236 research outputs found

    Influence of particle density on flow behavior and deposit architecture of concentrated pyroclastic density currents over a break in slope: Insights from laboratory experiments

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    Geological granular flows are highly complex, gravity-driven phenomena whose different behaviors depend on the mechanical properties, density and granulometric distributions of the constituent materials. Years of research have produced significant advances in understanding transport and deposition processes in granular flows. However, the role and effects of clast densities and density contrast in a granular flow are still not fully understood. In this paper we show the effect that pumice has on dry granular flows; specifically on flow velocity and longitudinal segregation of the deposits. Our work confirms, by experimental results, field observations on pumice/lithic segregation and longer pumice runout. We report results of velocity decay and deposit architecture for a granular flow passing over a break in slope (from 38° to 4° inclination). The 30 experimental runs were carried out in a five-meter long laboratory flume equipped with a series of sensors that include laser gates and high-speed cameras (400 fps). We used two polydisperse mixtures of dacitic lithics and rhyolitic pumice in varying amounts, with Weibull and Gaussian particle size distributions. The pumice/lithic ratio changes the flow response passing over a break in slope. This effect is particularly evident starting from 10% of pumice volume into the flow mixture, independently of its granulometric distribution. Runout relates to mass following a power law, with an exponent close 0.2. The experiments confirm that pumice segregation affects polydispersed mixtures, similarly to what has been observed in real field deposits, where density decoupling produces lithic-enriched proximal areas and pumice-enriched distal areas. The results obtained prove that the presence of low-density materials in a dense granular flow has a strong influence on its behavior

    High genetic connectivity in a gastropod with long-lived planktonic larvae

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    Genetic connectivity plays a crucial role in shaping the geographic structure of species. Our aim in this study was to explore the pattern of genetic connectivity in Bursa scrobilator, an iconic marine caenogastropod with long-lived pelagic larvae. Our study was based on the analysis of DNA sequence data for the 658-bp barcoding fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene. This is the largest DNA sequence dataset assembled to date for B. scrobilator. These data confirm that the two recently described subspecies B. scrobilator scrobilator (Linnaeus, 1758), from the Mediterranean and Macaronesia, and B. s. coriacea (Reeve, 1844), from West Africa, constitute two evolutionarily significant units (ESUs). We found that for the nominal subspecies, the variation in morphology (shell, radula and gross anatomy) and DNA sequences was not geographically structured, and this agrees with what we would expect in a species with high connectivity at the larval stage. The divergence between the two subspecies cannot be easily explained by isolation by distance, and we would argue that one or more extrinsic factors may have played a role in isolating the two ESUs and maintaining that isolation

    Discovery of a tyrosine-rich sporocyst wall protein in Eimeria tenella.

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    BACKGROUND: Eimeria is an important genus of apicomplexan parasites. A defining feature of these parasites is the oocyst, which is transmitted into the environment via the faeces of definitive hosts. The oocyst wall contains cross-linked, tyrosine-rich proteins and protects eight infectious sporozoites, housed in pairs within a second walled structure, the sporocyst. The biochemical basis for sporocyst wall formation is not known. FINDINGS: Here, we report the discovery of a novel tyrosine-rich protein, EtSWP1, in Eimeria tenella. Like the tyrosine-rich proteins of the oocyst wall, EtSWP1 is an intrinsically disordered protein with the tyrosine residues concentrated in a specific region of the protein, located immediately following the region of intrinsic disorder. We engineered E. tenella to express mCherry-tagged EtSWP1 and showed that the tagged protein localises specifically to sporocyst walls, indicating that the biochemistry of sporocyst wall assembly is analagous to that of oocyst walls. CONCLUSIONS: Tyrosine-rich proteins are known to be key components of the oocyst wall and we now demonstrate, using gene and protein analyses combined with genetic manipulation, that a novel tyrosine-rich protein is specific for the sporocyst wall. This finding is important because it shows that the biochemistry of these two distinct walls is similar and, hence, brings targeted disruption of sporulation and, therefore, potential neutralisation of oocysts in the environment, a step closer

    Concentração de carbono e nitrogênio na biomassa de capim Marandu e Mombaça sob alta dose de adubação nitronegada.

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    O carbono e o nitrogênio são importantes macro nutrientes que compõem estruturas e compostos orgânicos essenciais para plantas forrageiras, como os carboidratos, proteínas, ácidos nucleicos e clorofila. Estes compostos são determinados geneticamente, embora possam ser estimulados com ações de manejo. Portanto, objetivou-se avaliar a concentração carbono (C) e nitrogênio (N) na biomassa de Brachiaria brizantha cv. Marandu e Panicum maximum cv. Mombaça sob diferentes doses de nitrogênio. O experimento foi conduzido na Embrapa Agrossilvipastoril, em Sinop - MT, sobre um Latossolo amarelo distrófico. O delineamento foi em blocos completos casualizados, em arranjo fatorial 2 x 2 (duas cultivares: Mombaça e Marandu; e duas adubações: 0 e 550 kg N.ha-1.ano) com três repetições, totalizando 12 unidades experimentais de 32 m2. O período experimental foi de 22 de setembro de 2015 a 20 de março de 2016, compreendendo as estações de primavera e verão. O sistema de colheita simulou a lotação intermitente com períodos fixos de 28 dias. A altura do resíduo foi mantida a 15 cm para o Marandu e 40 cm para o Mombaça. Cortou-se a forragem a altura do solo presente em dois retângulos de 0,5 m², as quais foram secas e moídas (1 mm) para análise elementar de carbono e nitrogênio por meio do Vario Macro Cube CHNS. Os dados foram analisados utilizando o método de modelos mistos com estrutura paramétrica especial na matriz de covariância, utilizando o pacote estatístico do SAS®. A comparação de médias foi realizada pela probabilidade da diferença (pdiff) ao nível de 5% de significância. A concentração de C no Marandu (P=0,001; 42,1±0,1%) foi 1,7% maior que o Mombaça (41,4±0,1). No entanto, a concentração de C foi semelhante com e sem adubação (41,7±0,1) e entre as estações (41,7±0,1). A concentração de N foi maior (P=0,041) no Marandu colhido na primavera (1,8±0,1) do que no verão (1,6±0,1). De mesmo modo, o Mombaça na primavera (1,5±0,1) concentrou mais N do que no verão (1,1±0,1). No geral, o Marandu apresentou maiores teores de N. A adubação nitrogenada promoveu um aumento na concentração de N na biomassa (P=0,002), sobretudo na primavera (2,3±0,1). Este valor foi 56% maior do que sem adubação na mesma estação, 61% maior do que sem adubação no verão e 22% maior que no verão (1,8±0,1) com adubação. Conclui-se que a concentração de C e N na biomassa é bastante influenciado pelo cultivar e a adubação nitrogenada aumenta os teores de N na biomassa de plantas forrageiras.Resumos da XXV Reunião da Associação Latino-Americana de Produção Animal, Recife, nov. 2016. Títulos equivalentes Archivos Latinoamericanos de Producción Animal

    Pharmacogenetic prediction of clinical outcome in advanced colorectal cancer patients receiving oxaliplatin/5-fluorouracil as first-line chemotherapy

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    To determine whether molecular parameters could be partly responsible for resistance or sensitivity to oxaliplatin (OX)-based chemotherapy used as first-line treatment in advanced colorectal cancer (CRC). We studied the usefulness of the excision repair cross-complementing 1 (ERCC1), xeroderma pigmentosum group D (XPD), XRCC1 and GSTP1 polymorphisms as predictors of clinical outcome in these patients. We treated 126 CRC patients with a first-line OX/5-fluorouracil chemotherapeutic regimen. Genetic polymorphisms were determined by real-time PCR on an ABI PRISM 7000, using DNA from peripheral blood. Clinical response (CR), progression-free survival (PFS) and overall survival (OS) were evaluated according to each genotype. In the univariate analysis for CR, ERCC1-118 and XPD 751 polymorphisms were significant (P=0.02 and P=0.05, respectively). After adjustment for the most relevant clinical variables, only ERCC1-118 retained significance (P=0.008). In the univariate analysis for PFS, ERCC1-118 and XPD 751 were significant (P=0.003 and P=0.009, respectively). In the multivariant analysis, only the XPD 751 was significant for PFS (P=0.02). Finally, ERCC1-118 and XPD 751 polymorphisms were significant in the univariate analysis for OS (P=0.006 and P=0.015, respectively). Both genetic variables remained significant in the multivariate Cox survival analysis (P=0.022 and P=0.03). Our data support the hypothesis that enhanced DNA repair diminishes the benefit of platinum-based treatments

    <i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

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    Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data

    Comprehensive analysis of chemical and biological problems associated with browning agents used in aquatic studies

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    Inland waters receive and process large amounts of colored organic matter from the terrestrial surroundings. These inputs dramatically affect the chemical, physical, and biological properties of water bodies, as well as their roles as global carbon sinks and sources. However, manipulative studies, especially at ecosystem scale, require large amounts of dissolved organic matter with optical and chemical properties resembling indigenous organic matter. Here, we compared the impacts of two leonardite products (HuminFeed and SuperHume) and a freshly derived reverse osmosis concentrate of organic matter in a set of comprehensive mesocosm- and laboratory-scale experiments and analyses. The chemical properties of the reverse osmosis concentrate and the leonardite products were very different, with leonardite products being low and the reverse osmosis concentrate being high in carboxylic functional groups. Light had a strong impact on the properties of leonardite products, including loss of color and increased particle formation. HuminFeed presented a substantial impact on microbial communities under light conditions, where bacterial production was stimulated and community composition modified, while in dark potential inhibition of bacterial processes was detected. While none of the browning agents inhibited the growth of the tested phytoplankton Gonyostomum semen, HuminFeed had detrimental effects on zooplankton abundance and Daphnia reproduction. We conclude that the effects of browning agents extracted from leonardite, particularly HuminFeed, are in sharp contrast to those originating from terrestrially derived dissolved organic matter. Hence, they should be used with great caution in experimental studies on the consequences of terrestrial carbon for aquatic systems

    Complicaciones de la colocación de malla sintética vaginal para la incontinencia urinaria de esfuerzo

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    ResumenAntecedentesLas mallas para la incontinencia urinaria (IU) se han utilizado a pesar de la falta de evidencia de nivel i en la literatura para evaluar su seguridad y eficacia a largo plazo. Las complicaciones relacionadas con la malla provocaron una advertencia emitida por la FDA en 2008 y dejaron de ser consideradas eventos raros. Las complicaciones más comunes son la retención aguda de orina, sangrado, recurrencia o persistencia de la IU, erosión de uretra e infección de la malla.ObjetivoConocer cuáles son las complicaciones derivadas del tratamiento quirúrgico de la IU femenina con la colocación de mallas suburetrales.Material y métodoSe analizaron los pacientes con diagnóstico de IU operadas con cirugía antiincontinencia y colocación de malla vaginal del año 2007 al 2014. Se analizó las complicaciones derivadas de la colocación de malla y la recuperación de continencia.ResultadosA 58 pacientes se les colocó sling (cabestrillo) con malla sintética; edad promedio de 56 años. El 51% de las pacientes tenían IU de esfuerzo y el 49% IU mixta. Las complicaciones tempranas fueron: 4 pacientes con retención aguda de orina. Las complicaciones tardías: dolor uretral o vaginal (12.2%), dispareunia (20%) y extrusión de malla (10%) manejado con retiro de la misma, 2 de ellas requiriendo 2 procedimientos quirúrgicos. El 12% presentaron urgencia de novo, el 90.2% evolucionaron sin incontinencia, el 9.7% con IU postoperatoria y 2 pacientes sin mejoría.DiscusiónNuestra serie, aunque pequeña, muestra una baja tasa de complicaciones a largo plazo relacionadas con la malla en comparación con la mayoría de las series que muestran una tasa de reoperación de hasta>70% y con múltiples casos de retiro de malla, por lo que en nuestra experiencia los slings suburetrales continúan siendo una opción adecuada en el manejo de la IU.ConclusionesLos slings suburetrales son una opción segura y efectiva en el manejo de la IU.AbstractBackgroundSurgical mesh has been used for treating urinary incontinence (UI) despite the lack of level i evidence in the literature evaluating its long-term safety and efficacy. Mesh-related complications were responsible for a warning issued by the FDA in 2008 and they stopped being considered rare events. The most common complications are acute urinary retention, bleeding, recurrence or persistence of UI, erosion of the urethra, and mesh infection.AimsTo determine the complications derived from surgical UI treatment with the placement of suburethral mesh in women.Material and methodPatients diagnosed with UI that underwent anti-incontinence surgery with the placement of vaginal mesh within the time frame of 2007 and 2014 were analyzed. Mesh placement complications and the recovery of continence were evaluated.ResultsA synthetic mesh sling was placed in 58 patients with a mean age of 56 years. A total of 51% of the patients had stress urinary incontinence and 49% had mixed urinary incontinence. Early complications were: 4 patients with acute urine retention. Late complications were: urethral or vaginal pain (12.2%), dyspareunia (20%), and mesh extrusion (10%) that was managed through mesh removal; 2 of those patients required surgical procedures. Twelve percent of the patients presented with de novo urgency, 90.2% progressed with no incontinence, 9.7% presented with postoperative UI, and 2 patients had no improvement.DiscussionAlthough small, our case series showed a low long-term complication rate with the use of surgical mesh, compared with the majority of case series that demonstrate a re-operation rate>70%, as well as numerous cases of mesh removal. Thus, it is our experience that suburethral slings continue to be an adequate UI management option.ConclusionsSuburethral slings are a safe and effective option in UI management
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