bluuebunny/crossref_metadata_2025 huggingface dataset:
The energy pump and the origin of the non-equilibrium flux of the dynamical systems and the networks
Authors: Xu Liufang , Shi Hualin , Feng Haidong , Wang Jin
Published: April 2012

The global stability of dynamical systems and networks is still challenging to study. We developed a landscape and flux framework to explore the global stability. The potential landscape is directly linked to the steady state probability distribution of the non-equilibrium dynamical systems which can be used to study the global stability. The steady state probability flux together with the landscape gradient determines the dynamics of the system. The non-zero probability flux implies the breaking down of the detailed balance which is a quantitative signature of the systems being in non-equilibrium states. We investigated the dynamics of several systems from monostability to limit cycle and explored the microscopic origin of the probability flux. We discovered that the origin of the probability flux is due to the non-equilibrium conditions on the concentrations resulting energy input acting like non-equilibrium pump or battery to the system. Another interesting behavior we uncovered is that the probabilistic flux is closely related to the steady state deterministic chemical flux. For the monostable model of the kinetic cycle, the analytical expression of the probabilistic flux is directly related to the deterministic flux, and the later is directly generated by the chemical potential difference from the adenosine triphosphate (ATP) hydrolysis. For the limit cycle of the reversible Schnakenberg model, we also show that the probabilistic flux is correlated to the chemical driving force, as well as the deterministic effective flux. Furthermore, we study the phase coherence of the stochastic oscillation against the energy pump, and argue that larger non-equilibrium pump results faster flux and higher coherence. This leads to higher robustness of the biological oscillations. We also uncovered how fluctuations influence the coherence of the oscillations in two steps: (1) The mild fluctuations influence the coherence of the system mainly through the probability flux while maintaining the regular landscape topography. (2) The larger fluctuations lead to flat landscape and the complete loss of the stability of the whole system.
Low-power, fast, selective nanoparticle-based hydrogen sulfide gas sensor
Authors: Mickelson William , Sussman Allen , Zettl Alex
Published: April 2012

We demonstrate a small, low-cost, low-power, highly sensitive, and selective nanomaterials-based gas sensor. A network of tungsten oxide nanoparticles is heated by an on-chip microhotplate while the conductance of the network is monitored. The device can be heated with short pulses, thereby drastically lowering the power consumption, without diminishing the sensor response. The sensor shows high sensitivity to hydrogen sulfide and does not have significant cross sensitivities to hydrogen, water, or methane, gases likely to be present in operation. A sensing mechanism is proposed, and its effect on electronic properties is discussed.
Growth of (111)-oriented BaTiO3–Bi(Mg0.5Ti0.5)O3 epitaxial films and their crystal structure and electrical property characterizations
Authors: Tanaka Hidenori , Chentir Mohamed-Tahar , Yamada Tomoaki , Yasui Shintaro , Ehara Yoshitaka , Yamato Keisuke , Kashiwagi Yuta , Ngeah Theng Chua , Wang Junling , Okamura Soichiro , Uchida Hiroshi , Iijima Takashi , Wada Satoshi , Funakubo Hiroshi
Published: April 2012

Epitaxial (1−x)BaTiO3−xBi(Mg0.5Ti0.5)O3 films with x = 0 − 0.9 were grown on (111)cSrRuO3//(111)SrTiO3 substrates by pulsed laser deposition (PLD). Plotting the temperature where dielectric constant reaches a maximum {T[ɛr(max.)]} versus Bi(Mg0.5,Ti0.5)O3 content present minimum at x = 0.1. On the other hand, the remanent polarization (Pr) and the effective transverse piezoelectric constant [d33(eff.)] showed minimum at 0.1 and 0.2, respectively, but increased with the increase of x in (1−x)BaTiO3−xBi(Mg0.5Ti0.5)O3 above these values. These results show the simultaneous increase of T[ɛr(max.)] and d33(eff.) for the films above x = 0.2 that normally showed treads off characteristics.
Employing pre-stress to generate finite cloaks for antiplane elastic waves
Authors: Parnell William J. , Norris Andrew N. , Shearer Tom
Published: April 2012

It is shown that nonlinear elastic pre-stress of neo-Hookean hyperelastic materials can be used as a mechanism to generate finite cloaks and thus render objects near-invisible to incoming antiplane elastic waves. This approach appears to negate the requirement for special cloaking metamaterials with inhomogeneous and anisotropic material properties in this case. These properties are induced naturally by virtue of the pre-stress. This appears to provide a mechanism for broadband cloaking since dispersive effects due to metamaterial microstructure will not arise.
Paramecium swimming in capillary tube
Authors: Jana Saikat , Um Soong Ho , Jung Sunghwan
Published: April 2012

Swimming organisms in their natural habitat need to navigate through a wide range of geometries and chemical environments. Interaction with boundaries in such situations is ubiquitous and can significantly modify the swimming characteristics of the organism when compared to ideal laboratory conditions. We study the different patterns of ciliary locomotion in glass capillaries of varying diameter and characterize the effect of the solid boundaries on the velocities of the organism. Experimental observations show that Paramecium executes helical trajectories that slowly transition to straight lines as the diameter of the capillary tubes decreases. We predict the swimming velocity in capillaries by modeling the system as a confined cylinder propagating longitudinal metachronal waves that create a finite pressure gradient. Comparing with experiments, we find that such pressure gradient considerations are necessary for modeling finite sized ciliary organisms in restrictive geometries.
The lowest-lying electronic singlet and triplet potential energy surfaces for the HNO–NOH system: Energetics, unimolecular rate constants, tunneling and kinetic isotope effects for the isomerization and dissociation reactions
Authors: Bozkaya Uğur , Turney Justin M. , Yamaguchi Yukio , Schaefer Henry F.
Published: April 2012

The lowest-lying electronic singlet and triplet potential energy surfaces (PES) for the HNO–NOH system have been investigated employing high level ab initio quantum chemical methods. The reaction energies and barriers have been predicted for two isomerization and four dissociation reactions. Total energies are extrapolated to the complete basis set limit applying focal point analyses. Anharmonic zero-point vibrational energies, diagonal Born-Oppenheimer corrections, relativistic effects, and core correlation corrections are also taken into account. On the singlet PES, the 1HNO \documentclass[12pt]{minimal}\begin{document}$\longrightarrow$\end{document}→ 1NOH endothermicity including all corrections is predicted to be 42.23 ± 0.2 kcal mol−1. For the barrierless decomposition of 1HNO to H + NO, the dissociation energy is estimated to be 47.48 ±  0.2 kcal mol−1. For 1NOH \documentclass[12pt]{minimal}\begin{document}$\longrightarrow$\end{document}→ H + NO, the reaction endothermicity and barrier are 5.25 ±  0.2 and 7.88 ± 0.2 kcal mol−1. On the triplet PES the reaction energy and barrier including all corrections are predicted to be 7.73 ±  0.2 and 39.31 ± 0.2 kcal mol−1 for the isomerization reaction 3HNO \documentclass[12pt]{minimal}\begin{document}$\longrightarrow$\end{document}→ 3NOH. For the triplet dissociation reaction (to H + NO) the corresponding results are 29.03 ±  0.2 and 32.41 ± 0.2 kcal mol−1. Analogous results are 21.30 ± 0.2 and 33.67 ± 0.2 kcal mol−1 for the dissociation reaction of 3NOH (to H + NO). Unimolecular rate constants for the isomerization and dissociation reactions were obtained utilizing kinetic modeling methods. The tunneling and kinetic isotope effects are also investigated for these reactions. The adiabatic singlet–triplet energy splittings are predicted to be 18.45 ± 0.2 and 16.05 ± 0.2 kcal mol−1 for HNO and NOH, respectively. Kinetic analyses based on solution of simultaneous first-order ordinary-differential rate equations demonstrate that the singlet NOH molecule will be difficult to prepare at room temperature, while the triplet NOH molecule is viable with respect to isomerization and dissociation reactions up to 400 K. Hence, our theoretical findings clearly explain why 1NOH has not yet been observed experimentally.
Dissipation mechanisms in thermomechanically driven silicon nitride nanostrings
Authors: Suhel A. , Hauer B. D. , Biswas T. S. , Beach K. S. D. , Davis J. P.
Published: April 2012

High-stress silicon nitride nanostrings are a promising system for sensing applications because of their ultra-high mechanical quality factors (Qs). By performing thermomechanical calibration across multiple vibrational modes, we are able to assess the roles of the various dissipation mechanisms in these devices. Specifically, we possess a set of nanostrings in which all measured modes fall upon a single curve of peak displacement versus frequency. This allows us to rule out bulk bending and intrinsic loss mechanisms as dominant sources of dissipation and to conclude that the most significant contribution to dissipation in high-stress nanostrings occurs at the anchor points.
Reducing spin torque switching current density by boron insertion into a CoFeB free layer of a magnetic tunnel junction
Authors: Jiang Xin , Moriya Rai , Parkin Stuart
Published: April 2012

The spin torque switching current density is measured for magnetic tunnel junctions containing a CoFeB free layer. We find that the insertion of an ultra-thin boron layer near the free layer/tunnel barrier interface gives rise to an increased resistance-area product and to a reduction in the switching current density. This is attributed to a lower tunneling matrix element near the inserted boron. As a result, the injected current is concentrated within smaller areas of the free layer, which leads to an overall decrease in the switching current density.
Nanocomposites of TiO2 and double-walled carbon nanotubes for improved dye-sensitized solar cells
Authors: Khamwannah Jirapon , Noh Sun Young , Frandsen Christine , Zhang Yanyan , Kim Hyunsu , Kong Seong Deok , Jin Sungho
Published: April 2012

It is demonstrated that an incorporation of double-walled carbon nanotubes (DWCNTs) into a TiO2 photo-anode layer results in a significant improvement in the overall energy conversion performance in the dye-sensitized solar cell (DSSC). Comparing to the standard TiO2 anode, the carbon nanotube-containing TiO2 anode with 0.2 wt. % DWCNTs has boosted up the photocurrent density (Jsc) by 43%. The DSSC power conversion efficiency was also improved from ∼3.9% in the case of carbon nanotube-free TiO2 anode to as high as 6.4% with the addition of DWCNTs upon optimized anode annealing. The observed enhancement in the solar cell performance in the presence of the carbon nanotubes is attributed primarily to the noticeable reduction in microcracking and associated robust electrical conduction. Some contribution of the electrical conducting nature of the filler material (DWCNTs) to the improved DSSC properties may be possible; however, it is viewed as a minor effect, considering the small amount of the nanotubes used.
Deflection switching of a laser beam by the Pockels effect of water
Authors: Yukita Shunpei , Shiokawa Naoyuki , Kanemaru Hiroki , Namiki Hajime , Kobayashi Takayoshi , Tokunaga Eiji
Published: April 2012

Deflection of a laser beam in response to an electric field was detected with a Sagnac interferometer. A laser beam was aligned to travel between two electrodes immersed in aqueous electrolyte solution. When the alternating electric field was applied perpendicular to the beam axis, the direction of the beam deflection was switched synchronously with the field alternation as expected for the Pockels effect. Broken inversion symmetry is prerequisite to the linear electrooptic effect, but surprisingly the effect was observed even when the laser beam travels through the bulk water a few millimeters away from the electrode surface.
Nanoscale spin wave valve and phase shifter
Authors: Au Y. , Dvornik M. , Dmytriiev O. , Kruglyak V. V.
Published: April 2012

We have used micromagnetic simulations to demonstrate a method for controlling the amplitude and phase of spin waves propagating inside a magnonic waveguide. The method employs a nanomagnet formed on top of a magnonic waveguide. The function of the proposed device is controlled by defining the static magnetization direction of the nanomagnet. The result is a valve or phase shifter for spin waves, acting as the carrier of information for computation or data processing within the emerging spin wave logic architectures of magnonics. The proposed concept offers such technically important benefits as energy efficiency, non-volatility, and miniaturization.
Doping characterization for germanium-based microelectronics and photovoltaics using the differential Hall technique
Authors: Bennett N. S. , Cowern N. E. B.
Published: April 2012

In this coming decade, complementary metal-oxide-semiconductor microelectronic devices may undergo a major change with the implementation of germanium channels. Likewise, the performance of photovoltaic cells based on elemental semiconductors will continue to be optimized. Both technologies will rely on a detailed and thorough understanding of electrical properties, and here, precise doping characterization will play a key role. The differential Hall technique combines resistivity and Hall-effect measurements with successive surface layer removal, allowing one to measure independent carrier concentration and mobility depth profiles. In this Letter, we apply the technique for both microelectronic- and photovoltaic-relevant doping structures in germanium. Controllable and uniform layer removal is achieved with tailored depth resolution (<1–20 nm) for a range of doping structures (30–600 nm).
Strain-induced composition limitation in nitrogen δ-doped (In,Ga)As/GaAs quantum wells
Authors: Gargallo-Caballero R. , Luna E. , Ishikawa F. , Trampert A.
Published: April 2012

The local element distribution across tensile-strained N δ-doped (In,Ga)As/GaAs quantum wells (QWs) is investigated by transmission electron microscopy. The sub-monolayer (ML) insertion results in a several monolayers thick (In,Ga)(As,N) layer with lateral composition fluctuations. We also find an inhomogeneous In incorporation across the QW, with a minimum In content, [In]min, exactly at the position of the N-insertion, where N content is maximum, [N]max. Regardless of the position along the QW, [N]max corresponds to [In]min so that an (In,Ga)(As,N) layer of this composition has a lattice parameter close to aGaAs. The impact of tensile strain on this complex chemical configuration is discussed.
Double embedded photonic crystals for extraction of guided light in light-emitting diodes
Authors: Jewell Jason , Simeonov Dobri , Huang Shih-Chieh , Hu Yan-Ling , Nakamura Shuji , Speck James , Weisbuch Claude
Published: April 2012

Light-emitting diodes (LEDs) were fabricated in gallium nitride with two embedded photonic crystals (PhCs), creating a waveguide with a highly confined, strongly excited, and well-extracted fundamental mode. This structure improves upon previous PhC LED designs by reducing the extraction length of the fundamental mode and establishing a path to designs with very low absorption losses. Optical output was measured with angular-resolved electroluminescence. The extraction length of the fundamental mode was measured to be 21–39 μm along the PhCs’ Γ-M directions, which is much shorter than values reported for single-PhC devices. This structure opens the way to more efficient LEDs and lasers.
High-pressure electrical transport properties of KNbO3: Experimental and theoretical approaches
Authors: Wang Qinglin , Han Yonghao , Liu Cailong , Ma Yanzhang , Ren Wanbin , Gao Chunxiao
Published: April 2012

Pressure-induced electrical transport properties of KNbO3 including resistance, relaxation frequency, and relative permittivity have been investigated under pressure up to 30.6 GPa by in situ impedance spectroscopy measurement. The results indicate that the discontinuous changes of these physical parameters occur around the structural phase transition pressure. The decrease of activation energy with increasing pressure reveals that the vibration damping of Nb-O dipoles is weakened in the orthorhombic and the tetragonal phases. The density of states and difference charge density calculations show that the pressure-induced charge transfer between the Nb and O atoms causes the relative permittivity change of KNbO3.
Enhanced adhesion with pedestal-shaped elastomeric stamps for transfer printing
Authors: Kim Seok , Carlson Andrew , Cheng Huanyu , Lee Seungwoo , Park Jung-Ki , Huang Yonggang , Rogers John A.
Published: April 2012

Microscale elastomeric relief structures with “pedestal” shapes provide enhanced operation in stamps designed for deterministic materials assembly via transfer printing. Experimental measurements of adhesion and finite element analysis both show that for certain geometries, exceptionally large enhancements in adhesion strength (over 15×) can be achieved. Transfer printing of microscale platelets of silicon and ultrathin gallium nitride light emitting diodes onto a silicon substrate without adhesive coatings demonstrates some capabilities in assembly that result from this type of stamp, of interest in diverse applications, including those that involve heterogeneous materials integration.
Ultraviolet electroluminescence from ordered ZnO nanorod array/p-GaN light emitting diodes
Authors: Dong J. J. , Zhang X. W. , Yin Z. G. , Wang J. X. , Zhang S. G. , Si F. T. , Gao H. L. , Liu X.
Published: April 2012

The highly ordered and aligned ZnO nanorod arrays were grown on p-GaN substrates via a facile hydrothermal process assisted by the inverted self-assembled monolayer template, from which the ZnO nanorod/p-GaN heterojunction light emitting diodes (LEDs) were fabricated. The ZnO nanorod-based LEDs exhibit a stronger ultraviolet emission of 390 nm than the ZnO film-based counterpart, which is attributed to the low density of interfacial defects, the improved light extraction efficiency, and carrier injection efficiency through the nano-sized junctions. Furthermore, the LED with the 300 nm ZnO nanorods has a better electroluminescence performance compared with the device with the 500 nm nanorods.
A new type of low temperature conductivity in InSb doped with Mn
Authors: Obukhov Sergey A.
Published: April 2012

We investigated unusual low temperature transport properties of InSb single crystals doped with manganese to concentrations in the range of 1017<NMn<2*1017cm-3 which includes the critical concentration for metal-insulator transition Ncr= 2*1017cm-3. It was found that in the temperature range T=10÷1.5K the resisitivity had an unusual behavior described by an exponential quadratic function ρ ∼ exp(Δ1/kT)2 where Δ1 varied from Δ1=0.3meV to Δ1=0. Coexistence of electrons and holes at temperatures around the metal-insulator transition in p-InSb(Mn) crystals gives the ground to explain the unusual temperature - resistivity dependence in the framework of excitonic insulator phase model (L. V. Keldysh and Yu. V. Kopaev, Sov. Phys. Solid State 6, 2219 (1965)).
Effects of Memory Colour on Colour Constancy for Unknown Coloured Objects
Authors: Granzier Jeroen J M , Gegenfurtner Karl R
Published: April 2012

The perception of an object's colour remains constant despite large variations in the chromaticity of the illumination—colour constancy. Hering suggested that memory colours, the typical colours of objects, could help in estimating the illuminant's colour and therefore be an important factor in establishing colour constancy. Here we test whether the presence of objects with diagnostical colours (fruits, vegetables, etc) within a scene influence colour constancy for unknown coloured objects in the scene. Subjects matched one of four Munsell papers placed in a scene illuminated under either a reddish or a greenish lamp with the Munsell book of colour illuminated by a neutral lamp. The Munsell papers were embedded in four different scenes—one scene containing diagnostically coloured objects, one scene containing incongruent coloured objects, a third scene with geometrical objects of the same colour as the diagnostically coloured objects, and one scene containing non-diagnostically coloured objects (eg, a yellow coffee mug). All objects were placed against a black background. Colour constancy was on average significantly higher for the scene containing the diagnostically coloured objects compared with the other scenes tested. We conclude that the colours of familiar objects help in obtaining colour constancy for unknown objects.
Two distinct overstretched DNA structures revealed by single-molecule thermodynamics measurements
Authors: Zhang Xinghua , Chen Hu , Fu Hongxia , Doyle Patrick S. , Yan Jie
Published: April 2012

Double-stranded DNA is a dynamic molecule whose structure can change depending on conditions. While there is consensus in the literature about many structures DNA can have, the state of highly-stretched DNA is still not clear. Several groups have shown that DNA in the torsion-unconstrained B-form undergoes an “overstretching” transition at a stretching force of around 65 pN, which leads to approximately 1.7-fold elongation of the DNA contour length. Recent experiments have revealed that two distinct structural transitions are involved in the overstretching process: (
i
) a hysteretic “peeling” off one strand from its complementary strand, and (
ii
) a nonhysteretic transition that leads to an undetermined DNA structure. We report the first simultaneous determination of the entropy (Δ
S
) and enthalpy changes (Δ
H
) pertaining to these respective transitions. For the hysteretic peeling transition, we determined Δ
S
 ∼ 20 cal/(K.mol) and Δ
H
 ∼ 7 kcal/mol. In the case of the nonhysteretic transition, Δ
S
 ∼ -3 cal/(K.mol) and Δ
H
 ∼ 1 kcal/mol. Furthermore, the response of the transition force to salt concentration implies that the two DNA strands are spatially separated after the hysteretic peeling transition. In contrast, the corresponding response after the nonhysteretic transition indicated that the strands remained in close proximity. The selection between the two transitions depends on DNA base-pair stability, and it can be illustrated by a multidimensional phase diagram. Our results provide important insights into the thermodynamics of DNA overstretching and conformational structures of overstretched DNA that may play an important role in vivo.
Conserved and essential transcription factors for cellulase gene expression in ascomycete fungi
Authors: Coradetti Samuel T. , Craig James P. , Xiong Yi , Shock Teresa , Tian Chaoguang , Glass N. Louise
Published: April 2012

Rational engineering of filamentous fungi for improved cellulase production is hampered by our incomplete knowledge of transcriptional regulatory networks. We therefore used the model filamentous fungus
Neurospora crassa
to search for uncharacterized transcription factors associated with cellulose deconstruction. A screen of a
N. crassa
transcription factor deletion collection identified two uncharacterized zinc binuclear cluster transcription factors (
clr-1
and
clr-2
) that were required for growth and enzymatic activity on cellulose, but were not required for growth or hemicellulase activity on xylan. Transcriptional profiling with next-generation sequencing methods refined our understanding of the
N. crassa
transcriptional response to cellulose and demonstrated that
clr-1
and
clr-2
were required for the bulk of that response, including induction of all major cellulase and some major hemicellulase genes. Functional CLR-1 was necessary for expression of
clr-2
and efficient cellobiose utilization. Phylogenetic analyses showed that CLR-1 and CLR-2 are conserved in the genomes of most filamentous ascomycete fungi capable of degrading cellulose. In
Aspergillus nidulans
, a strain carrying a deletion of the
clr-2
homolog (
clrB
) failed to induce cellulase gene expression and lacked cellulolytic activity on Avicel. Further manipulation of this control system in industrial production strains may significantly improve yields of cellulases for cellulosic biofuel production.
Detecting Invasive Round Goby in Wadeable Streams: A Comparison of Gear Types
Authors: Nett Joseph H. G. , Campbell Timothy B. , Mandrak Nicholas E. , Tiegs Scott D.
Published: April 2012

The invasion of round goby Neogobius melanostomus into tributaries of the Laurentian Great Lakes poses concerns for the conservation of native fish communities and the functioning of stream ecosystems. In streams, where standard methods for detection are lacking, development of sensitive sampling methods to identify round goby-invaded sites is a prerequisite for the implementation of effective management strategies. We sampled 34 stream sites that spanned a range of goby densities with two active gears (electrofishing and seining) and one passive gear (minnow traps) to compare gear efficiency at detecting invasive round goby. Naive occupancy, defined as the number of sites where goby were detected with each gear divided by the total number of sites, was 0.79 (27/34 sites) for seining, 0.68 (23/34) for electrofishing, and 0.50 (17/34) for traps. The probability of detecting a single round goby in a single pass (determined with single-season, constant-probability models) was 0.75 ± 0.065 (mean ± SE) for minnow traps, 0.69 ± 0.056 for seining, and 0.47 ± 0.075 for electrofishing. Mean ± SE catch per unit effort (CPUE; round goby/min) was 0.716 + 0.158 for seining, 0.137 ± 0.043 for electrofishing, and 0.078 ± 0.022 for minnow traps, seining being significantly more efficient than minnow traps and electrofishing. The CPUE did not differ between electrofishing and traps. Mean goby size did not differ among gear types, but a size bias was detected when data from a related study were included in the analysis, seining capturing smaller round goby. Based on the sensitivity and efficiency of seining, we conclude that when stream conditions allow, this gear is a practical means of detecting round goby and determining their abundance in streams.

Received August 11, 2011; accepted January 4, 2012
Predicting foreign-accent adaptation in older adults
Authors: Janse Esther , Adank Patti
Published: April 2012

We investigated comprehension of and adaptation to speech in an unfamiliar accent in older adults. Participants performed a speeded sentence verification task for accented sentences: one group upon auditory-only presentation, and the other group upon audiovisual presentation. Our questions were whether audiovisual presentation would facilitate adaptation to the novel accent, and which cognitive and linguistic measures would predict adaptation. Participants were therefore tested on a range of background tests: hearing acuity, auditory verbal short-term memory, working memory, attention-switching control, selective attention, and vocabulary knowledge. Both auditory-only and audiovisual groups showed improved accuracy and decreasing response times over the course of the experiment, effectively showing accent adaptation. Even though the total amount of improvement was similar for the auditory-only and audiovisual groups, initial rate of adaptation was faster in the audiovisual group. Hearing sensitivity and short-term and working memory measures were associated with efficient processing of the novel accent. Analysis of the relationship between accent comprehension and the background tests revealed furthermore that selective attention and vocabulary size predicted the amount of adaptation over the course of the experiment. These results suggest that vocabulary knowledge and attentional abilities facilitate the attention-shifting strategies proposed to be required for perceptual learning.
The Effects of Ageing and Visual Noise on Conceptual Integration during Sentence Reading
Authors: Gao Xuefei , Levinthal Brian R. , Stine-Morrow Elizabeth A. L.
Published: April 2012

The effortfulness hypothesis implies that difficulty in decoding the surface form, as in the case of age-related sensory limitations or background noise, consumes the attentional resources that are then unavailable for semantic integration in language comprehension. Because ageing is associated with sensory declines, degrading of the surface form by a noisy background can pose an extra challenge for older adults. In two experiments, this hypothesis was tested in a self-paced moving window paradigm in which younger and older readers’ online allocation of attentional resources to surface decoding and semantic integration was measured as they read sentences embedded in varying levels of visual noise. When visual noise was moderate (Experiment 1), resource allocation among young adults was unaffected but older adults allocated more resources to decode the surface form at the cost of resources that would otherwise be available for semantic processing; when visual noise was relatively intense (Experiment 2), both younger and older participants allocated more attention to the surface form and less attention to semantic processing. The decrease in attentional allocation to semantic integration resulted in reduced recall of core ideas in both experiments, suggesting that a less organized semantic representation was constructed in noise. The greater vulnerability of older adults at relatively low levels of noise is consistent with the effortfulness hypothesis.
Synthesis of Y3Al5O12 : Ce3+ phosphors by a modified impinging stream method: a crystal growth and luminescent properties study
Authors: Zhou Zhi , Liu Suqin , Wang Fengchao , Liu Younian
Published: April 2012

A Y3Al5O12 : Ce3+ (YAG : Ce3+) phosphor was successfully prepared by a modified impinging stream (IS) method at a temperature of 1200 °C. The as-obtained sample has perfect crystallinity, uniform morphology and good dispersion due to the added size classification (SC) process and low-temperature calcination. The mechanism of YAG : Ce3+ crystal growth was proposed based on the results of scanning electron microscopy and x-ray diffractometry, which agreed with the Ostwald ripening process. The excitation and emission spectra revealed that the excitation band distributes between 310 nm and 520 nm and peaks at 342 nm and 460 nm, and the emission band covers from 470 nm to 650 nm and centres at 532.5 nm, respectively. White light can be obtained from the fabricated light-emitting diodes using the prepared phosphor, and the CIE coordinate, correlated colour temperature and luminescence efficiency are (0.312, 0.321), 7560 K and 80.7 lm W−1, respectively. All the results indicated that the modified IS method is a promising way to prepare the YAG : Ce3+ phosphor, and SC process is effective in producing the phosphor with uniform morphology, ideal size and size distribution. This method has a broad industrial prospect in phosphor manufacture.
O2 dissociation in Ar–O2 surface-wave microwave discharges
Authors: Kutasi Kinga , Sá Paulo A , Guerra Vasco
Published: April 2012

A self-consistent model is developed in order to investigate the dissociation of O2 molecules in Ar–O2 surface-wave microwave discharges. The dissociation degree of O2 molecules ([O]/2[O2]0) is determined for surface-wave discharges generated in 0.5 cm and 2.8 cm diameter tubes with 2.45 GHz and 915 MHz microwave field frequencies, respectively, in the 0.5–25 mbar pressure range at different mixture compositions from pure O2 to 95%Ar–5%O2. The dissociation degree varies non-monotonically with pressure—it passes through a minimum—which is more pronounced in high Ar content mixtures. This behaviour is found to be a consequence of the electron collision processes, in particular the evolution of the non-Maxwellian shape of the electron energy distribution function with pressure. These changes make the electron impact dissociation coefficient follow the same non-monotonic trend with pressure, despite leading to the expected monotonic variation of the ionization rate coefficient. The minimum in dissociation is in correlation with the momentum transfer cross-section profiles of the mixture's components, and occurs approximately at the pressure that satisfies the condition νce = ω, which explains its dependence on ω.
The limits of ultrahigh-resolution x-ray mapping: estimating uncertainties in thin-film and interface structures determined by phase retrieval methods
Authors: Zhou Hua , Pindak Ron , Clarke Roy , Steinberg David M , Yacoby Yizhak
Published: April 2012

Capturing subtle details at the sub-Angstrom level is key to understanding the structural basis of many intriguing interfacial phenomena in epitaxial thin films and nanostructures. X-ray phase retrieval methods are ideally suited to this task but the usual approaches for determination of uncertainties, based on refining a parametrized model, are not applicable in this case. Here we describe a method to estimate the uncertainties of the system electron density, obtained by phase retrieval, and of parameters of interest obtained from it. The method is based on the bootstrap approach and it can be generally applied to surface x-ray scattering data. Several examples are given which illustrate the method's utility in determining uncertainties arising from random and systematic errors. The approach also provides a quantitative measure of the validity of structural solutions obtained by phase retrieval methods.
First Report of Powdery Mildew Caused by Golovinomyces biocellatus on Common Sage (Salvia officinalis) in Slovenia
Authors: Radisek S. , Ferant N. , Jakse J. , Javornik B.
Published: April 2012

Common sage (Salvia officinalis) is a well known perennial and medicinal herb in the Lamiaceae family, which is widely planted in gardens and parks in Slovenia. In September 2007, symptoms of powdery mildew infection were observed on common sage plants grown in several gardens in the Savinja valley. White mycelium was present, principally on the upper leaf surface, but was also observed on stems. The disease progressed as spots coalesced and leaves become distorted and necrotic. Microscopic observations revealed septate and branched hyaline hyphae 4 to 7 μm wide. Conidiophores were cylindrical and septate and measured 40 to 90 × 9 to 12 μm. The foot cells of the conidiophores were straight, followed by one to three shorter cells. Conidia produced in chains (three to four conidia per chain) were hyaline and doliform in shape, measuring 27 to 35 × 14 to 20 μm and lacking fibrosin bodies. Cleistothecia were not observed in the collected samples. All of these characteristics were consistent with Golovinomyces biocellatus as described by Braun (2). For molecular identification of the pathogen, DNA was extracted from mycelia and conidia of infected plants, collected in two different gardens in the Savinja valley as representative samples (1GB-Sof and 2GB-Sof). Nuclear rDNA internal transcribed spacer (ITS) regions were amplified by PCR using the universal primers ITS4 and ITS5, and sequenced. Both samples yielded the same 532 bp sequence, which showed the highest identity (97 to 99%; E value = 0.0) to G. biocellatus ITS sequences in the NCBI GenBank (1). The nucleotide sequence has been assigned GenBank Accession No. JQ340358. Pathogenicity was confirmed by inoculation of 10 healthy plants of S. officinalis ‘Grower's Friend’ planted in pots. Plants were sprayed with a spore suspension (105 conidia/ml; 0.01% Tween 20) obtained from naturally infected leaves. Inoculated plants were covered with polyethylene bags for two days to maintain high humidity and incubated in a growing chamber at 22°C with a 12-h photoperiod. The first powdery mildew signs and symptoms developed on leaves 7 days after inoculation. Ten control plants sprayed with distilled water showed no symptoms. The fungus present on the inoculated plants was morphologically identical to that originally observed on diseased plants. Powdery mildew infections of common sage associated with G. biocellatus have been known in Argentina, Washington State (United States), and various countries in Europe (2,3,4). To the best of our knowledge, this is the first report of G. biocellatus on common sage in Slovenia. Voucher specimens are available at the culture collection of the Slovenian Institute of Hop Research and Brewing.

References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (3) M. G. Cabrera et al. Mycosphere 1:289, 2010. (4) F. M. Dugan. North American Fungi 6:1, 2011.
Recent Genotypes of Phytophthora infestans in the Eastern United States Reveal Clonal Populations and Reappearance of Mefenoxam Sensitivity
Authors: Hu Chia-Hui , Perez Frances G. , Donahoo Ryan , McLeod Adele , Myers Kevin , Ivors Kelly , Secor Gary , Roberts Pamela D. , Deahl Kenneth L. , Fry William E. , Ristaino Jean B.
Published: April 2012

Isolates of Phytophthora infestans (n = 178) were collected in 2002 to 2009 from the eastern United States, Midwestern United States, and eastern Canada. Multilocus genotypes were defined using allozyme genotyping, and DNA fingerprinting with the RG-57 probe. Several previously described and three new mulitilocus genotypes were detected. The US-8 genotype was found commonly on commercial potato crops but not on tomato. US-20 was found on tomato in North Carolina from 2002 through 2007 and in Florida in 2005. US-21 was found on tomato in North Carolina in 2005 and Florida in 2006 and 2007. US-22 was detected on tomato in 2007 in Tennessee and New York and became widespread in 2009. US-22 was found in 12 states on tomato and potato and was spread on tomato transplants. This genotype accounted for about 60% of all the isolates genotyped. The US-23 genotype was found in Maryland, Virginia, Pennsylvania, and Delaware on both tomato and potato in 2009. The US-24 genotype was found only in North Dakota in 2009. A1 and A2 mating types were found in close proximity on potato and tomato crops in Pennsylvania and Virginia; therefore, the possibility of sexual reproduction should be monitored. Whereas most individuals of US-8 and US-20 were resistant to mefenoxam, US-21 appeared to be intermediately sensitive, and isolates of US-22, US-23, and US-24 were largely sensitive to mefenoxam. On the basis of sequence analysis of the ras gene, these latter three genotypes appear to have been derived from a common ancestor. Further field and laboratory studies are underway using simple sequence repeat genotyping to monitor current changes in the population structure of P. infestans causing late blight in North America.
First Report of Curvularia lunata Causing Leaf Spot on Lotus in China
Authors: Cui R. Q. , Sun X. T.
Published: April 2012

Lotus (Nelumbo nucifera Gaertn.) is a flowering aquatic plant, and is widely planted as a vegetable and ornamental plant in China. In June 2011, a leaf spot was observed on lotus in Pingxiang City of Jiangxi Province, causing approximately 60% of leaves to die and leading to 10 to 15% yield loss. Initial symptoms were purple-brown spots emerging on the leaf surfaces with diameters ranging from 0.5 to 3 cm, which later developed grayish white centers and a black-brown banding pattern on the edges. Lesions often merged to form large necrotic areas, covering more than 70% of the leaf surface, which may have contributed to plant death. Small pieces (5 mm2) of symptomatic leaves were excised from the junction of diseased and healthy tissue, surface sterilized in 70% ethanol solution for 1 min and 0.1% mercuric chloride solution for 5 min, washed in three changes of sterile distilled water, and transferred to potato dextrose agar plates. Cultures were maintained in an incubator at 25°C for 5 to 7 days. After 7 days, six black-brown colonies were isolated, which developed dark brown septate conidiophores. Conidia were 20 to 25 × 9 to 13 μm, with three-horizontal septa, and curved at the third cell from the base that was longer and darker than the others. Cells at each end were subhyaline and intermediate cells were medium brown. These characteristics were consistent with Curvularia lunata (Wakker) Boedijng (1,2,4). Molecular characterization was based on rDNA sequence. For two isolates, DNA was extracted using a CTAB protocol with 0.8% mercaptoethanol, then the ITS1-5.8S-ITS2 region was amplified with primers ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) (3). PCR products were cloned and sequencing reactions were run on an AB3730 Stretch DNA sequencing system. On the basis of a comparison of 598 base pairs, both isolates had the same sequence (GenBank Accession No. JQ701798), which differed by one base pair from Cochliobolus lunatus NBRC 100173 (GenBank Accession No. JN943426) (conidial state: Curvularia lunata). Pathogenicity experiments were conducted by inoculating a conidial suspension (106 CFU/ml) on five newly matured leaves of healthy lotus. Plants inoculated with sterile water served as the noninoculated controls. Plants were incubated in the greenhouse at 20 to 25°C. All the inoculated leaves started showing disease symptoms (purple flecks) after 7 days and the noninoculated control plants remained asymptomatic. C. lunata was consistently recovered from all inoculated plants, except the control, thus fulfilling Koch's postulates. To our knowledge, this is the first report of leaf spot caused by C. lunata on lotus in China.

References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, Surrey, England, 1971. (2) M. M. Hawa, et al. Plant Dis. 93: 971, 2009. (3) K. J. Martin and P. T. Rygiewicz. BMC Microbiol. 5:28, 2005. (4) F. B. Rocha et al. Austral. Plant Pathol. 33: 601, 2004.
First Report of Grapevine Leafroll-associated Virus 4 in Vineyards of Turkey
Authors: Kaya A. , Erilmez S. , Paylan I. C. , Erkan S.
Published: April 2012

Turkey is one of the main grape producers in the world, with an annual production of about 4 million tons on approximately 500,000 hectares of viticulture areas, mainly in the Aegean, Southeast Anatolia, and Central Anatolia regions. Nearly 29% of the vineyards in Turkey are located in the Aegean region, with major growing districts including the provinces of Manisa and Izmir. Previous studies have shown that Grapevine leafroll-associated viruses (GLRaV-1, -2, -3, -5, -6, and -7), which cause Grapevine Leafroll Disease (GLD), were present in Turkish vineyards (1,2). Surveys in 2009 and 2011 were conducted to determine other viruses associated with this disease in commercial vineyards of the provinces of Manisa and Izmir. Leaves and young canes were randomly collected from individual symptomatic and symptomless grapevines (Vitis vinifera L.) of red or white cultivars in late summer and autumn. Symptoms observed in plants were reddening and downward rolling of leaves in red cultivars and yellowing of leaf tissue between main veins and leaf curling in white cultivars. In addition, affected grapevines appeared to have reduced growth resulting in smaller canopies. Samples were analyzed first by double antibody sandwich (DAS)-ELISA using commercial diagnostic kits (Bioreba, Switzerland) to GLRaV-4-9 according to the manufacturer's instructions. The results from serological assays on 145 samples revealed that five samples of cv. Syrah and three of cv. Round seedless from Izmir-Menderes and from Manisa-Alasehir, respectively, reacted positively with specific antibodies to GLRaV-4-9. The identification of GLRaV-4 was confirmed by reverse transcriptase-PCR and total nucleic acids were extracted by a silica capture method from fresh, symptomatic plant samples (3). The synthesis of complementary DNA (cDNA) was performed by a Fermentas cDNA synthesis kit in accordance with the procedure specified by the manufacturer and specific primers (Forward: CCAACTGTCGTGGGTATAAGGAAT, Reverse: CCCAGACACCGGTCCTATACT) were used according to methods described by Maliogka et al. (4). An expected PCR product of approximately 200 nt was obtained from symptomatic samples that were GLRaV-4 positive in DAS-ELISA. GLRaV, comprising GLRaV-4 as quarantine pests, are under official control in Turkey. To our knowledge, this is the first report of natural GLRaV-4 infection of grapevines in Turkey.

References: (1) B. Akbas et al., J. Phytopathol. 155:122, 2007. (2) N. Buzkan et al., J. Phytopathol. 158:448, 2010. (3) X. Foissac et al., Acta Hortic. 550:37, 2001. (4) V. I. Maliogka et al., J. Virol. Methods 154:41, 2008.
So Near and Yet so Far: The Specific Case of Ralstonia solanacearum Populations from Côte d'Ivoire in Africa
Authors: N'Guessan C. A. , Abo K. , Fondio L. , Chiroleu F. , Lebeau A. , Poussier S. , Wicker E. , Koné D.
Published: April 2012

The genetic and phenotypic diversity of Côte d'Ivoire Ralstonia solanacearum strains was assessed on a 168-strain collection sampled on Solanaceae both in the southern lowlands and western highlands. Phylotypes I, II, and III were prevalent, though at unexpected frequencies. Phylotype I strains (87.5%) were genetically diverse and overrepresented in all agroecological areas, including highlands (AEZ III). Phylotype II strains (10.7%) only belonged to one tropical lowland-adapted broad host range lineage (IIA-35), whereas no highland-adapted potato brown rot (IIB-1) or Moko strains were detected. African phylotype III strains were rare (1.8%). They originated from a single Burkina Faso lineage (III-23) and were only found in lowlands. Three phylotype I strains were found harboring pRSC35, a plasmid identified in phylotype III strains in Cameroon. From pathogenicity tests performed on commercial varieties and tomato/eggplant/pepper references, the virulence diversity observed was high, with five pathoprofiles described. Eggplant accessions MM152 and EG203 and tomato HW7996 displayed the largest resistance spectrum and highest level. Two highly virulent phylotype I strains were able to bypass resistance of HW7996 and the eggplant reference AG91-25. Collectively, these points lead to the conclusion that the situation in Côte d'Ivoire is specific towards other African countries, and specifically from the Cameroon reference, and that within phylotype I can exist a high virulence diversity. This calls for similar studies in neighboring West African countries, linking R. solanacearum pathogen genetic diversity to strain virulence at the regional level, for the rationalization of regional resistance deployment strategies and future resistance durability studies.