bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal configuration and analysis of combined cooling, heating, and power microgrid with thermal storage tank under uncertainty
Authors: Gu Wei , Tang Yiyuan , Peng Shuyong , Wang Delin , Sheng Wanxing , Liu Keyan
Published: January 2015

The optimal configuration and operation of the combined cooling, heating, and power (CCHP) microgrid can be easily influenced by the uncertainty of the cooling, heating, and power load. Although this process can be forecasted, the energy can still deviate from the predicted values. Therefore, this process must be properly planned to prevent unexpected problems and energy waste. In this paper, a CCHP microgrid composed of photovoltaic cell, gas turbines, gas boiler, thermal storage tank (TST), absorption chiller, electric chiller, as well as cooling, heating, and power load is studied. A nonlinear programming model is proposed, which aims to minimize the total costs of the CCHP system. A revised particle swarm optimization algorithm and Monte-Carlo simulation technique are used to solve this model. Three different configuration schemes are proposed to analyse the different influences on the system capacity. The main work of this paper includes comparing the different impacts when the cooling, heating, and power changes, respectively, simultaneously for the system configuration. Meanwhile, the sensitivity analysis for the price of natural gas versus the system configuration is also performed, which presents the function of the thermal storage tank in the system. The results indicate that the TST acts well when the system is under larger uncertainty of the cooling and heating load.
An accurate potential energy surface for the F + H2 → HF + H reaction by the coupled-cluster method
Authors: Chen Jun , Sun Zhigang , Zhang Dong H.
Published: January 2015

A three dimensional potential energy surface for the F + H2 → HF + H reaction has been computed by the spin unrestricted coupled cluster method with singles, doubles, triples, and perturbative quadruples [UCCSDT(2)Q] using the augmented correlation-consistent polarised valence quadruple zeta basis set for the fluorine atom and the correlation-consistent polarised valence quadruple zeta basis set for the hydrogen atom. All the calculations are based on the restricted open-shell Hartree-Fock orbitals, together with the frozen core approximations, and the UCCSD(T)/complete basis set (CBS) correction term was included. The global potential energy surface was calculated by fitting the sampled ab initio points without any scaling factor for the correlation energy part using a neutral network function method. Extensive dynamics calculations have been carried out on the potential energy surface. The reaction rate constants, integral cross sections, product rotational states distribution, and forward and backward scattering as a function of collision energy of the F + HD → HF + D, F + HD → DF + H, and F + H2 reaction, were calculated by the time-independent quantum dynamics scattering theory using the new surface. The satisfactory agreement with the reported experimental observations previously demonstrates the accuracy of the new potential energy surface.
Configuration interaction singles natural orbitals: An orbital basis for an efficient and size intensive multireference description of electronic excited states
Authors: Shu Yinan , Hohenstein Edward G. , Levine Benjamin G.
Published: January 2015

Multireference quantum chemical methods, such as the complete active space self-consistent field (CASSCF) method, have long been the state of the art for computing regions of potential energy surfaces (PESs) where complex, multiconfigurational wavefunctions are required, such as near conical intersections. Herein, we present a computationally efficient alternative to the widely used CASSCF method based on a complete active space configuration interaction (CASCI) expansion built from the state-averaged natural orbitals of configuration interaction singles calculations (CISNOs). This CISNO-CASCI approach is shown to predict vertical excitation energies of molecules with closed-shell ground states similar to those predicted by state averaged (SA)-CASSCF in many cases and to provide an excellent reference for a perturbative treatment of dynamic electron correlation. Absolute energies computed at the CISNO-CASCI level are found to be variationally superior, on average, to other CASCI methods. Unlike SA-CASSCF, CISNO-CASCI provides vertical excitation energies which are both size intensive and size consistent, thus suggesting that CISNO-CASCI would be preferable to SA-CASSCF for the study of systems with multiple excitable centers. The fact that SA-CASSCF and some other CASCI methods do not provide a size intensive/consistent description of excited states is attributed to changes in the orbitals that occur upon introduction of non-interacting subsystems. Finally, CISNO-CASCI is found to provide a suitable description of the PES surrounding a biradicaloid conical intersection in ethylene.
In-situ Raman spectroscopy and high-speed photography of a shocked triaminotrinitrobenzene based explosive
Authors: Saint-Amans C. , Hébert P. , Doucet M. , de Resseguier T.
Published: January 2015

We have developed a single-shot Raman spectroscopy experiment to study at the molecular level the initiation mechanisms that can lead to sustained detonation of a triaminotrinitrobenzene-based explosive. Shocks up to 30 GPa were generated using a two-stage laser-driven flyer plate generator. The samples were confined by an optical window and shock pressure was maintained for at least 30 ns. Photon Doppler Velocimetry measurements were performed at the explosive/window interface to determine the shock pressure profile. Raman spectra were recorded as a function of shock pressure and the shifts of the principal modes were compared to static high-pressure measurements performed in a diamond anvil cell. Our shock data indicate the role of temperature effects. Our Raman spectra also show a progressive extinction of the signal which disappears around 9 GPa. High-speed photography images reveal a simultaneous progressive darkening of the sample surface up to total opacity at 9 GPa. Reflectivity measurements under shock compression show that this opacity is due to a broadening of the absorption spectrum over the entire visible region.
Comment on “Steady-state fluctuations of a genetic feedback loop: An exact solution” [J. Chem. Phys. 137, 035104 (2012)]
Authors: Innocentini Guilherme C. P. , Ramos Alexandre F. , Hornos José Eduardo M.
Published: January 2015

The comment presents the complete steady state solution of the model introduced on ”Steady-state fluctuations of a genetic feedback loop: An exact solution” [Grima et al. J. Chem. Phys. 137, 035104 (2012)]. A closed form for the normalization constant is obtained and hence the explicit calculation of the moments as functions of the parameters is possible. We discuss the meaning of an exact solution to a differential equation and the construction of a model to the understanding of a phenomenon.
Simulation and quasilinear theory of proton firehose instability
Authors: Seough Jungjoon , Yoon Peter H. , Hwang Junga
Published: January 2015

The electromagnetic proton firehose instability is driven by excessive parallel temperature anisotropy, T∥ > T⊥ (or more precisely, parallel pressure anisotropy, P∥ > P⊥) in high-beta plasmas. Together with kinetic instabilities driven by excessive perpendicular temperature anisotropy, namely, electromagnetic proton cyclotron and mirror instabilities, its role in providing the upper limit for the temperature anisotropy in the solar wind is well-known. A recent Letter [Seough et al., Phys. Rev. Lett. 110, 071103 (2013)] employed quasilinear kinetic theory for these instabilities to explain the observed temperature anisotropy upper bound in the solar wind. However, the validity of quasilinear approach has not been rigorously tested until recently. In a recent paper [Seough et al., Phys. Plasmas 21, 062118 (2014)], a comparative study is carried out for the first time in which quasilinear theory of proton cyclotron instability is tested against results obtained from the particle-in-cell simulation method, and it was demonstrated that the agreement was rather excellent. The present paper addresses the same issue involving the proton firehose instability. Unlike the proton cyclotron instability, however, it is found that the quasilinear approximation enjoys only a limited range of validity, especially for the wave dynamics and for the relatively high-beta regime. Possible causes and mechanisms responsible for the discrepancies are speculated and discussed.
Invited Article: A round robin test of the uncertainty on the measurement of the thermoelectric dimensionless figure of merit of Co0.97Ni0.03Sb3
Authors: Alleno E. , Bérardan D. , Byl C. , Candolfi C. , Daou R. , Decourt R. , Guilmeau E. , Hébert S. , Hejtmanek J. , Lenoir B. , Masschelein P. , Ohorodnichuk V. , Pollet M. , Populoh S. , Ravot D. , Rouleau O. , Soulier M.
Published: January 2015

A round robin test aiming at measuring the high-temperature thermoelectric properties was carried out by a group of European (mainly French) laboratories (labs). Polycrystalline skutterudite Co0.97Ni0.03Sb3 was characterized by Seebeck coefficient (8 labs), electrical resistivity (9 labs), thermal diffusivity (6 labs), mass volume density (6 labs), and specific heat (6 labs) measurements. These data were statistically processed to determine the uncertainty on all these measured quantities as a function of temperature and combined to obtain an overall uncertainty on the thermal conductivity (product of thermal diffusivity by density and by specific heat) and on the thermoelectric figure of merit ZT. An increase with temperature of all these uncertainties is observed, in agreement with growing difficulties to measure these quantities when temperature increases. The uncertainties on the electrical resistivity and thermal diffusivity are most likely dominated by the uncertainty on the sample dimensions. The temperature-averaged (300–700 K) relative standard uncertainties at the confidence level of 68% amount to 6%, 8%, 11%, and 19% for the Seebeck coefficient, electrical resistivity, thermal conductivity, and figure of merit ZT, respectively. Thermal conductivity measurements appear as the least accurate. The moderate value of the temperature-averaged relative expanded (confidence level of 95%) uncertainty of 17% on the mean of ZT is essential in establishing Co0.97Ni0.03Sb3 as a high temperature standard n-type thermoelectric material.
Low-bias negative differential resistance effect in armchair graphene nanoribbon junctions
Authors: Li Suchun , Gan Chee Kwan , Son Young-Woo , Feng Yuan Ping , Quek Su Ying
Published: January 2015

Graphene nanoribbons with armchair edges (AGNRs) have bandgaps that can be flexibly tuned via the ribbon width. A junction made of a narrower AGNR sandwiched between two wider AGNR leads was recently reported to possess two perfect transmission channels close to the Fermi level. Here, we report that by using a bias voltage to drive these transmission channels into the gap of the wider AGNR lead, we can obtain a negative differential resistance (NDR) effect. Owing to the intrinsic properties of the AGNR junctions, the on-set bias reaches as low as ∼0.2 V and the valley current almost vanishes. We further show that such NDR effect is robust against details of the atomic structure of the junction, substrate, and whether the junction is made by etching or by hydrogenation.
Focusing surface plasmon and constructing central symmetry of focal field with linearly polarized light
Authors: Liu Jianlong , Gao Yang , Ran Lingling , Guo Kai , Lu Zhiwei , Liu Shutian
Published: January 2015

When linearly polarized light illuminates a plasmonic lens, it is challenging to realize centrally symmetric focal spot in the near field since there is mismatch between the symmetries of the plasmonic structures and the polarization spatial distribution of the incident light. In this paper, we propose a plasmonic lens that can focus surface plasmon to a centrally symmetric field when illuminated by light with linear polarization. Remarkably, the intensity distribution of the focal field is insensitive to the polarization direction, which makes it more reliable in optical applications. Numerical simulations are used to check the performance of the proposed structure. Comparisons with two conventional plasmonic lenses are made to demonstrate its unique superiority in polarization-insensitive focusing.
On the influence of polarization effects in predicting the interfacial structure and capacitance of graphene-like electrodes in ionic liquids
Authors: Paek Eunsu , Pak Alexander J. , Hwang Gyeong S.
Published: January 2015

The electric double layer (CD) and electrode quantum (CQ) capacitances of graphene-based supercapacitors are investigated using a combined molecular dynamics and density functional theory approach. In particular, we compare an approach that includes electronic polarization to one that is polarization-free by evaluating both CD and CQ using [EMIM][BF4] ionic liquid as a model electrolyte. Our results indicate that the inclusion of polarization effects can yield higher CD values—in this study by up to 40% around ±2 V—which we attribute primarily to the presence of charge smearing at the electrode-electrolyte interface. On the other hand, we find that the polarization-induced distortion of the electronic structure of graphene does not noticeably alter the predicted CQ. Our analysis suggests that an accurate description of the spatial charge distribution at the graphene interface due to polarization is necessary to improve our predictive capabilities, though more notably for CD. However, the conventional polarization-free approximation can serve as an efficient tool to study trends associated with both the CQ and CD at the interface of various graphene-like materials.
Second harmonic generation by relativistic self-focusing of q-Gaussian laser beam in preformed parabolic plasma channel
Authors: Singh Arvinder , Gupta Naveen
Published: January 2015

This paper presents an investigation of relativistic self-focusing effect of a q-Gaussian laser beam on second harmonic generation in a preformed parabolic plasma channel. An expression has been derived for density perturbation associated with the plasma wave excited by the laser beam. This in turn acts as a source of second harmonic generation. The moment theory approach has been used to derive a differential equation that governs the evolution of spot size of the laser beam with the distance of propagation. The detailed effects of intensity distribution deviation from Gaussian distribution, intensity of laser beam, density, and depth of the channel have been studied on self-focusing as well as on second harmonic generation.
Langmuir probe and optical emission spectroscopy studies in magnetron sputtering plasmas for Al-doped ZnO film deposition
Authors: Sahu B. B. , Han Jeon G. , Hori Masaru , Takeda Keigo
Published: January 2015

This work reports investigation of the Al-doped ZnO (AZO) film deposition process, at different working pressures, in a conventional magnetron sputtering system. The primary goal of this study is to investigate the plasma formation and deposition process using various diagnostic tools, by utilizing low-temperature deposition process. In addition, this paper also presents a systematic Langmuir probe (LP) analysis procedure to determine the maximum information about plasma parameters. For the present study, we have extensively used LP method to characterize the deposition process for the control of plasma parameters. Along with the LP method, we have also used optical emission spectroscopy diagnostic to examine the favorable deposition condition for the fabrication of conductive AZO film. Utilizing diagnostics, this also reports measurements of ion current density, substrate temperature, and deposition rates to fabricate low resistivity films of ∼3 mΩ cm.
Plasmon resonance enhanced mechanical detection of ligand binding
Authors: Ariyaratne Amila , Zocchi Giovanni
Published: January 2015

Small molecule binding to the active site of enzymes typically modifies the mechanical stiffness of the enzyme. We exploit this effect, in a setup which combines nano-mechanics and surface plasmon resonance (SPR) enhanced optics, for the label free detection of ligand binding to an enzyme. The large dynamic range of the signal allows to easily obtain binding curves for small ligands, in contrast to traditional SPR methods which rely on small changes in index of refraction. Enzyme mechanics, assessed by nano-rheology, thus emerges as an alternative to electronic and spin resonances, assessed by traditional spectroscopies, for detecting ligand binding.
Low temperature dependence of triboelectric effect for energy harvesting and self-powered active sensing
Authors: Su Yuanjie , Chen Jun , Wu Zhiming , Jiang Yadong
Published: January 2015

The triboelectric nanogenerator (TENG) has been proved as a simple, reliable, cost-effective, and efficient means to harvest ambient mechanical energy in a normal environment, although its performance evaluation under the room temperature is still lacking. Here, we systematically looked into the reliance of triboelectric nanogenerators output on the ambient temperature spanning from 77 K to 320 K. Employed the most commonly used Polytetrafluoroethylene (PTFE) and aluminum as two contact materials, both the output voltage and current show a tendency of increase with decreasing temperature. Applicability of triboelectric nanogenerator over a wide range of temperature was confirmed from 77 K to 320 K. And, an output enhancement of 79.3% was experimentally obtained at the temperature of 77 K compared to that at a temperature of 300 K. However, a reverse tendency was observed for the TiO2 nanotubes/PTFE and Al coated TiO2 nanotubes/PTFE based triboelectric nanogenerators. This work can contribute not only to the design and packaging of triboelectric devices to operate at extreme environmental temperatures but also to the fundamental understanding of the mechanism of triboelectric effect.
Structural properties and growth mechanism of Cd3As2 nanowires
Authors: Schönherr P. , Hesjedal T.
Published: January 2015

Cadmium arsenide (Cd3As2) is a material well-known for its very high room-temperature carrier mobility. Recently, it has also been shown to be a three-dimensional Dirac semimetal—the three-dimensional analogue of graphene. Here, we present a detailed structural study of the self-catalyzed growth of Cd3As2 nanowires. The crystal structure is confirmed using X-ray diffraction and transmission electron microscopy. Scanning electron microscopy and energy-dispersive X-ray spectroscopy are used to gain insight into the vapor-solid growth mechanism. The role of group II and V elements is reversed in contrast to III-V and other II-V systems, and the tips are found to be As-rich.
Bias-selectable dual-band mid-/long-wavelength infrared photodetectors based on InAs/InAs1−xSbx type-II superlattices
Authors: Haddadi A. , Chevallier R. , Chen G. , Hoang A. M. , Razeghi M.
Published: January 2015

A high performance bias-selectable mid-/long-wavelength infrared photodetector based on InAs/InAs1−xSbx type-II superlattices on GaSb substrate has been demonstrated. The mid- and long-wavelength channels' 50% cut-off wavelengths were ∼5.1 and ∼9.5 μm at 77 K. The mid-wavelength channel exhibited a quantum efficiency of 45% at 100 mV bias voltage under front-side illumination and without any anti-reflection coating. With a dark current density of 1 × 10−7 A/cm2 under 100 mV applied bias, the mid-wavelength channel exhibited a specific detectivity of 8.2 × 1012 cm·Hz/W at 77 K. The long-wavelength channel exhibited a quantum efficiency of 40%, a dark current density of 5.7 × 10−4 A/cm2 under −150 mV applied bias at 77 K, providing a specific detectivity value of 1.64 × 1011 cm·Hz/W.
Flower-shaped ZnO nanocrystallite aggregates synthesized through a template-free aqueous solution method for dye-sensitized solar cells
Authors: Chang Wei-Chen , Chen Hung-Shuo , Yu Wan-Chin
Published: January 2015

Hierarchically structured flower-shaped aggregates composed of ZnO nanocrystals were synthesized through a template-free aqueous solution method. The synthesized nanocrystallite aggregates were demonstrated to be promising photoanode materials for dye-sensitized solar cells (DSSCs). Compared with commercially available ZnO nanoparticles (ZnONPs), the flower-like aggregates (ZnONFs), each having an overall dimension of 400–600 nm, exhibited similar dye loading but higher light-scattering ability, which led to a substantial increase in the light-harvesting efficiency of resulting cells. The unique morphology of ZnONFs also boosted the absorbed photon-to-electric current generation efficiency. Consequently, DSSCs constructed from ZnONFs showed significantly improved photocurrent and achieved an overall conversion efficiency of 4.42%, which was 47% higher than that attained by ZnONP-based cells.
Spectroscopic ellipsometry on Si/SiO2/graphene tri-layer system exposed to downstream hydrogen plasma: Effects of hydrogenation and chemical sputtering
Authors: Eren Baran , Fu Wangyang , Marot Laurent , Calame Michel , Steiner Roland , Meyer Ernst
Published: January 2015

In this work, the optical response of graphene to hydrogen plasma treatment is investigated with spectroscopic ellipsometry measurements. Although the electronic transport properties and Raman spectrum of graphene change after plasma hydrogenation, ellipsometric parameters of the Si/SiO2/graphene tri-layer system do not change. This is attributed to plasma hydrogenated graphene still being electrically conductive, since the light absorption of conducting 2D materials does not depend on the electronic band structure. A change in the light transmission can only be observed when higher energy hydrogen ions (30 eV) are employed, which chemically sputter the graphene layer. An optical contrast is still apparent after sputtering due to the remaining traces of graphene and hydrocarbons on the surface. In brief, plasma treatment does not change the light transmission of graphene; and when it does, this is actually due to plasma damage rather than plasma hydrogenation.
Reproducible magnetostrain behavior induced by structure transformation for Ni46Co4Mn39Sn11 Heusler alloy
Authors: Li Z. , Xu K. , Zhang Y. L. , Jing C.
Published: January 2015

This paper presents the strain behavior associated with martensitic transformation for polycrystalline Ni46Co4Mn39Sn11. The unique reproducible magnetostrain in this alloy has been realized within a magnetic field change of 3 T, and its maximum value achieves about 0.012% at 225 K, which is almost ten times higher than that in Ni-Mn-Sn ternary alloy. Such a reproducible phenomenon could be attributed to the occurrence of the reversible transformation between multi-variant martensite and austenite under an applied isothermal magnetic field.
Electric field-induced phase transitions in Li-modified Na0.5K0.5NbO3 at the polymorphic phase boundary
Authors: Iamsasri Thanakorn , Tutuncu Goknur , Uthaisar Chunmanus , Wongsaenmai Supattra , Pojprapai Soodkhet , Jones Jacob L.
Published: January 2015

The electric field-induced phase transitions in Li-modified Na0.5K0.5NbO3 at the polymorphic phase boundary (PPB) were observed using in situ X-ray diffraction. The ratio of monoclinic to tetragonal phase fraction was used as an indicator of the extent and reversibility of the phase transitions. The reversibility of the phase transition was greater in compositions further from the PPB. These results demonstrate that the field-induced phase transition is one of the origins of high piezoelectric properties in lead-free ferroelectric materials.
Photoemission characteristics of thin GaAs-based heterojunction photocathodes
Authors: Feng Cheng , Zhang Yijun , Qian Yunsheng , Shi Feng , Zou Jijun , Zeng Yugang
Published: January 2015

To better understand the different photoemission mechanism of thin heterojunction photocathodes, the quantum efficiency models of reflection-mode and transmission-mode GaAs-based heterojunction photocathodes are revised based on one-dimensional continuity equations, wherein photoelectrons generated from both the emission layer and buffer layer are taken into account. By comparison of simulated results between the revised and conventional models, it is found that the electron contribution from the buffer layer to shortwave quantum efficiency is closely related to some factors, such as the thicknesses of emission layer and buffer layer and the interface recombination velocity. Besides, the experimental quantum efficiency data of reflection-mode and transmission-mode AlGaAs/GaAs photocathodes are well fitted to the revised models, which confirm the applicability of the revised quantum efficiency models.
Intense ion beam neutralization using underdense background plasma
Authors: Berdanier William , Roy Prabir K. , Kaganovich Igor
Published: January 2015

Producing an overdense background plasma for neutralization purposes with a density that is high compared to the beam density is not always experimentally possible. We show that even an underdense background plasma with a small relative density can achieve high neutralization of intense ion beam pulses. Using particle-in-cell simulations, we show that if the total plasma electron charge is not sufficient to neutralize the beam charge, electron emitters are necessary for effective neutralization but are not needed if the plasma volume is so large that the total available charge in the electrons exceeds that of the ion beam. Several regimes of possible underdense/tenuous neutralization plasma densities are investigated with and without electron emitters or dense plasma at periphery regions, including the case of electron emitters without plasma, which does not effectively neutralize the beam. Over 95% neutralization is achieved for even very underdense background plasma with plasma density 1/15th the beam density. We compare results of particle-in-cell simulations with an analytic model of neutralization and find close agreement with the particle-in-cell simulations. Further, we show experimental data from the National Drift Compression experiment-II group that verifies the result that underdense plasma can neutralize intense heavy ion beams effectively.
Laser-driven ion acceleration with hollow laser beams
Authors: Brabetz C. , Busold S. , Cowan T. , Deppert O. , Jahn D. , Kester O. , Roth M. , Schumacher D. , Bagnoud V.
Published: January 2015

The laser-driven acceleration of protons from thin foils irradiated by hollow high-intensity laser beams in the regime of target normal sheath acceleration (TNSA) is reported for the first time. The use of hollow beams aims at reducing the initial emission solid angle of the TNSA source, due to a flattening of the electron sheath at the target rear side. The experiments were conducted at the PHELIX laser facility at the GSI Helmholtzzentrum für Schwerionenforschung GmbH with laser intensities in the range from 1018 W cm−2 to 1020 W cm−2. We observed an average reduction of the half opening angle by (3.07±0.42)° or (13.2±2.0)% when the targets have a thickness between 12 μm and 14 μm. In addition, the highest proton energies were achieved with the hollow laser beam in comparison to the typical Gaussian focal spot.
Raman spectra analysis for Ba[(Mg1-
x
Ni
x
)1/3Nb2/3]O3 microwave dielectric ceramics
Authors: Sun Tu Lai , Chen Xiang Ming
Published: January 2015

Raman spectra analysis has been carried out for both the as-sintered and annealed Ba[(Mg1−xNix)1/3Nb2/3]O3 ceramics. Based on the harmonic resonant model, all the Raman modes are successfully assigned according to the effects of ion substitution and post-densification annealing. All of the as-sintered samples present 7 normal modes as predicted by factor group analysis; an extra mode at around 560 cm−1 exists in x = 0.6-1.0. The 3 modes Eg(O), Eg(Nb), A1g(Nb) between 150-350 cm−1 decrease in intensity with increasing x, agreeing well with the variation of ordering degree. By post-densification annealing for x = 0.4, a strong dependence on ordering degree has been proved for the A1g(O) mode at around 790 cm−1. For the as-sintered samples, the Q × f value correlates well with the oxygen octahedron stretch mode A1g(O), while the dielectric constant εr is dominated by ionic polarizability rather than the rigidity of the oxygen octahedra. After annealing, the Raman modes are intensified, corresponding to the enhancement of cations ordering. The annealing significantly increases the A1g(O) Raman shift and decreases the FWHM (full width at half maximum) of A1g(O) mode, resulting in the increase of εr and the improvement of Q × f value for each composition. The intensity ratio of A1g(Ba)+Eg(Ba) mode to A1g(O) mode increases after annealing, implying that A1g(Ba)+Eg(Ba) is more dominant in the ordered structure.
Graphene Q-switched Yb:KYW planar waveguide laser
Authors: Kim Jun Wan , Young Choi Sun , Aravazhi Shanmugam , Pollnau Markus , Griebner Uwe , Petrov Valentin , Bae Sukang , Jun Ahn Kwang , Yeom Dong-Il , Rotermund Fabian
Published: January 2015

A diode-pumped Yb:KYW planar waveguide laser, single-mode Q-switched by evanescent-field interaction with graphene, is demonstrated for the first time. Few-layer graphene grown by chemical vapor deposition is transferred onto the top of a guiding layer, which initiates stable Q-switched operation in a 2.4-cm-long waveguide laser operating near 1027 nm. Average output powers up to 34 mW and pulse durations as short as 349 ns are achieved. The measured output beam profile, clearly exhibiting a single mode, agrees well with the theoretically calculated mode intensity distribution inside the waveguide. As the pump power is increased, the repetition rate and pulse energy increase from 191 to 607 kHz and from 7.4 to 58.6 nJ, respectively, whereas the pulse duration decreases from 2.09 μs to 349 ns.
Algae and prey associated with traps of the Australian carnivorous plant Utricularia volubilis (Lentibulariaceae : Utricularia subgenus Polypompholyx) in natural habitat and in cultivation
Authors: Płachno Bartosz J. , Wołowski Konrad , Fleischmann Andreas , Lowrie Allen , Łukaszek Magdalena
Published: January 2015

The carnivorous plant genus Utricularia comprises three monophyletic subgenera, Polypompholyx, Bivalvaria, and Utricularia; however, all Utricularia species produce sophisticated suction traps. Most studies on the interactions between this genus and algae were performed on the derived aquatic bladderworts from Utricularia subgenus Utricularia, section Utricularia, thus our knowledge about phytotelmata in bladderworts is still limited. The main aim of our study was to examine the composition of algae and prey in phytotelmata of U. volubilis R.Br., the Australian species from subgenus Polypompholyx, that has different construction of the trap door and trigger mechanism than species studied so far within the context of trapped organisms. We examined the contents of traps collected at a natural site in Western Australia, and from cultivated material grown in a botanical garden. The traps from the natural site in Australia contained predominantly diatoms, mainly of the genus Frustulia. Young traps from the botanical garden contained mainly diatoms, xanthophytes and green algae, while in the older traps, cyanobacteria prevailed. In general these observations were in agreement with the data obtained for aquatic bladderworts from section Utricularia, thus suggesting that the type of trigger mechanism has a minor influence on the composition of the trapped algae and prey.
Phenotypic effects of additional chromosomes on agronomic and photosynthetic traits of common wheat in the background of Chinese Spring
Authors: Liu Caiyun , Yang Zhiyuan , Chen Xiaojie , Tsujimoto Hisashi , Hu Yin-Gang
Published: January 2015

Wheat alien chromosome addition lines possess abundant genetic resources and they are usually used for transferring desired genes or traits into wheat. The screening and characterisation of addition lines for target traits is one of the prerequisites for efficient utilisation of the alien chromosomes. In order to understand the properties and potential utilisation of wheat addition lines, the effects of additional chromosomes on agronomic and photosynthetic traits of common wheat were evaluated using 34 addition lines with the same genetic background of Chinese Spring. The results showed that most of the alien chromosomes decreased plant height (61.8%) and grain number per spike (47.1%), whereas some increased spike length and tiller number. Alien chromosomes of Agropyron intermedium G, Elymus trachycaulus T5HL5HL, El. trachycaulus 5SS and Haynaldia villosa 1V performed well in improving yield components. None of the alien chromosomes studied had negative effects on photosynthetic traits. Higher net photosynthetic rates were observed in Aegilops umbellulata 5U, El. trachycaulus 5H and rye 1R addition lines. Regarding seedling traits, 21 lines (61.8%) showed improvement in different root traits, whereas 26.5% of the chromosomes decreased coleoptile length. Addition lines with better performance for some specific traits were identified and discussed.
Inference for dynamic and latent variable models via iterated, perturbed Bayes maps
Authors: Ionides Edward L. , Nguyen Dao , Atchadé Yves , Stoev Stilian , King Aaron A.
Published: January 2015

Significance

Many scientific challenges involve the study of stochastic dynamic systems for which only noisy or incomplete measurements are available. Inference for partially observed Markov process models provides a framework for formulating and answering questions about these systems. Except when the system is small, or approximately linear and Gaussian, state-of-the-art statistical methods are required to make efficient use of available data. Evaluation of the likelihood for a partially observed Markov process model can be formulated as a filtering problem. Iterated filtering algorithms carry out repeated Monte Carlo filtering operations to maximize the likelihood. We develop a new theoretical framework for iterated filtering and construct a new algorithm that dramatically outperforms previous approaches on a challenging inference problem in disease ecology.
A chemiosmotic mechanism of symport
Authors: Kaback H. Ronald
Published: January 2015

Lactose permease (LacY), a paradigm for the largest family of membrane transport proteins, catalyzes the coupled translocation of a galactoside and an H
+
across the
Escherichia coli
membrane (galactoside/H
+
symport). Initial X-ray structures reveal N- and C-terminal domains, each with six largely irregular transmembrane helices surrounding an aqueous cavity open to the cytoplasm. Recently, a structure with a narrow periplasmic opening and an occluded galactoside was obtained, confirming many observations and indicating that sugar binding involves induced fit. LacY catalyzes symport by an alternating access mechanism. Experimental findings garnered over 45 y indicate the following: (
i
) The limiting step for lactose/H
+
symport in the absence of the H
+
electrochemical gradient (∆
µ
̃
H
+) is deprotonation, whereas in the presence of ∆
µ
̃
H
+, the limiting step is opening of apo LacY on the other side of the membrane; (
ii
) LacY must be protonated to bind galactoside (the pK for binding is ∼10.5); (
iii
) galactoside binding and dissociation, not ∆
µ
̃
H
+, are the driving forces for alternating access; (
iv
) galactoside binding involves induced fit, causing transition to an occluded intermediate that undergoes alternating access; (
v
) galactoside dissociates, releasing the energy of binding; and (
vi
) Arg302 comes into proximity with protonated Glu325, causing deprotonation. Accumulation of galactoside against a concentration gradient does not involve a change in
K
d
for sugar on either side of the membrane, but the pK
a
(the affinity for H
+
) decreases markedly. Thus, transport is driven chemiosmotically but, contrary to expectation, ∆µ̃
H
+ acts kinetically to control the rate of the process.
Coastal Distribution and Consequent Factors Influencing Production of Endangered Snake River Sockeye Salmon
Authors: Tucker S. , Thiess M. E. , Morris J. F. T. , Mackas D. , Peterson W. T. , Candy J. R. , Beacham T. D. , Iwamoto E. M. , Teel D. J. , Peterson M. , Trudel M.
Published: January 2015

Snake River Sockeye Salmon Oncorhynchus nerka were declared endangered in 1991 after several years of decreasing abundance. Several factors, including poor marine survival, likely contributed to the decline of Snake River Sockeye Salmon. Little is known about their migration and ocean distribution and the factors influencing their production. We sampled (1) coastal waters from southern British Columbia (BC) to southeast Alaska during June–July, October–November, and February–March 1998–2011; and (2) Oregon and Washington coastal waters during May–June and September 2007–2010. In total, 8,227 juvenile Sockeye Salmon were captured. Despite their extremely low abundance relative to other stocks, 15 coded‐wire‐tagged juveniles from Redfish Lake were recovered since 2007, primarily in spring and summer surveys off the BC coast. Genetic analyses revealed that an additional eight Redfish Lake juveniles were also present in this area during summer. Snake River smolts undertook a rapid northward migration that brought them well beyond the Columbia River estuary and plume, exposing them to ocean conditions prevailing off BC. Through a multimodel inference approach, we characterized associations between the number of returning adults and a suite of ocean and river variables. Seven ocean variables and five river variables were chosen for the model selection analysis (e.g., copepod biomass anomalies, coastal upwelling indices, date of the spring transition, river discharge, river temperature, and the proportion of smolts transported through the hydropower system). Although adult returns were highly correlated with smolt abundance, our analyses suggest that ocean conditions encountered during the first growing season (as indexed by copepod anomalies) contribute to the variability in total adult returns. There was also evidence for a negative effect of transporting smolts through the hydropower system, with the caveat that we used transportation data for steelhead O. mykiss as a proxy.

Received April 4, 2014; accepted September 15, 2014
Early Emigration of Juvenile Coho Salmon: Implications for Population Monitoring
Authors: Rebenack Jennifer J. , Ricker Seth , Anderson Colin , Wallace Michael , Ward Darren M.
Published: January 2015

Salmon monitoring programs often measure juvenile production by operating migrant traps downstream of spawning and rearing areas during smolt migration. However, this approach does not account for individuals that move downstream of trapping locations prior to smolt sampling. We used a mark–recapture study with passive integrated transponder tagging to estimate the proportion of Coho Salmon Oncorhynchus kisutch juveniles, tagged in the fall in a Northern California stream, that migrated to rearing habitat downstream of a seasonally operated trap before spring smolt sampling. Emigrants were detected by using the migrant trap, located near the upstream limit of tidal influence, and continuously operated antennas located in tidal wetlands downstream of the trap. For all three cohorts sampled (2010, 2011, 2012), we identified two distinct emigration periods (not including fry emigrants that emigrated in spring at a size too small to tag): a fall–winter period, when early emigrant parr moved into a restored tidal wetland (early emigrants); and a spring period, when smolts emigrated (smolt emigrants). There was little movement in the intervening period. Emigration timing varied depending on the location in the basin where fish were tagged; locations in the lower main stem generally produced more early emigrants, while locations in the upper basin produced more smolt emigrants. Across locations, early emigrants accounted for 2–25% of the fall‐marked juveniles from 2010, 8–29% from 2011, and 7–13% in 2012. Smolt emigrants accounted for 15–49% of the fall‐marked juveniles from 2010, 13–14% from 2011, and 3–35% from 2012. The consistent occurrence of early emigration in this and other recent studies brings into question estimates of smolt abundance and demographic rates (e.g., overwinter and marine survival) that do not account for this life history variant.

Received June 19, 2014; accepted October 23, 2014
Microchemical Signatures in Juvenile Winter Flounder Otoliths Provide Identification of Natal Nurseries
Authors: Bailey David S. , Fairchild Elizabeth A. , Kalnejais Linda H.
Published: January 2015

Variation of otolith microchemical signatures between natal nurseries from young‐of‐the‐year (age 0) Winter Flounder Pseudopleuronectes americanus were evaluated. Fish were collected in summer 2012 from 12 nursery areas from New Jersey to New Hampshire, spanning >500 km. Nursery specific microchemical signatures were developed using element : Ca ratios, which were determined with solution‐based inductively coupled plasma‐mass spectrometry on the whole otolith. Age‐0 flounder microchemical signatures showed significant nursery‐specific differences and varied on a small spatial scale (about 12 km) based on elemental (Li, Na, Mg, Mn, Sr, Cd, and Ba) ratios. Via quadratic discriminant function analysis, fish were classified back to natal nursery areas with 73% average cross‐validation classification accuracies. Based on this preliminary study, otolith microchemistry has the potential to be an effective tool to assess the connectivity between the inshore nursery areas and the offshore adult populations of Winter Flounder; however, further baseline studies are needed. In particular, between‐year and within‐year variation in the otolith elemental concentrations must be quantified. These elemental analyses need to be linked to specific management needs to be useful to fisheries managers; for Winter Flounder, the ability to rank estuaries by the yield of recruits may help solve estuary‐specific anthropogenic challenges.

Received July 11, 2014; accepted October 16, 2014
Long‐Term Increases in Trout Abundance following Channel Reconstruction, Instream Wood Placement, and Livestock Removal from a Spring Creek in the Blackfoot Basin, Montana
Authors: Pierce Ron , Podner Craig , Jones Leslie
Published: January 2015

To restore habitat for wild trout, Kleinschmidt Creek, a low‐gradient, groundwater‐dominated stream in the Blackfoot Basin, Montana, was reconstructed using natural channel design principles. Reconstruction increased stream sinuosity from a ratio of 1.1 to 1.6, decreased mean channel width from 14.5 to 2.8 m, and increased sediment transport capacity to reduce accumulations of fine instream sediment. To further improve trout habitat, coarse woody debris (CWD) was variably placed within the new channel and livestock were excluded to promote the vegetative recovery of the riparian area. To evaluate the response of wild trout (92% Brown Trout Salmo trutta) to channel restoration, the abundance (number of trout per linear meter) and biomass (g/linear m) of age 1+ trout were monitored for 15 years (1998–2012) in a reach with low density CWD (1.3 stems/100 m) and compared with regional (reference) trends. Posttreatment (2002–2012) trout numbers in the low‐density CWD reach were also compared with those in a reach with high‐density CWD (18.2 stems/100 m). Long‐term trends for the reference reaches showed a significant negative trend in trout abundance and no significant trend for biomass. Long‐term trends for the low‐density CWD reach showed a significant positive trend in abundance, as well as a significant trend in biomass. Trout abundance and biomass increased over the posttreatment period in the low‐density CWD reach. However, in the high density CWD reach, while posttreatment abundance increased significantly, there was no significant trend in biomass. These results demonstrated that channel restoration increased wild trout populations in a deep, narrow, vegetated stream and that instream wood provided primarily short‐term benefits during the early phase of habitat recovery.

Received November 26, 2013; accepted October 18, 2014
Varying Effects of Common Reed Invasion on Early Life History of Northern Pike
Authors: Larochelle Mélissa , Dumont Pierre , Lavoie Claude , Hatin Daniel
Published: January 2015

The invasion of North American wetlands by the Eurasian subspecies of common reed Phragmites australis australis is well documented, but very few studies have been conducted on its effects on freshwater fish communities. Northern Pike Esox lucius is one of several fish species using wetlands for reproduction and early development that could be affected by the spread of common reed. The effects of vegetation type (common reed stands, other reference plant assemblages) were evaluated on four aspects (egg deposition, abundance, growth, and feeding) of the early life history of Northern Pike in two St. Lawrence River wetlands in Quebec. During high water levels in 2009, the relative abundance of Northern Pike eggs was three times higher in the reference plant assemblages than in the common reed stands at the two study sites. In 2010, when water levels were extremely low and few other plant assemblages were accessible by fish, the relative abundance of eggs was two times higher in the common reed stands than in other plant assemblages within the only site available for sampling. In 2009, the relative abundance, length, and weight of age‐0 Northern Pike did not differ significantly between common reed stands and reference assemblages. Growth rate, condition, prey type, and relationship between digestive tract dry weight and total fish dry weight suggested slightly more favorable conditions in common reed stands in some cases or in reference assemblages in other cases (no consistent pattern between the vegetation types). Although common reed is still in the early invasion process in St. Lawrence River freshwater marshes, it does not seem to have any negative effects on Northern Pike early life history. However, little is known about the magnitude of common reed biomass accumulation, making it impossible to predict whether these stands, which are part of an ongoing invasion, will provide long‐term quality habitat.

Received March 3, 2014; accepted October 10, 2014
‘African Peasants and Revolution’ revisited
Authors: Bernstein Henry
Published: January 2015

This short essay begins by revisiting John Saul's landmark article in the first issue of theReview of African Political Economyin 1974, which was, inevitably, very much of its historical moment. The author suggests that Saul used an ideal-typical conception of ‘peasants’ combined with a particular view of ‘incomplete’ capitalism established by colonial rule in Africa and continuing since political independence. He then proposes, in highly selective and abbreviated fashion, an alternative approach to understanding the social conditions of existence of African ‘peasants’ and the politics of Africa's agrarian questions. He illustrates his argument with special reference to the current moment of globalisation and neoliberalism. ‘Globalisation’ serves as shorthand for the restructuring of capital on a world scale since the 1970s (and not least ‘financialisation’), while he uses ‘neoliberalism’ to refer to the political and ideological project of promoting the interests of capital in such restructuring at the expense of the interests of labour. He concludes with some broad historical theses about ‘African Peasants and Revolution’.
The graphic nature of Gaussian periods
Authors: Duke William , Garcia Stephan , Lutz Bob
Published: January 2015

Recent work has shown that the study of supercharacters on abelian groups provides a natural framework within which to study certain exponential sums of interest in number theory. Our aim here is to initiate the study of Gaussian periods from this novel perspective. Among other things, our approach reveals that these classical objects display dazzling visual patterns of great complexity and remarkable subtlety.