Tuesday, April 18, 2017
The Society of Women Engineers (SWE)'s has the SWENext program , which offers great resources and outreach for students through the age of 18. They hold engineering events designed for girls, provide scholarships, hold events to meet women engineers, have cool engineering projects, and great contests.
One of their newer outreach endeavors is "Constance and Nano Engineering Adventure!" This is a comic book about friends Constance and Nano and their engineering adventures, solving problems with science, engineering, technology and math! You can even download the first issue for free HERE.
Posted by Melissa Chernick at 4/18/2017
Wednesday, April 12, 2017
|Image credit: Thomas Shahan|
Robber flies (Asilidae family) are not your typical house flies. They are small, predatory insects that feed on a vast array of other arthropods. While they are small in size (10 times smaller than a dragonfly), these guys are serious hunters. For example, Mallophora omboides is known as the “Florida bee killer” for its taste for honey bees. Other robber flies hunt down wasps, dragonflies, spiders, or grasshoppers, just to name a few. Perhaps almost as impressive as the types of prey is how they are subdued. Typically, robber flies will perch out in an open sunny place and wait, seizing their prey in flight and injecting it with neurotoxic or proteolytic enzymes that both immobilizes it and liquefies its insides.
A recent study in Current Biology took a closer look at the robber fly’s “aerial attack strategy.” The authors focused on the genus Holcocephala, a group native to the Americas. Let’s start by going over something you know about but probably never realized had an actual term: constant bearing angle (CBA) strategy. Initially, I tried to describe this just using text, but it is really best visualized with the help of a supplemental graphic from the paper.
The study considered whether the flies were using this CBA strategy to catch their prey. To do this, the researchers went out to a field and hung up a big white sheet as a backdrop for their high-speed video cameras. Next, they set up their “fly teaser,” a custom made plastic frame that housed a stepper motor and several pulleys to move taut fishing line. This allowed for precise, computer controlled movements of the beads they attached to the fishing line. When a robber fly perched on a blade of grass in their study area, they “teased” it with a bead (a.k.a. dummy prey item for the fly). They included several variations including bead size and direction. They recorded the fly with two synchronized cameras running at 1000 fps to get a 3D view of the attack. For each attack video, they analyzed the frame at which the flies started to take off and until it began a terminal deceleration on final approach of the target. Then: measure, measure, measure, math, math, math.
They found that the flies were fairly consistent with the CBA model. If they decelerated or reversed the bead during the attack, the robber flies compensated, actively keeping the range vectors parallel. One unexpected finding occurred in cases where the bead moved in front of the fly and it took off with a head-on collision course. They found that the fly still intercepted the bead while flying at a backward angle, meaning that the latter part of its trajectory was distinctly curved. When they took a closer look, the found the results to reflect a “lock-on” process “during which the fly has a new heading and the speed is fixed to a value slightly higher than that of the prey.” This lock-on strategy has not been described in any other flying animal. The flies were able to compensate for unexpected changes in the target’s velocity and uncertainties in the location, size, and speed of the target.
|Adapted from paper's graphical abstract|
Interested in more details? Here’s a video summary put together by the researchers:
Wardill, T., Fabian, S., Pettigrew, A., Stavenga, D., Nordström, K., & Gonzalez-Bellido, P. (2017). A Novel Interception Strategy in a Miniature Robber Fly with Extreme Visual Acuity Current Biology, 27 (6), 854-859 DOI: 10.1016/j.cub.2017.01.050
Read more about robber flies at University of Florida's Featured Creatures page.
Wednesday, April 5, 2017
Lately I've been catching up on The Weekly Space Hangout podcast. A few weeks ago, they featured an interview with Dan Dixon, a developer of Universe Sandbox. This is an incredibly cool, scientifically accurate, interactive space and gravity game/simulator.
"Create and destroy on an unimaginable scale... with a space simulator that merges real-time gravity, climate, collision, and material interactions to reveal the beauty of our universe and the fragility of our planet."
Want to add a moon or two to a solar system and see how those moons will be ripped apart by a planet? How about seeing what happens when you fling planets into or out of a solar system? What about modeling Earth's climate, watching sea ice grow and recede based on the planets tilt? Oh! And go ahead and terraform Mars while you are tinkering with climates. The scenarios of creation and destruction you can do are endless!
Perhaps most importantly, it uses real science, real physics. And it runs on your home computer. The latest version even has VR mode. It only costs $24.99 (USD), which, for a video game of this complexity is pretty good.
Check it out:
|A moon colliding with Earth.|
|Orbiting bodies and their trails colored by their velocity.|
|A supernova within our solar system.|
|Neptune pulling apart Saturn's rings.|
All images from Universe Sandbox.
Posted by Melissa Chernick at 4/05/2017