Recent highly accurate sound velocity measurements reveal a phase transition to a competing phase in YBa2Cu3O6+δ that is not identified in available specific heat measurements. We show that this signature is consistent with the universality class of the loop current-ordered state when the free-energy reduction is similar to the superconducting condensation energy, due to the anomalous fluctuation region of such a transition. We also compare the measured specific heat with some usual types of transitions, which are observed at lower temperatures in some cuprates, and find that the upper limit of the energy reduction due to them is about 1/40th the superconducting condensation energy.

© 2014 IEEE. We consider a class of multibody robotic systems inspired by dynamics of animal locomotion, such as swimming and crawling. Distinctive properties of such systems are that the stiffness matrix is asymmetric due to skewed restoring force from the environment, and the damping matrix is a scalar multiple of the inertia matrix when the body is flat like those of fish. Extending the standard notion to this class, we define the natural oscillation as a free response under the damping compensation to yield marginal stability. The natural oscillation of the body provides a basic gait for locomotion. We propose a class of simple nonlinear feedback controllers to achieve entrainment to the natural oscillation of the body, resulting in a prescribed average velocity. As an example, a link chain system with symmetric mechanical structure is considered, and its natural oscillation is shown to exhibit traveling waves appropriate for undulatory locomotion. Controllers are designed under various conditions to achieve prescribed locomotion speeds by natural oscillations. In particular, it is shown how design parameters can be chosen to increase the rate of convergence, and how the locomotion speed can be set by adjusting the natural frequency through body stiffness compensation.

Confocal microscopy is a powerful tool that has been used in the development of 3D profilometers for depth-section image capture and surface measurements. Previously developed confocal microscopes operate by scanning a single point, or array of points, over the surface of a sample. The 3D profilometer we constructed acquires measurement data using a confocal microscopy technique, where transverse surface (x, y) scanning is performed by a digital micromirror device (DMD). The DMD is imaged onto the object's surface allowing for confocal surface scanning of the field of view at a rate faster than video rate without physical movement of the sample. 3D reconstruction is performed a posteriori from stacks of 2D image planes acquired at different depths. A description of the experimental setup with system design issues and solutions are presented. Backscatter noise and diffraction noise due to the periodic micromirror structure is minimized using spatial filtering and polarization coding techniques. Using a 100× objective, the longitudinal point spread function (FWHM) was measured at 2.1 μm, with simultaneous transverse resolution of 228.0 lines/mm. The optical resolution performance of our microscope with real-time scanning provided by the DMD, is shown to be effectively equivalent to those of conventional confocal microscopes. The 3D image capabilities of our scanning system using the DMD were demonstrated on various objects.

Cerebral deposition of amyloid β protein (Aβ) is an invariant feature of Alzheimer disease (AD), and epidemiological evidence suggests that moderate consumption of foods enriched with phenolic compounds reduce the incidence of AD. We reported previously that the phenolic compounds myricetin (Myr) and rosmarinic acid (RA) inhibited Aβ aggregation in vitro and in vivo. To elucidate a mechanistic basis for these results, we analyzed the effects of five phenolic compounds in the Aβ aggregation process and in oligomer-induced synaptic toxicities. We now report that the phenolic compounds blocked Aβ oligomerization, and Myr promoted significant NMR chemical shift changes of monomeric Aβ. Both Myr and RA reduced cellular toxicity and synaptic dysfunction of the Aβ oligomers. These results suggest that Myr and RA may play key roles in blocking the toxicity and early assembly processes associated with Aβ through different binding.