Volume 12 Issue 12, December 2016

Quasiparticles are an extremely useful concept that provides a more intuitive understanding of complex phenomena in many-body physics. As such, they appear in various contexts, linking ideas across different fields and supplying a common language.

Dendritic cells use components of their cytoskeleton to both move and ingest pieces of infected cells. This competition for protein resources can give rise to a complex set of states that may be understood with an advection–diffusion model.

Direct satellite observations of energy transfer between large and small space plasma scales contribute to our understanding of how matter in the Universe gets hot.

The control of long-range interactions is an essential ingredient for the study of exotic phases of matter using atoms in optical lattices. Such control is demonstrated using Rydberg dressing: the coupling of ground state atoms to Rydberg states.

The prediction of an antiferromagnetic semimetal that breaks both time-reversal and inversion symmetry but respects their combination could provide a platform for studying the interplay between Dirac fermions and magnetism.

Observations of topological surface states provide strong evidence that MoTe₂ is a type-II Weyl semimetal, hosting Weyl fermions that have no counterpart in high-energy physics.

Images of the second-generation Dirac cones that form when graphene is placed on hexagonal boron nitride show the potential of using superlattices to engineer the electronic band structure of van der Waals heterostructures.

The interaction between the outflow of gas from a quasar and the interstellar medium can boost protons to relativistic energies. Collisions between such protons can explain a significant fraction of the unexplained extragalactic gamma-ray background.

The anomalous Hall effect is usually associated with ferromagnets but a large anomalous Hall response can be found in topologically non-trivial half-Heusler antiferromagnets thanks to Berry phase effects associated with symmetry breaking.

The acoustic analogue of a topological insulator is shown: a metamaterial exhibiting one-way sound transport along its edge. The system — a graphene-like array of stainless-steel rods — is a promising new platform for exploring topological phenomena.

The response of amorphous solids to external stress is not very well understood. A study now shows that certain glasses, upon decreasing temperature, undergo a phase transition characterized by diverging nonlinear elastic moduli.

A colloidal particle connected to suspensions of motile bacteria forms a model system for studying microscale engines in contact with active baths. The engine outperforms its passive counterparts due to the presence of non-Gaussian fluctuations.

Parity–time symmetry in optics is studied in a warm atomic vapour, where its counterpart, anti-parity–time symmetry, as well as refractionless propagation, can also be observed.

Cell motility is typically described as a random walk due to the presence of noise. But a dynamical model suggests that dendritic cells move deterministically, alternating between fast and slow motility, and exhibiting periodic polarity reversals.

Animals moving in groups are expected to differ from their many-body counterparts in equilibrium. A method based on maximum entropy shows that the interactions in starling flocks rearrange slowly enough to permit an equilibrium description locally.

Substorms in the Earth’s magnetosphere lead to bright aurorae, releasing energy into the surrounding ionosphere. Ground- and space-based observations now reveal how that energy is dissipated and controlled by strong electric currents.

Processes in (space) plasmas occur on different levels — fluid, ion and electron. Now, from satellite data and simulations, an energy-transfer mechanism between the fluid and ion scales is reported: fluid velocity shear is converted into ion heating.

A high-resolution age map of the Milky Way picks out structures that validate the most widely accepted cosmological theory, lambda cold dark matter. The chronographic data are also used to probe the chemodynamical formation history of our Galaxy.

Every now and then, an extra second is added to an earthly year — a cause for trouble and debate, as Felicitas Arias has been witnessing.