2,631 research outputs found
Novel Precursors for Boron Nanotubes: The Competition of Two-Center and Three-Center Bonding in Boron Sheets
We present a new class of boron sheets, composed of triangular and hexagonal
motifs, that are more stable than structures considered to date and thus are
likely to be the precursors of boron nanotubes. We describe a simple and clear
picture of electronic bonding in boron sheets and highlight the importance of
three-center bonding and its competition with two-center bonding, which can
also explain the stability of recently discovered boron fullerenes. Our
findings call for reconsideration of the literature on boron sheets, nanotubes,
and clusters.Comment: 4 pages, 4 figures, 1 tabl
Activation of phonological and semantic codes in toddlers
What are the processes underlying word recognition in the toddler lexicon? Work with adults suggests that, by 5-years of age, hearing a word leads to cascaded activation of other phonologically, semantically and phono-semantically related words (Huang & Snedeker, 2010; Marslen-Wilson & Zwitserlood, 1989). Given substantial differences in children’s sensitivity to phonological and semantic relationships between words in the first few years of life (Arias-Trejo & Plunkett, 2010; Newman, Samuelson, & Gupta, 2009; Storkel & Hoover, 2012), the current set of experiments investigated whether children younger than five also show such phono-semantic priming. Using a picture-priming task, Experiments 1 and 2 presented 2-year-olds with phono-semantically related prime-target pairs, where the label for the prime image is phonologically related (Experiment 1 – onset CV overlap, Experiment 2 – rhyme VC overlap) to a semantic associate of the target label. Across both experiments, toddlers recognised a word faster when this was preceded by a phono-semantically related prime relative to an unrelated prime. Overall, the results provide strong evidence that word recognition involves cascaded processing of phono-semantically related words by 2-years of age
A corpus-based lexical analysis of Chinese medicine research articles.
This is the final version of the article. Available from the publisher via the URL in this record.This study investigates the usefulness of two academic word lists - Coxhead’s (2000) Academic Word List (AWL) and Gardner & Davies’ (2014) Academic Vocabulary List (AVL) - for students of English for Chinese Medical Purposes. The two academic word lists were evaluated in terms of the coverage they achieved in a corpus of Chinese medical research articles (CMRAs) written in English. The AWL was found to cover 10.64% of tokens in the corpus, while the AVL was found to cover 21.17% overall. In both cases, the majority of the coverage was achieved by a relatively small subset of the lexical items on the lists. Analysis of the most frequently used words that are not included in the General Service List, Academic Word List and Academic Vocabulary List in the CMRAs shows that a small number of such words achieve a high level of coverage, suggesting that they should be given a great deal of attention by learners in this discipline. This suggests that a discipline-specific listing would be of great benefit to learners in this discipline. A list of the most prominent 100 off-list lexical items is provided
Viral antibody dynamics in a chiropteran host
1. Bats host many viruses that are significant for human and domestic animal health, but the dynamics of these infections in their natural reservoir hosts remain poorly elucidated.<p></p>
2. In these, and other, systems, there is evidence that seasonal life-cycle events drive infection dynamics, directly impacting the risk of exposure to spillover hosts. Understanding these dynamics improves our ability to predict zoonotic spillover from the reservoir hosts.<p></p>
3. To this end, we followed henipavirus antibody levels of >100 individual E. helvum in a closed, captive, breeding population over a 30-month period, using a powerful novel antibody quantitation method.<p></p>
4. We demonstrate the presence of maternal antibodies in this system and accurately determine their longevity. We also present evidence of population-level persistence of viral infection and demonstrate periods of increased horizontal virus transmission associated with the pregnancy/lactation period.<p></p>
5.The novel findings of infection persistence and the effect of pregnancy on viral transmission, as well as an accurate quantitation of chiropteran maternal antiviral antibody half-life, provide fundamental baseline data for the continued study of viral infections in these important reservoir hosts
A kinetic and theoretical study of the borate catalysed reactions of hydrogen peroxide: the role of dioxaborirane as the catalytic intermediate for a wide range of substrates
Our recent work has provided new insights into the equilibria and species that exist in aqueous solution at different pHs for the boric acid – hydrogen peroxide system, and the role of these species in oxidation reactions. Most recently, (M. C. Durrant, D. M. Davies and M. E. Deary, Org. Biomol. Chem., 2011, 9,7249–7254), we have produced strong theoretical and experimental evidence for the existence of a previously unreported monocyclic three membered peroxide species, dioxaborirane, that is the likely catalytic species in borate mediated electrophilic reactions of hydrogen peroxide in alkaline solution. In the present paper, we extend our study of the borate–peroxide system to look at a wide range of substrates that include substituted dimethyl anilines, methyl-p-tolyl sulfoxide, halides, hydrogen sulfide anion, thiosulfate ,thiocyanate, and hydrazine. The unusual selectivity–reactivity pattern of borate catalysed reactions compared with hydrogen peroxide and inorganic or organic peracids previously observed for theorganic sulfides (D. M. Davies, M. E. Deary, K. Quill and R. A. Smith, Chem.–Eur. J., 2005, 11, 3552–3558) is also seen with substituted dimethyl aniline nucleophiles. This provides evidence that the pattern is not due to any latent electrophilic tendency of the organic sulfides and further supports dioxaborirane being the likely reactive intermediate, thus broadening the applicability of this catalytic system. Moreover, density functional theory calculations on our proposed mechanism involving dioxaborirane are consistent with the experimental results for these substrates. Results obtained at high concentrations of both borate and hydrogen peroxide require the inclusion the diperoxodiborate dianion in the kinetic analysis .A scheme detailing our current understanding of the borate–peroxide system is presented
Protecting Free-Living Dormice: Molecular Identification of Cestode Parasites in Captive Dormice (Muscardinus avellanarius) Destined for Reintroduction
The success of any population translocation programme relies heavily on the measures implemented to control and monitor the spread of disease. Without these measures, programmes run the risk of releasing immunologically naïve species or, more dangerously, introducing novel infectious agents to native populations. As a precaution, a reintroduction programme for the common or hazel dormouse, Muscardinus avellanarius, in England screens dormice before release following captive breeding. Using PCR sequencing of a range of genes, we tested whether the same species of tapeworm(s) were present in captive and free-living dormice. Whilst only Rodentolepis straminea were identified in free-living dormice, cestode ova found in a captive individual produced a molecular match closely related to Hymenolepis microstoma and a previously unrecorded Rodentolepis species. To prevent putting at risk the free-living population, we recommended the continued treatment of dormice showing tapeworm infection before release. Our work demonstrates how molecular techniques can be used to inform reintroduction programmes, reduce risk from disease and increase chances of reintroduction success
Inverse problem of photoelastic fringe mapping using neural networks
This paper presents an enhanced technique for inverse analysis of photoelastic fringes using neural networks to determine the applied load. The technique may be useful in whole-field analysis of photoelastic images obtained due to external loading, which may find application in a variety of specialized areas including robotics and biomedical engineering. The presented technique is easy to implement, does not require much computation and can cope well within slight experimental variations. The technique requires image acquisition, filtering and data extraction, which is then fed to the neural network to provide load as output. This technique can be efficiently implemented for determining the applied load in applications where repeated loading is one of the main considerations. The results presented in this paper demonstrate the novelty of this technique to solve the inverse problem from direct image data. It has been shown that the presented technique offers better result for the inverse photoelastic problems than previously published works
Rich pictures for stakeholder dialogue:A polyphonic picture book
We describe the design and use of a ‘polyphonic picture book’ for engaging stakeholders and research participants with findings from an interdisciplinary project investigating how UK citizens create and manage online identities at three significant life transitions. The project delivered socio-cultural and technical findings to inform policy-making and service innovation for enhancing digital literacy in online self-representation. The picture book presented findings through multi-perspectival, fictional scenarios about experiences of life transition. We describe our use of the book with our stakeholders in five workshop settings and our evaluation of the visual format for fostering stakeholder dialogue around the findings and their transferability. This paper contributes methodological insights about using visual storytelling to scaffold interpretative, dialogical contexts of research engagement
Gene expression in Leishmania is regulated predominantly by gene dosage
ABSTRACT Leishmania tropica, a unicellular eukaryotic parasite present in North and East Africa, the Middle East, and the Indian subcontinent, has been linked to large outbreaks of cutaneous leishmaniasis in displaced populations in Iraq, Jordan, and Syria. Here, we report the genome sequence of this pathogen and 7,863 identified protein-coding genes, and we show that the majority of clinical isolates possess high levels of allelic diversity, genetic admixture, heterozygosity, and extensive aneuploidy. By utilizing paired genome-wide high-throughput DNA sequencing (DNA-seq) with RNA-seq, we found that gene dosage, at the level of individual genes or chromosomal “somy” (a general term covering disomy, trisomy, tetrasomy, etc.), accounted for greater than 85% of total gene expression variation in genes with a 2-fold or greater change in expression. High gene copy number variation (CNV) among membrane-bound transporters, a class of proteins previously implicated in drug resistance, was found for the most highly differentially expressed genes. Our results suggest that gene dosage is an adaptive trait that confers phenotypic plasticity among natural Leishmania populations by rapid down- or upregulation of transporter proteins to limit the effects of environmental stresses, such as drug selection. IMPORTANCE Leishmania is a genus of unicellular eukaryotic parasites that is responsible for a spectrum of human diseases that range from cutaneous leishmaniasis (CL) and mucocutaneous leishmaniasis (MCL) to life-threatening visceral leishmaniasis (VL). Developmental and strain-specific gene expression is largely thought to be due to mRNA message stability or posttranscriptional regulatory networks for this species, whose genome is organized into polycistronic gene clusters in the absence of promoter-mediated regulation of transcription initiation of nuclear genes. Genetic hybridization has been demonstrated to yield dramatic structural genomic variation, but whether such changes in gene dosage impact gene expression has not been formally investigated. Here we show that the predominant mechanism determining transcript abundance differences (>85%) in Leishmania tropica is that of gene dosage at the level of individual genes or chromosomal somy
Detection of the European epidemic strain of Trichomonas gallinae in finches, but not other non-columbiformes, in the absence of macroscopic disease
Finch trichomonosis is an emerging infectious disease affecting European passerines caused by a clonal strain of Trichomonas gallinae. Migrating chaffinches (Fringilla coelebs) were proposed as the likely vector of parasite spread from Great Britain to Fennoscandia. To test for such parasite carriage, we screened samples of oesophagus/crop from 275 Apodiform, Passeriform and Piciform birds (40 species) which had no macroscopic evidence of trichomonosis (i.e. necrotic ingluvitis). These birds were found dead following the emergence of trichomonosis in Great Britain, 2009-2012, and were examined post-mortem. Polymerase chain reactions were used to detect (ITS1/5.8S rRNA/ITS2 region and single subunit rRNA gene) and to subtype (Fe-hydrogenase gene) T. gallinae. Trichomonas gallinae was detected in six finches (three chaffinches, two greenfinches (Chloris chloris) and a bullfinch (Pyrrhula pyrrhula)). Sequence data had 100% identity to the European finch epidemic A1 strain for each species. While these results are consistent with finches being vectors of T. gallinae, alternative explanations include the presence of incubating or resolved T. gallinae infections. The inclusion of histopathological examination would help elucidate the significance of T. gallinae infection in the absence of macroscopic lesions
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