bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetostrictive behaviors of Fe-Si(001) single-crystal films under rotating magnetic fields
Authors: Kawai Tetsuroh , Aida Takuya , Ohtake Mitsuru , Futamoto Masaaki
Published: February 2015

Magnetostrictive behaviors under rotating magnetic fields are investigated for bcc(001) single-crystal films of Fe100−x-Six(x = 0, 6, 10 at. %). The magnetostriction observation directions are along bcc[100] and bcc[110] of the films. The magnetostriction waveform varies greatly depending on the observation direction. For the observation along [100], the magnetostriction waveform of all the films is bathtub-like and the amplitude stays at almost constant even when the magnetic field is increased up to the anisotropy field. On the other hand, the waveform along [110] is triangular and the amplitude increases with increasing magnetic field up to the anisotropy field and then saturates. In addition, the waveform of Fe90Si10 film is distorted triangular when the applied magnetic fields are less than its anisotropy field. These magnetostrictive behaviors under rotating magnetic fields are well explained by employing a proposed modified coherent rotation model where the anisotropy field and the magnetization reversal field are determined by using measured magnetization curves. The results show that magnetocrystalline anisotropy plays important role on magnetostrictive behavior under rotating magnetic fields.
Detection of phase transitions from the study of whispering gallery mode resonance in liquid crystal droplets
Authors: Kumar T. Arun , Mohiddon M. A. , Dutta N. , Viswanathan Nirmal K. , Dhara Surajit
Published: February 2015

We report studies on the whispering gallery mode (WGM) resonance of liquid crystal (LC) droplets across the smectic-A (SmA) to nematic phase transition. The quality factor (Q) in the SmA phase decreases rapidly with a characteristic slope change at the SmA-N transition. In the SmA phase, Q-factor is linearly proportional to the birefringence (Δn). We discuss the effect of topological defect transformation on the WGM resonance. The study of WGM resonance is expected to be very useful for detecting subtle phase transitions among LC mesophases.
Magnetocaloric properties of rapidly solidified Dy3Co alloy ribbons
Authors: Sánchez Llamazares J. L. , Flores-Zúñiga H. , Álvarez-Alonso Pablo , Sánchez-Valdés C. F. , Lara Rodríguez G. A. , Fernández-Gubieda M. L.
Published: February 2015

The magnetic and magnetocaloric (MC) properties of melt-spun ribbons of the Dy3Co intermetallic compound were investigated. Samples were fabricated in an Ar environment using a homemade melt spinner system at a linear speed of the rotating copper wheel of 40 ms−1. X-ray diffraction analysis shows that ribbons crystallize into a single-phase with the Fe3C-type orthorhombic crystal structure. The M(T) curve measured at 5 mT reveals the occurrence of a transition at 32 K from a first to a second antiferromagnetic (AFM) state and an AFM-to-paramagnetic transition at TN = 43 K. Furthermore, a metamagnetic transition is observed below TN, but the magnetization change ΔM is well below the one reported for bulk alloys. Below 12 K, large inverse MC effect and hysteresis losses are observed. This behavior is related to the metamagnetic transition. For a magnetic field change of 5 T (2 T) applied along the ribbon length, the produced ribbons show a peak value of the magnetic entropy change ΔSMpeak of −6.5 (− 2.1) Jkg−1K−1 occurring close to TN with a full-width at half-maximum δTFWHM of 53 (37) K, and refrigerant capacity RC = 364 (83) Jkg−1 (estimated from the product |ΔSMpeak| × δTFWHM).
Advance ratio effects on the flow structure and unsteadiness of the dynamic-stall vortex of a rotating blade in steady forward flight
Authors: Raghav Vrishank , Komerath Narayanan
Published: February 2015

The effect of advance ratio on the flow structures above a rotor blade in dynamic-stall is studied using stereoscopic particle image velocimetry. The dynamic-stall vortex shows a significant velocity component in its core, implying a helical structure progressing radially outboard. In addition, a dual-vortical structure was observed at inboard locations only at high advance ratios. The radial velocity attenuates at outboard locations, in contrast to the expected increase with centripetal acceleration. This attenuation is accompanied by an increase in unsteadiness of the vortex. The unsteadiness shows a low-frequency cycle-to-cycle variation despite steady freestream conditions and phase-locked blade tracking. Proper orthogonal decomposition analysis of the dominant flow mode confirms the unsteady behavior of the leading-edge vortex. The dependence on advance ratio is used to relate the unsteadiness of the dynamic-stall vortex to Coriolis effects.
Absence of absolutely continuous spectrum for random scattering zippers
Authors: Boumaza Hakim , Marin Laurent
Published: February 2015

A scattering zipper is a system obtained by concatenation of scattering events with equal even number of incoming and outgoing channels. The associated scattering zipper operator is the unitary analog of Jacobi matrices with matrix entries. For infinite identical events and independent and identically distributed random phases, Lyapunov exponents positivity is proved and yields absence of absolutely continuous spectrum by Kotani’s theory.
Spicing up continuum solvation models with SaLSA: The spherically averaged liquid susceptibility ansatz
Authors: Sundararaman Ravishankar , Schwarz Kathleen A. , Letchworth-Weaver Kendra , Arias T. A.
Published: February 2015

Continuum solvation models enable electronic structure calculations of systems in liquid environments, but because of the large number of empirical parameters, they are limited to the class of systems in their fit set (typically organic molecules). Here, we derive a solvation model with no empirical parameters for the dielectric response by taking the linear response limit of a classical density functional for molecular liquids. This model directly incorporates the nonlocal dielectric response of the liquid using an angular momentum expansion, and with a single fit parameter for dispersion contributions it predicts solvation energies of neutral molecules with a RMS error of 1.3 kcal/mol in water and 0.8 kcal/mol in chloroform and carbon tetrachloride. We show that this model is more accurate for strongly polar and charged systems than previous solvation models because of the parameter-free electric response, and demonstrate its suitability for ab initio solvation, including self-consistent solvation in quantum Monte Carlo calculations.
Modeling of fast neutral-beam-generated ion effects on MHD-spectroscopic observations of resistive wall mode stability in DIII-D plasmas
Authors: Turco F. , Turnbull A. D. , Hanson J. M. , Navratil G. A.
Published: February 2015

Experiments conducted at DIII-D investigate the role of drift kinetic damping and fast neutral beam injection (NBI)-ions in the approach to the no-wall βN limit. Modelling results show that the drift kinetic effects are significant and necessary to reproduce the measured plasma response at the ideal no-wall limit. Fast neutral-beam ions and rotation play important roles and are crucial to quantitatively match the experiment. In this paper, we report on the model validation of a series of plasmas with increasing βN, where the plasma stability is probed by active magnetohydrodynamic (MHD) spectroscopy. The response of the plasma to an externally applied field is used to probe the stable side of the resistive wall mode and obtain an indication of the proximity of the equilibrium to an instability limit. We describe the comparison between the measured plasma response and that calculated by means of the drift kinetic MARS-K code [Liu et al., Phys. Plasmas 15, 112503 (2008)], which includes the toroidal rotation, the electron and ion drift-kinetic resonances, and the presence of fast particles for the modelled plasmas. The inclusion of kinetic effects allows the code to reproduce the experimental results within ∼13% for both the amplitude and phase of the plasma response, which is a significant improvement with respect to the undamped MHD-only model. The presence of fast NBI-generated ions is necessary to obtain the low response at the highest βN levels (∼90% of the ideal no-wall limit). The toroidal rotation has an impact on the results, and a sensitivity study shows that a large variation in the predicted response is caused by the details of the rotation profiles at high βN.
Comment on “Generalized dispersion relation for electron Bernstein waves in a non-Maxwellian magnetized anisotropic plasma” [Phys. Plasmas 17, 102114 (2010)]
Authors: Sharifi M. , Parvazian A.
Published: February 2015

In a recent paper [Deeba et al., Phys. Plasmas 17, 102114 (2010)], a generalized dielectric constant for the electron Bernstein waves using non-Maxwellian distribution functions was derived in a collisionless, uniform magnetized plasma. Using the Neumann series expansion for the products of Bessel functions, Deeba, Ahmad, and Murtaza derived the dispersion relations for both kappa and the generalized (r, q) distributions in a straightforward manner. However, their results are questionable, since the Neumann series expansion for the products of Bessel functions is valid for small argument, while for perpendicular propagation, it is necessary to evaluate special integrands for small as well as large arguments.
Global strong solutions to the 1-D compressible magnetohydrodynamic equations with zero resistivity
Authors: Fan Jishan , Hu Yuxi
Published: February 2015

This paper proves the global well-posedness of the 1-D compressible magnetohydrodynamics equations with zero resistivity with large initial data and vacuum.
Marginally trapped submanifolds in Lorentzian space forms and in the Lorentzian product of a space form by the real line
Authors: Anciaux Henri , Godoy Yamile
Published: February 2015

We give local, explicit representation formulas for n-dimensional spacelike submanifolds which are marginally trapped in the Minkowski space R1n+2, the de Sitter space d𝕊n+2, the anti-de Sitter space Ad𝕊n+2 and the Lorentzian products 𝕊n+1 × ℝ and ℍn+1 × ℝ of the sphere and the hyperbolic space by the real line.
Atomic layer deposition of crystalline SrHfO3 directly on Ge (001) for high-k dielectric applications
Authors: McDaniel Martin D. , Hu Chengqing , Lu Sirong , Ngo Thong Q. , Posadas Agham , Jiang Aiting , Smith David J. , Yu Edward T. , Demkov Alexander A. , Ekerdt John G.
Published: February 2015

The current work explores the crystalline perovskite oxide, strontium hafnate, as a potential high-k gate dielectric for Ge-based transistors. SrHfO3 (SHO) is grown directly on Ge by atomic layer deposition and becomes crystalline with epitaxial registry after post-deposition vacuum annealing at ∼700 °C for 5 min. The 2 × 1 reconstructed, clean Ge (001) surface is a necessary template to achieve crystalline films upon annealing. The SHO films exhibit excellent crystallinity, as shown by x-ray diffraction and transmission electron microscopy. The SHO films have favorable electronic properties for consideration as a high-k gate dielectric on Ge, with satisfactory band offsets (>2 eV), low leakage current (<10−5 A/cm2 at an applied field of 1 MV/cm) at an equivalent oxide thickness of 1 nm, and a reasonable dielectric constant (k ∼ 18). The interface trap density (Dit) is estimated to be as low as ∼2 × 1012 cm−2 eV−1 under the current growth and anneal conditions. Some interfacial reaction is observed between SHO and Ge at temperatures above ∼650 °C, which may contribute to increased Dit value. This study confirms the potential for crystalline oxides grown directly on Ge by atomic layer deposition for advanced electronic applications.
Spatial instability in annular swirling viscous liquid sheet
Authors: Yan Kai , Ning Zhi , Lü Ming , Sun Chunhua , Fu Juan , Li Yuanxu
Published: February 2015

The spatial linear instability of an annular swirling viscous liquid sheet moving in an inviscid gas medium was investigated. With both para-sinuous and para-varicose modes analyzed, results show that under certain conditions the mode difference for the maximum disturbance growth rate is small. However, the para-sinuous mode is always the dominant mode for an annular swirling viscous liquid sheet in the parameter range studied here. Liquid swirls have a stabilizing effect at low swirling strengths. Two regions were identified: the initial region, where the maximum disturbance growth rate decreases with increasing dimensionless liquid swirling strength, and a region of monotonic increase of maximum disturbance growth rate with increasing liquid swirling strength. The non-axisymmetric mode is the dominant mode when swirling strength is large in an annular liquid sheet. The drop in axial size of non-axisymmetric mode is larger than that for the axisymmetric mode. Liquid viscosity suppresses increases in the maximum disturbance growth rates and the dominant wavenumber. Surface tension has a destabilizing effect when liquid swirling strength is absent or small, subject to a certain criterion, and a stabilizing effect irrespective of the presence of liquid swirling strength otherwise. Curvature in the annular sheet stabilizes the breakup of the liquid sheet. This effect is more obvious if the liquid swirling strength is large. For different liquid swirling strengths, the dominant disturbance modes of annular liquid sheets become axisymmetric modes as the annular liquid curvature decreases. The dominant wavenumber increases as annular liquid curvature decreases; this trend is more obvious with larger liquid swirling strengths.
High-efficiency amorphous silicon solar cells: Impact of deposition rate on metastability
Authors: Matsui Takuya , Bidiville Adrien , Maejima Keigou , Sai Hitoshi , Koida Takashi , Suezaki Takashi , Matsumoto Mitsuhiro , Saito Kimihiko , Yoshida Isao , Kondo Michio
Published: February 2015

Hydrogenated amorphous silicon (a-Si:H) films, used for light absorbers of p-i-n solar cells, were deposited at various deposition rates (Rd) ranging over two orders of magnitude (Rd ∼ 2 × 10−3–3 × 10−1 nm/s) by using diode and triode plasma-enhanced chemical vapor deposition (PECVD). The impact of varying Rd on the light-soaking stability of the solar cells has been investigated. Although a reduction of Rd mitigates the light-induced degradation in the typical range of Rd (>10−1 nm/s), it remains present even in the very low Rd (<10−2 nm/s), indicating that the metastable effect persists in a-Si:H regardless of Rd. The best performing cell, whose a-Si:H absorber is characterized by low amount of metastable defect and high bandgap, can be obtained at Rd of ∼1–3 × 10−2 nm/s by triode PECVD. By applying such a-Si:H in the improved p-i-n devices, we demonstrate two record independently confirmed stabilized efficiencies of 10.22% for single-junction and 12.69% for a-Si:H/hydrogenated microcrystalline silicon (μc-Si:H) tandem solar cells.
Generation of spin currents in the skyrmion phase of a helimagnetic insulator Cu2OSeO3
Authors: Hirobe Daichi , Shiomi Yuki , Shimada Yuhki , Ohe Jun-ichiro , Saitoh Eiji
Published: February 2015

We report spin-current generation related to skyrmion dynamics resonantly excited by a microwave in a helimagnetic insulator Cu2OSeO3. A Pt layer was fabricated on Cu2OSeO3 and voltage in the Pt layer was measured upon magnetic upon magnetic resonance of Cu2OSeO3 to electrically detect injected spin currents via the inverse spin Hall effect (ISHE) in Pt. We found that ISHE-induced electromotive forces appear in the skyrmion phase of Cu2OSeO3 as well as in the ferrimagnetic phase, which shows that magnetic skyrmions can contribute to the spin pumping effect.
Electron plasma dynamics during autoresonant excitation of the diocotron mode
Authors: Baker C. J. , Danielson J. R. , Hurst N. C. , Surko C. M.
Published: February 2015

Chirped-frequency autoresonant excitation of the diocotron mode is used to move electron plasmas confined in a Penning-Malmberg trap across the magnetic field for advanced plasma and antimatter applications. Plasmas of 108 electrons, with radii small compared to that of the confining electrodes, can be moved from the magnetic axis to ≥90% of the electrode radius with near unit efficiency and reliable angular positioning. Translations of ≥70% of the wall radius are possible for a wider range of plasma parameters. Details of this process, including phase and displacement oscillations in the plasma response and plasma expansion, are discussed, as well as possible extensions of the technique.
Detecting low concentrations of plutonium hydride with magnetization measurements
Authors: Kim Jae Wook , Mun E. D. , Baiardo J. P. , Smith A. I. , Richmond S. , Mitchell J. , Schwartz D. , Zapf V. S. , Mielke C. H.
Published: February 2015

We report the formation of plutonium hydride in 2 at. % Ga-stabilized δ-Pu, with 1 at. % H charging. We show that magnetization measurements are a sensitive, quantitative measure of ferromagnetic plutonium hydride against the nonmagnetic background of plutonium. It was previously shown that at low hydrogen concentrations, hydrogen forms super-abundant vacancy complexes with plutonium, resulting in a bulk lattice contraction. Here, we use magnetization, X-ray, and neutron diffraction measurements to show that in addition to forming vacancy complexes, at least 30% of the H atoms bond with Pu to precipitate PuHx on the surface of the sample with x ∼ 1.9. We observe magnetic hysteresis loops below 40 K with magnetic remanence, consistent with ferromagnetic PuH1.9.
The effect of charged quantum dots on the mobility of a two-dimensional electron gas: How important is the Coulomb scattering?
Authors: Kurzmann A. , Beckel A. , Ludwig A. , Wieck A. D. , Lorke A. , Geller M.
Published: February 2015

We have investigated the influence of a layer of charged self-assembled quantum dots (QDs) on the mobility of a nearby two-dimensional electron gas (2DEG). Time-resolved transconductance spectroscopy was used to separate the two contributions of the change in mobility, which are: (i) The electrons in the QDs act as Coulomb scatterers for the electrons in the 2DEG. (ii) The screening ability and, hence, the mobility of the 2DEG decreases when the charge carrier density is reduced by the charged QDs, i.e., the mobility itself depends on the charge carrier concentration. Surprisingly, we find a negligible influence of the Coulomb scattering on the mobility for a 2DEG, separated by a 30 nm tunneling barrier to the layer of QDs. This means that the mobility change is completely caused by depletion, i.e., reduction of the charge carrier density in the 2DEG, which indirectly influences the mobility.
Development of a low-cost double rotor axial flux motor with soft magnetic composite and ferrite permanent magnet materials
Authors: Liu Chengcheng , Zhu Jianguo , Wang Youhua , Guo Youguang , Lei Gang , Liu Xiaojing
Published: February 2015

This paper proposes a low-cost double rotor axial flux motor (DRAFM) with low cost soft magnetic composite (SMC) core and ferrite permanent magnets (PMs). The topology and operating principle of DRAFM and design considerations for best use of magnetic materials are presented. A 905 W 4800 rpm DRAFM is designed for replacing the high cost NdFeB permanent magnet synchronous motor (PMSM) in a refrigerator compressor. By using the finite element method, the electromagnetic parameters and performance of the DRAFM operated under the field oriented control scheme are calculated. Through the analysis, it is shown that that the SMC and ferrite PM materials can be good candidates for low-cost electric motor applications.
Spatio-temporal characteristics of self-pulse in hollow cathode discharge
Authors: Jing Ha , He Shoujie
Published: February 2015

The characteristics of self-pulse in hollow cathode discharge at low pressure have been investigated. The voltage-current (V-I) curves, the influence of ballast resistor on the self-pulses, and the evolution of current and voltage are measured. Both the axial and radial spatio-temporal discharge images of self-pulse are recorded. The results show that there exists the hysteresis effect in the present hollow cathode discharge. The high value of ballast resistors is favourable for the observation of self-pulses. The process of the self-pulse can be divided into three stages from the temporal discharge images, i.e., the pre-discharge, the transition from mainly axial electric field to mainly radial electric field, and the decaying process. The self-pulse is suggested to originate from the mode transition of the discharge in essence.
The importance of the transmission flux in evaluating the preheat effect in x-ray driven ablation
Authors: Li Liling , Jiang Shaoen , Zhang Lu , Zheng Jianhua , Qing Bo , Zhang Jiyan , Kuang Longyu , Li Hang
Published: February 2015

In x-ray driven ablation, the preheat effect is caused by the high energy x-rays that pass through the ablator. Thus, the transmission flux can be used to characterize preheat effect in a certain degree. With the radiation temperature being 200 eV, the transmission flux and preheat temperature of pure polymer (CH) have been studied by using the one-dimensional multi-group radiation hydrodynamic code MULTI-1D. By studying the spectrum of the transmitted x-rays, it is found that the energy of the transmitted x-rays is in the range of 2–5 keV for pure CH ablator. This is of importance for selecting a dopant for CH ablator. We also calculated both the preheat temperature of CH near the surface of thick target (47.66 μm) and the transmission flux of a thinner target (38.66 μm). It is found that the more transmission flux leads to the higher preheat temperature. Preheat effect of graded Si-doped CH targets with different doped concentrations has also been studied. The results are consistent with this phenomenon. By analyzing the relationship between the transmission flux and the preheat temperature, we have presented a novel method to evaluate preheat effect in x-ray driven ablation.
Graphene nanopores as negative differential resistance devices
Authors: Qiu Wanzhi , Nguyen Phuong Duc , Skafidas Efstratios
Published: February 2015

We present graphene nanopores as new negative differential resistance (NDR) devices, and study their quantum transport properties using non-equilibrium Green's function and the density functional tight binding method. The proposed device structure is created on intrinsic armchair-edged graphene nanoribbons with uniform widths, where the central scattering region has a nanopore in the interior, and the two ends of the nanoribbon act naturally as connecting electrodes. We show that nitrogen-passivated scattering regions generally result in pronounced NDR properties, while hydrogen-passivated ones do not. This NDR effect occurs at low bias voltages, below 1 V, and achieves extraordinarily high peak-to-valley current ratio, while still attaining very high peak current densities. In addition, very sharp current peaks in the μA range can occur in the I-V curves, and through varying structural dimensions of the proposed structure multiple NDR regions can be realized. These results suggest that the device has promising potential in applications such as high frequency oscillators, memory devices, and fast switches.
Tunable and flexible solvent-free liquid organic distributed feedback lasers
Authors: Kim Ju-Hyung , Inoue Munetomo , Zhao Li , Komino Takeshi , Seo Soonmin , Ribierre Jean-Charles , Adachi Chihaya
Published: February 2015

We report on optically pumped blue, green, and red liquid organic distributed feedback (DFB) lasers based on solvent-free fluidic organic semiconductors, and prepared on highly flexible corrugated polymeric patterns. By the appropriate selection of laser dyes doping a liquid 9-(2-ethylhexyl)carbazole host, the lasing wavelength is effectively tuned across the visible spectrum via a cascade energy transfer scheme. We also demonstrate a mechanical tunability of the flexible liquid DFB laser emission, which is due to the deformation of the high-aspect ratio DFB grating under bending. Overall, this work provides an important step in the development of flexible liquid organic optoelectronic devices.
In vivo terahertz spectroscopy of pigmentary skin nevi: Pilot study of non-invasive early diagnosis of dysplasia
Authors: Zaytsev Kirill I. , Kudrin Konstantin G. , Karasik Valeriy E. , Reshetov Igor V. , Yurchenko Stanislav O.
Published: February 2015

In vivo terahertz (THz) spectroscopy of pigmentary skin nevi is performed. The in vivo THz dielectric characteristics of healthy skin and dysplastic and non-dysplastic skin nevi are reconstructed and analyzed. The dielectric permittivity curves of these samples in the THz range exhibit significant differences that could allow non-invasive early diagnosis of dysplastic nevi, which are melanoma precursors. An approach for differentiating dysplastic and non-dysplastic skin nevi using the THz dielectric permittivity is proposed. The results demonstrate that THz pulsed spectroscopy is potentially an effective tool for non-invasive early diagnosis of dysplastic nevi and melanomas of the skin.
Characterization of volume holographic recording in photopolymerizable nanoparticle-(thiol-ene) polymer composites at 404 nm
Authors: Kawana Masaru , Takahashi Jun-ichiro , Yasui Satoru , Tomita Yasuo
Published: February 2015

We report on the photopolymerization dynamics and the volume holographic recording properties of a thiol-ene based nanoparticle-polymer composite (NPC) doped with a blue-sensitive photoinitiator, Darocur® TPO, by using a highly coherent blue diode laser operating at a wavelength of 404 nm. Our study indicates that volume gratings recorded in the NPC amount to meeting the material requirements of refractive index modulation and material recording sensitivity for holographic data storage media. It is also found that polymerization shrinkage of recorded NPC gratings is higher than that of the same thiol-ene based NPC with a green (523 nm)-sensitive photoinitiator, Irgacure® 784/BzO2. We attribute such a difference in shrinkage to the photopolymerization dynamics at these recording wavelengths. We show that this shrinkage increase at 404 nm can be mitigated to some extent by controlling the thiol-ene stoichiometry in the NPC.
Erratum: “General nonlocality in quantum fields” [J. Math. Phys. 49, 033513 (2008)]
Authors: Han Lei , Wang Hai-Jun
Published: February 2015

While making some further progresses based on our previous paper [H.-J. Wang J. Math. Phys. 49, 033513 (2008)], we find a few typos or obscure points which may mislead readers interested in the topic. Now, we would like to correct them or make them more understandable.
Tailoring the nonlinear frequency coupling between odd harmonics for the optimisation of charged particle dynamics in capacitively coupled oxygen plasmas
Authors: Gibson A. R. , Greb A. , Graham W. G. , Gans T.
Published: February 2015

The influence of nonlinear frequency coupling in an oxygen plasma excited by two odd harmonics at moderate pressure is investigated using a numerical model. Through variations in the voltage ratio and phase shift between the frequency components changes in ionization dynamics and sheath voltages are demonstrated. Furthermore, a regime in which the voltage drop across the plasma sheath is minimised is identified. This regime provides a significantly higher ion flux than a single frequency discharge driven by the lower of the two frequencies alone. These operating parameters have potential to be exploited for plasma processes requiring low ion bombardment energies but high ion fluxes.
Dynamics of gene circuits shapes evolvability
Authors: Jiménez Alba , Cotterell James , Munteanu Andreea , Sharpe James
Published: February 2015

Significance

It is widely accepted that the structure of a biological system limits the range of possible novel phenotypes accessible by mutation. Here we show that it is not only the phenotype that determines this evolvability, but also the dynamics of how that phenotype is built during development. We perform theoretical analysis on a group of simple gene regulatory circuits that have recently been shown to fall into a handful of distinct dynamical mechanisms all producing the same phenotype: interpreting a morphogen gradient into a single-domain of gene expression. We find that the dynamical mechanisms underlying each circuit impose strong constraints on its evolvability, as hypothesized in a more general context by John Maynard Smith in the 1980s.
A fluid secretion pathway unmasked by acinar-specific
Tmem16A
gene ablation in the adult mouse salivary gland
Authors: Catalán Marcelo A. , Kondo Yusuke , Peña-Munzenmayer Gaspar , Jaramillo Yasna , Liu Frances , Choi Sooji , Crandall Edward , Borok Zea , Flodby Per , Shull Gary E. , Melvin James E.
Published: February 2015

Significance

There are no effective treatments for dry mouth, a common problem that affects millions of people in the United States. Salivary gland hyposecretion is caused by multiple diseases, including Sjögren's syndrome, as well as by radiation therapy and medications. The resulting dry mouth is often associated with dysphagia, reduced taste sensation, and opportunistic infections. The mammalian fluid secretion model predicts that Ca
2+
-activated Tmem16A and/or cAMP-dependent Cftr Cl
-
channels are critical in this process. We demonstrate that activation of the Tmem16A channel is required for muscarinic, Ca
2+
-dependent salivation, but that β-adrenergic receptor-mediated salivation is independent of Tmem16A, Cftr, and ClC-2 Cl
-
channels. A better understanding of the β-adrenergic stimulated secretion mechanism may prove important in the development of therapeutic targets for dry mouth.
Distinct pathways of RNA polymerase regulation by a phage-encoded factor
Authors: Esyunina Daria , Klimuk Evgeny , Severinov Konstantin , Kulbachinskiy Andrey
Published: February 2015

Significance

Transcription termination is an essential regulatory step in gene expression, but its molecular mechanisms remain less understood in comparison with other steps of transcription, owing to the highly dynamic nature of the termination process. Antitermination factors play important regulatory roles in bacteria, viruses, and eukaryotes, but only a few such factors have been studied in molecular detail. We describe a pathway of transcription antitermination by a viral factor that involves suppression of RNA polymerase pausing and stabilization of the transcription complex through interactions with an evolutionary conserved ω subunit of RNA polymerase. The results of the study extend the list of universal RNA polymerase sites able to accept regulatory inputs and provide new insights into the mechanisms of transcription termination.
Highly multiplexed profiling of single-cell effector functions reveals deep functional heterogeneity in response to pathogenic ligands
Authors: Lu Yao , Xue Qiong , Eisele Markus R. , Sulistijo Endah S. , Brower Kara , Han Lin , Amir El-ad David , Pe’er Dana , Miller-Jensen Kathryn , Fan Rong
Published: February 2015

Significance

We demonstrated codetection of 42 immune effector proteins in single cells, representing the highest multiplexing recorded to date for a single-cell secretion assay. Using this platform to profile differentiated macrophages stimulated with lipopolysaccharide reveals previously unobserved deep functional heterogeneity and varying levels of pathogenic activation, which is conserved throughout the cell activation process and prevails as it is extended to other Toll-like receptor (TLR) ligands and to primary human macrophages. The results indicate that the phenotypically similar cell population could still exhibit a large degree of intrinsic heterogeneity at the cell function level. This technology enables full-spectrum dissection of immune functional states in response to pathogenic stimulation and allows for more comprehensive and accurate monitoring of cellular immunity.
Structural basis for transcription reactivation by RapA
Authors: Liu Bin , Zuo Yuhong , Steitz Thomas A.
Published: February 2015

Significance

Transcription is the first and most regulated step of gene expression. During transcription, RNA polymerase (RNAP) translocates along DNA while processively synthesizing RNA molecules hundreds of nucleotides long. Excessive translocation in either direction halts RNA synthesis. Here, we present a structure of the
Escherichia coli
RNA polymerase in complex with ATPase RapA, a large DNA translocase that is involved in transcriptional reactivation. The structural insights gained from this study suggest an alternative mechanism for transcription regulation in which backward translocation (backtranslocation) might be promoted by a DNA translocase and also lead us to propose a model for how RapA reactivates RNA polymerases and stimulates transcription. This active backtranslocation proposed here could be a general mechanism for regulating transcription and transcription-related processes.
Regulator of G protein signaling 6 is a critical mediator of both reward-related behavioral and pathological responses to alcohol
Authors: Stewart Adele , Maity Biswanath , Anderegg Simon P. , Allamargot Chantal , Yang Jianqi , Fisher Rory A.
Published: February 2015

Significance

Almost 20% of women and 40% of men in the United States abuse alcohol or have experienced alcohol dependence in their lifetime. Though accidents, traffic fatalities, and violent crimes account for the majority of alcohol-involved mortalities, excessive, chronic drinking also causes often irreversible heart and liver damage. We identify regulator of G protein signaling 6 (RGS6) as a novel drug target with substantive potential clinical utility in the treatment of alcoholism and amelioration of the resultant hepatic and cardiac toxicity. Mice lacking RGS6 exhibit a reduction in voluntary alcohol consumption, conditioned reward and withdrawal. In addition,
RGS6
−/−
mice are largely protected from alcohol-induced cardiomyopathy, hepatic steatosis, gastrointestinal barrier dysfunction, and endotoxemia. Thus, targeting RGS6 could reduce alcohol cravings while simultaneously protecting the heart and liver from damage.
Aberrant recombination and repair during immunoglobulin class switching in BRCA1-deficient human B cells
Authors: Björkman Andrea , Qvist Per , Du Likun , Bartish Margarita , Zaravinos Apostolos , Georgiou Konstantinos , Børglum Anders D. , Gatti Richard A. , Törngren Therese , Pan-Hammarström Qiang
Published: February 2015

Significance

DNA double-strand breaks (DSBs) are one of the most deleterious types of DNA lesions and may pose a severe threat to genome integrity. Breast cancer type 1 susceptibility protein (BRCA1) is a multifunctional DNA damage response factor that is known to protect the chromosome/genome stability by participating in one of the major DSB repair pathways, homologous recombination (HR). Here we show that in human B cells BRCA1 is also required for another major DSB repair pathway, nonhomologous end-joining (NHEJ) during immunoglobulin class switch recombination (CSR), probably by inhibition of resection and microhomology-mediated end-joining (MMEJ), as well as promotion of long-range recombination. Our study provides previously unrecognized insights into BRCA1’s function in maintaining genome stability and tumor suppression.
Sulfur-cycling fossil bacteria from the 1.8-Ga Duck Creek Formation provide promising evidence of evolution's null hypothesis
Authors: Schopf J. William , Kudryavtsev Anatoliy B. , Walter Malcolm R. , Van Kranendonk Martin J. , Williford Kenneth H. , Kozdon Reinhard , Valley John W. , Gallardo Victor A. , Espinoza Carola , Flannery David T.
Published: February 2015

Significance

An ancient deep-sea mud-inhabiting 1,800-million-year-old sulfur-cycling microbial community from Western Australia is essentially identical both to a fossil community 500 million years older and to modern microbial biotas discovered off the coast of South America in 2007. The fossils are interpreted to document the impact of the mid-Precambrian increase of atmospheric oxygen, a world-changing event that altered the history of life. Although the apparent 2-billion-year-long stasis of such sulfur-cycling ecosystems is consistent with the null hypothesis required of Darwinian evolution—if there is no change in the physical-biological environment of a well-adapted ecosystem, its biotic components should similarly remain unchanged—additional evidence will be needed to establish this aspect of evolutionary theory.
Mitochondrial peroxiredoxin functions as crucial chaperone reservoir inLeishmania infantum
Authors: Teixeira Filipa , Castro Helena , Cruz Tânia , Tse Eric , Koldewey Philipp , Southworth Daniel R. , Tomás Ana M. , Jakob Ursula
Published: February 2015

Significance

Peroxiredoxins (Prxs) are highly abundant proteins, which serve two seemingly mutually exclusive roles as peroxidases and molecular chaperones. Little is known about the precise mechanism of Prxs’ activation as chaperone and the physiological significance of this second function. Here we demonstrate that inLeishmania infantum, reduced Prx provides a crucial, stress-specific chaperone reservoir, which is activated rapidly upon exposure to unfolding stress conditions. Once activated, Prx protects a wide range of different clients against protein unfolding. Clients are bound in the center of the decameric ring, providing experimental evidence for previous claims that Prxs serve as likely ancestors of chaperonins. Interference with client binding impairsLeishmaniainfectivity, providing compelling evidence for the in vivo importance of Prx’s chaperone function.
Suppression of systemic autoimmunity by the innate immune adaptor STING
Authors: Sharma Shruti , Campbell Allison M. , Chan Jennie , Schattgen Stefan A. , Orlowski Gregory M. , Nayar Ribhu , Huyler Annie H. , Nündel Kerstin , Mohan Chandra , Berg Leslie J. , Shlomchik Mark J. , Marshak-Rothstein Ann , Fitzgerald Katherine A.
Published: February 2015

Significance

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease that presents with a diverse array of clinical symptoms and afflicts over 1.5 million Americans. Current treatments involve immunosuppressive regimens associated with debilitating and adverse effects. With the description of a role for innate signaling in SLE, safe and efficient therapies that block Toll-like receptors also have been stymied by the relative short in vivo half lives of known inhibitors and the dangerous outcome of complete MyD88 blockade. Key natural regulators of the disease process are not well described but are more likely to provide disease-specific therapeutics with fewer adverse effects. In this study, we have identified a novel function for Stimulator of interferon genes as a suppressor of disease and a target for future SLE therapeutics.
N2gas is an effective fertilizer for bioethanol production byZymomonas mobilis
Authors: Kremer Timothy A. , LaSarre Breah , Posto Amanda L. , McKinlay James B.
Published: February 2015

Significance

Recently there has been a surge in ethanol biofuel production from cellulosic feedstocks, offering more environmental benefits than conventional ethanol production from food crops. However, cellulosic feedstocks are low in nitrogen, requiring that millions of dollars be spent on nitrogen supplements to grow the ethanol-producing microbes.Zymomonas mobilisis a bacterium that has long been viewed as a potential rival to Baker’s yeast as an ethanol producer. Contrary to published remarks, we discovered thatZ. mobiliscan use the most abundant gas in the atmosphere, N2, as a nitrogen source and does so without detriment to the high ethanol yield. Using N2-utilizingZ. mobiliscould offset much of the monetary and environmental costs of current industrial nitrogen supplements.
Potassium channelopathy-like defect underlies early-stage cerebrovascular dysfunction in a genetic model of small vessel disease
Authors: Dabertrand Fabrice , Krøigaard Christel , Bonev Adrian D. , Cognat Emmanuel , Dalsgaard Thomas , Domenga-Denier Valérie , Hill-Eubanks David C. , Brayden Joseph E. , Joutel Anne , Nelson Mark T.
Published: February 2015

Significance

Small vessel disease (SVD) of the brain refers to a group of pathological processes leading to cerebral lesions, cognitive decline, and stroke. Despite the importance of SVD, there is no specific treatment, mainly due to a limited understanding of the disease pathogenesis. Using a recently developed mouse model of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, a hereditary form of SVD, we determined the basis of altered brain artery function at an early stage of disease progression. We found that cerebrospecific up-regulation of the voltage-gated potassium channel, K
V
1, prevents intracerebral arterioles from constricting in response to physiological levels of intraluminal pressure. This impairment of a fundamental vascular function is expected to impact cerebral blood flow autoregulation and local dilation in response to neuronal activity (functional hyperemia).
Revealing the density of encoded functions in a viral RNA
Authors: Patel Nikesh , Dykeman Eric C. , Coutts Robert H. A. , Lomonossoff George P. , Rowlands David J. , Phillips Simon E. V. , Ranson Neil , Twarock Reidun , Tuma Roman , Stockley Peter G.
Published: February 2015

Significance

Single-stranded RNA viruses self-assemble protective protein containers around their cognate genomes rapidly and efficiently at low concentrations. RNA encapsidation in vivo occurs preferentially with the cognate genome, in contrast to many in vitro reassembly experiments. We describe in molecular detail how this specificity and efficiency is accomplished using multiple contacts between coat proteins and dispersed packaging signals in the viral genome. The sequences and relative positioning of the packaging signals are important for this mechanism, creating a strong evolutionary constraint. Packaging signals overlap untranslated and coding regions ensuring assembly is in competition with other functions of the genome. Disrupting these contacts has deleterious consequences for capsid assembly identifying a novel antiviral drug target.
Classification of charge density waves based on their nature
Authors: Zhu Xuetao , Cao Yanwei , Zhang Jiandi , Plummer E. W. , Guo Jiandong
Published: February 2015

Significance

Charge density waves (CDWs) are observed in many solids, especially in low-dimensional systems. Their existence was first predicted in the 1930s by Rudolf Peierls, who prophesied that CDWs would exist in an ideal one-dimensional (1D) chain of atoms, lowering the energy of the system and driving a reconstruction of the lattice. In 1959, Walter Kohn pointed out that this nesting results in what is now known as a “Kohn anomaly,” a simultaneous softening of coherent lattice vibrations, i.e., phonon softening. This simple textbook picture of the origin of CDWs does not seem to be correct in many materials and in this report we propose a previously unidentified classification of CDWs based upon their nature.
An early secretory pathway mediated by GNOM-LIKE 1 and GNOM is essential for basal polarity establishment inArabidopsis thaliana
Authors: Doyle Siamsa M. , Haeger Ash , Vain Thomas , Rigal Adeline , Viotti Corrado , Łangowska Małgorzata , Ma Qian , Friml Jiří , Raikhel Natasha V. , Hicks Glenn R. , Robert Stéphanie
Published: February 2015

Significance

Within plants, controlled gradients of the hormone auxin are essential for development. These gradients are achieved through intracellular polar positioning of auxin transporter proteins, such as PIN-FORMED proteins (PINs), at the plasma membrane, thus guiding the direction of auxin transport. The establishment and maintenance of PIN polarity is controlled within each cell by complicated trafficking pathways of the endomembrane system. In the model plantArabidopsis, it has long been known that endocytosis and recycling trafficking routes play roles in PIN polarity. In this study, we reveal the role of a secretory route in this process. Our evidence shows that this secretory trafficking route selectively controls basal (rootward) but not apical (shootward) PIN polarity.
Self-affirmation alters the brain’s response to health messages and subsequent behavior change
Authors: Falk Emily B. , O’Donnell Matthew Brook , Cascio Christopher N. , Tinney Francis , Kang Yoona , Lieberman Matthew D. , Taylor Shelley E. , An Lawrence , Resnicow Kenneth , Strecher Victor J.
Published: February 2015

Significance

Self-affirmation is a psychological technique that is effective in increasing receptivity to interventions across domains from promoting health behaviors in high-risk populations to improving academic performance in underrepresented groups. The neural mechanisms that lead to affirmation’s success, however, are not known. We show that neural responses associated with self-related processing and value in response to an otherwise-threatening health communication intervention can be changed using self-affirmation; furthermore, these neural responses predict objectively measured behavior change in the month following the intervention. These findings suggest that self-affirmation may exert its effects by allowing at-risk individuals to see the self-relevance and value in otherwise-threatening messages and provide a framework for studying neural effects of self-affirmation more broadly.
Characterization of nonprimate hepacivirus and construction of a functional molecular clone
Authors: Scheel Troels K. H. , Kapoor Amit , Nishiuchi Eiko , Brock Kenny V. , Yu Yingpu , Andrus Linda , Gu Meigang , Renshaw Randall W. , Dubovi Edward J. , McDonough Sean P. , Van de Walle Gerlinde R. , Lipkin W. Ian , Divers Thomas J. , Tennant Bud C. , Rice Charles M.
Published: February 2015

Significance

The origin of hepatitis C virus (HCV) has long remained a mystery. Unexpectedly, a plethora of HCV-related hepaciviruses was recently discovered in horses, monkeys, rodents, and bats. These discoveries are of particular interest and may aid in understanding HCV evolution, molecular biology, and natural history. Currently, immunocompetent HCV animal models are lacking, impeding vaccine development; novel hepaciviruses and their natural hosts could provide such models. Here, we demonstrate that the closest HCV homolog, nonprimate hepacivirus (NPHV), is a hepatotropic equine virus with many similarities to HCV, including the capacity to establish persistent infection, delayed-onset seroconversion, and liver pathology. We identify the complete NPHV genome and establish a functional clone infectious in horses, a key advance providing a direct link between virus infection and clinical outcome.
Overlapping hotspots in CDRs are critical sites for V region diversification
Authors: Wei Lirong , Chahwan Richard , Wang Shanzhi , Wang Xiaohua , Pham Phuong T. , Goodman Myron F. , Bergman Aviv , Scharff Matthew D. , MacCarthy Thomas
Published: February 2015

Significance

The somatic hypermutation of immunoglobulin (Ig) variable (V) regions is required to produce high-affinity protective antibodies. Activation-induced deaminase (AID) initiates the accumulation of mutations in the V regions at frequencies that are a million times higher than the normal mutation rates in non-Ig genes. On the basis of the in vivo pattern of mutations in the highly usedIGHV3-23*01human V region and the manipulation of DNA sequence motifs in that V region in a mutating B-cell line and biochemically, we have concluded that particular DNA sequence motifs focus and influence AID activity on those parts of the V region that affect antigen binding and should be considered in vaccine strategies.