Sep 01 2020

Review of Keto and Intermittent Fasting

A new review of the published literature regarding the ketogenic diet and intermittent fasting has, from my perspective, entirely predictable results. By this I mean they are consistent with previous dieting research and there are no surprises. They are also consistent with one of the major themes of this blog – you cannot get away from fundamental realities by making cosmetic changes. You cannot change the laws of physics or the nature of biology. This often translates to the fact that, as a general rule, there are rarely easy or simple answers to complex problems.

When it comes to dieting, researchers generally focus on several basic outcomes – weight maintenance, heart health, and glucose metabolism. You can also look at overall health outcomes, such as the risk of death over time. In terms of weight, there is only one factor that seems to matter – calories in vs calories out. This is the unavoidable reality, and there does not seem to be a way to game the system to significantly alter this equation. Proponents of special diets will argue that varying the proportion of macronutrients (fat, protein, and sugars) can affect metabolism. Some ironically argue that their recommended macronutrient balance will make metabolism “more efficient”. This is not necessarily a good thing when it comes to weight, however. Efficiency could mean getting more use out of fewer calories. If you want to waste energy (i.e. fat) you want to be inefficient.

But the bottom line of decades of research is that any effect of diets that vary macronutrient ratios on metabolism seem to have an insignificant effect on weight. You simply cannot get away from the massive factor of calories in vs calories out by slightly tweaking metabolism.

What does this current review show? Exactly that. First they find, as with most prior research, that the two diets do result in short-term weight loss. Pretty much all diets do. However, they also found that long term research (meaning up to 12 months) show that any short term advantage is lost and not sustainable. Since the goal of weight management is long term control, a short term reversible and small advantage does not contribute to this goal. It may, in fact, backfire. It is a distraction from effective long term behavioral changes. And some studies show that the rebound weight gain is greater. The review also concludes that any short term weight loss may be due to simply reducing calories, not any metabolic change. That is still the overall conclusion of the totality of dieting research – that any observed weight loss is due to reduced calories and not some other factor.

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Aug 31 2020

Elon Musk Unveils Neuralink Pig

Three days ago Elon Musk revealed an update to his Neuralink project – a pig named Gertrude that had the latest version of the Neuralink implanted. (I first wrote about the Neuralink here.) The demonstration does not seem to involve anything that itself is new with brain-machine interfaces, but it does represent Musk bringing the state of the art together into a device that is designed to be commercial, rather than just a laboratory proof-of-concept.

Unfortunately, I have had to cobble together information from multiple sources. There does not appear to be a scientific paper with all the technical details spelled out, and the mainstream reporting is often vague on those details. But I think I have a clear picture now. The device is a coin-sized, 23 mm diameter and 8 mm thick. It was implanted “in” the skull, and also described as being “flush” with the skull. From this I take it that the device is not on top of or inside the skull, but literally replacing a small piece of skull. It has 3,000 super thin and flexible electrodes that connect to 1000 neurons. The device itself has 1024 channels (a channel reads the electrical difference between two electrodes).

The company also reports that it has an internal battery that can last “all day” and then recharge overnight. It also communicates to an external device (such as an app on your smartphone) via bluetooth with a range of 5-10 meters. As an electronic device, this is pretty standard, but it is good to have these features in a small implantable device.

The big question is – what can the Neuralink actually do? The demonstration, in this regard, was not that impressive (compared to the hype for Neuralink) – just the absolute bare minimum for such a device. It was implanted in a pig and was interfaced with neurons that connect to the snout. This demo device was read only; it could not send signals to the pig’s brain, only read from the brain. The demonstration consisted of Gertrude sniffing around her cage, and when she did so we could see signals from the neurons in her brain that were interfacing with the Neuralink.

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Aug 27 2020

Nuclear Diamond Batteries

Articles are making the rounds on social media claiming a new battery technology that can make batteries that will last 28,000 years on a single charge. There is some truth to these claims, but they are mostly misleading. They make some unwarranted claims and leave out some critical context. This is likely mostly corporate self-promotion and fishing for investors, but what is the real science behind the claims?

Here is a typical quote form the popular press:

While they would be undeniably useful in EVs, their long life also makes them perfect for devices like pacemakers.

The company claims that its technology can be scaled up, and it could be used to make battery packs suitable for an electric car that lasts up to 90 years.

It is completely deniable that they would be useful in EVs, and I am always skeptical of claims that a technology can be “scaled up”. That should never be taken as a given, and is often the deal-killer with new technology. But let me review what these batteries actually are and then put the claims into context.

The concept was first introduced in the UK in 2016 – the idea is to encase nuclear waste in diamond so that the beta-decay of the waste interacts with the carbon in the diamond to generate a small electric current. The version being presented as a nuclear diamond battery (NDB) uses carbon-14 from graphite reactor rods as the source of beta decay. This represents a small percentage of the radioactivity of nuclear waste, 95% of which is the spent fuel itself, but the graphite waste is now also radioactive and there is a lot of it, about 250,000 tonnes world-wide.

The idea behind NDBs is that you make artificial diamond out of the carbon-14 from waste graphite from nuclear reactors. This would have the side benefit of taking care of some of the nuclear waste stream. Beta decay from the carbon-14 within the diamond would interact with other molecules causing the release of electrons and the generation of a small current. The entire thing could be encased in non-radioactive artificial diamond, which would prevent the escape of radiation and also protect it from damage.

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Aug 25 2020

Supernova Mass Extinction

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Over the history of life on Earth there have been many extinction events, but the top 5 mass extinctions are the big ones. Fortunately, such events don’t happen often. Understanding what caused these massive die-offs is inherently interesting, just so that we better understand the world, but might also provide some insight into potential future threats. A recent study suggests an interesting potential cause for one of these mass extinctions – nearby supernova.

These 5 mass extinction events are:

Ordovician-Silurian extinction – 444 million years ago – this is thought to have been caused by global cooling, resulting in increased polar ice, dropping of the ocean which reduced shallow habitats and changed its chemistry, allowing for more toxic minerals and less oxygen. This extinction saw the loss of 85% of species.

Late Devonian extinctions – 383-359 million years ago – this extinction correlates with a dramatic decrease in ocean oxygenation. The cause of this drop is not well understood, but candidates include asteroid impact, volcanic eruptions, and increased soil weathering due to the evolution of land plants. The species loss in this extinction was 70-80%.

Permian-Triassic extinction – 252 million years ago – this is the biggest mass extinction on Earth ever. Over 96% of sea species, and 75% of land species went extinct over about 60,000 years. Ecosystems did not recover for millions of years. These numbers actually underestimate the devastation, as these are the loss of species. But if you look at individual creatures, almost everything on Earth died, which just the slightest residue of life left. This was probably triggered by massive volcanic activity, releasing CO2, warming the planet, and causing acid rain.

Triassic-Jurassic extinction – 201 million years ago – this was caused also by global warming from an increase in atmospheric CO2 by a factor of four. This was in turn also caused by volcanic activity – this time from the Central Atlantic Magmatic Province. In this extinction about 80% of species were lost.

Cretaceous-Paleogene extinction – 66 million years ago – this is the one everyone knows about, because it saw the end of the non-avian dinosaurs. This was almost certainly caused by a large impact, but there persists a minority opinion regarding the contribution of volcanic activity from the Deccan Traps in what is now India. Along with the non-avian dinosaurs, 76% of species on Earth went extinct.

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Aug 24 2020

A Controllable Metalens

This is a (sort of) follow up to a previous post I wrote back in March about extreme depth-of-focus tiny flat nanolenses. The big ideas was that researchers are rapidly developing the technology to build a lens out of metamaterial that is structured on the nanoscale. Instead of using a large piece of curved glass to control light, these metalenses use the nanostructure on thin flat lenses. What impressed me at the time was the incredible potential applications of such tiny lenses, from cameras to medical applications. In fact, this tech was deemed one of the top ten emerging technologies in the 2019 World Economic Forum.

Now researchers have taken this technology one important step further – a method for possible dynamic control, meaning that these lenses can be focused and zoomed.

What the researchers did was infiltrate a metalens with “nematic liquid crystals”. This is the same technology used in liquid crystal displays – LCD monitors. They are basically transparent to translucent liquids that refract light like a lens. But the key with liquid crystals is that their properties can be modified by an external electric field (and also magnetically, thermally, or optically). They showed that they were able to “nontrivially” infiltrate the metalens with liquid crystals, and that this changed the optical properties of the metalens. They conclude:

By harnessing the tunability inherent in the orientation dependent refractive index of the infiltrated liquid crystal, the metalens system considered here has the potential to enable dynamic reconfigurability in metasurfaces.

In other words – they made the metalens tunable – this is a lens that cannot only be focused, but also can increase or decrease its magnification. In camera speak – this is a zoom lens. (“Telephoto lens” is a high magnification narrow focus lens, while a “zoom” lens can change its magnification.)

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Aug 20 2020

Opening Schools During a Pandemic

This is the big question facing many countries, but especially the US – how do we reopen schools while still in the middle of a pandemic? This is a serious dilemma. The American Academy of Pediatrics urges that, especially younger children, have the opportunity for in-person learning.  This is important not only for their education but their socialization and development.

The other important variable here, however, is how susceptible are children to SARS-CoV-2 and the COVID-19 infection it causes? Early experience showed that children are less susceptible to getting the illness and when they are infected are less likely to have serious disease. This partly informed the AAP’s recommendation. However – more recent data is casting doubt on the notion that children can safely return to school.

The most comprehensive review of the data so far, just published, shows that children are asymptomatic carriers of the virus, and have high viral loads, which means they can be very contagious. Further, when they do get symptoms they are likely to be more like cold symptoms, with a fever and runny nose, which in adults makes it less likely they have COVID-19. These two factors mean that children have been widely underdiagnosed. Most testing programs are focusing on symptomatic individuals, and children get missed by such efforts.

The review also concludes that a small percentage of children can get a late-stage complication of COVID-19, even if the illness is mild or asymptomatic – their immune reaction several weeks after infection can cause serious illness, including heart disease. This is one of the serious features of this illness, the immune system’s response can sometimes be severe, causing much more damage than the infection itself.

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Aug 18 2020

How Algorithms Affect Your Life

This is one of those things that futurists did not predict at all, but now seems obvious and unavoidable – the degree to which computer algorithms affect your life. It’s always hard to make negative statements, and they have to be qualified – but I am not aware of any pre-2000 science fiction or futurism that even discussed the role of social media algorithms or other informational algorithms on society and culture (as always, let me know if I’m missing something). But in a very short period of time they have become a major challenge for many societies. It also is now easy to imagine how computer algorithms will be a dominant topic in the future. People will likely debate their role, who controls them and who should control them, and what regulations, if any, should be put in place.

The worse outcome is if this doesn’t happen, meaning that people are not aware of the role of algorithms in their life and who controls them. That is essentially what is happening in China and other authoritarian nations. Social media algorithms are an authoritarian’s dream – they give them incredible power to control what people see, what information they get exposed to, and to some extent what they think. This is 1984 on steroids. Orwell imagined that in order to control what and how people think authoritarians would control language (double-plus good). Constrain language and you constrain thought. That was an interesting idea pre-web and pre-social media. Now computer algorithms can control the flow of information, and by extension what people know and think, seamlessly, invisibly, and powerfully to a scary degree.

Even in open democratic societies, however, the invisible hand of computer algorithms can wreak havoc. Social scientists studying this phenomenon are increasing sounding warning bells. A recent example is an anti-extremist group in the UK who now are warning, according to their research, that Facebook algorithms are actively promoting holocaust denial and other conspiracy theories. They found, unsurprisingly, that visitors to Facebook pages that deny the holocaust were then referred to other pages that also deny the holocaust. This in turn leads to other conspiracies that also refer to still other conspiracy content, and down the rabbit hole you go.

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Aug 17 2020

Adding Sound to AI

It has been fascinating, perhaps especially so as a neuroscientist, to watch the progress being made in artificial intelligence (AI), robotics, and brain-machine interface. Our understanding of biological intelligence is progressing in tandem with our attempts to replicate some of the functioning of that intelligence, as well as interface with it. Neuroscience and AI/robotics inform each other.

Here is another example of that – adding sound to the perception of an AI/robotic system to help it distinguish different objects. Before now AI object recognition has mostly been purely visual. (I always qualify these statements because I am not aware of every lab in the world that might be working on such things.) Visual object recognition is a good place to start, and this is what we probably think of when we imagine identifying an object ourselves – we look at it and compare it to our mental database of known objects. That is how our visual processing works.

But that is also not the whole story. We tend to underestimate, or simply not be aware of, the extent to which our brain are simultaneously processing multiple different sensory modalities to make sense of the world. When we listen to someone talk, for example, our brains also process the movement of their lips in order to make sense of the sounds as language (this is called the McGurk effect). When we identify someone else’s probable gender, we are strongly influenced by their voice.

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Aug 13 2020

Soft Tiny Robots

We are already living in the age of robots, but they are mostly hidden from our daily lives. Unless you have a job that entails interacting with a robot, the ones you see are mostly novelties, like Roombas, or the googly-eyed robots now wandering around some supermarkets.  Robots, however, are an iconic fixture of “the future”, and have been for the better part of a century.

The robots envisioned by the retro-sci-fi of the 1950s have not materialized, outside movies, but in the background robotic tech has been advancing significantly. We all love to watch the videos of running and jumping robots by Boston Dynamics. The tech is getting amazing. But so far they remain mostly for industrial use – a robot in every home still seems like a phenomenon of the future, not the present. In this video the creators show off their robot who can, for example, deliver boxes. That’s impressive, but why would you use such expensive advanced tech  (and risk having it jacked) to do something a human can easily and more cheaply do? Robots are great for manufacturing, and dangerous environments, but for everyday tasks they are not quite there – still too expensive to be worth it.

What about going in the opposite direction – small and squishy robots? We don’t even have to be talking about nanotechnology, not microscopic robots, just small ones. There are lots of tasks that could benefit from a swarm of small robots, but the challenge here is powering and controlling them. Advance is being made with this tech as well, but again we are not quite there, and still at the point where we cannot predict how long it will take before that “killer app” has arrived.

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Aug 11 2020

Ceres an Ocean World

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It seems we can add the dwarf planet, Ceres, to the list of ocean worlds in the solar system. These are planets or moons that have vast oceans beneath their surface – Earth is the only world with stable liquid water on its surface. These worlds are of particular interest because liquid water means the potential for life.

Ceres is the largest object in the asteroid belt between Mars and Jupiter. When it was first discovered it was categorized as a planet. Then it was discovered that it was the largest member of a belt of objects, and so it was “downgraded” to an asteroid (although the king of the asteroids). But then in 2006 the International Astronomical Union (IAU) famously created the new category of dwarf planet. Pluto was then demoted from full planet status to dwarf planet, but Ceres was upgraded also to a dwarf planet. These are worlds that orbit the sun, are not satellites, are large enough to pull themselves into a rough sphere, but have not cleared out their orbit of other large objects.

The recent study, based on data from the Dawn probe which did close up high-resolution imaging of Ceres (coming as close as 35 km) strongly suggests that there is at least a regional subsurface briny ocean on Ceres. The bright spot in Occator crater, which formed 22 million years ago from an impact, appears to be salt left behind by salty water leaking to the surface at the site of impact. The water then evaporated, leaving behind the highly reflective salt. This bright spot is a very unusual feature, that quickly grabbed attention when the Dawn probe images were first coming back.

At the very least, therefore, there is a large salty ocean beneath that crater. It is unknown if the ocean is regional or global, but even if regional it still qualifies Ceres as an ocean world.  It joins the list which includes the moons of Jupiter Europa, Ganymede, and Callisto, the moons of Saturn Enceladus and Titan, and possible (still unconfirmed) Saturn moon Mimas and the moon of Neptune, Triton. Astronomers believe that the subsurface ocean of Ceres must be slowly freezing. Moons of gas giants have tidal forces to produce internal heat and keep their oceans liquid.

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