Modélisation statistique du Speckle en OCT : application à la segmentation d'images de la peau

Cette thèse porte sur la segmentation d'images OCT cutanées. Cette modalité d'imagerie permet de visualiser les structures superficielles avec une profondeur de l'ordre du millimètre. En dermatologie, elle permet d'explorer l'épiderme et sa jonction avec le derme. Cependant, les images OCT sont sévèrement affectées par le bruit speckle. Ce phénomène conjugué à la complexité inhérente aux structures de la peau rend l'interprétation des images difficile même pour des experts. L'approche classique consiste à filtrer le speckle avant de faire des traitements de segmentation. A l'inverse, dans cette thèse nous exploitons exclusivement le bruit comme information pour segmenter. Notre approche repose sur la modélisation statistique du speckle. La segmentation se fait par classification des paramètres de ce modèle probabiliste. Ainsi, - On montre que le speckle ne suit pas une loi Rayleigh, comme cela est établi analytiquement. - On ajuste plusieurs lois de probabilité à l'amplitude OCT; et on montre que celle-ci est distribuée selon la loi Gamma généralisée. - On établit que les paramètres de cette loi discriminent statistiquement les couches de la peau. - On conçoit une méthode de segmentation par classification des paramètres locaux du speckle. Les nombreuses expérimentations faites sur plusieurs corpus d'images in-vivo confirment la validité de notre approche. ABSTRACT : This thesis deals with the segmentation of skin OCT images. This modality provides the means to visualize superficial structures down to a millimeter depth. In dermatology, it is used to examine the epidermis and its junction with the dermis. However, OCT images are severely affected by the speckle noise. This random phenomenon added to the complexity of human skin structures makes the visual interpretation of images very difficult. Classical image processing techniques filter this noise prior to any segmentation step. In this thesis, we rely exclusively on the properties of the speckle to perform segmentation. Our approach is based on the statistical modeling of the speckle. Images are segmented by classifying parameters of the statistical model. Therefore, - We show that speckle does not follow the Rayleigh distribution, as developed analytically in the literature. - We fit various probability laws to model OCT signal amplitude ; we show that Generalized Gamma has the best goodness of fit. - We establish that statistical parameters of this distribution discriminate skin layers with good variability. - We develop a segmentation method based on the classification of local statistical parameters. The various experimental results with a number of in-vivo images reported in the thesis confirm the validity of our approac

Hydroboration of Methyl Esters of Fatty Acids

Hydroboration addition reactions of a boron atom, and hydrogen over unsaturated, have been widely studied. They have excellent access routes to organoborans which have proven to be a very useful synthetic intermediate (Brown et al.; Matteson, 1987; Smith, 1994). The bill might be on one or other of the two carbons of the unsaturation. It is carried out preferentially along the least congested carbon (anti-Markownikov addition). This regioselectivity can be changed against steric effects (Brown & Zweifel, 1960; Brown & Sharp, 1968; Brown et al., 1974). The existence of two active sites in methyl esters of fatty acids, FAME: the carbon-carbon unsaturation and the ester, make their hydroboration reactions more difficult to achieve. However, it has been demonstrated that reducing the ester groups is much slower than that of olefins (Brown & Keblys, 1964). By using suitable operating conditions, it is possible to limit this secondary reaction and to obtain a selective reaction of carboncarbon double bond (Fore & Bickford, 1959). Others have protecting ester function by a silyl group in order to have a single reactive site (Kabalka & Bierer, 1989)

Evidence and consensus on technical aspects of embryo transfer

BACKGROUND Ultrasound-guided embryo transfer (US-GET) is a widely performed procedure, but standards for the best practice are not available. OBJECTIVE AND RATIONALE This document aims to provide an overview of technical aspects of US-GET after considering the published data and including the preparation for the embryo transfer (ET) procedure, the actual procedure, the post-procedure care, associated pathologies, complications and risks, quality assurance and practitioners' performance. SEARCH METHODS A literature search for evidence on key aspects of the ET procedure was carried out from database inception to November 2021. Selected papers (n = 359) relevant to the topic were analysed by the authors. The following key points were considered in the papers: whether ultrasound (US) practice standards were explained, to what extent the ET technique was described and whether complications or incidents and how to prevent such events were reported. In the end, 89 papers could be used to support the recommendations in this document, which focused on transabdominal US-GET. OUTCOMES The relevant papers found in the literature search were included in the current document and described according to the topic in three main sections: requirements and preparations prior to ET, the ET procedure and training and competence for ET. Recommendations are provided on preparations prior to ET, equipment and materials, ET technique, possible risks and complications, training and competence. Specific aspects of the laboratory procedures are covered, in particular the different loading techniques and their potential impact on the final outcomes. Potential future developments and research priorities regarding the ET technique are also outlined. LIMITATIONS, REASONS FOR CAUTION Many topics were not covered in the literature review and some recommendations were based on expert opinions and are not necessarily evidence based. WIDER IMPLICATIONS ET is the last procedural step in an ART treatment and is a crucial step towards achieving a pregnancy and live birth. The current paper set out to bring together the recent developments considering all aspects of ET, especially emphasizing US quality imaging. There are still many questions needing answers, and these can be subject of future research. STUDY FUNDING/COMPETING INTEREST(S) No funding. A.D.A. has received royalties from CRC Press and personal honorarium from Cook, Ferring and Cooper Surgical. The other co-authors have no conflicts of interest to declare that are relevant to the content of this article.Peer reviewe

Antibacterial and antibiofilm activities of polysaccharides, essential oil, and fatty oil extracted from Laurus nobilis growing in Lebanon

AbstractObjectiveTo evaluate the antibacterial activity of the extracts of Laurus nobilis against three Gram-positive bacteria (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212 and Staphylococcus epidermidis CIP 444) and two Gram-negative bacteria (Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 27853). Also, the antibiofilm activity has been investigated against the biofilm produced by Staphylococcus epidermidis CIP 444.MaterialsThe polysaccharides, essential oil, and fatty oils extracted from the plant were used in broth microdilution methods to study the minimal inhibitory concentration, and then the minimal bactericidal concentration was determined.ResultsThe results showed that alginate, fucoidan, fatty oils and essential oil have good antibacterial activities against the 5 bacterial strains, and a negligible biofilm eradication activity of fucoidan, laminaran, fatty oil, and essential oil was observed, but a promising biofilm eradication activity was obtained with alginate, which showed a reduced biofilm mass even at low concentration.ConclusionsThe extracts obtained have promising antibacterial capacities which need further investigation for them to be incorporated in medical or nutritional applications

BIOSORPTION OF METHYLENE BLUE FROM WASTE WATER USING LEBANESE CYMBOPOGON CITRATUS (CITRONNELLE)

The objective of this study was to investigate the possibility of using Lebanese Cymbopogon citratus stem as an alternative adsorbent for the removal of methylene blue from aqueous solutions. Different parameters such as the effect of initial concentration, pH, adsorbent dose, contact time and temperature were studied. Maximum adsorption capacity (61%) of MB was obtained at PH=6 an initial concentration 200 mg/L after 24h and at 25 ˚C. The adsorption isotherm was better described by a Freundlich model rather than a Langmiur model. Based on these results, it can be concluded that the stems of Cymbopogon citratus is effective as an alternative adsorbent for MB remediation in waste water

BIOSORPTION OF METHYLENE BLUE FROM WASTE WATER USING LEBANESE CYMBOPOGON CITRATUS (CITRONNELLE)

The objective of this study was to investigate the possibility of using Lebanese Cymbopogon citratus stem as an alternative adsorbent for the removal of methylene blue from aqueous solutions. Different parameters such as the effect of initial concentration, pH, adsorbent dose, contact time and temperature were studied. Maximum adsorption capacity (61%) of MB was obtained at PH=6 an initial concentration 200 mg/L after 24h and at 25 ˚C. The adsorption isotherm was better described by a Freundlich model rather than a Langmiur model. Based on these results, it can be concluded that the stems of Cymbopogon citratus is effective as an alternative adsorbent for MB remediation in waste water

3D+t segmentation of PET images using spectral clustering

International audienceSegmentation of dynamic PET images is often needed to extract the time activity curve (TAC) of regions. While clustering methods have been proposed to segment the PET sequence, they are generally either sensitive to initial conditions or favor convex shaped clusters. Recently, we have proposed a deterministic and automatic spectral clustering method (AD-KSC) of PET images. It has the advantage of handling clusters with arbitrary shape in the space in which they are identified. While improved results were obtained with AD-KSC compared to other methods, its use for clinical applications is constrained to 2D+t PET data due to its computational complexity. In this paper, we propose an extension of AD-KSC to make it applicable to 3D+t PET data. First, a preprocessing step based on a recursive principle component analysis and a Global K-means approach is used to generate many small seed clusters. AD-KSC is then applied on the generated clusters to obtain the final partition of the data. We validated the method with GATE Monte Carlo simulations of Zubal head phantom. The proposed approach improved the region of interest (ROI) definition and outperformed the K-means algorithm

Outcomes of SARS-CoV-2 infected pregnancies after medically assisted reproduction

The role of certain viruses in the etiology of some tumors is today indisputable, but there is a lack, however, of an overview of the relationship between viruses and cancer with a multidisciplinary approach. For this reason, the Health Sciences Foundation has convened a group of professionals from different areas of knowledge to discuss the relationship between viruses and cancer, and the present document is the result of these deliberations. Although viruses cause only 10-15% of cancers, advances in oncology research are largely due to the work done during the last century on tumor viruses. The clearest cancer-inducing viruses are: HPV, HBV, HCV, EBV and, depending on the geographical area, HHV-8, HTLV-1 and HIV. HPVs, for example, are considered to be the causative agents of cervical carcinomas and, more recently, of a proportion of other cancers. Among the Herpes viruses, the association with the development of neoplasms is well established for EBV and HHV-8. Viruses can also be therapeutic agents in certain neoplasms and, thus, some oncolytic viruses with selective tropism for tumor cells have been approved for clinical use in humans. It is estimated that the prophylaxis or treatment of viral infections could prevent at least 1.5 million cancer deaths per year

Outcomes of SARS-CoV-2 infected pregancies after medically assisted reproduction.

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