Posts Tagged ‘Natural’

Modelling catastrophic dam collapse and natural disasters

// June 24th, 2011 // Comments Off on Modelling catastrophic dam collapse and natural disasters // Recent Research, Science Communication

One of the biggest dams in the world, Geheyan Dam in China holds more water than five Sydney Harbour’s, a massive 3.12 billion cubic metres worth.

What would happen if it failed?

Models of Geheyan town before and after dam collapse

Australian CSIRO scientists collaborated with China’s Satellite Surveying & Mapping Application Centre (SASMAC) to model the region and apply six different dam failure scenarios.

“Our simulations show where the water would go, how fast it would reach important infrastructure such as power stations and the extent of inundation in major townships downstream,” said Dr Mahesh Prakash from CSIRO in the press release.

Dam failure is a real possibility, as many parts of China are prone to earthquakes. We’ve seen plenty of natural disasters over the past year, highlighting the need to prepare for such events.

Modelling and data visualisation can inform emergency procedure development and ensure new infrastructure is built protected areas.

“The modelling technique we developed for this work is really powerful,” Dr Prakash said. “It gives us very realistic water simulations including difficult-to-model behaviours such as wave motion, fragmentation and splashing.”

This video shows a dam failure simulation, and explains how the model was created. I enjoyed the delicious hundreds and thousands demonstration to show how water acts as a group of particles. Yummy!

The same software has been used to model other catastrophic events, including tsunamis and volcanoes. They also modeled the 1928 St Francis dam break in California. The simulation was very similar to the real event, suggesting the technique is accurate.

Science that’s only skin deep

// December 3rd, 2010 // 2 Comments » // How Things Work, Recent Research, Science Communication, Sex and Reproduction

I’m a guest blogger for the RiAus, and this post also appeared on their fancy website. To tell the truth, I really wanted to call this post “Hormonally Yours” in homage to the Shakespeare Sisters (anyone?) but I’ll save it for another post.

Recently I was in Arnhem Land, visiting some Indigenous communities with a couple of friends. While I was there, I got pretty jealous of everybody’s darker skin. “It’s so well suited for Australia,” one of my friends lamented. “I should be in Norway or something.”

Pale skin like mine is not great for Australia. I tan pretty easily, but only after being burned bright red. While I was in the NT I slathered sunscreen religiously, but still managed to get a highly embarrassing burn on my lower back when I was building a sandcastle (an epic sand turtle, actually. Totally worth it.)

Anyway, enough about me and my weirdly tanned lower back (it’s been months! Why won’t it go away?) Let’s talk about Nina Jablonski, an anthropologist. In 2000 she suggested a new reason why skin colour varies so much. It’s not an adaptation to protect against skin cancer and sunburn, like I always thought it was.

It’s real job is to keep us highly fertile by maintaining a delicate balance between two key vitamins: Vitamin D and Folic acid.

Pica's skin tone matched her UVB exposure like her scarf matched her dress. Image by Monja Con Patines

Vitamin D is obtained through some foods, but mostly from drinking in sunshine. UV light turns cholesterol into Vitamin D, which then goes to either your liver or kidneys to be converted to an active form.

Once active it helps white blood cells like macrophages kill bacteria, and helps control levels of calcium and phosphate – important for building healthy bones.

Deficiency in Vitamin D causes rickets, a disease resulting in soft, easily broken bones and deformity which can lead to early death.

So getting enough UV (specifically UVB light) is important to not dying, and therefore having reproductive success later in life. It’s been backed up by Yuen, A. (Vitamin D: In the evolution of human skin colour DOI: 10.1016/j.mehy.2009.08.007)

Natural selection favours soaking up UV.

Penny stayed under foliage at noon to protect her folic acid. Image by Monja Con Patines

Folic acid is obtained in leafy vegetables and fortified cereals. Rather than being made by UV, the light can destroy folic acid by literally breaking it apart. (Jablonski, N. The evolution of human skin coloration DOI: 10.1006/jhev.2000.0403)

Critical for DNA synthesis, folic acid is essential during pregnancy when a lot of new cells are being made.

Folic acid prevents against 70% of neural tube defects in embryos. Its destruction by UV is bad news.

Natural selection favours avoiding UV.

So there’s an ideal amount of UV light that needs to get through the skin – enough to produce Vitamin D, but not too much to destroy all the folic acid. Getting the balance right for the environment you’re in means higher fertility, which drives natural selection

This is what Nina Jablonski thinks caused the evolution of skin colour through the sepia spectrum we see today. Dark skin, with high melanin, stops more UV light. That’s exactly what you want if you live in a place with a lot of sun, like places near the equator. Light skin lets more UV in, which is great if you live somewhere overcast and not very high on UV.

Understanding how your skin colour (NOT your race) influences these two vitamins is important in being healthy. It’s more important now than ever, because we humans travel a LOT.

Sadly, Australia is pretty high in UV and I am pretty white. Thank god for sunscreen.

Things are rarely that simple though, and I imagine there’s a few different things going on that connect UV light to skin colour.

On Tuesday the RiAus is holding an event called Skin Deep: Exploring human ancestry. They’ll be showing a preview of a new SBS documentary about skin colour scientific research, as well as results from the Genographic Project. Basically they took DNA samples from a lot of volunteers and some national identities, and now they’re giving us the goss on who’s related to who’s secret love child.

I’ll be there, I’d love to see you (though seats are limited.) I’ll be the one tweeting in the corner. Follow me @CaptainSkellett

Would love to hear from anyone who took part in the Genographic Project, and anyone who didn’t. Who would you most like to be related to? For me it’s David Attenborough, then I can dream of inheriting his voice.

Ivy vs UV, could plant nanoparticles be the new sunscreen?

// July 21st, 2010 // Comments Off on Ivy vs UV, could plant nanoparticles be the new sunscreen? // How Things Work, Recent Research

English Ivy

Image by Tamara Horová

Research published in June shows that nanoparticles from the English Ivy might make superior sunscreen to current brands, offering high broad spectrum protection and lasting for longer than current creams.

The trend towards organics has influenced industries like food, coffee and shampoo as well as pretty much everything you can conceivably imagine. Over the past few years, some people have become worried about sunscreen containing nanosized titanium dioxide and zinc oxide. While these absorb light in the UV spectrum and protect the skin, perhaps the tiny particles could be absorbed through the skin and unleash toxic hell on the body! These could be unfounded fears, and damage from the sun is far more likely than damage from the sunscreen.

Personally, I’m all for synthetic chemicals. I think dear old Mother N has some freaky chemical concoctions of her own, many of which did not evolve to help humans but people inject it into their face anyway. Natural does not mean safe in my book.

All the same, ivy nanoparticles make a strong case. They absorbed or scattered light in the UV spectrum over five times better than titanium dioxide. The absorption dropped quickly when reaching the visible spectrum, so like current sunscreens it would look near invisible on your face.

Just like ivy can stick to brick walls and trees, the ivy nanoparticles have adhesive qualities. They could lead to sunscreens which last longer and are more water resistant. Hey, maybe that’s why Adam and Eve seem to always have ivy covering their-

Liked reading? There’s still time to vote for me in the Big Blog Theory, have a say in choosing Australia’s best science blog.

ResearchBlogging.orgXia, L., Lenaghan, S., Zhang, M., Zhang, Z., & Li, Q. (2010). Naturally occurring nanoparticles from English ivy: an alternative to metal-based nanoparticles for UV protection Journal of Nanobiotechnology, 8 (1) DOI: 10.1186/1477-3155-8-12

World’s sweetest antibiotic? The five ways honey kills bacteria.

// July 13th, 2010 // 5 Comments » // Drugs, How Things Work, Recent Research, Science at Home

HoneyYou’re at the doctors with a suspected infection, but instead of offering penicillin or erythromycin, they prescribe honey. Would you switch toast toppings? Take a honey pill? How about letting the doctor smear medical grade honey over the infected area?

People have been using honey (not mad honey) as medicine since ancient times, but until now we have never fully understood how it works. Research lead by Dr. Paulus Kwakman from the University of Amsterdam and his team have finally identified the key elements which give honey its antibacterial activity.

Bacteria are becoming resistant to drugs faster than we’re developing them. Honey might help because it works when other drugs don’t. Studies show it has good activity in vitro against antibiotic-resistant bacteria. An older study reports successful treatment of a chronic wound infections not responding to normal medicine.

So how does it work? It’s a combination of five factors.

1. Hydrogen peroxide, a kind of bleach. The honey enzyme called glucose oxidase makes hydrogen peroxide when honey is diluted with water. We clean toilets with bleach, and it’s pretty good at killing bacteria.

2. Sugar. Honey has so much sugar there’s hardly any water for bacteria to grow in.

3. Methylglyoxal (MGO), an antibacterial compound found in New Zealand Manuka honey a couple of years ago. It’s also found in medical grade honey which is made in controlled greenhouses, albeit in smaller amounts.

4. Bee defensin 1, a protein found in royal jelly (special food for queen bee larva.) This report is the first time bee defensin 1 has been identified in honey, and it works as an antibiotic.

5. Acid. Diluted honey has a pH of around 3.5, the acidic environment slows down bacterial growth.

These five things work together to provide a broad spectrum activity against bacteria. For example, S. aureus is vulnerable hydrogen peroxide, while B. subtillis is challenged only if MGO and bee defensin 1 are working simultaneously. Honey has the right mix for maximum destruction.

So that’s how bees keep their honey fresh and unspoiled by bacterial growth. Perhaps with this information we’ll create enhanced honey to guard against infection, improving on nature like we did with penicillin. Until then, I know what I’m having on my toast.

A Schooner of Science could be named Australia’s best science blog. If you enjoyed reading, please vote for me.

ResearchBlogging.orgKwakman, P., te Velde, A., de Boer, L., Speijer, D., Vandenbroucke-Grauls, C., & Zaat, S. (2010). How honey kills bacteria The FASEB Journal, 24 (7), 2576-2582 DOI: 10.1096/fj.09-150789

St Elmo’s Fire

// January 31st, 2010 // 5 Comments » // How Things Work

Some sailors regard it with fear and amazement, others see it as an omen of things to come, but when I see St Elmo’s Fire burning on the masts above I am struck with curiousity for this most bizarre natural phenomenon.

St Elmo’s Fire appears as a blueish glow gracing the tips of masts and other pointy objects (lightning rods, swords, staffs, unusually long noses) during thunderstorms. You may have heard of it before, it’s been mentioned in such classics as Tintin in Tibet, Terry Pratchett’s Nation, and Moby Dick.

Despite the name, it’s not fire. It’s actually plasma, just like lightning – except instead of travelling from a cloud to the ground it just… well.. glows. It works a bit like neon lights do – energy from stormy weather (rather than a powerpoint) collect on an object and discharge. When the discharge is strong enough, it ionises gasses in the air which makes them glow. It mostly happens on pointy objects because electric fields are strongest on curves – the curvier the object, the stronger the field.

The colour is blue simply because oxygen and nitrogen glow blue when they ionise (how’s that for a circular argument? I’m sure it’s got more to do with molecular spectroscopy *shudder* more than I want to go into tonight, but if you’re curious drop me a comment.) If our air was full of neon it would be all orange, and how cool would that be?!

St Elmo’s Fire was originally named for St Erasmus – the patron saint of sailors – but whoever came up with the name should get a prize because it sounds great. Off the top of my head I can think of three fantastic things which have stolen the name. It was the title of one of the Teen Power Inc books of my childhood. As a teenager I saw the awesome 80’s movie about the twenty-somethings who tackle life and relationships after leaving college. And lately I have been listening to the old song by John Parr… I can never pick up the words except for the titular line “in St Elmo’s Fi-yar!”… I have no idea what it means in this context but for some reason (probably the science) it really resonates with me. Click through to the lyrics.

I can see a new horizon
Underneath the blazin’ sky
I’ll be where the eagle’s
Flyin’ higher and higher
Gonna be your man in motion
All I need is a pair of wheels
Take me where my future’s lyin’
St. Elmo’s Fire

Ohhhhh YEAH! St Elmo’s Fi-yah!






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