283 research outputs found
Glass production at Jalame, Israel: Process, composition and relationship to Roman glass in Europe
Following an initial micro-XRF assay, 42 samples of glass from the twentieth-century excavations of the fourth-century CE production site at Jalame, Israel, were selected and analysed by EPMA, with subsets for trace elements by LA-ICP-MS (n=29 samples) and for Hf isotopes by MC-ICP-MS (n=6). Comparison of major elements for ten samples originally measured in Brill (1988) was good, although the earlier SiO2 values are slightly high. Analyses of furnace debris and contaminated glass imply that glass furnaces were made of, or lined with a lime-rich material, leading to contamination by CaO, rather than Al2O3. This confirms that higher alumina contents measured for Jalame glass relative to Roman Mn-decolourised glass of first-third century Europe are significant and it is suggested that the source of the earlier Roman glass lies further North on the eastern Mediterranean coast. A wide range of trace elements are shown to have entered the glass with the addition of manganese, so caution should be exercised when interpreting trace element and isotopic data on glass with significant amounts of Mn, although the effects on REE and some of the lithophiles most often used in provenancing appear minor or insignificant in Jalame glass with MnO below 1.3 wt%. For example, the hafnium isotope composition of the Jalame material does not appear to have been significantly affected and falls within the previously determined Levantine range, distinguishable from Egyptian glass. Associated trace elements indicate that two Mn sources were exploited and this raises the possibility of further investigation of Mn sources in early glass production. The wide range of added manganese suggests problems in obtaining a homogeneous batch and it is suggested that (a) a single initially inhomogeneous furnace load melted to a range of colours, which were subsequently colour-sorted as chunks, and/or (b) the recycling of poorly fused manganese-decolourised glass into later manganese-free batches resulted in the observed variation. The cobalt pigment used was the high-nickel late antique type and allows the introduction of this source to be pushed back from the sixth to the fourth century CE. The use of antimony in glassmaking ceased at around the same time, and it is speculated that these changes were related
Exotic glass types and the intensity of recycling in the northwest Quarter of Gerasa (Jerash, Jordan)
Major and trace elements are presented for 149 glass fragments ranging in date from the Roman to Early Islamic periods (1st – mid-8th centuries CE), excavated during the Danish-German Jerash Northwest Quarter Project's fieldwork between 2011 and 2016. The results confirm a clear dominance of Levantine glass types, but also reveal 12 glasses of Egyptian and Mesopotamian compositions recovered from two houses destroyed by the major earthquake which hit parts of the Levant in January 749 CE. These closed and undisturbed contexts from the final phase of occupation reveal the presence of relatively more pristine Levantine as well as imported material that is less visible in earlier contexts in the Gerasa assemblage, where the recycling indexes are high and chemical signatures of any exotic glass were largely lost due to remelting and their dilution by the overwhelming quantities of glass produced in the Levantine region. This emphasizes that imported glass may frequently be underestimated or even invisible in glass compositional studies, depending on the archaeological context sampled and the approach taken to artifact quantification.
Levantine glass was attributed to Roman, Late Roman (Jalame) and Byzantine/Early Islamic (Apollonia) productions based primarily on MnO, Al_{2}O_{3} and Na_{2}O concentrations, which offered an advantage over previous approaches. While colorants in weakly colored glass indicate recycled material, their concentrations are sensitive to context, with higher concentrations in the early periods when the use of intentionally colored glass was more frequent. We have therefore developed the concept of the intensity of recycling, which was estimated using components modified during prolonged melting, such as K_{2}O, P_{2}O_{5} and Cl. A pronounced enrichment in CaO, also dependent upon the intensity of recycling, may affect the assignment to compositional groups and should be taken into consideration in future. Recycling in Gerasa appears to have been more intensive than was the case for cities closer to the primary production centers on the Mediterranean coast, consistent with the view that the dependency on recycling increases further away from the source of the primary material. In contrast, the cities in the coastal plain could readily exploit the marine transportation network, which appears to have played a major role in the distribution of raw glass
A Roman provincial city and its contamination legacy from artisanal and daily-life activities
Funding: This project was supported by the Carlsberg Foundation (R.R., www.carlsbergfondet.dk, Grant CF14-0467), Danish National Research Foundation (R.R., www.dg.dk, Grant 119), the Deutsche Forchungsgemeinschaft (A.L., https://www.dfg.de/, grant nos LI978/4-1 and LI978/4-2), the Deutscher Palästinaverein (A.L., https://www.palaestina-verein.de/), the Danish EliteForsk Award (R.R., https://ufm.dk/forskning-og-innovation/forskningsformidling/eliteforsk, grant 4094-00077B), and H. P. Hjerl Hansens Mindefondet for Dansk Palæstinaforskning (RR).Roman metal use and related extraction activities resulted in heavy metal pollution and contamination, in particular of Pb near ancient mines and harbors, as well as producing a global atmospheric impact. New evidence from ancient Gerasa (Jerash), Jordan, suggests that small-scale but intense Roman, Byzantine and Umayyad period urban, artisanal, and everyday site activities contributed to substantial heavy metal contamination of the city and its hinterland wadi, even though no metal mining took place and hardly any lead water pipes were used. Distribution of heavy metal contaminants, especially Pb, observed in the urban soils and sediments within this ancient city and its hinterland wadi resulted from aeolian, fluvial, cultural and post-depositional processes. These represent the contamination pathways of an ancient city-hinterland setting and reflect long-term anthropogenic legacies at local and regional scales beginning in the Roman period. Thus, urban use and re-use of heavy metal sources should be factored into understanding historical global-scale contaminant distributions.Publisher PDFPeer reviewe
Petrogenesis of Siletzia: the world’s youngest oceanic plateau
Siletzia is an accreted Palaeocene-Eocene Large Igneous Province, preserved in the northwest United States and southern Vancouver Island. Although previous workers have suggested that components of Siletzia were formed in tectonic settings including back arc basins, island arcs and ocean islands, more recent work has presented evidence for parts of Siletzia to have formed in response to partial melting of a mantle plume. In this paper, we integrate geochemical and geochronological data to investigate the petrogenetic evolution of the province.
The major element geochemistry of the Siletzia lava flows is used to determine the compositions of the primary magmas of the province, as well as the conditions of mantle melting. These primary magmas are compositionally similar to modern Ocean Island and Mid-Ocean Ridge lavas. Geochemical modelling of these magmas indicates they predominantly evolved through fractional crystallisation of olivine, pyroxenes, plagioclase, spinel and apatite in shallow magma chambers, and experienced limited interaction with crustal components.
Further modelling indicates that Siletzia magmatism was derived from anomalously hot mantle, consistent with an origin in a mantle plume. This plume has been suggested to have been the same as that responsible for magmatism within the Yellowstone Plateau. Trace element compositions of the most primitive Siletzia lavas are similar to suites associated with the Yellowstone Mantle Plume, suggesting that the two provinces were derived from compositionally similar sources. Radiogenic isotope systematics for Siletzia consistently overlap with some of the oldest suites of the Yellowstone Magmatic Province. Therefore, we suggest Siletzia and the Yellowstone Mantle Plume are part of the same, evolving mantle plume system.
Our new geochronological data show the province was emplaced during the time when Eocene sea surface temperatures were their highest. The size of Siletzia makes the province a potential contributing factor to the biospheric perturbation observed in the early Eocene
Reduced level of arousal and increased mortality in adult acute medical admissions: a systematic review and meta-analysis
Abstract Background Reduced level of arousal is commonly observed in medical admissions and may predict in-hospital mortality. Delirium and reduced level of arousal are closely related. We systematically reviewed and conducted a meta-analysis of studies in adult acute medical patients of the relationship between reduced level of arousal on admission and in-hospital mortality. Methods We conducted a systematic review (PROSPERO: CRD42016022048), searching MEDLINE and EMBASE. We included studies of adult patients admitted with acute medical illness with level of arousal assessed on admission and mortality rates reported. We performed meta-analysis using a random effects model. Results From 23,941 studies we included 21 with 14 included in the meta-analysis. Mean age range was 33.4 - 83.8 years. Studies considered unselected general medical admissions (8 studies, n=13,039) or specific medical conditions (13 studies, n=38,882). Methods of evaluating level of arousal varied. The prevalence of reduced level of arousal was 3.1%-76.9% (median 13.5%). Mortality rates were 1.7%-58% (median 15.9%). Reduced level of arousal was associated with higher in-hospital mortality (pooled OR 5.71; 95% CI 4.21-7.74; low quality evidence: high risk of bias, clinical heterogeneity and possible publication bias). Conclusions Reduced level of arousal on hospital admission may be a strong predictor of in-hospital mortality. Most evidence was of low quality. Reduced level of arousal is highly specific to delirium, better formal detection of hypoactive delirium and implementation of care pathways may improve outcomes. Future studies to assess the impact of interventions on in-hospital mortality should use validated assessments of both level of arousal and delirium
Post-collisional shift from polygenetic to monogenetic volcanism revealed by new 40Ar/39Ar ages in the southern Lesser Caucasus (Armenia)
The post-collisional Syunik and Vardenis volcanic highlands, located in the southern Lesser Caucasus mountains (part of the Arabia-Eurasia collision zone) are host to over 200 monogenetic volcanoes, as well as 2 large Quaternary polygenetic volcanoes in the Syunik highland. The latter are overlain by lavas from the monogenetic volcanoes, suggesting there was a transition in the style of volcanic activity from large-volume central vent eruptions to dispersed small-volume eruptions. 12 new high quality 40Ar/39Ar ages are presented here, with 11 ages calculated by step-heating experiments on groundmass separates, and the final age obtained from total fusions of a population of sanidines. All the ages were younger than 1.5 Ma, except for one ignimbrite deposit whose sanidines gave an age of 6 Ma. While the bulk of the exposed products of post-collisional volcanism relate to Pleistocene activity, it is clear there has been active volcanism in the region since at least the late Miocene. All ages for monogenetic volcanoes in the Syunik highland are younger than 1 Ma, but to the north in Vardenis there is geochronological evidence of monogenetic volcanism at 1.4 and 1.3 Ma. An age of 1.3 Ma is determined for a lava flow from one of the polygenetic volcanoes- Tskhouk, and when combined with other ages helps constrain the timing of the polygenetic to monogenetic transition to around 1 Ma. The new ages illustrate a degree of spatio-temporal coupling in the formation of new vents, which could be related to pull-apart basins focussing ascending magmas. This coupling means that future eruptions are particularly likely to occur close to the sites of the most recent Holocene activity. The polygenetic to monogenetic transition is argued to be the result of a decreasing magma supply based on: (i) volume estimates for Holocene eruptions and for all monogenetic volcanoes and their lava flows in Syunik; and (ii) the volcanic stratigraphy of the Lesser Caucasus region which shows late Pliocene- early Pleistocene continental flood basalts being succeeded by a few large andesite-dacite volcanoes and then the most recent deposits consisting of small-volume scoria cones. The Syunik highland has the highest density of monogenetic centres in the Lesser Caucasus, which is taken to indicate this region has the highest magma flux, and was therefore the last location to transition to monogenetic volcanism, which is why the transition is most clearly seen there. There is no evidence from Sr-Nd-B isotope measurements for the exhaustion of fusible slab components in the mantle source, showing that an inherited slab signature can survive for millions of years after the end of subduction. Although volcanism in the Lesser Caucasus is currently waning, a future pulse of activity is possible
Functional comparison of blood-stage Plasmodium falciparum malaria vaccine candidate antigens
The malaria genome encodes over 5,000 proteins and many of these have also been proposed to be potential vaccine candidates, although few of these have been tested clinically. RH5 is one of the leading blood-stage Plasmodium falciparum malaria vaccine antigens and Phase I/II clinical trials of vaccines containing this antigen are currently underway. Its likely mechanism of action is to elicit antibodies that can neutralize merozoites by blocking their invasion of red blood cells (RBC). However, many other antigens could also elicit neutralizing antibodies against the merozoite, and most of these have never been compared directly to RH5. The objective of this study was to compare a range of blood-stage antigens to RH5, to identify any antigens that outperform or synergize with anti-RH5 antibodies. We selected 55 gene products, covering 15 candidate antigens that have been described in the literature and 40 genes selected on the basis of bioinformatics functional prediction. We were able to make 20 protein-in-adjuvant vaccines from the original selection. Of these, S-antigen and CyRPA robustly elicited antibodies with neutralizing properties. Anti-CyRPA IgG generally showed additive GIA with anti-RH5 IgG, although high levels of anti-CyRPA-specific rabbit polyclonal IgG were required to achieve 50% GIA. Our data suggest that further vaccine antigen screening efforts are required to identify a second merozoite target with similar antibody-susceptibility to RH5
The kinetics of antibody binding to Plasmodium falciparum VAR2CSA PfEMP1 antigen and modelling of PfEMP1 antigen packing on the membrane knobs
<p>Abstract</p> <p>Background</p> <p>Infected humans make protective antibody responses to the PfEMP1 adhesion antigens exported by <it>Plasmodium falciparum </it>parasites to the erythrocyte membrane, but little is known about the kinetics of this antibody-receptor binding reaction or how the topology of PfEMP1 on the parasitized erythrocyte membrane influences antibody association with, and dissociation from, its antigenic target.</p> <p>Methods</p> <p>A Quartz Crystal Microbalance biosensor was used to measure the association and dissociation kinetics of VAR2CSA PfEMP1 binding to human monoclonal antibodies. Immuno-fluorescence microscopy was used to visualize antibody-mediated adhesion between the surfaces of live infected erythrocytes and atomic force microscopy was used to obtain higher resolution images of the membrane knobs on the infected erythrocyte to estimate knob surface areas and model VAR2CSA packing density on the knob.</p> <p>Results</p> <p>Kinetic analysis indicates that antibody dissociation from the VAR2CSA PfEMP1 antigen is extremely slow when there is a high avidity interaction. High avidity binding to PfEMP1 antigens on the surface of <it>P. falciparum</it>-infected erythrocytes in turn requires bivalent cross-linking of epitopes positioned within the distance that can be bridged by antibody. Calculations of the surface area of the knobs and the possible densities of PfEMP1 packing on the knobs indicate that high-avidity cross-linking antibody reactions are constrained by the architecture of the knobs and the large size of PfEMP1 molecules.</p> <p>Conclusions</p> <p>High avidity is required to achieve the strongest binding to VAR2CSA PfEMP1, but the structures that display PfEMP1 also tend to inhibit cross-linking between PfEMP1 antigens, by holding many binding epitopes at distances beyond the 15-18 nm sweep radius of an antibody. The large size of PfEMP1 will also constrain intra-knob cross-linking interactions. This analysis indicates that effective vaccines targeting the parasite's vulnerable adhesion receptors should primarily induce strongly adhering, high avidity antibodies whose association rate constant is less important than their dissociation rate constant.</p
- …