Science

new-e.-coli-strain-will-accelerate-evolution-of-the-genes-of-your-choice

New E. coli strain will accelerate evolution of the genes of your choice

biochemistry, Biology, E. coli, evolution, mutation rate, mutations, Science / /

Making mutants —

Strain eliminates the trade-offs of a high mutation rate.

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Woman holding a plate of bacteria with clusters of bacteria on it.

Genetic mutations are essential for innovation and evolution, yet too many—or the wrong ones—can be fatal. So researchers at Cambridge established a synthetic “orthogonal” DNA replication system in E. coli that they can use as a risk-free way to generate and study such mutations. It is orthogonal because it is completely separate from the system that E. coli uses to copy its actual genome, which contains the genes E. coli needs to survive.

The genes in the orthogonal system are copied with an extraordinarily error-prone DNA replication enzyme, which spurs rapid evolution by generating many random mutations. This goes on while E. coli’s genes are replicated by its normal high-fidelity DNA copying enzyme. The two enzymes work alongside each other, each doing their own thing but not interfering with the other’s genes.

Engineering rapid mutation

Such a cool idea, right? The scientists stole it from nature. Yeast already has a system like this, with a set of genes copied by a dedicated enzyme that doesn’t replicate the rest of the genome. But E. coli is much easier to work with than yeast, and its population can double in 20 minutes, so you can get a lot of rounds of replication and evolution done fast.

The researchers generated the system by pillaging a phage—a virus that infects E. coli. They took out all of the phage genes that allow the phage to grow uncontrollably until it bursts the E. coli cell it infected open. The engineering left only a cassette containing the genes responsible for copying the phage genome. Once this cassette was inserted into the E. coli genome, it could simultaneously replicate at least three different strings of genes placed next to it in the DNA, maintaining them for over a hundred generations—all while leaving the rest of the E. coli genome to be copied by other enzymes.

The scientists then tweaked the mutation rate of the orthogonal DNA-replicating enzyme, eventually enhancing it 1,000-fold. To test if the system could be used to evolve new functions, they inserted a gene for resistance to one antibiotic and saw how long it took for that gene to mutate into one conferring resistance to a different antibiotic. Within twelve days, they got 150 times more resistance to the new antibiotic. They also inserted the gene encoding green fluorescent protein and increased its fluorescence over 1,000-fold in five days.

Evolving detoxification

Not 20 pages later, in the same issue of Science, Frances Arnold’s lab has a paper that provides evidence of how powerful this approach could be. This team directed the evolution of an enzyme the old-fashioned way: through sequential rounds of random mutagenesis and selection for the desired trait. Arnold won The Nobel Prize in Chemistry 2018 for the directed evolution of enzymes, so she knows what she’s about. In this recent work, her lab generated an enzyme that can biodegrade volatile methyl siloxanes. We make megatons of these compounds every year to stick in cleaning products, shampoos and lotions, and industrial products, but they linger in the environment. They contain carbon-silicon bonds, which were never a thing until humans made them about 80 years ago; since nature never made these bonds, there is no natural way to break them, either.

“Directed evolution with siloxane was particularly challenging,” the authors note in their introduction, for various technical reasons. “We started from an enzyme we had previously engineered for other chemistry on siloxanes—that enzyme, unlike the natural enzyme, showed a tiny bit of activity for siloxane Si-C bond cleavage. The overall project, however, from initial discovery to figuring out how to measure what we wanted, took several years,” Arnold said. And it is only the first step in possibly rendering siloxanes biodegradable. The accelerated continuous evolution that the new orthologous system allows will hopefully greatly facilitate the development of enzymes and other proteins like this that will have applications in research, medicine, and industry.

We do not (yet) have machines that can efficiently assemble long stretches of DNA or make proteins. But cells do these things extremely efficiently, and E. coli cells have long been the ones used in the lab as little factories, churning out whatever genes or proteins researchers program into them. Now E. coli can be used for one more molecular task—they can be little hotbeds of evolution.

Science, 2024.  DOI: 10.1126/science.adi5554, 10.1126/science.adk1281

New E. coli strain will accelerate evolution of the genes of your choice Read More »

humans-are-living-longer-than-ever-no-matter-where-they-come-from 

Humans are living longer than ever no matter where they come from 

Biology, health, Longevity, public health, Science / /

Live long and prosper? —

Disease outbreaks and human conflicts help dictate regional differences in longevity.

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An older person drinking coffee in an urban environment.

Most of us want to stay on this planet as long as possible. While there are still differences depending on sex and region, we are now living longer as a species—and it seems life spans will only continue to grow longer.

Researcher David Atance of Universidad de Alcalá, Spain, and his team gathered data on the trends of the past. They then used their findings to project what we can expect to see in the future. Some groups have had it harder than others because of factors such as war, poverty, natural disasters, or disease, but the researchers found that morality and longevity trends are becoming more similar regardless of disparities between sexes and locations.

“The male-female gap is decreasing among the [clusters],” they said in a study recently published in PLOS One.

Remembering the past

The research team used specific mortality indicators—such as life expectancy at birth and most common age at death–to identify five global clusters that reflect the average life expectancy in different parts of the world. The countries in these clusters changed slightly from 1990 to 2010 and are projected to change further by 2030 (though 2030 projections are obviously tentative). Data for both males and females was considered when deciding which countries belonged in which cluster during each period. Sometimes, one sex thrived while the other struggled within a cluster—or even within the same country.

Clusters that included mostly wealthier countries had the best chance at longevity in 1990 and 2010. Low-income countries predictably had the worst mortality rate. In 1990, these countries, many of which are in Africa, suffered from war, political upheaval, and the lethal spread of HIV/AIDS. Rwanda endured a bloody civil war during this period. Around the same time, Uganda had tensions with Rwanda, as well as Sudan and Zaire. In the Middle East, the Gulf War and its aftermath inevitably affected 1990 male and female populations.

Along with a weak health care system, the factors that gave most African countries a high mortality rate were still just as problematic in 2010. In all clusters, male life spans tended to differ slightly less between countries than female life spans. However, in some regions, there were differences between how long males lived compared to females. Mortality significantly increased in 1990 male populations from former Soviet countries after the dissolution of the Soviet Union, and this trend continued in 2010. Deaths in those countries were attributed to violence, accidents, cardiovascular disease, alcohol, an inadequate healthcare system, poverty, and psychosocial stress.

Glimpsing the future

2030 predictions must be taken with caution. Though past trends can be good indicators of what is to come, trends do not always continue. While things may change between now and 2030 (and those changes could be drastic), these estimates project what would happen if past and current trends continue into the relatively near future.

Some countries might be worse off in 2030. The lowest-income, highest-mortality cluster will include several African countries that have been hit hard with wars as well as political and socioeconomic challenges. The second low-income, high-mortality cluster, also with mostly African countries, will now add some Eastern European and Asian countries that suffer from political and socioeconomic issues most have recently been involved in conflicts and wars or still are, such as Ukraine.

The highest-income, lowest-mortality cluster will gain some countries. These include Chile, which has made strides in development that are helping people live longer.

Former Soviet countries will probably continue to face the same issues they did in 1990 and 2010. They fall into one of the middle-income, mid-longevity clusters and will most likely be joined by some Latin American countries that were once in a higher bracket but presently face high levels of homicide, suicide, and accidents among middle-aged males. Meanwhile, there are some other countries in Latin America that the research team foresees as moving toward a higher income and lower mortality rate.

Appearances can be deceiving

The study places the US in the first or second high-income, low-mortality bracket, depending on the timeline. This could make it look like it is doing well on a global scale. While the study doesn’t look at the US specifically, there are certain local issues that say otherwise.

A 2022 study by the Centers for Disease Control and Prevention suggests that pregnancy and maternal care in the US is abysmal, with a surprisingly high (and still worsening) maternal death rate of about 33 deaths per 100,000 live births. This is more than double what it was two decades ago. In states like Texas, which banned abortion after the overturn of Roe v. Wade, infant deaths have also spiked. The US also has the most expensive health care system among high-income countries, which was only worsened by the pandemic.

The CDC also reports that life expectancy in the US keeps plummeting. Cancer, heart disease, stroke, drug overdose, and accidents are the culprits, especially in middle-aged Americans. There has also been an increase in gun violence and suicides. Guns have become the No. 1 killer of children and teens, which used to be car accidents.

Whether the US will stay in that top longevity bracket is also unsure, especially if maternal death rates keep rising and there aren’t significant improvements made to the health care system. There and elsewhere, there’s no way of telling what will actually happen between now and 2030, but Atance and his team want to revisit their study then and compare their estimates to actual data. The team is also planning to further analyze the factors that contribute to longevity and mortality, as well as conduct surveys that could support their predictions. We will hopefully live to see the results.

PLOS One, 2024. DOI:  10.1371/journal.pone.0295842

Humans are living longer than ever no matter where they come from  Read More »

hermit-crabs-find-new-homes-in-plastic-waste:-shell-shortage-or-clever choice?

Hermit crabs find new homes in plastic waste: Shell shortage or clever choice?

hermit crabs, Science, syndication / /

ocean real estate bargains —

The crustaceans are making the most of what they find on the seafloor.

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hermit crab in plastic pen cap

Enlarge / Scientists have found that hermit crabs are increasingly using plastic and other litter as makeshift shell homes.

Land hermit crabs have been using bottle tops, parts of old light bulbs and broken glass bottles, instead of shells.

New research by Polish researchers studied 386 images of hermit crabs occupying these artificial shells. The photos had been uploaded by users to online platforms, then analyzed by scientists using a research approach known as iEcology. Of the 386 photos, the vast majority, 326 cases, featured hermit crabs using plastic items as shelters.

At first glance, this is a striking example of how human activities can alter the behavior of wild animals and potentially the ways that populations and ecosystems function as a result. But there are lots of factors at play and, while it’s easy to jump to conclusions, it’s important to consider exactly what might be driving this particular change.

Shell selection

Hermit crabs are an excellent model organism to study because they behave in many different ways and those differences can be easily measured. Instead of continuously growing their own shell to protect their body, like a normal crab or a lobster would, they use empty shells left behind by dead snails. As they walk around, the shell protects their soft abdomen but whenever they are threatened they retract their whole body into the shell. Their shells act as portable shelters.

Having a good enough shell is critical to an individual’s survival so they acquire and upgrade their shells as they grow. They fight other hermit crabs for shells and assess any new shells that they might find for suitability. Primarily, they look for shells that are large enough to protect them, but their decision-making also takes into account the type of snail shell, its condition and even its color—a factor that could impact how conspicuous the crab might be.

Another factor that constrains shell choice is the actual availability of suitable shells. For some as yet unknown reason, a proportion of land hermit crabs are choosing to occupy plastic items rather than natural shells, as highlighted by this latest study.

Housing crisis or ingenious new move?

Humans have intentionally changed the behavior of animals for millennia through the process of domestication. Any unintended behavioral changes in natural animal populations are potentially concerning, but how worried should we be about hermit crabs using plastic litter as shelter?

The Polish research raises a number of questions. First, how prevalent is the adoption of plastic litter instead of shells? While 326 crabs using plastic seems like a lot, this is likely to be an underestimation of the raw number given that users are likely to encounter crabs only in accessible parts of the populations. Conversely, it seems probable that users could be biased towards uploading striking or unusual images, so the iEcology approach might produce an exaggerated impression of the proportion of individuals in a population opting for plastic over natural shells. We need structured field surveys to clarify this.

Second, why are some individual crabs using plastic? One possibility is that they are forced to due to a lack of natural shells, but we can’t test this hypothesis without more information on the demographics of local snail populations. Or perhaps the crabs prefer plastic or find it easier to locate, compared with real shells? As the authors point out, plastic might be lighter than the equivalent shells affording the same amount of protection but at lower energy cost of carrying them. Intriguingly, chemicals that leach out of plastic are known to attract marine hermit crabs by mimicking the odor of food.

As hermit crabs adapt to an increase in plastic pollution, more research is needed to investigate the nuances.

Enlarge / As hermit crabs adapt to an increase in plastic pollution, more research is needed to investigate the nuances.

This leads to a third question about the possible downsides of using plastic. Compared to real shells plastic waste tends to be brighter and might contrast more with the background making the crabs more vulnerable to predators. Additionally, we know that exposure to microplastics and compounds that leach from plastic can change the behaviour of hermit crabs, making them less fussy about the shells that they choose, less adept at fighting for shells and even changing their personalities by making them more prone to take risks. To answer these questions about the causes and consequences of hermit crabs using plastic waste in this way, we need to investigate their shell selection behavior through a series of laboratory experiments.

Pollution changes behavior

Plastic pollution is just one of the ways we are changing our environment. It’s by far the most highly reported form of debris that we have introduced to marine environments. But animal behavior is affected by other forms of pollution too, including microplastics, pharmaceuticals, light, and noise, plus the rising temperatures and ocean acidification caused by climate change.

So while investigating the use of plastic waste by hermit crabs could help us better understand the consequences of certain human impacts on the environment, it doesn’t show how exactly animals will adjust to the Anthropocene, the era during which human activity has been having a significant impact on the planet. Will they cope by using plastic behavioral responses or evolve across generations, or perhaps both? In my view, the iEcology approach cannot answer questions like this. Rather, this study acts as an alarm bell highlighting potential changes that now need to be fully investigated.

Mark Briffa, Professor of Animal Behaviour, University of Plymouth. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Hermit crabs find new homes in plastic waste: Shell shortage or clever choice? Read More »

daily-telescope:-a-wolf-rayet-star-puts-on-a-howling-light-show

Daily Telescope: A Wolf-Rayet star puts on a howling light show

daily telescope, Science, Space / /

Hungry like the wolf —

I’d like to see it go boom.

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The Crescent Nebula.

Enlarge / The Crescent Nebula.

1Zach1

Welcome to the Daily Telescope. There is a little too much darkness in this world and not enough light, a little too much pseudoscience and not enough science. We’ll let other publications offer you a daily horoscope. At Ars Technica, we’re going to take a different route, finding inspiration from very real images of a universe that is filled with stars and wonder.

Good morning. It’s February 2, and today’s image concerns an emission nebula about 5,000 light-years away in the Cygnus constellation.

Discovered more than 230 years ago by William Herschel, astronomers believe the Crescent Nebula is formed by the combination of an energetic stellar wind from a Wolf-Rayet star at its core, colliding with slower-moving material ejected earlier in the star’s lifetime. Ultimately, this should all go supernova, which will be quite spectacular.

Will you or I be alive to see it? Probably not.

But in the meantime, we can enjoy the nebula for what it is. This photo was captured by Ars reader 1Zach1 with an Astro-Tech AT80ED Refractor telescope. It was the product of 11 hours of integration, or 228 exposures each lasting three minutes. It was taken in rural southwestern Washington.

Have a great weekend, everyone.

Source: 1Zach1

Do you want to submit a photo for the Daily Telescope? Reach out and say hello.

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why-interstellar-objects-like-‘oumuamua-and-borisov-may-hold-clues-to-exoplanets

Why interstellar objects like ‘Oumuamua and Borisov may hold clues to exoplanets

‘Oumuamua, Borisov, exoplanets, Science, Space, syndication / /

celestial nomads —

Two celestial interlopers in Solar System have scientists eagerly anticipating more.

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The first interstellar interloper detected passing through the Solar System, 1l/‘Oumuamua, came within 24 million miles of the Sun in 2017

Enlarge / The first interstellar interloper detected passing through the Solar System, 1l/‘Oumuamua, came within 24 million miles of the Sun in 2017. It’s difficult to know exactly what ‘Oumuamua looked like, but it was probably oddly shaped and elongated, as depicted in this illustration.

On October 17 and 18, 2017, an unusual object sped across the field of view of a large telescope perched near the summit of a volcano on the Hawaiian island of Maui. The Pan-STARRS1 telescope was designed to survey the sky for transient events, like asteroid or comet flybys. But this was different: The object was not gravitationally bound to the Sun or to any other celestial body. It had arrived from somewhere else.

The mysterious object was the first visitor from interstellar space observed passing through the Solar System. Astronomers named it 1I/‘Oumuamua, borrowing a Hawaiian word that roughly translates to “messenger from afar arriving first.” Two years later, in August 2019, amateur astronomer Gennadiy Borisov discovered the only other known interstellar interloper, now called 2I/Borisov, using a self-built telescope at the MARGO observatory in Nauchnij, Crimea.

While typical asteroids and comets in the Solar System orbit the Sun, ‘Oumuamua and Borisov are celestial nomads, spending most of their time wandering interstellar space. The existence of such interlopers in the Solar System had been hypothesized, but scientists expected them to be rare. “I never thought we would see one,” says astrophysicist Susanne Pfalzner of the Jülich Supercomputing Center in Germany. At least not in her lifetime.

With these two discoveries, scientists now suspect that interstellar interlopers are much more common. Right now, within the orbit of Neptune alone, there could be around 10,000 ‘Oumuamua-size interstellar objects, estimates planetary scientist David Jewitt of UCLA, coauthor of an overview of the current understanding of interstellar interlopers in the 2023 Annual Review of Astronomy and Astrophysics.

Researchers are busy trying to answer basic questions about these alien objects, including where they come from and how they end up wandering the galaxy. Interlopers could also provide a new way to probe features of distant planetary systems.

But first, astronomers need to find more of them.

“We’re a little behind at the moment,” Jewitt says. “But we expect to see more.”

2I/Borisov appears as a fuzzy blue dot in front of a distant spiral galaxy (left) in this November 2019 image taken by the Hubble Space Telescope when the object was approximately 200 million miles from Earth.

Enlarge / 2I/Borisov appears as a fuzzy blue dot in front of a distant spiral galaxy (left) in this November 2019 image taken by the Hubble Space Telescope when the object was approximately 200 million miles from Earth.

Alien origins

At least since the beginning of the 18th century, astronomers have considered the possibility that interstellar objects exist. More recently, computer models have shown that the Solar System sent its own population of smaller bodies into the voids of interstellar space long ago due to gravitational interactions with the giant planets.

Scientists expected most interlopers to be exocomets composed of icy materials. Borisov fit this profile: It had a tail made of gases and dust created by ices that evaporated during its close passage to the Sun. This suggests that it originated in the outer region of a planetary system where temperatures were cold enough for gases like carbon monoxide to have frozen into its rocks. At some point, something tossed Borisov, roughly a kilometer across, out of its system.

One potential culprit is a stellar flyby. The gravity of a passing star can eject smaller bodies, known as planetesimals, from the outer reaches of a system, according to a recent study led by Pfalzner. A giant planet could also eject an object from the outer regions of a planetary system if an asteroid or comet gets close enough for the planet’s gravitational tug to speed up the smaller body enough for it to escape its star’s hold. Close approaches can also happen when planets migrate across their planetary systems, as Neptune is thought to have done in the early Solar System.

Why interstellar objects like ‘Oumuamua and Borisov may hold clues to exoplanets Read More »

our-oldest-microbial-ancestors-were-way-ahead-of-their-time

Our oldest microbial ancestors were way ahead of their time

Biology, eukaryotes, evolution, paleontology, Science / /

Going Golgi —

Specialized internal structures were present over 1.5 billion years ago.

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computer generated image of membrane structures inside a cell

Enlarge / The Golgi apparatus, shown here in light green, may have been involved in building internal structures in cells.

ARTUR PLAWGO / SCIENCE PHOTO LIBRARY

Before Neanderthals and Denisovans, before vaguely humanoid primates, proto-mammals, or fish that crawled out of the ocean to become the first terrestrial animals, our earliest ancestors were microbes.

More complex organisms like ourselves descend from eukaryotes, which have a nuclear membrane around their DNA (as opposed to prokaryotes, which don’t). Eukaryotes were thought to have evolved a few billion years ago, during the late Palaeoproterozoic period, and started diversifying by around 800 million years ago. Their diversification was not well understood. Now, a team of researchers led by UC Santa Barbara paleontologist Leigh Ann Riedman discovered eukaryote microfossils that are 1.64 billion years old, yet had already diversified and had surprisingly sophisticated features.

“High levels of eukaryotic species richness and morphological disparity suggest that although late Palaeoproterozoic [fossils] preserve our oldest record of eukaryotes, the eukaryotic clade has a much deeper history,” Riedman and her team said in a study recently published in Papers in Paleontology.

Really, really, really old tricks

During the late Palaeoproterozoic, eukaryotes most likely evolved in the wake of several major changes on Earth, including a drastic increase in atmospheric oxygen and shifts in ocean chemistry. This could have been anywhere from 3 billion to 2.3 billion years ago. Riedman’s team explored the layers of sedimentary rock in the Limbunya region of Australia’s Birrindudu basin. The fossils they unearthed included a total of 26 taxa, as well as 10 species that had not been described before. One of them is Limbunyasphaera operculata, a species of the new genus Limbunyasphera.

What makes L. operculata so distinct is that it has a feature that appears to be evidence of a survival mechanism used by modern eukaryotes. There are some extant microbes that form a protective cyst so they can make it through harsh conditions. When things are more tolerable, they produce an enzyme that dissolves a part of the cyst wall into an opening, or pylome, that makes it possible for them to creep out. This opening also has a lid, or operculum. These were both observed in L. operculata.

While splits in fossilized single-cell organisms may be the result of taphonomic processes that break the cell wall, complex structures such as a pylome and operculum are not found in prokaryotic organisms, and therefore suggest that a species must be eukaryotic.

Didn’t know they could do that

Some of the previously known species of extinct eukaryotes also surprised the scientists with unexpectedly advanced features. Satka favosa had a vesicle in the cell that was enclosed by a membrane with platelike structures. Another species, Birrindudutuba brigandinia, also had plates identified around its vesicles, although none of its plates were as diverse in shape as those seen in different S. favosa individuals. Those plates came in a large variety of shapes and sizes, which could mean that what has been termed S. favosa is more than one species.

The plated vesicle of S. favosa is what led Riedman to determine that the species must have been eukaryotic, because the plates are possible indicators that Golgi bodies existed in these organisms. After the endoplasmic reticulum of a cell synthesizes proteins and lipids, Golgi bodies process and package those substances depending on where they have to go next. Riedman and her team think that Golgi or Golgi-like bodies transported materials within the cell to form plates around vesicles, such as the ones seen in S. favosa. The hypothetical Golgi bodies themselves are not thought to have had these plates.

This sort of complex sorting of cellular contents is a feature of all modern eukaryotes. “Taxa including Satka favosa… are considered [eukaryotes] because they have a complex, platy vesicle construction,” the researchers said in the study. These new fossils suggest that it arose pretty early in their history.

Eukaryotes have evidently been much more complex and diverse than we thought for hundreds of millions of years longer than we thought. There might be even older samples out there. While fossil evidence of eukaryotes from near their origin eludes us, samples upwards of a billion years old, such as those found by Riedman and her team, are telling us more than ever about their—and therefore our—evolution.

Papers in Paleontology, 2023.  DOI: 10.1002/spp2.1538

Our oldest microbial ancestors were way ahead of their time Read More »

over-2-percent-of-the-us’s-electricity-generation-now-goes-to-bitcoin

Over 2 percent of the US’s electricity generation now goes to bitcoin

Bitcoin, Cryptocurrency, Energy, mining, Science, Sustainability / /

Mining stakes —

US government tracking the energy implications of booming bitcoin mining in US.

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Digital generated image of golden helium balloon in shape of bitcoin sign inflated with air pump and moving up against purple background.

Enlarge / It takes a lot of energy to keep pumping out more bitcoins.

What exactly is bitcoin mining doing to the electric grid? In the last few years, the US has seen a boom in cryptocurrency mining, and the government is now trying to track exactly what that means for the consumption of electricity. While its analysis is preliminary, the Energy Information Agency (EIA) estimates that large-scale cryptocurrency operations are now consuming over 2 percent of the US’s electricity. That’s roughly the equivalent of having added an additional state to the grid over just the last three years.

Follow the megawatts

While there is some small-scale mining that goes on with personal computers and small rigs, most cryptocurrency mining has moved to large collections of specialized hardware. While this hardware can be pricy compared to personal computers, the main cost for these operations is electricity use, so the miners will tend to move to places with low electricity rates. The EIA report notes that, in the wake of a crackdown on cryptocurrency in China, a lot of that movement has involved relocation to the US, where keeping electricity prices low has generally been a policy priority.

One independent estimate made by the Cambridge Centre for Alternative Finance had the US as the home of just over 3 percent of the global bitcoin mining at the start of 2020. By the start of 2022, that figure was nearly 38 percent.

The Cambridge Center also estimates the global electricity use of all bitcoin mining, so it’s possible to multiply that by the US’s percentage and come up with an estimate for the amount of electricity that boom has consumed. Because of the uncertainties in these estimates, the number could be anywhere from 25 to 91 Terawatt-hours. Even the low end of that range would mean bitcoin mining is now using the equivalent of Utah’s electricity consumption (the high end is roughly Washington’s), which has significant implications for the electric grid as a whole.

So, the EIA decided it needed a better grip on what was going on. To get that, it went through trade publications, financial reports, news articles, and congressional investigation reports to identify as many bitcoin mining operations as it could. With 137 facilities identified, it then inquired about the power supply needed to operate them at full capacity, receiving answers for 101 of those facilities.

If running all-out, those 101 facilities would consume 2.3 percent of the US’s average power demand. That places them on the high side of the Cambridge Center estimates.

Finding power-ups

The mining operations fall in two major clusters: one in Texas, and one extending from western New York down the Appalachians to southern Georgia. While there are additional ones scattered throughout the US, these are the major sites.

The EIA has also found some instances where the operations moved in near underutilized power plants and sent generation soaring again. Tracking the history of five of these plants showed that generation had fallen steadily from 2015 to 2020, reaching a low where they collectively produced just half a Terawatt-hour. Miners moving in nearby tripled production in just a year and has seen it rise to over 2 Terawatt-hours in 2022.

Power plants near bitcoin mining operations have seen generation surge over the last two years.

Enlarge / Power plants near bitcoin mining operations have seen generation surge over the last two years.

These are almost certainly fossil fuel plants that might be reasonable candidates for retirement if it weren’t for their use to supply bitcoin miners. So, these miners are contributing to all of the health and climate problems associated with the continued use of fossil fuels.

The EIA also found a number of strategies that miners used to keep their power costs low. In one case, they moved into a former aluminum smelting facility in Texas to take advantage of its capacious connections to the grid. In another, they put a facility next to a nuclear plant in Pennsylvania and set up a direct connection to the plant. The EIA also found cases where miners moved near natural gas fields that produced waste methane that would otherwise have been burned off.

Since bitcoin mining is the antithesis of an essential activity, several mining operations have signed up for demand-response programs, where they agree to take their operations offline if electricity demand is likely to exceed generating capacity in return for compensation by the grid operator. It has been widely reported that one facility in Texas—the one at the former aluminum smelter site—earned over $30 million by shutting down during a heat wave in 2023.

To better understand the implications of this major new drain on the US electric grid, the EIA will be performing monthly analyses of bitcoin operations during the first half of 2024. But based on these initial numbers, it’s clear that the relocation of so many mining operations to the US will significantly hinder efforts to bring the US’s electric grid to carbon neutrality.

Over 2 percent of the US’s electricity generation now goes to bitcoin Read More »

mathematicians-finally-solved-feynman’s-“reverse-sprinkler”-problem

Mathematicians finally solved Feynman’s “reverse sprinkler” problem

fluid dynamics, mathematical modeling, mathematical physics, Physics, reverse sprinkler, Richard Feynman, Science / /

A decades-old conundrum —

We might not need to “unwater” our lawns, but results could help control fluid flows.

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Light-scattering microparticles reveal the flow pattern for the reverse (sucking) mode of a sprinkler, showing vortices and complex flow patterns forming inside the central chamber. Credit: K. Wang et al., 2024

A typical lawn sprinkler features various nozzles arranged at angles on a rotating wheel; when water is pumped in, they release jets that cause the wheel to rotate. But what would happen if the water were sucked into the sprinkler instead? In which direction would the wheel turn then, or would it even turn at all? That’s the essence of the “reverse sprinkler” problem that physicists like Richard Feynman, among others, have grappled with since the 1940s. Now, applied mathematicians at New York University think they’ve cracked the conundrum, per a recent paper published in the journal Physical Review Letters—and the answer challenges conventional wisdom on the matter.

“Our study solves the problem by combining precision lab experiments with mathematical modeling that explains how a reverse sprinkler operates,” said co-author Leif Ristroph of NYU’s Courant Institute. “We found that the reverse sprinkler spins in the ‘reverse’ or opposite direction when taking in water as it does when ejecting it, and the cause is subtle and surprising.”

Ristroph’s lab frequently addresses these kinds of colorful real-world puzzles. For instance, back in 2018, Ristroph and colleagues fine-tuned the recipe for the perfect bubble based on experiments with soapy thin films. (You want a circular wand with a 1.5-inch perimeter, and you should gently blow at a consistent 6.9 cm/s.) In 2021, the Ristroph lab looked into the formation processes underlying so-called “stone forests” common in certain regions of China and Madagascar. These pointed rock formations, like the famed Stone Forest in China’s Yunnan Province, are the result of solids dissolving into liquids in the presence of gravity, which produces natural convective flows.

In 2021, his lab built a working Tesla valve, in accordance with the inventor’s design, and measured the flow of water through the valve in both directions at various pressures. They found the water flowed about two times slower in the nonpreferred direction. And in 2022, Ristroph studied the surpassingly complex aerodynamics of what makes a good paper airplane—specifically what is needed for smooth gliding. They found that paper airplane aerodynamics differ substantially from conventional aircraft, which rely on airfoils to generate lift.

Mechanik (1883).” data-height=”1298″ data-width=”1200″ href=”https://cdn.arstechnica.net/wp-content/uploads/2024/02/feynman7.jpg”>Illustration of a Mechanik (1883).” height=”692″ src=”https://cdn.arstechnica.net/wp-content/uploads/2024/02/feynman7-640×692.jpg” width=”640″>

Enlarge / Illustration of a “reaction wheel” from Ernst Mach’s Mechanik (1883).

Public domain

The reverse sprinkler problem is associated with Feynman because he popularized the concept, but it actually dates back to a chapter in Ernst Mach’s 1883 textbook The Science of Mechanics (Die Mechanik in Ihrer Entwicklung Historisch-Kritisch Dargerstellt). Mach’s thought experiment languished in relative obscurity until a group of Princeton University physicists began debating the issue in the 1940s.

Feynman was a graduate student there at the time and threw himself into the debate with gusto, even devising an experiment in the cyclotron laboratory to test his hypothesis. (In true Feynman fashion, that experiment culminated with the explosion of a glass carboy used in the apparatus because of the high internal pressure.)

One might intuit that a reverse sprinkler would work just like a regular sprinkler, merely played backward, so to speak. But the physics turns out to be more complicated. “The answer is perfectly clear at first sight,” Feynman wrote in Surely You’re Joking, Mr. Feynman (1985). “The trouble was, some guy would think it was perfectly clear [that the rotation would be] one way, and another guy would think it was perfectly clear the other way.”

Mathematicians finally solved Feynman’s “reverse sprinkler” problem Read More »

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Starlab—with half the volume of the ISS—will fit inside Starship’s payload bay

commercial space stations, Science, Space, starlab, starship / /

It’s full of stars —

“Building and integrating in space is very expensive.”

–

An artist's concept of the Starlab space station.

Enlarge / An artist’s concept of the Starlab space station.

Starlab LLC

The Starlab commercial space station will launch on SpaceX’s Starship rocket, officials said this week.

Starlab is a joint venture between the US-based Voyager Space and the European-based multinational aerospace corporation Airbus. The venture is building a large station with a habitable volume equivalent to half the pressurized volume of the International Space Station and will launch the new station no earlier than 2028.

“SpaceX’s history of success and reliability led our team to select Starship to orbit Starlab,” Dylan Taylor, chairman and CEO of Voyager Space, said in a statement. “SpaceX is the unmatched leader for high-cadence launches and we are proud Starlab will be launched to orbit in a single flight by Starship.”

Fitting in a big fairing

Starlab will have a diameter of about 26 feet (8 meters). It is perhaps not a coincidence that Starship’s payload bay can accommodate vehicles up to 26 feet across in its capacious fairing. However, in an interview, Marshall Smith, the chief technology officer of Voyager Space, said the company looked at a couple of launch options.

“We looked at multiple launches to get Starlab into orbit, and eventually gravitated toward single launch options,” he said. “It saves a lot of the cost of development. It saves a lot of the cost of integration. We can get it all built and checked out on the ground, and tested and launch it with payloads and other systems. One of the many lessons we learned from the International Space Station is that building and integrating in space is very expensive.”

With a single launch on a Starship, the Starlab module should be ready for human habitation almost immediately, Smith said.

It's hard to believe the interior of Starlab will ever be this clean in space.

Enlarge / It’s hard to believe the interior of Starlab will ever be this clean in space.

Starlab LLC

Starlab is one of several privately developed space stations vying to become a commercial replacement for the International Space Station, which NASA is likely to retire in 2030. Among the other contenders are Axiom Space, Blue Origin, and Vast Space. SpaceX may also configure a human-rated version of Starship as a temporary space station.

NASA has provided seed funding to some of these companies, including Voyager Space, to begin designing and developing their stations. NASA is expected to hold a second round of competition next year, when it will select one or more companies to proceed with building and testing their stations.

Finding customers

Each company is developing a space station that will serve both government customers—NASA wants to continue flying at least a handful of astronauts in low-Earth orbit for research purposes—as well as private customers. The challenge for Starlab and other commercial stations is developing a customer base beyond NASA to support the expense of flying and operating stations.

The challenge is a huge one: NASA spent more than $100 billion constructing the International Space Station and has a $3 billion annual budget for operations and transportation of people and supplies to the station. The agency is likely to fund commercial space stations at a level of about $1 billion a year, so these companies must build their facilities relatively quickly at low cost and then find a diverse base of customers to offset expenses.

Starlab may have an advantage in this regard with its co-ownership by Airbus. One of the big questions surrounding the end of the International Space Station is what happens to the European astronauts who fly there now. The European Space Agency will likely be reticent about funding missions to private space stations owned and operated by US companies. The involvement by Airbus, therefore, makes Starlab attractive to European nations as a destination.

Starlab—with half the volume of the ISS—will fit inside Starship’s payload bay Read More »

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Clownfish “count” white stripes to determine if an invader is friend or foe

animal cognition, animals, Biology, clownfish, numerosity, Science / /

Counting Nemo —

They attacked similar fish with three stripes more often than those with one or two stripes.

–

Clown anemonefish (Amphiprion ocellaris) photographed in the wild.

Enlarge / Clown anemonefish (Amphiprion ocellaris) seem to recognize different species of clownfish by counting white stripes.

Kina Hayashi

Many people tend to think of clownfish, with their distinctive white bars against an orange, red, or black background, as a friendly sort of fish, perhaps influenced to some extent by the popular Pixar film Finding Nemo. But clownfish can be quite territorial when it comes to defending their host anemone from intrusion by others, particularly those from their own species. A new paper published in the Journal of Experimental Biology describes how clownfish determine if a fish approaching their home is friend or foe by “counting” the number of white bars or stripes on their bodies.

As previously reported, mathematical ability is often considered uniquely human, but in fact, scientists have found that many animal species—including lions, chimpanzees, birds, bees, ants, and fish—seem to possess at least a rudimentary counting ability or number sense. Crows can understand the concept of zero. So can bees, which can also add and subtract, as can both stingrays and cichlids—at least for a small number of objects (in the range of one to five). Some ants count their steps.

This so-called “numerosity” simply refers to the number of things in a set, according to cognitive psychologist Brian Butterworth, an emeritus professor at University College London and author of Can Fish Count? What Animals Reveal About Our Uniquely Mathematical Minds. It has nothing to do with reasoning or logical mathematical intelligence. This is information that will be in the environment, and counting animals must have some mechanism for extracting this numerical information from the environment. But it nonetheless makes for a fascinating field of study.

In 2022, Kina Hayashi of the Okinawa Institute of Science and Technology (OIST) and several colleagues found that clownfish display more aggressive behavior (e.g., chasing or biting) toward fish (or fish toys) with vertical bar patterns compared with fish with horizontal stripe patterns and that this aggressive behavior lasted longer when directed at fish with vertical bars versus horizontal bars. This behavior appears to influence the position of fish species between host anemones and coral reefs: No fish with vertical bars sought shelter in host anemones, while several species with vertical bars were found in the surrounding coral reefs. But it wasn’t clear how the fish recognized the color patterns or what basic rules controlled this signaling. The study results suggested that it wasn’t based on the mere presence of white bars or how much white color was present on a given fish’s body.

The plastic models used to measure the clown anemonefish’s aggressive behavior.

Enlarge / The plastic models used to measure the clown anemonefish’s aggressive behavior.

This new study builds on that earlier work. This time around, Kayashi and co-authors raised a school of young common clownfish (A. ocellaris) from eggs to ensure that the fish had never set eyes on other species of anemonefish. At six months old, the fish were introduced to several other clownfish species, including Clarke’s anemonefish (A. clarkii), orange skunk clownfish (A. sandaracinos), and saddleback clownfish (A. polymnus).

The researchers placed different species of clownfish, with different numbers of white bars, in small cases inside a tank with a clownfish colony and filmed their reaction. Because they were in a controlled tank environment, there was no chasing or biting. Rather, aggressive behavior was defined as staring aggressively at the other fish and circling the case in which the other fish were held.

They followed up with a second set of experiments in which they presented a colony of clownfish with different plastic models painted with accurate clownfish coloration, with differing numbers of white stripes. The researchers also filmed and measured the degree of aggressive behavior directed at the different plastic models.

Clownfish showing aggression toward another fish with similar stripes. Credit: Kina Hayashi

The results: “The frequency and duration of aggressive behaviors in clown anemonefish was highest toward fish with three bars like themselves,” said Hayashi, “while they were lower with fish with one or two bars, and lowest toward those without vertical bars, which suggests that they are able to count the number of bars in order to recognize the species of the intruder.”

Hayashi et al. cautioned that one limitation of their study is that all the fish used in the experiments were hatched and raised in an environment where they had only encountered other fish of their own species. So, they could not conclusively determine whether the observed behavior was innate or learned. Other species of clownfish also use the same anemone species as hosts, so aggressive behavior toward those species might be more frequent in the wild than observed in the laboratory tank environment.

Journal of Experimental Biology, 2024. DOI: 10.1242/jeb.246357  (About DOIs).

Clownfish “count” white stripes to determine if an invader is friend or foe Read More »

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Biogen dumps dubious Alzheimer’s drug after profit-killing FDA scandal

aducanumab, Aduhelm, Alzheimer's, Biogen, clinical trial, fda, health, Science / /
Multistory glass office building.

Enlarge / The exterior of the headquarters of biotechnology company Biogen in Cambridge, Massachusetts.

Biotechnology company Biogen is abandoning Aduhelm, its questionable Alzheimer’s drug that has floundered on the market since its scandal-plagued regulatory approval in 2021 and brow-raising pricing.

On Wednesday, the company announced it had terminated its license for Aduhelm (aducanumab) and will stop all development and commercialization activities. The rights to Aduhelm will revert back to the Neurimmune, the Swiss biopharmaceutical company that discovered it.

Biogen will also end the Phase 4 clinical trial, ENVISION, that was required by the Food and Drug Administration to prove Biogen’s claims that Aduhelm is effective at slowing progression of Alzheimer’s in its early stages—something two Phase 3 trials failed to do with certainty.

In the announcement, Biogen noted it took a financial hit of $60 million in the fourth quarter of 2023 to close out its work on Aduhelm, which the company at one point reportedly estimated would bring in as much as $18 billion in revenue per year.

The saga

But the data never appeared to support such lofty aspirations. The drug is intended to work against the clumps of misfolded beta-amyloid protein that accumulate in the brains of people with Alzheimer’s. Though a small, early clinical trial showed the drug could reduce plaques in the brains of people with Alzheimer’s, it initially failed two identically designed Phase 3 trials. The trials, which collectively enrolled nearly 3,300 patients, intended to evaluate if the drug could slow the progression of Alzheimer’s in its early stages.

In March 2019, the company announced that it was ending both trials after a futility analysis indicated that the drug wasn’t working. But later that year, Biogen stunningly reversed course, saying that additional data had rolled in from the trials after the March announcement. A new analysis of the data from one of the two trials indicated that a subset of patients given the highest dose showed a small benefit on cognitive tests—though the patients in the other trial still saw no benefit. The data also found that 40 percent of patients given the high dose developed brain swelling.

Biogen boldly submitted its data to the FDA for approval. In November 2020, a panel of independent advisors for the FDA voted resoundingly against Aduhelm’s approval. Ten of 11 committee members voted against the drug while the remaining member voted “uncertain.” After voting no, one member commented on the “incongruity” of Biogen’s presentation of the drug and the actual data. “It just feels to me like the audio and the video on the TV are out of sync, and there are literally a dozen red threads that suggests concerns about the consistency of evidence—a dozen,” the member said. The FDA, too, in its own statistical analysis of the data, concluded that “there is no compelling substantial evidence of treatment effect or disease slowing.”

Biogen dumps dubious Alzheimer’s drug after profit-killing FDA scandal Read More »

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Should you flush with toilet lid up or down? Study says it doesn’t matter

bacteria, Biology, cross contamination, epidemiology, fluid dynamics, hygiene, sanitation, Science, toilet plumes, toilets, viral aerosols / /
Whether the toilet lid is up or down doesn't make much difference in the spread of airborne bacterial and viral particles.

Enlarge / Whether the toilet lid is up or down doesn’t make much difference in the spread of airborne bacterial and viral particles.

File this one under “Studies We Wish Had Let Us Remain Ignorant.” Scientists at the University of Arizona decided to investigate whether closing the toilet lid before flushing reduces cross-contamination of bathroom surfaces by airborne bacterial and viral particles via “toilet plumes.” The bad news is that putting a lid on it doesn’t result in any substantial reduction in contamination, according to their recent paper published in the American Journal of Infection Control. The good news: Adding a disinfectant to the toilet bowl before flushing and using disinfectant dispensers in the tank significantly reduce cross-contamination.

Regarding toilet plumes, we’re not just talking about large water droplets that splatter when a toilet is flushed. Even smaller droplets can form and be spread into the surrounding air, potentially carrying bacteria like E. coli or a virus (e.g., norovirus) if an infected person has previously used said toilet. Pathogens can linger in the bowl even after repeated flushes, just waiting for their chance to launch into the air and spread disease. That’s because larger droplets, in particular, can settle on surfaces before they dry, while smaller ones travel further on natural air currents.

The first experiments examining whether toilet plumes contained contaminated particles were done in the 1950s, and the notion that disease could be spread this way was popularized in a 1975 study. In 2022, physicists and engineers at the University of Colorado, Boulder, managed to visualize toilet plumes of tiny airborne particles ejected from toilets during a flush using a combination of green lasers and cameras. It made for some pretty vivid video footage:

Colorado researchers managed to visualize toilet plumes in 2022 using green lasers and strategically placed cameras.

“If it’s something you can’t see, it’s easy to represent it doesn’t exist,” study co-author John Grimaldi said at the time. They found that the ejected airborne particles could travel up to 6.6 feet per second, reaching heights of 4.9 feet above the toilet within 8 seconds. And if those particles were smaller (less than 5 microns), they could hang around in that air for over a minute.

More relevant to this latest paper, it’s been suggested that closing the lid before flushing could substantially reduce the airborne spread of contaminants. For example, in 2019, researchers at University College Cork deployed bioaerosol sensors in a shared lavatory for a week to monitor the number and size of contaminant particles. They concluded that flushing with the toilet lid down reduced airborne droplets between 30 and 60 percent. But this scenario also increased the diameter of the droplets and bacteria concentration. Leaving the lid down also means the airborne microdroplets are still detectable 16 minutes after flushing, 11 minutes longer than if one flushed with the lid up.

Should you flush with toilet lid up or down? Study says it doesn’t matter Read More »