Etude de la structure des noyaux exotiques semi-magiques en séniorité généralisée

The experimental results on nuclei far from the valley of stability constitute a severe test of currently accepted models of nucler structure. Specifically, the discovery of new magic numbers has put into question the conventional choices that are made to define the valence space of the nuclear shell model. The approach followed in this thesis to elucidate this proble is based on the nuclear pairing property and allows the reduction of the dimensionality of the shel-model configuration-space. The net result is that, as a result of the ensuing genralized-seniority truncation, larger valence spaces can be treated in a shell-model approcah. Nevertheless, the approximation is valid for semi-magic nuclei only. Extensive comparisons of generlized-seniority calculations with results from analytical models or with exact shell-model calculations are carried out to test the quality and limitations of the truncation. Applications to nuclei of current interest are considered and, specifically, two series of nuclei are studied: - The nickel isotopes. To have a full description of excitations in these nuclei, the 0f1p0g9/2 valence space is considered. This choice is validated by the study of known stable isotopes and calculations are subsequently extended to the neutron rich side to study the N=40 sub-shell effect. - The N=82 isotones. The size of the valence space is varied and the influence of its size on the half-life of these isotones of astrophysical interest is studied. The results demonstrate the usefulness of the choice of a proper criterion for a shell-model truncation and also how symmetry principles can guide this choice.L'étude expérimentale de noyaux de plus en plus riche (ou pauvres) en neutrons met à rude épreuve les modèles de structure nucléaire. Ainsi, la découverte de nouveaux nombres magiques pose le problème de la définition de l'espace-modèle dans les calculs de modèle en couches. L'approche suivie consiste à utiliser les propriétés d'appariement des nucléons pour diminuer les dimensions de l'espace des configurations utilisé dans le modèle en couches. Cette approche, dite de séniorité généralisée, nous permet d'agrandir les espaces de valence tout en gardant les dimensions des matrices accessibles à une digonalisation numérique. Elle n'est toutefois valable qu'aux alentours de noyaux semi-magiques. Un ensemble de comparaisons de nos résultats à des calculs analytiques puis à des calculs de type modèle en couche complet, dans des espaces où ils étaient réalisables, nous a permis d'apprécier la qualité de notre approximation. Une explication de notre approche à des problèmes théoriques d'actualité a ensuite été réalisée. Deux séries de noyaux se prêtaient particulièrement bien à cette application : les isotopes du nickel. Afin de tenir compte des excitations décrites dans d'autres études comme extérieures à l'espace-modèle, nous avons considéré l'espace 0f1p0g9/2. Nous avons validé ce choix sur les isotope les plus stables avant d'étudier la fermeture de la sous-couche N = 40. Les isotones de 82 neutrons

Etude de la structure des noyaux exotiques semi-magiques en séniorité généralisées

CAEN-BU Sciences et STAPS (141182103) / SudocSTRASBOURG-Bib.Central Recherche (674822133) / SudocSudocFranceF

Management of thyroid nodules

SCOPUS: re.jinfo:eu-repo/semantics/publishe

Sudden hearing loss

Sudden hearing loss. This update on the latest studies and management policies for patients suffering from sudden sensorineural hearing loss (SSHL) represents a cooperative effort of Belgian ENT surgeons from various corners of the country. SSHL has an incidence ranging from 5 to 20 cases per 100,000 persons per year, and is a relative medical emergency, as only 30% to 65% of the patients recover spontaneously. Nowadays, treatment varies a great deal between countries and hospitals. The various etiologies and therapeutic modalities are reviewed, and evidence levels are indicated. Finally, diagnostic and therapeutic organigrams are proposed along with a Belgian therapeutic cocktail in view of conducting a large Belgian study on the management of SSHL

Autologous costochondral cartilage implant in two cases of velopharyngeal insufficiency

The velopharyngeal sphincter is critical in enabling the functions of speaking and swallowing. Velopharyngeal insufficiency (VPI) results in hypernasal speech and nasal regurgitation. A frequent cause of VPI is congenital cleft palate, but otolaryngologists sometimes encounter iatrogenic VPI after surgery. Treatment of VPI with prostheses is often successful but not always well tolerated. Many surgical procedures have been proposed to correct palatal length or to enlarge the posterior pharyngeal wall. We report two cases in which autologous costochondral cartilage was used as implant augmentation. This approach is indicated and efficient when the velopharyngeal deficit is less than 5 rum. An autologous costochondral cartilage implant procedure is safe and reversible and can be expected to incite minimal host reaction