657 research outputs found

    A Critical-Angle Ultrasonic Technique for the Inspection of Wood Parallel-to-Grain

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    The objective of this paper is to present a critically refracted longitudinal wave (LCR) technique that allows localized ultrasonic inspection of wood parallel-to-grain by accessing only a single side of the material. The LCR technique has been widely applied to other materials, but not to wood. The chief advantage of the LCR technique is that ultrasonic waves can be transmitted through wood at frequencies much higher than previously possible (up to 1.5 MHz), leading to potential gains in sensitivity over lower frequency methods.The LCR technique was verified using southern pine lumber. Transducer beam characteristics were examined and the influence of growth ring angle was observed. Ultrasonic wave energy was found to travel near to the inspection surface. Further, localized growth ring angle was significantly correlated to signal amplitude and frequency

    The domestication of the probiotic bacterium Lactobacillus acidophilus

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    Lactobacillus acidophilus is a Gram-positive lactic acid bacterium that has had widespread historical use in the dairy industry and more recently as a probiotic. Although L. acidophilus has been designated as safe for human consumption, increasing commercial regulation and clinical demands for probiotic validation has resulted in a need to understand its genetic diversity. By drawing on large, well-characterised collections of lactic acid bacteria, we examined L. acidophilus isolates spanning 92 years and including multiple strains in current commercial use. Analysis of the whole genome sequence data set (34 isolate genomes) demonstrated L. acidophilus was a low diversity, monophyletic species with commercial isolates essentially identical at the sequence level. Our results indicate that commercial use has domesticated L. acidophilus with genetically stable, invariant strains being consumed globally by the human population

    Ultrasonic Detection of a Plastic Hinge in Bolted Timber Connections

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    Connections between structural members are critical elements that typically govern the performance of structural systems; hence, techniques for monitoring the condition of connections are needed to provide early warning of structural damage. Plastic hinge formation in fasteners frequently occurs in timber connections when the yield capacity is exceeded. An innovative pulse echo testing technique was developed for detecting the formation of a plastic hinge in bolted timber connections and estimating the associated magnitude of connection displacement. A shift in overall signal centroid proved to be the best flTedictor of plastic hinge formation, with a coefficient of determination (R2) of 0.9. As the plastic hinge angle increased, the signal centroid shifted to the right since a higher proportion of pulse energy was forced to undergo multiple transverse wave reflections caused by the deformed geometry of the bolt. Because the determination of a shift in signal centroid requires the availability of prior test information for the initially undeformed fastener, an alternate linear relationship between echo amplitude ratios and plastic hinge formation was also proposed with an adjusted R2 of 0.87. This three parameter regression equation had the advantages of requiring no prior testing information and eliminating ambiguity in signal analysis associated with selection of echo start and end points. Plastic hinge formation was correlated with connection ductility, magnitude of connection overload and energy based measures of connection damage to assess residual connection capacity

    LUNASKA simultaneous neutrino searches with multiple telescopes

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    The most sensitive method for detecting neutrinos at the very highest energies is the lunar Cherenkov technique, which employs the Moon as a target volume, using conventional radio telescopes to monitor it for nanosecond-scale pulses of Cherenkov radiation from particle cascades in its regolith. Multiple-antenna radio telescopes are difficult to effectively combine into a single detector for this purpose, while single antennas are more susceptible to false events from radio interference, which must be reliably excluded for a credible detection to be made. We describe our progress in excluding such interference in our observations with the single-antenna Parkes radio telescope, and our most recent experiment (taking place the week before the ICRC) using it in conjunction with the Australia Telescope Compact Array, exploiting the advantages of both types of telescope.Comment: 4 pages, 4 figures, in Proceedings of the 32nd International Cosmic Ray Conference (Beijing 2011

    Preharvest Quarantine Treatments of Chlorantraniliprole, Clothianidin, and Imidacloprid-Based Insecticides for Control of Japanese Beetle (Coleoptera: Scarabaeidae) and Other Scarab Larvae in the Root Zone of Field-Grown Nursery Trees

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    Japanese beetle, Popillia japonica Newman (Coleoptera: Scarabaeidae), is an important quarantine pest of nurseries. Nursery plant movement from P. japonica-infested regions is regulated by the U.S. Domestic Japanese Beetle Harmonization Plan (DJHP), which classifies states by risk categories. Treatments for category 2 states include preharvest soil surface treatment of nursery plants grown in field soil using Discus SC, Marathon (1G or 60 WP), or Flagship (0.22G or 25 WG). In this study, Discus, Marathon 60 WP, or Flagship 0.22G DJHP standards were compared with labeled rates of non–DJHP-approved insecticides, including neonicotinoids clothianidin (Arena 50WDG), generic imidacloprid (Quali-Pro Imidacloprid 2 F T&O Insecticide, Mallet 2 F T&O Insecticide, and Lada 2 F Insecticide), and imidacloprid + bifenthrin (Allectus SC), as well as the anthranilic diamide, chlorantraniliprole (Acelepryn Insecticide). Arena provided 100% P. japonica control in May, June, and July over four test years, but had one larva recovered during August in two of those 4 yr. Acelepryn did not provide DJHP-acceptable P. japonica control. During July, Allectus provided 100% P. japonica control in three of four test years, but had four larvae in one test year. Other treatments tested only during July, which provided 100% P. japonica control, included Discus (five tests); Marathon, Quali-Pro, and Mallet (two tests); and Lada and Flagship (one test). Generic imidacloprid 2 F formulations were equivalent in P. japonica control to DJHP-approved insecticides. Insecticides generally performed poorly on other scarabs or curculionid larvae. The study supports Arena, Allectus, and generic imidacloprid 2 F products as suitable candidates for the DJHP

    Open-access bacterial population genomics: BIGSdb software, the PubMLST.org website and their applications [version 1; referees: 2 approved]

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    The PubMLST.org website hosts a collection of open-access, curated databases that integrate population sequence data with provenance and phenotype information for over 100 different microbial species and genera.  Although the PubMLST website was conceived as part of the development of the first multi-locus sequence typing (MLST) scheme in 1998 the software it uses, the Bacterial Isolate Genome Sequence database (BIGSdb, published in 2010), enables PubMLST to include all levels of sequence data, from single gene sequences up to and including complete, finished genomes.  Here we describe developments in the BIGSdb software made from publication to June 2018 and show how the platform realises microbial population genomics for a wide range of applications.  The system is based on the gene-by-gene analysis of microbial genomes, with each deposited sequence annotated and curated to identify the genes present and systematically catalogue their variation.  Originally intended as a means of characterising isolates with typing schemes, the synthesis of sequences and records of genetic variation with provenance and phenotype data permits highly scalable (whole genome sequence data for tens of thousands of isolates) means of addressing a wide range of functional questions, including: the prediction of antimicrobial resistance; likely cross-reactivity with vaccine antigens; and the functional activities of different variants that lead to key phenotypes.  There are no limitations to the number of sequences, genetic loci, allelic variants or schemes (combinations of loci) that can be included, enabling each database to represent an expanding catalogue of the genetic variation of the population in question.  In addition to providing web-accessible analyses and links to third-party analysis and visualisation tools, the BIGSdb software includes a RESTful application programming interface (API) that enables access to all the underlying data for third-party applications and data analysis pipelines

    IL-15 and PIM kinases direct the metabolic programming of intestinal intraepithelial lymphocytes

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    Intraepithelial lymphocytes (IEL) respond to IL-15 complexed with IL-15Ra but how this intrinsically affects IEL is unclear. Here the authors use proteomics analyses of the main mouse IEL subsets and identify PIM kinases as essential for IEL proliferation, metabolism and effector function downstream of IL-15

    Increased yield stability of field-grown winter barley (Hordeum vulgare L.) varietal mixtures through ecological processes

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    Crop variety mixtures have the potential to increase yield stability in highly variable and unpredictable environments, yet knowledge of the specific mechanisms underlying enhanced yield stability has been limited. Ecological processes in genetically diverse crops were investigated by conducting field trials with winter barley varieties (Hordeum vulgare), grown as monocultures or as three-way mixtures in fungicide treated and untreated plots at three sites. Mixtures achieved yields comparable to the best performing monocultures whilst enhancing yield stability despite being subject to multiple predicted and unpredicted abiotic and biotic stresses including brown rust (Puccinia hordei) and lodging. There was compensation through competitive release because the most competitive variety overyielded in mixtures thereby compensating for less competitive varieties. Facilitation was also identified as an important ecological process within mixtures by reducing lodging. This study indicates that crop varietal mixtures have the capacity to stabilise productivity even when environmental conditions and stresses are not predicted in advance. Varietal mixtures provide a means of increasing crop genetic diversity without the need for extensive breeding efforts. They may confer enhanced resilience to environmental stresses and thus be a desirable component of future cropping systems for sustainable arable farming

    Wild bird-associated Campylobacter jejuni isolates are a consistent source of human disease, in Oxfordshire, United Kingdom

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    The contribution of wild birds as a source of human campylobacteriosis was investigated in Oxfordshire, United Kingdom (UK) over a 10 year period. The probable origin of human Campylobacter jejuni genotypes, as described by multilocus sequence typing, was estimated by comparison with reference populations of isolates from farm animals and five wild bird families, using the STRUCTURE algorithm. Wild bird-attributed isolates accounted for between 476 (2.1%) and 543 (3.5%) cases annually. This proportion did not vary significantly by study year (P = 0.934) but varied seasonally, with wild bird-attributed genotypes comprising a greater proportion of isolates during warmer compared with cooler months (P = 0.003). The highest proportion of wild bird-attributed illness occurred in August (P < 0.001), with a significantly lower proportion in November (P = 0.018). Among genotypes attributed to specific groups of wild birds, seasonality was most apparent for Turdidae-attributed isolates, which were absent during cooler, winter months. This study is consistent with some wild bird species representing a persistent source of campylobacteriosis, and contributing a distinctive seasonal pattern to disease burden. If Oxfordshire is representative of the UK as a whole in this respect, these data suggest that the national burden of wild bird-attributed isolates could be in the order of 10,000 annually
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