Everyone across the world in going through some crazy times right now. We all have to make decisions based on uncertain data, and as scientists that is extremely difficult. It's hard to know if you should do another experiment, or cull your animals humanely, or hibernate. For me, the important thing is to keep everyone as safe as possible, and to remember that we are all people behind our professional roles. It's a good reminder to be kind to those around you, to ask if you can buy groceries for your older neighbors, and to make all those phone calls that you were somehow too busy to make just a few weeks ago. Take care of each other, and stay safe.
By Karin
Everyone across the world in going through some crazy times right now. We all have to make decisions based on uncertain data, and as scientists that is extremely difficult. It's hard to know if you should do another experiment, or cull your animals humanely, or hibernate. For me, the important thing is to keep everyone as safe as possible, and to remember that we are all people behind our professional roles. It's a good reminder to be kind to those around you, to ask if you can buy groceries for your older neighbors, and to make all those phone calls that you were somehow too busy to make just a few weeks ago. Take care of each other, and stay safe.
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-By Richard
Exciting news for us: we are putting the finishing touches on a new rig in our lab that will allow us to do behavioral experiments with flies in tethered flight. The rig features an infrared camera recording at over 180fps, allowing us to monitor dynamic aspects of behaviour such as wingbeats and other body part movements. It's set up to allow stimulus display on up to three computer monitors, arrayed in a triangular arrangement around the mounted fly. Here are a few photos showing the rig, and a video of a fly flying while mounted inside the rig. Many thanks are due to Pavan Kaushik at NCBS, who has been very generously sharing his expertise, patiently guiding me over the past few months in collecting together all the components and setting up the supporting software! Thank you also to the staff in our Biomedical Engineering department for assembling the final rig, Sarah for sourcing bits and pieces from all over and improvising solutions when I got stuck, Joseph for the video and Yuri for setting up the flies. I am currently working hard on a paper on dragonfly flight control from my previous post-doc position. Since my mind is already on the topic of insect flight, I thought I would give a brief discussion on how insects fly, and why they are so amazing.
Insects were the first animals to fly through earths atmosphere, hitting the skies hundreds of millions of years before dinosaurs managed the same feat. Unlike planes, insects have not evolved jet engines that thrust themselves through the world at incredible speeds. Instead, insects must flap wings to generate forces strong enough to support their entire body weight. But what does this flapping achieve? If we take the traditional aerodynamic approaches that we use in planes and apply it to the body and wings of an insect, we predict that insects should not generate enough lift to fly. Misinterpretation of this finding has lead to the common misconception that scientists are baffled that insects can still fly. In reality, insects and aircraft rely on different mechanisms to generate lift, aircraft use stable aerodynamic flows while insects use unstable aerodynamic flows. Insect wings are normally relatively small compared to those of aircraft. This is because insects flap, and flapping wings requires muscles. The larger and heavier your wings are, the more muscles you need to flap them. This creates a positive feedback loop, where bigger wings need more muscle, which increases your weight, meaning you need to flap even harder to support the additional weight, which needs more muscle again, which increases your weight again, and so on…. Therefore insects are a good example of a flying machine optimised for generating maximum lift from the lightest, smallest wings available. And the solution for doing so, is to generate unstable aerodynamic flows. Lift is all about air pressure. If you can produce an air pressure differential between above and below your body, your body will be lifted accordingly. And the easiest way to produce an air pressure differential is to alter the speed that air is moving at. Fast moving air has a lower pressure than slow moving air, so wings are designed to speed up the flow of air passing across their top surface. Flapping insect wings utilise very specific movements and wing angles to generate what we call Vortices. A vortex is a circular airflow, and in this pattern the air speed is generally very high. If you can generate large, fast vortices on the upper surface of your wing, you will generate a large pressure differential, and a significant amount of lift. This is exactly what insects do, and it is the secret to them generating such incredible amounts of lift, using such tiny, lightweight wings. The paper that I am now working on is investigating the sensory neuroscience of how insects achieve and maintain these unstable airflows. If your flight relies on generating very specific air flow patterns, it makes sense to monitor air flow and react when it fails to perform as intended. We are trying to describe a novel air-flow sensing system on the wings of dragonflies, which performs this very role. Hopefully I will have more to show in the future! Joseph. Here is a video showing a view of a male hoverfly who is pursuing a black bead in an artificial arena. This video is produced based on Malin's 3D flight trajectory data. I struggled to understand the way to calculate movements of the fly and how the target should look like on its retina. Thanks to lots of mathematical lectures on YouTube. They helped me to understand and use the Rodoligues' formula for creating a rotation matrix to move the target position relative to the movement of the fly. My mathematical ability must be improved compared to when I was a high school student who failed a few exams. A new electrophysiology rig is also ready. I am quite excited to start my experiments with this stimuli.
A paper entitled 'The buzz around spatial resolving power and contrast sensitivity in the honeybee, Apis mellifera' is out in Vision Research. I carried out this project at Macquarie University with shark researchers. Laura did great work in bees, especially providing an excellent pun to the title.
https://authors.elsevier.com/a/1agXs9jMT%7EWyS |
Hoverfly Vision
The hoverfly vision group can be found at 2 locations: At Flinders University in Adelaide, Australia, and at Uppsala University in Sweden. Archives
January 2022
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