749 research outputs found

    Stratigraphic Overview of Palaeogene Tuffs in the Faroe-Shetland Basin, NE Atlantic Margin

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    Acknowledgements We are very grateful to PGS for generously donating seismic datasets. Seismic interpretation was carried out using IHS Kingdom software, and wells were downloaded from the UK Oil & Gas Common Data Access Welllog interpretation was conducted using Schlumberger Techlog software. D.W. would also like to thank C. Telford for insights regarding the identification of tuffs in ditch cuttings and Total (UK) for material concerning the Vaila Formation. Attendees of VMRC workshops from academia and industry provided important insights into the stratigraphy of the FSB. Finally,D.W.would like to acknowledge the late Robert Knox, without whom our knowledge of North Atlantic explosive volcanism would be considerably poorer. The reviews of P. Reynolds and J. Ólavsdóttir greatly improved the paper. Funding This work is part of D.W.’s PhD research, which is funded by a University of Aberdeen College of Physical Sciences Scholarship.Peer reviewedPostprin

    Examining the role of individual movement in promoting coexistence in a spatially explicit prisoner's dilemma

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    AEFB gratefully acknowledges the support of an EPSRC CASE PhD studentship.The emergence of cooperation is a major conundrum of evolutionary biology. To unravel this evolutionary riddle, several models have been developed within the theoretical framework of spatial game theory, focussing on the interactions between two general classes of player, "cooperators" and "defectors". Generally, explicit movement in the spatial domain is not considered in these models, with strategies moving via imitation or through colonisation of neighbouring sites. We present here a spatially explicit stochastic individual-based model in which pure cooperators and defectors undergo random motion via diffusion and also chemotaxis guided by the gradient of a semiochemical. Individual movement rules are derived from an underlying system of reaction-diffusion-taxis partial differential equations which describes the dynamics of the local number of individuals and the concentration of the semiochemical. Local interactions are governed by the payoff matrix of the classical prisoner's dilemma, and accumulated payoffs are translated into offspring. We investigate the cases of both synchronous and non-synchronous generations. Focussing on an ecological scenario where defectors are parasitic on cooperators, we find that random motion and semiochemical sensing bring about self-generated patterns in which resident cooperators and parasitic defectors can coexist in proportions that fluctuate about non-zero values. Remarkably, coexistence emerges as a genuine consequence of the natural tendency of cooperators to aggregate into clusters, without the need for them to find physical shelter or outrun the parasitic defectors. This provides further evidence that spatial clustering enhances the benefits of mutual cooperation and plays a crucial role in preserving cooperative behaviours.PostprintPeer reviewe

    Survival, Growth and Reproduction of Non-Native Nile Tilapia II: Fundamental Niche Projections and Invasion Potential in the Northern Gulf of Mexico

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    Understanding the fundamental niche of invasive species facilitates our ability to predict both dispersal patterns and invasion success and therefore provides the basis for better-informed conservation and management policies. Here we focus on Nile tilapia (Oreochromis niloticus Linnaeus, 1758), one of the most widely cultured fish worldwide and a species that has escaped local aquaculture facilities to become established in a coastal-draining river in Mississippi (northern Gulf of Mexico). Using empirical physiological data, logistic regression models were developed to predict the probabilities of Nile tilapia survival, growth, and reproduction at different combinations of temperature (14 and 30°C) and salinity (0–60, by increments of 10). These predictive models were combined with kriged seasonal salinity data derived from multiple long-term data sets to project the species\u27 fundamental niche in Mississippi coastal waters during normal salinity years (averaged across all years) and salinity patterns in extremely wet and dry years (which might emerge more frequently under scenarios of climate change). The derived fundamental niche projections showed that during the summer, Nile tilapia is capable of surviving throughout Mississippi\u27s coastal waters but growth and reproduction were limited to river mouths (or upriver). Overwinter survival was also limited to river mouths. The areas where Nile tilapia could survive, grow, and reproduce increased during extremely wet years (2–368%) and decreased during extremely dry years (86–92%) in the summer with a similar pattern holding for overwinter survival. These results indicate that Nile tilapia is capable of 1) using saline waters to gain access to other watersheds throughout the region and 2) establishing populations in nearshore, low-salinity waters, particularly in the western portion of coastal Mississippi

    Zooplankton Avoidance of a Profiled Open-Path Fluorometer

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    Significant avoidance of acoustically detected zooplankton was observed in response to a profiling instrument package. Avoidance decreased acoustic scattering from zooplankton averaged over the entire profile by more than a factor of 2, while the maximum avoidance decreased zooplankton acoustic scattering by a factor of 15 over the depth of some discrete scattering layers. Experimental manipulation of the profiler and its instruments revealed that an open-path fluorometer was triggering the avoidance. Avoidance occurred at an average of 8 m below the profiler with a range between 2 and 13 m. Effect range was positively correlated with the average attenuation coefficient of light over the effect range and consistently resulted in avoidance when light levels of approximately 0.013 µmol photons m−2 s−1 were received by the zooplankton. These results have important implications for the analysis of zooplankton data collected from platforms carrying open-path fluorometers and may also warrant careful interpretation of optical measurements from these packages

    PTEN protein phosphatase activity is not required for tumour suppression in the mouse prostate

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    Loss PTEN function is one of the most common events driving aggressive prostate cancers and biochemically, PTEN is a lipid phosphatase which opposes the activation of the oncogenic PI3K-AKT signalling network. However, PTEN also has additional potential mechanisms of action, including protein phosphatase activity. Using a mutant enzyme, PTEN Y138L, which selectively lacks protein phosphatase activity, we characterised genetically modified mice lacking either the full function of PTEN in the prostate gland or only lacking protein phosphatase activity. The phenotypes of mice carrying a single allele of either wild-type Pten or Pten(Y138L) in the prostate were similar, with common prostatic intraepithelial neoplasia (PIN) and similar gene expression profiles. However, the latter group, lacking PTEN protein phosphatase activity additionally showed lymphocyte infiltration around PIN and an increased immune cell gene expression signature. Prostate adenocarcinoma, elevated proliferation and AKT activation were only frequently observed when PTEN was fully deleted. We also identify a common gene expression signature of PTEN loss conserved in other studies (including Nkx3.1, Tnf and Cd44). We provide further insight into tumour development in the prostate driven by loss of PTEN function and show that PTEN protein phosphatase activity is not required for tumour suppression

    Care of elderly in Portugal: Official data and scientific and professional challenges

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    First published online: 10 August 2019The world has never been so active in approaching human needs and human rights. As the population has become older, new kind of pressures has been made over health and protective services, as well as on research targeted to older adults. This chapter presents the scientific and practical developments in the field of elder mistreatment in Portugal. An overview of the scientific trends in Portuguese research is presented. National research on elder mistreatment has been increasing slowly. The current national scenery is focused on prevalence data and identifying risk and vulnerabilities. This chapter will also discuss the support structures available for mistreated older adults in Portugal, namely the current legal framework and the institutions/entities that offer aid to the victims. Legally, elder mistreatment in Portugal is no different from domestic violence, though some legislative advances have been seen in abandonment. Some structures have been developed over the years to offer aid to older adults, from special programs in the police to private institutions, passing by government supported initiatives.This study was conducted at Psychology Research Centre (UID/PSI/01662/2013), University of Minho, and supported by the Portuguese Foundation for Science and Technology and the Portuguese Ministry of Science, Technology and Higher Education through national funds and co-financed by FEDER through COMPETE2020 under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007653). The first author was funded by a scholarship from the Portuguese Foundations for Science and Technology - FCT - (PD/BD/105965/2014

    How many biological replicates are needed in an RNA-seq experiment and which differential expression tool should you use?

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    An RNA-seq experiment with 48 biological replicates in each of 2 conditions was performed to determine the number of biological replicates (nrn_r) required, and to identify the most effective statistical analysis tools for identifying differential gene expression (DGE). When nr=3n_r=3, seven of the nine tools evaluated give true positive rates (TPR) of only 20 to 40 percent. For high fold-change genes (log2(FC)>2|log_{2}(FC)|\gt2) the TPR is >85\gt85 percent. Two tools performed poorly; over- or under-predicting the number of differentially expressed genes. Increasing replication gives a large increase in TPR when considering all DE genes but only a small increase for high fold-change genes. Achieving a TPR >85\gt85% across all fold-changes requires nr>20n_r\gt20. For future RNA-seq experiments these results suggest nr>6n_r\gt6, rising to nr>12n_r\gt12 when identifying DGE irrespective of fold-change is important. For 6<nr<126 \lt n_r \lt 12, superior TPR makes edgeR the leading tool tested. For nr12n_r \ge12, minimizing false positives is more important and DESeq outperforms the other tools.Comment: 21 Pages and 4 Figures in main text. 9 Figures in Supplement attached to PDF. Revision to correct a minor error in the abstrac

    Reduced sensitivity for visual textures affects judgments of shape-from-shading and step climbing behaviour in older adults

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    Falls on stairs are a major hazard for older adults. Visual decline in normal aging can affect step climbing ability, altering gait and reducing toe clearance. Here we show that a loss of fine-grained visual information associated with age can affect the perception of surface undulations in patterned surfaces. We go on to show that such cues affect the limb trajectories of young adults, but due to their lack of sensitivity, not that of older adults. Interestingly neither the perceived height of a step nor conscious awareness are altered by our visual manipulation but stepping behaviour is: suggesting that the influence of shape perception on stepping behaviour is via the unconscious, action-centred, dorsal visual pathway

    Statistical models for RNA-seq data derived from a two-condition 48-replicate experiment

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    High-throughput RNA sequencing (RNA-seq) is now the standard method to determine differential gene expression. Identifying differentially expressed genes crucially depends on estimates of read count variability. These estimates are typically based on statistical models such as the negative binomial distribution, which is employed by the tools edgeR, DESeq and cuffdiff. Until now, the validity of these models has usually been tested on either low-replicate RNA-seq data or simulations. A 48-replicate RNA-seq experiment in yeast was performed and data tested against theoretical models. The observed gene read counts were consistent with both log-normal and negative binomial distributions, while the mean-variance relation followed the line of constant dispersion parameter of ~0.01. The high-replicate data also allowed for strict quality control and screening of bad replicates, which can drastically affect the gene read-count distribution. RNA-seq data have been submitted to ENA archive with project ID PRJEB5348.Comment: 15 pages 6 figure
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