift was 3.6 V between the program and the erase states. The retention characteristics were stable for over 105 s. The device characteristics were not degraded after 103 cycles of program/erase operations.
High‐speed quasi‐distributed strain sensing based on time division multiplexing of fibre Bragg gratings
Authors: Ma L. , Ma C. , Wang Y. , Wang D.Y. , Wang A.
Published: February 2016

A high‐speed quasi‐distributed fibre optic sensing technique for strain is proposed and a proof‐of‐concept experiment is performed. The sensing link is formed by multiple fibre Bragg gratings and interrogated by a pulsed broadband source. A dispersive unit is used to translate wavelength variations to time‐delay changes to enable high‐speed sensing capability. As the gratings can be weakly reflecting and nominally identical in their reflection spectra, this technique has the inherent capability of high‐capacity multiplexing. Linear and repeatable static strain response was achieved with a strain–delay conversion factor of −3.37 ps/με and a resolution of 4.73 με. Dynamic strain was successfully measured at a sampling rate of 7 kHz and dynamic resolution of 0.2 με/√Hz was obtained.
Segmentation of SAR images using similarity ratios for generating and clustering superpixels
Authors: Akyilmaz E. , Leloglu U.M.
Published: February 2016

The superpixels are groups of similar neighbouring pixels which are perceptually meaningful and representationally efficient segments. Among those existing superpixel generating algorithms, simple linear iterative clustering (SLIC) seems to be one of the simplest ones. Its simplicity is due to adaption of a distance measure which is a linear combination of colour and spatial proximity. It is this measure that is modified using a similarity ratio. This modified measure is used to label the pixels within the search areas for generating the superpixels. This generation phase is further augmented with a clustering phase based on the same formulated similarity metric, which clusters the superpixels into larger segments. It has been demonstrated that this modified version performs better in terms of boundary recall and undersegmentation error, and is more robust to the speckle noise than the one in SLIC. Moreover, the clustered segments formed by superpixels generated by this approach has better boundary adherence than those formed by superpixels generated by SLIC.
Miller effect suppression of tunnel field‐effect transistors (TFETs) using capacitor neutralisation
Authors: Choi W.Y.
Published: February 2016

A novel method of suppressing the Miller effects of tunnel field‐effect transistors (TFETs) is proposed by using capacitor neutralisation. Since TFETs suffer from more severe Miller effects than metal‐oxide‐semiconductor FETs, conventional ways such as short‐gate structures are not sufficient to fully suppress the Miller effects of TFETs. For further reduction of Miller effects, capacitor neutralisation is applied to TFET circuit design for the first time. An exemplary circuit has been shown to confirm the effectiveness of capacitor neutralisation such as differential cascade voltage switch logic. The suppression of Miller effects has been discussed in terms of undershoot, switching delay, power consumption and circuit area.
Joint channel estimation and decoding in the presence of phase noise over time‐selective flat‐fading channels
Authors: Shi Qiaolin , Wu Nan , Wang Hua , Yuan Weijie
Published: February 2016

Oscillator phase noise (PHN) can result in significant performance loss in coherent communication systems if not compensated appropriately. Most existing studies focus on either PHN estimation over additive white Gaussian noise channels or channel impulse response (CIR) estimation in the absence of PHN. In this study, joint CIR estimation and decoding over time‐selective flat‐fading channels impacted by PHN is studied. Both the time evolutions of CIR and PHN are approximated by autoregressive models. Building on this, factor graph of the joint a posteriori probability function is constructed and the sum–product algorithm is applied to derive messages on factor graph. Due to the non‐linearity of PHN, no closed‐form expressions of the messages can be obtained. To this end, the authors use canonical distribution approach, which approximates the messages by Gaussian and Tikhonov probability density functions on the sub‐graphs of CIR and PHN, respectively. Accordingly, the messages can be calculated by updating the parameters of the canonical distributions. A mixed serial‐parallel message passing schedule is presented to implement the algorithm, which enables the compromise between the bit error rate performance and the processing throughput. Simulation results show that the proposed joint estimation and decoding algorithm significantly outperforms the existing methods in fading channels impacted by PHN.
Effective dynamic channel assignment scheme for on‐board processing satellite platform
Authors: Li Hang , Zhao Ming , Wang Jing
Published: February 2016

Dynamic channel assignment is an effective approach to decrease inter‐cell interference and improve link quality. Due to flat beam coverage property, link performance is degraded if conventional dynamic channel assignment schemes are directly employed in satellite network. To solve this problem, this study proposes the beam cooperation based dynamic channel assignment scheme, in which adjacent beams serve edge users cooperatively. Feature of feed sharing, channel model of satellite network, number of cooperative beams and combination method of the receiver are discussed in the proposed scheme. In addition, link quality restriction is applied to avoid drastically performance degradation in case of heavy traffic. Simulation results show that the proposed dynamic channel assignment scheme can effectively improve the average performance of users in the beam. Furthermore, the optimal antenna parameter for the proposed scheme is achieved by simulation.
Inspecting lens collars for defects using discrete cosine transformation based on an image restoration scheme
Authors: Chen Ssu‐Han
Published: February 2016

Automated cutting process may produce superficial defects such as scratches and depressions on lens collars which are caused by cutter offset or scrap accumulation. Additionally, electroplating defects, such as dots and uneven electroplating occurs if the surface is rough or contaminated with foreign matters. As the inclined camber of lens collar contributes to external appearances of a single‐lens camera, customers extremely concern about its surface quality. Relying on human inspection to ensure the quality is time‐consuming, labor‐intensive and produces occupational injuries. Therefore, the implementation of auto‐inspection can help overcome these problems. The inspection system is composed of charge coupled device (CCD), coaxial light and motor. After an image is taken, it goes through a segmentation sub‐function to obtain a region of interesting (ROI). Since the texture of inclined camber of a lens collar is statistically distributed, an image restoration sub‐function based on discrete cosine transformation (DCT) is used to map the texture onto high‐energy components on a spectrum. They are then compressed by a notch‐rejecting filter. In contrast with the defects, the grey value of texture is limited within a certain range. Statistical process control binarisation, curve fitting and binary large object (blob) analysis are used to highlight defects.
Microwave coupler for W‐band micro re‐entrant square cavities
Authors: Paoloni Claudio , Mineo Mauro , Yin Huabi , Zhang Liang , He Wenlong , Robertson Craig W. , Ronald Kevin , Phelps Alan D.R. , Cross Adrian W.
Published: February 2016

Klystrons are vacuum electronic devices widely used for microwave amplification up to the millimetre‐wave region. The opportunity to push the operating frequency of conventional klystrons above 30–40 GHz is limited by the fabrication difficulties of the cavities that have very small dimensions. A high order mode micro re‐entrant square cavity was purposely devised to be compatible with the available micro fabrication processes and represents a viable solution for the design of millimetre‐wave klystrons. In this study, a coupler to correctly excite the higher order mode of the square re‐entrant cavities for W‐band operation is proposed. The design of the proposed novel coupler structure has been validated by realisation and measurement of a scaled X‐band prototype. The post‐realisation tuning methods adopted to improve the matching of the high order mode are also presented.
Speed control of electrical vehicles: a time‐varying proportional–integral controller‐based type‐2 fuzzy logic
Authors: Khooban Mohammad Hassan , Niknam Taher , Sha‐Sadeghi Mokhtar
Published: February 2016

The control of electrical vehicles (EVs) should be designed robustly and adaptively to improve the system on both dynamic and steady‐state performances, because EV systems are basically time variant (e.g. the operation parameters of EV and the road condition are always varying) that make the operation of controlling an EV difficult. In this study, general type‐2 fuzzy logic sets and the modified harmony search algorithm techniques for adaptive tuning of the most popular existing proportional–integral (PI) controller is integrated in order to address these uncertainties. Although it is computationally expensive to carry out general type‐2 fuzzy systems, it can be examined as a composition of several interval type‐2 fuzzy logic systems with a corresponding level of α for each by using a new plan which is presented, general type‐2 fuzzy set. The controller uses the linguistic rules directly. The achieved results are compared with optimal fuzzy‐PI controller and optimal interval type‐2 fuzzy‐PI controller results which are the most recent researches into in the present issue to evaluate the proficiency of the proposed controller. The simulation results demonstrate the successfulness and effectiveness of the proposed controller.
Risk Factors for Venous Thromboembolism following Thoracolumbar Surgery: Analysis of 43,777 Patients from the American College of Surgeons National Surgical Quality Improvement Program 2005 to 2012
Authors: Sebastian Arjun S. , Currier Bradford L. , Kakar Sanjeev , Nguyen Emily C. , Wagie Amy E. , Habermann Elizabeth S. , Nassr Ahmad
Published: February 2016

Study Design

Retrospective clinical study of a prospectively collected, national database.

Objective

Determine the 30-day incidence, timing, and risk factors for venous thromboembolism (VTE) following thoracolumbar spine surgery.

Methods

The American College of Surgeons National Surgical Quality Improvement Program Participant Use File identified 43,777 patients who underwent thoracolumbar surgery from 2005 to 2012. Multiple patient characteristics were identified. The incidence and timing (in days) of deep vein thrombosis (DVT) and pulmonary embolus (PE) were determined. Multivariable regression analysis was performed to identify significant risk factors.

Results

Of the 43,777 patients identified as having had thoracolumbar surgery, 202 cases of PE (0.5%) and 311 cases of DVT (0.7%) were identified. VTE rates were highest in patients undergoing corpectomy, with a 1.7% PE rate and a 3.8% DVT rate. Independent risk factors for VTE included length of stay (LOS) ≥ 6 days (odds ratio [OR] 4.07), disseminated cancer (OR 1.77), white blood cell count > 12 (OR 1.76), paraplegia (OR 1.75), albumin < 3 (OR 1.73), American Society of Anesthesiologists class 4 or greater (OR 1.54), body mass index > 40 (OR 1.49), and operative time > 193 minutes (OR 1.43). LOS < 3 days was protective (OR 0.427).

Conclusions

We report an overall 30-day PE rate of 0.5% and DVT rate of 0.7% following thoracolumbar spine surgery. Patients undergoing corpectomy were at highest risk for VTE. Multiple VTE risk factors were identified. Further studies are needed to develop algorithms to stratify VTE risk and direct prophylaxis accordingly.
Development of a low-drift integrator system on the HL-2A tokamak
Authors: Xu Yuan , Ji Xiaoquan , Yang Qingwei , Sun Tengfei , Yuan Baoshan , Liang Shaoyong , Ren Leilei , Zhou Jian
Published: February 2016

In this work, we developed a new integrator system with low-drift and small integration time constant less than 1 ms, which applies to the weak signals from magnetic measurements. This integrator system is designed on the basis of the analog drift compensation and the real-time digital correction of residual drift. The analog drift compensation is achieved by the subtraction between two integrators and the digital correction method is available due to the stability of integral drift in short time scale. The algorithm of the residual drift calculation and correction is implemented by the field programmable gate array. The integral drift can be well compensated within 10 mV/10 s at RC = 0.5 ms and meet the requirements of magnetic diagnostic on HL-2A.
Sub-Doppler infrared spectroscopy and formation dynamics of triacetylene in a slit supersonic expansion
Authors: Chang Chih-Hsuan , Agarwal Jay , Allen Wesley D. , Nesbitt David J.
Published: February 2016

Infrared spectroscopy and formation dynamics of triacetylene are investigated in a slit jet supersonic discharge and probed with sub-Doppler resolution (≈60 MHz) on the fundamental antisymmetric CH stretch mode (ν5). The triacetylene is generated in the throat of the discharge by sequential attack of ethynyl radical with acetyelene and diacetylene: (i) HCCH → HCC + H, (ii) HCC + HCCH → HCCCCH + H, (iii) HCC + HCCCCH → HCCCCCCH + H, cooled rapidly in the slit expansion to 15 K, and probed by near shot-noise-limited absorption sensitivity with a tunable difference-frequency infrared laser. The combination of jet cooled temperatures (Trot = 15 K) and low spectral congestion permits (i) analysis of rotationally avoided crossings in the ν5 band ascribed to Coriolis interactions, as well as (ii) first detection of ν5 Π–Π hot band progressions built on the ν12 sym CC bend and definitively assigned via state-of-the-art ab initio vibration-rotation interaction parameters (αi), which make for interesting comparison with recent spectroscopic studies of Doney et al. [J. Mol. Spectrosc. 316, 54 (2015)]. The combined data provide direct evidence for significantly non-equilibrium populations in the CC bending manifold, dynamically consistent with a strongly bent radical intermediate and transition states for forming triacetylene product. The presence of intense triacetylene signals under cold, low density slit jet conditions provides support for (i) barrierless addition of HCC with HCCCCH and (ii) a high quantum yield for HCCCCCCH formation. Complete basis set calculations for energetics [CCSD(T)-f12/VnZ-f12, n = 2,3] and frequencies [CCSD(T)-f12/VdZ-f12] are presented for both radical intermediate and transition state species, predicting collision stabilization in the slit jet expansion to be competitive with unimolecular decomposition with increasing polyyne chain length.
Characterizing the local solvation environment of OH− in water clusters with AIMD
Authors: Crespo Yanier , Hassanali Ali
Published: February 2016

In this work, we use ab initio molecular dynamics coupled with metadynamics to explore and characterize the glassy potential energy landscape of the OH− in a 20 and 48 water cluster. The structural, energetic, and topological properties of OH− are characterized for both clusters and the molecular origins of the IR signatures are examined. We find that in both the small and large clusters, the OH− can donate or accept a varying number of hydrogen bonds confirming that the amphiphilic character does not depend on cluster size. However, we highlight some important differences found between the energetic and topological properties of both families of clusters which may have implications on understanding the changes in the solvation structure of OH− between bulk and interfacial environments. By studying the IR spectra of smaller subsets of molecules within the 20 water molecule cluster, we find that the IR spectrum of the bare OH− as well as the water molecule donating a strong hydrogen bond to it exhibits characteristic absorption along the amphiphilic band between 1500 and 3000 cm−1 at positions very similar to those found for the entire hydroxide cluster. The results presented here will be useful in the calibration and improvement of both ab initio and semi-empirical methods to model this complex anion.
Isotopomer-selective spectra of a single intact H2O molecule in the Cs+(D2O)5H2O isotopologue: Going beyond pattern recognition to harvest the structural information encoded in vibrational spectra
Authors: Wolke Conrad T. , Fournier Joseph A. , Miliordos Evangelos , Kathmann Shawn M. , Xantheas Sotiris S. , Johnson Mark A.
Published: February 2016

We report the vibrational signatures of a single H2O molecule occupying distinct sites of the hydration network in the Cs+(H2O)6 cluster. This is accomplished using isotopomer-selective IR-IR hole-burning on the Cs+(D2O)5(H2O) clusters formed by gas-phase exchange of a single, intact H2O molecule for D2O in the Cs+(D2O)6 ion. The OH stretching pattern of the Cs+(H2O)6 isotopologue is accurately recovered by superposition of the isotopomer spectra, thus establishing that the H2O incorporation is random and that the OH stretching manifold is largely due to contributions from decoupled water molecules. This behavior enables a powerful new way to extract structural information from vibrational spectra of size-selected clusters by explicitly identifying the local environments responsible for specific infrared features. The Cs+(H2O)6 structure was unambiguously assigned to the 4.1.1 isomer (a homodromic water tetramer with two additional flanking water molecules) from the fact that its computed IR spectrum matches the observed overall pattern and recovers the embedded correlations in the two OH stretching bands of the water molecule in the Cs+(D2O)5(H2O) isotopomers. The 4.1.1 isomer is the lowest in energy among other candidate networks at advanced (e.g., CCSD(T)) levels of theoretical treatment after corrections for (anharmonic) zero-point energy. With the structure in hand, we then explore the mechanical origin of the various band locations using a local electric field formalism. This approach promises to provide a transferrable scheme for the prediction of the OH stretching fundamentals displayed by water networks in close proximity to solute ions.
Coarse-grained simulations of poly(propylene imine) dendrimers in solution
Authors: Smeijers A. F. , Markvoort A. J. , Pieterse K. , Hilbers P. A. J.
Published: February 2016

The behavior of poly(propylene imine) (PPI) dendrimers in concentrated solutions has been investigated using molecular dynamics simulations containing up to a thousand PPI dendrimers of generation 4 or 5 in explicit water. To deal with large system sizes and time scales required to study the solutions over a wide range of dendrimer concentrations, a previously published coarse-grained model was applied. Simulation results on the radius of gyration, structure factor, intermolecular spacing, dendrimer interpenetration, and water penetration are compared with available experimental data, providing a clear concentration dependent molecular picture of PPI dendrimers. It is shown that with increasing concentration the dendrimer volume diminishes accompanied by a reduction of internalized water, ultimately resulting in solvent filled cavities between stacked dendrimers. Concurrently dendrimer interpenetration increases only slightly, leaving each dendrimer a separate entity also at high concentrations. Moreover, we compare apparent structure factors, as calculated in experimental studies relying on the decoupling approximation and the constant atomic form factor assumption, with directly computed structure factors. We demonstrate that these already diverge at rather low concentrations, not because of small changes in form factor, but rather because the decoupling approximation fails as monomer positions of separate dendrimers become correlated at concentrations well below the overlap concentration.
Direct writing of birefringent elements by ultrafast laser nanostructuring in multicomponent glass
Authors: Fedotov S. S. , Drevinskas R. , Lotarev S. V. , Lipatiev A. S. , Beresna M. , Čerkauskaitė A. , Sigaev V. N. , Kazansky P. G.
Published: February 2016

Self-assembled nanostructures created by femtosecond laser irradiation are demonstrated in alkali-free aluminoborosilicate glass. The growth of the induced retardance associated with the nanograting formation is three orders of magnitude slower than in silica glass and is observed only within a narrow range of pulse energies. However, the strength of retardance asymptotically approaches the value typically measured in pure silica glass, which is attractive for practical applications. A similar intensity threshold for nanograting formation of about 1 TW/cm2 is observed for all glasses studied. The radially polarized vortex beam micro-converter designed as a space-variant quarter-wave retarder for the near-infrared spectral range is imprinted in commercial Schott AF32 glass.
Self-adjointness and domain of the Fröhlich Hamiltonian
Authors: Griesemer M. , Wünsch A.
Published: February 2016

In the large polaron model of Herbert Fröhlich, the electron-phonon interaction is a small perturbation in form sense, but a large perturbation in operator sense. This means that the form-domain of the Hamiltonian is not affected by the interaction but the domain of self-adjointness is. In the particular case of the Fröhlich model, we are nevertheless able, thanks to a recently published new operator bound, to give an explicit characterization of the domain in terms of a suitable dressing transform. Using the mapping properties of this dressing transform, we analyse the smoothness of vectors in the domain of the Hamiltonian with respect to the position of the electron.
Markov state models of protein misfolding
Authors: Sirur Anshul , De Sancho David , Best Robert B.
Published: February 2016

Markov state models (MSMs) are an extremely useful tool for understanding the conformational dynamics of macromolecules and for analyzing MD simulations in a quantitative fashion. They have been extensively used for peptide and protein folding, for small molecule binding, and for the study of native ensemble dynamics. Here, we adapt the MSM methodology to gain insight into the dynamics of misfolded states. To overcome possible flaws in root-mean-square deviation (RMSD)-based metrics, we introduce a novel discretization approach, based on coarse-grained contact maps. In addition, we extend the MSM methodology to include “sink” states in order to account for the irreversibility (on simulation time scales) of processes like protein misfolding. We apply this method to analyze the mechanism of misfolding of tandem repeats of titin domains, and how it is influenced by confinement in a chaperonin-like cavity.
Online beam energy measurement of Beijing electron positron collider II linear accelerator
Authors: Wang S. , Iqbal M. , Liu R. , Chi Y.
Published: February 2016

This paper describes online beam energy measurement of Beijing Electron Positron Collider upgraded version II linear accelerator (linac) adequately. It presents the calculation formula, gives the error analysis in detail, discusses the realization in practice, and makes some verification. The method mentioned here measures the beam energy by acquiring the horizontal beam position with three beam position monitors (BPMs), which eliminates the effect of orbit fluctuation, and is much better than the one using the single BPM. The error analysis indicates that this online measurement has further potential usage such as a part of beam energy feedback system. The reliability of this method is also discussed and demonstrated in this paper.
Development of a novel voltage divider for measurement of sub-nanosecond rise time high voltage pulses
Authors: Mitra S. , Senthil K. , Singh S. K. , Kumar Ranjeet , Sharma Archana
Published: February 2016

This paper is about the development of a copper sulphate based aqueous-electrolytic voltage divider for the measurement of high voltage pulses, 100 kV, with pulse widths of 1-2 ns and rise time <1 ns. Novel features are incorporated in the design of the divider, to meet the performance requirements for the application. Analytical calculations to justify design are described. Structural simulation of the divider is carried out using field wave simulation software to verify the effectiveness. A calibration procedure has been developed to calibrate the divider. Results obtained during calibration are subjected to statistical analysis to determine the confidence of measurement. Details of design, analysis, and simulation are described in this paper.
Mechanical design and fabrication of the VHF-gun, the Berkeley normal-conducting continuous-wave high-brightness electron source
Authors: Wells R. P. , Ghiorso W. , Staples J. , Huang T. M. , Sannibale F. , Kramasz T. D.
Published: February 2016

A high repetition rate, MHz-class, high-brightness electron source is a key element in future high-repetition-rate x-ray free electron laser-based light sources. The VHF-gun, a novel low frequency radio-frequency gun, is the Lawrence Berkeley National Laboratory (LBNL) response to that need. The gun design is based on a normal conducting, single cell cavity resonating at 186 MHz in the VHF band and capable of continuous wave operation while still delivering the high accelerating fields at the cathode required for the high brightness performance. The VHF-gun was fabricated and successfully commissioned in the framework of the Advanced Photo-injector EXperiment, an injector built at LBNL to demonstrate the capability of the gun to deliver the required beam quality. The basis for the selection of the VHF-gun technology, novel design features, and fabrication techniques are described.
Photoelectron spectra of 2-thiouracil, 4-thiouracil, and 2,4-dithiouracil
Authors: Ruckenbauer Matthias , Mai Sebastian , Marquetand Philipp , González Leticia
Published: February 2016

Ground- and excited-state UV photoelectron spectra of thiouracils (2-thiouracil, 4-thiouracil, and 2,4-dithiouracil) have been simulated using multireference configuration interaction calculations and Dyson norms as a measure for the photoionization intensity. Except for a constant shift, the calculated spectrum of 2-thiouracil agrees very well with experiment, while no experimental spectra are available for the two other compounds. For all three molecules, the photoelectron spectra show distinct bands due to ionization of the sulphur and oxygen lone pairs and the pyrimidine π system. The excited-state photoelectron spectra of 2-thiouracil show bands at much lower energies than in the ground state spectrum, allowing to monitor the excited-state population in time-resolved UV photoelectron spectroscopy experiments. However, the results also reveal that single-photon ionization probe schemes alone will not allow monitoring all photodynamic processes existing in 2-thiouracil. Especially, due to overlapping bands of singlet and triplet states the clear observation of intersystem crossing will be hampered.
Construction of a 3He magnetic force microscope with a vector magnet
Authors: Yang Jinho , Yang Ilkyu , Kim Yun Won , Shin Dongwoo , Jeong Juyoung , Wulferding Dirk , Yeom Han Woong , Kim Jeehoon
Published: February 2016

We constructed a 3He magnetic force microscope operating at the base temperature of 300 mK under a vector magnetic field of 2-2-9 T in the x–y–z direction. Fiber optic interferometry as a detection scheme is employed in which two home-built fiber walkers are used for the alignment between the cantilever and the optical fiber. The noise level of the laser interferometer is close to its thermodynamic limit. The capabilities of the sub-Kelvin and vector field are demonstrated by imaging the coexistence of magnetism and superconductivity in a ferromagnetic superconductor (ErNi2B2C) at T = 500 mK and by probing a dipole shape of a single Abrikosov vortex with an in-plane tip magnetization.
The light diffraction effect on stimulated Raman scattering
Authors: Liu Z. J. , Li B. , Hu X. Y. , Xiang J. , Zheng C. Y. , Cao L. H. , Hao L.
Published: February 2016

The stimulated Raman scattering is simulated with different size of incident light using code LAP3D. The reflectivity of Raman scattering is very sensitive to the size of single speckle of the incident light. Small reflectivity is obtained when width of speckle is small, which is explained by the effect of light diffraction. For inhomogeneous plasma, the reflectivity is larger with a positive density gradient than that with a negative density gradient, which is consistent with the theory result. The incident light smoothed by the continuous phase plate contains many speckles and has an intensity distribution. The fractional power above intensity profile is very important, because the high intensity power can excite the stimulated Raman scattering and reduce the threshold of average intensity.
Observation of second order ion acoustic Peregrine breather in multicomponent plasma with negative ions
Authors: Pathak Pallabi , Sharma S. K. , Nakamura Y. , Bailung H.
Published: February 2016

The experimental observation of second order ion acoustic Peregrine breathers in multicomponent plasma with negative ions is reported. A long wavelength initial perturbation on a continuous carrier frequency ∼0.5 ωpi (where ωpi is the ion plasma frequency) of finite amplitude is found to undergo self-modulation due to the interplay between nonlinear dispersive effect and group velocity dispersion because of modulational instability. Wave energy focusses to a smaller localized and isolated group of waves within the packet with amplitude amplification up to 5 times of the background carrier wave. The experimental results are compared with second order breather solution of nonlinear Schrodinger equation. The wavelet analysis and fast Fourier transform analysis of the experimental time series data indicate strong nonlinear evolution (wave energy focusing and spectral broadening) conforming to the formation of second order Peregrine solitons.
Tracking three-phase coexistences in binary mixtures of hard plates and spheres
Authors: Aliabadi Roohollah , Moradi Mahmood , Varga Szabolcs
Published: February 2016

The stability of demixing phase transition in binary mixtures of hard plates (with thickness L and diameter D) and hard spheres (with diameter σ) is studied by means of Parsons-Lee theory. The isotropic-isotropic demixing, which is found in mixtures of large spheres and small plates, is very likely to be pre-empted by crystallization. In contrast, the nematic-nematic demixing, which is obtained in mixtures of large plates and small spheres, can be stabilized at low diameter ratios (σ/D) and aspect ratios (L/D). At intermediate values of σ/D, where the sizes of the components are similar, neither the isotropic-isotropic nor the nematic-nematic demixing can be stabilized, but a very strong fractionation takes place between a plate rich nematic and a sphere rich isotropic phases. Our results show that the excluded volume interactions are capable alone to explain the experimental observation of the nematic-nematic demixing, but they fail in the description of isotropic-isotropic one [M. Chen et al., Soft Matter 11, 5775 (2015)].
Enhanced thermoelectric performance of CuGaTe2 based composites incorporated with graphite nanosheets
Authors: Zhang Jian , Qin Xiaoying , Li Di , Liu Yongfei , Li Yuanyue , Song Chunjun , Xin Hongxing , Zhu Xiaoguang
Published: February 2016

CuGaTe2 based composites incorporated with graphite nanosheets (GNs) CuGaTe2/x G (G = GNs, 0 ≤ x ≤ 3.04 vol. %) were prepared, and the thermoelectric properties of the composites were studied from 300 to 875 K. The results show that the incorporation of GNs into the CuGaTe2 matrix can enhance the Seebeck coefficient and power factor over the whole temperature range investigated due to energy filtering effects, and the reduction of thermal conductivity below 750 K owing to interface scattering. Although the resistivity increases, energy filtering significantly raises the Seebeck component, and the overall effect on power factor is positive. The sample with 2.28 vol. % GNs had the largest ZT value, reaching 0.93 at 873 K, which is a ∼21% improvement on pure CuGaTe2.
Investigation of ionization-induced electron injection in a wakefield driven by laser inside a gas cell
Authors: Audet T. L. , Hansson M. , Lee P. , Desforges F. G. , Maynard G. , Dobosz Dufrénoy S. , Lehe R. , Vay J.-L. , Aurand B. , Persson A. , Gallardo González I. , Maitrallain A. , Monot P. , Wahlström C.-G. , Lundh O. , Cros B.
Published: February 2016

Ionization-induced electron injection was investigated experimentally by focusing a driving laser pulse with a maximum normalized potential of 1.2 at different positions along the plasma density profile inside a gas cell, filled with a gas mixture composed of 99%H2+1%N2. Changing the laser focus position relative to the gas cell entrance controls the accelerated electron bunch properties, such as the spectrum width, maximum energy, and accelerated charge. Simulations performed using the 3D particle-in-cell code WARP with a realistic density profile give results that are in good agreement with the experimental ones. The interest of this regime for optimizing the bunch charge in a selected energy window is discussed.
Photoluminescence based H2 and O2 gas sensing by ZnO nanowires
Authors: Yadav Kavita , Gahlaut Shashank K. , Mehta B. R. , Singh J. P.
Published: February 2016

Gas sensing properties of ZnO nanowires prepared via thermal chemical vapor deposition method were investigated by analyzing change in their photoluminescence (PL) spectra. The as-synthesized nanowires show two different PL peaks positioned at 380 nm and 520 nm. The 380 nm emission is ascribed to near band edge emission, and the green peak (520 nm) appears due to the oxygen vacancy defects. The intensity of the green PL signal enhances upon hydrogen gas exposure, whereas it gets quenched upon oxygen gas loading. The ZnO nanowires' sensing response values were observed as about 54% for H2 gas and 9% for O2 gas at room temperature for 50 sccm H2/O2 gas flow rate. The sensor response was also analyzed as a function of sample temperature ranging from 300 K to 400 K. A conclusion was derived from the observations that the H2/O2 gases affect the adsorbed oxygen species on the surface of ZnO nanowires. The adsorbed species result in the band bending and hence changes the depletion region which causes variation in PL signal. A photoluminescence based gas sensing technique has advantage over a conductometric technique due to its higher sensitivity and faster response time.
Large tensile superelasticity from intermartensitic transformations in Ni49Mn28Ga23 single crystal
Authors: Chernenko V. A. , Villa E. , Salazar D. , Barandiaran J. M.
Published: February 2016

A multistep superelastic behavior, with up to a 12% strain, is reported in a 〈001〉P-oriented Ni49Mn28Ga23 single crystal. The observed behavior is produced by intermartensitic transformations during the tensile stress–strain measurements at temperatures between −140 °C and +60 °C. The tensile stress–temperature phase diagram and the stress dependence of the intermartensitic transformation entropies have been obtained. These results provide important input for theoretical modeling of the phase transformations in these alloys and show promising mechanical properties of the classical Ni-Mn-Ga ferromagnetic shape memory alloys.
Indirect excitons in a potential energy landscape created by a perforated electrode
Authors: Dorow C. J. , Kuznetsova Y. Y. , Leonard J. R. , Chu M. K. , Butov L. V. , Wilkes J. , Hanson M. , Gossard A. C.
Published: February 2016

We report on the principle and realization of an excitonic device: a ramp that directs the transport of indirect excitons down a potential energy gradient created by a perforated electrode at a constant voltage. The device provides an experimental proof of principle for controlling exciton transport with electrode density gradients. We observed that the exciton transport distance along the ramp increases with increasing exciton density. This effect is explained in terms of disorder screening by repulsive exciton-exciton interactions.
Communication: Determination of relativistic effects from X-ray structure factors
Authors: Batke Kilian , Eickerling Georg
Published: February 2016

In this communication, a procedure is presented which allows for the determination of the scalar-relativistic contraction of individual electronic shells of transition metal atoms from X-ray structure factor data. The procedure is verified and benchmarked employing theoretical and experimental F(hkl) data, revealing an overall good agreement between the experimentally determined results and the theoretical reference values. From the experimental data, the relativistic contraction of the n = 2 shell of a cerium atom is, for example, determined as 0.097 pm, compared to a theoretical reference value of 0.116 pm. It is further demonstrated that the reproducibility of the results is excellent when comparing different experimental data sets. Finally, the dependency of the according results on the data resolution of the structure factor data is investigated.
Large-gap quantum spin Hall state in functionalized dumbbell stanene
Authors: Wang Ya-ping , Ji Wei-xiao , Zhang Chang-wen , Li Ping , Li Feng , Wang Pei-ji , Li Sheng-shi , Yan Shi-shen
Published: February 2016

Two-dimensional dumbbell (DB) stanene has been proposed as a promising candidate material for realizing quantum spin Hall effect (QSHE) by Tang et al. [Phys. Rev. B 90, 121408 (2014)]. However, the small bulk-gap limits its possible applications at room temperature. Based on first-principles calculations, we predict that its band gap can be enhanced to 148 meV under methyl-functionalization, which can be further tuned by applying lattice strain. The QSHE is confirmed by s-px,y band inversion, topological invariant Z2 = 1, and helical gapless edge within bulk band gap. Notably, the characteristic properties of edge states, such as the large Fermi velocity and Dirac cone, can be modulated by edge modification. The effects of substrates on topological properties are explored when it is grown on various substrates, like SiC, h-BN, and Bi2Te3 sheets. These findings provide significant guidance for future fabrication and realistic applications of QSHE based on stanene in spintronics.
CuO/ZnO memristors via oxygen or metal migration controlled by electrodes
Authors: Huang Yong , Shen Zihan , Wu Ye , Xie Meiqiu , Hu Yanqiang , Zhang Shufang , Shi Xiaoqin , Zeng Haibo
Published: February 2016

We carry out a comparative study on resistive switching in CuO/ZnO bilayer films; both samples grown Pt and Ag electrodes show bipolar switching behaviors. The two kinds of current-voltage curves reveal the different resistive switching behaviors in Pt/CuO/ZnO/Pt and Ag/CuO/ZnO/Pt, respectively. We conjecture that the formation and rupture of conducting filaments are responsible for the switching effect. Filaments induced by migration of oxygen ions are responsible for resistive switching with the Pt electrode. In contrast, resistive switching with the Ag electrode is attributed to the migration of metal cations and the corresponding electrochemical metallization. It is also inferred that the characteristic nature of the conducting filaments influences many aspects of switching characteristics, including the switching voltages and cycling variations at room temperature.
Phosphorus-utilisation efficiency and leaf-morphology traits of Rytidosperma species (wallaby grasses) that differ in their growth response to phosphorus fertilisation
Authors: Waddell Heidi A. , Simpson Richard J. , Lambers Hans , Henderson Brent , Ryan Megan H. , Garden Denys L. , Richardson Alan E.
Published: February 2016

Rytidosperma species are perennial grasses found in cool temperate grasslands of Australia. The species differ in their intrinsic growth rates, response to phosphorus (P) fertiliser application and critical external P requirements (P required for 90% maximum growth). The present study examined whether internal P-utilisation efficiency (PUE) by Rytidosperma species influenced these differences. The PUE of nine Rytidosperma species and two grasses of Mediterranean origin, Bromus hordeaceus L. and Lolium perenne L., was assessed using alternative measures of shoot P concentration or its reciprocal. No measure of PUE was correlated with the critical external P requirements of the species. One measure of PUE, shoot dry matter per unit P, when assessed at a common shoot P content was correlated with potential growth rate (P < 0.001; r = 0.93; 4 mg shoot P). However, other measures of PUE were not correlated with potential growth rates. All of the fast-growing species (B. hordeaceus, L. perenne, Rytidosperma duttonianum (Cashmore) Connor & Edgar and Rytidosperma richardsonii (Cashmore) Connor & Edgar) exhibited high PUE, whereas PUE varied substantially among the slower-growing species. The fast-growing Rytidosperma species differed in the contribution that area-based P concentration of leaves and specific leaf area (SLA) made to the achievement of high PUE, and they retained shoot-morphology traits normally associated with slow-growing species such as smaller leaf area, smaller SLA and higher leaf dry matter content.
Infants use relative numerical group size to infer social dominance
Authors: Pun Anthea , Birch Susan A. J. , Baron Andrew Scott
Published: February 2016

Significance

The ability to detect dominance relationships is essential for survival because it helps individuals weigh the potential costs and benefits of engaging in a physical competition. Here we show that infants as young as 6 mo of age are capable of detecting dominance relations when provided with an ecologically relevant cue such as social group size. Furthermore, infants can infer the social dominance relationship between two competing individuals based on the size of the group to which they belong, and expect individuals from a numerically larger group to get their way. These findings reveal that infants may have an evolutionarily ancient cognitive capacity to represent social dominance relations that is shared with other species within the animal kingdom.
Deep phenotyping of 89 xeroderma pigmentosum patients reveals unexpected heterogeneity dependent on the precise molecular defect
Authors: Fassihi Hiva , Sethi Mieran , Fawcett Heather , Wing Jonathan , Chandler Natalie , Mohammed Shehla , Craythorne Emma , Morley Ana M. S. , Lim Rongxuan , Turner Sally , Henshaw Tanya , Garrood Isabel , Giunti Paola , Hedderly Tammy , Abiona Adesoji , Naik Harsha , Harrop Gemma , McGibbon David , Jaspers Nicolaas G. J. , Botta Elena , Nardo Tiziana , Stefanini Miria , Young Antony R. , Sarkany Robert P. E. , Lehmann Alan R.
Published: February 2016

Significance

Xeroderma pigmentosum (XP) is a genetic disorder caused by defective repair of DNA damage. Affected patients are mutated in one of eight genes and develop skin pigmentation changes, skin cancers, ocular surface abnormalities, and, in some cases, acute sunburn and neurodegeneration. The XP proteins are involved in different steps in the repair of DNA damage. Examination of 89 patients, the largest reported cohort under long-term follow-up, by the same multidisciplinary team of clinicians and scientists has revealed unexpected clinical heterogeneity dependent on the affected gene and the exact mutation. Our findings provide new insights into the mechanisms of carcinogenesis, ocular surface disease, and neurodegeneration, as well as providing improved clinical management and more definitive prognostic predictions.
Gene control of tyrosine kinase
TIE2
and vascular manifestations of infections
Authors: Ghosh Chandra C. , David Sascha , Zhang Ruyang , Berghelli Anthony , Milam Katelyn , Higgins Sarah J. , Hunter Jon , Mukherjee Aditi , Wei Yongyue , Tran Mei , Suber Freeman , Kobzik Lester , Kain Kevin C. , Lu Shulin , Santel Ansgar , Yano Kiichiro , Guha Prajna , Dumont Daniel J. , Christiani David C. , Parikh Samir M.
Published: February 2016

Significance

Major infections, such as influenza and bacterial sepsis, kill millions of individuals yearly, most commonly from complications affecting the vasculature, such as acute respiratory distress syndrome. Poor outcomes from rare infections, such as Ebola virus disease, have also been linked to the vasculature. The basis for prominent vascular involvement in infectious syndromes remains poorly understood. The present work shows that humans exhibit common, yet highly consequential, genetic variation in the ability to sustain expression of a key homeostatic vascular receptor called tunica interna endothelial cell kinase 2. The results suggest that host determinants of the molecular vascular response to infection may have a heretofore underappreciated impact on clinical outcomes. They also suggest new means to identify at-risk individuals and personalize future therapies.
A highly precise and portable genome engineering method allows comparison of mutational effects across bacterial species
Authors: Nyerges Ákos , Csörgő Bálint , Nagy István , Bálint Balázs , Bihari Péter , Lázár Viktória , Apjok Gábor , Umenhoffer Kinga , Bogos Balázs , Pósfai György , Pál Csaba
Published: February 2016

Significance

Current tools for bacterial genome engineering suffer from major limitations. They have been optimized for a few laboratory model strains, lead to the accumulation of numerous undesired, off-target modifications, and demand extensive modification of the host genome prior to large-scale editing. Herein, we address these problems and present a simple, all-in-one solution. By utilizing a highly conserved mutant allele of the bacterial mismatch-repair system, we were able to gain unprecedented precision in the control over the generation of desired modifications in multiple bacterial species. These results have broad implications with regards to both biotechnological and clinical applications.
The light chains of kinesin-1 are autoinhibited
Authors: Yip Yan Y. , Pernigo Stefano , Sanger Anneri , Xu Mengjia , Parsons Maddy , Steiner Roberto A. , Dodding Mark P.
Published: February 2016

Significance

Despite its importance for a host of cellular processes and contribution to neurological, viral, and bacterial disease, the molecular mechanisms underlying the regulation of the heterotetrameric motor kinesin-1 by its light chains and the binding of its cargo are not well understood. Here, we describe how a previously unnoticed intramolecular interaction between the light chain tetratricopeptide repeat domain (KLC2
TPR
) and a highly conserved peptide motif within an unstructured region of the molecule occludes a key cargo binding site on the light-chain TPR domain. Cargo binding displaces this intramolecular interaction, effecting a global overall conformational change in KLCs that results in a more extended conformation. We propose a model describing how, via this molecular switch, cargo binding regulates the activity of the holoenzyme.