bluuebunny/crossref_metadata_2025 huggingface dataset:
Recent advances in the Heusler based spin-gapless semiconductors
Authors: Wang Xiaotian , Cheng Zhenxiang , Wang Jianli , Wang Xiao-Lin , Liu Guodong
Published: June 2016

In this work, we review the progress on the Heusler-based materials with spin-gapless semiconducting behaviour, including half-Heusler compounds, full-Heusler compounds, DO3-type compounds, and LiMgPdSn-type quaternary Heusler compounds.
Clinical Decision Making for the Internationally Adopted Child With Cleft Lip and Palate
Authors: Morgan Amy , O'Gara Mary , Albert Meredith , Kapp-Simon Kathleen
Published: June 2016

Many children with orofacial clefts are adopted each year into English-speaking families in the United States. These children present unique challenges for achieving best practice in treatment delivery due to a variety of issues. Often, children experience delays in management of their cleft and have a high risk for impaired speech development as a result. Practitioners need to allow time for the child to learn high pressure consonants of English after palatal repair, without overlooking a persistent structural deficit that could be responsible for impairment of that learning. Additionally, children are immersed in a novel language while often completely removed from their native language, creating difficulty with knowing when and how to best identify true language disorder compared to second language learning issues. The purpose of this paper is to summarize the relevant literature pertaining to these issues and offer concrete guidelines for speech-language pathologists who encounter children with orofacial clefts who are internationally adopted.
Current‐mode multi‐scroll chaos generator employing CCCII
Authors: Lin Yuan , Wang Chunhua
Published: June 2016

Current‐mode multi‐scroll chaos generator is introduced. It uses second generation current controlled current conveyor (CCCII) and produces current output chaotic signals. PSPICE simulations show that current‐mode multi‐scroll chaos generator can generate more scroll chaotic attractors with high frequency and low voltage.
Microwave head imaging system using analogue fibre‐optic link for improved detection and localisation
Authors: Mohammed B.J. , Bertling K. , Abbosh A.M. , Rakić A.D.
Published: June 2016

The use of microwave photonics in the form of an optical link to transmit and receive microwave signals in microwave biomedical imaging systems is proposed. A single fibre is used to replace coaxial cables connecting the antenna array to the transceiver. The optical link, which is lightweight and offers an almost zero insertion loss, improves the signal‐to‐noise ratio and sensitivity, and thus offers better detection and localisation. As a proof of concept, an optical link that consists of a vertical‐cavity surface‐emitting laser, a multimode fibre and a high speed photo detector was built and tested. Experiments were performed using a 1–4 GHz microwave imaging system to scan a head phantom, which consists of accurately emulated brain tissues and embedded stroke. The head was imaged and the results were compared with those obtained using the traditional all‐microwave link. The results demonstrate that the optical link increases the signal‐to‐noise ratio of the system and thus improves the quality of the obtained images and accuracy of the detection and localisation.
Model to estimate the trapping parameters of cross‐linked polyethylene cable peelings of different service years and their relationships with dc breakdown strengths
Authors: Liu Ning , Zhou Churui , Chen George , Xu Yang , Cao Junzheng , Wang Haitian
Published: June 2016

In this study, an improved trapping/detrapping model was used to simulate the charge dynamics in cross‐linked polyethylene peelings from different‐year aged cables. Injection barrier of trapping parameters was estimated by the model fitted to experimental data for each type of sample. Moreover, dc breakdown tests were operated on those samples. It has been found that the dc breakdown strength of inner‐layer samples is the lowest in cable sections with thicker insulation layer taken from high‐voltage ac (HVAC) 220 kV service condition, whereas for the cable with thinner insulation from HVAC 110 kV, middle‐layer samples have worst breakdown performance. This might be explained by the space charge issues under long‐term HVAC condition. More importantly, a clear relationship between estimated model parameters, including injection barrier, trap depth and trap density, with the dc breakdown strength in each layer has been reported in this study.
Formation mechanism of streamer discharges in liquids: a review
Authors: Sun Anbang , Huo Chao , Zhuang Jie
Published: June 2016

Streamer discharges in liquids have received lots of attention with respect to their considerable applications in various disciplines. Much effort has been spent to understand the basis of streamer ignition and propagation in dielectric liquids, but a comprehensive mechanism is far from conclusive. In this review, based on an introduction to the streamer physics and experimentally observed characteristics in various liquids, the authors emphasise on the current status of streamer discharge ignition mechanisms and present their understanding for each theory.
Cooperative output regulation of discrete‐time linear time‐delay multi‐agent systems
Authors: Yan Yamin , Huang Jie
Published: June 2016

In this paper, we study the cooperative output regulation problem for the discrete linear time‐delay multi‐agent systems by distributed observer approach. In contrast with the same problem for continuous‐time linear time‐delay multi‐agent systems, the problem has two new features. First, in the presence of time‐delay, the regulator equations for discrete‐time linear systems are different from those for continuous‐time linear systems. Second, under the standard assumption on the connectivity of the communication graph, a distributed observer for any continuous‐time linear leader system always exists. However, this is not the case for the discrete counterpart of the distributed observer for the continuous‐time systems. Another type of discrete distributed observer is proposed. It turns out that such an observer always exists under some mild assumptions. Using this result, the authors further present the solvability conditions of the problem by distributed dynamic output feedback control law.
Spatially decoupled varactor biasing for a tunable staircase filter
Authors: Botes Elmine , Meyer Petrie
Published: June 2016

A spatially decoupled biasing circuit is proposed for the biasing of varactor diodes in a tunable staircase X‐band suspended substrate filter. The biasing lines are vertically aligned with lines of zero electric field which are created by the symmetric capacitive loading of half‐wave planar resonators. A prototype filter is designed and a tunable centre frequency of between 11.75 and 12.15 GHz is measured.
Design and fabrication of field‐emission tips with self‐aligned gates
Authors: Reddy Bobby , Codner Eric , Hainley Ryan E. , Tang William C.
Published: June 2016

A novel approach to the design and fabrication of field‐emission tips with self‐aligned gates intended for electric propulsion micro‐thruster applications is presented. Their micro‐electromechanical systems fabrication process is derived from the recent proliferation of research toward developing field emitter arrays, which are used primarily for field‐emission flat‐panel display applications. An array of micron‐sized tips for electric field enhancement via wet isotropic etching of silicon, using silicon nitride as a hard mask is fabricated. The wet etching is accomplished using a combination of hydrofluoric, nitric, and acetic acids. The tips were then coated with a metal layer to enhance wetting by indium, the proposed propellant. Next, a layer of SU‐8 photoresist was applied by spin coating and patterned to serve as a dielectric spacer. A second layer of metal was then applied to serve as a gate electrode. In addition, the results of electrostatic simulations of the prototype is described.
How direct electrospinning in methanol bath affects the physico‐chemical and biological properties of silk fibroin nanofibrous scaffolds
Authors: Hadisi Zhina , Nourmohammadi Jhamak , Haghighipour Nooshin , Heidari Shafagh
Published: June 2016

Developing a rapid and easy approach to fabricate crystalline silk fibroin nanofibres without any needs for post‐processing stage is focused. Thus, methanol bath was chosen as the collector and then the effect of soaking time on the properties of fibroin fibres was investigated. The results indicated that the wet‐electrospun mats had higher fibre diameter than mats made by conventional electrospinning system. With prolonging the electrospinning time in methanol bath, a slight increase in the average fibre diameter and crystallinity were observed. In addition, the stiffness of the wet‐electrospun mats increased with increasing soaking time, while the breaking stress decreased. The cellular viability of the osteoblast‐like cells (MG63) on fibroin mats improved during wet‐electrospinning process, while no significant difference was observed for cell attachment. Accordingly, it seems that wet electrospinning in methanol for 30 min is optimal for bone regeneration on account of viability and mechanical property.
Kardiovaskuläre Prävention – Akzeptanz einer erweiterten betrieblichen Vorsorge
Authors: Bleckwenn M. , Theisel N. , Mücke M. , Steudel H.
Published: June 2016

Hintergrund: Bisher laufen die Präventionsbemühungen von Betriebsärzten und Hausärzten weitgehend getrennt voneinander. In dem Modell des übergreifenden betrieblichen Gesundheitsmanagements soll der Betriebsarzt das Risiko für Herz- Kreislauferkrankung bei seinen Mitarbeiter feststellen. Bei einem erhöhten Risiko sollte dann ein Informationsaustausch zwischen beiden Fachgruppen zur Abstimmung gemeinsamer Präventionsmaßnahmen stattfinden.

Ziel der Arbeit: Eine Pilotstudie sollte überprüfen, wie gut eine kardiovaskuläre Risikoeinstufung von den Mitarbeitern eines mittelständischen Unternehmens angenommen wird und welcher Präventionsbedarf besteht.

Material und Methoden: In einem Unternehmen mit 660 Beschäftigten wurde im Rahmen der regulären betrieblichen Vorsorge eine Risikoanalyse bei den Mitarbeitern durchgeführt. Neben den Risikofaktoren wurden die hausärztliche Versorgung, das Einverständnis für einen interdisziplinären Informationsaustausch und die Motivation für gesundheitsfördernde Maßnahmen abgefragt.

Ergebnisse: Es wurden 204 Mitarbeiter (nur 4 weiblich) untersucht. Das Durchschnittsalter der Teilnehmer lag bei 42,9±10,3 Jahren. Bei 27% (n=55) lag ein erhöhtes Gesamtrisiko vor. Die Mitarbeiter mit einem interventionsbedürftigen Risiko waren in einer regelmäßigen hausärztlichen Betreuung und waren überwiegend (70%) mit der Informationsweitergabe an ihren Hausarzt einverstanden. Bei der Befragung zeigte sich ausreichende Motivation (VAS 6,4±2,8) für eine betriebliche Gesundheitsförderung.

Schlussfolgerung: Die Zustimmung für weitergehende gesundheitsfördernde Maßnahmen waren im untersuchten Betrieb gegeben. Aufgrund des demografischen Wandels werden neue Konzepte für eine effektive Prävention benötigt. Die hohe Akzeptanz des vorgestellten Präventionskonzeptes sollte zu einer Umsetzung in die Praxis motivieren. Im nächsten Schritt sollte die Effektivität eines betrieblichen Risikoscreenings in Studien überprüft werden.
Handshake electron transfer from hydrogen Rydberg atoms incident at a series of metallic thin films
Authors: Gibbard J. A. , Softley T. P.
Published: June 2016

Thin metallic films have a 1D quantum well along the surface normal direction, which yields particle-in-a-box style electronic quantum states. However the quantum well is not infinitely deep and the wavefunctions of these states penetrate outside the surface where the electron is bound by its own image-charge attraction. Therefore a series of discrete, vacant states reach out from the thin film into the vacuum increasing the probability of electron transfer from an external atom or molecule to the thin film, especially for the resonant case where the quantum well energy matches that of the atom. We show that “handshake” electron transfer from a highly excited Rydberg atom to these thin-film states is experimentally measurable. Thicker films have a wider 1D box, changing the energetic distribution and image-state contribution to the thin film wavefunctions, resulting in more resonances. Calculations successfully predict the number of resonances and the nature of the thin-film wavefunctions for a given film thickness.
Piezoelectric response enhancement in the proximity of grain boundaries of relaxor-ferroelectric thin films
Authors: Brewer Steven , Deng Carmen , Callaway Connor , Kalinin Sergei V. , Vasudevan Rama K. , Bassiri-Gharb Nazanin
Published: June 2016

The influence of surface morphology on the local piezoelectric response of highly (100)-textured 0.70PbMg2/3Nb1/3O3-0.30PbTiO3 thin films is studied using piezoresponse force microscopy in band-excitation mode. The local electromechanical response is mostly suppressed in direct proximity of the grain boundaries. However, within 100–200 nm of the grain boundary, the piezoresponse is substantially enhanced, before decaying again within a region at the center of the grain itself. Nested piezoresponse hysteresis curves confirm the influence of topography descriptors on parameters affecting the hysteresis loop shape. The enhancement of the electromechanical response is rationalized through reduced lateral clamping in the grains with deep trenched boundaries, as well as an expected lower energy for complex domain wall structures, due to curved ferroelectric surfaces. The lower piezoresponse at the center of the grain is assigned to the lateral clamping by the surrounding piezoelectric material.
Spanwise bifurcations beneath the bluff-body instability modes
Authors: Sau Amalendu , Peng Y. F. , Hwang R. R.
Published: June 2016

A new family of bifurcations is detected in a cylinder wake. The simulations reveal the presence of physically significant spanwise wavy flow undulation in the near-wake of a square cylinder which plays an important role in the modal transition. The alternate process of vortex shedding initiates a systematic cross-stream momentum transfer that activates self-sustained spanwise oscillation of the physical wake, leading to the growth of sequence of Hopf bifurcations along the topological cores of von Kármán vortices. The study exhibits how exactly such self-excited spanwise oscillatory fluctuations of pressure, velocity, and KE keep growing along a vortex-core for increased Re and distinctly influence the growth of “Mode A” and “Mode B” instability. It reports existence of two distinct stages of wake undulation over 125 ≤ Re ≤ 240. While the weakly subcritical spanwise-periodic oscillations of pressure, velocity, vorticity, and associated uniform and wider length-scale bifurcations along the von Kármán vortex corelines dominate during “Mode A” instability, the transition to the “Mode B” is prompted following faster and random eruption (and swapping) of significantly smaller but variable length-scaled bifurcations and accompanied low frequency non-uniform fluctuation of flow variables. Such unstable flow perturbations and resulting bifurcations along the von Kármán vortex cores apparently influence generation of longitudinal vortical ribs (Mode A and Mode B) in the wake. The appearance of a slow varying secondary frequency at the bifurcation points seemed crucial for initiating the spanwise flow irregularity and transition to “Mode B.”
On the stability of the production of bubbles in yield-stress fluid using flow-focusing and T-junction devices
Authors: Laborie B. , Rouyer F. , Angelescu D. E. , Lorenceau E.
Published: June 2016

We investigate experimentally the stability of bubble production in yield-stress fluids (YSF) and highly viscous silicone oil, using flow-focusing and T-junction devices. When the exit channel is initially pre-filled with the fluid and the gas is pressure-driven, the production is highly unstable, despite a regular frequency of bubble production in the junction. As observed for pressure-driven bubble trains in Newtonian fluids, we report that two mechanisms can explain these observations: (i) drastic reduction of the hydrodynamic pressure drop along the channel during the transient bubble production, which induces a rapid increase of the gas flow rate and (ii) thin film deposition resulting in a cascade of plug break-up and bubble coalescence. While the drastic reduction of the pressure drop is inevitable in such two-phase flows, we show that modifying the surfaces of the channel can help to stabilize the system when the continuous phase is a YSF. To do so, we measure the thickness of the film deposited on the channel wall for rough and smooth channels. Our results are rationalized by introducing the inverse of the Bingham number Bi−1 comparing the viscous stress to the yield stress. For Bi−1 ≥ 1, a fast fluidization process associated to efficient deposition of YSF on the channel wall leads to a rapid destabilization of bubble production. However, for Bi−1 < 1, the deposition driven by capillarity can be hindered by the wall-slip induced by the existence of the yield stress: the thickness of the deposited film is very thin and corresponds to the equivalent roughness of the channels. It is typically 40 μm thick for rough surfaces and below the limit of resolution of our set-up for smooth surfaces. In this regime of Bi−1 and for smooth surfaces, the length of the plugs barely vanishes, thus the start-up flow is less prone to destabilization. These results therefore potentially open routes to steady production of aerated YSF on smooth channels in the regime of small Bi−1.
Optical studies of the uniaxial stress-induced orbital alignment of the Cr2+ centers in KZnF3 single crystal
Authors: Nikitin S. I. , Gracheva I. N. , Zverev D. G. , Yusupov R. V.
Published: June 2016

Observation of an intense optical linear dichroism arising in cubic KZnF3:Cr crystal at low temperatures under uniaxial stress applied along the four-fold axis is reported. Dichroism occurs in the range of the wide vibronic absorption band corresponding to 5Eg → 5T2g transition of the Cr2+ ions. Strain dependences of the dichroism value were studied at the temperatures of 2.0 K, 4.2 K, and 77 K. We associate our observations with the Jahn-Teller effect in the 5Eg ground state of the Cr2+ ion. The model is proposed based on a redistribution of the centers between the minima of the E⨂e problem adiabatic potential that become inequivalent under uniaxial stress applied along the four-fold axis of the crystal. It is shown that random strains in the sample have to be taken into account to achieve the quantitative agreement of the model predictions with experimental data. It is found that random strains in the studied sample originate predominantly from point defects. Obtained parameter values are inversion splitting δ = 9.2 ± 1.6 cm−1, electron-strain coupling constant qVES = 16 500 ± 600 cm−1, width of the random strain distribution w = (6.9 ± 0.5) ⋅ 10−5. It is shown also that the minima of the [CrF6]4− cluster adiabatic potential correspond to the elongated along the four-fold axes configurations.
2-D soft x-ray arrays in the EAST
Authors: Chen Kaiyun , Xu Liqing , Hu Liqun , Duan Yanmin , Li Xueqin , Yuan Yi , Mao Songtao , Sheng Xiuli , Zhao Jinlong
Published: June 2016

A high spatial and temporal resolution soft x-ray (SXR) imaging diagnostic has been installed in EAST for the study of magnetohydrodynamics activities and core high-Z impurity transport. Up to 122 lines of sight view the poloidal plasma from three directions (two up-down symmetrical horizontal arrays and one vertical array), which renders the diagnostic able to provide detailed tomographic reconstructions under various conditions. Fourier-Bessel method based on flux coordinates was employed for 2-D SXR tomographic reconstruction. Examples of several events measured by SXR diagnostic in EAST are shown, namely the crash patterns of sawtooth, periodical burst of edge localized modes, and the transport of high-Z intrinsic impurities.
Stochastic lag time in nucleated linear self-assembly
Authors: Tiwari Nitin S. , van der Schoot Paul
Published: June 2016

Protein aggregation is of great importance in biology, e.g., in amyloid fibrillation. The aggregation processes that occur at the cellular scale must be highly stochastic in nature because of the statistical number fluctuations that arise on account of the small system size at the cellular scale. We study the nucleated reversible self-assembly of monomeric building blocks into polymer-like aggregates using the method of kinetic Monte Carlo. Kinetic Monte Carlo, being inherently stochastic, allows us to study the impact of fluctuations on the polymerization reactions. One of the most important characteristic features in this kind of problem is the existence of a lag phase before self-assembly takes off, which is what we focus attention on. We study the associated lag time as a function of system size and kinetic pathway. We find that the leading order stochastic contribution to the lag time before polymerization commences is inversely proportional to the system volume for large-enough system size for all nine reaction pathways tested. Finite-size corrections to this do depend on the kinetic pathway.
Stepwise crystallization and the layered distribution in crystallization kinetics of ultra-thin poly(ethylene terephthalate) film
Authors: Zuo Biao , Xu Jianquan , Sun Shuzheng , Liu Yue , Yang Juping , Zhang Li , Wang Xinping
Published: June 2016

Crystallization is an important property of polymeric materials. In conventional viewpoint, the transformation of disordered chains into crystals is usually a spatially homogeneous process (i.e., it occurs simultaneously throughout the sample), that is, the crystallization rate at each local position within the sample is almost the same. Here, we show that crystallization of ultra-thin poly(ethylene terephthalate) (PET) films can occur in the heterogeneous way, exhibiting a stepwise crystallization process. We found that the layered distribution of glass transition dynamics of thin film modifies the corresponding crystallization behavior, giving rise to the layered distribution of the crystallization kinetics of PET films, with an 11-nm-thick surface layer having faster crystallization rate and the underlying layer showing bulk-like behavior. The layered distribution in crystallization kinetics results in a particular stepwise crystallization behavior during heating the sample, with the two cold-crystallization temperatures separated by up to 20 K. Meanwhile, interfacial interaction is crucial for the occurrence of the heterogeneous crystallization, as the thin film crystallizes simultaneously if the interfacial interaction is relatively strong. We anticipate that this mechanism of stepwise crystallization of thin polymeric films will allow new insight into the chain organization in confined environments and permit independent manipulation of localized properties of nanomaterials.
Relationship between the line of density anomaly and the lines of melting, crystallization, cavitation, and liquid spinodal in coarse-grained water models
Authors: Lu Jibao , Chakravarty Charusita , Molinero Valeria
Published: June 2016

Liquid water has several anomalous properties, including a non-monotonous dependence of density with temperature and an increase of thermodynamic response functions upon supercooling. Four thermodynamic scenarios have been proposed to explain the anomalies of water, but it is not yet possible to decide between them from experiments because of the crystallization and cavitation of metastable liquid water. Molecular simulations provide a versatile tool to study the anomalies and phase behavior of water, assess their agreement with the phenomenology of water under conditions accessible to experiments, and provide insight into the behavior of water in regions that are challenging to probe in the laboratory. Here we investigate the behavior of the computationally efficient monatomic water models mW and mTIP4P/2005REM, with the aim of unraveling the relationships between the lines of density extrema in the p-T plane, and the lines of melting, liquid-vapor spinodal and non-equilibrium crystallization and cavitation. We focus particularly on the conditions for which the line of density maxima (LDM) in the liquid emerges and disappears as the pressure is increased. We find that these models present a retracing LDM, same as previously found for atomistic water models and models of other tetrahedral liquids. The low-pressure end of the LDM occurs near the pressure of maximum of the melting line, a feature that seems to be general to models that produce tetrahedrally coordinated crystals. We find that the mW water model qualitatively reproduces several key properties of real water: (i) the LDM is terminated by cavitation at low pressures and by crystallization of ice Ih at high pressures, (ii) the LDM meets the crystallization line close to the crossover in crystallization from ice Ih to a non-tetrahedral four-coordinated crystal, and (iii) the density of the liquid at the crossover in crystallization from ice Ih to a four-coordinated non-tetrahedral crystal coincides with the locus of maximum in diffusivity as a function of pressure. The similarities in equilibrium and non-equilibrium phase behavior between the mW model and real water provide support to the quest to find a compressibility extremum, and determine whether it presents a maximum, in the doubly metastable region.
Changes in the temperature-dependent specific volume of supported polystyrene films with film thickness
Authors: Huang Xinru , Roth Connie B.
Published: June 2016

Recent studies have measured or predicted thickness-dependent shifts in density or specific volume of polymer films as a possible means of understanding changes in the glass transition temperature Tg(h) with decreasing film thickness with some experimental works claiming unrealistically large (25%-30%) increases in film density with decreasing thickness. Here we use ellipsometry to measure the temperature-dependent index of refraction of polystyrene (PS) films supported on silicon and investigate the validity of the commonly used Lorentz-Lorenz equation for inferring changes in density or specific volume from very thin films. We find that the density (specific volume) of these supported PS films does not vary by more than ±0.4% of the bulk value for film thicknesses above 30 nm, and that the small variations we do observe are uncorrelated with any free volume explanation for the Tg(h) decrease exhibited by these films. We conclude that the derivation of the Lorentz-Lorenz equation becomes invalid for very thin films as the film thickness approaches ∼20 nm, and that reports of large density changes greater than ±1% of bulk for films thinner than this likely suffer from breakdown in the validity of this equation or in the difficulties associated with accurately measuring the index of refraction of such thin films. For larger film thicknesses, we do observed small variations in the effective specific volume of the films of 0.4 ± 0.2%, outside of our experimental error. These shifts occur simultaneously in both the liquid and glassy regimes uniformly together starting at film thicknesses less than ∼120 nm but appear to be uncorrelated with Tg(h) decreases; possible causes for these variations are discussed.
A repetitive long-pulse power generator based on pulse forming network and linear transformer driver
Authors: Li Mingjia , Kang Qiang , Tan Jie , Zhang Faqiang , Luo Min , Xiang Fei
Published: June 2016

A compact module for long-pulse power generator, based on Blumlein pulse forming network (PFN), was designed. Two Blumlein PFNs with L-type configuration and 20 Ω characteristic impedance were connected symmetrically to the primary coil of the linear transformer driver (LTD) and driven by an identical high voltage spark switch to ensure two Blumlein PFNs synchronizing operation. The output pulse of the module connected with 10 Ω water load is about 135 kV in amplitude and 200 ns in duration with a rise time of ∼50 ns and a flat top of ∼100 ns. On this basis, a repetitive long-pulse power generator based on PFN-LTD has been developed, which was composed of four modules. The following technical parameters of the generator were achieved on planar diode: output voltage amplitude of ∼560 kV, output current amplitude of ∼10 kA at a repetition rate of 25 Hz. The generator operates stable and outputs more than 104 pulses. Meanwhile, the continuous operating time of the generator is up to 60 s.
A diffuse interface model of grain boundary faceting
Authors: Abdeljawad F. , Medlin D. L. , Zimmerman J. A. , Hattar K. , Foiles S. M.
Published: June 2016

Interfaces, free or internal, greatly influence the physical properties and stability of materials microstructures. Of particular interest are the processes that occur due to anisotropic interfacial properties. In the case of grain boundaries (GBs) in metals, several experimental observations revealed that an initially flat GB may facet into hill-and-valley structures with well defined planes and corners/edges connecting them. Herein, we present a diffuse interface model that is capable of accounting for strongly anisotropic GB properties and capturing the formation of hill-and-valley morphologies. The hallmark of our approach is the ability to independently examine the various factors affecting GB faceting and subsequent facet coarsening. More specifically, our formulation incorporates higher order expansions to account for the excess energy due to facet junctions and their non-local interactions. As a demonstration of the modeling capability, we consider the Σ5 〈001〉 tilt GB in body-centered-cubic iron, where faceting along the {210} and {310} planes was experimentally observed. Atomistic calculations were utilized to determine the inclination-dependent GB energy, which was then used as an input in our model. Linear stability analysis and simulation results highlight the role of junction energy and associated non-local interactions on the resulting facet length scales. Broadly speaking, our modeling approach provides a general framework to examine the microstructural stability of polycrystalline systems with highly anisotropic GBs.
Catastrophic instabilities of modified DA-DC hybrid surface waves in a semi-bounded plasma system
Authors: Lee Myoung-Jae , Jung Young-Dae
Published: June 2016

We find the catastrophic instabilities and derive the growth rates for the dust-cyclotron resonance (DCR) and dust-rotation resonance (DRR) modes of the modified dust-acoustic and dust-cyclotron (DA-DC) hybrid surface waves propagating at the plasma–vacuum interface where the plasma is semi-bounded and composed of electrons and rotating dust grains. The effects of magnetic field and dust rotation frequency on the DCR- and DDR-modes are also investigated. We find that the dust rotation frequency enhances the growth rate of DCR-mode and the effect of dust rotation on this resonance mode decreases with an increase of the wave number. We also find that an increase of magnetic field strength enhances the DCR growth rate, especially, for the short wavelength regime. In the case of DRR-mode, the growth rate is found to be decreased less sensitively with an increase of the wave number compared with the case of DCR, but much significantly enhanced by an increase of dust rotation frequency. The DRR growth rate also decreases with an increase of the magnetic field strength, especially in the long wavelength regime. Interestingly, we find that catastrophic instabilities occur for both DCR- and DRR-modes of the modified DA-DC hybrid surface waves when the rotational frequency is close to the dust-cyclotron frequency. Both modes can also be excited catastrophically due to the cooperative interaction between the DCR-mode and the DRR-mode.
Anisotropic high-field terahertz response of free-standing carbon nanotubes
Authors: Lee Byounghwak , Mousavian Ali , Paul Michael J. , Thompson Zachary J. , Stickel Andrew D. , McCuen Dalton R. , Jang Eui Yun , Kim Yong Hyup , Kyoung Jisoo , Kim Dai-Sik , Lee Yun-Shik
Published: June 2016

We demonstrate that unidirectionally aligned, free-standing multi-walled carbon nanotubes (CNTs) exhibit highly anisotropic linear and nonlinear terahertz (THz) responses. For the polarization parallel to the CNT axis, strong THz pulses induce nonlinear absorption in the quasi-one-dimensional conducting media, while no nonlinear effect is observed in the perpendicular polarization configuration. Time-resolved measurements of transmitted THz pulses and a theoretical analysis of the data reveal that intense THz fields enhance permittivity in carbon nanotubes by generating charge carriers.
Cryobiology: principles, species conservation and benefits for coral reefs
Authors: Hagedorn Mary , Carter Virginia L.
Published: June 2016

Coral reefs are some of the oldest, most diverse and valuable ecosystems on Earth because they can support one-quarter of all marine life in our oceans. Despite their importance, the world’s coral reefs continue to be degraded at unprecedented rates by local and global threats that are warming and creating a more acidic ocean. This paper explores the reproductive challenges of coral for ex situ conservation, using IVF and cryopreservation, and our practical biobanking methods. Coral present challenges for cryopreservation because their reproductive period is often limited to a few nights yearly, they are mostly hermaphrodites with diverse modes of reproduction, including asexual reproduction (i.e. fragmentation and parthenogenesis) and sexual reproduction (i.e. self- and cross-fertilisation) and they express physiological toxins that can inhibit cryopreservation. We have banked spermatozoa from 12 coral species using the same field-hardy methods and have created new coral with thawed spermatozoa. In addition, we describe the cryopreservation of coral symbionts, whose physiology only permits the highest success seasonally. As part of a multidisciplinary conservation strategy, these collections may provide a major hedge against extinction for corals facing the damaging effects of climate change and loss of genetic diversity, and promise to help offset threats to our reefs worldwide.
Complex demographic responses of a common small mammal to a plant invasion
Authors: Litt Andrea R. , Steidl Robert J.
Published: June 2016

Context Invasions by non-native plants can alter the abundance and distribution of resources that can affect habitat quality for native animals. Aims We sought to understand the demographic consequences of a plant invasion on a functionally and numerically important rodent in a grassland ecosystem. Specifically, we evaluated how abundance, survival, reproductive activity and population structure of Arizona cotton rats (Sigmodon arizonae) varied across a gradient of invasion by Eragrostis lehmanniana (Lehmann lovegrass), a bunchgrass native to Africa that has invaded grasslands in North America. Methods Over a four-year period, we used capture–recapture methods to survey small mammals on 54 1-ha plots between 10 and 13 times. We used vegetation data collected each autumn to quantify biomass of non-native grass, total biomass and vegetation heterogeneity to characterise vegetation structure on each plot. Key results We captured 1344 individual cotton rats during 106 560 trap-nights across all sampling periods. In areas dominated by non-native grass, abundance of cotton rats increased 7- to 10-fold and survival increased by 117% relative to areas dominated by native grasses. In contrast, reproductive activity of adults decreased by 62% for females and 28% for males, and the proportion of adults in the population decreased by 20% in these same areas. Conclusions Demography of Arizona cotton rats differed markedly in areas invaded by a non-native plant relative to native grasslands, supporting the long-held idea that life histories can reflect local environmental conditions. Because distributions of many non-native plants are predicted to increase in response to future changes in natural and anthropogenic drivers, the potential breadth of these complex effects on communities of native animal is immense. Implications The complex variation in demographic responses across the invasion gradient suggests that it may be necessary to evaluate a suite of vital rates to fully understand the consequences of plant invasions on animals. This is especially important for species of conservation concern because single demographic parameters, which are used frequently as targets to gauge the success of conservation and management activities, could be misleading.
Incubating snowy plovers (Charadrius nivosus) exhibit site-specific patterns of disturbance from human activities
Authors: Faillace Cara A. , Smith Bradley W.
Published: June 2016

Context
Many shorebirds are threatened by human-caused disturbance. For snowy plovers, disturbance within nesting habitats has been implicated as a major contributing factor in their population decline through deleterious effects on breeding success. Very little is known about site specificity of disturbance from human activities for this species.

Aims
We examined the disturbance of incubating snowy plovers to determine if nesting shorebirds within one breeding population exhibited site-specific patterns of disturbance from human activities.

Methods
We recorded flush (i.e. flight or escape from a perceived threat) distances and time spent off the nest following approach by a single person on Sanibel and Cayo Costa Islands, two islands in south-west Florida that differ in daily human visitation, and by a person walking a dog on Sanibel. We used a Bayesian model framework to determine effects of location and approach type on flush distance and time spent off of the nest.

Key results
Birds nesting on Sanibel flushed at shorter distances from a solitary person without a dog than did birds nesting on Cayo Costa, but spent similar amounts of time off of nests following a flush. On Sanibel, nesting birds also flushed at significantly greater distances and spent significantly more time off of nests when flushed by a person walking a dog rather than by a person alone.

Conclusions
Within a population, nesting snowy plovers exhibit site- and stimulus-dependent patterns of disturbance. The intraspecific variation falls within the range of variation recorded among species of birds studied elsewhere. Although we cannot determine causation, we suggest habituation to human activities from a combination of high beach usage, smaller nesting exclusion zones, and narrower beach width on Sanibel compared to Cayo Costa as a likely explanation for this difference.

Implications
Set-back distances for symbolic fencing have been generalised across species and nesting locations. Our results suggest that disturbance of nesting shorebirds can be site-dependent even within one breeding population of a species. Set-back distances around shorebird nests must account for location and types of activities encountered, implying the need for more conservative implementation of set-back distances.
Soil phosphorus predicts feral pig (Sus scrofa) occupancy, detection probability and feeding activity in a temperate montane rainforest
Authors: Forsyth David M. , Allen Robert B. , Allen Roy K. J. , Affeld Kathrin , MacKenzie Darryl I.
Published: June 2016

Context Feral pigs (Sus scrofa) have a wide global distribution that includes large parts of Australia and New Zealand. There is concern about the impacts of feral pigs on above- and below-ground flora and fauna, but little is known about their habitat use and feeding activity in temperate rainforests. Aims We evaluated the importance of abiotic and biotic variables hypothesised to influence seasonal and annual feral pig habitat use and feeding activity in a montane conifer–angiosperm rainforest in Te Urewera, North Island, New Zealand. Methods We used a grid of 25 remote-camera locations to collect feral pig images in a 100-ha area during the winters and summers of 2010 and 2011. Plant composition, solar radiation and soil fertility variables were determined for each camera-image area. Multiseason, multistate occupancy models and information-theoretic methods were used to evaluate how these variables related to feral pig occupancy and feeding. Key results Feral pigs occupied more camera locations in summer than in winter, and detection probabilities increased if piglets were present and with increasing soil phosphorus (P). Piglets were detected only in summer, and their detection probability increased with increasing soil P. The probability of detecting feral pigs feeding also increased with soil P and was higher in 2010 than 2011. Conclusions Feral pigs selected locations with high soil P, probably because those sites had more food than did locations with low soil P. Mast fruiting of tawa (Beilschmiedia tawa) has been hypothesised to increase feral pig recruitment, and the higher detection probability of piglets in summer 2010 followed a heavier tawa fruit fall. Implications Our study highlighted the usefulness of camera traps and occupancy models for understanding seasonal and annual dynamics of cryptic ungulate species in remote, rugged forests, and suggests that the impacts of feral pigs will be greatest in areas of high soil P following widespread tawa masting.
Relative influence of meteorological conditions and aerosols on the lifetime of mesoscale convective systems
Authors: Chakraborty Sudip , Fu Rong , Massie Steven T. , Stephens Graeme
Published: June 2016

Significance

Mesoscale convective systems (MCSs) are the primary source of precipitation over the tropics and midlatitudes, and their lifetime can have a large influence on the variability of rainfall, especially extreme rainfall that causes flooding. The hypothesis that aerosols can increase the lifetime of the MCSs by weakening or delaying precipitation has long been proposed, but we have not known whether that increase is significant on global and regional scales, and, if so, how it compares with the influence of meteorological conditions. We use multiyear collocated geostationary and polar-orbital satellite datasets to provide, to our knowledge, the first observational assessment of such an aerosol effect and its relative importance compared with other meteorological conditions in determining the variability of MCSs’ lifetime.
Elongation factor G initiates translocation through a power stroke
Authors: Chen Chunlai , Cui Xiaonan , Beausang John F. , Zhang Haibo , Farrell Ian , Cooperman Barry S. , Goldman Yale E.
Published: June 2016

Significance

Elongation factor G (EF-G) uses energy stored in GTP to catalyze movement of transfer RNAs and messenger RNA in the ribosome during the translocation step of prokaryotic protein synthesis. Using single-molecule polarized fluorescence microscopy, three-dimensional rotational motions of individual domains of EF-G were directly captured, for the first time to our knowledge, during normal translocation. Our observations strongly imply a hybrid model, in which the initial steps of translocation are ribosome unlocking driven by a force generated via EF-G–dependent GTP hydrolysis, and further steps of translocation are mainly driven by the energetics of the ribosome itself. These results demonstrate that the ribosome and EF-G make use of power-stroke and Brownian-ratchet mechanisms to ensure efficiency and accuracy of translocation.
Dynamic heterogeneity as a strategy of stem cell self-renewal
Authors: Greulich Philip , Simons Benjamin D.
Published: June 2016

Significance

In many tissues, such as intestine and skin, cells are constantly turned over throughout life. To replenish cells that are lost, new cells are generated by stem cells, which divide and differentiate to maintain tissue in a steady state. The mechanisms that allow stem cells to achieve perfect self-renewal promise fundamental insights into processes leading to diseased states. Efforts to define strategies of stem cell self-renewal have placed emphasis on models in which stem cells progress one way through a differentiation hierarchy. Here, we show that a different paradigm, in which stem cells transfer reversibly between states primed for renewal or poised for differentiation, offers a viable and robust mechanism of tissue self-renewal.
Cross-modal object recognition and dynamic weighting of sensory inputs in a fish
Authors: Schumacher Sarah , Burt de Perera Theresa , Thenert Johanna , von der Emde Gerhard
Published: June 2016

Significance

Being able to spontaneously recognize objects across different senses increases the flexibility of a multisensory system, because the reliability of different sensory inputs depends on the environment and range. However, this ability has only been found in mammals, suggesting such a high-level function might be associated with complex mammalian brain structures. We show that the weakly electric fishGnathonemus petersii, is also capable of spontaneous cross-modal object recognition, discriminating objects learned visually with the active electric sense and vice versa. Furthermore, the modality-specific inputs are weighted dynamically according to their reliability at different ranges. This finding suggests that these complex cognitive abilities are present in fish in addition to mammals, and therefore do not require a cerebral cortex.
Metallurgically lithiated SiO
x
anode with high capacity and ambient air compatibility
Authors: Zhao Jie , Lee Hyun-Wook , Sun Jie , Yan Kai , Liu Yayuan , Liu Wei , Lu Zhenda , Lin Dingchang , Zhou Guangmin , Cui Yi
Published: June 2016

Significance

High-capacity prelithiation of the electrodes is an important strategy to compensate for lithium loss in lithium ion batteries. Because of the high chemical reactivity, conventional prelithiation reagent often presents serious safety concerns. Here, we present a new nanocomposite as the lithium source material with homogeneously dispersed active Li
x
Si nanodomains embedded in a robust Li
2
O matrix, which exhibits remarkable air compatibility and cycling performance. Other than the potential impact on battery manufacturing, our study focuses on the material science to stabilize active materials by tuning nanostructures and the degree of the crystallinity. Our result is valuable to researchers working with highly sensitive materials and not limited to the batteries community.
Cell type-specific control of protein synthesis and proliferation by FGF-dependent signaling to the translation repressor 4E-BP
Authors: Ruoff Rachel , Katsara Olga , Kolupaeva Victoria
Published: June 2016

Significance

Translational control is a key component of gene regulation; therefore, it is important to understand alterations to the translational machinery that occur during development. We identified a unique mTOR (the mechanistic target of rapamycin)-independent mechanism of 4E-BP (a repressor of cap-dependent translation) regulation that is utilized by chondrocytes in response to FGF signaling. It is well established that FGF signaling leads to inhibition of chondrocyte proliferation, and is crucial for bone development. We found that FGF specifically suppresses protein synthesis in chondrocytes by activating 4E-BP. Importantly, FGF-induced changes in the translation apparatus observed in cell culture are similarly detected in vivo, and reflect the action of FGF signaling on downstream targets during bone development.