Search results for "ABLATION"
showing 10 items of 322 documents
Laser fluence, repetition rate and pulse duration effects on paint ablation
2006
Abstract The efficiency (mm3/(J pulse)) of laser ablation of paint was investigated with nanosecond pulsed Nd:YAG lasers (λ = 532 nm) as a function of the following laser beam parameters: pulse repetition rate (1–10,000 Hz), laser fluence (0.1–5 J/cm2) and pulse duration (5 ns and 100 ns). In our study, the best ablation efficiency (η ≅ 0.3 mm3/J) was obtained with the highest repetition rate (10 kHz) at the fluence F = 1.5 J/cm2. This ablation efficiency can be associated with heat accumulation at high repetition rate, which leads to the ablation threshold decrease. Despite the low thermal diffusivity and the low optical absorption of the paint (thermal confinement regime), the ablation th…
MAGNETIC RESONANCE IMAGING–GUIDED FOCUSED ULTRASOUND THALAMOTOMY IN PATIENT WITH TREMOR COMBINED WITH PARKINSONISM: RETREATMENT AFTER BENEFIT DECAY
2019
Background In recent years, transcranial Magnetic Resonance-guided Focused UltraSounds (tcMRgFUS) treatments for functional neurological disorders are giving a new thrust to the field of therapeutic brain lesioning. This technique has been proven safe and effective in selected patients. Here we present the case of a patient affected by tremor combined with parkinsonism who underwent a second tcMRgFUS thalamotomy because of relapsing tremor after a few months from the first tcMRgFUS treatment. Materials and Methods A 72-year-old, right-handed man, who came to our observation because of a disabling tremor affecting mainly his upper right limb and refusing any invasive surgical procedure. His …
Design, characterization, and first field deployment of a novel aircraft-based aerosol mass spectrometer combining the laser ablation and flash vapor…
2021
In this paper, we present the design, development, and characteristics of the novel aerosol mass spectrometer ERICA (ERC Instrument for Chemical composition of Aerosols; ERC – European Research Council) and selected results from the first airborne field deployment. The instrument combines two well-established methods of real-time in situ measurements of fine particle chemical composition. The first method is the laser desorption and ionization technique, or laser ablation technique, for single-particle mass spectrometry (here with a frequency-quadrupled Nd:YAG laser at λ = 266 nm). The second method is a combination of thermal particle desorption, also called flash vaporization, and electro…
Simplified Electrophysiology Modeling Framework to Assess Ventricular Arrhythmia Risk in Infarcted Patients
2021
Patients that have suffered a myocardial infarction are at lifetime high risk for sudden cardiac death (SCD). Personalized 3D computational modeling and simulation can help to find non-invasively arrhythmogenic features of patients’ infarcts, and to provide additional information for stratification and planning of radiofrequency ablation (RFA). Currently, multiscale biophysical models require high computational resources and long simulations times, which make them impractical for clinical environments. In this paper, we develop a phenomenological solver based on cellular automata to simulate cardiac electrophysiology, with results comparable to those of biophysical models. The solver can ru…
Analysis of paper by laser-induced plasma spectroscopy
2001
Abstract Material distributions in paper and paper coatings are important factors which determine the characteristics and quality of paper. We have used laser-induced plasma spectroscopy (LIPS) to determine various properties of coated and uncoated papers. Depth profiles of double coated papers were determined. Microscopic variations of pigments in a double-coated paper were analyzed. It was observed, that the two coating layers can be distinguished, if they differ enough in composition. Filler distributions of uncoated copier papers were determined. The surface of the paper was studied for five samples containing different amounts of binder in the coating. Lateral contamination in paper an…
What the interventionalist should know about renal denervation in hypertensive patients: a position paper by the ESH WG on the interventional treatme…
2014
Percutaneous catheter-based transluminal renal denervation (RDN) has emerged as a new approach to achieve sustained blood pressure reduction in patients with drug-resistant hypertension. Experts from ESH and ESC in their recently released position papers and consensus document have summarised the current evidence, unmet needs and practical recommendations for the application of this therapeutic strategy in clinical practice. Experts of the ESH Working Group for the interventional treatment of hypertension prepared this position paper in order to provide interventionalists with guidance through the procedure of RDN. Given that there is no established intraprocedural control of ablation succe…
Deviation from threshold model in ultrafast laser ablation of graphene at sub-micron scale
2015
International audience; We investigate a method to measure ultrafast laser ablation threshold with respect to spot size. We use structured complex beams to generate a pattern of craters in CVD graphene with a single laser pulse. A direct comparison between beam profile and SEM characterization allows us to determine the dependence of ablation probability on spot-size, for crater diameters ranging between 700 nm and 2.5 μm. We report a drastic decrease of ablation probability when the crater diameter is below 1 μm which we interpret in terms of free-carrier diffusion.
Pattern of macrovascular invasion in hepatocellular carcinoma
2021
Background and aims: In patients with hepatocellular carcinoma (HCC), macrovascular invasion (MaVI) limits treatment options and decreases survival. Detailed data on the relationship between MaVI extension and patients' characteristics, and its impact on patients' outcome are limited. We evaluated the prevalence and extension of MaVI in a large cohort of consecutive HCC patients, analysing its association with liver disease and tumour characteristics, as well as with treatments performed and patients' survival. Methods: We analysed data of 4774 patients diagnosed with HCC recorded in the Italian Liver Cancer (ITA.LI.CA) database (2008-2018). Recursive partition analysis (RPA) was performed …
Analyse et détection des électrogrammes complexes fractionnés en vue de soigner la fibrillation auriculaire à l'aide de techniques d'ablation par rad…
2013
This manuscript presents research on the analysis and the detection of Complex Fractionated Atrial Electrograms (CFAE). In the first part, following a presentation over Atrial Fibrillation (AF) mechanisms and bioelectrical signals, the most commonly used tools for analyzing CFAE are presented. Linear tools are initially applied to signals from AF ablation procedures, then nonlinear tools are shown and integrated intoa CFAE detection algorithm. This one is based on the quantification of electrogram recurrence properties. In the second part, the cell and cardiac muscle tissue are described and simulated using mathematical models. Models such as FitzHugh Nagumo, Aliev Panfilov and Courtemanche…
Multimodal approaches to the treatment of hepatocellular carcinoma.
2008
The prevalence of hepatocellular carcinoma in Europe and the US is increasing and is currently the leading cause of death in patients with cirrhosis. Surveillance programs for patients with cirrhosis aim to detect tumors at an early stage, when the greatest therapeutic benefits can be achieved. Curative treatments for early-stage tumors include liver transplantation, resection and percutaneous ablation. Transarterial chemoembolization (TACE) and sorafenib can improve survival for patients with intermediate and advanced tumors, respectively. In clinical practice, combination therapies are often used, despite limited evidence to support this approach from randomized controlled trials. Combina…