Detailed landfill leachate plume mapping using 2D and 3D electrical resistivity tomography - with correlation to ionic strength measured in screens

Leaching of organic and inorganic contamination from landfills is a serious environmental problem as surface water and aquifers are affected. In order to assess these risks and investigate the migration of leachate from the landfill, 2D and large scale 3D electrical resistivity tomography were used at a heavily contaminated landfill in Grindsted, Denmark. The inverted 2D profiles describe both the variations along the groundwater flow as well as the plume extension across the flow directions. The 3D inversion model shows the variability in the low resistivity anomaly pattern corresponding to differences in the ionic strength of the landfill leachate. Chemical data from boreholes agree well with the observations indicating a leachate plume which gradually sinks and increases in size while migrating from the landfill in the groundwater flow direction. Overall results show that the resistivity method has been very successful in delineating the landfill leachate plume and that good correlation exists between the resistivity model and leachate ionic strength

Permeability estimation directly from logging-while-drilling Induced Polarization data

n this study, we present the prediction of permeability from time domain spectral induced polarization (IP) data, measured in boreholes on undisturbed formations using the El-log logging-while-drilling technique. We collected El-log data and hydraulic properties on unconsolidated Quaternary and Miocene deposits in boreholes at three locations at a field site in Denmark, characterized by different electrical water conductivity and chemistry. The high vertical resolution of the El-log technique matches the lithological variability at the site, minimizing ambiguity in the interpretation originating from resolution issues. The permeability values were computed from IP data using a laboratory-derived empirical relationship presented in a recent study for saturated unconsolidated sediments, without any further calibration. A very good correlation, within 1 order of magnitude, was found between the IP-derived permeability estimates and those derived using grain size analyses and slug tests, with similar depth trends and permeability contrasts. Furthermore, the effect of water conductivity on the IP-derived permeability estimations was found negligible in comparison to the permeability uncertainties estimated from the inversion and the laboratory-derived empirical relationship

Subsurface imaging of water electrical conductivity, hydraulic permeability and lithology at contaminated sites by induced polarization

At contaminated sites, knowledge about geology and hydraulic properties of the subsurface and extent of the contamination is needed for assessing the risk and for designing potential site remediation. In this study, we have developed a new approach for characterizing contaminated sites through time-domain spectral induced polarization. The new approach is based on: (1) spectral inversion of the induced polarization data through a reparametrization of the Cole-Cole model, which disentangles the electrolytic bulk conductivity from the surface conductivity for delineating the contamination plume; (2) estimation of hydraulic permeability directly from the inverted parameters using a laboratory-derived empirical equation without any calibration; (3) the use of the geophysical imaging results for supporting the geological modelling and planning of drilling campaigns. The new approach was tested on a data set from the Grindsted stream (Denmark), where contaminated groundwater from a factory site discharges to the stream. Two overlapping areas were covered with seven parallel 2-D profiles each, one large area of 410 m 790m(5melectrode spacing) and one detailed area of 126m 742m(2melectrode spacing). The geophysical results were complemented and validated by an extensive set of hydrologic and geologic information, including 94 estimates of hydraulic permeability obtained from slug tests and grain size analyses, 89 measurements of water electrical conductivity in groundwater, and four geological logs. On average the IP-derived and measured permeability values agreed within one order of magnitude, except for those close to boundaries between lithological layers (e.g. between sand and clay), where mismatches occurred due to the lack of vertical resolution in the geophysical imaging. An average formation factor was estimated from the correlation between the imaged bulk conductivity values and the water conductivity values measured in groundwater, in order to convert the imaging results from bulk conductivity to water conductivity. The geophysical models were actively used for supporting the geological modelling and the imaging of hydraulic permeability andwater conductivity allowed for a better discrimination of the clay/lignite lithology from the porewater conductivity. Furthermore, high water electrical conductivity values were found in a deep confined aquifer, which is separated by a low-permeability clay layer from a shallow aquifer. No contamination was expected in this part of the confined aquifer, and confirmation wells were drilled in the zone of increased water electrical conductivity derived from the geophysical results.Water samples from the new wells showed elevated concentrations of inorganic compounds responsible for the increased water electrical conductivity in the confined aquifer and high concentrations of xenobiotic organic contaminants such as chlorinated ethenes, sulfonamides and barbiturates

Methods for evaluating endothelial function: a position statement from the European Society of Cardiology Working Group on Peripheral Circulation

The endothelium holds a pivotal role in cardiovascular health and disease. Assessment of its function was until recently limited to experimental designs due to its location. The advent of novel techniques has facilitated testing on a more detailed basis, with focus on distinct pathways. This review presents available in-vivo and ex-vivo methods for evaluating endothelial function with special focus on more recent ones. The diagnostic modalities covered include assessment of epicardial and microvascular coronary endothelial function, local vasodilation by venous occlusion plethysmography and flow-mediated dilatation, arterial pulse wave analysis and pulse amplitude tonometry, microvascular blood flow by laser Doppler flowmetry, biochemical markers and bioassays, measurement of endothelial-derived microparticles and progenitor cells, and glycocalyx measurements. Insights and practical information on the theoretical basis, methodological aspects, and clinical application in various disease states are discussed. The ability of these methods to detect endothelial dysfunction before overt cardiovascular disease manifests make them attractive clinical tools for prevention and rehabilitation

HAS-1 genetic polymorphism in sporadic abdominal aortic aneurysm

The hyaluronan synthase 1 (HAS-1) gene encodes a plasma membrane protein that synthesizes hyaluronan (HA), an extracellular matrix molecule. Accumulating evidence emphasizes the relevance of HA metabolism in an increasing number of processes of clinical interest, including abdominal aortic aneurysm (AAA). The existence of aberrant splicing variants of the HAS-1 gene could partly explain the altered extracellular matrix architecture and influence various biological functions, resulting in progressive arterial wall failure in the development of AAA. In the present study, we assessed the hypothesis that HAS-1 genetic 833A/G polymorphism could be associated with the risk of AAA by performing a case-control association study, involving AAA patients and healthy matched donors

The management of acute venous thromboembolism in clinical practice. Results from the European PREFER in VTE Registry

Venous thromboembolism (VTE) is a significant cause of morbidity and mortality in Europe. Data from real-world registries are necessary, as clinical trials do not represent the full spectrum of VTE patients seen in clinical practice. We aimed to document the epidemiology, management and outcomes of VTE using data from a large, observational database. PREFER in VTE was an international, non-interventional disease registry conducted between January 2013 and July 2015 in primary and secondary care across seven European countries. Consecutive patients with acute VTE were documented and followed up over 12 months. PREFER in VTE included 3,455 patients with a mean age of 60.8 ± 17.0 years. Overall, 53.0 % were male. The majority of patients were assessed in the hospital setting as inpatients or outpatients (78.5 %). The diagnosis was deep-vein thrombosis (DVT) in 59.5 % and pulmonary embolism (PE) in 40.5 %. The most common comorbidities were the various types of cardiovascular disease (excluding hypertension; 45.5 %), hypertension (42.3 %) and dyslipidaemia (21.1 %). Following the index VTE, a large proportion of patients received initial therapy with heparin (73.2 %), almost half received a vitamin K antagonist (48.7 %) and nearly a quarter received a DOAC (24.5 %). Almost a quarter of all presentations were for recurrent VTE, with >80 % of previous episodes having occurred more than 12 months prior to baseline. In conclusion, PREFER in VTE has provided contemporary insights into VTE patients and their real-world management, including their baseline characteristics, risk factors, disease history, symptoms and signs, initial therapy and outcomes

COMPARISON OF TWO RADIO-FREQUENCY BASED ULTRASOUND SYSTEMS FOR ASSESSMENT OF CAROTID STIFFNESS

Objective: Measurement of arterial stiffness is becoming widely used for assessing cardiovascular risk and target organ damage. Two commercially available ultrasound systems (QAS, Esaote, Italy and eTracking, Aloka, Japan) provide radio-frequency (RF)-based tracking of carotid wall, thus allowing automatic accurate real-time determination of vessel diameter and distension, and subsequent calculation of indices of carotid stiffness. The measurement is performed in a single line by eTracking and in 16 equidistant lines within the region of interest by QAS. Aim of the present study was to evaluate whether the measures of carotid stiffness obtained by the two systems are interchangeable, and to assess the intra- and inter-operator variability of acquisitions. Design and methods: In the same session, MyLab 70 (Esaote, Italy) and Alpha 7 (Aloka, Japan) were used in random order to measure (2 cm before the flow divider) right common carotid artery (CCA) diameter and distension, and to calculate beta-index (Beta) in 104 subjects divided into 4 groups: 24 healthy controls (NL, age 32±7 yy), 24 prehypertensive subjects (PHBP, age 50±10 yy), 26 hypertensive patients (HBP, age 57±10 yy) and 27 type 2 diabetic patients (DM, age 62±6 yy). In 30 subjects, the second acquisition was performed after a 60-minute interval, both by the same operator and by a second operator. The reported values represent a mean of 3 measurements. Results: Brachial BP was similar during the acquisition with QAS and eTracking (p0.94), and the correlation between the two systems for CCA distension and Beta was high (r0.94 and 0.90, respectively,......

Incidence of peripheral vascular complications in subjects undergoing coronary angioplasty

The peripheral vascular complications following cardiac catheterization for interventional procedures are increasing. The aim of our study is to evaluate the importance of the early removal of the arterial sheath in reducing vascular complications. We examined 451 consecutive patients, submitted to percutaneous transluminal coronary angioplasty (PTCA) by femoral approach. In 229 patients (Group A), we removed the arterial sheath 12-14 hours after PTCA; in 222 patients (Group B) the arterial sheath was removed as soon as possible at the end of PTCA. In 31 Group A and 5 Group B patients we performed a coronarographic study after 12-14 hours. In total, 16 patients (11 Group A, 5 Group B) presented vascular complications. None of the risk factors that we have considered was predictive for complications, except that iliacofemoral atherosclerotic disease. In patients undergoing complex procedures we have found a greater amount of vascular complications. The coronarographic control revealed some pathologic lesion (dissection, occlusive thrombus) only in patients with clear ischemic signs or symptoms, both in Group A and B. In our opinion, an early removal of the arterial sheath reduces the incidence of vascular complications and the period of in-hospital stay