Search results for "conduit"

Ground deformation reveals the scale-invariant conduit dynamics driving explosive basaltic eruptions

2021

The mild activity of basaltic volcanoes is punctuated by violent explosive eruptions that occur without obvious precursors. Modelling the source processes of these sudden blasts is challenging. Here, we use two decades of ground deformation (tilt) records from Stromboli volcano to shed light, with unprecedented detail, on the short-term (minute-scale) conduit processes that drive such violent volcanic eruptions. We find that explosive eruptions, with source parameters spanning seven orders of magnitude, all share a common pre-blast ground inflation trend. We explain this exponential inflation using a model in which pressure build-up is caused by the rapid expansion of volatile-rich magma ri…

Sustaining persistent lava lakes: Observations from high-resolution gas measurements at Villarrica volcano, Chile

2016

International audience; Active lava lakes – as the exposed upper part of magmatic columns – are prime locations to investigate the conduit flow processes operating at active, degassing volcanoes. Persistent lava lakes require a constant influx of heat to sustain a molten state at the Earth's surface. Several mechanisms have been proposed to explain how such heat transfer can operate efficiently. These models make contrasting predictions with respect to the flow dynamics in volcanic conduits and should result in dissimilar volatile emissions at the surface. Here we look at high-frequency SO2 fluxes, plume composition, thermal emissions and aerial video footage from the Villarrica lava lake i…

Combined ground and aerial measurements resolve vent-specific gas fluxes from a multi-vent volcano

2020

Volcanoes with multiple summit vents present a methodological challenge for determining vent-specific gas emissions. Here, using a novel approach combining multiple ultraviolet cameras with synchronous aerial measurements, we calculate vent-specific gas compositions and fluxes for Stromboli volcano. Emissions from vent areas are spatially heterogeneous in composition and emission rate, with the central vent area dominating passive emissions, despite exhibiting the least explosive behaviour. Vents exhibiting Strombolian explosions emit low to negligible passive fluxes and are CO2-dominated, even during passive degassing. We propose a model for the conduit system based on contrasting rheologi…

The Fontan-Operation: From Intra- to Extracardiac Procedure

2003

Purpose For treatment of univentricular heart, the Fontan operation has been established as the definitive palliation. The current controversy is mainly based on the high incidence of arrhythmias after an intra-atrial lateral tunnel Fontan operation. Methods From January 1995 until April 2002. 46 children underwent a Fontan-type operation with or without a small fenestration. In 33 patients (group I) an Intracardiac tunnel and in 13 patients (group II) an extracardiac conduit procedure was performed. Principal findings There was no perioperative mortality. All patients showed postoperative a significant increase of arterial oxygen saturation, from 76 to 86% after surgery with fenestration, …

Observations of time-based measures of flow-mediated dilation of forearm conduit arteries: implications for the accurate assessment of endothelial fu…

2010

Endothelium-dependent flow-mediated dilation (FMD) is measured as the increase in diameter of a conduit artery in response to reactive hyperemia, assessed either at a fixed time point [usually 60-s post-cuff deflation (FMD60)] or as the maximal dilation during a 5-min continuous, ECG-gated, measurement (FMDmax-cont). Preliminary evidence suggests that the time between reactive hyperemia and peak dilation (time to FMDmax) may provide an additional index of endothelial health. We measured FMDmax-cont, FMD60, and time to FMDmax in 30 young healthy volunteers, 22 healthy middle-aged adults, 16 smokers, 23 patients with hypertension, 40 patients with coronary artery disease, and 22 patients wit…

Conversion from colonic conduit into recto-sigmoid pouch (Mainz pouch II)

2005

The Mainz Pouch II has now been used widely and found to be a valuable addition to the various types of urinary diversion. The authors from Mainz describe how a colonic conduit can be converted into a Mainz Pouch II, and the expected outcome from such a procedure. OBJECTIVE To report our long-term results of conversion from conduit conversion into a continent anal urinary diversion, as after conduit urinary diversion in childhood, some patients wish to have a later conversion to a continent diversion to avoid external appliances and to improve their quality of life. PATIENTS AND METHODS Between 1992 and 2003, 139 patients had a urinary diversion with a recto-sigmoid pouch (Mainz pouch II), …

Colonic Conduit in Children

1996

Complication rates of up to 86.6% have been reported after creation of an ileal conduit. In contrast to others, we construct an antirefluxing isoperistaltic colonic for incontinent diversion in children.Between 1968 and 1989 a colonic conduit was created in 105 patients up to age 20 years for neurogenic bladder (76), bladder exstrophy (16) and other reasons (13). Long-term followup (minimum 5 years, mean 16.3 years, range 5 to 26) was possible in 84 patients (159 renal units).Early and late stenosis at the ureterocolic anastomosis, and stomal stenosis occurred in 7.6 and 15.5% of the cases, respectively. Renal calculi developed in 8.2% of the renal units. Eight kidneys without function afte…

Quality of life following urinary diversion: Orthotopic ileal neobladder versus ileal conduit. A multicentre study among long-term, female bladder ca…

2019

Abstract Introduction Women undergoing radical cystectomy (RC) followed by urinary diversion (UD) for bladder cancer experience a substantial reduction in health-related quality of life (HRQOL). At present, studies comparing long-term QOL outcomes for different UD methods, needed to inform evidence-based choices of bladder reconstruction for female patients, are sparse. Our objective was to compare two common UD methods in terms of their HRQOL outcomes in women. Materials and methods We retrospectively analysed HRQOL in 73 consecutive female bladder cancer patients having undergone orthotopic ileal neobladder (IONB, N = 24) or ileal conduit (IC, N = 49) following RC between 2007 and 2013 in…

Indocyanine Green to Assess Vascularity of Ileal Conduit Anastomosis During Pelvic Exenteration for Recurrent/Persistent Gynecological Cancer: A Pilo…

2021

IntroductionPelvic exenteration performed for recurrent/persistent gynecological malignancies has been associated with urological short- and long-term morbidity due to altered vascularization of tissues for previous radiotherapy. The aims of the present study were to describe the use of intravenous indocyanine green (ICG) to assess vascularity of urinary diversion (UD) after pelvic exenteration for gynecologic cancers, to evaluate the feasibility and safety of this technique, and to assess the postoperative complications.MethodsProspective, observational, single-center, pilot study including consecutive patients undergoing anterior or total pelvic exenteration due to persistent/recurrent gy…

2017

Strombolian volcanism is a ubiquitous form of activity, driven by the ascent and bursting of bubbles of slug morphology. Whilst considerable attention has been devoted to understanding the behaviour of individual slugs in this regime, relatively little is known about how inter-slug interactions modify flow conditions. Recently, we reported on high temporal frequency strombolian activity on Etna, in which the larger erupted slug masses were followed by longer intervals before the following explosion than the smaller bursts (Pering et al., 2015). We hypothesised that this behaviour arose from the coalescence of ascending slugs causing a prolonged lag before arrival of the next distinct bubble…