bluuebunny/crossref_metadata_2025 huggingface dataset:
Spontaneous micro-modification of single-layer graphene induced by femtosecond laser irradiation
Authors: Cheng Chen , He Ruiyun , Romero Carolina , Vázquez de Aldana Javier R. , Chen Feng
Published: December 2017

Permanent micro-modifications in single-layer graphene with a spontaneous periodic structural change have been induced by femtosecond (fs) laser irradiation. These modifications present a regular variation along the radial direction from a central ablated region. Based on the obtained micro-Raman spectrum and the reflective micro-spectrum of laser-irradiated graphene, structural modification with periodic variations containing several spectral regimes has been observed, which was in good agreement with periodic topography of the structure observed using an atomic force microscope. It has also been found that several regions of the laser induced structures were with different optical properties, which were identified to be correlated with different modification mechanisms. In addition, after fs laser processing, graphene still maintains crystallinity. This work may be helpful for the development of graphene-based microstructures or devices by fs laser pulses.
Weakly nonlinear convection induced by the sequestration of CO2 in a perfectly impervious geological formation
Authors: Vo Liet , Hadji Layachi
Published: December 2017

Linear and weakly nonlinear stability analyses are performed to investigate the dissolution-driven convection induced by the sequestration of carbon dioxide in a perfectly impervious geological formation. We prescribe Neumann concentration boundary conditions at the rigid upper and lower walls that bound a fluid saturated porous layer of infinite horizontal extent. We envisage the physical situation wherein the top boundary is shut after a certain amount of positively buoyant super-critical carbon-dioxide has been injected. We model this situation by considering a Rayleigh-Taylor like base state consisting of carbon-rich heavy brine overlying a carbon-free layer and seek the critical thickness at which the top layer has acquired enough potential energy for fluid overturning to occur. We quantify the influence of carbon diffusion anisotropy, permeability dependence on depth and the presence of a first order chemical reaction between the carbon-rich brine and host mineralogy on the threshold instability conditions and associated flow patterns using classical normal modes approach and paper-and-pencil calculations. The critical Rayleigh number and corresponding wavenumber are found to be independent of the depth of the formation. The weakly nonlinear analysis is performed using long wavelength asymptotics, the validity of which is limited to small Damköhler numbers. We derive analytical expressions for the solute flux at the interface, the location of which corresponds to the minimum depth of the boundary layer at which instability sets in. We show that the interface acts like a sink leading to the formation of a self-organized exchange between descending carbon-rich brine and ascending carbon free brine. We delineate necessary conditions for the onset of the fingering pattern that is observed in laboratory and numerical experiments when the constant flux regime is attained. Using the derived interface flux conditions, we put forth differential equations for the time evolution and deformation of the interface as it migrates upward while the carbon dioxide is dissolving into the ambient brine. We solve for the terminal time when the interface reaches the top boundary thereby quantifying the time it takes for an initial amount of injected super-critical carbon dioxide to have completely dissolved within ambient brine thus signaling the start of the shutdown regime.
Another resolution of the configurational entropy paradox as applied to hard spheres
Authors: Baranau Vasili , Tallarek Ulrich
Published: December 2017

Ozawa and Berthier [J. Chem. Phys. 146, 014502 (2017)] recently studied the configurational and vibrational entropies Sconf and Svib from the relation Stot = Sconf + Svib for polydisperse mixtures of spheres. They noticed that because the total entropy per particle Stot/N shall contain the mixing entropy per particle kBsmix and Svib/N shall not, the configurational entropy per particle Sconf/N shall diverge in the thermodynamic limit for continuous polydispersity due to the diverging smix. They also provided a resolution for this paradox and related problems—it relies on a careful redefining of Sconf and Svib. Here, we note that the relation Stot = Sconf + Svib is essentially a geometric relation in the phase space and shall hold without redefining Sconf and Svib. We also note that Stot/N diverges with N → ∞ with continuous polydispersity as well. The usual way to avoid this and other difficulties with Stot/N is to work with the excess entropy ΔStot (relative to the ideal gas of the same polydispersity). Speedy applied this approach to the relation above in his work [Mol. Phys. 95, 169 (1998)] and wrote this relation as ΔStot = Sconf + ΔSvib. This form has flaws as well because Svib/N does not contain the kBsmix term and the latter is introduced into ΔSvib/N instead. Here, we suggest that this relation shall actually be written as ΔStot = ΔcSconf + ΔvSvib, where Δ = Δc + Δv, while ΔcSconf = Sconf − kBNsmix and ΔvSvib=Svib−kBN1+lnVΛdN+UNkBT with N, V, T, U, d, and Λ standing for the number of particles, volume, temperature, internal energy, dimensionality, and de Broglie wavelength, respectively. In this form, all the terms per particle are always finite for N → ∞ and continuous when introducing a small polydispersity to a monodisperse system. We also suggest that the Adam–Gibbs and related relations shall in fact contain ΔcSconf/N instead of Sconf/N.
Interaction of a magnetic island chain in a tokamak plasma with a resonant magnetic perturbation of rapidly oscillating phase
Authors: Fitzpatrick Richard
Published: December 2017

An investigation is made into the interaction of a magnetic island chain, embedded in a tokamak plasma, with an externally generated magnetic perturbation of the same helicity whose helical phase is rapidly oscillating. The analysis is similar in form to the classic analysis used by Kapitza [Sov. Phys. JETP 21, 588 (1951)] to examine the angular motion of a rigid pendulum whose pivot point undergoes rapid vertical oscillations. The phase oscillations are found to modify the existing terms, and also to give rise to new terms, in the equations governing the secular evolution of the island chain's radial width and helical phase. An examination of the properties of the new secular evolution equation reveals that it is possible to phase-lock an island chain to an external magnetic perturbation with an oscillating helical phase in a stabilizing phase relation provided that the amplitude, ϵ, of the phase oscillations (in radians) is such that |J0(ϵ)|≪1, and the mean angular frequency of the perturbation closely matches the natural angular frequency of the island chain.
Study on the effects of indentation-induced dislocations on the detector performance of CdZnTe crystals
Authors: Fu Xu , Xu Yadong , Gu Yaxu , Jia Ningbo , Xu Lingyan , Zha Gangqiang , Wang Tao , Jie Wanqi
Published: December 2017

The effects of indentation-induced dislocations on spectroscopic performances of CdZnTe detectors and on the deep-level defects of CdZnTe crystals are studied. The mobility-lifetime product (μτ) for electrons of the as-grown sample is determined to be 1.2 × 10−3 cm2/V by the γ-ray energy spectral measurement. However, the value reduced to 4.5 × 10−4 cm2/V after the dislocation is artificially increased by indentation. Meanwhile, the energy resolution is deteriorated from 7.45% to 28.15%. The ion beam induced charge (IBIC) measurements showed quite low carrier collection efficiency of electrons in the dislocation enriched areas. Moreover, the carrier recombination rate at dislocations was reduced with the increase in applied voltage. The thermally stimulated current measurements showed that the concentration of dislocation related defect levels observed at 0.107 eV and 0.159 eV increased almost twice after indentation. These defect levels could probably result in the carrier loss during the γ-ray energy spectrum and IBIC measurements.
Optimum efficiency control of a wind turbine with unknown desired trajectory and actuator faults
Authors: Habibi Hamed , Rahimi Nohooji Hamed , Howard Ian
Published: December 2017

The operational wind turbine efficiency in the power maximization regions and reliability improvement to reduce the produced power cost can both be enhanced by using an appropriate controller to cope with the highly nonlinear behavior of wind turbines in the presence of wind speed variation and actuator faults. In this regard, a nonlinear controller is proposed to make the wind turbine operate effectively despite some of the actuator faults, similar to the fault-free case. The considered actuator faults are pitch and generator actuator biases, as well as pitch actuator dynamic change, including pump wear, hydraulic leak, and high air content in the oil. Also, the wind speed is assumed to be an unmeasurable disturbance, and, accordingly, when using the neural network scheme, the unknown desired trajectory is reconstructed, so that the captured power is maximized. The proposed controller is shown to be able to keep the wind turbine tracking the reconstructed desired trajectory with sufficient accuracy. By using the Lyapunov analysis, the boundedness of the closed-loop system with the proposed controller is proven. The designed controller is verified via numerical simulations. The effectiveness of the proposed controller is evaluated in comparison with industrial constant gain controller results.
On degenerate metrics, dark matter and unification
Authors: Searight Trevor P.
Published: December 2017

A five-dimensional theory of relativity is presented which suggests that gravitation and electromagnetism may be unified using a degenerate metric. There are four fields (in the four-dimensional sense): a tensor field, two vector fields, and a scalar field, and they are unified with a combination of a gauge-like invariance and a reflection symmetry which means that both vector fields are photons. The gauge-like invariance implies that the fifth dimension is not directly observable; it also implies that charge is a constant of motion. The scalar field is analogous to the Brans-Dicke scalar field, and the theory tends towards the Einstein-Maxwell theory in the limit as the coupling constant tends to infinity. As there is some scope for fields to vary in the fifth dimension, it is possible for the photons to have wave behaviour in the fifth dimension. The wave behaviour has two effects: it gives mass to the photons, and it prevents them from interacting directly with normal matter. These massive photons still act as a source of gravity, however, and therefore they are candidates for dark matter.
Design of multi-frequency acoustic kinoforms
Authors: Brown Michael D. , Cox Ben T. , Treeby Bradley E.
Published: December 2017

Complex diffraction limited acoustic fields can be generated from a single element transducer using inexpensive 3-D printable acoustic kinoforms. This is extremely promising for a number of applications. However, the lack of ability to vary the field limits the potential use of this technology. In this work, this limitation is circumvented using multi-frequency acoustic kinoforms for which different acoustic fields are encoded onto different driving frequencies. An optimisation approach based on random downhill binary search is introduced for the design of the multi-frequency kinoforms. This is applied to two test cases to demonstrate the technique: a kinoform designed to generate the numerals “1,” “2,” and “3” in the same plane but at different driving frequencies, and a kinoform designed to generate 3 sets of eight foci lying on a circle with a driving-frequency-dependent radius. Field measurements from these samples confirmed that multi-frequency acoustic kinoforms can be designed that switch between different arbitrary, pre-designed, acoustic field patterns in the target plane by changing the driving frequency.
Blue emission in photoluminescence spectra of the red phosphor CaAlSiN3:Eu2+ at low Eu2+ concentration
Authors: Suda Yoriko , Kamigaki Yoshiaki , Yamamoto Hajime
Published: December 2017

In red phosphor CaAlSiN3:Eu2+, unintentional blue emission occurs with increasing intensity at low Eu2+ concentrations and also at low measurement temperatures. Time-resolved photoluminescence measurements were used to confirm the decrease in red emission and increase in blue emission with the decreasing Eu2+ concentration. The peak timing of blue emission occurred faster than that of red emission, and long lasting luminescence of red emission was observed as well as that of blue emission. The Eu2+ concentration dependences of the red and blue emissions were similar to those of the g values 4.75 (Eu2+) and 2.0025 (nitrogen vacancies), respectively, which were observed from electron spin resonance (ESR) measurements. The origin of the blue emission is proposed to be nitrogen vacancy defects, which had about the same ESR signal intensity as that of Eu2+ ions in CaAlSiN3:Eu2+ containing 0.01 at. % Eu2+. The possibility of red emission also arising from excited electron tunneling or thermal pathways via nitrogen vacancies is discussed. Long lasting red emission was observed, which is proposed to involve trapped electrons remaining at nitrogen vacancies, yielding blue emission and inducing red emission from Eu2+ ions.
An optical method for measuring exhaust gas pressure from an internal combustion engine at high speed
Authors: Leach Felix C. P. , Davy Martin H. , Siskin Dmitrij , Pechstedt Ralf , Richardson David
Published: December 2017

Measurement of exhaust gas pressure at high speed in an engine is important for engine efficiency, computational fluid dynamics analysis, and turbocharger matching. Currently used piezoresistive sensors are bulky, require cooling, and have limited lifetimes. A new sensor system uses an interferometric technique to measure pressure by measuring the size of an optical cavity, which varies with pressure due to movement of a diaphragm. This pressure measurement system has been used in gas turbine engines where the temperatures and pressures have no significant transients but has never been applied to an internal combustion engine before, an environment where both temperature and pressure can change rapidly. This sensor has been compared with a piezoresistive sensor representing the current state-of-the-art at three engine operating points corresponding to both light load and full load. The results show that the new sensor can match the measurements from the piezoresistive sensor except when there are fast temperature swings, so the latter part of the pressure during exhaust blowdown is only tracked with an offset. A modified sensor designed to compensate for these temperature effects is also tested. The new sensor has shown significant potential as a compact, durable sensor, which does not require external cooling.
Axisymmetric global Alfvén eigenmodes within the ellipticity-induced frequency gap in the Joint European Torus
Authors: Oliver H. J. C. , Sharapov S. E. , Breizman B. N. , Zheng L.-J. ,   JET Contributors
Published: December 2017

Alfvén eigenmodes (AEs) with toroidal mode number n = 0 (i.e., axisymmetric) have been observed in the ellipticity-induced frequency range in the Joint European Torus. The axisymmetric modes are of interest because they can be used to diagnose fast particle energy distributions at the mode location. The modes were identified as global Alfvén eigenmodes (GAEs), with the ellipticity of the plasma cross-section preventing strong continuum damping of the modes. The MHD codes CSCAS, MISHKA, and AEGIS were used to compute the n = 0 Alfvén continuum, eigenmode structure, and continuum damping. For zero ellipticity, a single mode exists at a frequency below the Alfvén continuum branch. This mode has two dominant poloidal harmonics with poloidal mode numbers m = ±1 that have the same polarity; therefore, it is an even mode. For finite ellipticity, the continuum branch splits into two branches and the single GAE splits into two modes. An even mode exists below the minimum of the top continuum branch, and the frequency of this mode coincides with the experimentally observed AE frequency. The other mode is found below the lower continuum branch with opposite signs between the two poloidal harmonics (an odd mode structure). This mode was not excited in our experiment. Analytical theory for the n = 0 GAE in an elliptical cylinder shows the n = 0 Alfvén continuum agrees with the numerical modelling.
Modeling of grain-oriented Si-steel and amorphous alloy iron core under ferroresonance using Jiles–Atherton hysteresis method
Authors: Sima Wenxia , Zou Mi , Yang Ming , Yang Qing , Peng Daixiao
Published: December 2017

Amorphous alloy is increasingly widely used in the iron core of power transformer due to its excellent low loss performance. However, its potential harm to the power system is not fully studied during the electromagnetic transients of the transformer. This study develops a simulation model to analyze the effect of transformer iron core materials on ferroresonance. The model is based on the transformer π equivalent circuit. The flux linkage–current (ψ–i) Jiles–Atherton reactor is developed in an Electromagnetic Transients Program-Alternative Transients Program and is used to represent the magnetizing branches of the transformer model. Two ferroresonance cases are studied to compare the performance of grain-oriented Si-steel and amorphous alloy cores. The ferroresonance overvoltage and overcurrent are discussed under different system parameters. Results show that amorphous alloy transformer generates higher voltage and current than those of grain-oriented Si-steel transformer and significantly harms the power system safety.
Optical second harmonic generation analysis of the atomically stepped Au/TiO2 (320) interface
Authors: Haque Md Ehasanul , Kobayashi Daiki , Tomatsu Yuki , Hien Khuat Thi Thu , Mizutani Goro , Rahman Mohammad Mizanur , Rutt Harvey N.
Published: December 2017

A gold thin film with the thickness of 2nm on the TiO2(320) substrate has been fabricated in a UHV chamber at the pressure of 2x10-7 Torr. We observed the second harmonic response from the Au/TiO2(320) interface and bare TiO2(320) as a function of the rotation angle around the surface normal by using of a pulsed Nd3+:YAG laser as the excitation light at a photon energy of 1.17 eV and 2.33 eV. An isotropic response was observed from both samples for 1.17 eV photon energy excitation. In contrast, an anisotropic response was observed from both samples for 2.33 eV photon energy excitation. From the Au/TiO2(320) interface, anisotropic structure of SHG response was observed in the [2¯30] direction for Pin/Pout polarization combination. Nonlinear susceptibility elements were decomposed and two groups of them were assigned as the main contribution from the step and terrace of the vicinal TiO2 surface.
Investigation of shape, position, and permeability of shielding material in quadruple butterfly coil for focused transcranial magnetic stimulation
Authors: Rastogi Priyam , Zhang Bowen , Tang Yalun , Lee Erik G. , Hadimani Ravi L. , Jiles David C.
Published: December 2017

Transcranial magnetic stimulation has been gaining popularity in the therapy for several neurological disorders. A time-varying magnetic field is used to generate electric field in the brain. As the development of TMS methods takes place, emphasis on the coil design increases in order to improve focal stimulation. Ideally reduction of stimulation of neighboring regions of the target area is desired. This study, focused on the improvement of the focality of the Quadruple Butterfly Coil (QBC) with supplemental use of different passive shields. Parameters such as shape, position and permeability of the shields have been explored to improve the focus of stimulation. Results have been obtained with the help of computer modelling of a MRI derived heterogeneous head model over the vertex position and the dorsolateral prefrontal cortex position using a finite element tool. Variables such as maximum electric field induced on the grey matter and scalp, volume and area of stimulation above half of the maximum value of electric field on the grey matter, and ratio of the maximum electric field in the brain versus the scalp have been investigated.
Improvement of gas-sensing performance of ZnO nanorods by group-I elements doping
Authors: Sáaedi Abdolhossein , Yousefi Ramin
Published: December 2017

In the present work, a comparative study of gas sensor performance of group-I-doped (Na- and K-doped) ZnO nanorods to ethanol was carried out for the first time. The nanorods were grown on SiO2/Si substrates by a thermal evaporation method, using a tube furnace. X-ray photoelectron spectroscopy (XPS) results confirmed that the K and Na were doped in the ZnO nanorods. Furthermore, the XPS spectra indicated that the K-doped ZnO nanorods were grown by more oxygen vacancy compared with the Na-doped ZnO nanorods. Room temperature photoluminescence results confirmed the XPS results about oxygen vacancy level of the doped samples. The doped ZnO nanorods showed excellent gas-sensing performance against ethanol in comparison with the undoped ZnO nanorods. The K-doped ZnO nanorods revealed a high gas sensing at the operating temperature of 300 °C, while the operating temperature of the Na-doped was 280 °C. Moreover, the response and recovery time of the doped samples were shorter than those of the undoped sample. The enhanced gas-sensing performance of doped ZnO nanorods is attributed to the larger amount of oxygen vacancy in the doped ZnO nanorods. Furthermore, group-I-doped ZnO nanorods performed good selectivity compared with the undoped ZnO nanorods.
Effect of lower hybrid current drive on pedestal instabilities in the HL-2A tokamak
Authors: Xiao G. L. , Zhong W. L. , Zou X. L. , Duan X. R. , Liu A. D. , Bai X. Y. , Cheng J. , Cui Z. Y. , Delpech L. , Ding X. T. , Dong J. Q. , Ekedahl A. , Feng B. B. , Giruzzi G. , Gao J. M. , Goniche M. , Hoang G. T. , Ji X. Q. , Jiang M. , Lu B. , Mazon D. , Peysson Y. , Rao J. , Song S. D. , Song X. M. , Shi Z. B. , Wang C. , Xu M. , Yan L. W. , Yang Z. C. , Yu D. L. , Zeng H. , Zhang B. Y. , Zhang Y. P. , Zhou Y. ,   HL-2A Team
Published: December 2017

Edge localized mode (ELM) mitigation with lower hybrid current drive (LHCD) has been observed in the HL-2A tokamak. This mitigation effect is very sensitive to the parameters as the plasma density and the LHCD absorbed power, i.e., more easily to be observed for high density and large LHCD absorbed power. The divertor peak heat load released by ELM has been significantly reduced during the mitigation phase. The pedestal density gradient is slightly reduced during ELM mitigation, and the plasma rotation velocity and ion temperature are significantly reduced by LHCD. It has been found that the ELM mitigation is not synchronized with the LHCD, while it is synchronized with the increase of the pedestal turbulence, showing that the enhancement of the transport due to the pedestal turbulence can be the direct cause of the ELM mitigation.
Cell micro-irradiation with MeV protons counted by an ultra-thin diamond membrane
Authors: Barberet Philippe , Pomorski Michal , Muggiolu Giovanna , Torfeh Eva , Claverie Gérard , Huss Cédric , Saada Samuel , Devès Guillaume , Simon Marina , Seznec Hervé
Published: December 2017

We report the development of thin single crystal diamond membranes suitable for dose control in targeted cell irradiation experiments with a proton microbeam. A specific design was achieved to deliver single protons with a hit detection efficiency approaching 100%. The membranes have thicknesses between 1.8 and 3 μm and are used as vacuum windows on the microbeam line. The impact of these transmission detectors on the microbeam spot size is estimated by Monte-Carlo simulations, indicating that a beam lateral resolution below 2 μm is achieved. This is confirmed by experiments showing the accumulation online of X-ray Repair Cross-Complementing protein 1 (XRCC1)-Green Fluorescent Protein (GFP) at DNA damaged sites in living cells.
Phase-field modeling and electronic structural analysis of flexoelectric effect at 180° domain walls in ferroelectric PbTiO3
Authors: Wang Yu-Jia , Li Jiangyu , Zhu Yin-Lian , Ma Xiu-Liang
Published: December 2017

The flexoelectric effect is the coupling between strain, polarization, and their gradients, which are prominent at the nanoscale. Although this effect is important to understand nanostructures, such as domain walls in ferroelectrics, its electronic mechanism is not clear. In this work, we combined phase-field simulations and first-principles calculations to study the 180° domain walls in tetragonal ferroelectric PbTiO3 and found that the source of Néel components is the gradient of the square of spontaneous polarization. Electronic structural analysis reveals that there is a redistribution of electronic charge density and potential around domain walls, which produces the electric field and Néel components. This work thus sheds light on the electronic mechanism of the flexoelectric effect around 180° domain walls in tetragonal ferroelectrics.
Emergence of undulating surface band upon oxygen adsorption of Fe thin film on W(110)
Authors: Souma Seigo , Honma Kohei , Sato Takafumi , Tsujikawa Masahito , Shirai Masafumi , Takahashi Takashi
Published: December 2017

We have performed high-resolution angle-resolved photoemission spectroscopy of oxygen-adsorbed Fe thin films on W(110) to elucidate the evolution of electronic states upon surface oxidation. After oxygen adsorption of 0.25 monolayer onto Fe films, we found a surface state in the vicinity of the Fermi level which exhibits an undulating energy band dispersion. Our first-principles band-structure calculation indicates that this state is attributed to the spin-polarized minority band arising from the hybridization between Fe 3d and O 2p orbitals. The present result suggests that the observed surface state is related to the unusual magnetic properties of oxidized Fe surfaces.
Application of accelerometers to record drinking behaviour of beef cattle
Authors: Williams Lauren R. , Bishop-Hurley Greg J. , Anderson Angela E. , Swain Dave L.
Published: December 2017

Accelerometers have been used to record many cattle postures and behaviours including standing, lying, walking, grazing and ruminating but not cattle drinking behaviour. This study explores whether neck-mounted triaxial accelerometers can identify drinking and whether head-neck position and activity can be used to record drinking. Over three consecutive days, data were collected from 12 yearling Brahman cattle each fitted with a collar containing an accelerometer. Each day the cattle were herded into a small yard containing a water trough and allowed 5 min to drink. Drinking, standing (head up), walking and standing (head down) were recorded. Examination of the accelerometer data showed that drinking events were characterised by a unique signature compared with the other behaviours. A linear mixed-effects model identified two variables that reflected differences in head-neck position and activity between drinking and the other behaviours: mean of the z- (front-to-back) axis and variance of the x- (vertical) axis (P < 0.05). Threshold values, derived from Kernel density plots, were applied to classify drinking from the other behaviours using these two variables. The method accurately classified drinking from standing (head up) with 100% accuracy, from walking with 92% accuracy and from standing (head down) with 79% accuracy. The study shows that accelerometers have the potential to record cattle drinking behaviour. Further development of a classification method for drinking is required to allow accelerometer-derived data to be used to improve our understanding of cattle drinking behaviour and ensure that their water intake needs are met.
Assisted colonisation trial of the eastern barred bandicoot (Perameles gunnii) to a fox-free island
Authors: Groenewegen Rebecca , Harley Dan , Hill Richard , Coulson Graeme
Published: December 2017

Context Assisted colonisation has the potential to protect species from intractable threats within their historical ranges. The Australian mainland subspecies of the eastern barred bandicoot (Perameles gunnii) is extinct in the wild, with surviving populations restricted to small sites protected by predator–barrier fences. PVA modelling shows that a self-sustaining bandicoot population would require an area free of the introduced red fox (Vulpes vulpes) of at least 2500ha. French Island is outside the historic range of the species, but is fox-free and contains around 9000ha of potentially suitable habitat. Aims This study will assess the suitability of French Island as a potential site for a self-sustaining eastern barred bandicoot population by conducting a 1-year assisted colonisation trial to assess habitat use, body condition and survival. Methods Between July and September 2012, 18 adult bandicoots were released. We radio-tracked bandicoots using intraperitoneal radio-transmitters for up to 122 days and trapped fortnightly. Key results The release group met the three measures of success: (1) appropriate habitat use; (2) recovery of post-release bodyweight; and (3) founder survival exceeding 100 days. Habitat use and body condition throughout the trial reflected that of mainland populations, and seven bandicoots survived longer than 100 days. Mortality was greatest in the first month, with veterinary investigations confirming two deaths due to cat predation, two deaths from toxoplasmosis and one unknown cause of death. Bandicoots that survived longer than 100 days occupied higher, drier ground than those that did not. Toxoplasmosis cases were associated with lower topographic position on the site. Conclusions Our results suggest that French Island provides suitable habitat for the establishment of a population of eastern barred bandicoots. On French Island, toxoplasmosis was identified as an important source of mortality in addition to cat predation, and warrants further investigation. Implications Given the costs and challenges of predator control and the maintenance of predator exclusion fences, assisted colonisation to one or more fox-free islands remains the most viable option to establish self-sustaining bandicoot populations. Our results highlight the value in conducting trial releases ahead of major translocations.
Accelerating fishes increase propulsive efficiency by modulating vortex ring geometry
Authors: Akanyeti Otar , Putney Joy , Yanagitsuru Yuzo R. , Lauder George V. , Stewart William J. , Liao James C.
Published: December 2017

Significance

The ability to move is one of the key evolutionary events that led to the complexity of vertebrate life. The most speciose group of vertebrates, fishes, displays an enormous variation of movement patterns during steady swimming. We discovered that this behavioral diversity collapses into one movement pattern when fishes are challenged to increase their swimming speed, regardless of their body size, shape, and ecology. Using flow visualization and biomimetic models, we provide the first mechanistic understanding of how this conserved movement pattern allows fishes to accelerate quickly.
Sclerostin influences body composition by regulating catabolic and anabolic metabolism in adipocytes
Authors: Kim Soohyun P. , Frey Julie L. , Li Zhu , Kushwaha Priyanka , Zoch Meredith L. , Tomlinson Ryan E. , Da Hao , Aja Susan , Noh Hye Lim , Kim Jason K. , Hussain Mehboob A. , Thorek Daniel L. J. , Wolfgang Michael J. , Riddle Ryan C.
Published: December 2017

Significance

Sclerostin exerts profound control over skeletal metabolism by regulating the osteoanabolic Wnt/β-catenin signaling pathway. In this study, we demonstrate that in addition to a dramatic increase in bone mass, Sost
−/−
mice as well as those treated with a sclerostin-neutralizing antibody exhibit a reduction in white adipose tissue mass and are protected from high fat diet feeding. This effect is associated with an increase in fatty acid oxidation and reduced de novo fatty acid synthesis in adipocytes due to increased Wnt/β-catenin signaling.
Understanding the mechanisms of amorphous creep through molecular simulation
Authors: Cao Penghui , Short Michael P. , Yip Sidney
Published: December 2017

Significance

The individual and collective molecular displacements in an amorphous solid undergoing plastic deformation are simulated by an atomistic method that allows incremental motions to be observed over a time window of fractions of seconds. Because the timescale matches well with the conditions of experimental measurements, simulation details provide dynamical evidence for the fundamental mechanisms of amorphous creep. In particular, knowledge of the interplay between diffusion (flow) and mechanical deformation processes enables us to explain the stress and temperature behavior of the experimental data as well as the validity of model descriptions of molecular mechanisms in terms of spatially and temporally heterogeneous fluctuations.
S
E
2 reaction in noncarbon system: Metal-halide catalysis for dehydrogenation of ammonia borane
Authors: Pai Sung Jin , Han Sang Soo
Published: December 2017

Significance

Ammonia borane (AB) is a promising hydrogen storage material due to its high hydrogen storage capacity. AB dehydrogenation can be facilitated by metal-halide (MCl
2
) catalysis. Here, we have elucidated the dehydrogenation mechanism of AB via MCl
2
catalysis using ab initio calculations. In contrast to a typical electrophilic substitution (S
E
) reaction occurring at a carbon atom, the nitrogen atom in AB serves as the reaction center for the S
E
reaction with the boron moiety as the leaving group when MCl
2
approaches AB. In addition, the S
E
2 backside reaction is favored as the initial step for the dehydrogenation of AB by MCl
2
. This work paves the way for the use of a new reaction in the field of BN chemistry.
Regulatory networks specifying cortical interneurons from human embryonic stem cells reveal roles for CHD2 in interneuron development
Authors: Meganathan Kesavan , Lewis Emily M. A. , Gontarz Paul , Liu Shaopeng , Stanley Edouard G. , Elefanty Andrew G. , Huettner James E. , Zhang Bo , Kroll Kristen L.
Published: December 2017

Significance

In the human cerebral cortex, activities of excitatory neurons are balanced by local inhibition provided by cortical interneurons (cINs). Although disrupted cIN development contributes to neurodevelopmental disorders, molecular networks controlling this process were largely unknown. Here, we refined protocols for differentiating human embryonic stem cells into functional cINs. We defined gene-expression programs underlying cIN development and direct targets of the NKX2-1 transcription factor in this process, identifying potential regulators. These included
CHD2
, a gene mutated to cause human epilepsies. Accordingly, CHD2 deficiency impaired cIN development and altered later cIN function, while CHD2 and NKX2-1 could coregulate cIN gene expression by cobinding shared genomic regulatory regions. This work defines key features of both normal and disrupted cIN development.
Autocatalytic surface reduction and its role in controlling seed-mediated growth of colloidal metal nanocrystals
Authors: Yang Tung-Han , Zhou Shan , Gilroy Kyle D. , Figueroa-Cosme Legna , Lee Yi-Hsien , Wu Jenn-Ming , Xia Younan
Published: December 2017

Significance

Controlling the shape of colloidal metal nanocrystals is central to the realization of their diverse applications in catalysis, photonics, electronics, and medicine. Here, we demonstrate that autocatalytic surface reduction can be employed to enable the formation of metal nanocrystals with well-controlled and predictable shapes through seed-mediated growth. Our quantitative analysis suggests that the kinetics of autocatalytic surface reduction is highly sensitive to the atomic structures on the surface of the seed, leading to different growth rates for different sites on the seed and eventually resulting in the evolution of nanocrystals into different shapes. The mechanistic insights into autocatalytic surface reduction obtained in this work can be extended to other systems involving nanocrystals with different compositions, facets, and structures.
Comparative transcriptomics as a guide to natural product discovery and biosynthetic gene cluster functionality
Authors: Amos Gregory C. A. , Awakawa Takayoshi , Tuttle Robert N. , Letzel Anne-Catrin , Kim Min Cheol , Kudo Yuta , Fenical William , S. Moore Bradley , Jensen Paul R.
Published: December 2017

Significance

Genomics has revealed that even well-studied bacteria maintain many more biosynthetic gene clusters (BGCs) predicted to encode specialized metabolites than expected based on product discovery. These orphan BGCs are often assumed to be transcriptionally silent. Here, we show that a majority of the 46 BGCs observed in four strains of the marine actinomycete
Salinispora
are transcribed at levels that should facilitate product detection. In five cases, similar BGCs were differentially expressed among strains, suggesting that simple presence or absence analyses are not good predictors of metabolic output. Highly expressed BGCs were bioinformatically linked to their products, including a series of salinipostins not previously reported from
Salinispora pacifica
. Subsequent genetic experiments established a formal link between salinipostins and their cognate BGC.
Cytoplasmic Cl
−
couples membrane remodeling to epithelial morphogenesis
Authors: He Mu , Ye Wenlei , Wang Won-Jing , Sison Eirish S. , Jan Yuh Nung , Jan Lily Yeh
Published: December 2017

Significance

Calcium-activated chloride channels (CaCCs) serve important physiological functions, including modulation of signal processing of neurons in the central and peripheral nervous system. In this study, we uncover a previously underappreciated role for TMEM16A, an evolutionarily conserved CaCC, in regulating cytoplasmic chloride homeostasis and membrane remodeling events in nonexcitable epithelial tissues. TMEM16A-mediated intracellular chloride homeostasis can modulate the partitioning of membrane phosphoinositides and endocytic transport, providing a new mechanism that controls membrane dynamics, a key property of eukaryotic cell membranes important for numerous cellular processes in development and diseases.
Human genetic variation alters CRISPR-Cas9 on- and off-targeting specificity at therapeutically implicated loci
Authors: Lessard Samuel , Francioli Laurent , Alfoldi Jessica , Tardif Jean-Claude , Ellinor Patrick T. , MacArthur Daniel G. , Lettre Guillaume , Orkin Stuart H. , Canver Matthew C.
Published: December 2017

Significance

CRISPR-Cas9 holds enormous potential for therapeutic genome editing. Effective therapy requires treatment to be efficient and safe with minimal toxicity. The sequence-based targeting for CRISPR systems necessitates consideration of the unique genomes for each patient targeted for therapy. We show using 7,444 whole-genome sequences that SNPs and indels can reduce on-target CRISPR activity and increase off-target potential when targeting therapeutically implicated loci; however, these occurrences are relatively rare. We further identify that differential allele frequencies among populations may result in population-specific alterations in CRISPR targeting specificity. Our findings suggest that human genetic variation should be considered in the design and evaluation of CRISPR-based therapy to minimize risk of treatment failure and/or adverse outcomes.
Predicting glycosaminoglycan surface protein interactions and implications for studying axonal growth
Authors: Griffith Adam R. , Rogers Claude J. , Miller Gregory M. , Abrol Ravinder , Hsieh-Wilson Linda C. , Goddard William A.
Published: December 2017

Significance

Glycans and proteins are important partners in the regulation of fundamental biological processes such as the immune response, migration, differentiation, morphogenesis, angiogenesis, axon guidance, and response to CNS injury. Understanding glycan–protein interactions is critical to mapping the biological functions of glycans and developing new therapies for diseases such as cancer, autoimmune disorders, and neurodegenerative disorders. It is difficult to extract information about molecular-level interactions from experiments, and theory/computation has not been able to provide definite information to aid the interpretation of experiments. Our glycosaminoglycan (GAG)-Dock methodology addresses this challenge, furthering understanding of GAG–protein interactions by predicting the binding structures and how they depend on glycan structure and predicting precise effects of mutations that can be used to validate and interpret the interactions.
Daple coordinates organ-wide and cell-intrinsic polarity to pattern inner-ear hair bundles
Authors: Siletti Kimberly , Tarchini Basile , Hudspeth A. J.
Published: December 2017

Significance

Each hair cell of our auditory and vestibular systems transduces stimuli into electrical signals through its mechanosensitive hair bundle. Because the bundle is responsive along only a single axis, its orientation is crucial. Two systems determine hair-bundle polarity: planar cell polarity proteins, which establish axes along which hair cells are oriented, and the proteins Gαi and LGN. Investigating how these two systems are coordinated so that each hair bundle is appropriately aligned, we identified Daple. In mutants lacking Daple, hair bundles are misoriented and misshapen, a phenotype suggestive of both organ-wide and cell-intrinsic defects. Our study indicates how Daple interacts with proteins of the two systems and proposes a model for its role in determining hair-bundle polarity.
Clinical, genetic, and structural basis of apparent mineralocorticoid excess due to 11β-hydroxysteroid dehydrogenase type 2 deficiency
Authors: Yau Mabel , Haider Shozeb , Khattab Ahmed , Ling Chen , Mathew Mehr , Zaidi Samir , Bloch Madison , Patel Monica , Ewert Sinead , Abdullah Wafa , Toygar Aysenur , Mudryi Vitalii , Al Badi Maryam , Alzubdi Mouch , Wilson Robert C. , Al Azkawi Hanan Said , Ozdemir Hatice Nur , Abu-Amer Wahid , Hertecant Jozef , Razzaghy-Azar Maryam , Funder John W. , Al Senani Aisha , Sun Li , Kim Se-Min , Yuen Tony , Zaidi Mone , New Maria I.
Published: December 2017

Significance

Apparent mineralocorticoid excess, a rare autosomal recessive disorder characterized by low renin hypertension, may display a severe or mild phenotype in patients. The variability in clinical presentation stems from different extents of impairment of the 11β-hydroxysteroid dehydrogenase type 2 (HSD11B2) enzyme arising from distinct mutations in the encoding gene. The computational model of the HSD11B2 protein that we constructed here will be useful in predicting disease severity for newly reported missense mutations in this gene.
Kinetics of drug–ribosome interactions defines the cidality of macrolide antibiotics
Authors: Svetlov Maxim S. , Vázquez-Laslop Nora , Mankin Alexander S.
Published: December 2017

Significance

Ribosome-targeting macrolide antibiotics can be bacteriostatic or bactericidal. What distinguishes the action of bactericidal macrolides from that of bacteriostatic compounds is unclear. We found that neither the residual translation in the macrolide-treated cells nor the affinity of the inhibitors explain the static/cidal distinction. Instead, bactericidal compounds show a markedly decreased rate of dissociation from the ribosome because of the presence of an extended side chain in their structure. The prolonged translation downtime caused by the slow rate of antibiotic clearance could bring the cell to a point of no return due to depletion of the factors critical for resumption of gene expression. Optimizing the kinetics of binding/dissociation rather than only the affinity could facilitate the development of bactericidal inhibitors of translation.
Rapid, direct activity assays for Smoothened reveal Hedgehog pathway regulation by membrane cholesterol and extracellular sodium
Authors: Myers Benjamin R. , Neahring Lila , Zhang Yunxiao , Roberts Kelsey J. , Beachy Philip A.
Published: December 2017

Significance

The Hedgehog pathway is critical in development and disease, but how cells respond to the secreted Hedgehog signal remains mysterious. A key step involves the regulation of the seven-transmembrane oncoprotein Smoothened by the 12-pass transporter-like Hedgehog receptor Patched1. We investigate the model that Patched1 is an ion-driven transporter of an endogenous lipidic Smoothened ligand. Whereas Patched–Smoothened regulation has traditionally been studied through indirect, downstream pathway readouts, we developed rapid, direct functional assays to dissect this step in simplified cell-based and in vitro systems. Cholesterol, a major membrane lipid, constitutively activates purified Smoothened by engaging its membrane-spanning region. Patched1 activity depends on extracellular Na
+
, suggesting that transmembrane Na
+
gradients, universal among metazoans, might power Patched1 transporter-like activity in Smoothened regulation.
Three tRNAs on the ribosome slow translation elongation
Authors: Choi Junhong , Puglisi Joseph D.
Published: December 2017

Significance

The rate of protein synthesis along a messenger RNA is not uniform and can influence the folding of the nascent protein. Using multichannel single-molecule fluorescence microscopy, we simultaneously monitored compositions and conformations of prokaryotic translational complex over translating multiple codons. We show that the dissociation of deacylated tRNA is necessary for conformational changes prior to translocating to the next codon. The deacylated tRNA dissociation kinetics strongly depended on the identity of tRNA, the ionic strength of the solution, and the reaction temperature. These findings suggest that in addition to the tRNA association kinetics, tRNA dissociation kinetics can also alter the dynamics of protein synthesis and may be used as a sensor for different cellular conditions to regulate cotranslational processes.
Mechanisms of carnosine-induced activation of neuronal cells
Authors: Yamashita Shuntaro , Sato Mikako , Matsumoto Takashi , Kadooka Keishi , Hasegawa Takanori , Fujimura Tatsuya , Katakura Yoshinori
Published: December 2017

Carnosine (β-Ala-l-His), an imidazole dipeptide, is known to have many functions. Recently, we demonstrated in a double-blind randomized controlled trial that carnosine is capable of preserving cognitive function in elderly people. In the current study, we assessed the ability of carnosine to activate the brain, and we tried to clarify the molecular mechanisms behind this activation. Our results demonstrate that carnosine permeates the blood brain barrier and activates glial cells within the brain, causing them to secrete neurotrophins, including BDNF and NGF. These results point to a novel mechanism of carnosine-induced neuronal activation. Our results suggest that carnosine should be recognized as a functional food factor that helps achieve anti-brain aging.
American think tank networks and expert debates around the Global Financial Crisis: Keynesian insurgents against austerity defenders
Authors: Salas-Porras Alejandra
Published: December 2017

This article applies social network analysis and a Bourdieu-inspired understanding of think tanks to a particular historical period, the aftermath of the Global Financial Crisis of 2007–2009, when the neoliberal policy consensus was fractured and struggles to replace it by Keynesian policies ensued. The analysis finds that think tank and expert networks have played a key role in mobilising policy ideas, contesting or defending policy discourses. Experts advanced their proposals for policy changes in all those fields of power where they have gained a foothold. However, no consensus has been reached on monetary and fiscal policies, and the policy communities remain divided in these domains.