279 research outputs found
The rise of (Chiral) 3D mechanical metamaterials
On the occasion of this special issue, we start by briefly outlining some of the history and future perspectives of the field of 3D metamaterials in general and 3D mechanical metamaterials in particular. Next, in the spirit of a specific example, we present our original numerical as well as experimental results on the phenomenon of acoustical activity, the mechanical counterpart of optical activity. We consider a three-dimensional chiral cubic mechanical metamaterial architecture that is different from the one that we have investigated in recent early experiments. We find even larger linear-polarization rotation angles per metamaterial crystal lattice constant than previously and a slower decrease of the effects towards the bulk lim
Learning fluid physics from highly turbulent data using sparse physics-informed discovery of empirical relations (SPIDER)
We show how a complete mathematical description of a complicated physical
phenomenon can be learned from observational data via a hybrid approach
combining three simple and general ingredients: physical assumptions of
smoothness, locality, and symmetry, a weak formulation of differential
equations, and sparse regression. To illustrate this, we extract a system of
governing equations describing flows of incompressible Newtonian fluids -- the
Navier-Stokes equation, the continuity equation, and the boundary conditions --
from numerical data describing a highly turbulent channel flow in three
dimensions. These relations have the familiar form of partial differential
equations, which are easily interpretable and readily provide information about
the relative importance of different physical effects as well as insight into
the quality of the data, serving as a useful diagnostic tool. The approach
described here is remarkably robust, yielding accurate results for very high
noise levels, and should thus be well-suited to experimental data
Virus preparations from the mixed-infected P70 Pinot Noir accession exhibit GLRaV-1/GVA ‘end-to-end’ particles
P70 is a Pinot Noir grapevine accession that displays strong leafroll disease symptoms. A high-throughput sequencing (HTS)-based analysis established that P70 was mixed-infected by two variants of grapevine leafroll-associated virus 1 (GLRaV-1, genus Ampelovirus) and one of grapevine virus A (GVA, genus Vitivirus) as well as by two viroids (hop stunt viroid [HSVd] and grapevine yellow speckle viroid 1 [GYSVd1]) and four variants of grapevine rupestris stem pitting-associated virus (GRSPaV). Immunogold labelling using gold particles of two different diameters revealed the existence of ‘hybrid’ particles labelled at one end as GLRaV-1, with the rest labelled as GVA. In this work, we suggest that immunogold labelling can provide information about the biology of the viruses, going deeper than just genomic information provided by HTS, from which no recombinant or ‘chimeric’ GLRaV-1/GVA sequences had been identified in the dataset. Our observations suggest an unknown interaction between members of two different viral species that are often encountered together in a single grapevine, highlighting potential consequences in the vector biology and epidemiology of leafroll and rugose-wood diseases
- …