Biology subjects

Chizari, M.

Publications and source records attributed to Chizari, M..

5 recordsLinked to original sources

bioRxiv2024

A Causal Role of the Right Dorsolateral Prefrontal Cortex in Random Exploration

Our brain faces the dilemma of exploiting familiar options to gain immediate rewards or exploring new options to increase probable future rewards, in many real-life decisions, and solves it by direct and random exploration. Previous studies show that these two explorative strategies have dissociable neural correlates in the brain. Using the continuous theta burst stimulation (cTBS) and horizon task, we investigate the causal role of the right dorsolateral prefrontal cortex (rDLPFC) in direct and random exploration. Twenty-five healthy right-handed adult participants underwent cTBS, and vertex stimulation sessions, and then completed the horizon tasks. Both model-free and model-based analysis showed that cTBS over rDLPFC selectively reduced random exploration, but not direct exploration. This suggests a causal role for rDLPFC especially in random exploration, and further supports dissociable neural implementations for direct and random exploration. (C) 2024 The Author(s)

neuroscience↗

bioRxiv2021

Core bone diameter in an organic implant-less technique affecting the biomechanical properties of the anterior cruciate ligament fixation; an in-vitro study

BackgroundBone and site hold tendon inside (BASHTI) is an implant-less technique that can solve some of the problems associated with other anterior cruciate ligament (ACL) reconstructive methods. This study aims to investigate the effect of core bone diameter variation on the biomechanical properties of a reconstructed ACL using BASHTI technique. MethodsA number of 15 laboratory samples of reconstructed ACL were built using bovine digital tendons and Sawbones blocks. Samples were divided into three groups with different core bone diameters of 8 mm, 8.5 mm, and 9 mm. The double-stranded tendon size and bone tunnel diameter were 8 mm and 10 mm, respectively. A loading scenario consisting of two cyclic loadings followed by a single cycle pull-out loading was applied to the samples simulating the after-surgery loading conditions to observe the fixation strength. ResultsResults showed that the core bone diameter had a significant effect on the failure mode of the samples (P = 0.006) and their fixation strength (P < 0.001). Also, it was observed that the engaging length and the average cyclic stiffness (ACS) of them were influenced by the core bone diameter significantly (engaging length: P = 0.001, ACS: P = 0.007), but its effect on the average pull-out stiffness was not significant (P = 0.053). ConclusionsIt was concluded that core bone diameter variation has a significant impact on the mechanical properties of ACL reconstruction when BASHTI technique is used, and it should be noted for surgeons who use BASHTI technique. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/452098v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@33ca50org.highwire.dtl.DTLVardef@276f38org.highwire.dtl.DTLVardef@f6e66forg.highwire.dtl.DTLVardef@192b117_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIA new implant-less technique was used to reconstruct anterior cruciate ligament. C_LIO_LIArtificial bone and fresh animal soft tissue used to simulate the fixation process. C_LIO_LILoading condition were carefully chosen to simulate the post-operation. C_LIO_LIComponents geometry had direct effect on biomechanical properties of the fixation. C_LIO_LIOptimum geometry was found trough an experimental examination. C_LI

bioengineering↗

bioRxiv2021

Concept design of a bionic grasp to capture the hand motion

This study has focused on designing a device allowing the user to perform hand exercise motions, in relation with previous methods with good effects in stroke rehabilitation. The project is mainly aimed at designing a low cost, easy to handle and easy to manufacture smart glove to assist users with finger flexion and extensions, which can at the same time transfer data to an application. The methodology used here includes research, design, simulation testing and finalised design. It started with research and investigations on the needs of the users and previous efficient stroke rehabilitation methods. This has been followed with 4 concept designs, which has been tested and evaluated in the next stage for possible optimizations using a computer modelling technique. At the final step, the virtual prototype and product design specification (PDS) of the finalise concept for the interactive device has been illustrated.

bioengineering↗

bioRxiv2020

Smart bionic graspers: background study and design process

This paper has focused on reviewing passive bionic grasper and designing a virtual prototype using a computer modelling technique. The main aim of this study is to review existing research and compare their functionalities. This has been followed by introducing a concept design with suitable components. To start the project, generating a clear overview form the most updated and relative knowledge and information on existing designs was the intention of the study. The concept design part of this study uses an iterative process (similar to the Double Diamond Model introduced by Frances et al (2019)) including Discover, Define, Develop and Deliver to complete the design components. Following the concept design process, the detailed theoretical considerations and the features of components selection were then defined. In Develop Phase, the goal was to decide the final design and generate the computer model using SolidWorks. The fourth phase of process was Delivery leading the design evaluation and validation of the generated model or virtual prototype. By completing the process, it is possible to determine the feasibility of the design and the need for improvement. In final stage of the design, a finite element approach using SolidWorks Simulation was performed on the concept. Final design was decided after comparing the concepts in terms of several considerations. A series of simulations were performed on the design to evaluate the durability of the design and extend its functionality. The results showed that the supporting pad was robust enough when dropped down from 1.5 meters height, while the hinge which connecting the finger straps would need further improvement to avoid failure during its practical loading.

bioengineering↗

bioRxiv2020

Biomechanical Modeling of a Bone Tunnel Enlargement Post ACL Reconstruction

BackgroundBone tunnel enlargement is considered as a potential problem following ACL reconstruction and can cause a fixation failure and complicate its revision surgery. This study evaluates post tibial tunnel expansion in ACL reconstruction using an interference screw. MethodsA series of in-vitro experimental tests on animal bone and tissues were used to simulate post ACL reconstruction. The study believes an unbalanced lateral force can cause a local enlargement on the contact zone inside the tunnel. Grayscale X-ray images were used to assess the screw alignment inside the tunnel. ResultsThey showed a slight misalignment between the screw and the tunnel axis as the tendon strands moved along the side of the tunnel, and the screw had partial contact with the tendon and bone along the tunnel. According to the results, increased stress in the tunnel wall causes tunnel enlargement. Although the tunnel created away from the tibial central axis produced a higher strength, it results in higher stress on the wall of the tunnel which can increase the risk of tunnel expansion. ConclusionsThe current study believes the use of an unguided interference screw insertion potentially increases risks of the misaligned fixation and cause a tunnel enlargement. This risk may be controlled by restricting the post-operative rehabilitation.

bioengineering↗