2,634 research outputs found

    Can interaction specificity in the fungus-farming termite symbiosis be explained by nutritional requirements of the fungal crop?

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    <p>Fungus-growing termites are associated with genus-specific fungal symbionts, which they acquire via horizontal transmission. Selection of specific symbionts may be explained by the provisioning of specific, optimal cultivar growth substrates by termite farmers. We tested whether differences in in vitro performance of Termitomyces cultivars from nests of three termite species on various substrates are correlated with the interaction specificity of their hosts. We performed single-factor growth assays (varying carbon sources), and a two-factor geometric framework experiment (simultaneously varying carbohydrate and protein availability). Although we did not find qualitative differences between Termitomyces strains in carbon-source use, there were quantitative differences, which we analysed using principal component analysis. This showed that growth of Termitomyces on different carbon sources was correlated with termite host genus, rather than host species, while growth on different ratios and concentrations of protein and carbohydrate was correlated with termite host species. Our findings corroborate the interaction specificity between fungus-growing termites and Termitomyces cultivars and indicate that specificity between termite hosts and fungi is reflected both nutritionally and physiologically. However, it remains to be demonstrated whether those differences contribute to selection of specific fungal cultivars by termites at the onset of colony foundation.</p

    análise espacial e estatística

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    UID/SOC/04647/2013O tráfico de seres humanos é um fenómeno transnacional cujos impactos são sentidos a nível regional, nacional e local, estima-se que este crime afete 152 diferentes nacionalidades em 124 países (UNODC, 2014). Realizado pelo Observatório de Tráfico de Seres Humanos, o principal objetivo deste estudo é a produção de conhecimento útil para a definição de estratégias de prevenção e combate ao tráfico de seres humanos para fins de exploração laboral, com base na apresentação de um modelo analítico sustentado no paradigma sócio-ecológico. Focalizado na região do Alentejo (distritos de Beja, Évora e Portalegre), pretende-se que o modelo seja adaptável a outras regiões e em última instância, outros tipos de exploração e/ou tráfico. Baseando-se fundamentalmente na análise estatístico-espacial da área de estudo, a análise territorial efetuada engloba a problematização dos perfis, tendências e padrões territoriais do tráfico e criminalidade conexa (abordagem sistémica), integrados na análise do seu contexto sócio-ecológico.publishersversionpublishe

    Soybean growth and production under straw of maize, Urochloa brizantha, Conyza spp. and Digitaria insularis

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    Weeds can cause serious damage during soybean development, due to allelopathy, competition for water, light and nutrients. It is necessary to investigate the influence of straw, of weeds Conyza spp. and Digitaria insularis, in soybean growth, production and composition and grains. If there is influence of allelopathic compounds at the crop. The aim of this study was to evaluate the influence of straw of maize and Urochloa brizantha (A.Rich.) R.D.Webster crops and Conyza spp., D. insularis, on growth, production and composition of grains produced by soybean. Treatments consisted of the control (absence of straw), maize straw, Urochloa brizantha straw, Conyza spp. straw (500, 1000, 1500 or 2000 kg ha-1) and D. insularis straw (500, 1000, 1500 or 2000 kg ha-1). The chlorophyll index, height of plants and insertion of the first pod, stem diameter at the collar and at 5 cm from the collar, root dry mass, number of pods and grains, weight of total grains, weight of 100 grains, protein and nitrogen (N), catalase and peroxidase contents in grains were evaluated. There was no difference between treatments for plant height, first pod height and chlorophyll index, as well as for total pods and 100 grain weight and protein content, N content and peroxidase and carboxylase enzymatic activity of the grains produced. For stem diameter, a higher value was found for the treatment with maize straw compared to the control (no straw). For dry root matter, treatments without straw and with Conyza spp. straw up to 1500 kg ha-1, differed from the treatment with maize straw. Even in some respects they provided beneficial effects compared to the absence of straw, which indicates the importance of crop residues. No allelopathic effects of weeds were observed on the growth and development of soybean. Conyza spp., D. insularis, maize or U. brizantha straws do not negatively affect soybean growth, production and grain composition

    Centre selection for clinical trials and the generalisability of results: a mixed methods study.

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    BACKGROUND: The rationale for centre selection in randomised controlled trials (RCTs) is often unclear but may have important implications for the generalisability of trial results. The aims of this study were to evaluate the factors which currently influence centre selection in RCTs and consider how generalisability considerations inform current and optimal practice. METHODS AND FINDINGS: Mixed methods approach consisting of a systematic review and meta-summary of centre selection criteria reported in RCT protocols funded by the UK National Institute of Health Research (NIHR) initiated between January 2005-January 2012; and an online survey on the topic of current and optimal centre selection, distributed to professionals in the 48 UK Clinical Trials Units and 10 NIHR Research Design Services. The survey design was informed by the systematic review and by two focus groups conducted with trialists at the Birmingham Centre for Clinical Trials. 129 trial protocols were included in the systematic review, with a total target sample size in excess of 317,000 participants. The meta-summary identified 53 unique centre selection criteria. 78 protocols (60%) provided at least one criterion for centre selection, but only 31 (24%) protocols explicitly acknowledged generalisability. This is consistent with the survey findings (n = 70), where less than a third of participants reported generalisability as a key driver of centre selection in current practice. This contrasts with trialists' views on optimal practice, where generalisability in terms of clinical practice, population characteristics and economic results were prime considerations for 60% (n = 42), 57% (n = 40) and 46% (n = 32) of respondents, respectively. CONCLUSIONS: Centres are rarely enrolled in RCTs with an explicit view to external validity, although trialists acknowledge that incorporating generalisability in centre selection should ideally be more prominent. There is a need to operationalize 'generalisability' and incorporate it at the design stage of RCTs so that results are readily transferable to 'real world' practice

    On the Monophyly and Relationships of Several Genera of Hylini (Anura: Hylidae: Hylinae), with Comments on Recent Taxonomic Changes in Hylids

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    We present a molecular phylogenetic analysis of the hylid tribe Hylini, with the goals of testing the monophyly of the genera Duellmanohyla, Isthmohyla, and Ptychohyla and providing a discussion on the monophyly of Bromeliohyla, Charadrahyla, Ecnomiohyla, Exerodonta, Megastomatohyla, and Sarcohyla. Our results indicate the paraphyly of Ptychohyla, with Bromeliohyla and Duellmanohyla nested within it, and, as in previous analyses, the paraphyly of Duellmanohyla (due to Ptychohyla legleri and P. salvadorensis being nested within it). To resolve this situation, we restrict the contents of Ptychohyla, redelimit those of Duellmanohyla and Bromeliohyla, and erect two new genera, one to include the former Ptychohyla panchoi and P. spinipollex, and the other for the former Ptychohyla acrochorda, P. sanctaecrucis, P. zoque, and tentatively, P. erythromma. Exerodonta as currently defined is not monophyletic, inasmuch as Exerodonta juanitae is nested within Charadrahyla. Consequently, we transfer this species and, tentatively, E. pinorum to Charadrahyla. Also, we discuss some possible taxonomic problems within Exerodonta. Our results indicate that Isthmohyla is polyphyletic, the bromeliad-dwelling Isthmohyla melacaena being the sister taxon of our only exemplar of Bromeliohyla, B. bromeliacia. For this reason, we transfer I. melacaena to Bromeliohyla, rendering Isthmohyla monophyletic. The former Isthmohyla pictipes Group is shown to be paraphyletic due to having the non-monophyletic I. pseudopuma Group within it. Accordingly, we recognize a redelimited I. pseudopuma Group (contents: I. infucata and I. pseudopuma), an I. zeteki Group (contents: I. picadoi and I. zeteki), and a newly defined I. tica Group (contents: I. angustilineata, I. calypsa, I. debilis, I. graceae, I. lancasteri, I. pictipes, I. tica, I. rivularis, and, tentatively, I. insolita and I. xanthosticta). The three groups of Isthmohyla are supported by molecular evidence with jackknife support values > 90%, and two of them by putative morphological synapomorphies. We discuss the recognition of Dryophytes, Hyliola, Rheohyla, and Sarcohyla and whether it is useful to recognize Anotheca, Diaglena, and Triprion as three distinct, monotypic genera. Finally, we discuss a recent taxonomic proposal involving changes in rank and from ranked to unranked names in hylids that overall we consider to have been poorly justified and only superficially discussed.Fil: Faivovich, Julián. Universidad de Buenos Aires; ArgentinaFil: Pereyra, Martín Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Luna, María Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Hertz, Andreas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Blotto Acuña, Boris Leonardo. University Of Massachusetts Boston;Fil: Vásquez-Almazán, Carlos R.. Senckenberg Forschungsinstitut Und Naturmuseum;Fil: McCranie, James R.. Universidade de Sao Paulo; BrasilFil: Sánchez, David A.. Universidad de San Carlos de Guatemala; GuatemalaFil: Baêta, Délio. Universidad de San Carlos de Guatemala; GuatemalaFil: Araujo-Vieira, Katyuscia. University Of Texas At Arlington;Fil: Köhler, Gunther. Unesp-universidade Estadual Paulista;Fil: Kubicki, Brian. Universidade Federal do Rio de Janeiro; BrasilFil: Campbell, Jonathan A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Frost, Darrel R.. Senckenberg Forschungsinstitut Und Naturmuseum;Fil: Wheeler, Ward C.. Costa Rican Amphibian Research Center; Costa RicaFil: Haddad, Célio F.B.. University Of Texas At Arlington

    MicroRNA-135b promotes cancer progression by acting as a downstream effector of oncogenic pathways in colon cancer

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    MicroRNA deregulation is frequent in human colorectal cancers (CRCs), but little is known as to whether it represents a bystander event or actually drives tumor progression in vivo. We show that miR-135b overexpression is triggered in mice and humans by APC loss, PTEN/PI3K pathway deregulation, and SRC overexpression and promotes tumor transformation and progression. We show that miR-135b upregulation is common in sporadic and inflammatory bowel disease-associated human CRCs and correlates with tumor stage and poor clinical outcome. Inhibition of miR-135b in CRC mouse models reduces tumor growth by controlling genes involved in proliferation, invasion, and apoptosis. We identify miR-135b as a key downsteam effector of oncogenic pathways and a potential target for CRC treatment

    The GALAH survey: observational overview and Gaia DR1 companion

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    The Galactic Archaeology with HERMES (GALAH) survey is amassive observational project to trace the MilkyWay's history of star formation, chemical enrichment, stellar migration and minor mergers. Using high-resolution (R ≃ 28 000) spectra, taken with the High Efficiency and Resolution Multi-Element Spectrograph (HERMES) instrument at the Anglo-Australian Telescope, GALAH will determine stellar parameters and abundances of up to 29 elements for up to one million stars. Selecting targets from a colour-unbiased catalogue built from 2MASS, APASS and UCAC4 data, we expect to observe dwarfs at 0.3-3 kpc and giants at 1-10 kpc. This enables a thorough local chemical inventory of the Galactic thin and thick discs, and also captures smaller samples of the bulge and halo. In this paper, we present the plan, process and progress as of early 2016 for GALAH survey observations. In our first two years of survey observing we have accumulated the largest high-quality spectroscopic data set at this resolution, over 200 000 stars. We also present the first public GALAH data catalogue: stellar parameters (Teff, log(g), [Fe/H], [α/Fe]), radial velocity, distance modulus and reddening for 10 680 observations of 9860 Tycho-2 stars, 7894 of which are included in the first Gaia data release.SLM and DBZ acknowledge support from Australian Research Council grants DE140100598 and FT110100743. JPM is supported by a UNSW Vice-Chancellor’s Research Fellowship. KL and SB acknowledge funds from the Alexander von Humboldt Foundation in the framework of the Sofja Kovalevskaja Award endowed by the Federal Ministry of Education and Research as well as funds from the Swedish Research Council (Grant no. 2015-00415_3) and Marie Sklodowska Curie Actions (Cofund Project INCA 600398). This work was partly supported by the European Union FP7 programme through ERG grant number 320360

    The GALAH survey: Co-orbiting stars and chemical tagging

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    We present a study using the second data release of the GALAH survey of stellar parameters and elemental abundances of 15 pairs of stars identified by Oh et al 2017. They identified these pairs as potentially co-moving pairs using proper motions and parallaxes from Gaia DR1. We find that 11 very wide (>1.7 pc) pairs of stars do in fact have similar Galactic orbits, while a further four claimed co-moving pairs are not truly co-orbiting. Eight of the 11 co-orbiting pairs have reliable stellar parameters and abundances, and we find that three of those are quite similar in their abundance patterns, while five have significant [Fe/H] differences. For the latter, this indicates that they could be co-orbiting because of the general dynamical coldness of the thin disc, or perhaps resonances induced by the Galaxy, rather than a shared formation site. Stars such as these, wide binaries, debris of past star formation episodes, and coincidental co-orbiters, are crucial for exploring the limits of chemical tagging in the Milky Way.Comment: 14 pages, 9 figures, submitted to MNRAS. Updated for Gaia DR2 value

    The GALAH survey: Co-orbiting stars and chemical tagging

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    We present a study using the second data release of the GALAH survey of stellar parameters and elemental abundances of 15 pairs of stars identified by Oh et al 2017. They identified these pairs as potentially co-moving pairs using proper motions and parallaxes from Gaia DR1. We find that 11 very wide (>1.7 pc) pairs of stars do in fact have similar Galactic orbits, while a further four claimed co-moving pairs are not truly co-orbiting. Eight of the 11 co-orbiting pairs have reliable stellar parameters and abundances, and we find that three of those are quite similar in their abundance patterns, while five have significant [Fe/H] differences. For the latter, this indicates that they could be co-orbiting because of the general dynamical coldness of the thin disc, or perhaps resonances induced by the Galaxy, rather than a shared formation site. Stars such as these, wide binaries, debris of past star formation episodes, and coincidental co-orbiters, are crucial for exploring the limits of chemical tagging in the Milky Way.Comment: 14 pages, 9 figures, submitted to MNRAS. Updated for Gaia DR2 value
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