bluuebunny/crossref_metadata_2025 huggingface dataset:
High-resolution current sensor utilizing nanocrystalline alloy and magnetoelectric laminate composite
Authors: Zhang Jitao , Li Ping , Wen Yumei , He Wei , Yang Aichao , Lu Caijiang , Qiu Jing , Wen Jing , Yang Jin , Zhu Yong , Yu Miao
Published: November 2012

A self-powered current sensor consisting of the magnetostrictive/piezoelectric laminate composite and the high-permeability nanocrystalline alloys is presented. The induced vortex magnetic flux is concentrated and amplified by using an optimized-shape nanocrystalline alloy of FeCuNbSiB into the magnetoelectric laminate composite; this optimization allows improving the sensitivity significantly as well as increasing the saturation of the current sensor. The main advantages of this current sensor are its large dynamic range and ability to measure currents accurately. An analytical expression for the relationship between current and voltage is derived by using the magnetic circuit principle, which predicts the measured sensitivity well. The experimental results exhibit an approximately linear relationship between the electric current and the induced voltage. The dynamic range of this sensor is from 0.01 A to 150 A, and a small electric current step-change of 0.01 A can be clearly distinguished at the power-line frequency of 50 Hz. We demonstrate that the current sensor has a flat operational frequency in the range of 1 Hz–20 kHz relative to a conventional induction coil. The current sensor indicates great potentials for monitoring conditions of electrical facilities in practical applications due to the large dynamic range, linear sensitivity, wide bandwidth frequency response, and good time stability.
High-speed solution-processed organic single crystal transistors using a novel triisopropylsilylethynyl anthracene derivative
Authors: Sung Chung Dae , Kyu An Tae , Eon Park Chan , Yun Hui-Jun , Kwon Soon-Ki , Kim Yun-Hi
Published: November 2012

A high-quality organic single crystal transistor (OSCT) was fabricated via solution-processing using a novel anthracene derivative (TIPsAntNE). The OSCT fabricated on a surface-modified high-capacitance ZrOx substrate provided a transistor that operated at low voltages with a high mobility up to 4.1 cm2/Vs and negligible hysteresis (a Vth shift of <20 mV). Importantly, the TIPsAntNE OSCT functioned under a high-frequency AC signal with a gate bias as high as 30 kHz. These are crucial operational requirements for commercial applications of organic transistors. The photoresponsivity (>1 A/W) of the TIPsAntNE single crystal was high over a wide range across the visible spectrum.
Solving the vibrational Schrödinger equation using bases pruned to include strongly coupled functions and compatible quadratures
Authors: Avila Gustavo , Carrington Tucker
Published: November 2012

In this paper, we present new basis pruning schemes and compatible quadrature grids for solving the vibrational Schrödinger equation. The new basis is designed to include the product basis functions coupled by the largest terms in the potential and important for computing low-lying vibrational levels. To solve the vibrational Schrödinger equation without approximating the potential, one must use quadrature to compute potential matrix elements. For a molecule with more than five atoms, the use of iterative methods is imperative, due to the size of the basis and the quadrature grid. When using iterative methods in conjunction with quadrature, it is important to evaluate matrix-vector products by doing sums sequentially. This is only possible if both the basis and the grid have structure. Although it is designed to include only functions coupled by the largest terms in the potential, the new basis and also the quadrature for doing integrals with the basis have enough structure to make efficient matrix-vector products possible. When results obtained with a multimode approximation to the potential are accurate enough, full-dimensional quadrature is not necessary. Using the quadrature methods of this paper, we evaluate the accuracy of calculations made by making multimode approximations.
Scattering function of semiflexible polymer chains under good solvent conditions
Authors: Hsu Hsiao-Ping , Paul Wolfgang , Binder Kurt
Published: November 2012

Using the pruned-enriched Rosenbluth Monte Carlo algorithm, the scattering functions of semiflexible macromolecules in dilute solution under good solvent conditions are estimated both in d = 2 and d = 3 dimensions, considering also the effect of stretching forces. Using self-avoiding walks of up to N = 25 600 steps on the square and simple cubic lattices, variable chain stiffness is modeled by introducing an energy penalty εb for chain bending; varying qb = exp (−εb/kBT) from qb = 1 (completely flexible chains) to qb = 0.005, the persistence length can be varied over two orders of magnitude. For unstretched semiflexible chains, we test the applicability of the Kratky-Porod worm-like chain model to describe the scattering function and discuss methods for extracting persistence length estimates from scattering. While in d = 2 the direct crossover from rod-like chains to self-avoiding walks invalidates the Kratky-Porod description, it holds in d = 3 for stiff chains if the number of Kuhn segments nK does not exceed a limiting value \documentclass[12pt]{minimal}\begin{document}$n^*_K$\end{document}nK* (which depends on the persistence length). For stretched chains, the Pincus blob size enters as a further characteristic length scale. The anisotropy of the scattering is well described by the modified Debye function, if the actual observed chain extension ⟨X⟩ (end-to-end distance in the direction of the force) as well as the corresponding longitudinal and transverse linear dimensions ⟨X2⟩ − ⟨X⟩2, \documentclass[12pt]{minimal}\begin{document}$\langle R_{g,\bot }^2 \rangle$\end{document}⟨Rg,⊥2⟩ are used.
Dielectric relaxation change of water upon phase transition of a lipid bilayer probed by terahertz time domain spectroscopy
Authors: Choi Da-Hye , Son Heyjin , Jung Seonghoon , Park Jaehun , Park Woong-Yang , Kwon Oh Sang , Park Gun-Sik
Published: November 2012

We investigate the influence of the 1, 2-ditetradecanoyl-sn-glycero-3-phosphocholine lipid bilayer phases on the water reorientation dynamics with terahertz time domain spectroscopy. The phase of the lipids was controlled by the temperature in the range of 14–35 °C. During the gel-to-fluid phase transition, the hydration water ratio drastically changed from 0.3 to 0.6. The absorption coefficient of the hydration water increased with the temperature in the gel phase and then decreased in the fluid phase. The dielectric relaxation time of the lipid solution decreased initially but then increased after the phase transition. This indicates that the hydration water reorientation dynamics are restricted by lipids and that this phenomenon is pronounced in a biologically relevant fluid phase.
Time-dependent current-voltage characteristics of Al/p-CdTe/Pt x-ray detectors
Authors: Principato F. , Gerardi G. , Turturici A. A. , Abbene L.
Published: November 2012

Current-voltage (I-V) characteristics of Schottky Al/p-CdTe/Pt detectors were investigated in dark and at different temperatures. CdTe detectors with Al rectifying contacts, very appealing for high resolution x-ray and gamma ray spectroscopy, suffer from bias-induced polarization phenomena which cause current increasing with the time and severe worsening of the spectroscopic performance. In this work, we studied the time-dependence of the I-V characteristics of the detectors, both in reverse and forward bias, taking into account the polarization effects. The I-V measurements, performed at different time intervals between the application of the bias voltage and the measurement of the current, and the measured current transients show as the electrical instability manifests itself even in time intervals shorter (i.e., <1 s) than those are necessary to make evident the degradation of the spectroscopic properties. The results point out as this time interval is a critical parameter for correct investigations on the electrical properties of these devices. Although the detectors are typically classified as Schottky-type detectors, we find that the thermionic emission is not the dominant transport mechanism, except at very low bias voltage values. Finally, the Schottky barrier height of the Al/p-CdTe contact was extracted by measuring the contact resistance at zero bias.
Conductivity in disordered structures: Verification of the generalized Jonscher's law on experimental data
Authors: Popov I. I. , Nigmatullin R. R. , Khamzin A. A. , Lounev I. V.
Published: November 2012

The generalized Jonscher's law for complex conductivity (derived earlier) is tested on available experimental data. We suggest some criteria, which are used for verification of the analytical expression describing the data related to complex conductivity. It is shown that the generalized Jonscher's law is suitable for description of the electrode polarization phenomenon.
Electrical excitation and detection of magnetic dynamics with impedance matching
Authors: Fang D. , Skinner T. D. , Kurebayashi H. , Campion R. P. , Gallagher B. L. , Ferguson A. J.
Published: November 2012

Motivated by the prospects of increased measurement bandwidth, improved signal to noise ratio, and access to the full complex magnetic susceptibility we develop a technique to extract microwave voltages from our high resistance (∼10kΩ) (Ga,Mn)As microbars. We drive magnetization precession with microwave frequency current, using a mechanism that relies on the spin orbit interaction. A capacitively coupled λ/2 microstrip resonator is employed as an impedance matching network, enabling us to measure the microwave voltage generated during magnetisation precession.
A suspended nanogap formed by field-induced atomically sharp tips
Authors: Hyun Han Jun , Song Kyung , Radhakrishnan Shankar , Ho Oh Sang , Hoon Lee Chung
Published: November 2012

A sub-nanometer scale suspended gap (nanogap) defined by electric field-induced atomically sharp metallic tips is presented. A strong local electric field (>109 V/m) across micro/nanomachined tips facing each other causes the metal ion migration in the form of dendrite-like growth at the cathode. The nanogap is fully isolated from the substrate eliminating growth mechanisms that involve substrate interactions. The proposed mechanism of ion transportation is verified using real-time imaging of the metal ion transportation using an in situ biasing in transmission electron microscope (TEM). The configuration of the micro/nanomachined suspended tips allows nanostructure growth of a wide variety of materials including metals, metal-oxides, and polymers.
Integrability of the modified generalised Vakhnenko equation
Authors: Wang Yunhu , Chen Yong
Published: November 2012

Integrability of the modified generalised Vakhnenko equation is investigated systematically. Based on binary Bell polynomials, its bilinear representation, N soliton solutions, bilinear Bäcklund transformation, and Lax pair are succinctly constructed. Moreover, the conservation laws of the modified generalised Vakhnenko equation are discussed by using corresponding Lax pair. Furthermore, the quasiperiodic solution of the modified generalised Vakhnenko equation is presented by applying Hirota direct method and Riemann theta function. The asymptotic behavior of the one periodic wave is analyzed in details. It is shown that the one periodic wave solution tends to the one soliton solution under a small amplitude limit λ → 0. Finally, the new N soliton solutions of the standard Vakhnenko equation are presented. It would be specially mentioned that all the results of modified generalised Vakhnenko equation can be reduced to the generalised Vakhnenko equation and standard Vakhnenko equation under the special case of α = 1 and α = 1, β = 0, respectively.
Phase diagram of the modified Lennard-Jones system
Authors: Asano Yuta , Fuchizaki Kazuhiro
Published: November 2012

An investigation of the precise determination of melting temperature in the modified Lennard-Jones system under pressure-free conditions [Y. Asano and K. Fuchizaki, J. Phys. Soc. Jpn. 78, 055002 (2009)10.1143/JPSJ.78.055002] was extended under finite-pressure conditions to obtain the phase diagram. The temperature and pressure of the triple point were estimated to be 0.61 ε/kB and 0.0018(5) ε/σ3, and those of the critical point were 1.0709(19) ε/kB and 0.1228(20) ε/σ3, where ε and σ are the Lennard-Jones parameters for energy and length scales, respectively, and kB is the Boltzmann constant. The potential used here has a finite attractive tail and does not suffer from cutoff problems. The potential can thus be a useful standard in examining statistical–mechanical problems in which different treatments for the tail would lead to different conclusions. The present phase diagram will then be a useful guide not only for equilibrium calculations but also for nonequilibrium problems such as discussions of the limits of phase (in)stability.
Effect of interface energy on effective dynamic properties of piezoelectric medium with randomly distributed piezoelectric nano-fibers
Authors: Fang Xue-Qian , Liu Jin-Xi , Huang Ming-Juan
Published: November 2012

In the framework of coupling surface/interface theory, a self-consistent scheme of effective field method is proposed to solve the dynamic electro-elastic properties of piezoelectric nanocomposites. The piezoelectric matrix with randomly distributed piezoelectric nano-fibers is reduced to the problem of an effective piezoelectric medium with a typical piezoelectric nano-fiber. The effective wave number and piezoelectrically stiffened elastic modulus are obtained on the basis of the derived imperfect interface conditions around the piezoelectric nano-fiber. Analyses show that the energy at the surface/interface shows significant effect on the dynamic electro-elastic properties, and the effect under different incident frequencies is discussed in details.
Role of measurement voltage on hysteresis loop shape in Piezoresponse Force Microscopy
Authors: Strelcov E. , Kim Y. , Yang J. C. , Chu Y. H. , Yu P. , Lu X. , Jesse S. , Kalinin S. V.
Published: November 2012

The dependence of field-on and field-off hysteresis loop shape in Piezoresponse Force Microscopy (PFM) on driving voltage, Vac, is explored. A nontrivial dependence of hysteresis loop parameters on measurement conditions is observed. The strategies to distinguish between paraelectric and ferroelectric states with small coercive bias and separate reversible hysteretic and non-hysteretic behaviors are suggested. Generally, measurement of loop evolution with Vac is a necessary step to establish the veracity of PFM hysteresis measurements.
Excitonic luminescence in two-dimensionally confined layered sulfide oxides
Authors: Ogino Hiraku , Shimoyama Jun-ichi , Kishio Kohji , Katsura Yukari , Tsuboi Mizuki , Yamanoi Kohei , Cadatal-Raduban Marilou , Nakazato Tomoharu , Shimizu Toshihiko , Sarukura Nobuhiko
Published: November 2012

A layered sulfide oxide, Sr2ScCuSO3, is synthesized and its electronic structure and luminescence properties are investigated. Sr2ScCuSO3 is composed of alternating layers of antifluoride type sulfide and perovskite-like oxide. Electronic structure calculations reveal that Sr2ScCuSO3 is a direct band gap semiconductor with a relatively large band gap. Excitonic luminescence was observed from Sr2ScCuSO3 and Sr3Sc2Cu2S2O5. The temperature stability of the luminescence intensity of Sr2ScCuSO3 was higher than that of Sr3Sc2Cu2S2O5. Control of the crystal structure might allow the excitonic luminescence properties of such two-dimensional compounds to be enhanced.
Enhanced thermoelectric properties of bulk TiNiSn via formation of a TiNi2Sn second phase
Authors: Douglas Jason E. , Birkel Christina S. , Miao Mao-Sheng , Torbet Chris J. , Stucky Galen D. , Pollock Tresa M. , Seshadri Ram
Published: November 2012

The effect of phase-segregated Heusler TiNi2Sn on high temperature thermoelectric properties of bulk half-Heusler TiNiSn has been studied. In samples expressed by the composition TiNi1+xSn, a significant decrease in thermal conductivity (between 10% and 30%) is observed for two-phase TiNi1.15Sn, despite the second-phase particles existing at the micrometer scale; a 50% increase in the electrical conductivity is also measured. These result in a maximum figure of merit, ZT, of 0.44 at 800 K, which is 25% greater than is observed for the x = 0 sample. Density functional calculations of TiNiSn and TiNi2Sn suggest that the latter should deplete carriers at 0 K.
Charging of nanostructured and partially reduced graphene oxide sheets
Authors: Shen Yue , Guo Shouwu , Hu Jun , Zhang Yi
Published: November 2012

We report on the charging of individual graphene oxide (GO) sheets with varied degrees of reduction by using electrically biased atomic force microscope (AFM) tips. AFM measurements indicate that the apparent height of reduced GO (rGO) sheets increases sharply after charging, while the charging ability is enhanced when the GO sheets are deeply reduced. In addition, the rGO sheets tend to be extracted with electrons (or to be injected with holes) with a positively biased AFM tip, in contrast to that with a negatively biased tip. Charging on isolated areas with tunable shape and size on single-layered GO has also been achieved.
Direct probing of density of states of reduced graphene oxides in a wide voltage range by tunneling junction
Authors: Wang Sheng-Tsung , Lin Yen-Fu , Li Ya-Chi , Yeh Pei-Ching , Tang Shiow-Jing , Rosenstein Baruch , Hsu Tai-Hsin , Zhou Xufeng , Liu Zhaoping , Lin Minn-Tsong , Jian Wen-Bin
Published: November 2012

Reduced graphene oxide (rGO) sheets are synthesized and tunneling junction devices are fabricated with an aluminum oxide layer inserted in between electrodes and rGO sheets. Differential conductances, revealing density of states (DOS), of rGO sheets are measured in a wide voltage range. A difference in DOS of rGO sheets with different thickness is identified. For the single-layer rGO, the DOS shows a whole band with band edges in line with theoretical predictions, and gating DOS is used to estimate electron's Fermi velocity. Disorder effects on conductance and DOS of rGO sheets are explored and compared with each other.
Bound and anti-bound biexciton in site-controlled pyramidal GaInAs/GaAs quantum dots
Authors: Jarlov C. , Gallo P. , Calic M. , Dwir B. , Rudra A. , Kapon E.
Published: November 2012

We present a detailed study of biexciton complexes formed in single, site-controlled pyramidal GaInAs/GaAs quantum dots (QDs). By using power dependent measurements and photon correlation spectroscopy, we identify the excitonic transitions of a large number of pyramidal QDs, exhibiting both positive and negative biexciton binding energies. Separation of charges within the QD, caused by piezoelectric fields, is believed to be responsible for the positive to negative crossover of the biexciton binding energy with increasing QD size. In particular, QDs exhibiting vanishing biexciton binding energies are evidenced, with potential applications in quantum information processing.
Self-aligned graphene field-effect transistors with polyethyleneimine doped source/drain access regions
Authors: Movva Hema C. P. , Ramón Michael E. , Corbet Chris M. , Sonde Sushant , Fahad Chowdhury Sk. , Carpenter Gary , Tutuc Emanuel , Banerjee Sanjay K.
Published: November 2012

We report a method of fabricating self-aligned, top-gated graphene field-effect transistors (GFETs) employing polyethyleneimine spin-on-doped source/drain access regions, resulting in a 2X reduction of access resistance and a 2.5X improvement in device electrical characteristics, over undoped devices. The GFETs on Si/SiO2 substrates have high carrier mobilities of up to 6300 cm2/Vs. Self-aligned spin-on-doping is applicable to GFETs on arbitrary substrates, as demonstrated by a 3X enhancement in performance for GFETs on insulating quartz substrates, which are better suited for radio frequency applications.
The role of cesium carbonate on the electron injection and transport enhancement in organic layer by admittance spectroscopy
Authors: Zhao Jin , Cai Yong , Yang Jin-Peng , Wei Huai-Xin , Deng Yan-Hong , Li Yan-Qing , Lee Shuit-Tong , Tang Jian-Xin
Published: November 2012

The effect of cesium carbonate (Cs2CO3) doping on the electron transport properties of 4,7-diphenyl-1, 10-phenanthroline (BPhen) layer has been investigated in organic light-emitting diodes (OLEDs). Temperature-dependent admittance spectroscopy studies show that the incorporation of Cs2CO3 from 0 to 42 wt. % can decrease the activation energy of the BPhen layer from 1.3 to 0.18 eV, resulting in the enhanced electron injection and transport with respect to reduced injection barrier and increased conductivity of the BPhen layer. This is consistent with the performance improvement in OLEDs, which yields better electrical characteristics and enhanced luminance efficiency.
The improved imprint effect in poly(vinylidene fluoride-trifluoroethylene) copolymer ultrathin films
Authors: Hou Ying , Lü Zhaoyue , Zhang Yuan , Xu Guoqiang , Xu Haisheng
Published: November 2012

The imprint behaviors for poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer ultrathin films with electroactive interlayers have been studied. The different electroactive polymers are used as the interlayer between P(VDF-TrFE) and metal electrodes. It is found that the smaller voltage shift is observed for the samples with electroactive interlayers and the imprint properties are improved substantially after the electroactive interlayers are introduced. The charge trap accumulation in P(VDF-TrFE) films without and with interlayers is analyzed and it is thought that the traps would be partially compensated by the free charges from the electroactive interlayers, illustrating the importance of the appropriate interlayer materials.
Enhanced broadband emission from Er-Tm codoped ZnO film due to energy transfer processes involving Si nanocrystals
Authors: Pu Yu , Xu Fei , Jiang Zuimin , Ma Zhongquan , Lu Fang , Chen Dandan
Published: November 2012

Er-Tm-Si codoped ZnO film was synthesized by co-sputtering, in which Si nanocrystals (Si-NCs) were observed to form by annealing at 1173 K for 30 min. A fairly flat emission with ∼375 nm bandwidth is achieved, and its intensity is enhanced by nearly an order of magnitude by the Si-NCs, which acted as broadband sensitizers, compared with that without Si-NCs. The film also exhibits broadband emission with relatively stable spectral shape under different excitation lines. The 1.80 μm emission intensity increases by a factor of 3 while the 1.53 μm emission is almost constant with decreasing the operating temperature from 300 to 20 K, attributed to competition between three energy transfer processes from Si-NCs to Er3+/Tm3+ and from Er3+ to Tm3+, and their back transfer processes.
Spin torque due to non-uniform Rashba spin orbit effect
Authors: Chen Ji , Jalil Mansoor Bin Abdul , Tan Seng Ghee
Published: November 2012

Following the early theoretical descriptions of the spin-orbit-induced spin torque [S. G. Tan et al., arXiv:0705.3502 (2007); S. G. Tan et al., Ann. Phys. 326, 207 (2011)]10.1016/j.aop.2010.11.014, the first experimental observation of such effect was reported by L. M. Miron et al., Nature Mater 9, 230 (2010). We present in this article three additional spin torque terms that arise from the non-uniformity in magnetization space of the Rashba spin-orbit effect. We propose a simple Rashba gradient device consisting of a heterogeneous trilayer structure, which could potentially lower switching current by n orders of magnitude, where n = −log10(|ΔM|/|M|) is a measure of the magnetization change across the device.
Genomic regions for canopy temperature and their genetic association with stomatal conductance and grain yield in wheat
Authors: Rebetzke Greg J. , Rattey Allan R. , Farquhar Graham D. , Richards Richard A. , Condon Anthony (Tony) G.
Published: November 2012

Stomata are the site of CO2 exchange for water in a leaf. Variation in stomatal control offers promise in genetic improvement of transpiration and photosynthetic rates to improve wheat performance. However, techniques for estimating stomatal conductance (SC) are slow, limiting potential for efficient measurement and genetic modification of this trait. Genotypic variation in canopy temperature (CT) and leaf porosity (LP), as surrogates for SC, were assessed in three wheat mapping populations grown under well-watered conditions. The range and resulting genetic variance were large but not always repeatable across days and years for CT and LP alike. Leaf-to-leaf variation was large for LP, reducing heritability to near zero on a single-leaf basis. Replication across dates and years increased line-mean heritability to ~75% for both CT and LP. Across sampling dates and populations, CT showed a large, additive genetic correlation with LP (rg = –0.67 to –0.83) as expected. Genetic increases in pre-flowering CT were associated with reduced final plant height and both increased harvest index and grain yield but were uncorrelated with aerial biomass. In contrast, post-flowering, cooler canopies were associated with greater aerial biomass and increased grain number and yield. A multi-environment QTL analysis identified up to 16 and 15 genomic regions for CT and LP, respectively, across all three populations. Several of the LP and CT QTL co-located with known QTL for plant height and phenological development and intervals for many of the CT and LP quantitative trait loci (QTL) overlapped, supporting a common genetic basis for the two traits. Notably, both Rht-B1b and Rht-D1b dwarfing alleles were paradoxically positive for LP and CT (i.e. semi-dwarfs had higher stomatal conductance but warmer canopies) highlighting the issue of translation from leaf to canopy in screening for greater transpiration. The strong requirement for repeated assessment of SC suggests the more rapid CT assessment may be of greater value for indirect screening of high or low SC among large numbers of early-generation breeding lines. However, account must be taken of variation in development and canopy architecture when interpreting performance and selecting breeding lines on the basis of CT.
Cripto regulates skeletal muscle regeneration and modulates satellite cell determination by antagonizing myostatin
Authors: Guardiola Ombretta , Lafuste Peggy , Brunelli Silvia , Iaconis Salvatore , Touvier Thierry , Mourikis Philippos , De Bock Katrien , Lonardo Enza , Andolfi Gennaro , Bouché Ann , Liguori Giovanna L. , Shen Michael M. , Tajbakhsh Shahragim , Cossu Giulio , Carmeliet Peter , Minchiotti Gabriella
Published: November 2012

Skeletal muscle regeneration mainly depends on satellite cells, a population of resident muscle stem cells. However, our understanding of the molecular mechanisms underlying satellite cell activation is still largely undefined. Here, we show that Cripto, a regulator of early embryogenesis, is a novel regulator of muscle regeneration and satellite cell progression toward the myogenic lineage. Conditional inactivation of
cripto
in adult satellite cells compromises skeletal muscle regeneration, whereas gain of function of Cripto accelerates regeneration, leading to muscle hypertrophy. Moreover, we provide evidence that Cripto modulates myogenic cell determination and promotes proliferation by antagonizing the TGF-β ligand myostatin. Our data provide unique insights into the molecular and cellular basis of Cripto activity in skeletal muscle regeneration and raise previously undescribed implications for stem cell biology and regenerative medicine.
Deep-sea record of impact apparently unrelated to mass extinction in the Late Triassic
Authors: Onoue Tetsuji , Sato Honami , Nakamura Tomoki , Noguchi Takaaki , Hidaka Yoshihiro , Shirai Naoki , Ebihara Mitsuru , Osawa Takahito , Hatsukawa Yuichi , Toh Yosuke , Koizumi Mitsuo , Harada Hideo , Orchard Michael J. , Nedachi Munetomo
Published: November 2012

The 34-million-year (My) interval of the Late Triassic is marked by the formation of several large impact structures on Earth. Late Triassic impact events have been considered a factor in biotic extinction events in the Late Triassic (e.g., end-Triassic extinction event), but this scenario remains controversial because of a lack of stratigraphic records of ejecta deposits. Here, we report evidence for an impact event (platinum group elements anomaly with nickel-rich magnetite and microspherules) from the middle Norian (Upper Triassic) deep-sea sediment in Japan. This includes anomalously high abundances of iridium, up to 41.5 parts per billion (ppb), in the ejecta deposit, which suggests that the iridium-enriched ejecta layers of the Late Triassic may be found on a global scale. The ejecta deposit is constrained by microfossils that suggest correlation with the 215.5-Mya, 100-km-wide Manicouagan impact crater in Canada. Our analysis of radiolarians shows no evidence of a mass extinction event across the impact event horizon, and no contemporaneous faunal turnover is seen in other marine planktons. However, such an event has been reported among marine faunas and terrestrial tetrapods and floras in North America. We, therefore, suggest that the Manicouagan impact triggered the extinction of terrestrial and marine organisms near the impact site but not within the pelagic marine realm.
Biogenic membranes of the chloroplast in
Chlamydomonas reinhardtii
Authors: Schottkowski Marco , Peters Matthew , Zhan Yu , Rifai Oussama , Zhang Ying , Zerges William
Published: November 2012

The polypeptide subunits of the photosynthetic electron transport complexes in plants and algae are encoded by two genomes. Nuclear genome-encoded subunits are synthesized in the cytoplasm by 80S ribosomes, imported across the chloroplast envelope, and assembled with the subunits that are encoded by the plastid genome. Plastid genome-encoded subunits are synthesized by 70S chloroplast ribosomes directly into membranes that are widely believed to belong to the photosynthetic thylakoid vesicles. However, in situ evidence suggested that subunits of photosystem II are synthesized in specific regions within the chloroplast and cytoplasm of
Chlamydomonas
. Our results provide biochemical and in situ evidence of biogenic membranes that are localized to these translation zones. A “chloroplast translation membrane” is bound by the translation machinery and appears to be privileged for the synthesis of polypeptides encoded by the plastid genome. Membrane domains of the chloroplast envelope are located adjacent to the cytoplasmic translation zone and enriched in the translocons of the outer and inner chloroplast envelope membranes protein import complexes, suggesting a coordination of protein synthesis and import. Our findings contribute to a current realization that biogenic processes are compartmentalized within organelles and bacteria.
Background-dependent effects of polyglutamine variation in the
Arabidopsis thaliana
gene
ELF3
Authors: Undurraga Soledad Francisca , Press Maximilian Oliver , Legendre Matthieu , Bujdoso Nora , Bale Jacob , Wang Hui , Davis Seth J. , Verstrepen Kevin J. , Queitsch Christine
Published: November 2012

Tandem repeats (TRs) have extremely high mutation rates and are often considered to be neutrally evolving DNA. However, in coding regions, TR copy number mutations can significantly affect phenotype and may facilitate rapid adaptation to new environments. In several human genes, TR copy number mutations that expand polyglutamine (polyQ) tracts beyond a certain threshold cause incurable neurodegenerative diseases. PolyQ-containing proteins exist at a considerable frequency in eukaryotes, yet the phenotypic consequences of natural variation in polyQ tracts that are not associated with disease remain largely unknown. Here, we use
Arabidopsis thaliana
to dissect the phenotypic consequences of natural variation in the polyQ tract encoded by
EARLY FLOWERING 3
(
ELF3
), a key developmental gene. Changing ELF3 polyQ tract length affected complex ELF3-dependent phenotypes in a striking and nonlinear manner. Some natural
ELF3
polyQ variants phenocopied
elf3
loss-of-function mutants in a common reference background, although they are functional in their native genetic backgrounds. To test the existence of background-specific modifiers, we compared the phenotypic effects of
ELF3
polyQ variants between two divergent backgrounds, Col and Ws, and found dramatic differences. In fact, the Col-
ELF3
allele, encoding the shortest known ELF3 polyQ tract, was haploinsufficient in Ws × Col F
1
hybrids. Our data support a model in which variable polyQ tracts drive adaptation to internal genetic environments.
RNA-seq pinpoints a
Xanthomonas
TAL-effector activated resistance gene in a large-crop genome
Authors: Strauß Tina , van Poecke Remco M. P. , Strauß Annett , Römer Patrick , Minsavage Gerald V. , Singh Sylvia , Wolf Christina , Strauß Axel , Kim Seungill , Lee Hyun-Ah , Yeom Seon-In , Parniske Martin , Stall Robert E. , Jones Jeffrey B. , Choi Doil , Prins Marcel , Lahaye Thomas
Published: November 2012

Transcription activator-like effector (TALE) proteins of the plant pathogenic bacterial genus
Xanthomonas
bind to and transcriptionally activate host susceptibility genes, promoting disease. Plant immune systems have taken advantage of this mechanism by evolving TALE binding sites upstream of resistance (
R
) genes. For example, the pepper
Bs3
and rice
Xa27
genes are hypersensitive reaction plant
R
genes that are transcriptionally activated by corresponding TALEs. Both
R
genes have a hallmark expression pattern in which their transcripts are detectable only in the presence and not the absence of the corresponding TALE. By transcriptome profiling using next-generation sequencing (RNA-seq), we tested whether we could avoid laborious positional cloning for the isolation of TALE-induced
R
genes. In a proof-of-principle experiment, RNA-seq was used to identify a candidate for
Bs4C
, an
R
gene from pepper that mediates recognition of the
Xanthomonas
TALE protein AvrBs4. We identified one major
Bs4C
candidate transcript by RNA-seq that was expressed exclusively in the presence of AvrBs4. Complementation studies confirmed that the candidate corresponds to the
Bs4C
gene and that an AvrBs4 binding site in the
Bs4C
promoter directs its transcriptional activation. Comparison of
Bs4C
with a nonfunctional allele that is unable to recognize AvrBs4 revealed a 2-bp polymorphism within the TALE binding site of the
Bs4C
promoter.
Bs4C
encodes a structurally unique R protein and
Bs4C
-like genes that are present in many solanaceous genomes seem to be as tightly regulated as pepper
Bs4C
. These findings demonstrate that TALE-specific
R
genes can be cloned from large-genome crops with a highly efficient RNA-seq approach.
Estimating divergence times in large molecular phylogenies
Authors: Tamura Koichiro , Battistuzzi Fabia Ursula , Billing-Ross Paul , Murillo Oscar , Filipski Alan , Kumar Sudhir
Published: November 2012

Molecular dating of species divergences has become an important means to add a temporal dimension to the Tree of Life. Increasingly larger datasets encompassing greater taxonomic diversity are becoming available to generate molecular timetrees by using sophisticated methods that model rate variation among lineages. However, the practical application of these methods is challenging because of the exorbitant calculation times required by current methods for contemporary data sizes, the difficulty in correctly modeling the rate heterogeneity in highly diverse taxonomic groups, and the lack of reliable clock calibrations and their uncertainty distributions for most groups of species. Here, we present a method that estimates relative times of divergences for all branching points (nodes) in very large phylogenetic trees without assuming a specific model for lineage rate variation or specifying any clock calibrations. The method (RelTime) performed better than existing methods when applied to very large computer simulated datasets where evolutionary rates were varied extensively among lineages by following autocorrelated and uncorrelated models. On average, RelTime completed calculations 1,000 times faster than the fastest Bayesian method, with even greater speed difference for larger number of sequences. This speed and accuracy will enable molecular dating analysis of very large datasets. Relative time estimates will be useful for determining the relative ordering and spacing of speciation events, identifying lineages with significantly slower or faster evolutionary rates, diagnosing the effect of selected calibrations on absolute divergence times, and estimating absolute times of divergence when highly reliable calibration points are available.
CTR1 phosphorylates the central regulator EIN2 to control ethylene hormone signaling from the ER membrane to the nucleus in
Arabidopsis
Authors: Ju Chuanli , Yoon Gyeong Mee , Shemansky Jennifer Marie , Lin David Y. , Ying Z. Irene , Chang Jianhong , Garrett Wesley M. , Kessenbrock Mareike , Groth Georg , Tucker Mark L. , Cooper Bret , Kieber Joseph J. , Chang Caren
Published: November 2012

The gaseous phytohormone ethylene C
2
H
4
mediates numerous aspects of growth and development. Genetic analysis has identified a number of critical elements in ethylene signaling, but how these elements interact biochemically to transduce the signal from the ethylene receptor complex at the endoplasmic reticulum (ER) membrane to transcription factors in the nucleus is unknown. To close this gap in our understanding of the ethylene signaling pathway, the challenge has been to identify the target of the CONSTITUTIVE TRIPLE RESPONSE1 (CTR1) Raf-like protein kinase, as well as the molecular events surrounding ETHYLENE-INSENSITIVE2 (EIN2), an ER membrane-localized Nramp homolog that positively regulates ethylene responses. Here we demonstrate that CTR1 interacts with and directly phosphorylates the cytosolic C-terminal domain of EIN2. Mutations that block the EIN2 phosphorylation sites result in constitutive nuclear localization of the EIN2 C terminus, concomitant with constitutive activation of ethylene responses in
Arabidopsis
. Our results suggest that phosphorylation of EIN2 by CTR1 prevents EIN2 from signaling in the absence of ethylene, whereas inhibition of CTR1 upon ethylene perception is a signal for cleavage and nuclear localization of the EIN2 C terminus, allowing the ethylene signal to reach the downstream transcription factors. These findings significantly advance our understanding of the mechanisms underlying ethylene signal transduction.
Sensitivity of human lung adenocarcinoma cell lines to targeted inhibition of BET epigenetic signaling proteins
Authors: Lockwood William W. , Zejnullahu Kreshnik , Bradner James E. , Varmus Harold
Published: November 2012

Bromodomain and extra terminal domain (BET) proteins function as epigenetic signaling factors that associate with acetylated histones and facilitate transcription of target genes. Inhibitors targeting the activity of BET proteins have shown potent antiproliferative effects in hematological cancers through the suppression of
c
-MYC
and downstream target genes. However, as the epigenetic landscape of a cell varies drastically depending on lineage, transcriptional coactivators such as BETs would be expected to have different targets in cancers derived from different cells of origin, and this may influence the activity and mechanism of action of BET inhibitors. To test this hypothesis, we treated a panel of lung adenocarcinoma (LAC) cell lines with the BET inhibitor JQ1 and found that a subset is acutely susceptible to BET inhibition. In contrast to blood tumors, we show that LAC cells are inhibited by JQ1 through a mechanism independent of
c-MYC
down-regulation. Through gene expression profiling, we discovered that the oncogenic transcription factor FOSL1 and its targets are suppressed by JQ1 in a dose-dependant manner. Knockdown of BRD4 also decreased FOSL1 levels, and inhibition of FOSL1 phenocopied the effects of JQ1 treatment, suggesting that loss of this transcription factor may be partly responsible for the cytotoxic effects of BET inhibition in LAC cells, although ectopic expression of FOSL1 alone did not rescue the phenotype. Together, these findings suggest that BET inhibitors may be useful in solid tumors and that cell-lineage–specific differences in transcriptional targets of BETs may influence the activity of inhibitors of these proteins in different cancer types.
The rhetorical relations in complex sentences with quando (‘when’) in European Portuguese
Authors: Silvano Purificação
Published: November 2012

In this paper we investigate the temporal and rhetorical relations in complex sentences with clauses introduced by quando ‘when’ in European Portuguese. We put forward a proposal for a semantic treatment within a theoretical framework which is grounded in Segmented Discourse Representation Theory (SDRT; Asher and Lascarides 2003), with some extra stipulations to deal with specificities of complex sentences related to: (i) the directionality of rhetorical and temporal relations; (ii) the fronted or final position of the adverbial clause and its implications for text-structuring rhetorical relations. We show that the directionality of both the temporal and rhetorical relations is from the main situation to the subordinate situation, regardless of the order of the discourse. We argue that each complex sentence with a clause introduced by quando describes situations that are connected by rhetorical relations at two distinct levels: at the level of content and at the level of text-structuring. At the level of content, we resort to SDRT’s list of rhetorical relations. As for the text-structuring relations, we propose two new relations: Frame and Specification. Finally, we compare the complex sentences with their non-complex counterparts to demonstrate that the rhetorical mechanisms used in both types of discourse are not always the same. To sum up, the investigation carried out allows us to conclude that an analysis which takes into account the temporal and rhetorical relations leads to a better semantic and discursive understanding of complex sentences with clauses introduced by quando.
Adverbials in German
Authors: Ludwig Rainer , Salfner Fabienne , Schenner Mathias
Published: November 2012

Adverbials are well-known to form a rather heterogeneous class in multiple respects. Here we examine their ability to bear focus and their ability to be embedded in subordinate sentences. For focusability, the distinction between informational focus and contrastive focus proves to play a role. We discern six main classes of adverbials, identified by their base position. As expected, not all classes (or subclasses) can bear (informational or contrastive) focus, and also not all (sub)classes can be embedded. Among those that can, it is still only a proper subset that may simultaneously be embedded and focused. A general finding is that the lower in the syntactic tree an adverbial is base-generated, the more likely it allows for focusing as well as for embedding. The distinction between proposition-internal and proposition-external adverbs is shown to be helpful in determining which adverbials may bear (informational) focus. Also certain extrinsic factors like the type of the embedding verb or the general context are discussed that influence focusability and/or embeddability. An analysis is given in presuppositional discourse representation theory that can account for our observations.
Emergent correlative concessivity
Authors: Leuschner Torsten , Van den Nest Daan
Published: November 2012

While concessives are well-known for their special semantic characteristics, most research has so far been oriented towards hypotactic construction types (although etc.). The present article seeks to complement this trend by investigating the paratactic zwar … aber-construction in German (roughly equivalent to English ‘true … but’), with a special focus on its patterns of variation. The aim is to document important aspects of this variation from a combined qualitative/quantitative perspective. The basic thesis is that zwar … aber constitutes the core instantiation of an emergent constructional schema zwar … aber whose surface variation is structured in a prototype-like fashion. Several functional regularities and statistical correlations are analysed and discussed from the point of view of grammaticalisation theory. The data consist of ca. 10,000 parsed tokens of zwar, mainly from newspaper usage, in the Deutsches Referenzkorpus (DeReKo).
Language management in intercultural business networks
Authors: Marriott Helen
Published: November 2012

This paper deals with language management within a transnational business network, with a specific focus on the process of noting. In an analysis of one business encounter involving one Japanese and one Australian business representative, language management is found to occur at the grammatical, (non-grammatical) communicative and also sociocultural/socioeconomic levels. Furthermore, the language management involves not just individual acts but also occurs at the level of the speech event, as seen through an analysis of how the participants perceive the function of the encounter and their respective roles vis-à-vis their own institutional networks. The data consists of a video-tape recording in conjunction with follow-up (stimulated recall) interviews with the two participants.
Simple management in contact situations
Authors: Fairbrother Lisa , Masuda Yuko
Published: November 2012

Empirical research has shown that not all deviations from norms occurring in contact situations are noted and that, in fact, many remain unnoted (Fairbrother, 2004; Kon, 2002). Indeed, Neustupný (1985) has proposed that there are “special circumstances” under which native speakers note deviations, such as when the speakers’ metalinguistic attention is drawn to the deviation or when the interlocutor is unfamiliar. Based on our analysis of natural data from a variety of Japanese contact situations, we will examine the factors that determine whether a deviation will be noted or not. In addition to finding evidence of “Neustupný’s “special circumstances”, we will show how the type of deviation, where the deviation occurs within the interaction, the situational context of the interaction, the relationship between the noted deviation and other previously noted deviations, the ethnicity of the interlocutor, and the psychological characteristics of the noter may each influence the noting process.
Theory and practice in language management
Authors: Neustupny J.V.
Published: November 2012

This paper addresses the distinction between theory and practice networks and the ways in which theory can be made more useful for language management practitioners. With regard to the dissemination of knowledge of language management theories, one should not forget that many of these theories contain components that are a direct reflection of their authors’ interests. Therefore, rather than teaching practitioners a set of concepts of a language management theory, it is more rewarding to acquaint them with the basic strategies that govern more than one of these theories. Six examples of such strategies are proposed.