Abstract

This study investigates the thermal noise characteristics of **ultrashort elastic membrane nanotubes**, structures critical for various cellular processes including vesicle trafficking and cell-cell communication. The primary objective is to quantify the influence of the nanotube's finite length and elasticity on its dynamic stability and fluctuation spectrum. Using a theoretical framework based on the Helfrich elastic energy model, coupled with Langevin dynamics simulations, we analyzed the spectral density of radius fluctuations. Our methods specifically account for the boundary conditions imposed by the ultrashort geometry, which significantly deviates from the behavior of infinitely long tethers. Key findings reveal that the noise spectrum is dominated by a single, low-frequency mode, whose amplitude is inversely proportional to the nanotube's length and directly proportional to its bending rigidity. This suggests that the thermal noise in these ultrashort structures is highly sensitive to local membrane properties and geometric constraints. These results provide crucial insights into the physical mechanisms governing the stability and function of membrane tethers, offering a foundation for understanding mechanosensing and material transport at the nanoscale within living cells.