20 research outputs found

    Extreme value analysis of decadal variations in storm surge elevations

    No full text
    We use a novel statistical approach to analyse changes in the occurrence and severity of storm surge events in the southern and central North Sea over the period 1955-2000, using 1) output from a numerical storm surge model and 2) in situ data on surge levels at sites for which sufficiently long observational records are available. The methodology provides a robust diagnostic tool for assessing the ability of models to reproduce the observed characteristics of storm surges, in a fashion that properly accounts both for variability within a single long run of the model and for recording error in observational data on sea levels. The model re-analysis data show strong positive trends in the frequency and severity of storm surge events at locations in the north-eastern North Sea, whilst trends at locations in the southern and western North Sea appear to be dominated by decadal variability. Trends in in situ data for sites along the North Sea coast are fairly synchronous with corresponding trends in the model re-analysis data, with the most serious discrepancies attributable to known problems in the observational record

    Trend estimation in extremes of synthetic North Sea surges

    No full text
    Mechanistic models for complex atmospheric and hydrological processes are often used to simulate extreme natural events, usually to quantify the risks that are associated with these events. We use novel extreme value methods to analyse the statistical properties of output from a numerical storm surge model for the North Sea. The 'model data' constitute a reconstruction of the storm surge climate for the period 1955-2000 based on a high quality meteorological data set and constitute the only available source of information on surge elevations at offshore and unmonitored coastal locations over this period. Previous studies have used extreme value methods to analyse storm surge characteristics, but we can extend and improve on these analyses by using a local likelihood approach to provide a non-parametric description of temporal and spatial variations in the magnitude and frequency of storm surge event

    Anaemia among patients with heart failure and preserved or reduced ejection fraction: results from the SENIORS study

    No full text
    AIMS: Anaemia is a co-morbidity frequently seen in patients with heart failure (HF) and reduced left ventricular ejection fraction (LVEF). Its presence carries adverse prognostic effects. The effects of anaemia have not been extensively investigated in patients with preserved or only mildly reduced LVEF. We sought to investigate prevalence and incidence of anaemia in patients with HF irrespective of whether reduced or preserved ejection fraction are present. In addition, we sought to study the effects of nebivolol on the development of anaemia. METHODS AND RESULTS: We analysed data from 2069 patients randomized to nebivolol or placebo in the SENIORS study, 391 (10.0%) of whom were anaemic. Anaemia was similarly common in patients with LVEF=35% and those with LVEF>35% (19.0 vs. 18.7%, P= 0.89). Anaemic patients were older, had lower diastolic blood pressure, and worse kidney function (all P35%: HR 1.47, 95% CI 1.09-2.00, P= 0.012]. After multivariable adjustment, haemoglobin remained an independent predictor of the primary outcome in this cohort of patients (HR 0.94 per 1 g/dL increase, 95% CI 0.89-0.99, P= 0.017). CONCLUSIONS: Anaemia is an independent predictor of death or hospitalization for cardiovascular reasons among elderly patients with chronic HF and reduced or preserved/mildly reduced LVEF. Nebivolol does not affect haemoglobin values during follow-up
    corecore