Intrinsic solidification behaviour of basaltic to rhyolitic melts: a cooling rate experimental study

Dynamic cooling-induced solidification experiments were run using six silicate glasses along the basalt - rhyolite join (B100= 100 wt % of basalt, R100= 100 wt % of rhyolite), i.e. B100, B80R20, B60R40, B40R60, B20R80 and R100; the glasses directly quenched from 1300 °C after a dwell of 120 minutes (experiment E0) contain 50-400 ppm H2O, << 1 area% μm-sized bubble, and Fe2+/Fetot between 0.34 and 0.46. Experiments were performed in Pt capsules at room pressure and fO2 of air, between 1300 and 800 °C using three different cooling rates of 0.0167, 3 and 30 °C/min; these cooling rates were run two times: E1-E2 experiments at 0.0167°C/min, S1-E3 at 3 °C/min, and E4-E5 at 30 °C/min. In experiments E1 to E5, samples were annealed for 120 minutes at 1300 °C, whereas in the experiment S1 the samples were firstly heated for 30 minutes at 1400 °C followed by a dwell time of 2400 minutes at 1300°C before cooling. In the experiments a preferential crystallization was not observed at the melt/gas interface. B100, B80R20 and B60R40 run-products have a low tendency to preferentially crystallize on Pt walls, while B40R60, B20R80 and R100 are not affected by the presence of Pt substrata. All run-products show very homogeneous textures, except for B60R40 and B40R60 at 0.0167°C/min in the E1 experiment. The duplicates of B40R60 and B60R40 at 0.0167°C/min and B100 at 30 °C/min show relatively large differences in crystal content (> 4 and < 14 area%). B40R60 and B60R40 duplicated run-products have the same amount of earlycrystallized clinopyroxene and spinel, but different contents in lately-formed plagioclase. The run-products with the same starting composition from E3-S1 (3 °C/min) show a high reproducibility in terms of crystal shape, size, and amount (< 4 area%). This demonstrates that the crystallization path is not affected by the different heat treatment above the liquidus temperature, i.e. the time scale of structural re-equilibration (relaxation) and chemical rehomogenization are shorter than our experimental time scale. Possible chemicalheterogeneities on a length scale of several micrometers for R100 and several hundreds of micrometers for B100 can be removed at 1300 °C within 120 minutes. A heat treatment at 1300 °C for 120 minutes significantly reduces the amount of μm-sized bubbles, potentially responsible for the onset of nucleation and unreveals the intrinsic solidification of silicate melts. The experimental reproducibility is low when the cooling path intersects the tip of the time-temperature-transformation (TTT) curves, i.e. when the nucleation rate is near its maximum (Imax). In that case, even small thermal variations in cooling rate and local composition can have large effects on phase abundance and crystal size. Dynamic crystallization experiments can be properly interpreted and compared only if they are texturally homogeneous and the physico-chemical state of the superheated silicate liquid is known. The solidification conditions used in this study mirror those of aphyric lavas and dikes emplaced at shallower crustal levels

Contributions of domestic sources to PM2.5 in South Korea

We use the CAMx (Comprehensive Air Quality Model with Extensions) chemical transport model (CTM) with 4-km horizontal resolution over the Korean Peninsula to investigate source contributions to PM2.5 in Korea from domestic and upwind sources. We modeled 2015 and 2016 to account for meteorological variation with Korean emissions from the Clean Air Policy Supporting System (CAPSS), meteorology from WRF (Weather, Research, and Forecasting) model, and regional boundary concentrations from the GEOS-Chem global CTM. The CAMx particulate source apportionment technology (PSAT) provided PM2.5 source contributions from 5 source sectors and 6 geographic regions within Korea, international sources, and boundary concentrations. PM2.5 contributions from outside Korea are important with boundary concentrations plus the “other” emissions sector (includes marine shipping, agricultural ammonia, and international emissions from North Korea and Japan within the CAMx domain) contributing 67% of annual average PM2.5 in Seoul in 2016 and 71% in 2015. The boundary concentrations contributed between 30% and 50% of PM2.5 at different Korean cities with contributions generally lower in 2016 than in 2015. For Korean sources, PM2.5 contributions from Electric Generating Unit (EGU) emissions were smaller than contributions from mobile and industrial emissions sources although there is considerable day-to-day variation in contributions. On an annual basis in 2016, the “other” category contributed 25% followed by mobile sources at 23%, industrial sources at 6%, and EGU sources at 3%. For 2015, the contributions were similar. Focusing on March when PM2.5 concentrations were higher than other months, the contributions from other, mobile, industrial, and EGUs were 21%, 18%, 4%, and 4%, respectively in 2016. For 2015, contributions from these four categories were 18%, 15%, 3%, and 3%, respectively

Contributions of international sources to PM2.5 in South Korea

The air quality in Republic of Korea, especially in cities such as Seoul, has been a serious public health concern over the years. The key pollutant in the atmosphere leading to poor air quality in Korea is fine particulate matter (PM2.5). Here, we use a 3-D global chemistry model (GEOS-Chem) to conduct source attribution to PM2.5 in Korea from international and domestic emissions. The modeling was done for 2015 and 2016 to account for different meteorological conditions. We ran the GEOS-Chem model for both years, conducted model evaluation using ground and aloft observations, and then conducted sensitivity simulations without domestic anthropogenic emissions and Chinese anthropogenic emissions, respectively. Results show that the Chinese influence on PM2.5 in Korea varies from month to month with the highest contribution during spring when observed concentrations are also the highest. Chinese contributions to PM2.5 concentrations in South Korea reach a maximum of up to ~60% in January and February and gradually decrease until August when they reach a minimum at about 20%. On an annual basis, our analysis estimated that in 2016, Chinese anthropogenic emissions contributed 45% to PM2.5 in South Korea. The 2016 contribution from China was generally 3–5% lower than in 2015 because of emissions reductions in China. Compared to the Chinese contribution, the rest of the world contributions (which also include contributions from natural emissions worldwide) were minor except for summer in the South Sea

The French Didactic Tradition in Mathematics

This chapter presents the French didactic tradition. It first describes theemergence and development of this tradition according to four key features (role ofmathematics and mathematicians, role of theories, role of design of teaching andlearning environments, and role of empirical research), and illustrates it through two case studies respectively devoted to research carried out within this traditionon algebra and on line symmetry-reflection. It then questions the influence of thistradition through the contributions of four researchers from Germany, Italy, Mexicoand Tunisia, before ending with a short epilogue

Circulating soluble Fas levels and risk of ovarian cancer

BACKGROUND: Dysregulation of apoptosis, specifically overexpression of soluble Fas (sFas), has been proposed to play a role in the development of ovarian cancer. The main objective of the present study was to evaluate serum sFas as a potential biomarker of ovarian cancer risk. METHODS: The association between serum sFas levels and the risk of ovarian cancer was examined in a case-control study nested within three prospective cohorts in New York (USA), Umeå (Sweden), and Milan (Italy). Case subjects were 138 women with primary invasive epithelial ovarian cancer diagnosed between 2 months and 13.2 years after the initial blood donation. Control subjects were 263 women who were free of cancer, and matched the case on cohort, menopausal status, age, and enrollment date. Serum sFas levels were determined using a quantitative sandwich enzyme immunoassay. RESULTS: Serum sFas levels were similar in women subsequently diagnosed with ovarian cancer (median, 6.5 ng/mL; range, 4.4 – 10.2) and in controls (median, 6.8 ng/mL; range, 4.5 – 10.1). Statistically significant trends of increasing serum sFas with age were observed among cases (r = 0.39, p < 0.0001) and controls (r = 0.42, p < 0.0001). Compared to women in the lowest third, women in the highest third of serum sFas were not at increased risk of ovarian cancer after adjustment for potential confounders (odd ratio (OR), 0.87; 95% confidence interval (CI), 0.42 – 1.82). CONCLUSION: The results suggest that serum sFas may not be a suitable marker for identification of women at increased risk of ovarian cancer

Non-allergic rhinitis: a case report and review

Rhinitis is characterized by rhinorrhea, sneezing, nasal congestion, nasal itch and/or postnasal drip. Often the first step in arriving at a diagnosis is to exclude or diagnose sensitivity to inhalant allergens. Non-allergic rhinitis (NAR) comprises multiple distinct conditions that may even co-exist with allergic rhinitis (AR). They may differ in their presentation and treatment. As well, the pathogenesis of NAR is not clearly elucidated and likely varied. There are many conditions that can have similar presentations to NAR or AR, including nasal polyps, anatomical/mechanical factors, autoimmune diseases, metabolic conditions, genetic conditions and immunodeficiency. Here we present a case of a rare condition initially diagnosed and treated as typical allergic rhinitis vs. vasomotor rhinitis, but found to be something much more serious. This case illustrates the importance of maintaining an appropriate differential diagnosis for a complaint routinely seen as mundane. The case presentation is followed by a review of the potential causes and pathogenesis of NAR

The RESET project: constructing a European tephra lattice for refined synchronisation of environmental and archaeological events during the last c. 100 ka

This paper introduces the aims and scope of the RESET project (. RESponse of humans to abrupt Environmental Transitions), a programme of research funded by the Natural Environment Research Council (UK) between 2008 and 2013; it also provides the context and rationale for papers included in a special volume of Quaternary Science Reviews that report some of the project's findings. RESET examined the chronological and correlation methods employed to establish causal links between the timing of abrupt environmental transitions (AETs) on the one hand, and of human dispersal and development on the other, with a focus on the Middle and Upper Palaeolithic periods. The period of interest is the Last Glacial cycle and the early Holocene (c. 100-8 ka), during which time a number of pronounced AETs occurred. A long-running topic of debate is the degree to which human history in Europe and the Mediterranean region during the Palaeolithic was shaped by these AETs, but this has proved difficult to assess because of poor dating control. In an attempt to move the science forward, RESET examined the potential that tephra isochrons, and in particular non-visible ash layers (cryptotephras), might offer for synchronising palaeo-records with a greater degree of finesse. New tephrostratigraphical data generated by the project augment previously-established tephra frameworks for the region, and underpin a more evolved tephra 'lattice' that links palaeo-records between Greenland, the European mainland, sub-marine sequences in the Mediterranean and North Africa. The paper also outlines the significance of other contributions to this special volume: collectively, these illustrate how the lattice was constructed, how it links with cognate tephra research in Europe and elsewhere, and how the evidence of tephra isochrons is beginning to challenge long-held views about the impacts of environmental change on humans during the Palaeolithic. © 2015 Elsevier Ltd.RESET was funded through Consortium Grants awarded by the Natural Environment Research Council, UK, to a collaborating team drawn from four institutions: Royal Holloway University of London (grant reference NE/E015905/1), the Natural History Museum, London (NE/E015913/1), Oxford University (NE/E015670/1) and the University of Southampton, including the National Oceanography Centre (NE/01531X/1). The authors also wish to record their deep gratitude to four members of the scientific community who formed a consultative advisory panel during the lifetime of the RESET project: Professor Barbara Wohlfarth (Stockholm University), Professor Jørgen Peder Steffensen (Niels Bohr Institute, Copenhagen), Dr. Martin Street (Romisch-Germanisches Zentralmuseum, Neuwied) and Professor Clive Oppenheimer (Cambridge University). They provided excellent advice at key stages of the work, which we greatly valued. We also thank Jenny Kynaston (Geography Department, Royal Holloway) for construction of several of the figures in this paper, and Debbie Barrett (Elsevier) and Colin Murray Wallace (Editor-in-Chief, QSR) for their considerable assistance in the production of this special volume.Peer Reviewe