The variation associated with different observable characteristics-phenotypes-at the cellular scale underpins homeostasis and the fitness of living systems. However, if and how these noisy... Show moreThe variation associated with different observable characteristics-phenotypes-at the cellular scale underpins homeostasis and the fitness of living systems. However, if and how these noisy phenotypic traits shape properties at the population level remains poorly understood. Here we report that phenotypic noise self-regulates with growth and coordinates collective structural organization, the kinetics of topological defects and the emergence of active transport around confluent colonies. We do this by cataloguing key phenotypic traits in bacteria growing under diverse conditions. Our results reveal a statistically precise critical time for the transition from a monolayer biofilm to a multilayer biofilm, despite the strong noise in the cell geometry and the colony area at the onset of the transition. This reveals a mitigation mechanism between the noise in the cell geometry and the growth rate that dictates the narrow critical time window. By uncovering how rectification of phenotypic noise homogenizes correlated collective properties across colonies, our work points at an emergent strategy that confluent systems employ to tune active transport, buffering inherent heterogeneities associated with natural cellular environment settings.The first step of biofilm formation is a transition from a single layer of bacteria to multiple layers. Now, there is evidence that this transition is determined by the phenotypic noise associated with cell geometry and growth rate. Show less
Lee, W.S., Zhou, K.; Hepting, M.; Li, J.; Nag, A.; Walters, A.C.; Garcia-Fernandez, M.; ... ; Devereaux, T.P. 2021
Transport experiments in twisted bilayer graphene haverevealed multiple superconducting domes separated by cor-related insulating states 1–5 . These properties are generallyassociated with strongly... Show moreTransport experiments in twisted bilayer graphene haverevealed multiple superconducting domes separated by cor-related insulating states 1–5 . These properties are generallyassociated with strongly correlated states in a flat mini-bandof the hexagonal moiré superlattice as was predicted by bandstructure calculations 6–8 . Evidence for the existence of a flatband comes from local tunnelling spectroscopy 9–13 and elec-tronic compressibility measurements 14 , which report two ormore sharp peaks in the density of states that may be asso-ciated with closely spaced Van Hove singularities. However,direct momentum-resolved measurements have proved to bechallenging 15 . Here, we combine different imaging techniquesand angle-resolved photoemission with simultaneous real- andmomentum-space resolution (nano-ARPES) to directly mapthe band dispersion in twisted bilayer graphene devices nearcharge neutrality. Our experiments reveal large areas with ahomogeneous twist angle that support a flat band with a spec-tral weight that is highly localized in momentum space. The flatband is separated from the dispersive Dirac bands, which showmultiple moiré hybridization gaps. These data establish thesalient features of the twisted bilayer graphene band structure. Show less
The architecture of mechanical metamaterials is designed to harness geometry1,2,3,4,5,6, nonlinearity7,8,9,10,11 and topology11,12,13,14,15 to obtain advanced functionalities such as shape... Show moreThe architecture of mechanical metamaterials is designed to harness geometry1,2,3,4,5,6, nonlinearity7,8,9,10,11 and topology11,12,13,14,15 to obtain advanced functionalities such as shape morphing7,9,16,17,18,19,20,21, programmability18,22,23 and one-way propagation11,13,14. Although a purely geometric framework successfully captures the physics of small systems under idealized conditions, large systems or heterogeneous driving conditions remain essentially unexplored. Here we uncover strong anomalies in the mechanics of a broad class of metamaterials, such as auxetics2,5,24, shape changers16,17,18,19,20,21 or topological insulators11,12,13,15; a non-monotonic variation of their stiffness with system size, and the ability of textured boundaries to completely alter their properties. These striking features stem from the competition between rotation-based deformations—relevant for small systems—and ordinary elasticity, and are controlled by a characteristic length scale which is entirely tunable by the architectural details. Our study provides new vistas for designing, controlling and programming the mechanics of metamaterials. Show less
