Brûlure | EPFL Graph Search

La brûlure est une destruction partielle ou totale pouvant concerner la peau, les parties molles des tissus, ou même les os. La gravité d'une brûlure dépend de plusieurs paramètres : sa localisation, sa topographie (une brûlure circulaire sera toujours grave), sa profondeur (le degré de brûlure), l'étendue de la surface endommagée (en pourcentage de la surface corporelle totale) et l'agent causal en question. Une brûlure peut être causée :

par le contact avec une source chaude (solide, liquide, ou gazeuse) ;
par le contact avec une substance dite caustique ;
par frottement ;
par l'effet de la combustion (action d'une flamme) ;
par l'effet d'un rayonnement (coup de soleil : rayonnement ultraviolet B, rayonnement infrarouge, rayonnement X) ;
par l'effet d'un courant électrique (électrisation) ;
par le froid (gelure).

Épidémiologie Dans le monde, les brûlures sont responsables de plus de annuels d'après l'Organisation mondiale de la santé. Ce nombre est très

Plasma breakdown and current formation in single core and doublet configurations on TCV

Joyeeta Sinha

This thesis presents an experimental investigation of the plasma formation in the TCV tokamak. The primary goal of this work was to program a reliable and smooth plasma formation at several positions within the TCV vessel and then use the gained understanding to revisit the creation of doublet plasma formation. The first part of this thesis is dedicated to understanding and improving the single-axis plasma formation scenario in TCV. A database for the single-axis TCV plasma formation scenario was created for discharges spanning several years of operation to understand the physics of the plasma formation dynamics. The database shows that most of the failed plasma formation in TCV were during the burn-through and ramp-up phase with only 0.5% of the discharges failing at breakdown. The failed plasma breakdowns are mainly attributed to technical issues, such as no injection of neutral gas into the vacuum vessel, absence of the toroidal field or the Ohmic coil current, and issues with the plasma control system. The improvement of the single-axis plasma formation was separated into two parts: improvement of the breakdown scenario and improvement of the plasma burn-through and ramp-up scenario. During the breakdown phase, a large mismatch was exposed between the intended and experimentally obtained vertical breakdown position, for both Z=0.05m and Z=+0.23m standard vertical breakdown positions and for both I_P and B_phi directions. This mismatch was caused by an additional poloidal field mainly due to errors in the back-off of the stray field generated by vessel currents. The use of a vessel resistivity assuming axisymmetry in the TCV discharge preparation procedure to model the vessel currents was identified as the main reason for the mismatch in the breakdown positions. The analysis of the plasma formation database revealed that most of the failed plasma formation during the burn-through and ramp-up phase occurred due to insufficient, albeit often temporary, Ohmic heating to sustain the plasma. The insufficient Ohmic heating was either due an insufficient initial I_P ramp rate, or a combined effect of strong I_P and/or radial position oscillations caused by the feedback control system due to too high initial I_P ramp rate. A bump-less transfer control technique was implemented to improve the reliability of plasma formation by avoiding the strong oscillations in I_P and radial position that resulted in reliable and sufficient Ohmic heating. The second part of this thesis focuses on developing a doublet shaped plasma configuration, which is a highly unconventional plasma configuration, and TCV's modern and unique shaping capabilities warrant an effort to revisit the configuration. Successful simultaneous breakdown at two locations in TCV was achieved by using the improved inductive breakdown scenario. The similar magnetic properties of the two magnetic null points ensured that the plasma current ramp rate in the two droplets were close and the plasma current in both droplets was ramped up to 50 kA each with Ohmic heating alone. A highly reproducible doublet formation scenario was finally achieved and was verified by several diagnostics. A highly reproducible doublet formation scenario was finally achieved and was verified by several diagnostics. A highest plasma current of 130 kA was achieved in each droplet, with a core electron temperature at 1.3keV, core electron density at 1.3e19m^-3, and 30ms duration with ECRH heating.

EPFL2017

Plastic Changes in Pain and Motor Network Induced by Chronic Burn Pain

Chang-Hyun Park

Musculoskeletal diseases with chronic pain are difficult to control because of their association with both central as well as the peripheral nervous system. In burn patients, chronic pain is one of the major complications that cause persistent discomfort. The peripheral mechanisms of chronic pain by burn have been greatly revealed through studies, but the central mechanisms have not been identified. Our study aimed to characterize the cerebral plastic changes secondary to electrical burn (EB) and non-electrical burn (NEB) by measuring cerebral blood volume (CBV). Sixty patients, twenty with electrical burn (EB) and forty with non-electrical burn (NEB), having chronic pain after burn, along with twenty healthy controls, participated in the study. Voxel-wise comparisons of relative CBV maps were made among EB, NEB, and control groups over the entire brain volume. The CBV was measured as an increase and decrease in the pain and motor network including postcentral gyrus, frontal lobe, temporal lobe, and insula in the hemisphere associated with burned limbs in the whole burn group. In the EB group, CBV was decreased in the frontal and temporal lobes in the hemisphere associated with the burned side. In the NEB group, the CBV was measured as an increase or decrease in the pain and motor network in the postcentral gyrus, precentral gyrus, and frontal lobe of the hemisphere associated with the burn-affected side. Among EB and NEB groups, the CBV changes were not different. Our findings provide evidence of plastic changes in pain and motor network in patients with chronic pain by burn.

MDPI2021

Scrambler Therapy for Chronic Pain after Burns and Its Effect on the Cerebral Pain Network: A Prospective, Double-Blinded, Randomized Controlled Trial

Chang-Hyun Park

Chronic pain is common after burn injuries, and post-burn neuropathic pain is the most important complication that is difficult to treat. Scrambler therapy (ST) is a non-invasive modality that uses patient-specific electrocutaneous nerve stimulation and is an effective treatment for many chronic pain disorders. This study used magnetic resonance imaging (MRI) to evaluate the pain network-related mechanisms that underlie the clinical effect of ST in patients with chronic burn-related pain. This prospective, double-blinded, randomized controlled trial (ClinicalTrials.gov: NCT03865693) enrolled 43 patients who were experiencing chronic neuropathic pain after unilateral burn injuries. The patients had moderate or greater chronic pain (a visual analogue scale (VAS) score of >= 5), despite treatment using gabapentin and other physical modalities, and were randomized 1:1 to receive real or sham ST sessions. The ST was performed using the MC5-A Calmare device for ten 45 min sessions (Monday to Friday for 2 weeks). Baseline and post-treatment parameters were evaluated subjectively using the VAS score for pain and the Hamilton Depression Rating Scale; MRI was performed to identify objective central nervous system changes by measuring the cerebral blood volume (CBV). After 10 ST sessions (two weeks), the treatment group exhibited a significant reduction in pain relative to the sham group. Furthermore, relative to the pre-ST findings, the post-ST MRI evaluations revealed significantly decreased CBV in the orbito-frontal gyrus, middle frontal gyrus, superior frontal gyrus, and gyrus rectus. In addition, the CBV was increased in the precentral gyrus and postcentral gyrus of the hemisphere associated with the burned limb in the ST group, as compared with the CBV of the sham group. Thus, a clinical effect from ST on burn pain was observed after 2 weeks, and a potential mechanism for the treatment effect was identified. These findings suggest that ST may be an alternative strategy for managing chronic pain in burn patients.

MDPI2022

Plasma breakdown and current formation in single core and doublet configurations on TCV

Joyeeta Sinha

EPFL2017

Scrambler Therapy for Chronic Pain after Burns and Its Effect on the Cerebral Pain Network: A Prospective, Double-Blinded, Randomized Controlled Trial

Chang-Hyun Park

MDPI2022