Small carbonaceous fossils (SCFs) from the Terreneuvian (lower Cambrian) of Baltica

We describe a new assemblage of small carbonaceous fossils (SCFs) from diagenetically 9 minimally altered clays and siltstones of Terreneuvian age from the Lontova and Voosi formations of 10 Estonia, Lithuania and Russia. This is the first detailed account of an SCF assemblage from the 11 Terreneuvian, and includes a number of previously undocumented Cambrian organisms. Recognisably 12 bilaterian-derived SCFs include abundant protoconodonts (total-group Chaetognatha), and distinctive 13 cuticular spines of scalidophoran worms. Alongside these metazoan remains are a range of protistan-14 grade fossils, including Retiranus balticus gen. et sp. nov., a distinctive funnel-shaped or sheet-like 15 problematicum characterized by terminal or marginal vesicles, and Lontohystrichosphaera grandis 16 gen. et sp. nov., a large (100–550 μm) ornamented vesicular microfossil. Together these data offer a 17 fundamentally enriched view of Terreneuvian life in the epicratonic seas of Baltica, from an episode 18 where records of non-biomineralized life are currently sparse. Even so, the recovered assemblages 19 contain a lower diversity of metazoans than SCF biotas from younger (Stage 4) Baltic successions that 20 represent broadly equivalent environments, echoing the diversification signal recorded in the coeval 21 shelly and trace-fossil records. Close comparison to the biostratigraphic signal from Fortunian small 22 shelly fossils (SSFs) supports a late Fortunian age for most of the Lontova/Voosi succession, rather 23 than a younger (wholly Stage 2) range.NER

Small carbonaceous fossils (SCFs) from the Terreneuvian (lower Cambrian) of Baltica

We describe a new assemblage of small carbonaceous fossils (SCFs) from diagenetically 9 minimally altered clays and siltstones of Terreneuvian age from the Lontova and Voosi formations of 10 Estonia, Lithuania and Russia. This is the first detailed account of an SCF assemblage from the 11 Terreneuvian, and includes a number of previously undocumented Cambrian organisms. Recognisably 12 bilaterian-derived SCFs include abundant protoconodonts (total-group Chaetognatha), and distinctive 13 cuticular spines of scalidophoran worms. Alongside these metazoan remains are a range of protistan-14 grade fossils, including Retiranus balticus gen. et sp. nov., a distinctive funnel-shaped or sheet-like 15 problematicum characterized by terminal or marginal vesicles, and Lontohystrichosphaera grandis 16 gen. et sp. nov., a large (100–550 μm) ornamented vesicular microfossil. Together these data offer a 17 fundamentally enriched view of Terreneuvian life in the epicratonic seas of Baltica, from an episode 18 where records of non-biomineralized life are currently sparse. Even so, the recovered assemblages 19 contain a lower diversity of metazoans than SCF biotas from younger (Stage 4) Baltic successions that 20 represent broadly equivalent environments, echoing the diversification signal recorded in the coeval 21 shelly and trace-fossil records. Close comparison to the biostratigraphic signal from Fortunian small 22 shelly fossils (SSFs) supports a late Fortunian age for most of the Lontova/Voosi succession, rather 23 than a younger (wholly Stage 2) range.NER

Oxygen minimum zones in the early Cambrian ocean

The relationship between the evolution of early animal 26 communities and oceanic oxygen levels remains unclear. In particular, uncertainty persists in reconstructions of redox conditions during the pivotal early Cambrian (541-510 million years ago, Ma), where conflicting datasets from deeper marine settings suggest either ocean anoxia or fully oxygenated conditions. By coupling geochemical palaeoredox proxies with a record of organic-walled fossils from exceptionally well-defined successions of the early Cambrian Baltic Basin, we provide evidence for the early establishment of modern-type oxygen minimum zones (OMZs). Both inner- and outer shelf environments were pervasively oxygenated, whereas mid-depth settings were characterized by spatially oscillating anoxia. As such, conflicting redox signatures recovered from individual sites most likely derive from sampling bias, whereby anoxic conditions represent mid-shelf environments with higher productivity. This picture of a spatially restricted anoxic wedge contrasts with prevailing models of globally stratified oceans, offering a more nuanced and realistic account of the Proterozoic-Phanerozoic ocean transition

Life-cycle impact assessment methods for physical energy scarcity: considerations and suggestions

Purpose: Most approaches for energy use assessment in life cycle assessment do not consider the scarcity of energy resources. A few approaches consider the scarcity of fossil energy resources only. No approach considers the scarcity of both renewable and non-renewable energy resources. In this paper, considerations for including physical energy scarcity of both renewable and non-renewable energy resources in life cycle impact assessment (LCIA) are discussed. Methods: We begin by discussing a number of considerations for LCIA methods for energy scarcity, such as which impacts of scarcity to consider, which energy resource types to include, which spatial resolutions to choose, and how to match with inventory data. We then suggest three LCIA methods for physical energy scarcity. As proof of concept, the use of the third LCIA method is demonstrated in a well-to-wheel assessment of eight vehicle propulsion fuels. Results and discussion: We suggest that global potential physical scarcity can be operationalized using characterization factors based on the reciprocal physical availability for a set of nine commonly inventoried energy resource types. The three suggested LCIA methods for physical energy scarcity consider the following respective energy resource types: (i) only stock-type energy resources (natural gas, coal, crude oil and uranium), (ii) only flow-type energy resources (solar, wind, hydro, geothermal and the flow generated from biomass funds), and (iii) both stock- and flow-type resources by introducing a time horizon over which the stock-type resources are distributed. Characterization factors for these three methods are provided. Conclusions: LCIA methods for physical energy scarcity that provide meaningful information and complement other methods are feasible and practically applicable. The characterization factors of the three suggested LCIA methods depend heavily on the aggregation level of energy resource types. Future studies may investigate how physical energy scarcity changes over time and geographical locations

Equator-to-pole temperature differences and the extra-tropical storm track responses of the CMIP5 climate models

This paper aims to understand the physical processes causing the large spread in the storm track projections of the CMIP5 climate models. In particular, the relationship between the climate change responses of the storm tracks, as measured by the 2–6 day mean sea level pressure variance, and the equator-to-pole temperature differences at upper- and lower-tropospheric levels is investigated. In the southern hemisphere the responses of the upper- and lower-tropospheric temperature differences are correlated across the models and as a result they share similar associations with the storm track responses. There are large regions in which the storm track responses are correlated with the temperature difference responses, and a simple linear regression model based on the temperature differences at either level captures the spatial pattern of the mean storm track response as well explaining between 30 and 60 % of the inter-model variance of the storm track responses. In the northern hemisphere the responses of the two temperature differences are not significantly correlated and their associations with the storm track responses are more complicated. In summer, the responses of the lower-tropospheric temperature differences dominate the inter-model spread of the storm track responses. In winter, the responses of the upper- and lower-temperature differences both play a role. The results suggest that there is potential to reduce the spread in storm track responses by constraining the relative magnitudes of the warming in the tropical and polar regions

Vulnerability of low-arsenic aquifers to municipal pumping in Bangladesh

Sandy aquifers deposited >12,000 years ago, some as shallow as 30 m, have provided a reliable supply of low-arsenic (As) drinking water in rural Bangladesh. This study concerns the potential risk of contaminating these aquifers in areas surrounding the city of Dhaka where hydraulic heads in aquifers >150 m deep have dropped by 70 m in a few decades due to municipal pumping. Water levels measured continuously from 2012 to 2014 in 12 deep (>150 m), 3 intermediate (90-150 m) and 6 shallow (<90 m) community wells, 1 shallow private well, and 1 river piezometer show that the resulting drawdown cone extends 15-35 km east of Dhaka. Water levels in 4 low-As community wells within the 62-147 m depth range closest to Dhaka were inaccessible by suction for up to a third of the year. Lateral hydraulic gradients in the deep aquifer system ranged from 1.7 × 10-4 to 3.7 × 10-4 indicating flow towards Dhaka throughout 2012-2014. Vertical recharge on the edge of the drawdown cone was estimated at 0.21 ± 0.06 m/yr. The data suggest that continued municipal pumping in Dhaka could eventually contaminate some relatively shallow community wells

A systematic review of models to predict recruitment to multicentre clinical trials

<p>Abstract</p> <p>Background</p> <p>Less than one third of publicly funded trials managed to recruit according to their original plan often resulting in request for additional funding and/or time extensions. The aim was to identify models which might be useful to a major public funder of randomised controlled trials when estimating likely time requirements for recruiting trial participants. The requirements of a useful model were identified as usability, based on experience, able to reflect time trends, accounting for centre recruitment and contribution to a commissioning decision.</p> <p>Methods</p> <p>A systematic review of English language articles using MEDLINE and EMBASE. Search terms included: randomised controlled trial, patient, accrual, predict, enrol, models, statistical; Bayes Theorem; Decision Theory; Monte Carlo Method and Poisson. Only studies discussing prediction of recruitment to trials using a modelling approach were included. Information was extracted from articles by one author, and checked by a second, using a pre-defined form.</p> <p>Results</p> <p>Out of 326 identified abstracts, only 8 met all the inclusion criteria. Of these 8 studies examined, there are five major classes of model discussed: the unconditional model, the conditional model, the Poisson model, Bayesian models and Monte Carlo simulation of Markov models. None of these meet all the pre-identified needs of the funder.</p> <p>Conclusions</p> <p>To meet the needs of a number of research programmes, a new model is required as a matter of importance. Any model chosen should be validated against both retrospective and prospective data, to ensure the predictions it gives are superior to those currently used.</p

The Sec1/Munc18 protein Vps45 regulates cellular levels of its SNARE binding partners Tlg2 and Snc2 in Saccharomyces cerevisiae

Intracellular membrane trafficking pathways must be tightly regulated to ensure proper functioning of all eukaryotic cells. Central to membrane trafficking is the formation of specific SNARE (soluble N-ethylmeleimide-sensitive factor attachment protein receptor) complexes between proteins on opposing lipid bilayers. The Sec1/Munc18 (SM) family of proteins play an essential role in SNARE-mediated membrane fusion, and like the SNAREs are conserved through evolution from yeast to humans. The SM protein Vps45 is required for the formation of yeast endosomal SNARE complexes and is thus essential for traffic through the endosomal system. Here we report that, in addition to its role in regulating SNARE complex assembly, Vps45 regulates cellular levels of its SNARE binding partners: the syntaxin Tlg2 and the v-SNARE Snc2: Cells lacking Vps45 have reduced cellular levels of Tlg2 and Snc2; and elevation of Vps45 levels results in concomitant increases in the levels of both Tlg2 and Snc2. As well as regulating traffic through the endosomal system, the Snc v-SNAREs are also required for exocytosis. Unlike most vps mutants, cells lacking Vps45 display multiple growth phenotypes. Here we report that these can be reversed by selectively restoring Snc2 levels in vps45 mutant cells. Our data indicate that as well as functioning as part of the machinery that controls SNARE complex assembly, Vps45 also plays a key role in determining the levels of its cognate SNARE proteins; another key factor in regulation of membrane traffic