bluuebunny/crossref_metadata_2025 huggingface dataset:
Noncontinuum drag force on a nanowire vibrating normal to a wall: Simulations and theory
Authors: Ramanathan Shriram , Koch Donald L. , Bhiladvala Rustom B.
Published: October 2010

Nanoelectromechanical oscillators are very attractive as sensing devices because of their low power requirements and high resolution, especially at low pressures. While many experimental studies of such systems are available in the literature, a fundamental theoretical understanding over the entire range of operating conditions is lacking. In this article, we use our newly developed Bhatnagar–Gross–Krook based low Mach number direct simulation Monte Carlo method to study the noncontinuum drag force acting on a cylinder oscillating normal to a wall. We explore quasisteady flows in which ωτf⪡1 as well as unsteady flows for which ωτf=O(1). Here ω is the oscillation frequency and τf is the characteristic time for the development of the gas flow. The drag force per unit length acting on a long cylindrical wire is studied as a function of the Knudsen number, defined in terms of the mean free path λ and the radius of the cylinder R as Kn=λ/R. For quasisteady flows, we also present theoretical calculations for the slip regime, Kn⪡1, and the free molecular flow regime, Kn⪢1. Simulations of unsteady gas flow around a sinusoidally oscillating cylinder near a wall indicate that the drag force per unit length nondimensionalized by 4πμU approaches constant values for ωτf⪡1 (quasisteady flow) and for ωτf⪢1. Here μ is the gas viscosity and U is the maximum value of the nanowire velocity. The simulation results are compared with experimental measurements in the quasisteady regime.
Electrostatic drift-wave instability in a nonuniform quantum magnetoplasma with parallel velocity shear flows
Authors: Tariq Sabeen , Mirza Arshad. M. , Masood W.
Published: October 2010

The propagation of high and low frequency (in comparison with the cyclotron frequency) electrostatic drift-waves is investigated in a nonuniform, dense magnetoplasma (composed of electrons and ions), in the presence of parallel shear flow, by employing the quantum magnetohydrodynamic (QMHD) model. Using QMHD model, a new set of equations is presented in order to investigate linear properties of electrostatic drift-waves with sheared plasma flows for dense plasmas. In this regard, dispersion relations for coupled electron-thermal and drift-ion acoustic modes are derived and several interesting limiting cases are discussed. For instance, it is found that sheared ion flow parallel to the external magnetic field can drive the quantum drift-ion acoustic wave unstable, etc. The present investigation may have relevance in dense astrophysical environments where quantum effects are significant.
Two-dimensional simulations of the neutron yield in cryogenic deuterium-tritium implosions on OMEGA
Authors: Hu S. X. , Goncharov V. N. , Radha P. B. , Marozas J. A. , Skupsky S. , Boehly T. R. , Sangster T. C. , Meyerhofer D. D. , McCrory R. L.
Published: October 2010

Maximizing the neutron yield to obtain energy gain is the ultimate goal for inertial confinement fusion. Nonuniformities seeded by target and laser perturbations can disrupt neutron production via the Rayleigh–Taylor instability growth. To understand the effects of perturbations on the neutron yield of cryogenic DT implosions on the Omega Laser Facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)], two-dimensional DRACO [P. B. Radha et al., Phys. Plasmas 12, 056307 (2005)] simulations have been performed to systematically investigate each perturbation source and their combined effects on the neutron-yield performance. Two sources of nonuniformity accounted for the neutron-yield reduction in DRACO simulations: target offset from the target chamber center and laser imprinting. The integrated simulations for individual shots reproduce the experimental yield-over-clean (YOC) ratio within a factor of 2 or better. The simulated neutron-averaged ion temperatures ⟨Ti⟩ is only about 10%–15% higher than measurements. By defining the temperature-over-clean, its relationship to YOC provides an indication of how much the hot-spot volume and density are perturbed with respect to the uniform situation. Typically, the YOC in OMEGA experiments is of the order of ∼5%. The simulation results suggest that YOC can be increased to the ignition hydroequivalent level of 15%–20% (with ⟨ρR⟩=200–300 mg/cm2) by maintaining a target offset of less than 10 μm and employing beam smoothing by spectral dispersion.
Forced turbulence in large-eddy simulation of compressible magnetohydrodynamic turbulence
Authors: Chernyshov A. A. , Karelsky K. V. , Petrosyan A. S.
Published: October 2010

We present the large-eddy simulation method for studying forced compressible magnetohydrodynamic turbulence. The proposed method is based on a solution of the filtered basic equations of magnetohydrodynamics by finite-difference methods and on a linear representation of the driving forces in the momentum conservation equation and the magnetic induction equation. These forces supply the production of kinetic and magnetic energies. The emphasis is placed upon the important, and not investigated, question about the ability of the large-eddy simulation approach to reproduce Kolmogorov and Iroshnikov–Kraichnan scale-invariant spectra in compressible magnetohydrodynamic flows.
Three-dimensional reconnection and relaxation of merging spheromak plasmas
Authors: Gray T. , Lukin V. S. , Brown M. R. , Cothran C. D.
Published: October 2010

Plasma relaxation inside a highly conducting cylindrical boundary is studied both experimentally and computationally. Dynamics are initiated by the introduction of two equal helicity spheromaks at either end of the cylinder. In the experiment, dense, high-magnetic-flux spheromaks are injected into the flux conserving volume with magnetized plasma guns. In the simulation, identical spheromaks initially occupy both halves of the cylinder and a perturbation is introduced. Merging commences with a single three-dimensional null-point that moves radially out of the flux conserving volume at velocities up to 0.2 of the reconnection outflow velocity. Relaxation to the minimum energy state occurs in about ten Alfvén times. An important conclusion is that even though the dynamical activity is limited to a few modes, this activity is sufficient to promote relaxation to the final, minimum energy state. The dynamical activity appears to conserve magnetic helicity while magnetic energy is converted to flow and heat. The final state arrived at dynamically is identical to that described by C. D. Cothran et al. [Phys. Rev. Lett. 103, 215002 (2009)] using static, eigenvalue analysis.
Circularly polarized luminescence microscopy for the imaging of charge and spin diffusion in semiconductors
Authors: Favorskiy I. , Vu D. , Peytavit E. , Arscott S. , Paget D. , Rowe A. C. H.
Published: October 2010

Room temperature electronic diffusion is studied in 3 μm thick epitaxial p+ GaAs lift-off films using a novel circularly polarized photoluminescence microscope. The method is equivalent to using a standard optical microscope and provides a contactless means to measure both the charge (L) and spin (Ls) diffusion lengths simultaneously. The measured values of L and Ls are in excellent agreement with the spatially averaged polarization and a sharp reduction in these two quantities (L from 21.3 to 1.2 μm and Ls from 1.3 to 0.8 μm) is found with increasing surface recombination velocity. Outward diffusion results in a factor of 10 increase in the polarization at the excitation spot. The range of materials to which the technique can be applied, as well as a comparison with other existing methods for the measurement of spin diffusion, is discussed.
Room temperature enhanced positive magnetoresistance in Pt and carrier induced Zn(Fe)O and Zn(Fe,Al)O dilute magnetic semiconductors junction
Authors: Chattopadhyay S. , Nath T. K.
Published: October 2010

Epitaxial films of ZnO doped with magnetic ion Fe and, in some cases, with 1% Al show clear evidence of room temperature ferromagnetic ordering. The dilute magnetic semiconducting films are n-type in nature. The magnetic moment depends on the carrier concentration of the films. All the films show non-ohmic behavior with Pt metal junction. The observed J–V behavior of Al incorporated films are found to be mainly due to thermionic emission. Except pure ZnO, the junction J–V changes under magnetic field for all the junctions, and shows reasonably high positive junction magnetoresistance at room temperature. The magnitude of junction magnetoresistance is found to depend on the magnitude of the magnetic moment of the dilute magnetic semiconductor films. These properties have been best explained through the standard spin injection theory.
SiBCN materials for high-temperature applications: Atomistic origin of electrical conductivity
Authors: Houska J. , Kos S.
Published: October 2010

The paper contains a detailed discussion of the electronic structure of the novel hard and thermally stable amorphous SiBCN materials. We focus on the weight of individual electronic states on different elements, bond types, bonds of different lengths, and the number of atoms and clusters of atoms the states are localized on. A special attention is paid to the states around the Fermi level. We show in detail the effect of individual elements and bond types on the (non)conductivity of the materials. The results provide a detailed insight into the complex relationships between the material composition and the electronic properties, and allow one to tailor SiBCN compositions which can combine different functional properties, such as high thermal stability with electrical conductivity.
Master-slave synchronization and invariant manifolds for coupled stochastic systems
Authors: Chueshov Igor , Schmalfuß Björn
Published: October 2010

We deal with abstract systems of two coupled nonlinear stochastic (infinite dimensional) equations subjected to additive white noise type process. This kind of systems may describe various interaction phenomena in a continuum random medium. Under suitable conditions we prove the existence of an exponentially attracting random invariant manifold for the coupled system and show that this system can be reduced to a single equation with modified nonlinearity. This result means that under some conditions, we observe (nonlinear) synchronization phenomena in the coupled system. Our applications include stochastic systems consisting of (i) parabolic and hyperbolic equations, (ii) two hyperbolic equations, and (iii) Klein–Gordon and Schrödinger equations. We also show that the random manifold constructed converges to its deterministic counterpart when the intensity of noise tends to zero.
Nonlocal transverse vibration of double-nanobeam-systems
Authors: Murmu T. , Adhikari S.
Published: October 2010

Vibration analysis of double-nanobeam-systems is considered. Double-nanobeam-systems are important in nano-optomechanical systems and sensor applications. Expressions for free bending-vibration of double-nanobeam-system are established within the framework of Eringen’s nonlocal elasticity theory. An analytical method is developed for determining the natural frequencies of the nonlocal double-nanobeam-system. Explicit closed-form expressions for natural frequencies are derived for the case when all four ends are simply-supported. The study highlights that the small-scale effects considerably influence the transverse vibration of double-nanobeam-systems. The nonlocal natural frequencies of double-nanobeam-system are smaller when compared to the corresponding local frequency values. The small-scale effects in the vibrating system are higher with increasing values of nonlocal parameter for the case of in-phase modes of vibration than in the out-of-phase modes of vibration. The increase in the stiffness of the coupling springs in double-nanobeam-system reduces the nonlocal effects during the out-of-phase modes of vibration.
First principles investigations of the thermoelectric behavior of tin sulfide
Authors: Parker David , Singh David J.
Published: October 2010

We present the results of density functional theory and Boltzmann transport calculations suggesting that the commonly available and inexpensive material SnS may show reasonable thermoelectric performance at temperatures suitable for exhaust waste heat recovery, if the material can be heavily p-doped and if the mobility is not greatly degraded by high doping.
Optical and electrical characterization of pulse-modulated argon atmospheric-pressure inductively coupled microplasma jets
Authors: Tajima Satomi , Matsumori Masashi , Nakatsuka Shigeki , Tsuchiya Shouichi , Ichiki Takanori
Published: October 2010

The critical parameters determining the generation of the pulse-modulated argon atmospheric-pressure inductively coupled plasma (AP-ICP) microjet were studied by varying the power, P, pulse-modulation frequency, f, and duty ratio, DR. The temporal changes in the net output power, Pnet, monitored between the very high frequency power supply and matching network by an rf sampler, and ArI 4s′[1/2]1O–4p′[1/2]0 emission from the antenna were measured to elucidate the behavior of this plasma. The AP-ICP microjet, which produces high-density (0.9–1.1×1015 cm−3) nonequilibrium plasma, consists of an alumina discharge tube with the inner diameter of 0.8 mm. The generation diagram of the pulse-modulated plasma was created by having f as the horizontal axis and DR as the vertical axis while varying P up to 50 W. At f≤10 kHz, the plasma was generated at above the linear lines of f and DR, which indicated the existence of the critical power-off period of approximately 80 μs. At f>10 kHz, the pulse-modulated plasma was produced above constant DR and almost independent of f. The time-averaged power, P¯, which is the product of P and DR, had to be more than 8–10 W to sustain the pulse-modulated plasma. From the measurement of the temporal changes in the net power and ArI emission, the dynamic behavior of the pulse-modulated plasma was revealed as follows. The prebreakdown period was present for ∼5 μs after the power was turned on. Once the plasma was generated, the impedance was changed and the reflected power gradually decreased. A strong emission peak was observed immediately after the breakdown, followed by the gradual increase up to the steady state. Finally, the intense afterpeak was observed at 0.8 μs after the power was turned off.
Bandgap shift in SnO2 nanostructures induced by lattice strain and coordination imperfection
Authors: Zhu Ziming , Ouyang Gang , Yang Guowei
Published: October 2010

We have established an analytical model to address the bandgap shift in SnO2 nanostructures in self-equilibrium state on the basis of bond length and bond energy correlations. Based on these analyses of the relationship among the bonding identities, single bond energy, and bandgap shifts derived from the energy perturbation, we found that the deformation potentials relationship of SnO2 nanodots and nanowires are different, while both bandgap energies exhibit a pronounced blueshift as comparable to those of the bulk counterparts. This bandgap shift is attributed to the lattice strain and coordination imperfection in the surfaces of nanostructures.
X-ray detectors based on GaN Schottky diodes
Authors: Duboz Jean-Yves , Frayssinet Eric , Chenot Sébastien , Reverchon Jean-Luc , Idir Mourad
Published: October 2010

GaN Schottky diodes have been fabricated and tested as x-ray detectors in the range from 6 to 21 keV. The spectral response has been measured and is compared to its theoretical value. The study of the response and its temporal dynamics as a function of the bias allows to identify a photovoltaic behavior at low bias and a photoconductive one at larger reverse biases. The GaN diode turned out to be linear as a function of the incident power. The noise and detectivity are given and discussed.
Support vector machine-based feature extractor for L/H transitions in JET
Authors: González S. , Vega J. , Murari A. , Pereira A. , Ramírez J. M. , Dormido-Canto S. ,   JET-EFDA Contributors
Published: October 2010

Support vector machines (SVM) are machine learning tools originally developed in the field of artificial intelligence to perform both classification and regression. In this paper, we show how SVM can be used to determine the most relevant quantities to characterize the confinement transition from low to high confinement regimes in tokamak plasmas. A set of 27 signals is used as starting point. The signals are discarded one by one until an optimal number of relevant waveforms is reached, which is the best tradeoff between keeping a limited number of quantities and not loosing essential information. The method has been applied to a database of 749 JET discharges and an additional database of 150 JET discharges has been used to test the results obtained.
Tuning the permeability of permalloy films for on-chip inductor applications
Authors: Dastagir Tawab , Xu Wei , Sinha Saurabh , Wu Hao , Cao Yu , Yu Hongbin
Published: October 2010

In this work, we demonstrate that the permeability of 1 μm thick NiFe/Cr multilayer films can be tuned by varying the thickness of individual NiFe layers while keeping the total multilayer film thickness constant. Our results show that the permeability can be increased from 170 to 650 by varying the NiFe thicknesses from 100 to 50 nm. The thickness dependant permeability variation was attributed to the presence of stripe domains, as examined by hysteresis measurements and magnetic force microscope imaging. Films with thinner NiFe layers coupled with on-chip spiral inductors enable an inductance increase by a factor of 6.
Surface plasmon coupling to nanoscale Schottky-type electrical detectors
Authors: Dufaux Thomas , Dorfmüller Jens , Vogelgesang Ralf , Burghard Marko , Kern Klaus
Published: October 2010

We have investigated the near-field coupling of surface plasmons to a titanium/CdS nanowire interface for two different device configurations. A bare aluminum grating on an underlying aluminum layer exhibited the expected stronger electrical signal for perpendicular versus parallel light polarization. An opposite intensity ratio was detected when the grating and the Schottky contact are connected via an aluminum–silica–aluminum sandwich structure. Based upon finite difference time domain device simulations, the enhanced coupling for parallel polarization is attributed to the emergence of a transversal electric wave within the metal–insulator–metal structure.
Acoustic field enhancement and subwavelength imaging by coupling to slab waveguide modes
Authors: Christensen J. , García de Abajo F. J.
Published: October 2010

We present a theoretical study on the amplification of evanescent sound waves produced by coupling to trapped modes hosted by a fluidic planar waveguide. Total internal reflection at interfaces of different refractive indexes can be frustrated by the introduction of a slow slab waveguide which is leading to a gigantic field enhancement, useful for sensitive transducers and acoustic shock lithotripsy. The mechanism behind the evanescent field coupling that is also known as tunnelling barrier penetration in quantum mechanics is here adopted for its use in an acoustic superlens. The higher spatial harmonics produced by a subwavelength object can couple to trapped modes of the slow waveguide and be reproduced as an image at a distant plane. We suggest a practical implementation of these ideas by means of a silicone rubber slab containing positive acoustic wave propagation parameters.
Ti/Cu bilayer electrodes for SiNx-passivated Hf–In–Zn–O thin film transistors: Device performance and contact resistance
Authors: Park Joon Seok , Kim Tae Sang , Son Kyoung Seok , Lee Eunha , Jung Ji Sim , Lee Kwang-Hee , Maeng Wan-Joo , Kim Hyun-Suk , Kim Eok Su , Park Kyung-Bae , Kwon Jang-Yeon , Ryu Myung Kwan , Lee Sang Yoon
Published: October 2010

In this study, we examine the possibility of using Ti/Cu bilayer as source/drain electrodes for SiNx-passivated Hf–In–Zn–O (HIZO) thin film transistors by comparing their electrical properties with devices that use Mo electrodes. The Mo devices operate in depletion mode with a higher field effect mobility, while the Ti/Cu devices exhibit an improved subthreshold swing and operate in enhancement mode. Transmission electron microscopy characterization reveals the formation of an amorphous TiOx layer at the Ti/HIZO interface, which is suggested to be responsible for the disparate device characteristics in terms of contact resistance and threshold delay.
Gap-mode plasmonic nanocavity
Authors: Russell Kasey J. , Hu Evelyn L.
Published: October 2010

Here we describe the fabrication and characterization of a plasmonic nanocavity formed in the narrow gap between a Ag nanowire and a flat Ag substrate. The fluorescence spectrum of nanocrystals within the gap was strongly modified by the cavity modes, showing peaks of position and width (Q∼30–60) in quantitative agreement with numerical calculations. At gap spacings of ∼15 nm, the noncavity background fluorescence is largely quenched by the Ag substrate, while the modal fluorescence remains strong, indicating that gap-type structures are more robust to fluorescence quenching.
Use of a putative maternal pheromone during transport and the effect of trailer temperatures on pig losses and welfare
Authors: Lewis C. R. G. , Krebs N. , Hulbert L. E. , McGlone J. J.
Published: October 2010

The efficacy of a maternal pheromone (MP) to reduce transport stress was evaluated in a field study. In addition, we determined the appropriate field sample sizes for measures of death rate and the proportion of fatigued pigs observed before, during, and after transportation. In the first experiment, semi-truck trailers were randomly treated with 500 mL of MP or isopropyl alcohol as the control (C). Animal handling measures were collected at truck loading, unloading, and from resting pens to the stun area. Blood samples were collected from a sample of transported pigs. In the second experiment, a single truck was used repeatedly for transport to the slaughter plant. The truck and lairage pens were sprayed either with the MP or C, depending on the week (n = 11 weeks). Rate of fatigued pigs coming off the truck was 0.41% for C-treated pigs and 0.15% for MP-treated pigs (P > 0.05). Air temperature recorded in the trailers rose during truck loading and idle time, but levelled off during driving (holding at 1.7°C greater than outside). MP tended to reduce the rate of fatigued pigs (39% although not statistically significant) but it also increased handling difficulty. A power test indicated the sample size needed to detect differences with a statistical significant magnitude (P < 0.05) in future transport studies was 249 trucks (~41 085 pigs).
Response of Leucaena leucocephala pastures to phosphorus and sulfur application in Queensland
Authors: Radrizzani Alejandro , Shelton H. Max , Dalzell Scott A.
Published: October 2010

A series of fertiliser trials were conducted on leucaena (Leucaena leucocephala subsp. glabrata) pastures growing on a range of soil types in south-east and central Queensland. The primary objective was to determine the extent of phosphorus (P) and sulfur (S) deficiencies in leucaena-grass pastures established on either virgin soils or previously cropped soils. Two experiments were conducted across nine sites and confirmed that, for many soils in Queensland, leucaena growth was restricted by P and S nutrient deficiencies, which limited plant growth directly and suppressed symbiotic N2 fixation. The major factors contributing to the P and S deficiencies and thus affecting leucaena response were: (i) inherent low soil fertility, (ii) nutrient removal by cropping and grazing, (iii) shallow soils, (iv) soil acidity, and (v) grass competition for available water and nutrients. A secondary treatment, inter-row cultivation, had little effect on leucaena growth but significantly increased grass growth in some soils. In all these experiments, leaf S concentrations and N : S ratios in index tissue were inconsistent indicators of adequacy of S. Similarly, leaf P concentrations were not useful indicators of P deficiency due to inappropriate (drought) leaf sampling conditions experienced in these experiments. The experiments demonstrate that the productivity of leucaena-grass pastures, especially in older leucaena plantations, will be limited by nutrient deficiencies on many soils in Queensland. While leucaena yield was suppressed, no foliar symptoms of nutrient deficiency were observed. Growers need to monitor the nutrient status of their leucaena-grass pastures by leaf tissue analysis using a new sampling protocol. Strategic fertiliser application has the potential to increase rainfall use efficiency by 50% with an expected parallel increase in cattle liveweight gain.
Effect of zilpaterol hydrochloride on feedlot performance and carcass characteristics of ewe lambs during heat-stress conditions
Authors: Macías-Cruz U. , Álvarez-Valenzuela F. D. , Torrentera-Olivera N. G. , Velázquez-Morales J. V. , Correa-Calderón A. , Robinson P. H. , Avendaño-Reyes L.
Published: October 2010

The objective of the present study was to evaluate the effects of supplementation of zilpaterol hydrochloride (ZH) to the finishing diets on the feedlot performance and carcass characteristics of hair sheep ewe lambs during hot environmental conditions. Twenty Katahdin × Pelilbuey and Dorper × Pelibuey crossbred females with an average initial liveweight (LW) of 26.2 ± 0.83 kg were blocked by the initial LW, and assigned individually to 20 pens in a closed calf-rearing unit provided with fans. Treatments were (1) control group (basal diet without ZH) and (2) ZH group (basal diet plus 10 mg of ZH/ewe.day). Skin temperatures were measured each 2 days in five ewes by treatment; ambient weather conditions were recorded every day. After a 34-day feeding period, all ewes were slaughtered. Climatic variables during the study showed severe heat stress, with the average temperature–humidity index and temperature 85 units and 34.1°C, respectively. The skin temperature of belly and right flank was greater (P < 0.05) in ZH females than in control lambs. Ewe lambs fed ZH had feedlot performance, carcass length, shear force, body fat and skin percentage similar (P > 0.05) to control ewe lambs. With the exception of peritoneum and head (P < 0.05), all visceral organs had similar (P > 0.05) percentages between treatments. However, hot- and cool-carcass weights, dressing percentage, conformation and rib-eye area were greater (P < 0.05) for ewes supplemented with ZH. Likewise, the weight of hindquarter, legs and ribs expressed as a percentage of hot-carcass weight increased (P < 0.05) with ZH supplementation. Growth and deposition of excessive fat in hair-sheep ewe lambs were not improved with ZH supplementation under heat-stress conditions, whereas carcass-quality traits such as dressing and rib-eye area were increased.
Photosynthesis and water-use efficiency of seedlings from northern Australian monsoon forest, savanna and swamp habitats grown in a common garden
Authors: Orchard Kim A. , Cernusak Lucas A. , Hutley Lindsay B.
Published: October 2010

Islands of monsoon rainforest and Melaleuca swamp punctuate vast tracts of savanna in monsoonal northern Australia. Seedlings of species from each of these habitat associations were grown in a common garden. Monsoon forest species had higher specific leaf area, lower photosynthetic capacity and lower photosynthetic light compensation points, and required lower irradiance to achieve 50% of light-saturated photosynthesis compared with savanna or swamp species. These traits probably contribute towards greater shade tolerance beneath dense monsoon-forest canopies, whereas savanna and swamp canopies are relatively open. Swamp species, especially two Melaleuca species, had high stomatal conductance and small CO2 drawdown during photosynthesis, and more negative leaf δ13C, compared with monsoon forest and savanna species. Higher stomatal conductance increases carbon uptake during photosynthesis and a high transpiration rate would increase transport of nutrients to absorbing surfaces in the root by mass flow. Thus, a strategy of high transpiration and low water-use efficiency appears to be favoured in swamp species compared with monsoon-forest and savanna species. Instantaneous measurements of the ratio of intercellular to ambient CO2 concentrations (ci/ca) explained 81% of variation in leaf δ13C across 44 species sampled in this and other studies, suggesting that leaf δ13C generally provides a robust proxy for comparisons of ci/ca, even when applied across species.
Phosphorylation of Ser312 contributes to tumor suppression by p53 in vivo
Authors: Slee Elizabeth A. , Benassi Barbara , Goldin Robert , Zhong Shan , Ratnayaka Indrika , Blandino Giovanni , Lu Xin
Published: October 2010

The tumor suppressor p53 is a master sensor of stress, and posttranslational modifications are key in controlling its stability and transcriptional activities. p53 can be phosphorylated on at least 23 Ser/Thr residues, the majority of which are phosphorylated by stress-related kinases. An exception is Ser315 in human p53 (Ser312 in mouse), which is predominantly phosphorylated by cell cycle-related kinases. To understand the biological importance of Ser312 phosphorylation in vivo, we generated p53Ser312Ala knock-in mice. We show here that, although Ser312 is not essential for mouse life span under normal physiological conditions, Ser312Ala mutation dampens p53’s activity during embryonic development. This is evident from its partial rescue of embryonic lethality caused by Mdm4 deletion. In agreement with the notion that Ser312 mutation weakens p53 function, Ser312Ala mice are also more susceptible to tumorigenesis following a sublethal ionizing radiation dose. Importantly, in the cohort studied, Ser312 mutation predisposes mice to develop thymic lymphomas and liver tumors, partly due to p53Ser312Ala's inability to fully induce a set of p53 target genes including p21 and cyclin G1. Thus, we demonstrate that phosphorylation of Ser312 is required for p53 to function fully as a tumor suppressor in vivo.
High-throughput injection with microfluidics using picoinjectors
Authors: Abate Adam R. , Hung Tony , Mary Pascaline , Agresti Jeremy J. , Weitz David A.
Published: October 2010

Adding reagents to drops is one of the most important functions in droplet-based microfluidic systems; however, a robust technique to accomplish this does not exist. Here, we introduce the picoinjector, a robust device to add controlled volumes of reagent using electro-microfluidics at kilohertz rates. It can also perform multiple injections for serial and combinatorial additions.
Acetylation modulates prolactin receptor dimerization
Authors: Ma Li , Gao Jin-song , Guan Yingjie , Shi Xiaoyan , Zhang Hao , Ayrapetov Marina K. , Zhang Zhe , Xu Li , Hyun Young-Min , Kim Minsoo , Zhuang Shougang , Chin Y. Eugene
Published: October 2010

Cytokine-activated receptors undergo extracellular domain dimerization, which is necessary to activate intracellular signaling pathways. Here, we report that in prolactin (PRL)-treated cells, PRL receptor (PRLR) undergoes cytoplasmic loop dimerization that is acetylation-dependent. PRLR-recruited CREB-binding protein (CBP) acetylates multiple lysine sites randomly distributed along the cytoplasmic loop of PRLR. Two PRLR monomers appear to interact with each other at multiple parts from the membrane-proximal region to the membrane-distal region, relying on the coordination among multiple lysine sites neutralized via acetylation. Cytoplasmic loop-dimerized PRLR activates STAT5, which is also acetylated by CBP and undergoes acetylation-dependent dimerization. PRLR dimerization and subsequent signaling are enhanced by treating the cells with deacetylase sirtuin (SIRT) inhibitor nicotinamide or histone deacetylase (HDAC) inhibitor trichostatin A but inhibited by expressing exogenous deacetylase SIRT2 or HDAC6. Our results suggest that acetylation and deacetylation provide the rheostat-like regulation for the cytokine receptor PRLR in its cytoplasmic loop dimerization and subsequent STAT5 activation.
Stoichiometry of the KCNQ1 - KCNE1 ion channel complex
Authors: Nakajo Koichi , Ulbrich Maximilian H. , Kubo Yoshihiro , Isacoff Ehud Y.
Published: October 2010

The KCNQ1 voltage-gated potassium channel and its auxiliary subunit KCNE1 play a crucial role in the regulation of the heartbeat. The stoichiometry of KCNQ1 and KCNE1 complex has been debated, with some results suggesting that the four KCNQ1 subunits that form the channel associate with two KCNE1 subunits (a 4∶2 stoichiometry), while others have suggested that the stoichiometry may not be fixed. We applied a single molecule fluorescence bleaching method to count subunits in many individual complexes and found that the stoichiometry of the KCNQ1 - KCNE1 complex is flexible, with up to four KCNE1 subunits associating with the four KCNQ1 subunits of the channel (a 4∶4 stoichiometry). The proportion of the various stoichiometries was found to depend on the relative expression densities of KCNQ1 and KCNE1. Strikingly, both the voltage-dependence and kinetics of gating were found to depend on the relative densities of KCNQ1 and KCNE1, suggesting the heart rhythm may be regulated by the relative expression of the auxiliary subunit and the resulting stoichiometry of the channel complex.
Qualitative and quantitative assessment of meningococcal antigens to evaluate the potential strain coverage of protein-based vaccines
Authors: Donnelly John , Medini Duccio , Boccadifuoco Giuseppe , Biolchi Alessia , Ward Joel , Frasch Carl , Moxon E. Richard , Stella Maria , Comanducci Maurizio , Bambini Stefania , Muzzi Alessandro , Andrews William , Chen Jie , Santos George , Santini Laura , Boucher Philip , Serruto Davide , Pizza Mariagrazia , Rappuoli Rino , Giuliani Marzia Monica
Published: October 2010

A unique multicomponent vaccine against serogroup B meningococci incorporates the novel genome-derived proteins fHbp, NHBA, and NadA that may vary in sequence and level of expression. Measuring the effectiveness of such vaccines, using the accepted correlate of protection against invasive meningococcal disease, could require performing the serum bactericidal assay (SBA) against many diverse strains for each geographic region. This approach is impractical, especially for infants, where serum volumes are very limited. To address this, we developed the meningococcal antigen typing system (MATS) by combining a unique vaccine antigen-specific ELISA, which detects qualitative and quantitative differences in antigens, with PorA genotyping information. The ELISA correlates with killing of strains by SBA and measures both immunologic cross-reactivity and quantity of the antigens NHBA, NadA, and fHbp. We found that strains exceeding a threshold value in the ELISA for any of the three vaccine antigens had ≥80% probability of being killed by immune serum in the SBA. Strains positive for two or more antigens had a 96% probability of being killed. Inclusion of multiple different antigens in the vaccine improves breadth of coverage and prevents loss of coverage if one antigen mutates or is lost. The finding that a simple and high-throughput assay correlates with bactericidal activity is a milestone in meningococcal vaccine development. This assay allows typing of large panels of strains and prediction of coverage of protein-based meningococcal vaccines. Similar assays may be used for protein-based vaccines against other bacteria.
On using qualitative lexicostatistics to illuminate language history
Authors: Grant Anthony P.
Published: October 2010

Following certain aspects of the work on lexicostatistics carried out in the 1960s and published thereafter (Hooley 1971, Miller et al. 1971, Miller 1984) and thereby working in a tradition which has most recently been practised by Ringe et al. (1997, 2001), among others, I maintain that much of lasting value can be learned about linguistic interrelationships by using techniques which have been developed in work on qualitative (rather than merely quantitative) lexicostatistics, using character-based methods.
Phonetic comparison, varieties, and networks
Authors: Sullivan Jennifer , McMahon April
Published: October 2010

While his eponymous basic vocabulary lists and the study of language divergence may be Swadesh’s most appreciated legacies, we demonstrate that phonetic quantification of language varieties also follows very much in the tradition of Swadesh’s own work. We compare a few different measures of phonetic distance on a very small set of data from Germanic varieties, showing the influence of lexicostatistics and the relevance of Swadesh’s ‘Mesh Principle’. What we emphasise overall is that Swadesh’s influence is palpable, even in domains outside those for which he is best remembered.
All in the family
Authors: Tovares Alla V.
Published: October 2010

In recent years, narrative analysis has experienced what can be identified as a small stories turn. Specifically, some researchers, especially Bamberg (2004, 2006), Georgakopoulou (2006, 2007), Bamberg and Georgakopoulou (2008), have argued that the analysis of small stories that have been previously overlooked in favor of large-scale autobiographical narratives presents a valuable contribution to our understanding of identity construction and display. This paper builds on and extends the discussion of small stories as sites for identity construction by demonstrating how various small stories — retellings, hypothetical narratives, near-narrative structures as well as short past-oriented narratives — all construct a coherent family identity that includes pets as members. While a number of previous studies considered narrative as a key site for exploring how family members construct social identities, they primarily focused on individual family members and centered their analyses on traditional past-oriented narratives often limiting their settings to dinner-table conversations or interviews. In contrast, this study, drawing on prior studies of discursive construction of a shared family identity (Gordon, 2007) and pets as family members (Tannen, 2004), demonstrates how a shared family identity that includes pets emerges in diverse small stories that are embedded in on-going conversations and occur in a variety of places: a car, a dining room, a living room. This paper also shows how small stories about pets simultaneously create a shared family identity that includes pets and situate this family within a larger social discourse, or Discourse (Gee, 1996, 1999), of treating pets as family members.
“We had a wonderful time”
Authors: Davies Catherine Evans
Published: October 2010

Using perspectives from interactional sociolinguistics (Goffman, 1956; Gumperz, 1982, 1992; Schiffrin, 1996; Tannen, 2005) and discursive psychology (Bamberg, 1997, Davies & Harré, 1999, Wortham, 2001) this analysis demonstrates how three sisters reveal their very different personalities, styles, and stances in the collaborative narrative process, and yet come together in the end to affirm the common family ethos. The sisters’ roles in the family system are played out both in the story world and also in the interactional context of the storytelling. A distinction is made between apparently intentional self-disclosure as part of a positioning strategy of explicit evaluation, and inadvertent self-disclosure in the enactment whereby the relationships within the family system are revealed. The data will be of interest to students of narrative because (1) the context in which the data was recorded highlights the idea of a family as a community of practice; (2) the “family” consists of three unmarried sisters who had lived together for 60 years; (3) the discourse data is triangulated with ethnographic background knowledge and letters written by the siblings; (4) the shaping power of context is revealed through an immediate revision of the story by the narrator; and (5) the data provides an example of a story “abstract” being treated in two ways by the same narrator: as a “result” for which an explanation must be provided, and as a “complicating action” for which a result must be supplied.
Small stories as resources for performing teacher identity
Authors: Juzwik Mary M. , Ives Denise
Published: October 2010

This paper sets out to (a) Theorize teacher identity as fluid, dynamic, interactionally emergent in situ, (b) Operationalize a dialogic narrative approach for the study of teacher identity on these terms, and (c) Account for the locally unfolding process of teacher identity, over short periods of time, in relation to curricular content. We pursue the inquiry through multi-layered small story analysis of a narrative, “My Worst Mistake,” told by a veteran English language arts teacher in the Midwestern United States.
The relevance of narrative ratifications in talk-in-interaction for Japanese pre-service teachers of English
Authors: Rugen Brian D.
Published: October 2010

In everyday conversation, narratives are used as rhetorical tools for managing identities, allowing participants to carve out identity positions in moment-to-moment interactions. An interesting, yet understudied, focus of these narratives involves exploring the links between the discourse identities (or narrative participation roles) and larger, social identities of participants in the narrative interactions (e.g., Georgakopoulou, 2002, 2003, 2006, 2007). In this paper, I build on this work by looking specifically at the relevance of narrative ratifications for the emergent discourse and social identities of those offering the ratifications. Following Bamberg’s (1997, 2003) analytical framework for examining narratives in talk-in-interaction, I examine how participants are positioned with respect to whose contributions they choose to ratify and how their ratifications (or lack thereof) make available certain discourse identities, which may then point to larger, social identities. Findings not only demonstrate the relevance of ratifications for identity work in narrative interactions, but also advance our understanding of certain aspects of narrative structure, in particular, sequences of narrative openings in talk-in-interaction.
Ethnic categorization and moral agency in ‘fitting in’ narratives among Madrid immigrant students
Authors: Relaño Pastor Ana María
Published: October 2010

This article examines a group of ‘fitting in’ narratives told by students with different migrant backgrounds in focus group interviews. These narratives indicate shared experiences of adaptation and transformation among these students in Madrid’s multilingual/multicultural schools and Spanish society . I argue that these narratives were told in interaction and constrained by the moderators’ development of the topic-talk at hand, emerging only as answers to questions related to personal experiences of social exclusion in and outside school, as well as those related to group relations at school. They presented a pervasive use of ethnic categorization, which is analyzed in relation to narrators, the problematic event, and the moral order displayed in these narratives. As an interactional device, ethnic categorization served different purposes: (1) to index intragroup solidarity (‘we’ versus ‘other’); (2) to signal opposition and comparison among students with different migrant backgrounds (‘them’ versus ‘them’ or ‘them’ versus ‘us’); (3) to attribute different degrees of moral agency to narrative protagonists. All in all, these narratives display the moral order of school integration and open a window of understanding to the challenges faced by immigrant origin students in Spanish society.
‘Story’ — An English cultural keyword and a key interpretive tool of Anglo culture
Authors: Wierzbicka Anna
Published: October 2010

This paper shows that story is an English cultural keyword and a key interpretive tool of modern Anglo culture and that it is linked with a family of concepts which have no semantic equivalents in other languages and are unique conceptual artefacts of Anglo culture. It argues that if we can pinpoint these concepts we can also pinpoint the shared values and assumptions reflected in them. It shows that this can be done with the help of the natural semantic metalanguage (NSM) methodology developed over many years by the author and her colleague Cliff Goddard — a methodology which has been previously applied effectively to many other semantic domains, across a wide range of languages. Further, the paper argues that because the uniqueness and centrality of the English story has until now gone unnoticed, many semantic components associated with it have been projected onto other languages, which has lead to the positing of spurious human universals and to claims such as “story is a basic principle of mind”. The paper draws attention to the fact that a unique English cultural keyword (story) has played a significant role in the “narrative turn” in the humanities and social sciences, and discusses some of the implications of this fact.
Narrative research
Authors: Spector-Mersel Gabriela
Published: October 2010

As a result of the popularization of the narrative idea and the considerable diversity existing among narrative studies, a rather “all included” conception has arisen, in which the framework of narrative inquiry has been significantly blurred. For narrative inquiry to persist as a unique mode of investigation into human nature, a complementary dialogue is required that aims at outlining its core, alongside the emphasis given in the literature on diversity as its hallmark. As a possible reference point for this debate, recognizing the narrative paradigm that has crystallized since the “narrative turn” is suggested. The narrative paradigm is discussed in light of six major dimensions — ontology, epistemology, methodology, inquiry aim, inquirer posture and participant/narrator posture — indicating that it coincides with other interpretive paradigms in certain aspects yet proffers a unique philosophical infrastructure that gives rise to particular methodological principles and methods. Considering the narrative paradigm as the essence of narrative inquiry asserts that the latter is not confined to a methodology, as often implied. Rather it constitutes a full-fledged research Weltanschauung that intimately connects the “hows” of investigation to the “whats”, namely premises about the nature of reality and our relationships with it.
Prospective Evaluation of Dietary Treatment in Childhood Constipation: High Dietary Fiber and Wheat Bran Intake Are Associated With Constipation Amelioration
Authors: Maffei Helga Verena Leoni , Vicentini Andréa Pereira
Published: October 2010

Objectives:

The aim of the study was to evaluate, over 24 months, the intake of dietary fiber (DF) and the bowel habit (BH) of constipated children advised a DF‐rich diet containing wheat bran.

Patients and Methods:

BH and dietary data of 28 children with functional constipation defined by the “Boston criteria” were obtained at visit 1 (V1, n = 28) and at 4 follow‐up visits (V2–V5, n = 80). At each visit the BH was rated BAD (worse/unaltered; improved but still complications) or RECOVERY (REC) (improved, no complications; asymptomatic), and a food intake questionnaire was applied. DF intake was calculated according to age (year)+5 to 10 g/day and bran intake according to international tables. Nonparametric statistics were used.

Results:

Median age (range) was 7.25 years (0.25–15.6 years); 21 children underwent bowel washout (most before V1/V2), and 14 had the last visit at V3/V4. DF intake, bran intake, and the BH rate significantly increased at V2 and remained higher than at V1 through V2 to V5. At V1, median DF intake was 29.9% below the minimum recommended and at the last visit 49.9% above it. Twenty‐four children accepted bran at 60 visits, at which median bran intake was 20 g/day and median proportion of DF due to bran 26.9%. Children had significantly higher DF and higher bran intake at V2 to V5 at which they had REC than at those at which they presented BAD BH. DF intake >age+10 g/day was associated with bran acceptance and REC. At the last visit 21 children presented REC (75%); 20 of them were asymptomatic and 18 were off washout/laxatives.

Conclusions:

High DF and bran intake are feasible in constipated children and contribute to amelioration of constipation.