Mercury enrichments and the Frasnian-Famennian biotic crisis: A volcanic trigger proved?

The Frasnian-Famennian (F-F) global event, one of the five largest biotic crises of the Phanerozoic, has been inconclusively linked to rapid climatic perturbations promoted in turn by volcanic cataclysm, especially in the Viluy large igneous province (LIP) of Siberia. Conversely, the triggers of four other Phanerozoic mass extinction intervals have decisively been linked to LIPs, owing to documented mercury anomalies, shown as the diagnostic proxy. Here, we report multiple Hg enrichments in the two-step late Frasnian (Kellwasser) crisis interval from paleogeographically distant successions in Morocco, Germany, and northern Russia. The distinguishing signal, > 1 ppm Hg in the domain of closing Rheic Ocean, was identified in different lithologies immediately below the F-F boundary and approximately correlated with the onset of the main extinction pulse. This key Hg anomaly, comparable only with an extreme spike known from the end-Ordovician extinction, was not controlled by increased bioproductivity in an anoxic setting. We suggest, therefore, that the global chemostratigraphic pattern near the F-F boundary records a greatly increased worldwide Hg input, controlled by the Center Hill eruptive pulse of the Eovariscan volcanic acme, but likely not manifested exclusively by LIP(s). Consequently, all five major biotic crises of the Phanerozoic have now been more reliably linked to volcanic cataclysms

Modeling performance of Hadoop applications: A journey from queueing networks to stochastic well formed nets

Nowadays, many enterprises commit to the extraction of actionable knowledge from huge datasets as part of their core business activities. Applications belong to very different domains such as fraud detection or one-to-one marketing, and encompass business analytics and support to decision making in both private and public sectors. In these scenarios, a central place is held by the MapReduce framework and in particular its open source implementation, Apache Hadoop. In such environments, new challenges arise in the area of jobs performance prediction, with the needs to provide Service Level Agreement guarantees to the enduser and to avoid waste of computational resources. In this paper we provide performance analysis models to estimate MapReduce job execution times in Hadoop clusters governed by the YARN Capacity Scheduler. We propose models of increasing complexity and accuracy, ranging from queueing networks to stochastic well formed nets, able to estimate job performance under a number of scenarios of interest, including also unreliable resources. The accuracy of our models is evaluated by considering the TPC-DS industry benchmark running experiments on Amazon EC2 and the CINECA Italian supercomputing center. The results have shown that the average accuracy we can achieve is in the range 9–14%

Salvinorin A analogues PR-37 and PR-38 attenuate compound 48/80-induced itch responses in mice: Salvinorin A analogues PR-37 and PR-38 in pruritus

The opioid system plays a crucial role in several physiological processes in the CNS and in the periphery. It has also been shown that selective opioid receptor agonists exert potent inhibitory action on pruritus and pain. In this study we examined whether two analogues of Salvinorin A, PR-37 and PR-38, exhibit antipruritic properties in mice

Low-temperature zircon growth related to hydrothermal alteration of siderite concretions in Mississippian shales, Scotland

Zircon occurs in voids and cracks in phosphatic coprolites enclosed in siderite concretions in Mississippian shales near Edinburgh, Scotland. The zircon formed during hydrothermal alteration of early-diagenetic concretions and occurs as spherical aggregates of prismatic crystals, sometimes radiating. Vitrinite reflectance measurements indicate temperatures of ~270°C for the zircon-bearing concretions and the host shales. Molecular parameter values based on dibenzothiophene and phenanthrene distribution and occurrence of di- and tetra-hydro-products of polycyclic aromatic compounds suggest that the rocks experienced relatively high-temperature aqueous conditions related to hydrothermal fluids, perhaps associated with neighboring mafic intrusions. The zircon was dissolved from the concretions, transported in fluids, and reprecipitated in voids. This is the first record of the precipitation of authigenic zircon in sedimentary rock as a new phase, not as outgrowths

Lake sediment fecal and biomass burning biomarkers provide direct evidence for prehistoric human-lit fires in New Zealand

Deforestation associated with the initial settlement of New Zealand is a dramatic example of how humans can alter landscapes through fire. However, evidence linking early human presence and land-cover change is inferential in most continental sites. We employed a multi-proxy approach to reconstruct anthropogenic land use in New Zealand’s South Island over the last millennium using fecal and plant sterols as indicators of human activity and monosaccharide anhydrides, polycyclic aromatic hydrocarbons, charcoal and pollen as tracers of fire and vegetation change in lake-sediment cores. Our data provide a direct record of local human presence in Lake Kirkpatrick and Lake Diamond watersheds at the time of deforestation and a new and stronger case of human agency linked with forest clearance. The first detection of human presence matches charcoal and biomarker evidence for initial burning at c. AD 1350. Sterols decreased shortly after to values suggesting the sporadic presence of people and then rose to unprecedented levels after the European settlement. Our results confirm that initial human arrival in New Zealand was associated with brief and intense burning activities. Testing our approach in a context of well-established fire history provides a new tool for understanding cause-effect relationships in more complex continental reconstructions

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts. June 4-7, 2019, Szczyrk, Polan

Konzentrat-Lagerstätte-type carbonate concretions from the uppermost Bajocian (Middle Jurassic) of the Częstochowa area, South-Cental Poland

Early-diagenetic calcitic concretions of latest Bajocian (parkinsoni Zone, bomfordi Subzone) age in the Polish Jura contain an extremely rich and well-preserved macrofauna. In addition to bivalves and brachiopods, there are numerous ammonites of the (sub)genera Parkinsonia, Nannolytoceras, Lissoceras (Lissoceras), L. (Microlissoceras), as well as rare representatives of Vermisphinctes, Strigoceras (Strigoceras) and Phylloceras. Carapaces of primitive prosopid crabs are found associated. Such a diverse and well-preserved fauna (previously unknown from Bajocian epicratonic deposits of the Polish Jura), is typical of Konzentrat-Lagerstätte-type deposits. The random distribution of the concretions in exposure and the small size of the fauna may suggest that all remains were concentrated by bottom-current action in small depressions on an uneven sea-floor. The presence of numerous small-sized ammonites may be regarded as reflecting post-spawning assemblages which sufferedmass-mortality. Although cause of their death remains unclear, storm events are a possibility. Such depressions acted as natural “traps” as well as constituted a size-limiting factor for the accumulating fauna. The fact that all elements are well preserved indicates brief post-mortem transport and rapid burial, followed by early diagenesis that protected them from compaction. The absence of such fossil-rich concretions higher in the Middle Jurassic sequence clearly shows that our current assessment of biotic diversity may be an underestimate. The carbonate concretions contain a predominantly terrestrial type of organic matter (OM). Samples analysed are extremely immature, but early diagenetic transformations of OM occurred prior to concretion formation