Scientific Scribbles

The voice of UniMelb Science Communication students


Now, I realise that the title can be misconstrued as something really negative. Don’t take it too literally, I’m not going to talk about the time your parents told you Chubby the hamster ran away. What this post is about is instead the idea of teaching someone a technical or difficult concept by first feeding them a simplified version that is, hopefully, more easily understood. With experience, the person will later be introduced to the more advanced concept which will not seem as overwhelming due to the student already having some background knowledge. The elementary version is usually simple, concise and “wrong” in some way. As described in The Science of Discworld by Terry Pratchett, Ian Stewart and Jack Cohen:

“A lie-to-children is a statement that is false, but which nevertheless leads the child’s mind towards a more accurate explanation, one that the child will only be able to appreciate if it has been primed with the lie”.

Sometimes the teacher will actually note that the information is slightly inaccurate, but justify it by saying: “this isn’t exactly true, but is easier to understand than the real thing.”

Or to quote The Science of Discworld again:

“Yes, you needed to understand that” they are told, “so that now we can tell you why it isn’t exactly true

I know my Chemistry teacher in 10th grade said that when she was teaching us about the arrangement of electrons around the nucleus of an atom. I spent two years learning about how electrons moved in rings around the nucleus, sort of like planets orbiting around the sun. Then first year Chemistry taught me that all of that was a lie and that in reality, things are way more confusing. I’m sure most of you have a better grasp of the Schrödinger equation than I do, so I won’t go into detail about something that pretty much made my brain explode.

From this:

Electron shells around a Boron atom. Image licensed under creative commons via Wikimedia Commons

To this:Single electron orbitals. Image licensed under creative commons via Wikimedia Commons

These “lies-to-children” are an important aspect of education. They are not intended as deceptions but are simply easier to understand. As such, many commendations are due to “liars-to-children” (read: teachers) who prepare us for more sophisticated ideas that will no doubt continue to bombard us in the future.

So my questions to you are these: How do you feel when something you thought was a simple fact turns out to be untrue? Do you experience a period of denial as you struggle to incorporate this new information? Do you feel excited that science still has so much to teach us? Or do you simply feel annoyed that you’ve wasted time and effort learning something that has now been rendered “useless”?

the immunization debate- it is still on…. REALLY??

As a mother of a almost two year old, it is my unfortunate duty to take my child to be immunized. It is a horrible and daunting experience, but it must be done. Yet, I am coming to realize that for some reason a large proportion of mothers refuse to have their children immunized.
I recently joined several facebook mother support groups. In the last few months i have noticed many mothers asking questions about why we immunize our children, and why some people are against it. It seems to me a very large proportion of mothers just want to know what the debate is about, where to get ‘unbiased information’ and then make up their own mind.
As a scientist with a major in pharmacology and biochemistry I would like to think I have a good understanding of how immunisations work, why we have them done and the associated risks of having my child immunized.
Whenever I see a post questioning the ethics or reasons behind immunization, I tend to explain why we have them done, possible side effects and give links to government websites with more information.
I was astounded yesterday to see a mother had posted this ‘very informative fact sheet on what is actually in vaccines’

Misinformation- how are parents expected to really KNOW what is real!

To say I was astounded is a very large understatement!
This very biased piece of ‘information’ has tried to use science as a reason against immunisations. It claims many of the ingredients in vaccines are KNOWN carcinogens, that the genetically modified material contained in vaccines can induce unknown genetic mutations in the vaccine recipient.
The person who posted this image is not personally against immunizations, she thought that this information sheet was a factual account and that all mothers wanting to make an informed decision would benefit from knowing such information.
I explained in detail on the public forum how this image had manipulated their desire for factual information and provided misleading and false statements.  I provided links to scientific information for background reading if they really wanted to know the information- which none actually went on to read.
It seems to me that these mothers want factual information, yet they do not trust the information provided to them by their government or by scientists. The government has spent billions of dollars implementing the national immunization register and schedule, and even provides two tax free ‘bonus’ payments to parents whom have their children fully immunized by age 18months and 4 years.
I think that this growing group of woman want to be fully informed so they can make their own decisions. They are aware that the government does not provide explanations for both sides of the debate or directly provide information on the associated risks of immunizations (only a list of common side effects is available).

With the growth of social media, the radical american idealism of refusing immunisation is penetrating deeper and deeper into Australian society with no real opposition. The uninformed are becoming the misinformed, spreading further the misconceptions of the risks of vaccination. I think that a multi-media education program should be initiated, written for and delivered to the woman of Australia. The use of the internet should not be limited to fact sheets available on government websites; informative videos, posters, images and factsheet could be spread rapidly via social media. Informing parents of actual facts regarding immunizations is key to helping them make informed decisions.

Animals of War: Pneumatic Pup

In combat, troops will sometimes have to carry up to 50 kg of gear, and this can severely limit their effectiveness. So how might this burden be reduced or even eliminated?

Enter BigDog:

BigDog: The United States Army’s answer to Simpson’s Donkey.

This robot is designed to carry up to 150 kg, so the soldiers don’t have to. It is roughly 3 feet long, 2.5 feet tall, and weighs in at around 110 kg. Its designers, Boston Dynamics, have nicknamed the robot for its resemblance to our canine friends. If the video is anything to go by, you might say that the resemblance is uncanny.

BigDog is a dynamically-stabilised quadruped robot, equipped with around 50 sensors that measure things like the acceleration and angle of its body, the motion and force on its joints, and diagnostic information about its engine and computing hardware. It is powered by a 2-stroke, 1-cylinder go-kart engine, and controlled by a pretty powerful little computer. Using this equipment, BigDog can navigate rough terrain, maintain its balance when pushed over and can even regain control on icy surfaces – just like a real dog might.

You can read a summary paper of BigDog and its workings here.

But Boston Dynamics and DARPA weren’t happy to settle on their laurels with this one, and last year revealed a new, updated, and more frightening version of their 2005 creation. Its name? AlphaDog. Its other, more terminator-sounding name?

The Legged Squad Support System, or LS3.

AlphaDog: for carrying stuff and scaring you silly (Image Courtesy: DARPA)

Ultimately, the aim is to have a robot with the responsiveness of an animal and the carrying capacity of a mule. And they’re not far off.

AlphaDog‘s superior computing power allows it to autonomously make course corrections and follow a specific person or object. Just like a real dog, it can roll itself back over if it falls or is knocked down. To make it viable for extended missions in the field, DARPA is testing its ability to carry up to 180 kg over 32 km within 24 hours, all without the need for refuelling. Even a horse can typically only carry around 110 kg.

There are also plans to embue the thing with “hearing technology” so that soldiers can speak commands like ‘stop’, ‘sit’ and ‘come here’. Of course, its loud motor would be an impediment to its use in the field, but this shouldn’t be all that technically difficult to overcome considering DARPA’s budget.

It seems that AlphaDog is quickly shaping up to be man’s best friend (in a war, at least). And if it does nothing else, it’ll scare the bejeezus out of the enemy.

No Shrimp, when it comes to Sound

Sonic boom!

Most of us are somewhat familiar with the notion of a sonic boom. Those that have taken physics may be able to explain the phenomena through the example of a plane breaking the sound barrier. At supersonic speeds, lagging sound waves tend to bunch up and merge into a single shockwave forming a cone at the tip of the aircraft. This cumulative shockwave caries with it an enormous amount of sound energy, which we experience as a very loud crack or explosion as the aircraft flies overhead.

As loud as a sonic boom…

The rest of us non-physics folk (myself included) are probably satisfied to accept that a sonic boom is a very loud noise, with a very impressive form of generation. There is however an equivalently loud sound produced in nature, which I think results from an even more spectacular mechanism. Yet, the marine creature responsible is typically no larger than 5 cm. I am talking about the sound generated by the snapping shrimp (or pistol shrimp).

A Snapping Shrimp with it’s extraordinary claw. Image licensed under creative commons via Wikimedia Commons.

Communicating as part of a marine chorus…

Divers may experience this sound as part of a chorus of marine noise if they take the opportunity to momentarily hold their breath and listen to their surroundings when submerged. It’s often described as a background crackling or popping sound and can be heard vast distances away from the source of origin. Auditory signals are commonly used by a whole host of marine organisms to communicate. In some instances they may signal to larvae to help them identify the coastline or a favourable environment for development. There may also be benefits to living in groups, and thus signalling positional information might be important. Or it may convey a completely different message entirely. Despite their small size, snapping shrimp are amongst the loudest creatures in the sea, with only a few species of whale about to create a similar din!

Hunting with sound…

Concentrated sound energy produced by snapping shrimp is a highly effective weapon for hunting. Blasting small fish at close range can itself be lethal, but otherwise the shockwave is intended to stun prey providing an easy meal. It is even sufficient to crack the shell of crustaceans.

Sound production and Sonoluminescence…

This impressive sound is generated through the shrimp snapping shut it’s highly specialised claw which produces fast moving cavitation bubbles. As these bubbles collapse in on themselves, they not only generate sound waves well in excess of 200 dB (at very close range), but also the phenomena of  sonoluminescence. That is, for the briefest of instants (around 3 nano seconds) light is emitted (not visible to the naked eye) in association with the sound generated by the imploding bubbles. At this instant temperatures inside the bubbles can reach in excess of 4,700°C (around the same temperature as the sun!). Snapping shrimp are 1 of only 2 known cases in nature where sonoluminescence has been observed (also observed in the mantis shrimp).

Snapping shrimp can cause sonoluminescence through generating high speed cavitation bubbles.Image licensed under creative commons via Wikimedia Commons.

An impressive shrimp…

At very very close range the sound produced by the snapping shrimp is as loud as a sonic boom. It can stun or kill it’s prey when hunting and also plays an important role in communication. Perhaps even more remarkable than this tiny shrimp being able to produce such a loud sound is the associated phenomena of sonoluminescence.


PistolShrimp (Snapping shrimp) Video

Sound Generation in Snapping Shrimp Video

More information:

Lohse D, Schmitz B, Versluis M (2001) Snapping shrimp make flashing bubbles. Nature 413:477-478

Versluis M, Schmitz B, Von De Heydt A, Lohse D (2000) How Snapping Shrimp Snap: Through Cavitating Bubbles. Science 289: 2114-2117.

Turritopsis nutricula: The Immortal Jellyfish.

Being immortal would be amazing, right? Just ask Edward Cullen. Many people yearn to be young forever. They spend an inordinate amount of time and money on ridiculous treatments such as plastic surgery, botox or Horcruxes. However, unfortunately for most of us, immortality is utterly impossible.

That is, unless you are a member of the species Turritopsis nutricula, otherwise known as the Immortal Jellyfish. These guys are the only known organism to be classified as ‘biologically immortal’, and are fast becoming a little obsession of mine simply because they’re so unique!

The lifecycle of T. nutricula is actually quite similar to that of other metazoans. They begin as a fertilized egg that grows into a seslie poylup, which then undergoes metamorphous into an adult, sexually mature medusa. I’ve drawn a very simple diagram in case you are unfamiliar with this process.

Usually what happens next is that adult medusa reproduces and then dies.  But not in the case of T. nutricula! When the adult medusa becomes stressed, it life cycle swings into reverse. The medusa reverts back into a colonial polyp, escaping death and achieving potential immortality.

(I say potential immortality because there is of course the chance it may be eaten!)

But how does T. nutricula do this? What seems to happen is a sort of reverse metamorphosis. This involves a process called transdiffentication in which cells are converted from one state to another, as well as cell death. This eventually converts the medusa back into a polyup, which then reproduces asexually to release many more identical copies of itself into the ocean.

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