An anonymous reader quotes a report from MIT Technology Review: Physicists have created a new type of radar that could help improve underground imaging, using a cloud of atoms in a glass cell to detect reflected radio waves. The radar is a type of quantum sensor, an emerging technology that uses the quantum-mechanical properties of objects as measurement devices. It's still a prototype, but its intended use is to image buried objects in situations such as constructing underground utilities, drilling wells for natural gas, and excavating archaeological sites. [...] The glass cell that serves as the radar's quantum component is full of cesium atoms kept at room temperature. The researchers use lasers to get each individual cesium atom to swell to nearly the size of a bacterium, about 10,000 times bigger than the usual size. Atoms in this bloated condition are called Rydberg atoms. When incoming radio waves hit Rydberg atoms, they disturb the distribution of electrons around their nuclei. Researchers can detect the disturbance by shining lasers on the atoms, causing them to emit light; when the atoms are interacting with a radio wave, the color of their emitted light changes. Monitoring the color of this light thus makes it possible to use the atoms as a radio receiver. Rydberg atoms are sensitive to a wide range of radio frequencies without needing to change the physical setup... This means a single compact radar device could potentially work at the multiple frequency bands required for different applications. [Matthew Simons, a physicist at the National Institute of Standards and Technology (NIST), who was a member of the research team] tested the radar by placing it in a specially designed room with foam spikes on the floor, ceiling, and walls like stalactites and stalagmites. The spikes absorb, rather than reflect, nearly all the radio waves that hit them. This simulates the effect of a large open space, allowing the group to test the radar's imaging capability without unwanted reflections off walls.The researchers placed a radio wave transmitter in the room, along with their Rydberg atom receiver, which was hooked up to an optical table outside the room. They aimed radio waves at a copper plate about the size of a sheet of paper, some pipes, and a steel rod in the room, each placed up to five meters away. The radar allowed them to locate the objects to within 4.7 centimeters. The team posted a paper on the research to the arXiv preprint server in late June.

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Researchers at Kyushu University have developed a solid-oxide fuel cell that operates at just 300C, less than half the usual operating temperature. The team was able to do this by engineering a "ScO6 highway" in the electrolyte, allowing protons to move quickly without losing performance. "The team expects that their new findings will lead to the development of low-cost, low-temperature SOFCs and greatly accelerate the practical application of these devices," said the researchers in a press release. Interesting Engineering reports: "While SOFCs are promising due to their high efficiency and long lifespan, one major drawback is that they require operation at high temperatures of around 700-800C (1292F-1472F)," added the researchers in a press release. Such heat requires costly, specialized heat-resistant materials, making the technology expensive for many applications. A lower operating temperature is expected to reduce these manufacturing costs. The team's success comes from re-engineering the fuel cell's electrolyte, the ceramic layer that transports protons (hydrogen ions) to generate electricity. Previously, scientists faced a trade-off. Adding chemical dopants to an electrolyte increases the number of available protons but also tends to clog the material's crystal lattice, slowing proton movement and reducing performance. The Kyushu team worked to resolve this issue. "We looked for oxide crystals that could host many protons and let them move freely -- a balance that our new study finally struck," stated Yamazaki. They found that by doping two compounds, barium stannate (BaSnO3) and barium titanate (BaTiO3), with high concentrations of scandium (Sc), they could create an efficient structure. Their analysis showed that the scandium atoms form what the researchers call a "ScO6 highway." This structure creates a wide and softly vibrating pathway through the material. "This pathway is both wide and softly vibrating, which prevents the proton-trapping that normally plagues heavily doped oxides," explained Yamazaki. The resulting material achieves a proton conductivity of more than 0.01 S/cm at 300C, a performance level comparable to conventional SOFC electrolytes that run at more than double the temperature. The research has been published in the journal Nature Materials.

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After four weather-related delays, Amazon successfully launched 24 more Kuiper internet satellites aboard a SpaceX Falcon 9, bringing its total to 102. CNBC reports: SpaceX's Starlink is currently the dominant provider of low-earth orbit satellite internet, with a constellation of roughly 8,000 satellites and about 5 million customers worldwide. Amazon is racing to get more of its Kuiper satellites into space to meet a deadline set by the Federal Communications Commission. The FCC requires that Amazon have about 1,600 satellites in orbit by the end of July 2026, with the full 3,236-satellite constellation launched by July 2029. Amazon has booked up to 83 launches, including three rides with SpaceX. While the company is still in the early stages of building out its constellation, Amazon has already inked deals with governments as it hopes to begin commercial service later this year.

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JavaScript is frequently surprising in terms of what functions it does not support. For example, while it has a Math.round function, that only rounds to the nearest integer, not an arbitrary precision. That's no big deal, of course, as if you wanted to round to, say, four decimal places, you could write something like: Math.floor(n * 10000) / 10000.

But in the absence of a built-in function to handle that means that many developers choose to reinvent the wheel. Ryan found this one.

function stripExtraNumbers(num) { //check if the number's already okay //assume a whole number is valid var n2 = num.toString(); if(n2.indexOf(".") == -1) { return num; } //if it has numbers after the decimal point, //limit the number of digits after the decimal point to 4 //we use parseFloat if strings are passed into the method if(typeof num == "string"){ num = parseFloat(num).toFixed(4); } else { num = num.toFixed(4); } //strip any extra zeros return parseFloat(num.toString().replace(/0*$/,"")); }

We start by turning the number into a string and checking for a decimal point. If it doesn't have one, we've already rounded off, return the input. Now, we don't trust our input, so if the input was already a string, we'll parse it into a number. Once we know it's a number, we can call toFixed, which returns a string rounded off to the correct number of decimal points.

This is all very dumb. Just dumb. But it's the last line which gets really dumb.

toFixed returns a padded string, e.g. (10).toFixed(4) returns "10.0000". But this function doesn't want those trailing zeros, so they convert our string num into a string, then use a regex to replace all of the trailing zeros, and then parse it back into a float.

Which, of course, when storing the number as a number, we don't really care about trailing zeros. That's a formatting choice when we output it.

I'm always impressed by a code sample where every single line is wrong. It's like a little treat. In this case, it even gets me a sense of how it evolved from little snippets of misunderstood code. The regex to remove trailing zeros in some other place in this developer's experience led to degenerate cases where they had output like 10., so they also knew they needed to have the check at the top to see if the input had a fractional part. Which the only way they knew to do that was by looking for a . in a string (have fun internationalizing that!). They also clearly don't have a good grasp on types, so it makes sense that they have the extra string check, just to be on the safe side (though it's worth noting that parseFloat is perfectly happy to run on a value that's already a float).

This all could be a one-liner, or maybe two if you really need to verify your types. Yet here we are, with a delightfully wrong way to do everything.

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