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Tikalon Blog is now in archive mode. Here's a directory of links to easily printed and saved articles. If you're willing to wait a while for the download, a zip file of all the blog articles can be found at the link below. Note, however, that these articles are copyrighted and can't be used to train artificial intelligent agents. Individuals are free to republish single articles on their personal websites.
Microphones convert sound into an electrical signal for subsequent amplification, as in auditorium public address systems; or transmission, as in landline and mobile phones. The most common types of microphones are carbon, used in early telephones, condenser, electret, dynamic, ribbon, crystal and MEMS. All these microphones operate as transducers that convert sound pressure into an electrical signal. This makes them also sensitive to noise caused by air molecules bouncing against their diaphragms. In an effort to solve this thermal noise problem, a team of mechanical engineers has investigated a sound sensing approach that uses viscous air flow rather than sound pressure. Viscous flow is what vibrates spiderwebs in gentle breezes. Air flow passing a thread of a spiderweb drags the thread. They demonstrated sound detection by a simulated spiderweb, an array of thin cantilever beams. The beams were 0.5 micrometer thick silicon nitride placed over a hole in a silicon wafer, and a laser was used to measure the displacement of the microbeams, first in response to thermal noise, and then in response to sound waves from 100 to 1000 Hz. The cantilever velocity matched that of the sound wave, irrespective of the length or width of the beam. The demonstrated cantilever microphone is about 50 dBa less sensitive than the best pressure-based microphones; but, pressure microphones have been perfected over a span of 150 years. As the lead author of the paper comments, "Detecting air flow as a way to sense sound has largely been ignored by researchers, but the principles show that it's worth considering."
"Form follows function" is a maxim that an object's shape and appearance should be defined only by its purpose or function. A quick perusal of any antique shop will show that this maxim is generally ignored. Humans (Homo sapiens) have been called "naked apes," but we and our close species cousins quickly adopted the concept of wearing the fur skins of animals for protection. Our ancestors were likely much more interested in how they would obtain their next meal than how stylish they appeared in hyena fur. As human culture progressed, people desired to distinguish themselves from others; and, what could be an easier way to do that than through dress. This is accomplished by the simple technique of dyeing drab natural fibers, but the simple sewing needle is a technical innovation that's lead to a means of producing more ornate dress. A recent open access article in Science Advances investigates the use of delicate eyed needles in the Paleolithic as the means for producing refined, ornamented dress. One argument for clothing's becoming a means of decoration is that traditional body decoration, such as body painting with ochre, weren't effective in cold climates, since clothing was needed all the time for survival. Homo sapiens arrived in Europe at around 45,000 BC, and the earliest known eyed needles appeared in Siberia around 40,000 BC, in the Caucasus around 38,000 BC, in West Asia around 30,000 BC, and in Europe around 26,000 BC. Clothing the human body regardless of climate is a social practice that's persisted to this day. The eyed needle combined the processes of hole puncture and threading to allow finer and more efficient sewing.
Deep thought is what distinguishes humans from other animals. The brain is the medium for thought; so, there's the idea that brain size is important, with larger brains allowing more profound thought. Larger brains in hominids appears to have an evolutionary advantage, but the largest animals do not have proportionally larger brains. For the last century, conventional wisdom was that body mass in mammals could be described by a power law. A British research team has created a large dataset of brain and body sizes from about 1,500 species to determine the trend in brain size evolution, finding that the trend is brain size and body mass is not log-linear, but rather log-curvilinear, plateauing at high body mass. The research team found that all groups of mammals demonstrated rapid bursts of evolutionary change, not only towards larger brain size, but smaller as well. Bats very rapidly reduced their brain size, suggesting that flight may have imposed an evolutionary constraint. Homo sapiens has evolved more than twenty times faster than all other mammalian species, resulting in the massive brain size of modern man. Primates, rodents, and carnivores show a tendency for increase in relative brain size as they evolved. It appears that there is something preventing brains from getting too big, perhaps because big brains beyond a certain size are simply too costly to maintain. This upper limit of brain size applies to animals with very different biology.
In today's bigger is better world, you don't order a large coffee, you order a 20 fluid ounce Venti coffee. From 1987 through 2004, McDonald's restaurants had a supersize option for larger than large portions of its French fries and soft drinks. The prefix, super, has been used to describe supercooling, the unexpected cooling without a phase change when liquids can be cooled below their freezing points without solidifying. Water has many unusual properties, and these are most probably the result of water molecule being small, and the force holding these molecules together in a liquid or solid arising from hydrogen bonding. Supercooled water is a hazard to aviation, since supercooled water droplets often existing in cumulus and stratus clouds will instantly freeze on aircraft surfaces and plug the Pitot tubes that indicate airspeed. It's easy to create supercooled water in the laboratory. You just need to purify the water to remove contained minerals. The mineral crystals act as nucleation sites. Bacteria and fungi are efficient natural ice nucleators because of the way their proteins act as ice templates. The best such natural ice nucleators the Pseudomonas syringae bacterium, which is used to make artificial snow. Larger protein molecules are usually better at ice nucleation, but small fungal proteins are good at ice nucleation when they clump into larger aggregates. Scientists at the University of Utah have developed a model for prediction of the nucleation temperature of ice on a given surface. Model parameters include the shapes of surface defects, and appropriately sized and shaped surface bumps and depressions can squeeze water molecules into configurations that make it easier or harder for ice to form.
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February 26, 2024 As dawn broke, Laura, Moises and I slowly cruised along a quiet watercourse. The dawn chorus was active and included species like Ferruginous Pygmy-Owl, Zimmer's Woodcreeper and Black-tailed Antbird, but I stayed focused on the treeline, hoping that a curassow-shaped bird would appear. The dawn chorus quieted as the sun rose above the horizon. Early morning is the best time to find the curassow, and we were running out of time. Domain of the Wattled Curassow - Muyuna Lodge, Loreto, Peru And there it was! It was the bright red bill that first caught my attention and 0.05 seconds later, my brain registered that I was staring at a female Wattled Curassow. Wattled Curassow - Muyuna Lodge, Loreto, Peru But it was better than I had imagined - the female was accompanied by a tiny chick! For a few magical minutes we watched the duo in their element. Wattled Curassow chick - Muyuna Lodge, Loreto, Peru Wattled Curassow chick - Muyuna Lodge, Loreto, Peru Wattled Curassows are closely associated with these rivers in the western Amazon basin and that has led to their downfall. The rivers are the highways, and curassows have a lot of meat. But in a few areas like here, hunting of the curassows does not occur and encounters with this secretive species are possible. The curassows like feeding on the fruits of mahogany trees that line the watercourses, and that is likely what this female was on the hunt for. Wattled Currasow - Muyuna Lodge, Loreto, Peru We were on cloud nine after such an epic start to the day! I was pleased that I even managed some mostly in-focus photos with my broken lens. For the next few hours we cruised around by boat, checking out different waterways in search of some of our target birds. We were successful with Black-tailed Antbird and Short-tailed Parrot. Black-tailed Antbird - Muyuna Lodge, Loreto, Peru Short-tailed Parrot - Muyuna Lodge, Loreto, Peru It was a very birdy morning and we cleared the hundred species mark before returning to the lodge for breakfast. Bluish-fronted Jacamar - Muyuna Lodge, Loreto, Peru Black-tailed Tityra - Muyuna Lodge, Loreto, Peru Proboscis Bat (Rhynchonycteris nasa) - Muyuna Lodge, Loreto, Peru After breakfast, we searched by boat for some of the few remaining target birds I had in mind such as Purple-throated Cotinga, Gray-eyed Greenlet and Wing-barred Seedeater, but were unsuccessful. Unidentified katydid - Muyuna Lodge, Loreto, Peru We were also on the lookout for Dusky-billed Parrotlets, a potential lifer for Laura and a new photographed bird for me. Moises claimed sightings on a few occasions, but each time my photos revealed that they were the more expected Riparian Parrotlets. Band-tailed Antbird - Muyuna Lodge, Loreto, Peru At one point during the afternoon we entered an area of higher ground where there was a small walking trail. After spending most of the day in a boat it felt great to feel the earth beneath our boots, even though this meant that we were accompanied by a swarm of mosquitoes. Amazonian Trogon - Muyuna Lodge, Loreto, Peru Methona confusa - Muyuna Lodge, Loreto, Peru We found several groups of Eastern Pygmy Marmosets, one of the smallest species of monkey! Eastern Pygmy Marmoset (Cebuella niveiventris) - Muyuna Lodge, Loreto, Peru Eastern Pygmy Marmoset (Cebuella niveiventris) - Muyuna Lodge, Loreto, Peru Our guide, Moises had a stake-out for Nancy Ma's Night-Monkey (Aotus nancymai) that was visible from the main watercourse. Nancy Ma's Night-Monkey (Aotus nancymai) - Muyuna Lodge, Loreto, Peru During the mid-afternoon, Moises took us down a channel choked with vegetation to look for some herps. We kept a close eye on the vegetation until Laura spotted the first snake, as she is known to do! Giant Parrot Snake (Leptophis ahaetulla nigromarginatus) - Muyuna Lodge, Loreto, Peru While we have seen this widespread species before, this was a new subspecies for us. The extensive black markings between the scales are quite distinctive. Giant Parrot Snake (Leptophis ahaetulla nigromarginatus) - Muyuna Lodge, Loreto, Peru Even better than the parrot snake was this next species: a Northern Caiman Lizard (Dracaena guianensis)! I have wanted to see this huge species of lizard for many years but had never gotten lucky. As the name suggests, particularly large individuals somewhat resemble caimans, and they share similar aquatic habitats. Caiman lizards feed on snails, fish, amphibians and other creatures that they find underwater. Northern Caiman Lizard (Dracaena guianensis) - Muyuna Lodge, Loreto, Peru Northern Caiman Lizard (Dracaena guianensis) - Muyuna Lodge, Loreto, Peru As the sun set, we found ourselves slowly paddling in a different wetland after another unsuccessful Purple-throated Cotinga search. We enjoyed watching a pair of Yellow-chinned Spinetails. This species is widespread in South America but is fairly localized in Peru. Yellow-chinned Spinetail - Muyuna Lodge, Loreto, Peru You would be hard-pressed to find an activity that Laura likes more than a night-hike in the tropics, and tonight's walk was a good one. We only stayed out for a short while but came away with some nice sightings, including several snakes! Smoky Jungle Frog (Leptodactylus pentadactylus) - Muyuna Lodge, Loreto, Peru Ancylometes sp. - Muyuna Lodge, Loreto, Peru Unidentified net-casting spider (family Deinopidae) - Muyuna Lodge, Loreto, Peru Crowned False Boa (Pseudoboa coronata) - Muyuna Lodge, Loreto, Peru Pierella hortona - Muyuna Lodge, Loreto, Peru Leptodactylus sp. - Muyuna Lodge, Loreto, Peru Sais rosalia - Muyuna Lodge, Loreto, Peru Garden Tree Boa (Corallus hortulana) - Muyuna Lodge, Loreto, Peru I think my favourite sighting of the walk was this Slender Opossum (Marmosops sp.). It was extremely confiding and didn't mind my close approach for photos. Slender Opossum (Marmoseps sp.) - Muyuna Lodge, Loreto, Peru Though they may resemble a rodent to some (Moises confidently identified it as an "Amazonian Mouse", whatever that is), these are actually a tiny genus of neotropical opossums, meaning that they are a marsupial. Slender opossums typically live in the viny, dense understory where they search for insects, arachnids, flowers and fruit. Slender Opossum (Marmoseps sp.) - Muyuna Lodge, Loreto, Peru My final post from Peru will include our last couple of days at Muyuna Lodge.
When pigeons outnumber pigeonholes, some birds must double up. This obvious statement — and its inverse — have deep connections to many areas of math and computer science. The post How a Problem About Pigeons Powers Complexity Theory first appeared on Quanta Magazine
Yes – it is well-documented that in many industries the design of products incorporates a plan for when the product will need to be replaced. A blatant example was in 1924 when an international meeting of lightbulb manufacturers decided to limit the lifespan of lightbulbs to 1,000 hours, so that consumers would have to constantly […] The post Is Planned Obsolescence Real first appeared on NeuroLogica Blog.
The crazy story of a few days that changed Korea forever
Despite the hype, it’s been surprisingly challenging to find quantum algorithms that outperform classical ones. In this episode, Ewin Tang discusses her pioneering work in “dequantizing” quantum algorithms — and what it means for the future of quantum computing. The post What Is the True Promise of Quantum Computing? first appeared on Quanta Magazine
