bluuebunny/crossref_metadata_2025 huggingface dataset:
Three‐dimensional bistatic array imaging using range migration algorithm
Authors: Guo Qijia , Zhang Xiaoxuan , Chang Tianying , Cui Hong‐Liang , Tian Xianzhong
Published: November 2016

Millimetre wave imaging systems are widely used in many fields, such as non‐destructive testing, security screening and medical imaging. For security‐related personnel screening, the geometries of planar and cylindrical‐scanning antenna arrays are often adopted. A planar array imager is capable of acquiring a three‐dimensional image in real time, but the information on the back side of the object will be lost. A cylindrical scanning imager is well suited for constructing an image in full 360° directions, what is lost is the time that it takes to complete a full scan. Regardless, mechanical scanning geometry is not always the best approach for real‐time systems. In this letter, an imaging scenario is proposed, which is composed of two parallel arrays facing each other. Multiple input multiple output technology is applied to the pair of arrays. Range migration algorithm is adapted specially for this scenario, through which nearly 360°‐images of high quality can be constructed in real time when an object is placed between the two arrays.
predictive control with probability constraints for linear stochastic systems
Authors: Li Jiwei , Li Dewei , Xi Yugeng
Published: November 2016

This study develops stochastic model predictive control that guarantees the recursive feasibility of the closed‐loop performance. Multi‐step sets with scaling parameters are proposed to contain the uncertain system trajectory. Meanwhile, by extending the probabilistic invariance to disturbed stochastic systems, we formulate probabilistic constraints as linear matrix inequalities. We show that the introduced scaling parameters enhance the feasibility of predictive control and reduce the conservatism of the constraint satisfaction. The designed control algorithm is recursively feasible and stabilises the system in the mean‐square sense. A simplified algorithm further reduces much computational burden and makes the proposed approach more practical.
Adaptive neural network control of a robotic manipulator with unknown backlash‐like hysteresis
Authors: He Wei , Ofosu Amoateng David , Yang Chenguang , Gong Dawei
Published: November 2016

This study proposes an adaptive neural network controller for a 3‐DOF robotic manipulator that is subject to backlash‐like hysteresis and friction. Two neural networks are used to approximate the dynamics and the hysteresis non‐linearity. A neural network, which utilises a radial basis function approximates the robot's dynamics. The other neural network, which employs a hyperbolic tangent activation function, is used to approximate the unknown backlash‐like hysteresis. The authors also consider two cases: full state and output feedback control. For output feedback, where system states are unknown, a high gain observer is employed to estimate the states. The proposed controllers ensure the boundedness of the control signals. Simulations are also performed to show the effectiveness of the controllers.
Predictive control of permanent magnet synchronous motor with non‐sinusoidal flux distribution for torque ripple minimisation using the recursive least square identification method
Authors: Abbaszadeh Alireza , Arab Khaburi Davood , Rodríguez José
Published: November 2016

To reduce the torque ripple of permanent magnet synchronous motor with non‐sinusoidal flux distribution, a new method is presented in this study. This method is based on model predictive control (MPC). MPC is a model‐based control and requires an accurate model of the motor. A sliding mode observer, accompanied with a recursive least square estimator, is utilised to determine the magnitudes of the harmonics of the back electromotive force (EMF) waveforms. The appropriate current harmonics, considering the back EMF harmonics, are injected to shape the motor current. The interaction of non‐sinusoidal back EMF and the shaped current leads to torque ripple reduction. The experimental results verify the effectiveness of the proposed method.
Analytical, numerical and experimental analysis of induction heating of graphite crucible for melting of non‐magnetic materials
Authors: Patidar Bhupendra , M. Hussain Mozahir , Jha Sanjeev K. , Sharma Archana , Tiwari Akhilanand P.
Published: November 2016

This study presents analytical formulation used for design of helical coil for induction heating of solid and hollow cylindrical non‐magnetic workpiece (graphite crucible). This formulation is applied for estimation of the active power in graphite crucibles and reactive power drawn by the induction coil in presence of different wall thickness (30, 20, 10 and 5 mm) of graphite crucibles at different frequency (1–50 kHz). Magnetic field produced by induction coil is estimated by using empirical factors suggested by kNagaoka et al. Induction heating processes, i.e. electromagnetism and heat transfer physics are mathematically modelled by Maxwell and Fourier equations, respectively. Finite‐element method is used to solve the electromagnetic field in frequency domain and heat transfer in transient domain. Numerical analysis is carried out by using two‐dimensional axisymmetric geometry. Analytical results and numerical results are compared and are found to be in good agreement with each other. Experimentally obtained coil voltage and graphite crucible temperature were compared with numerical results and the authors found that they also match very well confirming the validity of their assumptions in analytical/numerical approach.
Investigation and implementation of a new hybrid excitation synchronous machine drive system
Authors: Zhang Zhuoran , Liu Ye , Tian Bo , Wang Wenjia
Published: November 2016

Hybrid excitation synchronous machines (HESMs) inherit the high‐torque density of permanent magnet synchronous machines and flux regulation capability of wound rotor synchronous machines. This makes HESMs attractive candidates for vehicle traction applications. To further improve torque density, an optimised HESM with magnet shunting rotor is proposed in this study. This study presents a maximum torque control strategy with zero d‐axis current. Furthermore, an optimised control strategy that utilises the coordinated operation between the field current and d‐axis current is proposed. The optimised control strategy exhibits advantages of low‐speed high‐torque, wide constant power range, and high efficiency in flux‐weakening (FW) region. A 100 kW drive system based on the optimised HESM with the proposed control strategy is developed, experimentally realised, and validated. The experimental results show that the FW range is 3.5–1, and the efficiency of the drive system is >92% in most operating region, which verify the superiority and effectiveness of the proposed HESM drive system.
Low complexity predictive torque control strategies for a three‐level inverter driven induction motor
Authors: Habibullah Md. , Lu Dylan Dah‐Chuan , Xiao Dan , Fletcher John E. , Rahman Muhammed Fazlur
Published: November 2016

Iterative and complex prediction loop is a challenge for the implementation of finite‐state predictive torque control (FS‐PTC) of motor drive. The complexity is due to the complex torque calculations, number of available voltage vectors (which are called as prediction vectors), and weighting factor tuning for torque and flux errors in the cost function. One way to reduce the complexity is an equivalent reference stator flux vector calculation (RSFVC) from torque and flux references, which also solves the problem of weighting factor tuning. Along with a new stator flux based RSFVC technique, a reduced number of prediction vectors are proposed in this study to reduce the number of iteration of the prediction loop. The position of the stator flux and sign of the stator flux‐error are considered to lessen the number of prediction vectors. Hence, the implementation challenges of FS‐PTC algorithm are overcome. The performance of the proposed technique is investigated for two types of RSFVCs: one is based on the stator flux, and another one is based on the rotor flux. Experimental results verify that the proposed low complexity FS‐PTC strategies retain the advantages of a conventional FS‐PTC.
Compact broadband circularly‐polarised directional universal GNSS antenna with symmetric radiation pattern and stable near‐zenith coverage
Authors: Liu Qiang , Li Yong , Mo Zhiguang , Liu Yuanan
Published: November 2016

Circularly‐polarised (CP) antennas are widely used in global navigation satellite system (GNSS). In this study, a compact broadband CP directional antenna comprises a circular radiating patch, four coupled semi‐sector‐annulus sheets, and a novel compact broadband four‐feed circuit is presented. In combination of the out‐of‐phase power splitter, coupled‐line power dividers, and broadband phase shifters, the four‐feed circuit characterises consistent 90° phase shift sequentially on the four equal output signals. The bandwidth of the four‐feed circuit is 104.8% for 10‐dB return loss (RL), output magnitude distribution −6.5 (±0.2) dB, and phase err 90° (±6°), which provides the antenna with high‐precision feed signals. Measured results show that the antenna achieves CP bandwidth of 75.8% from 1.13 to 2.51 GHz for RL better than 10 dB, axial ratio lower than 3 dB, and gain variation less than 3 dB. Performance contrast shows that the design provides the widest CP bandwidth and small volume of 0.7 × 0.8 × 0.09λ03. Moreover, the antenna exhibits considerably symmetric patterns and stable near‐zenith coverage in the whole CP band. Therefore, the proposed antenna is well suited to universal GNSS applications, especially when receivers operate in street canyons and mountainous area.
Proposal of neural approach to maritime radar and automatic identification system tracks association
Authors: Kazimierski Witold
Published: November 2016

This study presents results of a study on association of targets tracked with an automatic identification system and marine tracking radar. This paper shows various approaches for solving association problem. Description of selected numerical methods is given, followed by an experimental evaluation, showing advantages and disadvantages for each of them. On the other hand, novel approach is proposed: namely, the use of neural networks for this task. Association is defined as a classification problem and suitable neural networks are selected and trained. Each pair of targets is being classified with neural filter, stating if association takes place. The main advantage of this approach is its flexibility in adjusting to current data. Neural networks can be trained during data processing to adjust to current situation, which is not the case in a priori defined numerical models. Experimental verification of the proposed solution and comparison of neural networks with numerical methods is included. The results obtained indicate that neural networks are an interesting alternative to numerical methods.
A two-energies principle for the biharmonic equation and ana posteriorierror estimator for an interior penalty discontinuous Galerkin approximation
Authors: Braess Dietrich , Hoppe R.H.W. , Linsenmann Christopher
Published: November 2016

We consider ana posteriorierror estimator for the Interior Penalty Discontinuous Galerkin (IPDG) approximation of the biharmonic equation based on the Hellan-Herrmann-Johnson (HHJ) mixed formulation. The error estimator is derived from a two-energies principle for the HHJ formulation and amounts to the construction of an equilibrated moment tensor which is done by local interpolation. The reliability estimate is a direct consequence of the two-energies principle and does not involve generic constants. The efficiency of the estimator follows by showing that it can be bounded from above by a residual-type estimator known to be efficient. A documentation of numerical results illustrates the performance of the estimator.
Integrity: the virtue of compromise
Authors: Schwartz Jeremy
Published: November 2016

In this article, I develop a novel interpretation of integrity that I believe ought to be of special interest to business ethicists. According to a traditional understanding, integrity is the virtue of holding fast to one’s principles in the face of temptations. Against this, I suggest that integrity is the virtue that governs rather than forbids compromise. In other words, integrity does not just forbid compromise; it sometimes demands it. This virtue will sound paradoxical to some, and I spend much of the essay arguing for its plausibility and locating it within the larger philosophical tradition. In the second half of the essay, I try to connect this virtue to the essential aims of business as understood by shareholder theorists. If my argument is correct, it may explain why integrity is of such central concern for business ethicists. This article is published as part of a collection on integrity and its counterfeits.
Analysing security subcomplexes in a changing Middle East—the role of non-Arab state actors and non-state actors
Authors: Seeberg Peter
Published: November 2016

This article presents a theoretical framework for a collection of articles (“special issue”), which aims at discussing the role of non-Arab state actors and non-state actors in a changing Middle East. The articles in the collection offer perspectives that have been overlooked in recent research, namely those focusing on the role of non-Arab state actors and non-state actors in connection with the changing security environment in the region. Furthermore, these articles discuss how changes in the Middle East and North Africa (MENA) region are appearing in different and shifting contexts in the creation of new local, sub-regional, or regional security subcomplexes in which Arab states, non-Arab states and non-state actors enter into new conflicts, alliances and other political relations with and against each other. The role of international actors interfering in the region is also analyzed in the context of the changing Middle East.
Automated electrorotation shows electrokinetic separation of pancreatic cancer cells is robust to acquired chemotherapy resistance, serum starvation, and EMT
Authors: Lannin Timothy , Su Wey-Wey , Gruber Conor , Cardle Ian , Huang Chao , Thege Fredrik , Kirby Brian
Published: November 2016

We used automated electrorotation to measure the cytoplasmic permittivity, cytoplasmic conductivity, and specific membrane capacitance of pancreatic cancer cells under environmental perturbation to evaluate the effects of serum starvation, epithelial-to-mesenchymal transition, and evolution of chemotherapy resistance which may be associated with the development and dissemination of cancer. First, we compared gemcitabine-resistant BxPC3 subclones with gemcitabine-naive parental cells. Second, we serum-starved BxPC3 and PANC-1 cells and compared them to untreated counterparts. Third, we induced the epithelial-to-mesenchymal transition in PANC-1 cells and compared them to untreated PANC-1 cells. We also measured the electrorotation spectra of white blood cells isolated from a healthy donor. The properties from fit electrorotation spectra were used to compute dielectrophoresis (DEP) spectra and crossover frequencies. For all three experiments, the median crossover frequency for both treated and untreated pancreatic cancer cells remained significantly lower than the median crossover frequency for white blood cells. The robustness of the crossover frequency to these treatments indicates that DEP is a promising technique for enhancing capture of circulating cancer cells.
A Hückel source-sink-potential theory of Pauli spin blockade in molecular electronic devices
Authors: Pickup Barry T. , Fowler Patrick W. , Sciriha Irene
Published: November 2016

This paper shows how to include Pauli (exclusion principle) effects within a treatment of ballistic molecular conduction that uses the tight-binding Hückel Hamiltonian and the source-sink-potential (SSP) method. We take into account the many-electron ground-state of the molecule and show that we can discuss ballistic conduction for a specific molecular device in terms of four structural polynomials. In the standard one-electron picture, these are characteristic polynomials of vertex-deleted graphs, with spectral representations in terms of molecular-orbital eigenvectors and eigenvalues. In a more realistic many-electron picture, the spectral representation of each polynomial is retained but projected into the manifold of unoccupied spin-orbitals. Crucially, this projection preserves interlacing properties. With this simple reformulation, selection rules for device transmission, expressions for overall transmission, and partition of transmission into bond currents can all be mapped onto the formalism previously developed. Inclusion of Pauli spin blockade, in the absence of external perturbations, has a generic effect (suppression of transmission at energies below the Fermi level) and specific effects at anti-bonding energies, which can be understood using our previous classification of inert and active shells. The theory predicts the intriguing phenomenon of Pauli perfect reflection whereby, once a critical electron count is reached, some electronic states of devices can give total reflection of electrons at all energies.
A novel system of coils for magnetobiology research
Authors: Makinistian L.
Published: November 2016

A novel system of coils for testing in vitro magnetobiological effects was designed, simulated, and built. Opposite to what is usual, the system generates a controlled gradient of magnetic field. This feature is introduced to allow the assessment of multiple values of the field in a single experiment. The apparatus consists of two flattened orthogonal coils, which permit independent control of two of the spatial components of the field. Geometry of design, combined with the use of a standard multi-well microplate for cellular culture, allows for simultaneous testing of 96 different field conditions. The system, intended to increase the efficiency of evaluating biological effects throughout ranges of the field parameters, was fully characterized injecting DC currents to the coils (i.e., generating static magnetic fields) in order to assess the spatial distribution of both the field’s and field-gradient’s components. Temperature load was carefully evaluated and the maximum values of 350 μT and 9 μT/mm (for the field and its gradient) could be generated without excessive heating of the cellular cultures.
Current-controlled unidirectional edge-meron motion
Authors: Xing Xiangjun , Pong Philip W. T. , Zhou Yan
Published: November 2016

In order to address many of the challenges and bottlenecks currently experienced by traditional charge-based technologies, various alternatives are being actively explored to provide potential solutions of device miniaturization and scaling in the post-Moore's-law era. Amongst these alternatives, spintronic physics and devices have recently attracted rapidly increasing interest by exploiting the additional degree of electrons-spin. For example, magnetic domain-wall racetrack-memory and logic devices have been realized via manipulating domain-wall motion. As compared to domain-wall-based devices, magnetic skyrmions have the advantages of ultrasmall size (typically 5–100 nm in diameter), facile current-driven motion, topological stability, and peculiar emergent electrodynamics, promising for next-generation electronics applications in the post-Moore's-law regime. Here, a magnetic meron device, which behaves similarly to a PN-junction diode, is demonstrated for the first time, by tailoring the current-controlled unidirectional motion of edge-merons (i.e., fractional skyrmions) in a nanotrack with interfacial Dzyaloshinskii-Moriya interaction. The working principles of the meron device, theoretically predicted from the Thiele equation for topological magnetic objects, are further verified using micromagnetic simulations. The present study has revealed the topology-independent transport property of different magnetic objects and is expected to open the vista toward integrated composite circuitry (with unified data storage and processing) based on a single magnetic chip, as the meron device can be used, either as a building block to develop complex logic components or as a signal controller to interconnect skyrmion, domain-wall, and even spin-wave devices.
Early time instability in nanofilms exposed to a large transverse thermal gradient: Improved image and thermal analysis
Authors: Fiedler Kevin R. , Troian Sandra M.
Published: November 2016

Liquid nanofilms exposed to a large transverse thermal gradient undergo an instability featuring an array of nanopillars whose typical pitch is tens of microns. In earlier works, a comparison of this pitch with the fastest growing wavelength predicted by three different models based on linear instability showed closest agreement with a long wavelength thermocapillary mechanism in which gravity plays no role. Here, we present improved feature extraction techniques, which allow identification of the fastest growing wavelength at much earlier times than previously reported, and more realistic simulations for assessing thermal gradients, which better approximate the actual experimental system. While these improvements lead to better agreement with the thermocapillary mechanism, there persists a quantitative discrepancy with theory which we attribute to a number of experimental challenges.
Glass forming range of the Ti-Fe-Si amorphous alloys: An effective materials-design approach coupling CALPHAD and topological instability criterion
Authors: Zhao Guo-Hua , Mao Huahai , Louzguine-Luzgin Dmitri V.
Published: November 2016

A method of composition design for metallic glasses was proposed by using the Calculation of Phase Diagrams (CALPHAD) with the assistance of the topological instability criterion. This methodology was demonstrated in the quick and effective searching of glass-forming regions for Ti-Fe-Si and Ti-Zr-Fe-Si alloys containing no biologically toxic elements, e.g., Ni and Cu. In addition, the Ti-Fe-Si system may promote the glass formation owing to the existence of a deep eutectic at the Ti-rich corner. A self-consistent thermodynamic database was constructed based on the CALPHAD approach. The liquidus projection, isothermal sections, and the enthalpy of mixing were calculated by using the database. On the basis of these calculations coupling with the topological instability “lambda λ criterion,” the potential glass-forming alloy compositions in a narrow region were suggested for experimental validation. Thereafter, the isothermal sections of the Ti-Zr-Fe-Si quaternary system were calculated at certain contents of Zr. The designed alloys were prepared by arc-melting and followed by melt-spinning to the ribbon shape. The experimental verifications matched reasonably well with the theoretical calculations. This work offers new insights for predicting glass-forming alloys based on thermodynamic arguments; it shall be of benefit for the exploration of new metallic glasses.
Fast analysis and optimal design of metasurface for wideband monostatic and multistatic radar stealth
Authors: Su Jianxun , Lu Yao , Zheng Zhiyan , Li Zengrui , Yang Yaoqing (Lamar) , Che Yongxing , Qi Kainan
Published: November 2016

In this paper, a metasurface (MS) is designed based on the hybrid array pattern synthesis and particle swarm optimization method for wideband monostatic and multistatic radar stealth. The non-absorptive MS is composed of two kinds of electronic band gap structures with the reflection phase difference of 180° (±37°) over a wide frequency range. Far field scattering pattern of the MS can be quickly and accurately synthetized by the method of moments and array pattern synthesis. A new strategy is proposed for realizing the diffusion reflection of electromagnetic waves by redirecting electromagnetic energies to more directions through optimizing the reflected phase arrangement for the MS by hybrid array pattern synthesis and particle swarm optimization algorithm. Due to the non-uniform distributions of phase gradient between neighboring lattices, numerous scattering lobes are produced in the upper half-space, leading to a great reduction of bistatic radar cross section (RCS). The −10 dB RCS reduction bandwidth of 80.2% is achieved for both monostatic and bistatic at normal incidence. The specular reflection and bistatic scattering for oblique incidence with TE and TM polarizations are also considered in detail. The measured results are in good agreement with the corresponding simulations.
Multi-field electron emission pattern of 2D emitter: Illustrated with graphene
Authors: Luo Ma , Li Zhibing
Published: November 2016

The mechanism of laser-assisted multi-field electron emission of two-dimensional emitters is investigated theoretically. The process is basically a cold field electron emission but having more controllable components: a uniform electric field controls the emission potential barrier, a magnetic field controls the quantum states of the emitter, while an optical field controls electron populations of specified quantum states. It provides a highly orientational vacuum electron line source whose divergence angle over the beam plane is inversely proportional to square root of the emitter height. Calculations are carried out for graphene with the armchair emission edge, as a concrete example. The rate equation incorporating the optical excitation, phonon scattering, and thermal relaxation is solved in the quasi-equilibrium approximation for electron population in the bands. The far-field emission patterns, that inherit the features of the Landau bands, are obtained. It is found that the optical field generates a characteristic structure at one wing of the emission pattern.
Surface plasmon driven lowering of the electron emission order in a carbon/gold bilayer film
Authors: Greig S. R. , Morteza-Najarian A. , McCreery R. L. , Elezzabi A. Y.
Published: November 2016

We demonstrate the reduction of the nonlinear surface plasmon driven electron emission order from a bilayer of electron beam evaporated carbon (eC) and gold (Au). Higher confined electric fields, and the presence of sp2/sp3 clustering in the eC layer increase the electron emission at lower orders via field-driven energy gain. This bilayer provides a platform for ultrafast surface plasmon driven electron sources.
A versatile setup for ultrafast broadband optical spectroscopy of coherent collective modes in strongly correlated quantum systems
Authors: Baldini Edoardo , Mann Andreas , Borroni Simone , Arrell Christopher , van Mourik Frank , Carbone Fabrizio
Published: November 2016

A femtosecond pump-probe setup is described that is optimised for broadband transient reflectivity experiments on solid samples over a wide temperature range. By combining high temporal resolution and a broad detection window, this apparatus can investigate the interplay between coherent collective modes and high-energy electronic excitations, which is a distinctive characteristic of correlated electron systems. Using a single-shot readout array detector at frame rates of 10 kHz allows resolving coherent oscillations with amplitudes <10−4. We demonstrate its operation on the charge-transfer insulator La2CuO4, revealing coherent phonons with frequencies up to 13 THz and providing access into their Raman matrix elements.
Effects of partially replacing barley with sugar beet pulp, with and without roasted canola seeds, on performance, rumen histology and fermentation patterns in finishing Arabian lambs
Authors: Asadollahi S. , Sari M. , Erafanimajd N. , Chaji M. , Mamoui M. , Kiani A.
Published: November 2016

This study investigated the effects of partially replacing barley grains with sugar beet pulp (SBP), with and without roasted canola seed (RCS) on ruminal pH, ruminal volatile fatty acid (VFA) concentrations, ruminal histomorphometric characteristics, and performance in finishing lambs fed a high concentrate diet. Twenty-four Arabian male lambs (23.7 ± 2.5 kg bodyweight, 118 ± 10 days in age) were used for 99 days in a completely randomised design with a 2 × 2 factorial arrangement. Lambs were fed with a high concentrate diet containing (1) 68% barley (B) (2) barley plus 7% RCS (B + RCS) (3) 36% SBP, (4) SBP plus 7% RCS (SBP + RCS). Ruminal fluid pH and VFA concentrations were determined at 0, 2, 4 and 8 h post-feeding 1 day before slaughter day. Tissue samples were collected for histomorphometric study at slaughter day. Average daily gain of the lambs was not affected by partial replacement of barley with SBP, however it was improved by RCS inclusion (P < 0.05). Diets with RCS had significantly lower (P < 0.05) neutral detergent fibre and acid detergent fibre digestibility values than diets without RCS (P < 0.05). Both SBP and RCS increased ruminal pH, molar proportions of acetate, isobutyrate but decreased molar proportion of propionate in rumen content (P < 0.05). The height, width, epithelial thickness and tunica muscularis of rumen papilla and reticulum folds were increased by SBP (P < 0.05). Density of reticulum folds were higher in lambs fed by higher SBP (P < 0.05). Inclusion of RCS significantly increased papillae height and thickness of epithelium (P < 0.05). In conclusion, partially replacing barley with SBP as well as RCS inclusion prevented a drop in the ruminal pH, and improved the morphology of the rumen-reticulum in finishing lambs fed a high concentrate diet.
Synthesis of Side-Chain Modified Peptides Using Iterative Solid Phase ‘Click' Methodology
Authors: Liu Xuejian , Elmes Robert B. P. , Jolliffe Katrina A.
Published: November 2016

A series of side-chain modified peptides have been prepared via an iterative sequence of peptide couplings and azide–alkyne cycloadditions (‘click’ reactions) using Fmoc-solid phase peptide synthesis. This efficient modular synthetic route allows the systematic and sequential incorporation of a variety of side-chain modifications onto short peptides. The versatility of this approach was demonstrated by the synthesis of a series of short peptides with appended anion recognition motifs and fluorescent indicators.
Quantification of deep soil carbon by a wet digestion technique
Authors: Sangmanee Podjanee , Dell Bernard , Harper Richard J. , Henry David J.
Published: November 2016

Two wet digestion methods were evaluated using pure kaolinite as background for quantifying small concentrations of carbon (<0.05% total organic carbon (TOC)) in deep kaolinitic regolith in south-western Australia. The limit of detection and limit of quantification of the Walkley–Black method (0.015 and 0.050% TOC respectively) were approximately five times lower than those of the Heanes method (0.085 and 0.281% TOC respectively). Both methods showed excellent linearity (R2>0.99) using prepared standards (lignin, humic acid, cellulose and chitin mixed with kaolinite and their combinations), in the concentration range 0.008–1.000% TOC. However, the percentage carbon recovery values were underestimated for chitin. The Walkley–Black method (TOCWB, %) was evaluated with 94 calibration and 27 validation deep soil samples (1–35m soil depth) and compared with a dry combustion (Elementar) technique (TOCactual, %). The predictive equation (TOCactual=1.66TOCWB+0.018) (R2=0.91) obtained from the calibration set agreed well with the benchmark dry combustion values (root mean square error=0.017) and is recommended for quantification of deep soil carbon in other kaolinitic regoliths.
Phosphatidylinositol 3-kinase inhibition restores Ca
2+
release defects and prolongs survival in myotubularin-deficient mice
Authors: Kutchukian Candice , Lo Scrudato Mirella , Tourneur Yves , Poulard Karine , Vignaud Alban , Berthier Christine , Allard Bruno , Lawlor Michael W. , Buj-Bello Ana , Jacquemond Vincent
Published: November 2016

Significance

Myotubular myopathy is a fatal muscle disease due to deficiency in a phosphoinositide 3-phosphatase called myotubularin. We identify critical alterations involved in the pathophysiology of the disease, and we reveal the beneficial effect of a pharmacological treatment. Specifically, we demonstrate that the disease-associated dysfunction of Ca
2+
signaling is strongly heterogeneous at the subcellular level, affects the amplitude and activation kinetics of sarcoplasmic reticulum Ca
2+
release, and promotes a Ca
2+
-gated opening mode of the calcium release channels. Pharmacological inhibition of phosphoinositide 3-kinase activity substantially alleviates these functional defects and prolongs survival of myotubularin-deficient mice, suggesting a crucial role of this kinase activity in the dysfunction of Ca
2+
homeostasis and a potential benefit of this therapeutic approach for the disease.
How constraints affect the hunter’s decision to shoot a deer
Authors: Diekert Florian K. , Richter Andries , Rivrud Inger Maren , Mysterud Atle
Published: November 2016

Significance

Wildlife populations in Europe and North America are regulated through hunting, as natural predators are still scarce. Therefore, wildlife is a social–ecological system with delicate feedbacks between the social and ecological subsystems. Both for population control and for evolution and because of cultural values, it is essential to understand how many and which animals are removed from the population. However, the question of how the social context influences the individual hunter’s decision to shoot or not to shoot an animal has not been addressed. We apply insights from economic search theory to explain how hunter selection is shaped by social constraints. We provide convincing evidence, using a unique dataset from deer hunting, that selectivity declines with more hunters competing and a shorter remaining season.
Deglacial temperature history of West Antarctica
Authors: Cuffey Kurt M. , Clow Gary D. , Steig Eric J. , Buizert Christo , Fudge T. J. , Koutnik Michelle , Waddington Edwin D. , Alley Richard B. , Severinghaus Jeffrey P.
Published: November 2016

Significance

The magnitude and timing of Antarctic temperature change through the last deglaciation reveal key aspects of Earth’s climate system. Prior attempts to reconstruct this history relied on isotopic indicators without absolute calibration. To overcome this limitation, we combined isotopic data with measurements of in situ temperatures along a 3.4-km-deep borehole. Deglacial warming in Antarctica was two to three times larger than the contemporaneous global temperature change, quantifying the extent to which feedback processes amplify global changes in polar regions, a key prediction of climate models. Warming progressed earlier in Antarctica than in the Northern Hemisphere but coincident with glacier recession in southern mountain ranges, a manifestation of changing oceanic heat transport, insolation, and atmospheric CO2that can further test models.
Carrier dynamics and the role of surface defects: Designing a photocatalyst for gas-phase CO
2
reduction
Authors: Hoch Laura B. , Szymanski Paul , Ghuman Kulbir Kaur , He Le , Liao Kristine , Qiao Qiao , Reyes Laura M. , Zhu Yimei , El-Sayed Mostafa A. , Singh Chandra Veer , Ozin Geoffrey A.
Published: November 2016

Significance

In this work, we investigate the role of defects on the electronic and photocatalytic properties of In
2
O
3
-
x
(OH)
y
nanoparticles that have been shown to effectively reduce CO
2
to CO via the reverse water–gas shift reaction under light. To understand how such defects affect photogenerated electrons and holes in these materials, we studied the relaxation dynamics of these nanoparticles with varying concentration of defects. This analysis showed that higher defect concentrations result in longer excited-state lifetimes, which are attributed to improved charge separation and correlate well with the observed trends in the photocatalytic activity.
Mechanism of the intrinsic arginine finger in heterotrimeric G proteins
Authors: Mann Daniel , Teuber Christian , Tennigkeit Stefan A. , Schröter Grit , Gerwert Klaus , Kötting Carsten
Published: November 2016

Significance

The α-subunit of heterotrimeric G proteins is a molecular switch that mediates a great number of physiological processes such as vision, smelling, and blood pressure regulation. A GTPase-activating protein (GAP) [e.g. regulator of G protein signaling 4 (RGS4) in the case of Gα
i1
] regulates the off-switch by catalyzing GTP hydrolysis. Here, we present the molecular reactions of GAP catalysis at atomic resolution using a combination of FTIR spectroscopy and biomolecular simulations. In contrast to X-ray structures, not GTP analogs but GTP itself is used. This approach is crucial to reveal now a previously undescribed GAP mechanism for Gα. A key player of the hydrolysis reaction, called the arginine finger, is pushed from a monodentate γ-GTP coordination toward a bidentate α-γ-GTP coordination by RGS4, and thereby catalyzes GTP-hydrolysis.
Aerosol indirect effect from turbulence-induced broadening of cloud-droplet size distributions
Authors: Chandrakar Kamal Kant , Cantrell Will , Chang Kelken , Ciochetto David , Niedermeier Dennis , Ovchinnikov Mikhail , Shaw Raymond A. , Yang Fan
Published: November 2016

Significance

Atmospheric aerosol concentration is linked to cloud brightness and lifetime through the modulation of precipitation. Generally speaking, larger cloud droplets and wider-droplet size distributions form precipitation more efficiently. We create steady-state clouds in the laboratory through a balance of constant aerosol injection and cloud-droplet removal due to settling. As aerosol concentration is decreased, the cloud-droplet mean diameter increases, as expected, but also the width of the size distribution increases sharply. Theory, simulations, and measurements point to greater supersaturation variability as the cause of this broadening in what can be considered a low aerosol/slow microphysics limit.
Programmable and reversible plasmon mode engineering
Authors: Yang Ankun , Hryn Alexander J. , Bourgeois Marc R. , Lee Won-Kyu , Hu Jingtian , Schatz George C. , Odom Teri W.
Published: November 2016

Significance

Plasmonic nanostructures that can amplify localized optical fields and support ultranarrow resonances are critical for applications ranging from ultrasensitive molecular sensing to nanoscale lasing. However, the active engineering and maintaining of narrow resonances over a broad range of wavelengths, within a single system, is a grand challenge. In this paper, we introduce a platform that can overcome the limitations of as-fabricated nanoparticle arrays as well as toggle between different lattice plasmon mode orders (dipolar or quadrupolar) by mechanical manipulation of the sample along different symmetry directions. Dynamic tuning of narrow lattice plasmons (<5 nm) was possible over the entire visible wavelength range, which now opens possibilities in real-time optical systems and flexible electronics.
Two crystal structures reveal design for repurposing the C-Ala domain of human AlaRS
Authors: Sun Litao , Song Youngzee , Blocquel David , Yang Xiang-Lei , Schimmel Paul
Published: November 2016

Significance

Here we present an exception that supports the rule that the 20 human tRNA synthetases acquired new architectures to expand their functions during evolution. The new features are associated with novel, appended domains that are absent in prokaryotes and retained by their many splice variants. Alanyl-tRNA synthetase (AlaRS) is the single example that has a prototypical appended domain—C-Ala—even in prokaryotes, which is spliced out in humans. X-ray structural, small-angle X-ray scattering, and functional analysis showed that human C-Ala lost its prokaryotic tRNA functional role and instead was reshaped into a nuclear DNA-binding protein. Thus, we report another paradigm for tRNA synthetase acquisition of a novel function, namely, repurposing a preexisting domain rather than addition of a new one.
Multistep regulation of autophagy by WNK1
Authors: Gallolu Kankanamalage Sachith , Lee A-Young , Wichaidit Chonlarat , Lorente-Rodriguez Andres , Shah Akansha M. , Stippec Steve , Whitehurst Angelique W. , Cobb Melanie H.
Published: November 2016

Significance

With-no-lysine (K) 1 (WNK1) is widely expressed, yet little is known about its actions beyond its well-studied regulation of ion transport proteins. We find that WNK1 suppresses autophagy in multiple cell types, indicative of WNK1 actions outside of ion transport. Because autophagy is a complex cellular pathway with many regulatory inputs, identifying steps influenced by WNK1 may also be of value to better understand how autophagy is controlled. Our results show a connection between WNK1 and regulation of PI3KC3 that may have implications for other processes mediated by products of this lipid kinase complex. This study demonstrates a function of WNK1 as a regulator of autophagy.
Map reading, navigating from maps, and the medial temporal lobe
Authors: Urgolites Zhisen J. , Kim Soyun , Hopkins Ramona O. , Squire Larry R.
Published: November 2016

Significance

The hippocampus has been linked to both memory and spatial cognition, but these ideas are not entirely compatible. We administered navigation tasks in which participants transformed map coordinates into geographical coordinates to follow paths indicated on maps. Patients with limited hippocampal lesions performed normally. A patient with large lesions that damaged the hippocampus as well as the adjacent parahippocampal gyrus was impaired. All the patients were impaired at remembering facts about the task. The findings suggest that the spatial computations needed for navigating from maps are independent of the hippocampus. The impairment after large medial temporal lobe lesions may result from damage to the posterior parahippocampal gyrus. The findings emphasize the importance of the hippocampus for memory functions.
DNA methylome of the 20-gigabase Norway spruce genome
Authors: Ausin Israel , Feng Suhua , Yu Chaowei , Liu Wanlu , Kuo Hsuan Yu , Jacobsen Elise L. , Zhai Jixian , Gallego-Bartolome Javier , Wang Lin , Egertsdotter Ulrika , Street Nathaniel R. , Jacobsen Steven E. , Wang Haifeng
Published: November 2016

Significance

There are two main groups of land plants, flowering plants (also referred to as angiosperms) and gymnosperms. Compared with angiosperms, gymnosperms have larger genomes, often approximately 20 Gb, and have a higher abundance of transposons and other repetitive elements that are silenced by DNA methylation. Here, we present a whole genome single-base resolution DNA methylation analysis of the important conifer Norway spruce (
Picea abies
), providing an important resource for the epigenetic study of this species. We show that the Norway spruce genome is heavily methylated because of high transposon content. In addition, we also show that somatic embryogenesis cultures used in the industry show altered DNA methylation patterning.
Global analysis of genomic instability caused by DNA replication stress in
Saccharomyces cerevisiae
Authors: Zheng Dao-Qiong , Zhang Ke , Wu Xue-Chang , Mieczkowski Piotr A. , Petes Thomas D.
Published: November 2016

Significance

One important source of genomic instability associated with tumor cells is DNA replication stress. In the current study, replication stress was induced in yeast by a 10-fold reduction in the level of the replicative DNA polymerase δ. By DNA microarray analysis and high-throughput DNA sequencing, we showed that this stress resulted in very high rates of both large (aneuploidy, mitotic recombination, deletions and duplications, and translocations) and small (point mutations and small insertion/deletions) genetic alterations. Some of these changes resulted in a selective growth advantage of the cells, demonstrating the role of elevated genetic instability in the rapid evolution of cells in challenging growth conditions.
Opinion polling and construction of public opinion in newspaper discourses during the Umbrella Movement
Authors: Lee Francis L. F.
Published: November 2016

Public opinion not only influences the likelihood of success for a protest movement; images of public opinion can also be used to legitimize or delegitimize a protest. In contemporary societies, opinion polling is the most authoritative way to “measure” public opinion. Yet the meanings of poll findings need to be interpreted and are often contested. Following these premises, this article analyzes the construction of images of public opinion through polling during the Umbrella Movement. The analysis illustrates the discursive strategies involved in selective reporting of opinion polls by newspapers with different political stances. It also demonstrates how poll results were articulated with other assumptions, principles, and discourses to generate claims about the legitimacy or proper strategies of the movement. On the whole, the analysis shows how public opinion, as a discursive category, was brought to bear on the dynamics of the Umbrella Movement through polling and its communication.
Rational-experiential thinking style and rational intergroup cooperation: the moderating role of intergroup conflict / Estilos de pensamiento racional-experiencial y la cooperación intergrupal racional: el rol modulador del conflicto intergrupal
Authors: Peñarroja Vicente , Serrano Miguel A. , Gracia Esther , Alacreu-Crespo Adrián , González Patricia , Martínez-Tur Vicente
Published: November 2016

Cooperative relationships between groups are difficult because of the high human capability to differentiate between in-group vs. out-group members. This obstacle exists even when the groups can obtain benefits for themselves from cooperation with other groups (rational cooperation). Based on an interactionist approach, the authors propose that personal (individual differences) and situational (conflicts) factors contribute to rational intergroup cooperation. The authors conducted a preliminary correlational study (Study 1) and an experimental investigation (Study 2). In Study 1, the authors examined, with 105 participants, the psychometric properties of the Spanish version of the Rational–Experiential Inventory (REI), measuring individual differences in information processing. In Study 2, the authors conducted an experimental investigation with 141 participants, testing the role of individual differences and conflict in intergroup rational cooperation. Findings of Study 1 showed that the scale has adequate psychometric properties. Results of Study 2 confirmed that the existence of both manipulated and perceived intergroup conflict reduces the magnitudes of the relationships between rational ability and rational cooperation. In addition, perceived intergroup conflict increased the magnitude of the links from experiential ability and experimental engagement to rational cooperation. Both individual differences and previous conflict have a role in predicting rational intergroup cooperation. According to the interactionist approach, personal and situational factors should be considered in the understanding of intergroup relationships.