246 research outputs found

    Evolution of the Great Tehuelche Paleolake in the Torres del Paine National Park of Chilean Patagonia during the Last Glacial Maximum and Holocene

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    Indexación: Web of Science; ScieloRESUMEN. Una serie de morrenas glaciares se distribuyen desde el margen oriental de la cuenca de drenaje Torres del Paine a cerca del actual margen de los Campos de Hielo Patagónico, junto con una serie de terrazas lacustres regional continuos relacionados con las fluctuaciones glaciales. La geomorfología, apoyada por la evidencia de sedimentos del lago, indica la existencia de un único paleolago proglacial en esta zona, aquí denominado el Gran Tehuelche paleolago. Este concepto ayuda a aclarar la cronología de eventos glaciales y conduce a una mejor comprensión de la evolución del sistema hidrológico de la zona de Torres del Paine. Avances glaciales referidos anteriormente como ocurrieron A, B y C durante el Último Máximo Glacial y alimentados con la Gran Tehuelche paleolago con agua de deshielo, que le permite alcanzar su máxima extensión. El descubrimiento de trombolitos en Laguna Amarga sugiere que el drenaje de la paleolago hacia el fiordo de Última Esperanza tuvo lugar en 7113 Cal. años AP, después de la fusión de una barrera de hielo que existía durante el avance glacial antes. Esto dio lugar al desarrollo de un sistema hidrológico fluvio-lacustre complejo que persiste hasta nuestros días. Palabras clave: Patagonia, último máximo glacial, Younger Dryas, trombolitos. RESUMEN. Un grupo de morrenas glaciales estan Distribuidas desde el margen Este de la cuenca de drenaje de Torres del Paine Hacia el margen real de los Campos de Hielo Patagónicos. Las morrenas se observan en conjunto con las Naciones Unidas Grupo de terrazas Lacustres Regionales, las Cuales estan vinculadas y una las fluctuaciones glaciales. La geomorfología y Evidencias de sedimentos Lacustres indicano la existence De unico ONU lago proglacial, referido En Este Estudio de Como Gran Paleolago Tehuelche. Este Concepto ayuda a clarificar la cronología de los eventos glaciales y permite Una mejor Comprensión de la Evolución del Sistema hidrológico del sector de Torres del Paine. Los eventos glaciales, previamente Referidos Como Avance A, B y C, ocurrieron Durante el Último Máximo Glacial y alimentaron con Aguas de fusión al Gran Paleolago Tehuelche, permitiéndole Alcanzar su alcalde extensión. El Descubrimiento de trombolitos en Laguna Amarga sugiere Que El desagüe del paleolago Ocurrió Hace 7.113 Cal. Por años AP el Seno de Última Esperanza, producto de la fusión De Una barrera glaciar existente Durante los Avances glaciales Anteriores. LUEGO del drenaje sí Desarrollo en Un complejo Sistema hidrológico Que Persiste Hasta el presente. Palabras clave: Patagonia, Último Máximo Glacial, Dryas Temprano, Trombolitos.http://ref.scielo.org/wgc2q

    Improved efficiency of organic solar cells using Au NPs incorporated into PEDOT:PSS buffer layer

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    Au based plasmonic phenomenon inside the hole transport layer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) of an organic solar cell based on blend of poly(3-hexylthiophene) (P3HT) and [6:6]-phenyl-C61-butyric acid (PCBM) is investigated. The concentration of the Au nanoparticles synthesized by wet chemical reduction is one of the key factors to strong light trapping when the spherical gold nanoparticles are blended into the PEDOT:PSS solution. Studies of the influence of the concentration of nanoparticles distribution in the PEDOT:PSS were carried out using UV–Vis spectroscopy and atomic force microscopy. Electrical characteristics of the pristine device and of device with metallic nanostructures were analyzed from J –V characteristics to observe the plasmonic effects on the performance in the P3HT:PCBM organic solar cells. The origin of the photocurrent enhancements with varying Au nanoparticles concentrations on PEDOT:PSS are discussed.The University of theWitwatersrand, Material Physics Research Institute, School of Physics & Chemistry; and MMU facilities at Wits, NRF and Material Energy Research Group (MERG).http://scitation.aip.orgcontent/aip/journal/advaam2017Physic

    Transitory Microbial Habitat in the Hyperarid Atacama Desert

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    Traces of life are nearly ubiquitous on Earth. However, a central unresolved question is whether these traces always indicate an active microbial community or whether, in extreme environments, such as hyperarid deserts, they instead reflect just dormant or dead cells. Although microbial biomass and diversity decrease with increasing aridity in the Atacama Desert, we provide multiple lines of evidence for the presence of an at times metabolically active, microbial community in one of the driest places on Earth. We base this observation on four major lines of evidence: a physico-chemical characterization of the soil habitability after an exceptional rain event, identified biomolecules indicative of potentially active cells [e.g., presence of ATP, phospholipid fatty acids (PLFAs), metabolites, and enzymatic activity], measurements of in situ replication rates of genomes of uncultivated bacteria reconstructed from selected samples, and microbial community patterns specific to soil parameters and depths. We infer that the microbial populations have undergone selection and adaptation in response to their specific soil microenvironment and in particular to the degree of aridity. Collectively, our results highlight that even the hyperarid Atacama Desert can provide a habitable environment for microorganisms that allows them to become metabolically active following an episodic increase in moisture and that once it decreases, so does the activity of the microbiota. These results have implications for the prospect of life on other planets such as Mars, which has transitioned from an earlier wetter environment to today's extreme hyperaridity. [Abstract copyright: Copyright © 2018 the Author(s). Published by PNAS.

    Effects and safety of rituximab in systemic sclerosis: An analysis from the European Scleroderma Trial and Research (EUSTAR) group

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    Objectives: To assess the effects of Rituximab (RTX) on skin and lung fibrosis in patients with systemic sclerosis (SSc) belonging to the European Scleroderma Trial and Research (EUSTAR) cohort and using a nested case-control design. Methods: Inclusion criteria were fulfilment of American College of Rheumatology classification criteria for SSc, treatment with RTX and availability of follow-up data. RTX-treated patients were matched with control patients from the EUSTAR database not treated with RTX. Matching parameters for skin/lung fibrosis were the modified Rodnan Skin Score (mRSS), forced vital capacity (FVC), follow-up duration, scleroderma subtype, disease duration and immunosuppressive co-treatment. The primary analysis was mRSS change from baseline to follow-up in the RTX group compared with the control group. Secondary analyses included change of FVC and safety measures. Results: 63 patients treated with RTX were included in the analysis. The case-control analysis in patients with severe diffuse SSc showed that mRSS changes were larger in the RTX group versus matched controls (N=25; -24.0±5.2% vs-7.7±4.3%; p=0.03). Moreover, in RTX-treated patients, the mean mRSS was significantly reduced at follow-up compared with baseline (26.6±1.4 vs 20.3±1.8; p=0.0001). In addition, in patients with interstitial lung disease, RTX prevented significantly the further decline of FVC compared with matched controls (N=9; 0.4±4.4% vs-7.7±3.6%; p=0.02). Safety measures showed a good profile consistent with previous studies in autoimmune rheumatic diseases. Conclusions: The comparison of RTX treated versus untreated matched-control SSc patients from the EUSTAR cohort demonstrated improvement of skin fibrosis and prevention of worsening lung fibrosis, supporting the therapeutic concept of B cell inhibition in SSc

    Acquired homotypic and heterotypic immunity against oculogenital Chlamydia trachomatis serovars following female genital tract infection in mice

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    BACKGROUND: Chlamydia trachomatis is the most common sexually transmitted bacterial pathogen causing female genital tract infection throughout the world. Reinfection with the same serovar, as well as multiple infections with different serovars, occurs in humans. Using a murine model of female C. trachomatis genital tract infection, we determined if homotypic and/or heterotypic protection against reinfection was induced following infection with human oculogenital strains of C. trachomatis belonging to two serovars (D and H) that have been shown to vary significantly in the course of infection in the murine model. METHODS: Groups of outbred CF-1 mice were reinfected intravaginally with a strain of either serovar D or H, two months after initial infection with these strains. Cellular immune and serologic status, both quantitative and qualitative, was assessed following initial infection, and the course of infection was monitored by culturing vaginal samples collected every 2–7 days following reinfection. RESULTS: Serovar D was both more virulent (longer duration of infection) and immunogenic (higher level of circulating and vaginal IgG and higher incidence of IgA in vaginal secretions) in the mouse genital tract. Although both serovars induced cross-reacting antibodies during the course of primary infection, prior infection with serovar H resulted in only a slight reduction in the median duration of infection against homotypic reinfection (p ~ 0.10), while prior infection with serovar D resulted in significant reduction in the median duration of infection against both homotypic (p < 0.01) and heterotypic reinfection (p < 0.01) when compared to primary infection in age and conditions matched controls. CONCLUSION: Serovar D infection resulted in significant homotypic and heterotypic protection against reinfection, while primary infection with serovar H resulted in only slight homotypic protection. In addition to being the first demonstration of acquired heterotypic immunity between human oculogenital serovars, the differences in the level and extent of this immunity could in part explain the stable difference in serovar prevalence among human isolates

    Systemic sclerosis: state of the art on clinical practice guidelines

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    Systemic sclerosis (SSc) is an orphan disease characterised by autoimmunity, fibrosis of the skin and internal organs, and vasculopathy. SSc may be associated with high morbidity and mortality. In this narrative review we summarise the results of a systematic literature research, which was performed as part of the European Reference Network on Rare and Complex Connective Tissue and Musculoskeletal Diseases project, aimed at evaluating existing clinical practice guidelines or recommendations. Only in the domains 'Vascular &amp; Ulcers' (ie, non-pharmacological approach to digital ulcer), 'PAH' (ie, screening and treatment), 'Treatment' and 'Juveniles' (ie, evaluation of juveniles with Raynaud's phenomenon) evidence-based and consensus-based guidelines could be included. Hence there is a preponderance of unmet needs in SSc referring to the diagnosis and (non-)pharmacological treatment of several SSc-specific complications. Patients with SSc experience significant uncertainty concerning SSc-related taxonomy, management (both pharmacological and nonpharmacological) and education. Day-to-day impact of the disease (loss of self-esteem, fatigue, sexual dysfunction, and occupational, nutritional and relational problems) is underestimated and needs evaluation
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