Self consistent calculations of the electric charge, ion drag force, and the drift velocity of spherical grains using Langevin dynamics and comparisons against canonical experiments

The relative motion of ions with respect to objects/grains in a plasma leads to the ion drag force 1-5, like the drag force experienced by surfaces immersed in flows of neutral fluids. Ion drag force F ⃗_id plays a critical role in the collective motion and self-organization of grains in plasmas 6, 7, void formation in We present trajectory simulation-based modeling to capture the interactions between ions and charged grains in dusty or complex plasmas. Our study is motivated by the need for a self-consistent and experimentally validated approach for accurately calculating the ion drag force and grain charge that determine grain collective behavior in plasmas. We implement Langevin Dynamics in a computationally efficient multiscale approach to capture multiscale ion and grain dynamics. Along with critical assessments of our approach, suggestions for future experimental design to probe charging of and momentum transfer onto grains that capture the effect of space charge concentration and external fields are outlined

Human t-cell leukemia virus type 1 and strongyloides stercoralis: Partners in pathogenesis

Infection with human T-cell leukemia/lymphoma virus type 1 (HTLV-1) has been associated with various clinical syndromes including co-infection with Strongyloides stercoralis, which is an intestinal parasitic nematode and the leading cause of strongyloidiasis in humans. Interestingly, HTLV-1 endemic areas coincide with regions citing high prevalence of S. stercoralis infection, making these communities optimal for elucidating the pathogenesis of co-infection and its clinical significance. HTLV-1 co-infection with S. stercoralis has been observed for decades in a number of published patient cases and case series; however, the implications of this co-infection remain elusive. Thus far, data suggest that S. stercoralis increases proviral load in patients co-infected with HTLV-1 compared to HTLV-1 infection alone. Furthermore, co-infection with HTLV-1 has been associated with shifting the immune response from Th2 to Th1, affecting the ability of the immune system to address the helminth infection. Thus, despite this well-known association, further research is required to fully elucidate the impact of each pathogen on disease manifestations in co-infected patients. This review provides an analytical view of studies that have evaluated the variation within HTLV-1 patients in susceptibility to S. stercoralis infection, as well as the effects of strongyloidiasis on HTLV-1 pathogenesis. Further, it provides a compilation of available clinical reports on the epidemiology and pathology of HTLV-1 with parasitic co-infection as well as data from mechanistic studies suggesting possible immunopathogenic mechanisms. Furthermore, specific areas of potential future research have been highlighted to facilitate advancing understanding of the complex interactions between these two pathogens

Regulation of human T-cell leukemia virus type 1 antisense promoter by myocyte enhancer factor-2C in the context of adult T-cell leukemia and lymphoma

Adult T-cell leukemia and lymphoma (ATLL) is an intractable T-cell neoplasia caused by a retrovirus, namely human T-cell leukemia virus type 1 (HTLV-1). Patients suffering from ATLL present a poor prognosis and have a dearth of treatment options. In contrast to the sporadic expression of viral transactivator protein Tax present at the 5’ promoter region long terminal repeats (LTR), HTLV-1 bZIP gene (HBZ) is encoded by 3’LTR (the antisense promoter) and maintains its constant expression in ATLL cells and patients. The antisense promoter is associated with selective retroviral gene expression and has been an understudied phenomenon. Herein, we delineate the activity of transcription factor MEF (myocyte enhancer factor)-2 family members, which were found to be enriched at the 3'LTR and play an important role in the pathogenesis of ATLL. Of the four MEF isoforms (A to D), MEF-2A and 2C were highly overexpressed in a wide array of ATLL cell lines and in acute ATLL patients. The activity of MEF-2 isoforms were determined by knockdown experiments that led to decreased cell proliferation and regulated cell cycle progression. High enrichment of MEF-2C was observed at the 3'LTR along with cofactors Menin and JunD resulting in binding of MEF-2C to HBZ at this region. Chemical inhibition of MEF-2 proteins resulted in the cytotoxicity of ATLL cells in vitro and reduction of proviral load in a humanized mouse model. Taken together, this study provides a novel mechanism of 3’LTR regulation and establishes MEF-2 signaling a potential target for therapeutic intervention for ATLL

Développement d'un outil numérique pour l’optimisation de la structure interne de pièce imprimée avec le FDM

L'objectif de cette thèse est de développer un outil numérique pour optimiser la structure interne des pièces imprimées en 3D produites par le procédé dépôt de fil fondu (DFF). En impression 3D, le terme remplissage fait référence à la structure interne de la pièce. Pour créer la conception de remplissage, un logiciel de tranchage est utilisé, qui crée généralement le remplissage uniformément dans toute la pièce. Lorsqu'une telle pièce est soumise à une charge externe, toutes les régions de remplissage ne subiront pas la même quantité de contrainte. Par conséquent, l'utilisation d'un remplissage uniforme dans toute la pièce n'est pas la solution la plus optimisée en termes d'utilisation des matériaux. Nous visons à développer un outil numérique pour faire évoluer la conception du remplissage par rapport aux contraintes mécaniques générées par les charges externes. Pour y parvenir, nous proposons deux méthodologies différentes basées sur un processus itératif utilisant des techniques de raffinement et de remaillage couplées à la simulation par éléments finis (simulation EF) pour contrôler la structure interne de la pièce sans modifier le contour. Ces méthodologies visent à renforcer le remplissage de la pièce sans modifier le contour, dans la zone où la résistance mécanique doit être améliorée pour renforcer la structure, mais aussi à diminuer la quantité de matière pour réduire le temps d'impression.The objective of this thesis is to develop a numerical tool to optimise the internal structure of 3D printed parts produced by the Fused Deposition Modelling (FDM) process. In 3D printing, the term infill refers to the internal structure of the part. To create the infill design, slicing software is used, which generally creates the infill uniformly throughout the part. When such a part is subjected to external loading, not all the infill regions will experience the same amount of stress. Therefore, using uniform infill throughout the part is not the most optimised solution in terms of material usage. We aim to develop a numerical tool to evolve the infill design with respect to the mechanical stresses generated by the external loads. To achieve this, we propose two different methodologies based on an iterative process using refinement technique and remeshing techniques coupled to Finite Element simulation (FE simulation) to control the internal structure of the part without changing the contour. These methodologies aim to reinforce the infill of the part without changing the contour, in the area where the mechanical strength must be improved to strengthen the structure, but also to decrease the amount of material to reduce the printing time

Infill Design Reinforcement of 3D Printed Parts Using Refinement Technique Adapted to Continuous Extrusion

In this paper, we introduce an advanced numerical tool aimed to optimise the infill design of 3D printed parts by reducing printing time. In 3D printing, the term infill refers to the internal structure of a part. To create the infill design, slicing software is used, which generally creates the infill uniformly throughout the part. When such a part is subjected to external loading, all the infill regions will not experience the same amount of stress. Therefore, using uniform infill throughout the part is not the most optimised solution in terms of material usage. We do propose to evolve the infill design with respect to the mechanical stresses generated by the external loads. To achieve this, an advanced numerical tool has been developed, based on refinement techniques, to control the infill design. This tool is coupled with Finite Element Simulation (FE Simulation) software, which helps to identify the zones where the material is required as an infill to reinforce a part, whereas the refinement technique makes it possible to place the material as an infill in such a way that the airtime during the printing of the part is zero. Zero airtime printing is defined as the ability to deposit each layer of a part, without stopping the material extrusion during the displacement of the nozzle. Therefore, the proposed numerical tool guides us to generate the infill design of a part, in such a way that it will consume zero airtime while manufacturing. Simultaneously, it will increase the stiffness of the part. The proposed approach is here applied to a rectangular structure subjected to four-point bending, made up of PLA material (Poly-Lactic Acid)

Geometrical, Flexural and Vibroacoustical Characterization of Saxophone Reeds

The sound production by the saxophone, a single-reed wind instrument, relies mainly on the control of the vibration of a plate by the player’s lower lip and the air blown into the instrument. This vibrating plate is securely attached to the mouthpiece and is known as a reed. In this study, we have investigated eight different reeds, including both (natural) cane reeds and reeds made of synthetic materials, compared their design, material and vibroacoustic properties. The long-term aim of this study is to facilitate the fabrication of reeds aiming to aide musicians in customizing their reeds aligning with their specific needs

Dimensionnement, fabrication et caractérisation d'anches de saxophone en composite à fibre de lin Design, manufacture and characterisation of flax fibre composite saxophone reeds

Single-reed wind instruments, such as the saxophone, have a vibrating plate attached to the mouthpiece. The musician creates the vibrations by blowing into the space between the reed and the mouthpiece, which produces the sound. This vibrating plate is called the reed. Traditionally, saxophone reeds are made from natural cane (Arundo Donax), but to overcome problems of variability and durability, synthetic reeds of various types have been developed. The project is part of an ambitious partnership between the Materials and Structures team, the LMA Sound team and the start-up SYOS. The aim is to develop saxophone reeds made from flax fibre composites that are more durable and of consistent quality (i.e. more reproducible than reed reeds), while at the same time creating a catalogue of reeds associated with the musical sensations of the saxophonist.Dans les instruments à vent à anche simple tels que le saxophone, une plaque vibrante est fixée à l'embouchure. Le musicien génère les vibrations en soufflant dans l'espace entre l'anche et le bec, ce qui crée le son. Cette plaque vibrante est appelée anche. Traditionnellement, les anches de saxophone sont fabriquées en canne naturelle (Arundo Donax L), mais afin de surmonter les problèmes de variabilité et de durabilité, des anches synthétiques de différents types ont été développées. Le projet se place dans le cadre d'un partenariat ambitieux entre l'équipe matériaux et structures, l'équipe son du LMA et de la start-up SYOS. Il se propose de développer des anches de saxophone en matériaux composites à fibre de lin plus durables et de qualité constante (i.e. plus reproductibles que les anches en roseau) tout en créant un catalogue d'anches associées aux ressentis musicaux du saxophoniste