How Bats Prevent Doppler Acoustic Interference

September 7, 2026 by Maya Posch 13 Comments

https://commons.wikimedia.org/wiki/File:Bat(20070605).jpg — Lesser horseshoe bat. (Credit: Lylambda, Wikimedia)

As great as echolocation is, things can get rather messy once it’s not just you chirping away, but also hundreds of your buddies in roughly the same area. This is the scenario that the typical colonies of bats have to deal with. In a recent study by [Haruhito Matsumoto] et al. in Journal of Comparative Physiology they investigated how colonies of greater Japanese horseshoe bats deal with this issue.

Echolocation in animals can use a variety of methods, including frequency modulation (FM, varying the pitch) or constant frequency (CF), with both having their uses during hunting as well as obstacle avoidance. One big advantage of CF is that it can be used for Doppler shift, giving very precise information about location and velocity of objects in the environment, but if used in a busy colony the acoustic interference would effectively render them blind.

What researchers have found is that the CF component frequencies differ per bat colonies, with the mixing of wild-caught and resident horseshoe bats in this experiment showing them adjusting the dominant second harmonic (CF2) to match, with bats using a lower frequency CF2 adjusting it upwards. In this way frequency convergence is used as a strategy to avoid acoustic interference using a so-called ‘silent spectral window’.

As this spectral window for effective Doppler tracking is found above the CF2 frequency, it therefore makes sense that the bats at a lower CF2 harmonic would adjust their CF upwards to match that of their neighbors. Although more research is required to fully confirm these findings, it sheds some more light on the use of echolocation by these amazing flying mammals.

Kelvin–Helmholtz Instabilities Found To Drive Plasma Mixing On The Sun

September 7, 2026 by Maya Posch 3 Comments

As easy as the Sun is to observe, it’s simultaneously very hard to study due to how extreme the conditions are, even on the surface of a rather unassuming star. One of these study topics is the interaction between the Sun’s plasma and magnetic field, as this drives much of the dynamism of the Sun’s surface layer (i.e., the photosphere). Recent observations by the 4-meter solar telescope in Hawaii have now led to interesting new findings, as detailed in a paper in Nature by [David Kuridze] et al.

Despite popular portrayal, this photosphere is not a boiling liquid, but rather pockets of plasma at various temperatures. The plasma moves within the magnetic field and convective movements that create the ‘boiling’ pattern, which gives the illusion of a boiling liquid surface.

Within this photosphere, [Kuridze] et al. were able to observe Kelvin-Helmholtz instabilities, which are fluid instabilities caused by velocity shearing in either a continuous fluid or due to a velocity difference between two fluids. This is also observed in clouds in Earth’s atmosphere, where they cause the billowing effect, somewhat similar to watching a boiling liquid.

In a MURaM simulation (see heading image), these findings were confirmed, showing how these instabilities drive the transport of plasma in the Sun’s photosphere.

Comparing PETG And PCTG Filaments

September 7, 2026 by Maya Posch 5 Comments

The average 3D printer owner knows a few types of filaments – PLA, ABS, somewhere in the middle, PETG. PCTG is another option that can be confusingly similar to PETG. Recently, [Igor Gaspar] of [My Tech Fun] took a poke at both types. He obtained both PETG and PCTG transparent filaments from the same manufacturer to compare them directly.

As we recently detailed in an article on PET polyesters, PETG is glycol-modified PET, meaning that some of the glycol monomers are replaced by CHDM monomers to create a more flexible and robust material. PCTG is very similar to PETG, except that more than half of the glycol monomers are replaced rather than less than half. This creates a PET-type material that has distinct physical properties from PETG, which might be desirable for some applications.

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How Charged Water Drops Induce Corrosion

September 6, 2026 by Maya Posch 11 Comments

Generally, we do not look at the gentle patter of raindrops on a surface with much concern, but according to a study by [Zhongyuan Ni] et al. in Nature, we should probably regard these droplets with a little scrutiny for their corrosion potential. What they found is that these drops can gather a significant electric potential as they gently slide down a surface, with over 1 kV measured. By first having droplets charge up on an insulating surface before hitting a target metal surface, they were able to induce significant corrosion.

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Saturn’s South Pole Is Apparently Decagon-Shaped

September 6, 2026 by Maya Posch 15 Comments

Saturn's north pole captured by Cassini in 2013. (Credit: NASA/JPL-Caltech/SSI/CICLOPS/Kevin M. Gill) — Saturn’s north pole captured by *Cassini* in 2013. (Credit: NASA/JPL-Caltech/SSI/CICLOPS/Kevin M. Gill)

Although some would argue that the hexagon is the bestagon, astronomers have discovered that Saturn appears to favor the ten-sided decagon on its south pole. This comes as its south pole has recently been confirmed to show a pattern that’s oddly ten-sided, per a recent research article by [Agustín Sánchez-Lavega] et al. in Science Advances.

Because Saturn is a gas giant, this naturally isn’t some gigantic planet-sized rock formation, but rather an interesting wave phenomenon in this massive gas bubble. The hexagon shape on its north pole had been known about for a while already, so it is perhaps not too surprising to find something similar on its south pole.

These shapes are generally the result of standing waves within a polar vortex, through the interaction of waves in Saturn’s atmosphere. For the north pole hexagon, the formation is driven by an intense eastward jet, but no similar wave had been reported for the planet’s south pole.

While in this paper a decagon shape is identified based on multiple observations, they postulate that it’s due to a meandering wave in the area rather than a jet as at the other pole. This clearly doesn’t make this wave pattern as obvious as the one at the north pole, but it provides another fascinating insight into fluid dynamics scaled up to a planetary gas giant.

Can AI Now Design PCBs That Just Work?

September 5, 2026 by Maya Posch 63 Comments

With the recent release of its GPT-6 Astra model, OpenAI explicitly pushed the claim that it is capable of designing complete circuit boards in KiCad, starting from a provided schematic and outputting a fully routed PCB that theoretically could be sent off to be manufactured. This of course raises the question whether this is just a nifty party trick that works under strictly controlled conditions like most auto-routing tools, or whether there’s more to it. In a recent [EEBench] blog post, OpenAI’s claims are put to the test.

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Pixel Watch 5 Demonstrates Good Repairability

September 5, 2026 by Maya Posch 18 Comments

Although we often find ourselves drowning in a seemingly unending sea of portable devices that are effectively e-waste once an internal component gives out, it’s good to remind ourselves that there are a few examples out there by large brands that manage to tick all the fancy feature boxes, while still being very much repairable. Case in point the Pixel Watch 5, a smart watch which much like its predecessor gets a 9/10 on [iFixit]’s repairability score.

No heat gun required, just undo the latch on the side of the watch. (Credit: iFixit, YouTube) — No heat gun required, just undo the latch on the side of the watch.

Despite featuring an IP68 rating, opening it is as easy as taking out a few screws to release its latch. This allows the back to swing open, with not a drop of glue in sight, just an O-ring gasket that keeps moisture out and can be reused many times. Digging into the guts, there are color-coded screws that guide one’s hand as the very modular design is taken apart in a matter of minutes.

Being able to simply unlatch the back, and also easily obtain spare parts are two aspects that are a very welcome sight indeed. Although it’s much easier to just glue everything together, something like this latch-and-gasket approach is something that we hope that more manufacturers will copy for these small devices.

It’s potentially also an idea for one’s next DIY smart watch project, as tempting as reaching for that tube of glue may seem.

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