667 research outputs found

    Mixed-layer characteristics as related to the monsoon climate of New Delhi, India

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    Annual variations of mixed-layer characteristics at New Delhi, India have been studied for a weak monsoon (1987) and a strong monsoon (1988) year. In the weak monsoon year (1987), the maximum mixing depthh max was found to have a value of around 3000 m during the pre-monsoon, less than 2000 m during the summer monsoon, around 2000 m during the post-monsoon, and less than 1000 m in the winter season. For the strong monsoon year (1988),h max values were less than 1987 values for comparable periods throughout the year. The seasonal and yearly differences ofh max were explained by the surface energy balance and potential temperature gradient γ at a time close to sunrise. According to the spatial patterns of γ obtained by an objective analysis of the 850 to 700 hPa layers. mixed-layer characteristics obtained at New Delhi are representative of the north and central regions of India

    A Roman bronze and silver handle from the villa of Huerta del Río (Tarancueña, Soria): Archaeological context and interpretation

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    Se presenta y analiza una pieza romana excepcional de bronce y plata hallada en los niveles superficiales de la villa tardorromana de Tarancueña (Soria) durante la excavación arqueológica de 1979. Esta excavación constituye hasta ahora la única referencia científica sobre dicha villa, dado que las excavaciones posteriores, mucho más amplias, no se han publicado y su documentación está perdida. Tanto los datos de 1979 como lo poco que se conoce de los posteriores apuntan a una ocupación relativamente corta de la villa, a caballo entre los siglos IV y V. Los edificios parecen haber sido abandonados de forma súbita y haberse luego derrumbado paulatinamente, sin ninguna huella de destrucción intencionada. El asa de bronce consta de una escultura superior de un grifo, unas abrazaderas laterales del vaso (que no fue hallado) con volutas y cabezas de ánade, y un asa de agarre inferior que termina en una cabeza de hombre barbudo, posiblemente Sileno. El bronce fue decorado con incrustaciones lineales de plata en varias de sus partes. Todo ello hace referencia a los rituales sociales de consumo del vino, cuyos protectores eran los grifos y el dios Baco. El asa se encontró en superficie, por encima de uno de los muros de la posible pars urbana de la villa, luego no tenía ninguna relación estratigráfica con ésta. Además, del análisis estilístico se deduce su segura cronología alto-imperial, por lo que la pieza fue probablemente conservada durante varios siglos como una posesión valiosa. Al no haber sido hallada en niveles de ocupación, su presencia en el yacimiento queda sin explicar del todo (¿tal vez parte de un escondrijo de piezas valiosas esparcidas por el arado?) y originalmente podría haber procedido de la importante y cercana ciudad de Tiermes o quizás de un posible asentamiento romano situado en el mismo pueblo de Tarancueña, todavía sin investigar.An exceptional Roman bronze and silver piece found in the surface levels of the late Roman villa of Tarancueña (Soria) in the archaeological excavation of 1979 is presented and analysed. This excavation is so far the only scientific reference on this villa, since the later excavations, which were much more extensive, have not been published and their documentation is lost. Both the 1979 data and the little that is known of the following diggings point to a relatively short occupation of the villa, between the 4th and 5th centuries. The buildings seem to have been abandoned suddenly and then gradually collapsed, without any trace of intentional destruction. The bronze handle consists of an upper sculpture of a griffin, side clamps of the vessel (which was not found) with scrolls and duck heads, and a lower grip handle ending in the head of a bearded man, possibly Silenus. The bronze was decorated with linear silver inlays in several parts. All of this refers to the social rituals of wine consumption, whose protectors were the griffins and the god Bacchus. The handle was found on the surface, above one of the walls of what may have been the pars urbana of the villa, therefore it had no stratigraphic relationship with it. Furthermore, stylistic analysis suggests that it is certainly of early imperial chronology, so that the piece was probably preserved for several centuries as a valuable possession. Since it was not found in the occupation levels, its presence at the site is not fully explained (perhaps part of a cache of valuable artefacts that was scattered by the plough?), and originally it could have come from the important nearby city of Tiermes or perhaps from a possible Roman settlement located in the neighbouring village of Tarancueña itself, still uninvestigated

    Methane in the Baltic and North Seas and a reassessment of the marine emissions of methane

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    During three measurement campaigns on the Baltic and North Seas, atmospheric and dissolved methane was determined with an automated gas chromatographic system. Area-weighted mean saturation values in the sea surface waters were 113 ± 5% and 395 ± 82% (Baltic Sea, February and July 1992) and 126 ± 8% (south central North Sea, September 1992). On the bases of our data and a compilation of literature data the global oceanic emissions of methane were reassessed by introducing a concept of regional gas transfer coefficients. Our estimates computed with two different air-sea exchange models lie in the range of 11-18 Tg CH4 yr-1. Despite the fact that shelf areas and estuaries only represent a small part of the world's ocean they contribute about 75% to the global oceanic emissions. We applied a simple, coupled, three-layer model to numerically simulate the time dependent variation of the oceanic flux to the atmosphere. The model calculations indicate that even with increasing tropospheric methane concentration, the ocean will remain a source of atmospheric methane

    Electronic structure and magnetic properties of the graphene/Fe/Ni(111) intercalation-like system

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    The electronic structure and magnetic properties of the graphene/Fe/Ni(111) system were investigated via combination of the density functional theory calculations and electron-spectroscopy methods. This system was prepared via intercalation of thin Fe layer (1 ML) underneath graphene on Ni(111) and its inert properties were verified by means of photoelectron spectroscopy. Intercalation of iron in the space between graphene and Ni(111) changes drastically the magnetic response from the graphene layer that is explained by the formation of the highly spin-polarized 3dz23d_{z^2} quantum-well state in the thin iron layer.Comment: Manuscript and supplementary material

    MIXED-LAYER CHARACTERISTICS AS RELATED TO THE MONSOON CLIMATE OF NEW DELHI, INDIA

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    Abstract. Annual variations of mixed-layer characteristics at New Delhi, India have been studied for a weak monsoon (1987) and a strong monsoon (1988) year. In the weak monsoon year (1987), the maximum mixing depth hma x was found to have a value of around 3000 m during the pre-monsoon, less than 2000 m during the summer monsoon, around 2000 m during the post-monsoon, and less than 1000 m in the winter season. For the strong monsoon year (1988), hmax values were Jess than 1987 values for comparable periods throughout the year. The seasonal and yearly differences of h~ax were explained by the surface energy balance and potential temperature gradient y at a time close to sunrise. According to the spatial patterns of 7 obtained by an objective analysis of the 850 to 700 hPa layers, mixed-layer characteristics obtained at New Delhi are representative of the north and central regions of India

    The Parasite Reduction Ratio (PRR) assay version 2: standardized assessment of Plasmodium falciparum viability after antimalarial treatment in vitro

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    With artemisinin-resistant Plasmodium falciparum parasites emerging in Africa, the need for new antimalarial chemotypes is persistently high. The ideal pharmacodynamic parameters of a candidate drug are a rapid onset of action and a fast rate of parasite killing or clearance. To determine these parameters, it is essential to discriminate viable from nonviable parasites, which is complicated by the fact that viable parasites can be metabolically inactive, whilst dying parasites can still be metabolically active and morphologically unaffected. Standard growth inhibition assays, read out via microscopy or [3H] hypoxanthine incorporation, cannot reliably discriminate between viable and nonviable parasites. Conversely, the in vitro parasite reduction ratio (PRR) assay is able to measure viable parasites with high sensitivity. It provides valuable pharmacodynamic parameters, such as PRR, 99.9% parasite clearance time (PCT99.9%) and lag phase. Here we report the development of the PRR assay version 2 (V2), which comes with a shorter assay duration, optimized quality controls and an objective, automated analysis pipeline that systematically estimates PRR, PCT99.9% and lag time and returns meaningful secondary parameters such as the maximal killing rate of a drug (Emax) at the assayed concentration. These parameters can be fed directly into pharmacokinetic/pharmacodynamic models, hence aiding and standardizing lead selection, optimization, and dose prediction. © 2023 by the authors

    Drug Screen Targeted at Plasmodium Liver Stages Identifies a Potent Multistage Antimalarial Drug

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    Plasmodium parasites undergo a clinically silent and obligatory developmental phase in the host's liver cells before they are able to infect erythrocytes and cause malaria symptoms. To overcome the scarcity of compounds targeting the liver stage of malaria, we screened a library of 1037 existing drugs for their ability to inhibit Plasmodium hepatic development. Decoquinate emerged as the strongest inhibitor of Plasmodium liver stages, both in vitro and in vivo. Furthermore, decoquinate kills the parasite's replicative blood stages and is active against developing gametocytes, the forms responsible for transmission. The drug acts by selectively and specifically inhibiting the parasite's mitochondrial bc1 complex, with little cross-resistance with the antimalarial drug atovaquone. Oral administration of a single dose of decoquinate effectively prevents the appearance of disease, warranting its exploitation as a potent antimalarial compoun

    Limits to sustained energy intake XXIV : impact of suckling behaviour on the body temperatures of lactating female mice

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    We would like to thank the animal house staff and all members of the Energetics group for their invaluable help at various stages throughout the project. This work was supported by Natural Environment Research Council grant (NERC, NE/C004159/1). YG was supported by a scholarship from the rotary foundation. LV was supported by a Rubicon grant from the Netherlands Scientific Organisation (NWO).Peer reviewedPublisher PD

    Oxidation resistance of graphene-coated Cu and Cu/Ni alloy

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    The ability to protect refined metals from reactive environments is vital to many industrial and academic applications. Current solutions, however, typically introduce several negative effects, including increased thickness and changes in the metal physical properties. In this paper, we demonstrate for the first time the ability of graphene films grown by chemical vapor deposition to protect the surface of the metallic growth substrates of Cu and Cu/Ni alloy from air oxidation. SEM, Raman spectroscopy, and XPS studies show that the metal surface is well protected from oxidation even after heating at 200 \degree C in air for up to 4 hours. Our work further shows that graphene provides effective resistance against hydrogen peroxide. This protection method offers significant advantages and can be used on any metal that catalyzes graphene growth
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