Tag: science

Tail latency aware caching

RobinHood dynamically allocates cache space to those backends responsible for high request tail latency (cache-poor) backends, while stealing space from backends that do not affect the request tail latency (cache-rich backends). In doing so, Robin Hood makes compromises that may seem counter-intuitive (e.g., significantly increasing the tail latencies of certain backends).

Liberal Radicalism

We were able to compute the optimum level of the public good because we knew each individual’s utility function. In the real world each individual’s utility function is private information. Thus, to reach the social optimum we must solve 2 problems. The information problem and the free rider problem. The information problem is that no one knows the optimal quantity of the public good. The free rider problem is that no one is willing to pay for the public good. The government used the contribution levels under the top-up mechanism as a signal to decide how much of the public good to produce and almost magically the top-up function is such that citizens will voluntarily contribute exactly the amount that correctly signals how much society as a whole values the public good. Amazing!

Brain Research Notes

We are generally poor at describing our mental state. Our friends generally do a better job on identifying if we are depressed. 25% of the world will develop a serious brain malfunction in their lifetime. If you spend 10-100 hours in an fMRI, we can read your thoughts. 40 Hz flickering LED light induces gamma oscillations in the brain. After 1 hour of exposure, she saw a 50% reduction in amyloid plaques in a Alzheimer’s rat model. Expansion microscopy is the opposite of normal microscopy. Instead of zooming in on the brain, you make the brain bigger with a polymer expansion similar to the gel found in super-absorbent diapers. Ed Boyden’s team can trigger brain activity at a targeted deep area with a pair of acoustic waves at close frequencies, like 2.00 and 2.01 Hz

Destroying psychology

interesting piece on the replication crisis in psychology, and what’s next.

Lindsay talks with psychologists all the time who aren’t eager to embrace the updated rules, and he understands why. “Our literature is packed with unreliable findings. And I can imagine if you hitched your whole wagon to a concept that doesn’t seem to be a real thing, that could be threatening.” Like Heathers, Nick Brown sometimes shakes his head at the reluctance among researchers to acknowledge what, to him, seems obvious. To continue to defend a system that’s churned out stacks upon stacks of hopelessly flawed papers, rather than to own up to the truth and try to fix it, seems pointless. “I don’t know whether they genuinely believe they’re doing the right thing or there’s a sort of doubt niggling at the back of their mind, but they don’t want to acknowledge it. Maybe the people who need to make those changes, in that deep, dark moment before they go to sleep, they think to themselves, ‘How are we going to get out of this?’”

88 OOM Dark Matter Search

physicist Davide D’Angelo and geomicrobiologist Jennifer Macalady travel to Laboratori Nazionali del Gran Sasso to see one of the latest efforts to detect dark matter, the SABRE detector. As with the search for neutrinos, looking for dark matter needs to happen under conditions of “cosmic silence” — in this case, beneath a mountain in Italy. D’Angelo, who is a collaborator on the project, likens the search to “hunting ghosts”.

2020-11-24:

the search spans 10e-21 eV to 10e67 eV, 88 orders of magnitude. perhaps the broadest search ever? The lightest that dark matter could possibly be is about one-thousandth of a trillionth of a trillionth of the electron’s mass — which would result in a particle that’s like an extremely low-energy wave, with a wavelength the size of a small galaxy. Lighter (and therefore longer) entities would be too diffuse to explain why galaxies stick together. The heaviest is a black hole of 30 solar masses.

Prime Numbers Patterns

A new analysis has uncovered patterns in primes that are similar to those found in the positions of atoms inside certain crystal-like materials. The discovery may aid research in both mathematics and materials science. “Prime numbers have beautiful structural properties, including unexpected order, hyperuniformity and effective limit-periodic behavior. The primes teach us about a completely new state of matter.”

Etching solar

While researchers did find that production of individual black-Si passive emitter rear cells (PERC) were between 15.8 and 25.1% more expensive than making conventional cells, they also found that the efficiency gains and the ability to go to the less-expensive multicrystalline silicon starting material far outweighed those extra costs: overall the cost per unit power dropped by 10.8%.