Lifeboat Foundation

For more than half a century, researchers around the world have been struggling with an algorithmic problem known as “the single source shortest path problem.” The problem is essentially about how to devise a mathematical recipe that best finds the shortest route between a node and all other nodes in a network, where there may be connections with negative weights.

Sound complicated? Possibly. But in fact, this type of calculation is already used in a wide range of the apps and technologies that we depend upon for finding our ways around—as Google Maps guides us across landscapes and through cities, for example.

Now, researchers from the University of Copenhagen’s Department of Computer Science have succeeded in solving the single source shortest path problem, a riddle that has stumped researchers and experts for decades.

Yes, conceivably. And if/when we achieve the levels of technology necessary for simulation, the universe will become our playground.

Circa 2016 face_with_colon_three

A transistor laser (TL)^1,2,3, having the structure of a transistor with multi-quantum wells (MQWs) near its base region, bridges the functionality gap between lasers and transistors. From a TL, an electrical signal can be outputted simultaneously with a light signal by inputting one electrical signal, making it suitable for future high performance optoelectronic integrated device applications⁴. As a new kind of semiconductor laser or transistor, TLs have aroused many interests since its invention. For example, in 2006, the paper² reporting the first room temperature operation of TLs was voted as one of the five most important papers published by Applied Physics Letters in over 40 years⁵. Because of the transistor structure, many interesting characters have been demonstrated, including resonance free frequency response, large direct modulation band width⁶, voltage controlled mode of operation⁷, low relative intensity noise (RIN) close to the shot-noise limit⁸ and low 3rd order intermodulation distortion (IMD)⁹.

However, light emission for all the TLs reported up to now is produced at the expense of current gain. Taking npn TLs as an example, in the devices, electrons injected from the emitter into the base layer first recombine with holes radiatively before the left being collected by the collector⁴. The majority of the electrons are consumed by stimulated light emissions, leading to a current gain which is a lot lower than the gain of a traditional transistor. The common emitter (CE) mode current gain (collector current/base current) is lower than 5 for most, if not all, of the TLs studied, either experimentally^{1,2,3,6,7,8,9,10} or numerically^11,12,13. The low current gain may limit the performance of systems that use TLs. For example, it is much easier to integrate monolithically a heterojunction bipolar transistor (HBT) and a TL than to integrate an HBT with a laser diode (LD) because of the dual functionality of TLs. For such applications, a large current gain of TL (used as HBT) is desired for the amplification of electrical signal to drive the laser.

Continue reading “High current gain transistor laser” »

Organic electronic-based gas sensors hold great potential for portable healthcare-and environment-monitoring applications. It has recently been shown that introducing a porous structure into an organic semiconductor (OSC) film is an efficient way to improve the gas-sensing performance because it facilitates the interaction between the gaseous analyte and the active layer. Although several methods have been used to generate porous structures, the development of a robust approach that can facilely engineer the porous OSC film with a uniform pore pattern remains a challenge. Here, we demonstrate a robust approach to fabricate porous OSC films by using a femtosecond laser-processed porous dielectric layer template. With this laser-assisted strategy, various polymeric OSC layers with controllable pore size and well-defined pore patterns were achieved.

Circa 2021 face_with_colon_three

“Optical accelerator” devices could one day soon turbocharge tailored applications.

“You can think of curiosity as a kind of reward which the agent generates internally on its own, so that it can go explore more about its world,” Agrawal said. This internally generated reward signal is known in cognitive psychology as “intrinsic motivation.” The feeling you may have vicariously experienced while reading the game-play description above — an urge to reveal more of whatever’s waiting just out of sight, or just beyond your reach, just to see what happens — that’s intrinsic motivation.

Humans also respond to extrinsic motivations, which originate in the environment. Examples of these include everything from the salary you receive at work to a demand delivered at gunpoint. Computer scientists apply a similar approach called reinforcement learning to train their algorithms: The software gets “points” when it performs a desired task, while penalties follow unwanted behavior.

Zuckerberg likes to quote Steve Jobs’ description of computers as “bicycles for the mind.” I can imagine him thinking, “What’s wrong with helping us pedal a little faster?”

https://www.youtube.com/watch?v=rTRzYjoZhIY

And while I reflexively gag at Zuckerberg’s thinking, that isn’t meant to discount its potential to do great things or to think that holding it off will be easy or necessarily desirable. But at a minimum, we should demand a pause to ask hard questions about such barrier-breaking technologies—each quietly in our own heads, I should hasten to add, and then later as a society.

Continue reading “Zuckerberg Wants Facebook to Build a Mind-Reading Machine” »

Arthur C. Clarke, science fiction author and futurist, crossed paths with the scientists of the Bell System on numerous occasions. In 1945, he concurrently, but independently, conceived of the first concept for a communications satellite at the same time as Bell Labs scientist, John Robinson Pierce too, was a science fiction writer. To avoid any conflict with his day job at Bell Labs, Pierce published his stories under the pseudonym J.J. Coupling.

In the early 1960s, Clarke visited Pierce at Bell Labs. During his visit, Clarke saw and heard the voice synthesis experiments going on at the labs by John L. Kelly and Max Mathews, including Mathews’ computer vocal version of “Bicycle Built for Two”. Clarke later incorporated this singing computer into the climactic scene in the screenplay for the movie 2001: A Space Odyssey, where the computer HAL9000 sings the same song. According to Bob Lucky, another Bell Labs scientist, on the same visit, Clarke also saw an early Picturephone, and incorporated that into 2001 as well.

Continue reading “Interview with author/futurist Arthur C. Clarke, from an AT&T-MIT Conference, 1976” »

Advances in brain-computer interface technology are impressive, but we’re not close to anything resembling mind control.