Search results for "quantitative"
showing 10 items of 2409 documents
Magnetic dipole with a flexible tail as a self-propelling microdevice.
2012
By numerical simulations, it is illustrated that a magnetic dipole with a flexible tail behaves as a swimmer in AC magnetic fields. The behavior of the swimmer on long time scales is analyzed and it is shown that due to the flexibility of the tail two kinds of torques arise, the first is responsible for the orientation of the swimmer perpendicularly to the AC field and the second drags the filament in the direction of the rotating field. Due to this, circular trajectories of the swimmer are possible; however, these are unstable. The self-propulsion velocity of this swimmer is higher than the velocities of other magnetic microdevices for comparable values of the magnetoelastic number.
Ballistic phonon transport in dielectric membranes
2006
We have calculated the ballistic phononic heat transport in dielectric membranes as a function of radiator temperature and membrane thickness. The phonon modes of such membranes are known as Lamb-modes from elasticity theory. The striking result is that, for a fixed temperature, the radiated power first decreases with decreasing membrane thickness, but then develops a minimum when the transition to two dimensionality is reached. Further decrease of the membrane thickness in the 2D limit leads to increasing radiated power.
Excitation Transport in Helical Proteins
1994
Recent results for excitation dynamics in and IR-absorption spectrum of helical polypeptides are briefly reviewed.
Membrane-mediated Protein-protein Interaction: A Monte Carlo Study
2012
We investigate membrane-mediated interactions between transmembrane proteins using coarse-grained models. We compare the effective potential of mean force (PMF) between two proteins, which are always aligned parallel to the z-axis of the simulation box, with those PMFs obtained for proteins with fluctuating orientations. The PMFs are dominated by an oscillatory packing-driven contribution and a smooth attractive hydrophobic mismatch contribution, which vanishes if the hydrophobic length of the protein matches the thickness of the membrane. If protein orientations are allowed to fluctuate, the oscillations are greatly reduced compared to proteins with fixed orientation. Furthermore, the hydr…
Hydrodynamic synchronization of pairs of puller type magnetotactic bacteria in a high frequency rotating magnetic field.
2019
Ensembles of magnetotactic bacteria are known to interact hydrodynamically and form swarms under the influence of external magnetic fields. We describe the synchronization of puller type magnetotactic bacteria in a rotating magnetic field by representing the bacteria as hydrodynamic force dipoles. Numerical simulations show that at moderate values of the hydrodynamic interaction parameter large ensembles of asynchronously rotating bacteria randomly eject propagating doublets of synchronized bacteria. We quantitatively analyze the dynamics of the doublets and show that an important role in the formation of these propagating structures is played by the parameters characterizing the possible t…
Ewald sum for hydrodynamic interactions of rigid spherical microswimmers
2018
We derive the Ewald sum decomposition of the grand mobility tensor which captures the hydrodynamic interactions in an infinite suspension of rigid spherical microswimmers. The grand mobility tensor connects the motion of an individual swimmer to the active and passive forces and torques acting on all the swimmers, and it is calculated based on a minimal microswimmer model incorporating the swimmers' finite body size. Our results have direct applications to the Stokesian dynamics simulations of an infinite suspension of rigid-bodied microswimmers. They also provide a platform to develop more advanced methods such as particle-mesh-Ewald-sum and accelerated Stokesian dynamics simulations.
Current-induced H-shaped-skyrmion creation and their dynamics in the helical phase
2021
Abstract Inevitable for the basic principles of skyrmion racetrack-like applications is not only their confined motion along one-dimensional channels but also their controlled creation and annihilation. Helical magnets have been suggested to naturally confine the motion of skyrmions along the tracks formed by the helices, which also allow for high-speed skyrmion motion. We propose a protocol to create topological magnetic structures in a helical background. We furthermore analyse the stability and current-driven motion of the skyrmions in a helical background with in-plane uniaxial anisotropy fixing the orientation of the helices.
Photon antibunching and collective effects in the fluorescence of single bichromophoric molecules.
2003
The fluorescence of individual pairs of perylenemonoimide chromophores coupled via a short rigid linker is investigated. Photon antibunching is reported, indicating collective effects in the fluorescence, which are further substantiated by the observation of collective triplet off times and triplet lifetime shortening. The experimental findings are analyzed in terms of singlet-singlet and singlet-triplet annihilation based on Forster type energy transfer. The results reported here demonstrate that the statistical properties of the emission light of isolated single quantum systems can serve as a hallmark of intermolecular interactions.
Dynamics of breather modes in a nonlinear “helicoidal” model of DNA
1991
Via a recent model with an additional helicoidal coupling, the dynamics of breathers modes in DNA are studied analytically and with the use of numerical simulations. It is shown that these excitations are longlived and can match experimentally observed fluctuational openings.
Plenary talk - non coaxial force and inductance calculations for bitter coils and coils with uniform radial current distributions
2011
Recently the Bessel function approach to calculating the magnetic fields of coils has been used to calculate the mutual inductance and the force between two non coaxial thick cylindrical coils with parallel axes and uniform radial current distributions. This method can also be applied to calculate the force and inductance between an ordinary coil and a Bitter coil, or between two bitter coils, not necessarily coaxial. Bitter coils give a simpler case of the method, and it is possible to solve analytically for the magnetic field of a bitter disk.