bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetically directed soft actuators driven by moisture
Authors: Gao Fengxian , Zhang Ning , Fang Xiaodong , Ma Mingming
Published: March 2017

Herein we report the fabrication of a moisture-driven actuator capable of performing directional motion, by incorporating superparamagnetic nanoparticles into a water-responsive polypyrrole film.
Vascular basement membrane alterations and β-amyloid accumulations in an animal model of cerebral small vessel disease
Authors: Held Friederike , Morris Alan W.J. , Pirici Daniel , Niklass Solveig , Sharp Matthew M.G. , Garz Cornelia , Assmann Anne , Heinze Hans-Jochen , Schreiber Frank , Carare Roxana Octavia , Schreiber Stefanie
Published: March 2017

Non-amyloid cerebral small vessel disease (CSVD) and cerebral amyloid angiopathy (CAA) may be interrelated through the damaged basement membranes (BMs) and extracellular matrix changes of small vessels, resulting in a failure of β-amyloid (Aβ) transport and degradation. We analyzed BM changes and the pattern of deposition of Aβ in the walls of blood vessels in spontaneously hypertensive stroke-prone rats (SHRSP), a non-transgenic CSVD model. In 45 SHRSP and 38 Wistar rats aged 18 to 32 weeks: (i) the percentage area immunostained for vascular collagen IV and laminin was quantified; (ii) the capillary BM thickness as well as endothelial and pericyte pathological changes were analysed using transmission electron microscopy (TEM); and (iii) the presence of vascular Aβ was assessed. Compared with controls, SHRSP exhibited a significantly higher percentage area immunostained with collagen IV in the striatum and thalamus. SHRSP also revealed an age-dependent increase of the capillary BM thickness and of endothelial vacuoles (caveolae) within subcortical regions. Endogenous Aβ deposits in the walls of small blood vessels were observed in the cortex (with the highest incidence found within fronto-parietal areas), striatum, thalamus and hippocampus. Vascular β-amyloid accumulations were frequently detected at sites of small vessel wall damage. Our data demonstrate changes in the expression of collagen IV and of the ultrastructure of BMs in the small vessels of SHRSP. Alterations are accompanied by vascular deposits of endogenous Aβ. Impaired β-amyloid clearance along perivascular and endothelial pathways and failure of extracellular Aβ degradation may be the key mechanisms connecting non-amyloid CSVD and CAA.
Child–Adult Differences in Using Dual-Task Paradigms to Measure Listening Effort
Authors: Picou Erin M. , Charles Lauren M. , Ricketts Todd A.
Published: March 2017

Purpose

The purpose of the project was to investigate the effects modifying the secondary task in a dual-task paradigm to measure objective listening effort. To be specific, the complexity and depth of processing were increased relative to a simple secondary task.

Method

Three dual-task paradigms were developed for school-age children. The primary task was word recognition. The secondary task was a physical response to a visual probe (simple task), a physical response to a complex probe (increased complexity), or word categorization (increased depth of processing). Sixteen adults (22–32 years,
M
= 25.4) and 22 children (9–17 years,
M
= 13.2) were tested using the 3 paradigms in quiet and noise.

Results

For both groups, manipulations of the secondary task did not affect word recognition performance. For adults, increasing depth of processing increased the calculated effect of noise; however, for children, results with the deep secondary task were the least stable.

Conclusions

Manipulations of the secondary task differentially affected adults and children. Consistent with previous findings, increased depth of processing enhanced paradigm sensitivity for adults. However, younger participants were more likely to demonstrate the expected effects of noise on listening effort using a secondary task that did not require deep processing.
Imposing voltage security and network radiality for reconfiguration of distribution systems using efficient heuristic and meta‐heuristic approach
Authors: Kumar Pawan , Ali Ikbal , Thomas Mini S. , Singh Surjit
Published: March 2017

In a deregulated energy market, voltage security (VS) is one of the major concerns, as it improves the loadability limits, loading profiles while concurrently reducing power loss. Further, voltage dependent loads can operate at high efficiency at rated voltage. Therefore, power utilities have to explore options of reconfiguration to secure the voltage level under frequently changing operating conditions. In this study, an efficient heuristic and meta‐heuristic (harmony search) approach for reconfiguration is proposed by imposing VS. Two indices namely node voltage security index (NVSI) and node voltage quality index are developed for aggregated improvement in node voltages. Moreover, efficient methodologies for identification of new tie‐lines, network radiality and the load flow solution are also presented. The effectiveness of the proposed index and the methodology is tested for reconfiguration of various distribution systems and the results are obtained with reduced computational efforts.
Broadband slot cut shorted sectoral microstrip antennas
Authors: Deshmukh Amit A.
Published: March 2017

Slot cut variations of shorted sectoral microstrip antennas are proposed which yields bandwidth of more than 900 MHz (>75%). Formulation in resonant length at modified shorted patch modes is presented. Frequencies calculated using them show close agreement with simulated results. Using proposed formulations, procedure to design slot cut shorted sectoral antennas at different frequency is presented, which gives wideband response. Thus, proposed work gives guidelines to design shorted compact antennas at any given frequency.
Heptaband swastik arm antenna for MIMO applications
Authors: Rajkumar Sampath , Vivek Sivaraman Narayanaswamy , Murali Sharada , Selvan Krishnasamy T.
Published: March 2017

In this study, a two‐element multiple‐input–multiple‐output (MIMO) antenna with heptaband characteristics is proposed. The total size of the proposed antenna is 82 × 40 × 0.8 mm3. The geometry of the radiating element is derived from a hybrid Quadric–Koch island fractal for size miniaturisation. The antenna operates at the bands of 0.95–1.02 GHz (GSM 900), 1.73–1.79 GHz (GSM 1800), 2.68–2.85 GHz (LTE‐A), 3.66–3.7 GHz [ultra‐wideband (UWB)], 4.20–4.40 GHz (UWB), 5.50–5.65 GHz [worldwide interoperability for microwave access/high‐performance radio local area network] and 5.93–6.13 GHz (UWB). The spacing between the two radiating elements is maintained at 5 mm. The proposed heptaband swastik arm MIMO antenna exhibits an S11 ≤ −6 dB and S21 ≤ −17 dB over the entire bands of operation. It provides high isolation without requiring any additional structures. The antenna also offers stable radiation characteristics with circular polarisation at the operating bands of 3.66–3.7 GHz and 5.93–6.13 GHz and linear polarisation at 0.95–1.02 GHz, 1.73–1.79 GHz, 2.68–2.85 GHz, 4.20–4.40 GHz and 5.50–5.65 GHz bands. The diversity performance of the antenna is studied in terms of the envelope correlation coefficient which is <0.05, and capacity loss which is <0.5 bits/s/Hz at all the operating frequencies, making it suitable for use in fifth generation communication systems incorporating the existing bands.
Multilevel inverter topology using single source and double source module with reduced power electronic components
Authors: Vinoth Kumar Nagaraj , Kumar Chinnaiyan Venkatachalam , Murukesapillay Pradish , Prabhakar Karthikeyan Shanmugam
Published: March 2017

Two‐level inverters are the most basic subset of multi‐level inverters (MLIs). As the number of output levels increase, total harmonic distortion reduces and the performance level increases. In traditional MLI topologies, more number of power devices are involved to obtain higher order inverters which increases cost, complexity and volume. By minimising the use of power component, overall cost can be reduced. In this study, a MLI structure is proposed with minimised power components. The reduction of components are achieved through single and double source modules such as single source and single switch, single source and switch with parallel diode and double source and single switch with parallel diode. In the proposed MLI structure, the switches are reduced by half in comparison with cascaded MLI and hence the percentage in reduction of switches increase as the levels increase. For better appreciation, the proposed topology is compared with the current state of the art in MLI. This topology is modelled and simulated using LTspice and MATLAB/SIMULINK R2014 a. The prototype is designed and validated for seven and nine levels experimentally.
Kinetic study of electrostatic twisted waves instability in nonthermal dusty plasmas
Authors: Arshad Kashif , Lazar M. , Mahmood Shahzad , Aman-ur-Rehman  , Poedts S.
Published: March 2017

The kinetic theory of electrostatic twisted waves' instability in a dusty plasma is developed in the presence of orbital angular momentum of the helical (twisted) electric field in plasmas with kappa distributed electrons, ions, and dust particles. The kappa distributed electrons are considered to have a drift velocity. The perturbed distribution function and helical electric field are decomposed by Laguerre-Gaussian mode functions defined in cylindrical geometry. The Vlasov-Poisson equation is obtained and solved analytically to investigate the growth rates of the electrostatic twisted waves in a non-thermal dusty plasma. The growth rates of the dust ion acoustic twisted mode (DIATM) and dust acoustic twisted mode (DATM) are obtained analytically and also pictorial presented numerically. The instability condition for the DIATM and DATM is also discussed with different plasma parameters. The growth rates of DIATM and DATM are larger when the drifted electrons are non-Maxwellian distributed and smaller for the Maxwellian distributed drifted electrons in the presence of the helical electric field.
The exact solution of one-dimensional nonrelativistic Vlasov equation: Antitropic electron beams and Landau damping
Authors: Stepanov Nikolay S. , Zelekson Lev A.
Published: March 2017

The exact stationary solution of one-dimensional non-relativistic Vlasov equation is obtained in the article. It is shown that in the energy exchange with the self-consistent longitudinal electric field, both wave trapped charged particles and the passing ones take part. It is proved that the trapped electron distribution is fundamentally different from distribution functions described by other authors, which used the Bernstein, Greene, and Kruskal method. So, the correct distribution function is characterized by its sudden change at the equality of wave and electrons' velocity but not on the edges of the potential well. This jump occurs for any arbitrary small value of wave potential. It was also found that the energy density of fast electrons trapped by the wave is less than the energy density of slow trapped electrons. This leads to the fact that the energy of the self-consistent electric field may both increase and decrease due to the nonlinear Landau damping. The conditions under which a similar effect can be observed are defined. Also for the first time, it is shown that the self-generated strong electric field always produces antitropic electron beams.
Effect of background ionization on plasma ignition dynamics
Authors: Qiu Y. , Xian Y. , Lu X. , Ostrikov K.
Published: March 2017

The influence of background ionization on the ignition dynamics of the pulsed plasma plume is studied. The ignition delay time of each pulse is investigated by recording the voltage signal and the light emission signal. By changing the frequency, the relationship between the pulse-off time and the ignition delay time is revealed. This indicates that residual active species produced in the previous discharge play a role in the next one. With the decrease in the frequency, both time delay and ignition delay time increase. This is due to the decay of the reactive species densities in the pulse-off time. Lower concentrations of these species lead to a longer ignition delay time. The functions for calculating the ignition delay time are utilized to explain the effect of residual species. The independent data of each discharge also evidence the impact of the previous pulse. The exotic relationship between the ignition delay times of the first two pulses may be due to the electrode configuration used in this work. For a pin-to-plane electrode structure, the active species produced during the breakdown are accumulated around the anode (pin-point) where the discharge initiated for the asymmetrical electric field distribution.
Decreasing Brillouin and Raman scattering by alternating-polarization light
Authors: Liu Z. J. , Zheng C. Y. , Cao L. H. , Li B. , Xiang J. , Hao L.
Published: March 2017

A new method to reduce the scattering levels of stimulated Raman scattering (SRS) and stimulated Brillouin (SBS) scattering is proposed using alternating-polarization light. The effect of the new technique is related to the alternating time. If the alternating time is smaller than the growth time, the scattering level of SRS or SBS can be decreased. The SBS process is simulated by the fluid method, and the SRS process is verified by the particle-in-cell method. This method is also compared with the spike trains of uneven duration and delay (STUD) technique. Combining STUD pulses with alternating-polarization light is also discussed. Under proper alternating-polarization parameters, the scattering level of SRS and SBS can be dramatically reduced by more than one order of magnitude.
Semi-analytic model of plasma-jet-driven magneto-inertial fusion
Authors: Langendorf Samuel J. , Hsu Scott C.
Published: March 2017

A semi-analytic model for plasma-jet-driven magneto-inertial fusion is presented. Compressions of a magnetized plasma target by a spherically imploding plasma liner are calculated in one dimension (1D), accounting for compressible hydrodynamics and ionization of the liner material, energy losses due to conduction and radiation, fusion burn and alpha deposition, separate ion and electron temperatures in the target, magnetic pressure, and fuel burn-up. Results show 1D gains of 3–30 at spherical convergence ratio <15 and 20–40 MJ of liner energy, for cases in which the liner thickness is 1 cm and the initial radius of a preheated magnetized target is 4 cm. Some exploration of parameter space and physics settings is presented. The yields observed suggest that there is a possibility of igniting additional dense fuel layers to reach high gain.
Plasticity and optical properties of GaN under highly localized nanoindentation stress fields
Authors: Caldas P. G. , Silva E. M. , Prioli R. , Huang J. Y. , Juday R. , Fischer A. M. , Ponce F. A.
Published: March 2017

Nanoscale plasticity has been studied on (0001) GaN thin films, using tips with very small radius of curvature. Cross-section transmission electron microscopy images of the nanoindentations indicate that the primary slip systems are the pyramidal {11¯01}⟨112¯3⟩ and {112¯2}⟨112¯3⟩, followed by the basal {0002}⟨112¯0⟩. Incipient plasticity was observed to be initiated by metastable atomic-scale slip events that occur as the crystal conforms to the shape of the tip. Large volumetric material displacements along the {11¯01}⟨112¯3⟩ and {112¯2}⟨112¯3⟩ slip systems were observed at an average shear stress of 11 GPa. Hexagonal shaped nanoindentation impressions following the symmetry of GaN were observed, with material pile-up in the ⟨112¯0⟩ directions. Spatially resolved cathodoluminescence images were used to correlate the microstructure with the optical properties. A large number of non-radiative defects were observed directly below the indentation. Regions under tensile stress extending from the nanoindentation along ⟨112¯0⟩ directions were associated with the {0002}⟨112¯0⟩ slip.
Invited Article: Chiral optics of helicoidal cellulose nanocrystal films
Authors: Wilts B. D. , Dumanli A. G. , Middleton R. , Vukusic P. , Vignolini S.
Published: March 2017

Cellulose nanocrystals in water suspensions behave as lyotropic liquid crystals forming a chiral nematic phase above a critical concentration. Such an organization can be retained in solid films and give rise to an intense colored appearance. Here, we characterize their optical response by applying optical and scanning electron microscopy, imaging scatterometry, and angle-resolved reflectance measurements. We show that the experimental results are well explained by computational modeling using the finite-difference time-domain method, but slightly less well by Berremann’s analytical model.
The role of the plasma current in turbulence decrease during lower hybrid current drive
Authors: Antar G. , Ekedahl A. , Goniche M. , Asghar A. , Žàček F.
Published: March 2017

The interaction of radio frequency (RF) waves with edge turbulence has resurfaced after the results obtained on many tokamaks showing that edge turbulence decreases when the ion cyclotron frequency heating (ICRH) is switched on. Using the lower hybrid (LH) waves to drive current into tokamak plasmas, this issue presented contradicting results with some tokamaks (FTU & HT-7) showing a net decrease, similar to the ICRH results, and others (Tore Supra) did not. In this article, these apparent discrepancies among tokamaks and RF wave frequencies are removed. It is found that turbulence large-scale structures in the scrape-off layer decrease at high enough plasma currents (Ip) on the Tore Supra tokamak. We distinguish three regimes: At low Ip's, no modification is detected with statistical properties of turbulence similar to ohmic plasmas even with PLH reaching 4.8 MW. At moderate plasma currents, turbulence properties are modified only at a high LH power. At high plasma currents, turbulent large scales are reduced to values smaller than 1 cm, and this is accompanied by a net decrease in the level of turbulence of about 30% even with a moderate LH power.
Driving force for a nonequilibrium phase transition in three-dimensional complex plasmas
Authors: Zhukhovitskii D. I.
Published: March 2017

An example of the non-equilibrium phase transition is the formation of lanes when one kind of particle is driven against the other. According to experimental observation, lane formation in binary complex plasmas occurs when the smaller particles are driven through the stationary dust cloud of the larger particles. We calculate the driving force acting on a probe particle that finds itself in a quiescent cloud of particles in complex plasma of the low-pressure radio frequency discharge under microgravity conditions. It is shown that the nonzero driving force is a result of the dependence of the ion mean free path on the particle number density. If this effect is properly included in the model of similar complex plasmas, then one arrives at the driving force that changes its sign at the point where the probe and the dust particles have equal radii. If the probe is smaller than the dust particle, then the driving force is directed toward the discharge center and vice versa, in accordance with the experiment. The obtained results can serve as the ansatz for future investigation of the lane formation in complex plasmas.
Quantitative analysis of total reflection X-ray fluorescence from finely layered structures using XeRay
Authors: Gong Zhiliang , Kerr Daniel , Hwang Hyeondo Luke , Henderson J. Michael , Suwatthee Tiffany , Slaw Benjamin R. , Cao Kathleen D. , Lin Binhua , Bu Wei , Lee Ka Yee C.
Published: March 2017

Total reflection x-ray fluorescence (TXRF) is a widely applicable experimental technique for studying chemical element distributions across finely layered structures at extremely high sensitivity. To promote and facilitate scientific discovery using TXRF, we developed a MATLAB-based software package with a graphical user interface, named XeRay, for quick, accurate, and intuitive data analysis. XeRay lets the user model any layered system, each layer with its independent chemical composition and thickness, and enables fine-tuned data fitting. The accuracy of XeRay has been tested in the analysis of TXRF data from both air/liquid interface and liquid/liquid interfacial studies and has been compared to literature results. In an air/liquid interface study, Ca2+ sequestration was measured at a Langmuir monolayer of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphatidic acid (SOPA) on a buffer solution of 1 mM CaCl2 at pH 7.5. Data analysis with XeRay reveals that each 1 nm2 of interfacial area contains 2.38 ± 0.06 Ca2+ ions, which corresponds to a 1:1 ratio between SOPA headgroups and Ca2+ ions, consistent with several earlier reports. For the liquid/liquid interface study of Sr2+ enrichment at the dodecane/surfactant/water interface, analysis using XeRay gives a surface enrichment of Sr2+ at 68−5+6 Å2 per ion, consistent with the result published for the same dataset.
A terahertz study of taurine: Dispersion correction and mode couplings
Authors: Dai Zelin , Xu Xiangdong , Gu Yu , Li Xinrong , Wang Fu , Lian Yuxiang , Fan Kai , Cheng Xiaomeng , Chen Zhegeng , Sun Minghui , Jiang Yadong , Yang Chun , Xu Jimmy
Published: March 2017

The low-frequency characteristics of polycrystalline taurine were studied experimentally by terahertz (THz) absorption spectroscopy and theoretically by ab initio density-functional simulations. Full optimizations with semi-empirical dispersion correction were performed in spectral computations and vibrational mode assignments. For comparison, partial optimizations with pure density functional theory were conducted in parallel. Results indicate that adding long-range dispersion correction to the standard DFT better reproduces the measured THz spectra than the popular partial optimizations. The main origins of the observed absorption features were also identified. Moreover, a coupled-oscillators model was proposed to explain the experimental observation of the unusual spectral blue-shift with the increase of temperature. Such coupled-oscillators model not only provides insights into the temperature dynamics of non-bonded interactions but also offers an opportunity to better understand the physical mechanisms behind the unusual THz spectral behaviors in taurine. Particularly, the simulation approach and novel coupled-oscillators model presented in this work are applicable to analyze the THz spectra of other molecular systems.
Collective hydration dynamics in some amino acid solutions: A combined GHz-THz spectroscopic study
Authors: Samanta Nirnay , Das Mahanta Debasish , Choudhury Samiran , Barman Anjan , Kumar Mitra Rajib
Published: March 2017

A detailed understanding of hydration of amino acids, the building units of protein, is a key step to realize the overall solvation processes in proteins. In the present contribution, we have made a combined GHz (0.2-50) to THz (0.3-2.0) experimental spectroscopic study to investigate the dynamics of water at room temperature in the presence of different amino acids (glycine, L-serine, L-lysine, L-tryptophan, L-arginine, and L-aspartic acid). The THz absorption coefficient, α(ν), of amino acids follows a trend defined by their solvent accessible surface area. The imaginary and real dielectric constants obtained in GHz and THz regions are fitted into multiple Debye model to obtain various relaxation times. The ∼100 ps time scale obtained in the GHz frequency region is attributed to the rotational motion of the amino acids. In the THz region, we obtain ∼8 ps and ∼200 fs time scales which are related to the cooperative dynamics of H-bond network and partial rotation or sudden jump of the under-coordinated water molecules. These time scales are found to be dependent on the amino acid type and the cooperative motion is found to be dependent on both the hydrophobic as well as the hydrophilic residue of amino acids.
Ion dynamics in AgI doped silver selenium-tellurite mixed former glasses
Authors: Palui A. , Ghosh A.
Published: March 2017

The ionic conductivity and the conductivity spectra of the glass compositions xAgI-(1-x)[yAg2O-(1-y)(0.5SeO2-0.5TeO2)] have been studied at different temperatures The activation energy for the dc conduction has been analyzed using the Anderson-Stuart model, and a correlation between the dc conductivity and the doorway radius has been obtained. We have analyzed the conductivity spectra using the random free-energy barrier model, taking into account the contribution of electrode polarization. It is observed that the Barton-Nakajima-Namikawa relation between the conductivity and the relaxation time is valid for these glasses. The time-temperature superposition principle has been verified using the scaling of the conductivity spectra in the framework of the random barrier model. The charge carrier density, obtained from the Nernst-Einstein relation, is found to be almost independent of temperature, but dependent weakly on composition. We have also studied the influence of the modification of the network structure of these glasses on ion migration and correlated the conductivity with the relative strength of the structural units.
Experimental demonstration of one-dimensional active plate-type acoustic metamaterial with adaptive programmable density
Authors: Allam Ahmed , Elsabbagh Adel , Akl Wael
Published: March 2017

A class of active acoustic metamaterials (AMMs) with a fully controllable effective density in real-time is introduced, modeled, and experimentally verified. The density of the developed AMM can be programmed to any value ranging from −100 kg/m3 to 100 kg/m3 passing by near zero density conditions. This is achievable for any frequency between 500 and 1500 Hz. The material consists of clamped piezoelectric diaphragms with air as the background fluid. The dynamics of the diaphragms are controlled by connecting a closed feedback control loop between the piezoelectric layers of the diaphragm. The density of the material is adjustable through an outer adaptive feedback loop that is implemented by the real-time evaluation of the density using the 4-microphone technique. Applications for the new material include programmable active acoustic filters, nonsymmetric acoustic transmission, and programmable acoustic superlens.
Contribution of optical emission spectroscopy measurements to the understanding of TiO2 growth by chemical vapor deposition using an atmospheric-pressure plasma torch
Authors: Gazal Y. , Chazelas C. , Dublanche-Tixier C. , Tristant P.
Published: March 2017

The plasma jet of an atmospheric-pressure chemical vapor deposition system, namely, the axial injection torch, was diagnosed by optical emission spectroscopy (OES) in the conditions corresponding to titanium oxide deposition. Titanium tetraisopropoxide (TTIP) was used as the Ti organometallic precursor. The determination of the spatially-resolved excitation temperatures in the discharge allowed the determination of relative concentrations of atomic emitting species. The entrainment of air was estimated by measuring the relative quantity of N and O atoms in the discharge. The decomposition of TTIP was estimated by measuring the relative concentration of atomic Ti. It was shown that the air is rapidly introduced and distributed in the discharge while TTIP is progressively decomposed. Space-resolved OES measurements allowed to highlight titanium-depletion regions in the discharge. In light of previous results, it was suggested that these Ti-depletion regions reflect TiO2 gas phase nucleation processes. They are thus expected to affect the deposition growth mechanisms: Ti-rich regions would contribute to surface deposition (heterogeneous phase reactions) whereas Ti-depletion regions would contribute to the TiO2 particles deposition (homogeneous phase reactions).
Momentum transfer using variable gaseous plasma ion beams and creation of high aspect ratio microstructures
Authors: Maurya Sanjeev Kumar , Paul Samit , Shah Jay Kumar , Chatterjee Sanghamitro , Bhattacharjee Sudeep
Published: March 2017

Intense gaseous ion beams are created from compact microwave plasmas confined in a multicusp magnetic field. The wave frequency (ω) is comparable to the electron plasma frequency (ωpe) and ⪢ the ion plasma frequency (ωpi); therefore, the heavier plasma (ions) are least disturbed by the high frequency electromagnetic waves. By changing the experimental gas, ion beams of different species are obtained, which expands the applicability of the ion beams. For the same applied accelerating potential, the controllability of the beam current owing to different velocities for different ionic species adds to the enhanced functionality. The ion beams are utilized to create a variety of microstructures by direct writing on metallic substrates, and microstructures of a high aspect ratio (ar = line width/depth) in the range of 100–1000 are created by varying the ion species and writing speed. For fixed species (Ga) and low current (1 pA) focused ion beam systems, typically ar ∼ 2.0 to 9.3 may be realized in a single beam scan. A parameter called current normalized force, defined as the momentum transfer per unit time, normalized with the beam current helps in understanding the different momentum transferred to the target sample upon impact by the ion beams of variable species. A mathematical formulation is developed to demonstrate this aspect.
The beam energy feedback system for Beijing electron positron collider II linac
Authors: Wang S. , Iqbal M. , Chi Y. , Liu R. , Huang X.
Published: March 2017

A beam-energy feedback system has been developed for the injection linac to meet the beam quality needed for the Beijing electron positron collider II storage ring. This paper describes the implementation and commissioning of this system in detail. The system consists of an energy measurement unit, application software, and an actuator unit. A non-intersecting beam energy monitor was developed to allow real-time online energy adjustment. The beam energy adjustment is achieved by adjusting the output microwave phase of the RF power source station. The phase control mechanism has also been modified, and a new control method taking the return difference of the phase shifter into account is used to improve the system’s performance. This system achieves the design aim and can adjust the beam center energy with a rate of 2 Hz. With the energy feedback system, the stability of the injection rate is better; the fluctuation range is reduced from 20 mA/min to 10 mA/min, while the stability of the beam center energy is maintained within ±0.1%.
Reducing mass peak instability caused by the phase changes of RF and AC signals in a rectilinear ion-trap analyzer
Authors: Lu Xinqiong , Ni Kai , Yu Quan , Xu Wenchao , Qian Xiang , Wang Xiaohao
Published: March 2017

For an ion trap with resonance ejection, peak intensity and peak position of the acquired mass spectra are affected by the phase difference between the radio frequency (RF) and auxiliary alternating current (AC) potentials. To ensure measurement stability, RF and AC phase-locking is commonly used in commercial ion trap mass spectrometers. In this study, a compact electronic control system was developed to accurately regulate the RF and AC phases and was employed in a photoionization rectilinear ion trap (RIT) mass spectrometer. We found that the phase-locking method was defective in multicomponent analysis because the optimal RF and AC phase difference was usually different for different m/z peaks. After studying and characterizing the relationship between the peaks and the RF and AC phases, a correction method based on data processing was used to improve the peaks’ stability and accuracy. The results show that the fluctuations of both peak intensity and peak position were significantly reduced and that the instrument presented satisfying reproducibility and quantitative ability.
Luminescence imaging of photoelectron spin precession during drift in a p-type GaAs microfabricated Hall bar
Authors: Notot V. , Paget D. , Rowe A. C. H. , Martinelli L. , Cadiz F. , Arscott S.
Published: March 2017

Using a microfabricated p-type GaAs Hall bar, it is shown that the combined application of co-planar electric and magnetic fields enables the observation of spatial oscillations of the photoluminescence circular polarization due to the precession of drifting spin-polarized photoelectrons. Observation of these oscillations as a function of electric field gives a direct measurement of the minority carrier drift mobility and reveals that the spin coherence length can be tuned up to more than 10μm with electric fields below 1 kV/cm.
Self-ignition induced by cylindrically imploding shock adapting to a convergent channel
Authors: Yang Jianting , Zhu Yujian , Yang Jiming
Published: March 2017

A convergent channel method is applied to create an imploding arc shock as a partial representative of an overall cylindrical shock. The self-ignition phenomenon induced by such an imploding shock is investigated experimentally and numerically. Agreements between experimental and numerical results are widely reached not only for the shock imploding process but also for shock reflection and features of self-ignition, which approves the validity of the method. The induced self-ignition is found to lag behind the incident shock front and experience a shockless spontaneous process before the onset of detonation. The mechanisms are briefly addressed.
Antimicrobial effect of essential oils of some Fijian medicinal plant leaves on pathogenic bacteria
Authors: Maharaj Prayna P. P. , Devi Riteshma , Prasad Surendra
Published: March 2017

Fiji is highly populated with plants containing essential oils (EO). The essential oils extracted from the leaves of the selected Fijian leafy plants were screened against two Gram-negative bacteria (Salmonella typhimurium, Pseudomonas aeruginosa) and three Gram-positive bacteria (Staphylococcus aureus, Enterococcus faecalis and Bacillus subtilis). The agar diffusion method was used to examine the antimicrobial activities of the extracted EO. All the EO tested showed antibacterial properties against one or more strains while none of the EO was active against Pseudomonas aeruginosa. Viburnum lantana (Wayfaring tree), Annona muricata (Soursop), Coleus amboinicus (Spanish thyme) and Cinnamomum zeylancium (Cinnamon) showed good inhibition against both Gram-positive and Gram-negative bacteria and proved as worthy source of antimicrobial agent. These findings will help the Pacific population to use the studied plants leaves as antimicrobial agent.
MYO6 is targeted by
Salmonella
virulence effectors to trigger PI3-kinase signaling and pathogen invasion into host cells
Authors: Brooks Andrew B. E. , Humphreys Daniel , Singh Vikash , Davidson Anthony C. , Arden Susan D. , Buss Folma , Koronakis Vassilis
Published: March 2017

Significance

Salmonella
causes many different diseases including gastroenteritis and typhoid fever. For infection to take place,
Salmonella
must enter the epithelium in the gut by injecting a number of effector proteins that trigger dramatic actin rearrangements and membrane ruffles to engulf the pathogen. In this study we identified a myosin motor protein that translocates along actin filaments as one of the crucial host proteins that are targeted by two
Salmonella
effector proteins, SopE and SopB, at the onset of infection. SopE and SopB exploit MYO6 to facilitate membrane ruffle formation and phospholipid production at the invasion site to mediate pathogen uptake. Myosin motors are highly druggable targets, and therefore myosin inhibitors are attractive new tools to fight bacterial infections.
Nurr1:RXRα heterodimer activation as monotherapy for Parkinson’s disease
Authors: Spathis Athanasios D. , Asvos Xenophon , Ziavra Despina , Karampelas Theodoros , Topouzis Stavros , Cournia Zoe , Qing Xiaobing , Alexakos Pavlos , Smits Lisa M. , Dalla Christina , Rideout Hardy J. , Schwamborn Jens Christian , Tamvakopoulos Constantin , Fokas Demosthenes , Vassilatis Demetrios K.
Published: March 2017

Significance

In Parkinson’s disease (PD), dopamine (DA)-producing neurons gradually degenerate, leading to DA deficiency and to the main symptoms of PD. Current medications do not impede neurodegeneration, but relieve symptoms by replenishing DA; however, their chronic use causes serious side effects. We targeted a protein required for the development and function of DA neurons by designing a chemical compound that, by activating this protein, increases DA and improves symptoms without current treatment side effects while simultaneously preventing neuron loss in PD mice. Our findings point to a monotherapy that can both impede PD progression and concurrently improve symptoms of PD.
Mouse-adapted MERS coronavirus causes lethal lung disease in human DPP4 knockin mice
Authors: Li Kun , Wohlford-Lenane Christine L. , Channappanavar Rudragouda , Park Jung-Eun , Earnest James T. , Bair Thomas B. , Bates Amber M. , Brogden Kim A. , Flaherty Heather A. , Gallagher Tom , Meyerholz David K. , Perlman Stanley , McCray Paul B.
Published: March 2017

Significance

Middle East respiratory syndrome, caused by a zoonotically transmitted coronavirus (MERS-CoV), has a high mortality (∼36%). Because of limited autopsy data on tissues from MERS fatalities, a small animal model can provide an important tool to better understand the disease. We humanized the mouse locus of the virus receptor DPP4, preserving native DPP4 expression. After inoculating hDPP4 knockin mice with MERS-CoV, there was virus replication without disease. We then generated a mouse-adapted MERS-CoV by serial passage in hDPP4 knockin mice. The resultant virus causes fatal lung disease that includes diffuse alveolar damage and immune dysregulation. Here, we characterize the pathologic features of the model and elucidate key aspects of the immunopathology and factors contributing to virulence.
KETCH1 imports HYL1 to nucleus for miRNA biogenesis in
Arabidopsis
Authors: Zhang Zhonghui , Guo Xinwei , Ge Chunxiao , Ma Zeyang , Jiang Mengqiu , Li Tianhong , Koiwa Hisashi , Yang Seong Wook , Zhang Xiuren
Published: March 2017

Significance

Microprocessor components are transported into the nucleus to process primary miRNAs (pri-miRNAs). Hyponastic leaves 1 (HYL1) is a core component of microprocessor in
Arabidopsis
. This study identifies an importin β-protein, KETCH1, as a partner of HYL1 protein.
KETCH1
knockdown mutation causes developmental defect, reminiscent of mutants in the miRNA pathway. The mutation also reduces miRNA abundance but does not affect its nuclear-cytoplasmic distribution. Rather,
KETCH1
knockdown mutation decreases the accumulation of HYL1 protein in the nucleus and compromises the HYL1-mediated pri-miRNA processing, supporting that KETCH1 specifically transports HYL1 into the nucleus to facilitate miRNA production. Given that HYL1 and importin β-proteins are all conserved in various organisms, this study sheds light on the poorly understood nuclear-cytoplasmic trafficking of microprocessor components through eukaryotes.
Structure of the MeCP2–TBLR1 complex reveals a molecular basis for Rett syndrome and related disorders
Authors: Kruusvee Valdeko , Lyst Matthew J. , Taylor Ceitidh , Tarnauskaitė Žygimantė , Bird Adrian P. , Cook Atlanta G.
Published: March 2017

Significance

Methyl-CpG–binding protein 2 (MeCP2) links epigenetics, brain function, and neurological disease. Mutations in the MeCP2 protein cause Rett syndrome (RTT), making it imperative to determine its mechanism of action. One domain of MeCP2 targets it to methylated DNA, but little was known about a second essential domain except that it recruits a gene-silencing complex. We determined that transducin beta-like (TBL) subunits of the silencing complex bind MeCP2 and solved the structure of the binary complex. Strikingly, amino acids mutated in RTT are precisely those amino acids that intimately contact the TBL subunits. Furthermore, mutations in TBL proteins that cause intellectual disability block interaction with MeCP2. Our data suggest that the TBL–MeCP2 interaction is essential for brain function.
PLP and GABA trigger GabR-mediated transcription regulation in
Bacillus subtilis
via external aldimine formation
Authors: Wu Rui , Sanishvili Ruslan , Belitsky Boris R. , Juncosa Jose I. , Le Hoang V. , Lehrer Helaina J. S. , Farley Michael , Silverman Richard B. , Petsko Gregory A. , Ringe Dagmar , Liu Dali
Published: March 2017

Significance

Regulator of the
gabTD
operon and its own gene (GabR) is an intriguing case of molecular evolution, displaying the evolutionary lineage between a pyridoxal-5′-phosphate (PLP)-dependent aminotransferase and a regulation domain of a transcription regulator. Here, PLP’s native function is not a catalytic coenzyme, but an effector of transcription regulation. The chemical species of GabR-PLP–GABA, which is responsible for GabR-mediated transcription activation, has been revealed as a stable external aldimine formed between PLP and GABA by a crystal structure with further support from results in mechanistic crystallography, NMR spectroscopy, and biological assays using both GABA and a GABA analog, (
S
)-4-amino-5-fluoropentanoic acid (AFPA), as a molecular probe. Our results provide mechanistic insights for a currently understudied
Rhizobium meliloti
rhizopine catabolism regulator (MocR)/GabR subfamily of bacterial transcription regulators.
Does slow motion impact on the perception of foul play in football?
Authors: Spitz Jochim , Put Koen , Wagemans Johan , Williams A. Mark , Helsen Werner F.
Published: March 2017

Objectives: Slow‐motion replays of foul play situations are now used in the education and training of sports officials. We investigated the impact of video speed on the decision‐making process of association football referees and how this interacted with expertise. Methods: Three different groups of referees, varying in level of expertise, assessed video clips from an in‐game perspective. Video clips represented corner kick and open play situations in which a foul occurred or not. For these foul/no foul situations, the referees had to make a technical (no foul; indirect free kick; direct free kick; or penalty kick) and a disciplinary decision (no card; yellow card; or red card), under both slow‐motion and real‐time viewing conditions. Accuracy scores were determined by comparing participant's responses with the decisions of an expert panel. Results: Significant differences were observed across groups for foul/no foul situations, suggesting that the experts were able to process the available information more effectively than their less expert colleagues. The accuracy scores for the technical decision were higher in slow motion (67%) compared to a real‐time viewing condition (56%), particularly for corner kick situations. No differences were found between real time and slow motion for the disciplinary decision. Conclusions: Slow‐motion footage results in higher accuracy scores for complex technical decisions. These findings have implications for the use of slow‐motion replays in the decision‐making process of referees.
PARTIE: a partition engine to separate metagenomic and amplicon projects in the Sequence Read Archive
Authors: Torres Pedro J , Edwards Robert A , McNair Katelyn A
Published: March 2017

Motivation

The Sequence Read Archive (SRA) contains raw data from many different types of sequence projects. As of 2017, the SRA contained approximately ten petabases of DNA sequence (1016 bp). Annotations of the data are provided by the submitter, and mining the data in the SRA is complicated by both the amount of data and the detail within those annotations. Here, we introduce PARTIE, a partition engine optimized to differentiate sequence read data into metagenomic (random) and amplicon (targeted) sequence data sets.

Results

PARTIE subsamples reads from the sequencing file and calculates four different statistics: k-mer frequency, 16S abundance, prokaryotic- and viral-read abundance. These metrics are used to create a RandomForest decision tree to classify the sequencing data, and PARTIE provides mechanisms for both supervised and unsupervised classification. We demonstrate the accuracy of PARTIE for classifying SRA data, discuss the probable error rates in the SRA annotations and introduce a resource assessing SRA data.

Availability and Implementation

PARTIE and reclassified metagenome SRA entries are available from https://github.com/linsalrob/partie

Supplementary information

Supplementary data are available at Bioinformatics online.
The accreted stellar halo as a window on halo assembly in L* galaxies
Authors: Amorisco Nicola C.
Published: March 2017

Theory and observations agree that the accreted stellar haloes (ASHs) of Milky Way-like galaxies display significant scatter. I take advantage of this stochasticity to invert the link between halo assembly history (HAH) and ASH, using mock ASHs corresponding to 750 ΛCDM HAHs, sharing a final virial mass of Mh(z = 0) = 1012.25M⊙. Hosts with poor/rich ASHs assemble following orthogonal growth-patterns. Hosts with rich ASHs experience accretion events (AEs) with high virial mass ratios (HVMRs, Ms/Mh ≳ 0.1) at 0.5 ≲ zinfall ≲ 1.5, in a phase of fast growth. This maximizes the accreted stellar mass under the condition these satellites are disrupted by z = 0. At similar times, hosts with poor ASHs grow slowly through minor mergers, with only very recent HVMR AEs: this results in a globally more abundant satellite population and in distinctive surviving massive satellites (stellar mass log Ms, */M⊙ ≳ 9). Several properties of the Milky Way are in agreement with the predictions of this framework for hosts with poor, concentrated ASHs, including: (i) the recent infall of Sagittarius and Magellanic Clouds, (ii) the likely higher-than-average concentration of its dark halo and (iii) the signatures of fast chemical enrichment of a sizable fraction of its halo stellar populations.
Orbital modulations of X-ray light curves of Cygnus X-1 in its low/hard and high/soft states
Authors: Sugimoto Juri , Kitamoto Shunji , Mihara Tatehiro , Matsuoka Masaru
Published: March 2017

The black hole binary Cygnus X-1 has a 5.6-d orbital period. We first detected a clear intensity modulation with the orbital period in its high/soft state with six-year MAXI data, as well as in its low/hard state. In the low/hard state, the folded light curves showed an intensity drop at the superior conjunction of the black hole by a modulation factor (MF), which is the amplitude divided by the average, of 8 ± 1%, 4 ± 1%, and 3 ± 2% for 2–4, 4–10, and 10–20 keV bands, respectively, showing a spectral hardening at the superior conjunction of the black hole. Spectral analysis in the low/hard state, with a model consisting of a power law and a photoelectric absorption, showed that the hydrogen column density, NH, increased from (2.9 ± 0.4) × 1021 cm−2 to (4.7 ± 1.1) × 1021 cm−2 around the superior conjunction. The flux of the power-law component decreased by 6 ± 1%. On the other hand, MFs for the folded light curves in the high/soft state, were 4 ± 1% and 4 ± 2% for the 2–4 keV and 4–10 keV bands, respectively. We applied a model consisting of a power law and a disk blackbody with a photoelectric absorption. A modulation of the flux of the power-law component was found to be 7 ± 5% in MF, while the modulation of NH was less than 1 × 1021 cm−2. These results can be interpreted as follows: the modulation of both states can be mainly explained by scattering of X-rays by an ionized stellar wind, but, only at the superior conjunction in the low/hard state, a large photoelectric absorption appears because of the low ionization state of the wind in the line of sight at phase 0. Such a condition can be established by reasonable parameters of an inhomogeneous wind and the observed luminosities.