Purpose:The aim of this study was to extend current half-sarcomere models by involving a recently found force-mediated activation of the thick filament and analyze the effect of this mechanosensing regulation on the l...Purpose:The aim of this study was to extend current half-sarcomere models by involving a recently found force-mediated activation of the thick filament and analyze the effect of this mechanosensing regulation on the length stability of half-sarcomeres arranged in series.Methods:We included a super-relaxed state of myosin motors and its force-dependent activation in a conventional cross-bridge model.We simulated active stretches of a sarcomere consisting of 2 non-uniform half-sarcomeres on the descending limb of the force-length relationship.Results:The mechanosensing model predicts that,in a passive sarcomere on the descending limb of the force-length relationship,the longer half-sarcomere has a higher fraction of myosin motors in the on-state than the shorter half-sarcomere.The difference in the number of myosin motors in the on-state ensures that upon calcium-mediated thin filament activation,the force-dependent thick filament activation keeps differences in active force within 20%during an active stretch.In the classical cross-bridge model,the corresponding difference exceeds 80%,leading to great length instabilities.Conclusion:Our simulations suggest that,in contrast to the classical cross-bridge model,the mechanosensing regulation is able to stabilize a system of non-uniform half-sarcomeres arranged in series on the descending limb of the force-length relationship.展开更多
In this paper,we present a surface reconstruction via 2D strokes and a vector field on the strokes based on a two-step method.In the first step,from sparse strokes drawn by artists and a given vector field on the stro...In this paper,we present a surface reconstruction via 2D strokes and a vector field on the strokes based on a two-step method.In the first step,from sparse strokes drawn by artists and a given vector field on the strokes,we propose a nonlinear vector interpolation combining total variation(TV)and H1 regularization with a curl-free constraint for obtaining a dense vector field.In the second step,a height map is obtained by integrating the dense vector field in the first step.Jump discontinuities in surface and discontinuities of surface gradients can be well reconstructed without any surface distortion.We also provide a fast and efficient algorithm for solving the proposed functionals.Since vectors on the strokes are interpreted as a projection of surface gradients onto the plane,different types of strokes are easily devised to generate geometrically crucial structures such as ridge,valley,jump,bump,and dip on the surface.The stroke types help users to create a surface which they intuitively imagine from 2D strokes.We compare our results with conventional methods via many examples.展开更多
文摘Purpose:The aim of this study was to extend current half-sarcomere models by involving a recently found force-mediated activation of the thick filament and analyze the effect of this mechanosensing regulation on the length stability of half-sarcomeres arranged in series.Methods:We included a super-relaxed state of myosin motors and its force-dependent activation in a conventional cross-bridge model.We simulated active stretches of a sarcomere consisting of 2 non-uniform half-sarcomeres on the descending limb of the force-length relationship.Results:The mechanosensing model predicts that,in a passive sarcomere on the descending limb of the force-length relationship,the longer half-sarcomere has a higher fraction of myosin motors in the on-state than the shorter half-sarcomere.The difference in the number of myosin motors in the on-state ensures that upon calcium-mediated thin filament activation,the force-dependent thick filament activation keeps differences in active force within 20%during an active stretch.In the classical cross-bridge model,the corresponding difference exceeds 80%,leading to great length instabilities.Conclusion:Our simulations suggest that,in contrast to the classical cross-bridge model,the mechanosensing regulation is able to stabilize a system of non-uniform half-sarcomeres arranged in series on the descending limb of the force-length relationship.
基金The research is supported by MOE(Ministry of Education)Tier II project T207N2202and National Research Foundation grant,which is administered by the Media Development Authority Interactive Digital Media Programme Office,MDA(IDMPO).
文摘In this paper,we present a surface reconstruction via 2D strokes and a vector field on the strokes based on a two-step method.In the first step,from sparse strokes drawn by artists and a given vector field on the strokes,we propose a nonlinear vector interpolation combining total variation(TV)and H1 regularization with a curl-free constraint for obtaining a dense vector field.In the second step,a height map is obtained by integrating the dense vector field in the first step.Jump discontinuities in surface and discontinuities of surface gradients can be well reconstructed without any surface distortion.We also provide a fast and efficient algorithm for solving the proposed functionals.Since vectors on the strokes are interpreted as a projection of surface gradients onto the plane,different types of strokes are easily devised to generate geometrically crucial structures such as ridge,valley,jump,bump,and dip on the surface.The stroke types help users to create a surface which they intuitively imagine from 2D strokes.We compare our results with conventional methods via many examples.
