Synchronizing Fireflies

(via MAKE magazine)

I was always fascinated by the emergence of patterns. One I like most is the synchronization of hundreds or thousands of fireflies. First they flash randomly but after some time and influencing each other, they flash in sync.

The rule behind this is very simple. All fireflies have nearly the same frequency for their flashing, but their phase is shifted. If a firefly receives a flash of a neighbour firefly, it flashes slightly earlier.

This circuit simulates fireflies with small microcontrollers.

A single Firefly

The board consists of 25 fireflies. Every single firefly is self contained, there is no over-all controller. A single firefly consists of:

• ATtiny13 microcontroller, 1k SRAM, 64 bytes RAM
• Light Dependant Resistor (LDR)
• LED
• 2 resistors

The circuit is the same as for the Programmable LED.

The complete Board

Assembling 25 fireflies on a prototype board is easy. Harder is to get the right distance between all fireflies. It has to be close enough to let one firefly influence another, but not the whole group.

The LEDs I used emit the light mostly straight up. So a kind of reflector is needed. I used a piece of paper which is located 5 mm above the LEDs. For the next version I would take LEDs with a wider light emitting angle and use a kind of diffuser, as proposed by Tod for his Smart LED Prototypes.

Here is a video. It is a bit dark as my camera is not very suitable for this.

Links

• Synchronizing Fireflies on Instructables. That is a more detailed step-by-step instruction with more pictures, sourcecode, etc.
• More on the algorithm can be found here:
  Firefly Synchronization Ad Hoc Networks

Ikea Lamps and DIY Platonic Solids.

Make Magazine shows "[i]n this Instructable, the builder combines a bunch of $5 Ikea "Lampans" into larger spherical, Platonic-y lamps."

See the flickr set for more pictures and my log.

The "Instructable" in question (pdf) "... shows you how to build large spherical lamps out of Ikea lampan lamps ( $4.99 each ). The lamps are based on platonic solids. With this method I have built large spheres up to 32 lamps.
In the PDF below i included three templates: for the six, twelve and 32 lamp versions. These are all generated from a python script in the Maya software. I calculated that the largest sphere that could be build has about 120 lamps and i would love to build that one; but it will be heavy and bright and probably needs some serious thinking on the structural integrity."

New Species Photo Roundup

from Cryptomundo, via Boingboing

During the first couple weeks of March, several new species have been revealed as new discoveries. Here is a survey of their published images and links to more details about the findings.

The green tree skink (Prasinohaema virens) is one of five described species of green-blooded lizards from New Guinea. Credit: Chris Austin, Louisiana State University.

A new species of frog of the genus Hylophorbus from New Guinea. Credit: Chris Austin, Louisiana State University.

Source: “New Species Found in Mysteriously Diverse Jungle: Louisiana State University’s Chris Austin describes his work studying the diversity of life on the island of New Guinea”

New species of catfish, Eutropiichthys britzi, is 166mm in length and is named after Museum scientist Ralf Britz. The fish comes from Myanmar in Southeast Asia. Credit: T. Britt Griswold/National Museum of Natural History, Smithsonian Institution.

Source: “Catfish named after Museum scientist”

Two field scientists from the University of Indonesia have found a new bird species, Zosterops Somadikartai or Togian white-eye, in the Togian Islands, Gulf of Tomini, Central Sulawesi province.

Photograph courtesy Mochamad Indrawan.

Sources: “New bird species found in Indonesia”; “New Bird Found in Indonesia”

Images of the floral banded wobbegong (top) and Dwarf spotted wobbegong. Courtesy of DoF.
Source: “Two shark species discovered”

A bird species not seen for 80 years has been rediscovered near Papua New Guinea. The Beck’s petrel (Pseudobulweria becki), long thought to be extinct, was photographed last summer by an Israeli ornithologist in the Bismarck Archipelago, a group of islands northeast of New Guinea.

Source: “Bird unseen for 80 years found”

And how about a dramatic 5th anniversary discovery’s photograph?

A new species of jellyfish, Big Red, Tiburonia granrojo, was discovered in 2003 by researchers from MBARI and from the Japanese Marine Science and Technology Center. This amazing jelly gets up to 1 meter in diameter and is found throughout the Pacific Ocean.

Source: “New Jellyfish Species Found”

ANTS HAVE ALGORITHMS: A Talk with Iain Couzin

From 3QuarksDaily:

Ants have algorithms. If you think about an ant colony, it's a computing device; there's some wonderful work by Jean-Louis Deneubourg in Brussels and his collaborators that really started this field in a way with Ilya Prigogine and later on Jean Louis Deneubourg looking at the ways in which social insect colonies can interact. One example would be—it sounds trivial, but if you think about it, it is quite difficult—how can a colony decide between two food sources, one of which is slightly closer than the other? Do they have to measure this? Do they have to perform these computations?

We now know that this is not the case. Chris Langton and other researchers have also investigated these properties, whereby individuals just by virtue of the fact that one food source is closer, even if they are searching more or less at random, have a higher probability of returning to the nest more quickly. Which means they lay more chemical trail, which the other ants tend to follow. You have this competition between these sources. You have an interaction between positive feedback, which is the amplification of information—that's the trail-laying behavior—and then you have negative feedback because of course if you just have positive feedback, there is no regulation, there is no homeostasis, you can't create these accurate decisions.

There's a negative feedback, which in this case is the decay of the pheromone, or the limited number of ants within the colony that you can recruit, and this delicate balance of positive and negative feedback allows the colony to collectively decide which source is closest and exploit that source, even though none of these individuals themselves have that knowledge.

More here.

What makes Mathematics so hard to learn?

In a recent essay, Artificial Intelligence guru Marvin Minsky explores problems in mathematics education. Minsky’s first distinction is between Arithmetic and Mathematics — grade schools emphasize the former, leaving grander concepts of Mathematics for later education. Minsky points out that if students are bored by Arithmetic, they may be turned off by math in general (that was certainly the case for me!).

Here’s a bit from Minsky’s essay:

Why do some children find Math hard to learn? I suspect that this is often caused by starting with the practice and drill of a bunch of skills called Arithmetic—and instead of promoting inventiveness, we focus on preventing mistakes. I suspect that this negative emphasis leads many children not only to dislike Arithmetic, but also later to become averse to everything else that smells of technology. It might even lead to a long-term distaste for the use of symbolic representations.

…

Anecdote: I asked a younger child “how much is 15 and 15″ and she quickly answered, “I think it’s 30.” I asked how she figured that out so fast and she replied, “Well, everyone knows that 16 and 16 is 32, and then I subtracted the extra 1’s.”

Traditional teacher: “Your answer is right but your method was wrong: you should add the two 5’s to make a 10; then write down a 0 and carry a 1, and then add it to the other two 1’s.” The traditional emphasis on accuracy leads to weakness of ability to make order-of-magnitude estimates—whereas this particular child already knew and could use enough powers of 2 to make approximations that rivaled some adult’s abilities. Why should children learn only “fixed-point” arithmetic, when “floating point” thinking is usually better for problems of everyday life! More generally, we need to find out more about how each child regards each subject. How might it answer questions like “What am I doing here, and why? “What can I expect to happen next?” “Where and when am I likely to use this?

What do you think? How did your Mathematics education affect you — do you love or hate math? How would you have changed your Mathematics education? Share your experience in the comments! Also check out the whole essay, and AI fans will dig Wikipedia’s page on Minsky himself.

via MentalFloss

Song-Learning Birds Shed Light on Our Ability to Speak

From 3Quarksdaily


A new study may have been for (and about) the birds, but it also hints at how humans may have developed the ability to speak, potentially paving the way to one day to identifying the causes of speech deficiencies. Duke University scientists report in PLoS ONE this week that they attempted to pinpoint regions of the brain responsible for vocal skills by studying three types of birds (parrots, hummingbirds, and songbirds) capable of picking up new songs and utterances as well as birds (zebra finches and ringed turtle doves) that lack the ability. Their findings: vocal pathways are always nestled in the same areas of the brain that control body movement.

“The vocal learning system is embedded within [an] ancient pathway'“ designed to handle motor function that, in birds, controls their wings and legs, says study co-author Erich Jarvis, an associate professor of neurobiology at Duke University. So how did some birds develop an ability to learn new sounds? Jarvis speculates that the ability evolved from motor function or, more specifically, that the original “wiring“ in the pathway linked to limbs may have duplicated and connected to vocal organs in these birds. He believes that human language pathways may have developed in a similar fashion, given that our ability to speak is based on controlling movements in the larynx (voice box).
More here.

Curious property of Prince Rupert's Drop glass

If you drop molten glass into a bucket of water, it will solidify into what's called a "Prince Rupert's Drop." According to this Corning video, the surface of the drop is in a state of great compression, while the interior is in a state of great tension. You can squeeze the bulbous part of the drop with pliers or bang on it with a hammer to no avail. However, if you snap off the hair-thin tail at the end of the drop, it'll shatter into dust. (Via boingboing)

Powerbocking Sifakas

Deja Vu Video From: Yesbutnobutyes

Posted by Miss Cellania on March 10, 2008.

I’ve seen videos of powerbocking for some time now, and they reminded me of something else. Yeah, they remind me of the stilts my dad made for me crossed with the pogo stick I got for Christmas when I was eight. But that’s not it. Powerbocks are spring-loaded stilts that attach to each foot. Something that Wile E. Coyote might order from ACME back in the day, but they are available from several sources now. No, that’s not what I was reminded of, either.

Oh, wait, now I know....

For best results, play both at once. The music from the first makes the second one better.

Learning to talk changes how we perceive color

A new British study suggests that our perception of color changes when we acquire language (and the ability to linguistically categorize colors):

"As an adult, color categorization is influenced by linguistic categories. It differs as the language differs," said Kay, who is renowned for his studies on the ways that different cultures classify colors. He cited recent research on the ability of Russian speakers to detect shades of blue [pdf] that English speakers classify as a single color.

How does the switch to a language-bound perception of color take place?

"That's the $64,000 question," said Kay. "We have every reason to believe that learning a language has a lot to do with it -- but [as for] how that works, it's early."

Link (via Kottke) (via Boing Boing)