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How a gene shapes the architecture of the human brain

Researchers around the world are studying how the human brain achieves its extraordinary complexity. A team at the Central Institute of Mental Health in Mannheim and the German Primate Center—Leibniz Institute for Primate Research in Göttingen has now used organoids to show that the ARHGAP11A gene plays a crucial role in brain development. If this gene is missing, key processes involved in cell division and structure become unbalanced.

The human brain distinguishes us from other living beings like no other organ. It enables language, abstract thinking, complex social behavior, and culture. But how can this extraordinarily powerful organ develop, and how is it ensured that nerve cells and supporting cells form in exactly the right places to create the complexity of the human brain?

A team led by Dr. Julia Ladewig at the Central Institute of Mental Health (CIMH) in Mannheim and Dr. Michael Heide at the German Primate Center (DPZ) in Göttingen has investigated this question at the molecular level.

The universe is a puzzle that fits together only one way

Heraclitus famously argued that you can’t step into the same river twice. Here, philosopher JB Manchak argues that the whole universe is like that – and that such a universe has some interesting knock-on consequences. One being that although one can add more structure to a Heraclitus spacetime – by adding a big sign saying “here is the centre of the universe!” What one can’t do, Manchak argues, is reduce symmetries in a Heraclitus spacetime by adding such a sign. To illustrate the point, imagine the universe is a giant puzzle in which each event in space and time is a piece. In a non-Heraclitus universe, some pieces would be able to fit in several places. But in a Heraclitus universe, Manchak argues, there is exactly only one way to put the puzzle pieces of the universe together.

The ancient Greek philosopher Heraclitus is known for his theory of constant flux: “It is not possible to step twice into the same river.” It turns out that one can explore this idea within the context of Einstein’s general relativity. A four-dimensional “Heraclitus spacetime” is a model of the universe in which no two events have the same structure. This means that such models exhibit a radical type of spacetime asymmetry.

In what follows, I will first introduce the notion of Heraclitus spacetime within general relativity. To do this, a few basic definitions will be needed as well as a related discussion of spacetime symmetries. Next, I will highlight a curious result: if a model universe has the Heraclitus property, then its local structure completely fixes its global structure as well. In other words, bits of information encoded at each event allow one to piece together what the universe is like in its entirety (e.g. its shape). Finally, I will sketch a way in which the radical asymmetry present in a Heraclitus spacetime can be used to clarify a number of other topics in the philosophy of spacetime physics.

Scientists Reveal Turning Point When Your Body’s Aging Accelerates

The passage of time may be linear, but the course of human aging is not.

Rather than a gradual transition, your life staggers and lurches through the rapid growth of childhood and the plateau of early adulthood, to an acceleration in aging as the decades progress.

A study has identified a turning point at which that acceleration typically takes place: at around age 50.

Bichromatic moiré superlattices for tunable quadrupolar trions and correlated states

The authors show that bichromatic moiré superlattices formed by two mismatched moiré patterns in van der Waals semiconductor heterotrilayers stabilize quadrupolar moiré trions and enable electric-field tuning of excitonic and electronic ground states.

Single-crystalline monolayer semiconductors with coherent quantum transport by vicinal van der Waals epitaxy

By controlling the coalescence of multiple unidirectional grains on vicinal sapphire substrates, wafer-scale channels of single-crystalline molybdenum disulfide can be grown, which exhibit coherent quantum transport across large length scales.

Physicists generate hybrid spin-sound waves, expanding options for 6G implementation

Acoustic frequency filters, which convert electrical signals into miniaturized sound waves, separate the different frequency bands for mobile communications, Wi-Fi, and GPS in smartphones. Physicists at RPTU have now shown that such miniaturized sound waves can couple strongly with spin waves in yttrium iron garnet. This results in novel hybrid spin-sound waves in the gigahertz frequency range.

The use of such nanoscale hybrid spin-sound waves provides a pathway for agile frequency filters for the upcoming 6G mobile communications generation. The fundamental study by the RPTU researchers has been published in the journal Nature Communications.

Surface acoustic waves (SAWs) are ubiquitous. They unleash destructive power in the form of earthquake waves but are also at the heart of miniaturized frequency filters that are used billions of times for GHz-frequency mobile communication in smartphones.

The Cuckoo’s Egg: Tracking a Spy Through the Maze of Computer Espionage

Before the Internet became widely known as a global tool for terrorists, one perceptive U.S. citizen recognized its ominous potential. Armed with clear evidence of computer espionage, he began a highly personal quest to expose a hidden network of spies that threatened national security. But would the authorities back him up? Cliff Stoll’s dramatic firsthand account is “a computer-age detective story, instantly fascinating [and] astonishingly gripping” (Smithsonian).

Cliff Stoll was an astronomer turned systems manager at Lawrence Berkeley Lab when a 75-cent accounting error alerted him to the presence of an unauthorized user on his system. The hacker’s code name was “Hunter” — a mysterious invader who managed to break into U.S. computer systems and steal sensitive military and security information. Stoll began a one-man hunt of his spying on the spy. It was a dangerous game of deception, broken codes, satellites, and missile bases — a one-man sting operation that finally gained the attention of the CIA…and ultimately trapped an international spy ring fueled by cash, cocaine, and the KGB.

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