What are the challenges in making aligned myotubes?5 answersChallenges in creating aligned myotubes include the difficulty in inducing controlled alignment of cells on traditional two-dimensional substrates, the need for tailored microenvironmental inputs to promote alignment and maturation of myotubes in microfluidic devices, and the issue of myotube delamination from synthetic culture substrates during differentiation from myoblasts. Strategies to overcome these challenges involve utilizing plant-derived cellulose biomaterials to guide cell alignment, integrating topological constraints in microfluidic channels to mimic native anisotropic organization of skeletal muscle cells, and using micromolded gelatin hydrogels as culture substrates to maintain aligned myotubes for extended periods. These approaches aim to replicate in vivo conditions and provide insights for tissue engineering, disease modeling, and drug testing applications.
How does position level affect the use of a system?5 answersIncreasing the degrees of freedom of robotic systems makes them more versatile and flexible. This usually renders the system kinematically redundant: the main manipulation or interaction task does not fully determine its joint maneuvers. Additional constraints or objectives are required to solve the under-determined control and planning problems. The state-of-the-art approaches arrange tasks in a hierarchy and decouple lower from higher priority tasks on velocity or torque level using projectors. We develop an approach to redundancy resolution and decoupling on position level by determining subspaces of the configurations space independent of the primary task. We call them orthogonal foliations because they are, in a certain sense, orthogonal to the task self-motion manifolds. The approach provides a better insight into the topological properties of robot kinematics and control problems, allowing a global view. A condition for the existence of orthogonal foliations is derived. If the condition is not satisfied, we will still find approximate solutions by numerical optimization. Coordinates can be defined on these orthogonal foliations and can be used as additional task variables for control. We show in simulations that we can control the system without the need for projectors using these coordinates, and we validate the approach experimentally on a 7-DoF robot.
Are there any positional statistics?5 answersPositional statistics are discussed in several of the abstracts. Needham and Boyle present metrics for evaluating the performance of positional trackers in determining the position of a target object. Chun and Griffith investigate how positional errors in georeferenced data affect spatial statistical analyses and the confidence intervals of regression coefficients. Cuartero et al. propose a method using circular statistics to analyze positional accuracy errors in satellite images. Thamrongpairoj and Remmel define and study positional marked patterns in permutations, introducing a new class of statistics.
How does car alignment affect racing performance?5 answersCar alignment can have a significant impact on racing performance. Proper wheel alignment can improve coast down characteristics, which are important for calculating fuel efficiency and overall performance. Wheel alignments within the vehicle architecture can affect the vehicle's dynamic performance and should be optimized within the performance bandwidth. Additionally, alignment verification locations can be used to monitor and assess alignment, with an alignment score determined based on the distance between the verification locations and alignment targets. If the alignment score is below a threshold, alignment setup can be performed. Therefore, ensuring proper car alignment can contribute to improved racing performance by optimizing fuel efficiency, dynamic performance, and alignment accuracy.
Why is random initialization of atom positions for molecular dynamics simulations bad?5 answersRandom initialization of atom positions for molecular dynamics simulations can lead to inaccurate results. The high stochasticity of collision cascades in these simulations requires running large sets of simulations to obtain meaningful statistics. However, random initialization alone does not guarantee convergence of results. It has been observed that larger sets of simulations are needed to converge the penetration depth of primary knock-on atoms (PKAs) compared to the number of clusters and defects. Additionally, the higher the energy of the PKA, the harder it becomes to reach convergence. On the other hand, using symmetry considerations in setting the initial directions of PKAs can ease the convergence of results. Therefore, random initialization of atom positions may not provide accurate and reliable results in molecular dynamics simulations, and alternative methods should be considered to improve convergence and eliminate the influence of initial positions.
What is positionality?4 answersPositionality refers to the personal and social constructs that shape our identity and influence how we perceive and interpret the world around us. It recognizes that researchers and participants in qualitative studies have their own unique positions and perspectives that can impact the research process and outcomes. Positionality challenges the notion of a neutral observer and emphasizes the importance of acknowledging and embracing our social position as researchers. It involves being reflexive about our biases, values, privileges, and identities, and how they may influence our research. Positionality also highlights the role of power dynamics and relationships in research, particularly in ethnographic studies. By considering positionality, researchers can uncover hidden aspects of the lived experience and enhance the rigor of qualitative research. Additionally, understanding positionality can raise awareness of power dynamics, subjectivity, and ethical considerations in design work and research.