Caractérisation d'une cellule de mesure électro-acoustique-pulsée pour la qualification électrostatique des diélectriques spatiaux : modélisation électro-acoustique et traitement du signal

La structure externe des satellites en orbite, composée de matériaux polymères, est exposée continument à des particules chargées induisant des potentiels à l'origine des Décharges Electrostatiques - ESD. Plusieurs techniques sont actuellement utilisées pour sonder la charge d'espace dans les matériaux diélectriques, une de ces techniques est la méthode électro-acoustique pulsée - PEA (Pulsed Electro-Acoustic). Cette méthode consiste en la détection des ondes acoustiques générées par la charge d'espace sous l'effet coulombien d'une impulsion de champ électrique appliqué. Après un traitement numérique adéquat, la distribution de la charge d'espace en fonction de la profondeur de l'échantillon est établie. L'un des inconvénients de cette technique pour la caractérisation des matériaux spatiaux est sa résolution spatiale, environ 10 µm. En effet, les matériaux diélectriques utilisés dans les structures satellites ont une épaisseur comprise entre 50 et 75µm. L'objectif de cette thèse consiste donc à concevoir une cellule de mesure de la charge d'espace avec une résolution spatiale suffisante pour analyser le comportement des charges dans des matériaux spatiaux, environ 1 µm. Ce projet finalisé permettra de disposer d'un outil de mesure parfaitement maitrisé en terme de limite en résolution et comprendre ainsi l'origine des artefacts présents généralement dans la mesure et ainsi éviter toute interprétation de phénomènes considérés comme physique mais qui sont, en réalité, uniquement la manifestation d'un défaut de la chaine de mesure.Dielectric materials are frequently used in satellite structures as a thermal blanket. Subjected to an electron irradiation - space environment - they can cause in-orbit satellite anomalies. One of these aspects is the charge accumulation due to the flux of space charged particles, and particularly to electrons. This accumulation increases the local electric field in the material bulk and can lead to an Electrostatic Surface Discharge - ESD. This phenomenon could cause serious damage to the satellite structure or performance. In order to have a better control on the discharge it is necessary to clarify; the nature, position and quantity of stored charges with time and to understand the dynamics of the charge transport in solid dielectrics. The Pulsed-Electro Acoustic - PEA method allows us to obtain these features, like the spatial distribution of space charges. One of the weaknesses of this current technique is spatial resolution, about 10 µm. Dielectric materials used in satellite structures have a thickness of 50 and 75 µm. This work aims at improving the spatial resolution for the PEA method. Whatever measurement principle considered, the best spatial resolution achievable is 10µm. This is a drawback when considering rather thin insulating layers (order of tens of microns), as the case in some capacitors or films on outer parts of satellites. Also, a better resolution (1µm) is expected to provide a better description of charge generation in insulation at metal dielectric interfaces or under low energy electron beams

Presacral malakoplakia presenting as foot drop: a case report

Background: Malakoplakia is a rare condition characterized by inflammatory masses with specific histological characteristics. These soft tissue masses can mimic tumors and tend to develop in association with chronic or recurrent infections, typically of the urinary tract. A specific defect in innate immunity has been described. In the absence of randomized controlled trials, management is based on an understanding of the biology and on case reports. Case presentation: Here we describe a case of presacral malakoplakia in a British Indian woman in her late 30s, presenting with complex unilateral foot drop. Four years earlier, she had suffered a protracted episode of intrapelvic sepsis following a caesarean delivery. Resection of her presacral soft tissue mass was not possible. She received empiric antibiotics, a cholinergic agonist, and ascorbic acid. She responded well to medical management both when first treated and following a recurrence of symptoms after completing an initial 8 months of therapy. Whole exome sequencing of the patient and her parents was undertaken but no clear causal variant was identified. Conclusions: Malakoplakia is uncommon but the diagnosis should be considered where soft tissue masses develop at the site of chronic or recurrent infections. Obtaining tissue for histological examination is key to making the diagnosis. This case suggests that surgical resection is not always needed to achieve a good clinical and radiological outcome

Loss of Expression and Promoter Methylation of SLIT2 Are Associated with Sessile Serrated Adenoma Formation.

Serrated adenomas form a distinct subtype of colorectal pre-malignant lesions that may progress to malignancy along a different molecular pathway than the conventional adenoma-carcinoma pathway. Previous studies have hypothesised that BRAF mutation and promoter hypermethylation plays a role, but the evidence for this is not robust. We aimed to carry out a whole-genome loss of heterozygosity analysis, followed by targeted promoter methylation and expression analysis to identify potential pathways in serrated adenomas. An initial panel of 9 sessile serrated adenomas (SSA) and one TSA were analysed using Illumina Goldengate HumanLinkage panel arrays to ascertain regions of loss of heterozygosity. This was verified via molecular inversion probe analysis and microsatellite analysis of a further 32 samples. Methylation analysis of genes of interest was carried out using methylation specific PCR (verified by pyrosequencing) and immunohistochemistry used to correlate loss of expression of genes of interest. All experiments used adenoma samples and normal tissue samples as control. SSA samples were found on whole-genome analysis to have consistent loss of heterozygosity at 4p15.1–4p15.31, which was not found in the sole TSA, adenomas, or normal tissues. Genes of interest in this region were PDCH7 and SLIT2, and combined MSP/IHC analysis of these genes revealed significant loss of SLIT2 expression associated with promoter methylation of SLIT2. Loss of expression of SLIT2 by promoter hypermethylation and loss of heterozygosity events is significantly associated with serrated adenoma development, and SLIT2 may represent a epimutated tumour suppressor gene according to the Knudson “two hit” hypothesis

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Caractérisation d'une cellule de mesure électro-acoustique-pulsée pour la qualification électrostatique des diélectriques spatiaux (modélisation électro-acoustique et traitement du signal)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Study of signal treatment for a pulsed electro-acoustic measurement cell: a way of improving the transfer matrix condition number

International audienceThis work is focused on the improvement of the condition number of the transfer function matrix in a pulsed electro-acoustic (PEA) cell. A numerical electro-acoustic model is developed with the software COMSOL. This model is one-dimensional and the system of equations with partial differential functions is solved using a finite element method in non-stationary situations. Using this model, we can establish the output voltage of the piezoelectric sensor and acoustic pressure at each point of the calculation domain. Our approach consists in recovering the charge distribution within the sample using a deconvolution method between the simulated output voltage and the transfer function of the PEA cell. Results show why some changes of the PEA cell such as the nature of materials or sensor geometry involve an ill-posed problem or ill-conditioned problem, and why other arrangements lead to a well-conditioned problem, more amenable to giving the appropriate solution