Lifeboat Foundation

A memristor¹ has been proposed as an artificial synapse for emerging neuromorphic computing applications^2,3. To train a neural network in memristor arrays, changes in weight values in the form of device conductance should be distinct and uniform³. An electrochemical metallization (ECM) memory^4,5, typically based on silicon (Si), has demonstrated a good analogue switching capability^6,7 owing to the high mobility of metal ions in the Si switching medium⁸. However, the large stochasticity of the ion movement results in switching variability. Here we demonstrate a Si memristor with alloyed conduction channels that shows a stable and controllable device operation, which enables the large-scale implementation of crossbar arrays. The conduction channel is formed by conventional silver (Ag) as a primary mobile metal alloyed with silicidable copper (Cu) that stabilizes switching. In an optimal alloying ratio, Cu effectively regulates the Ag movement, which contributes to a substantial improvement in the spatial/temporal switching uniformity, a stable data retention over a large conductance range and a substantially enhanced programmed symmetry in analogue conductance states. This alloyed memristor allows the fabrication of large-scale crossbar arrays that feature a high device yield and accurate analogue programming capability. Thus, our discovery of an alloyed memristor is a key step paving the way beyond von Neumann computing.

Circa 2019 o,.0.

How did the universe evolve from a point of singularity, known as the Big Bang, into a massive structure whose boundaries seem limitless? New clues and insight into the evolution of the universe have recently been provided by an international team of physicists, who performed the most detailed large-scale simulation of the universe to date.

The researchers made their own universe in a box — a cube of space spanning more than 230 million light-years across. Previous cosmological simulations were either very detailed but spanned a small volume or less detailed across large volumes. The new simulation, known as TNG50, managed to combine the best of two worlds, producing a large-scale replica of the cosmos while, at the same time, allowing for unprecedented computational resolution.

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Can lost species ever become un-extinct? Many scientists believe it’s only a matter of time before many extinct animals again walk the Earth through cloning.

A simple chemical reaction gives platelets the ability to swim around.

Numerous efforts have been made to improve the temporal resolution of CRISPR-Cas9–mediated DNA cleavage to the hour time scale. Liu et al. developed a Cas9 system that achieved genome-editing manipulation at the second time scale (see the Perspective by Medhi and Jasin). Part of the guide RNA is chemically caged, allowing the Cas9-guide RNA complex to bind at a specific genomic locus without cleavage until activation by light. This fast CRISPR system achieves genome editing at high temporal resolution, enabling the study of early molecular events of DNA repair processes. This system also has high spatial resolution at short time scales, allowing editing of one genomic allele while leaving the other unperturbed.

Science, this issue p. 1265; see also p. 1180

CRISPR-Cas systems provide versatile tools for programmable genome editing. Here, we developed a caged RNA strategy that allows Cas9 to bind DNA but not cleave until light-induced activation. This approach, referred to as very fast CRISPR (vfCRISPR), creates double-strand breaks (DSBs) at the submicrometer and second scales. Synchronized cleavage improved kinetic analysis of DNA repair, revealing that cells respond to Cas9-induced DSBs within minutes and can retain MRE11 after DNA ligation. Phosphorylation of H2AX after DNA damage propagated more than 100 kilobases per minute, reaching up to 30 megabases. Using single-cell fluorescence imaging, we characterized multiple cycles of 53BP1 repair foci formation and dissolution, with the first cycle taking longer than subsequent cycles and its duration modulated by inhibition of repair. Imaging-guided subcellular Cas9 activation further facilitated genomic manipulation with single-allele resolution.

Groundbreaking research finds that the human brain creates multi-dimensional neural structures.

Here are a few details that have remained more or less intact: J, when he was alive, had dark brown hair, large eyes, olive skin. He loved Proust and Fitzgerald, Marsalis and Bechet. Said things like “this too shall pass,” wrote them on rogue scraps of paper, and hid them in the bottoms of our backpacks.

Then, one morning, he was gone.

I tried to remember all of the details that constituted him, but my memory would not allow it. Instead, I saw a body vaulting through the sky, a bike clumsily skidding below, and I was furious with myself for not being able to imagine something else or, at the very least, remember more. Me, the keeper of a thousand notebooks. The guardian of a thousand pens. But The Cloud, my trusty companion, seemed to have stored all of him. And when grief took me, it preempted my needs like any good lover would; showed me parts of myself I didn’t know were there and parts of others I had almost completely forgotten—and because the bereaved and the writer in me were rattled in their obsessive need to remember, they both gave themselves over to it entirely.

After sending NASA astronauts to the ISS, SpaceX is focusing back on the Mars-colonizing Starship project.

The largest Mayan structure to date has been discovered at a new site in Tabasco, Mexico. In a new paper in Nature, the researchers describe how they used lidar surveys, excavations, and radiocarbon dating of charcoal samples to find and age the site which has been named Aguada Fénix.

“To our knowledge, this is the oldest monumental construction ever found in the Maya area and the largest in the entire pre-Hispanic history of the region,” the researchers say.

This 3,000-year-old discovery—and additional previous findings—challenge the notion that Mayan civilization began gradually with small villages and eventually evolving into larger sites and ceremonial complexes. For example, a formal ceremonial complex and plateau dating back to 950 B.C. was previously discovered in Ceibal, Guatemala, that “suggests that substantial ceremonial centers developed in the Maya lowlands earlier than was previously thought.” The Ceibal structure was believed to display the oldest Mayan architecture before Aguada Fénix was found.