89 research outputs found
Hydro-climatic projections_Sweden
No full textThe ensemble set consists of 16 available hydro-climatic (river flow (m3s-1), precipitation (mm), and temperature (oC)) projections for Sweden. It includes 3 different emission scenarios (A1B, B1 and A2), 5 GCMs (ECHAM5, ARPEGE, CCSM3, HadCM3Q and BCM), 6 RCMs (SMHI-RCA3, CNRM-ALADIN, KNMI-RACMO, MPI-REMO, HC-HadRM3, and DMI-HIRHAM), and two spatial resolutions (50 and 25 km). The results are provided for 1007 Swedish sub basins on a monthly, seasonal and annual scale. Different statistics (mean, 10th and 90th percentiles) are calculated and provided. The HBV model [Lindström, G., B. Johansson, M. Persson, M. Gardelin, and S. Bergström (1997), Development and test of the distributed HBV-96 hydrological model, J. Hydrol., 201, 272–288] was used to provide the hydrological projections. The results for the whole country of Sweden have been published in: Pechlivanidis, I.G., Gupta, H., and Bosshard, T. 2018. An information theory approach to identifying a representative subset of hydro-climatic simulations for impact modeling studies, Water Resources Research.</p
Massive feature extraction for explaining and foretelling hydroclimatic time series forecastability at the global scale
No full textStatistical analyses and descriptive characterizations are sometimes assumed to be offering information on time series forecastability. Despite the scientific interest suggested by such assumptions, the relationships between descriptive time series features (e.g., temporal dependence, entropy, seasonality, trend and linearity features) and actual time series forecastability (quantified by issuing and assessing forecasts for the past) are scarcely studied and quantified in the literature. In this work, we aim to fill in this gap by investigating such relationships, and the way that they can be exploited for understanding hydroclimatic forecastability and its patterns. To this end, we follow a systematic framework bringing together a variety of –mostly new for hydrology– concepts and methods, including 57 descriptive features and nine seasonal time series forecasting methods (i.e., one simple, five exponential smoothing, two state space and one automated autoregressive fractionally integrated moving average methods). We apply this framework to three global datasets originating from the larger Global Historical Climatology Network (GHCN) and Global Streamflow Indices and Metadata (GSIM) archives. As these datasets comprise over 13,000 monthly temperature, precipitation and river flow time series from several continents and hydroclimatic regimes, they allow us to provide trustable characterizations and interpretations of 12-month ahead hydroclimatic forecastability at the global scale. We first find that the exponential smoothing and state space methods for time series forecasting are rather equally efficient in identifying an upper limit of this forecastability in terms of Nash-Sutcliffe efficiency, while the simple method is shown to be mostly useful in identifying its lower limit. We then demonstrate that the assessed forecastability is strongly related to several descriptive features, including seasonality, entropy, (partial) autocorrelation, stability, (non)linearity, spikiness and heterogeneity features, among others. We further (i) show that, if such descriptive information is available for a monthly hydroclimatic time series, we can even foretell the quality of its future forecasts with a considerable degree of confidence, and (ii) rank the features according to their efficiency in explaining and foretelling forecastability. We believe that the obtained rankings are of key importance for understanding forecastability. Spatial forecastability patterns are also revealed through our experiments, with East Asia (Europe) being characterized by larger (smaller) monthly temperature time series forecastability and the Indian subcontinent (Australia) being characterized by larger (smaller) monthly precipitation time series forecastability, compared to other continental-scale regions, and less notable differences characterizing monthly river flow from continent to continent. A comprehensive interpretation of such patters through massive feature extraction and feature-based time series clustering is shown to be possible. Indeed, continental-scale regions characterized by different degrees of forecastability are also attributed to different clusters or mixtures of clusters (because of their essential differences in terms of descriptive features)
Leukocyte filtration of blood cardioplegia attenuates myocardial damage and inflammation.
No full textOBJECTIVES: Leukocyte filtration of blood cardioplegia (cLkF) is postulated to reduce ischaemia-reperfusion myocardial injury. Contradictory results have been published and few studies have addressed perioperative cytokine leakage and haemodynamic status after LkF.
METHODS: Thirty patients undergoing isolated aortic valve replacement were randomized to cLkF (cLkF-Group) or to standard cold blood cardioplegia (S-Group). Troponin I (TnI) and lactate were sampled from the coronary sinus at reperfusion. Peripheral TnI and lactate were collected preoperatively at admission, and in the intensive care unit (ICU) at 8, 12, 36 and 60 h postoperatively. Cardiac index (CI), indexed systemic vascular resistances, cardiac cycle efficiency (CCE) and central venous pressure (CVP) were registered preoperatively, at admission to the ICU and at the 6th, 12th, 18th, 24th and 36th postoperative hour. IL-6, IL-8, TNF-alpha and IL-10 were sampled preoperatively, at reperfusion, on admission to the ICU and the 6th, 18th and 24th postoperative hours.
RESULTS: The cLkF group showed lower TnI (2.4 ± 0.4 vs. 5.1 ± 0.8 μg/l, P = 0.0001) and lactate (0.9 ± 0.1 vs. 1.6 ± 0.2 mmol/l, P = 0.0001) from the coronary sinus at reperfusion. TnI levels (group-P = 0.0001, group time-P < 0.0001) and lactate (group time-P = 0.001) remained lower postoperatively after cLkF. Ventricular defibrillation at aortic declamping was less common in the cLkF-Group (33.3% vs. S-Group: 93.3%; P = 0.002). Cytokines demonstrated significant postoperative leakage (time-P = 0.0001 in both groups for IL-6, IL-8, TNF-alpha, IL-10), with lower pro-inflammatory (IL-6 group-P = 0.0001, group time-P = 0.0001; IL-8 group-P = 0.0001, group time-P = 0.007; TNF-alpha group-P = 0.0001; group time-P = 0.012) and higher anti-inflammatory cytokine secretion after cLkF (IL-10 group-P = 0.005). Perioperative haemodynamic indices proved to be similar between the two groups (group-P = NS for CI, SVRI, CCE and CVP).
CONCLUSIONS: cLkF during blood cardioplegia attenuates myocardial ischaemia/reperfusion injury and reduces perioperative leakage of TnI, lactate and pro-inflammatory cytokines. These data did not result in a better haemodynamic status
Repair of mitral valve prolapse through ePTFE Neochordae: A finite element approach from CMR
No full textPatient-specific finite element (FE) modeling is largely used to quantify mitral valve (MV) biomechanics associated to pathological and post-surgical conditions. We used this approach, integrated with non-invasive cardiac magnetic resonance (CMR) imaging data, to numerically perform the repair of the isolated mitral valve leaflet prolapse through expanded-polytetrafluoroethylene (ePTFE) sutures and quantitatively compare the effects of different techniques of neochordal implantation (NCI). CMR-derived FE models well reproduced MVP-related alterations and were able to assess the efficacy of each repairing technique and its biomechanical effects onMVapparatus; the quantification of biomechanical differences between NCI techniques, especially in terms of both chordal tensions and leaflet stresses redistribution, may impact on the short- and long-term the clinical outcome, potentially opening the way to patient-specific optimization of NCIs and, if extensively and successfully tested, improve surgical planning
Polarizing microplegia improves cardiac cycle efficiency after CABG for unstable angina
No full textMyocardial protection during coronary artery bypass grafting (CABG) for unstable angina (UA) still represents a major challenge, ought to the risk for further ischemia/reperfusion injury. Few studies investigate the biochemical, hemodynamic and echocardiographic results of microplegia (Mic) in UA.
Eighty UA-patients undergoing CABG were randomized to Mic (Mic-Group) or standard 4:1 blood Buckberg-cardioplegia (Buck-Group). Troponin-I and lactate were sampled from coronary sinus at reperfusion (T1), and from peripheral blood preoperatively (T0), at 6 (T2), 12 (T3) and 48 (T4) hours. Cardiac index (CI), indexed systemic vascular resistances (ISVR), Δp/Δt, cardiac cycle efficiency (CCE), and central venous pressure (CVP) were collected preoperatively (T0), and since Intensive Care Unit (ICU)-arrival (T1) to 24h (T5). Echocardiographic E-wave (E), A-wave (A), E/A, peak early-diastolic TDI-mitral annular-velocity (Ea), and E/Ea investigated the diastolic function and Wall Motion Score Index (WMSI) the systolic function, preoperatively (T0) and at 96h (T1).
Mic-Group showed lower troponin-I and lactate from coronary sinus (p=.0001 for both) and during the postoperative course (between-groups p=.001 and .0001, respectively). WMSI improved only after Mic (time-p=.001). Higher CI Δp/Δt and CCE (between-groups p=.0001), with comparable CVP and ISVR (p=N.S.) were detected after Mic. Diastolic function improved in both groups, but better after Mic (between-groups p=.003, .001, and .013 for E, E/A, and Ea, respectively). Mic resulted in lower transfusions (p=.006) and hospitalization (p=.002), and a trend towards lower need/duration of inotropes (p=.04 and p=.041, respectively), and ICU-stay (p=.015).
Microplegia attenuates myocardial damage in UA, reduces transfusions, improves postoperative systo-diastolic function, and shortens hospitalization
In which patients is transcatheter aortic valve replacement potentially better indicated than surgery for redo aortic valve disease? Long-term results of a 10-year surgical experience
No full textBackgroundRedo aortic valve replacement procedures have been reduced by the growing practice of trans-catheter aortic valve-in-valve procedures. We analyzed our long-term results of redo aortic valve replacement procedures during a 10-year period in an effort to define subgroups in which trans-catheter aortic valve-in-valve procedures may be better than surgery.MethodsFrom 2002 to 2010, 131 redo aortic valve replacement procedures with at least 18 months of follow-up were prospectively enrolled. Hospital and follow-up outcome of the entire population and of high-risk subgroups were evaluated.ResultsHospital mortality was 2.3%, major re-entry complications were seen in 1.5%, re-exploration for bleeding was seen in 9.2%, perioperative low cardiac output state (ie, low cardiac output syndrome) was seen in 9.9%, stroke was seen in 3.1%, prolonged ventilation was seen in 18.3%, pneumonia was seen in 4.6%, acute renal insufficiency was seen in 11.5%, intra-aortic counterpulsation (intra-aortic balloon pump) was seen in 9.2%, renal replacement therapy was seen in 4.6%, need for transfusions was seen in 60.3%, and permanent pacemaker implantation was seen in 2.3%. One hundred twenty-month actuarial survival, freedom from acute heart failure, reinterventions, stroke, and thromboembolisms were 61.5% ± 8.6%, 62.9% ± 6.9%, 97.8% ± 1.5%, 93.2% ± 3.0%, and 91.2% ± 3.2%, respectively. Patients aged >75 years had similar outcome to younger patients (nonsignificant P for all). Endocarditis resulted in higher hospital mortality (P = .034), low cardiac output state (P < .0001), intra-aortic balloon pump (P < .0001), prolonged ventilation (P = .011), pneumonia (P = .049), acute renal insufficiency (P = .004), lower actuarial survival (log-rank P = .0001), freedom from acute heart failure (P = .002), and re-intervention (P = .003). New York Heart Association functional class IV at admission resulted in a higher incidence of low cardiac output state (P < .0001), intra-aortic balloon pump (P = .0001), prolonged ventilation (P < .0001), pneumonia (P = .015), and a lower actuarial freedom from re-intervention (P = .0001). Higher need for permanent pacemaker implantation (P = .015) and lower freedom from acute heart failure (P = .019) emerged after urgencies/emergencies.ConclusionsRedo aortic valve replacement procedures achieves good results, especially in nonendocarditic or elective cases, and young or New York Heart Association functional class I/II patients. Indeed, endocarditis significantly affects outcome. New York Heart Association functional class IV and nonelective procedures might benefit from trans-catheter aortic valve-in-valve procedures
Fuzzy Postprocessing to Advance the Quality of Continental Seasonal Hydrological Forecasts for River Basin Management
No full text[EN] Streamflow forecasting services driven by seasonal meteorological forecasts from dynamic prediction systems deliver valuable information for decision-making in the water sector. Moving beyond the traditional river basin boundaries, large-scale hydrological models enable a coordinated, efficient, and harmonized anticipation and management of water-related risks (droughts, floods). However, the use of forecasts from such models at the river basin scale remains a challenge, depending on how the model reproduces the hydrological features of each particular river basin. Consequently, postprocessing of forecasts is a crucial step to ensure usefulness at the river basin scale. In this paper we present a methodology to postprocess seasonal streamflow forecasts from large-scale hydrological models and advance their quality for local applications. It consists of fuzzy logic systems that bias-adjust seasonal forecasts from a large-scale hydrological model by comparing its modeled streamflows with local observations. The methodology is demonstrated using forecasts from the pan-European hydrological model E-HYPE at the Jucar River basin (Spain). Fuzzy postprocessed forecasts are compared to postprocessed forecasts derived from a quantile mapping approach as a benchmark. Fuzzy postprocessing was able to provide skillful streamflow forecasts for the Jucar River basin, keeping most of the skill of raw E-HYPE forecasts and also outperforming quantile-mapping-based forecasts. The proposed methodology offers an efficient one-to-one mapping between large-scale modeled streamflows and basin-scale observations preserving its temporal dependence structure and can adapt its input set to increase the skill of postprocessed forecasts.This study was partially funded by the EU Horizon 2020 programme under the IMPREX research and innovation project (grant agreement no. 641.811), by the European Research Area for Climate Services programme (ER4CS) under the INNOVA project (Grant Agreement 690462), by the ADAPTAMED project (RTI2018-101483-B-I00) from the Ministerio de Ciencia, Innovacion Universidades (MICINN) of Spain, and by the postdoctoral program of Universitat Politecnica de Valencia (PAID 10-18). Funding was also received from the EU Horizon 2020 project S2S4E (Sub -seasonal to Seasonal forecasting for the Energy sector) under Grant Agreement 776787. This study was also partially funded by the EU Horizon 2020 project CLARA under the Grant Agreement 730482.Macian-Sorribes, H.; Pechlivanidis, I.; Crochemore, L.; Pulido-Velazquez, M. (2020). Fuzzy Postprocessing to Advance the Quality of Continental Seasonal Hydrological Forecasts for River Basin Management. Journal of Hydrometeorology. 21(10):2375-2389. https://doi.org/10.1175/JHM-D-19-0266.1S237523892110Abbaspour, K. C., Rouholahnejad, E., Vaghefi, S., Srinivasan, R., Yang, H., & Kløve, B. (2015). A continental-scale hydrology and water quality model for Europe: Calibration and uncertainty of a high-resolution large-scale SWAT model. Journal of Hydrology, 524, 733-752. doi:10.1016/j.jhydrol.2015.03.027Arnal, L., Ramos, M.-H., Coughlan de Perez, E., Cloke, H. L., Stephens, E., Wetterhall, F., … Pappenberger, F. (2016). Willingness-to-pay for a probabilistic flood forecast: a risk-based decision-making game. 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Experimental study of the effects of grass vegetation and gravel bed on the turbulent flow using particle image velocimetry
No full textLaboratory experiments are used to explore the effect of impermeable bed on the turbulent flow by using particle image velocimetry (PIV). The experiments were conducted in an open channel of 6.5 m length, 7.5 cm width and 25 cm height. Two different types of permeable bed (flexible vegetation with grass and gravel bed) with different height (2 and 6 cm) with the same porosity epsilon = 0.80 (volume of fluid over total porous medium volume) were used to represent the porous bed. These conditions can be commonly found in systems with sediment transport. Forty-eight (48) experiments were carried out for permeable beds, twenty-four (24) for flexible vegetation with grass and twenty-four (24) for gravel bed. Hydraulic characteristics such as distributions of velocities, turbulent intensities, turbulent kinetic energy and Reynolds stress are investigated. Measurements of velocity were taken for horizontal channel slope at different heights using the PIV. Results show that the kind of the bed type can significantly influence the turbulent characteristics of the flow
Transition from permeable to impermeable beds and vice versa in open channels: Effects on the velocity distribution of turbulent flow
No full textThis study investigates the impact of permeable to impermeable (and vice versa) bed transition on the velocity distribution of turbulent flow in an open channel. This experimental investigation is based on the 2D Particle Image Velocimetry (PIV) method, which allows data acquisition at fine spatial-temporal resolution. The experiments were conducted in a horizontal channel of 6.5 m length, 7.5 cm width, and 25 cm height. A grass-like vegetation of 2 cm height was used to represent a permeable bed, since these conditions are typical of flows encountered in sediment transport problems. In total, 36 experiments were carried out. The velocity is measured above the vegetation for the permeable bed and above the impermeable bed at three different discharges (0.735, 0.845 and 0.970 lt/s) and three different flow depths (4, 7 and 10 cm). The experiments were performed in four different locations of the channel (over the permeable bed, in the transition point from permeable to impermeable bed, over the impermeable bed, and in the transition point from impermeable bed to permeable bed). Results show that the velocity distribution in channels with transited permeable-impermeable beds (and vice versa) is different to distributions of velocity in solely permeable or impermeable channel beds. In particular, results show high sensitivity to the magnitude of discharge and total flow depth. © 2014 Taylor & Francis Group, London
Skill-informed seamless communication of European S2S hydrological forecasts
No full textInternational audienceSub-seasonal to seasonal (S2S) information holds significant socio-economic value for decision-makers relying on climate variability. While significant advancements have been made in S2S meteorological forecasting, skill variability among prediction systems persists due to differences in physical process representation and technical characteristics of the predictive systems. Traditionally, sub-seasonal systems are considered more informative than seasonal systems within their time horizons, leading to seamless communication approaches that combine systems at fixed horizons, overlooking tailored solutions to optimize forecast skill. This study investigates S2S streamflow forecasting skill across Europe’s diverse hydrological regimes, identifying optimal combination horizons for skill-informed seamless communication. Using bias-adjusted forecasts from ECMWF’s sub-seasonal (ENS-ER) and seasonal (SEAS5) systems, we evaluate streamflow forecasts to uncover spatiotemporal complementarities between the two systems. The results reveal that most European basins benefit from sub-seasonal forecasts up to 3 to 6 weeks ahead, while steep, snow-dominated mountain ranges, high-precipitation basins, and elevated Mediterranean areas exhibit shorter horizons of 2 to 4 weeks. Gains in meteorological forecast skill at short lead times (1 to 3 weeks) are amplified when translated into hydrological processes, extending predictability up to 6 weeks. ENS-ER-based forecasts demonstrate greater spatial homogeneity in skill during shorter lead times, while SEAS5-based forecasts excel at extended horizons. These findings highlight the potential for tailored seamless products to enhance S2S forecast utility. By integrating complementary S2S prediction systems with this diagnostic, region-dependent strategy tailored to diverse hydrological regimes, hydro-climate services can seamlessly deliver accurate, actionable, and operationally relevant information to water- and climate-dependent sectors
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