Overall, balance training appears to be the most effective exercise intervention. Studies focusing exclusively on strength, or a combination of endurance and strength, appear to have a lower impact. For metabolically-induced neuropathies, endurance training also plays an important role. Further research with high methodological quality needs to be conducted in order to establish evidence-based clinical recommendations for neuropathic patients.

We introduce smectic freely floating microbubbles and report their unusual dynamic properties. In equilibrium, they form minimal surfaces like soap films, but shape transformations of closed smectic membranes not in contact with menisci involve complex layer rearrangements. Very small distortions of the spherical equilibrium shape can relax by damped oscillations, driven by surface tension. Larger film area changes require the creation and motion of islands and layer dislocations. Then, film area changes are slow compared to natural oscillation frequencies. Quasistationary intermediate shapes evolve on the time scale of dislocation dynamics. These shape transformations are reminiscent of vesicles, in which the surface tension is effectively zero. We prepare smectic shells from collapsing catenoids and analyze their behavior with optical highspeed imaging.

A new series of azobenzene containing bent-core molecules incorporating 4-cyanoresorcinol as the central core unit exhibiting cybotactic nematic, rectangular, columnar, and different types of tilted smectic (SmC) phases are synthesized. The mesophase behavior and phase structures are characterized in bulk and freely suspended fi lms using a variety of experimental techniques. Depending on the chain length and temperature a series of different mesophases is observed in these compounds, ranging from cybotactic nematic via paraelectric SmC phases, polarization randomized SmC s P R phases to ferroelectric and antiferroelectric SmC phases, associated with increasing size and correlation length of the polar domains. Spontaneous formation of chiral domains is observed in the paraelectric SmC and the SmC s P R phases and discussed in relation with superstructural chirality, bend elastic constants, and surface effects.

We demonstrate spontaneous wrinkling as a transient dynamical pattern in thin freely floating smectic liquid-crystalline films. The peculiarity of such films is that, while flowing liquid-like in the film plane, they cannot quickly expand in the direction perpendicular to that plane. At short time scales they therefore behave in two dimensions like quasi-incompressible membranes. Such films can develop a transient undulation instability or form bulges in response to lateral compression. Optical experiments with freely floating bubbles on parabolic flights and in ground lab experiments are reported. The characteristic wavelengths of the wrinkles are in the submillimeter range. We demonstrate the dynamic nature of the pattern formation mechanism and develop a basic model for the wavelength selection and wrinkle orientation. arXiv:1809.08082v2 [cond-mat.soft]

We have investigated the dynamics of freely floating smectic bubbles using high-speed optical imaging. Bubbles in the size range from a few hundred micrometers to several centimeters were prepared from collapsing catenoids. They represent ideal model systems for the study of thin-film fluid dynamics under well-controlled conditions. Owing to the internal smectic layer structure, the bubbles combine features of both soap films and vesicles in their unique shape dynamics. From a strongly elongated initial shape after pinch-off, they relax towards the spherical equilibrium, first by a slow redistribution of the smectic layers, and finally by weak, damped shape oscillations. In addition, we describe the rupture of freely floating smectic bubbles, and the formation and stability of smectic filaments.

No abstract

Using experiments and molecular dynamics simulations, we explore magnetic field-induced phase transformations in suspensions of nonmagnetic rodlike and magnetic sphere-shaped particles. We experimentally demonstrate that an external uniform magnetic field causes the formation of small, stable clusters of magnetic particles that, in turn, induce and control the orientational order of the nonmagnetic subphase. Optical birefringence was studied as a function of the magnetic field and the volume fractions of each particle type. Steric transfer of the orientational order was investigated by molecular dynamics (MD) simulations; the results are in qualitative agreement with the experimental observations. By reproducing the general experimental trends, the MD simulation offers a cohesive bottom-up interpretation of the physical behavior of such systems, and it can also be regarded as a guide for further experimental research.

We study the meniscus profiles of ferrofluids in the magnetic field of a vertical current-carrying wire. Measurements of the free ferrofluid surface profile are quantitatively compared with numerical calculations. The theoretical model leads to a second-order ordinary differential equation. All material parameters are determined in independent experiments, therefore no fitting parameters are involved in the calculations. The experimental results can be modeled by the equilibrium of magnetic, gravitational, and interface tension forces. The classical model that neglects interface tension yields significant deviations from the experimental profiles in the parameter range studied.