2,653 research outputs found

    A century of sea level data and the UK's 2013/14 storm surges: an assessment of extremes and clustering using the Newlyn tide gauge record

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    For the UK's longest and most complete sea level record (Newlyn), we assess extreme high waters and their temporal clustering; prompted by the 2013/2014 winter of storms and flooding. These are set into context against this almost 100-year record. We define annual periods for which storm activity and high sea levels can be compared on a year-by-year basis. Amongst the storms and high tides which affected Newlyn, the recent winter produced the largest recorded high water level (3 February 2014) and five other high water events above a 1 in 1-year return period. The large magnitude of tide and mean sea level, and the close inter-event spacings (of large return period high waters), suggests that the 2013/2014 extreme high water level "season" can be considered the most extreme on record. However, storm and sea level events may be classified in different ways. For example, in the context of sea level rise (which we calculate linearly as 1.81 ± 0.1 mm yr?1 from records between 1915 to 2014), a lower probability combination of surge and tide occurred on 29 January 1948, whilst the 1995/1996 storm surge season saw the most high waters of ? the 1 in 1-year return period. We provide a basic categorisation of the four types of extreme high water level cluster, ranging from consecutive tidal cycles to multiple years. The assessment is extended to other UK sites (with shorter sea level records and different tide-surge characteristics), which suggests 2013/2014 was particularly unusual. Further work will assess clustering mechanisms and flood system "memory"

    Simulation of direct source-to-drain tunnelling using the density gradient formalism: Non-Equilibrium Greens Function calibration

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    Quantum mechanical confinement effects, gate, hand-to-hand and source-to-drain tunnelling will dramatically affect the characteristics of future generation nanometre scaled devices. It has been demonstrated already that first-order quantum corrections, which satisfactorily describe quantum confinement effects, can be introduced into efficient TCAD orientated drift-diffusion simulators using the density gradient approach. In this paper we refer to Non-Equilibrium Green's Function simulations in order to calibrate the density gradient formalism in respect of both confinement and source-to-drain tunnelling using different effective masses in directions normal and parallel to the conducting channel. We demonstrate that the density gradient formalism can describe accurately the current characteristics in sub 20 nm double gate MOSFETs

    Early results after staged hybrid repair of thoracoabdominal aortic aneurysms

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    Advances in genome-wide RNAi cellular screens: a case study using the Drosophila JAK/STAT pathway

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    BACKGROUND: Genome-scale RNA-interference (RNAi) screens are becoming ever more common gene discovery tools. However, whilst every screen identifies interacting genes, less attention has been given to how factors such as library design and post-screening bioinformatics may be effecting the data generated. RESULTS: Here we present a new genome-wide RNAi screen of the Drosophila JAK/STAT signalling pathway undertaken in the Sheffield RNAi Screening Facility (SRSF). This screen was carried out using a second-generation, computationally optimised dsRNA library and analysed using current methods and bioinformatic tools. To examine advances in RNAi screening technology, we compare this screen to a biologically very similar screen undertaken in 2005 with a first-generation library. Both screens used the same cell line, reporters and experimental design, with the SRSF screen identifying 42 putative regulators of JAK/STAT signalling, 22 of which verified in a secondary screen and 16 verified with an independent probe design. Following reanalysis of the original screen data, comparisons of the two gene lists allows us to make estimates of false discovery rates in the SRSF data and to conduct an assessment of off-target effects (OTEs) associated with both libraries. We discuss the differences and similarities between the resulting data sets and examine the relative improvements in gene discovery protocols. CONCLUSIONS: Our work represents one of the first direct comparisons between first- and second-generation libraries and shows that modern library designs together with methodological advances have had a significant influence on genome-scale RNAi screens

    Assessment and comparison of extreme sea levels and waves during the 2013/2014 storm season in two UK coastal regions

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    The extreme sea levels and waves experienced around the UK's coast during the 2013/2014 winter caused extensive coastal flooding and damage. In such circumstances, coastal managers seek to place such extremes in relation to the anticipated standards of flood protection, and the long-term recovery of the natural system. In this context, return periods are often used as a form of guidance. We therefore provide these levels for the winter storms, as well as discussing their application to the given data sets and case studies (two UK case study sites: Sefton, northwest England; and Suffolk, east England). We use tide gauge records and wave buoy data to compare the 2013/2014 storms with return periods from a national dataset, and also generate joint probabilities of sea level and waves, incorporating the recent events. The UK was hit at a national scale by the 2013/2014 storms, although the return periods differ with location. We also note that the 2013/2014 high water and waves were extreme due to the number of events, as well as the extremity of the 5 December 2013 "Xaver" storm, which had a very high return period at both case study sites. Our return period analysis shows that the national scale impact of this event is due to its coincidence with spring high tide at multiple locations as the tide and storm propagated across the continental shelf. Given that this event is such an outlier in the joint probability analyses of these observed data sets, and that the season saw several events in close succession, coastal defences appear to have provided a good level of protection. This type of assessment should be recorded alongside details of defence performance and upgrade, with other variables (e.g. river levels at estuarine locations) included and appropriate offsetting for linear trends (e.g. mean sea level rise) so that the storm-driven component of coastal flood events can be determined. Local offsetting of the mean trends in sea level allows long-term comparison of storm severity and also enables an assessment of how sea level rise is influencing return levels over time, which is important when considering long-term coastal resilience in strategic management plans

    Management and drivers of change of pollinating insects and pollination services. National Pollinator Strategy: for bees and other pollinators in England, Evidence statements and Summary of Evidence

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    These Evidence Statements provide up-to-date information on what is known (and not known) about the status, values, drivers of change, and responses to management of UK insect pollinators (as was September 2018). This document has been produced to inform the development of England pollinator policy, and provide insight into the evidence that underpins policy decision-making. This document sits alongside a more detailed Summary of Evidence (Annex I) document written by pollinator experts. For information on the development of the statements, and confidence ratings assigned to them, please see section ?Generation of the statements? below. Citations for these statements are contained in the Summary of Evidence document

    Assessment and comparison of extreme sea levels and waves during the 2013/14 storm season in two UK coastal regions

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    The extreme sea levels and waves experienced around the UK's coast during the 2013/14 winter caused extensive coastal flooding and damage. Coastal managers seek to place such extremes in relation to the anticipated standards of flood protection, and the long-term recovery of the natural system. In this context, return periods are often used as a form of guidance. This paper provides these levels for the winter storms, and discusses their application to the given data sets for two UK case study sites: Sefton, northwest England, and Suffolk, east England. Tide gauge records and wave buoy data were used to compare the 2013/14 storms with return periods from a national data set, and also joint probabilities of sea level and wave heights were generated, incorporating the recent events. The 2013/14 high waters and waves were extreme due to the number of events, as well as the extremity of the 5 December 2013 "Xaver" storm, which had a high return period at both case study sites. The national-scale impact of this event was due to its coincidence with spring high tide at multiple locations. Given that this event is such an outlier in the joint probability analyses of these observed data sets, and that the season saw several events in close succession, coastal defences appear to have provided a good level of protection. This type of assessment could in the future be recorded alongside defence performance and upgrade. Ideally other variables (e.g. river levels at estuarine locations) would also be included, and with appropriate offsetting for local trends (e.g. mean sea-level rise) so that the storm-driven component of coastal flood events can be determined. This could allow long-term comparison of storm severity, and an assessment of how sea-level rise influences return levels over time, which is important for consideration of coastal resilience in strategic management plans

    Key myths about corruption (Briefing Paper)

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    Corruption has been one of the major international concerns of the past decade. It is an issue that affects all countries, rich and poor, in different ways and to differing degrees. Exactly how corruption affects particular societies has, however, been the subject of some discussion in the literature. The major international institutions promoting governance reforms have, for example, persistently argued that corruption has a direct negative impact upon overall economic growth levels and can depress the climate for attracting international investment; although these are far from universally-held assumptions, even in the mainstream economics literature. Amidst heightened international concern for tackling the abject poverty which continues to affect such large sections of humanity (expressed most clearly in the evolution of the millennium development goals or MDGs), perhaps the most important concern that has been expressed about corruption is that it disproportionately affects the poor and marginalized, through excluding them from access to services or reducing the funds available for direct use in social programmes. Donor-country fears over corruption in the handling of development aid monies may also act to erode the political will necessary to ensure adequate international funding of the actions needed to meet MDG targets, whilst within Southern countries perceptions of widespread corruption within political life can act decisively to depress popular support for state reforms and/or open democratic political systems. Clearly, then, corruption – its extent, nature, dynamics, causation and how it might be tackled – is an issue of fundamental importance to those working in the field of international development. One of the things noticeable on a first exploration of the literature on corruption and development is the singular lack of attention that was devoted to the issue for most of the period since the second world war and, in turn, the sudden rediscovery of the issue towards the end of the 1980s and the explosion of international legislative initiatives, institutional formation and academic work that has occurred since then. Clearly, the end of the bipolar geopolitical world of the cold war and the onslaught of contemporary globalization appear to have presented considerable opportunities for international collaboration in placing the issue at the centre of the international stage. Nevertheless, those very same global processes also present Preliminary version – not for citation without the permission of the authors important challenges to the international community in dealing with the issue because of the difficulties involved in tracing international flows of capital, the increasing complexity of international criminal networks and non-criminal tax evasion networks and the complex and hazy lines between the private and public sectors. Since the early 1990s large amounts of public money have been spent on the development of new legislation at national and international levels, the creation of national anti-corruption programmes and the evolution of anticorruption departments within just about every major international development institution. The impact of such measures, however, has been, at best, partial. As such, whilst the international community should continue to do what it can to raise the international profile of corruption and how it might be better combatted, we argue that it is even more important that a more detailed independent assessment of the effectiveness of existing interventions is carried out. Our position is that the first steps towards such a review of international anticorruption initiatives must involve subjecting the ways in which the issue has been constructed in the mainstream development arenas to closer scrutiny. This workshop is intended to be a first step in this direction. As such, this paper is intended to generate debate about the meaning of corruption, its complexity, how it relates to particular areas of development policy intervention and the means whereby it might be combated (if indeed this is considered feasible or even desirable). Given this, what follows is (i) deliberately provocative, (ii) deliberately broad and (iii) deliberately polemical. We thought long and hard about how best to organize this session and in the end decided to organize it around the presentation of a series of key myths which we have identified as important amongst those involved in anticorruption activities and research. Some of these myths relate to the academic community, some to a kind of general common sense amongst development practitioners and some to those involved in the implementation of anti-corruption initiatives. Here, they are organized into four broad sections dealing with (a) basic definitions, (b) states and markets, (c) actors and anticorruption initiatives and (d) economic factors

    Search for Electronic Recoil Event Rate Modulation with 4 Years of XENON100 Data

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    We report on a search for electronic recoil event rate modulation signatures in the XENON100 data accumulated over a period of 4 yr, from January 2010 to January 2014. A profile likelihood method, which incorporates the stability of the XENON100 detector and the known electronic recoil background model, is used to quantify the significance of periodicity in the time distribution of events. There is a weak modulation signature at a period of 431-14+16 day in the low energy region of (2.0-5.8) keV in the single scatter event sample, with a global significance of 1.9σ; however, no other more significant modulation is observed. The significance of an annual modulation signature drops from 2.8σ, from a previous analysis of a subset of this data, to 1.8σ with all data combined. Single scatter events in the low energy region are thus used to exclude the DAMA/LIBRA annual modulation as being due to dark matter electron interactions via axial vector coupling at 5.7σ

    Constraining the Spin-Dependent WIMP-Nucleon Cross Sections with XENON1T

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    We report the first experimental results on spin-dependent elastic weakly interacting massive particle (WIMP) nucleon scattering from the XENON1T dark matter search experiment. The analysis uses the full ton year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only cases. No significant signal excess is observed, and a profile likelihood ratio analysis is used to set exclusion limits on the WIMP-nucleon interactions. This includes the most stringent constraint to date on the WIMP-neutron cross section, with a minimum of 6.3 × 10−42 cm2 at 30 GeV/c2 and 90% confidence level. The results are compared with those from collider searches and used to exclude new parameter space in an isoscalar theory with an axial-vector mediator
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