Hole cutter

An adjustable hole cutter is described for use in forming circular openings in workpieces. The hole cutter is characterized by a mount of a substantially planar configuration, positionable into a plane paralleling the working plane of a selected workpiece. It also contains a shaft for imparting rotary motion to the mount about an axis of rotation normally related to the working plane, a plurality of stabilizing struts for resiliently supporting the mount in parallelism with the working plane as rotary motion is imparted thereto, a drill bit for drilling a pilot hole concentric with the axis of rotation, and an elongated cutting tool adjustably seated within a radially extended slot

Behaviour problems in children

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Biofabricated Constructs of Carbon-based Nanoparticles with Mesenchymal Stem Cells for Orthopedic Repair

Breakthroughs in tissue engineering are moving at a rapid rate especially in the regenerative bone biofabrication. Technology growth in the field of additive manufacturing (AM) such 3D bioprinting which provides the ability to create biocompatible 3D construct on which a cell source could be seeded is an encouraging substitute to autologous grafts. This present research aims to biofabricate a construct for bone tissue engineering using AM technology. The biocompatible material was chosen corresponding to bones extracellular matrix (ECM) composition, which demonstrates an inorganic and organic development phase: Poly (lactic-glycolic acid) was chosen as the polymeric matrix of the compound, due to its bioactivity, biocompatibility, and ability to regulate biodegradability to support cell and bone function; graphene-nanoparticle was chosen for mechanical and organic reinforcement to support the mineral phase of the ECM. A commercial 3D bioprinter called the Aether 1 was used. The printer is a pneumatic based printer, which allows printing from hydrogels to thermo polymers. The bioprinter is located in the Regenerative Medicine Lab in the Large Animal Clinical Sciences. The first part of our study was to show the relationship of mesenchymal stem cells and graphene-nanoparticles. This was to evaluate the ECM layout on the graphene for biocompatibility and establish markers for supporting osteogenesis. Second part of the research dealt with finding a safe solvent to melt the different molar ratios of PLGA and the blending in of graphene-nanoparticles for low thermodynamic and low-pressure printing. This work dealt with the characterization, constating in the evaluation of different extrusion speeds, pressure values and nozzle diameters to construct a 3D print for testing the biocompatibility and cellular behavior. The final study was to utilize the 3D constructs in a long bone segmental defect model to characterize its in vivo capabilities. This work proved that the biofabrication of the PLGA+graphene blend could be achieved and repeatable with 3D bioprinting, supports cellular behavior for regeneration and provided results in the long bone defect study

Isolating intrinsic noise sources in a stochastic genetic switch

The stochastic mutual repressor model is analysed using perturbation methods. This simple model of a gene circuit consists of two genes and three promotor states. Either of the two protein products can dimerize, forming a repressor molecule that binds to the promotor of the other gene. When the repressor is bound to a promotor, the corresponding gene is not transcribed and no protein is produced. Either one of the promotors can be repressed at any given time or both can be unrepressed, leaving three possible promotor states. This model is analysed in its bistable regime in which the deterministic limit exhibits two stable fixed points and an unstable saddle, and the case of small noise is considered. On small time scales, the stochastic process fluctuates near one of the stable fixed points, and on large time scales, a metastable transition can occur, where fluctuations drive the system past the unstable saddle to the other stable fixed point. To explore how different intrinsic noise sources affect these transitions, fluctuations in protein production and degradation are eliminated, leaving fluctuations in the promotor state as the only source of noise in the system. Perturbation methods are then used to compute the stability landscape and the distribution of transition times, or first exit time density. To understand how protein noise affects the system, small magnitude fluctuations are added back into the process, and the stability landscape is compared to that of the process without protein noise. It is found that significant differences in the random process emerge in the presence of protein noise

Exploring Lifetime Effects in Femtoscopy

We investigate the role of lifetime effects from resonances and emission duration tails in femtoscopy at RHIC in two Blast-Wave models. We find the non-Gaussian components compare well with published source imaged data, but the value of R_out obtained from Gaussian fits is not insensitive to the non-Gaussian contributions when realistic acceptance cuts are applied to models.Comment: 5 pages, 2 figure

IN-SITU ALLOYING OF TI6AL4V-x%CU STRUCTURES BY DIRECT METAL LASER SINTERING

ArticleThe formation of in-situ Ti6Al4V-x%Cu (1%, 3% and 5% Cu) alloy structures by Direct Metal Laser Sintering (DMLS) for application in medical implants was investigated. Ti6Al4V (ELI) powder was mixed with pure Cu powder of similar particle size distribution. Optimal process parameters were established for in-situ alloying of Ti6Al4V-x%Cu to form dense parts with suitable microstructural and surface quality. Process parameters such as laser power, scanning speed, hatch distance and layer thickness directly affect the surface quality and part density. Firstly, single track formation was studied at different scanning speeds for 170 W and 340 W laser powers. The effect of laser power and scanning speed on the track width and shape was described. Secondly, the surface roughness and single layer morphology were considered