Interaural time differences allow many animals to perform azimuthal sound localization. Snakes lack a tympanic membrane, external ear openings, and any other superficial indication of an auditory mechanism. They do, however, possess an inner ear with functional cochlea. The oval window is connected through a loss-free osseous lever system to the two, de facto independent, sides of the lower jaw, which typically rest on the substrate. The footfall of prey generates small-amplitude, low propagation velocity, Rayleigh waves in the soil. This type of wave can be described as fluid motion. Accordingly we apply naval-engineering techniques to show that lower-jaw motion gives rise to a neuronal representation of the auditory world with realistic sensitivity and stereo precision.

We examine the surface morphological evolution of a conducting crystalline solid under the simultaneous action of an electric field and mechanical stress based on a fully nonlinear model and combining linear stability theory with self-consistent dynamical simulations. We demonstrate that electric current, through surface electromigration, can stabilize the surface morphology of the stressed solid against cracklike surface instabilities. The results also have more general implications for the morphological response of solid surfaces under the simultaneous action of multiple external forces.

Codeposition of ${\mathrm{C}}_{60}$ and the three-dimensional molecular hydrocarbon 1,3,5,7-tetraphenyladamantane (TPA) on Au(111) leads to the spontaneous formation of molecular nanostructures in which each fullerene is locked into a specific orientation by three surrounding TPA. Scanning tunneling spectroscopy shows that the electronic coupling of ${\mathrm{C}}_{60}$ with the surface is significantly reduced in these nanostructures, enhancing the free-molecule properties. As evidenced by density functional theory simulations, the nanostructures are stabilized by 18 local electrostatic forces between ${\mathrm{C}}_{60}$ and TPA, resulting in a lifting of the ${\mathrm{C}}_{60}$ cage from the surface.

By means of time-resolved electron crystallography, we report direct observation of the structural dynamics of graphite, providing new insights into the processes involving coherent lattice motions and ultrafast graphene ablation. When graphite is excited by an ultrashort laser pulse, the excited carriers reach their equilibrium in less then one picosecond by transferring heat to a subset of strongly coupled optical phonons. The time-resolved diffraction data show that on such a time scale the crystal undergoes a contraction whose velocity depends on the excitation fluence. The contraction is followed by a large expansion which, at sufficiently high fluence, leads to the ablation of entire graphene layers, as recently predicted theoretically.

A crucial point in the debate on the feasibility of earthquake predictions is the dependence of an earthquake magnitude from past seismicity. Indeed, while clustering in time and space is widely accepted, much more questionable is the existence of magnitude correlations. The standard approach generally assumes that magnitudes are independent and therefore in principle unpredictable. Here we show the existence of clustering in magnitude: earthquakes occur with higher probability close in time, space, and magnitude to previous events. More precisely, the next earthquake tends to have a magnitude similar but smaller than the previous one. A dynamical scaling relation between magnitude, time, and space distances reproduces the complex pattern of magnitude, spatial, and temporal correlations observed in experimental seismic catalogs.

The destabilization process of an emulsion under flow is investigated in a microfluidic device. The experimental approach enables us to generate a periodic train of droplet pairs, and thus to isolate and analyze the basic step of the destabilization, namely, the coalescence of two droplets which collide. We demonstrate a counterintuitive phenomenon: coalescence occurs during the separation phase and not during the impact. Separation induces the formation of two facing nipples in the contact area that hastens the connection of the interfaces prior to fusion. Moreover, droplet pairs initially stabilized by surfactants can be destabilized by forcing the separation. Finally, we note that the fusion mechanism is responsible for a cascade of coalescence events in a compact system of droplets where the separation is driven by surface tension.

We study the formation of shock waves in a nanomechanical resonator with an embedded two-dimensional electron gas using surface acoustic waves. The mechanical displacement of the nanoresonator is read out via the induced acoustoelectric current. Applying acoustical standing waves, we are able to determine the so-called anomalous acoustocurrent. This current is found only in the regime of shock wave formation.

Through acoustic scattering theory we derive the mass density and bulk modulus of a spherical shell that can eliminate scattering from an arbitrary object in the interior of the shell—in other words, a 3D acoustic cloaking shell. Calculations confirm that the pressure and velocity fields are smoothly bent and excluded from the central region as for previously reported electromagnetic cloaking shells. The shell requires an anisotropic mass density with principal axes in the spherical coordinate directions and a radially dependent bulk modulus. The existence of this 3D cloaking shell indicates that such reflectionless solutions may also exist for other wave systems that are not isomorphic with electromagnetics.

We present a method for the calculation of the low frequency vibrational modes and frequencies of viral capsids, or other large molecules, where the modes are modeled with atomic detail. Extending ideas from electronic structure theory, an energy functional is used to find modes of a classical dynamical matrix below a fixed (pseudo-Fermi) level. The icosahedral satellite tobacco necrosis virus is modeled as an example. We find that atoms around the $C5$ and $C3$ axis have small relative displacement while the $\beta$ sheet body shows gliding motion.

We report on the generation of a quantum degenerate Fermi-Fermi mixture of two different atomic species. The quantum degenerate mixture is realized employing sympathetic cooling of fermionic ${}^6\mathrm{Li}$ and ${}^{40}\mathrm{K}$ gases by an evaporatively cooled bosonic ${}^{87}\mathrm{Rb}$ gas. We describe the combination of trapping and cooling methods that proved crucial to successfully cool the mixture. In particular, we study the last part of the cooling process and show that the efficiency of sympathetic cooling of the ${}^6\mathrm{Li}$ gas by ${}^{87}\mathrm{Rb}$ is increased by the presence of ${}^{40}\mathrm{K}$ through catalytic cooling. Because of the differing physical properties of the two components, the quantum degenerate ${}^6\mathrm{Li}\mathrm{\text{−}}{}^{40}\mathrm{K}$ Fermi-Fermi mixture is an excellent candidate for a stable, heteronuclear system allowing the study of several so far unexplored types of quantum matter.

When plasmodia of the true slime mold Physarum were exposed to unfavorable conditions presented as three consecutive pulses at constant intervals, they reduced their locomotive speed in response to each episode. When the plasmodia were subsequently subjected to favorable conditions, they spontaneously reduced their locomotive speed at the time when the next unfavorable episode would have occurred. This implied the anticipation of impending environmental change. We explored the mechanisms underlying these types of behavior from a dynamical systems perspective.

We report that a full three-dimensional (3D) photonic band gap (PBG) is formed in a photonic amorphous structure in spite of complete lack of lattice periodicity. It is numerically shown that the structure “photonic amorphous diamond” possesses a sizable 3D PBG (18% of the center frequency for Si-air dielectric contrast) and that it can confine light at a defect as strongly as conventional photonic crystals can. These findings present important new insight into the origin of 3D PBG formation and open new possibilities in developing 3D PBG materials.

The broadband, coherent nature of narrow-linewidth fiber frequency combs is exploited to measure the full complex spectrum of a molecular gas through multiheterodyne spectroscopy. We measure the absorption and phase shift experienced by each of 155 000 individual frequency-comb lines, spaced by 100 MHz and spanning from 1495 to 1620 nm, after passing through hydrogen cyanide gas. The measured phase spectrum agrees with the Kramers-Kronig transformation of the absorption spectrum. This technique can provide a full complex spectrum rapidly, over wide bandwidths, and with hertz-level accuracy.

We have observed the persistent flow of Bose-condensed atoms in a toroidal trap. The flow persists without decay for up to 10 s, limited only by experimental factors such as drift and trap lifetime. The quantized rotation was initiated by transferring one unit of the orbital angular momentum from Laguerre-Gaussian photons to each atom. Stable flow was only possible when the trap was multiply connected, and was observed with a Bose-Einstein condensate fraction as small as 20%. We also created flow with two units of angular momentum and observed its splitting into two singly charged vortices when the trap geometry was changed from multiply to simply connected.

We report on the first measurement of the ${\beta }^{+}$ and orbital electron-capture decay rates of ${}^{140}\mathrm{Pr}$ nuclei with the simplest electron configurations: bare nuclei, hydrogenlike, and heliumlike ions. The measured electron-capture decay constant of hydrogenlike ${}^{140}\mathrm{Pr}^{58+}$ ions is about 50% larger than that of heliumlike ${}^{140}\mathrm{Pr}^{57+}$ ions. Moreover, ${}^{140}\mathrm{Pr}$ ions with one bound electron decay faster than neutral ${}^{140}\mathrm{Pr}^{0+}$ atoms with 59 electrons. To explain this peculiar observation one has to take into account the conservation of the total angular momentum, since only particular spin orientations of the nucleus and of the captured electron can contribute to the allowed decay.

The root-mean-square (rms) nuclear charge radius of ${}^8\mathrm{He}$, the most neutron-rich of all particle-stable nuclei, has been determined for the first time to be 1.93(3) fm. In addition, the rms charge radius of ${}^6\mathrm{He}$ was measured to be 2.068(11) fm, in excellent agreement with a previous result. The significant reduction in charge radius from ${}^6\mathrm{He}$ to ${}^8\mathrm{He}$ is an indication of the change in the correlations of the excess neutrons and is consistent with the ${}^8\mathrm{He}$ neutron halo structure. The experiment was based on laser spectroscopy of individual helium atoms cooled and confined in a magneto-optical trap. Charge radii were extracted from the measured isotope shifts with the help of precision atomic theory calculations.

We have measured the nuclear transparency of the $A(e,e^{\prime }{\pi }^{+})$ process in ${}^2\mathrm{H}$, ${}^{12}\mathrm{C}$, ${}^{27}\mathrm{Al}$, ${}^{63}\mathrm{Cu}$, and ${}^{197}\mathrm{Au}$ targets. These measurements were performed at the Jefferson Laboratory over a four momentum transfer squared range $Q^2=1.1$ to $4.7(\mathrm{GeV}/c{)}^2$. The nuclear transparency was extracted as the super-ratio of (${\sigma }_A/{\sigma }_H$) from data to a model of pion-electroproduction from nuclei without $\pi \mathrm{\text{−}}N$ final-state interactions. The $Q^2$ and atomic number dependence of the nuclear transparency both show deviations from traditional nuclear physics expectations and are consistent with calculations that include the quantum chromodynamical phenomenon of color transparency.

We study the thermally activated transition from amorphous to crystalline ice (${\mathrm{D}}_2\mathrm{O}$) on Cu(111) with high-resolution scanning tunneling microscopy. Annealing of amorphous solid water up to the desorption temperature of 149 K results subsequently in monomer decorated double bilayers with different superstructure, a faceted surface, pyramidal islands, and nanocrystallites of distinct height at different coverages. Though all structures are truncations from crystalline water ice, for none of them is the ice bilayer found to be the terminating surface.

We establish the existence of a chiral spin liquid (CSL) as the exact ground state of the Kitaev model on a decorated honeycomb lattice, which is obtained by replacing each site in the familiar honeycomb lattice with a triangle. This CSL state spontaneously breaks time reversal symmetry but preserves other symmetries. There are two topologically distinct CSL’s separated by a quantum critical point. Interestingly, vortex excitations in the topologically nontrivial (Chern number $\pm 1$) CSL obey non-Abelian statistics.

It has been predicted, but never confirmed, that colloidal particles in a nematic liquid crystal could be self-assembled by delocalized topological defects and entangled disclinations. We show experimentally and theoretically that colloidal dimers and 1D structures bound by entangled topological defect loops can indeed be created by locally thermally quenching a thin layer of the nematic liquid crystal around selected colloidal particles. The topological entanglement provides a strong stringlike binding, which is ten thousand times stronger compared to water-based colloids. This unique binding mechanism could be used to assemble resonator optical waveguides and robust chiral and achiral structures of topologically entangled colloids that we call colloidal wires.