Musings: 2025 (current posts)

A ring for Earth?

February 19, 2025

The rings of Saturn are prominent, almost a defining feature of that planet. As we got better observations, we found rings around other bodies. Even little Chariklo seems to have rings; see background post below. How about us? We don't see Earth rings, even with telescopes. But a new article suggests that Earth might have had a ring (or ring system) 460 million years ago -- one big enough to have major consequences for Earth climate.

What leads to the suggestion that Earth had a ring? There is a cluster of meteor craters from about the same time in about the same place. The authors suggest that one could account for this if an asteroid approached the Earth and broke up, forming a debris ring. Over the next few (million) years, the debris settled to Earth, giving us a set of craters in a relatively small region of time and space. Further, there was an ice age at about the same time; the authors suggest that the dense debris ring acted as a sunscreen, leading to the ice age.

Direct evidence for a ring? Not really. It's a hypothesis to explain some Earth features that we do see. It is supported by computer modeling, at this point.

* News stories:
- Earth Might Have Had a Ring System Like Saturn Millions of Years Ago -- The ring might have acted like a giant sunshade, causing a cooling effect that might have unleashed an ice age. (Tibi Puiu, ZME Science, December 31, 2024.)
- Hidden craters reveal Earth may once have had a ring - like Saturn. (Andrew Tomkins, The Conversation, September 15, 2024.) From the lead author of the article.
* The article (open access): Evidence suggesting that earth had a ring in the Ordovician. (Andrew G Tomkins et al, Earth and Planetary Science Letters 646:118991, November 15, 2024.)

Background post about rings: Rings for Chariklo (May 9, 2014). Links to more.

A novel and simple way to make ammonia?

A new article reports that it works rather well -- and that includes a small test of a prototype device in the field. Developing a catalyst was the heart of the work. The scientists end up using a mixture of iron oxide and an acidic polymer called Naflon. The process uses chemicals from the air, and produces a dilute solution of ammonia, suitable for direct application to crops. No external energy is needed, and there is no greenhouse gas emission.

That is all in contrast to the well-established Haber-Bosch process for making ammonia. The new process offers the possibility of inexpensive and sustainable ammonia, produced on-site as needed. The process works, but does need further development, to scale it up to become practical for large fields.

A mutation that may lead to "bird flu" virus being better able to infect humans

February 5, 2025

Scientists have introduced a single specific mutation into the HA (hemagglutinin) gene from a new isolate of H5N1 bird flu virus, and shown that it makes the viral HA protein bind better to the human flu virus receptor. The specific mutation had previously been associated with improved binding to the human receptor; the current work extends that to the background of an H5N1 isolate from cattle. This is lab work, using purified proteins. It is not clear how the finding would carry over to the complexity of the real world. But it does illustrate how the virus might change its host specificity, and in some general sense is a concern.

* News stories:
- Scripps Research scientists identify mutation that could facilitate H5N1 "bird flu" virus infection and potential transmission in humans -- New findings underscore the importance of ongoing surveillance for H5N1 mutations that pose risks to public health. (Scripps Research Institute, December 5, 2024.) From the lead institution. Useful overview.
- Bovine H5N1 influenza shows potential for human adaptation through key mutations. (Vijay Kumar Malesu, News-Medical.net, December 9, 2024.) Includes more detail about the work.
- Expert reaction to study of single mutation in bovine influenza H5N1 hemagglutinin and specificity to human receptors. (Science Media Centre, December 5, 2024.) Multiple views from flu exports.
* The article: A single mutation in bovine influenza H5N1 hemagglutinin switches specificity to human receptors. (Ting-Hui Lin et al, Science 386:1128, December 6, 2024.)

Posts on flu are listed on the supplementary page Musings: Influenza.

January 2025

On reducing meat consumption: The squirrels dissent

What do squirrels eat? Acorns and such. In fact, it has long been known that squirrels do consume some meat, though the role of meat in their diet is unclear but generally minimal. For example, do they actually attack animals, or merely scavenge what they may find? A new article is part of a multi-year study of squirrels in a park area. One summer, the squirrels were seen to regularly hunt and attack voles (small rodents) and eat them. The scientists were surprised, but they have many videos. The vole-eating was seen at a peak in the vole population. The observations raise questions about what controls the behavior, but at least it shows more flexibility in squirrel diet than previously recognized.

On reducing meat consumption: Evaluation of alternatives

January 28, 2025

There are various reasons to promote reducing meat consumption. That leads to, what are the alternatives and what are their merits? Musings has discussed some aspects of cultured meat (growing cells from meat animals in culture). This is an interesting development, but it has significant challenges. Other alternatives include a range of plant products, with varying degrees of processing. A new article provides an extensive analysis of the issues. The author comes out with a clear winner. But a big caution... This is still a work in progress. For now, understanding the questions is as important as anything.

* News story: The best and worst meat replacements for your health, your wallet and the planet - new research. (Marco Springmann, The Conversation, December 3, 2024.) From the author of the article. Useful overview.
* The article, which is open access: A multicriteria analysis of meat and milk alternatives from nutritional, health, environmental, and cost perspectives. (Marco Springmann, PNAS 121:e2319010121, December 2, 2024.)

Among Musings posts on the topic... Tuning the protein and fat content of cultured meat (February 2, 2021).

Added January 30, 2025. Also see the next post, immediately above: On reducing meat consumption: The squirrels dissent (January 30, 2025).

Why are twin births uncommon in humans?

Twin births occur about 2% of the time in humans. In fact, they are uncommon in most primates -- but not all. A recent article explores the history behind that. The article analyzes data for litter size in nearly a thousand types of mammals, including 155 primate species. Litter size is mapped onto a phylogenetic tree. The results suggest that having twins was the ancestral state of primates. That trait has since been lost in most primate branches. The article includes extensive discussion of the merits of one litter size or another; that discussion may make the article worth reading, without getting too bogged down in the data.

Recent craters in Siberia due to methane release from hydrates in the permafrost

January 15, 2025

Methane hydrate is a complex of methane and water. It is an ice-like solid at conditions where methane itself would be a gas. There is a lot of methane underground in cold regions, where the methane hydrate is effectively part of the permafrost. There is a concern that warming of the permafrost could lead to release of the methane, which is a potent greenhouse gas and also flammable.

Concern that it might happen is being replaced by study of how it happened.

A crater on the Yamal Peninsula in Siberia.

The crater core is about 30 meters across.

This crater was first noticed in 2014. There are now about 20 such craters in Siberia, all new since about that time and many in the same region. From the time of the initial observations, it seemed likely that the craters were due to methane release, probably stimulated by climate change, but the details have been debated.

This is trimmed and reduced from the top figure on the Wikipedia page listed below; credit is given there to the scientists who provided it. There are other views of such craters in Figure 1 of the article and in the news stories.

So, what happens? The simplest model might be that the hydrate warms, releasing methane, which escapes. That model does not necessarily lead to a crater. A more complex model might postulate that the methane builds up inside a closed region, until the pressure is high enough to break it open -- explosively. A new article offers support for an even more complex process. It involves the migration and mixing of water layers of different salinities (salt content) and temperatures. That flow of differing liquid phases promotes heat transfer, and puts physical stress on the subsurface structures. The article is based largely on mathematical modeling, with some lab work that supports the idea. The model depends on the geological details of the area. Thus it helps to explain the limited geographical distribution as well as the nature of the craters.

Of course, it is reasonable that there are various processes that can lead to methane release. The current work is just an example of one way it might happen. The work serves to remind us of the likely importance of methane hydrates.

* News stories:
- Massive exploding methane craters are tearing Siberia apart and scientists finally know why -- Scientists uncover the mechanics behind Siberia's explosive craters as warming drives methane release. (Tibi Puiu, ZME Science, November 11, 2024.)
- New explanation for Siberia's permafrost craters -- The region's unique geology, not only warming and permafrost thaw, caused the methane explosions. (AGU, September 26, 2024.)
* Wikipedia page referred to above as source for the figure: Gas emission crater. (Wikipedia.) Useful overview. The current article is noted there. It is now reference #11; search the page for the lead author (Morgado) if needed.
* The article, which is open access: Osmosis Drives Explosions and Methane Release in Siberian Permafrost. (Ana M O Morgado et al, Geophysical Research Letters 51:e2024GL108987, September 26, 2024.)

Among posts about methane and its hydrate:
* Methane hydrate: a model for pingo eruption (August 4, 2017).
* Climate change: Should we focus on methane? (March 24, 2012).
* Ice on fire (August 28, 2009).

Photosynthetic hamster cells

Scientists have added chloroplasts to hamster cells growing in lab culture. The chloroplasts functioned for at least two days; there is at least a hint that they contributed fuel to the cell economy. This appears to be the first example of free chloroplasts (that is, not within their own host cell) functioning in animal cells. What will it take to get good chloroplast function over an extended period? We'll see.

The authors suggest an interesting lab use for such photosynthetic animal cells. In tissue culture, they could be a useful source of oxygen for the cells.

Happy 45²

January 6, 2025

A once in a lifetime event for most of us. But it is extra special for anyone who was around in 1936.

This post is listed on my page Internet resources: Miscellaneous in the section Mathematics; statistics.

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