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Neurobiological Mechanisms Underlying Qualia

Many of my essays are quite old. They were, in effect, written by a person who no longer exists in that my views, beliefs, and overall philosophy have grown and evolved over the years. Consequently, if I were to write on the same topics again, the resulting essays might differ significantly from their current versions. Rather than edit my essays to remain contemporary with my views, I have chosen to preserve them as a record of my past inclinations and writing style. Thank you for understanding.

Douglas Hofstadter: The Nature of Categories and Concepts

Stanford Symbolic Systems Distinguished Speaker Lecture Thursday, March 6, 2013.

Douglas Hofstadter, College of Arts and Sciences Distinguished Professor of Cognitive Science and Comparative Literature. Indiana University.

What is a quintessential category? Bird, perhaps? Or maybe chair? And what is a quintessential concept? Two? Number? Prime number?

I’m not trying to put words into your mouth — I’m just trying to get you to ask yourself these questions. Also, I wonder if by any chance you thought that these are really exactly the same question, in which case you might have wondered why I asked you the same question twice.

Or did you perhaps think something along these lines: \.

New technique cools high-performance chips from the inside out

Researchers at the Korea Advanced Institute of Science and Technology (KAIST) have developed a technique to carve microscopic liquid-cooling channels directly inside silicon semiconductor chips.

Interestingly, the computer architecture slashed the energy required for cooling by pumping ordinary, room-temperature water straight through the chip’s internal structure.

“As the performance of AI semiconductors and advanced electronic packaging becomes increasingly limited by heat, we expect this technology to serve as a foundational cooling solution for future high-performance computing systems,” said Professor Sung Jin Kim.

A Giant Seismic Wave Bounced Off Earth’s Core And May Have Shifted Japan

When the magnitude 9.0 Tōhoku earthquake struck off the coast of Japan in 2011, its seismic shivers did more than ripple through the planet.

At least one wave traveled 2,900 kilometers (1,800 miles) down to the boundary between Earth’s mantle and liquid outer core, where it was reflected right back to the surface.

And there, according to a new analysis of earthquake data from across Japan, it may have done something scientists have never identified before.

Fermi mission uncovers possible sibling supernova remnants

A new study of two supernova remnants, the debris left behind after stars explode, suggests the explosions came from stellar siblings that once orbited each other. The first star’s detonation sent its binary companion hurtling through space, and then, after traveling for thousands of years, the surviving star blew up, too.

“Using 16 years of data from NASA’s Fermi Gamma-ray Space Telescope, our analysis uncovered gamma rays associated with a supernova remnant that was hidden in the glare of its neighbor, the Jellyfish Nebula, one of the brightest gamma-ray-emitting supernova remnants known,” said Miltiadis Michailidis, a postdoctoral fellow in the physics department at Stanford University in California. “There are so many striking connections between the two remnants that we conclude they’re likely related, giving us the first known example of a binary system where both stars have undergone supernova explosions.”

Michailidis presented the findings Wednesday at the 248th meeting of the American Astronomical Society in Pasadena, California. A paper describing the results will appear in a future edition of Nature Communications.

Laser pulses set layered metals vibrating 1 trillion times per second, revealing electron-driven motion

How does light turn into motion within a metal? A team of researchers from European XFEL, the University of Potsdam and other participating institutions has shown that ultrashort optical laser pulses can trigger extremely rapid lattice vibrations in periodically layered metal structures—not primarily by heating the atomic lattice, but through the pressure exerted by hot electrons. The results are published in Nature Communications.

In the study, platinum and copper layers just a few nanometers (millionths of a millimeter) thick were stacked to form an artificial metal lattice. After being excited by a laser pulse, the artificial crystal lattice began to oscillate at around one terahertz: At a rate of roughly one trillion times per second, the platinum nanolayers expand and squeeze the copper layers. The oscillation, which begins immediately, is too rapid to be explained by conventional lattice heating via heat transfer from the electrons.

“That surprised us,” says Jan-Etienne Pudell of European XFEL. “The oscillation is not caused by the pressure of the heated lattice, but by electron pressure, particularly in the platinum layers.”

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