Science - USA (2020-01-03)

the knot as the two strands are

pulled apart. The authors show

why some common knots slip

easily and untie, whereas others

hold tight. —MSL

Science, this issue p. 71

OPTICS

Miniaturizing particle

accelerators

Particle accelerators are usually

associated with large national

facilities. Because photons

are able to impart momentum

to electrons, there are also

efforts to develop laser-based

particle accelerators. Sapra

et al. developed an integrated

particle accelerator using pho-

tonic inverse design methods to

optimize the interaction between

MULTIPLEX GENOMICS

Single-cell chemical

transcriptomics

Single-cell transcriptomic
technologies have emerged as
powerful tools to explore cellular
heterogeneity at the resolution
of individual cells. Srivatsan
et al. now add another layer of
information and complexity by
combining single-cell transcrip-
tomics with oligo hashing and
small molecule screening in a
method called sci-Plex. Because
screening many chemical com-
pounds requires the ability to
profile many cells, and because
screens perturb cells in many
different ways, the authors
demonstrate the effects of 188
compounds in three cancer
lines. The sci-Plex method can

capture gene expression profiles

from thousands of experimental

conditions in a single experiment.

—LMZ

Science, this issue p. 45

NANOPARTICLES

Finding the fivefold path

Crystals formed in nature or

synthesized in a lab can have

domains with different orienta-

tions that are called twins. Having

five of these domains is relatively

common, but how these fivefold

twins form is still a mystery. Song

et al. combined in situ trans-

mission electron microscope

observations with simulations

to find two different pathways

for forming fivefold twins in

gold, platinum, and palladium

nanoparticles. This combination

provides a key insight into the

twin-forming process, which

might be exploited for develop-

ing nanoparticles suitable for a

variety of applications. —BG

Science, this issue p. 40

APPLIED PHYSICS

It’s knot what you know

Why is it that some knots seem

to hold tight while others readily

slip apart? Patil et al. develop a

theoretical analysis of the stabil-

ity of knots and find links between

topological parameters (twist

charge, crossing numbers, hand-

edness) and mechanical stability.

The theory is confirmed using

simulations and experiments

on color-changing fibers that

optically show localized stress

differences in different parts of PHOTO: CNRI/SCIENCE SOURCE

36 3 JANUARY 2020 • VOL 367 ISSUE 6473 sciencemag.org SCIENCE

Edited by Michael Funk

IN SCIENCE JOURNALS

RESEARCH

NEUROSCIENCE

Human dendrites are special

A

special developmental program in the human brain drives

the disproportionate thickening of cortical layer 2/3. This

suggests that the expansion of layer 2/3, along with its

numerous neurons and their large dendrites, may contribute

to what makes us human. Gidon et al. thus investigated the

dendritic physiology of layer 2/3 pyramidal neurons in slices taken

from surgically resected brain tissue in epilepsy patients. Dual

somatodendritic recordings revealed previously unknown classes

of action potentials in the dendrites of these neurons, which

make their activity far more complex than has been previously

thought. These action potentials allow single neurons to solve two

long-standing computational problems in neuroscience that were

considered to require multilayer neural networks. —PRS

Science, this issue p. 83

Light micrograph

showing cortical

neurons with

branching dendrites

Published by AAAS