1,293 research outputs found

    Linkages between the southern Patagonia Pre-Permian basements : new insights from detrital zircons U-Pb SHRIMP ages from the Cerro Negro District

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    The Patagonian basement rocks are dominated by Precambrian to Early Paleozoic metamorphic rocks intruded by Paleozoic granitoids. Recently discovered basement rocks in the Cerro Negro District are characterized mainly by quartz-muscovite-chlorite schists; the metamorphic grade reaches greenschist facies (biotite-garnet grade) with a regional S1 schistosity subparallel to the original sedimentary structure S0 and a secondary non-penetrative S2 foliation. New detrital zircon U-Pb geochronology shows that maximum depositional ages for detrital zircons are Devonian, ages of 379 ± 4Ma. These results suggest that the Cerro Negro basement rocks are the youngest basement in the Deseado Massif, overlapping some detrital zircon ages in the eastern Andean Metamorphic Complex in the Andean region. Most of detrital zircons are igneous in origin with a major peak around ~396Ma, provably sourced from the Devonian granitoids of the Río Deseado Complex (El Laurel and Bahía Laura granites) and equivalent northern Patagonia granitoids (e.g. Colan Conhué and Lago Lolog granites). Secondary peaks correspond to Ordovician to Silurian ages, being the Río Deseado Complex and La Modesta Formation (and their igneous contributors) the possible sources of the zircons. The minor oldest peaks yield Cambrian-Neoproterozoic; Mesoproterozoic and Paleoproterozoic-Archean ages, evidencing a common source from the interior of Gondwana. The results provide new insights about the relationships between the pre-Permian metasedimentary rocks of the extra-Andean and Andean region during Mid-Paleozoic ages

    Burdigalian deposits of the Santa Cruz Formation in the Sierra Baguales, Austral (Magallanes) Basin: Age, depositional environment and vertebrate fossils

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    Indexación: Web of Science; Scielo.ABSTRACT. A succession of marine and continental strata on the southern flank of Cerro Cono in the Sierra Baguales, northeast of Torres del Paine, can be correlated with stratigraphic units exposed along the southern border of the Lago Argentino region in Santa Cruz Province, Argentina. These include the Estancia 25 de Mayo Formation and the basal part of the Santa Cruz Formation. The lithological correlation is also confirmed by detrital zircon ages (maximum age of 18.23±0.26 Ma) and a rich assemblage of terrestrial vertebrate fossils, biostratigraphically equivalent to a postColhuehuapian, pre-Santacrucian South American Land Mammal Age (SALMA) fauna, suggesting a range of 19 to 17.8 Ma. Similar ages have been obtained from the basal part of the Santa Cruz Formation at Estancia Quién Sabe in southwestern Argentina, supporting the assumption of a regional continuity between these deposits. A measured lithostratigraphic column is presented and the depositional environment is interpreted as a coastal plain with small, meandering rivers and ephemeral floodplain lakes. The sedimentation coincides with intensified uplift of the Patagonian Andes during the ‘Quechua Phase’ of Andean tectonism, which is reflected by a change in paleocurrent directions from northwest to east-northeast. Keywords: Burdigalian, Santa Cruz Formation, Santacrucian SALMA, ‘Notohippidian’ fauna, Meandering rivers.RESUMEN. Una sucesión de estratos marinos y continentales en el flanco meridional del cerro Cono, en la sierra Baguales, al noreste de Torres del Paine, se correlaciona con estratos al sur de la región de lago Argentino en la Provincia de Santa Cruz, República Argentina. Estas unidades incluyen la Formación Estancia 25 de Mayo y la parte basal de la Formación Santa Cruz. La correlación litológica es, además, confirmada por datación de circones detríticos (edad máxima de 18,23±0,26 Ma) y un variado ensamble de vertebrados fósiles terrestres de edad post-Colhuehuapense a pre-Santacrucense en la escala de Edades Mamífero Sudamericanas (EMAS), con un rango temporal de entre 19 a 17,8 Ma. Edades similares han sido reportadas para la parte basal de la Formación Santa Cruz, en estancia Quién Sabe, en el suroeste de Argentina, ratificando la continuidad regional entre estos depósitos. Se presenta una columna estratigráfica y se interpreta el ambiente de depositación como una llanura costera con pequeños ríos sinuosos y lagos efímeros. La edad de sedimentación coincide con el solevantamiento de los Andes Patagónicos durante la 'Fase Quechua', lo que se ve reflejado por un cambio en la dirección de las paleocorrientes desde el noroeste hacia el este-noreste.http://ref.scielo.org/csxwd

    Patterns and factors influencing oral anticoagulant prescription in people with atrial fibrillation and dementia: Results from UK primary care

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    Aims: Oral anticoagulant (OAC) is recommended for preventing stroke in atrial fibrillation (AF). However, the OAC utilisation in AF patients with dementia or cognitive impairment (CI) is limited. This study aimed to examine the prevalence of OAC prescriptions in AF patients with dementia/CI and to identify factors associated with OAC treatment within 180 days after dementia/CI diagnosis. / Methods: Using The Health Improvement Network database, the annual trends of OAC between 2000 and 2015 were calculated. Multivariable logistic regression was performed to identify factors associated with OAC treatment. / Results: The prevalence rate of OAC prescriptions increased from 6.1% in 2000 to 45.9% in 2015. Among OAC users, the proportion of direct oral anticoagulants (DOACs) use increased significantly from 0.1% in 2011 to 33.8% in 2015 (P‐trend < 0.001), while the proportion of vitamin K antagonist use decreased by 28.6% from 100% in 2000 to 71.4% in 2015 (P‐trend < 0.001). In the multivariable analysis, younger age, very old age, female sex, higher Charlson Comorbidity Index, having a HAS‐BLED score ≥3, a history of intracranial bleeding, falls and polypharmacy were significantly associated with lower odds of receiving OAC. / Conclusions: In UK primary care, OAC use increased from 2000 to 2015 in AF patients with dementia/CI, with a substantial increase in use of DOACs. Characteristics related to frailty are associated with lower odds of OAC prescription. Given the increasing use of DOACs in patients with dementia/CI, further studies are needed to investigate the safety and effectiveness of DOACs in this important patient group

    Enterobacter Sakazakii: an Emerging Microbe With Implications for Infant Health

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    Enterobacter sakazakii (E. sakazakii) is an opportunistic pathogen and the aetiological agent in rare but life-threatening cases of meningitis, necrotizing enterocolitis, and sepsis in infants. Among infants, those at greatest risk are neonates (\u3c28 \u3edays), particularly those born prematurely or of low birth weight (g). Consumption of contaminated powdered infant formula (PIF) has been epidemiologically linked with cases of infection. Contamination can occur during the manufacturing process or during postmanufacture reconstitution of formula. Development of rapid, sensitive and specific detection methods will facilitate manufacturers efforts to reduce the occurrence of E. sakazakii in the final powdered product. Furthermore, since PIF is not a sterile product, proper precautions should be taken during handling and reconstitution of formula prior to feeding in order to prevent contamination and proliferation of the bacterium

    Oral anticoagulant and reduced risk of dementia in patients with atrial fibrillation: A population-based cohort study

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    Background: Whether oral anticoagulation (OAC) can prevent dementia or cognitive impairment (CI) in patients with atrial fibrillation (AF) remains unclear. Objective: The purpose of this study was to investigate the risk of dementia/CI among AF patients with and without OAC treatment. Methods: We conducted a retrospective cohort study using United Kingdom (UK) primary care data (2000–2017). Participants with newly diagnosed AF without a history of dementia/CI were identified. Inverse probability of treatment weights based on propensity scores and Cox regression were used to compare the dementia outcomes. Results: Among 84,521 patients with AF, 35,245 were receiving OAC treatment and 49,276 received no OAC treatment; of these patients, 29,282 were receiving antiplatelets. Over a mean follow-up of 5.9 years, 5295 patients developed dementia/CI. OAC treatment was associated with a lower risk of dementia/CI compared to no OAC treatment (hazard ratio [HR] 0.90; 95% confidence interval 0.85–0.95; P <.001) or antiplatelets (HR 0.84; 95% confidence interval 0.79–0.90; P <.001). No significant difference in dementia risk was observed for direct oral anticoagulants (DOACs) vs warfarin (HR 0.89; 95% confidence interval 0.70–1.14; P = .373), whereas dual therapy (OAC plus an antiplatelet agent) was associated with a higher risk of dementia/CI compared with no treatment (HR 1.17; 95% confidence interval 1.05–1.31; P = .006). Conclusion: OAC use was associated with a lower risk of dementia/CI compared to non-OAC and antiplatelet treatment among AF patients. The evidence for DOAC on cognitive function is insufficient, and further studies including randomized clinical trials are warranted

    Provenance Response to Rifting and Separation at the Jan Mayen Microcontinent Margin

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    Funding This research received no external funding. Acknowledgments We are grateful to John Still (University of Aberdeen) and Iain Macdonald (Cardiff University) for their assistance with acquisition of mineral chemical data, and to Mick Pointon (CASP) for running the “R” code to assign apatite provenance. This research was carried out as part of CASP’s Greenland-Norway Project. Our sponsors’ financial support is gratefully acknowledged. We are grateful for the reviewers comments, which significantly improved the manuscript.Peer reviewedPublisher PD

    The Arequipa Massif of Peru: new SHRIMP and isotope constraints on a Paleoproterozoic inlier in the Grenvillian orogen

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    The enigmatic Arequipa Massif of southwestern Peru is an outcrop of Andean basement that underwent Grenville-age metamorphism, and as such it is important for the better constraint of Laurentia–Amazonia ties in Rodinia reconstruction models. U–Pb SHRIMP zircon dating has yielded new evidence on the evolution of the Massif between Middle Paleoproterozoic and Early Paleozoic. The oldest rock-forming events occurred in major orogenic events between ca. 1.79 and 2.1 Ga (Orosirian to Rhyacian), involving early magmatism (1.89–2.1 Ga, presumably emplaced through partly Archaean continental crust), sedimentation of a thick sequence of terrigenous sediments, UHT metamorphism at ca. 1.87 Ga, and late felsic magmatism at ca. 1.79 Ga. The Atico sedimentary basin developed in the Late-Mesoproterozoic and detrital zircons were fed from a source area similar to the high-grade Paleoproterozoic basement, but also from an unknown source that provided Mesoproterozoic zircons of 1200–1600 Ma. The Grenville-age metamorphism was of low-P type; it both reworked the Paleoproterozoic rocks and also affected the Atico sedimentary rocks. Metamorphism was diachronous: ca. 1040 Ma in the Quilca and Camana areas and in the San Juan Marcona domain, 940 ± 6 Ma in the Mollendo area, and between 1000 and 850 Ma in the Atico domain. These metamorphic domains are probably tectonically juxtaposed. Comparison with coeval Grenvillian processes in Laurentia and in southern Amazonia raises the possibility that Grenvillian metamorphism in the Arequipa Massif resulted from extension and not from collision. The Arequipa Massif experienced Ordovician–Silurian magmatism at ca. 465 Ma, including anorthosites formerly considered to be Grenvillian, and high-T metamorphism deep within the magmatic arc. Focused retrogression along shear zones or unconformities took place between 430 and 440 Ma.Centro de Investigaciones Geológica

    Inhibition of Simian Virus 40 replication by targeting the molecular chaperone function and ATPase activity of T antigen

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    Polyomaviruses such as BK virus and JC virus have been linked to several diseases, but treatments that thwart their propagation are limited in part because of slow growth and cumbersome culturing conditions. In contrast, the replication of one member of this family, Simian Virus 40 (SV40), is robust and has been well-characterized. SV40 replication requires two domains within the viral-encoded large tumor antigen (TAg): The ATPase domain and the N-terminal J domain, which stimulates the ATPase activity of the Hsp70 chaperone. To assess whether inhibitors of polyomavirus replication could be identified, we examined a recently described library of small molecules, some of which inhibit chaperone function. One compound, MAL2-11B, inhibited both TAg's endogenous ATPase activity and the TAg-mediated activation of Hsp70. MAL2-11B also reduced SV40 propagation in plaque assays and compromised DNA replication in cell culture and in vitro. Furthermore, the compound significantly reduced the growth of BK virus in a human kidney cell line. These data indicate that pharmacological inhibition of TAg's chaperone and ATPase activities may provide a route to combat polyomavirus-mediated disease. © 2009 Elsevier B.V. All rights reserved

    Was Sinn Féin dying? A quantitative post-mortem of the party's decline and the emergence of Fianna Fáil

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    This article calls for a reappraisal of the consensus surrounding the split within Sinn Féin in 1926 that led to the foundation of Fianna Fáil. It demonstrates that quantitative factors cited to demonstrate Sinn Féin’s “terminal” decline – finances, cumann numbers, and election results – and to explain de Valera’s decision to leave Sinn Féin and establish a rival republican organisation, Fianna Fáil, do not provide sufficient objective grounds to explain the republican leader’s actions. This article demonstrates that Sinn Féin’s election results during the period in question (1923-1926) were encouraging and the decline in finances and cumann numbers can be explained by the fact that the base year used to compare progress was 1923, an election year. Moreover, this article compares the performance of Sinn Féin to the first five years of Fianna Fáil (1926-1931) to show that what has been interpreted as terminal decline can also be attributed to normal inter-election lulls in party activity. Correspondingly, subjective factors – e.g. personal rivalries, differences in ideology, organisational style and levels of patience in terms of achieving political power – were most likely the determining factors rather than organisational decline
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