140 research outputs found

    Boron and Lithium in Calcium Sulfate Veins: Tracking Precipitation of Diagenetic Materials in Vera Rubin Ridge, Gale Crater

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    The NASA Curiosity rover’s ChemCam instrument suite has detected boron in calcium‐sulfate‐filled fractures throughout the sedimentary strata of Gale crater including Vera Rubin ridge (VRR). The presence of elevated B concentration provides insights into Martian subsurface aqueous processes. In this study we extend the dataset of B in Ca‐sulfate veins across Gale crater, comparing the detection frequency and relative abundances with Li. We report 33 new detections of B within veins analyzed between sols 1548 and 2311 where detections increase in Pettegrove Point and Jura members, which form VRR. The presence of B and Li in the Ca‐sulfate veins is possibly due to dissolution of pre‐existing B in clays of the bedrock by acids or neutral water and redistribution of the elements into the veins. Elevated frequency of B detection in veins of Gale crater correlate with presence of dehydration features such as desiccation cracks, altered clay minerals and detections of evaporites such as Mg‐sulfates, chloride salts in the host rocks. The increased observations of B also coincide with decreased Li concentration in the veins (average Li concentration of veins drops by ~15 ppm). Boron and Li have varying solubilities and Li does not form salts as readily upon dehydration as B, causing it to remain in the solution. So, the weak negative correlation between B and Li may reflect the crystallization sequence during dehydration on Vera Rubin ridge

    The field high-amplitude SX Phe variable BL Cam: results from a multisite photometric campaign. II. Evidence of a binary - possibly triple - system

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    Short-period high-amplitude pulsating stars of Population I (δ\delta Sct stars) and II (SX Phe variables) exist in the lower part of the classical (Cepheid) instability strip. Most of them have very simple pulsational behaviours, only one or two radial modes being excited. Nevertheless, BL Cam is a unique object among them, being an extreme metal-deficient field high-amplitude SX Phe variable with a large number of frequencies. Based on a frequency analysis, a pulsational interpretation was previously given. aims heading (mandatory) We attempt to interpret the long-term behaviour of the residuals that were not taken into account in the previous Observed-Calculated (O-C) short-term analyses. methods heading (mandatory) An investigation of the O-C times has been carried out, using a data set based on the previous published times of light maxima, largely enriched by those obtained during an intensive multisite photometric campaign of BL Cam lasting several months. results heading (mandatory) In addition to a positive (161 ±\pm 3) x 10−9^{-9} yr−1^{-1} secular relative increase in the main pulsation period of BL Cam, we detected in the O-C data short- (144.2 d) and long-term (∼\sim 3400 d) variations, both incompatible with a scenario of stellar evolution. conclusions heading (mandatory) Interpreted as a light travel-time effect, the short-term O-C variation is indicative of a massive stellar component (0.46 to 1 M_{\sun}) with a short period orbit (144.2 d), within a distance of 0.7 AU from the primary. More observations are needed to confirm the long-term O-C variations: if they were also to be caused by a light travel-time effect, they could be interpreted in terms of a third component, in this case probably a brown dwarf star (≥\geq 0.03 \ M_{\sun}), orbiting in ∼\sim 3400 d at a distance of 4.5 AU from the primary.Comment: 7 pages, 5 figures, accepted for publication in A&

    Late Byzantine Mineral Soda High Alumina Glasses from Asia Minor: A New Primary Glass Production Group

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    The chemical characterisation of archaeological glass allows the discrimination between different glass groups and the identification of raw materials and technological traditions of their production. Several lines of evidence point towards the large-scale production of first millennium CE glass in a limited number of glass making factories from a mixture of Egyptian mineral soda and a locally available silica source. Fundamental changes in the manufacturing processes occurred from the eight/ninth century CE onwards, when Egyptian mineral soda was gradually replaced by soda-rich plant ash in Egypt as well as the Islamic Middle East. In order to elucidate the supply and consumption of glass during this transitional period, 31 glass samples from the assemblage found at Pergamon (Turkey) that date to the fourth to fourteenth centuries CE were analysed by electron microprobe analysis (EPMA) and by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The statistical evaluation of the data revealed that the Byzantine glasses from Pergamon represent at least three different glass production technologies, one of which had not previously been recognised in the glass making traditions of the Mediterranean. While the chemical characteristics of the late antique and early medieval fragments confirm the current model of glass production and distribution at the time, the elemental make-up of the majority of the eighth- to fourteenth-century glasses from Pergamon indicate the existence of a late Byzantine glass type that is characterised by high alumina levels. Judging from the trace element patterns and elevated boron and lithium concentrations, these glasses were produced with a mineral soda different to the Egyptian natron from the Wadi Natrun, suggesting a possible regional Byzantine primary glass production in Asia Minor

    Geographical variation in therapy for bloodstream infections due to multidrug-resistant enterobacteriaceae: a post hoc analysis of the INCREMENT study

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    We aimed to describe regional differences in therapy for bloodstream infection (BSI) caused by extended-spectrum ?-lactamase-producing Enterobacteriaceae (ESBL-E) or carbapenemase-producing Enterobacteriaceae (CPE). 1,482 patients in 12 countries were included from an observational study of BSI caused by ESBL-E or CPE. Multivariate logistic regression was used to calculate adjusted odds ratios (aORs) for the influence of country of recruitment on empirical use of ?-lactam/?-lactamase inhibitors (BLBLI) or carbapenems, targeted use of BLBLI for ESBL-E and use of targeted combination therapy for CPE. The use of BLBLI for empirical therapy was least likely in sites from Israel (aOR 0.34, 95% CI 0.14-0.81), Greece (aOR 0.49, 95% CI 0.26-0.94) and Canada (aOR 0.31, 95% CI 0.11-0.88) but more likely in Italy (aOR 1.58, 95% CI 1.11-2.2) and Turkey (aOR 2.09, 95% CI 1.14-3.81), compared to Spain as a reference. Empirical carbapenems were more likely to be used in sites from Taiwan (aOR 1.73, 95% CI 1.03-2.92) and USA (aOR 1.89; 95% CI 1.05-3.39), and less likely in Italy (aOR 0.44, 95% CI 0.28-0.69) and Canada (aOR 0.10, 95% CI 0.01-0.74). Targeted BLBLI for ESBL-E was more likely in sites from Italy. Treatment at sites within Israel, Taiwan, Turkey and Brazil was associated with less combination therapy for CPE. Although this study does not provide precise data on the relative prevalence of ESBL-E or CPE, significant variation in therapy exists across countries even after adjustment for patient factors. A better understanding of what influences therapeutic choices for these infections will aid antimicrobial stewardship efforts.PH is supported by an Australian Postgraduate Award from the University of Queensland. The study was funded by the Ministerio de EconomĂ­a y Competitividad, Instituto de Salud Carlos III - co-financed by European Development Regional Fund "A way to achieve Europe" ERDF, Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015). BGG, JRB, APH and YC also received funds from the COMBACTE-CARE project (grant agreement 115620), Innovative Medicines Initiative (IMI), the European Union's Seventh Framework Programme (FP7/2007-2013) and in-kind contributions from EFPIA companies

    STRATIGRAPHY, MINERALOGY, AND GENESIS OF THE BIGADIC BORATE DEPOSITS, WESTERN TURKEY

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    The Bigadic borates are the largest colemanite and ulexite deposits in the world and the high-grade colemanite and ulexite ores (30 and 29% B2O3, respectively) should supply a substantial proportion of the world's needs for many years. The Bigadic deposits formed within Neogene perennial saline lakes sediments located in a northeast-southwest-trending basin. The volcano-sedimentary sequence in the deposits consists of (from bottom to top) basement volcanics, lower limestone, lower tuff, lower borate zone, upper tuff, upper borate zone, and olivine basalt. The borate deposits formed under arid conditions in perennial saline lakes fed by hyrdrothermal springs associated with local volcanic activity. The deposits are interbedded with tuffs, clays, and limestones

    Glauberite-Thenardite of the Kirmir Formation (Neogene, Beypazar/Basin, Turkey)

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    This paper studies the petrologic and sedimentologic characteristics of the sodium-sulphate deposit which intercalates within the evaporatic facies of the Kirmir Formation (Miocene, Bypazar/Basin, Central Anatolia

    Zoning in the Kirka borate deposit, western Turkey: Primary evaporitic fractionation or diagenetic modifications?

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    The Kirka borate deposit (Miocene), in western Turkey, the most important B2O3 producer at present in the world, exhibits a symmetrical zonation in a lateral sense; it is comprised of: a central body of Na berate (borax), an intermediate zone of Na-Ca borate (ulexite), and a marginal zone of Ca borate (colemanite). This mineral zonation is also developed in a vertical sense, although it is somewhat asymmetrical because of the presence of a discontinuous Mg borate horizon overlying the central body of borax. The genesis of such a mineral zonation in the Tertiary lacustrine borate deposits of the world has been attributed to a number of diagenetic processes. In contrast, we postulate that the Kirka sequence is merely depositional and represents an evaporitic sequence in a lake basin. The existence of a lateral gradient of salinity in the Kirka lacustrine system would have conditioned the concentric pattern of the facies. The various borax lithofacies (chemical, elastic, mixed) present in the central body reflect precipitation in a lake under evolving conditions. These conditions oscillate from a predominant subaqueous setting at variable depths (perennial lake stage), to an interstitial setting (playa-lake stage). The evaporative concentration of the boratiferous solution in the lake, together with the periodic changes in temperature of the water mass, are considered to be the main controls on the crystallization of borax. No petrographic evidence was found for an inyoite-to-colemanite transformation, as previously proposed. Furthermore, the post-depositional burial of the Kirka deposit is considered to be only moderate, and insufficient for such generalized transformation. The Mg borates represent the ultimate evaporitic precipitates from the fractionation of the initial boratiferous solution, instead of the reaction products between pre-existing borates and groundwaters. The mineral zonation in Kirka is primary, not only for borax and ulexite, but also for both the colemanite forming the marginal zone and the Mg borates overlying the central body of borax
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