bluuebunny/crossref_metadata_2025 huggingface dataset:
Self-similar evolution of a body eroding in a fluid flow
Authors: Moore Matthew N. J. , Ristroph Leif , Childress Stephen , Zhang Jun , Shelley Michael J.
Published: November 2013

Erosion of solid material by flowing fluids plays an important role in shaping landforms, and in this natural context is often dictated by processes of high complexity. Here, we examine the coupled evolution of solid shape and fluid flow within the idealized setting of a cylindrical body held against a fast, unidirectional flow, and eroding under the action of fluid shear stress. Experiments and simulations both show self-similar evolution of the body, with an emerging quasi-triangular geometry that is an attractor of the shape dynamics. Our fluid erosion model, based on Prandtl boundary layer theory, yields a scaling law that accurately predicts the body's vanishing rate. Further, a class of exact solutions provides a partial prediction for the body's terminal form as one with a leading surface of uniform shear stress. Our simulations show this predicted geometry to emerge robustly from a range of different initial conditions, and allow us to explore its local stability. The sharp, faceted features of the terminal geometry defy the intuition of erosion as a globally smoothing process.
The dependence of ZnO photoluminescence efficiency on excitation conditions and defect densities
Authors: Simmons Jay G. , Foreman John V. , Liu Jie , Everitt Henry O.
Published: November 2013

The quantum efficiencies of both the band edge and deep-level defect emission from annealed ZnO powders were measured as a function of excitation fluence and wavelength from a tunable sub-picosecond source. A simple model of excitonic decay reproduces the observed excitation dependence of rate constants and associated trap densities for all radiative and nonradiative processes. The analysis explores how phosphor performance deteriorates as excitation fluence and energy increase, provides an all-optical approach for estimating the number density of defects responsible for deep-level emission, and yields new insights for designing efficient ZnO-based phosphors.
Richtmyer-Meshkov instability in dilute gas-particle mixtures with re-shock
Authors: Schulz J. C. , Gottiparthi K. C. , Menon S.
Published: November 2013

The Richtmyer-Meshkov instability (RMI) is investigated in a dilute gas-particle mixture using three-dimensional numerical simulations. This work extends an earlier two-dimensional study [S. Ukai, K. Balakrishnan, and S. Menon, “On Richtmyer-Meshkov instability in dilute gas-particle mixtures,” Phys. Fluids 22, 104103 (2010)] to a larger parameter space consisting of variations in the mass loading and the particle size as well as considering both single-mode and multi-mode interface initializations. In addition, the effect of the presence of particles on re-shock RMI is also investigated. Single-phase numerical predictions of the mixing layer growth-rate are shown to compare well to both experimental and theoretical results. In a dilute gas-particle mixture, the initial growth-rate of RMI shows similar trends compared to previous work; however, the current numerical predictions show that there is an observable increase, not previously predicted, in the growth of the mixing layer at higher mass loadings. For the range of cases considered, an increase as much as 56% is observed. This increase is attributed to additional vorticity production in the mixing layer resulting from inter-phase momentum coupling. Moreover, the presence of particles introduces a continuous drag on the gas-phase resulting in a delay in the time at which re-shock occurs. This delay, which is observed to be as much as 6%, is largest for higher initial mass loadings and smaller particle radii and has a corresponding effect on both the growth-rate of the mixing-layer after re-shock and the final width of the mixing layer. A new semi-analytical correlation is developed and verified against the numerical data to predict the re-shocked RMI growth-rate in dilute gas-particle flows. The correlation shows that the re-shock RMI growth-rate is linearly proportional to the velocity jump at re-shock, the molecular mixing fraction, and the multi-phase Atwood number. Depending on the initial mass loading and particle radii, the re-shock RMI growth-rates were observed to be reduced by as much as 48% in some cases with variations of around 26% in the width of the mixing layer after re-shock.
Enhancement of strong-field multiple ionization in the vicinity of the conical intersection in 1,3-cyclohexadiene ring opening
Authors: Petrovic Vladimir S. , Schorb Sebastian , Kim Jaehee , White James , Cryan James P. , Glownia J. Michael , Zipp Lucas , Broege Douglas , Miyabe Shungo , Tao Hongli , Martinez Todd , Bucksbaum Philip H.
Published: November 2013

Nonradiative energy dissipation in electronically excited polyatomic molecules proceeds through conical intersections, loci of degeneracy between electronic states. We observe a marked enhancement of laser-induced double ionization in the vicinity of a conical intersection during a non-radiative transition. We measured double ionization by detecting the kinetic energy of ions released by laser-induced strong-field fragmentation during the ring-opening transition between 1,3-cyclohexadiene and 1,3,5-hexatriene. The enhancement of the double ionization correlates with the conical intersection between the HOMO and LUMO orbitals.
Mechanism of bubble detachment from vibrating walls
Authors: Kim Dongjun , Park Jun Kwon , Kang In Seok , Kang Kwan Hyoung
Published: November 2013

We discovered a previously unobserved mechanism by which air bubbles detach from vibrating walls in glasses containing water. Chaotic oscillation and subsequent water jets appeared when a wall vibrated at greater than a critical level. Wave forms were developed at water-air interface of the bubble by the wall vibration, and water jets were formed when sufficiently grown wave-curvatures were collapsing. Droplets were pinched off from the tip of jets and fell to the surface of the glass. When the solid-air interface at the bubble-wall attachment point was completely covered with water, the bubble detached from the wall. The water jets were mainly generated by subharmonic waves and were generated most vigorously when the wall vibrated at the volume resonant frequency of the bubble. Bubbles of specific size can be removed by adjusting the frequency of the wall's vibration.
Maxwell boundary condition and velocity dependent accommodation coefficient
Authors: Struchtrup Henning
Published: November 2013

A modification of Maxwell's boundary condition for the Boltzmann equation is developed that allows to incorporate velocity dependent accommodation coefficients into the microscopic description. As a first example, it is suggested to consider the wall-particle interaction as a thermally activated process with three parameters. A simplified averaging procedure leads to jump and slip boundary conditions for hydrodynamics. Coefficients for velocity slip, temperature jump, and thermal transpiration flow are identified and compared with those resulting from the original Maxwell model and the Cercignani-Lampis model. An extension of the model leads to temperature dependent slip and jump coefficients.
Label-free detection of cardiac troponin-I using gold nanoparticles functionalized single-walled carbon nanotubes based chemiresistive biosensor
Authors: Rajesh  , Sharma Vikash , Puri Nitin K. , Singh Rajiv K. , Biradar Ashok M. , Mulchanadani Ashok
Published: November 2013

We report a specific and ultrasensitive, label-free chemiresistive biosensor based on mercaptopropionic acid capped gold nanoparticles (GNP) functionalized single walled carbon nanotube (SWNT) hybrid for the detection of cardiac specific biomarker troponin-I (cTnI). GNPs were attached to SWNTs through a molecular linker 1-pyrenemethylamine. The highly specific cTnI antibody was covalently immobilized on GNPs through capping agent using carbodiimide coupling reaction. The cTnI interaction to its corresponding antibody was studied with respect to changes in conductance in SWNTs channel, and a detailed field-effect transistor characteristic was delineated. The device exhibited a linear response to cTnI from 0.01 to 10 ng ml−1.
Comparative studies of thermal, oxidative and low temperature properties of waste cooking oil and castor oil
Authors: Babu Borugadda Venu , Goud Vaibhav V.
Published: November 2013

This study compares the thermo-oxidative stability and cold flow properties of waste cooking oil (WCO) and castor oil (CO) as inexhaustible potential raw materials to replace the conventional diesel fuels. The thermo-oxidative stability and high viscosity are the limitations of the vegetable oils to use directly as fuel in diesel engines. Therefore, proper investigation on these physical properties of WCO and CO could help to develop high energy efficient biofuels which could act as an alternative to fossil fuels. This study proposes modern and advanced analytical techniques, i.e., thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC) which consumes less time, energy, and requires less quantity of sample to evaluate aforementioned physical properties. For comparison purpose, properties were also found out using conventional ASTM standard methods. Obtained results by TGA and DSC were very much close to the conventional standard methods. WCO used in this study was found to be thermally more stable, but displays less oxidative stability than CO. Similarly, CO demonstrates improved cold flow properties, i.e., pour point (PP) than WCO. Higher oxidative stability and PP of CO attributed due to the presence of more mono-unsaturated fatty acids in its composition. Finally, from this communication, it can be concluded that the TGA and DSC studies proved as a reliable and efficient analytical techniques to determine thermo-oxidative stability and cold flow properties of virgin oils.
Communication: Long-lived neutral H2 in hydrogen migration within methanol dication
Authors: Nakai K. , Kato T. , Kono H. , Yamanouchi K.
Published: November 2013

The ejection of triatomic hydrogen molecular ions HD2+ and D3+ from CD3OH2+ is investigated by first-principle molecular dynamics simulation. Two C–D chemical bonds are found to be broken to form a neutral D2 moiety that vibrates, rotates, and moves for a relatively long period of time (20–330 fs) towards a transition state leading to the ejection of HD2+ or D3+. The formation of such a long-lived neutral D2 moiety within a hydrocarbon molecule interprets well the recent experimental findings of the long lifetime of doubly charged energized hydrocarbon molecules prior to the ejection of H3+.
Loss-compensated broadband epsilon-near-zero metamaterials with gain media
Authors: Sun Lei , Yang Xiaodong , Gao Jie
Published: November 2013

The concept of loss-compensated broadband epsilon-near-zero metamaterials consisting of step-like metal-dielectric multilayer structures doped with gain media is proposed based on the combination of the Milton representation of the effective permittivity and the optical nonlocality due to the metal-dielectric multilayer structures. With the loss compensation by gain media, broadband epsilon-near-zero metamaterials possesses significantly low material loss in optical frequency range, leading to superior broadband electromagnetic properties for realizing unique functional optical devices, such as the demonstrated prisms for broadband directional emission and S-shaped lenses for phase front shaping.
Performance evaluation of solar air heater having V-down perforated baffles on the absorber plate
Authors: Chamoli Sunil , Thakur N. S.
Published: November 2013

The roughened solar air heater performs thermally better than the conventional smooth solar air heater but is associated with a high pumping power requirement. The effective efficiency based criteria is suitable to design roughened solar air heater duct, as it takes both in accounts the useful heat gain from the system and the pumping power requirement. The thermal and effective efficiency of V down perforated baffled roughened solar air heater is studied analytically and the results obtained are compared with the conventional system. Flow Reynolds number and roughness parameters have combined effect on the heat transfer and fluid flow characteristics. The effective efficiency based criteria to predict the performance suggests using the V down perforated baffled roughened solar air heater in the range of flow Reynolds number 10 000–20 000, which corresponds to the range of solar air heater. It was found that there exists an optimum set of roughness parameters for a given Reynolds number or temperature rise parameter at which effective efficiency is maximum. Designs plots are prepared to predict the optimum set of roughness parameters.
Crystallization and thermophysical properties of Cu46Zr47Al6Co1 bulk metallic glass
Authors: Wu Kang , Li Ran , Zhang Tao
Published: November 2013

Phase evolution of two-step crystallization and the subsequent B2-phase transformation was presented in Cu46Zr47Al6Co1 bulk metallic glass (BMG) during heating process. Thermophysical properties, i.e. the thermal diffusivity and the specific heat capacity, of the BMG in amorphous solid state and supercooled liquid state as well as its crystalline counterparts were measured from room temperature to 1070 K. The thermal conductivity was also calculated through combination of the data of the thermal diffusivity and the specific heat capacity. The possible influence of the crystallization on the thermophysical properties was discussed.
Methodology Matters: Measuring Urban Spatial Development Using Alternative Methods
Authors: Orenstein Daniel E , Frenkel Amnon , Jahshan Faris
Published: November 2013

The effectiveness of policies implemented to prevent urban sprawl has been a contentious issue among scholars and practitioners for at least two decades. While disputes range from the ideological to the empirical, regardless of the subject of dispute, participants must bring forth reliable data to buttress their claims. In this study we discuss several sources of complexity inherent in measuring sprawl. We then exhibit how methodological decisions can lead to disparate results regarding the quantification and characterization of sprawl. We do so by employing three GIS-based methods for quantifying the amount and defining the configuration of land-cover change from open to built space in a 350 km2 area in central Israel over a five-year period. We then calculate values for a variety of spatial indices commonly associated with urban sprawl. Our results reveal that some urban growth patterns are so robust that multiple methods and indices yield similar results and thus lead to similar conclusions. However, we also note that many divergent and even contradictory results are produced depending on the measurement method used and the index selection.
Predicting pH buffering capacity of New Zealand soils from organic matter content and mineral characteristics
Authors: Curtin Denis , Trolove Stephen
Published: November 2013

Information on the pH buffer capacity of soil is required to estimate changes in pH due to acidic or alkaline inputs, and to model pH-dependent processes within the soil nitrogen (N) cycle. The objective was to determine whether a model based on soil organic matter (SOM) and mineral characteristics (clay content, extractable iron (Fe) and aluminium (Al)) would be adequate to estimate the buffer capacities of New Zealand soils. We measured pH changes in 34 soils, representing a range of SOM and texture, after equilibration with several rates (range 0–15 cmol OH– kg–1 soil) of either KOH or Ca(OH)2. The Ca(OH)2 method often yielded higher buffer capacity values than the KOH method, possibly because of incomplete reaction of Ca(OH)2, especially at high addition rates. Buffer capacity (measured using KOH) of the soils was strongly correlated with soil carbon (C) (R2 = 0.76), and weakly (but significantly, P < 0.05) with clay content, and with dithionite extractable Fe and Al. A regression with soil C, clay, and P-retention (a surrogate for extractable Al and Fe) as independent variables explained 90% of the variability in pH buffering. The role of organic matter was further evaluated by measuring buffer capacity of soil from research plots at Lincoln, Canterbury, New Zealand, that differed in C (21–37 g C kg–1 in the top 7.5 cm; 19–26 g C kg–1 in the 7.5–15 cm) as a result of the treatments imposed during the 12-year trial period. A substantial decrease in pH buffering (by up to 24% in top 7.5 cm) was associated with a decline in SOM following the conversion of permanent pasture (pre-trial land use) to arable cropping. Across all treatments and sampling depths, buffer capacity was linearly related (R2 = 0.84, P < 0.001) to soil C; the estimated buffer capacity of SOM was 89 cmolc kg–1 C pH unit–1, similar to the value calculated from the previous study with different soil types. After 12 years, treatments with low soil C concentrations tended to be more acidic, possibly partly because of weaker pH buffering.
Transcription-factor binding and sliding on DNA studied using micro- and macroscopic models
Authors: Marklund Erik G. , Mahmutovic Anel , Berg Otto G. , Hammar Petter , van der Spoel David , Fange David , Elf Johan
Published: November 2013

Significance

Transcription factors (TFs) are the major regulators of gene expression. We have used a combination of computer simulations and theoretical methods to explore the atomic details for how a model TF, the
lac
repressor, moves on DNA in search for its specific binding site. We find that it slides along the DNA along a helical path, which allows it to probe for specific binding in a major groove. The uniqueness in the study lies in that the fully atomistic molecular dynamics model allows us to estimate the microscopic interaction energies from the TF-DNA structure and that we have developed a theoretical tool to derive macroscopic, experimentally testable, predictions for DNA residence time and sliding lengths from the microscopic interaction energies.
Bringing integrated ecosystem assessments to real life: a scientific framework for ICES
Authors: Walther Yvonne M. , Möllmann Christian
Published: November 2013

An ecosystem approach to management (EAM) aims to secure a healthy ecosystem along with sustainable use of its goods and services. Although the main principles of EAM are agreed upon and desirable, wider implementation of EAM is still a challenge. The difficulties stem from unclear definition and communication of the EAM, lack of routines or protocols to develop ecosystem-based advice, inappropriate institutional structures, and communication issues between scientists, advisers, and managers. Integrated ecosystem assessment (IEA) is an instrument that has proven to help in the implementation of EAM. For successful implementation of EAM and IEA in the European regional seas context, an international forum is required that develops tailor-made EAM tools specific to the different regional ecosystems to overcome fragmented national strategies. We describe a multinational peer network of working groups developed within the International Council for the Exploration of the Sea (ICES) under the auspice of Science Steering Group on Regional Sea Programmes. Available is a wealth of data, expertise, scientific methods, and models for each regional sea. This network can be instrumental in advancing IEA for the implementation of EAM in the North Atlantic seas.
Showdown at the ILO? A Historical Perspective on the Employers’ Group’s 2012 Challenge to the Right to Strike
Authors: La Hovary Claire
Published: November 2013

In June 2012, the International Labour Organization’s (ILO) Employers’ group dramatically challenged the right to strike, interrupting usual proceedings within the organisation’s annual International Labour Conference. Among their many arguments was the fact that the ILO’s Committee of Experts on the Application of Conventions and Recommendations did not have a mandate to interpret conventions and could not therefore interpret the existence of a right to strike in a convention that does not explicitly mention this right. This has widely been seen as an unprecedented crisis, but the fact is that the Employers have regularly voiced their opposition to the right to strike since 1989, and it is moreover intertwined with deep-rooted questions regarding interpretation within the ILO. In other words, the questions raised by the Employers long predate the current (so-called) crisis. At the same time, however, until 1989, the Employers not only supported the interpretations of the Committee of Experts, but also supported the interpretation of a right to strike. In order to get to grips with this apparent paradox, this article explores the historical and political circumstances surrounding the Employers’ relationship with the right to strike within the ILO, highlighting how current events reflect a new position of power that is historically contingent, as well as a desire to reduce the ILO’s influence.
Transgenic Expression of the Functional Fragment Hpa110-42of the Harpin Protein Hpa1 Imparts Enhanced Resistance to Powdery Mildew in Wheat
Authors: Wang Defu , Wang Yajun , Fu Maoqiang , Mu Shuyuan , Han Bing , Ji Hongtao , Cai Hongsheng , Dong Hansong , Zhang Chunling
Published: November 2013

Powdery mildew, one of devastating diseases of wheat worldwide, is caused by Erysiphe graminis f. sp. tritici, a fungal species with constant population changes, which often poses challenges in disease management with host resistance. Transgenic approaches that utilize broad-spectrum resistance may limit changes of pathogen populations and contribute to effective control of the disease. The harpin protein Hpa1, produced by the rice bacterial blight pathogen, can induce resistance to bacterial blight and blast in rice. The fragment comprising residues 10 through 42 of Hpa1, Hpa110-42, is reportedly three- to eightfold more effective than the full-length protein. This study evaluated the transgenic expression of the Hpa110-42gene for resistance to powdery mildew in wheat caused by E. graminis f. sp. tritici. Nine Hpa110-42transgenic wheat lines were generated. The genomic integration of Hpa110-42was confirmed, and expression of the transgene was detected at different levels in the individual transgenic lines. Following inoculation with the E. graminis f. sp. tritici isolate Egt15 in the greenhouse, five transgenic lines had significantly higher levels of resistance to powdery mildew compared with nontransformed plants. Thus, transgenic expression of Hpa110-42conferred resistance to one isolate of E. graminis f. sp. tritici in wheat in the greenhouse.
First Report of Diplodia pinea on Pseudotsuga menziesii in Turkey
Authors: Kaya A. G. A. , Lehtijärvi A. , Kaya Ö. , Doğmuş-Lehtijärvi T.
Published: November 2013

Diplodia pinea is a latent, opportunistic pathogen of Pinus and other coniferous species, including Pseudotsuga menziesii (3). The fungus causes twig blight, branch cankers, tree and seedling collar rot, root rot, and can also infect cones (1). D. pinea has often been reported causing tip and shoot blight on various Pinus spp. in different parts of Turkey. During disease surveys on Pinus spp. carried out in May 2012 in Izmit in the Marmara Region (37°36′54″N, 31°20′00″E), typical shoot blight symptoms of D. pinea infection were also observed on the neighboring P. menziesii trees. Shoots and cones of P. menziesii were investigated for the presence of D. pinea pycnidia. Pycnidia from cones and shoots were placed on potato dextrose agar (PDA) and incubated at 23°C. Three isolates were obtained from shoot and cone samples. Identification of the pathogen was based on morphological characteristics of the conidia and by PCR of the ITS region of nuclear rDNA. Colonies on PDA were woolly, whitish at first turning black, sometimes partly or entirely turning light gray. Micromorphological characteristics of the Diplodia isolates were similar to those described in (2): conidia width 18.4 μm (SD ± 2.8) (range 11 to 22 μm) × length 34.0 μm (SD ± 5.3) (range 20 to 41 μm) (n = 100). Conidia were at first hyaline, later becoming brown to dark brown, oblong ellipsoid, bicellular with a distinct septum. To confirm the identity of the isolates, genomic DNA was extracted and the internal transcribed spacer (ITS) region of the rDNA was amplified using primers ITS1 and ITS4 (4). Amplicons were 483 bp in length (GenBank Accession No. KF372874) and shared 98% nucleotide identity with HM100285.1 and 97% nucleotide identity with JX981458.1 of D. pinea. Inoculation tests were performed on 2-year-old P. menziesii seedlings by placing mycelial plugs of three isolates obtained from pycnidia on the main stem after wounding with a cork borer. Control seedlings were inoculated with PDA plugs without mycelium. All seedlings were incubated at 24°C for 3 weeks in a climate chamber. Following incubation, the seedlings displayed dark brown-to-black discoloration, measuring on average 10.7 ± 0.6 cm, of the bark and wood tissues around the inoculation points on the stems. The pathogen was successfully re-isolated from symptomatic stem tissues, thus fulfilling Koch's postulates. To our knowledge, this is the first report of P. menziesii as a host of D. pinea in Turkey. P. menziesii is not endemic to Turkey and to date has a limited distribution (approximately 140 ha), but it is an important fast growing tree species for new industrial plantations.

References: (1) J. de Wet. PhD thesis, University of Pretoria, 2008. (2) J. de Wet et al. Plant Dis. 84:151, 2000. (3) G. Hausner et al. Can. J. Plant Pathol. 21:256, 1999. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.
First Report of Leaf Spot Caused by Alternaria alternata on Chinese Dwarf Banana in China
Authors: Fu B. Z. , Zhang Z. H. , Wang L. H. , Li G. Y. , Zhang J. Z. , Zhang Y.
Published: November 2013

The Chinese dwarf banana (Ensete lasiocarpum) is one of the ornamental bananas that belongs to Musaceae family. The plant is native to the southwestern China, where it grows semi-wild in the mountains between 1,500 and 2,500 m above sea level. During July 2011, a leaf spot disease on this plant was observed in the campus and parks in Kunming, Yunnan Province. The incidence level was about 22%, mainly on the old leaves. The leaf symptoms were irregular spots with gray to off-white centers surrounded by dark brown margins, and usually also surrounded by chlorotic halos. Leaf tissues (3 × 5 mm), cut from the margins of lesions, were surface-disinfected (95% ethanol for 3 min, 0.1% HgCl2 for 2 min, rinsed three times with sterile water), plated on potato sucrose agar (PSA), and incubated at 26°C under natural lights. The same fungus was consistently isolated from the diseased leaves. Colonies of white-to-dark gray mycelia formed on PSA that were black on the underside. The colonies were further identified as Alternaria sp. based on the dark brown, obclavate to obpyriform catenulate conidia with longitudinal and transverse septa tapering to a prominent beak attached in chains on a simple and short conidiophore (2). Conidia were 5.26 to 30.26 μm long and 3.95 to 15.79 μm wide, averaging 10.21 (±3.17) × 20.02 (±5.75) μm (n = 50), with a beak length of 0 to 7.89 μm, and had 3 to 8 transverse and 0 to 3 longitudinal septa. PCR amplification was carried out by utilizing universal rDNA-ITS primer pair ITS4/ITS5 (1). The ITS region of isolate DY1 (GenBank Accession No. KF516556) was 572 bp in length. BLAST search revealed 99% identity with two Alternaria alternata isolates (JF440581.1 and GQ121322.2). Phylogenetic analysis (MEGA 5.1) using the neighbor-joining algorithm placed the isolate in a well-supported cluster with other A. alternata isolates. The pathogen was identified as A. alternate (Fr.:Fr.) Keissler based on the morphological characteristics and rDNA-ITS sequence analysis. To confirm pathogenicity, Koch's postulates were performed on detached leaves of E. lasiocarpum inoculated with mycelial plugs with ddH2O and agar plugs as a control. Leaf spots identical to those observed in the field developed in 9 days on the inoculated leaves but not on the control. The inoculation assay used three leaves, totaling 72 spots for control and 36 spots for inoculation. The experiments were repeated once. A. alternata was consistently re-isolated from the inoculated leaves. The symptom developed easier with wounds. To our knowledge, this is the first report of E. lasiocarpum leaf spot disease caused by A. alternata in China and the world.

References: (1) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990. (2) T. Y. Zhang. Flora Fungorum Sinicorum, Vol. 16: Alternaria. Science Press, Beijing, China, 2003.
Epidemiology of Blackberry chlorotic ringspot virus
Authors: Poudel Bindu , Ho Thien , Laney Alma , Khadgi Archana , Tzanetakis Ioannis E.
Published: November 2013

The pollen- and seed-borne ilarviruses pose a substantial threat to many specialty crops, including berries, rose, and tree fruit, because there are no efficient control measures other than avoidance. The case of Blackberry chlorotic ringspot virus (BCRV) is of particular interest because the virus has been found to be an integral part of blackberry yellow vein disease and is widespread in rose plants affected by rose rosette disease. This study provides insight into the epidemiology of BCRV, including incidence in blackberry and rose; host range, with the addition of apple as a host of the virus; and seed transmission that exceeded 50% in rose. Sensitive detection protocols that can be used to avoid dissemination of infected material through nurseries and breeding programs were also developed.
Aspergillus parasiticusCommunities Associated with Sugarcane in the Rio Grande Valley of Texas: Implications of Global Transport and Host Association WithinAspergillusSectionFlavi
Authors: Garber N. P. , Cotty P. J.
Published: November 2013

In the Rio Grande Valley of Texas (RGV), values of maize and cottonseed crops are significantly reduced by aflatoxin contamination. Aflatoxin contamination of susceptible crops is the product of communities of aflatoxin producers and the average aflatoxin-producing potentials of these communities influence aflatoxin contamination risk. Cropping pattern influences community composition and, thereby, the epidemiology of aflatoxin contamination. In 2004, Aspergillus parasiticus was isolated from two fields previously cropped to sugarcane but not from 23 fields without recent history of sugarcane cultivation. In 2004 and 2005, A. parasiticus composed 18 to 36% of Aspergillus section Flavi resident in agricultural soils within sugarcane-producing counties. A. parasiticus was not detected in counties that do not produce sugarcane. Aspergillus section Flavi soil communities within sugarcane-producing counties differed significantly dependent on sugarcane cropping history. Fields cropped to sugarcane within the previous 5 years had greater quantities of A. parasiticus (mean = 16 CFU/g) than fields not cropped to sugarcane (mean = 0.1 CFU/g). The percentage of Aspergillus section Flavi composed of A. parasiticus increased to 65% under continuous sugarcane cultivation and remained high the first season of rotation out of sugarcane. Section Flavi communities in fields rotated to non-sugarcane crops for 3 to 5 years were composed of <5% A. parasiticus, and fields with no sugarcane history averaged only 0.2% A. parasiticus. The section Flavi community infecting RGV sugarcane stems ranged from 95% A. parasiticus in billets prepared for commercial planting to 52% A. parasiticus in hand-collected sugarcane stems. Vegetative compatibility assays and multilocus phylogenies verified that aflatoxin contamination of raw sugar was previously attributed to similar A. parasiticus in Japan. Association of closely related A. parasiticus genotypes with sugarcane produced in Japan and RGV, frequent infection of billets by these genotypes, and the ephemeral nature of A. parasiticus in RGV soils suggests global transport with sugarcane planting material.
Molecular Detection of Peronospora variabilis in Quinoa Seed and Phylogeny of the Quinoa Downy Mildew Pathogen in South America and the United States
Authors: Testen Anna L. , del Mar Jiménez-Gasco María , Ochoa José B. , Backman Paul A.
Published: November 2013

Quinoa (Chenopodium quinoa) is an important export of the Andean region, and its key disease is quinoa downy mildew, caused by Peronospora variabilis. P. variabilis oospores can be seedborne and rapid methods to detect seedborne P. variabilis have not been developed. In this research, a polymerase chain reaction (PCR)-based detection method was developed to detect seedborne P. variabilis and a sequencing-based method was used to validate the PCR-based method. P. variabilis was detected in 31 of 33 quinoa seed lots using the PCR-based method and in 32 of 33 quinoa seed lots using the sequencing-based method. Thirty-one of the quinoa seed lots tested in this study were sold for human consumption, with seed originating from six different countries. Internal transcribed spacer (ITS) and cytochrome c oxidase subunit 2 (COX2) phylogenies were examined to determine whether geographical differences occurred in P. variabilis populations originating from Ecuador, Bolivia, and the United States. No geographical differences were observed in the ITS-derived phylogeny but the COX2 phylogeny indicated that geographical differences existed between U.S. and South American samples. Both ITS and COX2 phylogenies supported the existence of a Peronospora sp., distinct from P. variabilis, that causes systemic-like downy mildew symptoms on quinoa in Ecuador. The results of these studies allow for a better understanding of P. variabilis populations in South America and identified a new causal agent for quinoa downy mildew. The PCR-based seed detection method allows for the development of P. variabilis-free quinoa seed, which may prove important for management of quinoa downy mildew.
The Reverse Remodeling Effect of Mesenchymal Stem Cells is Independent from the Site of Epimyocardial Cell Transplantation
Authors: Arsalan Mani , Dhein Stefan , Aupperle Heike , Rastan Ardawan Julian , Barten Markus Jan , Walther Thomas , Mohr Friedrich Wilhelm , Garbade Jens
Published: November 2013

Objective

The transplantation of mesenchymal stem cells (MSCs) represents a promising approach for treating the ischemic and the nonischemic diseased heart. The positive effects of transplanting these cells could be shown, but the exact mechanisms remain unknown. We evaluated whether the injection site affects the improvement in left ventricular (LV) ejection fraction (EF) and angiogenesis in doxorubicin (Dox)–induced failing hearts.

Methods

Heart failure was induced in New Zealand white rabbits by doxorubicin treatment, followed by right ventricular MSC transplantation (RV-MSC, n = 6), LV MSC transplantation (LV-MSC, n = 6), sham treatment (sham group, n = 6), or no therapy (Dox group, n = 5). Healthy rabbits were used as control group (n = 8). Cells were isolated after bone marrow aspiration and transplanted locally into the ventricular myocardium. After 4 weeks, cardiac function and capillary density (CD31 staining) were measured.

Results

The transplantation of MSCs increased the EF significantly (LV-MSC, 39.0% ± 1.4%, and RV-MSC, 39.2% ± 2.6%, vs sham group, 29.8% ± 3.7%; P < 0.001), without significance between the MSC groups ( P = 0.858). Neither the evidence of a transdifferentiation nor any signs of cell engraftment of transplanted cells could be found. The capillary density (capillaries/high-power field) increased in both MSC groups compared with the sham group (LV-MSC by 8.3% ± 3.4%; and RV-MSC, 8.1% ± 2.2%; P < 0.05), without significance between the two MSC groups ( P = 0.927).

Conclusions

Injection of autologous MSCs in doxorubicin-induced cardiomyopathic rabbit hearts improves EF and enhances angiogenesis. Despite local application, we observed global effects on heart function and capillary density without significant difference between right and LV injection. The paracrine mechanism might be one possible explanation for these findings.
Alternative male reproductive tactics drive asymmetrical hybridization between sunfishes (
Lepomis
spp.)
Authors: Garner Shawn R. , Neff Bryan D.
Published: November 2013

The potential role of alternative reproductive tactics in circumventing premating isolating mechanisms and driving hybridization between species has long been recognized, but to date there is little empirical support from natural systems. Hybridization occurs between bluegill (
Lepomis macrochirus
) and pumpkinseed sunfish (
Lepomis gibbosus
) and it is known to be asymmetrical (male bluegill × female pumpkinseed). Here, we test whether this pattern is driven by a recognition failure by pumpkinseed females or by an alternative cuckolder reproductive tactic in bluegill males. Using genetic parentage data, we found that bluegill cuckolders fathered 24.9% of the larvae in bluegill nests, but no evidence that pumpkinseed females spawned in bluegill nests. Pumpkinseed cuckolders fathered 8.7% of the larvae in pumpkinseed nests, whereas bluegill cuckolders fathered 13.6% of the larvae in those nests. Bluegill cuckolders thus frequently spawn in pumpkinseed nests and are responsible for the asymmetrical hybridization between the species. We discuss the evolutionary consequences of interactions between bluegill and pumpkinseed and the role of alternative reproductive tactics in adaptation and introgression.
Oxytocin shapes parental motion during father–infant interaction
Authors: Weisman Omri , Delaherche Emilie , Rondeau Margot , Chetouani Mohamed , Cohen David , Feldman Ruth
Published: November 2013

An infant-oriented parental repertoire contributes to an infant's development and well-being. The role of oxytocin (OT) in promoting affiliative bonds and parenting has been established in numerous animal and human studies. Recently, acute administration of OT to a parent was found to enhance the carer's, but at the same time also the infant's, physiological and behavioural readiness for dyadic social engagement. Yet, the exact cues that are involved in this affiliative transmission process remain unclear. The existing literature suggests that motion and vocalization are key social signals for the offspring that facilitates social participation, and that distance and motion perception are modulated by OT in humans. Here, we employed a computational method on video vignettes of human parent–infant interaction including 32 fathers that were administered OT or a placebo in a crossover experimental design. Results indicate that OT modulates parental proximity to the infant, as well as the father's head speed and head acceleration but not the father's vocalization during dyadic interaction. Similarly, the infant's OT reactivity is positively correlated with father's head acceleration. The current findings are the first to report a relationship between the OT system and parental motion characteristics, further suggesting that the cross-generation transmission of parenting in humans might be underlaid by nuanced, infant-oriented, gestures relating to the carer's proximity, speed and acceleration within the dyadic context.
Alternative mating tactics in the yellow dung fly: resolving mechanisms of small-male advantage off pasture
Authors: Gress Brian E. , Waltzer Ryan J. , Lüpold Stefan , Droge-Young Elizabeth M. , Manier Mollie K. , Pitnick Scott
Published: November 2013

Recent work suggests that the yellow dung fly mating system may include alternative patroller–competitor mating tactics in which large males compete for gravid females on dung, whereas small, non-competitive males search for females at foraging sites. Small males obtain most matings off pasture, yet the behavioural mechanism(s) giving rise to this pattern are unknown. We investigated the male and female behaviours that determine mating success in this environment by conducting field mating experiments and found small males to benefit from several attributes specific to the off-pasture mating environment. First, small males from foraging sites exhibited higher mating propensity, indicating that large males away from dung may be depleted of energy and/or sperm. Second, small males were more discriminating, being significantly less likely to attempt with non-gravid females, which are absent on dung but common off pasture. Third, non-gravid females were generally more likely to actively struggle and reject mating attempts; however, such behaviours occurred disproportionately more often with large males. Female
Scathophaga stercoraria
thus appear to preferentially mate with small males when off pasture. These findings challenge assumptions about male–female interactions in systems with alternative mating tactics and reveal hidden processes that may influence selection patterns in the field.
Differential allocation in a lekking bird: females lay larger eggs and are more likely to have male chicks when they mate with less related males
Authors: Sardell Rebecca J. , DuVal Emily H.
Published: November 2013

The differential allocation hypothesis predicts increased investment in offspring when females mate with high-quality males. Few studies have tested whether investment varies with mate relatedness, despite evidence that non-additive gene action influences mate and offspring genetic quality. We tested whether female lekking lance-tailed manakins (
Chiroxiphia lanceolata
) adjust offspring sex and egg volume in response to mate attractiveness (annual reproductive success, ARS), heterozygosity and relatedness. Across 968 offspring, the probability of being male decreased with increasing parental relatedness but not father ARS or heterozygosity. This correlation tended to diminish with increasing lay-date. Across 162 offspring, egg volume correlated negatively with parental relatedness and varied with lay-date, but was unrelated to father ARS or heterozygosity. Offspring sex and egg size were unrelated to maternal age. Comparisons of maternal half-siblings in broods with no mortality produced similar results, indicating differential allocation rather than covariation between female quality and relatedness or sex-specific inbreeding depression in survival. As males suffer greater inbreeding depression, overproducing females after mating with related males may reduce fitness costs of inbreeding in a system with no inbreeding avoidance, while biasing the sex of outbred offspring towards males may maximize fitness via increased mating success of outbred sons.
Sociality influences cultural complexity
Authors: Muthukrishna Michael , Shulman Ben W. , Vasilescu Vlad , Henrich Joseph
Published: November 2013

Archaeological and ethnohistorical evidence suggests a link between a population's size and structure, and the diversity or sophistication of its toolkits or technologies. Addressing these patterns, several evolutionary models predict that both the size and social interconnectedness of populations can contribute to the complexity of its cultural repertoire. Some models also predict that a sudden loss of sociality or of population will result in subsequent losses of useful skills/technologies. Here, we test these predictions with two experiments that permit learners to access either one or five models (teachers). Experiment 1 demonstrates that naive participants who could observe five models, integrate this information and generate increasingly effective skills (using an image editing tool) over 10 laboratory generations, whereas those with access to only one model show no improvement. Experiment 2, which began with a generation of trained experts, shows how learners with access to only one model lose skills (in knot-tying) more rapidly than those with access to five models. In the final generation of both experiments, all participants with access to five models demonstrate superior skills to those with access to only one model. These results support theoretical predictions linking sociality to cumulative cultural evolution.
Surface proteins of group G Streptococcus in different phases of growth: patterns of production and implications for the host–bacteria relationship
Authors: Wollein Waldetoft Kristofer , Karlsson Christofer , Gram Magnus , Malmström Johan , Mörgelin Matthias , Frick Inga-Maria , Björck Lars
Published: November 2013

Group GStreptococcus(GGS) is a human bacterial pathogen expressing surface proteins FOG and protein G (PG) which interact with several host defence systems, including the complement and contact systems. Selected reaction monitoring mass spectrometry, electron microscopy and protein binding assays were used to track the amounts of FOG and PG intracellularly and on the bacterial surface during different phases of growth. Large and increasing amounts of PG were present on the surface in the stationary growth phase, and this was due tode novoproduction. In contrast, the amount of FOG did not change substantially during this phase. Apart from PG, a number of housekeeping proteins also increased in abundance in the stationary phase. These results show that GGS protein production is active during the stationary phase and that the bacteria actively remodel their surface and enter a less pro-inflammatory state in this phase.
Temperature-dependence of yadBC phenotypes in Yersinia pestis
Authors: Uittenbogaard Annette M. , Myers-Morales Tanya , Gorman Amanda A. , Welsh Erin , Wulff Christine , Hinnebusch B. Joseph , Korhonen Timo K. , Straley Susan C.
Published: November 2013

YadB and YadC are putative trimeric autotransporters present only in the plague bacterium Yersinia pestis and its evolutionary predecessor, Yersinia pseudotuberculosis. Previously, yadBC was found to promote invasion of epithelioid cells by Y. pestis grown at 37 °C. In this study, we found that yadBC also promotes uptake of 37 °C-grown Y. pestis by mouse monocyte/macrophage cells. We tested whether yadBC might be required for lethality of the systemic stage of plague in which the bacteria would be pre-adapted to mammalian body temperature before colonizing internal organs and found no requirement for early colonization or growth over 3 days. We tested the hypothesis that YadB and YadC function on ambient temperature-grown Y. pestis in the flea vector or soon after infection of the dermis in bubonic plague. We found that yadBC did not promote uptake by monocyte/macrophage cells if the bacteria were grown at 28 °C, nor was there a role of yadBC in colonization of fleas by Y. pestis grown at 21 °C. However, the presence of yadBC did promote recoverability of the bacteria from infected skin for 28 °C-grown Y. pestis. Furthermore, the gene for the proinflammatory chemokine CXCL1 was upregulated in expression if the infecting Y. pestis lacked yadBC but not if yadBC was present. Also, yadBC was not required for recoverability if the bacteria were grown at 37 °C. These findings imply that thermally induced virulence properties dominate over effects of yadBC during plague but that yadBC has a unique function early after transmission of Y. pestis to skin.