Wednesday 28 July 2010

Classic Science Videos

If you understand all the mathematical references in the following video, you're doing well. Enjoy the classic mathematical a capella (bet you thought you'd never read that sentence) Finite Simple Group (of Order Two).

If you think that dance is the best medium to portray protein synthesis, then the next video is for you. Made in 1971 by Robert Alan Weiss for the Department of Chemistry of Stanford University, this short film is narrated by Paul Berg, 1980 Nobel prize winner for Chemistry. It makes me wish I had taken science in the 70s - there is no other word than awesome to describe seeing 30s ribosome in the form of hippy interpretative dance. Gotta love the acid-trip music.

Wednesday 21 July 2010

Ep 132: Science of Superheroes - The Hulk

The science of superheroes is taking a green and nasty turn this week as we discuss the largest superhero of them all, The Hulk. Join myself and our regular superhero expert Dr Boob as we delve into the science of how we might realise The Hulk in the lab. It was one of the more entertaining interviews I have done for the podcast.

Listen in to this show here (or press play below), and read further for more info:

The Hulk is alter-ego of Dr Bruce Banner, who allegedly bares a striking resemblance to Dr Boob. Banner is a reserved physicist who involuntarily transforms into The Hulk when triggered by a strong emotion such as anger, fear, terror or grief. The Hulk himself is a massive green monster who gets stronger the angrier he gets. He also has bullet-proof skin.

The Hulk’s origin story includes depends on whether we are looking at the comic book Hulk, the Hulk of the two recent movies, or The Incredible Hulk of the TV series (in which it is David Banner, not Bruce Banner, who metamorphoses into The Hulk).

The 2003 movie version "Hulk" includes many of the topics we discuss in the podcast. The movie starts with genetics researcher David Banner – Bruce Banner’s father - working with the military to "improve" human DNA. The opening credit sequence depicts experiments with jellyfish and starfish DNA, and Banner’s notepad mentions bioluminescence. This suggests that the Hulk gets his green colour from jellyfish DNA as some jellyfish bioluminesce at around 450 nm, which is at the blue/green end of the spectrum. In 1961, Osamu Shimomura extracted green fluorescent protein and another bioluminescent protein, called aequorin, from Aequorea victoria while studying bioluminescence. He eventually received the Nobel prize in Chemistry in 2008 for this work. The mention of starfish is also interesting because, as we found with Wolverine, starfish and sea cucumbers have great healing powers and are able to regenerate lost limbs. Evidently, Banner wanted to splice bioluminescence and improved healing into human DNA.

Banner’s experiments then moved to lizards and monkeys, but unfortunately they all died. Naturally, he then decided if his experiments did not work on animals, he would try them on himself – clearly, ethics committees are not part of superhero science. After conducting experiments on his own DNA, he eventually passes on his mutant DNA to his unborn son Bruce. Once David realises this, he changes his approach and works to cure his son of his genetic afflictions, however the research is shut down and an explosion kills David’s wife. David is taken to a lunatic asylum and Bruce is adopted.

Years later, Bruce has followed his father’s line of work and is conducting military research – Bruce’s area of interest is the use of nanomeds in soldiers. This might include such things as targeted drug delivery for rapid recovery from injury. An experimental accident subjects Bruce to an enormous dose of gamma radiation which “activates” his mutant DNA (possibly combining with the nanomeds) and the building rage/stress transforms him into The Hulk for the first time.

Whether or not this is scientifically possible – well, that’s the topic of the podcast so tune in!

Other issues that we discuss include:
  • Gamma radiation and radiation poisoning;
  • Genetic transfer and gene therapy – could David Banner change his own DNA in such a way that this change would be copied to his progeny? For more information, check out the Weismann Barrier;
  • The Hulk’s size – is it possible to rapidly increase your size? Simple conservation of mass equations would suggest no, and bacteria in a Petri dish generally have a 24 hour doubling time. There are also enormous metabolic requirements involved – we need to have resources available to feed these growing cells and Bruce Banner is not excessively fat. Perhaps to do this we need to accelerate Bruce Banner to the near the speed of light, at which point he may relativistically pick up some mass - however, this is not particularly practical!
  • The Hulk’s strength – is it possible to rapidly increase your strength?
  • The Hulk's healing properties - could we use some of the science of Wolverine here?
  • The materials used to create bullet-proof skin. The toughest skins in the animal kingdom are crocodile, elephant, shark and armadillo; however none are bullet (and knife) proof;
  • What materials could we use to make his "one-size-fits-all" pants? You will notice that no matter what size Bruce Banner or The Hulk are, and no matter what the ripped state of his other clothes, his undies always fit.
  • And of course, whether The Hulk has irritable bowel syndrome and wears giant green snuggies.
    Hope you enjoy this show - we certainly enjoyed recording it, as you will be able to tell by the end! Listen in to this show here (or press play below):

    NB: I've now discovered there's a Red Hulk - future show perhaps?
    Samples in this podcast are broadcast courtesy of ioda PROMONET. They were:

    The Toxic Avenger
    "Superheros 2007" 
    from "Superheroes" 
    Buy at iTunes
    from "Little Baby Souls"
    Buy at iTunes
    Candye Kane
    from "Superhero"  
    Buy at iTunes
    Ninja Kodou
    "Superhero (Psychedelic Man)"
    from "Ninjutsu"  
    Buy at iTunes

    Shimomura, O., Johnson, F., & Saiga, Y. (1962). Extraction, Purification and Properties of Aequorin, a Bioluminescent Protein from the Luminous Hydromedusan,Aequorea Journal of Cellular and Comparative Physiology, 59 (3), 223-239 DOI: 10.1002/jcp.1030590302

    Moghimi, S. (2005). Nanomedicine: current status and future prospects The FASEB Journal, 19 (3), 311-330 DOI: 10.1096/fj.04-2747rev

    National Science Week 2010 Preview (oh, and vote for Marc!)

    Australian National Science Week is being held in 2010 between the 14th and 22nd August.

    One of the competitions being run for this year's festival is a hunt for Australia's best science blogger called The Big Blog Theory - and I am rather humbled to have made the shortlisted top 10. There are some top Australian science blogs in the list, and it will be a tough ask to gain more votes than the ABC and sceptic blogs (not climate sceptic, thank goodness...), so if you feel like voting and checking out the final 10, check out the comp website.

    Dan Keogh, one of the judges, put together this video on what he likes in science blogs.

    They are also looking for Australia's best microblogger. Shortlisted in this category is @brainsmatter who you may remember from our combined show on fictional scientists. The closest other contender (IMHO) in this category is @cbsquared_, who made this video we featured a few weeks back on climate change for the Australian current affairs program Q and A.

    There are a few cool events that I'll be looking out for during the week. Apart from the usual cavalcade of scientific fun and excellence, if you are in Melbourne check out the aforementioned @brainsmatter and his From Slime to Dinosaurs show at the Monash Science Centre. If you're not in Melbourne, you'll be able to watch it live online on the Brains Matter site.

    I'm also intrigued by the Big Sleep Survey 2010. People of all ages are invited to take part in the survey during Science Week, during which time they get online at the Sleep Survey website, answer questions about their sleep habits and fill in a week long sleep diary. As well as contributing to a real research project, each participant will find out their Sleep IQ (hmmm, sounds pretty pop-sciencey to me, although probably fun) and go into the draw for a prize. Check out the National Tour and Guests page for more info on the science week happenings.

    I'm very much looking forward to seeing Simon Pampena in what I guess you would describe as a humorous maths stage show called Planet of the Primes. Last year I saw Simon in Super Mega Maths Battle and it was one of the funniest things I've seen on stage, certainly on a "science" stage - although I'm pretty sure the kids in the audience didn't get the jokes! If you are near one of these shows, make sure you get along to see it, not only because it is maths communication (a particular passion of mine) but because it's very funny - well I presume it is, going on last year's show. Below is the video from last year's show - I'm not sure it does it justice, but you can sense the absurdity, which is right up my alley.

    I'll be at various Sydney shows, hope to see you there. And don't forget to vote!

    Sunday 11 July 2010

    The Science of Double Rainbows (OMG, what does this mean?)

    This post was chosen as an Editor's Selection for ResearchBlogging.orgThis question came in from @holabendez for Science Week. What causes a double rainbow? The question is inspired by, in my opinion, the best youtube video since Keyboard Cat met Hall and Oates. Check out the Double Rainbow video below - if I'm this happy for just one day in my life, it will have been a happy life:

    And now you'd better check out the Double Rainbow Song....

    Rainbows are the result of the reflection and refraction of light by water droplets. They can be seen when there are water droplets in the air in front of you and sunlight shining from behind you at a low angle. You can also see them when looking at a sprinkler or hose, and sometimes they are created by the moon. But before we jump into the optics involved, let's review some high school physics.

    White light and refraction:
    White light from the Sun is made up of all the various colours of visible light. Each of these colours has a different wavelength - red light (at one edge of the rainbow) has a wavelength of ~650 nm, whilst violet light (at the other edge) has a wavelength of ~400 nm.

    When light travels from one medium (say air) to another (water), it changes speed, and if the light enters at an angle, it will bend. This is known as refraction. Shorter wavelength light (such as violet) refracts more than longer wavelength light (such as red). You can see white light splitting into its constituent colours in the image to the right.

    NB: The Sun may not look white from here on Earth (it looks yellow), but if you were to observe it from space, it would look white. This is because the Earth's atmosphere scatters shorter wavelength light (like violet) more than longer wavelength light (red). See our story on the dust storm that turned Sydney red for more discussion of atmospheric scattering.

    Primary Rainbow:
    Rainbows result from a combination of reflection and refraction. The pictures below show the optics of how this works. The grey circles are water droplets. White light enters the droplet and is refracted, then reflected off the back of the droplet, before leaving the drop split into its constituent colours, again refracted. Some light will travel through the droplet - the reflection is not 100%. Red light leaves the droplet at a slightly higher angle than violet - this angle is independent of the size of the drop, but does depend on its refractive index. Seawater has a higher refractive index than rain water, so the radius of a rainbow in sea spray is smaller than a rainbow in the sky. The following picture shows the paths of red and violet light in the production of a rainbow - the other colours of a rainbow (for example green) travel somewhere between the two extremes.

    Primary Rainbow

    When you see a rainbow, you are seeing light that has been refracted and reflected through water droplets, however the red colour does not come from exactly the same droplets of water as the violet colour. If you were able to isolate one particular water drop that produced some of the red colour you saw, the violet light from this drop would not meet your eyes - it would travel over your head. The following picture shows that multiple water droplets contribute to the colours you see - this is why red is the top colour in the rainbow.

    Primary Rainbow View

    Secondary Rainbow:
    In the immortal words of the above youtube video, a double rainbow, Oh My God, what does this mean? It means interesting optics. A secondary rainbow is produced when there is one extra reflection of light within the water drop. As some light is lost each time it hits the edge of the drop, the secondary rainbow is fainter than the first. It appears higher in the sky because the light exits the drop at a larger angle (50-53 degrees) than the primary rainbow (40-42 degrees).

    Secondary Rainbow

    The colours in the secondary rainbow are in reversed order to the primary rainbow.

    Secondary Rainbow View

    The following picture shows how the rainbow appears in the sky with regards to the Sun and the observer. The same picture also makes sense for the secondary rainbow, however it would appear at a larger angle, and therefore could also appear later in the day when the Sun is higher in the sky - it would also have the colours reversed. If the Sun is higher than 42° (or 53° for the secondary), the rainbow is below the horizon and usually cannot be seen.


    The reason that the rainbow is circular is that this is the only shape that reflects the light back to your eyes at 42° (or 53°) - water droplets below and above (or to the left and right) of the rainbow do not reflect the light to your eyes. What this means is that everyone sees a different rainbow. If you are looking at a rainbow and walk to a new position, the light you see in the new spot will have been reflected by different water droplets to the light you saw in the first spot. This is also why there is no pot of gold at the end of the rainbow - there is actually no end of the rainbow. A rainbow does not actually exist at a particular location in the sky - it all depends on your location and the position of the Sun.

    It is possible to see a completely circular rainbow, but only if you are in a plane above the ground. In this case, you could look down and possibly see a rainbow whose centre is the shadow the plane. Climbing a mountain may not help you see a more complete rainbow as the mountain itself would cast a shadow, blocking the light which would cause the rainbow.

    So even though a "double rainbow all the way across the sky" may seem a mystical experience, it's really just physics!

    G., T. (1938). Descartes' Discourse on Method Nature, 141 (3574), 769-769 DOI: 10.1038/141769c0

    Tuesday 6 July 2010

    An egg in space - or an egg in a vacuum - what would happen?

    This is a question that has been bugging us at work.

    What would happen to a chicken egg in space? Equally interesting is the question what would happen to a chicken egg if placed in a vacuum chamber?

    Eggshells are able to withstand quite large forces from the outside because of their dome structure, but are not so strong from the inside. This makes sense - they need to be strong enough to withstand the force of the mother chook sitting on them, but need to be fragile enough from the inside for the baby chick to escape. If placed into a vacuum, would the pressure of the small amount of air inside the egg be enough to break the shell? Let's assume for the sake of argument that the egg was laid at normal atmospheric pressure.

    Other things to consider include temperature. Would the egg white and egg yolk freeze and therefore expand? This could break the shell. Is there enough empty space inside the egg into which the mainly water interior could expand? Or would this happen too suddenly? Is temperature actually a factor?

    Or perhaps a sudden change in pressure might cause the interior to rapidly boil, exploding the egg? Water only boils at 100 degrees at normal atmospheric pressure - the more you lower the pressure, the lower the temperature that water boils at. For instance, at the top of Mount Everest, the boiling point of water is 69 degrees. Human blood would boil in space except for the fact that our skin is strong enough to protect our blood from the rapid drop in pressure. Is an eggshell similarly strong, or is it too permeable?

    Is there a difference between the scenario where the egg is in space - let's say at about the Earth's orbit - and so is heated by the Sun (or at least half of it), and in a vacuum chamber where there is no heat source?

    As much as we like to ponder these questions, we don't have an answer. What do you think? Please feel free to speculate and throw ideas into the mix.

    For extra reading, check out the references for work conducted on hatching chickens in low gravity, and also hypergravity.

    SUDA, T., ABE, E., SHINKI, T., KATAGIRI, T., YAMAGUCHI, A., YOKOSE, S., YOSHIKI, S., HORIKAWA, H., COHEN, G., & YASUGI, S. (1994). The role of gravity in chick embryogenesis FEBS Letters, 340 (1-2), 34-38 DOI: 10.1016/0014-5793(94)80168-1

    Jones SM, Warren LE, Shukla R, Browning A, Fuller CA, & Jones TA (2000). The effects of hypergravity and substrate vibration on vestibular function in developing chickens. Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology, 7 (3), 31-44 PMID: 12124183