bluuebunny/crossref_metadata_2025 huggingface dataset:
Feasibility of electron and hole injection in heavily doped strontium barium niobate (SBN50) Sr0.5Ba0.5Nb2O6 for thermoelectric applications
Authors: Ottini Riccardo , Tealdi Cristina , Tomasi Corrado , Tredici Ilenia G. , Soffientini Alessandro , Anselmi-Tamburini Umberto , Ghigna Paolo , Spinolo Giorgio
Published: March 2017

Undoped and heavily doped (K, Y, Zr, Mo) strontium barium niobate Sr0.5Ba0.5Nb2O6 (SBN50) materials have been prepared by co-precipitation. X-ray diffraction shows the formation of a single-phase product and that 10% and 12.5% of the Nb sites can be occupied by Zr and Mo, respectively. K can enter 40% of the Sr sites, while the maximum Y substitution is also around 40%. The starting stoichiometry is effective in driving the substitutions to the desired sites. X-ray Absorption Spectroscopy (XAS) at the Nb-K edge shows the presence of Nb(V) independent of doping. A pre-edge 1s-4d transition surprisingly indicates the hole injection with Y doping and the electron injection with Zr doping. Chemical reduction does not affect the stability of the structure, except for a small decrease of maximum Y solubility, while the Nb(V) oxidation state and the XAS pre-edge feature are unmodified. The oxidized samples are insulators, the reduced samples show electrical conductivity, and doping significantly enhances thermopower and electrical conductivity. The Y doped sample shows a power factor ∼30 times larger than that of the undoped sample.
Investigation of multiferroicity, spin-phonon coupling, and unusual magnetic ordering close to room temperature in LuMn0.5Fe0.5O3
Authors: Sarkar Tanushree , Manna Kaustuv , Elizabeth Suja , Anil Kumar P. S.
Published: March 2017

We report the detailed experimental characteristics of LuMn0.5Fe0.5O3 synthesized by the wet chemical method and proclaim it as a new member of the multiferroic family. The compound stabilizes in P63cm crystal symmetry. It exhibits a spin re-orientation transition at TSR and an antiferromagnetic transition at TN. In addition, our magnetization vs. temperature data reveals an extra broad maximum close to room temperature; unseen in earlier studies. By invoking the compatible nature of the magnetic exchange path in P63cm symmetry, we have argued that the origin lies in the intraplane short-range spin ordering. Heat capacity is measured and analysed to elucidate the magnetic entropy. Though long-range antiferromagnetic ordering vanishes at TN ∼ 103 K, we find the experimental magnetic entropy calculated till 200 K is less by a significant amount from the value of theoretical spin randomization magnetic entropy; further supporting the existence of spin ordering beyond TN and even above 200 K. While the specific heat data and phonon modes of Raman spectra show a signature of spin-phonon coupling at TSR and TN both, dielectric anomaly indicating a magnetoelectric effect is seen only at TN. Piezoresponse force microscopy and ferroelectric hysteresis loop measurement confirm the room-temperature weak ferroelectricity with a saturation polarization value 0.007 μC/cm2 and low coercive field. Furthermore high-temperature dielectric characteristics reveal the ferroelectric transition at around 900 K and exhibit Maxwell-Wagner type relaxation. The present work serves as a bridge between h-RMnO3 and rare earth ferrite RFeO3. It assumes significance in the light of recent research developments in hexagonal RFeO3 (mainly h-LuFeO3) in the context of room-temperature multiferroicity and magnetoelectricity.
Effect of sputtering power on crystallinity, intrinsic defects, and optical and electrical properties of Al-doped ZnO transparent conducting thin films for optoelectronic devices
Authors: Hu Yu Min , Li Jung Yu , Chen Nai Yun , Chen Chih Yu , Han Tai Chun , Yu Chin Chung
Published: March 2017

The crystallinity and intrinsic defects of transparent conducting oxide (TCO) films have a high impact on their optical and electrical properties and therefore on the performance of devices incorporating such films, including flat panel displays, electro-optical devices, and solar cells. The optical and electrical properties of TCO films can be modified by tailoring their deposition parameters, which makes proper understanding of these parameters crucial. Magnetron sputtering is the most adaptable method for preparing TCO films used in industrial applications. In this study, we investigate the direct and inter-property correlation effects of sputtering power (PW) on the crystallinity, intrinsic defects, and optical and electrical properties of Al-doped ZnO (AZO) TCO films. All of the films were preferentially c-axis-oriented with a wurtzite structure and had an average transmittance of over 80% in the visible wavelength region. Scanning electron microscopy images revealed significantly increased AZO film grain sizes for PW ≥ 150 W, which may lead to increased conductivity, carrier concentration, and optical band gaps but decreased carrier mobility and in-plane compressive stress in AZO films. Photoluminescence results showed that, with increasing PW, the near band edge emission gradually dominates the defect-related emissions in which zinc interstitial (Zni), oxygen vacancy (VO), and oxygen interstitial (Oi) are possibly responsible for emissions at 3.08, 2.8, and 2.0 eV, respectively. The presence of Zni- and Oi-related emissions at PW ≥ 150 W indicates a slight increase in the presence of Al atoms substituted at Zn sites (AlZn). The presence of Oi at PW ≥ 150 W was also confirmed by X-ray photoelectron spectroscopy results. These results clearly show that the crystallinity and intrinsic-defect type of AZO films, which dominate their optical and electrical properties, may be controlled by PW. This understanding may facilitate the development of TCO-based optoelectronic devices for industrial production.
Shock initiation of nano-Al/Teflon: High dynamic range pyrometry measurements
Authors: Wang Jue , Bassett Will P. , Dlott Dana D.
Published: March 2017

Laser-launched flyer plates (25 μm thick Cu) were used to impact-initiate reactive materials consisting of 40 nm Al particles embedded in TeflonAF polymer (Al/Teflon) on sapphire substrates at a stoichiometric concentration (2.3:1 Teflon:Al), as well as one-half and one-fourth that concentration. A high dynamic range emission spectrometer was used to time and spectrally resolve the emitted light and to determine graybody temperature histories with nanosecond time resolution. At 0.5 km s−1, first light emission was observed from Teflon, but at 0.6 km s−1, the emission from Al/Teflon became much more intense, so we assigned the impact threshold for Al/Teflon reactions to be 0.6 (±0.1) km s−1. The flyer plates produced a 7 ns duration steady shock drive. Emission from shocked Al/Teflon above threshold consisted of two bursts. At the higher impact velocities, the first burst started 15 ns after impact, peaked at 25 ns, and persisted for 75 ns. The second burst started at a few hundred nanoseconds and lasted until 2 μs. The 15 ns start time was exactly the time the flyer plate velocity dropped to zero after impact with sapphire. The first burst was associated with shock-triggered reactions and the second, occurring at ambient pressure, was associated with combustion of leftover material that did not react during shock. The emission spectrum was found to be a good fit to a graybody at all times, allowing temperature histories to be extracted. At 25 ns, the temperature at 0.7 km s−1 and the one-fourth Al load was 3800 K. Those temperatures increased significantly with impact velocity, up to 4600 K, but did not increase as much with Al load. A steady combustion process at 2800 (±100) K was observed in the microsecond range. The minimal dependence on Al loading indicates that these peak temperatures arise primarily from Al nanoparticles reacting almost independently, since the presence of nearby heat sources had little influence on the peak temperatures.
Degradation of CH3NH3PbI3 perovskite due to soft x-ray irradiation as analyzed by an x-ray photoelectron spectroscopy time-dependent measurement method
Authors: Motoki Keisuke , Miyazawa Yu , Kobayashi Daisuke , Ikegami Masashi , Miyasaka Tsutomu , Yamamoto Tomoyuki , Hirose Kazuyuki
Published: March 2017

The effects of soft X-ray exposure on structures of CH3NH3PbI3 perovskite were investigated using an X-ray photoelectron spectroscopy (XPS) time-dependent measurement method. A crystalline sample was fabricated with the inverse-temperature crystallization method. The time evolutions of the core-level and valence-band spectra were recorded to determine the compositional ratios and valence band electronic structure of the sample, respectively. In addition, first-principles calculations were conducted to evaluate the valence band XPS spectra. The in situ XPS analysis combined with theoretical calculations demonstrated a degradation of the surface of CH3NH3PbI3 perovskite into PbI2 owing to the evaporation of methylammonium iodide.
Correlated disordered electrons and organic magnetoconductance
Authors: Larabi A. , Bourbie D.
Published: March 2017

The purpose of this paper is to explore the magnetoconductance (MC) effect in an organic semiconductor. By taking into account the external magnetic field and the hyperfine interaction, we determine the magnetoconductance (MC) from a numerical solution by using a steady-state rate equation for correlated electrons in Gaussian disordered systems. The ingredient of this model is that at thermal equilibrium, the spins of the polarons relax in the same direction as the local magnetic fields. We have investigated the MC dependence of the external magnetic field, the hyperfine interaction, the carrier densities, the intra-site coulomb energy, and the applied electrical field. We show that the interplay between the Hubbard energy and the charge-carrier density leads to positive and negative magnetoconductance. The theoretical calculations are in qualitative agreement with the experimental results.
An extended study of the ignition design space of magnetized target
fusion
Authors: Lindemuth Irvin R.
Published: March 2017

The survey by Lindemuth [Phys. Plasmas 22, 122712 (2015)] of the parameter space in which magnetized targets can achieve ignition and high gain has been extended and broadened with the intent of determining, for a specified initial density and β (ratio of plasma pressure to magnetic pressure), the initial temperature and minimum initial size required to achieve ignition at reasonable convergence and to determine what are the implosion velocity and energy required to maximize gain. For three basic types of magnetized targets—spherical with azimuthal magnetic field, cylindrical with azimuthal magnetic field, and cylindrical with axial magnetic field—we find that high gain is possible only for high-β (e.g., β > 1) initial plasmas in a density range for which very little research on plasma formation has been conducted.
Design and commissioning of the RIKEN cryogenic electrostatic ring (RICE)
Authors: Nakano Y. , Enomoto Y. , Masunaga T. , Menk S. , Bertier P. , Azuma T.
Published: March 2017

A new electrostatic ion storage ring, the RIKEN cryogenic electrostatic ring, has been commissioned with a 15-keV ion beam under cryogenic conditions. The ring was designed with a closed ion beam orbit of about 2.9 m, where the ion beam is guided entirely by electrostatic components. The vacuum chamber of the ring is cooled using a liquid-He-free cooling system to 4.2 K with a temperature difference of 0.4 K at most within all the positions measured by calibrated silicon diode sensors. The first cryogenic operation with a 15-keV Ne+ beam was successfully performed in August 2014. During the measurement, the Ne+ beam was stored under a ring temperature of 4.2 K with a residual-gas lifetime of more than 10 min. This permits an estimation of the residual gas density at a few 104 cm−3, which corresponds to a room-temperature-equivalent pressure of around 1×10−10 Pa. An effect of longitudinal pulse compression at the bunching cavity in the ring was clearly identified by monitoring the pick-up beam detector. The detailed design and mechanical structure of the storage ring, as well as the results from the commissioning run, are reported.
Geometric Hamilton–Jacobi theory on Nambu–Poisson manifolds
Authors: de León M. , Sardón C.
Published: March 2017

The Hamilton–Jacobi theory is a formulation of classical mechanics equivalent to other formulations as Newtonian, Lagrangian, or Hamiltonian mechanics. The primordial observation of a geometric Hamilton–Jacobi theory is that if a Hamiltonian vector field XH can be projected into the configuration manifold by means of a 1-form dW, then the integral curves of the projected vector field XHdWcan be transformed into integral curves of XH provided that W is a solution of the Hamilton–Jacobi equation. Our aim is to derive a geometric Hamilton–Jacobi theory for physical systems that are compatible with a Nambu–Poisson structure. For it, we study Lagrangian submanifolds of a Nambu–Poisson manifold and obtain explicitly an expression for a Hamilton–Jacobi equation on such a manifold. We apply our results to two interesting examples in the physics literature: the third-order Kummer–Schwarz equations and a system of n copies of a first-order differential Riccati equation. From the first example, we retrieve the original Nambu bracket in three dimensions and from the second example, we retrieve Takhtajan’s generalization of the Nambu bracket to n dimensions.
Quantum-classical calculations of X-ray photoelectron spectra of polymers—Polymethyl methacrylate revisited
Authors: Löytynoja T. , Harczuk I. , Jänkälä K. , Vahtras O. , Ågren H.
Published: March 2017

In this work, we apply quantum mechanics/molecular mechanics (QM/MM) approach to predict core-electron binding energies and chemical shifts of polymers, obtainable via X-ray photoelectron spectroscopy (XPS), using polymethyl methacrylate as a demonstration example. The results indicate that standard parametrizations of the quantum part (basis sets, level of correlation) and the molecular mechanics parts (decomposed charges, polarizabilities, and capping technique) are sufficient for the QM/MM model to be predictive for XPS of polymers. It is found that the polymer environment produces contributions to the XPS binding energies that are close to monotonous with the number of monomer units, totally amounting to approximately an eV decrease in binding energies. In most of the cases, the order of the shifts is maintained, and even the relative size of the differential shifts is largely preserved. The coupling of the internal core-hole relaxation to the polymer environment is found to be weak in each case, amounting only to one or two tenths of an eV. The main polymeric effect is actually well estimated already at the frozen orbital level of theory, which in turn implies a substantial computational simplification. These conclusions are best represented by the cases where the ionized monomer and its immediate surrounding are treated quantum mechanically. If the QM region includes only a single monomer, a couple of anomalies are spotted, which are referred to the QM/MM interface itself and to the neglect of a possible charge transfer.
High sensitivity field asymmetric ion mobility spectrometer
Authors: Chavarria Mario A. , Matheoud Alessandro V. , Marmillod Philippe , Liu Youjiang , Kong Deyi , Brugger Jürgen , Boero Giovanni
Published: March 2017

A high sensitivity field asymmetric ion mobility spectrometer (FAIMS) was designed, fabricated, and tested. The main components of the system are a 10.6 eV UV photoionization source, an ion filter driven by a high voltage/high frequency n-MOS inverter circuit, and a low noise ion detector. The ion filter electronics are capable to generate square waveforms with peak-to-peak voltages up to 1000 V at frequencies up to 1 MHz with adjustable duty cycles. The ion detector current amplifier has a gain up to 1012 V/A with an effective equivalent input noise level down to about 1 fA/Hz1/2 during operation with the ion filter at the maximum voltage and frequency. The FAIMS system was characterized by detecting different standard chemical compounds. Additionally, we investigated the use of a synchronous modulation/demodulation technique to improve the signal-to-noise ratio in FAIMS measurements. In particular, we implemented the modulation of the compensation voltage with the synchronous demodulation of the ion current. The analysis of the measurements at low concentration levels led to an extrapolated limit of detection for acetone of 10 ppt with an averaging time of 1 s.
Three dimensional measurement with an electrically tunable focused plenoptic camera
Authors: Lei Yu , Tong Qing , Xin Zhaowei , Wei Dong , Zhang Xinyu , Liao Jing , Wang Haiwei , Xie Changsheng
Published: March 2017

A liquid crystal microlens array (LCMLA) with an arrayed microhole pattern electrode based on nematic liquid crystal materials using a fabrication method including traditional UV-photolithography and wet etching is presented. Its focusing performance is measured under different voltage signals applied between the electrodes of the LCMLA. The experimental outcome shows that the focal length of the LCMLA can be tuned easily by only changing the root mean square value of the voltage signal applied. The developed LCMLA is further integrated with a main lens and an imaging sensor to construct a LCMLA-based focused plenoptic camera (LCFPC) prototype. The focused range of the LCFPC can be shifted electrically along the optical axis of the imaging system. The principles and methods for acquiring several key parameters such as three dimensional (3D) depth, positioning, and motion expression are given. The depth resolution is discussed in detail. Experiments are carried out to obtain the static and dynamic 3D information of objects chosen.
Phthalocyanine based metal containing porous carbon sheet
Authors: Honda Z. , Sakaguchi Y. , Tashiro M. , Hagiwara M. , Kida T. , Sakai M. , Fukuda T. , Kamata N.
Published: March 2017

Highly-ordered fused-ring poly copper phthalocyanine (PCuPc) was prepared using copper octacyanophthalocyanine as a building block, and two-dimensional (2D) square superlattices were directly observed by the transmission electron microscopy. Remarkably, we have found a formation of polymer network that consists of a 2D porous PCuPc sheet in which the centers of phthalocyanine units are alternately occupied by Cu atom and vacancy. Using this “half-filling” PCuPc, it must be possible to create alternating arrangements for transition metal centers, and therefore control the magnetic properties of the 2D carbon sheets.
Detection of phase transition in polyethylene glycol using a multimodal micromechanical acoustic resonator
Authors: Prasad A. , Seshia A. A.
Published: March 2017

A piezoelectrically transduced micromechanical beam acoustic resonator is utilized to detect solid to liquid phase transitions in sub-nanoliter volume of Polyethylene Glycol (PEG) 1000. A lower frequency flexural mode and a higher frequency length-extensional mode are simultaneously monitored for changes in the device response. The phase transition of the PEG drop perturbs the acoustic loading of the resonator, bringing about characteristic and repeatable changes in the frequency response. The phase transitions in the drop are verified optically, and the resonant parameters are compared with the control case when the resonator is pristine without the presence of any PEG drop.
Black phosphorus nanodevices at terahertz frequencies: Photodetectors and future challenges
Authors: Viti Leonardo , Politano Antonio , Vitiello Miriam Serena
Published: March 2017

The discovery of graphene triggered a rapid rise of unexplored two-dimensional materials and heterostructures having optoelectronic and photonics properties that can be tailored on the nanoscale. Among these materials, black phosphorus (BP) has attracted a remarkable interest, thanks to many favorable properties, such as the high carrier mobility, the in-plane anisotropy, the possibility to alter its transport via electrical gating, and the direct band-gap, which can be tuned by thickness from 0.3 eV (bulk crystalline) to 1.7 eV (single atomic layer). When integrated in a microscopic field effect transistor, a few-layer BP flake can detect Terahertz (THz) frequency radiation. Remarkably, the in-plane crystalline anisotropy can be exploited to tailor the mechanisms that dominate the photoresponse; a BP-based field effect transistor can be engineered to act as a plasma-wave rectifier, a thermoelectric sensor, or a thermal bolometer. Here we present a review on recent research on BP detectors operating from 0.26 THz to 3.4 THz with particular emphasis on the underlying physical mechanisms and the future challenges that are yet to be addressed for making BP the active core of stable and reliable optical and electronic technologies.
Electronic band structure of the buried SiO2/SiC interface investigated by soft x-ray ARPES
Authors: Woerle J. , Bisti F. , Husanu M.-A. , Strocov V. N. , Schneider C. W. , Sigg H. , Gobrecht J. , Grossner U. , Camarda M.
Published: March 2017

The electronic structure of the SiO2/SiC (0001) interface, buried below SiO2 layers with a thickness from 2 to 4 nm, was explored using soft X-ray angle-resolved photoemission spectroscopy with photon energies between 350 and 1000 eV. The measurements have detected the characteristic k-dispersive energy bands of bulk Silicon Carbide (SiC) below the SiO2 layer without any sign of additional dispersive states, up to an estimated instrumental sensitivity of ≈5 × 109 cm2 eV. This experimental result supports the physical picture that the large density of interface traps observed in macroscopic measurements results from dangling bonds randomized by the SiO2 rather than from Shockley-Tamm surface derived states extending into the bulk SiC.
Control of circularly polarized THz wave from intrinsic Josephson junctions by local heating
Authors: Asai Hidehiro , Kawabata Shiro
Published: March 2017

This paper reports a practical method of generating circularly polarized terahertz (THz) waves from intrinsic Josephson junctions (IJJs) and controlling their polarization states by external local heating. We theoretically find that a mesa-structure IJJ whose geometry is almost square can emit circularly polarized THz waves by local heating of the mesa. Moreover, we demonstrate that the polarization states of the THz waves change dramatically with the local heating position. Our results indicate that the use of local heating can provide a high level of controllability of the THz emissions and significantly extend the range of applications of IJJ-based THz emitters.
Electric field effect of GaAs monolayer from first principles
Authors: Wu Jiongyao , Yang Yali , Gao Heng , Qi Yuting , Zhang Jiaqi , Qiao Zhenhua , Ren Wei
Published: March 2017

Using first-principle calculations, we investigate two-dimensional (2D) honeycomb monolayer structures composed of group III-V binary elements. It is found that such compound like GaAs should have a buckled structure which is more stable than graphene-like flat structure. This results a polar system with out-of-plane dipoles arising from the non-planar structure. Here, we optimized GaAs monolayer structure, then calculated the electronic band structure and the change of buckling height under external electric field within density functional theory using generalized gradient approximation method. We found that the band gap would change proportionally with the electric field magnitude. When the spin-orbit coupling (SOC) is considered, we revealed fine spin-splitting at different points in the reciprocal space. Furthermore, the valence and conduction bands spin-splitting energies due to SOC at the K point of buckled GaAs monolayers are found to be weakly dependent on the electric field strength. Finally electric field effects on the spin texture and second harmonic generation are discussed. The present work sheds light on the control of physical properties of GaAs monolayer by the applied electric field.
Genotypic water-deficit stress responses in durum wheat: association between physiological traits, microRNA regulatory modules and yield components
Authors: Liu Haipei , Able Amanda J. , Able Jason A.
Published: March 2017

In Mediterranean environments, water-deficit stress that occurs before anthesis significantly limits durum wheat (Triticum turgidum L. ssp. durum) production. Stress tolerant and stress sensitive durum varieties exhibit genotypic differences in their response to pre-anthesis water-deficit stress as reflected by yield performance, but our knowledge of the mechanisms underlying tolerance is limited. We have previously identified stress responsive durum microRNAs (miRNAs) that could contribute to water-deficit stress tolerance by mediating post-transcriptional silencing of genes that lead to stress adaptation (e.g. miR160 and its targets ARF8 (auxin response factor 8) and ARF18). However, the temporal regulation pattern of miR160-ARFs after induction of pre-anthesis water-deficit stress in sensitive and tolerant varieties remains unknown. Here, the physiological responses of four durum genotypes are described by chlorophyll content, leaf relative water content, and stomatal conductance at seven time-points during water-deficit stress from booting to anthesis. qPCR examination of miR160, ARF8 and ARF18 at these time-points revealed a complex stress responsive regulatory pattern, in the flag leaf and the head, subject to genotype. Harvest components and morphological traits measured at maturity confirmed the stress tolerance level of these four varieties for agronomic performance, and their potential association with the physiological responses. In general, the distinct regulatory pattern of miR160-ARFs among stress tolerant and sensitive durum varieties suggests that miRNA-mediated molecular pathways may contribute to the genotypic differences in the physiological traits, ultimately affecting yield components (e.g. the maintenance of harvest index and grain number).
One Thousand Years of Islamic Education in Najaf: Myth and History of the Shiʿi Ḥawza
Authors: Heern Zackery M.
Published: March 2017

According to Shiʿi tradition, the seminary (ḥawza) in Najaf, Iraq is 1,000 years old. The origins of theḥawzaare closely associated with the famous scholar Shaykh al-Ṭūsī (385/995‒459/1067). This paper addresses the question of whether or not there is sufficient historical evidence to support the tradition that theḥawzaof Najaf is indeed 1,000 years old. On the basis of Arabic sources, the article argues that although Shiʿi educational institutions in Najaf were incepted a millennium ago, Najaf was rarely the locus of Shiʿi education prior to the thirteenth/nineteenth century. Based on statistical and historical analysis of Shiʿi scholars in Najaf, this paper outlines a short history of scholarly activity in one of the oldest college towns in the world. In addition to developing a working definition of the termḥawza, the paper situates the rise of Shiʿi educational systems in the broader context of the evolution of Islamic scholarly institutions, including colleges (madrasas).
Length Limits Fail to Restructure a Largemouth Bass Population: A 28-Year Case History
Authors: Miranda L. E. , Colvin M. E. , Shamaskin A. C. , Bull L. A. , Holman T. , Jones R.
Published: March 2017

Length limits have been implemented by fisheries management agencies to achieve population density, size structure, and angler satisfaction objectives. By redirecting harvest towards or away from particular length- or age-groups, length limits rely on harvest by anglers to maintain a population at or near a desired state. The fish population changes that follow the implementation of harvest regulations may take several years to manifest, so long-term monitoring may be needed to adequately evaluate length limits. We used an innovative application of cluster analysis to facilitate evaluation of the effects of three consecutive length limits on a population of Largemouth Bass Micropterus salmoides over a 28-year period in Ross Barnett Reservoir, Mississippi. A 13–16-in protected slot length limit (10 years), followed by a 15-in minimum length limit (MLL; 11 years), followed by a 12-in MLL (7 years) failed to restructure the Largemouth Bass population due to what we suggest was the expansion of a voluntary catch-and-release attitude that started in the first decade of the study period. Various population metrics shifted towards values expected in an unharvested population, and the observed shifts can be attributed to a harvest deficit created by the prevailing catch-and-release attitude. Largemouth Bass harvest regulations may no longer be relevant in many waters. The utility of regulations for restructuring Largemouth Bass populations is largely dependent on harvesting attitudes that vary geographically, depending on cultural characteristics and demographics.

Received September 15, 2016; accepted March 15, 2017 Published online May 4, 2017
Challenges and complexity of functionality evaluation of flavan-3-ol derivatives
Authors: Saito Akiko
Published: March 2017

Flavan-3-ol derivatives are common plant-derived bioactive compounds. In particular, (–)-epigallocatechin-3-O-gallate shows various moderate biological activities without severe toxicity, and its health-promoting effects have been widely studied because it is a main ingredient in green tea and is commercially available at low cost. Although various biologically active flavan-3-ol derivatives are present as minor constituents in plants as well as in green tea, their biological activities have yet to be revealed, mainly due to their relative unavailability. Here, I outline the major factors contributing to the complexity of functionality studies of flavan-3-ol derivatives, including proanthocyanidins and oligomeric flavan-3-ols. I emphasize the importance of conducting structure-activity relationship studies using synthesized flavan-3-ol derivatives that are difficult to obtain from plant extracts in pure form to overcome this challenge. Further discovery of these minor constituents showing strong biological activities is expected to produce useful information for the development of functional health foods.
Inhibitory effects of 3α-hydroxy-lup-20(29)-en-23, 28-dioic acid on lipopolysaccharide-induced TNF-α, IL-1β, and the high mobility group box 1 release in macrophages
Authors: Liu Xiang-Qian , Zou Qin-Peng , Huang Jian-Jun , Yook Chang-Soo , Whang Wan-Kyunn , Lee Hyeong-Kyu , Kwon Ok-Kyoung
Published: March 2017

We investigated the anti-inflammatory effects of 3α-hydroxy-lup-20(29)-en-23, 28-dioic acid (HLEDA)—a lupane-type triterpene isolated from leaves of Acanthopanax gracilistylus W. W.Smith (AGS), as well as the underlying molecular mechanisms in lipopolysaccharide (LPS)-induced RAW264.7 cells. Our results demonstrated that HLEDA concentration-dependently reduced the production of nitric oxide (NO), signiﬁcantly suppressed LPS-induced expression of TNF-α and IL-1β at the mRNA and protein levels in RAW264.7 cells. Further analysis revealed that HLEDA could reduce the secretion of High Mobility Group Box 1 (HMGB1). Additionally, the results showed that HLEDA efficiently decreased nuclear factor-kappaB (NF-κB) activation by inhibiting the degradation and phosphorylation of IκBα. These results suggest that HLEDA exerts anti-inflammatory properties in LPS-induced macrophages, possibly through inhibition of the NF-κB signaling pathway, which mediates the expression of pro-inflammatory cytokines. These results warrant further studies that would concern candidate therapy for diseases, such as fulminant hepatitis and rheumatology of triterpenoids in AGS.
Material properties of the nugget zone in resistance spot-welded DP980 steel joint at various strain rates
Authors: Park Namsu , Park Moonsu , Kwon Junbeom , Huh Hoon
Published: March 2017

This paper suggests an approach to evaluate the material properties of the nugget zone in resistance spot-welded DP980 steel joints at various strain rates ranging from 0.001 to 100 s−1. Two kinds of micro-specimens are prepared for the tests: one cut from the centre of the welded nugget zone; and the other cut at 1 mm away from the welded nugget centre. Test results show that the welded nugget zone has little discrepancy in the material properties depending on sampling location and that the flow stress of the nugget zone is relatively high compared with that of the base metal at each strain rate tested. It is confirmed from microscopic observation that the differences are mainly caused by the formation of coarse martensite phase in the welded nugget zone due to the rapid cooling after the resistance spot-welding process.
HIV: Persistence through division
Authors: Cohn Lillian B. , Nussenzweig Michel C.
Published: March 2017

A long-lived latent reservoir for HIV-1 persists in CD4+ T cells despite antiretroviral therapy and is the major barrier to cure. In this issue of JEM, Hosmane et al. show that T cell proliferation could explain the long-term persistence of this reservoir.
Infinity: A Very Short Introduction
Authors: Stewart Ian
Published: March 2017

Infinity has connections to philosophy, religion, and physics as well as mathematics. The infinitely large (infinite) is intimately related to the infinitely small (infinitesimal). Infinity: A Very Short Introduction explains the mathematical concept of infinity, its different forms, and its uses in calculus, Fourier analysis, and fractals, and also describes the philosophical aspects and debates involving infinity. It argues that working with infinity is not just an abstract, intellectual exercise, but that it is instead a concept with important practical everyday applications, and considers how mathematicians use infinity and infinitesimals to answer questions or supply techniques that do not appear to involve the infinite.
Variation of Free Asparagine Concentration and Association with Quality Parameters for Hard Red Spring Wheat Grown in North Dakota
Authors: Ohm Jae‐Bom , Mergoum Mohamed , Simsek Senay
Published: March 2017

Free asparagine in wheat is known to be a precursor for the formation of acrylamide, which is unacceptable to consumers owing to its potential risks to human health. This research was performed to determine variation of free asparagine concentration (FAC) in hard red spring (HRS) wheat grown in North Dakota. Quality traits and FAC were analyzed for 75 HRS wheat genotypes grown at three locations. The ANOVA indicated that growing location had a strong effect on FAC. The main effect of genotype and interaction of genotype × location were also highly significant (P < 0.001). The genotype × location interaction was also explored graphically using a biplot of principal components calculated from the genotype and genotype × environment interaction model. The biplot analysis revealed that the pattern of interaction of genotype × location might be a noncrossover type. Certain HRS genotypes were identified to have consistently low FAC across growing locations. The FAC showed low genotypic correlations with quality traits, indicating low level of linkage between FAC and quality traits for HRS wheat genotypes.
Development and Evaluation of Near-Isogenic Lines with Different Blast Resistance Alleles at the Piz Locus in japonica Rice from the Lower Region of the Yangtze River, China
Authors: Wu Yunyu , Chen Yu , Pan Cunhong , Xiao Ning , Yu Ling , Li Yuhong , Zhang Xiaoxiang , Pan Xuebiao , Chen Xijun , Liang Chengzhi , Dai Zhengyuan , Li Aihong
Published: March 2017

Rice blast, caused by Magnaporthe oryzae, threatens rice production in most of the rice-growing areas in China, especially in regions that have grown Oryza sativa subsp. japonica in recent years. The use of resistance genes is the most effective and economical approach for blast control. In our study, a set of six near-isogenic lines (NIL) were developed by introgression of six resistance alleles of the Piz locus (Pi2, Pigm, Pi40, Pi9, Piz, and Pizt) into a blast-susceptible, high-yielding, high-quality japonica ‘07GY31’ via marker-assisted backcross breeding. Artificial inoculation using 144 M. oryzae isolates collected from the lower region of the Yangtze River, China, revealed that most of the NIL, including NIL-Pi2, NIL-Pigm, NIL-Pi40, NIL-Pi9, and NIL-Pizt, exhibited broad-spectrum resistance against rice blast at the seedling stage, with resistance frequencies (RF) of 93.06 to 98.61%. NIL-Piz was an exception, with an RF of 21.53%, which was slightly higher than the recurrent parent 07GY31. NIL-Pi40 and NIL-Pigm had broad-spectrum resistance (RF of 93.33 and 71.67%, respectively) at the heading stage following inoculation of 60 isolates of M. oryzae. Field trials with artificial inoculation at the seedling and heading stage showed that NIL-Pigm and NIL-Pi40 were highly resistant in four locations under high disease pressure. NIL-Pizt showed effective resistance in three locations from Zhejiang and Jiangsu Provinces. This study shows that O. sativa subsp. japonica alleles of the Piz locus confer resistance to M. oryzae, and provides an effective method to enhance seedling and panicle blast resistance in rice plants in the lower region of the Yangtze River, China.
Conditioning by Subthreshold Synaptic Input Changes the Intrinsic Firing Pattern of CA3 Hippocampal Neurons
Authors: Soldado-Magraner Saray , Brandalise Federico , Honnuraiah Suraj , Pfeiffer Michael , Gerber Urs , Douglas Rodney
Published: March 2017

Unlike synaptic strength, intrinsic excitability is assumed to be a stable property of neurons. For example, learning of somatic conductances is generally not incorporated into computational models, and the discharge pattern of neurons in response to test stimuli is frequently used as a basis for phenotypic classification. However, it is increasingly evident that signal processing properties of neurons are more generally plastic on the timescale of minutes. Here we demonstrate that the intrinsic firing patterns of CA3 neurons of the rat hippocampus in vitro undergo rapid long-term plasticity in response to a few minutes of only subthreshold synaptic conditioning. This plasticity on the spike-timing could also be induced by intrasomatic injection of subthreshold depolarizing pulses and was blocked by kinase inhibitors, indicating that discharge dynamics are modulated locally. Cluster analysis of firing patterns before and after conditioning revealed systematic transitions towards adapting and intrinsic burst behaviours, irrespective of the patterns initially exhibited by the cells. We used a conductance-based model to decide appropriate pharmacological blockade, and found that the observed transitions are likely due to recruitment of calcium and M-type potassium conductances. We conclude that CA3 neurons adapt their conductance profile to the subthreshold activity of their input, so that their intrinsic firing pattern is not a static signature, but rather a reflection of their history of subthreshold activity. In this way, recurrent output from CA3 neurons may collectively shape the temporal dynamics of their embedding circuits.

New & Noteworthy

Despite being widely conserved across the animal phyla, it is still a mystery why nerve cells present diverse discharge dynamics upon somatic step currents. Adding a new timing dimension to the intrinsic plasticity literature, here we show that CA3 neurons rapidly adapt through the space of known firing patterns in response to the subthreshold signals that they receive from their embedding circuit. This result implies that CA3 neurons collectively adjust their network processing to the temporal statistics of their circuit.
Machine Learning-based state-of-the-art methods for the classification of RNA-Seq data
Authors: Jabeen Almas , Ahmad Nadeem , Raza Khalid
Published: March 2017

RNA-Seq measures expression levels of several transcripts simultaneously. The identified reads can be gene, exon, or other region of interest. Various computational tools have been developed for studying pathogen or virus from RNA-Seq data by classifying them according to the attributes in several predefined classes, but still computational tools and approaches to analyze complex datasets are still lacking. The development of classification models is highly recommended for disease diagnosis and classification, disease monitoring at molecular level as well as researching for potential disease biomarkers. In this chapter, we are going to discuss various machine learning approaches for RNA-Seq data classification and their implementation. Advancements in bioinformatics, along with developments in machine learning based classification, would provide powerful toolboxes for classifying transcriptome information available through RNA-Seq data.
Demographic variability in spruce-fir-beech forest stands in Europe
Authors: Lagarrigues Guillaume , Jabot Franck , Zingg Andreas , Gégout Jean-Claude , Klopčič Matija , Courbaud Benoît
Published: March 2017

1

Many studies have predicted large changes in forest dynamics during the next century because of global warming. Although empirical approaches and studies based on species distribution models provide valuable information about future changes, they do not take into account biotic interactions and stand-level demographic variations. The objective of this study was to quantify the local and regional variability of the growth and regeneration of three important forest species growing often in mixed stands in Europe (Picea abies (L.) Karst., Abies alba Mill., Fagus sylvatica), and to assess the climatic drivers of this variability. For that purpose, we collected a large forestry data set compiling the long-term (up to 100 years) evolution of species and size distributions for 163 stands across Europe, in the mesic distribution area of these forests. We used an inverse modeling approach, Approximate Bayesian Computation, to calibrate an individual-based model of forest dynamics on these data. Our study revealed that the variability of the demographic processes was of the same order of magnitude between stands of a same forest as between different forests. Out of the three species and two demographic processes studied, only the fir growth strongly varied with temperature. Water availability did not explain any demographic variation over stands. For these forests experiencing mesic conditions, local unmeasured factors seem therefore to have an influence at least as important as macro-environmental factors on demographic variations. Efforts to include these important factors in projection scenarios should therefore be prioritized. Besides, our study demonstrates that inverse modelling methods make possible the analysis of long-term forestry data. Such data should therefore be more widely compiled and used for ecological and global change research.
A dynamic bioenergetic model for coral-Symbiodiniumsymbioses and coral bleaching as an alternate stable state
Authors: Cunning Ross , Muller Erik B. , Gates Ruth D. , Nisbet Roger M.
Published: March 2017

Coral reef ecosystems owe their ecological success–and vulnerability to climate change–to the symbiotic metabolism of corals andSymbiodiniumspp. The urgency to understand and predict the stability and breakdown of these symbioses (i.e., coral ‘bleaching’) demands the development and application of theoretical tools. Here, we develop a dynamic bioenergetic model of coral-Symbiodiniumsymbioses that demonstrates realistic steady-state patterns in coral growth and symbiont abundance across gradients of light, nutrients, and feeding. Furthermore, by including a mechanistic treatment of photo-oxidative stress, the model displays dynamics of bleaching and recovery that can be explained as transitions between alternate stable states. These dynamics reveal that ‘healthy’ and ‘bleached’ states correspond broadly to nitrogen- and carbon-limitation in the system, with transitions between them occurring as integrated responses to multiple environmental factors. Indeed, a suite of complex emergent behaviors reproduced by the model (e.g., bleaching is exacerbated by nutrients and attenuated by feeding) suggests it captures many important attributes of the system; meanwhile, its modular framework and open source R code are designed to facilitate further problem-specific development. We see significant potential for this modeling framework to generate testable hypotheses and predict integrated, mechanistic responses of corals to environmental change, with important implications for understanding the performance and maintenance of symbiotic systems.
Adjusting for principal components of molecular phenotypes induces replicating false positives
Authors: Dahl Andy , Guillemot Vincent , Mefford Joel , Aschard Hugues , Zaitlen Noah
Published: March 2017

High-throughput measurements of molecular phenotypes provide an unprecedented opportunity to model cellular processes and their impact on disease. Such highly-structured data is strongly confounded, and principal components and their variants reliably estimate latent confounders. Conditioning on PCs in downstream analyses is known to improve power and reduce multiple-testing miscalibration and is an indispensable element of thousands of published functional genomic analyses. Further clarifying this approach is of fundamental interest to the genomics and statistics communities. We uncover a novel bias induced by PC conditioning and provide an analytic, deterministic and intuitive approximation. The bias exists because PCs are, roughly, unshielded colliders on a causal path: because PCs partially incorporate a causal genotype effect on one phenotype, the genotype becomes correlated with every phenotype conditional on PCs. We empirically quantify this bias in realistic simulations. For small genetic effects, a nearly negligible bias is observed for all tested PC variants. For large genetic effects, or other differential covariates, dramatic false positives can arise. Though one PC variant (supervised SVA) largely avoids this bias, it is computationally prohibitive genome-wide; further, its immunity to this bias is novel. Our analysis informs best practices for confounder correction in genomic studies.