bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural insight into how Pseudomonas aeruginosa peptidoglycanhydrolase Tse1 and its immunity protein Tsi1 function
Authors: Shang Guijun , Liu Xiuhua , Lu Defen , Zhang Junbing , Li Ning , Zhu Chunyuan , Liu Shiheng , Yu Qian , Zhao Yanyu , Zhang Heqiao , Hu Junqiang , Cang Huaixing , Xu Sujuan , Gu Lichuan
Published: August 2012

Tse1 (Tse is type VI secretion exported), an effector protein produced by Pseudomonas aeruginosa, is an amidase that hydrolyses the γ-D-glutamyl-DAP (γ-D-glutamyl-L-meso-diaminopimelic acid) linkage of the peptide bridge of peptidoglycan. P. aeruginosa injects Tse1 into the periplasm of recipient cells, degrading their peptidoglycan, thereby helping itself to compete with other bacteria. Meanwhile, to protect itself from injury by Tse1, P. aeruginosa expresses the cognate immunity protein Tsi1 (Tsi is type VI secretion immunity) in its own periplasm to inactivate Tse1. In the present paper, we report the crystal structures of Tse1 and the Tse1-(6–148)–Tsi1-(20-end) complex at 1.4 Å and 1.6 Å (1 Å=0.1 nm) resolutions respectively. The Tse1 structure adopts a classical papain-like α+β fold. A cysteine–histidine catalytic diad is identified in the reaction centre of Tse1 by structural comparison and mutagenesis studies. Tsi1 binds Tse1 tightly. The HI loop (middle finger tip) from Tsi1 inserts into the large pocket of the Y-shaped groove on the surface of Tse1, and CD, EF, JK and LM loops (thumb, index finger, ring finger and little finger tips) interact with Tse1, thus blocking the binding of enzyme to peptidoglycan. The catalytic and inhibition mechanisms provide new insights into how P. aeruginosa competes with others and protects itself.
Identification of a novel malonyl-CoA IC50 for CPT-I: implications for predicting in vivo fatty acid oxidation rates
Authors: Smith Brennan K. , Perry Christopher G. R. , Koves Timothy R. , Wright David C. , Smith Jeffrey C. , Neufer P. Darrell , Muoio Deborah M. , Holloway Graham P.
Published: August 2012

Published values regarding the sensitivity (IC50) of CPT-I (carnitine palmitoyltransferase I) to M-CoA (malonyl-CoA) inhibition in isolated mitochondria are inconsistent with predicted in vivo rates of fatty acid oxidation. Therefore we have re-examined M-CoA inhibition kinetics under various P-CoA (palmitoyl-CoA) concentrations in both isolated mitochondria and PMFs (permeabilized muscle fibres). PMFs have an 18-fold higher IC50 (0.61 compared with 0.034 μM) in the presence of 25 μM P-CoA and a 13-fold higher IC50 (6.3 compared with 0.49 μM) in the presence of 150 μM P-CoA compared with isolated mitochondria. M-CoA inhibition kinetics determined in PMFs predicts that CPT-I activity is inhibited by 33% in resting muscle compared with >95% in isolated mitochondria. Additionally, the ability of M-CoA to inhibit CPT-I appears to be dependent on P-CoA concentration, as the relative inhibitory capacity of M-CoA is decreased with increasing P-CoA concentrations. Altogether, the use of PMFs appears to provide an M-CoA IC50 that better reflects the predicted in vivo rates of fatty acid oxidation. These findings also demonstrate that the ratio of [P-CoA]/[M-CoA] is critical for regulating CPT-I activity and may partially rectify the in vivo disconnect between M-CoA content and CPT-I flux within the context of exercise and Type 2 diabetes.
The Fefferman-Stein decomposition for the Constantin-Lax-Majda equation: Regularity criteria for inviscid fluid dynamics revisited
Authors: Ohkitani Koji
Published: August 2012

The celebrated Beale-Kato-Majda (BKM) criterion for the 3D Euler equations has been updated by Kozono and Taniuchi by replacing the supremum with the bounded mean oscillation norm. We consider this generalized criterion in an attempt to understand it more intuitively by giving an alternative explanation. For simplicity, we first treat the Constantin-Lax-Majda (CLM) equation \documentclass[12pt]{minimal}\begin{document}$\dfrac{\partial \omega }{\partial t}=H(\omega )\omega$\end{document}∂ω∂t=H(ω)ω for the vorticity ω in one-dimension and identify a mechanism underlying the update of such an estimate. We consider a Fefferman-Stein (FS) decomposition for the initial vorticity ω = ω0 + H[ω1] and how it propagates under the dynamics of the CLM equation. In particular, we obtain a set of dynamical equations for it, which reads in its simplest case \documentclass[12pt]{minimal}\begin{document}$\dfrac{\partial \omega _0}{\partial t} =\omega _0 H[\omega _0]-{\omega _1} H[{\omega _1}]$\end{document}∂ω0∂t=ω0H[ω0]−ω1H[ω1] and \documentclass[12pt]{minimal}\begin{document}$\dfrac{\partial {\omega _1}}{\partial t} =\omega _0 H[{\omega _1}]+{\omega _1} H[\omega _0]$\end{document}∂ω1∂t=ω0H[ω1]+ω1H[ω0]. The equation for the second component ω1, responsible for a possible logarithmic blow-up, is linear and homogeneous; hence it remains zero if it is so initially until a stronger blow-up takes place. This rules out a logarithmic blow-up on its own and underlies the generalized BKM criterion. Numerical results are also presented to illustrate how each component of the FS decomposition evolves in time. Higher dimensional cases are also discussed. Without knowing fully explicit FS decompositions for the 3D Euler equations, we show that the second component of the FS decomposition will not appear if it is zero initially, thereby precluding a logarithmic blow-up.
Concentration studies of collision-induced fundamental absorption of hydrogen dissolved in liquid neon
Authors: Herrebout W. A. , van der Veken B. J. , Kouzov A. P.
Published: August 2012

We report further and more detailed results of our recent investigation [W. A. Herrebout, B. J. van der Veken, and A. P. Kouzov, Phys. Rev. Lett. 101, 093001 (2008)]10.1103/PhysRevLett.101.093001 on the collision-induced fundamental absorption by hydrogen dissolved in liquid neon (T ≈ 25 K). The band shapes were studied in a wide range of concentrations (0.003–0.05 mole fractions) as well as for different ortho/para ratios and at much higher level of accuracy and resolution than before. Due to almost unhindered rotation of the hydrogen molecule and low temperature, an unprecedently rich frequency-domain picture produced by different terms of the interaction-induced polarization was observed. While some of them are conspicuous via fast intracell motion of a light guest (H2), others—induced by the electrostatic field of the guest—give rise to lines whose shapes are imprinted by fluctuations of the nearest surrounding. Strong motional narrowing observed on the guest-guest induced lines shows up in their Lorentzian shapes which are signatures of microscopic-scale diffusion. Near-Lorentzian peaks were also detected at the tops of the diffuse lines induced by isolated guests. Their formation may be associated with a long-living defect (vacancy) emerging in the vicinity of the polarization inductor. Altogether, our results give the first unambiguous spectroscopic evidence on the diffusional evolution of isolated binary interactions that emerge in dense chaotic media.
Vibronic coupling in asymmetric bichromophores: Theory and application to diphenylmethane
Authors: Nebgen Ben , Emmert Frank Lee , Slipchenko Lyudmila V.
Published: August 2012

The theory for modeling vibronic interactions in bichromophores was introduced in sixties by Witkowski and Moffitt [J. Chem. Phys. 33, 872 (1960)10.1063/1.1731278] and extended by Fulton and Gouterman [J. Chem. Phys. 35, 1059 (1961)10.1063/1.1701181]. The present work describes extension of this vibronic model to describe bichromophores with broken vibrational symmetry such as partly deuterated molecules. Additionally, the model is extended to include inter-chromophore vibrational modes. The model can treat multiple vibrational modes by employing Lanczos diagonalization procedure of sparse matrices. The developed vibronic model is applied to simulation of vibronic spectra of flexible bichromophore diphenylmethane and compared to high-resolution experimental spectra [J. A. Stearns, N. R. Pillsbury, K. O. Douglass, C. W. Müller, T. S. Zwier, and D. F. Plusquellic, J. Chem. Phys. 129, 224305 (2008)10.1063/1.3028543].
Electric field-induced deformation of polydimethylsiloxane polymers
Authors: Ioppolo T. , Stubblefield J. , Ötügen M. V.
Published: August 2012

The deformation of polydimethylsiloxane (PDMS) spheres under uniform external electric field was studied experimentally and analytically. In the experiments, ∼1 mm diameter PDMS spheres with base-to-curing-agent mixing ratios of 10:1 and 60:1 were exposed to uniform external electric field with varying magnitudes and poling durations. The spheres elongate along the electric field direction. For a given electric field strength, the sphere deformation is initially a time function but reaches a terminal strain value over a certain time period. This terminal strain value is larger for stronger external electric fields and larger PDMS mixing ratio spheres. At this state, the material is no longer poled and the surface charge distribution remains constant. In the analysis, an expression for the sphere deformation is obtained by modeling the PDMS as a linear elastic solid and solving the Navier equation along with Maxwell’s equations for boundary conditions. The analysis takes into account the surface charge distribution and predicts well the experimental trends.
On physical aspects of the Jiles-Atherton hysteresis models
Authors: Zirka Sergey E. , Moroz Yuriy I. , Harrison Robert G. , Chwastek Krzysztof
Published: August 2012

The physical assumptions underlying the static and dynamic Jiles-Atherton (JA) hysteresis models are critically analyzed. It is shown that the energy-balance method used in deriving these models is actually closer to a balance of coenergies, thereby depriving the resulting JA phenomenology of physical meaning. The non-physical basis of its dynamic extension is demonstrated by a sharp contrast between hysteresis loops predicted by the model and those measured for grain-oriented steel under conditions of controlled sinusoidal flux density at frequencies of 50, 100, and 200 Hz.
A new approach for the design of hypersonic scramjet inlets
Authors: Raj N. Om Prakash , Venkatasubbaiah K.
Published: August 2012

A new methodology has been developed for the design of hypersonic scramjet inlets using gas dynamic relations. The approach aims to find the optimal inlet geometry which has maximum total pressure recovery at a prescribed design free stream Mach number. The design criteria for inlet is chosen as shock-on-lip condition which ensures maximum capture area and minimum intake length. Designed inlet geometries are simulated using computational fluid dynamics analysis. The effects of 1D, 2D inviscid and viscous effects on performance of scramjet inlet are reported here. A correction factor in inviscid design is reported for viscous effects to obtain shock-on-lip condition. A parametric study is carried out for the effect of Mach number at the beginning of isolator for the design of scramjet inlets. Present results show that 2D and viscous effects are significant on performance of scramjet inlet. Present simulation results are matching very well with the experimental results available from the literature.
A link between nonlinear self-organization and dissipation in drift-wave turbulence
Authors: Manz P. , Birkenmeier G. , Ramisch M. , Stroth U.
Published: August 2012

Structure formation and self-organization in two-dimensional drift-wave turbulence show up in many different faces. Fluctuation data from a magnetized plasma are analyzed and three mechanisms transferring kinetic energy to large-scale structures are identified. Beside the common vortex merger, clustering of vortices constituting a large-scale strain field and vortex thinning, where due to the interactions of vortices of different scales larger vortices are amplified by the smaller ones, are observed. The vortex thinning mechanism appears to be the most efficient one to generate large scale structures in drift-wave turbulence. Vortex merging as well as vortex clustering are accompanied by strong energy transfer to small-scale noncoherent fluctuations (dissipation) balancing the negative entropy generation due to the self-organization process.
Thermoelectric properties of Ba8Ga16Ge30 with TiO2 nanoinclusions
Authors: Heijl R. , Cederkrantz D. , Nygren M. , Palmqvist A. E. C.
Published: August 2012

The effects on thermal and electrical properties of adding small amounts of TiO2 nanoinclusions to bulk Ba8Ga16Ge30 clathrate have been investigated. The thermal properties were analysed using the transient plane source technique and the analysis showed a significant decrease in thermal conductivity as the volume fraction of TiO2 increased from 0 vol. % to 1.2 vol. %. The introduction of TiO2 nanoparticles caused a shift in the peak value of the Seebeck coefficient towards lower temperatures. The maximum value of the Seebeck coefficient was, however, only little affected. The introduction of TiO2 nanoparticles into the bulk Ba8Ga16Ge30 resulted in an increased electrical resistivity of the sample, thus simultaneously reducing the charge carrier contribution to the thermal conductivity, partly explaining the decrease in total thermal conductivity. Due to the large increase in resistivity of the samples, ZT was only somewhat improved for the material with 0.4 vol. % TiO2 while the ZT values of the other materials were lower than for the reference Ba8Ga16Ge30 material without TiO2 nanoparticles. The combined results are consistent with a scenario where the nanoparticle introduction causes a light doping of the semiconductor matrix and an increased concentration of phonon scattering centres.
Cooperative and substitution effects in enhancing strengths of halogen bonds in FCl⋯CNX complexes
Authors: Li Qingzhong , Ma Shumin , Liu Xiaofeng , Li Wenzuo , Cheng Jianbo
Published: August 2012

In this paper, the cooperative effect of halogen bond with hydrogen bond has been used to make a halogen bond in FCl–CNH dimer vary from a chlorine-shared one to an ion-pair one. The halogen bond is strengthened in FCl–CNH–CNH trimer and its maximal interaction energy equals to −76 kJ/mol when the number of CNH in FCl–CNH–(CNH)n polymer approaches infinity. Once the free H atom in FCl–CNH–CNH trimer is replaced with alkali metals, the halogen bond becomes strong enough to be an ion-pair one in FCl–CNH–CNLi and FCl–CNH–CNNa trimers. An introduction of a Lewis acid in FCl–CNH dimer has a more prominent effect on the type of halogen bond. A prominent cooperative effect is found for the halogen bond and hydrogen bond in the trimers. FH–FCl–CNH–CNH and FH–FCl–CNH–CNLi tetramers have also been studied and the interaction energy of halogen bonding in FH–FCl–CNH–CNLi tetramer is about 12 times as much as that in the FCl–CNH dimer. The atoms in molecules and natural bond orbital analyses have been carried out for these complexes to understand the nature of halogen bond and the origin of the cooperativity.
Correspondence principle between anisotropic poroviscoelasticity and poroelasticity using micromechanics and application to compression of orthotropic rectangular strips
Authors: Hoang Son K. , Abousleiman Younane N.
Published: August 2012

In this paper, the correspondence principle between poroviscoelasticity and poroelasticity in both time domain and Laplace transform domain is established for the general case of matrix anisotropy as well as solid constituent anisotropy using micromechanics considerations. Using this correspondence principle, any constitutive relation or formula for material coefficient of linear anisotropic poroviscoelasticity can be obtained from the corresponding expression in poroelasticity. Numerical examples of the complex behavior of the poroviscoelastic Biot’s effective stress coefficient for geomaterials and biomaterials are included as illustration. Moreover, analytical solutions for initial and boundary value problems in the Laplace transform domain in poroelasticity can now be readily transferred to poroviscoelasticity and vice versa. To illustrate this technique, analytical solutions for orthotropic poroelastic rectangular strips under either unconfined compression (Mandel’s problem) or confined compression (1D consolidation problem) subjected to either time-dependent force or time-dependent displacement loading have been derived and then transferred to poroviscoelasticity herein. Finally, a biomechanics analysis of laboratory testing on orthotropic articular cartilage illustrates the usefulness of the newly derived solutions.
Influence of atomic processes on the implosion of plasma liners
Authors: Kim Hyoungkeun , Samulyak Roman , Zhang Lina , Parks Paul
Published: August 2012

The influence of atomic physics processes on the implosion of plasma liners for magneto-inertial nuclear fusion has been investigated numerically by using the method of front tracking in spherically symmetric geometry and equation of state models accounting for dissociation and ionization. Simulation studies of the self-collapse of argon liners to be used in the Los Alamos Plasma Liner Experiment (PLX) program have been performed as well as studies of implosion of deuterium and argon liners on plasma targets. Results show that atomic processes in converging liners reduce the temperature of liners and increase the Mach number that results in the increase of the stagnation pressure and the fusion energy gain. For deuterium and argon liners imploding on plasma targets, dissociation and ionization increased the stagnation pressure and the fusion energy gain by the factor of 1.5 (deuterium) and 2 (argon) correspondingly. Similarly, ionization during the self-collapse of argon liners leads to approximately doubling of the Mach number and the stagnation pressure. The influence of the longitudinal density spread of the liner has also been investigated. The self-collapse stagnation pressure decreased by the factor of 8.7 when the initial position of the liner was shifted from the merging radius (33 cm) to the PLX chamber edge (137.2 cm). Simulations with and without the heat conduction demonstrated that the heat conduction has negligible effect on the self-collapse pressure of argon liners.
Theoretical and experimental investigation of Alfa type bio mass Stirling engine with effect of regenerator effectiveness, heat transfer, and properties of working fluid
Authors: Thombare Dhananjay G. , Karmare Suhas V.
Published: August 2012

A bio mass Stirling cycle engine system with all necessary components is designed for 1 kW power output. The designed engine is simulated for air standard cycle analysis for thermodynamic performance evaluation. The relationship of cycle efficiency and power output with temperature ratio, initial pressure, and regenerator effectiveness is established. The effect of engine heat transfer, regenerator effectiveness, and properties of the working fluid on cycle performance is studied with the help of cycle simulation, and the optimum values of the temperature ratio and regeneration effectiveness are obtained. The designed and simulated engine is constructed with all necessary components and tested for validation of simulation results. The engine cycle efficiencies attained in this simulation is from 54% to 38% for corresponding regeneration effectiveness from 1 to 0.6. The temperature ratio 0.25 has shown best engine thermal performance. The results of experimentation show close association with simulation results. The results obtained by the simulation will be useful in selection of temperature range and proper working fluid for Stirling engine and will provide helpful guideline to design Stirling engine components.
Nonstationarity signatures in the dynamics of global nonlinear models
Authors: Aguirre L. A. , Letellier C.
Published: August 2012

The aim of this paper is to learn how to recognize a posteriori signatures that nonstationarity leaves on global models obtained from data. To this end the effects of nonstationarity on the dynamics of such models are reported for two benchmarks. Parameters of the Rössler and Lorenz models are varied to produce nonstationary data. It is shown that not only the rate of change of the varying parameter but also which recorded variable is used to estimate global models may have visible effects on the results, which are system-dependent and therefore difficult to generalize. Although the effects of nonstationarity are not necessarily obvious from the phase portraits, the first-return map to a Poincaré section is a much more adequate tool to recognize such effects. Three examples of models previously obtained from experimental data are analyzed in the light of the concepts discussed in this paper.
Clocking convergence to a stable limit cycle of a periodically driven nonlinear pendulum
Authors: Landauskas Mantas , Ragulskis Minvydas
Published: August 2012

Convergence to a stable limit cycle of a periodically driven nonlinear pendulum is analyzed in this paper. The concept of the H-rank of a scalar sequence is used for the assessment of transient processes of the system. The circle map is used to illustrate the complex structure of the manifold of non-asymptotic convergence to a fixed point. It is demonstrated that the manifold of non-asymptotic convergence to a stable limit cycle also exists in the stroboscopic representation of the transient data of the periodically driven nonlinear pendulum. A simple method based on a short external impulse is proposed for the control of transient processes when the transition time to stable limit cycles must be minimized.
Dielectric-solid polarization at strong fields: Breakdown of Smoluchowski's electrophoresis formula
Authors: Schnitzer Ory , Yariv Ehud
Published: August 2012

We investigate the thin-double-layer electrophoretic drift of a uniformly charged dielectric particle, driven by an intense electric field comparable to the transverse Debye-layer field. Under these circumstances, solid polarization affects the leading-order electrokinetic transport in the fluid by inducing a nonuniform zeta-potential distribution. The resulting expression for the particle velocity is accordingly nonlinear in the applied field. The electrophoretic “mobility”—the ratio of this velocity and the applied field—depends upon two parameters, the first quantifying the surface-charge density, and the second constituting the product of the solid-to-liquid permittivity ratio and the scaled applied-field magnitude. At weak values of this product, solid polarization results in field-cubed deviations from Smoluchowski's velocity; at large values of it, the particle velocity is a slowly increasing function of the applied field, essentially varying with its logarithm. The transition between these two limits features a shift from zeta-potential proportionality to a charge-density proportionality. For all values of the two governing parameters solid polarization acts so as to reduce the electrophoretic velocity relative to the Smoluchowski limit.
Overall performance evaluation using an equivalent circuit model for radio-frequency single-electron transistors
Authors: Liou Saxon , Chien Wei-Chen , Kuo Watson
Published: August 2012

Charge sensitivities of a radio-frequency single-electron transistor (RF-SET) by using amplitude (AD) and phase-shift detection (PSD) of the reflected RF signals were experimentally studied. It was found that AD is most sensitive at the resonant frequency while PSD is most sensitive at a frequency slightly off the resonance. The best PSD sensitivity is better than the best AD one when the quality factor of a tank circuit is higher than 10; the higher Q-value is, the superior PSD. The maximal change in reflection amplitude and phase-shift were found proportional to the SET conductance change. The above experimental findings were confirmed by the calculation based on an equivalent circuit model.
Spin current generator based on topological insulator coupled to ferromagnetic insulators
Authors: Ma M. J. , Jalil M. B. A. , Tan S. G. , Li Y. , Siu Z. B.
Published: August 2012

We propose a spin current generator based on a topological insulator current-in-plane spin valve, consisting of a 3D topological insulator sandwiched between two ferromagnetic insulator layers. The “on” and “off” states of the spin current can be toggled by switching the magnetization configuration of the two ferromagnetic insulator layers which are coupled to the surface states of the topological insulator.
Tribological properties of nanocrystalline diamond films deposited by hot filament chemical vapor deposition
Authors: Kumar N. , Panda K. , Dash S. , Popov C. , Reithmaier J. P. , Panigrahi B. K. , Tyagi A. K. , Raj Baldev
Published: August 2012

The dependence of the structural and morphological properties of nanocrystalline diamond films grown by hot filament chemical vapor deposition on the substrate temperature was studied. Friction coefficients of these films were measured and found to vary from high to ultra low, depending on the chemical nature of the films i.e., sp2 and sp3 phase fractions. For all films, the friction coefficient was found to decrease with increase in sp2/sp3 phase fraction. The wear rate follows the trend of the friction coefficient and was likewise found to depend on the structural and morphological properties of the films. For all the films, the friction coefficient is found to decrease with normal load which is ascribed to sliding induced surface amorphization/graphitization.
Metabolic hypothesis for human altriciality
Authors: Dunsworth Holly M. , Warrener Anna G. , Deacon Terrence , Ellison Peter T. , Pontzer Herman
Published: August 2012

The classic anthropological hypothesis known as the “obstetrical dilemma” is a well-known explanation for human altriciality, a condition that has significant implications for human social and behavioral evolution. The hypothesis holds that antagonistic selection for a large neonatal brain and a narrow, bipedal-adapted birth canal poses a problem for childbirth; the hominin “solution” is to truncate gestation, resulting in an altricial neonate. This explanation for human altriciality based on pelvic constraints persists despite data linking human life history to that of other species. Here, we present evidence that challenges the importance of pelvic morphology and mechanics in the evolution of human gestation and altriciality. Instead, our analyses suggest that limits to maternal metabolism are the primary constraints on human gestation length and fetal growth. Although pelvic remodeling and encephalization during hominin evolution contributed to the present parturitional difficulty, there is little evidence that pelvic constraints have altered the timing of birth.
Can hearing puter activate pupil? Phonological competition and the processing of reduced spoken words in spontaneous conversations
Authors: Brouwer Susanne , Mitterer Holger , Huettig Falk
Published: August 2012

In listeners' daily communicative exchanges, they most often hear casual speech, in which words are often produced with fewer segments, rather than the careful speech used in most psycholinguistic experiments. Three experiments examined phonological competition during the recognition of reduced forms such as [pjutər] for computer using a target-absent variant of the visual world paradigm. Listeners' eye movements were tracked upon hearing canonical and reduced forms as they looked at displays of four printed words. One of the words was phonologically similar to the canonical pronunciation of the target word, one word was similar to the reduced pronunciation, and two words served as unrelated distractors. When spoken targets were presented in isolation (Experiment 1) and in sentential contexts (Experiment 2), competition was modulated as a function of the target word form. When reduced targets were presented in sentential contexts, listeners were probabilistically more likely to first fixate reduced-form competitors before shifting their eye gaze to canonical-form competitors. Experiment 3, in which the original /p/ from [pjutər] was replaced with a “real” onset /p/, showed an effect of cross-splicing in the late time window. We conjecture that these results fit best with the notion that speech reductions initially activate competitors that are similar to the phonological surface form of the reduction, but that listeners nevertheless can exploit fine phonetic detail to reconstruct strongly reduced forms to their canonical counterparts.
Improved thermal and electrical properties of Al-doped Ge2Sb2Te5 films for phase-change random access memory
Authors: Wang Guoxiang , Shen Xiang , Nie Qiuhua , Wang Rongping , Wu Liangcai , Lv Yegang , Chen Fen , Fu Jing , Dai Shixun , Li Jun
Published: August 2012

Al
x
(Ge2Sb2Te5)100−x
materials with different Al contents are systemically studied for applications in phase-change random access memory (PRAM) devices. Al-doped Ge2Sb2Te5 (GST) films show better thermal stability than GST because they do not have phase transformation from face-centred cubic (fcc) to hexagonal at high annealing temperatures. As the Al content increases, the resistance in both amorphous and crystalline phases improves and there is four to five orders of magnitude difference in the resistance between the amorphous and crystalline phases, all of which are helpful in achieving a higher On/OFF ratio for PRAM. In addition, the introduction of Al into the GST films can increase the optical band gap that is favourable to decrease the threshold current of PRAM devices. Raman spectra show that a significant change in the local bonding arrangement around Sb atoms has occurred due to the phase transformation from fcc to hexagonal in the GST film but this can be suppressed by Al addition during the crystallization process. All these results confirm that Al-doped GST films are suitable for use in PRAM.
Annealing improved ductility and fracture toughness of nanocrystalline Cu films on flexible substrates
Authors: Hu K , Cao Z H , Wang L , She Q W , Meng X K
Published: August 2012

In this paper, the effect of annealing temperature (T) on the ductility of 50 nm thick nanocrystalline (NC) Cu films adhered to flexible substrates was investigated by a uniaxial tension test. It was found that the ductility and the fracture toughness (G
c) can be significantly improved through an annealing treatment. The crack onset strain of the 300 °C annealed Cu film is 18.1%, which is about twice that of the as-deposited NC Cu film. In addition, G
c of the 300 °C annealed Cu film is 1833 J m−2, which is nearly three times that of the as-deposited NC Cu film. Focused ion beam results indicate that the as-deposited film fractures with delamination and strain localization coevolving, while the as-annealed film fractures by adhering well to the substrate. At a higher T, the tensile residual stress is lower, the microstructure is more stable, and a diffusion or compound interface is generated, resulting in a better bonding between the film and the substrate. In this case, the strain localization is suppressed more effectively, causing improved ductility and G
c. Whether the film is as-deposited or as-annealed, the saturated crack spacing is about 1.41 µm, which accords well with the theoretical analysis. Intergranular fracture is suggested to be the main fracture mechanism.
An October call to arms: We Are Research!
Authors: Goldstein Lawrence S. B.
Published: August 2012

The American Society for Cell Biology is targeting the first week of October 2012 (the week before Nobel Prize winners are announced) to launch the We Are Research initiative. The goal of this initiative is to mobilize practicing junior and senior scientists, including graduate students, postdocs, and other lab members, to make contact with their elected officials and neighbors and explain to them why Federal support and investment in biomedical research is vital to the health and economic welfare of the United States. This initiative is designed to illustrate how important people are to scientific research and to supply our representatives with reliable and accurate information in the form of letters, emails, telephone calls, and personal visits.
The “study” role of past National Institutes of Health study sections
Authors: Pederson Thoru
Published: August 2012

The original National Institutes of Health (NIH) study sections had two missions. The review of grant applications was the enduring one that we all recognize. The second original function, less remembered today, was to stand ready to advise the NIH, and in fact the entire community in a given biomedical field, on the current state of that discipline, as well as to opine on what new vistas were arising and to suggest (or occasionally even launch) appropriate courses of action. The present contribution is intended to remind us of this lesser-known original function of NIH study sections. We might ponder whether today's study sections, although more overworked than Sisyphus, should again take up this second function.
Hect E3 ubiquitin ligase Tom1 controls Dia2 degradation during the cell cycle
Authors: Kim Dong-Hwan , Koepp Deanna M.
Published: August 2012

The ubiquitin proteasome system plays a pivotal role in controlling the cell cycle. The budding yeast F-box protein Dia2 is required for genomic stability and is targeted for ubiquitin-dependent degradation in a cell cycle–dependent manner, but the identity of the ubiquitination pathway is unknown. We demonstrate that the Hect domain E3 ubiquitin ligase Tom1 is required for Dia2 protein degradation. Deletion of DIA2 partially suppresses the temperature-sensitive phenotype of tom1 mutants. Tom1 is required for Dia2 ubiquitination and degradation during G1 and G2/M phases of the cell cycle, whereas the Dia2 protein is stabilized during S phase. We find that Tom1 binding to Dia2 is enhanced in G1 and reduced in S phase, suggesting a mechanism for this proteolytic switch. Tom1 recognizes specific, positively charged residues in a Dia2 degradation/NLS domain. Loss of these residues blocks Tom1-mediated turnover of Dia2 and causes a delay in G1–to–S phase progression. Deletion of DIA2 rescues a delay in the G1–to–S phase transition in the tom1Δ mutant. Together our results suggest that Tom1 targets Dia2 for degradation during the cell cycle by recognizing positively charged residues in the Dia2 degradation/NLS domain and that Dia2 protein degradation contributes to G1–to–S phase progression.
Efficacy of apixaban when compared with warfarin in relation to renal function in patients with atrial fibrillation: insights from the ARISTOTLE trial
Authors: Hohnloser Stefan H , Hijazi Ziad , Thomas Laine , Alexander John H , Amerena John , Hanna Michael , Keltai Matyas , Lanas Fernando , Lopes Renato D. , Lopez-Sendon Jose , Granger Christopher B , Wallentin Lars
Published: August 2012

Aims

Atrial fibrillation (AF) is common among patients with impaired renal function. Apixaban, a novel oral anticoagulant with partial renal excretion, was compared with warfarin and reduced the rate stroke, death and bleeding in the ARISTOTLE trial. We evaluated these outcomes in relation to renal function.

Methods and results

Baseline glomerular filtration rate (GFR) was estimated using the Cockcroft–Gault and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations as well as cystatin C measurements. According to baseline Cockcroft–Gault, there were 7518 patients (42%) with an estimated GFR (eGFR) of >80 mL/min, 7587 (42%) between >50 and 80 mL/min, and 3017 (15%) with an eGFR of ≤50 mL/min. The rate of cardiovascular events and bleeding was higher at impaired renal function (≤80 mL/min). Apixaban was more effective than warfarin in preventing stroke or systemic embolism and reducing mortality irrespective of renal function. These results were consistent, regardless of methods for GFR estimation. Apixaban was associated with less major bleeding events across all ranges of eGFRs. The relative risk reduction in major bleeding was greater in patients with an eGFR of ≤50 mL/min using Cockcroft–Gault {hazard ratio (HR) 0.50 [95% confidence interval (CI) 0.38–0.66], interaction P = 0.005} or CKD-EPI equations [HR 0.48 (95% CI 0.37–0.64), interaction P = 0.003].

Conclusion

In patients with AF, renal impairment was associated with increased risk of cardiovascular events and bleeding. When compared with warfarin, apixaban treatment reduced the rate of stroke, death, and major bleeding, regardless of renal function. Patients with impaired renal function seemed to have the greatest reduction in major bleeding with apixaban.
Extractability and Molecular Modifications of Gliadin and Glutenin Proteins Withdrawn from Different Stages of a Commercial Ethanol Fuel/Distillers Dried Grains with Solubles Process Using a Wheat Feedstock
Authors: Hong Geun‐Pyo , Avramenko Nicole , Stone Andrea , Abbott Dawn , Classen Hank , Nickerson Michael
Published: August 2012

Extractability and molecular modifications of gliadin and glutenin proteins withdrawn from different stages of a commercial ethanol fuel/distillers dried grains with solubles (DDGS) process using a wheat feedstock were investigated. Materials were taken postliquefaction (PL), postdistillation (whole stillage), and postdrying (DDGS) during the process and then fractionated to separate the gliadins and the soluble high‐ and low‐molecular‐weight glutenins following a modified Verbruggen extraction method. Each fraction was characterized based on the extraction efficiencies within various aqueous alcohols of propan‐1‐ol, electrophoretic patterns, intrinsic and extrinsic fluorescence, free and total sulfhydryl content, and total disulfide bond levels. Findings indicated significant changes to the composition of extracted proteins and modifications to the protein structure (i.e., surface properties and conformation) throughout the ethanol/DDGS process, beginning with the first step of production (PL, ≈83°C). Overall, processing resulted in a shift toward an unextractable gluten matrix, accompanied by increases in hydrophobicity, disulfide bridging, and excessive protein aggregation.
Sclerotinia Rot of Windflower (Pulsatilla koreana Nakai) Caused by Sclerotinia nivalis in China
Authors: Fu J. F. , Su D. , Zhou R. J.
Published: August 2012

Windflowers (Pulsatilla spp.) are perennial medicinal plants in the family Ranunculaceae with high economic as well as medicinal value in China. It is a commonly used traditional Chinese medicine (1). In 2012, a stem rot disease was observed on windflower (P. koreana Nakai) at flowering stages in fields of Liaoning Province, China. Disease incidence ranged from 10 to 65% (average of 45%) and resulted in approximately 25 to 60% yield loss. The infected area of plants initially takes on a dark green or brown water-soaked appearance and then becomes paler. Soon after, plants turn brown or black and die. If moisture conditions remain conducive, a cottony mycelium cover was observed on the affected area. Later, the mycelium usually produces numerous black sclerotia that were up to 1 cm long in affected plant parts. Diseased tissue were surface sterilized for 1 min in 1% NaOCl (v/v), rinsed with sterilized distilled water, and plated on potato dextrose agar (PDA). Isolates were mesophilic, with an optimum growth temperature of around 20°C. Colonies on PDA were white, with abundant aerial mycelium. Some mycelium in the colony center, especially that submerged in the medium, was light brown. Sclerotia were spherical to subspherical, elongated or fused to form irregular shapes, 2.5 to 9.0 × 2.0 to 6.8 mm. They were tightly attached to the agar surface by their under surface, which could be seen through the bottom of the petri dishes. These characteristics were consistent with Sclerotinia nivalis (2,3). Two isolates were selected for molecular identification. The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 (4) and sequenced. The obtained sequences (GenBank Accession Nos. JX206828 and JX424615) showed 99 and 100% homology with the sequences of S. nivalis in GenBank (Accession No. AB516670). To demonstrate pathogenicity, mycelial blocks of the isolates grown on PDA were placed on the base of the stems of ten 1-month-old Pulsatilla koreana plants. The same numbers of control plants were treated with PDA plugs as a control. The inoculated plants were incubated at 25°C with a 12-h photoperiod. After 4 days, the initiation of stem necrosis was observed, and 9 days after inoculation, the plants collapsed and died. Control plants had no symptoms. The same fungus was reisolated from all inoculated plants, satisfying Koch's postulates. To our knowledge, this is the first confirmed report of windflower as a natural host for S. nivalis in China.

References: (1) S. C. Bang et al. J. Nat. Prod. 68:268, 2005. (2) G. Q. Li et al. Mycol. Res. 104:232, 2000. (3) I. Saito. Mycoscience. 38:227, 1997. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.
Tie-dyed2Encodes a Callose Synthase That Functions in Vein Development and Affects Symplastic Trafficking within the Phloem of Maize Leaves
Authors: Slewinski Thomas L. , Baker R. Frank , Stubert Adam , Braun David M.
Published: August 2012

The tie-dyed2 (tdy2) mutant of maize (Zea mays) displays variegated green and yellow leaves. Intriguingly, the yellow leaf tissues hyperaccumulate starch and sucrose, the soluble sugar transported long distance through the phloem of veins. To determine the molecular basis for Tdy2 function, we cloned the gene and found that Tdy2 encodes a callose synthase. RNA in situ hybridizations revealed that in developing leaves, Tdy2 was most highly expressed in the vascular tissue. Comparative expression analysis with the vascular marker maize PINFORMED1a-yellow fluorescent protein confirmed that Tdy2 was expressed in developing vein tissues. To ascertain whether the defect in tdy2 leaves affected the movement of sucrose into the phloem or its long-distance transport, we performed radiolabeled and fluorescent dye tracer assays. The results showed that tdy2 yellow leaf regions were defective in phloem export but competent in long-distance transport. Furthermore, transmission electron microscopy of tdy2 yellow leaf regions showed incomplete vascular differentiation and implicated a defect in cell-to-cell solute movement between phloem companion cells and sieve elements. The disruption of sucrose movement in the phloem in tdy2 mutants provides evidence that the Tdy2 callose synthase functions in vascular maturation and that the vascular defects result in impaired symplastic trafficking into the phloem translocation stream.
Acyl Editing and Headgroup Exchange Are the Major Mechanisms That Direct Polyunsaturated Fatty Acid Flux into Triacylglycerols
Authors: Bates Philip D. , Fatihi Abdelhak , Snapp Anna R. , Carlsson Anders S. , Browse John , Lu Chaofu
Published: August 2012

Triacylglycerols (TAG) in seeds of Arabidopsis (Arabidopsis thaliana) and many plant species contain large amounts of polyunsaturated fatty acids (PUFA). These PUFA are synthesized on the membrane lipid phosphatidylcholine (PC). However, the exact mechanisms of how fatty acids enter PC and how they are removed from PC after being modified to participate in the TAG assembly are unclear, nor are the identities of the key enzymes/genes that control these fluxes known. By reverse genetics and metabolic labeling experiments, we demonstrate that two genes encoding the lysophosphatidylcholine acyltransferases LPCAT1 and LPCAT2 in Arabidopsis control the previously identified “acyl-editing” process, the main entry of fatty acids into PC. The lpcat1/lpcat2 mutant showed increased contents of very-long-chain fatty acids and decreased PUFA in TAG and the accumulation of small amounts of lysophosphatidylcholine in developing seeds revealed by [14C]acetate-labeling experiments. We also showed that mutations in LPCATs and the PC diacylglycerol cholinephosphotransferase in the reduced oleate desaturation1 (rod1)/lpcat1/lpcat2 mutant resulted in a drastic reduction of PUFA content in seed TAG, accumulating only one-third of the wild-type level. These results indicate that PC acyl editing and phosphocholine headgroup exchange between PC and diacylglycerols control the majority of acyl fluxes through PC to provide PUFA for TAG synthesis.
Working longer in European countries: underestimated and unexpected effects
Authors: Anxo Dominique , Ericson Thomas , Jolivet Annie
Published: August 2012

Purpose

The purpose of this paper is to analyse the main evolutions and the current situation of the 50‐74 year olds on the labour market in eight European countries (Denmark France, Germany, Italy, The Netherlands, Sweden, Poland and the UK).

Design/methodology/approach

Based on a cross‐country comparative approach, this overview draws on detailed analysis of the situation of older workers and public policies in each of the selected countries but also on a wide range of available studies and statistics on employment and welfare outcomes.

Findings

The eight selected countries display similarities: a u‐shaped pattern of employment rates of older workers (55‐64 years old) over the last 40 years, with an increase since the mid 1990s, the later exit of higher educated workers and the higher prevalence of non‐standard employment contracts among older workers. On the other hand, considerable disparities can be observed regarding the gender gap in employment rate, current employment rates, self‐employment and part‐time employment among older workers.

Social implications

Specific questions will be more acute with the effective postponement of retirement: increasing inequalities between groups of older workers, increasing uncertainty about the age of retirement, the way to keep lower educated workers in their jobs, sustainable working conditions, increasing risks of age discrimination, and impact of care of older relatives.

Originality/value

This paper offers a synthetic overview with a special attention paid to the main features of the countries’ exit patterns at the end of the working life, the prevailing public policies and the specificity of the different national employment and societal models.
Employers’ attitudes and actions towards the extension of working lives in Europe
Authors: Conen Wieteke S. , Henkens Kène , Schippers Joop
Published: August 2012

Purpose

Although policymakers have put great efforts into the promotion of older workers’ labour force participation, quantitative empirical knowledge about employers’ views towards extension of working lives is limited. The purpose of this paper is to improve the understanding of employers’ attitudes and actions towards extension of working lives, by examining recruitment and retention behaviour towards older workers, employers’ views on the consequences of an ageing workforce, organisational policies, and what governments can do to extend working lives.

Design/methodology/approach

The authors analyse surveys administered to employers in Denmark, France, Germany, Italy, The Netherlands, Poland, Sweden and the UK in 2009.

Findings

It is found that a minority of employers have applied measures to recruit or retain older workers, and employers rather retain than hire older workers. A considerable share of employers, albeit to different degrees per country, associate the ageing of their staff with a growing gap between labour costs and productivity. Employers expecting a larger gap do not apply more organisational measures to either increase productivity or adjust the cost‐productivity balance. Employers may think the cost‐productivity issue is partly for governments to solve; employers expecting a larger cost‐productivity gap consider wage subsidies to be an effective measure to extend working lives.

Originality/value

The paper addresses the employers’ perspective, one that is often neglected compared to attitudes and behaviour of older workers themselves and research on institutional arrangements. This paper is also among the first to report on employers’ policies and practices from a cross‐national perspective.