Neurons that represented the smell of an apple in May and those that represented the same smell in June were as different from each other as those that represent the smells of apples and grass at any one time. Representational drift occurs in a variety of brain regions besides the piriform cortex. Its existence is clear; everything else is a mystery. How can animals possibly make any lasting sense of the world if their neural responses to that world are constantly in flux? If such flux is common, “there must be mechanisms in the brain that are undiscovered and even unimagined that allow it to keep up.”
Month: June 2021
Galactic Settlement
The simulation depicts the expansion of a technological civilization through the Milky Way, created along lines previously described in the literature. What we are looking at is the transition between a Kardashev Type II civilization, and a Type III, which has spread throughout the galaxy. This might be a fast process considering the motions of stars themselves, which would overcome the inertia of slower growing settlements and boost expansion rates. Issues like starship capabilities and the lifetime of colonies come into play, but the striking thing is how fast galactic settlement occurs and how the motions of stars factor into the settlement wave. The parameters are everything, and they’re interesting:
- Ships are launched no more frequently than every 100 ka;
- Technology persists in a given settlement for 100 ma before dying out;
- Ship range is 10 light years.
- Ship speeds are 10 km/s; Voyager-class speeds.
- The simulation covers 1 ga
No Financial System
As much as 50% of all unemployment monies, or $400b might have been stolen. Unemployment fraud is now offered as a service, much like ransomware. States without fraud-detection services are targeted the most.
This may be scare mongering by interested parties like the id “theft” cottage industry, but seems directionally correct. Terrible identity and financial infrastructure has consequences.
The Circles of Friendship
The innermost layer of 1.5 is the most intimate; clearly that has to do with your romantic relationships. The next layer of 5 is your shoulders-to-cry-on friendships. They are the ones who will drop everything to support us when our world falls apart. The 15 layer includes the previous 5, and your core social partners. They are our main social companions, so they provide the context for having fun times. The next layer up, at 50, is your big-weekend-barbecue people. And the 150 layer is your weddings and funerals group who would come to your once-in-a-lifetime event. The layers come about primarily because the time we have for social interaction is not infinite. You have to decide how to invest that time, bearing in mind that the strength of relationships is directly correlated with how much time and effort we give them.
While I quibble with the names and sizes of these circles, it still seems directionally correct.
Bug Welfare
Last month the EU officially approved mealworms as safe for human consumption, sparking a bunch of articles on how bugs are the food of the future. In order to produce a kilogram of bug-based food, you need ~10k bugs. On the one hand, bugs probably don’t matter much morally. On the other hand, 10k is a lot. Do bugs have moral value? What about the other limit? Plausibly the most morally correct action, short of becoming vegetarian, would be to eat the largest animal there is. And according to the Talmud the righteous in Heaven dine on the flesh of Leviathan, which suffices to feed all of them forever. Hypothesis confirmed!
Better Crowdfunding
On Kickstarter you contribute to a project and if a contribution threshold isn’t reached you get your money back. The Kickstarter contract is useful but it’s still easy for a good project to fail because there are many equilibria with non-funding. For example, if I think that you won’t contribute then I may decide not to contribute and if I don’t contribute then you may decide not to contribute. Neither of us can do better by contributing, given the other person is not-contributing, and so non-contributing is a Nash equilibrium. Now introduce refund bonuses which pay out only if the threshold is not reached. Now if I think that you won’t contribute then I want to contribute, to earn the refund bonus, and the same is true for you. The only equilibria in the crowdfunding game with refund bonuses have the project being funded. Thus, a nice feature of refund bonus game is that in equilibrium the refund bonuses are never paid! Without refund bonuses only ~30% of socially valuable projects succeed (perhaps coincidentally almost the exact same as on Kickstarter). But with refund bonuses the success rate increases 60% and it doesn’t much matter much what type of refund bonuses are used!
AI Labor Supply
61.6% of the working-age population were active in the labor force, either working in jobs or looking for them. That is essentially unchanged from the summer of 2020. Wages are soaring. In May, average wages grew at a 6.1% annual rate. In April, they grew at an 8.7% annual rate. Employers are boosting wage offers in order to attract and retain workers, who are increasingly difficult to attract and retain.
Unable to find enough workers, Lee’s Famous Recipe Chicken, installed an automated voice system to take orders. The system never fails to upsell customers on fries or a drink, which has boosted sales. There’s no longer a need for a person to take orders at the drive-thru window. “It also never calls in sick. There’s no way we’re going back.”
A massive shift to delivery and virtual kitchens triggered by the pandemic may mean that some restaurants and some customers will be more willing to use technology that once seemed unfamiliar. Using an app to order at a restaurant table could mean that, eventually, fewer servers will be needed.
City Microbiomes
Researchers took 4700 samples from mass transit systems in 60 cities across the world, swabbing common touch points like turnstiles and railings in bustling subways and bus stations across the world. Using metagenomic sequencing, they created a global atlas of the urban microbial ecosystem, the first systematic catalog of its kind. The results suggest that no 2 cities are alike, with each major metropolis studied so far revealing a unique molecular echo of the microbial species that inhabit it, distinct from populations found in other urban environments.
2023-10-12: Dark matter
Metagenomes encode an enormous diversity of proteins, reflecting a multiplicity of functions and activities. Exploration of this vast sequence space has been limited to a comparative analysis against reference microbial genomes and protein families derived from those genomes. Here, to examine the scale of yet untapped functional diversity beyond what is currently possible through the lens of reference genomes, we develop a computational approach to generate reference-free protein families from the sequence space in metagenomes. We analyse 27k metagenomes and identify 1.17b protein sequences longer than 35 amino acids with no similarity to any sequences from reference genomes. Using massively parallel graph-based clustering, we group these proteins into 106k novel sequence clusters with more than 100 members, doubling the number of protein families obtained from the reference genomes clustered using the same approach. We annotate these families on the basis of their taxonomic, habitat, geographical and gene neighbourhood distributions and, where sufficient sequence diversity is available, predict protein three-dimensional models, revealing novel structures. Overall, our results uncover an enormously diverse functional space, highlighting the importance of further exploring the microbial functional dark matter.
Worst Translator
Attack-resistant Hardware
Attacks often succeed by abusing the gap between program and machine-level semantics– for example, by locating a sensitive pointer, exploiting a bug to overwrite this sensitive data, and hijacking the victim program’s execution. In this work, we take secure system design on the offensive by continuously obfuscating information that attackers need but normal programs do not use, such as representation of code and pointers or the exact location of code and data. Our secure hardware architecture, Morpheus, combines 2 powerful protections: ensembles of moving target defenses and churn. Ensembles of moving target defenses randomize key program values (e.g., relocating pointers and encrypting code and pointers) which forces attackers to extensively probe the system prior to an attack. To ensure attack probes fail, the architecture incorporates churn to transparently re-randomize program values underneath the running system. With frequent churn, systems quickly become impractically difficult to penetrate. We demonstrate Morpheus through a RISC-V-based prototype designed to stop control-flow attacks. Each moving target defense in Morpheus uses hardware support to individually offer more randomness at a lower cost than previous techniques. When ensembled with churn, Morpheus defenses offer strong protection against control-flow attacks, with our security testing and performance studies revealing: i) high-coverage protection for a broad array of control-flow attacks, including protections for advanced attacks and an attack disclosed after the design of Morpheus, and ii) negligible performance impacts (1%) with churn periods up to 50 ms, which our study estimates to be at least 5000x faster than the time necessary to possibly penetrate Morpheus.
Morpheus went undefeated in a hacking challenge.
See also a related approach: Physically unclonable functions, or PUFs, exploit the fact that, at a microscopic level, even mass-produced computer chips have tiny differences. PUFs leverage that to let every chip in a computer, smartphone, or other device generate a signal that no other chip can generate.“ The SolarWinds hack that targeted the US government really got people thinking about how we’re going to be doing authentication and cryptography. We’re hopeful that this could be part of the solution.”
Gregor J. Rothfuss 