bluuebunny/crossref_metadata_2025 huggingface dataset:
Lattice relaxation studies in strained epitaxial Fe-Co-C films
Authors: Reichel L. , Schultz L. , Fähler S.
Published: February 2015

Aiming at high magnetocrystalline anisotropies, small additions of carbon have been proposed to stabilize a tetragonal lattice distortion in Fe-Co. In the present work, the relaxation mechanisms of Fe-Co films containing 2 at. % C are examined in detail. Film growth on buffers with different lattice constants is compared by a combination of in situ reflection high energy electron diffraction and ex-situ X-ray diffraction measurements. It is shown that relaxation starts at a thickness around 2 nm and ends at a distortion of about 4%, which is independent from the chosen buffer. Integral XRD and magnetization measurements suggest that the relaxation occurs over the complete film thickness.
Asymptotic entanglement transformation between W and GHZ states
Authors: Vrana Péter , Christandl Matthias
Published: February 2015

We investigate entanglement transformations with stochastic local operations and classical communication in an asymptotic setting using the concepts of degeneration and border rank of tensors from algebraic complexity theory. Results well-known in that field imply that GHZ states can be transformed into W states at rate 1 for any number of parties. As a generalization, we find that the asymptotic conversion rate from GHZ states to Dicke states is bounded as the number of subsystems increases and the number of excitations is fixed. By generalizing constructions of Coppersmith and Winograd and by using monotones introduced by Strassen, we also compute the conversion rate from W to GHZ states.
Local hybrid functionals with orbital-free mixing functions and balanced elimination of self-interaction error
Authors: de Silva Piotr , Corminboeuf Clémence
Published: February 2015

The recently introduced density overlap regions indicator (DORI) [P. de Silva and C. Corminboeuf, J. Chem. Theory Comput. 10(9), 3745–3756 (2014)] is a density-dependent scalar field revealing regions of high density overlap between shells, atoms, and molecules. In this work, we exploit its properties to construct local hybrid exchange-correlation functionals aiming at balanced reduction of the self-interaction error. We show that DORI can successfully replace the ratio of the von Weizsäcker and exact positive-definite kinetic energy densities, which is commonly used in mixing functions of local hybrids. Additionally, we introduce several semi-empirical parameters to control the local and global admixture of exact exchange. The most promising of our local hybrids clearly outperforms the underlying semi-local functionals as well as their global hybrids.
Diffused phase transitions in Pb(Zr0.65Ti0.35)O3-Pb(Fe2/3W1/3)O3 multiferroics
Authors: Tirupathi Patri , Kumar Nawnit , Pastor Mukul , Pandey A. C. , Choudhary R. N. P.
Published: February 2015

The solid solutions of (1−x)Pb(Zr0.65Ti0.35)O3-xPb(Fe2/3W1/3)O3 in different ratios were fabricated by a high-temperature solid-state reaction method using high-purity oxides for possible multi-ferroic applications. Structural analysis using x-ray diffraction powder patterns of the system by Rietveld refinement method exhibits the formation of rhombohedral phase with R3c space group. Detailed studies of dielectric permittivity as a function of temperature of the systems show that the frequency independent dielectric maximum temperature shifts toward room temperature on increasing x. In addition to this, the degree of diffuseness of the permittivity anomaly is more pronounced for higher content of Pb(Fe2/3W1/3)O3, implying the existence of a composition-induced diffuse phase transition for the limited range of compositional ratios. Detailed impedance spectroscopy analysis shows the contributions of grain, grain boundary, and interfacial polarizations in the resistive characteristics and conduction mechanism of the materials. The weak ferromagnetic and saturated ferroelectric loops indicate that system with x = 0.1, 0.2 have good multiferroic characteristics, and may be useful for future spintronic devices.
Millimeter-wave magneto-dielectric effects in self-assembled ferrite-ferroelectric core-shell nanoparticles
Authors: Srinivasan G. , Popov M. , Sreenivasulu G. , Petrov V. M. , Chavez F.
Published: February 2015

The magneto-dielectric effect (MDE) involves studies on the influence of an applied magnetic field on the dielectric constant of a material. MDEs in self-assembled core-shell nanoparticles of nickel ferrite and barium titanate have been investigated in the millimeter wave frequencies. The core-shell nanocomposites were synthesized by coating 15 nm nickel ferrite and 100 nm barium titanate nanoparticles with complementary coupling groups and allowing them to self-assemble in the presence of a catalyst forming heterogeneous nanocomposites. Studies on MDE in as-assembled particles have been carried out by measurements of the relative permittivity as a function of frequency f under an applied static magnetic field H over 16–24 GHz. Measurements show an H-induced decrease in permittivity by 0.8% for H = 4 kOe and is much stronger than MDE in single phase multiferroics. A model for the high frequency MDE has been discussed here.
Note: Design and development of improved indirectly heated cathode based strip electron gun
Authors: Maiti Namita , Bade Abhijeet , Tembhare G. U. , Patil D. S. , Dasgupta K.
Published: February 2015

An improved design of indirectly heated solid cathode based electron gun (200 kW, 45 kV, 270° bent strip type electron gun) has been presented. The solid cathode is made of thoriated tungsten, which acts as an improved source of electron at lower temperature. So, high power operation is possible without affecting structural integrity of the electron gun. The design issues are addressed based on the uniformity of temperature on the solid cathode and the single long filament based design. The design approach consists of simulation followed by extensive experimentation. In the design, the effort has been put to tailor the non-uniformity of the heat flux from the filament to the solid cathode to obtain better uniformity of temperature on the solid cathode. Trial beam experiments have been carried out and it is seen that the modified design achieves one to one correspondence of the solid cathode length and the electron beam length.
Analysis of the hydropower generation cost and the affordability of the hydropower on-grid price in Tibet
Authors: Hu Yanlong , Huang Weibin , Chen Shijun , Wang Jinlong , Liu Yue
Published: February 2015

This study systematically investigated electricity production cost in Tibet and analyzed the affordability of the on-grid price for newly built hydropower plants. According to the investigation, the ratio of the power generation cost to the power transmission and distribution cost is 5:5 in Tibet's Central grid, whereas the ratios are 4.5:5.5 and 6:4 in the Changdu and Ali grids, respectively. It was determined that the increased financial expense of newly built independent power plants is the main cause of their higher electricity production cost. Based on the particular conditions prevalent in Tibet, we established a new affordability evaluation model that takes into account the local resident living standard, the potential for cost reduction for industrial production, the capacity for surrendering profits, and the capability of transferring price for each industry. The results indicate that the highest affordable on-grid price of the Central, Changdu, and Ali grids are 0.3274, 0.2398, and 0.9212 RMB/kW h, respectively. These values do not meet the breakeven point for a newly built hydropower plant, which indicates a serious electricity price problem. In this article, alternatives are investigated for mitigating the mismatch between the hydropower generation cost and the local affordability of the on-grid price to protect the investment motivation of independent power enterprises. The alternatives considered are the acceleration of electrical system reform in Tibet, the value added tax rebate for independent hydropower enterprises, and extension of loan payment periods for power generation enterprises.
UV-black rutile TiO2: An antireflective photocatalytic nanostructure
Authors: Sanz Ruy , Romano Lucia , Zimbone Massimo , Buccheri Maria Antonietta , Scuderi Viviana , Impellizzeri Giuliana , Scuderi Mario , Nicotra Giuseppe , Jensen Jens , Privitera Vittorio
Published: February 2015

This work presents an experimental study on the specific quantitative contributions of antireflective and effective surface areas on the photocatalytic and antibacterial properties of rutile TiO2 nanospikes. They are studied when continuously distributed over the whole surface and when integrated into well-defined microstructures. The nanospikes were produced following MeV ion beam irradiation of bulk rutile TiO2 single crystals and subsequent chemical etching. The ion beam irradiation generated embedded isolated crystalline nanoparticles inside an etchable amorphous TiO2 layer, and nanospikes fixed to the not etchable TiO2 bulk substrate. The produced nanospikes are shown to resist towards aggressive chemical environments and act as an efficient UV antireflective surface. The photocatalytic activity experiments were performed under the ISO 10678:2010 protocol. The photonic and quantum efficiency are reported for the studied samples. The combined micro- and nanostructured surface triples the photonic efficiency compared to the initial flat surface. Results also revealed that the antireflective effect, due to the nanostructuring, is the dominating factor compared to the increase of surface area, for the observed photocatalytic response. The obtained results may be taken as a general strategy to design and precisely evaluate photoactive nanostructures.
A metamaterial-inspired sensor for combined inductive-capacitive detection
Authors: Long Jiang , Wang Bingnan
Published: February 2015

In this letter, we introduce a metamaterial-inspired sensor that is capable of performing combined inductive–capacitive sensing, so that both detection and discrimination between metallic and dielectric objects are accomplished. Metals and dielectrics are distinguished based on their different responses to inductive and capacitive sensing. Both sensing modes are integrated into a single sensing unit, which is developed from an Ω-shaped metamaterial structure. Inductive and capacitive sensing are simultaneously realized when the sensor is operated at off-resonant frequencies. The proposed sensor is fabricated and experimented with metallic and dielectric objects. The measurement results demonstrate the proposed sensor's ability of conducting combined sensing with a range of 10 mm. The performance of proposed sensor is competitive among industrial state-of-the-art proximity sensors, yet with added functionality of differentiating metallic and dielectric objects.
Adapted parameterization of incomplete ionization in aluminum-doped silicon and impact on numerical device simulation
Authors: Steinkemper Heiko , Rauer Michael , Altermatt Pietro , Heinz Friedemann D. , Schmiga Christian , Hermle Martin
Published: February 2015

The amount of incomplete ionization of aluminum-doped silicon is measured at room temperature by comparing electrochemical capacitance-voltage measurements with micro Raman spectroscopy. It is shown that commonly used parameterizations significantly underestimate the effect of incomplete ionization in Al doped Si. Based on the experimental data, we propose new parameter values for the parameterization of incomplete ionization given in Altermatt et al., J. Appl. Phys. 100, 113715 (2006). Using these new values, the saturation current density J0,p+ of the Al-alloyed region of a standard silicon solar cell is determined by means of numerical device modeling. It is shown that the parameterization influences J0,p+ significantly. Additionally, the weakening effect of incomplete ionization on band gap narrowing (BGN) should be taken into account in modeling that aims to predict device behavior after changes made to the Al-alloyed region.
Harnessing intrinsic localized modes to identify impurities in nonlinear periodic systems
Authors: Thota M. , Harne R. L. , Wang K. W.
Published: February 2015

Intrinsic localized modes (ILMs) are concentrations of vibrational energy in periodic systems/lattices due to the combined influences of nonlinearity and discreteness. Moreover, ILMs can move within the system and may strongly interact with an impurity, such as a stiffness change, mass variation, etc. Numerous scientific fields have uncovered examples and evidence of ILMs, motivating a multidisciplinary pursuit to rigorously understand the underlying principles. In spite of the diverse technical studies, a characterization of ILM interaction behaviors with multiple impurities in dissipative lattices remains outstanding. The insights on such behaviors may be broadly useful when dynamic measurements are the only accessible features of the periodic system. For instance, one may guide an ILM within the lattice using a deliberately applied and steered impurity and harness the observed interaction behaviors with a second, static (immovable) impurity/defect to identify how the underlying lattice is different at the second, defected site, whether or not one knew the position of the defect a priori. In this spirit, this research studies, analyzes, and characterizes the interaction types amongst an ILM and multiple impurities, and devises a method to identify a static defect impurity using quantitatively and qualitatively distinct interaction phenomena. The method is found to be robust to moderate levels of lattice stiffness heterogeneity and is applicable to monitor various property changes that represent impurities. Finally, experimental studies verify that ILMs interact with multiple impurities in unique ways such that defect features may be effectively identified.
Leaf-like nanotips synthesized on femtosecond laser-irradiated dielectric material
Authors: Kiani Amirkianoosh , Patel Nikunj B. , Tan Bo , Venkatakrishnan Krishnan
Published: February 2015

Nanotips are the key nanostructures for the improvement of field emission, flat panel displays, force microscopy, and biosensor applications. We propose a single-step, rapid synthesis method to generate nanotips using femtosecond laser irradiation at megahertz frequency with a background flow of nitrogen gas at ambient conditions. Two different types of leaf-like nanotips can be grown on the target surface: randomly oriented multiple tips growing from a single large droplet and single tips growing from small droplets. In this report, we explain the mechanism accountable for the formation of such nanotips using known concepts of laser breakdown of dielectric materials, plasma plume generation, plasma interactions with incoming laser pulses and surrounding gas, as well as known thermal properties of target material. Nitrogen gas plays an interesting role for the resultant structural changes on the target surface and thus it is given special attention in our discussion. Our unique fabrication technique has enabled us to produce tips with nanoscale apexes with a stem and length ranging from few hundred nanometers to few micrometers.
Generic incubation law for laser damage and ablation thresholds
Authors: Sun Zhanliang , Lenzner Matthias , Rudolph Wolfgang
Published: February 2015

In multi-pulse laser damage and ablation experiments, the laser-induced damage threshold (LIDT) usually changes with the number of pulses in the train, a phenomenon known as incubation. We introduce a general incubation model based on two physical mechanisms—pulse induced change of (i) absorption and (ii) critical energy that must be deposited to cause ablation. The model is applicable to a broad class of materials and we apply it to fit data for dielectrics and metals. It also explains observed changes of the LIDT as a function of the laser repetition rate. We discuss under which conditions the crater-size method to determine LIDTs can be applied in multi-pulse experiments.
Probing the carrier concentration profiles in phosphorus-implanted germanium using infrared spectroscopic ellipsometry
Authors: D'Costa Vijay Richard , Yeo Yee-Chia
Published: February 2015

Spectroscopic ellipsometry with photon energy in the 0.045–0.65 eV range was used to investigate germanium samples implanted with 30 keV phosphorus ions and annealed at 700 °C. The infrared response of implanted layers is dominated by free carrier absorption which is modeled using a Drude oscillator. The carrier concentration profiles were modeled using an error function, and compared with those obtained by electrochemical capacitance-voltage profiling and secondary ion mass spectrometry. In the flat region of the carrier concentration profile, average carrier concentration and mobility of 1.40 × 1019 cm−3 and 336 cm2V−1s−1, respectively, were obtained. A phosphorus diffusivity of ∼1.2 × 10−13 cm2/s was obtained. The mobility versus carrier concentration relationships obtained for the implanted samples are close to the empirical relationship for bulk Ge.
Surface enhanced infrared absorption by nanoantenna on chalcogenide glass substrates
Authors: Verger Frédéric , Colas Florent , Sire Olivier , Shen Hong , Rinnert Emmanuel , Boukerma Kada , Nazabal Virgine , Boussard-Plédel Catherine , Bureau Bruno , Toury Timothée , de la Chapelle Marc Lamy , Compère Chantal
Published: February 2015

In recent years, nanowires have been proven efficient to enhanced IR absorption of molecules and opened prospects of new ultrasensitive IR sensors. The development of integrated components requires the use of special IR glasses such as chalcogenide or silver halide glasses. In this study, we report the fabrication of a surface enhanced IR absorption substrate composed of nanowires deposited onto a chalcogenide glass slide. It enabled us to detect 4-nitrophenol at the femtomolar level and enhancement factor close to 106 was calculated.
Optimization of the random multilayer structure to break the random-alloy limit of thermal conductivity
Authors: Wang Yan , Gu Chongjie , Ruan Xiulin
Published: February 2015

A low lattice thermal conductivity (κ) is desired for thermoelectrics, and a highly anisotropic κ is essential for applications such as magnetic layers for heat-assisted magnetic recording, where a high cross-plane (perpendicular to layer) κ is needed to ensure fast writing while a low in-plane κ is required to avoid interaction between adjacent bits of data. In this work, we conduct molecular dynamics simulations to investigate the κ of superlattice (SL), random multilayer (RML) and alloy, and reveal that RML can have 1–2 orders of magnitude higher anisotropy in κ than SL and alloy. We systematically explore how the κ of SL, RML, and alloy changes relative to each other for different bond strength, interface roughness, atomic mass, and structure size, which provides guidance for choosing materials and structural parameters to build RMLs with optimal performance for specific applications.
Diagnosis of energy transport in iron buried layer targets using an extreme ultraviolet laser
Authors: Shahzad M. , Culfa O. , Rossall A. K. , Wilson L. A. , Guilbaud O. , Kazamias S. , Delmas O. , Demailly J. , Maitrallain A. , Pittman M. , Baynard E. , Farjardo M. , Tallents G. J.
Published: February 2015

We demonstrate the use of extreme ultra-violet (EUV) laboratory lasers in probing energy transport in laser irradiated solid targets. EUV transmission through targets containing a thin layer of iron (50 nm) encased in plastic (CH) after irradiation by a short pulse (35 fs) laser focussed to irradiances 3 × 1016 Wcm−2 is measured. Heating of the iron layer gives rise to a rapid decrease in EUV opacity and an increase in the transmission of the 13.9 nm laser radiation as the iron ionizes to Fe5+ and above where the ion ionisation energy is greater than the EUV probe photon energy (89 eV). A one dimensional hydrodynamic fluid code HYADES has been used to simulate the temporal variation in EUV transmission (wavelength 13.9 nm) using IMP opacity values for the iron layer and the simulated transmissions are compared to measured transmission values. When a deliberate pre-pulse is used to preform an expanding plastic plasma, it is found that radiation is important in the heating of the iron layer while for pre-pulse free irradiation, radiation transport is not significant.
Photon-noise limited sensitivity in titanium nitride kinetic inductance detectors
Authors: Hubmayr J. , Beall J. , Becker D. , Cho H.-M. , Devlin M. , Dober B. , Groppi C. , Hilton G. C. , Irwin K. D. , Li D. , Mauskopf P. , Pappas D. P. , Van Lanen J. , Vissers M. R. , Wang Y. , Wei L. F. , Gao J.
Published: February 2015

We demonstrate photon-noise limited performance at sub-millimeter wavelengths in feedhorn-coupled, microwave kinetic inductance detectors made of a TiN/Ti/TiN trilayer superconducting film, tuned to have a transition temperature of 1.4 K. Micro-machining of the silicon-on-insulator wafer backside creates a quarter-wavelength backshort optimized for efficient coupling at 250 μm. Using frequency read out and when viewing a variable temperature blackbody source, we measure device noise consistent with photon noise when the incident optical power is >0.5 pW, corresponding to noise equivalent powers >3×10−17 W/Hz. This sensitivity makes these devices suitable for broadband photometric applications at these wavelengths.
Strain-induced improvement of retention loss in PbZr0.2Ti0.8O3 films
Authors: Guo E. J. , Roth R. , Das S. , Herklotz A. , Dörr K.
Published: February 2015

The retention behavior of nanoscale domains in PbZr0.2Ti0.8O3 thin films is investigated by in-situ controlling the epitaxial strain arising from a piezoelectric substrate. The retention behavior in our sample shows strong polarity-dependence: Upward-poled domains exhibit excellent stability, whereas downward-poled domains reveal a stretched exponential decay. Reversible release of in-plane compressive strain strongly reduced the retention loss, reflected in an enhancement of the relaxation time by up to one order of magnitude. We tentatively attribute the observed behavior to a strain dependence of the built-in field at the interface to the La0.7Sr0.3MnO3 bottom electrode, with a possible further contribution of strain-dependent screening of the depolarizing field. Our work directly reveals the importance of epitaxial strain for reducing ferroelectric domain relaxation which is detrimental for applications such as nonvolatile memory devices.
Enhanced exchange bias in IrMn/CoFe deposited on self-organized hexagonally patterned nanodots
Authors: Li W. J. , Shi D. W. , Greene Peter K. , Javed K. , Liu Kai , Han X. F.
Published: February 2015

Exchange biased nanostructures of IrMn/CoFe were deposited on anodized alumina with hexagonally patterned nanodot surface structures. Nanodots with diameters of 20, 70, and 100 nm were fabricated to investigate the size effect on the magnetic properties. Magnetometry and the first-order reversal curve method revealed significant enhancements of the exchange bias and coercivity in the nanodots compared with flat films. The enhancements can be attributed to the effective reduction of ferromagnet domain sizes and increased random fields due to the nanostructure morphology and domain wall pinning by the boundaries between adjacent nanodots.
Growing antiphase-domain-free GaAs thin films out of highly ordered planar nanowire arrays on exact (001) silicon
Authors: Li Qiang , Ng Kar Wei , Lau Kei May
Published: February 2015

We report the use of highly ordered, dense, and regular arrays of in-plane GaAs nanowires as building blocks to produce antiphase-domain-free GaAs thin films on exact (001) silicon. High quality GaAs nanowires were grown on V-grooved Si (001) substrates using the selective aspect ratio trapping concept. The 4.1% lattice mismatch has been accommodated by the initial GaAs, a few nanometer-thick with high density stacking faults. The bulk of the GaAs wires exhibited smooth facets and a low defect density. An unusual defect trapping mechanism by a “tiara”-like structure formed by Si undercuts was discovered. As a result, we were able to grow large-area antiphase-domain-free GaAs thin films out of the nanowires without using SiO2 sidewalls for defect termination. Analysis from XRD ω-rocking curves yielded full-width-at-half-maximum values of 238 and 154 arc sec from 900 to 2000 nm GaAs thin films, respectively, indicating high crystalline quality. The growth scheme in this work offers a promising path towards integrated III-V electronic, photonic, or photovoltaic devices on large scale silicon platform.
Direct measurements of the magnetocaloric effect in pulsed magnetic fields: The example of the Heusler alloy Ni50Mn35In15
Authors: Ghorbani Zavareh M. , Salazar Mejía C. , Nayak A. K. , Skourski Y. , Wosnitza J. , Felser C. , Nicklas M.
Published: February 2015

We have studied the magnetocaloric effect (MCE) in the shape-memory Heusler alloy Ni50Mn35In15 by direct measurements in pulsed magnetic fields up to 6 and 20 T. The results in 6 T are compared with data obtained from heat-capacity experiments. We find a saturation of the inverse MCE, related to the first-order martensitic transition, with a maximum adiabatic temperature change of ΔTad = −7 K at 250 K and a conventional field-dependent MCE near the second-order ferromagnetic transition in the austenitic phase. The pulsed magnetic field data allow for an analysis of the temperature response of the sample to the magnetic field on a time scale of ∼10 to 100 ms, which is on the order of typical operation frequencies (10–100 Hz) of magnetocaloric cooling devices. Our results disclose that in shape-memory alloys, the different contributions to the MCE and hysteresis effects around the martensitic transition have to be carefully considered for future cooling applications.
Processing dependence of mechanical properties of metallic glass nanowires
Authors: Zhang Qi , Li Qi-Kai , Li Mo
Published: February 2015

Compared to their crystalline counterparts, nanowires made of metallic glass have not only superb properties but also remarkable processing ability. They can be processed easily and cheaply like plastics via a wide range of methods. To date, the underlying mechanisms of how these different processing routes affect the wires' properties as well as the atomic structure remains largely unknown. Here, by using atomistic modeling, we show that different processing methods can greatly influence the mechanical properties. The nanowires made via focused ion beam milling and embossing exhibit higher strength but localized plastic deformation, whereas that made by casting from liquid shows excellent ductility with homogeneous deformation but reduced strength. The different responses are reflected sensitively in the underlying atomic structure and packing density, some of which have been observed experimentally. The presence of the gradient of alloy concentration and surface effect will be discussed.
Third-order intermodulation distortion in graphene resonant channel transistors
Authors: Lekas Michael , Lee Sunwoo , Cha Wujoon , Hone James , Shepard Kenneth
Published: February 2015

Third-order intermodulation distortion (IM3) is an important metric for electromechanical resonators used in radio frequency signal processing applications since it characterizes the nonlinearity of the device, and the amount of in-band interference it generates when subject to unwanted, out-of-band signals. In this letter, we measure and model IM3 in a strain-engineered graphene mechanical resonator operated as a graphene resonant channel transistor (G-RCT). The device analyzed in this work has a voltage third-order intercept point (VIIP3) of 69.5 dBm V at a gate-to-source DC bias (Vgs) of 2.5 V, which drops to 52.1 dBm V at Vgs = 4.5 V when driven with two out-of-band input tones spaced 5 and 10 MHz from the resonant frequency. The decrease in the VIIP3 with Vgs coincides with an increase in the transmission response (S21) of the device, illustrating a trade-off between transduction efficiency and linearity. In addition, we find that conventional micro-electro-mechanical systems theory for IM3 calculation does not accurately describe our measurement data. To resolve this discrepancy, we develop a model for IM3 in G-RCTs that takes into account all of the output current terms present in the embedded transistor structure, as well as an effective Duffing parameter (αeff).
Measurement of chest wall displacement based on terahertz wave
Authors: Li Hui , Lv Hao , Jiao Teng , Lu Guohua , Li Sheng , Li Zhao , Liu Miao , Jing Xijing , Wang Jianqi
Published: February 2015

Measurement of chest wall displacement is an important approach for measuring mechanics of chest wall, which has considerable significance for assessing respiratory system and diagnosing pulmonary diseases. However, existing optical methods for measuring chest wall displacement are inconvenient for some specific patients such as the female patients and the patients with bandaged chest. In this letter, we proposed a method for measuring chest wall displacement based on terahertz wave and established corresponding mathematic model and set up a terahertz measurement system. The main advantages of this method are that it can measure the chest wall displacement of the subjects without taking off clothes or arranging any markers. To validate this method and assess the performance of the terahertz system, in vitro, the displacement of a water module driven by a linear guide rail was measured by the terahertz system and compared with the actual displacement of the water module. The results showed that the waveforms measured with two methods have a good agreement, and the relative error is less than 5% and sufficiently good for measurement demands. In vivo, the synchronous experiment was performed on five human volunteers with the terahertz system and a respiratory belt transducer. The results demonstrate that this method has good performance and promising prospects for measuring chest wall displacement.
Endophyte metabolites associated with perennial ryegrass toxicosis
Authors: Reed K. F. M. , Mace W. J. , Walker L. V. , Fletcher L. R.
Published: February 2015

Perennial ryegrass (PRG) was analysed for alkaloids associated with the expression of perennial ryegrass endophyte toxicosis (PRGT) in south-east Australia. Over two seasons, the PRG cultivar Samson (‘high endophyte’, viz. naturally infected with a wild-type strain of Epichloë festucae var. lolii) was sampled on five occasions during November to May at four farms in Victoria and at Lincoln, New Zealand. Endophyte frequency in the populations was 77–100%. PRG was also sampled from 20 Victorian and Tasmanian farm pastures where stock were experiencing PRGT (endophyte infection frequencies of 87–100%). The Victorian summer of 2010–11 was atypically moist; pasture remained green. Lolitrem B was consistently high at Lincoln and 2–3 times that observed in Victorian samples of isogenetic PRG, or in PRG causing PRGT; it was the dominant toxin in 2011 with concentrations commonly exceeding the tolerance level of 1.8 mg/kg. In the following year, one with a more typical summer, ergovaline was the dominant toxin. Liquid Chromatography–Mass Spectrometry/Mass Spectrometry (LC-MS/MS) was carried out to determine indole diterpene intermediates in the lolitrem B biosynthesis pathway and for ergot alkaloid intermediates in the ergovaline pathway. The values for lolitrem B determined by LC-MS/MS correlated strongly with those obtained using high pressure liquid chromatography. In both Years 1 and 2, significantly higher expression was observed in the Lincoln relative to Victorian samples of PRG for paspaline, terpendole C, lolitrem E, lolitrem B and lolitrem F. For the ergot alkaloids, significant differences were not apparent between Victorian and Lincoln samples in Year 1. In Year 2, LC-MS/MS results showed ergovaline concentrations were greater in Victorian samples. In addition to endophyte-produced toxins, ergot alkaloids produced by Claviceps purpurea (ergotamine, ergocryptine and ergocornine) were detected in grass samples on 6/27 occasions. Some unidentified metabolites were noted in both Victorian and Lincoln samples. The effects of ingested vaso-constrictive ergot alkaloids combined with that of high solar radiation on ruminants’ heat load are considered most important with respect to the occasionally severe expression of PRGT in Australia.
Liveweight gains of young sheep grazing dual-purpose wheat with sodium and magnesium supplied as direct supplement, or with magnesium supplied as fertiliser
Authors: Dove H. , Kelman W. M.
Published: February 2015

In four experiments conducted in 2006–2008 near Canberra, Australia, young sheep grazed vegetative dual-purpose wheat (cv. Mackellar) while receiving either no mineral supplement or receiving extra sodium (Na) and/or magnesium (Mg). In the first two experiments, supplements were fed to the sheep whereas in Experiments 3 and 4, the extra Mg was applied to the crop just before grazing commenced, either as MgSO4 (Experiment 3, 4) or Causmag (MgO; Experiment 4). Direct supplements of Na resulted in increases of liveweight gain of 20–25% (36–42 g/day). In Experiment 2, sheep consumed significantly less of the mixed Na/Mg supplement than of salt alone (12.0 vs 24.8 g/day; P < 0.05) but still grew significantly faster (61 g/day; P < 0.05) than unsupplemented sheep. Application of supplementary Mg to the crop resulted in significant increases in forage Mg, from levels close to animal requirement (0.10% DM) to levels well above this. It also improved a range of mineral indices related to Mg status. Increases in liveweight gain occurred in response to top-dressing of the crop, but compared with feeding Mg directly to the sheep, these were transient and strongly interacted with stocking rate. Estimates of the cost of supplementation or top dressing, and of the value of the extra liveweight gain obtained, indicated that direct supplementation would be economic, but that top-dressing costs would exceed the value of the extra liveweight gain obtained.
Fertilisation, cattle grazing and voles: collapse of meadow vole populations in young forests?
Authors: Sullivan Thomas P. , Sullivan Druscilla S.
Published: February 2015

Context A puzzling aspect of microtine population fluctuations is the damping out or collapsing of cycles over the last three decades, particularly in northern Europe. Occasional population fluctuations of Microtus may also have been damped out in temperate and boreal forests of the Pacific North-west of North America. One cause might be the presence of cattle (Bos taurus) grazing in forest habitats that offer summer forage. Aims We tested hypotheses (H) that abundance, population fluctuations, and demographic parameters of reproduction, recruitment and survival, of Microtus pennsylvanicus would be driven by understory plant productivity. Two predictions follow from this hypothesis: (H1) enhanced abundance and demography in fertilised stands, and (H2) reduced abundance and demography in stands with cattle grazing. Methods Study areas were located in ‘grazed’ and ‘ungrazed’ young forests in south-central British Columbia, Canada. Each study area had four replicate units of unfertilised and repeatedly fertilised stands. Herbaceous vegetation and meadow vole (M. pennsylvanicus) populations were sampled from 1993 to 2002. Key results Mean abundance of total herbs, grasses, and fireweed (Epilobium angustifolium) increased dramatically (8 to 34 times higher) with fertilisation in the ungrazed stands. Mean abundance of meadow voles was 3.1 to 8.5 times higher in the nutrient-enriched herbaceous vegetation in the ungrazed fertilised than grazed fertilised stands. Demographic variables also followed this pattern of abundance. Except for two years, mean abundance of meadow voles was similar between fertilised and unfertilised stands at the grazed area, with some degree of fluctuations generated in grazed stands. Thus, H1 and H2 were at least partly supported for M. pennsylvanicus in fertilised stands. Conclusions In high-quality habitats where cover and other attributes of vegetation are substantial enough to generate population increases and fluctuations of Microtus, grazing of vegetation by cattle or other livestock may indeed lead to potential collapse of fluctuations. Degree of grazing pressure would be crucial, but considering the widespread nature of grazing in the continuum of post-harvest forested sites in the Pacific North-west of North America, moderate to heavy grazing pressure is common. Implications Reductions in populations of microtines have serious consequences for predator communities and other ecological functions.
Habitat use and behaviour of birds in areas invaded by buffel grass (Cenchrus ciliaris L.) and in restored habitat
Authors: Young Lauren , Schlesinger Christine
Published: February 2015

Context
Buffel grass (Cenchrus ciliaris L.) is an introduced pasture grass that has spread over large areas of semiarid Australia with potentially significant negative consequences for biodiversity. Previous studies suggest that the response of bird communities to the changes in habitat associated with buffel grass invasion is complex.

Aims
This study compares the behaviour of birds between sub-sites with predominantly native vegetation where buffel grass had been removed and control sub-sites with buffel grass, which were left unmanaged, at two locations in central Australia. Our objective was to evaluate whether removing buffel grass at small scales had measurable benefits for local bird species and to better understand how the presence of buffel grass affects bird behaviour.

Methods
We assessed differences in microhabitat use and behaviour of all species combined and when separated into above ground, flexible and ground foraging guilds. We also tested for direct correlations between different cover types and the microhabitat use and behaviour of birds within guilds, with some further analyses of three common species individually.

Key results
Management of buffel grass was associated with changes in the microhabitat use and behaviour of birds when all species were combined and for all foraging guilds. Buffel grass cover was negatively correlated with the proportional time birds spent on the ground and with proportional time spent foraging. However, of the three species examined individually only the behaviour of white-winged trillers (Lalage tricolor) was consistently correlated with ground vegetation cover. Our observations also suggest birds spent less time overall at sites with high buffel grass.

Conclusions
Managing buffel grass in small areas creates islands of habitat that provide important opportunities for foraging at a localised scale. Buffel grass and other ground cover affects the behaviour of birds collectively, but individual species responses vary.

Implications
Management of buffel grass in small areas with high conservation value should be considered. Our study will help to inform land managers of the benefits of controlling buffel grass on a localised scale.
Externally definable sets and dependent pairs II
Authors: Chernikov Artem , Simon Pierre
Published: February 2015

We continue investigating the structure of externally definable sets in

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\mathrm {NIP}

theories and preservation of

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\mathrm {NIP}

after expanding by new predicates. Most importantly: types over finite sets are uniformly definable; over a model, a family of non-forking instances of a formula (with parameters ranging over a type-definable set) can be covered with finitely many invariant types; we give some criteria for the boundedness of an expansion by a new predicate in a distal theory; naming an arbitrary small indiscernible sequence preserves

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\mathrm {NIP}

, while naming a large one doesn’t; there are models of

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\mathrm {NIP}

theories over which all 1-types are definable, but not all

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-types.
Comparative study of the effectiveness and limitations of current methods for detecting sequence coevolution
Authors: Mao Wenzhi , Kaya Cihan , Dutta Anindita , Horovitz Amnon , Bahar Ivet
Published: February 2015

Motivation: With rapid accumulation of sequence data on several species, extracting rational and systematic information from multiple sequence alignments (MSAs) is becoming increasingly important. Currently, there is a plethora of computational methods for investigating coupled evolutionary changes in pairs of positions along the amino acid sequence, and making inferences on structure and function. Yet, the significance of coevolution signals remains to be established. Also, a large number of false positives (FPs) arise from insufficient MSA size, phylogenetic background and indirect couplings.

Results: Here, a set of 16 pairs of non-interacting proteins is thoroughly examined to assess the effectiveness and limitations of different methods. The analysis shows that recent computationally expensive methods designed to remove biases from indirect couplings outperform others in detecting tertiary structural contacts as well as eliminating intermolecular FPs; whereas traditional methods such as mutual information benefit from refinements such as shuffling, while being highly efficient. Computations repeated with 2,330 pairs of protein families from the Negatome database corroborated these results. Finally, using a training dataset of 162 families of proteins, we propose a combined method that outperforms existing individual methods. Overall, the study provides simple guidelines towards the choice of suitable methods and strategies based on available MSA size and computing resources.

Availability and implementation: Software is freely available through the Evol component of ProDy API.

Contact:  bahar@pitt.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.
Is the Quality of Sushi Ruined by Freezing Raw Fish and Squid? A Randomized Double-Blind Trial With Sensory Evaluation Using Discrimination Testing
Authors: Iwata Kentaro , Fukuchi Takahiko , Yoshimura Kenichi
Published: February 2015

Background.  Sushi is a traditional Japanese cuisine enjoyed worldwide. However, using raw fish to make sushi may pose risk of certain parasitic infections, such as anisakidosis, which is most reported in Japan. This risk of infection can be eliminated by freezing fish; however, Japanese people are hesitant to freeze fish because it is believed that freezing ruins sushi's taste.

Methods.  A randomized double-blind trial with discrimination testing was conducted to examine the ability of Japanese individuals to distinguish between frozen and unfrozen sushi. A pair of mackerel and squid sushi, one once frozen and the other not, was provided to the participants, and they were asked to answer which one tasted better.

Results.  Among 120 rounds of discrimination testing involving the consumption of 240 pieces of mackerel sushi, unfrozen sushi was believed to taste better in 42.5% (51 dishes) of cases, frozen sushi was thought to taste better in 49.2% (59 dishes), and the participants felt the taste was the same in 8.3% (10 dishes). The odds ratio for selecting unfrozen sushi as “tastes better” over frozen sushi was 0.86 (95% confidence interval [CI], .59–1.26; P = .45). For squid, unfrozen sushi was believed to be superior 48.3% of the time (58 dishes), and frozen sushi, 35.0% of the time (42 dishes). They were felt to be the same in 16.7% (20 dishes) (odds ratio, 1.38; 95% CI, .93–2.05; P = .11).

Conclusions.  Freezing raw fish did not ruin sushi's taste. These findings may encourage the practice of freezing fish before using it in sushi, helping to decrease the incidence of anisakidosis.
Prevalence of HIV-1 drug resistance among patients failing first-line ART in Monrovia, Liberia: a cross-sectional study
Authors: Loubet Paul , Charpentier Charlotte , Visseaux Benoit , Borbor Abraham , Nuta Cecilia , Adu Eric , Chapplain Jean-Marc , Baysah Maima , Tattevin Pierre , Yazdanpanah Yazdan , Descamps Diane
Published: February 2015

Objectives

To assess the prevalence of acquired drug resistance in HIV-1-infected patients living in Monrovia, Liberia, who had clinical and/or immunological failure of first-line ART according to WHO criteria.

Patients and methods

Patients receiving ART for >1 year with clinical and/or immunological failure were included. Sequencing of protease and reverse transcriptase regions was performed using Agence Nationale de Recherche sur le SIDA et les hépatites virales (ANRS) procedures and sequences were interpreted using the ANRS resistance algorithm.

Results

Ninety patients were enrolled. They had been receiving ART for a median time of 42 months and half were receiving zidovudine/lamivudine/nevirapine. Seventy-five per cent of patients were infected with CRF02_AG. Twenty-seven per cent of patients displayed a plasma viral load <50 copies/mL. Among the 66 patients with detectable viraemia, the median viral load was 4.7 log10 copies/mL (IQR = 3.0–5.6). The prevalence of NRTI and NNRTI resistance-associated mutations (RAMs) was 63% and 71%, respectively; and the median number of NRTI and NNRTI RAMs was 2 and 3, respectively. Two patients (4%) displayed viruses with PI RAMs. Regarding NRTI drug resistance, 29%, 38%, 63%, 29% and 25% of patients had viruses resistant to zidovudine, stavudine, lamivudine/emtricitabine, abacavir and tenofovir, respectively. Regarding the NNRTI drug class, 56%, 65%, 33% and 42% of patients had viruses resistant to efavirenz, nevirapine, etravirine and rilpivirine, respectively.

Conclusions

The high prevalence of acquired drug resistance in patients followed in two centres of the Liberian capital city, documented after a median of 3 years on a first-line ART regimen, jeopardizes the activity of second-line regimens and highlights the need for virological monitoring in these settings.
Extracorporeal clearance of colistin methanesulphonate and formed colistin in end-stage renal disease patients receiving intermittent haemodialysis: implications for dosing
Authors: Jitmuang Anupop , Nation Roger L. , Koomanachai Pornpan , Chen Gong , Lee Hee Ji , Wasuwattakul Somkiat , Sritippayawan Suchai , Li Jian , Thamlikitkul Visanu , Landersdorfer Cornelia B.
Published: February 2015

Objectives

Colistin, administered intravenously as its inactive prodrug colistin methanesulphonate (CMS), is being increasingly used. However, there is very limited information available on the impact of haemodialysis (HD) on the pharmacokinetics of CMS and formed colistin.

Patients and methods

A single 30 min intravenous dose of CMS (150 mg of colistin base activity) was administered to 10 patients undergoing HD. HD was performed from 1.5 to 5.5 h after the start of the CMS infusion. Serial blood samples were collected over 50 h, additional blood samples pre- and post-dialysis membrane at three timepoints during HD, dialysate samples at four timepoints during HD, and a cumulative urine sample over 24 h. CMS and colistin were determined by HPLC. Population modelling and determination of HD clearance by multiple methods was conducted.

Results

The average amount of CMS recovered in the dialysate was 30.6% of the dose administered. The concentrations of CMS and colistin in the plasma and the amounts of CMS recovered in the dialysate were well described by the population disposition model. The clearance of CMS by dialysis as estimated by population analysis based on systemic plasma concentrations and amounts in the dialysate was 4.26 L/h (26% coefficient of variation). The dialysis clearance determined from the pre- and post-membrane plasma concentrations was 5.67 L/h (21%) for CMS and 3.99 L/h (44%) for colistin. Thus, CMS clearance by dialysis from trans-cartridge extraction was ∼30% higher than when calculated based on the amount in dialysate, suggesting adsorption to the membrane.

Conclusions

Due to the extensive removal of CMS by dialysis, HD should be conducted at the end of a dosing interval and a supplemental dose should be administered.