Littérature scientifique sur le sujet « Bos3d »

OBJECTIVE Bottom-of-sulcus dysplasia (BOSD) is challenging to identify radiologically. The aim of this study was to explore seizure outcomes after resective surgery or MR-guided laser interstitial thermal therapy (MRgLITT) in children with BOSD. METHODS Children with radiologically defined BOSD who underwent resective surgery or MRgLITT, with at least 1 year of follow-up were included. Clinical, radiological, neurophysiological, and histological data were extracted from medical records. Invasive video EEG (IVEEG) was used to evaluate the ictal onset zone or motor/language mapping, wherever appropriate. Histology of MRI-visible BOSD, including the overlying and adjacent cortex, was also evaluated. RESULTS Forty-one children with BOSD underwent surgical treatment. The lesion was initially overlooked on MRI in 20 patients (48.8%). Of 34 patients who underwent IVEEG and who had available ictal data, the ictal onset zone extended beyond the MRI-visible BOSD in 23 patients (67.6%). Surgical treatment included lesionectomy (24 patients), extended lesionectomy (12 patients), lobectomy (1 patient), and ablation of BOSD (4 patients). The pathology in 37 patients who underwent resection showed focal cortical dysplasia type IIB and type IIA in 21 (53.8%) and 16 patients (41%), respectively. Seizure freedom was achieved in 32 patients (78.1%) after a mean follow-up of 4.3 years. CONCLUSIONS Seizure outcomes after resective surgery or MRgLITT in children with BOSD were generally favorable. The authors found that the neurophysiological abnormality and pathology often extended beyond the MRI-visible BOSD.

Background and ObjectivesTo identify white matter fiber tracts that exhibit structural abnormality in patients with bottom-of-sulcus dysplasia (BOSD) and investigate their association with seizure activity.MethodsWhole-brain fixel-based analysis of diffusion MRI data was performed to identify white matter fiber tracts with significant reductions in fiber density and cross-section in patients with BOSD (n = 20) when compared to healthy control participants (n = 40). Results from whole-brain analysis were used to investigate the association of fiber tract abnormality with seizure frequency and epilepsy duration.ResultsDespite the focal nature of the dysplasia, patients with BOSD showed widespread abnormality in white matter fiber tracts, including the bilateral corticospinal, corticothalamic, and cerebellothalamic tracts, superior longitudinal fasciculi, corpus callosum (body), and the forceps major. This pattern of bilateral connectivity reduction was not related to the laterality of the lesion. Exploratory post hoc analyses showed that high seizure frequency was associated with greater reduction in fiber density at the forceps major, bilateral corticospinal, and cerebellothalamic tracts.DiscussionWe demonstrate evidence of a bilaterally distributed, specific white matter network that is vulnerable to disruption in BOSD. The degree of tract abnormality is partly related to seizure activity, but additional contributors such as the genetic background and effects of treatment or environment have not been excluded.

ObjectiveTo determine whether 1-stage, limited corticectomy controls seizures in patients with MRI-positive, bottom-of-sulcus dysplasia (BOSD).MethodsWe reviewed clinical, neuroimaging, electrocorticography (ECoG), operative, and histopathology findings in consecutively operated patients with drug-resistant focal epilepsy and MRI-positive BOSD, all of whom underwent corticectomy guided by MRI and ECoG.ResultsThirty-eight patients with a median age at surgery of 10.2 (interquartile range [IQR] 6.0–14.1) years were included. BOSDs involved eloquent cortex in 15 patients. Eighty-seven percent of patients had rhythmic spiking on preresection ECoG. Rhythmic spiking was present in 22 of 24 patients studied with combined depth and surface electrodes, being limited to the dysplastic sulcus in 7 and involving the dysplastic sulcus and gyral crown in 15. Sixty-eight percent of resections were limited to the dysplastic sulcus, leaving the gyral crown. Histopathology was focal cortical dysplasia (FCD) type IIb in 29 patients and FCDIIa in 9. Dysmorphic neurons were present in the bottom of the sulcus but not the top or the gyral crown in 17 of 22 patients. Six (16%) patients required reoperation for postoperative seizures and residual dysplasia; reoperation was not correlated with ECoG, neuroimaging, or histologic abnormalities in the gyral crown. At a median 6.3 (IQR 4.8–9.9) years of follow-up, 33 (87%) patients are seizure-free, 31 off antiseizure medication.ConclusionBOSD can be safely and effectively resected with MRI and ECoG guidance, corticectomy potentially being limited to the dysplastic sulcus, without need for intracranial EEG monitoring and functional mapping.Classification of EvidenceThis study provides Class IV evidence that 1-stage, limited corticectomy for BOSD is safe and effective for control of seizures.

ObjectiveTo determine the genetic basis of bottom-of-sulcus dysplasia (BOSD), which is a highly focal and epileptogenic cortical malformation in which the imaging, electrophysiologic, and pathologic abnormalities are maximal at the bottom of sulcus, tapering to a normal gyral crown.MethodsTargeted panel deep sequencing (>500×) was performed on paired blood and brain-derived genomic DNA from 20 operated patients with drug-resistant focal epilepsy and BOSD. Histopathology was assessed using immunohistochemistry.ResultsBrain-specific pathogenic somatic variants were found in 6 patients and heterozygous pathogenic germline variants were found in 2. Somatic variants were identified in MTOR and germline variants were identified in DEPDC5 and NPRL3. Two patients with somatic MTOR variants showed a mutation gradient, with higher mutation load at the bottom of sulcus compared to the gyral crown. Immunohistochemistry revealed an abundance of dysmorphic neurons and balloon cells in the bottom of sulcus but not in the gyral crown or adjacent gyri.ConclusionsBOSD is associated with mTOR pathway dysregulation and shares common genetic etiologies and pathogenic mechanisms with other forms of focal and hemispheric cortical dysplasia, suggesting these disorders are on a genetic continuum.

L'objectif de cette thèse est d'étudier les mécanismes physiques qui gouvernent l'évolution et le mélange des jets latéraux au sein des jets ronds de mélange binaire à faible densité, au moyen d'une double approche numérique et expérimentale. Les mécanismes physiques à l'origine des jets latéraux restent encore incertains et sont en lien direct avec le développement d'instabilités secondaires responsables de la tridimensionalisation de l'écoulement. Ainsi, une meilleure compréhension de ces mécanismes en jeu constitue un prérequis indispensable à la conception d'une stratégie de contrôle qui vise à promouvoir le mélange entre le jet et l'environnement ambiant.L'objectif de l'étude numérique est d'identifier les mécanismes transitoires qui influencent la croissance des perturbations tridimensionnelles dans le jet rond à faible masse volumique, en particulier dans les conditions physiques pour lesquelles apparaissent les jets latéraux. À cet effet, nous mettons en oeuvre une analyse de stabilité linéaire non-modale de l'évolution non-linéaire et axisymétrique de l'anneau tourbillonnaire de Kelvin-Helmholtz qui se développe dans les jets ronds à faible masse volumique en réponse à l'instabilité primaire de Kelvin-Helmholtz. Cette analyse de stabilité est réalisée à l'aide du code académique dalsa qui a été adapté pour ce régime d'écoulement. L'utilisation d'une méthode d’optimisation directe-adjointe permet d'identifier la structure spatiale et l'évolution temporelle des perturbations tridimensionnelles qui maximisent leur gain d'énergie généralisée, ainsi que les mécanismes physiques sous-jacents et leur lien avec l'apparition des jets latéraux. En particulier, l'objectif est d'apporter de nouveaux éléments permettant de statuer entre les deux hypothèses proposées dans la littérature pour expliquer le mécanisme à l'origine des jets latéraux. La première proposée par Monkewitz & Pfizenmaier (1991) repose sur un mécanisme d'induction de vitesse par les tourbillons longitudinaux contra-rotatifs qui se développent dans les écoulement cisaillés à masse volumique constante. La seconde est basée sur le mécanisme de tri-dimensionalisation associé aux stries de vitesse longitudinale de signe opposé qui se développent de part et d'autre du point de stagnation hyperbolique dans la tresse identifiée par Lopez-Zazuetaet al. (2016) dans la couche de mélange plane à densité variable.L'étude numérique conduite dans cette thèse est conçue en lien étroit avec la campagne expérimentale visant à étudier la structure des jets latéraux dans un jet de mélange binaire hélium-air. Ainsi, les paramètres de l'étude numérique comme les nombres de Reynolds et d'Atwood ainsi que le rapport d'aspect du jet, sont basés sur les conditions expérimentales. Ceci permet une comparaison directe des résultats théoriques aux observations expérimentales. Pour ce faire, nous avons conduit une campagne de mesures d'anémométrie à fil chaud du profil radial de vitesse du jet, et de la fréquence de l'instabilité primaire, afin de le caractériser et de le placer dans le contexte de la littérature scientifique.L'objectif de l'approche expérimentale est d'analyser la structure des jets latéraux et le mélange qu'ils induisent. Nous avons ainsi conçu et assemblé un banc de Background Oriented Schlieren tomographique (3DBOS). Ce banc est conçu afin de pouvoir observer les déviations optiques de l'ordre de 0,5 mrad induites par le champ hétérogène d'indices de réfraction créé par le jet de mélange hélium-air. Les mesures de 3DBOS obtenues permettent de reconstruire les champs de masse volumique du jet à faible densité en présence de jets latéraux. Ces champs de masse volumique sont originaux dans la littérature scientifique sur le sujet, et permettent d'augmenter notre compréhension de la structure des jets latéraux et de leur impact sur le mélange, et ainsi de corroborer les prédictions issues de l'analyse de stabilité
The aim of this PhD thesis is to study the physical mechanisms which govern the evolution and the mixing of side-jets in low-density binary mixing round jets, using a complementary numerical and experimental approach. The physical mechanisms which are responsible for the generation of side-jets, closely related to the three-dimensionalisation of the jet through the development of secondary instabilities, are as of yet not fully understood. As such, a better understanding of the mechanisms at play is a prerequisite for the design of an efficient control strategy to promote the mixing between the jet and ambient fluid.The objective of the numerical study is to identify the transient mechanisms which influence the growth of three-dimensional disturbances in the low-density round jet, specifically under the physical conditions in which side-jets appear. To that aim, a linear non-modal stability analysis was conducted over the non-linear evolution of a two dimensional axisymmetric Kelvin-Helmholtz vortex ring which develops in low-density round jets due to the Kelvin-Helmholtz primary instability.The stability analysis was implemented through further numerical development of the existing dalsa academic code. Through the use of a direct-adjoint optimisation method, we identify the spatial structure and temporal evolution of three-dimensional disturbances which yield the highest growth of generalised energy, as well as the underlying physical mechanisms and their relation to side-jets generation in low-density round jets at low Atwood numbers. In particular, we seek to bring a new perspective in order to settle between the two current hypotheses concerning the physical mechanisms at the origin of side-jets. The first hypothesis suggested by Monkewitz & Pfizenmaier (1991) relies on a velocity induction mechanism induced by the longitudinal counter-rotating vortex dipoles developing in the constant-density case. The second one is based on the three-dimensionalisation mechanism associated with longitudinal velocity streaks of opposite sign developing on either side of the hyperbolic stagnation point in the braid identified by Lopez-Zazueta et al. (2016) in the case of variable-density plane mixing layers.The numerical analysis is conducted in close relation to an experimental investigation of the structure of side-jets in a helium-air binary mixture round jet. The parameters used in the numerical analysis, such as the Reynolds number, the Atwood number and jet aspect ratio, are based on the operating conditions used in the experiment, allowing the theoretical predictions to be compared with the empirical evolution of the helium-air jet. To that aim, we conduct hot-wire anemometry measurements of the jet radial profile and frequency of the primary instability under several operating conditions to characterise the evolution of the governing parameters and relate the experimental conditions to the existing scientific literature.The objective of the experimental investigation is to study the structure of side-jets and their effect on the mixing of the jet and ambient fluids. To do so, we have designed and assembled a tomographic Background Oriented Schlieren (3DBOS) experimental bench. This bench is designed to observe the deviations of light-rays of the order of 0.5 mrad induced by the change in refractive index in the helium-air jet. The 3DBOS technique employed in this study provides novel reconstructions of three-dimensional density maps of the side-jets which develop over the helium-air jet. Through these novel density maps, we can provide new insight into the structure of side-jets and their induced mixing, and relate them to the predictions of the stability analysis

碩士
南華大學
非營利事業管理研究所
91
The civil force of religious organization in Taiwan is an organized, non-profitable organization (NPO) with various potential capacities to serve the society. The role of local non-profitable organization in facing the changing environment plays important parts in services such as social welfare relief, the aged problems, and lifting unemployment situations. This is the motive of my research and I expect the results can be helpful for the society moving towards the world village. 　　The CORPS model developed by Dr. Si-tu about the NPO will be introduced. By using the documentary analysis and the depth interview method, the study of the subordinate charity association of the temple-- TA Tian Gong, will be conducted. Since the performance of a charity association is based on its internal management, a decision center (DC) concept will be discussed and verified in the case study. We also recommend the use of external relationships of charity association to make the function more effective such as: the relation with the community, the media, the government and other charity associations. After reviewing the case, I have the following results: （1）Charity association plays an important role in case of government failure. （2）Charity association plays an important role in maintaining the society value. （3）Charity association and government have the relationship of cooperative and complementary partnership. （4）Charity association is a local NPO and the guard for the neighborhood. （5）Charity association conforms the CORPS model.