bluuebunny/crossref_metadata_2025 huggingface dataset:
On the breaking of a plasma wave in a thermal plasma. II. Electromagnetic wave interaction with the breaking plasma wave
Authors: Bulanov Sergei V. , Esirkepov Timur Zh. , Kando Masaki , Koga James K. , Pirozhkov Alexander S. , Nakamura Tatsufumi , Bulanov Stepan S. , Schroeder Carl B. , Esarey Eric , Califano Francesco , Pegoraro Francesco
Published: November 2012

In thermal plasma, the structure of the density singularity formed in a relativistically large amplitude plasma wave close to the wavebreaking limit leads to a refraction coefficient with discontinuous spatial derivatives. This results in a non-exponentially small above-barrier reflection of an electromagnetic wave interacting with the nonlinear plasma wave.
Infrared spectroscopy of HOOO and DOOO in 4He nanodroplets
Authors: Raston Paul L. , Liang Tao , Douberly Gary E.
Published: November 2012

The HOOO hydridotrioxygen radical and its deuterated analog (DOOO) have been isolated in helium nanodroplets following the in situ association reaction between OH and O2. The infrared spectrum in the 3500–3700 cm−1 region reveals bands that are assigned to the ν1 (OH stretch) fundamental and ν1 + ν6 (OH stretch plus torsion) combination band of the trans-HOOO isomer. The helium droplet spectrum is assigned on the basis of a detailed comparison to the infrared spectrum of HOOO produced in the gas phase [E. L. Derro, T. D. Sechler, C. Murray, and M. I. Lester, J. Chem. Phys. 128, 244313 (2008)10.1063/1.2945872]. Despite the characteristic low temperature and rapid cooling of helium nanodroplets, there is no evidence for the formation of a weakly bound OH-O2 van der Waals complex, which implies the absence of a kinetically significant barrier in the entrance channel of the reaction. There is also no spectroscopic evidence for the formation of cis-HOOO, which is predicted by theory to be nearly isoenergetic to the trans isomer. Under conditions that favor the introduction of multiple O2 molecules to the droplets, bands associated with larger H/DOOO-(O2)n clusters are observed shifted ∼1–10 cm−1 to the red of the trans-H/DOOO ν1 bands.
Modeling and simulation of pressure waves generated by nano-thermite reactions
Authors: Martirosyan Karen S. , Zyskin Maxim , Jenkins Charles M. , (Yuki) Horie Yasuyuki
Published: November 2012

This paper reports the modeling of pressure waves from the explosive reaction of nano-thermites consisting of mixtures of nanosized aluminum and oxidizer granules. Such nanostructured thermites have higher energy density (up to 26 kJ/cm3) and can generate a transient pressure pulse four times larger than that from trinitrotoluene (TNT) based on volume equivalence. A plausible explanation for the high pressure generation is that the reaction times are much shorter than the time for a shock wave to propagate away from the reagents region so that all the reaction energy is dumped into the gaseous products almost instantaneously and thereby a strong shock wave is generated. The goal of the modeling is to characterize the gas dynamic behavior for thermite reactions in a cylindrical reaction chamber and to model the experimentally measured pressure histories. To simplify the details of the initial stage of the explosive reaction, it is assumed that the reaction generates a one dimensional shock wave into an air-filled cylinder and propagates down the tube in a self-similar mode. Experimental data for Al/Bi2O3 mixtures were used to validate the model with attention focused on the ratio of specific heats and the drag coefficient. Model predictions are in good agreement with the measured pressure histories.
Effect of (Bi, La)(Fe, Zn)O3 thickness on the microstructure and multiferroic properties of BiFeO3 thin films
Authors: Wu Jiagang , Xiao Dingquan , Zhu Jianguo
Published: November 2012

The effect of Bi0.90La0.10Fe0.90Zn0.10O3 (BLFZO) thicknesses on the microstructure and multiferroic properties of BiFeO3 (BFO) thin films was investigated, and all bilayered thin films were grown on Pt-coated silicon substrates without any buffer layers by a radio frequency sputtering. A (110) orientation is dominant in all the bilayers, and two grain growth modes are identified in these bilayers by using an atomic force microscope, where different grain growth modes significantly affect their leakage behavior. The dielectric constant (εr) of bilayers gradually increases, and magnetic properties were deteriorated with the addition of BLFZO with a higher εr and a weaker magnetic behavior. An enhanced ferroelectric behavior of 2Pr ∼ 116.2 μC/cm2 and 2Ec ∼ 524 kV/cm could be observed in the BFO/BLFZO bilayered thin film with 80 nm BLFZO layer owing to a higher orientation degree of (110) and an interface coupling together with a lower leakage current density. As a result, electrical properties of BFO could be tailored by modifying the thicknesses of BLFZO.
Reverse Schottky gate current in AlGaN-GaN high-electron-mobility-transistors
Authors: Jos Rik
Published: November 2012

Two theoretical one-dimensional models are developed for reverse currents through Schottky gate contacts on AlGaN-GaN high-electron-mobility-transistors (HEMTs) and compared with measurement data. One model covers ideal triangular and square junction barriers and contains current contributions of thermionic emission, thermionic field emission, and tunneling of electrons from the contact metal towards the two dimensional electron gas (2-DEG) at the AlGaN-GaN interface. The second model describes the contribution of trap assisted tunneling through a Schottky barrier. Both models are compared with measurements done on AlGaN-GaN diodes at reverse voltages between threshold voltage and zero volt, which is the regime in which the current flow can be described by one-dimensional models. The trap assisted tunneling model cannot explain the data. The first model agrees with the measurements only if it is assumed that the barrier is triangular and that the current only flows through a fraction (2 × 10−4) of the junction area, probably through defect patches. The triangular barrier in the defects has a barrier height of 0.58 eV. This result is consistent with previously reported findings of defect patches at the AlGaN surface.
Defect mechanisms in the In2O3(ZnO)k system (k = 3, 5, 7, 9)
Authors: Mitchell Hopper E. , Peng Haowei , Hawks Steven A. , Freeman Arthur J. , Mason Thomas O.
Published: November 2012

The defect chemistry of several compounds in the In2O3(ZnO)k series (k = 3, 5, 7, and 9) was investigated in bulk specimens by analysis of the dependence of their conductivity on the oxygen partial pressure. The resulting Brouwer slopes were inconsistent with a doubly charged oxygen vacancy defect model, and varied with the phase. The k = 3 phase had behavior similar to donor-doped In2O3, and the behavior of the other phases resembled that of donor-doped ZnO. The donor in both cases is proposed to be In occupying Zn sites. First principles calculations of the formation energy of intrinsic defects in this system support the proposed models. The present work expands prior theoretical analysis to include acceptor defects, such as cation vacancies (VZn, VIn) and oxygen interstitials (Oi).
Second order nonlinear optical properties of AIBIIIC2VI chalcopyrite semiconductors
Authors: Kumar V. , Tripathy S. K. , Jha Vijeta
Published: November 2012

The second-order nonlinear optical (NLO) properties of ternary chalcopyrite semiconductors have been studied. The NLO tensor coefficients (d36) of the A-C and B-C bonds in AIBIIIC2VI semiconductors and their total contribution to whole family of these compounds have been calculated at 10.6 μm using plasma oscillations theory of solids. The calculated values are compared with the experimental values and the values reported by different workers. Reasonably good agreement has been found between them.
Instantons on the six-sphere and twistors
Authors: Lechtenfeld Olaf , Popov Alexander D.
Published: November 2012

We consider the six-sphere S6 = G2/SU(3) and its twistor space \documentclass[12pt]{minimal}\begin{document}${\cal Z}= G_2/$\end{document}Z=G2/U(2) associated with the SU(3)-structure on S6. It is shown that a Hermitian Yang-Mills connection (instanton) on a smooth vector bundle over S6 is equivalent to a flat partial connection on a vector bundle over the twistor space \documentclass[12pt]{minimal}\begin{document}${\cal Z}$\end{document}Z. The relation with Tian's tangent instantons on \documentclass[12pt]{minimal}\begin{document}${\mathbb {R}}^7$\end{document}R7 and their twistor description are briefly discussed.
Entanglement transformation between sets of bipartite pure quantum states using local operations
Authors: Chau H. F. , Fung Chi-Hang Fred , Li Chi-Kwong , Poon Edward , Sze Nung-Sing
Published: November 2012

Alice and Bob are given an unknown initial state chosen from a set of pure quantum states. Their task is to transform the initial state to a corresponding final pure state using local operations only. We prove necessary and sufficient conditions on the existence of such a transformation. We also provide efficient algorithms that can quickly rule out the possibility of transforming a set of initial states to a set of final states.
Inelastic collisions of the uracil molecules with electrons
Authors: Shafranyosh I. I. , Sukhoviya M. I.
Published: November 2012

Ionization and excitation of the uracil molecules by electron impact is investigated. Production of positive ions of uracil molecules (nucleic acid base) was studied using a crossed electron and molecular beam technique. The method developed by the authors enabled the molecular beam intensity to be measured and the electron dependences and the absolute values of the total cross sections of production of both positive ions to be determined. It is shown that the total positive uracil ion production cross section reaches its maximal value of (1.0 ± 0.1) × 10−15 cm2 at the 95 eV electron energy. Dissociative ionization cross sections were also determined. The luminescence spectra of isolated uracil molecules in the wavelength range of 200–500 nm under the influence of slow electrons are obtained. In the spectrum, more than 20 spectral bands and lines at 100 eV electron energy are observed. It is shown that the uracil radiation spectrum is formed by the processes of molecules dissociative excitation, dissociative excitation with ionization, excitation of electronic levels of the initial molecule and molecular ion.
Integration of a broad beam ion source with a high-temperature x-ray diffraction vacuum chamber
Authors: Manova D. , Bergmann A. , Mändl S. , Neumann H. , Rauschenbach B.
Published: November 2012

Here, the integration of a low energy, linearly variable ion beam current density, mechanically in situ adjustable broad beam ion source with a high-temperature x-ray diffraction (XRD) vacuum chamber is reported. This allows in situ XRD investigation of phase formation and evolution processes induced by low energy ion implantation. Special care has been taken to an independent adjustment of the ion beam for geometrical directing towards the substrate, a 15 mm small ion source exit aperture to avoid a secondary sputter process of the chamber walls, linearly variable ion current density by using a pulse length modulation (PLM) for the accelerating voltages without changing the ion beam density profile, nearly homogeneous ion beam distribution over the x-ray footprint, together with easily replaceable Kapton® windows for x-rays entry and exit. By combining a position sensitive x-ray detector with this PLM-modulated ion beam, a fast and efficient time resolved investigation of low energy implantation processes is obtained in a compact experimental setup.
Self-similar drag reduction in plug-flow of suspensions of macroscopic fibers
Authors: Gillissen J. J. J. , Hoving J. P.
Published: November 2012

Pipe flow experiments show that turbulent drag reduction in plug-flow of concentrated suspensions of macroscopic fibers is a self-similar function of the wall shear stress over the fiber network yield stress. We model the experimental observations, by assuming a central fiber network plug, whose radius is determined by the yield stress. According to the model the plug constrains the size of the turbulent eddies in the surrounding annulus, with the effect of a reduced friction factor as compared to Newtonian flow.
Guided atom gyroscope on an atom chip with symmetrical state-dependent microwave potentials
Authors: Yan Hui
Published: November 2012

We proposed to realize area-enclosed Raman-type atom interferometer on an atom chip based on the moving guide. Symmetrical state-dependent microwave potentials are applied to split and recombine the atoms with different internal states along the free-propagation direction of a magnetic guide, while the atoms are translated along another direction with the moving guide back and forth. For the long coherence time of the atom internal states and the moving guide scheme, compact and large area-enclosed atom gyroscope can be realized on an atom chip.
Single-crystalline BiFeO3 nanowires and their ferroelectric behavior
Authors: Li Shun , Nechache Riad , Harnagea Catalin , Nikolova Liliya , Rosei Federico
Published: November 2012

We report the ferroelectric properties of single-crystalline BiFeO3 nanowires using piezoresponse force microscopy (PFM). The nanowires, synthesized by a hydrothermal approach, have a rhombohedral perovskite structure and a preferential growth of the (211) crystallographic plane perpendicular to the wire axis, as revealed by x-ray and electron diffraction investigations. PFM measurements reveal that the as-synthesized BiFeO3 nanowires, down to 40 nm in diameter, have components of spontaneous polarization along both the axial and radial directions, thereby demonstrating the ferroelectric nature of the wires. The results indicate that such ferroelectric BiFeO3 nanowires should provide promising opportunity for nanoscale nonvolatile memory devices.
Inducing vortex formation in multilayered circular dots using remanent curves
Authors: Kim Dong-Ok , Ryeol Lee Dong , Choi Yongseong , Metlushko Vitali , Park Jihwey , Kim Jae-Young , Bong Lee Ki
Published: November 2012

We report field manipulation of magnetic vortex states in Co(30 nm)/Cu(3 nm)/Ni80Fe20 (20 nm)-multilayer dot arrays via remanent curve. The element-resolved resonant x-ray magnetic measurements, combined with micromagnetic simulations, show vortex formation in the Co layer but not in the NiFe layer along the major hysteresis loop. Although the two magnetic layers are not directly coupled due to the presence of the Cu interlayer, the NiFe layer is strongly influenced by the dipolar field from uncompensated magnetic poles in the Co layer. Using remanent curves, we demonstrate that the single vortex state can be induced simultaneously in both layers.
A multilayered-representation quantum mechanical/molecular mechanics study of the SN2 reaction of CH3Br + OH− in aqueous solution
Authors: Xu Yulong , Wang Tingting , Wang Dunyou
Published: November 2012

The bimolecular nucleophilic substitution (SN2) reaction of CH3Br and OH− in aqueous solution was investigated using a multilayered-representation quantum mechanical and molecular mechanics methodology. Reactant complex, transition state, and product complex are identified and characterized in aqueous solution. The potentials of mean force are computed under both the density function theory and coupled-cluster single double (triple) (CCSD(T)) levels of theory for the reaction region. The results show that the aqueous environment has a significant impact on the reaction process. The solvation effect and the polarization effect combined raise the activation barrier height by ∼16.2 kcal/mol and the solvation effect is the dominant contribution to the potential of mean force. The CCSD(T)/MM representation presents a free energy activation barrier height of 22.8 kcal/mol and the rate constant at 298 K of 3.7 × 10−25 cm3 molecule−1 s−1 which agree very well with the experiment values at 23.0 kcal/mol and 2.6 × 10−25 cm3 molecule−1 s−1, respectively.
Experimental evidence of foam homogenization
Authors: Nicolaï Ph. , Olazabal-Loumé M. , Fujioka S. , Sunahara A. , Borisenko N. , Gus'kov S. , Orekov A. , Grech M. , Riazuelo G. , Labaune C. , Velechowski J. , Tikhonchuk V.
Published: November 2012

The propagation of an ionization wave through a subcritical foam is studied under inertial confinement fusion conditions. Independent measurements of the ionization wave velocity are compared with hydrodynamic simulations and analytical models. It is shown that simulations of a homogeneous material at equivalent density strongly overestimate the front velocity. The internal foam structure can be accounted for with a simple model of foam homogenization that allows improving agreement between experiment and calculations.
Influence of cross-sectional geometry on the sensitivity and hysteresis of liquid-phase electronic pressure sensors
Authors: Park Yong-Lae , Tepayotl-Ramirez Daniel , Wood Robert J. , Majidi Carmel
Published: November 2012

Cross-sectional geometry influences the pressure-controlled conductivity of liquid-phase metal channels embedded in an elastomer film. These soft microfluidic films may function as hyperelastic electric wiring or sensors that register the intensity of surface pressure. As pressure is applied to the elastomer, the cross-section of the embedded channel deforms, and the electrical resistance of the channel increases. In an effort to improve sensitivity and reduce sensor nonlinearity and hysteresis, we compare the electrical response of 0.25 mm2 channels with different cross-sectional geometries. We demonstrate that channels with a triangular or concave cross-section exhibit the least nonlinearity and hysteresis over pressures ranging from 0 to 70 kPa. These experimental results are in reasonable agreement with predictions made by theoretical calculations that we derive from elasticity and Ohm's Law.
Towards the development of a virtual organic solar cell: An experimental and dynamic Monte Carlo study of the role of charge blocking layers and active layer thickness
Authors: Feron K. , Fell C. J. , Rozanski L. J. , Gong B. B. , Nicolaidis N. , Belcher W. J. , Zhou X. , Sesa E. , King B. V. , Dastoor P. C.
Published: November 2012

Monte Carlo (MC) simulations have been used to fully model organic solar cells. The quantum efficiency and short-circuit current of these virtual devices are in excellent agreement with experimental measurements. Simulations show that, contrary to expectation, indium tin oxide/poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)/poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methylester (PCBM)/aluminium devices lack effective charge blocking layers at the electrode interfaces. X-ray photoelectron spectroscopy depth profiling shows that despite a PCBM-rich region near the cathode, interface intermixing at the electrodes combined with incomplete PCBM coverage leads to significant interface recombination. This work highlights the effectiveness of MC simulations as a predictive tool and emphasizes the need to control electrode interface processes.
'A Biochemist of the Best Type': The Contribution of Arthur Cecil Hamel Rothera to Biochemistry in Australia
Authors: Flesch Juliet
Published: November 2012

Biochemistry was an early concern of physiologists and agricultural scientists in the universities of Australia. Much more is known and recorded about such early biochemists as Osborne, Robertson and Young than about Arthur Rothera, whose contribution from 1906 to 1915 is the principal focus of this paper. Rothera was the first lecturer in biochemistry in Australia, the author of a number of significant papers and, through his ketone test, is still influential in diagnosis of diabetes today. At his death, he left biochemistry at Melbourne in new laboratories, and several students able to take his place.
The effect of leaf beetle herbivory on the fire behaviour of tamarisk (Tamarix ramosissima Lebed.)
Authors: Drus Gail M. , Dudley Tom L. , Brooks Matt L. , Matchett J. R.
Published: November 2012

The non-native tree, Tamarix spp. has invaded desert riparian ecosystems in the south-western United States. Fire hazard has increased, as typically fire-resistant native vegetation is replaced by Tamarix. The tamarisk leaf beetle, Diorhabda carinulata Desbrochers, introduced for biological control, may affect fire behaviour by converting hydrated live Tamarix leaves and twigs into desiccated and dead fuels. This potentially increases fire hazard in the short term before native vegetation can be re-established. This study investigates how fire behaviour is altered in Tamarix fuels desiccated by Diorhabda herbivory at a Great Basin site, and by herbivory simulated by foliar herbicide at a Mojave Desert site. It also evaluates the influence of litter depth on fire intensity. Fire behaviour was measured with a fire intensity index that integrates temperature and duration (degree-minutes above 70°C), and with maximum temperature, duration, flame lengths, rates of spread and vegetation removal. Maximum temperature, flame length and rate of spread were enhanced by foliar desiccation of Tamarix at both sites. At only the Mojave site, there was a trend for desiccated trees to burn with greater fire intensity. At both sites, fire behaviour parameters were influenced to a greater degree by litter depth, vegetation density and drier and windier conditions than by foliar desiccation.
Assessing exposure of human and ecological values to wildfire in Sardinia, Italy
Authors: Salis Michele , Ager Alan A. , Arca Bachisio , Finney Mark A. , Bacciu Valentina , Duce Pierpaolo , Spano Donatella
Published: November 2012

We used simulation modelling to analyse spatial variation in wildfire exposure relative to key social and economic features on the island of Sardinia, Italy. Sardinia contains a high density of urban interfaces, recreational values and highly valued agricultural areas that are increasingly being threatened by severe wildfires. Historical fire data and wildfire simulations were used to estimate burn probabilities, flame length and fire size. We examined how these risk factors varied among and within highly valued features located on the island. Estimates of burn probability excluding non-burnable fuels, ranged from 0–1.92 × 10–3, with a mean value of 6.48 × 10–5. Spatial patterns in modelled outputs were strongly related to fuel loadings, although topographic and other influences were apparent. Wide variation was observed among the land parcels for all the key values, providing a quantitative approach to inform wildfire risk management activities.
Impact of copy number variations (CNVs) on long-range gene regulation at the
HoxD
locus
Authors: Montavon Thomas , Thevenet Laurie , Duboule Denis
Published: November 2012

Copy number variations are genomic structural variants that are frequently associated with human diseases. Among these copy number variations, duplications of DNA segments are often assumed to lead to dosage effects by increasing the copy number of either genes or their regulatory elements. We produced a series of large targeted duplications within a conserved gene desert upstream of the murine
HoxD
locus. This DNA region, syntenic to human 2q31-32, contains a range of regulatory elements required for
Hoxd
gene transcription, and it is often disrupted and/or reorganized in human genetic conditions collectively known as the 2q31 syndrome. Unexpectedly, one such duplication led to a transcriptional down-regulation in developing digits by impairing physical interactions between the target genes and their upstream regulatory elements, thus phenocopying the effect obtained when these enhancer sequences are deleted. These results illustrate the detrimental consequences of interrupting highly conserved regulatory landscapes and reveal a mechanism where genomic duplications lead to partial loss of function of nearby located genes.
Gating pore currents and the resting state of Na
v
1.4 voltage sensor domains
Authors: Gosselin-Badaroudine Pascal , Delemotte Lucie , Moreau Adrien , Klein Michael L. , Chahine Mohamed
Published: November 2012

Mammalian voltage-gated sodium channels are composed of four homologous voltage sensor domains (VSDs; DI, DII, DIII, and DIV) in which their S4 segments contain a variable number of positively charged residues. We used single histidine (H) substitutions of these charged residues in the Na
v
1.4 channel to probe the positions of the S4 segments at hyperpolarized potentials. The substitutions led to the formation of gating pores that were detected as proton leak currents through the VSDs. The leak currents indicated that the mutated residues are accessible from both sides of the membrane. Leak currents of different magnitudes appeared in the DI/R1H, DII/R1H, and DIII/R2H mutants, suggesting that the resting state position of S4 varies depending on the domain. Here, DI/R1H indicates the first arginine R1, in domain DI, has been mutated to histidine. The single R1H, R2H, and R3H mutations in DIV did not produce appreciable proton currents, indicating that the VSDs had different topologies. A structural model of the resting states of the four VSDs of Na
v
1.4 relaxed in their membrane/solution environment using molecular dynamics simulations is proposed based on the recent Na
v
Ab sodium channel X-ray structure. The model shows that the hydrophobic septa that isolate the intracellular and the extracellular media within the DI, DII, and DIII VSDs are ∼2 Å long, similar to those of K
v
channels. However, the septum of DIV is longer, which prevents water molecules from hydrating the center of the VSD, thus breaking the proton conduction pathway. This structural model rationalizes the activation sequence of the different VSDs of the Na
v
1.4 channel.
The tomato borer
Tuta absoluta
: insecticide resistance and control failure.
Authors: Guedes R. N. C. , Siqueira H. A. A.
Published: November 2012

The tomato borer
Tuta absoluta
(Meyrick) (Lepidoptera: Gelechiidae) evolved from a local South American concern to become a worldwide threat in tomato production less than three decades after initially spreading throughout South America, and eventually through Europe, North Africa and Middle East with an increased likelihood of invading Asia. Despite the studies performed thus far on this invasive species, management is difficult and insecticide is a major component of control. As a result, insecticide resistance has led to insecticide control failure in South America, where farmers have heavily relied on insecticide against this pest species since the 1980s. Reports from Chile, Argentina and, in particular, Brazil suggest that insecticide resistance evolves quickly in this species as a direct response to insecticide use (and overuse). Insecticide replacement for controlling the tomato borer typically leads to rapid changes in the patterns of insecticide resistance for this species. However, the resistance frequency for previously used compounds, such as pyrethroids, remains and likely results in a faster increase in resistance with selection, even in areas where this pest species was recently introduced. Recent genetic studies on the tomato borer suggest that insecticide resistance and control failure for this species in South America are also concerns elsewhere because newly introduced strains carry insecticide-resistance genes at a relatively high frequency even without local selection at the site of introduction.
A novel technique to fabricate 28 nm p-MOSFETs possessing gate oxide integrity on an embedded SiGe channel without silicon surface passivation
Authors: Yu M H , Liao M H , Huang T C , Wang L T , Lee T L , Jang S M , Cheng H C
Published: November 2012

A novel technique to create a suspending stacked gate oxide and subsequently to fill in an embedded SiGe channel (ESC) between the gate oxide and the underlying silicon substrate is proposed for the first time to fabricate 28 nm p-metal–oxide–semiconductor field-effect transistors (p-MOSFET). Without Si surface passivation on the ESC, such an ESC structure could achieve a p-FET transconductance (G
m) gain of 26% higher and a better I
on–I
off performance gain of 8% than that of conventional strained Si p-FETs with the source/drain (S/D) SiGe. Better S/D resistance (R
sd) in the resistance versus gate length plot and improved swing slope of the I
d–V
gs plot indicates higher mobility in the ESC devices. Moreover, the off-state gate current of the ESC structure is also comparable to the conventional ones. From the x-ray photoelectron spectrum analysis, only the Si–O bonding, and no Ge–O bonding at the SiGe/SiO2 interface could account for this superior gate oxide integrity for the ESC and strained Si structure. Therefore, such a novel technique with an ESC structure is very promising for the 28 nm p-MOSFET devices era.
MicroRNA-7–regulated TLR9 signaling–enhanced growth and metastatic potential of human lung cancer cells by altering the phosphoinositide-3-kinase, regulatory subunit 3/Akt pathway
Authors: Xu Lin , Wen Zhenke , Zhou Ya , Liu Zhongmin , Li Qinchuan , Fei Guangru , Luo Junmin , Ren Tao
Published: November 2012

Recent evidence shows that microRNAs (miRNAs) contribute to the biological effects of Toll-like receptor (TLR) signaling on various cells. Our previous data showed that TLR9 signaling could enhance the growth and metastatic potential of human lung cancer cells. However, the potential role of miRNAs in the effects of TLR9 signaling on tumor biology remains unknown. In this paper, we first report that TLR9 signaling could reduce intrinsic miR-7 expression in human lung cancer cells. Furthermore, overexpression of miR-7 can significantly inhibit TLR9 signaling–enhanced growth and metastatic potential of lung cancer cells in vitro and in vivo. Notably, we identify phosphoinositide-3-kinase, regulatory subunit 3 (PIK3R3) as a novel target molecule of miR-7 in lung cancer cells by Western blotting and luciferase report assay. Further study shows that miR-7 inhibits the effects of TLR9 signaling on lung cancer cells through regulation of the PIK3R3/Akt pathway. These data suggest that miR-7 could act as a fine-tuner in regulating the biological effects of TLR9 signaling on human lung cancer cells, which might be helpful to the understanding of the potential role of miRNAs in TLR signaling effects on tumor biology.
Modelling emergence of oscillations in communicating bacteria: a structured approach from one to many cells
Authors: Mina Petros , di Bernardo Mario , Savery Nigel J. , Tsaneva-Atanasova Krasimira
Published: November 2012

Population-level measurements of phenotypic behaviour in biological systems may not necessarily reflect individual cell behaviour. To assess qualitative changes in the behaviour of a single cell, when alone and when part of a community, we developed an agent-based model describing the metabolic states of a population of quorum-coupled cells. The modelling is motivated by published experimental work of a synthetic genetic regulatory network (GRN) used in
Escherichia coli
cells that exhibit oscillatory behaviour across the population. To decipher the mechanisms underlying oscillations in the system, we investigate the behaviour of the model via numerical simulation and bifurcation analysis. In particular, we study the effect of an increase in population size as well as the spatio-temporal behaviour of the model. Our results demonstrate that oscillations are possible only in the presence of a high concentration of the coupling chemical and are due to a time scale separation in key regulatory components of the system. The model suggests that the population establishes oscillatory behaviour as the system's preferred stable state. This is achieved via an effective increase in coupling across the population. We conclude that population effects in GRN design need to be taken into consideration and be part of the design process. This is important in planning intervention strategies or designing specific cell behaviours.
Toll-like receptor 7 suppresses virus replication in neurons but does not affect viral pathogenesis in a mouse model of Langat virus infection
Authors: Baker David G. , Woods Tyson A. , Butchi Niranjan B. , Morgan Timothy M. , Taylor R. Travis , Sunyakumthorn Piyanate , Mukherjee Piyali , Lubick Kirk J. , Best Sonja M. , Peterson Karin E.
Published: November 2012

Toll-like receptor 7 (TLR7) recognizes guanidine-rich viral ssRNA and is an important mediator of peripheral immune responses to several ssRNA viruses. However, the role that TLR7 plays in regulating the innate immune response to ssRNA virus infections in specific organs such as the central nervous system (CNS) is not as clear. This study examined the influence of TLR7 on the neurovirulence of Langat virus (LGTV), a ssRNA tick-borne flavivirus. TLR7 deficiency did not substantially alter the onset or incidence of LGTV-induced clinical disease; however, it did significantly affect virus levels in the CNS with a log10 increase in virus titres in brain tissue from TLR7-deficient mice. This difference in virus load was also observed following intracranial inoculation, indicating a direct effect of TLR7 deficiency on regulating virus replication in the brain. LGTV-induced type I interferon responses in the CNS were not dependent on TLR7, being higher in TLR7-deficient mice compared with wild-type controls. In contrast, induction of pro-inflammatory cytokines including tumour necrosis factor, CCL3, CCL4 and CXCL13 were dependent on TLR7. Thus, although TLR7 is not essential in controlling LGTV pathogenesis, it is important in controlling virus infection in neurons in the CNS, possibly by regulating neuroinflammatory responses.
Protease-sensitive prion species in neoplastic spleens of prion-infected mice with uncoupling of PrPSc and prion infectivity
Authors: Krasemann Susanne , Neumann Melanie , Szalay Beata , Stocking Carol , Glatzel Markus
Published: November 2012

Prion diseases are fatal neurodegenerative disorders. An important step in disease pathophysiology is the conversion of cellular prion protein (PrPC) to disease-associated misfolded conformers (PrPSc). These misfolded PrP variants are a common component of prion infectivity and are detectable in diseased brain and lymphoreticular organs such as spleen. In the latter, PrPSc is thought to replicate mainly in follicular dendritic cells within spleen follicles. Although the presence of PrPSc is a hallmark for prion disease and serves as a main diagnostic criterion, in certain instances the amount of PrPSc does not correlate well with neurotoxicity or prion infectivity. Therefore, it has been proposed that prions might be a mixture of different conformers and aggregates with differing properties. This study investigated the impact of disruption of spleen architecture by neoplasia on the abundance of different PrP species in spleens of prion-infected mice. Although follicular integrity was completely disturbed, titres of prion infectivity in neoplastic spleens were not significantly altered, yet no protease-resistant PrPSc was detectable. Instead, unique protease-sensitive prion species could be detected in neoplastic spleens. These results indicate the dissociation of PrPSc and prion infectivity and showed the presence of non-PrPSc PrP species in spleen with divergent biochemical properties that become apparent after tissue architecture disruption.
Heterogeneity of West Nile virus genotype 1a in Italy, 2011
Authors: Rossini Giada , Carletti Fabrizio , Rigoli Roberto , Piga Sandro , Bagnarelli Patrizia , Gaibani Paolo , Pierro Anna , Nanni Costa Alessandro , Grossi Paolo , Ippolito Giuseppe , Landini Maria Paola , Di Caro Antonino , Capobianchi Maria Rosaria , Sambri Vittorio
Published: November 2012

West Nile virus (WNV) is currently circulating in several European countries and, over recent decades, concomitantly with enhanced surveillance studies and improved diagnostic capabilities, an increase in the geographical distribution and in the number of cases in Europe has been documented. In Italy in 2011, 14 human cases of WNV neuroinvasive infections due to lineage 1 strains were registered in several Italian regions. Here we report WNV partial sequences obtained from serum samples of two patients living in different regions of Italy (Veneto and Sardinia). Phylogenetic analysis, performed on a fragment (566 nt) of the envelope gene, showed that WNV strains circulating in Italy in 2011 belong to lineage 1a, but are different from lineage 1a strains isolated in 2008–2009.The data reported here are consistent with the hypothesis of multiple recent introductions of WNV lineage 1a strains into Italy.
Gag sequence variation in a human immunodeficiency virus type 1 transmission cluster influences viral replication fitness
Authors: Gijsbers Esther F. , van Nuenen Ad C. , Schuitemaker Hanneke , Kootstra Neeltje A.
Published: November 2012

Three men from a proven homosexual human immunodeficiency virus type 1 (HIV-1) transmission cluster showed large variation in their clinical course of infection. To evaluate the effect of evolution of the same viral variant in these three patients, we analysed sequence variation in the capsid protein and determined the impact of the observed variation on viral replication fitnessin vitro. Viralgagsequences from all three patients contained a mutation at position 242, T242N or T242S, which have been associated with lower virus replicationin vitro. Interestingly, HIV-1 variants from patients with a progressive clinical course of infection developed compensatory mutations within the capsid that restored viral fitness, instead of reversion of the T242S mutation. In HIV-1 variants from patient 1, an HLA-B57+elite controller, no compensatory mutations emerged during follow-up.
Impact of National HIV and AIDS Communication Campaigns in South Africa to Reduce HIV Risk Behaviour
Authors: Peltzer Karl , Parker Warren , Mabaso Musawenkosi , Makonko Elias , Zuma Khangelani , Ramlagan Shandir
Published: November 2012

In South Africa social and behavioural communication interventions are a critical component of HIV/AIDS prevention, and numerous communication campaigns have been implemented intensively across the country through government initiatives and nongovernmental organisations over the past decade. The aim of this paper is to assess the reach of HIV and AIDS communication campaigns in conjunction with contributions to knowledge, attitudes, and HIV risk behaviours in the general population in South Africa. The sample included in this nationally representative cross-sectional survey was 13234 people aged 15–55 years. Overall, the study found that there was high exposure to 18 different HIV communication programmes (median 6 programmes and 14 programmes more than 30%) across different age groups. Most programmes were more often seen or heard by young people aged between 15 and 24 years. In multivariate analysis, greater exposure to HIV mass communication programmes was associated with greater HIV knowledge, condom use at last sex, having tested for HIV in the past 12 months, and less stigmatizing attitude toward PLWHA.
A Conifer ABI3-Interacting Protein Plays Important Roles during Key Transitions of the Plant Life Cycle
Authors: Zeng Ying , Zhao Tiehan , Kermode Allison R.
Published: November 2012

ABI3 (for ABSCISIC ACID INSENSITIVE3), a transcription factor of the abscisic acid signal transduction pathway, plays a major role during seed development, dormancy inception, and dormancy maintenance. This protein appears to also function in meristematic and vegetative plant tissues and under certain stress conditions. We have isolated the ABI3 gene ortholog (CnABI3) from yellow cedar (Callitropsis nootkatensis) and found that it was functionally similar to other ABI3 genes of angiosperms. Here, we report that using a yeast (Saccharomyces cerevisiae) two-hybrid approach, we have identified another protein of yellow cedar (CnAIP2; for CnABI3 INTERACTING PROTEIN2) that physically interacts with CnABI3. Functional analyses revealed that CnAIP2 plays important roles during key transitions in the plant life cycle: (1) CnAIP2 impaired seed development and reduced seed dormancy; (2) CnAIP2 promoted root development, particularly the initiation of lateral roots, and the CnAIP2 gene promoter was exquisitely auxin sensitive; and (3) CnAIP2 promoted the transition from vegetative growth to reproductive initiation (i.e. flowering). The nature of the effects of CnAIP2 on these processes and other evidence place CnAIP2 in the category of a “global” regulator, whose actions are antagonistic to those of ABI3.
X-ray study of the conformational changes in the molecule of phosphopantetheine adenylyltransferase fromMycobacterium tuberculosisduring the catalyzed reaction
Authors: Timofeev Vladimir , Smirnova Evgenia , Chupova Larisa , Esipov Roman , Kuranova Inna
Published: November 2012

Structures of recombinant phosphopantetheine adenylyltransferase (PPAT) fromMycobacterium tuberculosis(PPATMt) in the apo form and in complex with the substrate ATP were determined at 1.62 and 1.70 Å resolution, respectively, using crystals grown in microgravity by the counter-diffusion method. The ATP molecule of the PPATMt–ATP complex was located with full occupancy in the active-site cavity. Comparison of the solved structures with previously determined structures of PPATMt complexed with the reaction product dephosphocoenzyme A (dPCoA) and the feedback inhibitor coenzyme A (CoA) was performed using superposition on Cαatoms. The peculiarities of the arrangement of the ligands in the active-site cavity of PPATMt are described. The conformational states of the PPAT molecule in the consequent steps of the catalyzed reaction in the apo enzyme and the enzyme–substrate and enzyme–product complexes are characterized. It is shown that the binding of ATP and dPCoA induces the rearrangement of a short part of the polypeptide chain restricting the active-site cavity in the subunits of the hexameric enzyme molecule. The changes in the quaternary structure caused by this rearrangement are accompanied by a variation of the size of the inner water-filled channel which crosses the PPAT molecule along the threefold axis of the hexamer. The molecular mechanism of the observed changes is described.
The Debye–Scherrer camera at synchrotron sources: a revisit
Authors: Straasø Tine , Becker Jacob , Iversen Bo Brummerstedt , Als-Nielsen Jens
Published: November 2012

In a powder diffraction pattern one measures the intensity of Miller-indexed Bragg peaksversusthe wavevector transfer sinθ/λ. With increasing wavevector transfer the density of occurrence of Bragg peaks increases while their intensity decreases until they vanish into the background level. The lowest possible background level is that due to Compton scattering from the powder. A powder diffraction instrument has been designed and tested that yields this ideal low-background level, obtainable by having the space between sample and detector all in vacuum with the entrance window so far upstream that scattering from it is negligible. To minimize overlap of Bragg peaks the combination of fine collimation of synchrotron radiation, a thin cylindrical sample and a high-resolution imaging plate detector is taken advantage of.
L539 fs/47, a truncated mutation of human ether‐a‐go‐go‐related gene (hERG), decreases hERG ion channel currents in HEK 293 cells
Authors: Zhang Aifeng , Sun Chaofeng , Zhang Li , Lv Ying , Xue Xiaolin , Li Guoliang , Cui Changcong , Yan Gan‐Xin
Published: November 2012

Mutations in the human ether‐a‐go‐go‐related gene (hERG) are responsible for congenital Type 2 long QT syndrome (LQT2). Previously, we reported a truncated mutation of hERG in a Chinese family with LQT2, namely L539 fs/47, which is composed of a 19 bp deletion mutation and an A1692G polymorphism. This mutation was found to cause an LQT2 phenotype. The aim of the present study was to investigate the functional role of L539 fs/47 at the cellular level and its potential contribution to the loss of function of hERG channels.

The function of the truncated mutation L539 fs/47 was evaluated by constructing a mutated plasmid, transfection of the mutated cDNA into HEK 293 cells and subsequent patch‐clamp, western blotting and immunostaining experiments.

Homologous expression of L539 fs/47 in HEK 293 cells produced a non‐functional protein that was detected in cell membranes. When L539 fs/47 was expressed simultaneously with wild‐type hERG, it suppressed wild‐type hERG currents in a dose‐dependent manner and changed the gating properties of the channel.

Although L539 fs/47 hERG proteins were detected on plasma membranes, they failed to generate hERG currents. In general, L539 fs/47 dose‐dependently decreases hERG ion channel currents and suppresses the function of wild‐type channels function. This may explain, in part, the clinical manifestations of LQT2 in the family with this mutation.
Do Early Career Indicators of Clinical Skill Predict Subsequent Career Outcomes and Practice Characteristics for General Internists?
Authors: Gray Bradley , Reschovsky James , Holmboe Eric , Lipner Rebecca
Published: November 2012

Objective

To study relationships between clinical skill measures assessed at the beginning of general internists' careers and their career outcomes and practice characteristics.

Data Sources

General Internist Community Tracking Study Physician Survey respondents (2000–2001, 2004–2005) linked with residency program evaluations and American Board of Internal Medicine board certification examination score records; n = 2,331.

Study Design

Cross‐sectional regressions of career outcome and practice characteristic measures on board examination scores/success, residency evaluations interacted with residency type, and potential confounding variables.

Principal Findings

Failure to achieve board certification was associated with $27,206 (18 percent, p < .05) less income and 14.9 percent more minority patients relative to physicians scoring in the bottom quartile on their initial examination who eventually became certified (p < .01). Other skill measures were not associated with income. Scoring in the top rather than bottom quartile on the board certification examination was associated with 9 percent increased likelihood of reporting high career satisfaction (p < .05). Among physicians trained in community hospital residency programs, lower evaluations were associated with 14.5 percent higher share of minority patients (p < .05). Both skill measures were associated with practice type.

Conclusions

There are associations between early career skill measures and career outcomes. In addition, minority patients are more likely to be treated by physicians with lower early career clinical skills measures than nonminority patients.
Recognition by association: Within‐ and cross‐modality associative priming with faces and voices
Authors: Stevenage Sarah V. , Hale Sarah , Morgan Yasmin , Neil Greg J.
Published: November 2012

Recent literature has raised the suggestion that voice recognition runs in parallel to face recognition. As a result, a prediction can be made that voices should prime faces and faces should prime voices. A traditional associative priming paradigm was used in two studies to explore within‐modality priming and cross‐modality priming. In the within‐modality condition where both prime and target were faces, analysis indicated the expected associative priming effect: The familiarity decision to the second target celebrity was made more quickly if preceded by a semantically related prime celebrity, than if preceded by an unrelated prime celebrity. In the cross‐modality condition, where a voice prime preceded a face target, analysis indicated no associative priming when a 3‐s stimulus onset asynchrony (SOA) was used. However, when a relatively longer SOA was used, providing time for robust recognition of the prime, significant cross‐modality priming emerged. These data are explored within the context of a unified account of face and voice recognition, which recognizes weaker voice processing than face processing.