Tag: science

Semaglutide

The mean change in body weight from baseline to week 68 was −14.9% in the semaglutide group as compared with −2.4% with placebo, for an estimated treatment difference of −12.4% (95% confidence interval [CI], −13.4 to −11.5; P<0.001). More participants in the semaglutide group than in the placebo group achieved weight reductions of 5% or more (1047 participants [86.4%] vs. 182 [31.5%]), 10% or more (838 [69.1%] vs. 69 [12.0%]), and 15% or more (612 [50.5%] vs. 28 [4.9%]) at week 68 (P<0.001 for all 3 comparisons of odds). The change in body weight from baseline to week 68 was −15.3 kg in the semaglutide group as compared with −2.6 kg in the placebo group (estimated treatment difference, −12.7 kg; 95% CI, −13.7 to −11.7). Participants who received semaglutide had a greater improvement with respect to cardiometabolic risk factors and a greater increase in participant-reported physical functioning from baseline than those who received placebo.

this could be the first weight loss drug that actually works. if true, huge public health implications.

A Fitbit for an Elephant

Understanding energy expenditure can help scientists understand how well animals are doing and whether they are going to be able to hunt, reproduce, and survive. Wilson has used accelerometers to study all sorts of animals including sea turtles, sheep, bats, hawks, and penguins. He combines the accelerometer data with inputs from other sensors that measure temperature, magnetic force, and geolocation to understand exactly what the animal is doing and where it is. The technology allows him to track penguins as they sit on their nests, get up, waddle to the ocean, and dive in. His sensors can stay on the animals for weeks, and after he retrieves the devices, he can follow along as the penguins swim and dive and fish, all from 1000s of km away.

Light sphere argument

If we’re to have an experience remotely like the human one, then we have to be relatively close to the beginning of time—since 100s of billions of years from now, the universe will likely be dominated by near-light-speed expanding spheres of intelligence, and a little upstart civilization like ours would no longer stand a chance. I.e., even though our existence is down to some lucky accidents, and even though those same accidents probably recur throughout the cosmos, we shouldn’t yet see any of the other accidents, since if we did see them, it would already be nearly too late for us.

if we want human-originated sentience to spread across the universe, then the sooner we get started the better! Just like Bill Gates in 1975, we should expect that there will soon be competitors out there. Indeed, there are likely competitors out there “already” (where “already” means, let’s say, in the rest frame of the cosmic microwave background)—it’s just that the light from them hasn’t yet reached us. So if we want to determine our own cosmic destiny, rather than having post-singularity extraterrestrials determine it for us, then it’s way past time to get our act together as a species. We might have only a few 100M more years to do so.

and here’s the preprint

First New Blue in 200 years

for the first time in 2 centuries, a new shade of the celebrated color is available for artists — YInMn Blue. It’s named after its components — Yttrium, Indium, and Manganese — and its luminous, vivid pigment never fades, even if mixed with oil and water. Blue pigments, which date back 6000 years, have been traditionally toxic and prone to fading. That’s no longer the case with YInMn, which reflects heat and absorbs UV radiation, making it cooler and more durable than pigments like cobalt blue.

Incredibly efficient brains

But it’s not just this flexible behavioral repertoire that’s so amazing. It’s not the fact that somehow, this dumb little spider with its crude compound optics has visual acuity to rival a cat’s (even though a cat’s got orders of magnitude more neurons in one retina than our spider has in her whole head). It’s not even the fact that this little beast can figure out a maze which entails recognizing prey, then figuring out an approach path along which that prey is not visible (i.e., the spider can’t just keep her eyes on the ball: she has to develop and remember a search image), then follow her best-laid plans by memory including recognizing when she’s made a wrong turn and retracing her steps, all the while out of sight of her target. No, the really amazing thing is how she does all this with a measly 600K neurons— how she pulls off cognitive feats that would challenge a mammal with 70M or more.

She does it like a Turing Machine, one laborious step at a time.

She’ll sit there for 2 hours, just watching. It takes that long to process the image: whereas a cat or a mouse would assimilate the whole hi-res vista in an instant, Portia’s poor underpowered graphics driver can only hold a fraction of the scene at any given time. So she scans, back and forth, back and forth, like some kind of hairy multilimbed Cylon centurion, scanning each little segment of the game board in turn. Then, when she synthesizes the relevant aspects of each, she figures out a plan, and puts it into motion: climbing down the branch, falling out of sight of the target, ignoring other branches that would only seem to provide a more direct route to payoff, homing in on that one critical fork in the road that leads back up to satiation. Portia won’t be deterred by the fact that she only has a few % of a real brain: she emulates the brain she needs, a few % at a time.

2022-06-24: Speaking of efficiency, the brain has a power saving mode.

When mice were deprived of sufficient food for weeks at a time — long enough for them to lose 15%-20% of their typical healthy weight — neurons in the visual cortex reduced the amount of ATP used at their synapses by 29%. Because the neurons in low-power mode processed visual signals less precisely, the food-restricted mice performed worse on a challenging visual task. The fact that these impairments in perception occurred long before the animal entered real starvation was unexpected.

A significant implication of the new findings is that much of what we know about how brains and neurons work may have been learned from brains that researchers unwittingly put into low-power mode. It is extremely common to restrict the amount of food available to mice and other experimental animals for weeks before and during neuroscience studies to motivate them to perform tasks in return for a food reward.

Mendelian randomization

by employing innate genetic differences between people—an inborn susceptibility to alcohol, say, or to higher cholesterol levels in the arteries—they can now mimic, at much less effort and expense, the kinds of large trials that would be necessary to determine if an HDL-lowering medicine is really beneficial. The new technique, called Mendelian randomization, is already being used by drug companies to make billion-dollar decisions about which drugs to pursue. What may worry Davey Smith and others most is that as genetic databases have multiplied, tying genes to virtually any imaginable biological or even behavioral variable, studies of cause and association have become almost effortless.

The University of Bristol hosts a platform called MR-Base that lets anyone carry out virtual experiments without collecting any new data.

“You can do these studies now, sitting at your desk, in 10 minutes. It’s just too easy. Because of the flood of studies coming out, it may very well fall into disrepute.”

Monkey ransom

Shrewd macaques prefer to target items that humans are most likely to exchange for food, such as electronics, rather than objects that tourists care less about, such as hairpins or empty camera bags. Bargaining between a monkey robber, tourist and a temple staff member quite often lasted several minutes. The longest wait before an item was returned was 25 minutes, including 17 minutes of negotiation. For lower-valued items, the monkeys were more likely to conclude successful bartering sessions by accepting a lesser reward.

New variants

Many virologists thought this very unlikely, you could never know that a new variety had higher transmission from mere incidence data: you must understand the biological mechanism. Are they correct? Obviously not.

Why did they think that a new, more transmissible variant of COVID-19 was unlikely? There are several reasons. One, they typically deal with viruses that have been around for a long time, like measles ( > 1000 years). An old virus is going to be pretty well-adapted to to humans. Probably it’s at a local optimum, where small changes would reduce infectivity. But you don’t expect that high degree of optimization in a virus that’s brand new in humans: while spreading to very many people, more than 100M, greatly increases the chance of transmission-increasing mutations. Fisherian acceleration.

Like most biologists and MDs, most virologists don’t know any theory, and in fact don’t _believe_ in theory. For this they occasionally pay a price.

Can open access work?

The biggest problem for an open-access regime is how to ensure good refereeing, which if done correctly raises the quality of academic papers. Under the current system, editors decide which papers get refereed, and they choose the identities of the referees. Those same referees are underpaid and underincentivized, and often do a poor or indifferent job.

Many of the original papers on mRNA vaccines, for example, were rejected numerous times by academic journals, hardly a ringing endorsement of the status quo. More generally, since publication is currently a yes/no decision, the refereeing system creates incentives to avoid criticism and play it safe, rather than to strike out with bold new ideas and risk rejection.

Under my alternative vision, research scientists would be told to publish one-third less and devote the extra time to volunteer refereeing of what they consider to be the most important online postings. That refereeing, which would not be anonymous, would be considered as a significant part of their research contribution for tenure and promotion. Professional associations, foundations and universities could set up prizes for the top referees, who might be able to get tenure just by being great at adding value to other people’s work. If the lack of anonymity bothers you, keep in mind that book reviews are already a key determinant for tenure in many fields, such as the humanities, and they are not typically anonymous.