bluuebunny/crossref_metadata_2025 huggingface dataset:
Coupled electron-nuclear dynamics: Charge migration and charge transfer initiated near a conical intersection
Authors: Mendive-Tapia David , Vacher Morgane , Bearpark Michael J. , Robb Michael A.
Published: July 2013

Coupled electron-nuclear dynamics, implemented using the Ehrenfest method, has been used to study charge migration with fixed nuclei, together with charge transfer when nuclei are allowed to move. Simulations were initiated at reference geometries of neutral benzene and 2-phenylethylamine (PEA), and at geometries close to potential energy surface crossings in the cations. Cationic eigenstates, and the so-called sudden approximation, involving removal of an electron from a correlated ground-state wavefunction for the neutral species, were used as initial conditions. Charge migration without coupled nuclear motion could be observed if the Ehrenfest simulation, using the sudden approximation, was started near a conical intersection where the states were both strongly coupled and quasi-degenerate. Further, the main features associated with charge migration were still recognizable when the nuclear motion was allowed to couple. In the benzene radical cation, starting from the reference neutral geometry with the sudden approximation, one could observe sub-femtosecond charge migration with a small amplitude, which results from weak interaction with higher electronic states. However, we were able to engineer large amplitude charge migration, with a period between 10 and 100 fs, corresponding to oscillation of the electronic structure between the quinoid and anti-quinoid cationic electronic configurations, by distorting the geometry along the derivative coupling vector from the D6h Jahn-Teller crossing to lower symmetry where the states are not degenerate. When the nuclear motion becomes coupled, the period changes only slightly. In PEA, in an Ehrenfest trajectory starting from the D2 eigenstate and reference geometry, a partial charge transfer occurs after about 12 fs near the first crossing between D1, D2 (N+-Phenyl, N-Phenyl+). If the Ehrenfest propagation is started near this point, using the sudden approximation without coupled nuclear motion, one observes an oscillation of the spin density – charge migration – between the N atom and the phenyl ring with a period of 4 fs. When the nuclear motion becomes coupled, this oscillation persists in a damped form, followed by an effective charge transfer after 30 fs.
Effects from A-site substitution on morphotropic phase boundary and phonon modes of (Pb1–1.5xLax)(Zr0.42Sn0.40Ti0.18)O3 ceramics by temperature dependent Raman spectroscopy
Authors: Chen X. , Hu Z. G. , Duan Z. H. , Chen X. F. , Wang G. S. , Dong X. L. , Chu J. H.
Published: July 2013

The complex perovskite ferroelectric/antiferroelectric of (Pb1−1.5xLax)(Zr0.42Sn0.40Ti0.18)O3 (PLZST) ceramics have been investigated by Raman scattering spectra from 77 to 480 K. It was found that phase transition occurs between La composition of 2.6% and 2.8% for PLZST ceramics. Softing of A1(TO1) mode and dramatic changes of relative strength from E(TO2) mode are observed at morphotropic phase boundary (MPB). Moreover, it was found that MPB characteristic shows a wider and lower trend of temperature region with increasing La composition. This could be ascribed to the diminishment of the energy barrier and increment of A-cation entropy.
Remanence plots technique extended to exchange bias systems
Authors: Harres A. , Cichelero R. , Pereira L. G. , Schmidt J. E. , Geshev J.
Published: July 2013

Efforts have been recently made to use remanence plots in exchange-bias studies. However, since the two remnant magnetizations of a biased loop may differ, this technique cannot be applied in its classical form. This work extends it to systems with shifted loops and shows that the number of distinct plots is significantly increased. The approach was probed on Co/IrMn exchange bias films. Possible discrepancies between experiment and theory are pointed out and discussed. The adaptation of the model presented here enables it to become one of the few accessible techniques for rapid and accurate evaluation of magnetic interactions in biased systems.
Enhancement of the stability of resistive switching characteristics by conduction path reconstruction
Authors: Huang Jheng-Jie , Chang Ting-Chang , Yu Chih-Cheng , Huang Hui-Chun , Chen Yu-Ting , Tseng Hsueh-Chih , Yang Jyun-Bao , Sze Simon M. , Gan Der-Shin , Chu Ann-Kuo , Lin Jian-Yang , Tsai Ming-Jinn
Published: July 2013

In this study, a Pt/BiFeO3/TiN device was fabricated and the resistance switching characteristics were investigated. After the first forming process, the conduction path was formed and exhibited unstable bipolar switching characteristics. Subsequently, the original conduction path was destroyed thoroughly by high negative bias. By reconstructing the conduction path after a second forming process (re-forming process), the device exhibits stable bipolar switching characteristics. Transmission electron microscopy analysis indicates that the stability of switching behavior was enhanced because of the joule heating effect, and is an easy way to improve the resistance switching characteristics.
Intrinsically modified thermoelectric performance of alkaline-earth isovalently substituted [Bi2AE2O4][CoO2]y single crystals
Authors: Sun N. , Dong S. T. , Zhang B. B. , Chen Y. B. , Zhou J. , Zhang S. T. , Gu Z. B. , Yao S. H. , Chen Y. F.
Published: July 2013

Alkaline-earth elements isovalently substituted into a [Bi2AE2O4][CoO2]y (AE2 = Ca2, Sr2, and CaSr) single crystal with a layered structure were grown by the optical floating zone method. Structural characterization by X-ray diffraction and electron microscopy showed that the layers were oriented perpendicular to the c-axis, as well as the growth of direction was parallel to the ab-plane. The thermoelectric properties, including the Seebeck effect, electrical conductivity and thermal conductivity were investigated. The results of the thermoelectric measurements showed that the full substitution of Ca for Sr in [Bi2Sr2−xCaxO4][CoO2]y has the best overall thermoelectric performance. Compared with the other two cases studied, the full Ca substituted crystal [Bi2Ca2O4][CoO2]y exhibits both reduced resistivity and thermal conductivity, but not a reduced Seebeck coefficient. The enhanced thermoelectric property in [Bi2Ca2O4][CoO2]y is mainly due to lower structural symmetry, which is confirmed by electron microscopy characterization. This work demonstrates that even isovalently substitution can play a crucial role in the thermoelectric effect of layered cobalt oxides.
Metal-oxide thin-film transistors patterned by printing
Authors: Levy David H. , Ellinger Carolyn R. , Nelson Shelby F.
Published: July 2013

We demonstrate thin-film transistors with the fabrication advantages associated with printed electronics and the device performance associated with inorganic materials that are typically patterned via photolithography. In this process a polymeric material is printed to selectively inhibit the deposition of the electrically active material, which is globally applied via spatial atomic layer deposition. We identify water-soluble inhibitors that make attractive choices for printable ink formulations and explore the interactions of two examples of polymeric inhibitors with the process space. Using this knowledge we demonstrate zinc oxide thin film transistors, patterned entirely by inkjet-printed polyvinyl pyrrolidone.
Metamaterial-based gradient index beam steerers for terahertz radiation
Authors: Neu Jens , Beigang René , Rahm Marco
Published: July 2013

We designed, fabricated, and optically characterized single and double layer metamaterial-based gradient index beam steerers for terahertz radiation. We measured a maximal deflection angle of 6°. The operation bandwidth of the beam steerers was 300 GHz around a center frequency of 1.3 THz. Within this bandwidth, the amplitude transmission was higher than 50%. Due to a thickness of only 100 μm or below, the implemented beam steerers are ideally suited for integration in compact terahertz measurement systems.
Phase and amplitude dynamics in large systems of coupled oscillators: Growth heterogeneity, nonlinear frequency shifts, and cluster states
Authors: Shing Lee Wai , Ott Edward , Antonsen Thomas M.
Published: July 2013

This paper addresses the behavior of large systems of heterogeneous, globally coupled oscillators each of which is described by the generic Landau-Stuart equation, which incorporates both phase and amplitude dynamics of individual oscillators. One goal of our paper is to investigate the effect of a spread in the amplitude growth parameter of the oscillators and of the effect of a homogeneous nonlinear frequency shift. Both of these effects are of potential relevance to recently reported experiments. Our second goal is to gain further understanding of the macroscopic system dynamics at large coupling strength, and its dependence on the nonlinear frequency shift parameter. It is proven that at large coupling strength, if the nonlinear frequency shift parameter is below a certain value, then there is a unique attractor for which the oscillators all clump at a single amplitude and uniformly rotating phase (we call this a single-cluster “locked state”). Using a combination of analytical and numerical methods, we show that at higher values of the nonlinear frequency shift parameter, the single-cluster locked state attractor continues to exist, but other types of coexisting attractors emerge. These include two-cluster locked states, periodic orbits, chaotic orbits, and quasiperiodic orbits.
Transport through a single donor in p-type silicon
Authors: Miwa J. A. , Mol J. A. , Salfi J. , Rogge S. , Simmons M. Y.
Published: July 2013

Single phosphorus donors in silicon are promising candidates as qubits in the solid state. Here, we present low temperature scanning probe microscopy and spectroscopy measurements of individual phosphorus dopants deliberately placed in p-type silicon ∼1 nm below the surface. The ability to image individual dopants combined with scanning tunnelling spectroscopy allows us to directly study the transport mechanism through the donor. We show that for a single P donor, transport is dominated by a minority carrier recombination process with the surrounding p-type matrix. The understanding gained will underpin future studies of atomically precise mapping of donor-donor interactions in silicon.
Enhanced perpendicular magnetic anisotropy in Fe/Mn bilayers by incorporating ultrathin ferromagnetic underlayer through magnetic proximity effect
Authors: Wang Bo-Yao , Chiu Chieh-Chen , Lin Wen-Chin , Lin Minn-Tsong
Published: July 2013

The perpendicular magnetic anisotropy(PMA) was shown to be established in ferromagnetic (FM)/fcc-Mn bilayers through the FM-antiferromagnetic (AFM) exchange coupling. We demonstrate here that such PMA can be further enhanced by incorporating an ultrathin Fe film as an underlayer. In a series of Fe/Mn bilayers, hysteresis loop measurement shows that the thickness of top Fe layer with PMA can be extended to a thicker range while an ultrathin Fe underlayer is inserted. Such enhancement of PMA is attributed to an increase of AFM ordering on the Mn film originated from the magnetic proximity effect with the Fe underlayer.
Electric field effects in ultrathin β-ZrNBr nano-crystals
Authors: De Debtanu , Su Guoxiong , See Sean , Guloy Arnold , Ting Chin-Sen , Peng Haibing
Published: July 2013

Layered materials with a non-zero band gap have emerged in the past few years because of their potential to supersede graphene in nano-electronics. Zirconium nitrogen halides (ZrNX, X = Cl,Br) are indirect gap semiconductors with a layered crystal structure. Here, we report the realization of electric field effects in exfoliated nano-crystals of β-ZrNBr using degenerately doped silicon as a back-gate. The as-produced devices demonstrate n-type transport with field effect carrier mobility of 5.8 cm2 V−1 s−1. The conduction is dominated by variable range hopping for the range of temperature from 295 K to 32 K. Our results present a promising candidate for future thin-film electronics application.
Charge conduction and relaxation in MoS2 nanoflakes synthesized by simple solid state reaction
Authors: Ahmad Mushtaq , Rafiq M. A. , Imran Z. , Rasool Kamran , Shahid R. N. , Javed Yasir , Hasan M. M.
Published: July 2013

We present the synthesis of crystalline MoS2 nanoflakes through self-exfoliation in a simple solid state reaction at temperature ∼650 °C. X-ray diffraction and Transmission Electron Microscope analysis indicate the formation of pure hexagonal phase MoS2 nanoflakes. Impedance and modulus plane plots from 20 Hz to 2 MHz show two relaxations associated with bulk and interface phases at temperatures from 180 K to 280 K. The conductivity obeys Mott's 2D variable-range hopping phenomenon and density of localized states ∼3.42 × 1019 eV-1 cm−3 is extracted.
Tuning properties of columnar nanocomposite oxides
Authors: Liao Zhaoliang , Gao Peng , Stadler Shane , Jin Rongying , Pan Xiaoqing , Plummer E. W. , Zhang Jiandi
Published: July 2013

One major challenge for engineering functional nanocomposites is how to tune the geometry structure and control the chemical composition. We demonstrate here that columnar nanocomposite films can be grown by using alternate deposition of La2/3Sr1/3MnO3 and V2O3 on LaAlO3 (111). A solid state reaction, rather than simple spinodal decomposition, dictates the nanocomposite structure, chemical composition, and functionality. By controlling the deposition time ratio of the two compounds, the physical properties of the composite films can be tuned, thus providing a flexible way to tailor nanocomposites for advanced functionality.
Accurate determination of charge transition levels of the As-As dimer defect at GaAs/oxide interfaces through hybrid functionals
Authors: Miceli Giacomo , Pasquarello Alfredo
Published: July 2013

The energy levels of the As-As dimer defect at GaAs/oxide interfaces are accurately determined within a hybrid functional scheme and aligned with respect to the GaAs band gap. An As-As dimer is constructed at a model interface between GaAs and κ-Al2O3, which satisfies electron counting rules. The defect is studied through its charge transition levels which account for structural relaxation upon charging and which can directly be compared to measured defect energies. The antibonding state of the As-As dimer is found to lie at 0.30 eV below the conduction-band edge, in good correspondence with experimentally observed defect states.
Effect of drought on morphological and functional traits of Poa ligularis and Pappostipa speciosa, native perennial grasses with wide distribution in Patagonian rangelands, Argentina
Authors: Cenzano Ana M. , Varela M. Celeste , Bertiller Mónica B. , Luna M. Virginia
Published: July 2013

Poa ligularis Nees. Ap. Steudel and Pappostipa speciosa (Trin. et Rupr.) Romaschenko are dominant perennial grasses in the arid Patagonian rangelands of Argentina. Both species are exposed to periods of water shortage during spring-summer and are grazed by domestic and native herbivores. Pappostipa speciosa displays xeromorphic adaptations and is less preferred by herbivores than P. ligularis. The knowledge of how drought affects morphological/functional traits in coexisting perennial grass species is useful to understanding the function of desert perennial grasses, and for the use and conservation of Patagonian arid rangelands. The hypothesis of this study was that co-existing perennial grasses contrasting in drought resistance mechanisms display different degrees of phenotypic plasticity in underlying and/or functional traits. Plants of both species were exposed to two levels of gravimetric soil moisture: 16% (~field capacity) and 4%. Plant vegetative and reproductive traits were measured weekly in individual plants and these were harvested at the end of the experiment. Aboveground and root biomass were separated in the harvested plants and the concentration of photosynthetic pigments was assessed in green leaves. The trait response range was also calculated through the plasticity index. In both species, drought stress led to significant reductions in plant height, total plant dry weight, number of total leaves, dry weight of green and senescent leaf, percentage of flowering plants, length of inflorescences, and number, length and dry weight of roots. The concentration of photosynthetic pigments increased under drought in both species. In conclusion, drought strongly affected reproductive and vegetative traits in both species and the greatest negative effect of drought was found in P. speciosa, the most conservative species. However, our findings might indicate that both species are able to maintain photosynthetic activity through the increase of photosynthetic pigments under drought conditions in Patagonian rangelands.
Mass Spectrometry of Gangliosides from Human Sensory and Motor Cortex
Authors: Flangea Corina , Fabris Dragana , Vukelić Željka , Zamfir Alina D.
Published: July 2013

Sialylated glycosphingolipids, known as gangliosides, are highly expressed in the central nervous system exhibiting region-specific composition in correlation to the specialised functions of particular brain regions. In the present study high resolution tandem mass spectrometry on a quadrupole time-of-flight instrument with nanoelectrospray was optimised and applied for the first comparative assessment of the ganglioside profile in single specimens of adult human motor and somatosensory cortex. In the second stage, the structural analysis performed by collision induced dissociation tandem MS disclosed the presence in motor cortex of a fucose-ganglioside Fuc-GM1 (d18 : 1/20 : 0) isomer exhibiting both N-acetylneuraminic acid and fucose residues linked to the inner galactose.
Candidate gene-based association genetics analysis of herbage quality traits in perennial ryegrass (Lolium perenne L.)
Authors: Pembleton L. W. , Wang J. , Cogan N. O. I. , Pryce J. E. , Ye G. , Bandaranayake C. K. , Hand M. L. , Baillie R. C. , Drayton M. C. , Lawless K. , Erb S. , Dobrowolski M. P. , Sawbridge T. I. , Spangenberg G. C. , Smith K. F. , Forster J. W.
Published: July 2013

Due to the complex genetic architecture of perennial ryegrass, based on an obligate outbreeding reproductive habit, association-mapping approaches to genetic dissection offer the potential for effective identification of genetic marker–trait linkages. Associations with genes for agronomic characters, such as components of herbage nutritive quality, may then be utilised for accelerated cultivar improvement using advanced molecular breeding practices. The objective of the present study was to evaluate the presence of such associations for a broad range of candidate genes involved in pathways of cell wall biosynthesis and carbohydrate metabolism. An association-mapping panel composed from a broad range of non-domesticated and varietal sources was assembled and assessed for genome-wide sequence polymorphism. Removal of significant population structure obtained a diverse meta-population (220 genotypes) suitable for association studies. The meta-population was established with replication as a spaced-plant field trial. All plants were genotyped with a cohort of candidate gene-derived single nucleotide polymorphism (SNP) markers. Herbage samples were harvested at both vegetative and reproductive stages and were measured for a range of herbage quality traits using near infrared reflectance spectroscopy. Significant associations were identified for ~50% of the genes, accounting for small but significant components of phenotypic variance. The identities of genes with associated SNPs were largely consistent with detailed knowledge of ryegrass biology, and they are interpreted in terms of known biochemical and physiological processes. Magnitudes of effect of observed marker–trait gene association were small, indicating that future activities should focus on genome-wide association studies in order to identify the majority of causal mutations for complex traits such as forage quality.
Plant–aphid interactions with a focus on legumes
Authors: Kamphuis Lars G. , Zulak Katherine , Gao Ling-Ling , Anderson Jonathan , Singh Karam B.
Published: July 2013

Sap-sucking insects such as aphids cause substantial yield losses in agriculture by draining plant nutrients as well as vectoring viruses. The main method of control in agriculture is through the application of insecticides. However, aphids rapidly evolve mechanisms to detoxify these, so there is a need to develop durable plant resistance to these damaging insect pests. The focus of this review is on aphid interactions with legumes, but work on aphid interactions with other plants, particularly Arabidopsis and tomato is also discussed. This review covers advances on the plant side of the interaction, including the identification of major resistance genes and quantitative trait loci conferring aphid resistance in legumes, basal and resistance gene mediated defence signalling following aphid infestation and the role of specialised metabolites. On the aphid side of the interaction, this review covers what is known about aphid effector proteins and aphid detoxification enzymes. Recent advances in these areas have provided insight into mechanisms underlying resistance to aphids and the strategies used by aphids for successful infestations and have significant impacts for the delivery of durable resistance to aphids in legume crops.
SOX2–LIN28/let-7 pathway regulates proliferation and neurogenesis in neural precursors
Authors: Cimadamore Flavio , Amador-Arjona Alejandro , Chen Connie , Huang Chun-Teng , Terskikh Alexey V.
Published: July 2013

Significance

The transcription factor SOX2 plays a critical role in self-renewal and neuronal differentiation of neural precursors (NPCs); however, the molecular mechanisms underlying its functions are poorly understood. We found that SOX2 regulates the expression of LIN28, a suppressor of let-7 microRNA biogenesis. Exogenous LIN28 rescued the NPC proliferation and some neurogenic deficits in the absence of SOX2. We identified let-7i as a novel and potent inhibitor of neuronal differentiation that represses proneural genes. The discovery of SOX2–LIN28/let-7 pathway that maintains both NPC proliferation and neurogenic potential will enhance our understanding and therapeutic development relevant to neurodegeneration and brain tumors.
Increased transmissibility explains the third wave of infection by the 2009 H1N1 pandemic virus in England
Authors: Dorigatti Ilaria , Cauchemez Simon , Ferguson Neil M.
Published: July 2013

In the 2009 H1N1 pandemic, the United Kingdom experienced two waves of infection, the first in the late spring and the second in the autumn. Given the low level of susceptibility to the pandemic virus expected to be remaining in the population after the second wave, it was a surprise that a substantial third epidemic occurred in the UK population between November 2010 and February 2011, despite no evidence for any significant antigenic evolution of the pandemic virus. Here, we use a mathematical model of influenza transmission embedded within a Bayesian synthesis inferential framework to jointly analyze syndromic, virological, and serological surveillance data collected in England in 2009–2011 and thereby assess epidemiological mechanisms which might have generated the third wave. We find that substantially increased transmissibility of the H1N1pdm09 virus is required to reproduce the third wave, suggesting that the virus evolved and increased fitness in the human host by the end of 2010, or that the very cold weather experienced in the United Kingdom at that time enhanced transmission rates. We also find some evidence that the preexisting heterologous immunity which reduced attack rates in adults during 2009 had substantially decayed by the winter of 2010, thus increasing the susceptibility of the adult population to infection. Finally, our analysis suggests that a pandemic vaccination campaign targeting adults and school-age children could have mitigated or prevented the third wave even at moderate levels of coverage.
Fall and Early Winter Movement and Habitat Use of Wild Brook Trout
Authors: Mollenhauer Robert , Wagner Tyler , Kepler Megan V. , Sweka John A.
Published: July 2013

Brook Trout Salvelinus fontinalis populations face a myriad of threats throughout the species’ native range in the eastern United States. Understanding wild Brook Trout movement patterns and habitat requirements is essential for conserving existing populations and for restoring habitats that no longer support self‐sustaining populations. To address uncertainties related to wild Brook Trout movements and habitat use, we radio‐tracked 36 fish in a headwater stream system in central Pennsylvania during the fall and early winter of 2010–2011. We used generalized additive mixed models and discrete choice models with random effects to evaluate seasonal movement and habitat use, respectively. There was variability among fish in movement patterns; however, most of the movement was associated with the onset of the spawning season and was positively correlated with fish size and stream flow. There was heterogeneity among fish in selection of intermediate (0.26–0.44 m deep) and deep (0.44–1.06 m deep) residual pools, while all Brook Trout showed similar selection for shallow (0.10–0.26 m) residual pools. There was selection for shallow residual pools during the spawning season, followed by selection for deep residual pools as winter approached. Brook Trout demonstrated a threshold effect for habitat selection with respect to pool length, and selection for pools increased as average pool length increased up to approximately 30 m, and then use declined rapidly for pool habitats greater than 30 m in length. The heterogeneity and nonlinear dynamics of movement and habitat use of wild Brook Trout observed in this study underscores two important points: (1) linear models may not always provide an accurate description of movement and habitat use, which can have implications for management, and (2) maintaining stream connectivity and habitat heterogeneity is important when managing self‐sustaining Brook Trout populations.
Spatiotemporal Variation of Juvenile Common Carp Foraging Patterns as Inferred from Stable Isotope Analysis
Authors: Weber Michael J. , Brown Michael L.
Published: July 2013

Ontogenetic diet shifts from zooplankton to macroinvertebrates represent an important transition for many fishes during early life stages. However, some fishes have plastic feeding habits that allow them to take advantage of abundant prey resources or display diet specialization instead of undergoing distinct diet shifts. In this study, we evaluated ontogenetic changes in energy sources (based on the carbon isotope signature, δ13C) and trophic position (based on the nitrogen isotope signature, δ15N) for age‐0 Common Carp Cyprinus carpio from eight natural lakes in eastern South Dakota. In general, Common Carp trophic position decreased and energy sources shifted from pelagic to littoral prey resources from July to August. As anticipated, substantial inter‐ and intrapopulation variation existed in Common Carp isotope signatures. Common Carp trophic position increased with increasing fish TL in three lakes but decreased with fish TL in two systems. Intrapopulation variation in trophic position was related to Common Carp relative abundance during July, indicating that individuals may have specialized on different energy resources as a result of intraspecific interactions. The δ13C values decreased with increasing fish size in two populations during July, suggesting a shift toward pelagic resources; δ13C increased with fish size in six populations during August, suggesting a shift toward littoral resources. Our results indicate a high degree of trophic variation in juvenile Common Carp populations, indicative of a foraging generalist. Year‐class strength may increase trophic specialization of individuals but without negative effects on fish growth, suggesting that diet plasticity is an important factor contributing to the success of this invasive species.
Population Structure of a Neotropical Migratory Fish: Contrasting Perspectives from Genetics and Otolith Microchemistry
Authors: Collins Sarah M. , Bickford Nate , McIntyre Peter B. , Coulon Aurélie , Ulseth Amber J. , Taphorn Donald C. , Flecker Alexander S.
Published: July 2013

Developing conservation strategies for migratory fishes requires an understanding of connectivity among populations. Neotropical rivers contain diverse and economically important assemblages of migratory fishes, but little is known about the population biology of most species. We examined the population structure of Prochilodus mariae, an abundant migratory fish species found in Venezuelan rivers that plays essential roles in both regional fisheries and ecosystem dynamics. By coupling otolith microchemistry and microsatellite genetic analyses, we were able to evaluate both natal origins of individual fish and genetic structure on a regional level. The chemistry of otolith cores inferred separate breeding grounds for four of six populations, with 75–85% of individuals from each river sharing a natal signature that is distinct from the other populations. In contrast, we detected no genetic structure, indicating that gene flow among these rivers prevents population differentiation. These disparate inferences underscore the complexity of conserving migratory species; otolith data suggest that ensuring fishery sustainability requires recognizing distinct breeding stocks, while gene flow reflects the importance of connectivity across the broader river network on an evolutionary time scale. We conclude that multiple methodological approaches may often be necessary to fully understand the spatial ecology and management needs of migratory fishes and, therefore, also influence local management practices.
Narrative vignettes and online enquiry in researching therapist accounts of practice with children in schools: An analysis of the methodology
Authors: Jones Phil
Published: July 2013

Aims: This article reviews a research methodology that uses an Internet mediated qualitative, narrative approach to provide in‐depth analysis of vignettes. The research sought to investigate the ways in which dramatherapists, based in different countries, understood the nature of therapeutic change in their work with children. Method: The article describes a qualitative approach to the generation of data by a combination of therapist‐authored vignettes, live, synchronous Internet mediated communication (aMSN Messenger) and email. Participants kept a diary of their response to the research and the article draws on this data within its analysis of the methodology. Findings: Samples of the data are used to analyse how such innovative, online methodology can develop effective access and relationships with geographically dispersed participants and as an effective way of investigating therapist practitioners' understanding of their practice.
PSR B1133+16: radio emission height and plasma composition
Authors: Jones P. B.
Published: July 2013

Recent operation of LOFAR by Hassall et al. has produced severe constraints on the size and altitude of the 40 MHz emission region in this pulsar. It is shown that these limits, given a limited number of unexceptionable assumptions, demonstrate that an electron–positron plasma cannot be the source of the emission. A physically acceptable plasma source composed of protons and ions arises naturally in pulsars having positive corotational polar-cap charge density. Acceptance of this would greatly clarify the classification of pulsar types within the whole.
Specific In Planta Recognition of Two GKLR Proteins of the Downy Mildew Bremia lactucae Revealed in a Large Effector Screen in Lettuce
Authors: Stassen Joost H. M. , Boer Erik den , Vergeer Pim W. J. , Andel Annemiek , Ellendorff Ursula , Pelgrom Koen , Pel Mathieu , Schut Johan , Zonneveld Olaf , Jeuken Marieke J. W. , Van den Ackerveken Guido
Published: July 2013

Breeding lettuce (Lactuca sativa) for resistance to the downy mildew pathogen Bremia lactucae is mainly achieved by introgression of dominant downy mildew resistance (Dm) genes. New Bremia races quickly render Dm genes ineffective, possibly by mutation of recognized host-translocated effectors or by suppression of effector-triggered immunity. We have previously identified 34 potential RXLR(-like) effector proteins of B. lactucae that were here tested for specific recognition within a collection of 129 B. lactucae-resistant Lactuca lines. Two effectors triggered a hypersensitive response: BLG01 in 52 lines, predominantly L. saligna, and BLG03 in two L. sativa lines containing Dm2 resistance. The N-terminal sequences of BLG01 and BLG03, containing the signal peptide and GKLR variant of the RXLR translocation motif, are not required for in planta recognition but function in effector delivery. The locus responsible for BLG01 recognition maps to the bottom of lettuce chromosome 9, whereas recognition of BLG03 maps in the RGC2 cluster on chromosome 2. Lactuca lines that recognize the BLG effectors are not resistant to Bremia isolate Bl:24 that expresses both BLG genes, suggesting that Bl:24 can suppress the triggered immune responses. In contrast, lettuce segregants displaying Dm2-mediated resistance to Bremia isolate Bl:5 are responsive to BLG03, suggesting that BLG03 is a candidate Avr2 protein.
The Cpc1 Regulator of the Cross-Pathway Control of Amino Acid Biosynthesis Is Required for Pathogenicity of the Vascular Pathogen Verticillium longisporum
Authors: Timpner Christian , Braus-Stromeyer Susanna A. , Tran Van Tuan , Braus Gerhard H.
Published: July 2013

The plant-pathogenic fungus Verticillium longisporum is a causal agent of early senescence and ripening in cruciferous crops like Brassica napus. Verticillium wilts have become serious agricultural threats in recent decades. Verticillium species infect host plants through the roots and colonize xylem vessels of the host plant. The xylem fluid provides an environment with limited carbon sources and unbalanced amino acid supply, which requires V. longisporum to induce the cross-pathway control of amino acid biosynthesis. RNA-mediated gene silencing reduced the expression of the two CPC1 isogenes (VlCPC1-1 and VlCPC1-2) of the allodiploid V. longisporum up to 85%. VlCPC1 encodes the conserved transcription factor of the cross-pathway control. The silenced mutants were highly sensitive to amino-acid starvation, and the infected plants showed significantly fewer symptoms such as stunting or early senescence in oilseed rape plant infection assays. Consistently, deletion of single CPC1 of the haploid V. dahliae resulted in strains that are sensitive to amino-acid starvation and cause strongly reduced symptoms in the plant-host tomato (Solanum lycopersicum). The allodiploid V. longisporum and the haploid V. dahliae are the first phytopathogenic fungi that were shown to require CPC1 for infection and colonization of their respective host plants, oilseed rape and tomato.
Characterization of Management and Environmental Factors Associated with Regional Variations in Potato Zebra Chip Occurrence
Authors: Workneh F. , Henne D. C. , Goolsby J. A. , Crosslin J. M. , Whipple S. D. , Bradshaw J. D. , Rashed A. , Paetzold L. , Harveson R. M. , Rush C. M.
Published: July 2013

Potato zebra chip (ZC), caused by the bacterial pathogen ‘Candidatus Liberibacter solanacearum’, which is vectored by the potato psyllid (Bactericera cockerelli), has caused widespread damage to U.S. potato production ever since its first discovery in south Texas in 2000. To determine the influence of environmental factors and management practices on ZC occurrence, data on management and meteorological variables, field locations, and psyllid counts were collected over a 3-year period (2010 to 2012) from six locations across the central United States (south Texas to Nebraska). At these locations, ZC-symptomatic plants were counted in 26 fields from systematically established 20 m × 30 m plots around the field edges and field interiors. Mean numbers of symptomatic plants per plot were classified into two intensity classes (ZC ≤ 3 or ZC > 3) and subjected to discriminant function and logistic regression analyses to determine which factors best distinguish between the two ZC intensity classes. Of all the variables, location, planting date, and maximum temperature were found to be the most important in distinguishing between ZC intensity classes. These variables correctly classified 88.5% of the fields into either of the two ZC-intensity classes. Logistic regression analysis of the individual variables showed that location accounted for 90% of the variations, followed by planting date (86%) and maximum temperature (70%). There was a low but significant (r = –0.44983, P = 0.0211) negative correlation between counts of psyllids testing positive for pathogen and latitudinal locations, indicating a south-to-north declining trend in counts of psyllids testing positive for the pathogen. A similar declining trend also was observed in ZC occurrence (r = –0.499, P = 0.0094).
Lidocaine Patch (5%) in Treatment of Persistent Inguinal Postherniorrhaphy Pain
Authors: Bischoff Joakim M. , Petersen Marian , Üçeyler Nurcan , Sommer Claudia , Kehlet Henrik , Werner Mads U.
Published: July 2013

Background:

Evidence-based pharmacological treatment options for patients with persistent inguinal postherniorrhaphy pain are lacking.

Methods:

Twenty-one male patients, with severe, unilateral, persistent inguinal postherniorrhaphy pain, participated in a randomized, double-blind, placebo-controlled crossover trial, receiving lidocaine patch (5%) and placebo patch treatments in periods of 14 days separated by a 14-day wash-out period. Pain intensities (at rest, during movement, and pressure evoked [Numerical Rating Scale]) were assessed before treatment and on the last 3 days of each treatment period. Patients were a priori divided into two subgroups based on quantitative sensory testing (+/− thermal “hyposensitivity”). Skin biopsies for intraepidermal nerve fiber density assessment were taken at baseline, and quantitative sensory testing was performed before and after each treatment period. The primary outcome was change in pain intensity assessed as the difference in summed pain intensity differences between lidocaine and placebo patch treatments.

Results:

There was no difference in summed pain intensity differences between lidocaine and placebo patch treatments in all patients (mean difference 6.2% [95% CI = −6.6 to 18.9%]; P = 0.33) or in the two subgroups (+/− thermal “hyposensitivity”). The quantitative sensory testing (n = 21) demonstrated an increased pressure pain thresholds after lidocaine compared with placebo patch treatment. Baseline intraepidermal nerve fiber density (n = 21) was lower on the pain side compared with the nonpain side (−3.8 fibers per millimeter [95% CI = −6.1 to −1.4]; P = 0.003). One patient developed mild erythema in the groin during both treatments.

Conclusions:

Lidocaine patch treatment did not reduce combined resting and dynamic pain ratings compared with placebo in patients with severe, persistent inguinal postherniorrhaphy pain.
Differences in offspring size predict the direction of isolation asymmetry between populations of a placental fish
Authors: Schrader Matthew , Fuller Rebecca C. , Travis Joseph
Published: July 2013

Crosses between populations or species often display an asymmetry in the fitness of reciprocal
F
1
hybrids. This pattern, referred to as isolation asymmetry or Darwin's Corollary to Haldane's Rule, has been observed in taxa from plants to vertebrates, yet we still know little about which factors determine its magnitude and direction. Here, we show that differences in offspring size predict the direction of isolation asymmetry observed in crosses between populations of a placental fish,
Heterandria formosa
. In crosses between populations with differences in offspring size, high rates of hybrid inviability occur only when the mother is from a population characterized by small offspring. Crosses between populations that display similarly sized offspring, whether large or small, do not result in high levels of hybrid inviability in either direction. We suggest this asymmetric pattern of reproductive isolation is due to a disruption of parent–offspring coadaptation that emerges from selection for differently sized offspring in different populations.
Analysing photonic structures in plants
Authors: Vignolini Silvia , Moyroud Edwige , Glover Beverley J. , Steiner Ullrich
Published: July 2013

The outer layers of a range of plant tissues, including flower petals, leaves and fruits, exhibit an intriguing variation of microscopic structures. Some of these structures include ordered periodic multilayers and diffraction gratings that give rise to interesting optical appearances. The colour arising from such structures is generally brighter than pigment-based colour. Here, we describe the main types of photonic structures found in plants and discuss the experimental approaches that can be used to analyse them. These experimental approaches allow identification of the physical mechanisms producing structural colours with a high degree of confidence.
Bioavailability of silver nanoparticles and ions: from a chemical and biochemical perspective
Authors: Behra Renata , Sigg Laura , Clift Martin J. D. , Herzog Fabian , Minghetti Matteo , Johnston Blair , Petri-Fink Alke , Rothen-Rutishauser Barbara
Published: July 2013

Owing to their antimicrobial properties, silver nanoparticles (NPs) are the most commonly used engineered nanomaterial for use in a wide array of consumer and medical applications. Many discussions are currently ongoing as to whether or not exposure of silver NPs to the ecosystem (i.e. plants and animals) may be conceived as harmful or not. Metallic silver, if released into the environment, can undergo chemical and biochemical conversion which strongly influence its availability towards any biological system. During this process, in the presence of moisture, silver can be oxidized resulting in the release of silver ions. To date, it is still debatable as to whether any biological impact of nanosized silver is relative to either its size, or to its ionic constitution. The aim of this review therefore is to provide a comprehensive, interdisciplinary overview—for biologists, chemists, toxicologists as well as physicists—regarding the production of silver NPs, its (as well as in their ionic form) chemical and biochemical behaviours towards/within a multitude of relative and realistic biological environments and also how such interactions may be correlated across a plethora of different biological organisms.
Dengue virus-infected human monocytes trigger late activation of caspase-1, which mediates pro-inflammatory IL-1β secretion and pyroptosis
Authors: Tan Ter Yong , Chu Justin Jang Hann
Published: July 2013

Dengue virus (DENV) infection affects millions of people annually and has the potential to cause fatal haemorrhagic fever and shock. Although the underlying pathogenesis of severe dengue illness is still unclear, current evidence suggests that severe disease progression has an immunological basis. In this study, we investigated the role of caspase-1 during host–pathogen interactions within DENV-infected human monocytes. Using DENV-infected primary monocytes, we examined caspase-1 at various levels of gene expression and probed for potential immune consequences mediated by caspase-1 such as secretion of pro-inflammatory IL-1β and pyroptotic cell death. We report that DENV-infected monocytes upregulated functional caspase-1 mRNA and pro-caspase-1 activation as a late response to infection. In addition, we found that caspase-1 is responsible for IL-1β secretion and pyroptosis of DENV-infected monocytes. Together, our results show that late caspase-1 activation within DENV-infected monocytes can contribute to pro-inflammatory outcomes that might play a role in dengue immunopathogenesis.
Three-dimensional phase-contrast X-ray microtomography with scanning–imaging X-ray microscope optics
Authors: Takeuchi Akihisa , Uesugi Kentaro , Suzuki Yoshio
Published: July 2013

A three-dimensional (3D) X-ray tomographic micro-imaging system has been developed. The optical system is based on a scanning–imaging X-ray microscope (SIXM) optics, which is a hybrid system consisting of a scanning microscope optics with a one-dimensional (1D) focusing (line-focusing) device and an imaging microscope optics with a 1D objective. In the SIXM system, each 1D dataset of a two-dimensional (2D) image is recorded independently. An object is illuminated with a line-focused beam. Positional information of the region illuminated by the line-focused beam is recorded with the 1D imaging microscope optics as line-profile data. By scanning the object with the line focus, 2D image data are obtained. In the same manner as for a scanning microscope optics with a multi-pixel detector, imaging modes such as phase contrast and absorption contrast can be arbitrarily configured after the image data acquisition. By combining a tomographic scan method and the SIXM system, quantitative 3D imaging is performed. Results of a feasibility study of the SIXM for 3D imaging are shown.
Accounting quality of German and UK cross‐listings
Authors: Li Eng Li , Lin Jing
Published: July 2013

Purpose

This paper aims to compare the quality of financial reporting (or accounting quality) of firms cross‐listed in Germany and the United Kingdom relative to domestic firms that are not cross‐listed in Germany and the United Kingdom.

Design/methodology/approach

The authors assess financial reporting quality based on five measures of earnings management; two measures of timely loss recognition; and the explanatory power (R2) of three models of stock price and returns association with accounting data. Accounting quality is associated with less earnings management, more timely loss recognition and higher stock price/returns association with accounting data.

Findings

The authors find that there is no difference in financial reporting quality of firms cross‐listed in Germany and the United Kingdom and domestic firms that do not cross‐list in these countries. They further find that German and UK cross‐listing firms have lower accounting quality than US cross‐listing firms.

Research limitations/implications

The study is subject to some limitations. Cross‐listing firms may be different from non‐cross‐listing firms in characteristics other than country, size and cross‐listing, the variables used to match the firms. The authors also lose quite a number of observations due to the matching process and therefore are limited by a small sample size.

Originality/value

This paper contributes to a growing literature on cross‐listing and quality of financial reporting. The authors extend Lang et al.'s work to exchanges outside of the USA. They provide further support for Coffee, and Lang et al. that firms cross‐listed in the USA conform to higher reporting standards than others, in particular in comparison with firms cross‐listed in Germany.